U.S. GOVERNMENT PRINTING OFFICE

68–501 WASHINGTON : 2011

112th Congress, 1st Session – – – – – – – – – – – – – House Document 112–43 

RECOMMENDATIONS FOR THE IMPLEMENTATION OF 

FOUR PROJECTS 

COMMUNICATION

FROM

THE ASSISTANT SECRETARY OF THE ARMY, 

CIVIL WORKS, THE DEPARTMENT OF DEFENSE

TRANSMITTING

RECOMMENDATIONS FOR THE IMPLEMENTATION OF FOUR 

PROJECTS BY THE SECRETARY OF THE ARMY 

VOLUME VI OF VI 

JULY 12, 2011.—Referred to the Committee on Transportation and 

Infrastructure and ordered to be printed 

2:45 Sep 29 2011 Jkt 068501 PO 00000 Frm 00003 Fmt 4012 Sfmt 4012 E:\HR\OC\HD043V6 XXX HD043V6

LOUISIANA COASTAL AREA (LCA)

ECOSYSTEM RESTORATION STUDY

Volume VI of VI

Final Integrated Feasibility Study and

Supplemental Environmental Impact Statement

for the

Medium Diversion at White Ditch

Plaquemines Parish Louisiana

September 2010

U.S. Army Corps of Engineers Coastal Protection and

New Orleans District Restoration Authority (1)

LOUISIANA COASTAL AREA (LCA)

ECOSYSTEM RESTORATION STUDY

Volume VI of VI

Final Integrated Feasibility Study and

Supplemental Environmental Impact Statement

for the

Medium Diversion at White Ditch

Plaquemines Parish Louisiana

The responsible lead Federal agency for this study is the U.S. Army Corps of

Engineers  Mississippi Valley, New Orleans District (CEMVN). The non-Federal

sponsor for the study is Coastal Protection and Restoration Authority (CPRA). This

report is a combined feasibility report and environmental impact statement complying

with requirements of the U.S. Army Corps of Engineers (USACE) and the Council of

Environmental Quality (CEQ), and is intended to reduce duplication and paperwork.

An asterisk (*) in the table of contents notes paragraphs that are required for National

Environmental Policy Act (NEPA) compliance.

September 2010

U.S. Army Corps of Engineers Coastal Protection and

New Orleans District Restoration Authority

3
This report contains six volumes.

You are at Volume VI, which is the Medium Diversion at White Ditch Final Integrated

Feasibility Study Report and Supplemental Environmental Impact Statement.

Volume I: Summary

Volume II: Amite River Diversion Canal Modification

Volume III: Convey Atchafalaya to Northern Terrebonne Marshes /

Multipurpose Operation of the Houma Navigation Lock

Volume IV: Small Diversion at Convent / Blind River

Volume V: Terrebonne Basin Barrier Shoreline Restoration

Volume VI: Medium Diversion at White Ditch

If you have any questions, or require additional information, please contact:

Mr. Timothy Axtman, Senior Plan Formulator

U.S. Army Corps of Engineers New Orleans District;

P.O. Box 60267, New Orleans, LA 70160-0267

(504) 862-1921, email: Timothy.J.Axtman@usace.army.mil

4
Final Integrated A-1 September 2010

Feasibility Study / SEIS

FINAL

INTEGRATED FEASIBILITY STUDY AND

SUPPLEMENTAL ENVIRONMENTAL IMPACT STATEMENT

Louisiana Coastal Area (LCA), Louisiana

Medium Diversion at White Ditch

Plaquemines Parish, Louisiana

LEAD AGENCY: U.S. Army Corps of Engineers (USACE) - Mississippi Valley Division, New Orleans

District (District).

ABSTRACT: Four of 12 alternative plans were considered in detail: Alternative 1 would implement a 5,000

cubic feet per second (cfs) maximum diversion and outfall management features; Alternative 2 would

implement a 10,000 cfs maximum diversion; Alternative 3 would implement a 15,000 cfs maximum diversion.

Alternative 4 is the Recommended Plan and would implement a 35,000 cubic feet per second maximum

diversion with associated outfall management features. This project would provide a source of river sediment,

freshwater and nutrients to the River aux Chenes subbasin and other nearby portions of the upper Breton Sound

Basin, to restore and protect marsh soils and vegetation and maintain a functional salinity regime. The project

would be expected to benefit approximately 98,000 acres of wildlife and fisheries habitat in this portion of the

Breton Sound Basin. The fully funded cost of the Recommended Plan is estimated to be $387,620,000.

Currently, the annual operation, maintenance, repair, replacement, and rehabilitation (OMRR&R) costs are

estimated at $1,467,836. OMRR&R costs are the responsibility of the non-Federal sponsor. These costs can be

found in Tables 3.15 and 3.16 of the main report. Information presented in the LCA Main Report, Final

Programmatic Environmental Impact Statement (EIS), and supporting volumes and appendices are incorporated

by reference in this Final Integrated Feasibility Study with Supplemental EIS.

Comments: Please send comments or questions on this Final Supplemental Environmental Impact Statement

(SEIS) to the U.S. Army Corps of Engineers, New Orleans District, Attention: Andrew D. MacInnes, P.O. Box

60267, New Orleans, LA 70160-0267. Telephone: (504) 862-1062; Fax (504) 862-1892. The official Closing

Date before Federal Action can occur on this project will be 30 days from the date on which the Notice of

Availability of this Final Integrated Feasibility/SEIS appeared in the Federal Register.

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Project Photographs of the White Ditch Study Area

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Feasibility Study / SEIS

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Final Integrated iii September 2010

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Contents1

Page

Abstract ......................................................................................................................................................A-1

List of Figures........................................................................................................................................... xxvii

List of Tables........................................................................................................................................... xxviii

Executive Summary ................................................................................................................................ ES-1

1.0 STUDY INFORMATION ........................................................................................................................... 1-1

1.1 STUDY AUTHORITY........................................................................................................................ 1-1

1.2 PURPOSE AND SCOPE.................................................................................................................. 1-2

1.3 STUDY AREA.................................................................................................................................... 1-3

1.4 HISTORY OF INVESTIGATION ...................................................................................................... 1-4

1.5 PRIOR REPORTS AND EXISTING PROJECTS ........................................................................... 1-4

1.5.1 Federal .............................................................................................................................. 1-4

1.5.2 State .................................................................................................................................. 1-9

1.5.3 Local................................................................................................................................ 1-10

1.6 PLANNING PROCESS AND REPORT ORGANIZATION........................................................... 1-14

1.7 USACE CAMPAIGN PLAN............................................................................................................. 1-19

2.0 NEED FOR AND OBJECTIVES OF ACTION ........................................................................................ 2-1

2.1 NATIONAL OBJECTIVES ................................................................................................................ 2-1

2.2 SIGNIFICANCE OF THE MDWD PROJECT AREA ...................................................................... 2-1

2.3 PUBLIC CONCERNS ....................................................................................................................... 2-3

2.4 PROBLEMS, NEEDS, AND OPPORTUNITIES ............................................................................. 2-4

2.4.1 General Problem Statement ............................................................................................ 2-4

2.4.2 Study Area Opportunities................................................................................................. 2-6

2.4.3 Desired Future Conditions ............................................................................................... 2-7

2.5 PLANNING OBJECTIVES................................................................................................................ 2-7

2.5.1 Goals and Objectives ....................................................................................................... 2-8

2.6 PLANNING CONSTRAINTS ............................................................................................................ 2-9

3.0 ALTERNATIVES....................................................................................................................................... 3-1

3.1 PLAN FORMULATION RATIONALE............................................................................................... 3-1

3.1.1 Plan Formulation Rationale.............................................................................................. 3-1

3.1.2 Plan Formulation Criteria.................................................................................................. 3-1

3.1.2.1 Completeness............................................................................................ 3-1

3.1.2.2 Effectiveness.............................................................................................. 3-1

3.1.2.3 Efficiency.................................................................................................... 3-1

3.1.2.4 Acceptability............................................................................................... 3-1

3.1.3 Environmental Operating Principles................................................................................ 3-1

3.1.4 White Ditch Study Area Land Loss.................................................................................. 3-2

3.1.5 Future Study Area Loss Rates......................................................................................... 3-4

3.2 MANAGEMENT MEASURES.......................................................................................................... 3-7

3.2.1 Value Engineering Study.................................................................................................. 3-7

3.2.2 Development of Management Measures........................................................................ 3-8

1 An asterisk (*) denotes paragraphs that are required for National Environmental Policy Act (NEPA) compliance.

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3.2.3 Description of Management Measures ........................................................................... 3-9

3.2.3.1 Freshwater Supply................................................................................... 3-10

3.2.3.2 Hydraulic Distribution............................................................................... 3-10

3.2.3.3 Sediment Supply and Distribution........................................................... 3-10

3.2.3.4 Protection (Existing Marshes)................................................................. 3-11

3.2.3.5 Invasive Species Management............................................................... 3-11

3.2.3.6 Freshwater Supply................................................................................... 3-11

3.2.3.7 Hydraulic Distribution............................................................................... 3-12

3.2.3.8 Sediment Supply and Distribution........................................................... 3-13

3.2.3.9 Protection (Existing Marshes)................................................................. 3-13

3.2.3.10 Invasive Species Management............................................................... 3-15

3.2.4 Screening / Evaluation of Alternative Plans .................................................................. 3-15

3.2.5 Alternative Plans not Carried Forward for Further Analysis......................................... 3-16

3.3 PRELIMINARY ALTERNATIVE PLANS........................................................................................ 3-18

3.3.1 Development of Alternative Plans ................................................................................. 3-18

3.3.2 Location for Diversion Structure(s) ................................................................................ 3-21

3.3.3 Description of Alternative Plans..................................................................................... 3-27

3.3.4 Screening / Evaluation of Alternative Plans .................................................................. 3-29

3.3.4.1 The ERDC-SAND2 Model ...................................................................... 3-29

3.3.4.2 CE/IC Analysis......................................................................................... 3-33

3.3.5 Alternative Plans not Carried for Further Analysis........................................................ 3-34

3.4 FINAL ARRAY OF ALTERNATIVES ............................................................................................. 3-35

3.4.1 No Action (Future Without Project Conditions)............................................................. 3-35

3.4.2 Alternative 1 – 5,000 cfs diversion................................................................................. 3-38

3.4.3 Alternative 2 – 10,000 cfs Max Diversion...................................................................... 3-40

3.4.4 Alternative 3 – 15,000 cfs Max Diversion...................................................................... 3-40

3.4.5 Alternative 4 – 35,000 cfs Max Diversion (Recommended Plan)................................ 3-43

3.5 COMPARISON OF ALTERNATIVE PLANS................................................................................. 3-43

3.5.1 Incremental Cost/Cost Effectiveness Analysis Process............................................... 3-43

3.5.2 Wetland Value Assessment (WVA)............................................................................... 3-45

3.5.3 Results of the Incremental Cost/Cost Effectiveness Analysis...................................... 3-50

3.5.4 Other Factors.................................................................................................................. 3-52

3.5.4.1 Recreational Benefits .............................................................................. 3-52

3.5.4.2 Desired Future Condition ........................................................................ 3-53

3.5.4.3 Relative Sea Level Rise .......................................................................... 3-54

3.5.4.4 Breton Sound Benefits ............................................................................ 3-55

3.5.4.5 Adaptive Management ............................................................................ 3-55

3.5.4.6 Acceptability, Completeness, Effectiveness, and Efficiency. ................ 3-56

3.5.4.7 Selection of the Recommended Plan..................................................... 3-56

3.6 NER PLAN....................................................................................................................................... 3-56

3.7 PLAN SELECTION – RECOMMENDED PLAN............................................................................ 3-58

3.7.1 Budget and Reauthorization .......................................................................................... 3-58

3.7.2 Components ................................................................................................................... 3-58

3.7.3 Design, Environmental, and Construction Considerations........................................... 3-59

3.7.4 Real Estate Requirements............................................................................................. 3-60

3.7.5 Operations and Maintenance Considerations .............................................................. 3-60

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3.7.6 Monitoring Plan and Adaptive Management................................................................. 3-61

3.7.7 Effectiveness of Recommended Plan in Meeting Goals and Objectives.................... 3-64

3.7.8 Effectiveness of Recommended Plan in Meeting Environmental Operating

Principles......................................................................................................................... 3-65

3.7.9 Compensatory Mitigation Measures.............................................................................. 3-65

3.8 RISK AND UNCERTAINTY............................................................................................................ 3-65

3.8.1 Induced Shoaling............................................................................................................ 3-65

3.8.2 Relative Sea Level Rise................................................................................................. 3-66

3.8.3 ERDC-SAND2 Model Background................................................................................ 3-66

3.8.4 Real Estate...................................................................................................................... 3-67

3.8.5 Sediment Modeling......................................................................................................... 3-67

3.8.6 Reauthorization............................................................................................................... 3-68

3.8.7 Other Diversions............................................................................................................. 3-68

3.8.8 Water Quality .................................................................................................................. 3-69

3.8.9 Fisheries.......................................................................................................................... 3-69

3.9 IMPLEMENTATION REQUIREMENTS ........................................................................................ 3-69

3.9.1 Milestone Schedule........................................................................................................ 3-69

3.9.2 Implementation Responsibilities .................................................................................... 3-70

3.9.3 Cost Sharing ................................................................................................................... 3-72

3.9.4 Environmental Commitments ........................................................................................ 3-73

3.9.5 Financial Requirements ................................................................................................. 3-75

3.9.5.1 Sponsorship Agreement.......................................................................... 3-75

3.9.5.2 Financial Requirements........................................................................... 3-76

3.9.5.3 Local Cooperation.................................................................................... 3-76

3.9.5.4 Project Management Plan....................................................................... 3-76

3.9.5.5 Procedures for Project Implementation.................................................. 3-76

3.9.6 Views of Non-Federal Sponsor...................................................................................... 3-78

4.0 AFFECTED ENVIRONMENT................................................................................................................... 4-1

4.1 ENVIRONMENTAL SETTING OF STUDY AREA.......................................................................... 4-1

4.1.1 Location............................................................................................................................. 4-1

4.1.2 Climate .............................................................................................................................. 4-1

4.1.3 Geomorphic and Physiographic Setting.......................................................................... 4-2

4.2 SIGNIFICANT RESOURCES........................................................................................................... 4-2

4.2.1 Soils and Waterbottoms................................................................................................... 4-2

4.2.1.1 Soils and Waterbottoms............................................................................ 4-3

4.2.1.1.1 Historic Conditions ........................................................... 4-3

4.2.1.1.2 Existing Conditions........................................................... 4-3

4.2.2 Hydrology.......................................................................................................................... 4-3

4.2.2.1 Flow and Water Levels.............................................................................. 4-3

4.2.2.1.1 Historic Conditions ........................................................... 4-3

4.2.2.1.2 Existing Conditions........................................................... 4-4

4.2.2.2 Sedimentation and Erosion....................................................................... 4-4

4.2.2.2.1 Historic Conditions ........................................................... 4-4

4.2.2.2.2 Existing Conditions........................................................... 4-5

4.2.2.3 Water Use and Supply .............................................................................. 4-5

4.2.2.3.1 Historic Conditions ........................................................... 4-5

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4.2.2.3.2 Existing Conditions........................................................... 4-6

4.2.2.4 Groundwater .............................................................................................. 4-6

4.2.2.4.1 Historic Conditions ........................................................... 4-6

4.2.2.4.2 Existing Conditions........................................................... 4-6

4.2.3 Water Quality and Salinity................................................................................................ 4-6

4.2.3.1 Historic Conditions..................................................................................... 4-6

4.2.3.2 Existing Conditions .................................................................................... 4-6

4.2.4 Air Quality.......................................................................................................................... 4-8

4.2.4.1 Historic Conditions..................................................................................... 4-8

4.2.4.2 Existing Conditions .................................................................................... 4-8

4.2.5 Noise ............................................................................................................................... 4-11

4.2.5.1 Historic Conditions................................................................................... 4-11

4.2.5.2 Existing Conditions .................................................................................. 4-11

4.2.6 Vegetation Resources.................................................................................................... 4-11

4.2.6.1 Riparian Vegetation................................................................................. 4-12

4.2.6.1.1 Historic Conditions ......................................................... 4-12

4.2.6.1.2 Existing Conditions......................................................... 4-12

4.2.6.2 Wetland Vegetation ................................................................................. 4-13

4.2.6.2.1 Historic Conditions ......................................................... 4-13

4.2.6.2.2 Existing Conditions......................................................... 4-13

4.2.6.3 Upland Vegetation................................................................................... 4-16

4.2.6.3.1 Historic Conditions ......................................................... 4-16

4.2.6.3.2 Existing Conditions......................................................... 4-16

4.2.6.4 Submerged Aquatic Vegetation (SAV)................................................... 4-16

4.2.6.4.1 Historic Conditions ......................................................... 4-16

4.2.6.4.2 Existing Conditions......................................................... 4-16

4.2.6.5 Invasive Species – Vegetation................................................................ 4-17

4.2.6.5.1 Historic Conditions ......................................................... 4-17

4.2.6.5.2 Existing Conditions......................................................... 4-17

4.2.7 Wildlife and Habitat......................................................................................................... 4-17

4.2.7.1 Historic Conditions................................................................................... 4-17

4.2.7.2 Existing Conditions .................................................................................. 4-18

4.2.8 Aquatic Resources ......................................................................................................... 4-19

4.2.8.1 Historic Conditions................................................................................... 4-19

4.2.8.2 Existing Conditions .................................................................................. 4-19

4.2.9 Fisheries.......................................................................................................................... 4-20

4.2.9.1 Historic Conditions................................................................................... 4-20

4.2.9.2 Existing Conditions .................................................................................. 4-20

4.2.10 Essential Fish Habitat (EFH).......................................................................................... 4-21

4.2.10.1 Historic Conditions................................................................................... 4-21

4.2.10.2 Existing Conditions .................................................................................. 4-22

4.2.11 Threatened and Endangered Species .......................................................................... 4-23

4.2.11.1 Historic Conditions................................................................................... 4-23

4.2.11.2 Existing Conditions .................................................................................. 4-23

4.2.12 Cultural and Historic Resources .................................................................................... 4-25

4.2.12.1 Historic Conditions................................................................................... 4-25

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4.2.12.2 Existing Conditions .................................................................................. 4-25

4.2.13 Aesthetics........................................................................................................................ 4-25

4.2.13.1 Historic Conditions................................................................................... 4-25

4.2.13.2 Existing Conditions .................................................................................. 4-26

4.2.14 Recreational Resources................................................................................................. 4-26

4.2.14.1 Historic Conditions................................................................................... 4-26

4.2.14.2 Existing Conditions .................................................................................. 4-27

4.2.15 Socioeconomics and Human Resources...................................................................... 4-28

4.2.15.1 Population and Housing.......................................................................... 4-30

4.2.15.1.1 Historic Conditions ......................................................... 4-30

4.2.15.1.2 Existing Conditions......................................................... 4-30

4.2.15.2 Employment, Business, and Industrial Activity ...................................... 4-30

4.2.15.2.1 Historic Conditions ......................................................... 4-30

4.2.15.2.2 Existing Conditions......................................................... 4-31

4.2.15.3 Community Cohesion.............................................................................. 4-31

4.2.15.3.1 Historic Conditions ......................................................... 4-31

4.2.15.3.2 Existing Conditions......................................................... 4-32

4.2.15.4 Environmental Justice ............................................................................. 4-32

4.2.15.4.1 Historic Conditions ......................................................... 4-33

4.2.15.4.2 Existing Conditions......................................................... 4-34

4.2.15.5 Infrastructure............................................................................................ 4-34

4.2.15.5.1 Historic Conditions ......................................................... 4-34

4.2.15.5.2 Existing Conditions......................................................... 4-34

4.2.15.6 Business and Industry............................................................................. 4-34

4.2.15.6.1 Historic Conditions ......................................................... 4-34

4.2.15.6.2 Existing Conditions......................................................... 4-35

4.2.15.7 Traffic and Transportation ....................................................................... 4-35

4.2.15.7.1 Historic Conditions ......................................................... 4-35

4.2.15.7.2 Existing Conditions......................................................... 4-35

4.2.15.8 Public Facilities and Services.................................................................. 4-35

4.2.15.8.1 Historic Conditions ......................................................... 4-35

4.2.15.8.2 Existing Conditions......................................................... 4-35

4.2.15.9 Tax Revenues and Property Values....................................................... 4-36

4.2.15.9.1 Historic Conditions ......................................................... 4-36

4.2.15.9.2 Existing Conditions......................................................... 4-36

4.2.15.10 Community and Regional Growth........................................................... 4-36

4.2.15.10.1 Historic Conditions ......................................................... 4-36

4.2.15.10.2 Existing Conditions......................................................... 4-36

4.2.15.11 Land Use Socioeconomics ..................................................................... 4-37

4.2.15.11.1 Agriculture ...................................................................... 4-37

4.2.15.11.2 Forestry........................................................................... 4-37

4.2.15.11.3 Public Lands................................................................... 4-37

4.2.15.12 Water Use and Supply ............................................................................ 4-38

4.2.15.12.1 Historic Conditions ......................................................... 4-38

4.2.15.12.2 Existing Conditions......................................................... 4-38

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4.2.15.13 Navigation ................................................................................................ 4-38

4.2.15.13.1 Historic Conditions ......................................................... 4-38

4.2.15.13.2 Existing Conditions......................................................... 4-38

4.2.15.14 Man-Made Resources............................................................................. 4-38

4.2.15.14.1 Oil, Gas, Utilities, Pipelines............................................ 4-38

4.2.15.14.2 Flood Control and Hurricane Protection ....................... 4-39

4.2.15.15 Natural Resources................................................................................... 4-41

4.2.15.15.1 Commercial Fisheries.................................................... 4-41

4.2.15.15.2 Oyster Leases................................................................ 4-41

4.2.16 Hazardous, Toxic, and Radioactive Wastes................................................................. 4-42

4.2.16.1 Historic Conditions................................................................................... 4-42

4.2.16.2 Existing Conditions .................................................................................. 4-45

5.0 ENVIRONMENTAL CONSEQUENCES.................................................................................................. 5-1

5.1 SOILS AND WATERBOTTOMS...................................................................................................... 5-2

5.1.1 Soils and Waterbottoms................................................................................................... 5-2

5.1.1.1 No Action Alternative (Future Without Project Conditions)...................... 5-2

5.1.1.1.1 Direct................................................................................. 5-2

5.1.1.1.2 Indirect.............................................................................. 5-2

5.1.1.1.3 Cumulative........................................................................ 5-2

5.1.1.2 Alternative 1 – 5,000 cfs max Diversion................................................... 5-3

5.1.1.2.1 Direct................................................................................. 5-3

5.1.1.2.2 Indirect.............................................................................. 5-3

5.1.1.2.3 Cumulative........................................................................ 5-3

5.1.1.3 Alternative 2 – 10,000 cfs max Diversion................................................. 5-3

5.1.1.3.1 Direct................................................................................. 5-3

5.1.1.3.2 Indirect.............................................................................. 5-3

5.1.1.3.3 Cumulative........................................................................ 5-3

5.1.1.4 Alternative 3 – 15,000 cfs max Diversion................................................. 5-4

5.1.1.4.1 Direct................................................................................. 5-4

5.1.1.4.2 Indirect.............................................................................. 5-4

5.1.1.4.3 Cumulative........................................................................ 5-4

5.1.1.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ........... 5-4

5.1.1.5.1 Direct................................................................................. 5-4

5.1.1.5.2 Indirect.............................................................................. 5-4

5.1.1.5.3 Cumulative........................................................................ 5-4

5.2 HYDROLOGY.................................................................................................................................... 5-5

5.2.1 Flow and Water Levels..................................................................................................... 5-5

5.2.1.1 No Action Alternative (Future Without Project Conditions)...................... 5-5

5.2.1.1.1 Direct................................................................................. 5-5

5.2.1.1.2 Indirect.............................................................................. 5-5

5.2.1.1.3 Cumulative........................................................................ 5-6

5.2.1.2 Alternative 1 – 5,000 cfs max Diversion................................................... 5-6

5.2.1.2.1 Direct................................................................................. 5-6

5.2.1.2.2 Indirect.............................................................................. 5-7

5.2.1.2.3 Cumulative........................................................................ 5-7

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5.2.1.3 Alternative 2 – 10,000 cfs max Diversion................................................. 5-7

5.2.1.3.1 Direct................................................................................. 5-7

5.2.1.3.2 Indirect.............................................................................. 5-8

5.2.1.3.3 Cumulative........................................................................ 5-8

5.2.1.4 Alternative 3 – 15,000 cfs max Diversion................................................. 5-8

5.2.1.4.1 Direct................................................................................. 5-8

5.2.1.4.2 Indirect.............................................................................. 5-9

5.2.1.4.3 Cumulative........................................................................ 5-9

5.2.1.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ........... 5-9

5.2.1.5.1 Direct................................................................................. 5-9

5.2.1.5.2 Indirect............................................................................ 5-10

5.2.1.5.3 Cumulative...................................................................... 5-10

5.2.2 Sedimentation and Erosion............................................................................................ 5-11

5.2.2.1 No Action Alternative (Future Without Project Conditions).................... 5-11

5.2.2.1.1 Direct............................................................................... 5-11

5.2.2.1.2 Indirect............................................................................ 5-11

5.2.2.1.3 Cumulative...................................................................... 5-11

5.2.2.2 Alternative 1 – 5,000 cfs max Diversion................................................. 5-11

5.2.2.2.1 Direct............................................................................... 5-11

5.2.2.2.2 Indirect............................................................................ 5-12

5.2.2.2.3 Cumulative...................................................................... 5-12

5.2.2.3 Alternative 2 – 10,000 cfs max Diversion............................................... 5-12

5.2.2.3.1 Direct............................................................................... 5-12

5.2.2.3.2 Indirect............................................................................ 5-13

5.2.2.3.3 Cumulative...................................................................... 5-13

5.2.2.4 Alternative 3 – 15,000 cfs max Diversion............................................... 5-14

5.2.2.4.1 Direct............................................................................... 5-14

5.2.2.4.2 Indirect............................................................................ 5-14

5.2.2.4.3 Cumulative...................................................................... 5-14

5.2.2.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ......... 5-15

5.2.2.5.1 Direct............................................................................... 5-15

5.2.2.5.2 Indirect............................................................................ 5-15

5.2.2.5.3 Cumulative...................................................................... 5-16

5.2.3 Water Use and Supply ................................................................................................... 5-16

5.2.3.1 No Action Alternative (Future Without Project Conditions).................... 5-16

5.2.3.1.1 Direct............................................................................... 5-16

5.2.3.1.2 Indirect............................................................................ 5-16

5.2.3.1.3 Cumulative...................................................................... 5-16

5.2.3.2 Alternative 1 – 5,000 cfs max Diversion................................................. 5-17

5.2.3.2.1 Direct............................................................................... 5-17

5.2.3.2.2 Indirect............................................................................ 5-17

5.2.3.2.3 Cumulative...................................................................... 5-17

5.2.3.3 Alternative 2 – 10,000 cfs max Diversion............................................... 5-17

5.2.3.3.1 Direct............................................................................... 5-17

5.2.3.3.2 Indirect............................................................................ 5-17

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5.2.3.3.3 Cumulative...................................................................... 5-17

5.2.3.4 Alternative 3 – 15,000 cfs max Diversion............................................... 5-17

5.2.3.4.1 Direct............................................................................... 5-17

5.2.3.4.2 Indirect............................................................................ 5-17

5.2.3.4.3 Cumulative...................................................................... 5-18

5.2.3.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ......... 5-18

5.2.3.5.1 Direct............................................................................... 5-18

5.2.3.5.2 Indirect............................................................................ 5-18

5.2.3.5.3 Cumulative...................................................................... 5-18

5.2.4 Groundwater................................................................................................................... 5-18

5.2.4.1 No Action Alternative (Future Without Project Conditions).................... 5-18

5.2.4.1.1 Direct............................................................................... 5-18

5.2.4.1.2 Indirect............................................................................ 5-18

5.2.4.1.3 Cumulative...................................................................... 5-18

5.2.4.2 Alternative 1 – 5,000 cfs max Diversion................................................. 5-18

5.2.4.2.1 Direct............................................................................... 5-18

5.2.4.2.2 Indirect............................................................................ 5-19

5.2.4.2.3 Cumulative...................................................................... 5-19

5.2.4.3 Alternative 2 – 10,000 cfs max Diversion............................................... 5-19

5.2.4.3.1 Direct............................................................................... 5-19

5.2.4.3.2 Indirect............................................................................ 5-19

5.2.4.3.3 Cumulative...................................................................... 5-19

5.2.4.4 Alternative 3 – 15,000 cfs max Diversion............................................... 5-19

5.2.4.4.1 Direct............................................................................... 5-19

5.2.4.4.2 Indirect............................................................................ 5-19

5.2.4.4.3 Cumulative...................................................................... 5-19

5.2.4.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ......... 5-20

5.2.4.5.1 Direct............................................................................... 5-20

5.2.4.5.2 Indirect............................................................................ 5-20

5.2.4.5.3 Cumulative...................................................................... 5-20

5.3 WATER QUALITY AND SALINITY................................................................................................ 5-20

5.3.1 Water Quality .................................................................................................................. 5-20

5.3.1.1 No Action Alternative (Future Without Project Conditions).................... 5-20

5.3.1.1.1 Direct............................................................................... 5-20

5.3.1.1.2 Indirect............................................................................ 5-20

5.3.1.1.3 Cumulative...................................................................... 5-20

5.3.1.2 Alternative 1 – 5,000 cfs max Diversion................................................. 5-22

5.3.1.2.1 Direct............................................................................... 5-22

5.3.1.2.2 Indirect............................................................................ 5-22

5.3.1.2.3 Cumulative...................................................................... 5-22

5.3.1.3 Alternative 2 – 10,000 cfs max Diversion............................................... 5-22

5.3.1.3.1 Direct............................................................................... 5-22

5.3.1.3.2 Indirect............................................................................ 5-22

5.3.1.3.3 Cumulative...................................................................... 5-22

5.3.1.4 Alternative 3 – 15,000 cfs max Diversion............................................... 5-22

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5.3.1.4.1 Direct............................................................................... 5-22

5.3.1.4.2 Indirect............................................................................ 5-22

5.3.1.4.3 Cumulative...................................................................... 5-23

5.3.1.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ......... 5-23

5.3.1.5.1 Direct............................................................................... 5-23

5.3.1.5.2 Indirect............................................................................ 5-24

5.3.1.5.3 Cumulative...................................................................... 5-27

5.3.2 Salinity............................................................................................................................. 5-29

5.3.2.1 No Action Alternative (Future Without Project Conditions).................... 5-29

5.3.2.1.1 Direct............................................................................... 5-29

5.3.2.1.2 Indirect............................................................................ 5-29

5.3.2.1.3 Cumulative...................................................................... 5-29

5.3.2.2 Alternative 1 – 5,000 cfs max Diversion................................................. 5-29

5.3.2.2.1 Direct............................................................................... 5-29

5.3.2.2.2 Indirect............................................................................ 5-30

5.3.2.2.3 Cumulative...................................................................... 5-30

5.3.2.3 Alternative 2 – 10,000 cfs max Diversion............................................... 5-30

5.3.2.3.1 Direct............................................................................... 5-30

5.3.2.3.2 Indirect............................................................................ 5-35

5.3.2.3.3 Cumulative...................................................................... 5-35

5.3.2.4 Alternative 3 – 15,000 cfs max Diversion............................................... 5-35

5.3.2.4.1 Direct............................................................................... 5-35

5.3.2.4.2 Indirect............................................................................ 5-35

5.3.2.4.3 Cumulative...................................................................... 5-36

5.3.2.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ......... 5-36

5.3.2.5.1 Direct............................................................................... 5-36

5.3.2.5.2 Indirect............................................................................ 5-36

5.3.2.5.3 Cumulative...................................................................... 5-36

5.4 AIR QUALITY .................................................................................................................................. 5-37

5.4.1 No Action Alternative (Future Without Project Conditions) .......................................... 5-37

5.4.2 Alternative 1 – 5,000 cfs max Diversion........................................................................ 5-37

5.4.2.1 Direct ........................................................................................................ 5-37

5.4.2.2 Indirect...................................................................................................... 5-37

5.4.2.3 Cumulative ............................................................................................... 5-37

5.4.3 Alternative 2 – 10,000 cfs max Diversion...................................................................... 5-37

5.4.3.1 Direct ........................................................................................................ 5-37

5.4.3.2 Indirect...................................................................................................... 5-38

5.4.3.3 Cumulative ............................................................................................... 5-38

5.4.4 Alternative 3 – 15,000 cfs max Diversion...................................................................... 5-38

5.4.4.1 Direct ........................................................................................................ 5-38

5.4.4.2 Indirect...................................................................................................... 5-38

5.4.4.3 Cumulative ............................................................................................... 5-38

5.4.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)................................ 5-38

5.4.5.1 Direct ........................................................................................................ 5-38

5.4.5.2 Indirect...................................................................................................... 5-38

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5.4.5.3 Cumulative ............................................................................................... 5-39

5.5 NOISE .............................................................................................................................................. 5-39

5.5.1 No Action Alternative (Future Without Project Conditions) .......................................... 5-39

5.5.2 Alternative 1 – 5,000 cfs max Diversion........................................................................ 5-39

5.5.2.1 Direct ........................................................................................................ 5-39

5.5.2.2 Indirect...................................................................................................... 5-39

5.5.2.3 Cumulative ............................................................................................... 5-40

5.5.3 Alternative 2 – 10,000 cfs max Diversion...................................................................... 5-40

5.5.3.1 Direct ........................................................................................................ 5-40

5.5.3.2 Indirect...................................................................................................... 5-40

5.5.3.3 Cumulative ............................................................................................... 5-40

5.5.4 Alternative 3 – 15,000 cfs max Diversion...................................................................... 5-40

5.5.4.1 Direct ........................................................................................................ 5-40

5.5.4.2 Indirect...................................................................................................... 5-40

5.5.4.3 Cumulative ............................................................................................... 5-40

5.5.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)................................ 5-41

5.5.5.1 Direct ........................................................................................................ 5-41

5.5.5.2 Indirect...................................................................................................... 5-41

5.5.5.3 Cumulative ............................................................................................... 5-41

5.6 VEGETATIVE RESOURCES.........................................................................................................5-42

5.6.1 Riparian Vegetation Resources..................................................................................... 5-42

5.6.1.1 No Action Alternative (Future Without Project Conditions).................... 5-42

5.6.1.1.1 Direct............................................................................... 5-42

5.6.1.1.2 Indirect............................................................................ 5-42

5.6.1.1.3 Cumulative...................................................................... 5-42

5.6.1.2 Alternative 1 – 5,000 cfs max Diversion................................................. 5-42

5.6.1.2.1 Direct............................................................................... 5-42

5.6.1.2.2 Indirect............................................................................ 5-43

5.6.1.2.3 Cumulative...................................................................... 5-43

5.6.1.3 Alternative 2 – 10,000 cfs max Diversion............................................... 5-43

5.6.1.3.1 Direct............................................................................... 5-43

5.6.1.3.2 Indirect............................................................................ 5-43

5.6.1.3.3 Cumulative...................................................................... 5-43

5.6.1.4 Alternative 3- 15,000 cfs max Diversion................................................. 5-44

5.6.1.4.1 Direct............................................................................... 5-44

5.6.1.4.2 Indirect............................................................................ 5-44

5.6.1.4.3 Cumulative...................................................................... 5-44

5.6.1.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ......... 5-44

5.6.1.5.1 Direct............................................................................... 5-44

5.6.1.5.2 Indirect............................................................................ 5-44

5.6.1.5.3 Cumulative...................................................................... 5-44

5.6.2 Wetland Vegetation Resources..................................................................................... 5-45

5.6.2.1 No Action Alternative (Future Without Project Conditions).................... 5-45

5.6.2.1.1 Direct............................................................................... 5-45

5.6.2.1.2 Indirect............................................................................ 5-45

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5.6.2.1.3 Cumulative...................................................................... 5-45

5.6.2.2 Alternative 1 – 5,000 cfs max Diversion................................................. 5-45

5.6.2.2.1 Direct............................................................................... 5-45

5.6.2.2.2 Indirect............................................................................ 5-46

5.6.2.2.3 Cumulative...................................................................... 5-46

5.6.2.3 Alternative 2 – 10,000 cfs max Diversion............................................... 5-46

5.6.2.3.1 Direct............................................................................... 5-46

5.6.2.3.2 Indirect............................................................................ 5-46

5.6.2.3.3 Cumulative...................................................................... 5-47

5.6.2.4 Alternative 3 – 15,000 cfs max Diversion............................................... 5-47

5.6.2.4.1 Direct............................................................................... 5-47

5.6.2.4.2 Indirect............................................................................ 5-47

5.6.2.4.3 Cumulative...................................................................... 5-47

5.6.2.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ......... 5-47

5.6.2.5.1 Direct............................................................................... 5-47

5.6.2.5.2 Indirect............................................................................ 5-48

5.6.2.5.3 Cumulative...................................................................... 5-48

5.6.3 Upland Vegetation Resources....................................................................................... 5-48

5.6.4 Submerged Aquatic Vegetation (SAV).......................................................................... 5-48

5.6.4.1 No Action Alternative (Future Without Project Conditions).................... 5-48

5.6.4.1.1 Direct............................................................................... 5-48

5.6.4.1.2 Indirect............................................................................ 5-48

5.6.4.1.3 Cumulative...................................................................... 5-49

5.6.4.2 Alternative 1 – 5,000 cfs max Diversion................................................. 5-49

5.6.4.2.1 Direct............................................................................... 5-49

5.6.4.2.2 Indirect............................................................................ 5-49

5.6.4.2.3 Cumulative...................................................................... 5-49

5.6.4.3 Alternative 2 – 10,000 cfs max Diversion............................................... 5-50

5.6.4.3.1 Direct............................................................................... 5-50

5.6.4.3.2 Indirect............................................................................ 5-50

5.6.4.3.3 Cumulative...................................................................... 5-50

5.6.4.4 Alternative 3 – 15,000 cfs max Diversion............................................... 5-50

5.6.4.4.1 Direct............................................................................... 5-50

5.6.4.4.2 Indirect............................................................................ 5-50

5.6.4.4.3 Cumulative...................................................................... 5-50

5.6.4.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ......... 5-51

5.6.4.5.1 Direct............................................................................... 5-51

5.6.4.5.2 Indirect............................................................................ 5-51

5.6.4.5.3 Cumulative...................................................................... 5-51

5.6.5 Invasive Species – Vegetation....................................................................................... 5-51

5.6.5.1 No Action Alternative (Future Without Project Conditions).................... 5-51

5.6.5.1.1 Direct............................................................................... 5-51

5.6.5.1.2 Indirect............................................................................ 5-51

5.6.5.1.3 Cumulative...................................................................... 5-51

5.6.5.2 Alternative 1 – 5,000 cfs max Diversion................................................. 5-52

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5.6.5.2.1 Direct............................................................................... 5-52

5.6.5.2.2 Indirect............................................................................ 5-52

5.6.5.2.3 Cumulative...................................................................... 5-52

5.6.5.3 Alternative 2 – 10,000 cfs max Diversion............................................... 5-52

5.6.5.3.1 Direct............................................................................... 5-52

5.6.5.3.2 Indirect............................................................................ 5-52

5.6.5.3.3 Cumulative...................................................................... 5-53

5.6.5.4 Alternative 3 – 15,000 cfs max Diversion............................................... 5-53

5.6.5.4.1 Direct............................................................................... 5-53

5.6.5.4.2 Indirect............................................................................ 5-53

5.6.5.4.3 Cumulative...................................................................... 5-53

5.6.5.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ......... 5-53

5.6.5.5.1 Direct............................................................................... 5-53

5.6.5.5.2 Indirect............................................................................ 5-53

5.6.5.5.3 Cumulative...................................................................... 5-53

5.7 WILDLIFE AND HABITAT .............................................................................................................. 5-54

5.7.1 No Action Alternative (Future Without Project Conditions) .......................................... 5-54

5.7.1.1 Direct ........................................................................................................ 5-54

5.7.1.2 Indirect...................................................................................................... 5-54

5.7.1.3 Cumulative ............................................................................................... 5-54

5.7.2 Alternative 1 – 5,000 cfs max Diversion........................................................................ 5-54

5.7.2.1 Direct ........................................................................................................ 5-54

5.7.2.2 Indirect...................................................................................................... 5-54

5.7.2.3 Cumulative ............................................................................................... 5-55

5.7.3 Alternative 2 – 10,000 cfs max Diversion...................................................................... 5-55

5.7.3.1 Direct ........................................................................................................ 5-55

5.7.3.2 Indirect...................................................................................................... 5-55

5.7.3.3 Cumulative ............................................................................................... 5-55

5.7.4 Alternative 3 – 15,000 cfs max Diversion...................................................................... 5-56

5.7.4.1 Direct ........................................................................................................ 5-56

5.7.4.2 Indirect...................................................................................................... 5-56

5.7.4.3 Cumulative ............................................................................................... 5-56

5.7.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)................................ 5-57

5.7.5.1 Direct ........................................................................................................ 5-57

5.7.5.2 Indirect...................................................................................................... 5-57

5.7.5.3 Cumulative ............................................................................................... 5-57

5.8 AQUATIC RESOURCES................................................................................................................ 5-58

5.8.1 Benthic ............................................................................................................................ 5-58

5.8.1.1 No Action Alternative (Future Without Project Conditions).................... 5-58

5.8.1.1.1 Direct............................................................................... 5-58

5.8.1.1.2 Indirect............................................................................ 5-58

5.8.1.1.3 Cumulative...................................................................... 5-58

5.8.1.2 Alternative 1 – 5,000 cfs max Diversion................................................. 5-59

5.8.1.2.1 Direct............................................................................... 5-59

5.8.1.2.2 Indirect............................................................................ 5-59

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5.8.1.2.3 Cumulative...................................................................... 5-59

5.8.1.3 Alternative 2 – 10,000 cfs max Diversion............................................... 5-60

5.8.1.3.1 Direct............................................................................... 5-60

5.8.1.3.2 Indirect............................................................................ 5-60

5.8.1.3.3 Cumulative...................................................................... 5-61

5.8.1.4 Alternative 3 – 15,000 cfs max Diversion............................................... 5-61

5.8.1.4.1 Direct............................................................................... 5-61

5.8.1.4.2 Indirect............................................................................ 5-62

5.8.1.4.3 Cumulative...................................................................... 5-62

5.8.1.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ......... 5-63

5.8.1.5.1 Direct............................................................................... 5-63

5.8.1.5.2 Indirect............................................................................ 5-63

5.8.1.5.3 Cumulative...................................................................... 5-63

5.8.2 Plankton .......................................................................................................................... 5-64

5.8.2.1 No Action Alternative (Future Without Project Conditions).................... 5-64

5.8.2.1.1 Direct............................................................................... 5-64

5.8.2.1.2 Indirect............................................................................ 5-65

5.8.2.1.3 Cumulative...................................................................... 5-65

5.8.2.2 Alternative 1 – 5,000 cfs max Diversion................................................. 5-65

5.8.2.2.1 Direct............................................................................... 5-65

5.8.2.2.2 Indirect............................................................................ 5-66

5.8.2.2.3 Cumulative...................................................................... 5-66

5.8.2.3 Alternative 2 – 10,000 cfs max Diversion............................................... 5-66

5.8.2.3.1 Direct............................................................................... 5-66

5.8.2.3.2 Indirect............................................................................ 5-66

5.8.2.3.3 Cumulative...................................................................... 5-66

5.8.2.4 Alternative 3 – 15,000 cfs max Diversion............................................... 5-67

5.8.2.4.1 Direct............................................................................... 5-67

5.8.2.4.2 Indirect............................................................................ 5-67

5.8.2.4.3 Cumulative...................................................................... 5-67

5.8.2.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ......... 5-67

5.8.2.5.1 Direct............................................................................... 5-67

5.8.2.5.2 Indirect............................................................................ 5-68

5.8.2.5.3 Cumulative...................................................................... 5-68

5.8.3 Other Aquatic Resources............................................................................................... 5-69

5.9 FISHERIES...................................................................................................................................... 5-69

5.9.1 No Action Alternative (Future Without Project Conditions) .......................................... 5-69

5.9.1.1 Direct ........................................................................................................ 5-69

5.9.1.2 Indirect...................................................................................................... 5-69

5.9.1.3 Cumulative ............................................................................................... 5-70

5.9.2 Alternative 1 – 5,000 cfs diversion................................................................................. 5-70

5.9.2.1 Direct ........................................................................................................ 5-70

5.9.2.2 Indirect...................................................................................................... 5-70

5.9.2.3 Cumulative ............................................................................................... 5-71

5.9.3 Alternative 2 – 10,000 cfs max Diversion...................................................................... 5-71

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5.9.3.1 Direct ........................................................................................................ 5-71

5.9.3.2 Indirect...................................................................................................... 5-72

5.9.3.3 Cumulative ............................................................................................... 5-72

5.9.4 Alternative 3 – 15,000 cfs max Diversion...................................................................... 5-72

5.9.4.1 Direct ........................................................................................................ 5-72

5.9.4.2 Indirect...................................................................................................... 5-73

5.9.4.3 Cumulative ............................................................................................... 5-74

5.9.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)................................ 5-74

5.9.5.1 Direct ........................................................................................................ 5-74

5.9.5.2 Indirect...................................................................................................... 5-74

5.9.5.3 Cumulative ............................................................................................... 5-75

5.10 ESSENTIAL FISH HABITAT (EFH) ............................................................................................... 5-75

5.10.1 No Action Alternative (Future Without Project Conditions) .......................................... 5-75

5.10.1.1 Direct ........................................................................................................ 5-75

5.10.1.2 Indirect...................................................................................................... 5-75

5.10.1.3 Cumulative ............................................................................................... 5-76

5.10.2 Alternative 1 – 5,000 cfs max Diversion........................................................................ 5-76

5.10.2.1 Direct ........................................................................................................ 5-76

5.10.2.2 Indirect...................................................................................................... 5-76

5.10.2.3 Cumulative ............................................................................................... 5-77

5.10.3 Alternative 2 – 10,000 cfs max Diversion...................................................................... 5-77

5.10.3.1 Direct ........................................................................................................ 5-77

5.10.3.2 Indirect...................................................................................................... 5-77

5.10.3.3 Cumulative ............................................................................................... 5-78

5.10.4 Alternative 3 – 15,000 cfs max Diversion...................................................................... 5-78

5.10.4.1 Direct ........................................................................................................ 5-78

5.10.4.2 Indirect...................................................................................................... 5-78

5.10.4.3 Cumulative ............................................................................................... 5-78

5.10.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)................................ 5-79

5.10.5.1 Direct ........................................................................................................ 5-79

5.10.5.2 Indirect...................................................................................................... 5-79

5.10.5.3 Cumulative ............................................................................................... 5-79

5.11 THREATENED AND ENDANGERED SPECIES.......................................................................... 5-80

5.11.1 No Action Alternative (Future Without Project Conditions) .......................................... 5-80

5.11.1.1 Direct ........................................................................................................ 5-80

5.11.1.2 Indirect...................................................................................................... 5-80

5.11.1.3 Cumulative ............................................................................................... 5-80

5.11.2 Alternative 1 – 5,000 cfs max Diversion........................................................................ 5-80

5.11.2.1 Direct ........................................................................................................ 5-80

5.11.2.2 Indirect...................................................................................................... 5-80

5.11.2.3 Cumulative ............................................................................................... 5-81

5.11.3 Alternative 2 – 10,000 cfs max Diversion...................................................................... 5-81

5.11.3.1 Direct ........................................................................................................ 5-81

5.11.3.2 Indirect...................................................................................................... 5-82

5.11.3.3 Cumulative ............................................................................................... 5-82

5.11.4 Alternative 3 – 15,000 cfs max Diversion...................................................................... 5-82

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5.11.4.1 Direct ........................................................................................................ 5-82

5.11.4.2 Indirect...................................................................................................... 5-82

5.11.4.3 Cumulative ............................................................................................... 5-82

5.11.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)................................ 5-83

5.11.5.1 Direct ........................................................................................................ 5-83

5.11.5.2 Indirect...................................................................................................... 5-85

5.11.5.3 Cumulative ............................................................................................... 5-85

5.12 CULTURAL AND HISTORIC RESOURCES ................................................................................ 5-85

5.12.1 No Action Alternative (Future Without Project Conditions) .......................................... 5-86

5.12.1.1 Direct ........................................................................................................ 5-86

5.12.1.2 Indirect...................................................................................................... 5-86

5.12.1.3 Cumulative ............................................................................................... 5-86

5.12.2 Alternative 1 – 5,000 cfs max Diversion........................................................................ 5-86

5.12.2.1 Direct ........................................................................................................ 5-86

5.12.2.2 Indirect...................................................................................................... 5-86

5.12.2.3 Cumulative ............................................................................................... 5-86

5.12.3 Alternative 2 – 10,000 cfs max Diversion...................................................................... 5-86

5.12.3.1 Direct ........................................................................................................ 5-86

5.12.3.2 Indirect...................................................................................................... 5-86

5.12.3.3 Cumulative ............................................................................................... 5-87

5.12.4 Alternative 3 – 15,000 cfs max Diversion...................................................................... 5-87

5.12.4.1 Direct ........................................................................................................ 5-87

5.12.4.2 Indirect...................................................................................................... 5-87

5.12.4.3 Cumulative ............................................................................................... 5-87

5.12.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)................................ 5-87

5.12.5.1 Direct ........................................................................................................ 5-87

5.12.5.2 Indirect...................................................................................................... 5-87

5.12.5.3 Cumulative ............................................................................................... 5-87

5.13 AESTHETICS.................................................................................................................................. 5-88

5.13.1 No Action Alternative (Future Without Project Conditions) .......................................... 5-88

5.13.1.1 Direct ........................................................................................................ 5-88

5.13.1.2 Indirect...................................................................................................... 5-88

5.13.1.3 Cumulative ............................................................................................... 5-88

5.13.2 Alternative 1 – 5,000 cfs max Diversion........................................................................ 5-88

5.13.2.1 Direct ........................................................................................................ 5-88

5.13.2.2 Indirect...................................................................................................... 5-88

5.13.2.3 Cumulative ............................................................................................... 5-89

5.13.3 Alternative 2 – 10,000 cfs max Diversion...................................................................... 5-89

5.13.3.1 Direct ........................................................................................................ 5-89

5.13.3.2 Indirect...................................................................................................... 5-89

5.13.3.3 Cumulative ............................................................................................... 5-89

5.13.4 Alternative 3 – 15,000 cfs max Diversion...................................................................... 5-89

5.13.4.1 Direct ........................................................................................................ 5-89

5.13.4.2 Indirect...................................................................................................... 5-89

5.13.4.3 Cumulative ............................................................................................... 5-89

5.13.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)................................ 5-90

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5.13.5.1 Direct ........................................................................................................ 5-90

5.13.5.2 Indirect...................................................................................................... 5-90

5.13.5.3 Cumulative ............................................................................................... 5-90

5.14 RECREATION................................................................................................................................. 5-90

5.14.1 No Action Alternative (Future Without Project Conditions) .......................................... 5-90

5.14.1.1 Direct ........................................................................................................ 5-90

5.14.1.2 Indirect...................................................................................................... 5-91

5.14.1.3 Cumulative ............................................................................................... 5-91

5.14.2 Alternative 1 – 5,000 cfs max Diversion........................................................................ 5-91

5.14.2.1 Direct ........................................................................................................ 5-91

5.14.2.2 Indirect...................................................................................................... 5-92

5.14.2.3 Cumulative ............................................................................................... 5-92

5.14.3 Alternative 2 – 10,000 cfs max Diversion...................................................................... 5-93

5.14.3.1 Direct ........................................................................................................ 5-93

5.14.3.2 Indirect...................................................................................................... 5-93

5.14.3.3 Cumulative ............................................................................................... 5-93

5.14.4 Alternative 3 – 15,000 cfs max Diversion...................................................................... 5-94

5.14.4.1 Direct ........................................................................................................ 5-94

5.14.4.2 Indirect...................................................................................................... 5-94

5.14.4.3 Cumulative ............................................................................................... 5-94

5.14.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)................................ 5-94

5.14.5.1 Direct ........................................................................................................ 5-94

5.14.5.2 Indirect...................................................................................................... 5-95

5.14.5.3 Cumulative ............................................................................................... 5-95

5.15 SOCIOECONOMICS AND HUMAN RESOURCES..................................................................... 5-95

5.15.1 Displacement of Population and Housing..................................................................... 5-95

5.15.1.1 No Action Alternative (Future Without Project Conditions).................... 5-95

5.15.1.1.1 Direct............................................................................... 5-95

5.15.1.1.2 Indirect............................................................................ 5-95

5.15.1.1.3 Cumulative...................................................................... 5-95

5.15.1.2 Alternative 1 – 5,000 cfs Diversion ......................................................... 5-96

5.15.1.2.1 Direct............................................................................... 5-96

5.15.1.2.2 Indirect............................................................................ 5-96

5.15.1.2.3 Cumulative...................................................................... 5-96

5.15.1.3 Alternative 2 – 10,000 cfs max Diversion............................................... 5-96

5.15.1.3.1 Direct............................................................................... 5-96

5.15.1.3.2 Indirect............................................................................ 5-96

5.15.1.3.3 Cumulative...................................................................... 5-96

5.15.1.4 Alternative 3 – 15,000 cfs max Diversion............................................... 5-97

5.15.1.4.1 Direct............................................................................... 5-97

5.15.1.4.2 Indirect............................................................................ 5-97

5.15.1.4.3 Cumulative...................................................................... 5-97

5.15.1.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ......... 5-97

5.15.1.5.1 Direct............................................................................... 5-97

5.15.1.5.2 Indirect............................................................................ 5-97

5.15.1.5.3 Cumulative...................................................................... 5-97

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5.15.2 Employment, Business, and Industrial Activity ............................................................. 5-97

5.15.2.1 No Action Alternative (Future Without Project Conditions).................... 5-97

5.15.2.1.1 Direct............................................................................... 5-97

5.15.2.1.2 Indirect............................................................................ 5-97

5.15.2.1.3 Cumulative...................................................................... 5-98

5.15.2.2 Alternative 1 – 5,000 cfs Diversion ......................................................... 5-98

5.15.2.2.1 Direct............................................................................... 5-98

5.15.2.2.2 Indirect............................................................................ 5-98

5.15.2.2.3 Cumulative...................................................................... 5-98

5.15.2.3 Alternative 2 – 10,000 cfs max Diversion............................................... 5-98

5.15.2.3.1 Direct............................................................................... 5-98

5.15.2.3.2 Indirect............................................................................ 5-99

5.15.2.3.3 Cumulative...................................................................... 5-99

5.15.2.4 Alternative 3 – 15,000 cfs max Diversion............................................... 5-99

5.15.2.4.1 Direct............................................................................... 5-99

5.15.2.4.2 Indirect............................................................................ 5-99

5.15.2.4.3 Cumulative...................................................................... 5-99

5.15.2.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ......... 5-99

5.15.2.5.1 Direct............................................................................... 5-99

5.15.2.5.2 Indirect............................................................................ 5-99

5.15.2.5.3 Cumulative.................................................................... 5-100

5.15.3 Community Cohesion................................................................................................... 5-100

5.15.3.1 No Action Alternative (Future Without Project Conditions).................. 5-100

5.15.3.1.1 Direct............................................................................. 5-100

5.15.3.1.2 Indirect.......................................................................... 5-100

5.15.3.1.3 Cumulative.................................................................... 5-100

5.15.3.2 Alternative 1 – 5,000 cfs Diversion ....................................................... 5-100

5.15.3.2.1 Direct............................................................................. 5-100

5.15.3.2.2 Indirect.......................................................................... 5-100

5.15.3.2.3 Cumulative.................................................................... 5-101

5.15.3.3 Alternative 2 – 10,000 cfs max Diversion............................................. 5-101

5.15.3.3.1 Direct............................................................................. 5-101

5.15.3.3.2 Indirect.......................................................................... 5-101

5.15.3.3.3 Cumulative.................................................................... 5-101

5.15.3.4 Alternative 3 – 15,000 cfs max Diversion............................................. 5-101

5.15.3.4.1 Direct............................................................................. 5-101

5.15.3.4.2 Indirect.......................................................................... 5-101

5.15.3.4.3 Cumulative.................................................................... 5-101

5.15.3.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ....... 5-102

5.15.3.5.1 Direct............................................................................. 5-102

5.15.3.5.2 Indirect.......................................................................... 5-102

5.15.3.5.3 Cumulative.................................................................... 5-102

5.15.4 Environmental Justice .................................................................................................. 5-102

5.15.4.1 No Action Alternative (Future Without Project Conditions).................. 5-102

5.15.4.1.1 Direct............................................................................. 5-102

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5.15.4.1.2 Indirect.......................................................................... 5-102

5.15.4.1.3 Cumulative.................................................................... 5-102

5.15.4.2 Alternative 1 – 5,000 cfs Diversion ....................................................... 5-102

5.15.4.2.1 Direct............................................................................. 5-102

5.15.4.2.2 Indirect.......................................................................... 5-103

5.15.4.2.3 Cumulative.................................................................... 5-103

5.15.4.3 Alternative 2 – 10,000 cfs max Diversion............................................. 5-103

5.15.4.3.1 Direct............................................................................. 5-103

5.15.4.3.2 Indirect.......................................................................... 5-103

5.15.4.3.3 Cumulative.................................................................... 5-103

5.15.4.4 Alternative 3 – 15,000 cfs max Diversion............................................. 5-103

5.15.4.4.1 Direct............................................................................. 5-103

5.15.4.4.2 Indirect.......................................................................... 5-103

5.15.4.4.3 Cumulative.................................................................... 5-103

5.15.4.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ....... 5-103

5.15.4.5.1 Direct............................................................................. 5-103

5.15.4.5.2 Indirect.......................................................................... 5-104

5.15.4.5.3 Cumulative.................................................................... 5-104

5.15.5 Infrastructure................................................................................................................. 5-104

5.15.5.1 No Action Alternative (Future Without Project Conditions).................. 5-104

5.15.5.1.1 Direct............................................................................. 5-104

5.15.5.1.2 Indirect.......................................................................... 5-104

5.15.5.1.3 Cumulative.................................................................... 5-104

5.15.5.2 Alternative 1 – 5,000 cfs Diversion ....................................................... 5-104

5.15.5.2.1 Direct............................................................................. 5-104

5.15.5.2.2 Indirect.......................................................................... 5-104

5.15.5.2.3 Cumulative.................................................................... 5-105

5.15.5.3 Alternative 2 – 10,000 cfs max Diversion............................................. 5-105

5.15.5.3.1 Direct............................................................................. 5-105

5.15.5.3.2 Indirect.......................................................................... 5-105

5.15.5.3.3 Cumulative.................................................................... 5-105

5.15.5.4 Alternative 3 – 15,000 cfs max Diversion............................................. 5-105

5.15.5.4.1 Direct............................................................................. 5-105

5.15.5.4.2 Indirect.......................................................................... 5-105

5.15.5.4.3 Cumulative.................................................................... 5-105

5.15.5.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ....... 5-105

5.15.5.5.1 Direct............................................................................. 5-105

5.15.5.5.2 Indirect.......................................................................... 5-106

5.15.5.5.3 Cumulative.................................................................... 5-106

5.15.6 Business and Industry.................................................................................................. 5-106

5.15.6.1 No Action Alternative (Future Without Project Conditions).................. 5-106

5.15.6.1.1 Direct............................................................................. 5-106

5.15.6.1.2 Indirect.......................................................................... 5-106

5.15.6.1.3 Cumulative.................................................................... 5-106

5.15.6.2 Alternative 1 – 5,000 cfs Diversion ....................................................... 5-106

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5.15.6.2.1 Direct............................................................................. 5-106

5.15.6.2.2 Indirect.......................................................................... 5-107

5.15.6.2.3 Cumulative.................................................................... 5-107

5.15.6.3 Alternative 2 – 10,000 cfs max Diversion............................................. 5-107

5.15.6.3.1 Direct............................................................................. 5-107

5.15.6.3.2 Indirect.......................................................................... 5-107

5.15.6.3.3 Cumulative.................................................................... 5-107

5.15.6.4 Alternative 3 – 15,000 cfs max Diversion............................................. 5-107

5.15.6.4.1 Direct............................................................................. 5-107

5.15.6.4.2 Indirect.......................................................................... 5-107

5.15.6.4.3 Cumulative.................................................................... 5-107

5.15.6.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ....... 5-108

5.15.6.5.1 Direct............................................................................. 5-108

5.15.6.5.2 Indirect.......................................................................... 5-108

5.15.6.5.3 Cumulative.................................................................... 5-108

5.15.7 Traffic and Transportation............................................................................................ 5-108

5.15.7.1 No Action Alternative (Future Without Project Conditions).................. 5-108

5.15.7.1.1 Direct............................................................................. 5-108

5.15.7.1.2 Indirect.......................................................................... 5-108

5.15.7.1.3 Cumulative.................................................................... 5-108

5.15.7.2 Alternative 1 – 5,000 cfs Diversion ....................................................... 5-109

5.15.7.2.1 Direct............................................................................. 5-109

5.15.7.2.2 Indirect.......................................................................... 5-109

5.15.7.2.3 Cumulative.................................................................... 5-109

5.15.7.3 Alternative 2 – 10,000 cfs max Diversion............................................. 5-109

5.15.7.3.1 Direct............................................................................. 5-109

5.15.7.3.2 Indirect.......................................................................... 5-109

5.15.7.3.3 Cumulative.................................................................... 5-109

5.15.7.4 Alternative 3 – 15,000 cfs max Diversion............................................. 5-109

5.15.7.4.1 Direct............................................................................. 5-109

5.15.7.4.2 Indirect.......................................................................... 5-109

5.15.7.4.3 Cumulative.................................................................... 5-110

5.15.7.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ....... 5-110

5.15.7.5.1 Direct............................................................................. 5-110

5.15.7.5.2 Indirect.......................................................................... 5-110

5.15.7.5.3 Cumulative.................................................................... 5-110

5.15.8 Public Facilities and Services....................................................................................... 5-110

5.15.8.1 No Action Alternative (Future Without Project Conditions).................. 5-110

5.15.8.1.1 Direct............................................................................. 5-110

5.15.8.1.2 Indirect.......................................................................... 5-110

5.15.8.1.3 Cumulative.................................................................... 5-110

5.15.8.2 Alternative 1 – 5,000 cfs Diversion ....................................................... 5-111

5.15.8.2.1 Direct............................................................................. 5-111

5.15.8.2.2 Indirect.......................................................................... 5-111

5.15.8.2.3 Cumulative.................................................................... 5-111

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5.15.8.3 Alternative 2 – 10,000 cfs max Diversion............................................. 5-111

5.15.8.3.1 Direct............................................................................. 5-111

5.15.8.3.2 Indirect.......................................................................... 5-111

5.15.8.3.3 Cumulative.................................................................... 5-111

5.15.8.4 Alternative 3 – 15,000 cfs max Diversion............................................. 5-111

5.15.8.4.1 Direct............................................................................. 5-111

5.15.8.4.2 Indirect.......................................................................... 5-111

5.15.8.4.3 Cumulative.................................................................... 5-111

5.15.8.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ....... 5-112

5.15.8.5.1 Direct............................................................................. 5-112

5.15.8.5.2 Indirect.......................................................................... 5-112

5.15.8.5.3 Cumulative.................................................................... 5-112

5.15.9 Tax Revenues and Property Values ........................................................................... 5-112

5.15.9.1 No Action Alternative (Future Without Project Conditions).................. 5-112

5.15.9.1.1 Direct............................................................................. 5-112

5.15.9.1.2 Indirect.......................................................................... 5-112

5.15.9.1.3 Cumulative.................................................................... 5-112

5.15.9.2 Alternative 1 – 5,000 cfs Diversion ....................................................... 5-113

5.15.9.2.1 Direct............................................................................. 5-113

5.15.9.2.2 Indirect.......................................................................... 5-113

5.15.9.2.3 Cumulative.................................................................... 5-113

5.15.9.3 Alternative 2 – 10,000 cfs max Diversion............................................. 5-113

5.15.9.3.1 Direct............................................................................. 5-113

5.15.9.3.2 Indirect.......................................................................... 5-113

5.15.9.3.3 Cumulative.................................................................... 5-113

5.15.9.4 Alternative 3 – 15,000 cfs max Diversion............................................. 5-113

5.15.9.4.1 Direct............................................................................. 5-113

5.15.9.4.2 Indirect.......................................................................... 5-113

5.15.9.4.3 Cumulative.................................................................... 5-113

5.15.9.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ....... 5-114

5.15.9.5.1 Direct............................................................................. 5-114

5.15.9.5.2 Indirect.......................................................................... 5-114

5.15.9.5.3 Cumulative.................................................................... 5-114

5.15.10 Disruption of Desirable Community and Regional Growth......................................... 5-114

5.15.10.1 No Action Alternative (Future Without Project Conditions).................. 5-114

5.15.10.1.1 Direct............................................................................. 5-114

5.15.10.1.2 Indirect.......................................................................... 5-114

5.15.10.1.3 Cumulative.................................................................... 5-114

5.15.10.2 Alternative 1 – 5,000 cfs Diversion ....................................................... 5-114

5.15.10.2.1 Direct............................................................................. 5-114

5.15.10.2.2 Indirect.......................................................................... 5-115

5.15.10.2.3 Cumulative.................................................................... 5-115

5.15.10.3 Alternative 2 – 10,000 cfs max Diversion............................................. 5-115

5.15.10.3.1 Direct............................................................................. 5-115

5.15.10.3.2 Indirect.......................................................................... 5-115

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5.15.10.3.3 Cumulative.................................................................... 5-115

5.15.10.4 Alternative 3 – 15,000 cfs max Diversion............................................. 5-115

5.15.10.4.1 Direct............................................................................. 5-115

5.15.10.4.2 Indirect.......................................................................... 5-115

5.15.10.4.3 Cumulative.................................................................... 5-115

5.15.10.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ....... 5-115

5.15.10.5.1 Direct............................................................................. 5-115

5.15.10.5.2 Indirect.......................................................................... 5-116

5.15.10.5.3 Cumulative.................................................................... 5-116

5.15.11 Land Use Socioeconomics .......................................................................................... 5-116

5.15.11.1 Agriculture .............................................................................................. 5-116

5.15.11.1.1 No Action Alternative (Future Without Project

Conditions) ................................................................... 5-116

5.15.11.1.2 Alternative 1 – 5,000 cfs Diversion.............................. 5-116

5.15.11.1.3 Alternative 2 – 10,000 cfs max Diversion ................... 5-117

5.15.11.1.4 Alternative 3 – 10,000 cfs max Diversion ................... 5-117

5.15.11.1.5 Alternative 4 – 35,000 cfs max Diversion

(Recommended Plan).................................................. 5-118

5.15.11.2 Forestry .................................................................................................. 5-118

5.15.11.2.1 No Action Alternative (Future Without Project

Conditions) ................................................................... 5-118

5.15.11.2.2 Alternative 1 – 5,000 cfs Diversion.............................. 5-119

5.15.11.2.3 Alternative 2 – 10,000 cfs max Diversion ................... 5-119

5.15.11.2.4 Alternative 3 – 15,000 cfs max Diversion ................... 5-119

5.15.11.2.5 Alternative 4 – 35,000 cfs max Diversion

(Recommended Plan).................................................. 5-120

5.15.11.3 Public Lands........................................................................................... 5-120

5.15.11.3.1 No Action Alternative (Future Without Project

Conditions) ................................................................... 5-120

5.15.11.3.2 Alternative 1 – 5,000 cfs Diversion.............................. 5-121

5.15.11.3.3 Alternative 2 – 10,000 cfs max Diversion ................... 5-121

5.15.11.3.4 Alternative 3 – 15,000 cfs max Diversion ................... 5-121

5.15.11.3.5 Alternative 4 – 35,000 cfs max Diversion

(Recommended Plan).................................................. 5-122

5.15.12 Water Use and Supply ................................................................................................. 5-122

5.15.12.1 No Action Alternative (Future Without Project Conditions).................. 5-122

5.15.12.1.1 Direct............................................................................. 5-122

5.15.12.1.2 Indirect.......................................................................... 5-122

5.15.12.1.3 Cumulative.................................................................... 5-122

5.15.12.2 Alternative 1 – 5,000 cfs Diversion ....................................................... 5-122

5.15.12.2.1 Direct............................................................................. 5-122

5.15.12.2.2 Indirect.......................................................................... 5-123

5.15.12.2.3 Cumulative.................................................................... 5-123

5.15.12.3 Alternative 2 – 10,000 cfs max Diversion............................................. 5-123

5.15.12.3.1 Direct............................................................................. 5-123

5.15.12.3.2 Indirect.......................................................................... 5-123

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5.15.12.3.3 Cumulative.................................................................... 5-123

5.15.12.4 Alternative 3 – 15,000 cfs max Diversion............................................. 5-123

5.15.12.4.1 Direct............................................................................. 5-123

5.15.12.4.2 Indirect.......................................................................... 5-123

5.15.12.4.3 Cumulative.................................................................... 5-123

5.15.12.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ....... 5-123

5.15.12.5.1 Direct............................................................................. 5-123

5.15.12.5.2 Indirect.......................................................................... 5-123

5.15.12.5.3 Cumulative.................................................................... 5-124

5.15.13 Navigation ..................................................................................................................... 5-124

5.15.13.1 No Action Alternative (Future Without Project Conditions).................. 5-124

5.15.13.1.1 Direct............................................................................. 5-124

5.15.13.1.2 Indirect.......................................................................... 5-124

5.15.13.1.3 Cumulative.................................................................... 5-124

5.15.13.2 Alternative 1 – 5,000 cfs Diversion ....................................................... 5-124

5.15.13.2.1 Direct............................................................................. 5-124

5.15.13.2.2 Indirect.......................................................................... 5-124

5.15.13.2.3 Cumulative.................................................................... 5-125

5.15.13.3 Alternative 2 – 10,000 cfs max Diversion............................................. 5-125

5.15.13.3.1 Direct............................................................................. 5-125

5.15.13.3.2 Indirect.......................................................................... 5-125

5.15.13.3.3 Cumulative.................................................................... 5-126

5.15.13.4 Alternative 3 – 15,000 cfs max Diversion............................................. 5-126

5.15.13.4.1 Direct............................................................................. 5-126

5.15.13.4.2 Indirect.......................................................................... 5-126

5.15.13.4.3 Cumulative.................................................................... 5-127

5.15.13.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan) ....... 5-127

5.15.13.5.1 Direct............................................................................. 5-127

5.15.13.5.2 Indirect.......................................................................... 5-127

5.15.13.5.3 Cumulative.................................................................... 5-128

5.15.14 Man-Made Resources.................................................................................................. 5-128

5.15.14.1 Oil, Gas, Utilities..................................................................................... 5-128

5.15.14.1.1 No Action Alternative (Future Without Project

Conditions) ................................................................... 5-128

5.15.14.1.2 Alternative 1 – 5,000 cfs Diversion.............................. 5-128

5.15.14.1.3 Alternative 2 – 10,000 cfs max Diversion ................... 5-129

5.15.14.1.4 Alternative 3 – 15,000 cfs max Diversion ................... 5-129

5.15.14.1.5 Alternative 4 – 35,000 cfs max Diversion

(Recommended Plan).................................................. 5-130

5.15.14.2 Flood Control and Hurricane Protection............................................... 5-130

5.15.14.2.1 No Action Alternative (Future Without Project

Conditions) ................................................................... 5-130

5.15.14.2.2 Alternative 1 – 5,000 cfs Diversion.............................. 5-130

5.15.14.2.3 Alternative 2 – 10,000 cfs max Diversion ................... 5-131

5.15.14.2.4 Alternative 3 – 15,000 cfs max Diversion ................... 5-132

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5.15.14.2.5 Alternative 4 – 35,000 cfs max Diversion

(Recommended Plan).................................................. 5-132

5.15.15 Natural Resources........................................................................................................5-133

5.15.15.1 Commercial Fisheries............................................................................ 5-133

5.15.15.1.1 No Action Alternative (Future Without Project

Conditions) ................................................................... 5-133

5.15.15.1.2 Alternative 1 – 5,000 cfs Diversion.............................. 5-133

5.15.15.1.3 Alternative 2 – 10,000 cfs max Diversion ................... 5-134

5.15.15.1.4 Alternative 3 – 15,000 cfs max Diversion ................... 5-135

5.15.15.1.5 Alternative 4 – 35,000 cfs max Diversion

(Recommended Plan).................................................. 5-136

5.15.15.2 Oyster Leases........................................................................................ 5-137

5.15.15.2.1 No Action Alternative (Future Without Project

Conditions) ................................................................... 5-137

5.15.15.2.2 Alternative 1 – 5,000 cfs Diversion.............................. 5-138

5.15.15.2.3 Alternative 2 – 10,000 cfs max Diversion ................... 5-139

5.15.15.2.4 Alternative 3 – 15,000 cfs max Diversion ................... 5-140

5.15.15.2.5 Alternative 4 – 35,000 cfs max Diversion

(Recommended Plan).................................................. 5-141

5.16 HAZARDOUS, TOXIC, AND RADIOACTIVE WASTES ............................................................ 5-142

5.16.1 No Action Alternative (Future Without Project Conditions) ........................................ 5-142

5.16.2 Alternative 1 – 5,000 cfs max Diversion...................................................................... 5-142

5.16.2.1 Direct ...................................................................................................... 5-142

5.16.2.2 Indirect.................................................................................................... 5-142

5.16.2.3 Cumulative ............................................................................................. 5-142

5.16.3 Alternative 2 – 10,000 cfs max Diversion.................................................................... 5-142

5.16.3.1 Direct ...................................................................................................... 5-142

5.16.3.2 Indirect.................................................................................................... 5-142

5.16.3.3 Cumulative ............................................................................................. 5-142

5.16.4 Alternative 3 – 15,000 cfs max Diversion.................................................................... 5-143

5.16.4.1 Direct ...................................................................................................... 5-143

5.16.4.2 Indirect.................................................................................................... 5-143

5.16.4.3 Cumulative ............................................................................................. 5-143

5.16.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan).............................. 5-143

5.16.5.1 Direct ...................................................................................................... 5-143

5.16.5.2 Indirect.................................................................................................... 5-143

5.16.5.3 Cumulative ............................................................................................. 5-143

5.17 UNAVOIDABLE ADVERSE EFFECTS ....................................................................................... 5-143

5.18 RELATIONSHIP OF SHORT-TERM USES AND LONG-TERM PRODUCTIVITY.................. 5-144

5.19 IRREVERSIBLE AND IRRETRIEVABLE COMMITMENTS OF RESOURCES....................... 5-144

5.20 MITIGATION.................................................................................................................................. 5-145

5.21 ENVIRONMENTAL CONSEQUENCES SUMMARY................................................................. 5-145

6.0 PUBLIC INVOLVEMENT ......................................................................................................................... 6-1

6.1 NEPA SCOPING............................................................................................................................... 6-1

6.2 OTHER PUBLIC COMMENTS......................................................................................................... 6-4

6.2.1 Federal and State Agencies............................................................................................. 6-4

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6.2.2 Land Owner, Non-Governmental Organization (NGO), Parish and Other

Involvement....................................................................................................................... 6-5

6.2.3 Public Comments on the Draft SEIS............................................................................... 6-8

7.0 COORDINATION AND COMPLIANCE................................................................................................... 7-1

7.1 USACE PRINCIPLES AND GUIDELINES (P&G)........................................................................... 7-1

7.2 ENVIRONMENTAL COORDINATION AND COMPLIANCE ......................................................... 7-1

7.2.1 U.S. Fish and Wildlife Coordination Act .......................................................................... 7-3

7.2.2 Clean Water Act – Section 404(b)(1) .............................................................................. 7-6

7.2.3 Section 122 of the Rivers and Harbors Act..................................................................... 7-6

7.2.4 Coastal Zone Management Act of 1972 ......................................................................... 7-7

7.2.5 Endangered Species Act of 1973.................................................................................... 7-7

7.2.6 Magnuson-Stevens Fishery Conservation and Management Act of 1996; and

the Magnuson-Stevens Act Reauthorization of 2006 (Essential Fish Habitat) ............. 7-7

7.2.7 Clean Air Act – Air Quality Determination ....................................................................... 7-8

7.2.8 National Historic Preservation Act of 1966...................................................................... 7-8

7.2.9 Farmland Protection Policy Act (Prime and Unique Farmlands) ................................... 7-8

7.2.10 Executive Order 13186 – Migratory Bird Habitat Protection .......................................... 7-8

7.2.11 Executive Order 12898 – Environmental Justice............................................................ 7-9

7.2.12 Executive Order 13112 – Invasive Species.................................................................... 7-9

7.2.13 Executive Order 11990 – Floodplain Management...................................................... 7-10

7.2.14 Executive Order 11988 – Protection of Wetlands......................................................... 7-10

7.2.15 Uniform Relocation Assistance and Real Property Acquisition Policies Act of

1970 (Public Law 91-646).............................................................................................. 7-11

7.2.16 Louisiana State Rare, Threatened, and Endangered Species, and Natural

Communities Coordination............................................................................................. 7-11

7.2.17 Clean Water Act – Section 401 Water Quality.............................................................. 7-11

8.0 CONCLUSIONS AND DETERMINATIONS............................................................................................ 8-1

8.1 AREAS OF CONTROVERSY AND UNRESOLVED ISSUES....................................................... 8-1

8.2 CONCLUSIONS................................................................................................................................ 8-4

8.3 RECOMMENDATIONS .................................................................................................................... 8-5

9.0 DISTRIBUTION LIST AND OTHER ........................................................................................................ 9-1

9.1 DISTRIBUTION LIST ........................................................................................................................ 9-1

9.2 LIST OF PREPARERS ..................................................................................................................... 9-1

9.3 LITERATURE CITED........................................................................................................................ 9-3

9.4 GLOSSARY....................................................................................................................................... 9-9

9.5 ACRONYMS AND ABBREVIATIONS........................................................................................... 9-20

Attachments:

1 Non-Federal Sponsor’s Self-Certification of Financial Capability

2 Non-Federal Sponsor’s Letter of Intent

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Figures

Figure 1.1: Study Area Map .................................................................................................................................... 1-5

Figure 1.2: Other Diversion Projects..................................................................................................................... 1-15

Figure 2.1: Potential Desired Future Condition...................................................................................................... 2-8

Figure 3.1: Land Area Change in Coastal Louisiana after the 2005 Hurricanes (19562005) (USGS).............. 3-5

Figure 3.2: Land Area Trends.................................................................................................................................. 3-6

Figure 3.3: Future Without-Project Condition........................................................................................................ 3-6

Figure 3.4: Relative Sea Level Rise: Medium and High Scenario Impacts on Future Without-Project

Condition............................................................................................................................................. 3-7

Figure 3.5: Potential Diversion Structure Locations............................................................................................. 3-22

Figure 3.6: White Ditch CE/IC AnalysisOpen Diversion................................................................................ 3-33

Figure 3.7: White Ditch CE/IC Analysis Step 1MarchMay Pulse................................................................ 3-34

Figure 3.8: LCA: Medium Diversion at White Ditch Future Without Project Condition.................................. 3-35

Figure 3.9: Relative Sea Level Rise: Medium and High Scenario Impacts on Future Without Project

Condition........................................................................................................................................... 3-36

Figure 3.10: Alternative 1  Location 3 ................................................................................................................ 3-39

Figure 3.11: Alternative 2  Location 3 ................................................................................................................ 3-41

Figure 3.12: Alternative 3  Location 3 ................................................................................................................ 3-42

Figure 3.13: Alternative 4  Location 3 ................................................................................................................ 3-44

Figure 3.14: CE/IC Analysis of Final Alternatives............................................................................................... 3-51

Figure 3.15: CE/IC Best Buy Plans....................................................................................................................... 3-52

Figure 3.16: FWP Acres at TY50 per Operational Plan....................................................................................... 3-53

Figure 3.17: The Recommended Plan as Compared to Evaluated Alternatives and Different Rates of

Projected Sea-Level Rise.................................................................................................................. 3-54

Figure 4.1: LCA White Ditch Existing Condition Salinities  July 2009 ............................................................. 4-9

Figure 4.2: Historic Habitat Analysis of the White Ditch Project Area .............................................................. 4-14

Figure 4.3: Marsh Types in the White Ditch Project Area................................................................................... 4-15

Figure 4.4: LCA White Ditch Boat Launch/Marina............................................................................................. 4-29

Figure 4.5: LCA White Ditch Oil/Gas Wells and Pipelines ................................................................................ 4-40

Figure 4.6: LCA White Ditch Existing Condition Salinities  July 2009 ........................................................... 4-43

Figure 5.1: Sea Level Rise Rates for the White Ditch Study Area........................................................................ 5-5

Figure 5.2: Modeled Salinities Following Maximum Diversions at White Ditch and Caernarvon 

Approximately May 1st Under Our Proposed Operational Scheme.............................................. 5-31

Figure 5.3: Modeled Salinities Two Months After Maximum Diversions at White Ditch and

Caernarvon  Approximately July 1st Under Our Proposed Operational Scheme ....................... 5-33

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Tables

Table 1.1: Relevance of Prior Studies, Reports, Programs, and Water Projects to the MDWD

Feasibility Study ................................................................................................................................. 1-7

Table 1.2: Related Studies That Played a Role in MDWD Project Development.............................................. 1-17

Table 2.1: CWPPRAs Restoration Projects in the Breton Sound Basin.............................................................. 2-2

Table 2.2: Goals and Objectives.............................................................................................................................. 2-8

Table 3.1: Study Area, Medium Diversion at White Ditch.................................................................................... 3-3

Table 3.2: Summary of the Problems, Opportunities, Goals, Objectives and Measures to this Point in

the Planning Process......................................................................................................................... 3-14

Table 3.3: Specific Measures Screened from Further Consideration .................................................................. 3-16

Table 3.4: Conceptual Alternatives Screened from Further Consideration......................................................... 3-20

Table 3.5: Diversion Location Screening.............................................................................................................. 3-26

Table 3.6: LCA: White Ditch Incremental Cost/Cost Effectiveness Step 1a...................................................... 3-31

Table 3.7: LCA: White Ditch Incremental Cost/Cost Effectiveness Step 1b...................................................... 3-32

Table 3.8: Direct Footprint Acreage Impacts........................................................................................................ 3-49

Table 3.9: Benefits Summary*.............................................................................................................................. 3-49

Table 3.10: Acreage Summary.............................................................................................................................. 3-49

Table 3.11: LCA: White Ditch Cost Estimates..................................................................................................... 3-50

Table 3.12: White Ditch Incremental Cost/Cost Effectiveness Step 2................................................................ 3-50

Table 3.13: White Ditch Incremental Cost/Cost Effectiveness Step 2................................................................ 3-51

Table 3.14: Net Increase in Recreation Benefits................................................................................................... 3-53

Table 3.15: ERDC-SAND2 Model Calculations of Acreages for the MDWD Project Area Under

Historical Sea Level Rise Rates ....................................................................................................... 3-55

Table 3.16: ERDC-SAND2 Model Calculations of Acreages for the MDWD Project Area Under the

Intermediate and High Sea Level Rise Rates .................................................................................. 3-55

Table 3.17: Medium Diversion at White Ditch Authorized, Adjusted, and Recommended Plan Cost

Table.................................................................................................................................................. 3-59

Table 3.18: O&MRRR Annualization .................................................................................................................. 3-61

Table 3.19: Cost Sharing........................................................................................................................................ 3-74

Table 4.1: Essential Fish Habitat (EFH) for Various Life Stages for Shrimp, Red Drum, Reef Fish, and

Stone Crab (NMFS Scoping Correspondence, 2009)..................................................................... 4-22

Table 4.2: Fishing Licenses Year 2009................................................................................................................. 4-27

Table 4.3: Hunting Licenses Year 2009................................................................................................................ 4-27

Table 4.4: Boat Registrations Year 2008 .............................................................................................................. 4-28

Table 5.1: Estimated Average Total Load (Tonnes)/Month................................................................................ 5-24

Table 5.2: Estimated Residual N After Wetland Uptake ..................................................................................... 5-25

Table 6.1: Categorization of Scoping Comments by Draft EIS Subject Matter ................................................... 6-4

Table 7.1: Relevant Federal Statutory Authorities and Executive Orders............................................................. 7-2

Table 7.2: Relevant State Statutory Authorities...................................................................................................... 7-3

Table 9.1: List of Preparers...................................................................................................................................... 9-1

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APPENDICES (VOLUME VI)

Appendix A Biological Assessment

Appendix B U.S. Fish and Wildlife Service Coordination Letter and Support (includes WVA Appendix and

revised/updated information on WVA benefits and assumptions)

Appendix C NOAA Fisheries Service Coordination Letter

Appendix D 404(b)(1) Water Quality Report

Appendix E Louisiana Coastal Resources Program Consistency Determination

Appendix F State Historic Preservation Officer Coordination Letter

Appendix G Responses to Comments

Appendix H Value Engineering Study Report

Appendix I Monitoring and Adaptive Management Plan

Appendix J Real Estate Plan

Appendix K Benefit / Cost  Incremental Cost Analysis

Appendix L Engineering Appendix

Appendix M Hazardous, Toxic, and Radioactive Waste Initial Assessment Documentation

Appendix N Qualitative Induced Shoaling Analysis

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Final Integrated ES-1 September 2010

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Executive Summary

ES.1 Summary Introduction and Study Information

Title VII of the Water Resources Development Act (WRDA) 2007 authorizes the Louisiana Coastal Area

(LCA) ecosystem restoration program. Included within that authority are requirements for comprehensive

coastal restoration planning, program governance, a Science and Technology Program, a program for the

beneficial use of dredged material, feasibility studies for restoration plans, project modification

investigations, and restoration project construction, in addition to other program elements. This

authorization was recommended by the Chief of Engineers Report, dated January 31, 2005.

This report is an integrated Feasibility Study and Supplemental Environmental Impact Statement (SEIS)

conducted for the Medium Diversion at White Ditch (MDWD) project. This report fulfills the reporting

requirement to Congress of Section 7006(e)(3), which directs the Secretary of the Army to submit

feasibility reports on the six projects included in that section by December 31, 2008, and authorizes

implementation of the projects provided a favorable Chief of Engineers Report is completed no later than

December 31, 2010.

ES.2 Problems, Need for, Opportunities, and Objectives of

Action for the MDWD Project

The altered supply and distribution of freshwater, lack of sediments, marsh subsidence and human

development in the White Ditch area have resulted in rapid loss of marsh habitat in the MDWD project

area over the past century. Various human activities have resulted in degraded and unbalanced

distribution of freshwater, brackish, and saltwater marsh habitats. Further, the degradation of the existing

marshes has made them more vulnerable to the range of Gulf storm events; extreme and seasonal,

resulting in accelerated degradation, and altered hydrology changed salinity regimes. The threat of

increasing relative sea level rise is compounding these problems.

Wetlands in the project area are deteriorating for several reasons: 1) subsidence, 2) lack of sediment and

nutrient deposition, 3) erosion via tidal exchange, 4) channelization, 5) saltwater intrusion and 6) lack of

freshwater. Recent hurricanes and tropical storms have also caused significant damage to the project area.

These activities have resulted in the loss of several thousand acres of solid, vegetated marsh. It is

expected that the project area will lose thousands of acres of marsh over the 50-year planning horizon.

Deterioration will continue and the system is vulnerable to complete collapse unless preventative

measures are taken.

Based on the available data and the outcome of public scoping meetings, a series of potential desired

futures exists that require consideration by the study team, sponsor, collaborating agencies and citizens.

Early in the planning process a Desired Future Condition was identified as a no net loss of marsh acres

consistent with LCA Planning Goal 2. It should be noted that no net loss was what the Project Delivery

Team (PDT) felt was achievable and desirable given the uncertainty associated with sea level rise and the

constraints of time and availability of information.

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Study goals, objectives, and constraints were developed to comply with the study authority and to respond

to study area problems and opportunities. In consultation with the non-Federal sponsor and other

interested parties, Goals and Objectives were developed in the first quarter of 2009. They are:

Goals and Objectives

Overarching System Goal Objective

Restore and maintain ecological integrity,

including habitats, communities, and

populations of native species, and the processes

that sustain them by reversing the trend of

degradation and deterioration to the area

between the Mississippi River and the River aux

Chenes ridges, so as to contribute towards

achieving and sustaining a larger coastal

ecosystem that can support and protect the

environment, economy, and culture of southern

Louisiana and thus contribute to the economy

and well-being of the nation.

A. Maintain the current area of marsh habitat, of all types

(41,206 acres), that provide life requisite habitat conditions

for native coastal marsh fish and wildlife.

B. Restore adequate freshwater and nutrient inputs into the

project area such that sustainable areas of fresh, intermediate,

brackish and saline marsh are present and existing areas of

marsh acres are maintained.

C. Restore sediment inputs into the project area equivalent to

an average of approximately 1,300,000 cubic yards of

sediment per year.

ES.3 Alternatives

Management measures were developed to address study area problems and to capitalize upon study area

opportunities. Management measures were derived from a variety of sources including prior studies, the

NEPA public scoping process, and the multidisciplinary, interagency project delivery team (IPDT).

The development of alternative plans is described extensively in Chapter 3. Multiple structural measures

and management measures were assessed. Five diversion locations were considered. These were

repeatedly screened to develop the final array.

The alternatives in the Final Array are:

No Action (Future Without-Project Conditions). Over a 50-year period of analysis, if nothing were

done, we would see significant losses of all marsh types throughout the study area. More major storms

could accelerate this loss. As a result open-water habitats would continue to grow allowing for further

intrusion of saltwater into the marsh.

Alternative 1 – 5,000 cfs diversion at Location 3. This alternative involves construction of a structure

capable of diverting up to 5,000 cfs consisting of three 15-ft x 15-ft box culverts. Additionally, 32 acres

of ridge and terrace creation, 139 acres of marsh creation utilizing dredged material from an adjacent 153

acres of canal being reconfigured to convey freshwater, nutrient and sediments. Notched weirs would be

installed in outflow canals to restrict flow into the River aux Chenes and retain diverted water in the

project area. The diversion would be operated fully open only during March and April and run at up to

1,000 cfs for the rest of the year.

Alternative 2 – 10,000 cfs Max Diversion at Location 3. This alternative involves construction of a

structure capable of diverting up to 10,000 cfs consisting of three 15-ft x 15-ft box culverts. Additionally,

32 acres of ridge and terrace creation, 176 acres of marsh creation utilizing dredged material from an

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adjacent 167 acres of canal being reconfigured to convey freshwater, nutrient and sediments. Notched

weirs would be installed in outflow canals to restrict flow into the River aux Chenes and retain diverted

water in the project area. The diversion would be operated fully open only during March and April and

run at up to 1,000 cfs for the rest of the year.

Alternative 3 – 15,000 cfs Max Diversion at Location 3. This alternative involves construction of a

structure capable of diverting up to 15,000 cfs consisting of ten 15-ft x 15-ft box culverts. Additionally,

32 acres of ridge and terrace creation, 235 acres of marsh creation utilizing dredged material from an

adjacent 182 acres of canal being reconfigured to convey freshwater, nutrient and sediments. Notched

weirs would be installed in outflow canals to restrict flow into the River aux Chenes and retain diverted

water in the project area. The diversion would be operated fully open only during March and April and

run at up to 1,000 cfs for the rest of the year.

Alternative 4 – 35,000 cfs Max Diversion (Recommended Plan) at Location 3. This alternative

involves construction of a structure capable of diverting up to 35,000 cfs consisting of ten 15-ft x 15-ft

box culverts. Additionally, 31 acres of ridge and terrace creation, 385 acres of marsh creation utilizing

dredged material from an adjacent 223 acres of canal being reconfigured to convey freshwater, nutrient

and sediments. Notched weirs would be installed in outflow canals to restrict flow into the River aux

Chenes and retain diverted water in the project area. The diversion would be operated fully open only

during March and April and run at up to 1,000 cfs for the rest of the year.

Desired Future Condition

The desired future condition established early on in study development was to achieve no net loss of

marsh acres at the end of the 50-year period of analysis. While it was desirable to maximize the acres of

marsh, it was uncertain if that was possible given the various physical and operational constraints. The

ERDC-SAND2 model is an engineering spreadsheet that predicts sedimentation in a wetland system. The

ERDC-SAND2 model assessed sediment dispersal and was used to generate land creation outputs for the

MDWD project area. The ERDC-SAND2 model outputs along with the hydraulic engineering model

outputs are the key components in the WVA, which is used to generate habitat units. Based on the ERDCSAND2 results, Alternative 4 provided the most net acres at the end of period of analysis. By

implementing Alternative 4, it is possible that the study area could see a return to historic marsh acreages.

Finally, the IC/CE analysis of the final array of alternatives utilized WVA benefits based in part on an

operation regime of Open Diversion during MarchApril with a 1,000 cfs maintenance flow the

remainder of the year. Alternative 4 is the most capable at achieving no net loss. Alternative 3 also has the

potential to achieve no net loss but requires longer pulse durations. Longer pulse duration was viewed by

the PDT and stakeholders as less acceptable.

Relative Sea Level Rise and Sustainability

An analysis of the high sea level rise scenario was conducted utilizing the ERDC-SAND2 model. The

model was used to determine whether a net loss or gain of marsh acreage would occur assuming a high

sea level rise scenario. Alternative 4 was the most effective at countering the effects of high sea level rise.

Alternative 4 could maintain marsh acreage out to approximately year 20 of the analysis which was then

quickly followed by a sharp decline and eventual collapse of the marsh and near total conversion to open

water. This result was based on the MarchApril Pulse plus a 1,000 cfs maintenance flow the rest of the

year. It should be noted however, that in the event high sea level rise becomes a reality, Alternative 4

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alone has the capability (assuming an open diversion) to divert large enough quantities of freshwater,

nutrients and sediments to overcome high sea level rise. While not publicly acceptable at present, if the

collapse of the marsh within the study areas was imminent, then having the ability to respond accordingly

with a year round open diversion would be critical. Alternative 4 is the only alternative capable of

providing a sustainable solution to the high sea level rise scenario

Recommendation of the Recommended Plan

The interagency team recommends Alternative Plan 4 (Location 3  35,000 cfs) as the Recommended

Plan. This alternative best meets the study objectives, is the most flexible, and has the most robust

sustainable capability against relative sea level rise over the length of the 50-year planning horizon.

Alternative Plan 4 has a primary operating regime of a maximum 35,000 cfs pulse during MarchApril

with a maximum 1,000 cfs maintenance flow throughout the remainder of the 12-month cycle (May

February). The pulse regime was chosen because it capitalizes on sediment availability while minimizing

adverse effects to socioeconomic resources. It mimics a natural hydrologic regime.

Alternative 4 meets the four evaluation criteria of the Economic and Environmental Principles and

Guidelines for Water and Related Land Resources Implementation Studies. Alternative 4 provides the

most robust capability for adapting to future risk and uncertainty. Alternative 4 provides the most flexible

management of operations to respond to sea level rise. Based on the ERDC-SAND2 results, Alternative 4

provides the most net acres at the end of period of analysis and it is possible that the study area could see

a return to historic marsh acreages. The current cost is $361,606,000, the total first cost of construction is

$365,201,000, and the fully funded project cost is $387,620,000. It would result in restoration of natural

deltaic processes within the study area. In cooperation with the USFWS, NOAA, and the State of

Louisiana, the Corps has planned and would design a project that serves the needs of the nation.

NER Plan

The NER plan reasonably maximizes ecosystem restoration benefits compared to costs, considering the

cost effectiveness and incremental cost of implementing other restoration options. Alternative 4 Location

3  35,000 cfs, based on all considerations is the NER plan. The NER Plan is supported by the nonFederal sponsor and therefore no locally preferred plan is identified. Additionally, based on the evaluation

conducted as part of this EIS, it has been determined that Alternative 4 Location 3  35,000 cfs, is the

environmentally preferable alternative.

ES.4 Affected Environment

This chapter describes the climate, geomorphic and physiographic setting, and the historic and existing

conditions for important resources.

A resource is considered important if it is recognized by statutory authorities including laws, regulations,

Executive Orders (EO), policies, rules, or guidance; if it is recognized as important by some segment of

the general public; or if it is determined to be important based on technical or scientific criteria. The

following sections discuss historic and existing conditions of each important resource occurring within

the project area.

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Executive Summary Volume VI – Medium Diversion at White Ditch

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Feasibility Study / SEIS

Location and Climate

The MDWD project study area is located in LCA Subprovince 1, and comprises part of the Breton Sound

hydrologic basin in Plaquemines Parish, Louisiana. Plaquemines Parish is located within the Central Gulf

Coastal Plain in southeastern coastal Louisiana. The parish encompasses the current delta of the

Mississippi River, which was built up from alluvial silt deposited over centuries when the river was leveefree and overflowed its banks. Elevations range from sea level along the Gulf Coast, to approximately

+15 feet above sea level along levee ridges. The project area is located within the Mississippi River

Deltaic Plain, with the Mississippi River acting as the primary influence on geomorphic processes in the

delta region. The boundary of the project study area encompasses over 98,000 acres of intermediate to

brackish intertidal wetland habitats. The climate of the project area is subtropical marine with long humid

summers and short moderate winters.

Significant Resources

Significant Resources considered within the development of this Feasibility Report with Integrated SEIS

included soils; coastal vegetation; wildlife; fisheries; plankton; benthos; essential fish habitat (EFH);

threatened and endangered species; hydrology (including flow and water levels, and sediment); water

quality; recreation; public lands; cultural and historic resources; aesthetics; air quality; socioeconomic and

human resources (including population; infrastructure; employment and income; navigation; oil, gas, and

utilities; pipelines; commercial fisheries; oyster leases; and flood control and hurricane protection). In

addition, the characterization of noise and hazardous, toxic, and radioactive waste (HTRW) in the project

area are presented.

ES.5 Environmental Consequences

This chapter describes the potential environmental consequences of implementing alternative plans

considered for freshwater diversion and marsh restoration in the project study area. The following

analysis compares the No Action Alternative to four alternatives carried over for detailed analysis:

Alternative Plans 1, 2, 3, and 4. Alternative 4 is the Recommended Plan. Alternatives developed and

evaluated in this study are described in Chapter 3. A comparison of the direct, indirect, and cumulative

impacts for wetland creation and enhancement is presented. If this diversion were operated fully open

outside the 2-month window that is described in the document, then there could be significantly different

impacts with some potentially being very negative.

No Action Alternative (Future Without Project Conditions)

Direct

The No Action Alternative would have a direct impact on the area between the Mississippi River and

River aux Chenes through the continuation of existing degradation of marsh. The absence of a supply of

freshwater, sediment, and nutrients combined with the ongoing pressures of wind and wave action, storm

surges, and human activities has severely eroded marsh soils and reduced the ability of the project area to

maintain a balance of emergent wetland and shallow water. The project area would continue to be isolated

from natural riverine processes. No opportunities for beneficial use of dredged material for construction

features would occur.

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Existing vegetation resources in the project footprint would continue to degrade and convert to

intermediate marsh. Wildlife habitat would continue to degrade and switch. The project area is recognized

as an important and productive fisheries nursery habitat, and conversion to open water would reduce

availability of this habitat. Juvenile fish and invertebrates are important food sources for migratory birds,

such as wading birds and waterfowl.

There would be no direct impacts to population and housing, minority populations, infrastructure, tax

revenues and property values in the vicinity of the proposed Phoenix diversion site from the No Action

Alternative.

Indirect

Without implementation of the proposed diversion, no increase in input of sediment, freshwater and

nutrients to the project area would occur. This would result in the persistence of existing conditions

including continued erosion of marsh soils, and continued fragmentation and conversion of existing

intermediate, brackish and saline marsh to shallow open-water habitats. Both man-induced and natural

processes would contribute to the continued loss of vegetated habitats, including: continued erosion and

subsidence, increased saltwater intrusion, increased water velocities, and increased herbivory. Over the

next 50 years, approximately 13,750 acres of emergent marsh is projected to be lost, and it is likely that

all remaining remnants of bottomland hardwood vegetation would disappear over the same period.

Continued conversion of emergent marsh to open water is expected to have long-term adverse impacts to

many fish species that depend on estuarine wetlands. The abundances of aquatic organisms would

decrease. The reduction in emergent wetlands would also result in shifts in predator/prey relationships, a

decline in fishery productivity, and reduced recreational fishing opportunities. The loss and deterioration

of transitional wetland habitats over time could continue to indirectly affect, to an undetermined degree,

all Threatened and Endangered species that may potentially utilize the Breton Sound basin including.

In terms of Socioeconomics, there would be no indirect impacts to population and housing, human health,

minority or low-income populations, business and industry, traffic and transportation, public facilities and

services, infrastructure, tax revenues and property, community and regional growth, land use

socioeconomics, water use and supply, or manmade resources. However, there would be indirect impacts

to important Socioeconomic natural resources due to no action. Indirect impacts on natural resources and

commercial fisheries would occur as a result of continuing loss of emergent wetland and increase in

shallow open water. There would be a shift in the populations of fishes and invertebrates, with more

saline-dominated species replacing freshwater species. Over the 50-year planning horizon, habitat for

many commercial fishery species would likewise decline, leading to a net loss in fisheries population size

and diversity. Without implementation of the proposed diversion, indirect impacts on oyster leases would

occur as a result of continuing loss of emergent wetland and increase in shallow open water. This would

likely result in a shift in oyster population toward the middle and upper reaches of the estuary. At the

same time, currently productive oyster leases in the lower portions of the project area would likely

degrade in time as salinity shifts above the optimal. Over the 50-year planning horizon, optimal habitat

for oyster production would likewise decline, leading to a net loss in oyster lease productivity and harvest.

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Alternative 1 – 5,000 cfs max Diversion, Alternative 2 – 10,000 cfs max Diversion,

and Alternative 3 – 15,000 cfs max Diversion

The adverse Direct, Indirect, and Cumulative impacts associated with Alternative 1, Alternative 2, and

Alternative 3 would be similar to those presented for Alternative 4. The reason for this is that most

adverse impacts are associated with construction activities, which would be relatively equivalent

regardless of alternative size. Other negative impacts would be associated with freshening of the basin

and would be relatively equivalent regardless of alternative size.

Positive Direct, Indirect, and Cumulative impacts associated with Alternative 1, Alternative 2, and

Alternative 3 would not equal those provided by Alternative 4. This alternative best meets the study

objectives, is the most flexible, is the most robust, and has the most sustainable capability against relative

sea level rise over the length of the 50-year planning horizon. It would result in restoration of natural

deltaic processes within the study area. Alternative 1, Alternative 2, and Alternative 3 would not fully

satisfy the Goal and Objectives of the project.

Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

Direct

Construction of the 35,000 cfs maximum diversion would directly impact approximately 640 acres in the

intermediate zone (277 acres of marsh and 363 acres of shallow open water). Approximately 223 acres of

marsh and shallow water area would be excavated to enlarge the outfall channel for the structure. This

excavated material would be placed on organic marsh soils and aquatic substrates to create approximately

31 acres of ridges lining the outfall channels, and 385 acres of created marsh in locations adjacent to the

outfall channels.

The direct impact to hydrology of Alternative 4 would be increased water levels and flows within the

project area while the structure is being operated. During operations, Mississippi River water would flow

through natural and man-made channels. This would increase the availability of freshwater, sediments,

and nutrients. The sediments in the waters would be available to help restore areas of open water that

were historically marsh. The areas that would receive the most potential benefits from the sediments

would be the open water areas that are adjacent to Bayou Garelle. It is believed that it would be a

sufficient amount to keep up with the current rate of marsh loss and have the potential for restoring the

marsh back to its historic condition.

Under the 35,000 cfs diversion, no direct impacts to water use and supply or groundwater would occur.

However, it could cause short-term adverse impacts to water quality. These impacts would be minimized

through best management practices (BMPs). Direct impacts to ambient air quality would be temporary

and localized. Construction activities would temporarily cause minor increases in noise levels.

Under the 35,000 cfs diversion alternative, the existing benthic communities in the footprint of the

proposed construction and dredging activities would be lost. However, following construction, benthic

organisms would likely recolonize aquatic habitats in the project area, and the enhancement of freshwater

marsh habitat by the diversion should be beneficial to numerous benthic species. Construction of the

35,000 cfs alternative is expected to have minor short-term impacts to fisheries resources in the

immediate vicinity of the outfall management features. Following construction, displaced fish would

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likely return to the project area. Direct impacts to EFH would include the disturbance and displacement of

managed species in the construction footprint. Construction of the proposed diversion and associated

outfall management features would not jeopardize the continued existence of any listed species or destroy

or adversely modify critical habitat. Construction of the 35,000 cfs diversion alternative and associated

outfall management features would not be expected to adversely affect archaeological sites.

In terms of Socioeconomics, there would be no long-term adverse direct impacts to population and

housing, human health, minority or low-income populations, business and industry, traffic and

transportation, public facilities and services, infrastructure, tax revenues and property, community and

regional growth, agriculture; forestry; public lands; water use and supply; navigation, oil, gas, and

utilities; flood control and hurricane protection; fisheries; and oyster leases. Any short-term impacts

would be minor and inconsequential.

Indirect

Indirect beneficial impacts of implementing the 35,000 cfs max diversion would include the expected

restoration of approximately 20,315 net cumulative acres of emergent marsh soils by year 50 following

construction of the project. Indirect impacts to hydrology would be the inundation of lands while the

structure is being operated. Lands that would not normally be inundated during the period would become

submerged. However, with this submergence there would be an opportunity for the lands to collect

beneficial sediments that are being carried by the diverted Mississippi River water, thus renewing historic

deltaic processes. Increased sediment introduction into the project area would result in the filling-in of

open water areas adjacent to Bayou Garelle.

Increased flows from the diversion would also result in changes to the salinity levels in the Breton Sound

Basin. Flows of freshwater would result in lower salinities across the project area, and beyond River aux

Chenes. These lower salinities would remain for approximately a 3-month period following peak flows

from the diversion. No indirect impacts to water use and supply or groundwater would occur. There could

be both positive and negative effects to water quality. Creation and protection of emergent wetlands

would help to improve local air quality by reducing particulates and gaseous air pollutants. Indirect

impacts due to noise are expected to be localized, temporary, and minor in nature. Operation would

indirectly provide an inflow of freshwater, sediments and nutrients to the project area and redistribute

sediments along existing and created BLH ridges during pulses. An increase in all land types in the

project area is expected to occur with this alternative. Additionally, the ERDC-SAND Model land loss

calculations conducted in support of the WVA assessment of proposed diversion alternatives projected

that the 35,000 cfs diversion would produce an overall gain in land acreage to approximately 59,902 acres

by year 50 after project implementation. Operation of the 35,000 cfs diversion is anticipated to result in

an increase in SAV coverage in the fresh, intermediate, and brackish zones as a consequence of delivery

of nutrients and sediments throughout the project area

There is potential for entrainment of larval and young-of-year (YOY) fish into the marsh and open water

of the project area, including individual specimens of federally listed species such as the pallid sturgeon.

However, no critical habitat for pallid sturgeon has been identified in the vicinity of the White Ditch

project area. While there is a potential for individuals of the species to be adversely affected by

entrainment during operation of the diversion, the proposed project is not considered likely to jeopardize

the continued existence of pallid sturgeon in the lower Mississippi River.

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In terms of Socioeconomics, there would be no distinguishable adverse indirect impacts to population and

housing, human health, minority or low-income populations, business and industry, traffic and

transportation, public facilities and services, infrastructure, tax revenues and property, community and

regional growth, land use socioeconomics, water use and supply, community cohesion, or manmade

resources. In the long term the continued existence of these wetlands would benefit, to some

undetermined level, local employment in wetland-dependent jobs such as commercial and recreational

fisheries, alligator farming, hunting and fishing guide services, and ecotourism; as well as provide

benefits for supporting economic activities such as marinas, bait and tackle shops, and others.

Diversion of river sediment and water with this operating plan is unlikely to substantially increase the

potential for sedimentation and shoaling in the Mississippi River downstream of the diversion, or to

require additional or increased dredging over the 50-year planning horizon. Indirect effects within the

project area resulting from operation of Alternative 4 would include increased water levels within interior

distributaries such as River aux Chenes and Bayou Garelle, and increased inundation of low-lying lands,

particularly when the diversion is operated at maximum capacity. These hydrologic alterations are

expected to distribute and deposit river sediments throughout the project area. No significant adverse

effects on existing Federal or non-Federal levees are expected to result from implementation of this

alternative.

Over the 50-year planning horizon, implementation of Alternative 4 is expected to have large-scale

benefits for commercial fisheries and shellfish operations by restoring and preserving marsh and critical

nursery habitat in the project area. Without project implementation most marsh in the project area will be

lost based on current rates of loss. Although the long-term, large-scale outlook of implementation would

be positive, there would be unavoidable impacts to certain natural resources in the project area.

Alternative 4 would have indirect impacts on commercial fisheries by affecting the location of target

species. Changes in salinity levels in the project area as a result of project operation could change the

distribution of fish and shellfish species based on their salinity tolerance. No broad system-level change in

species density, assemblage, or numbers would be expected. Changes in fisheries distribution could

impact commercial fishing patterns and locations. There is also a potential for some indirect impact on

commercial seafood processing facilities located on the West Bank of Plaquemines Parish if Alternative 4

is implemented. Indirect impacts to oyster leases around this diversion site if Alternative 4 is implemented

could include increased rate of mortality and decrease in productivity in oyster leases located closest to

the diversion site. This could result in a loss of revenue for commercial oyster harvesters on those leases.

Cumulative

Cumulative impacts would be the synergistic effect of the No Action Alternative with the added

combination of similar wetland degradation and wetland loss impacts throughout coastal Louisiana, as

well as the benefits and impacts of other state and Federal coastal restoration projects in the vicinity. The

Caernarvon Diversion does freshen the White Ditch project area, albeit to an unknown extent, and could

potentially impact patterns in and near the study area, but would not likely the study area. The proposed

CWPPRA project for the rehabilitation and expansion of the existing siphon at White Ditch could have

impacts on the project area, but conclusive details as to those extents are not available at this time. Other

diversions along the Mississippi River would collectively have impacts on Mississippi River stages and

possibly sediment and nutrient loads available to the Breton Sound Basin.

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ES.6 Public Involvement

A project kick-off meeting was held on December 12, 2008, and a public scoping meeting was organized

and hosted in accordance with NEPA on February 5, 2009. A scoping meeting announcement requesting

comments on the scope of the MDWD Study was mailed to Federal, State, and local agencies; and

interested groups and individuals on January 7, 2009. The media advisory announcing the scoping

meeting was provided to 350 media outlets. The open house session provided attendees with an

opportunity to visit a series of poster stations staffed by project team members and subject matter experts

regarding the following topics: the LCA plan, the NEPA process and milestones, an overview of the study

and its goals and objectives, as well as maps of the study area. Approximately 26 people attended the

MDWD scoping meeting. A total of 16 multi-part comments were received during the comment period,

of which one was received via e-mail and two were copies of letters. Fourteen individuals expressed

comments at the scoping meeting. A total of three written comments (letter, email, web site) were

received during the comment period. The comments were categorized according to their applicability to

the SEIS.

ES.7 Coordination and Compliance

Coordination and compliance efforts were conducted regarding statutory authorities. These include

environmental laws, regulations, executive orders, policies, rules, and guidance such as the U.S. Fish and

Wildlife Coordination Act, Clean Water Act  Section 401 Water Quality and Section 404(b)(1), Coastal

Zone Management Act of 1972, Magnuson-Stevens Fishery Conservation and Management Act of 1996,

and the Magnuson-Stevens Act Reauthorization of 2006 (Essential Fish Habitat), Clean Air Act, National

Historic Preservation Act of 1966, Farmland Protection Policy Act, Uniform Relocation Assistance and

Real Property Acquisition Policies Act of 1970, Louisiana State Rare, Threatened, and Endangered

Species, and Natural Communities Coordination, and Executive Orders 13186,12898, and 13112. Full

compliance with statutory authorities will be accomplished upon review of the integrated feasibility study

and environmental impact statement by appropriate agencies and the public and the signing of a ROD.

ES.8 Areas of Controversy and Unresolved Issues

During the scoping meeting and throughout the alternative identification and evaluation a number of

issues have been raised regarding diversions in general and those under consideration in the study area.

Every effort has been made to address these concerns and clearly identify the impacts, both beneficial and

detrimental of the alternatives considered. Through public review of the document, most of these issues

were clarified and resolved. However, it is also likely that if construction and operation of the

Recommended Plan were to occur, then these issues would continue to be raised. They are summarized as

follows:

 Joint operation of the proposed White Ditch Diversion with the existing Caernarvon Diversion

would be key to maintaining the condition of the overall Breton Sound ecosystem. These two

projects should not be operated independently of one another. Modeling results and monitoring

data suggests that Caernarvon has the ability to substantially freshen the Breton Sound even

without freshwater inputs from another source. In order for Breton Sound salinities to rebound

after the MarchApril pulse from the White Ditch Diversion, flow from Caernarvon would have

to be closely controlled. This will mean a change to the current operational plan. It will be crucial

that future modeling during PED for White Ditch and during Feasibility for the LCA

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Modification to Caernarvon investigate joint operation. The LCA 4 Modification to Caernarvon

will consider and account for the proposed Medium Diversion at White Ditch project during its

analysis. Additionally the existing and proposed operational plans for both White Ditch and

Caernarvon are subject to refinement based on any newly acquired data. If significant changes are

required, these would be properly disclosed to the public through the NEPA process.

 Potential negative impacts to oysters from over-freshening of the basin. An evaluation of the

impacts to the salinity regimes in the study area was conducted and the areas most important to

commercial oyster harvesting could experience significant changes as a result of the project,

especially if an unfavorable operational regime is implemented. During the PED phase, detailed

and extensive aquatic modeling using the fisheries modeling software will be used to thoroughly

evaluate the potential impacts to fisheries resources, including commercially important species

such as oysters. These results could assist in further refinement of the proposed operational

regime.

 Converting the estuary to fresh/intermediate marsh. Fresh and intermediate marsh types are an

important habitat type in coastal areas and specifically the study area. The loss of these areas has

diminished the ecological integrity of the study area. The restoration of fresh and intermediate

marsh types will not exceed historic trends and is not expected to displace significant areas of

brackish or saline marsh. Additionally the Recommended Plan has the potential to create new

areas of brackish and saline marsh through restoration of the functional processes that create and

sustain them.

 Creating flotant marsh that is not anchored and provides no surge protection. The short duration

of the pulse (MarchApril) operating regime has the potential to saturate existing marsh.

However, due to the relatively short pulsing season, significant habitat switching is not expected

to occur.

 Direct sediment delivery with dredging from the river. The cost of this approach would be

excessive. While building marsh directly would have an immediate benefit, it would not restore

the processes needed to sustain marsh within the study area.

 Impacts to pallid sturgeon. At this time, surveys are being conducted to determine whether pallid

sturgeon are present and if the Recommended Plan will impact the species. Preliminary

indications are that the species is not present; however, the USFWS has not yet made a formal

determination. That information will be available before a public review draft of the report is

completed.

 Creating access and/or land-use problems for private landowners. The Recommended Plan will

have immediate impacts in the area being considered for the location of the structure. Access

during construction may be limited but this would be temporary.

 Did we pick the best spot on the river to capture sediment? Based on the available information,

the supply of sediment at the Phoenix location would be adequate to meet the goals and

objectives of the project and operational requirements of the structure. The information used to

predict project benefits in the ERDC-Sand2 Model came from data obtained from the Belle

Chasse station, which represented the longest continuous dataset from a nearby location. When

comparing the ERDC-Sand2 Model inputs to data that have been collected within the project area

itself, it is seen that the programs estimates are conservative. Data collected by the USGS in the

outfall canal of the existing White Ditch Siphon suggests that more sediment is available to enter

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into the project area than represented by the Belle Chasse Data. Using the Belle Chasse Data, it is

expected that the Recommended Plan will deliver approximately 16,600 tons of sediment per day

into the project area during the MarchApril Pulse. Using the USGS sediment loads and the same

pulse operation, approximately 17,900 tons of sediment per day could enter the project area. This

results in a potential 8% increase in sediment loads from what are currently being projected.

Current research being done by the University of Texas in conjunction with the State of Louisiana

also suggests that there will be further increased sediment concentrations specifically at the

Phoenix site. The Phoenix location of the Recommended Plan was selected because there is a

back-current in flows on the Mississippi River. This will enhance the amount of sediment

available in the area of the diversion as the back-current will continually pull sediments into the

diversion.

Additional analysis will be conducted during PED to determine the best orientation and

placement of the structure within close proximity of its presently proposed location. The project

would not move from the Phoenix location.

 Relative Sea-Level Rise (RSLR). Extensive consideration of RSLR occurred during formulation.

Further, the impacts of the moderate and high sea-level rise scenarios on the Recommended Plan

were evaluated but it should be noted that no evaluated alternative is able to entirely offset the

high rate of sea-level rise.

 Induced shoaling effects and other effects to the navigation/shipping industry. No impacts are

expected to the day-to-day activities of the navigation/shipping industry. A qualitative analysis of

induced shoaling effects is included in Appendix N. Further analysis is recommended during

design to accurately assess and minimize, through the diversion structure design, potential

impacts.

 The Recommended Plan for this project exceeds the cost authorization presented in the 2004

LCA Report. The District Commander recommends seeking additional authorization in order to

construct the Recommended/NER plan; however, the need to request additional authorization has

the potential to impact the project construction schedule.

 Fishery modeling and habitat change modeling will be performed during the PED phase. The cost

and schedule for this will be incorporated into the PMP being developed by the USACE for the

PED Phase. At this time, a SOW is being developed as part of the Donaldsonville to the Gulf

project to look at various models and develop a white paper on the best use of them. The intent of

these models is to support adaptive management of this project.

 If this diversion were operated fully open outside the 2-month window that is described in the

document, then there could be significantly different impacts with some potentially being very

negative.

 The impacts of the Deepwater Horizon oil spill on coastal Louisiana are uncertain at this time

(September 2010). The impacts of the oil spill as well as the various emergency actions taken to

address oil spill impacts (e.g., use of oil dispersants, creation of sand berms, use of Hesco baskets,

rip rap, sheet piling and other actions) could potentially impact USACE water resources projects

and studies within the Louisiana coastal area, including the MDWD project. Potential impacts

could include factors such as changes to existing, future-without, and future-with-project

conditions, as well as increased project costs and implementation delays. The USACE will

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continue to monitor and closely coordinate with other Federal and state resource agencies and

local sponsors in determining how to best address any potential problems associated with the oil

spill that may adversely impact project implementation. Supplemental planning and

environmental documentation may be required as information becomes available. If at any time

petroleum or crude oil is discovered on project lands, all efforts will be taken to seek clean up by

the responsible parties, pursuant to the Oil Pollution Act of 1990 (33 U.S.C. 2701 et seq.).

Ongoing documentation of the impacts associated with the Deepwater Horizon Oil spill can be

found in several governmental sources. The USFWS Situation Report for August 2, 2010

(http://www.fws.gov/home/dhoilspill/pdfs/MondayAugust22010.pdf) indicates the following

environmental-related Deepwater Horizon oil spill information: 563 personnel are actively

engaged in the response, working to protect wildlife and their habitats, including 36 national

wildlife refuges. They are also assessing the damage from the oil spill in preparation for the work

that will be needed to restore the Gulf of Mexico. Some 1,643 visibly oiled birds have been

collected alive by the U.S. Fish and Wildlife Service, the states and our partners in response to the

Deepwater Horizon oil spill. Of those, 594 birds have been rehabilitated and released. Another

1,451 visibly oiled birds have been collected dead. Aerial operations over Louisiana observed an

oil sheen covering 300 acres in the northeastern portion of Barataria Bay. A heavily oiled

coastline covering about one-half mile was found at Bayou Chalond and heavy oil and tar balls

were observed on landfall east of Point-Au-Fer and along Timbalier Island. Beached bird surveys

were conducted in Texas, Louisiana, Mississippi, Alabama and Florida. Aerial missions are

scheduled for Southwest Pass, Chandeleur Islands, Biloxi Marsh, Barataria Bay, Terrebonne,

Marsh Islands, Atchafalaya Delta, Point-Au-Fer and Timbalier Bay.

 Overall number of personnel responding: approximately 30,100

 Total vessels responding: more than 4,500

 Total boom deployed: more than 2,155 miles

 Boom available: more than 856 miles

 Oily water recovered: more than 34.7 million gallons

 Estimated 11.14 million gallons of oil burned

 Estimated total of more than 1.84 million gallons of dispersant used including:

+ Estimated more than 1.07 million gallons surface dispersant used

+ Estimated more than 771,000 gallons of sub-sea dispersant used:

 Estimated approximately 632 miles of Gulf Coast shoreline is currently oiled-approximately

365 miles in Louisiana, 111 miles in Mississippi, 68 miles in Alabama, and 88 miles in

Florida.

The USACE, New Orleans District Regulatory Branch, has considered and responded to

approximately 55 emergency permits related to the Deepwater Horizon oil spill. In addition, the

State of Louisiana is permitted to dredge and fill to construct a six sand berm reaches along the

shoreline of the Chandeleur Islands/Breton National Wildlife Refuge westward to Baptiste

Collette Bayou and along the seaward shoreline of Timbalier Island eastward to Sandy Pont.

Material to construct the berms would be dredged from Ship Shoal, South Pelto, the Mississippi

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River Offshore Disposal Site, Pass a Loutre, St. Bernard Shoal and Hewes Point. Emergency

permits have the following clause that provides for removing, relocating or altering permitted

structures if necessary and upon due notice from the Corps. The clause would pertain to future

actions by the United States, such as proposed Louisiana Coastal Area restoration projects:

The permittee understands and agrees that, if future operations by the United

States require the removal, relocation, or other alteration, of the structure or

work herein authorized, or if, in the opinion of the Secretary of the Army or his

authorized representative, said structure or work shall cause unreasonable

obstruction to the free navigation of the navigable waters, the permittee shall be

required upon due notice from the Corps of Engineers, to remove, relocate, or

alter the structural work or obstructions caused thereby, without expense to the

United States. No claim shall be made against the United States on account of

any such removal or alteration.

As is evident from the numerous ongoing actions, the dynamic nature of the impacts associated

with the Deepwater Horizon oil spill will likely require additional consideration in the near future

for USACE Civil Works projects.

ES.9 Conclusions and Recommendations

The Recommended Plan will restore degraded marsh habitat and impaired deltaic processes that sustain

them between the Mississippi River and River aux Chenes. This will be accomplished by reconnecting

the study area to the supplies of freshwater, nutrients and sediment that have been isolated within the

Mississippi River by the MR&T levee. These benefits are represented by the 13,355 Average Annual

Habitat Units expected from the NER plan at an estimated fully funded cost of $387,620,000 (Appendix

L). When compared to the FWOP in 50 years, the Recommended Plan yields a Net Increase of

approximately 35,000 acres under the current rate of sea level rise. The Recommended Plan is the plan

that best meets the Louisiana Coastal Area goals and objectives as well as those identified for the study

area in partnership with the State of Louisiana. The Recommended Plan is also the plan that best meets

the P&Gs four criteria of completeness, effectiveness, efficiency, and acceptability, as well as the

Environmental Operating Principles of environmental sustainability, interdependence, balance and

synergy, accountability, knowledge, respect, and assessing and mitigating cumulative impacts.

The District Commander has considered all the significant aspects of this study including the

environmental, social, and economic effects, the engineering feasibility, and the comments received from

other resource agencies, the Non-Federal Sponsors, and the public and has determined that the

Recommended Plan presented in this report is in the overall public interest and a justified expenditure of

Federal funds.

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1.0 STUDY INFORMATION

1.1 STUDY AUTHORITY

Title VII of the Water Resources Development Act (WRDA) 2007 authorizes the Louisiana Coastal Area

(LCA) ecosystem restoration program. Included within that authority are requirements for comprehensive

coastal restoration planning, program governance, a Science and Technology Program, a program for the

beneficial use of dredged material, feasibility studies for restoration plans, project modification

investigations, and restoration project construction, in addition to other program elements. This

authorization was recommended by the Chief of Engineers Report, dated January 31, 2005.

SEC. 7003. LOUISIANA COASTAL AREA.

(a) IN GENERAL.-The Secretary may carry out a program for ecosystem restoration, Louisiana Coastal Area,

Louisiana, substantially in accordance with the report of the Chief of Engineers, dated January 31, 2005.

(b) PRIORITIES.—

(1) IN GENERAL.—In carrying out the program under subsection a), the Secretary shall give priority to—

(A) any portion of the program identified in the report described in subsection (a) as a critical

restoration feature;

(B) any Mississippi River diversion project that—

(i) will protect a major population area of the Pontchartrain, Pearl, Breton Sound, Barataria,

or Terrebonne basins; and

(ii) will produce an environmental benefit to the coastal Louisiana ecosystem;

(C) any barrier island, or barrier shoreline, project that—

(i) will be carried out in conjunction with a Mississippi River diversion project; and

(ii) will protect a major population area;

(D) any project that will reduce storm surge and prevent or reduce the risk of loss of human life and the

risk to public safety; and

(E) a project to physically modify the Mississippi River-Gulf Outlet and to restore the areas affected by

the Mississippi River-Gulf Outlet in accordance with the comprehensive plan to be developed under

section 7002(a) and consistent with sections 7006(c)(1)(A) and 7013.

Under the 2007 WRDA Section 7006, the LCA program has authority for feasibility-level reports of six

near-term critical restoration features. The excerpt below from WRDA outlines the project authority for

this report for the Medium Diversion at White Ditch project:

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SEC. 7006. CONSTRUCTION.

(3) PROJECTS SUBJECT TO REPORTS.—

(A) FEASIBILITY REPORTS.—Not later than December

31, 2008, the Secretary shall submit to Congress feasibility

reports on the following projects referred to in the restoration

plan:

(i) Multipurpose Operation of Houma Navigation

Lock at a total cost of $18,100,000.

(ii) Terrebonne Basin Barrier Shoreline Restoration

at a total cost of $124,600,000.

(iii) Small Diversion at Convent/Blind River at a total

cost of $88,000,000.

(iv) Amite River Diversion Canal Modification at a

total cost of $5,600,000.

(v) Medium Diversion at White’s Ditch at a total

cost of $86,100,000.

(vi) Convey Atchafalaya River Water to Northern

Terrebonne Marshes at a total cost of $221,200,000.

(B) CONSTRUCTION.—The Secretary may carry out the

projects under subparagraph (A) substantially in accordance

with the plans and subject to the conditions, recommended

in a final report of the Chief of Engineers if a

favorable report of the Chief is completed by not later than

December 31, 2010.

(4) CONSTRUCTION.—No appropriations shall be made to

construct any project under this subsection if the report under

paragraph (2) or paragraph (3), as the case may be, has not

been approved by resolutions adopted by the Committee on

Environment and Public Works of the Senate.

This report is an integrated Feasibility Study and Supplemental Environmental Impact Statement (SEIS)

conducted for the Medium Diversion at White Ditch (MDWD) project. This report fulfills the reporting

requirement to Congress of Section 7006(e)(3), which directs the Secretary of the Army to submit

feasibility reports on the six projects included in that section by December 31, 2008, and authorizes

implementation of the projects provided a favorable Chief of Engineers Report is completed no later than

December 31, 2010.

1.2 PURPOSE AND SCOPE

In November 2008, the U.S. Army Corps of Engineers (USACE) and the State of Louisiana represented

through the Coastal Protection and Restoration Authority (CPRA), executed a single Feasibility CostShare Agreement (FCSA) covering six LCA near-term plan elements listed in Section 7006(e) of the

Water Resources Development Act (WRDA), 2007. The six features will each go through a separate

feasibility analysis and environmental compliance review culminating in a single master feasibility

document. The cost-share during this feasibility phase is 50% Federal and 50% Non-Federal in total.

However, the individual elements have been divided so that each entity has lead responsibility for

preparing three of the six report components. This means that at the end of the feasibility phase the total

cost will be shared on a 50/50 basis, yet for work on each individual element during the feasibility phase

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the ratio of funds expended by either the Federal or non-Federal sponsor will be higher depending upon

their level of responsibility. Although three of the projects will be lead by state teams, each individual

feasibility component will be conducted and written to meet USACE planning and technical standards for

a feasibility level document.

This document serves as the Final Feasibility Report for the LCA MDWD project. This project was

identified as a Near-term Critical Restoration Feature Recommended for Study and Future Congressional

Authorization in the LCA Main Report dated January 21, 2005. In November 2007, WRDA passed,

authorizing this and other projects from the LCA Main Report. The MDWD feasibility study is

anticipated to result in a Chiefs Report containing a Recommended Plan to construct a Mississippi River

diversion in the vicinity of White Ditch for the purposes of introducing freshwater, sediments, and

nutrients into the study area.

1.3 STUDY AREA

The MDWD project study area is located in LCA Subprovince 1 in the Breton Sound hydrologic basin in

Plaquemines Parish, Louisiana (Figure 1.1). The boundary of the project encompasses over 98,000 acres

of intermediate to brackish intertidal wetland habitats. The study area boundary follows distinct landscape

features beginning in the north with the confluence of the non-Federal back levee and the Forty-Arpent

canal, extending along the non-Federal back levee, the Mississippi River levee, the Federal back levee

and along the left descending natural bank of the Mississippi River to the west; past American Bay,

California Bay, and through Breton Sound, near Bay Gardene to the south; into and along River aux

Chenes to the east, and back to the point of beginning. The area has been significantly impacted by recent

tropical storms and hurricanes and is currently isolated from the effects of the Caernarvon freshwater

diversion, located at the northern end of the Breton Sound basin.

There are two discreet project locations that will be considered for the purposes of the feasibility study:

The area along the Mississippi River where a freshwater diversion structure might be located; and the

project area that could be influenced and benefited by the diverted freshwater. The footprint of both of

these areas will be dependent upon the overall size and capacity of the diversion structure recommended

in the report.

The area of interest where a diversion structure could be located occurs on the left descending bank of the

Mississippi River, between Bertrandville to the north (river mile 69) and the community of Davant to the

south (river mile 51). An area of particular interest for this study is the stretch between White Ditch (river

mile 64.4) and Phoenix (river mile 59.7). This 4.7-mile stretch is unique in that there is no hurricane

protection levee (back levee) on the marsh side that protects existing homes and infrastructure from

elevated water levels (tidal or storm surge). The Mississippi River levee is the only flood protection

structure that keeps river water from entering the project study area. This situation minimizes the amount

of infrastructure that could be affected by construction of a diversion structure and allows for a broader

array of measures to be considered in addressing problems in the project area. The project study area has

been heavily influenced by both man-made and natural processes. Channel construction, subsidence,

erosion, saltwater intrusion, and storm-related damages have all significantly altered the natural

environment, causing extensive losses of wetland habitats.

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1.4 HISTORY OF INVESTIGATION

The MDWD feasibility study is designed to address coastal restoration problems and opportunities in the

project area based on guidance from the LCA Ecosystem Restoration Study completed in 2004. The LCA

effort identified numerous projects that were classified by immediacy of need in order to prioritize efforts

undertaken to eventually achieve Congressional appropriation for construction. An additional nine

projects are identified in WRDA 2007 section 7006 and all projects are scheduled to be included in a

Chiefs Report to be completed by 31 December 2010.

Given the magnitude of Louisianas coastal land losses and ecosystem degradation, it has become

apparent that a systematic approach involving larger projects to restore natural geomorphic structures and

processes, working in concert with smaller projects, will be required to effectively deal with a physical

problem of such large proportions (LCA 2004).

A siphon capable of diverting Mississippi River water up to 250 cubic feet per second (cfs) currently

exists at White Ditch. It was constructed in 1963 to improve oyster and muskrat habitats, but has not been

operated since 1991 except for brief modeling studies and other temporary durations. In addition to the

LCA authority, both the State-developed Louisiana Comprehensive Master Plan for a Sustainable Coast

and the Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) program have diversion

projects identified for further evaluation at White Ditch.

1.5 PRIOR REPORTS AND EXISTING PROJECTS

A number of prior water resources development efforts have been identified as relevant to the MDWD

study. Prominent existing efforts are detailed in Sections 1.5.1, 1.5.2, 1.5.3, 1.5.4, and Attachment B. The

relevance of these reports is reflected in Table 1.1.

1.5.1 Federal

Several comprehensive planning efforts have significance to the MDWD Feasibility Study, including the

Coast 2050 Plan; LCA Ecosystem Restoration Study; Louisianas Comprehensive Master Plan for a

Sustainable Coast; and the LACPR technical report. These comprehensive planning efforts are described

below.

Coast 2050 Plan, 1999. In 1998, Federal and State agencies, local governments, academia, numerous

non-governmental groups, and private citizens participated in developing the Coast 2050 Plan, a

conceptual plan for restoration of the Louisiana coast. The Plan was a direct outgrowth of lessons learned

from implementation of restoration projects through the CWPPRA and other programs, and reflected a

growing recognition that a more comprehensive systemic approach to restoring coastal wetlands was

needed. The Plan formed the basis for the May 1999 905(b) reconnaissance report that preceded the LCA

Ecosystem Restoration Study that recommended the MDWD project.

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1-5

Figure 1.1: Study Area Map

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Table 1.1: Relevance of Prior Studies, Reports, Programs, and Water Projects

to the MDWD Feasibility Study

Prior Studies, Reports, Programs, and Water Projects

Relevance to Medium

Diversion at White Ditch

Data Source

Consistency

Structural

Measurements

Non-Structural

Measures

Future Without

Project

Condition

Mississippi River and Tributaries (MR&T), 1928 X X X

New Orleans to Venice, Louisiana Hurricane

Protection, 1962 X X X

Hydrologic and Geologic Studies of Coastal Louisiana, LSU

1973 X X

Deep-Draft Access to the Ports of New Orleans and Baton

Rouge, Louisiana, 1981 X

Louisianas Eroding Coastline: Recommendations for

Protection, EPA 1982 X X X X X

Mississippi Deltaic Plain Region Ecological Characterization,

USFWS 1982 X X

Proceedings of the Conference on Coastal Erosion and Wetland

Modification in Louisiana: Causes, Consequences, and Options,

1982

X X

Mississippi and Louisiana Estuarine Areas, 1984 X X

Louisiana Coastal Area, Hurricane Protection, 1988 (Draft) X X

Louisiana Coastal Wetlands Conservation, Restoration and

Management Act, Act 6 1989 X X X

The Coastal Wetlands Planning, Protection and Restoration Act

(CWPPRA), 1990 X X X X X

Whites Ditch Diversion Siphon  Outfall Management Plan

Feasibility Report (1992) X X X X

An Environmental- Economic Blueprint for Restoring the

Louisianan Coastal Zone: The State Plan for the Wetlands

Conservation and Restoration Authority, 1994

X X X X X

A White Paper- The State of Louisianas Policy for Coastal

Restoration Activities, 1995 X X X

Coast 2050, 1999 X X X X X

Mississippi River Sediment, Nutrient and Freshwater

Redistribution Feasibility Study, 2000 X X

LCA Ecosystem Restoration Study, 2004 X X X X X

Act 8 of the First Extraordinary Session of 2005 X

Drawing Louisianas New Map: Addressing Land Loss in

Coastal Louisiana, 2006 X X

Louisianas Comprehensive Master Plan for a Sustainable

Coast, 2007 X X X X X

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Table 1.1, concluded

Prior Studies, Reports, Programs, and Water Projects

Relevance to Medium

Diversion at White Ditch

Data Source

Consistency

Structural

Measurements

Non-Structural

Measures

Future Without

Project

Condition

Louisiana Coastal Protection and Restoration (LACPR), 2009 X X X X X

Bonnet Carré Spillway X X X X

CWPPRA Projects Constructed or Authorized for Design X X X X X

Greater New Orleans Hurricane and Storm Damage Risk

Reduction System (GNOHSDRRS) X X X X

Various Environmental Assessments (EAs) Prepared by the

USACE X X X X X

Louisiana Coastal Area (LCA), 2004. In 2000, the USACE and State of Louisiana initiated the

Louisiana Coastal Area Ecosystem Restoration Study to address Louisianas severe coastal land loss

problem. The goal of LCA is to achieve and sustain a coastal ecosystem that can support and protect the

environment, economy, and culture of coastal Louisiana and thus, contribute to the economy and wellbeing of the nation. The LCA study focused on lessons learned from previous Louisiana coastal

restoration efforts, the Coast 2050 restoration strategies, and the best available science and technology to

develop a plan addressing the most critical coastal ecological needs. This study recommended the

MDWD project.

Louisiana’s Comprehensive Master Plan for a Sustainable Coast, 2007. The Louisiana Legislature,

through Act 8 of the First Extraordinary Session of the 2005 Louisiana Legislature, established the

Coastal Protection and Restoration Authority (CPRA) to develop, implement, make reports on, and

provide oversight for a comprehensive coastal protection master plan and annual coastal protection plans.

A diversion at White Ditch is identified as a restoration concept for restoring natural processes in the

Delta Plain and maintaining critical landscape features.

Louisiana Coastal Protection and Restoration (LACPR), 2009. The Louisiana Coastal Protection and

Restoration technical report includes analysis and design for coastal restoration and Category 5

hurricane risk reduction. The USACE submitted a Preliminary Technical Report to Congress in July 2006

and a draft final report is now in Independent External Peer Review. The LACPR report identifies the

MDWD area as a key location for marsh creation though it does not recommend a Mississippi River

diversion in the area.

Prior Studies, Reports, and Projects

In addition to the comprehensive planning efforts described above, the studies, reports, and projects listed

in Table 1.1 have been identified as potentially relevant to the MDWD study. A brief description of

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relevant prior studies and reports and National Environmental Policy Act (NEPA) documents is provided

below.

Related Laws and Programs

Over the past three decades, both the Federal Government and the State of Louisiana have established

policies and programs that are intended to halt and reverse the loss of coastal wetlands and to restore and

enhance ecosystem function.

Federal Laws and Programs

Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA), 1990. The CWPPRA of

1990 was the first Federal statutory mandate for restoration of Louisianas coastal wetlands. The

CWPPRA Task Force is composed of five Federal agencies: U.S. Environmental Protection Agency

(USEPA), U.S. Fish and Wildlife Service (USFWS), USACE, National Marine Fisheries Service

(NMFS), and Natural Resources Conservation Service (NRCS); and the State of Louisiana. The initial

priority of the task force was to prepare a comprehensive restoration plan that would coordinate and

integrate coastal wetlands restoration projects to ensure the long-term conservation of coastal wetlands of

Louisiana. The plan was adopted in 1993.

The task force is also required to prepare an annual Project Priority List (PPL). CWPPRA provides funds

annually for coastal restoration planning and the construction of coastal protection and restoration

projects. As of April 2009, 146 active CWPPRA projects have been approved, 77 have been constructed,

17 are under construction, and 30 have been de-authorized or transferred to other programs. The

CWPPRA program anticipates receiving $84 million in Federal funds for Fiscal Year 2009 (FY 2009).

The CWPPRA program has authorized the White Ditch Resurrection and Outfall Management project for

Phase I funding as part of PPL-14.

1.5.2 State

Coastal resource management in Louisiana formally evolved once Louisiana adopted and began

participating in the Federal Coastal Zone Management (CZM) program in 1978. Shortly thereafter, the

State developed a coastal zone management plan. One of the primary objectives of this plan was to ensure

that future development activities within the coastal area would be accomplished with the greatest benefit

and the least amount of environmental damage. The Plaquemines Parish Government operates its own

CZM program in accordance with State and Federal regulations and adheres to the policy of minimizing

environmental damages from approved projects. Any final MDWD project recommendations must be in

compliance with the Parish and State CZM program.

Louisiana Coastal Wetlands Conservation, Restoration and Management Act, 1989. In 1989, the

constitution of the State of Louisiana was amended with passage and voter approval of Act 6 (LA. R.S.

49:213 et seq.), also known as the Louisiana Coastal Wetlands Conservation, Restoration and

Management Act. Act 6 designated the Louisiana Department of Natural Resources (LDNR) as the lead

State agency for the development, implementation, operation, maintenance, and monitoring of coastal

restoration projects. LDNR had the lead for the development and implementation of State-sponsored

coastal restoration projects.

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Act 6 also created the Wetlands Conservation and Restoration Fund (WCRF), which dedicates a portion

of the States revenues from severance taxes on mineral production (e.g., oil and gas) to finance coastal

restoration activities and projects. Currently, the WCRF provides approximately $25 million per year to

support coastal restoration activities and projects. Act 6 requires the State to prepare and annually update

a Coastal Wetlands Conservation and Restoration Plan. This plan provides location-specific

authorizations for the funding of coastal restoration projects from the WCRF.

Act 8 of the First Extraordinary Session of 2005. In November 2005, Act 8 of the First Extraordinary

Session of 2005 created the CPRA and charged it with coordinating the efforts of local, State, and Federal

agencies to achieve long-term and comprehensive coastal protection and restoration. The CPRA created a

Master Plan to integrate what had previously been discrete areas of activity: flood control and wetland

restoration. The Master Plan identifies a diversion at White Ditch in several of its concept alternatives.

1.5.3 Local

Non-governmental organizations (NGOs) have also participated in various coastal restoration projects.

Public and private parties involved in wetlands preservation or restoration activities in coastal Louisiana

include Coastal America, Corporate Wetlands Restoration Partnership, Gulf Coast Joint Venture,

Audubon Society, National Fish and Wildlife Foundation, The Nature Conservancy, and the National

Wildlife Federation. These efforts are primarily concerned with preservation. The restoration activities of

these organizations may support the overall goals of the MDWD project; however, these efforts are small

in scale and will not appreciably influence plan formulation.

The Lake Pontchartrain Basin Foundation (LPBF) and the Coalition to Restore Coastal Louisiana (CRCL)

are both active and prominent NGOs that have taken an interest in the development of the MDWD study.

The LPBF has developed several plans that rely on alternatives that could be constructed in the White

Ditch area.

 Multiple Lines of Defense Strategy

 Pontchartrain Coastal Lines of Defense Plan

 Comprehensive Habitat Management Plan

Public scoping comments were also received from both organizations that propose a large spillway-type

structure that is capable of delivering significant amounts of freshwater and sediments to the project area

(see Appendix A).

Related Water Projects

Several existing and authorized navigation, river flood control, hurricane storm surge risk reduction and

coastal restoration projects are related to the MDWD Feasibility Study. These projects are briefly

described below.

River Flood Control Projects

Mississippi River and Tributaries (MR&T), 1928. The MR&T is a comprehensive project for flood

control on the lower Mississippi River below Cape Girardeau, Missouri. The MR&T has four major

elements: levees, floodways, channel improvement and stabilization, and tributary basin improvements.

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The MR&T system controls and confines the river system before it reaches the coastal area. Any location

for a diversion from the Mississippi River in the vicinity of White Ditch will be situated on the MR&T

levee.

Bonnet Carré Spillway, 1931. The Bonnet Carré Spillway is located at the site of an old crevasse, and

contains a flood control structure at the Mississippi River that was completed in 1931. The facility is

designed to convey a maximum of 250,000 cfs of floodwater to Lake Pontchartrain to relieve flood

conditions downstream. The spillway could serve as a guide in the design of the MDWD project and this

concept was submitted for consideration during the public scoping process.

Hurricane Storm Surge Risk Reduction Projects

Greater New Orleans Hurricane and Storm Damage Risk Reduction System. The Hurricane and

Storm Damage Risk Reduction System (HSDRRS) for Greater New Orleans consists of more than 200

projects forming a comprehensive system of levees, floodwalls, gates, internal drainage and pumping

stations and other structures, integrated into a single system designed to reduce the risk of hurricane and

storm damage to the Greater New Orleans area. It is located in southeastern Louisiana and includes all or

a portion of six parishes: Jefferson, Orleans, St. Bernard, St. Charles, Lafourche and Plaquemines. The

HSDRRS is integrated with the Mississippi River flood system along the main stem of the Mississippi

River which protects against riverine flooding. The HSDRRS is designed to perform as an integrated

system when completed.

Coastal Restoration Projects

Bonnet Carré Freshwater Diversion. In the 1984 Mississippi and Louisiana Estuarine Areas:

Freshwater Diversion at Lake Pontchartrain Basin and Mississippi Sound feasibility study, various

alternative locations were considered for diverting river water into the Basin at Bonnet Carré and Violet,

both alone and in combination with other diversions. The diversion at Bonnet Carré was selected as the

preferred alternative, largely due to cost considerations. The Assistant Secretary of the Army for Civil

Works [ASA(CW)] transmitted the final feasibility report and Environmental Impact Statement (EIS) to

Congress in September 1989. The Design Memorandum was submitted to USACE headquarters in

October 1990, approved in November 1991, and the ASA(CW) concurred in January 1993. An

Environmental Assessment (EA) evaluating water quality impacts to Lake Pontchartrain was developed

following a re-assessment of the project, and a Finding of No Significant Impact (FONSI) was signed in

July 1996. The State of Louisiana replied to USACE in July 1996, declining to participate further in the

project due to concerns about adverse impacts to water quality in Lake Pontchartrain.

Davis Pond Freshwater Diversion. The Davis Pond diversion structure is located on the west bank of St.

Charles Parish and is capable of diverting up to 10,650 cfs of Mississippi River water into a large ponding

area to help control salinity levels in the Barataria Bay hydrologic basin. Construction of the project

began in 1997 and it began operations in 2002. The project was authorized by the Flood Control Act of

1965 and modified by WRDA in 1974, 1986, and 1996. The Davis Pond project, like Caernarvon, fits

within the MDWD authorized project capacity of 5,000 to 15,000 cfs. Davis Pond is currently

experiencing design modifications that could serve as a reference in designing the MDWD project.

Caernarvon Freshwater Diversion and Outfall Management. The Freshwater Diversion to the

Barataria and Breton Sound Basins report and subsequent technical appendices (USACE 1984),

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recommended diverting Mississippi River water into the Breton Sound Basin near Caernarvon to increase

habitat quality and improve fish and wildlife resources. The Caernarvon Freshwater Diversion was

completed in 1991 with a design discharge of 8,000 cfs. Since its construction, the Caernarvon structure

has been operated as a salinity control measure. The design and operation of this project served as a

reference for development of the MDWD project.

The Water Resources Development Act of 2007, Section 7006(e)(1)(C), authorized a study to identify

changes in the operation of the Caernarvon project to increase wetland creation and restoration outputs for

this structure. The introduction of additional freshwater would facilitate organic and sediment deposition,

improve biological productivity, and prevent further deterioration of the marshes. The present structure,

constructed in 1991, can divert up to 8,000 cfs of freshwater; however, the actual amount of diverted flow

depends on a detailed annual operational plan which correlates with projected river stages and

hunting/migrating seasons. The proposed restoration feature study would assess changes in the operation

of the Caernarvon project to increase wetland creation and restoration outputs for this structure. Modified

operation of this structure would allow an increase in the freshwater introduction rate, perhaps 5,000 cfs

(178 cms) on average, to accommodate the wetland building function of the system. This study would

identify any changes to this features operation that would increase restoration outputs. The proposed

project will also investigate the economical effects of commercial fisheries and the environmental impacts

of aquatic wildlife and vegetation due to the possible deviating operational schedule. A Chief of

Engineers report is scheduled for completion by November 2011.

Bertrandville Siphon. The Bertrandville Siphon project was recently authorized for Phase I engineering

and design under the CWPPRA program in January 2009. This project is located to the north of the

MDWD project on the eastbank of Plaquemines Parish and proposes to construct a siphon to divert water

from the Mississippi River into surrounding wetlands. The capacity of the structure is proposed at 1,000

cfs and it is under development by the USEPA and the State of Louisiana.

Naomi Siphon and Outfall Management. The Naomi Siphon and Outfall Management project is

comprised of two separable elements: the siphon, which is capable of diverting up to 2,100 cfs; and

hydrologic control features consisting of two fixed crest rock weirs to retain sediments in the system and

help prevent saltwater intrusion into the project area. The siphon was completed in 1992 and the outfall

management features were completed in 2002. Although this project is located on the westbank of

Plaquemines Parish, its location is near where the MDWD could be located. The Naomi Siphon could

serve as a guide for design and implementation of the MDWD project.

White Ditch Resurrection and Outfall Management. A siphon built in 1963 at White Ditch to deliver

freshwater for oyster and muskrat habitat has ceased operation due to age and various other

complications. The rehabilitation or replacement of the existing siphon at White Ditch and the

construction of an additional siphon of similar size is proposed through CWPPRA. Phase I engineering

and design funds have been appropriated and the NRCS and the State of Louisiana are developing project

details. The projects proposed strategies also include installing a water control structure in the White

Ditch outfall channel at the junction with River aux Chenes to force water into interior marshes. The

MDWD project team and NRCS are coordinating the development of both projects.

West Pointe à la Hache Siphon and Outfall Management. The existing siphon consists of eight 72-

inch siphon tubes capable of diverting up to 2,144 cfs of freshwater from the Mississippi River into the

~17,000 acre project area. Outfall management measures consist of earthen plugs, rock weirs, and spoil

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bank maintenance. The project area is suffering from significant loss of wetland habitat due to a variety of

factors including subsidence, the absence of freshwater and sediments, canal dredging, and saltwater

intrusion. Construction of the project features will help to re-establish Spartina patens, the target plant

species, in the project area. This project is located on the westbank of the Mississippi River in

Plaquemines Parish and could serve as a guide for design of the MDWD project.

Bohemia Mississippi River Reintroduction. The Bohemia Mississippi River Reintroduction project was

authorized for Phase I engineering and design funding under the CWPPRA program in October 2007.

This project seeks to connect an existing canal to the Mississippi River allowing up to 10,000 cfs to flow

through the uncontrolled diversion. A gap would be cut through the natural bank of the River and

maintenance dredging would take place in the canal to facilitate the increased flow of freshwater. The

project is located south of the MDWD project on the eastbank of the Mississippi River in Plaquemines

Parish and could be used as a reference source for data and design considerations.

Bayou Lamoque Freshwater Diversion. Two large freshwater diversion structures are located at Bayou

Lamoque on the eastbank of the Mississippi River in Plaquemines Parish: one built in 1955 capable of

diverting 4,000 cfs of river water and one built in 1978 capable of diverting 8,000 cfs. These structures

were operated periodically by the Louisiana Department of Wildlife and Fisheries (LDWF) until 1994.

Neither structure is officially managed because of repair and operation issues and the lack of an

interagency management plan. Improvements to the structures were proposed through CWPPRA, and are

currently being developed with Coastal Impact Assistance Program (CIAP) funding. The structures could

be used as a data and design reference in developing the MDWD project.

Delta Building Diversion North of Fort St. Philip. The wetlands in the area are deteriorating from

erosion, subsidence, and insufficient sediment input. Some delta building is occurring in the downstream

end of the project area from Mississippi River overbank flow. However, most of the project area is

deteriorating from a lack of sediment. The proximity of open, shallow, estuarine water to the Mississippi

River, coupled with the low level of development and infrastructure at this site, presents a rare

opportunity to construct a sediment diversion project for a reasonable construction cost. The size of the

diversion channel was designed to allow enough sediment through to create about 624 acres of marsh

over the project life. This project has significantly increased sediment input into the benefited wetlands

through the diversion of about 2,5005,000 cfs of Mississippi River water. This project could serve as a

guide for design and operation for the MDWD.

Benney’s Bay Sediment Diversion. The objective of the project is to restore vegetated wetlands in an

area that is currently shallow open water. The project would divert sediments in an effort to create,

nourish, and maintain approximately 5,828 acres of fresh to intermediate marsh in the Benneys Bay area

over the 20-year project life. The project consists of a conveyance channel for the large-scale diversion of

water and sediments from the river. The conveyance channel would be constructed in two phases: (1)

construction of an initial channel with an average discharge of 20,000 cfs; (2) after a period of intensive

monitoring, enlargement of the channel to a 50,000 cfs discharge. Material from the construction of the

channel would be used to create wetlands in the diversion outfall area. This project is currently being

designed. This project could serve as a guide for design of the MDWD.

West Bay Diversion. The diversion site is located on the west bank of the Mississippi River, in

Plaquemines Parish, Louisiana, 4.7 miles above Head of Passes. The project diverts Mississippi River

water and sediments into West Bay. The project consists of a conveyance channel for the large-scale

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diversion of sediments from the river. Material from the construction of the initial channel was used to

create wetlands in the diversion outfall area. This project could serve as a guide for design of the MDWD

despite recent developments by the CWPPRA Task Force that mandate its closure in 2011 due to negative

induced shoaling effects on a nearby anchorage area.

Myrtle Grove Diversion. The 2004 LCA Ecosystem Restoration study considered diversions of various

sizes (5,000 cfs, 15,000 cfs, 38,000 cfs with sediment enrichment, 75,000 cfs with sediment enrichment,

and 150,000 cfs with sediment enrichment) at Myrtle Grove for inclusion in the near-term restoration

plan. The 2005 Report of the Chief of Engineers recommended that a diversion with a capacity between

2,500 and 15,000 cfs with dedicated dredging be authorized for construction at Myrtle Grove contingent

upon approval of a feasibility level of detail report by the Secretary of the Army. The project was

authorized for construction contingent on preparation of a construction report in section 7006(c) of the

WRDA 2007. A diversion at Myrtle Grove was approved for study under the CWPPRA program in 2001

and deauthorized in 2008. The State of Louisiana has continued to conduct hydrologic modeling of the

proposed diversion. The diversion would provide additional sediment and nutrients to nourish highly

degraded existing fresh to brackish wetlands in shallow open-water areas of mid- and lower Barataria

Basin. Dedicated dredging (from the Mississippi River) at the rate of approximately 2 million cubic

yards/year for several years with the new structure would provide for the projected creation of up to

19,700 acres of new wetlands over the project life. The LCA White Ditch team has coordinated modeling

of the White Ditch diversion with the state's Myrtle Grove modeling team because the two diversions may

be located across from one another on the Mississippi River. A feasibility study on the Myrtle Grove

diversion was initiated under the LCA program in July 2010.

Existing Studies

A summary of studies and analyses performed on other projects is described in Table 1.2 and shown on

Figure 1.2. Information gleaned from these studies was used as a basis for determining measurable

metrics in the project objectives and for ensuring assumptions made regarding inputs to the hydraulic

model and the ERDC-SAND2 model were sound. Not all studies listed in the table played a significant

role in project development, but they were considered and applied where appropriate.

1.6 PLANNING PROCESS AND REPORT ORGANIZATION

The Medium Diversion at White Ditch project follows the USACEs six-step planning process specified

in Engineering Regulation (ER) 1105-2-100. The planning process identifies and responds to problems

and opportunities associated with the Federal objective and specified State and local concerns. This

integrated report includes elements of both the planning process and sections specific to the NEPA review

of the project.

The chapter headings and order in this report generally follow the outline of the required NEPA

documentation for an EIS. Chapters of the report relate to the six steps of the planning process in ER

1105-2-100 as follows:

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Figure 1.2: Other Diversion Projects

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Table 1.2: Related Studies That Played a Role in MDWD Project Development

Study Name Study Focus Relevant Information How Used?

River Diversions and

Shoaling (Letter, Jr. et al.)

Mississippi River Examines the effects of how

freshwater and sediment diversions

affect shoaling rates and subsequent

dredging in the lower Mississippi

River.

This study was

referenced as a

supplement to the

qualitative shoaling

analysis (Appendix N).

Defining Restoration

Targets for Water Depth

and Salinity in WindDominated Spartina Patens

Coastal Marshes (Nyman,

et al.)

South-central and

southwest

Louisiana

intermediate

marshes

Discusses the effects of predicted

vs. observed water levels and

salinities on the productivity of

marshes dominated by Spartina

patens.

This study was

considered in

conjunction with the

MDWD pulsing scheme

and maintenance flow

scenarios.

The Decline in the

Suspended Load of the

Lower Mississippi River

and its Influence on

Adjacent Wetlands (Kesel)

Lower Mississippi

River and the

Mississippi River

Delta

Analyzes the relatively recent trends

of decreasing sediment loads in the

Mississippi River due to factors

such as reservoir construction

upriver and land-use changes.

Data was considered as

inputs were determined

for use in ERDCSAND2 model runs.

The Effect of

Environmental Forcing on

the Suspended Sediment

Within the Naomi

Wetlands as Reflected in

Turbidity Data (McGraw)

Marshes

surrounding the

Naomi Siphon

Analyzes the forcing functions that

affect the input and distribution of

sediment in a system from a

freshwater diversion.

Data was used to

consider outfall channel

and management

arrangements as well as

pulsing strategies.

Mississippi River

Sediment, Nutrient, and

Freshwater Redistribution

Study (CWPPRA)

Mississippi River

Deltaic Plain and

tributaries

Evaluates numerous diversion

structures and locations in addition

to sediment and nutrient load in the

Mississippi River.

This study was used

both in developing an

array of diversion

alternatives and the

qualitative shoaling

analysis (Appendix N).

Pulsed River Flooding

Effects on Sediment

Deposition in Breton

Sound Estuary, Louisiana

(Wheelock)

Upper Breton

Sound estuary and

Caernarvon

diversion

Sediment accretion rates were

documented at and around the

diversion structure and analysis

looked at how to operate diversions

to capture as much sediment as

possible.

The study was used to

assess input

assumptions for the

ERDC-SAND2 model,

consider different

pulsing techniques, and

distribute flows

throughout the study

area.

Abatement of Wetland

Loss in Louisiana Through

Diversions of Mississippi

River Water Using Siphons

(Roberts et al.)

Central River aux

Chenes sub-area of

the Breton Sound

basin

The existing White Ditch siphon

was studied to determine sediment

accretion rates and spatial

distribution of introduced

sediments.

Study was referenced

for known sediment

loads in the Mississippi

River, pulsing schemes,

and outfall channel

arrangements.

Current and Historical

Sediment Loads in the

Lower Mississippi River

(Thorne et al.)

Lower Mississippi

River

Observed sediment loads (with

variability) in the Mississippi River

were documented for current and

historic trends.

The study was

considered as a source

of sediment inputs,

capacity needs for landbuilding, and when to

focus pulsing events.

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Table 1.2, cont’d

Study Name Study Focus Relevant Information How Used?

The Impacts of Pulsed

Reintroduction of River

Water on a Mississippi

Delta Coastal Basin (Day

et al.)

Upper Breton

Sound estuary and

Caernarvon

diversion

Relates the importance of diversion

discharge timing, over-marsh sheet

flow, and water distribution to

maximize effectiveness.

The study was used to

assess input

assumptions for the

ERDC-SAND2 model,

consider different

pulsing techniques, and

distribute flows

throughout the study

area.

The Use of Large Water

and Sediment Diversions in

the Lower Mississippi

River (Louisiana) for

Coastal Restoration

(Allison et al.)

Lower Mississippi

River

Focuses on river-side mechanics

including analyzing sediment loads

and the importance of structure

location for maximizing restoration

opportunities.

Data utilized in

coordination with

Myrtle Grove diversion

development, sediment

suspension in the river

and diversion potential.

Sediment Discharge into a

Subsiding Louisiana

Deltaic Estuary Through a

Mississippi River

Diversion (Snedden et al.)

Upper Breton

Sound Estuary and

Caernarvon

diversion

Report stresses the importance of

timing pulsed diversions to

maximize sediment introduction

and also examines the distribution

of sediments within the system.

Study was considered in

conjunction with

proposed pulsing

operations and design of

the distribution

network.

Chapter 2: Need For and Objectives of Action. This chapter addresses the first step in the planning

process. In the first step of the planning process, the study area problems and opportunities are defined in

addition to the constraints, goals, and objectives. An initial statement of problems and opportunities was

developed for the 2004 LCA report which reflected the priorities and preferences of the Federal

Government, non-Federal sponsor, and other stakeholders. This report presents an updated problem

identification that includes enhanced understanding of the process and problems of the study area.

Chapter 3: Alternatives. The third chapter of this report addresses the third, fifth, and sixth steps in the

planning process. Step three of the planning process is the formulation of alternative plans. During this

step, the plans developed in the 2004 LCA report were reevaluated. The fifth step in the planning process

addresses comparisons of the alternative plans with emphasis on the outputs and affects each alternative.

During the sixth step of the planning process, the selection of the Recommended Plan is made based upon

the comparison of the alternative plans.

Chapter 4: Affected Environment. The fourth chapter of this report addresses the second step of the

planning process which requires an inventory and forecast of resources within the study area. The

inventory and forecast of the study area provides the without project condition and is the basis of

comparison for the alternatives.

Chapter 5: Environmental Consequences. The fifth chapter of this report covers the fourth step of the

planning process which evaluates the effects of the proposed alternative plans in terms of ecosystem

benefits. The evaluation criteria are based on the overall goals and objectives of the LCA program and

specific planning objectives and purposes of the near-term critical restoration projects recommended in

the 2005 Chief of Engineers Report.

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1.7 USACE CAMPAIGN PLAN

The USACE has developed a Campaign Plan with a mission to provide vital public engineering services

in peace and war to strengthen our nations security energize the economy and reduce risk from

disasters. This Campaign plan is shaping USACE command priorities, focusing transformation

initiatives, measuring and guiding progress, and helping the USACE adapt to the needs of the future.

USACE Campaign Plan Goals and Objectives Summary

 Goal 1: Deliver USACE support to combat, stability and disaster operations through forward

deployed and reach back capabilities.

 Objective 1a: USACE is ready, responsive and reliable in delivering high performance, all

hazard, contingency mission execution in a world-wide theater of operations.

 Objective 1b: Prepare Theater Engineer Commands (TEC) to support Combatant

Commanders throughout the spectrum of operations.

 Objective 1c: Establish human resources and family support programs that promote readiness

and quality of life.

 Objective 1d: Institutionalize USACE capabilities in interagency policy and doctrine.

 Goal 2: Deliver enduring and essential water resource solutions through collaboration with

partners and stakeholders.

 Objective 2a: Deliver integrated, sustainable, water resources solutions.

 Objective 2b: Implement collaborative approaches to effectively solve water resource

problems.

 Objective 2c: Implement Streamlined and Transparent Regulatory Processes to Sustain

Aquatic Resources.

 Objective 2d: Enable Gulf Coast recovery.

 Goal 3: Deliver innovative, resilient, sustainable solutions to the Armed Forces and the nation.

 Objective 3a: Deliver sustainable infrastructure via consistent and effective military

construction and real estate support to customers.

 Objective 3b: Improve resilience and lifecycle investment in critical infrastructure.

 Objective 3c: Deliver reliable infrastructure using a risk-informed asset management strategy.

 Objective 3d: Develop and apply innovative approaches to delivering quality infrastructure.

 Goal 4: Build and cultivate a competent, disciplined, and resilient team equipped to deliver high

quality solutions.

 Objective 4a: Identify, develop, maintain, and strengthen technical competencies in selected

Communities of Practice (CoP).

 Objective 4b: Communicate strategically and transparently.

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 Objective 4c: Standardize business processes.

 Objective 4d: Establish tools and systems to get the right people in the right jobs, then

develop and retain this highly skilled workforce.

This project addresses two points of the USACE Campaign Plan. The second goal of the USACE

Campaign Plan is addressed by this project since it is an element of the LCA ecosystem restoration plan

on the Gulf Coast. This project also addresses the third goal through the application of the planning

process to formulate, analyze, and evaluate alternative designs in pursuit of a sustainable, environmentally

beneficial, and cost-effective ecosystem restoration design.

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2.0 NEED FOR AND OBJECTIVES OF ACTION

2.1 NATIONAL OBJECTIVES

The USACE planning process is based on the economic and environmental Principals and Guidelines

(P&G) promulgated in 1983. The P&G provide for development of reasonable plans that are responsive to

National, State, and local concerns. Planning project benefits are quantified in this process as national

economic development (NED) output, national ecosystem restoration (NER) output, or a combination of

NED/NER output.

For water and land resources planning, the Federal objective is to contribute to NED while protecting the

nations environment and adhering to national environmental statutes, executive orders, and Federal

planning requirements. NED contributions are increases in the net value of the national output of goods

and services, expressed in monetary units. These NED outputs are the direct net benefits that accrue in the

planning area and the rest of the nation. Contributions to NED may include increases in the net value of

marketed and non-marketed goods and services.

Ecosystem restoration is one of the primary goals of the USACE Civil Works Program. The USACE

objective in ecosystem restoration planning is to contribute to NER. NER contributions include increases

in the net quantity and/or quality of desired ecosystem resources. NER measurements are changes in

ecological resource quality as a function of improvement in habitat quality and/or quantity. The units are

expressed quantitatively in physical units or indexes that are not based on monetary units. Net changes are

measured in the study area and in the rest of the nation. Single-purpose ecosystem restoration plans shall

be formulated and evaluated in terms of their net contributions to increases in NER output. Multipurpose

plans that include ecosystem restoration shall contribute to both NED outputs and NER outputs. For

multipurpose projects, a plan that trades off NED and NER benefits to maximize the sum of net

contributions to NED and NER is usually recommended.

NED and NER contributions were considered in the alternatives analysis for this project. However, under

Title VII of WRDA 2007, any project or separable project element under LCA may be justified by the

environmental benefits alone and economic justification is not required if the Secretary determines that

the project or activity is cost-effective. This exemption does not apply for any project that is not

predominately related to the protection, preservation, and restoration of the coastal Louisiana ecosystem.

2.2 SIGNIFICANCE OF THE MDWD PROJECT AREA

The benefits of ecosystem restoration and protection projects are difficult to measure in monetary terms.

When determining Federal interest, it is important that the significance of the resources being studied for

restoration by clearly identified. Under Title VII of WRDA 2007, any project or separable project element

under LCA may be justified by the environmental benefits alone and economic justification is not

required if the Secretary determines that the project or activity is cost-effective. The USACEs P&G

defines significance in terms of institutional, public, and technical recognition of the resources. For years,

the Federal Government, the State of Louisiana and other agencies have been engaged in activities that

clearly demonstrate the institutional, public, and technical recognition of the resources of the MDWD

project area.

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Institutional

The formal recognition of coastal Louisiana in laws, adopted plans, and other policy statements of public

agencies and private groups illustrate the significance of the Breton Sound Basin to a variety of

institutions. At the Federal level, the MDWD project areas importance as an environmental and

economic resource has long been recognized by congressional action and through the activities of several

agencies. The U.S. Congress recognized the significance of coastal Louisiana by the passage of the

CWPPRA (PL-101-646, Title III, CWPPRA), which provided authorization and funding for the Louisiana

Coastal Wetlands Conservation and Restoration Task Force to begin actions to curtail wetland losses.

Table 2.1 is a list of CWPPRA projects in the Breton Sound Basin.

Table 2.1: CWPPRAs Restoration Projects in the Breton Sound Basin

PPL Number Agency Project Name

2 BS-03a NRCS Caernarvon Diversion Outfall Management

10 BS-10 COE Delta Building Diversion North of Fort St. Philip

10 BS-11 USFWS Delta Management at Fort St. Philip

14 BS-12 NRCS White Ditch Diversion Restoration and Outfall Management

15 BS-13 COE Bayou Lamoque Freshwater Diversion (Transferred to CIAP)

17 BS-15 EPA Bohemia Mississippi River Reintroduction

17 BS-16 USFWS Caernarvon Outfall Management/Lake Lery Shoreline Restoration

18 BS-18 EPA Bertrandville Siphon

While CWPPRA is an ongoing program, it is comprised of relatively small projects that only partially

restore the coastal ecosystem, and has proven that given the magnitude of Louisianas coastal land losses

and ecosystem degradation, a systematic approach involving larger projects, working in concert with

smaller projects is necessary to reverse the trend of degradation and restore coastal wetlands in Louisiana.

Congress reaffirmed the significance of coastal Louisiana by authorizing the LCA Program through Title

VII of the WRDA (Public Law 110-114). The MDWD project is specifically categorized as a near-term

critical project. This conditional authorization and accelerated schedule to ensure swift action,

demonstrates the importance and necessity of taking immediate and bold measures to reduce the rate of

degradation that has been allowed to progress in coastal Louisiana for decades. The FY 2011 presidential

budget for the USACE provides $35.6 million for Gulf Coast restoration, including $19 million for

wetlands construction projects and $16.6 million for wetlands pre-construction studies. The FY 2011

presidential budget for the USFWS provides $5 million for Gulf Coast restoration.

Public

Coastal Louisiana is significant based on wide public recognition of the environmental resources present

in the coastal wetlands. Louisianas coastal wetlands and barrier island systems enhance protection of an

internationally significant commercial-industrial complex from the destructive forces of storm-driven

waves and tides. Population for Plaquemines Parish, location of the MDWD study area, was estimated at

approximately 21,540 in 2007 (U.S. Census Bureau, 2009). Between 60% and 70% of Louisianas

population lives within 50 miles of the coast. Louisianas coast is a working coast, supporting critical

infrastructure such as highways, ports, pipelines and navigational waterways of national economic

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significance. Without coastal restoration, people and businesses that power the nation will be forced to

retreat from coastal Louisiana, resulting in severe economic consequences to the nation.

Excluding Alaska, Louisiana produced the nations highest commercial marine fish landings (about $343

million) excluding mollusk landings such as clams, oysters, and scallops (NMFS 2003). The State of

Louisiana also leases thousands of sites throughout the basin for the production and harvesting of oysters.

Data from the USFWS show expenditures on recreational fishing (trips and equipment) in Louisiana to be

nearly $703 million, and hunting expenditures were $446 million for 2001 (USFWS, 2002).

Technical

Numerous scientific analyses and evaluations of the MDWD project area have documented its significant

ecological resources. Louisiana contains one of the largest expanses of coastal wetlands in the contiguous

U.S., and accounts for 90 percent of the total coastal marsh loss occurring in the nation. While many

studies have been conducted to identify the major contributing factors (e.g., Boesch et al., 1994; Turner

1997; Penland et al., 2000), most studies agree that land loss and the degradation of the coastal ecosystem

are the result of both natural and human induced factors, producing conditions where wetland vegetation

can no longer survive and wetlands are lost. The natural processes of subsidence, saltwater intrusion, and

erosion of wetlands, and the human effects of river levee construction and the oil and gas industry, have

caused major impacts to the Breton Sound Basin in recent decades. The two major wetland problems

resulting from the natural processes and human intervention in this basin are sediment deprivation and

saltwater intrusion.

The MDWD project area contains an extraordinary diversity of habitats that range from narrow natural

levees to expanses of forested swamps and freshwater, intermediate, brackish, and saline marshes. Taken

as a whole, the unique habitats of wetland areas and the Gulf of Mexico, with their hydrological

connections to each other, and migratory routes of birds, fish and other species, combine to place the

coastal wetlands of the project area among the nations most productive and important natural assets. In

human terms, these coastal wetlands have been a center for culturally diverse social development.

The commercial harvest of alligator eggs is important economically in the basin. The alligator population

in the Breton Sound estuary is surveyed annually by the LDWF via aerial nest inventories conducted in

late June or early July after nesting is complete.

Approximately 70 percent of all waterfowl that migrate through the U.S. use the Mississippi and Central

flyways, which are located directly over (within) the MDWD project area. With over 5 million birds

wintering in Louisiana, the Louisiana coastal wetlands are a crucial habitat to these birds, as well as to

neo-tropical migratory songbirds and other avian species that use them as crucial stopover habitat. These

economic and habitat values, which are protected and supported by the coastal wetlands of Louisiana, and

the MDWD project area specifically, are significant on a national level.

2.3 PUBLIC CONCERNS

A number of public concerns have been identified during the course of the study. Initial concerns were

expressed in the study authorization. Additional input was received through coordination with the

sponsor, coordination with other agencies, public review of draft and interim products, and through

workshops and public meetings. A discussion of public involvement is included in Chapter 6, Public

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Involvement, Review and Consultation. The public concerns that are related to the establishment of

planning objectives and planning constraints are:

 Potential negative effects from the diversion on oyster habitats

 Potential negative effects from the diversion on alligator egg collecting

 Potential negative effects from the diversion on the proliferation of invasive species

 Potential negative effects from the diversion on the Mississippi River shipping and navigation

industry

 Excessive changes in the salinity gradient that converts existing estuarine habitats into purely

freshwater and intermediate types

 Making the project area more susceptible to storm surge by creating flotant marsh

 Not having a rigorous and comprehensive operational scheme

 Proliferating the range and extent of invasive species (water hyacinth)

 Increasing costs associated with maintenance dredging in the Mississippi River due to induced

shoaling effects

 Uncertainty about effects of the diversion on commercial and recreational fisheries species

 Coordinating the operational scheme with the Myrtle Grove diversion that could be located

directly across from the White Ditch diversion location

2.4 PROBLEMS, NEEDS, AND OPPORTUNITIES

The first step in the planning process is the identification of problems and opportunities. Problems are

undesirable, negative conditions that the study will address. Opportunities are desirable conditions that

could be achieved in the future. Study area problems and opportunities were drawn from prior

comprehensive planning studies and from public input and interagency information exchange.

System-wide problems and opportunities were used to identify and define more geographically specific

problems and opportunities throughout the study area. Through the NEPA public scoping process, the

study team solicited input on problems and opportunities from members of the public, government

resource agencies, and other stakeholders. A discussion of general study area problems and opportunities

follows.

2.4.1 General Problem Statement

The altered supply and distribution of freshwater, lack of sediments, marsh subsidence and human

development in the MDWD area have resulted in degraded and unbalanced distribution of freshwater,

brackish, and saltwater marsh habitats. Further, the degradation of the existing marshes has made them

more vulnerable to the range of Gulf storm events; extreme and seasonal, resulting in accelerated

degradation, altered hydrology changed salinity regimes.

Installation of the existing White Ditch diversion siphon was completed in 1963 with the objective of

enhancing muskrat and oyster habitat. In the absence of an outfall management plan, the surrounding

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marsh received limited benefits from the diverted river water. Two 50-inch steel pipes divert water from

the Mississippi River through the White Ditch, into the Belair Canal and then into the River aux Chenes,

where it continues south and out of the project area. Usage of the siphons was abandoned for many years

and they degraded into a non-usable condition. The siphons were recently refurbished and water was

diverted into White Ditch as part of research efforts.

Wetlands in the project area are deteriorating for several reasons: 1) subsidence, 2) lack of sediment and

nutrient deposition, 3) erosion via tidal exchange, 4) channelization, 5) saltwater intrusion, 6) lack of

freshwater, and 7) sea level rise. Recent hurricanes and tropical storms have also caused significant

damage to the project area. These activities have resulted in the loss of several thousand acres of solid,

vegetated marsh. Deterioration will continue unless preventative measures are taken.

Along the Louisiana coast, both changes in water level and changes in land elevation are occurring.

Relative sea level change is the term applied to the difference between the change in eustatic sea level and

the change in land elevation (also referred to as relative subsidence). Land elevations decrease due to

subsidence from compaction and consolidation of sediments, faulting, and groundwater depletion, and

increase due to sediment accretion from riverine and littoral sources as well as organic deposition from

vegetation. For most of coastal Louisiana, sediment accretion is insufficient to offset subsidence, so land

elevations are decreasing. Taking into account changes in land elevation and water levels, the average rate

of relative sea level change along coastal Louisiana is currently estimated to be between 3.4 to 3.9

feet/century (1.03 and 1.19 meters/century).

In the absence of supplemental freshwater and sediment from the Mississippi River, subsidence, sea-level

rise, wave erosion, and saltwater intrusion will continue to be problems. Protection and enhancement of

this area are dependent on providing a hydrologic and sediment regime that minimizes the physiological

stress to wetland vegetation from saltwater intrusion and tidal energy and is conducive to the retention of

locally provided freshwater and sediments

The historic hydrology of the project area indicates that the current course of the Mississippi River has

remained the same for the last 700 years and has directly influenced the development of the entire area.

The project area is located on the east side of the Mississippi River and was formed between two natural

levee ridge systems, River aux Chenes on the east and the Mississippi River on the west. There are also

two unnamed bayou ridges found within the project area. These ridges formed along the old natural

bayous which were distributary channels for the Mississippi River. These natural bayous once carried

sediments and nutrients into the project area during high river stages when the natural ridges were

seasonally overtopped.

In the historical setting, floodwater from the river would recede and sediments and nutrients would be

deposited in the inter-distributary basins located between ridges. During normal or low river stages, the

ridges along the distributary channels served like levees and buffered the basin areas from the daily tidal

influence. This buffering effect created a low energy freshwater environment in the inter-distributary

basins, forming deep organic soils. Drainage to the area was provided by a high water event breaching the

River aux Chenes ridge in the southern part of the project area. This event caused the development of the

Bayou Garelle tributary channel.

The present day hydrology of the project area has been altered and no longer functions in a historically

natural pattern. Historically, water moved very slowly through the system. Freshwater slowly exited the

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system through meandering pathways in the marsh and saltwater was slow to intrude. Presently, changes

in the marsh allow water to rapidly pass through the system and saltwater is able to quickly intrude. The

hydrologic balance within the marsh has been disturbed due to the following man-made changes:

1. The Mississippi River can no longer overflow its banks into the project area due to the

Mississippi River protection levee. This has eliminated the introduction of freshwater from the

river and disrupted natural sediment deposition patterns.

2. Channels have been dredged through natural ridges, which have increased drainage and tidal

exchange and exposed the soil to erosive forces.

2.4.2 Study Area Opportunities

Opportunities exist to naturalize the distribution of freshwater and sediments, improve hydrologic

distribution of freshwater, improve topographic diversity, reduce the negative impacts of Gulf storm

events and inhibit invasive species.

 Freshwater Supply  Re-introduction of freshwater supplies is an opportunity to restore a

degraded and impaired deltaic forming process. Further, freshwater introduction has the potential

to balance the altered salinity regime, improve the viability of freshwater marsh plant life and

therefore restore fish and wildlife habitats.

 Hydraulic Distribution  Human induced habitat fragmentation (canals) has resulted in a

degraded condition whereby the limited existing freshwater supplies are directed towards River

aux Chenes and into the Gulf. Opportunities exist to improve the internal distribution of

freshwater to restore and improve the sustainability of freshwater marsh habitats.

 Sediment Supply and Distribution  The lack of sediments from the Mississippi River has

accelerated the degradation of all marsh types. Opportunities exist to re-introduce sediments from

the river and use on site sediments displaced by Gulf storm events to create new marsh area.

Based on the available survey data, the average depth of open water in the study area is 2 feet,

with approximately 1 foot of soil structure above water required to support healthy marsh. This

total of 3 feet of soil structure is assumed to be needed to support healthy marsh in the future.

 Topographic Diversity  As the freshwater marshes in the area degrade, niche habitats on ridges

are lost, particularly forest resources such as oaks. Opportunities exist to restore ridge type

features with both sediment introduction and targeted placement of materials.

 Sustainability  As marsh degradation has accelerated, seasonal Gulf events have a magnified

impact on the remaining marsh areas. Opportunities exist through freshwater supply and

distribution and sediment supply and distribution to create a healthier marsh which will be more

resistant to the normal range of Gulf events.

 Invasive Species  Hyacinth is a common invasive species in the Breton Sound Basin. Freshwater

introduction has the potential to improve conditions for its growth. Opportunities exist to control

this incursion through effective diversion flexible management, prescribed burns of marsh grass

and chemical control.

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2.4.3 Desired Future Conditions

In order to more clearly articulate restoration goals and objectives for the project and understand how they

fit into the large coastal system and the knowledge gained through the 2004 LCA Study; it is useful to

outline potential desired future ecological conditions. Desired future conditions represent the restoration

need of the project area. The restoration need in the case of White Ditch is the difference between a fully

functioning and sustainable marsh community and the future habitat conditions (future without project).

As an ideal ecological condition is difficult to determine for the project area due to a lack of reference

conditions, the desired future condition is somewhat conceptual and reflects the value of the resource

placed upon it by stakeholders. Project objectives will be refined based on the desired future. Finally, it is

a useful way of establishing the upper bounds to restoration goals, objectives, and ultimately alternatives.

Based on the available data and the outcome of public scoping meetings, a series of potential desired

futures exists that require consideration by the study team, sponsor, collaborating agencies and citizens.

Figure 2.1 illustrates five potential desired future conditions. They are:

 Louisiana Coastal Area Study (2004) 1: Increase of marsh acres 50% over no net loss.

 Louisiana Coastal Area Study (2004) 2: Maintain no net loss of marsh acres.

 Louisiana Coastal Area Study (2004) 3: Reduce loss rate by 50%.

 Desired Future 1: Historic Condition (1985).

 Desired Future 2: Other proposed target?

At this time a Desired Future Condition has been identified as a no net loss of marsh acres consistent with

LCA 2. It should be noted that no-net-loss was what the Project Delivery Team (PDT) felt was achievable

and desirable given the uncertainty associated with sea level rise and the constraints of time and

availability of information. Given the severe loss of marsh from over the last 25 years exceeding the

current marsh areas would be beneficial to both the project area but also the larger ecosystem of the

Breton Sound. The annual loss rate of marsh of 274.5 acres per year is equivalent to approximately 1.3

million cubic yards of sediment. The 1.3 million cubic yards figure is the quantity of sediment required to

offset the loss of 274.5 acres per year. Based on the available survey data, the average depth of open

water in the study area is 2 feet with approximately 1 foot of soil structure above water required to

support healthy marsh. This total of 3 feet of soil structure is assumed to be needed to support healthy

marsh in the future. The 1.3 million cubic yards figure is the volume of sediment needed to fill the 274.5

acres to an average depth of 3 feet.

2.5 PLANNING OBJECTIVES

Study goals, objectives, and constraints were developed to comply with the study authority and to respond

to study area problems and opportunities.

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Figure 2.1: Potential Desired Future Condition

2.5.1 Goals and Objectives

In consultation with the non-Federal sponsor and other interested parties, Goals and Objectives were

developed in the first quarter of 2009. They are:

Table 2.2: Goals and Objectives

Overarching System Goal Objective

Restore and maintain ecological integrity,

including habitats, communities, and

populations of native species, and the processes

that sustain them by reversing the trend of

degradation and deterioration to the area

between the Mississippi River and the River

aux Chenes ridges, so as to contribute towards

achieving and sustaining a larger coastal

ecosystem that can support and protect the

environment, economy, and culture of southern

Louisiana and thus contribute to the economy

and well-being of the nation.

A. Maintain the current area of marsh habitat, of all types

(41,206 acres) that provide life requisite habitat conditions

for native coastal marsh fish and wildlife.

B. Restore adequate freshwater and nutrient inputs into the

project area such that sustainable areas of fresh,

intermediate, brackish and saline marsh are present and

existing areas of marsh acres are maintained.

C. Restore sediment inputs into the project area equivalent to

an average of approximately 1,300,000 cubic yards of

sediment per year.

50,590

Marsh

Acres

1985

2008 2059

41,206

Marsh

Acres

27,481

Marsh

Acres

Time: 50-year period

of analysis

Quality

(acres)

Loss of 9,384 Acres

(1985-2008)

Loss of 13,725

Acres

(2009-2059)

Window of

Uncertainty

Louisiana Coastal Area: Medium Diversion at White Ditch

Potential Desired Future Condition

LCA 1: 48,069

Acres

LCA 2: 41,206

Acres

LCA 3: 34,343

Acres

DF1: 50,590

Acres

DF2: ???

Acres

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2.6 PLANNING CONSTRAINTS

Development and evaluation of restoration alternatives for the proposed project are constrained by a

number of factors. These factors are generally divided into two categories:

 Project design constraints- Limitations to the scope and functionality of specific project features

because of issues regarding project effects on other projects or infrastructure in the study area;

and

 Ecosystem constraints- Constraints imposed upon the project design by existing conditions within

the study areas ecosystem.

These categories and their constituent constraints are discussed separately below.

Project Design Constraints. Identified project design constraints for the MDWD project include the

following:

 The current authorization identifies a 5,00015,000 cfs diversion with the ultimate size to be

determined by the PDT. The 2004 LCA report determined based on limited information, a

medium diversion would be sufficient to meet the goals and objectives of the overall LCA

project. Existing conditions may have changed and we will investigate all reasonable alternatives

for achieving the goals and objectives, even if they include larger diversions.

 Flood Damage Protection  The MDWD restoration measures must accomplish its goals while

avoiding and/or minimizing significant impacts to the existing level of flood protection.

 Drainage Infrastructure  The current arrangement of canals and water bodies would likely need

to be altered to support the goals of the project. The project should permit reasonable access to

the local waterways for all prospective users.

 General Infrastructure  A State highway and several local roads, as well as a few residences are

found in the study area. Adverse effects to the existing infrastructure will be minimized to the

extent practicable. Numerous gas and oil pipelines exist that are not mapped and may limit the

design or restrict the use of some potential restoration measures. The risk and uncertainty

associated with any project feature must be evaluated as it relates to buried utilities.

 Potential impacts such as induced shoaling or increased Operations and Maintenance of the

authorized Mississippi River Navigation Project should be avoided but if necessary mitigation

measures and costs will be evaluated and included as part of the Recommended Plan.

Ecosystem Constraints. Identified ecosystem constraints for the MDWD project included the following:

 It may be likely that the restoration of marsh habitats may still not occur fast enough to

compensate for the losses due to Gulf storm events and potential sea level rise.

 Water Quality  Planning objectives of the proposed project include the introduction of water and

sediments from the Mississippi River. Restoration measures cannot introduce water, nutrient or

sediment flows that would violate established state water quality standards.

 Pallid Sturgeon  In 2008 the Bonnet Carré Diversion, north of New Orleans was opened for the

first time in 15 years. A number of pallid sturgeons were entrained in the diversion. At this time it

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is not known if pallid sturgeons are in the lower river near the MDWD study area. Monitoring

will need to be done to determine its presence and if so this will need to be coordinated closely

with USFWS.

 River aux Chenes  River aux Chenes, while disconnected from the Mississippi River, still

conveys flows from the Breton Sound Basin to the Gulf. Overtopping of the natural levees or

banks of the River aux Chenes from a diversion could potentially result in loss of those diversion

flows to the Gulf. This effect could serve as an upper constraint on the size of flows that can be

diverted. Further Hydrology and Hydraulic modeling will need to be done to better understand

these conditions.

 Estuarine Access  Diversion features need to be designed to allow the continuance of

ecologically important exchanges of water, nutrients, food sources and fish between the project

area and River aux Chenes, as well as navigation access, while achieving project objectives for

marsh restoration.

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3.0 ALTERNATIVES

3.1 PLAN FORMULATION RATIONALE

3.1.1 Plan Formulation Rationale

Alternatives for the proposed action were formulated in consideration of study area problems and

opportunities, as well as study goals, objectives and constraints. As specified in ER 1105-2-100, four

criteria were considered during alternative plan screening: completeness, effectiveness, efficiency, and

acceptability.

3.1.2 Plan Formulation Criteria

3.1.2.1 Completeness

Completeness is the extent that an alternative provides and accounts for all investments and actions

required to ensure the planned output is achieved. These criteria may require that an alternative consider

the relationship of the plan to other public and private plans if those plans affect the outcome of the

project. Completeness also includes consideration of real estate issues, O&M, monitoring, and

sponsorship factors. Adaptive management plans formulated to address project uncertainties also have to

be considered.

3.1.2.2 Effectiveness

Effectiveness is defined as the degree to which the plan will achieve the planning objective. The plan

must make a significant contribution to the problem or opportunity being addressed.

3.1.2.3 Efficiency

The project must be a cost-effective means of addressing the problem or opportunity. The plan outputs

cannot be produced more cost-effectively by another institution or agency.

3.1.2.4 Acceptability

A plan must be acceptable to Federal, state, and local government in terms of applicable laws, regulation,

and public policy. The project should have evidence of broad-based public support and be acceptable to

the non-Federal cost sharing partner.

3.1.3 Environmental Operating Principles

In 2002, the USACE formalized a set of Environmental Operating Principles applicable to decisionmaking in all programs. The principles are consistent with NEPA; the Army Strategy for the

Environment; other environmental statutes, and the WRDAs that govern USACE activities. The

Environmental Operating Principles inform the plan formulation process and are integrated into all

project management processes. Alternatives were formulated for this project consistent with the

Environmental Operating Principles.

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The USACE Environmental Operating Principles are:

 Strive to achieve environmental sustainability, and recognize that an environment maintained in a

healthy, diverse, and sustainable condition is necessary to support life;

 Recognize the interdependence of life and the physical environment, and proactively consider

environmental consequences of USACE programs and act accordingly in all appropriate

circumstances;

 Seek balance and synergy among human development activities and natural systems by designing

economic and environmental solutions that support and reinforce one another;

 Continue to accept corporate responsibility and accountability under the law for activities and

decisions under our control that impact human health and welfare and the continued viability of

natural systems;

 Seek ways and means to assess and mitigate cumulative impacts to the environment and bring

systems approaches to the full life cycle of our processes and work;

 Build and share an integrated scientific, economic, and social knowledge base that supports a

greater understanding of the environment and impacts of our work; and

 Respect the views of individuals and groups interested in USACE activities, listen to them

actively, and learn from their perspective in the search to find innovative win-win solutions to the

nations problems that also protect and enhance the environment.

3.1.4 White Ditch Study Area Land Loss

The loss of coastal marsh within the White Ditch study area has been profound. The data available and

shown in Table 3.1 depicts habitat change over time from the earliest time period of 1956 through 2008

including the aftermath of the 2005 hurricanes that affected the study area. From 1956 to 2008,

approximately 12,762 marsh acres of all types have been converted to open water.

This loss of marsh habitat is accounted for in a variety of one time or short term events and the alteration

of systemic marsh building processes. These contributors to marsh conversion include:

 Gas and Oil Pipeline Construction

 Extreme 2005 Gulf Storm Events

 Altered Deltaic Process

 Subsidence

 Diminished Sediment Inputs

 Diminished Fresh Water Inputs

 Diminished Nutrient Inputs

 Sea Level Rise

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Table 3.1: Study Area, Medium Diversion at White Ditch

Date Julian Data

Land

Area

(acres)

Water

(acres)

Total

(acres)

Land

Area

(mi2)

Water

(mi2)

Total

(mi2) % Land % Water

1956 1956.8 habitat 53,968 44,361 98,329 84.3 69.3 153.6 54.9% 45.1%1978 1978.8 habitat 46,904 51,425 98,329 73.3 80.4 153.6 47.7% 52.3%

1/9/1985 1985.0 TM 50,590 47,739 98,329 79.0 74.6 153.6 51.4% 48.6%

1/28/1988 1988.1 TM 50,792 47,537 98,329 79.4 74.3 153.6 51.7% 48.3%

1988 1988.8 habitat 47,202 51,127 98,329 73.8 79.9 153.6 48.0% 52.0%

11/1/1990 1990.8 TM 47,114 51,215 98,329 73.6 80.0 153.6 47.9% 52.1%2/24/1998 1998.2 TM 47,996 50,333 98,329 75.0 78.6 153.6 48.8% 51.2%

11/18/1999 1999.9 TM 45,407 52,922 98,329 70.9 82.7 153.6 46.2% 53.8%

10/1/2000 2000.8

TM LCA

Desktop 46,325 52,004 98,329 72.4 81.3 153.6 47.1% 52.9%

10/30/2001 2001.8 TM 45,829 52,500 98,329 71.6 82.0 153.6 46.6% 53.4%

2/27/2002 2002.2 TM 46,728 51,601 98,329 73.0 80.6 153.6 47.5% 52.5%11/7/2004 2004.9 TM 45,538 52,791 98,329 71.2 82.5 153.6 46.3% 53.7%

10/25/2005 2005.8 TM 40,831 57,498 98,329 63.8 89.8 153.6 41.5% 58.5%10/28/2006 2006.8 TM 42,057 56,272 98,329 65.7 87.9 153.6 42.8% 57.2%

10/1/2008 2008.8 TM 41,206 57,123 98,329 64.4 89.3 153.6 41.9% 58.1%

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The short time frame events include large oil and gas pipeline construction during the 1950s and 1960s.

Also, the 2005 hurricane season proved devastating in both the intensity of the storm and the storm track

of Katrina through the Breton Sound Basin. Alterations in the deltaic processes that build and sustain

marsh are primarily related to the disruption of freshwater, nutrient and sediment inputs that result from

the isolation of the study area from the Mississippi River. Sea level rise also has contributed to the loss of

marsh habitat to open water. The marsh loss in 2005 compared to historic areas of loss is illustrated in

Figure 3.1. The map depicts areas converted from marsh to open water from 19562005, not inclusive of

Hurricane Katrina. The areas in red indicate those areas of marsh lost to open water as a result of

Hurricane Katrina.

In consultation with the U.S. Geological Survey (USGS) and taking into consideration the quality of the

available data sets, the loss rates were calculated for the period 19852008. With respect to the older data

(1956 and 1978), there are issues with using those data points quantitatively in calculating land loss rates.

These issues relate primarily to the consistency of data collection methodology and classification of

landscape features. They can be looked at qualitatively in terms of what the trends are for an area, but

should not be used in calculating the slope of the land loss line. Figure 3.2 shows the 19852008 loss

rates.

3.1.5 Future Study Area Loss Rates

The future loss rate for the study area is what the PDT in partnership with the sponsor and the public have

set goals and objectives against and have measured action alternatives against to determine relative

benefits. However, it is important to discuss the assumptions, risk and uncertainty involved with

predicting the future rate of marsh conversion to open water.

The available information indicates that a continued loss rate of approximately 274.5 acres +/- per year

throughout the 50-year period of analysis would be reasonable. This would yield a loss of an additional

13,725 acres of marsh of various types to open water within the study area. Figure 3.3 illustrates both the

historic loss rate and extrapolates that decline out to the end of our period of analysis. The result is 27,481

acres of marsh of all types remaining compared to the 2008 measure of 41,206 acres, or a 33.3% decline

in marsh acres.

In Figure 3.3 this concept is expressed as a window of uncertainty.

The two major areas of uncertainty related to the future without project condition are hurricane and storm

damage and sea level rise. Seasonal hurricanes and storm damages are reflected in the proposed loss rate

as they reflect the inclusion of these events in the historic average. Large catastrophic events similar to

Katrina are not included in the future without project condition for the following reasons:

 A storm of the magnitude of Katrina equates to a 425-year storm. While there is always a

probability in any given year that a damaging storm of this magnitude could occur, for the period

of analysis it is not included.

 One reason the damage to the study area from Katrina was so extensive is the storm track

maximized the storm surge into the study area. It is unlikely that another storm would take the

same track through the study area during the period of analysis.

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Figure 3.1: Land Area Change in Coastal Louisiana after the 2005 Hurricanes (19562005) (USGS)

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Figure 3.2: Land Area Trends

Figure 3.3: Future Without-Project Condition

50,590

Marsh

Acres

1985

2008 2059

41,206

Marsh

Acres

27,481

Marsh

Acres

Time: 50-years period

of analysis

Future without project condition

Quality

(acres)

Loss of 9,384

Acres (1985-

2008)

Loss of

13,725 Acres

(2009-2059)

Window of

Uncertainty

Louisiana Coastal Area: Medium Diversion at White Ditch

Future Without Project Condition

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USACE guidance on sea level rise is found in EC1165-2-211 which directs the consideration of three

different scenarios for sea level rise into the planning process. A regional historic rate for the study area

has been determined to be 10.2 millimeters per year (mm/yr) or 1.8 feet over the 50-year period of

analysis. This is based on the historic average and is already reflected in the 274.5 acres +/- loss rate,

which is also based on historic trends. Intermediate and high rates of sea level rise are projected to be 2.3

and 3.7 feet, respectively. The average elevation of marsh within the study area ranges from 1 to 3 feet

with exceptions being remnant ridges and terraces. The inclusion of the intermediate scenarios (2.3 feet)

and the high sea level rise scenario (3.7 feet) results in a significant decline in marsh habitat of all types.

The high rate of sea level rise would likely result in a total collapse of the marsh habitat within the study

area. To reflect this uncertainty the impacts of the high rate sea level rise scenario on the future without

project condition are shown on in Figure 3.4

Figure 3.4: Relative Sea Level Rise: Medium and High Scenario Impacts on

Future Without-Project Condition

3.2 MANAGEMENT MEASURES

3.2.1 Value Engineering Study

A Value Engineering (VE) workshop was conducted on May 1822, 2009, for the U.S. Army Corps of

Engineers (USACE), New Orleans District, by Value Management Strategies, Inc. The subject of the

study was a group of three Louisiana Coastal Area (LCA) ecological restoration projects: Small Diversion

at Convent/Blind River, Amite River Diversion Canal Modification, and Medium Diversion at White

Ditch. This study was conducted at the Feasibility Scoping Report/Preliminary Draft EIS, an early stage

of project development, and as such is the beginning of plan formulation.

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VE Study Results

The VE team developed alternative concepts that are intended to assist the USACE in better formulating

plans to carry forward into the next phase of project development. These recommendations are

categorized per subject project, as well as those that pertain to general plan formulation.

Major findings of the workshop are summarized as follows:

Presently, loss of area in the marsh allows water to rapidly pass through the system and saltwater is able

to quickly intrude. The absence of an outfall management plan related to the White Ditch diversion

siphon results in the surrounding marsh receiving limited benefits from the diverted river water. Also, the

lack of marsh-forming sediments from the Mississippi River has accelerated the degradation of all marsh

types. Sediment needs in the project area are extensive and plan strategies that increase diversion flows to

provide required sediment transport may not be sufficient to provide the necessary sediment. Key VE

alternatives identified to address these issues are as follows:

 Design diversion structures to maximize sediment introduction

 Optimize quantity of freshwater diverted at White Ditch in combination with other proposed

diversion projects

 Construct diversion structure approximately 7 miles south of Phoenix

 Construct a combination spillway with capacity controls to medium diversion levels

 Install sediment introduction system into White Ditch diversion structure

 Optimize flow conveyance in White Ditch

 Identify and incorporate impacts effects of subsidence due to fluid withdrawal into project

analysis

General/Plan Formulation

 Develop Plan Strategies that account for much higher levels of global sea level (GSL) rise

 Provide clarification and address the Water Resources Development Act of 2007 (WRDA 2007)

regarding specified authorized funding limits and the extent of planning development of LCA

projects

Many of these comments and recommendations were adopted and considered by the MDWD PDT during

alternative formulations process. The Recommended Plan incorporates most of the suggestions developed

by the VE team.

3.2.2 Development of Management Measures

A management measure is a feature (a structural element that requires construction or assembly on-site)

or an activity (a nonstructural action) that can be combined with other management measures to form

alternative plans. Management measures were developed to address study area problems and to capitalize

upon study area opportunities. Management measures were derived from a variety of sources including

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prior studies, the NEPA public scoping process, and the multidisciplinary, interagency project delivery

team (IPDT).

Before alternative plans were formulated, the first step taken was to identify general locations and

categories of potential improvements that would satisfy the goals and objectives established previously.

The process began with several discussions concerning the management goals and objectives discussed in

the previous section. This yields an array of general measures from which specific measures were

developed. The formulation of these specific measures involved an assessment of the measures as to

whether they met the goals and objectives of the study and how likely they were to produce measurable

habitat benefits. This is a subjective process requiring further trade-off analysis and habitat evaluation

procedures of alternative plans; however, the depth of professional experience and first-hand management

knowledge by many members of the team was invaluable in defining specific measures.

Finally, during this process, several specific measures were screened for a variety of reasons. They are not

included as specific measures but are described in the screening section below, along with the necessary

justification for their elimination from consideration. Upon finalization of specific measures, alternatives

were developed through combinations of specific measures. This development of alternative plans is

described in 3.3 and 3.4.

3.2.3 Description of Management Measures

As each potential category of measures was developed, a corresponding list of criteria related to each

potential measure was also developed. Below are listed the categories of actions to adequately address the

ecosystem objectives. Measures are loosely defined in five categories that seek to address deficiencies in

or unbalanced deltaic forming processes. They are:

F  Freshwater Supply

F1) Uncontrolled Diversion (Levee Removal)

F2) Uncontrolled Diversion (Large Spillway)

F3) Uncontrolled Diversion (Multiple Spillways)

F4) Gated Diversion Structure (Single)

F5) Gated Diversion Structure (Multiple)

F6) Siphon (Large Multiple)

F7) Siphon (Medium Multiple)

F8) Siphon (Small Multiple)

H  Hydraulic Distribution

H1) Culverts and/or Weirs

H2) Canal Reconfiguration

H3) Construct New Canals

H4) Modify Existing Ridges to Redistribute Flow

S  Sediment Supply and Distribution

S1) Canal Dredging and Placement

S2) Dredging and Placement of local Mississippi River Sediments

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S3) Importation and Placement of Regional Sediments

S4) Construct Seed Wetlands

P  Protection and Sustainability (Existing Marshes)

P1) Barrier Islands

P2) Rock Dikes

P3) Construct Ridges

P4) Construct Terraces

I- Invasive Species Management

I1) Prescribed Burning

I2) Chemical Control

3.2.3.1 Freshwater Supply

The 2004 LCA Study identified reduction of freshwater inputs to coastal marsh areas as a critical

impediment to higher functioning and quality marsh habitats. The disconnect between riverine freshwater

sources and the adjacent floodplain marshes has allowed saltwater to intrude into historically freshwater

habitat types. The salinity intrusion damages existing vegetation which then dies or begins conversion to

saltwater tolerant species. This transition weakens the soil structure and makes it vulnerable to seasonal

Gulf storm events. This category of measures includes both controlled and uncontrolled introduction of

freshwater to the MDWD area. Potential measures include removing portions of the MR&T levee not

required for flood damage reduction, variously sized spillways in the existing MR&T levee, gated

diversion structures, and siphons or pumps.

3.2.3.2 Hydraulic Distribution

Existing canal configurations, storm damage and a generally fragmented landscape impede the effective

distribution of existing and planned freshwater within the site. This category of measures includes

culverts within existing ridges, notched weirs in existing canals, canal reconfiguration or construction of

new canals and modifying existing ridges to redistribute freshwater flows within the MDWD area.

3.2.3.3 Sediment Supply and Distribution

Sediment deposition is as least as important as freshwater supply and distribution. In the current

configuration, the availability of sediments has been completely eliminated from the project site. While it

is likely that the MDWD area would be in a stage of natural degradation, the unavailability of riverine

sediments has accelerated this process, resulting in large-scale subsidence and land loss from Gulf storm

events. The reintroduction of freshwater discussed above will provide necessary seasonal sediment inputs

required for a more sustainable marsh area. However, the large sediment depositional events that

historically occurred with an unconfined Mississippi River could be difficult to replicate, despite their

importance to marsh creation and sustainability. Further, opportunities exist to strategically place

sediment in order to capture what may be introduced along with supplies of freshwater. This category of

measures includes dredging existing canals and beneficial placement of material, dredging and placement

of Mississippi River sediments, importing and placement of regional sediment resources, and the

construction of seed wetlands.

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3.2.3.4 Protection (Existing Marshes)

As the MDWD area has degraded, the effects of seasonal and extreme Gulf storm events has led to large

scale land loss, particularly since 2005. Opportunities exist to create structures that provide not only

habitats similar to barrier islands present in other areas of the Louisiana coast but also to provide

protection to the MDWD study area from storm events while other long term measures such as freshwater

and sediment reintroduction and distribution take effect. This category of measures includes construction

of barrier islands, rock shoreline protection, restoration of historical ridges and associated terraces.

3.2.3.5 Invasive Species Management

Hyacinth is a common invasive species in the Breton Sound Basin. Freshwater introduction has the

potential to improve conditions for its growth. Hyacinth can out-compete native marsh grasses for

resources resulting in conversion to a monoculture. Measures have been considered to control the

proliferation of invasive species that could result from sustained freshwater introduction.

Specific Measures

Management measures that were carried forward for further evaluation are consistent with Administration

budget policy, specific USACE policies for ecosystem restoration, and Federal laws, regulations, and

Executive Orders.

Reflecting the criteria outlined above and the constraints present at the project site, specific measures

were developed within the broad categories of potential measures. These measures are intended to satisfy

the objectives and reach the goals of the project study (see Section 2.5.1)

3.2.3.6 Freshwater Supply

 F1 Uncontrolled Diversion (MR&T Levee Removal)  The current MR&T levee between White

Ditch and Phoenix, Louisiana, is approximately 4.7 miles in length and provides protection from

the river to the community of Carlisle, though there is very little existing infrastructure or

developed area. Portions of the levee could be removed to provide a constant connection to the

Mississippi River and the corresponding ranges of flood events. The size of the diversion would

need to be determined based on hydraulic criteria and the potential biological response to the

freshwater diversion. Other considerations include the need to bridge Louisiana State Highway 39

(LA 39) over any created gap in levee protection.

 F2 Uncontrolled Diversion (Large Spillway)  Based on hydraulic and biologic analysis, a large

spillway that would convey certain Mississippi River flows into the study area could be

constructed on the MR&T levee. A minimum flood frequency of 0.5 would be a starting point for

analysis. Other considerations include the need to bridge any potential gap in levee protection for

LA 39. Also, the non-Federal back-levee that protects the communities of Belair and

Bertrandville to the north would need to be raised because the potential for induced flooding

exists with the measure. Finally, the likelihood of the navigation channel migrating during large

flood events through the levee opening could increase. A risk analysis would need to be

conducted and an adequate structural response would need to be incorporated.

 F3 Uncontrolled Diversion (Multiple Spillways)  A single diversion presents limitations on

freshwater distribution within the project site. This measure involves construction of several

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small spillways placed along the 4.7-mile length of the MR&T levee to better distribute incoming

freshwater. The individual spillways could also be notched or sized differently to allow a variety

of flows into the site.

 F4 Gated Diversion Structure (Single)  This measure features a single structure with gates that

pass flows ranging from 5,000 to 100,000 cfs. The gates could be electrically controlled similar to

Caernarvon. Another option would be a stop log type structure with several bays similar to the

Bonnet Carré structure. Stop logs could be placed or removed with truck mounted winches.

 F5 Gated Diversion Structure (Multiple)  A single gated diversion presents limitations on

freshwater distribution within the project site. Multiple gated structures that collectively pass

5,000 to 100,000 cfs could be more effective at distributing freshwater throughout the project site.

 F6 Siphon (Large Multiple)  A siphon is a continuous tube that would allow freshwater to drain

from the Mississippi River through the MR&T levee into the MDWD area. The flow being driven

only by the difference in hydrostatic pressure between the river side and the study area without

any need for pumping. Currently, a siphon capable of diverting water up to 250 cfs exists at

White Ditch. It was constructed in 1963 by the Parish and the NRCS to improve oyster and

muskrat habitats, but has not been operated since 1991 except for brief episodes. To achieve a

minimum diversion of 5,000 cfs several large siphons could be required to achieve the desired

flow rates.

 F7 Siphon (Medium Multiple)  Several smaller siphons could be constructed in combination

with other freshwater measures to achieve the desired cfs.

 F8 Siphon (Small Multiple)  Several smaller siphons could be constructed in combination with

other freshwater measures to achieve the desired cfs.

3.2.3.7 Hydraulic Distribution

 H1 Culverts and/or Weirs  Due to storm events and canal construction many areas of existing

marsh do not receive adequate distribution of existing freshwater resources. Culverts would be

placed, based on existing conditions and alternative hydraulic modeling, to allow for a more even

distribution of freshwater throughout the site. Weirs could also be placed in existing waterways to

help direct the flow of freshwater and sediments to target areas.

 H2 Canal Reconfiguration  Existing canals for gas, oil and utilities have the effect of

fragmenting the marshes and altering the distribution of existing freshwater. This results in

degraded areas becoming more susceptible to saltwater intrusion and Gulf storm damage.

Existing canals could be altered to better redistribute flows. These alterations could include

cutting spoil banks to facilitate sheet flow, filling of abandoned canals and creation of

distributaries.

 H3 Construct New Canals  Where appropriate and in conjunction with other measures, new

canals could but cut to facilitate freshwater dispersion to degraded freshwater areas.

 H4 Modify Existing Ridges to Redistribute Flow  Remnant historical ridges serve a vital purpose

in creating niche habitats for tree species. They also present an opportunity to direct freshwater

inputs from proposed diversions. Existing ridges near proposed freshwater sources could be

restored to more historical dimensions. The restored ridges would also act to channel introduced

sediments to areas needing nourishment.

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3.2.3.8 Sediment Supply and Distribution

 S1 Canal Dredging and Placement  Canals that are still needed to support commerce but that

have filled in due to storm surge could be dredged to improve their ability to circulate freshwater.

The dredged material would be placed in adjacent marshes where pockets of open water exist,

thereby decreasing marsh fragmentation and increasing overall marsh acreage.

 S2 Dredging and Placement of local Mississippi River Sediments  Diversion of freshwater does

provide opportunities to introduce sediment. However the decades of isolation from wetland

forming river flows has resulted in a significant deficit in sediments. This measure entails large

scale importation of suitable riverine sediments from dredging nearby Mississippi River reaches.

Dredging and placement could be both mechanical and hydraulic. Additionally innovative

dredging and placement technologies tested in 2004 could be used to place material in sensitive

marsh habitats. These include concrete pumps on floating platforms and conveyor belts.

 S3 Importation and Placement of Regional Sediments  The loss of land within the Breton Sound

Basin and in particular the MDWD study area has been dramatic. The large quantities of sediment

required for a holistic restoration of marsh habitats in the area could justify large scale

importation of sediment from areas other than the immediate MDWD reach of the Mississippi

River. It is possible to make use of USACE New Orleans District (MVN) channel maintenance

material for beneficial use as well as long range transport of suitable sediments from USACE

Mississippi Valley Division (MVD) ecosystem projects that are being dredged from critical

backwater habitats and where removing the sediment from a given donor study area is preferable

in ecosystem terms to placement on site. Placement could be both mechanical and hydraulic.

Additionally innovative dredging and placement technologies tested in 2004 could be used to

place material in sensitive marsh habitats. These include concrete pumps on floating platforms

and conveyor belts.

 S4 Construction of Seed Wetlands  Certain areas that will be subject to increased sediment load

from freshwater introduction could be constructed to create immediate marsh habitat while being

configured to trap additional sediments from freshwater diversions. An example would be a

perched wetland with an elevated perimeter and transitional (habitat) interior. As water levels

fluctuate sediments would become trapped in the center and drop out, resulting in marsh creation.

3.2.3.9 Protection (Existing Marshes)

 P1 Barrier Islands  Currently, a complex of barrier islands exists on the extreme south-east of

the Breton Sound basin that is being addressed through other efforts. However, the MDWD area

and Breton Sound in general have reached a point where the marsh is no longer able to recover

from seasonal storm events due to saltwater intrusion and conversion of marsh to open water. A

series of smaller constructed barrier islands aligned along high probability hurricane tracks and

on the south-east edge of the study area would serve to disrupt storm surge and damage to project

features. In addition to the habitat value of the barrier islands they would provide protection of

the study area over the long term (>50 years), while freshwater and sediment measures restore the

marshes themselves and make them more resilient to Gulf storm damage.

 P2 Rock Dikes  Areas of existing high quality marsh could be made more resilient to seasonal

Gulf events by construction of rock shoreline protection.

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Table 3.2: Summary of the Problems, Opportunities, Goals, Objectives and Measures to this Point in the Planning Process

Problems and Opportunities

Overarching

System Goal Objective

Potential General

Measures

Problem: The altered supply anddistribution of freshwater, lack ofsediments, marsh subsidence and humandevelopment in the White Ditch area haveresulted in a degraded and unbalanceddistribution of freshwater, brackish andsaltwater marsh habitats. Further, thedegradation of the existing marshes hasmade them more vulnerable to the rangeof Gulf storm events; extreme andseasonal, resulting in accelerateddegradation, altered hydrology changedsalinity regimes.Opportunities: Opportunities exist tonaturalize the distribution of freshwaterand sediments, improve hydrologicdistribution of freshwater, improvetopographic diversity, reduce the negativeimpacts of Gulf storm events and inhibitinvasive species.

Restore and maintainecological integrity, includinghabitats, communities, andpopulations of native species,and the processes that sustainthem by reversing the trend ofdegradation and deteriorationto the area between theMississippi River and theRiver aux Chenes ridges, soas to contribute towardsachieving and sustaining alarger coastal ecosystem thatcan support and protect theenvironment, economy, andculture of southern Louisianaand thus contribute to theeconomy and well-being ofthe nation.

A. Maintain the current area ofmarsh habitat, of all types (41,206acres) that provide life requisitehabitat conditions for native coastalmarsh fish and wildlife.B. Restore adequate freshwater andnutrient inputs into the project areasuch that sustainable areas of fresh,intermediate, brackish and salinemarsh are present and existingareas of marsh acres aremaintained.C. Restore sediment inputs into theproject area equivalent to anaverage of approximately1,300,000 cubic yards of sedimentper year.

F1) Uncontrolled Diversion (Levee Removal)F2) Uncontrolled Diversion (Large Spillway)F3) Uncontrolled Diversion (Multiple Spillways)F4) Gated Diversion Structure (Single)F5) Gated Diversion Structure (Multiple)F6) Siphon (Large Multiple)F7) Siphon (Medium Multiple)F8) Siphon (Small Multiple)H1) CulvertsH2) Canal ReconfigurationH3) Construct New CanalsH4) Modify Existing Ridges to Redistribute FlowS1) Canal Dredging and PlacementS2) Dredging and Placement of local MississippiRiver SedimentsS3) Importation and Placement of RegionalSedimentsS4) Construct Seed WetlandsP1) Barrier IslandsP2) Rock DikesP3) Construct RidgesP4) Construct TerracesI1) Prescribed BurnsI2) Chemical Control

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 P3 Construct Ridges  In areas where historical ridges have been degraded due to Gulf storm

damage or subsidence, new ridges could be constructed using local sediments. The short term

sustainability of such features can be enhanced with practices such as stone-toe protection or

construction utilizing geo-textile fabrics (textile tubes). Stone-toe protection is a practice whereby

rock is placed along the active erosion line (toe) of a bankline, thereby inhibiting undercutting of

the bank. Long-term sustainability is dependent on other measures to build healthy marshes

through freshwater and sediment supplies.

 P4 Construct Terraces  Terraces could be constructed in open-water habitats to help trap

sediments that move through the area.

3.2.3.10 Invasive Species Management

 I1 Prescribed Burning  Fire is a natural disturbance regime in coastal marshes. Habitat

fragmentation has limited the effectiveness of this regime at controlling invasive plant species.

Prescribed burns at locations susceptible for non-native species invasion will control the species

and improve the overall health of the marsh habitat.

 I2 Chemical Control  In areas where hyacinth is dominant or the spatial extent is small and

isolated, chemical means may be employed to control invasive species. These measures would be

likely combined with other measures to improve overall habitat quality.

3.2.4 Screening / Evaluation of Alternative Plans

Screening of measures is a process whereby various criteria are evaluated to better characterize a specific

measure and the likelihood that it can achieve cost effective restoration. The outcome of this process can

result in specific measures being dropped from further consideration. Reasons (screening criteria) for

elimination of specific measures can include:

 Objectives Supported  Each measure can support some or all of the ecosystem objectives. Those

that support more objectives represent more holistic solutions.

 Timeframe for Marsh Creation  Measures have variable timeframes for creating acres of marsh

habitat; some immediate, others long term.

 Operation, Maintenance, Repair, Rehabilitation, and Replacement (OMRR&R)  The complexity

and cost of operations and maintenance of measures was discussed.

 Lands, Easements, Rights-of-Way, Relocations of Utilities or Other Existing Structures, and

Disposal Areas (LERRDs)  While acquisition of LERRDs is a sponsor responsibility, the

likelihood that the lands can be acquired or that impacts to oil, gas, oyster and alligator leases

generate excessive costs or risks must be considered.

 Navigation  Measures that have the potential to introduce navigational hazards or increased

Operation and Maintenance (O&M) costs were identified.

 Flooding  Measures that increase base and flood event water elevations on the existing

Mississippi River & Tributaries levee or the non-Federal back-levee were identified. Measures

that would require significant raising of the non-Federal back levee were also identified.

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A workshop was held in April 2009 with the sponsor and other resource managers to screen the

preliminary list of specific measures. Appendix L also provides additional information. The table below

details measures that were eliminated from further consideration and why.

3.2.5 Alternative Plans not Carried Forward for Further

Analysis

Table 3.3: Specific Measures Screened from Further Consideration

Category Specific Measure Symbol

Justification for Elimination

from Further Consideration

Freshwater Supply Uncontrolled

Diversion (Levee

Removal)

F1 Uncontrolled diversions would not allow for

targeted management of water inflows to account

for seasonal variation. Also, as the flows on the

Mississippi River are highly altered this measure

would not fulfill the objective of naturalizing

freshwater and nutrient flow into the study area.

This alternative would not allow flexibility needed

for cooperative management with other existing and

future diversion projects in the region. The cost to

relocate or elevate the State highway would be high.

This measure would necessitate at a minimum the

raising of the non-Federal back levee to the north of

MDWD and possibly require the raising of the back

levee protecting Phoenix.

Uncontrolled

Diversion (Large

Spillway)

F2 Uncontrolled diversions would not allow for

targeted management of water inflows to account

for seasonal variation. Also, as the flows on the

Mississippi River are highly altered this measure

would not fulfill the objective of naturalizing

freshwater and nutrient flow into the study area.

This alternative would not allow flexibility needed

for cooperative management with other existing and

future diversion projects in the region. The cost to

relocate or elevate the State highway would be high.

Uncontrolled

Diversion (Multiple

Spillways)

F3 Uncontrolled diversions would not allow for

targeted management of water inflows to account

for seasonal variation. Also, as the flows on the

Mississippi River are highly altered this measure

would not fulfill the objective of naturalizing

freshwater and nutrient flow into the study area.

This alternative would not allow flexibility needed

for cooperative management with other existing and

future diversion projects in the region. The cost to

relocate or elevate the State highway would be high.

Controlled Diversion

(Single Gates)

F4 Engineering analysis concluded that a single gate

structure would be inadequate to pass the minimum

flows necessary to meet project goals and

objectives.

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Table 3.3, cont’d

Category Specific Measure Symbol

Justification for Elimination

from Further Consideration

Siphon (Large

Multiple

F6 The use of large siphons was evaluated. The first

cost of construction and O&M costs were higher

than comparably sized (CFS) gated box culverts,

while the habitat benefits were identical. Further

discussion and analysis can be found in the

Engineering Appendix.

Siphon (Medium) F7 The use of medium siphons was evaluated. The first

cost of construction and O&M costs were higher

than comparably sized (CFS) gated box culverts,

while the habitat benefits were identical. Further

discussion and analysis can be found in the

Engineering Appendix.

Siphon (SmallMultiple)

F8 The use of small siphons (less than 1,000 cfs) would

require multiple crossing of the MR&T levee, the

State highway and utilities. The operation of

numerous (>5) sites would pose operation and

maintenance issues for the sponsor. The need to cut

multiple new outfall canals through healthy marsh to

distribute freshwater is undesirable.

Hydraulic

Distribution

Construct New Canals H3 Construction of new canals would require cutting

through existing healthy marsh and result in

immediate loss of wetlands in the study area. It

would also result in additional habitat fragmentation.

The distribution of freshwater throughout the site

can be achieved through other measures. These

types of measures are envisioned as stand-alone new

canals and distinct from an outfall canal necessary to

move water directly from the diversion structure.

Sediment Supply

and Distribution

Dredge and Place

Mississippi River

Sediments

S2 Upon further analysis it was determined that the

diversion structures themselves were far more

efficient at capturing needed sediments for marsh

creation.

Importation of

Regional Sediments

S3 Upon further analysis it was determined that the

diversion structures themselves were far more

efficient at capturing needed sediments for marsh

creation.

Construct Seed

Wetlands

S4 After further discussion and engineering analysis

this measure was effectively combined with

measure S1 for each of the final array of diversion

alternatives.

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Table 3.3, cont’d

Category Specific Measure Symbol

Justification for Elimination

from Further Consideration

Protection Barrier Islands P1 Based on costs and efforts associated with recent

projects, the level of effort to construct barrier

islands as part of the MDWD project would likely

be cost prohibitive, especially in light of the primary

goal of the project. This is primarily due to the large

amount of construction and associated material that

would likely be required to effectively accomplish

this task. This measure alone would not accomplish

the goals of the project and could impair the ability

to implement other necessary associated measures.

Invasive Species

Management

Prescribed Burning I1 After further discussion among the state and Federal

resource managers, it was concluded that burning,

though practiced widely for marsh vegetation

propagation, was ineffective as a tool for controlling

the spread of invasive species. (Will be considered

as future adaptive management actions where

determined necessary and appropriate).

Chemical Control I2 Large scale application of chemicals could have as

much detrimental effect to healthy marsh as to

invasive species. Further, the use of chemicals to

control invasive species could present problems

when applied over large swaths of private property.

(Will be considered as future adaptive management

actions where determined necessary and

appropriate).

3.3 PRELIMINARY ALTERNATIVE PLANS

3.3.1 Development of Alternative Plans

Alternative plans are combinations of management measures that collectively meet study goals and

objectives within the defined study constraints. Alternative plans are assembled and compared against one

another using performance outputs and costs. Alternative plans and their component management

measures will be assessed relative to the objective of National Ecosystem Restoration (NER). As

alternative plans are evaluated, implementation roles for other Federal and non-Federal agencies will be

considered and developed in detail for the Recommended Plan.

Alternatives were developed that combine the best measures to provide a broad range of alternatives. All

of the action alternatives have freshwater diversions as the base option with additional measures added as

more data became available in later stages of the feasibility study. Based on discussions with the sponsor

and a study team review of goals and objectives the following conceptual alternatives have been defined:

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1. Conceptual White Ditch (CWD) 1: No Action. Over a 50-year period of analysis, if nothing

were done, we would see significant losses of all marsh types throughout the study area. More

major storms could accelerate this loss. As a result open-water habitats would continue to grow

allowing for further intrusion of saltwater into the marsh.

2. CWD 2: LCA Plan. This alternative involves construction of a 15,000 cfs maximum diversion

structure. No other measures would be evaluated as part of this alternative. The need for a

managed diversion was previously established as part of the screening of uncontrolled diversion

measures. Therefore the design would allow for control of freshwater and sediment delivery

(based on flow) at a 5,000 cfs minimum.

3. CWD3: LCA Plan Enhanced. This alternative involves construction of a 15,000 cfs maximum

diversion structure. The design would allow for control of freshwater and sediment delivery

(based on flow) at a 5,000 cfs minimum. Additionally, once the preliminary freshwater and

sediment supply benefits of the structure are determined, measures from the hydraulic distribution

(H), sediment supply & distribution (S), and protection and sustainability (P) will be refined to

improve beneficial distribution of freshwater and sediments to create and restore marsh habitat

and improve its sustainability.

4. CWD4: 45,000 CFS Freshwater Diversion. This alternative involves construction of a structure

capable of diverting up to 45,000 cfs. Additionally, once the preliminary freshwater and sediment

supply benefits of the structure are determined, measures from the hydraulic distribution (H),

sediment supply & distribution (S), and protection and sustainability (P) will be refined to

improve beneficial distribution of freshwater and sediments to create and restore marsh habitat

and improve its sustainability.

5. CWD5: 75,000 CFS Freshwater Diversion. This alternative involves construction of a structure

capable of diverting up 75,000 cfs. Additionally, once the preliminary freshwater and sediment

supply benefits of the structure are determined, measures from the hydraulic distribution (H),

sediment supply & distribution (S) and protection and sustainability (P) will be refined to

improve beneficial distribution of freshwater and sediments to create and restore marsh habitat

and improve its sustainability.

6. CWD6: 100,000 CFS Freshwater Diversion. This alternative involves construction of a

structure capable of diverting up to 100,000 cfs. Additionally, once the preliminary freshwater

and sediment supply benefits of the structure are determined, measures from the hydraulic

distribution (H), sediment supply & distribution (S) and protection and sustainability (P) will be

refined to improve beneficial distribution of freshwater and sediments to create and restore marsh

habitat and improve its sustainability.

After defining the desired future condition, following the feasibility scoping meeting, the objectives for

the project were refined. The freshwater, sediment and nutrient requirements needed to maintain existing

acres of marsh habitat while improving the distribution of marsh types, necessitated a reevaluation of all

large diversion (>15,000 cfs) alternatives. Additionally, the Diversion Project at Myrtle Grove on the

opposite bank of the Mississippi River completed hydraulic evaluation of the same range of diversions

(45k, 75k and 100k) and identified significant issues with impacts to MR&T and back levees; a situation

very similar to the White Ditch study area. Table 3.4 below lists the alternatives eliminated from further

consideration and why.

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Table 3.4: Conceptual Alternatives Screened from Further Consideration

Alternative Symbol Justification for Elimination

from Further Consideration

45,000 CFS

Freshwater

Diversion.

CWD5 Significant impacts were identified at Myrtle Grove in evaluating the

45,000 diversion option. Sustained water levels in excess of 3 feet

were identified. Similar water levels could be expected within the

White Ditch project site. These sustained water depths indicate the

need for toe armoring of significant portions of the levee system as

well as the potential to raise non-Federal back levees. Finally, an

important design criterion was the desire for all diversions not to

exceed the natural levees of River aux Chenes. When this occurs,

freshwater and nutrients discharge to the Gulf via River aux Chenes

and their benefits are lost.

75,000 CFS

Freshwater

Diversion.

CWD5 Significant impacts were identified at Myrtle Grove in evaluating the

75,000 diversion option. Sustained water levels in excess of 3 feet

were identified. Similar water levels could be expected within the

White Ditch project site. These sustained water depths indicate the

need for toe armoring of significant portions of the levee system as

well as the potential to raise non-Federal back levees. Finally, an

important design criterion was the desire for all diversions not to

exceed the natural levees of River aux Chenes. When this occurs,

freshwater and nutrients discharge to the Gulf via River aux Chenes

and their benefits are lost.

100,000 CFS

Freshwater

Diversion.

CWD6 Significant impacts were identified at Myrtle Grove in evaluating the

100,000 diversion option. Sustained water levels in excess of 3.5 feet

were identified. Similar water levels could be expected within the

White Ditch project site. These sustained water depths indicate the

need for toe armoring of significant portions of the levee system as

well as the potential to raise non-Federal back levees. Finally, an

important design criterion was the desire for all diversions not to

exceed the natural levees of River aux Chenes. When this occurs,

freshwater and nutrients discharge to the Gulf via River aux Chenes

and their benefits are lost.

Ecohydraulic modeling of the project alternatives was utilized to compare the effects of one alternative to

another. Modeling of this type is a difficult and computationally intensive analysis. For a detailed

description of the methodology and results of the analysis, see Appendix L. The initial screening of

alternatives was conducted to narrow down the number of alternatives to be run for the WVA Analysis

based on time constraints. These simulations were setup to examine a hypothetical spring pulse period

and allow for the comparison of results between all 660 runs. Each simulation was to run for a 1-month

duration with maximum flows from the proposed new diversion as well as from the existing

Caernarvon diversion (8,000 cfs). By assuming maximum flow from Caernarvon, it was possible to

examine the potential extremity of events. Other parameters were as follows:

 Average spring (MarchMay) tidal conditions.

 Average spring (MarchMay) wind forcing conditions for Plaquemines Parish, Louisiana.

 Average spring (MarchMay) rainfall inputs.

 An average evaporation constant of 5 mm/day.

 Starting salinity over the entire grid of 7 ppt.

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The results of this round of modeling clearly demonstrated that any diversion alternative will greatly

freshen the project area, particularly if the diversion is operated in conjunction with Caernarvon. The

smaller diversions freshen the sound more slowly, but are just as effective as the larger diversions. Other

conclusions that were drawn from this initial modeling are that the larger diversions, 70,000 cfs and

100,000 cfs, will overtop the River Aux Chenes ridge.

After the screening of the larger-sized diversions, it was decided by the PDT that in order for a full array

of alternatives to be evaluated, a diversion that went beyond the 2005 LCA report description was needed.

Since the original concepts for an alternative over the 2005 15,000 cfs project (45,000100,000 cfs)

proved unacceptable, the PDT developed and discussed a 30,000 cfs diversion because it was the next

logical increment up from 15,000 cfs that did not encounter the problems with the 45,000 cfs or larger

diversions. As we progressed through our hydrology and hydraulics assessment we developed a minimum

operating condition for all of the structures such that they could operate at design flows at any time during

a typical year with a minimum of 1 foot of head differential on the Mississippi River which is an average

low stage. The structure design for the 15,000 cfs diversion (ten 15-x-15-foot box culverts) is physically

capable of passing a maximum flow of 35,000 cfs based on a 7-foot head differential on the Mississippi

River which is an average yearly stage. Further, H&H modeling determined that 35,000 cfs was the

maximum diversion that would not exceed River aux Chenes natural levees. Therefore a 35,000 cfs

diversion alternative was developed for both locations 2 and 3. See Appendix L for additional information

on the H&H analysis.

3.3.2 Location for Diversion Structure(s)

The various conceptual alternatives are all centered on diversion structures as the primary means by

which wetland forming processes are restored. The location of one or multiple diversion structures within

the study area is a critical piece to quantifying the benefits of various increments of diversion size ranging

from 5,000 to 35,000 cfs. The remaining non-diversion measures formulated in Section 3.2 were then

combined and optimized based on the variety of diversion sizes and locations to most effectively and

efficiently distribute diverted freshwater, nutrients and sediments so as to maximize marsh creation.

Preliminary investigations identified five potential locations for diversion structures. These areas are

shown on Figure 3.5

Negative and positive aspects of each of these sites are evaluated based on best professional judgment and

an evaluation of known and collected data.

Location 1

Location 1 is at the north end of the White Ditch study area. It is a populated residential area interspersed

with orchards, pastures, and bottomland hardwoods. The west border is the Mississippi River and MR&T

levee and the east border is the Plaquemines Parish non-Federal back levee. The distance between the

MR&T levee and the back levee ranges from approximately 1,900 to 2,700 feet.

The Value Engineering Study team suggested this as a potential location for a diversion structure. This

area was identified because it is located on a point bar of the Mississippi River giving it greater potential

to deliver sediment into the study area. This location would provide the greatest benefit to the extreme

northern end of the study area.

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Figure 3.5: Potential Diversion Structure Locations

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Benefits of this location include:

 It would deliver benefits to the northern section of the study area.

Drawbacks of this location include:

 The presence of a back levee introduces additional construction challenges and costs. Flood

protection measures such as coffer dams would have to be maintained on two levees instead of

one during construction. Water would have to be transported approximately 2,000 feet in pipes or

culverts to reach the marsh.

 It would be difficult to convey sediment, freshwater, and nutrients to the southeast portion study

area. Therefore, it would be difficult to satisfy the goals and objectives throughout the entire

study area. An alternative at this location would likely not be independently viable.

 The vast majority of water and sediments introduced at this location would travel into the Forty

Arpent Canal and away from the study area. It would be difficult to prevent this because the canal

is not a natural feature and does not have a spoil terrace to restrict overland flow. It is likely that

potential benefits would never be maximized due to the difficulty in maintaining water in the

system.

 Due to the proximity of River aux Chenes, less flow would be required to exceed the riverbank

compared to a diversion that was located further away. If less flow is allowed into the study area,

less sediment and nutrients would be put into the system.

 Location 1 contains private development between the MR&T levee and the back levee.

Construction at this location would require removal of homes and relocations would likely be

necessary. There is one potential area in location 1 that would not impact homes, but would

require clearing of approximately 30 acres of bottomland forest.

Location 2

Location 2 is at the existing siphons at White Ditch. There are no residences in the potential construction

footprint. There are several small recreational buildings and an electrical substation nearby. Additionally,

several oil/gas pipelines run through the diversion study area. The length of this location runs from the

existing White Ditch down the MR&T levee for 9,000 feet. It is considered a good location for sediment.

Benefits of this location include:

 The most important characteristic of this site is the lack of a back levee. The absence of a back

levee simplifies construction efforts and minimizes construction costs.

 There are existing internal infrastructure features, such as channels and levees, which could be

modified to convey diverted water within the marsh.

 The location is centrally located within the overall study area. It could independently provide

environmental benefits and meet project objectives throughout the study area. An alternative at

this location would be independently viable.

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 There are minimal residences to impact and potentially no relocations would be necessary. Real

estate issues would be substantially less complicated compared to other areas because there are

very few land owners to acquire ROEs from.

Drawbacks of this location include:

 There could be a need to elevate an existing electrical substation within this location.

 There are a few residences in the vicinity of the location that might need to be elevated

Location 3

Location 3 is just north of Phoenix, Louisiana. There are no known structures within the footprint of this

area. It runs from the junction of the MR&T levee and the Federal back levee to a point approximately

9,200 feet north on the MR&T levee. The White Ditch Value Engineering team identified this area as a

good location to intake sediment because it is on a point bar. Point bars are locations where sediments

drop out of the water column and settle. It is centrally located within the study area and could yield

benefits to the north and south.

Benefits of this location include:

 The most important characteristic of this site is the lack of a back levee. The absence of a back

levee would greatly simplify construction and would minimize construction costs.

 There are existing internal features, such as channels, ridges, and historic distributaries, which

could be used to convey diverted water within the marsh.

 The location is centrally located within the overall study area. It could provide environmental

benefits and meet project objectives throughout most of the study area, rather than just in a

specific section.

 There are no residences to directly impact and no relocations would be necessary. Real estate

issues would be substantially less complicated compared to other areas because there are very few

land owners to acquire ROEs from.

Drawbacks of this location include:

 There is not an existing channel to directly convey diverted flows.

 There are a few residences in the vicinity of the location that would likely need to be elevated.

 Marsh would have to be excavated to create the outfall channel.

Location 4

Location 4 is in the central portion of the White Ditch study area. It is near commercial and residential

areas. The distance between the MR&T levee and the Federal back levee is approximately 2,200 feet. The

White Ditch Engineering team identified this area as a good location to intake sediment because it is near

a channel crossing in the river. It is centrally located within the study area and could yield benefits to the

north and south.

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Benefits of this location include:

 The location is centrally located within the overall study area. It could provide environmental

benefits and meet project objectives throughout most of the study area, rather than just in a

specific section.

 The location is centrally located within the overall study area. It could provide environmental

benefits and meet project objectives throughout most of the study area, rather than just in a

specific section.

 There are existing internal infrastructure features, such as channels and levees, which could be

used to convey diverted water within the marsh.

Drawbacks of this location include:

 The presence of a back levee introduces additional construction challenges and costs. Flood

protection measures such as coffer dams would have to be maintained on two levees instead of

one during construction. Water would have to be transported approximately 2,200 feet in pipes or

culverts to reach the marsh.

 The existing canal between the levees would need to be widened to convey appropriate flows.

Numerous oil and natural gas lines on the bottom of the channel could create difficulties in

dredging.

 There is an anchorage area on the Mississippi River side of this location that might have to be

relocated.

 Location 4 contains some private development between the MR&T levee and the back levee.

Construction at this location might require removal of homes, depending upon the configuration

of the outfall canal.

Location 5

Location 5 is located in the central portion of the White Ditch study area between Phoenix and Pointe à la

Hache, Louisiana. It is a populated residential and business area with multiple land owners. The distance

between the MR&T levee and the Federal back levee ranges from approximately 1,800 to 2,900 feet. This

area was recommended for consideration in the Value Engineering Study. It was identified as a good

location to intake sediment and deliver environmental benefits to the southern end of the study area.

Benefits of this location include:

 There are existing internal infrastructure features, such as channels and levees, which could be

used to convey diverted water.

 There are existing internal infrastructure features, such as channels and levees, which could be

used to convey diverted water.

Drawbacks of this location include:

 The presence of a back levee introduces additional construction challenges and costs. Flood

protection measures such as coffer dams would have to be maintained on two levees instead of

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one during construction. Water would have to be transported up to 2,900 feet in pipes or culverts

to reach the marsh.

 The location contains a substantial amount of private development. Construction at this location

could require removal of homes and relocations might be necessary.

 It would be difficult to convey sediment, freshwater, and nutrients to the northwest portion study

area. Therefore, it would be difficult to meet objectives for entire study area. An alternative at this

location would likely not be independently viable.

Discussion and Conclusions

A screening process was used to determine which of the locations were most suitable for further

evaluation in combination with increments of diversion size. Criteria evaluated include:

 Back Levee Cost: Several locations would need to cross residential areas with back levees. The

cost of crossing two levees would be high.

 Lack of Beneficial Sediment: Certain locations have high sediment load along the Mississippi

River and would be better suited for capturing river sediments.

 Hydrology and Hydraulics: The flow of water to the Gulf in a north-west to south-east fashion

indicates that diversion located towards the lower downstream end of the project sites would be

less effective at distributing the requisite freshwater, sediment and nutrients. See Appendix H for

additional information on Hydrology and Hydraulics.

 Infrastructure Cost: All locations have infrastructure in addition to the levees. Locations that have

higher densities of infrastructure relative to one another and therefore higher relocation costs

were identified.

 Capacity Limitation: Not all locations are able to accommodate the full range of diversion

structure capacities.

 New Outfall Canals: Locations that would require new outfall canal construction as opposed to

those locations with existing outfall available were identified.

Table 3.5 aligns the locations with the criteria that limit the sites overall suitability as a location for

diversion.

Table 3.5: Diversion Location Screening

Louisiana Coastal Area: Medium Diversion at White Ditch

Diversion Location Matrix

Back Levee

Cost H&H Infrastructure Cost

Capacity

Limitations

New Outfall

Canals

Location

1 X X X X

2

3 X

4 X X X X

5 X X X X X

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There are numerous disadvantages to placing alternatives at Locations 1, 4, or 5. Most of these

disadvantages are directly related to the existence of a back levee. From an engineering standpoint, these

sites are more complicated for construction and would be more costly to construct. The distance between

the MR&T and back levee at these locations averages around 2,000 feet. Long trenches would need to be

excavated to a depth of ~20 feet between the two levees. Once excavated, this distance would need to be

spanned by concrete box culverts or pipes to carry water from the river to the marsh. Long-term O&M of

these features would be difficult. Coffer dams would have to be constructed on the MR&T and the back

levee.

By comparison, Locations 2 and 3 do not have a back levee and therefore lack the engineering

disadvantages associated with 1, 4, and 5. Water and sediment could move directly from the river into the

marsh through a box culvert structure beneath the MR&T levee, which would be approximately 350 feet.

Only one coffer dam would have to be constructed. Diversions at Locations 2 or 3 would be much simpler

to construct and less costly than at Locations 1, 4, and 5.

Locations 2 and 3 also have the advantage of being centrally located and directly adjacent to much of the

most degraded marsh within the project boundary. These locations could independently provide positive

influences on most of the study area. Location 4 is also centrally located and could provide benefits to

most of the study area. However, locations 1 and 5 are at the fringe of the area of severe degradation. It

would be very difficult for either site to independently provide benefits to the entire study area.

Because of the back levee and the protection it provides, Locations 1, 4, and 5 have numerous real estate

and relocation concerns. There are several homes, businesses, and farms at each of these locations.

Removal and relocations of homes and businesses would be unavoidable. By comparison, Locations 2

and 3 have minimal real estate concerns. There are far fewer landowners and very few homes or business

in the footprint of either. The few impacts that potentially exist would be indirect.

In summation, no justifiable reason exists to continue consideration of any area outside of the 4.7-mile

stretch between White Ditch and Phoenix where there is no back levee. It is believed that the goals and

objectives of the project can be fully and effectively addressed from Location 2 and 3. Locations 1, 4, and

5 have been removed from further consideration.

3.3.3 Description of Alternative Plans

The remaining conceptual alternatives from Section 3.3.1 have been integrated with the remaining

suitable locations for diversion structures to yield an array of alternatives that meet the goals and

objectives of the project and are likely to restore the impaired deltaic processes. The alternatives are:

1. White Ditch (WD) 1: No Action. Over a 50-year period of analysis, if nothing were done, we

would see significant losses of all marsh types throughout the study area. More major storms

could accelerate this loss. As a result open-water habitats would continue to grow allowing for

further intrusion of saltwater into the marsh.

2. White Ditch (WD) 2: Location 2 – 5,000 cfs. This alternative involves construction of a

structure capable of diverting up to 5,000 cfs. Additionally, once the preliminary freshwater and

sediment supply benefits of the structure are determined, measures from the hydraulic distribution

(H), sediment supply & distribution (S), and protection and sustainability (P) will be refined to

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improve beneficial distribution of freshwater and sediments to create and restore marsh habitat

and improve its sustainability.

3. White Ditch (WD) 3: Location 2 – 10,000 cfs. This alternative involves construction of a

structure capable of diverting up to 10,000 cfs. Additionally, once the preliminary freshwater and

sediment supply benefits of the structure are determined, measures from the hydraulic distribution

(H), sediment supply & distribution (S) and protection and sustainability (P) will be refined to

improve beneficial distribution of freshwater and sediments to create and restore marsh habitat

and improve its sustainability.

4. White Ditch (WD) 4: Location 2 – 15,000 cfs. This alternative involves construction of a

structure capable of diverting up to 15,000 cfs. Additionally, once the preliminary freshwater and

sediment supply benefits of the structure are determined, measures from the hydraulic distribution

(H), sediment supply & distribution (S) and protection and sustainability (P) will be refined to

improve beneficial distribution of freshwater and sediments to create and restore marsh habitat

and improve its sustainability.

5. White Ditch (WD) 5: Location 2 – 35,000 cfs. This alternative involves construction of a

structure capable of diverting up to 35,000 cfs. Additionally, once the preliminary freshwater and

sediment supply benefits of the structure are determined, measures from the hydraulic distribution

(H), sediment supply & distribution (S) and protection and sustainability (P) will be refined to

improve beneficial distribution of freshwater and sediments to create and restore marsh habitat

and improve its sustainability.

6. White Ditch (WD) 6: Location 3 – 5,000 cfs. This alternative involves construction of a

structure capable of diverting up to 5,000 cfs. Additionally, once the preliminary freshwater and

sediment supply benefits of the structure are determined, measures from the hydraulic distribution

(H), sediment supply & distribution (S) and protection and sustainability (P) will be refined to

improve beneficial distribution of freshwater and sediments to create and restore marsh habitat

and improve its sustainability.

7. White Ditch (WD) 7: Location 3 – 10,000 cfs. This alternative involves construction of a

structure capable of diverting up to 10,000 cfs. Additionally, once the preliminary freshwater and

sediment supply benefits of the structure are determined, measures from the hydraulic distribution

(H), sediment supply & distribution (S) and protection and sustainability (P) will be refined to

improve beneficial distribution of freshwater and sediments to create and restore marsh habitat

and improve its sustainability.

8. White Ditch (WD) 8: Location 3 – 15,000 cfs. This alternative involves construction of a

structure capable of diverting up to 15,000 cfs. Additionally, once the preliminary freshwater and

sediment supply benefits of the structure are determined, measures from the hydraulic distribution

(H), sediment supply & distribution (S) and protection and sustainability (P) will be refined to

improve beneficial distribution of freshwater and sediments to create and restore marsh habitat

and improve its sustainability.

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9. White Ditch (WD) 9: Location 3 – 35,000 cfs. This alternative involves construction of a

structure capable of diverting up to 35,000 cfs. Additionally, once the preliminary freshwater and

sediment supply benefits of the structure are determined, measures from the hydraulic distribution

(H), sediment supply & distribution (S) and protection and sustainability (P) will be refined to

improve beneficial distribution of freshwater and sediments to create and restore marsh habitat

and improve its sustainability.

3.3.4 Screening / Evaluation of Alternative Plans

3.3.4.1 The ERDC-SAND2 Model

The ERDC-SAND2 model was originally known as the Boustany Model. The Boustany Model was

developed for evaluating the marsh creation potential. ERDC modified and refined the Boustany model to

specifically measure the marsh creation potential of diversion structures. The modified version became

known as the SAND model. The SAND was refined further and became the SAND2. The ERDC-SAND2

model was the tool used by the MDWD team to predict changes in marsh acreages for all alternatives

over a 50 year planning horizon. It is an ecohydraulic engineering model specifically designed to assess

the effectiveness of potential diversion projects on restoration of land in the coastal marsh. The ERDCSAND2 model is fundamentally based on three processes impacting marsh accretion:

1) Historical land loss rates are applied to account for marsh loss due to all negatively impacting

system processes (e.g. sea level rise, compaction, subsidence, etc.) along with background

processes existing prior to the diversion operation (e.g. marsh nutrient cycling, net tidal and

groundwater inputs, etc.).

2) Inorganic benefits of flow diversion from the addition of sediment.

3) Organic benefits of flow diversion due to plant growth, mortality, and burial stimulated by

addition of the limiting nutrient (nitrogen).

The model applies these processes to assess Future With Project (FWP) and Future Without Project

(FWOP) conditions for alternative comparison. Since the FWOP condition is without diversion, FWOP

marsh acreage is a function of land loss only. The model processes these categories and projects acres of

marsh within a specified project area. With some slight modifications, the model can also project acreages

with accelerated sea level rise rates. More extensive information concerning the ERDC-SAND2 model

can be found in Appendix L.

The outputs (net and average annual acres) from the ERDC-SAND2 model became a key component of

the WVA ecosystem model. A defined operating plan had yet to be evaluated, so three such operating

schemes were proposed to begin to characterize the potential range of benefits of various operating

regimes for each diversion and the ability of each alternative to achieve the goals and objectives of the

project. The Open Diversion reflects the upper threshold in terms of potential impacts. The other two

regimes focus on maximizing sediment capture during the highest sediment load in the River based on

available information. They are:

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 Open Diversion Year Round

 A March 1May 30 Maximum Pulse with no Maintenance Flow

 A March only pulse with a 1,000 cfs Monthly Maintenance Flow

Finally, the likelihood existed that these large diversion alternatives may have impacts beyond the

immediate study area. Therefore the ERDC-SAND2 Model was run on the original study area as well as

the entire Breton Sound Basin. The Institute for Water Resources (IWR) Planning Suite was used for the

analysis.

Table 3.6 displays the costs and net acres of marsh created at the end of the 50-year period of analysis in

order to compare alternatives that can achieve no net loss of marsh acres. The most cost effective

alternatives and operating schemes that achieve a no net loss or desired future condition are highlighted in

green. The desired future condition would be equivalent to the current marsh acres (2009) of 41,206. The

Location 3  10,000 cfs alternative achieves this at the end of the period of analysis only for the year

round open diversion operating regime. It does this more cost effectively than the same size diversion at

Location 2. The Location 3  15,000 alternative achieves the desired future condition at the end of the

period of analysis for the year round open diversion and the MarchMay Pulse. It does this more cost

effectively than the same size diversion at Location 2. The Location 3  35,000 alternative achieves the

desired future condition at the end of the period of analysis for all three operating regimes and more cost

effectively than the same size diversion at Location 2. The 35,000 cfs diversion also achieves a no net loss

of marsh within the expanded Breton Sound Basin if operated at full capacity year round.

It should be noted that the major difference in cost between Location 2 alternatives and Location 3 is the

length of conveyance channels needed to move freshwater, nutrients and sediments. While Location 2 has

an existing conveyance channel (White Ditch) Hydrologic and Hydraulic modeling indicated that it

requires considerably more dredging and placement of material to make it effective at moving diversion

flows to the majority of the study area. Location 3, while it does involve dredging of new conveyance

channels, they are much shorter and more efficient at distributing diversion flows of freshwater, nutrients

and sediments. A complete discussion of this can be found in the Engineering Appendix L.

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Table 3.6: LCA: White Ditch Incremental Cost/Cost Effectiveness Step 1a

Operating Regimes Gross/Net Acres

(Original Study Area) Year 50

Operating Regimes

Gross Acres

(Expanded Study Area) Year 50

Alternative Total First Cost*

Annualized

Cost**

Original Study

area - Open

Diversion

Original Study area -

MarchMay Pulse

Original Study

area - March

Pulse + 1,000

CFS

Expanded Study

area Open

Diversion

Expanded

Study area

MarchMay

Pulse

Location 2 - 5,000 CFS Box $181,800,000 $9,013,128 35,241/

5,965

32,676/

8,530

34,484/

6,722 69,251 64,481

Location 2 - 10,000 CFS Box $230,000,000 $11,402,748 43,448/

2,242

38,071/

3,135

36,318/

4,888 80,924 70,298

Location 2 - 15,000 CFS Box $398,600,000 $19,761,458 51,445/

10,239

43,327/

2,121

38,111/

3,095 92,668 76,099

Location 2 - 35,000 CFS Box $493,400,000 $24,461,373 76,174/

34,968

59,670/

18,464

44,364/

3,155 139,965 98,909

Location 3 - 5,000 CFS Box $140,600,000 $6,970,549 35,241/

5,965

32,676/

8,530

34,484/

6,722 69,251 64,481

Location 3 - 10,000 CFS Box $165,000,000 $8,180,232 43,448/

2,242

38,071/

3,135

36,318/

4,888 80,924 70,298

Location 3 - 15,000 CFS Box $229,400,000 $11,373,001 51,445/

10,239

43,327/

2,121

38,111/

3,095 92,668 76,099

Location 3 - 35,000 CFS Box $334,800,000 $16,598,435 76,174/

34,968

59,670/

18,464

44,364/

3,155 139,965 98,909

*Excludes Real Estate and O&MRRR**FY 2010 Discount Rate 4 3/8%

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Table 3.7: LCA: White Ditch Incremental Cost/Cost Effectiveness Step 1b

Incremental Cost/Cost Effectiveness Analysis

Open Operation

Incremental Cost/Cost Effectiveness Analysis

March–May Pulse

Alternative

Open

Diversion

(Average

Annual

Acres) Incremental Cost

Incremental

Acres

Incremental

Cost per Acre

MarMay

Pulse

(Average

Annual

Acres)

Incremental

Cost

Incremental

Acres

Incremental

Cost per

Acre

Location 2 - 5,000 CFS Box 5,276

Non-Cost

Effective

Plans

2,715

Non-Cost

Effective Plans

Location 2 - 10,000 CFS Box 11,553 5,853Location 2 - 15,000 CFS Box 17,860 8,984Location 2 - 35,000 CFS Box 42,731 21,282Location 3 - 5,000 CFS Box 5,276 $6,970,549 5,276 $1,321 2,715 $6,970,549 2,715 $2,567Location 3 - 10,000 CFS Box 11,553 $1,209,683 6,277 $193 5,853 $1,209,683 3,138 $385Location 3 - 15,000 CFS Box 17,860 $10,163,318 11,583 $877 8,984 $10,163,318 5,846 $1,739Location 3 - 35,000 CFS Box 42,731 $6,435,117 31,148 $207 21,282 $6,435,117 15,436 $417*Excludes Real Estate and O&MRRR**Discount Rate 4 3/8%

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Figure 3.6: White Ditch CE/IC Analysis—Open Diversion

3.3.4.2 CE/IC Analysis

In order to refine the preliminary alternatives further, a two-step Cost Effectiveness & Incremental Cost

(CE/IC) Analysis was utilized. The first step used preliminary cost estimates developed for each action

alternative and outputs from the ERDC-SAND2 model. Table 3.7 displays the CE/IC analysis of the

action alternatives. Average Annual Acres of Marsh is compared against the annualized first cost of the

action alternatives. Average Annual Acres of Marsh produced by each size of diversion structure is the

same for each location. All of the alternatives at location 2 were not cost effective while the 5, 10 and 15

thousand cfs diversions at location 3 were found to be cost effective. The 35,000 cfs diversion was

considered a best buy.

WD 6

WD 7

WD 8

WD 9

No Action

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Figure 3.7: White Ditch CE/IC Analysis Step 1—March–May Pulse

3.3.5 Alternative Plans not Carried for Further Analysis

Based on the above analysis, it was determined that the following alternatives would not be further

evaluated:

 White Ditch (WD) 2: Location 2  5,000 cfs

 White Ditch (WD) 3: Location 2  10,000 cfs

 White Ditch (WD) 4: Location 2  15,000 cfs

 White Ditch (WD) 5: Location 2  35,000 cfs

WD 6

WD 7

WD 8

WD 9

No Action

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3.4 FINAL ARRAY OF ALTERNATIVES

3.4.1 No Action (Future Without Project Conditions)

No Action. The future without project condition for White Ditch will continue to see declines in overall

wetland acres of all types (Figure 3.8). The current altered deltaic process will result in the lack of

freshwater, nutrients and sediments in the project are that are critical to sustain existing marsh and build

additional areas. Overall the study area is expected to see an average loss of 274.5 acres of marsh per

year. This land loss will, during the 50-year period of analysis, result in a further loss of 13,725 acres of

marsh from the 2009 acreage of 41,206.

50,590

Marsh

Acres

1985

2008 2059

41,206

Marsh

Acres

27,481

Marsh

Acres

Time: 50-years period

of analysis

Future without project condition

Quality

(acres)

Loss of 9,384

Acres (1985-

2008)

Loss of

13,725 Acres

(2009-2059)

Window of

Uncertainty

Louisiana Coastal Area: Medium Diversion at White Ditch

Future Without Project Condition

Figure 3.8: LCA: Medium Diversion at White Ditch Future Without Project Condition

Waterbodies would grow larger and wave erosion would accelerate causing further land loss, making

remaining marsh lands in the project area and the larger Breton Sound Basin more vulnerable to tropical

storms. The Future Without Project Condition will likely see the existing marsh persist with minimal

circulation of water, nutrients, and sediment. The sediment deficit has and would continue to result in

both subsidence and a disruption of natural processes that promote productivity and diversity in the marsh

ecosystem. Increases in relative sea level due to continued subsidence and sea level rise would continue to

inundate plant communities, which would ultimately lead to substantial losses. The study area will likely

see additional saltwater intrusion and conversion of the remaining intermediate and brackish marsh to

saline marsh types with the associated salt-tolerant or marine fauna.

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The remaining marsh acreage of 27,481 does not account for any losses that may be incurred by moderate

or high rates of sea level rise. Figure 3.9 below depicts the impacts of both the moderate and high rates of

sea level rise on the project area.

Figure 3.9: Relative Sea Level Rise: Medium and High Scenario Impacts on Future Without

Project Condition

Marsh acres are the result of a variety of physical structure and functions within the larger ecosystem.

Some of these components include soils and waterbottoms, sediment, subsidence, salinity, riparian

vegetation, benthics and fishery resources. Summaries of the future without project condition for these

resources are below with more details provided in Section 4.

Soils and Waterbottoms. No direct alteration of soils or substrate would occur under the No Action

Alternative and associated water management features. No conversion of prime or unique farmland would

occur, and the No Action Alternative would have no direct impact on these resources.

The indirect impacts of the No Action Alternative, would be that the existing patterns of soil erosion and

land loss would continue into the future. Organic soils in the project area would not be able to maintain

their elevations due to subsidence, decreased plant productivity, wave erosion, and relative sea level rise.

Net primary productivity within the project area would continue to decline and existing wetland

vegetation would continue to diminish. The ongoing conversion of existing fragmented emergent

wetlands to shallow open water would continue with associated indirect impacts on coastal vegetation,

fish and wildlife resources, EFH, recreation, aesthetic, and socioeconomic resources. In the future, if no

actions are taken to restore and protect marsh habitat within the project area, any prime and unique

farmland that remains outside of the protection of existing Federal and non-Federal back levees would

continue to be subject to further degradation and possible loss.

Sedimentation and Erosion. The No Action Alternative (i.e., not implementing a sediment and

freshwater diversion in the White Ditch Study Area) would have a direct impact on sedimentation or

erosion within the area between the Mississippi River and River aux Chenes through the continuation of

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existing degradation of marsh. The absence of a supply of freshwater, sediment, and nutrients combined

with the ongoing pressures of wind and wave action, storm surges, and human activities has severely

eroded marsh soils and reduced the ability of the project area to maintain a balance of emergent wetland

and shallow water.

Indirect impacts of the No Action Alternative, not implementing the diversion, are the persistence of

existing conditions. Consequences would include further degradation of the existing marsh from saltwater

intrusion due to short circuited hydrologic processes present in the basin; as well as the continued lack of

sediments, nutrients, and freshwater River aux Chenes and the Mississippi River. With the absences of

these features, the marsh would not be able to sustain itself against subsidence and prolonged inundation

from sea level rise. The No Action Alternative would cause the existing marsh to persist with minimal

circulation of water, nutrients, and sediment. The sediment deficit has and would continue to result in

both subsidence and a disruption of natural processes that promote productivity and diversity in the marsh

ecosystem. Increases in relative sea level due to continued subsidence and sea level rise would continue to

inundate plant communities, which would ultimately lead to substantial losses.

Subsidence. The Future Without Project Condition will likely see the existing marsh to persist with

minimal circulation of water, nutrients, and sediment. The sediment deficit has and would continue to

result in both subsidence and a disruption of natural processes that promote productivity and diversity in

the marsh ecosystem. Increases in relative sea level due to continued subsidence and sea level rise would

continue to inundate plant communities, which would ultimately lead to substantial losses.

Salinity. Under the No Action Alternative, no direct impacts to salinity levels of the Mississippi River or

the White Ditch project area would occur.

Indirect impacts of not implementing restoration features would result in the persistence of existing

conditions for the Mississippi River and continued degradation of the White Ditch project area.

Vegetation Resources. Direct impacts under the No Action Alternative, no construction of diversion

structure or associated outfall management features would occur, and no BLH would be cleared or filled

by construction activities. No opportunities for beneficial use of dredged material for construction

features would occur. Existing BLH in the project footprint would continue to degrade and convert to

intermediate marsh. No direct impacts to existing wetland vegetation resulting from construction of the

proposed diversion and associated features would occur. No opportunities for beneficial reuse of marsh

soil and substrate excavated for construction would be realized. No direct impacts to Submerged Aquatic

Vegetation (SAV) would occur. Baseline SAV coverage was estimated at approximately 15% of open

water areas in the vicinity of the proposed construction footprint (25% in the overall project area).

Existing SAV in the project footprint would continue to degrade and die off as increased salinities enter

the study area and marsh continues to decrease in acreage.

Without implementation of the proposed diversion, no input of sediment, freshwater and nutrients to the

project area would occur. This would result in indirect impacts including the continued erosion of marsh

soils and continued fragmentation and conversion of BLH to intermediate and brackish marsh habitats.

Both man-made and natural processes would contribute to the continued loss of vegetated habitats,

including: continued erosion and subsidence, increased saltwater intrusion, and increased water velocities.

Over the next 50 years, the remaining BLH species in the Study Area would experience continued

subsidence, sea level rise, and salinity increases. The BLH would eventually diminish and convert to

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marsh. Over the next 50 years, approximately 13,750 acres of emergent marsh is projected to be lost, and

it is likely that all remaining remnants of bottomland hardwood vegetation would disappear over the same

period. Over the next 50 years, SAV is projected to be reduced from the estimated baseline of 25% of

open water areas to approximately 15% as the area deteriorates.

Benthics. The Future Without Project Condition will likely see marine (saltwater) influences continue to

take hold and convert freshwater wetlands into intermediate, brackish, and saline marsh. As freshwater

inputs continue to decline and allow marine influences to predominate over riverine influence, salinity

levels rise, resulting in the conversion of low-lying vegetated areas to open water and the redistribution of

marine sediment. These actions eventually lead to conditions that expedite interior marsh loss and the

benthic community and benthic processes would shift from that of an estuarine community to a more

open water marine community. Over the long term, without renewed inputs of freshwater, sediment, and

nutrients to restore and maintain emergent marsh habitat, the project area is likely to convert from a

predominately estuarine habitat to a predominately marine habitat. The benthic community that supports

the estuarine system processes would be adversely affected by the reduction and eventual loss of this

habitat.

Essential Fish Habitat. The No Action Alternative (no construction of river diversion structure or

associated outfall management features) would have no direct impact on Essential Fish Habitat (EFH).

Indirect impacts of not implementing wetland creation/nourishment and shoreline protection features

would result in the persistence of existing conditions resulting in the conversion of categories of EFH,

such as estuarine marsh and SAV, to marine water column and mud, sand, or shell substrates is expected

to continue. Over time, the No Action Alternative would result in the conversion of an estimated 13,724

acres of emergent marsh to open water. Substantial decreases in the quality of EFH in the project area

would reduce the areas ability to support federally managed species.

3.4.2 Alternative 1 – 5,000 cfs diversion

Location 3  5,000 cfs. This alternative involves construction of a structure capable of diverting up to

5,000 cfs consisting of three 15-ft x 15-ft box culverts. Additionally, 32 acres of ridge and terrace

creation, 139 acres of marsh creation utilizing dredged material from an adjacent 153 acres of canal being

reconfigured to convey freshwater, nutrient and sediments (Figure 3.10).

The locations of secondary features, such as notched weirs, were determined from best professional

judgment. Notched weirs are rock structures designed to increase the retention time of the diverted water

within the project area by restricting flow into the River Aux Chenes. Hydraulic modeling clearly

demonstrated that River aux Chenes drains the project area and that once water enters it is quickly carried

away from the desired benefit area. Major outfalls into River aux Chenes would be restricted in order to

retain water in the benefit area and create a greater retention time. A greater retention time would allow

for more sediment to fall in the project area versus being lost to River Aux Chenes. Placing notched weirs

in outfall canals would create a smaller cross-section and result in smaller outflow capacity from the

project area into River Aux Chenes. Notched weirs were chosen because they would not restrict

navigational traffic, nor would they restrict the ingress/egress of aquatic organisms. The structures would

be constructed of 400-pound rip rap with a geotextile and geogrid bedding. A typical cross-section of a

notched weir and plans showing their potential locations can be found in Section L7.5.

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Figure 3.10: Alternative 1 – Location 3

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3.4.3 Alternative 2 – 10,000 cfs Max Diversion

Location 3  10,000 cfs. This alternative involves construction of a structure capable of diverting up to

10,000 cfs consisting of three 15-ft x 15-ft box culverts. Additionally, 32 acres of ridge and terrace

creation, 176 acres of marsh creation utilizing dredged material from an adjacent 167 acres of canal being

reconfigured to convey freshwater, nutrient and sediments (Figure 3.11).

The locations of secondary features, such as notched weirs, were determined from best professional

judgment. Notched weirs are rock structures designed to increase the retention time of the diverted water

within the project area by restricting flow into the River Aux Chenes. Hydraulic modeling clearly

demonstrated that River aux Chenes drains the project area and that once water enters it is quickly carried

away from the desired benefit area. Major outfalls into River aux Chenes would be restricted in order to

retain water in the benefit area and create a greater retention time. A greater retention time would allow

for more sediment to fall in the project area versus being lost to River Aux Chenes. Placing notched weirs

in outfall canals would create a smaller cross-section and result in smaller outflow capacity from the

project area into River Aux Chenes. Notched weirs were chosen because they would not restrict

navigational traffic, nor would they restrict the ingress/egress of aquatic organisms. The structures would

be constructed of 400-pound rip rap with a geotextile and geogrid bedding. A typical cross-section of a

notched weir and plans showing their potential locations can be found in Section L7.5.

3.4.4 Alternative 3 – 15,000 cfs Max Diversion

Location 3  15,000 cfs. This alternative involves construction of a structure capable of diverting up to

15,000 cfs consisting of ten 15-ft x 15-ft box culverts. Additionally, 32 acres of ridge and terrace creation,

235 acres of marsh creation utilizing dredged material from an adjacent 182 acres of canal being

reconfigured to convey freshwater, nutrient and sediments (Figure 3.12).

The locations of secondary features, such as notched weirs, were determined from best professional

judgment. Notched weirs are rock structures designed to increase the retention time of the diverted water

within the project area by restricting flow into the River Aux Chenes. Hydraulic modeling clearly

demonstrated that River aux Chenes drains the project area and that once water enters it is quickly carried

away from the desired benefit area. Major outfalls into River aux Chenes would be restricted in order to

retain water in the benefit area and create a greater retention time. A greater retention time would allow

for more sediment to fall in the project area versus being lost to River Aux Chenes. Placing notched weirs

in outfall canals would create a smaller cross-section and result in smaller outflow capacity from the

project area into River Aux Chenes. Notched weirs were chosen because they would not restrict

navigational traffic, nor would they restrict the ingress/egress of aquatic organisms. The structures would

be constructed of 400-pound rip rap with a geotextile and geogrid bedding. A typical cross-section of a

notched weir and plans showing their potential locations can be found in Section L7.5.

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Figure 3.11: Alternative 2 – Location 3

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Figure 3.12: Alternative 3 – Location 3

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3.4.5 Alternative 4 – 35,000 cfs Max Diversion

(Recommended Plan)

Location 3  35,000 cfs. This alternative involves construction of a structure capable of diverting up to

35,000 cfs consisting of ten 15-ft x 15-ft box culverts. Additionally, 31 acres of ridge and terrace creation,

385 acres of marsh creation utilizing dredged material from an adjacent 223 acres of canal being

reconfigured to convey freshwater, nutrient and sediments (Figure 3.13).

The locations of secondary features, such as notched weirs, were determined from best professional

judgment. Notched weirs are rock structures designed to increase the retention time of the diverted water

within the project area by restricting flow into the River Aux Chenes. Hydraulic modeling clearly

demonstrated that River aux Chenes drains the project area and that once water enters it is quickly carried

away from the desired benefit area. Major outfalls into River aux Chenes would be restricted in order to

retain water in the benefit area and create a greater retention time. A greater retention time would allow

for more sediment to fall in the project area versus being lost to River Aux Chenes. Placing notched weirs

in outfall canals would create a smaller cross-section and result in smaller outflow capacity from the

project area into River Aux Chenes. Notched weirs were chosen because they would not restrict

navigational traffic, nor would they restrict the ingress/egress of aquatic organisms. The structures would

be constructed of 400-pound rip rap with a geotextile and geogrid bedding. A typical cross-section of a

notched weir and plans showing their potential locations can be found in Section L7.5.

3.5 COMPARISON OF ALTERNATIVE PLANS

This section describes the alternative plans and the process used to determine the potential costs, habitat

benefits, incremental cost/cost effectiveness, and other factors leading to a recommended plan. Once the

final array was determined, a second round of ecohydraulic modeling was conducted. These runs

analyzed how salinities would encroach back into the Breton Sound with maintenance flows coming

from the proposed diversion (1,000 cfs) and Caernarvon (800 cfs). For these runs, simulations started

following the final results of the initial screening of alternatives using the salinities that were estimated

there. These results fed into the WVA analysis. These simulations were for a 3-month period with the

following parameters:

 Average summer (JuneAugust) tidal conditions.

 Average summer (JuneAugust) wind forcing conditions for Plaquemines Parish, Louisiana.

 Average summer (JuneAugust) rainfall inputs.

 An average evaporation constant of 5 mm/day.

3.5.1 Incremental Cost/Cost Effectiveness Analysis

Process.

Cost effectiveness analysis was used to determine what project features should be built, based on habitat

benefits (outputs) that meet the goals and objectives of the project and at the same time are the most cost

effective. The Corps has incorporated cost effectiveness analysis into its planning process for all

ecosystem restoration planning efforts. A cost effectiveness analysis is conducted to ensure that least cost

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Figure 3.13: Alternative 4 – Location 3

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alternatives are identified for various levels of output. After the cost effectiveness of the alternatives has

been established, incremental cost analysis is conducted to reveal and evaluate changes in cost for

increasing levels of environmental output.

Cost effectiveness and incremental analysis is a three step procedure: (1) calculate the environmental

outputs of each alternative; (2) determine a cost estimate for each alternative; (3) combine the alternatives

to evaluate the best overall project alternative based on habitat benefits and cost. While cost and

environmental outputs are necessary factors, other factors such as the ability to construct, schedule,

likelihood to achieve projected results, immeasurable environmental benefits, ancillary benefits etc., are

very important in deciding on the preferred alternative.

Environmental outputs were calculated as Average Annual Habitat Units (AAHUs). The annualized costs

were calculated by applying a 4-3/8% annual interest rate to the construction costs over the 50-year period

of analysis. What is described below is the second step of the process introduced in Section 3.3.4 above.

3.5.2 Wetland Value Assessment (WVA)

The Wetland Value Assessment (WVA) methodology is a quantitative habitat-based assessment

methodology developed for use in determining wetland benefits of project proposals submitted for

funding under the CWPPRA. The WVA quantifies changes in fish and wildlife habitat quality and

quantity that are expected to result from a proposed wetland restoration project. The results of the WVA,

measured in Average Annual Habitat Units (AAHUs), can be combined with cost data to provide a

measure of the effectiveness of a proposed project in terms of annualized cost per AAHU gained. In

addition, the WVA methodology provides an estimate of the number of acres benefited or enhanced by

the project and the net acres of habitat protected/restored. See Appendix B for a complete description of

the WVA and its application to this project.

The WVA was developed in 1991 by the Environmental Work Group (EnvWG) assembled under the

Planning and Evaluation Subcommittee of the CWPPRA Technical Committee; the EnvWG includes

members from each agency represented on the CWPPRA Task Force and members of the Academic

Assistance Subcommittee. The WVA was designed to be applied, to the greatest extent possible, using

only existing or readily obtainable data. The WVA models have been revised several times since they

were developed in 1991. WVA has been used to evaluate 5060 projects CWPPRA coastal restoration

projects over the last 2 years. WVA has also been used to evaluate proposed impacts for approximately

200 permit applications and 3040 mitigation areas. For these reasons, and because it was developed

specifically for use in Louisiana coastal environments, this methodology was selected for use in

evaluating MDWD and other LCA projects.

The WVA is a modification of the Habitat Evaluation Procedures (HEP) developed by the USFWS

(USFWS 1980). HEP is widely used by the USFWS and other Federal and State agencies in evaluating

the impacts of development projects on fish and wildlife resources. A notable difference exists between

the two methodologies, however, in that HEP generally uses a species-oriented approach, whereas the

WVA utilizes a community approach.

The WVA has been developed for application to several habitat types along the Louisiana coast and

community models have been developed for fresh marsh, intermediate marsh, brackish marsh, saline

marsh, fresh swamp, barrier islands, and barrier headlands. Two other habitat assessment models for

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bottomland hardwoods and coastal chenier/ridge habitat were developed outside of the CWPPRA arena

and are periodically used by the EnvWG. A WVA Procedural Manual was prepared by the EnvWG to

provide guidance to project planners in the use of the various community models.

Habitat types impacted by construction of the MDWD outfall management features (channel enlargement,

marsh creation, and ridge creation) are intermediate marsh and open water in the intermediate salinity

zone. Habitat types impacted by operation of the MDWD are intermediate, brackish, and saline marsh,

and open water in the intermediate, brackish, and saline zones. Project implementation will create two

habitat types found historically but not currently present in the impacted area: fresh marsh and ridge.

Consequently, the WVA assessment for MDWD utilized community models for fresh/intermediate

marsh, brackish marsh, saline marsh, and coastal chenier/ridge habitat.

WVA Model Certification

The WVA model is completing model certification in accordance with EC 1105-2-407, May 2005

Planning Models Improvement Program:

Model Certification. The model has undergone external review which is documented in the July 8, 2009,

Draft Model Certification Review Report for the Wetland Value Assessment Models prepared by the

Battelle Memorial Institute for the U.S. Army Corps of Engineers, Ecosystem Planning Center of

Expertise. The WVA revision documentation and spreadsheets have been submitted to the ECO-PCX.

The ECO-PCX has reviewed the revisions and will forward a recommendation to certify the model for

use in the LCA projects.

Since the WVA was still in the process of being certified, the projects using the WVA model were

required to respond to specific comments related to the ongoing certification process and the use of WVA

on the specific project. The specific comments and responses for the WVA as it relates to the LCAMDWD Modification project can be found in Appendix K. Based on satisfactory responses to these

comments, Planning Center of Expertise for Ecosystem Restoration has cleared the WVA model for use

in evaluating the alternatives considered in this report.

WVA Concept

The WVA operates under the assumption that optimal conditions for fish and wildlife habitat within a

given coastal wetland habitat type can be characterized, and that existing or predicted conditions can be

compared to that optimum to provide an index of habitat quality. Habitat quality is estimated or expressed

through the use of community models developed specifically for each habitat type. Each model consists

of 1) a list of variables that are considered important in characterizing fish and wildlife habitat, 2) a

Suitability Index graph for each variable, which defines the assumed relationship between habitat quality

(Suitability Index) and different variable values, and 3) a mathematical formula that combines the

Suitability Index for each variable into a single value for habitat quality; that single value is referred to as

the Habitat Suitability Index, or HSI. The output of each model (the HSI) is assumed to have a linear

relationship with the suitability of a coastal wetland system in providing fish and wildlife habitat.

The WVA models have been developed for determining the suitability of Louisiana coastal wetlands in

providing resting, foraging, breeding, and nursery habitat to a diverse assemblage of fish and wildlife

species. The models have been designed to function at a community level and therefore attempt to define

an optimum combination of habitat conditions for common fish and wildlife species utilizing a given

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habitat type. Earlier attempts to capture other wetland functions and values such as storm-surge

protection, flood water storage, water quality functions, and nutrient import/export were abandoned due to

the difficulty in defining unified model relationships and meaningful model outputs for such a variety of

wetland benefits. However, the ability of a Louisiana coastal wetland to provide those functions and

values may be generally assumed to be positively correlated with fish and wildlife habitat quality as

predicted through the WVA.

Community Model Variable Selection

Habitat variables considered appropriate for describing habitat quality in each wetland type were selected

according to the following criteria:

 The condition described by the variable had to be important in characterizing fish and wildlife

habitat quality in the wetland type under consideration;

 Values had to be easily estimated and predicted based on existing or readily obtainable data (e.g.,

aerial photography, habitat classification data, water quality monitoring stations, interviews with

knowledgeable individuals, etc.); and

 The variable had to be sensitive to the types of changes expected to be brought about by typical

wetland restoration projects proposed under the CWPPRA.

The marsh community models used in the WVA assessment for the MDWD (fresh/intermediate, brackish,

and saline) all utilize the same habitat variables. These are: 1) percent of wetland (marsh) covered by

emergent vegetation; 2) percent of open water covered by submerged and floating-leaved aquatic

vegetation; 3) Marsh edge and interspersion with open water; 4) percent of open water less than or equal

to 1.5 feet deep in relation to marsh surface; 5) salinity; and 6) aquatic organism access. Baseline values

assigned to these variables are listed and explained in the WVA Assessment appendix (pages 1774)

included with the USFWS Coordination Act Report attached to this document as Appendix B.

Suitability Index Graphs

A suitability index graph is a graphical representation of how fish and wildlife habitat quality or

"suitability" of a given habitat type is predicted to change as values of the given variable change, and

allows the model user to numerically describe, through a Suitability Index, the habitat quality of a wetland

area for any variable value. Each Suitability Index ranges from 0.1 to 1.0, with 1.0 representing the

optimal condition for the variable in question. Suitability Index (SI) graphs were constructed for each

variable. While the three marsh community models used for the MDWD utilize the same six variables, the

suitability graphs for each variable differ according to the marsh community type (fresh/intermediate,

brackish, or saline).

Habitat Suitability Index Formula

The final step in model development was to construct a mathematical formula that combines all

Suitability Indices into a single Habitat Suitability Index value. Because the Suitability Indices range from

0.1 to 1.0, the HSI also ranges from 0.1 to 1.0, and is a numerical representation of the overall or

"composite" habitat quality of the particular wetland area being evaluated. The HSI formula defines the

aggregation of Suitability Indices in a manner unique to each wetland type depending on how the formula

is constructed.

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Within an HSI formula, any Suitability Index can be weighted by various means to increase the power or

"importance" of that variable relative to the other variables in determining the HSI. Additionally, two or

more variables can be grouped together into subgroups to further isolate variables for weighting.

Benefit Assessment

The net benefits of a proposed project are estimated by predicting future habitat conditions under two

scenarios: future without-project and future with-project. Specifically, predictions are made as to how the

model variables will change through time under the two scenarios. Through that process, HSIs are

established for baseline (pre-project) conditions and for future without- and future with-project scenarios

for selected "target years" throughout the expected life of the project. Those HSIs are then multiplied by

the study area acreage at each target year to arrive at Habitat Units (HUs). Habitat Units represent a

numerical combination of quality (HSI) and quantity (acres) existing at any given point in time. The HUs

resulting from the future without- and future with-project scenarios are annualized, averaged over the

project life, to determine AAHUs. The "benefit" of a project can be quantified by comparing AAHUs

between the future without- and future with-project scenarios. The difference in AAHUs between the two

scenarios represents the net benefit attributable to the project in terms of habitat quantity and quality. The

starting point for the WVA 50-year period of analysis was assumed to be 2015 based upon the current

schedule to complete Plans & Specifications and Construction. This 2015 date differs slightly from the

2009 used in the previous iterations of the planning process. While the starting point of the analysis has

changes between steps (2015 compared to 2009) the entire final array of alternatives was evaluated on

equal terms and therefore the comparison of alternatives and their respective benefits is valid.

The WVA assessment for the MDWD utilized habitat and land-water data generated by the USGS for the

project area, aerial photography, monitoring and hydrodynamic modeling data (for salinity) and also used

field survey data collected for WVAs recently conducted for other, smaller CWPPRA projects within and

adjacent to the MDWD project area. Separate WVA analyses were conducted for each marsh type and

each diversion size alternative, and for each outfall management feature type. Target year 0 (TY0) was

assumed to be 2015. The WVA analyses conducted for the future-without-project (FWOP) condition used

two target years: 1 (TY1) and 50 (TY50) to assess changes in the project area over the 50-year planning

horizon. Analyses of the future-with-project (FWP) condition also used TY1 and TY50, but added a

target year 5 (TY5) within the 50-year planning horizon. TY5 was used in the FWP analyses because

review of hydrodynamic modeling outputs projecting salinities indicated that a portion of the intermediate

marsh area would transition to fresh marsh within a few years following the start of project operation.

More-detailed information concerning data sources, variable assumptions, anticipated habitat changes,

and performance of the diversion alternatives over time is presented in an appendix to the USFWS

Coordination Act Report at Appendix B.

MDWD Summary

Following the multiple operating regimes analyzed as part of Step 1 described previously, an optimal

operating regime was established based on the best available supplies of freshwater, nutrients and

sediments while avoiding the negative impacts of open diversions on the public, oyster and alligator

resources. A MarchApril Open Pulse with a 1,000 cfs maintenance flow the rest of the year would

achieve these ends. The WVA values for the MDWD project are summarized below:

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Table 3.8: Direct Footprint Acreage Impacts

Ridge

Creation

Marsh

Creation

Channel

Enlargement

Alternative 1: Location 3  5,000 cfs Diversion 32 139 153

Alternative 2: Location 3  10,000 cfs Diversion 32 176 167

Alternative 3: Location 3  15,000 cfs Diversion 32 235 182

Alternative 4: Location 3  35,000 cfs Diversion 31 385 223

Table 3.9: Benefits Summary*

Outfall Management Features

Feature 5,000 cfs 10,000 cfs 15,000 cfs 35,000 cfs

Marsh Creation 54.59 72.52 92.19 155.20

Channel Enlargement -15.99 -19.08 -21.89 -31.25

Ridge Footprint -11.33 -11.33 -11.33 -11.37

Ridge Creation 28.24 28.24 28.24 27.36

Net AAHUs 55.51 70.35 87.21 139.94

Diversion Benefits

Marsh Type 5,000 cfs 10,000 cfs 15,000 cfs 35,000 cfs

Fresh/Intermediate 3,505.05 3,862.13 5,650.28 8,802.11

Brackish 1,359.93 1,655.31 1,656.16 3,965.54

Saline 276.26 347.78 347.97 447.42

Net AAHUs 5,141.24 5,865.22 7,654.41 13,215.07

Total Net AAHUs 5,196.75 5,935.57 7,741.62 13,355.01

* The WVAs were updated during the review process. The updated AAHUs and acres are in

Appendix B. There was no significant change in these values.

Table 3.10: Acreage Summary

MDWD Final Array of Alternatives

WVA AAHUs

MarchApril Open +

1,000 cfs Maintenance Flow

Year 0 = 2015

Gross/Net Acres

MarchApril Open +

1,000 cfs Maintenance Flow

Year 0 = 2015

No Net Loss Acres = 39,587

Location 3  5,000 cfs 5,197 35,638 / 3,949

Location 3  10,000 cfs 5,936 40,419 / 562

Location 3  15,000 cfs 7,742 45,046 / 5,459

Location 3  35,000 cfs 13,355 59,902 / 20,315

Note: The WVA assessment was updated during the review process. The updated AAHUs and acres affected can be

found in Appendix B. There was no significant change in these values as a result of the update.

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Cost Estimates for Habitat Improvement Measures

Rough cost estimates were developed to conduct the cost effectiveness and incremental cost analysis of

the various alternative plans. Items included in the first cost construction estimated are mobilization,

dredging, placement, demobilization, contingency, Engineering and Design during Construction (EDC),

Supervision & Administration (S&A), Real Estate and Operations and Maintenance. Table 3.11

summarizes the costs associated with each alternative plan. Following selection of the Recommended

Plan, the design will be refined and a feasibility level cost estimate prepared. Therefore, the cost of the

Recommended Plan may differ from the numbers used during IC/CE analysis. Further details can be

found in the Engineering and Cost Appendices (Appendix L).

Table 3.11: LCA: White Ditch Cost Estimates

Alternative Total First Cost*

Annualized

O&MRRR

Annualized

First Cost**

Total Annualized

Cost

Location 3  5,000 CFS Box $152,900,000 $781,804 $7,580,348 $8,362,152

Location 3  10,000 CFS Box $174,200,000 $871,463 $8,636,342 $9,507,805

Location 3  15,000 CFS Box $241,700,000 $1,131,044 $11,982,801 $13,113,845

Location 3  35,000 CFS Box $329,300,000 $1,467,836 $16,325,760 $17,793,596

*Includes Real Estate

**FY 2010 Discount Rate 4-3/8%

3.5.3 Results of the Incremental Cost/Cost Effectiveness

Analysis

The analyses showed that alternative plans 1, 2, 3, and 4 are cost effective. Aside from the No Action

Alternative, Alternative 4 exhibited the lowest cost per Unit of all alternatives, $1,332 per AAHU.

Alternative 3 exhibited the highest cost per Unit at $1,694 per AAHU.

Table 3.12: White Ditch Incremental Cost/Cost Effectiveness Step 2

Alternative

Total

Annualized

Cost WVA AAHU

Average Cost

per AAHU

Location35,000 CFS Box $8,362,152 5,197 $1,609

Location 3  10,000 CFS Box $9,507,805 5,936 $1,602

Location315,000 CFS Box $13,113,845 7,742 $1,694

Location 3  35,000 CFS Box $17,793,596 13,355 $1,332

* Includes Real Estate

** Discount Rate 43⁄8%

Overall, alternative 4 was considered a best buy plan. However, as the plans are linear in benefits and

costs, a CE/IC analysis was conducted on all of the alternatives. These plans provide the greatest increase

in benefits for the least increase in cost.

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The No Action Alternative (FWOP) is cost effective; however, it provides no improvement in habitat

quality resulting in steep declines in marsh. Alternative plan 1 provides 5,197 AAHUs over and above the

No Action Alternative (FWOP) at an annualized incremental cost of $8,362,152 (tables 3.12 and 3.13).

Alternative plan 2 provides 739 additional AAHUs, at an annualized incremental cost of $1,145,653.

Alternative plan 3 provides 1,806 additional AAHUs, at an annualized incremental cost of $3,606,040.

Alternative Plan 4 provides 5,613 additional AAHUs at an annualized incremental cost of $4,679,752.

Alternative 4 has the lowest incremental cost per AAHU of $834.

Figure 3.14: CE/IC Analysis of Final Alternatives

Table 3.13: White Ditch Incremental Cost/Cost Effectiveness Step 2

Incremental Cost/Cost Effectiveness

Analysis of Cost Effective Plans

Alternative

Total

Annualized

Cost

WVA

AAHU

Incremental

Cost

Incremental

AAHU

Incremental

Cost per

AAHU

Location 3  5,000 CFS Box $8,362,152 5,197 $8,362,152 5,197 $1,609

Location310,000 CFS Box $9,507,805 5,936 $1,145,653 739 $1,550

Location 3  15,000 CFS Box $13,113,845 7,742 $3,606,040 1,806 $1,997

Location 3  35,000 CFS Box $17,793,596 13,355 $4,679.752 5,613 $834

* Includes Real Estate

** Discount Rate 43⁄8%

No Action

Alt 1

Alt 2

Alt 3

Alt 4

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Figure 3.15: CE/IC Best Buy Plans

3.5.4 Other Factors

As part of the process to determine whether additional increments of ecosystem investment are worth the

cost, other factors were considered.

3.5.4.1 Recreational Benefits

The primary purpose of the White Ditch Study is to determine a cost effective ecosystem restoration plan,

however there are potential ancillary benefits to recreation. Recreation benefits are not being claimed to

justify the project but are useful in discerning among the final alternatives. A complete analysis can be

found in the Recreation Benefits Analysis Annex to Appendix K.

Given that the study area has 90,109 unit days per year and that each unit day is valued at $8.99, the total

annual monetary value of the recreational resource that would be affected by the White Ditch project is

$810,256. Given that the likelihood at success with fishing will increase and that environmental factors

will improve over time if the proposed project is implemented, the total annual monetary value of the

recreational resource will increase in the future compared to the annual monetary value of the recreational

resource should the proposed project not be implemented.

To better understand the economic impact of the proposed project on recreation, the analysis considered

effects over a 50-year period. The analysis uses the Federal discount rate for 2009 of 4 3/8%. The

following table summarizes the potential net present value of recreational resources for each alternative.

Alt 4

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Table 3.14: Net Increase in Recreation Benefits

Without

Project Alternative 1 Alternative 2 Alternative 3 Alternative 4

Net Present

Value of

Benefits over

50 years

$0 $1,206,000 $1,278,000 $1,421,000 $853,000

Annualized

Benefits $0 $57,284 $60,704 $67,496 $40,517

3.5.4.2 Desired Future Condition

The desired future established early on in the study was to achieve a no net loss of marsh acres at the end

of the 50-year period of analysis. While it was desirable to maximize the acres of marsh, it was uncertain

if that was possible given the various physical and operational constraints. The outputs of the ERDCSAND2 model are one of the key components in the WVA. Based on the ERDC-SAND2 results,

Alternative 4 provided the most net acres at the end of period of analysis. It is possible that the study area

could see a return to historic marsh acreages. Finally, the IC/CE analysis of the final array of alternatives

utilized WVA benefits based in part on an operation regime of Open Diversion during MarchApril with

a 1,000 cfs maintenance flow the remainder of the year. As can be seen in the figure below, under a

variety of operating regimes, Alternative 4 is the most capable at achieving no net loss.

Figure 3.16: FWP Acres at TY50 per Operational Plan

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3.5.4.3 Relative Sea Level Rise

An analysis of the high sea level rise scenario was conducted utilizing the ERDC-SAND2 model. The

model was used to determine whether a net loss or gain of marsh acreage would occur assuming a high

sea level rise scenario. Alternative 4 was the most effective at countering the effects of high sea level rise.

Alternative 4 could maintain marsh acreage out to approximately year 20 of the analysis which was then

quickly followed by a sharp decline and eventual collapse of the marsh and near total conversion to open

water. This result was based on the MarchApril Pulse plus a 1,000 cfs maintenance flow the rest of the

year. Tables 3.15 and 3.16 display these details. It should be noted however, that in the event high sea

level rise becomes a reality, Alternative 4 alone has the capability (assuming an open diversion) to divert

large enough quantities of freshwater, nutrients and sediments to overcome high sea level rise. Longer

term pulses of freshwater may result in large scale habitat switching to predominately freshwater types.

Further, long term freshwater pulses can saturate marsh vegetation and soils such that they are less

resilient to storm surge from seasonal events resulting in marsh displacement and conversion to open

water. There is strong public feeling that the prolonged operation of Caernarvon prior to Katrina

contributed to the severe loss of marsh. While not publicly acceptable at present (due to the anticipated

negative consequences of over-freshening the basin), if the collapse of the marsh within the study areas

was imminent, then having the ability to respond accordingly with a year round open diversion would be

critical.

Figure 3.17: The Recommended Plan as Compared to Evaluated Alternatives and Different Rates

of Projected Sea-Level Rise

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Table 3.15: ERDC-SAND2 Model Calculations of Acreages for the MDWD Project Area Under

Historical Sea Level Rise Rates

Gross Acres of Marsh

Project Life Years: 0 10 20 30 40 50

No Action Alternative (FWOP) 38,700 36,000 33,300 30,500 27,800 25,000

5,000 cfs Diversion Alternative 38,700 38,300 37,800 37,000 36,600 35,600

10,000 cfs Diversion Alternative 38,700 39,300 39,900 39,900 40,700 40,400

15,000 cfs Diversion Alternative 38,700 40,300 41,900 42,700 44,600 45,000

35,000 cfs Diversion Alternative 38,700 43,800 48,800 52,200 57,300 59,900

Note: the total project area for the Medium Diversion at White Ditch is 98,000 acres.

Table 3.16: ERDC-SAND2 Model Calculations of Acreages for the MDWD Project Area Under

the Intermediate and High Sea Level Rise Rates

Gross Acres of Marsh

Project Life Years: 0 10 20 30 40 50

Intermediate RSLR

No Action Alternative (FWOP) 38,700 34,900 30,900 26,500 21,800 16,900

35,000 cfs Diversion Alternative 38,700 42,800 46,600 48,500 51,800 52,400

High RSLR

No Action Alternative (FWOP) 38,700 31,500 23,700 14,000 2,900 0

35,000 cfs Diversion Alternative 38,700 39,500 39,600 36,300 33,800 27,600

Note: the total project area for the Medium Diversion at White Ditch is 98,000 acres.

3.5.4.4 Breton Sound Benefits

During the initial ERDC-SAND2 evaluation of alternatives in Step 2, it was determined that Alternative 4

has the capability to create marsh in the larger Breton Sound basin (i.e., beyond the MDWD project

boundary) through nutrient transfer. The modification of the Caernarvon Diversion is currently being

evaluated in an effort to investigate ways to enhance the capture of sediment. It may be possible, with

further analysis, to claim benefits to the Caernarvon study area as a result of implementing Alternative 4.

This may lead to cost savings for the Caernarvon project.

3.5.4.5 Adaptive Management

Alternative 4 provides the most robust capability for adapting to future risk and uncertainty. As discussed

above, Alternative 4 provides the most flexible management of operations to respond to sea level rise.

The difference between alternatives 3 and 4 is the outfall canals, ridges and flow notched weirs that are

responsible for distributing flows at 15,000 and 35,000 cfs, respectively. Just as sea level rise represents

uncertainty at one end of the spectrum, it is also possible that the sea level rise will not be any more

pronounced than historic levels. Also, as the science of operating large diversion structures is refined

throughout the period of analysis, it is possible to maximize environmental outputs with smaller

diversions. Finally, it is expected that as the project is actually operated and benefits are achieved, it will

be of value for the Federal, state and local partnership to revisit the goals and objectives associated with

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the study area. If the project is proving to be very successful at creating marsh it may no longer necessary

to maintain a 35,000 cfs diversion capability. To achieve this, O&M could be reduced resulting in outfall

canals, ridges and notched weir structures necessary to support a decreased diversion flow.

3.5.4.6 Acceptability, Completeness, Effectiveness, and Efficiency.

Alternative 4 meets the four evaluation criteria of the Economic and Environmental Principles and

Guidelines for Water and Related Land Resources Implementation Studies. Special consideration is also

given to these criteria within the larger context of the LCA Report (2004). The four criteria are

acceptability, completeness, effectiveness, and efficiency.

Acceptability. The plan is acceptable to Federal, state, tribal, local entities, and the public. It is compatible

with existing laws, regulations, and policies.

Completeness. The plan is complete. Realization of the plan does not depend on implementation of

actions outside the plan.

Effectiveness. The plan is effective. It addresses all the project objectives. It improves marsh habitat by

restoring deltaic process related to freshwater, nutrient and sediments. It does this by introducing the

quantities of freshwater, nutrients and sediments required (objectives) to achieve no net loss of marsh

during the period of analysis.

Efficiency. The plan is efficient. It is a cost-effective solution to the stated problems and objectives. No

other plan produces the same level of output more cost effectively. The plan is cost effective and provides

the greatest increase in benefits for the least increase in costs.

3.5.4.7 Selection of the Recommended Plan

The interagency team selected Alternative Plan 4 as the Tentatively Selected Plan. After approval by the

Civil Works Review Board, the Tentatively Selected Plan became known as Recommended Plan. It

would result in restoration of deltaic processes within the study area. In cooperation with the USFWS,

NOAA, and the State of Louisiana, the Corps has planned and would design a project that serves the

needs of the nation. The Recommended Plan best meets the study objectives, is the most flexible, and has

the most robust sustainable capability against relative sea level rise over the length of the 50-year

planning horizon. Once the Recommended Plan was determined, a year-long hydraulic model scenario

was run to analyze the effects of the plan over an annual cycle and these results are available in

Appendix L.

3.6 NER PLAN

The NER plan reasonably maximizes ecosystem restoration benefits compared to costs, considering the

cost effectiveness and incremental cost of implementing other restoration options. Alternative 4 Location

3  35,000 cfs, based on all considerations is the NER plan as well as the Recommended Plan. This

alternative involves construction of a structure capable of diverting up to 35,000 cfs consisting of ten 15-

x-15-foot box culverts. Additionally, there would be 31 acres of ridge and terrace creation, and 385 acres

of marsh creation utilizing dredged material from an adjacent 223 acres of canal construction. The

Recommended Plan has a primary operating regime of up to a maximum 35,000 cfs pulse during March

April with up to a maximum 1,000 cfs maintenance flow throughout the remainder of the 12-month cycle

(MayFebruary).

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The pulsed operational scheme is as important to the Recommended Plan as the proposed structure itself.

This combination of structure operation and size represents an optimization of desirable impacts and a

minimization of undesirable impacts. The pulse regime was chosen because it minimizes adverse effects

to natural socioeconomic resources and mimics a natural hydrologic regime. The MarchApril timeframe

is specifically meant to target sediment loads that are typically high in the Mississippi River during that

time of year. Although the Recommended Plan would be authorized to run up to 35,000 cfs during the

MarchApril timeframe, it does not necessarily mean it always would. If conditions were unfavorable,

flow through the structure could be reduced. For example, if the river was falling and sediment

concentrations were low, the structure could be closed. Conversely, it could be reopened when water

started rising and sediment levels in the river become elevated. Additionally, the 1,000 cfs maintenance

flow that is authorized from MayFebruary does not mean that it would continuously operate at 1,000 cfs.

It is possible that the structure would be completely shut down during much of the year in order to

encourage stabilization of estuarine salinity gradients. This flexibility to actively and adaptively manage

the operation within the recommended framework is a critical aspect of the Recommended Plan.

All of the diversion alternatives that were considered during the planning process resulted in freshening of

the Breton Sound basin to a comparable degree. The performance obtained by coupling a 35,000 cfs

structure with the MarchApril pulse regime is what makes the Recommended Plan unique among the

alternatives considered. It can attain project objectives while minimizing adverse impacts to natural and

manmade resources. It is the length of operation that makes the effect of a diversion on salinity regimes

either large or small, not the cubic-feet-per-second capacity of the diversion. From this perspective, a

large diversion achieves objectives while having negligible long-term effect on salinities and the

associated ecosystems. Although somewhat counterintuitive, it is important to note that a larger diversion

is in fact smaller when measuring the effect on balance of the estuarine system. For comparisons sake,

consider that smaller diversions would require a much longer run time in order to get close to achieving

similar sediment input results as the Recommended Plan. Longer runs could potentially disturb desirable

estuarine salinity gradients and create conditions unfavorable to vital natural socioeconomic resources

while also potentially creating favorable conditions for nuisance invasive plant species. There is also a

limit on how big a diversion can be dictated by the conditions of the project area. At the Phoenix location,

there is a limit on effectiveness of size because diversions larger than 35,000 cfs would exceed the

containment capacity of the River aux Chenes ridges. The Recommended Plan is the optimization point

between achieving project objectives and preserving estuarine balance.

The Recommended Plan is capable of achieving no-net-loss of marsh acreages during the period of

analysis (20152065). Estimated total marsh acreage at the end of the period of analysis is estimated to be

59,000 acres with approximately 32,000 net acres of new marsh created from the primary operating

regime. Further, the Recommended Plan is robust enough to achieve benefits through the period of

analysis taking into account both the intermediate and high rates of relative sea level rise. The

Recommended Plan is capable of achieving no-net-loss of marsh acres accounting for the intermediate

relative sea level rise rate. In summary, the Recommended Plan has the potential to reverse the decline of

marsh habitats occurring now and in the future within the project area and provides sustainability in the

face of uncertainty surrounding relative sea level rise.

The Recommended Plan will restore degraded marsh habitat and impaired deltaic processes between the

Mississippi River and River aux Chenes. This will be accomplished by reconnecting the study area to the

supplies of freshwater, nutrients and sediment that have been isolated within the Mississippi River by the

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MR&T levee. These benefits are represented by the 13,355 AAHUs expected from the Recommended

Plan at an estimated fully funded cost of $387,620,000 (Appendix L).

3.7 PLAN SELECTION – RECOMMENDED PLAN

3.7.1 Budget and Reauthorization

Section 902 of the WRDA of 1986 legislates a maximum total project cost. Projects to which this

limitation applies and for which increases in costs exceed the limitations established by Section 902

require further authorization by Congress raising the maximum cost established for the project. No funds

may be obligated or expended nor any credit afforded that would result in the maximum cost being

exceeded, unless the House and Senate committees on Appropriations have been notified that Section 106

of the Energy and Water Development Appropriations Act of 1997 will be utilized. The maximum project

cost allowed by Section 902 includes the authorized cost (adjusted for inflation), the current cost of any

studies, modifications, and actions authorized by the WRDA of 1986 or any later law, and 20 percent of

the authorized cost (without adjustment for inflation).

The authorized cost for the MDWD project in WRDA 2007 is $86,100,000. After Section 902 guidance is

applied, the adjusted budget (including inflation and adaptive management costs) of the project is

$126,686,400, projected to April 2014 dollars. The first cost of construction estimate for the

Recommended Plan is $365,201,000 and the fully funded Recommended Plan cost estimate is

$387,620,000 (mid-point of construction).

In order to proceed to the next phases of the proposed project, including Preconstruction, Engineering and

Design (PED) and construction, a Congressional reauthorization of the project that accounts for the

increase in project costs must be implemented. This could either happen with the enactment of a new

WRDA, perhaps as early as 2011, or with the enactment of other amending language that adjusts the

project as authorized in WRDA 2007 to account for the increase in the construction cost estimate.

3.7.2 Components

This alternative involves construction of a structure capable of diverting up to 35,000 cfs which involves

excavating a section of levee and constructing 10 each, sized 15 feet x 15 feet, box culverts with hydraulic

operated sluice gates, replacing the roadway, and constructing an outfall channel to carry freshwater and

sediment to the desired locations in the marsh. The plan also includes 31 acres of ridge and terrace

creation and 385 acres of marsh creation utilizing dredged material from an adjacent 223 acres of canal

being excavated and reconfigured to convey freshwater, sediments, and nutrients. Notched weirs would

be installed in outflow canals to restrict flow into the River aux Chenes and retain diverted water in the

project area.

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Table 3.17: Medium Diversion at White Ditch Authorized,

Adjusted, and Recommended Plan Cost Table

Authorized cost in WRDA 2007 Title VII, Section

7006 (e)(3)(A):

$86,100,000

* Cost Index Used:

EM 1110-2-1304 (Revised 31 Mar 2010)

CWBS Feature Code 15

Floodway Control & Diversion Structure

Cost Index Ratio:

1Q FY07 to 3Q FY14

1.15

** Current Project Cost Estimate:

(Inflation applied from 10/2006 to 4/2014)

$99,015,000

20% of Authorized Cost: $17,220,000

*** Monitoring & Adaptive Management:

(per WRDA 2007 Section 2039)

$11,143,400  $692,000

= $10,451,400

Maximum Cost Limited by Section 902 B: $99,015,000 + $17,220,000 + $10,451,400

= $126,686,400

Recommended Plan cost $387,620,000

Notes:

* The cost index applied to the current estimate through PED is derived from: EM 1110-2-1304,

March 31, 2000, Civil Works Construction Cost Index System (CWCCIS).

** For the purposes of applying the Cost Index to the WRDA Authorized Cost, each project was

adjusted for inflation from October 2006 price identified in WRDA 2007 to the mid-point of

construction.

*** This is the cost of any modifications required by law. This is derived from section 8.0 of each

projects Monitoring and Adaptive Management Plan minus the project monitoring cost found on the

LCA Cost Summary Worksheet  October 2004 Price Levels modified study cost December 20, 2004.

3.7.3 Design, Environmental, and Construction

Considerations

Major Project Considerations

 Ensure that stability of the Mississippi River Levee will not be compromised during construction.

 Continued access of LA 39, a major evacuation route, will be maintained during construction.

 Construction of the diversion will be done in accordance with industry standards.

 Construction of the channel conveyance systems will be done in accordance with industry

standards.

 Ridge restoration features will make use of beneficial spoil from the channel conveyance systems

and will be done in accordance with industry standards.

 Any excess spoil from the channel conveyance systems, beyond the ridge restoration features,

will go into marsh creation. These marsh creation features will be built to industry standards.

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3.7.4 Real Estate Requirements

The White Ditch study area is located in the Breton Sound estuary and covers the area extending north

and south from just south of Belair, Louisiana to the coastline of Louisiana and extending east and west

from the Mississippi River to River aux Chenes. This area extends about 50 km in the NW-SE directions

and about 30 km in the SW-NE direction. Subsidence, erosion, channelization, saltwater intrusion, storm

damage and the absence of freshwater, sediments and nutrients from the Mississippi River have all caused

significant adverse impacts to the White Ditch study area resulting in extensive wetland loss and

ecosystem degradation. There is an existing siphon at the mouth of White Ditch that was built in 1963 and

has not been in operation since 1991, except for brief episodes.

This restoration project would reverse the trend of habitat degradation between the Mississippi River and

the River Aux Chenes Ridges through Mississippi River re-introduction. This will be accomplished by reconnecting the Mississippi River to the study area through the use of a river diversion. The material

obtained through deepening/widening of the outfall channel will be used to stabilize ridges on either side

of the channel acting as containment. Dredge material will also be placed in strategic locations to build

marsh. Any excess dredged material is to be used for beneficial marsh creation.

Although the White Ditch diversion would increase the frequency of inundation in the interior marshes

during the MarchApril pulse, the project would not interfere with economically viable uses of the

property. Therefore, flowage easements are not necessary within the project area. In addition, there is no

acquisition of real estate interests proposed specifically to protect the benefits area of the project. Any

activity that may have a detrimental effect to the benefits area of the project is regulated. Therefore, the

risks over time would be minimal, aside from uncontrollable forces such as nature (hurricanes, etc.).

There is a total of 1,161.2 acres required for this project. The diversion structure will require

approximately 7.2 acres. Approximately 317.7 acres are necessary for the dredging of channels and

improvement/enhancement of associated channel ridges needed to maximize the conveyance of

freshwater and sediment. Approximately 381 acres are required to accommodate marsh restoration

efforts. Approximately 3 acres are needed to install notched weirs to redirect and restrict a certain level of

flow entering surrounding marshlands from the freshwater diversion. The additional 452.3 acres is

required for temporary work area. A more-detailed discussion regarding real estate requirements is in

Appendix J, Real Estate Plan.

3.7.5 Operations and Maintenance Considerations

For purposes of analysis, it was assumed that the diversion would operate at maximum capacity during

MarchApril with a 1,000 cfs maintenance flow for the remainder of the year. Although the

Recommended Plan would be authorized to run up to 35,000 cfs during the MarchApril timeframe, it

does not necessarily mean it always would. Additionally, the 1,000 cfs maintenance flow that is

authorized from MayFebruary does not mean that it would continuously operate at 1,000 cfs.

With the proposed diversion there will be needs for channel maintenance dredging and sluice gate

maintenance. It is estimated that there will need to be significant channel dredging every 10 years on the

proposed channel enhancement features. It is also assumed that there will be annual maintenance and

lubrication needs provided to the sluice gates. The project is not anticipated to induce shoaling in the

Mississippi River. However, if further analysis determines that the project increases maintenance

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dredging requirements for the Mississippi River, Baton Rouge to the Gulf of Mexico Project by inducing

shoaling, the incremental costs of any additional maintenance dredging would be a 100 percent nonFederal responsibility.

More-detailed information on the operations and maintenance of the proposed diversion can be found in

the engineering Appendix L.

Table 3.18: O&MRRR Annualization

Annualized

OperationsCulver

Operations

& Gate

Maintenance

Channel

Maintenance

Dredging

Present

Value

Rip Rap

Replacement

Present

Value

Structural

Rehabilitation

Present

Value

Annualized

Cost of

Present Value

Components

Total

Annualized

O&MRRR

Location 3 – 5,000 CFS Box $27,138 $7,760,630 $6,151,522 $1,309,900 $754,666 $781,804

Year 9 3,064,984 2,429,483

Year 19 1,996,436 1,582,490

Year 24 975,770

Year 29 1,300,416 1,030,785

Year 39 847,051 671,421

Year 49 551,743 437,343 334,130

Location 3 – 10,000 CFS Box $27,138 $9,418,113 $6,302,499 $1,309,900 $844,325 $871,463

Year 9 3,719,591 2,489,110

Year 19 2,422,826 1,621,329

Year 24 975,770

Year 29 1,578,154 1,056,083

Year 39 1,027,961 687,900

Year 49 669,582 448,077 334,130

Location 3 – 15,000 CFS Box $50,003 $11,985,939 $6,372,738 $3,446,525 $1,081,040 $1,131,044

Year 9 4,733,728 2,516,850

Year 19 3,083,404 1,639,398

Year 24 2,567,384

Year 29 2,008,434 1,067,853

Year 39 1,308,231 695,566

Year 49 852,141 453,070 879,141

Location 3 – 35,000 CFS Box $50,003 $18,403,436 $6,748,546 $3,446,525 $1,417,833 $1,467,836

Year 9 7,268,256 2,665,272

Year 19 4,734,316 1,736,075

Year 24 2,567,384

Year 29 3,083,787 1,130,826

Year 39 2,008,683 736,585

Year 49 1,308,394 479,788 879,141

3.7.6 Monitoring Plan and Adaptive Management

For the Medium Diversion at White Ditch project, there are a number of uncertainties associated with

ecosystem function and how the ecosystem components of interest will respond to the restoration project.

In addition, there are associated uncertainties about the best design and operation for the project. Using an

adaptive management approach during project planning provided a mechanism for building flexibility

into project design and for providing new knowledge to better define anticipated ecological responses.

This also enabled better selection of appropriate design and operating scenarios to meet the project

objectives. Additionally, an adaptive management approach will help define project success and identify

outcomes that should realistically be expected for the project.

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In order to utilize an adaptive management approach throughout project implementation, an effective

monitoring program will be required. Monitoring results will be used through an assessment process to

determine whether the project outcomes are consistent with original project goals and objectives. The

power of a monitoring program developed to support adaptive management lies in the establishment of

feedback between continued project monitoring and corresponding project management, where periodic

assessments are performed using monitoring data and reported back to the LCA Adaptive Management

Planning Team. This team will review the assessment reports and make recommendations to the LCA

Program Management Team for adaptive management actions. A carefully designed monitoring program

is central component of the White Ditch diversion adaptive management program.

According to the CECW-PB Memo dated 31 August 2009, Monitoring includes the systemic collection

and analysis of data that provides information useful for assessing project performance, determining

whether ecological success has been achieved, or whether adaptive management may be needed to attain

project benefits. The following discussion outlines key components of a monitoring plan that will

support the LCA Medium Diversion at White Ditch Adaptive Management Program. The plan identifies

performance measures along with desired outcomes and monitoring designs in relation to specific project

goals and objectives. Additional monitoring is identified under Supporting Information Need to help

further understand and corroborate project effects.

Objective 1: Maintain the current area of marsh habitat, of all types, that provide life requisite habitat

conditions for native coastal marsh fish and wildlife.

Performance Measure: Habitat and land:water classification

Desired Outcome: Reduce the rate of land loss (10 year post-construction trend) compared to the

pre-project condition (19852012).

Desired Outcome: Maintain and/or increase acreage of marsh habitats from pre-construction

estimates (41,206 acres)

Monitoring Design: Habitats will be classified using Landsat TM scenes collected in 3 pre- and 10

post-project years and Digital Orthophoto Quadrangles for 1 pre- and 2 post-project years, as well as

any available field data in the study area to assess land:water trends and habitat distribution.

Supporting Information Need: Finfish and shellfish status and trends will be assessed by increasing

the number of LDWF finfish and shellfish sampling sites in the White Ditch project area.

Objective 2: Restore adequate freshwater and nutrient inputs into the project area such that sustainable

areas of fresh, intermediate, brackish and saline marsh are present and existing areas of marsh acres are

maintained.

Performance Measure: Plant diversity and cover

Desired Outcome: Enhance floristic quality of marsh vegetation communities

Monitoring Design: Permanent vegetation monitoring stations will be established for assessing

project area vegetation communities. These stations will be sampled 3 years prior to project

completion to assess pre-project conditions and 10 years post-construction.

Supporting Information Need: Salinity and hydroperiod will be assessed by establishing nine

hydrologic sites in project and reference areas

Risk Endpoint: Nutrient loading

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Desired Outcome: Nutrient introductions do not contribute to reduced biomass of belowground plant

material when compared to pre-construction estimates

Monitoring Design: Belowground biomass will be sampled quarterly at the nine vegetation sites.

These stations will be sampled for 3 years prior to project completion to assess pre-project conditions

and sampled for 10 years post-construction. Nutrients (TN, Ammonia, Nitrate+Nitrite, TP), Metals,

Agro-chemicals, and Dissolved Oxygen will be measured every 2 months in the immediate project

outfall channel and at the nine hydrologic sites for 3 years prior to project completion to assess preproject conditions and sampled for 10 years post-construction.

Desired Outcome: Nutrient introductions do not contribute to expansion of floating aquatic

vegetation (water hyacinth) in project area when compared to pre-construction estimates

Monitoring Design: The distribution of water hyacinth throughout the project area will be tracked by

visual assessment of water hyacinth cover from overflights during summer.

Objective 3: Restore sediment inputs into the into the project area equivalent to an average of

approximately 1,328,580 cubic yards of sediment per year.

Performance Measure: Annual sediment discharge

Desired Outcome: Deliver 1.328 million cubic yards (equivalent to 1.422 million tons) of sediment

through the White Ditch diversion each year.

Monitoring Design: Hourly turbidity recorder will be deployed in the outfall channel and at nine

hydrologic sites and correlated to TSS to investigate this measure. The sites will be measured for 3

years prior to project completion to assess pre-project conditions and sampled for 10 years postconstruction.

Performance Measures: accretion and subsidence

Desired Outcome: Maintain marsh elevation within tidal frame (relative sea level rise = 0 cm yr-1).

Monitoring Design: SET/feldspar stations will be sampled at nine hydrologic sites for assessing

project area accretion and marsh elevation changes for 3 years prior to project completion to assess

pre-project conditions and sampled for 10 years post-construction.

An Adaptive Management Program for the Medium Diversion at White Ditch project is needed to ensure

the project achieves the desired outcomes. The Program will also facilitate coordination of projects within

the LCA Program and coordination among PDTs, the LCA S&T, and LCA Program Management. The

LCA Adaptive Management Planning Team will lead all LCA project and program adaptive management

recommendations and actions. This team is responsible for ensuring that monitoring data and assessments

are properly used in the adaptive management decision making process. If this team determines that

adaptive management actions are needed, the team will coordinate a path forward with project planners

and project managers. Other PDT members may be solicited as needed; for instance, if the adaptive

management measure is operational, Operations and Hydraulics representatives might be asked to

participate.

The costs associated with implementing these monitoring and adaptive management plans were estimated

based on currently available data and information developed during plan formulation as part of the

feasibility study. Because uncertainties remain as to the exact project features, monitoring elements, and

adaptive management opportunities, the costs estimates will be need to be refined in PED during the

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development of the detailed monitoring and adaptive management plans. The current total estimate for

implementing the monitoring, assessment, and adaptive management program is $9,363,400. Costs to be

incurred during PED and Construction include drafting of the detailed monitoring plan, monitoring site

establishment and pre-construction and construction data acquisition to establish baseline conditions. Cost

calculations for post construction monitoring were calculated for a 10-year (maximum) period post

construction. If ecological success is determined earlier (prior to 10 years post construction), the

monitoring program will cease and costs will decrease accordingly.

For further details on the Monitoring and Adaptive Management Plan, please refer to Appendix I.

3.7.7 Effectiveness of Recommended Plan in Meeting

Goals and Objectives

The Recommended Plan is the most effective alternative at meeting the Goals and Objectives of the

alternatives evaluated. It achieves no net loss of marsh acres and provides the requisite freshwater,

nutrients and sediments to sustain them. The Recommended Plan restores the functional wetland building

processes that have been impaired resulting in a degraded condition of the marsh. For each objective, the

Recommended Plan achieves the following:

 Maintain the current area of marsh habitat, of all types (41,206 acres) that provide life requisite

habitat conditions for native coastal marsh fish and wildlife.

The Recommended Plan is capable of achieving no net loss of marsh acreages during the period

of analysis (20152065) resulting in the maintenance of the current area of marsh habitat (41,206

acres). Estimated marsh acreage at the end of the period of analysis is estimated to be 48,000

73,000 acres, depending on the operating regime with approximately 60,000 total acres of marsh

resulting from the primary operating regime (Figure 3.16). Further, the Recommended Plan is

robust enough to achieve benefits through the period of analysis taking into account both the

intermediate and high rates of Relative Sea Level Rise. The Recommended Plan is capable of

achieving no net loss of marsh acres accounting for the intermediate Relative Sea Level Rise rate.

 Restore adequate freshwater and nutrient inputs into the project area such that sustainable areas

of fresh, intermediate, brackish and saline marsh are present and existing areas of marsh acres

are maintained.

Based on the availability of nutrient and freshwater supplies available in the Mississippi River in

the vicinity of Recommended Plans location (USGS Gages data) the Recommended Plan will

provide adequate supplies of both to maintain current areas of marsh. The pulsed operation of the

Recommended Plan will result in the maintenance of the overall distribution of marsh types

within the study area.

 Restore sediment inputs into the project area equivalent to an average of approximately

1,300,000 cubic yards of sediment per year.

The Recommended Plan is designed, relative to the sediment column in the Mississippi River, to

capture sufficient sediments to achieve the required to offset the projected loss rate over the 50-

year period of analysis.

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3.7.8 Effectiveness of Recommended Plan in Meeting

Environmental Operating Principles

The formulation of all of the alternatives considered for implementation was done in accordance with the

Environmental Operating Principles.

3.7.9 Compensatory Mitigation Measures

The project will provide positive ecosystem benefits to the study area. Temporary negative marsh impacts

associated with excavation of outfall canals and management structures will be compensated for by

creation of new marsh of better quality as a result of the reintroduction of freshwater, nutrients and

sediments into the study area. No mitigation measures are needed.

3.8 RISK AND UNCERTAINTY

3.8.1 Induced Shoaling

A complete qualitative analysis can be found in Appendix N. The diversion of significant quantities of

river sediments and water typically leads to unintended consequences, in that the diverted water and

sediment concentrations are not in the same proportion as in the river. The typical response is

sedimentation and shoaling in the main river downstream of the diversion. In the receiving diversion

channel, sedimentation or erosion could take place, depending on a variety of factors.

An additional consideration will be the sedimentation that may take place in interior distribution channels

after the flow is diverted. The MarchApril discharge will be directed into marsh and open water areas

and the portion of the diverted sediment load that is sand will settle quickly when the flow velocity

decreases. If it is desired for the sand load to be carried well away from the diversion point, the diversion

channel(s) must be carefully designed to maintain the velocity necessary to keep the sand load in

suspension. Similarly, silts and clays will begin depositing as velocities approach zero, so the diversion

channel design should minimize the creation of eddies or areas of low velocity.

The current operating plan for the Recommended Plan is limited to a diversion pulse of 35,000 cfs in

MarchApril of each year during the normal high flow period of the Mississippi River and a diversion of

1,000 cfs the rest of the year. This flow rate may not be experienced over the full 60-day period. The

proposed 35,000 cfs diversion will be the largest man-made diverted flow for wetland building on the

Lower Mississippi River, but the 1- to 2-month duration will be a modifying factor. The diversion should

approximate 5 percent or less of the main channel flow for most years. Although some deposition in the

downstream channel could occur, the 1- or 2-month duration should result in minimal shoaling, especially

in the navigation channel. Although the peak monthly sediment concentration normally occurs in March,

the peak monthly water discharge occurs in April with high flows typically continuing into May and later.

When the diversion is reduced to 1,000 cfs, some of this deposition could be resuspended by the

Mississippi flow and carried on downstream in the following months. On an annual basis, the net gain in

downstream deposition could be minimal. Specific sediment transport studies for the White Ditch

Diversion are required to better address the amount of deposition expected. If this diversion were operated

fully open outside the 2-month window that is described in the document, then there could be

significantly different impacts with some potentially being very negative. Specific sediment transport

studies to better address the amount of deposition expected will be conducted during PED. If further

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analysis determines that the project increases maintenance dredging requirements for the Mississippi

River, Baton Rouge to the Gulf of Mexico Project by inducing shoaling, the incremental costs of any

additional maintenance dredging would be a 100 percent non-Federal responsibility.

3.8.2 Relative Sea Level Rise

An analysis of the high sea level rise scenario was conducted utilizing the ERDC-SAND2 model. The

model was used to determine whether a net loss or gain of marsh acreage would occur assuming a high

sea level rise scenario. Alternative 4 was the most effective at countering the effects of high sea level rise.

Alternative 4 could maintain marsh acreage out to approximately year 20 of the analysis which was then

quickly followed by a sharp decline and eventual collapse of the marsh and near total conversion to open

water. This result was based on the MarchApril Pulse plus a 1,000 cfs maintenance flow the rest of the

year. It should be noted however, that in the event high sea level rise became a reality, Alternative 4 alone

has the capability (assuming an open diversion) to divert large enough quantities of freshwater, nutrients

and sediments to overcome high sea level rise. While not publicly acceptable at present, if the collapse of

the marsh within the study area was imminent, having the ability to respond accordingly with a yearround open diversion would be critical.

3.8.3 ERDC-SAND2 Model Background

The ERDC-SAND2 model was used to calculate acres of marsh created over the life of the project by

predicting accretion rates across the project area. Several sites were initially considered for the proposed

diversion; however, equivalent data for each site was not available. Ideally, data from each individual

potential diversion site could have been used to make this prediction. In an attempt to fairly compare each

site, the known water level data for the Mississippi River were taken from the Tarberts Landing gage,

which has daily records for the past 25 years. Sediment load data were obtained from the Belle Chasse

gage site, which is very close to the project area and representative of that section of the river. Together,

river level data and sediment load data were used to fairly and evenly compare one potential site to

another. There is some uncertainty associated with not using site-specific data for the analysis. However

the risk is minimal because the sediment data being used came from nearby stations and the site(s) that

were selected, especially those of the Final Array, appear to occur in areas of higher sediment

concentration than the location used in the model.

Verification of the ERDC-SAND2 model was conducted by simulating the effects of the freshwater

diversions (siphons) at Naomi and West Pointe à la Hache, both of which began operating in 1993, and

the larger Caernarvon Freshwater Diversion Project, which began operating in 1991. The model

verification work and other work with the model indicates that it is most applicable in interior marsh

systems. When applied to open bays or large lakes, it appears to substantially overestimate land-building.

This may be related to resuspension and export of deposited sediments, a process the model does not

address. The MDWD measures, however, are all generally interior locations which are handled well by

the model. Unfortunately, no examples of freshwater introductions without sediment are available to

verify the application of the ERDC-SAND2 model for nutrient-only situations.

The ERDC-SAND2 model uses the average water depth of the project area along with the sediment load

introduced into the area from the river to project future acres of marsh created. If the assumed average

water depth is greater or the introduced sediment load is less than what was assumed, a decrease in the

projected benefits could occur. It is uncertain as to the accuracy of the average water depth or actual

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sediment loads for the project area. The risk of encountering lower sediment loads than what was used in

the ERDC-SAND2 calculation is minimal. In fact, it is likely that the site will encounter heavier sediment

loads than what was used in the model due to the location selected. This would in turn likely increase

project benefits. For more information surrounding the ERDC-SAND2 equations used, see Appendix L.

3.8.4 Real Estate

Although the White Ditch diversion would increase the frequency of inundation in the interior marshes

during the MarchApril pulse, the project would not interfere with economically viable uses of the

property. The benefited area consists of low-lying marsh and shallow open water accessible only by boat

and vulnerable to tidal surges. The area was once subject to inundation by the Mississippi River during

spring high-water events, until levees were constructed along the river by the Mississippi River and

Tributaries project. The White Ditch diversion is formulated to mimic these natural, land-building flood

events by reintroducing freshwater, sediment and nutrients to the marshes in the project area. Over the 50-

year period of analysis, the project is anticipated to prevent the loss of approximately 13,750 acres of

emergent marsh in the project area and could potentially lead to a net gain in marsh acres. Economically

viable uses of the private property in the project area include recreational and commercial fishing and

hunting, as well as alligator farming. These uses are likely to be enhanced through operation of the

diversion because it will improve fish and wildlife values in the benefited area. All existing viable uses of

the marshlands are not expected to be detrimentally affected by the periodic change in water elevation.

Therefore, flowage easements are not necessary within the project area.

The benefited area of the White Ditch diversion is approximately 98,000 acres, nearly all of which is

marshlands. Any activity that may have a detrimental effect to the benefits area of the project is regulated.

Therefore, the risks over time would be minimal, aside from uncontrollable forces such as nature

(hurricanes, etc.). The types of activities that could be considered risks (oil/gas surface exploration,

excavation and fill activities, etc.) are currently regulated by the Louisiana Department of Natural

Resources, Office of Coastal Management, under Title 43, Chapter 7 of the Louisiana Administrative

Code. Specifically, Subchapter C, Section 723.A.2 requires permits for dredging or filling, urban

developments, energy development activity(exploration and transmission of oil/gas), mining

activities(surface & subsurface), surface water control, shoreline modification, recreational developments,

industrial development, drainage projects and any other activities or projects that would require a permit

or other form of consent or authorization from the U.S. Army Corps of Engineers, the Environmental

Protection Agency, or the Louisiana Department or Natural Resources. Additionally, activities in the

marshes (wetlands) are regulated by Section 404 of the Clean Water Act under the purview of the

USACE. Certain other activities are regulated by the U.S. Fish and Wildlife Service, the National Marine

Fisheries Service, the U.S. EPA, and the Louisiana Department of Environmental Quality.

More-detailed information regarding real estate is in Appendix J, Real Estate Plan.

3.8.5 Sediment Modeling

Sediment modeling of the Mississippi River was not conducted as part of this study due to time

constraints. Modeling is anticipated as part of PED to refine the diversion orientation and determine

whether intake structures would benefit the project. The uncertainty associated with the project outputs in

the absence of this information is small. The information used in the ERDC-Sand2 Model came from data

obtained from the Belle Chasse station, which represented the longest continuous dataset from a nearby

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location. When comparing the ERDC-Sand2 Model inputs to data that have been collected within the

project area, it is seen that the programs estimates are conservative. Data collected by the USGS in the

outfall canal of the existing White Ditch Siphon suggests that more sediment is available to enter into the

project area than represented by the Belle Chasse Data. Using the Belle Chasse Data, it is expected that

the Recommended Plan will deliver approximately 16,600 ton of sediment per day into the project area

during the MarchApril Pulse. Using the USGS sediment loads and the same pulse operation,

approximately 17,900 tons of sediment per day could enter the project area. This results in a potential 8%

increase in sediment loads from what are currently being projected.

Current research being done by the University of Texas in conjunction with the State of Louisiana also

suggests that there will be further increased sediment concentrations specifically at the Phoenix site. The

Phoenix location of the Recommended Plan was selected because there is a back-current in flows on the

Mississippi River. This will enhance the amount of sediment available in the area of the diversion as the

back-current will continually pull sediments into the diversion.

All available information points to the proposed location as a suitable location to capture Mississippi

River Sediments. However this will be evaluated further during the PED phase.

3.8.6 Reauthorization

The Recommended Plan for this project exceeds the cost authorization presented in the 2004 LCA Report.

The Recommended Plan exceeds the maximum project cost authorized in section 7006(e)(3) of the

WRDA 2007. The District Commander recommends seeking additional authorization in order to

construct the Recommended Plan/NER plan; however, the need to request additional authorization has the

potential to impact the project construction schedule.

3.8.7 Other Diversions

Some uncertainty exists as to the potential for future diversion on the Mississippi River to come online

during the period of analysis for the White Ditch Project. To the extent possible based on the available

information, the alternatives were formulated so as to produce benefits independent of other diversions.

However, as other regional diversions are planned or come online, operational coordination will need to

occur not only with White Ditch but in a systemic fashion. Joint operation of the proposed White Ditch

Diversion with the existing Caernarvon Diversion would be key to maintaining the condition of the

overall Breton Sound ecosystem. These two projects should not be operated independently of one another.

Modeling results and monitoring data suggests that Caernarvon has the ability to substantially freshen the

Breton Sound even without freshwater inputs from another source. In order for Breton Sound salinities to

rebound after the MarchApril pulse from the White Ditch Diversion, flow from Caernarvon would have

to be closely controlled. This will mean a change to the current operational plan. It will be crucial that

future modeling during PED for White Ditch and during Feasibility for the LCA Modification to

Caernarvon investigate joint operation. The LCA 4 Modification to Caernarvon will consider and account

for the proposed Medium Diversion at White Ditch project during its analysis. Additionally the existing

and proposed operational plans for both White Ditch and Caernarvon are subject to refinement based on

any newly acquired data. If significant changes are required, these would be properly disclosed to the

public and additional NEPA documents prepared as appropriate.

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3.8.8 Water Quality

In preparation of the Water Quality sections, the best available data was used to characterize existing

conditions, and best professional judgment was used to predict the projects impacts. During PED, more

data will be collected in receiving basin. Water quality parameters will be modeled as part of the

hydrologic modeling effort conducted during the PED phase. If the results of these modeling efforts

suggest that the projects water quality impacts will differ from those currently anticipated, then a

supplemental NEPA document may be prepared as appropriate. If further analysis during PED indicates

that the project is likely to have significant adverse impacts to water quality, then the projects features

and/or operation will be refined to mitigate the adverse impacts to the fullest extent possible, consistent

with the projects overall goals of creating marsh and restoring natural deltaic processes. The project will

also be adaptively managed post-construction to maximize the projects ability to meet its goals and

objectives and minimize adverse impacts. Appendix I details the Water Quality monitoring that would

occur pre- and post-project implementation.

3.8.9 Fisheries

In preparation of the Fisheries sections, the best available data was used to characterize existing

conditions and best professional judgment was used to predict the projects impacts. During PED, an

aquatic model will be used to further analyze the projects potential impacts on fisheries resources. If the

results of the modeling effort suggest that the projects impacts will differ from those currently

anticipated, then a supplemental NEPA document may be prepared as appropriate. Although maximizing

productivity of fisheries is not an objective of the project, fish populations may be monitored before and

after project completion if additional aquatic modeling suggests this is warranted. If further analysis

during PED indicates that the project is likely to have significant adverse impacts to fisheries resources,

then the projects features and/or operation will be refined to mitigate the adverse impacts to the fullest

extent possible, consistent with the projects overall goals of creating marsh and restoring natural deltaic

processes. The project will also be adaptively managed post-construction to maximize the projects ability

to meet its goals and objectives and minimize adverse impacts.

3.9 IMPLEMENTATION REQUIREMENTS

3.9.1 Milestone Schedule

Milestones Schedule

Final Report August 2010

Division Engineer Notice August 2010

Washington Level Review August 2010

State and Agency Review October 2010

Execute Cost-Sharing Agreement for PED November 2010

Chief of Engineers Report November 2010

Begin Preconstruction Engineering and Design 2010

ASA and OMB Review 2011

ASA Report to Congress 2011

Execute PPA November 2011

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Milestones Schedule

Receive Reauthorization from WRDA 2011** November 2011

Request Construction Funding per Reauthorization** November 2011

Complete Design Documentation Report June 2012

Complete Plans and Specifications July 2012

Complete Real Estate Acquisition July 2012

Advertise Construction AugustSeptember 2013

Start Construction November 2013

Complete Construction November 2016

Turnover Project to Local Sponsor 2016

Initiate Monitoring and Adaptive Management During PED

Complete Monitoring and Adaptive Management 2026

3.9.2 Implementation Responsibilities

The non-Federal sponsor shall, prior to implementation, agree to perform all of the local cooperation

requirements and non-Federal obligations. Local cooperation requirements and non-Federal sponsor

obligations include, but are not necessarily limited to:

a. Provide a minimum of 35 percent of total project costs as further specified below:

(1) Enter into an agreement which provides, prior to execution of the project partnership

agreement, 25 percent of design costs;

(2) Provide, during the first year of construction, any additional funds needed to cover the nonFederal share of design costs;

(3) Provide all lands, easements, and rights-of-way, including those required for relocations, the

borrowing of material, and the disposal of dredged or excavated material; perform or ensure

the performance of all relocations; and construct improvements required on lands, easements,

and rights-of-way to enable the disposal of dredged or excavated material that the

Government determines to be necessary for the construction, operation, maintenance, repair,

replacement, and rehabilitation of the project;

(4) Provide, during construction, any additional funds necessary to make its total contribution

equal to 35 percent of the total project costs allocated to the project;

b. Provide the non-Federal share of that portion of the costs of mitigation and data recovery

activities associated with historic preservation, that are in excess of 1 percent of the total amount

authorized to be appropriated for the project;

c. Not use funds provided by a Federal agency under any other Federal program, to satisfy, in whole

or in part, the non-Federal share of the cost of the project unless the Federal agency that provides

the funds determines that the funds are authorized to be used to carry out the study or project;

d. Not use project or lands, easements, and rights-of-way required for the project as a wetlands bank

or mitigation credit for any other project;

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e. For as long as the project remains authorized, operate, maintain, repair, replace, and rehabilitate

the project, or functional portions of the project, including mitigation, at no cost to the Federal

Government, in a manner compatible with the project's authorized purposes and in accordance

with applicable Federal and state laws and regulations and any specific directions prescribed by

the Federal Government;

f. Give the Federal Government a right to enter, at reasonable times and in a reasonable manner,

upon property that the non-Federal sponsor, now or hereafter, owns or controls for access to the

project for the purpose of inspecting, operating, maintaining, repairing, replacing, rehabilitating,

or completing the project. No completion, operation, maintenance, repair, replacement, or

rehabilitation by the Federal Government shall relieve the non-Federal sponsor of responsibility

to meet the non-Federal sponsor's obligations, or to preclude the Federal Government from

pursuing any other remedy at law or equity to ensure faithful performance;

g. Hold and save the United States free from all damages arising from the construction, operation,

maintenance, repair, replacement, and rehabilitation of the project and any project-related

betterments, except for damages due to the fault or negligence of the United States or its

contractors;

h. Perform, or cause to be performed, any investigations for hazardous substances that are

determined necessary to identify the existence and extent of any hazardous substances regulated

under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA),

Public Law 96-510, as amended (42 U.S.C. 9601-9675), that may exist in, on, or under lands,

easements, or rights-of-way that the Federal Government determines to be required for the initial

construction, periodic nourishment, operation, and maintenance of the project. However, for lands

that the Federal Government determines to be subject to the navigation servitude, only the

Federal Government shall perform such investigations unless the Federal Government provides

the non-Federal sponsor with prior specific written direction, in which case the non-Federal

sponsor shall perform such investigations in accordance with such written direction;

i. Assume, as between the Federal Government and the non-Federal sponsor, complete financial

responsibility for all necessary cleanup and response costs of any CERCLA regulated materials

located in, on, or under lands, easements, or rights-of-way that the Federal Government

determines to be necessary for the initial construction, periodic nourishment, operation, or

maintenance of the project;

j. Agree that, as between the Federal Government and the non-Federal sponsor, the non-Federal

sponsor shall be considered the operator of the project for the purpose of CERCLA liability, and

to the maximum extent practicable, operate, maintain, and repair the project in a manner that

would not cause liability to arise under CERCLA;

k. Prevent obstructions of or encroachments on the project (including prescribing and enforcing

regulations to prevent such obstruction or encroachments) which might reduce ecosystem

restoration benefits, hinder operation and maintenance, or interfere with the project's proper

function, such as any new developments on project lands or the addition of facilities which would

degrade the benefits of the project;

l. Keep and maintain books, records, documents, and other evidence pertaining to costs and

expenses incurred pursuant to the project, for a minimum of 3 years after completion of the

accounting for which such books, records, documents, and other evidence is required, to the

extent and in such detail as would properly reflect total costs of construction of the project, and in

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accordance with the standards for financial management systems set forth in the Uniform

Administrative Requirements for Grants and Cooperative Agreements to State and Local

Governments at 32 Code of Federal Regulations (CFR) Section 33.20;

m. Comply with Section 221 of Public Law 91-611, Flood Control Act of 1970, as amended (42

U.S.C. 1962d-5), and Section 103 of the Water Resources Development Act of 1986, Public Law

99-662, as amended (33 U.S.C. 2213), which provides that the Secretary of the Army shall not

commence the construction of any water resources project or separable element thereof, until the

non-Federal sponsor has entered into a written agreement to furnish its required cooperation for

the project or separable element;

n. Comply with all applicable Federal and state laws and regulations, including, but not limited to,

Section 601 of the Civil Rights Act of 1964, Public Law 88-352 (42 U.S.C. 2000d), and

Department of Defense Directive 5500.11 issued pursuant thereto, as well as Army Regulation

600-7, entitled Nondiscrimination on the Basis of Handicap in Programs and Activities Assisted

or Conducted by the Department of the Army, and all applicable Federal labor standards and

requirements, including but not limited to 40 U.S.C. 3141- 3148 and 40 U.S.C. 3701 - 3708

(revising, codifying, and enacting without substantial change the provisions of the Davis-Bacon

Act (formerly 40 U.S.C. 276a et seq.), the Contract Work Hours and Safety Standards Act

(formerly 40 U.S.C. 327 et seq.) and the Copeland Anti-Kickback Act (formerly 40 U.S.C. 276c

et seq.); and

o. Comply with all applicable provisions of the Uniform Relocation Assistance and Real Property

Acquisition Policies Act of 1970, Public Law 91-646, as amended (42 U.S.C. 4601-4655), and

the Uniform Regulations contained in 49 CFR Part 24, in acquiring lands, easements, and rightsof-way necessary for the initial construction, periodic nourishment, operation, and maintenance of

the project, including those necessary for relocations, borrow materials, and dredged or excavated

material disposal, and inform all affected persons of applicable benefits, policies, and procedures

in connection with said Act.

3.9.3 Cost Sharing

The State of Louisiana, acting through the CPRA, will be the non-Federal sponsor for the LCA MDWD

project. In November 2008, the USACE and CPRA executed a single Feasibility Cost-Share Agreement

covering six Louisiana Coastal Area near-term plan elements listed in Section 7006(e) of the Water

Resources Development Act of 2007. The six features each underwent a separate feasibility analysis and

environmental compliance analysis culminating in a single master feasibility document. The cost-share

during the feasibility phase was 50% Federal and 50% non-Federal, however, the individual elements

have been divided so that each entity has lead responsibility for preparing three of the six report

components. At the end of the feasibility phase the total cost for all elements will have been shared on a

50/50 basis, yet for work on each individual element during the feasibility phase the ratio of funds

expended by either the Federal or non-Federal sponsor will be higher depending upon their level of

responsibility. The Corps has the technical planning lead for this particular LCA project element.

Following the feasibility phase, the cost share for the planning, design and construction of the project will

be 65% Federal and 35% non-Federal. The CPRA must provide all lands, easements, rights-of-way,

utility or public facility relocations, and disposal areas (LERRDs) required for the project. Operation,

Maintenance, Repair, Replacement and Rehabilitation (OMRR&R) of the project would be a 100%

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CPRA responsibility. Additionally, project monitoring and any Adaptive Management deemed necessary

will be cost shared at 65/35 for the first 10 years of the project life.

Under current law, authority for the non-Federal sponsor to receive credit for construction activities is

limited. Section 7007(a) of WRDA 2007 authorizes the Secretary to credit, toward the non-Federal share

of the cost of a study or project under this title the cost of work carried out in the coastal Louisiana

ecosystem by the non-Federal interest for the project before the date of the execution of the partnership

agreement for the study or project. In addition, section 7007(a) incorporates the requirement of section

221 of the Flood Control Act of 1970, as amended, (42 U.S.C. 1962d-5b) that the Government and nonFederal sponsor must enter into a separate agreement for any work that will be carried out prior to

execution of the partnership agreement. In other words, work undertaken by the non-Federal sponsor prior

to (but not after) execution of the project partnership agreement (PPA) is eligible for credit subject to

execution of a separate agreement covering such work before it is undertaken. For design work that the

non-Federal sponsor proposes to undertake, the Design Agreement will serve as the required separate

agreement. For construction work that the non-Federal sponsor proposes to undertake, an In-Kind

Memorandum of Understanding will be required. Opportunities to enter into an In-Kind MOU for

construction activities will depend on the schedule for entering into the PPA for a project.

Section 7007(d) provides that credit afforded under section 7007 that is in excess of the non-Federal

cost share for a study or project authorized in Title VII of the Water Resources Development Act of 2007

may be applied toward the non-Federal cost share of any other study or project under that title. Excess

credit will be applied only toward another study or project involving the same sponsor. In addition,

excess credit will be applied within project phases (i.e., study to study, design to design, and

construction to construction). At this time, it is anticipated that that there are limited opportunities for the

application of excess credit from other Title VII projects toward these projects.

Table 3.19 provides the distribution of costs for the fully funded project cost estimate. The fully funded

cost of implementing the Recommended Plan is estimated to be $387,620,000 (Engineering Appendix L).

The Federal Government would provide 65% of the first cost of implementing the Recommended Plan

including PED, construction, and construction management, which is estimated to total $251,953,000.

The State of Louisiana would be responsible for providing 35% of the First Cost of implementing the

Recommended Plan. The 35% share of the project cost includes the State of Louisiana's responsibility for

providing all LERRDs. The estimated costs are $135,667,000 in cash with $508,000 in LERRD credit.

The State of Louisiana also would be responsible for OMRR&R of project features. The operation and

maintenance costs are anticipated to be minimal over the 50-year period of analysis at an average annual

cost of $1,467,836.

3.9.4 Environmental Commitments

Mitigation measures are proposed to avoid or minimize impacts that would otherwise occur as a result of

the implementation of the preferred alternative. These environmental and related commitments would be

implemented by construction contractors or management authorities. Some commitments, such as

monitoring or adaptive management would continue beyond completion of construction of facilities.

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Table 3.19: Cost Sharing

Non-Federal Federal

Project Feature Total Cost % Cost % Cost

Total first cost of

construction1 $365,201,000 35 $127,820,000 65 $237,381,000

LERRD credit $494,000 100 $494,000 0 $0

Monitoring & adaptive

management

$11,143,000 35 $3,900,000 65 $7,243,000

OMRR&R2 $1,468,000 100 $1,468,000 0 $0

1 Total first cost of construction is based on the sum of the PED; construction management (i.e., supervision

and administration); LERRDs; and monitoring and adaptive management and is based on October 2010

price levels. 2 Average annual cost based on October 2010 price levels.

Throughout the planning process, efforts have been made to avoid impacts to the extent practicable. If

avoidance could not be achieved, mitigation measures were developed to reduce the magnitude and extent

of the impact. The Recommended Plan would impact approximately 277 acres of intermediate marsh and

363 acres of shallow open water for construction of the diversion. Approximately 223 acres of

intermediate marsh and shallow open water would be excavated for the outfall channel. However,

creation of approximately 385 acres of intermediate marsh habitat, nourishment of 35,000 cumulative

acres of emergent marsh habitat, and creation of 31 acres of ridge habitat would mitigate for wetland

impacts resulting from construction activities.

Best management practices would be included in construction specifications and they would be employed

during construction activities to minimize environmental effects. Many of these best management

measures are required by Federal, State, or local laws and regulations, regardless of whether they are

specifically identified in this document or not. Project implementation would comply with all relevant

Federal, State, and local laws, ordinances, regulations, and standards during the implementation of the

preferred alternative. Implementation of the environmental commitments would be documented to track

execution and completion of the environmental commitments.

Fishery modeling and habitat change modeling will be performed during the PED phase. The cost and

schedule for this will be incorporated into the PMP being developed by the USACE for the PED Phase.

At this time a SOW is being developed as part of the Donaldsonville to the Gulf project to look a various

models and develop a white paper on the best use of them. The intent of these models is to support

adaptive management of this project.

A summary of the environmental and related commitments made during the planning process and

incorporated into the proposed project plan include the following:

 Ensure construction contractors limit ground disturbance to the smallest extent feasible.

 Use accepted erosion control measures during construction.

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 Conduct a search for bald eagle, other raptors and colonial nesting wading bird active nests within

three-quarters of a mile from proposed disturbance activities prior to construction. Appropriate

protective measures and no-work distance restrictions would be implemented to avoid or

minimize nest disturbance if active nests are identified

 Contact pipeline and gas well companies prior to construction activities to identify and avoid

existing hazards.

 Implement best management practices and measures contained in erosion control guidelines to

control soil erosion from construction areas.

 Implement measures to control fugitive dust during construction.

 Implement a program to compensate for losses of archaeological sites (if any) that would occur as

a result of construction and operation of the proposed project.

 Fishery modeling and habitat change modeling will be performed during the PED phase. The cost

and schedule for this will be incorporated into the PMP being developed by the USACE for the

PED Phase. At this time a SOW is being developed as part of the Donaldsonville to the Gulf

project to look at various models and develop a white paper on the best use of them. The intent of

these models is to support adaptive management of this project.

 An operating plan will be developed based on a maximum of a 2-month pulse. If this diversion

were operated fully open outside the 2-month window that is described in the document, then

there could be significantly different impacts with some potentially being very negative.

 The USACE will follow the Reasonable and Prudent Measures and Terms and Conditions as

described in the USFWS Biological Opinion for Pallid sturgeon which can be found in Appendix

A and summarized in Section 5.11.5. The USACE is aware that the reinitiation of formal

consultation is required where discretionary Federal agency involvement or control over the

action has been retained (or is authorized by law) and if: (1) the amount or extent of incidental

take (i.e., the habitat acreage amount described herein) is exceeded; (2) new information reveals

effects of the agency action that may affect listed species or critical habitat in a manner or to an

extent not considered in this opinion; (3) the agency action is subsequently modified in a manner

that causes an effect to the listed species or critical habitat not considered in this opinion; or (4) a

new species is listed or critical habitat designated that may be affected by the action. In instances

where the amount or extent of incidental take is exceeded, any operations causing such take shall

cease pending reinitiation.

3.9.5 Financial Requirements

3.9.5.1 Sponsorship Agreement

Prior to the start of construction, the State of Louisiana will be required to enter into a Project Partnership

Agreement (PPA) with the Federal Government and satisfy State laws and all applicable regulations. In

general, the items included in the PPA have been outlined in the previous paragraphs.

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3.9.5.2 Financial Requirements

It is expected that the CPRA will have the capacity to provide the required local cooperation for the

Recommended Plan. A project schedule and cost estimate will be provided to the CPRA so that it may

develop a financing plan. A standard cost share percentage of 65% Federal and 35% non-Federal would

be applied to the total first cost of the project. The 35% share of the project cost includes the State of

Louisiana's responsibility for providing all LERRDs.

Section 7007(b) of WRDA 2007 provides that The non-Federal interest may use, and the Secretary shall

accept, funds provided by a Federal agency under any other Federal program, to satisfy, in whole or part,

the non-Federal share of the cost of the study or project if the Federal agency that provides the funds

determines that the funds are authorized to carry out the study or project. If the Mineral Management

Services determines in writing that funds it provides to the non- Federal sponsor under the Energy Policy

Act of 2005 (Coastal Impact Assistance Program - CIAP) and the Gulf of Mexico Energy Security Act of

2006 (GOMESA) are authorized to be used to carry out the Medium Diversion at White Ditch project, the

non-Federal sponsor can use those funds toward satisfying its local cooperation for the project, including

the non-Federal sponsor's acquisition of Lands, Easements, Relocations, Rights of-way and Disposals

(LERRDs) required for the project.

By letters dated July 2, 2009, and December 18, 2009, the Minerals Management Service and the USACE

established a process for the Minerals Management Service to provide its written determination regarding

the acceptability of the use of CIAP funds for LCA studies, projects, and programs. That process provides

that the Minerals Management Services' written determination for a specific study, project, or program

will take the form of the grant award document for that activity.

3.9.5.3 Local Cooperation

The CPRA provided a letter of intent to serve as the non-Federal sponsor for the project on August 9,

2010. A copy of the letter can be found in Attachment 2.

3.9.5.4 Project Management Plan

A Project Management Plan (PMP) for implementation of the Recommended Plan will be prepared. The

PMP will describe activities, responsibilities, schedules, and costs required for the Plans and

Specifications phase and construction of the project. The Plans and Specifications phase will last for an

estimated 24 months at a total cost of $36,980,000.

3.9.5.5 Procedures for Project Implementation

Under the 2007 WRDA Section 7006, the LCA program has authority for feasibility-level reports of six

near-term critical restoration features. Project construction is contingent upon a favorable Chief's report

by December 31, 2010. The excerpt below from WRDA outlines the project authority for this report for

the Medium Diversion at White Ditch project.

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SEC. 7006. CONSTRUCTION.

(3) PROJECTS SUBJECT TO REPORTS.-

...

(B) CONSTRUCTION.-The Secretary may carry out the projects under

subparagraph (A) substantially in accordance with the plans and subject to

the conditions, recommended in a final report of the Chief of Engineers if a

favorable report of the Chief is completed by not later than December 31,

2010.

...

The Recommended Plan for the Medium Diversion at White Ditch project exceeds its total authorized

cost authorized under Section 7006(e)(3)(A)(v) of WRDA 2007 and Section 902 of WRDA 1986 as

amended. As such, additional authority must be enacted to enable the Recommended Plan to be carried

out with these increased costs. Future actions necessary for project approval and implementation are

summarized as follows:

1. The U.S. Army Corps of Engineers Mississippi Valley Division Commander will review the final

report and then issue a public notice announcing completion of the final report. This is referred to

as the Division Engineer's Notice, or DE's Notice.

2. The report will then be submitted to Headquarters, U.S. Army Corps of Engineers (HQUSACE),

and the Office of the Assistant Secretary of the Army for Civil Works (ASA (CW)) for

concurrent Washington level review.

3. The 30-day State and agency review and coordination of the EIS will be ongoing concurrently

during the HQUSACE review.

4. Concurrent Washington level review by HQUSACE and ASA(CW) will conclude with a

HQUSACE staff assessment, the 30-day State and agency review, review input by the ASA(CW),

HQUSACE final assessment, a field visit and meeting, if necessary, and the documentation of

report review prepared by HQUSACE.

5. The Washington level decision-making process will follow the decision-making sequence of

HQUSACE and ASA(CW), once the documentation of report review has been completed. There

will be a briefing, if necessary, for the Designated Senior Representatives of Decision-Makers to

resolve any outstanding issues. The Chief of Engineers will provide his recommendations on the

report to the ASA(CW), who will provide the report and proposed recommendations to the Office

of Management and Budget (OMB) to obtain their views and comments on whether the proposed

recommendations are consistent with Administrative policies. Prior to the transmittal of the report

to the Congress, the Non-Federal Sponsor, the State of Louisiana, interested Federal agencies,

and other parties will be advised of any significant modifications made to the recommendations

and will be afforded an opportunity to comment further.

6. The report will then be transmitted to Congress for project authorization with the Chief of

Engineer's report, ASA(CW) report, State and agency comments, and Office of Management and

Budget comments.

7. Congress will have to enact law to increase the authorized cost of the project.

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8. Funds could be provided, when appropriated in the budget, for Preconstruction Engineering and

Design (PED) upon issuance of the Division Engineer's public notice, announcing the completion

of the final report and pending project funding authorization. A Design Cooperation Agreement

will need to be developed and executed between the Federal Government and the State of

Louisiana, whereby the sponsor will provide 25% of the cost of PED studies.

9. The U.S. Army Corps of Engineers will complete final design and plans and specifications for

project construction.

10. Subsequent to appropriation of construction funds by Congress, formal assurances of local

cooperation in the form of a Project Partnership Agreement (PPA) will be required from the State

of Louisiana.

11. The State of Louisiana will be required to provide all real estate requirements for project

implementation.

12. Bids for construction will be advertised and contracts awarded.

13. Upon completion of construction, the Corps' acceptance from the contractor and notice of

construction completion for the project (or a functional portion of the project) to the non-Federal

sponsor will proceed or be concurrent with the delivery of an O&M manual and as-built

drawings. The State of Louisiana will be responsible for OMRR&R of the project in accordance

with guidelines provided by the U.S. Army Corps of Engineers.

3.9.6 Views of Non-Federal Sponsor

CPRA, the non-Federal sponsor, has expressed the desire for implementing the LCA MDWD project and

sponsoring the project construction in accordance with the items of local cooperation that are set forth in

the recommendations chapter of this report. In addition, CPRA supports the NER/Recommended Plan

since this plan has the greatest potential to restore the study area to historic conditions for marsh acreage

in addition to being able to offset effects from the range of potential sea-level rise. The plan is also costeffective and provides the most benefits of all the best-buy plans in the final array. However, due to

authorized cost limitations in WRDA 2007, the project may require additional Congressional

authorization to increase funding and allow the implementation of the NER/Recommended Plan to fully

address the ecosystem needs identified in this report.

The State of Louisiana fully supports the project. The state recognizes that the USACEs position is that

Section 7007 does not authorize credit for work carried out after the date of a partnership agreement.

However, the State disagrees with the USACEs position and intends to continue to seek a change in law

that would allow in-kind contribution credit for work carried out after the date of a Project Partnership

Agreement and that would allow for such in-kind contributions credit to carry over between LCA

Program components (i.e., excess credit for work undertaken after signing of the project partnership

agreement for one project may be carried over for credit to another project). Nevertheless, while the State

is of the opinion that its view is consistent with the authority and Congressional intent under WRDA

2007, the State fully intends to proceed with the project under the Corps interpretation of current law and

to meet all non-Federal financial and other obligations outlined by the USACE in this report until such

time as the law is changed.

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4.0 AFFECTED ENVIRONMENT

This chapter describes the climate, geomorphic and physiographic setting, and the historic and existing

conditions for the following important resources: soils; coastal vegetation; wildlife; fisheries; plankton;

benthos; essential fish habitat (EFH); threatened and endangered species; hydrology (including flow and

water levels, and sediment); water quality; recreation; public lands; cultural and historic resources;

aesthetics; air quality; socioeconomic and human resources (including population; infrastructure;

employment and income; navigation; oil, gas, and utilities; pipelines; commercial fisheries; oyster leases;

and flood control and hurricane protection). In addition, the characterization of noise and hazardous,

toxic, and radioactive waste (HTRW) in the project area are presented.

A resource is considered important if it is recognized by statutory authorities including laws, regulations,

Executive Orders (EO), policies, rules, or guidance; if it is recognized as important by some segment of

the general public; or if it is determined to be important based on technical or scientific criteria. The

following sections discuss historic and existing conditions of each important resource occurring within

the project area.

4.1 ENVIRONMENTAL SETTING OF STUDY AREA

The MDWD project study area is located in LCA Subprovince 1, and comprises part of the Breton Sound

hydrologic basin in Plaquemines Parish, Louisiana. Plaquemines Parish is located within the Central Gulf

Coastal Plain in southeastern coastal Louisiana. The parish encompasses the current delta of the

Mississippi River, which was built up from alluvial silt deposited over centuries when the river was leveefree and overflowed its banks. Elevations range from sea level along the Gulf Coast, to approximately

+15 feet above sea level along levee ridges. The project area is located within the Mississippi River

Deltaic Plain, with the Mississippi River acting as the primary influence on geomorphic processes in the

delta region.

4.1.1 Location

The boundary of the project study area encompasses over 98,000 acres of intermediate to brackish

intertidal wetland habitats. The boundary follows distinct landscape features beginning in the north with

the confluence of the non-Federal back levee and the Forty-Arpent canal, extending along the non-Federal

back levee, the Mississippi River levee, the Federal back levee and along the left descending natural bank

of the Mississippi River to the west; past American Bay, California Bay, and through Breton Sound, near

Bay Gardene to the south; into and along River aux Chenes to the east, and back to the point of

beginning. The area has been significantly impacted by recent tropical storms and hurricanes and is

currently isolated from the beneficial effects of the Caernarvon freshwater diversion, located at the

northern end of the Breton Sound Basin.

4.1.2 Climate

The climate of the project area is subtropical marine with long humid summers and short moderate

winters. The climate is strongly influenced by the water surface of many sounds, bays, lakes and the Gulf

of Mexico and seasonal changes in atmospheric circulation. During the fall and winter, the study area

experiences cold continental air masses which produce frontal passages with temperature drops. During

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the spring and summer, the study area experiences tropical air masses which produce a warm, moist

airflow conducive to thunderstorm development (LACPR 2008).

The study area is also subject to periods of drought, flood, tropical waves, tropical depressions, tropical

storms and hurricanes. These weather systems can cause considerable property and environmental

damage and loss of human life. Historical data from 1899 to 2007 indicate that 30 hurricanes and 41

tropical storms have made landfall along the Louisiana coastline (NOAA 2009). The largest recent

hurricanes were Katrina and Rita in 2005, which caused considerable damage in the study area. Hurricane

Gustav, while much smaller and less intense, caused additional damage in the study area. Hurricane Ike,

which made landfall in Galveston, Texas in 2008, caused flooding and wind damage in coastal areas as it

passed the Louisiana Coast.

Average annual temperature in the area is 67° (F), with monthly temperatures varying from the mid-90°s

(F) in July and August, to the mid-30°s (F) in January and February. Average annual precipitation is 57.0

inches, varying from a monthly average of 7.5 inches in July, to an average of 3.5 inches in October.

Recent climate research by the Intergovernmental Panel on Climate Change (IPCC) predicts continued or

accelerated global warming for the 21st Century and possibly beyond, which will cause a continued or

accelerated rise in global mean sea-level.

4.1.3 Geomorphic and Physiographic Setting

The project study area is located within the Plaquemines-Balize delta complex, one of six such complexes

that make up the Mississippi River Deltaic Plain. The primary geomorphic influence in this region is the

natural hydrologic process referred to as the delta cycle. The delta cycle is a dynamic and episodic

process alternating between periods of seaward progradation of deltas (regressive deposition) and the

subsequent landward retreat of deltaic headlands as deltas are abandoned, reworked, and submerged by

marine waters (transgressive deposition). The Plaquemines-Balize complex is in the latter phase of the

cycle. More detailed information on the delta cycle was provided in the LCA Final Programmatic

Environmental Impact Statement (FPEIS).

4.2 SIGNIFICANT RESOURCES

4.2.1 Soils and Waterbottoms

This resource is institutionally significant because of the Council on Environmental Quality (CEQ)

memorandum of August 11, 1980, entitled, Analysis of Impacts on Prime or Unique Agricultural Lands

in Implementing the National Environmental Policy Act (NEPA); Executive Order 11990  Protection of

Wetlands; and the Agriculture and Food Act of 1981 (Public Law 97-98) containing the Farmland

Protection Policy Act (P.L. 97-98; 7 U.S.C. 4201 et seq.). Coastal land loss is directly and inextricably

linked to the five factors of soil formation (parent material; climate; plants and other organisms; relief;

and time). These factors are discussed in detail in the FPEIS for the 2004 LCA report.

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4.2.1.1 Soils and Waterbottoms

4.2.1.1.1 Historic Conditions

The soils in the Louisiana coastal zone formed in either alluvial sediments or loess, and many have

accumulations of organic material in the upper part. Some soils are organic throughout, and some, nearest

to the coast, formed in marine sediments. Deltaic processes have played a significant role in the types of

soil present in the project area. The dynamic and episodic deltaic building processes alternates between

periods of seaward progradation of deltas (regressive deposition) and the subsequent landward retreat of

deltaic headlands as deltas are abandoned, reworked, and submerged by marine waters (transgressive

deposition). The types of soils present today in much of the project area are characterized by the

depositional environments associated with both of these phases of the deltaic cycle.

4.2.1.1.2 Existing Conditions

The feasibility report for the Whites Ditch Diversion Siphon Outfall Management Plan (United States

Department of Agriculture, Soil Conservation Services (USDA-SCS, 1992)) noted that there are several

different soils mapped in the project area. These are Commerce, Sharkey, Clovelly, Lafitte, and Gentilly.

Commerce and Sharkey soils are poorly drained, firm mineral soils formed in loamy or clayey alluvium.

Gentilly soils are very poorly drained, very slowly permeable, semi-fluid, mineral soils formed in clay

alluvium. Clovelly and Lafitte soils are both level, very poorly drained, semi-fluid, organic soils formed

in accumulation of herbaceous plant material in brackish marshes. The Commerce and Sharkey soil series

are classified as prime farmland soils where rarely flooded and adequately drained, while the Gentilly,

Clovelly, and Lafitte soil series are classified as hydric soils.

4.2.2 Hydrology

This resource is institutionally important because of the Clean Water Act of 1977 (CWA), as amended.

The Mississippi River is technically important because it provides habitat for various species of wildlife,

finfish and shellfish. The Mississippi River is publicly important because of its use as a major

navigational channel and it recreational use for fishing, boating and bird watching.

4.2.2.1 Flow and Water Levels

4.2.2.1.1 Historic Conditions

Over geologic history, the course of the Mississippi River has changed several times through the deltaswitching process. Formation of a new delta lobe occurred roughly once every 1,000 years in response to

changes in the flow path of the Mississippi River into the Gulf over the past 5,000-6,000 years; the

modern delta consequently consists of smaller delta complexes formed over the past 8,000 years (Fisk

1944; Frazier 1967; Penland and Boyd, 1985; Autin et al., 1991, Saucier 1994). Major distributaries over

this period have included Bayous Lafourche, Terrebonne, Des Families, Barataria, and to a lesser extent,

the Atchafalaya River (USACE 2000).

Historically, the Lower Mississippi River was prone to frequent spring floods that caused catastrophic

damage and loss of life post-settlement (Davis 1993, USACE 2009). Federal flood control and navigation

measures that began in earnest with the authorization of the MR&T Project by the Flood Control Act of

1928 have since regulated the rivers stage and flow and mitigated damage (USACE 2009). These actions

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have channelized the Lower Mississippi River and prevented the abandonment of the current flow path.

Operation of the Old River Control Structure (ORCS) has strictly regulated Mississippi River flows since

1977 to prevent capture by the Atchafalaya River: 30 percent of flows are allocated to the Atchafalaya

and 70 percent to the Mississippi River (USACE 2009).

4.2.2.1.2 Existing Conditions

The MDWD project area is part of the Breton Sound estuary system. The Breton Sound estuary is located

in southeastern Louisiana, and is bounded on the west by the Mississippi River, on the north by Bayou la

Loutre, on the east by the south bank of the Mississippi River-Gulf Outlet (MRGO), and on the south by

Baptiste Collette Bayou and Breton Island. The estuary consists of about 430 square miles of fresh and

brackish coastal wetlands that comprises shallow-water ponds, lakes, bays, and a man-made canal system.

Major natural streamcourses within the estuary are the Oak River (also known as River aux Chenes) and

Bayou Terra aux Boeufs. These functioned as distributary channels of the Mississippi River into the

estuary prior to construction of the MR&T mainstem levee. Other large water bodies are Big Mar, Lake

Leary, Spanish Lake, Grand Lake, and Little Lake.

Flood control measures and flow management have resulted in relatively consistent flows and water

levels in the Lower Mississippi River from 1978 to present in the study area. The flow and water level of

the Lower Mississippi River are directly related and exhibit a seasonal pattern that is presumably linked to

snowmelt runoff and spring rains. High flows and water levels are characteristic of spring months (March

1May 31), while low flows and low water levels are typical from mid-summer to mid-fall (August 16

November 15). Based on USGS data from their Tarberts Landing gage from 1978 to 2008, the average

annual, spring, and summerfall discharge rates are 566,123 + 306,846; 813,333 + 283,377; and 283,925

+ 113,984 cfs (Mean + SD), respectively. Stage and flow are more variable in the spring than summer

fall months.

Other factors influencing the stage and flow of the Lower Mississippi River in the study area are

astronomical and meteorological tides, which have the greatest effect during periods of low stage and

flow (USACE 2000). Astronomical tides have been observed as far upstream as the head of ship

navigation in Baton Rouge, Louisiana. Strong south and southeasterly winds can cause rapid rise and

northwesterly winds rapid decline in the rivers stage (USACE, 2000). Seasonally, tides tend to be highest

in late summer through mid fall (AugustNovember) and lowest in the winter and early spring

(DecemberMarch). Storm surges can also raise tidal levels in the summer and fall months. These levels

can vary greatly depending on the strength and location of the storm.

4.2.2.2 Sedimentation and Erosion

4.2.2.2.1 Historic Conditions

Prior to development of the current mainstem Mississippi River levee system in the mid-twentieth

century, seasonal high river stage events periodically replenished the Breton Sound Basin with sediments

and nutrients that acted to maintain the area as a functioning estuary.

Extensive research and data exist on the historic and existing sediment dynamics of the Lower Mississippi

River. Historically, the Lower Mississippi River transported extremely high sediment loads to the Gulf in

association with deltaic processes. When it was a classical meandering alluvial river that was aggrading

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its channel throughout much of its length, the suspended sediment and bed loads of the Mississippi River

have been estimated to have been as high as 270 x 106 m3

/hr (353 x 106 yd3/hr) and 130 x 106 m3/yr (170

x 106 yd3

/yr), respectively (Kesel et al. 1992). The Lower Mississippi River has experienced significant

changes in sediment transport dynamics over its more recent history, with a general trend of decreased

sediment transport from historic to present times. Kesel (1988) estimated a 43 percent reduction in

sediment loading from historic (prior to 1900) to predam periods (19301952) and a 51 percent decline

from predam to postdam periods (19631982). Increased land development along the Mississippi River

during the 1800s would have contributed to higher sediment loading, and thus this period may provide an

inappropriate reference time frame for long-term trend analysis (USACE 2000). Consequently, there is

uncertainty as to how current sediment loads of the Lower Mississippi River compare to historic levels.

4.2.2.2.2 Existing Conditions

The absence of a supply of freshwater, sediment, and nutrients combined with the ongoing pressures of

wind and wave action, storm surges, and human activities have eroded marsh soils and reduced the ability

of the project area to maintain a balance of emergent wetland and shallow water.

The USGS station at Tarbert Landing, Mississippi, maintains an extended record of sediment data for the

Lower Mississippi River Period of record for daily measurements extends from 1975 to present. Sediment

loading patterns suggest that daily-suspended sediment loads are above average from January through

May and below average from August through November (USGS 1999, 2009). Based on water year 2002

through 2008, the average daily measured suspended sediment load at this location was 334,000 tons/day;

the daily measured suspended sediment load varies from 39,000 to 119,000 tons/day (USGS 2009). The

sand to silt ratio of suspended sediment is typically 20% sand to 80% silt (USGS 1999). Mashriqui and

Kemp (1996) reported the mean sediment load of the Mississippi River at Tarbert Landing to be 226

mg/L, of which about 26% was sand, with silts and clays each contributing between 30% and 40%.

In 1995 the USACE derived the long-term relative subsidence rates from radiocarbon dating of buried

peat deposits for all of southeast Louisiana. It was determined that the MDWD project area is subsiding at

a rate of approximately 0.50 foot per century. Just beyond the project boundary toward Head of Passes,

the rate increases to 1.04.0 feet per century.

4.2.2.3 Water Use and Supply

4.2.2.3.1 Historic Conditions

Fresh ground and surface water is abundant in southern Louisiana. Prior to the 1900s, water used for most

purposes was from surface sources. Many households collected rainwater for domestic uses and farmers

generally relied on rainfall and irrigation ditches to provide water to their crops. During the late 1800s,

water wells began to come into common usage and quickly proliferated in areas where fresh groundwater

was available. The use of groundwater allowed farmers to plant crops in areas where sources of fresh

surface water were unreliable or unavailable. In coastal areas of southeastern Louisiana, groundwater

supplies are generally limited and surface water is primarily used. Large amounts of fresh groundwater

are generally available and groundwater is used for most purposes.

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4.2.2.3.2 Existing Conditions

During 2000, about 3,000 million gallons per day (Mgal/d) (11,370 million liters per day [Ml/d]) of

freshwater were withdrawn for various uses in the LCA Study area. Of this water, about 97 percent was

from surface sources and about 3 percent was from groundwater sources. Most of this use was in

southeastern Louisiana in parishes that border or straddle the Mississippi River.

The Mississippi River and some of its distributaries were the largest sources of surface water, contributing

96 percent (2,800 Mgal/d [10,612 Ml/d]) of the total surface withdrawals. Withdrawals for power

generation and industry were primarily from the Mississippi River and used for once-through cooling and

much of the water was returned to the source. Industrial withdrawals were primarily for petroleum

refining and chemical manufacturing.

4.2.2.4 Groundwater

4.2.2.4.1 Historic Conditions

Southern Louisiana generally has very abundant fresh groundwater supplies. However, aquifers along the

coast typically contain saltwater that extends inland as a wedge along the base of the aquifer. Coastward,

the saltwater wedge typically thickens and the overlying freshwater thins until the entire thickness of the

aquifer contains saltwater. Salty groundwater is often defined as water containing a chloride concentration

greater than 250 mg/L or a dissolved solids concentration greater than 1,000 mg/L. Saltwater can move

into freshwater parts of the aquifer by lowering freshwater levels through pumping. Such movement of

saltwater or the saltwater wedge is known as saltwater encroachment. Saltwater can move laterally or

vertically in an aquifer.

4.2.2.4.2 Existing Conditions

The water table is at or near the surface throughout most of the coastal zone. The silt- and sand-rich

depositional environments such as point bar, intradelta, natural levee, beach, and near shore gulf are

generally connected hydraulically to the adjacent water body (i.e., river, lake, distributary channel) and

the elevation of the water table in these deposits reflects the level/stage of the adjacent water body. This is

especially true in deposits adjacent to the Mississippi and Atchafalaya Rivers.

4.2.3 Water Quality and Salinity

4.2.3.1 Historic Conditions

Historic water quality issues for the project area are similar to existing issues addressed below. Mean

salinities in the Breton Sound Basin range from fresh (02 parts per thousand [ppt]) in the upper basin to

saline (>10 ppt in the middle and lower portions of the basin.

4.2.3.2 Existing Conditions

Historic and current water quality issues for the waters within the White Ditch project include the

transport of nutrients, pesticides, synthetic organic compounds, trace elements, suspended sediment, and

bacteria. The database for sampling stations on the Mississippi River near the diversion site is extensive,

with comprehensive water quality datasets beginning in the mid-1970s. Historically, sites have been

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operated in cooperation with the USACE and the Louisiana Department of Environmental Quality

(LDEQ). The database for the Mississippi River is extensive enough that several general conclusions can

be made concerning its suitability for coastal restoration efforts: Trace elements, including heavy metals,

are generally not considered a water quality issue in the Mississippi River.

1. Nitrate concentrations average around 1.41.6 mg/L in the lower Mississippi River. This is the

result of natural and human inputs, particularly agricultural fertilizers in the mid-continent.

Nitrate at these concentrations can cause excessive algal growth and eutrophication in coastal

water bodies and contribute to the hypoxia problem in the Gulf of Mexico.

2. Fecal coliform bacteria in the lower Mississippi River have declined dramatically with more

effective sewage treatment at Baton Rouge and New Orleans since the mid to late 1980s.

3. The primary pesticides detected in the Mississippi River are the herbicides atrazine, metolachlor,

and acetochlor.

4. Per LDEQs database2

, organic compounds are typically not detected in the Mississippi River.

5. For conventional parameters in LDEQs database2

, there is essentially no difference in water

quality spatially along the length of the Mississippi River between Pointe à la Hache and the

Louisiana state line.

The most common individual designated uses within proximity to the White Ditch Project Area include

primary contact recreation, secondary contact recreation, fish and wildlife propagation, shellfish

propagation, and drinking water supply. Primary contact recreation is defined by LDEQ as any

recreational activity that involves or requires prolonged body contact with the water, such as swimming,

water skiing, tubing, snorkeling, and skin-diving. Secondary contact recreation is defined as any

recreational activity that may involve incidental or accidental body contact with the water and during

which the probability of ingesting appreciable quantities of water is minimal, such as fishing, wading, and

recreational boating. Fish and wildlife propagation is defined as the use of water for preservation and

reproduction of aquatic biota such as indigenous species of fish and invertebrates, as well as reptiles,

amphibians, and other wildlife associated with the aquatic environment. This also includes the

maintenance of water quality at a level that prevents contamination of aquatic biota consumed by humans.

Shellfish propagation is the use of water to sufficiently maintain biological systems that support

economically important species of oysters, clams, mussels, or other mollusks so that their productivity is

preserved and the health of human consumers of these species is protected.

The Louisiana Department of Health and Hospitals (LDHH) coordinates with LDEQ, the LDWF, and the

Louisiana Department of Agriculture and Forestry (LDAF) to issue water body advisories aimed at

protecting the publics health. These include fish and shellfish consumption advisories and swimming

advisories. Fish and shellfish consumption advisories employ a risk-based method to advise the public to

limit or avoid the intake of certain species of fish and shellfish that have unsafe contaminant levels in

their tissues. Swimming advisories may be issued for a water body due to fecal coliform or other types of

contamination. This information comes from the LDEQs 2008 305(b)/303(d) Integrated Report. The

water bodies within the White Ditch project area are currently meeting their designated uses. The

Mississippi River in proximity of the project was fully supporting the designated uses of secondary

2 LDEQ performs collection and analysis for 29 conventional parameters and fecal coliform through the Surface Water Monitoring Program with a

priority pollutant scan quarterly at the Mississippi River site near the White Ditch Project Area.

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contact recreation and drinking water supply; however, was assessed as not supporting primary contact

recreation or fish and wildlife propagation. The suspected causes of impairment include nitrogen,

phosphorus, and total fecal coliform from suspected sources of municipal point source discharges and

upstream sources. The Mississippi River Basin Coastal Bays and gulf waters were assessed as not

supporting fish and wildlife propagation due to mercury from atmospheric deposition. The Mississippi

River within the project area was not assessed for the other designated uses due to insufficient data.

For the White Ditch WVA assessment, baseline salinity values for the project area were determined using

20082009 data from Coastal Reference Monitoring stations located within or near the project area.

Baseline values determined for intermediate marsh were representative of the mean values during the

growing season (MarchNovember), which ranged from 3.7 to 5.7; the mean baseline was calculated as

4.0. Baseline salinity for brackish and saline marsh was representative of the mean annual salinity

recorded in 20082009. Baseline values of 6.6 for the brackish marsh zone was determined using station

data that ranged from 5.0 to 9.9 ppt. A baseline value of 13.0 was estimated for the saline zone by

extrapolating data from a single monitoring station in an isolated area of marsh to the larger open-water

areas at the lower end of the estuary, where salinities were believed to be higher. Figure 4.1 shows the

existing salinity gradients that could be found in a typical July.

4.2.4 Air Quality

This resource is institutionally significant because of the Clean Air Act of 1963 (CAA), as amended, and

the Louisiana Environmental Quality Act of 1983 (LEQA), as amended. Air quality is technically

significant because of the status of regional ambient air quality in relation to the National Ambient Air

Quality Standards (NAAQS). It is publicly significant because of the desire for clean air expressed by

virtually all citizens.

4.2.4.1 Historic Conditions

Historic air quality conditions in the project area are similar to those described in Section 4.2.5.2 below.

4.2.4.2 Existing Conditions

The EPA Green Book Nonattainment Areas for Criteria Pollutants (Green Book) maintains a list of all

areas within the United States that are currently designated nonattainment areas with respect to one or

more criteria air pollutants. Nonattainment areas are discussed by county or metropolitan statistical area

(MSA). MSAs are geographic locations, characterized by a large population nucleus, that are comprised

of adjacent communities with a high degree of social and economic integration. MSAs are generally

composed of multiple counties. Review of the Green Book indicates that Plaquemines Parish is in

attainment for all Federal NAAQS pollutants (http://www.epa.gov/oar/oaqps/greenbk/multipol.html)

(http://www.deq.louisiana.gov/portal/Default.aspx?tabid=112)

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4-9

Figure 4.1: LCA White Ditch Existing Condition Salinities – July 2009

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4.2.5 Noise

Noise is institutionally significant because of the Noise Control Act of 1972 that declares the policy of the

United States to promote an environment for all Americans free from noise that jeopardizes their health or

welfare; and the Occupational Safety and Health Standards (29 CFR, part 1910) regarding protection

against the effects of noise exposure. Noise is technically significant because noise can negatively affect

the physiological or psychological well-being of an individual (Kryter, 1994) ranging from annoyance to

adverse physiological responses, including permanent or temporary loss of hearing, and other types of

disturbance to humans and animals, including disruption of colonial nesting birds. Noise is publicly

significant because of the publics concern for the potential annoyance and adverse effects of noise on

wildlife and humans.

4.2.5.1 Historic Conditions

Noise is typically associated with human activities and habitations, such as operation of commercial and

recreational boats, water vessels, air boats, and other recreational vehicles; operation of machinery and

motors; and human residential-related noise (air conditioner, lawn mower, etc.). However, the project area

is a remote marsh only sparsely populated on its perimeter. The noise from distant urban areas

surrounding the project area has little if any impacts on the area.

4.2.5.2 Existing Conditions

The MDWD study area contains a wide array of land use activities that vary throughout the entire project

corridor. The dominant land use category located within the project area, as described under the Federal

Highway Administrations (FHWA) Noise Abatement Criteria (NAC), is Activity Category C, which

includes developed and undeveloped lands. The project area also contains a moderate amount of elements

described in Activity Category B, which consists of playgrounds; active sports areas; parks, residences;

motels; schools; churches; libraries; and hospitals. The dBA ranges for Activity Categories B and C were

calculated by the FHWA using two different noise descriptors (Leq and L10). According to FHWA NAC,

the estimated dBA ranges that are typically present for Activity Categories B and C are 67 dBA to 70

dBA and 72 dBA to 75 dBA, respectively (FHWA-2).

4.2.6 Vegetation Resources

Coastal vegetation resources attain institutional significance through the following Federal statutes: the

Coastal Barrier Resources Act of 1982; the Coastal Zone Management Act of 1972; the Emergency

Wetlands Resources Act of 1986; the Estuary Protection Act of 1968; the Fish and Wildlife Conservation

Act of 1980; the Fish and Wildlife Coordination Act of 1958, as amended; the Migratory Bird

Conservation Act; the Migratory Bird Treaty Act; the Endangered Species Act of 1973 (ESA); the

Magnuson Fishery Conservation and Management Act 1990; the NEPA of 1969; the North American

Wetlands Conservation Act; the Water Resources Development Acts of 1976, 1986, 1990, and 1992; and

Executive Order 13186Responsibility of Federal Agencies to Protect Migratory Birds. Coastal

vegetation resources are technically significant because they are a critical element of the coastal habitats.

In addition, coastal vegetation resources serve as the basis of productivity, contribute to ecosystem

diversity, provide various habitat types for fish and wildlife, and are an indicator of the health of coastal

habitats. Coastal vegetation resources are publicly significant because of the high priority that the public

places on their aesthetic, recreational, and commercial value.

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Vegetation in coastal Louisiana is inextricably linked to coastal hydrology. Two of the major mechanisms

of vegetation change in the region, which includes the project area, are flooding and salinity. Hydrologic

alterations such as levee building, channel construction, and drainage activities have substantially

contributed to the vegetation changes in the project area over the past 50 years. A more-detailed

discussion of the relationship between regional hydrology and vegetation regimes in the region was

provided in the Final Programmatic EIS for the LCA Ecosystem Restoration Study (LCA 2004).

4.2.6.1 Riparian Vegetation

4.2.6.1.1 Historic Conditions

Historically, the Mississippi River had a riparian zone that transitioned from bottomland hardwood (BLH)

forested ridges, transitioning through a mixed woodland community, to a swamp habitat between the

ridges and eventually into marshland. The study area formed by a crevasse of the Mississippi River,

forming River aux Chenes (Oak River) which transported water to the marshes during seasonal high

water events, mainly during the late winter and early spring. The Mississippi River protection levee was

constructed and reduced the spatial extent of the riparian zone while eliminating the natural flow of river

water into the basin. This has eliminated the introduction of freshwater from the river and disrupted

natural sediment deposition patterns. In addition, numerous channels have been dredged through natural

ridges which increased drainage and tidal exchange. Composite coastal habitat mapping conducted by the

USGSs National Wetlands Research Center in 2000 indicated that 839 acres of wetland forest, 460 acres

of wetland shrub-scrub, and 0 acre of swamp were present in the project area at that time. Comparable

survey data for the post-Katrina period was not available; however, local reports and visual observation

suggest that storm damage has further reduced riparian forested acreage.

4.2.6.1.2 Existing Conditions

This resource is institutionally important because of Section 906 of the Water Resources Development

Act of 1986 and the Fish and Wildlife Coordination Act of 1958, as amended. BLH forest is technically

important because: it provides necessary habitat for a variety of species of plants, fish, and wildlife; it

often provides a variety of wetland functions and values; it is an important source of lumber and other

commercial forest products; and it provides various consumptive and non-consumptive recreational

opportunities. BLH forest is publicly important because of the high priority that the public places on its

aesthetic, recreational, and commercial value. BLH provides necessary habitat for a variety of species of

plants, fish, and wildlife, and provides a variety of wetland functions and values. Seasonal flooding

occurs over portions of the forests.

BLH provides necessary habitat for a variety of species of plants, fish, and wildlife, and provides a variety

of wetland functions and values. Existing BLH in the study area is limited to small remnants of forested

ridges adjacent to the Mississippi River, Oak River, and numerous oil and gas exploration canals. The

BLH species along the Mississippi River batture include Drummond red maple (Acer drummundii),

sugarberry (Celtis laevigata), Chinese tallow (Sapium sebiferum) sweet gum (Liquidambar styraciflua),

water oak (Quercus nigra), and black willow (Salix nigra). Shrubs and vines include buttonbush

(Cephalanthus occidentalis), dew berry (Rubus sp.), and green briar (Smilax sp.)

The species found along Oak River include live oak trees (Quercus virginiana), black willow, sugarberry,

and scattered baldcypress (Taxodium distichum) on the northern end. A lot of the oak trees have died

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leaving remnant snag trees on the subsiding ridge. Scrub/shrub species include palmetto (Sabal minor),

elderberry (Sambucus canadensis), eastern baccharis (Baccharis haemifolia) locally called mung bushes,

and wax myrtle (Myrica cerifera), and marshhay cordgrass (Spartina patens). The Bayou Garelle ridges

have subsided to mostly a scrub/shrub habitat with the same species as above.

Canal dredging for oil and gas exploration has created numerous man-made ridges. The species on the

banklines include sugarberry, Chinese tallow, and black willow. Shrubs and vines include palmetto,

elderberry, mung bushes, and dewberry. Strong southeasterly winds associated with storms causes

seasonal flooding over portions of the banklines and ridges.

4.2.6.2 Wetland Vegetation

4.2.6.2.1 Historic Conditions

Historically, there was a basin with wide and gradual salinity transition zones that supported a healthy,

natural, and sustainable estuary and fisheries. The 1956 habitat map was used for target land and

vegetation distribution. The 1956 USGS analysis divided marsh between fresh (fresh and intermediate)

and non-fresh (brackish and saline). According to the 1956 USGS Habitat Analysis, there was 10,716

acres of fresh marsh and 40,130 acres of non-fresh marsh (Figure 4.2).

4.2.6.2.2 Existing Conditions

The following Federal laws recognize the national significance of marshes as a natural resource: the

Clean Water Act of 1977, as amended; Executive Order 11990 of 1977, Protection of Wetlands; Coastal

Zone Management Act of 1972, as amended; and the Estuary Protection Act of 1968. Marshes are

ecologically important because they: 1) provide necessary habitat for various species of plants, fish, and

wildlife; they serve as ground water recharge areas; 2) provide storage areas for storm and flood waters;

3) serve as natural water filtration areas; 4) provide protection from wave action, erosion, and storm

damage; and 5) provide various consumptive and non-consumptive recreational opportunities. Marshes

are significant to the public because of the high value the public places on the ecological functions and

human benefits that marshes provide. The basic marsh habitats within the MDWD study area are

intermediate, brackish, and saline marsh with an addition of fresh marsh in the extended influence area

(Figure 4.3).

There are approximately 2,000 acres of fresh marsh (03 ppt salinity) in the extended influence area.

There are two basic types of fresh marsh in the area, flotant emergent and attached emergent. The flotant

marsh is actually not attached to the underlying soil although the marsh plants form a dense mat that

appears to be solid. The flotant marshes contain primarily maiden cane, coastal arrowhead, and Baldwin's

spikerush. The attached emergent fresh marsh is attached to the underlying soil and also contains

predominantly maiden cane and coastal arrowhead, along with spikerush, alligatorweed, common reed,

coastal water-hyssop, penny-wort, and saltmeadow cordgrass.

Intermediate marsh (28 ppt salinity) habitat lies between fresh marsh and brackish marsh and the species

of vegetation are not much different from fresh marsh, however, the dominance of the species is different.

Marshhay cordgrass (Spartina patens) is the dominant species, with coastal arrowhead (Sagittaria

falcata), roseau cane (Phragmites australis), coastal water-hyssop (Bacopa monnieri), seashore paspalum

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Figure 4.2: Historic Habitat Analysis of the White Ditch Project Area

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Figure 4.3: Marsh Types in the White Ditch Project Area

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(Paspalum vaginatum), spikerush (Eleocharis parvula), eastern baccharis (Baccharis halimifolia)

smartweed (Polygonum sp.), deerpea (Vigna repens), marsh morning glory (Ipomoea sagittata), and leafy

three-square (Scirpus robustus) also common. There are approximately 32,000 and 90,000 acres of

intermediate marsh in the MDWD study area and the extended influence areas, respectively.

Brackish marsh (418 ppt salinity) habitat lies between intermediate marsh and saline marsh. The

dominant brackish marsh plant is marshhay cordgrass, comprising about one-half of the plants (Gosselink

1984: Conner and Day 1987). Other important species include seashore saltgrass (Distichlis spicata),

camphorweed (Pluchea camphorata), and coastal water-hyssop (Conner and Day 1987). There are

approximately 17,500 and 11,500 acres of brackish marsh in the MDWD study area and the extended

influence areas, respectively.

The saline marsh (829 ppt salinity) community typically has the lowest plant species diversity of any

marsh type. The dominant species in the salt marshes of the project area is oystergrass (Spartina

alterniflora). There are approximately 7,500 and 5,000 acres of saline marsh in the MDWD study area

and the extended influence areas, respectively.

4.2.6.3 Upland Vegetation

4.2.6.3.1 Historic Conditions

Historically, upland vegetation in the project study area, if present, would have been limited to the highest

natural levee areas.

4.2.6.3.2 Existing Conditions

Upland vegetation in the project study area is limited to the highest elevation developed areas such as the

Federal levee and landscaping around home sites.

4.2.6.4 Submerged Aquatic Vegetation (SAV)

4.2.6.4.1 Historic Conditions

Fresh and intermediate marshes often support diverse communities of submerged aquatic plants that

provide important food and cover to a wide variety of fish and wildlife species. Brackish marshes also

have the potential to support aquatic plants that serve as important sources of food and cover for several

species of fish and wildlife. Although brackish marshes generally do not support the amounts and kinds of

subaquatic plants that occur in fresh/intermediate marshes, certain species, such as widgeon-grass (Ruppia

maritima), and coontail (Ceratophyllum demersum) and Eurasian watermilfoil (Myriophyllum spicatum)

in lower salinity brackish marshes, can occur abundantly under certain conditions. Those species,

particularly widgeon-grass, provide important food and cover for many species of fish and wildlife. The

saline marshes typically do not contain an abundance of aquatic vegetation as often found in

fresh/intermediate and brackish marshes.

4.2.6.4.2 Existing Conditions

Little to no up-to-date field information is available on the current composition and extent of submerged

aquatic vegetation (SAV) in the White Ditch project area. For purposes of the WVA analysis, existing

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SAV in the intermediate marsh zone was assumed to be 25% of the total area. That value is the mean of

the SAV cover values from the Monsecour Siphon Project (2009), Bertrandville Siphon Project (2008),

and White Ditch Siphon Project (2004) WVAs prepared by CWPPRA. Those WVAs encompass the

majority of the intermediate marsh zone in the project area. No SAV cover data has been collected in the

brackish marsh zone and there are no previous project WVAs that have been conducted in this portion of

the project area. It is assumed that SAV cover would be somewhat less in this area (15% assumed) as

compared to the intermediate area. Similar to the brackish marsh zone, no SAV cover data has been

collected in the saline marsh zone and there are no previous project WVAs that have been conducted in

this portion of the project area. SAV cover is typically very low or non-existent within saline marshes and

this area contains very large open water areas, which typically contain no SAV. However, it is assumed

that SAV cover may exist in some of the more isolated bodies of water (2% coverage assumed).

4.2.6.5 Invasive Species – Vegetation

4.2.6.5.1 Historic Conditions

Invasive plant species often increase and spread rapidly because the new habitat into which they are

introduced is often free of insects and diseases that are natural controls in their native habitats. In coastal

Louisiana, Chinese tallow, water hyacinth, alligator weed and hydrilla are well-known invasive plants.

More recently, common salvinia, giant salvinia, and variable-leaf milfoil also have become invasive,

displacing native aquatic species and degrading water quality and habitat quality (LACPR 2008).

4.2.6.5.2 Existing Conditions

Of the invasive plant species occurring or potentially occurring within the White Ditch project area, water

hyacinth is currently the species most identified as problematic by local property owners. No information

on the existing occurrence or coverage within the project area is available; however, the reported

proliferation of this species in canals and water bodies within the Caernarvon subbasin is commonly

attributed to the fresher water conditions resulting from operation of that existing diversion.

4.2.7 Wildlife and Habitat

This resource is institutionally significant because of the Fish and Wildlife Conservation Act of 1980, the

Fish and Wildlife Coordination Act of 1958, as amended, the Migratory Bird Conservation Act, the

Migratory Bird Treaty Act, the ESA, and Executive Order 13186, Migratory Bird Habitat Protection.

Wildlife resources are technically significant because they are a critical element of the various coastal

habitats, they are an indicator of the health of coastal habitats, and many wildlife species are important

commercial resources. Wildlife resources are publicly significant because of the high priority the public

places on their aesthetic, recreational, and commercial value.

4.2.7.1 Historic Conditions

The wetlands and associated habitats of coastal Louisiana are of national importance and provide essential

habitat to diverse and abundant wildlife resources, including a wide range of resident and migratory birds

as well as critical habitat for the wintering populations of the piping plover. Coastal Louisiana has the

Nations largest concentrations of colonial nesting wading birds and seabirds. Coastal marshes in the state

provide habitat to 14 species of ducks and geese (those species for which data is available). Marshes,

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swamps, and associated habitats support millions of neotropical and other migratory avian species such as

rails, gallinules, shorebirds, wading birds, and numerous songbirds, providing essential stopover habitat

on their annual migration route. Coastal Louisiana has been a leading fur-producing area in North

America, and coastal marshes and swamps also support game and small mammals. Louisiana marshes

provide abundant habitat for many reptiles, most notably the American alligator, and the swamps and

fresh/intermediate marshes also support many amphibians, especially various frog species.

4.2.7.2 Existing Conditions

Existing wetlands in the study area provide important and essential wildlife habitats, used for shelter,

nesting, feeding, roosting, cover, nursery, and other life requirements. The coastal marshes of Louisiana

provide winter habitat for more than 50 percent of the duck population of the Mississippi Flyway. Large

populations of migratory waterfowl, including gadwalls, blue-winged teal, green-winged teal, wigeons,

lesser scaup, shovelers, pintails, and mallards, are present during winter in the MDWD study area.

Mottled ducks are present year-round. These waterfowl are highly sought by sportsmen. In addition,

coots, gallinules, rails, mourning doves, and snipe are important game species. Dabbling duck and diving

duck numbers are increasing in the vicinity of existing freshwater diversions, such as in the Caernarvon

area upriver of the study area.

Non-game avian species present in the study area include wading birds, shore birds, and sea birds include

egrets, ibis, herons, sandpipers, willets, black-necked stilts, gulls, terns, skimmers, grebes, loons,

cormorants, and white and brown pelicans. Various raptors such as barred owls, red-shouldered hawks,

northern harriers (marsh hawks), American kestrel, and red-tailed hawks are present. Passerine birds

present include sparrows, vireos, warblers, mockingbirds, grackles, red-winged blackbirds, wrens, blue

jays, cardinals, and crows. Many of these birds are present primarily during periods of spring and fall

migrations.

The study area also contains a great variety of mammals, reptiles, and amphibians. Abundant furbearers,

including nutria, muskrat, mink, otter, and raccoon, formerly supported a trapping industry in the nearby

Terrebonne Basin. Other species inhabiting the area where suitable habitat is present include white-tailed

deer, skunks, rabbits, squirrels, armadillos, and a variety of smaller mammals. The area provides habitat

for salamanders, toads, frogs, turtles, and several species of poisonous and nonpoisonous snakes. The

American alligator is abundant in fresh to intermediate marsh and is caught commercially for its hides and

meat throughout the area.

Numerous terrestrial invertebrates are found throughout the study area. The most notable are insects,

which often serve as vectors, transmitting disease organisms to higher animals, including man.

Mosquitoes are the most important of the vectors in the area, although other groups, such as deer flies,

horseflies, and biting midges are also considered vectors. The area provides suitable breeding habitat for

such species as Aedes sollicitans (salt-marsh mosquito), Culex salinarius, and other species of

mosquitoes. Mosquitoes carry the West Nile virus, which has recently caused some illness and even death

of both animals and humans in Louisiana.

Native muskrats, once trapped for their valuable fur throughout coastal Louisiana, have been crowded out

by invasive South American nutria. Damage by nutria herbivory on marsh vegetation is an ongoing

concern in the study area. The first CWPPRA-funded coast-wide survey, conducted in 1998, showed

herbivory damage areas totaling approximately 90,000 acres. By 1999 this coast-wide damage had

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increased to nearly 105,000 acres. This rapid and dramatic increase in damaged acres prompted LDWF to

pursue funding for the Coastwide Nutria Control Program (CNCP) in January 2002.

The project is funded by the CWPPRA through the NRCS and the CPRA with the LDWF as the lead

implementing agency. The project goal is to significantly reduce damage to coastal wetlands attributable

to nutria herbivory by removing 400,000 nutria annually. This project goal is consistent with the Coast

2050 common strategy of controlling herbivory damage to wetlands. The method chosen for the program

is an incentive payment to registered trappers/hunters for each nutria tail delivered to established

collection centers. Initially, registered participants were given $4.00 per nutria tail. To encourage

participation, the payment was increased to $5.00 per tail in the 20062007 season. During the 2007

2008 season, a total of 73,797 tails were harvested in Plaquemines Parish (LDWF annual report, 2008).

4.2.8 Aquatic Resources

4.2.8.1 Historic Conditions

A general description of aquatic resources in the overall LCA study area (plankton and benthos) was

provided in Sections 3.9 and 3.10 of the LCA FPEIS and is incorporated here by reference. No

information is available on historic conditions of aquatic resources in the specific White Ditch project

area.

4.2.8.2 Existing Conditions

Aquatic habitat in the project vicinity is provided by the Mississippi River, oxbow lakes, borrow areas

and estuarine wetlands. The main stem of the Mississippi River with an average depth of greater than 5

feet is inherently low in primary productivity on a relative basis because of high turbidity. Poor benthic

productivity is characteristic of the shifting substrates and high current velocities in the area. The deep

main river channel is the habitat of large predaceous fishes, some plankton feeders and a number of

omnivorous species.

Plankton communities serve an important role in the coastal waters of Louisiana. Phytoplankton are the

primary producers of the water column, and form the base of the estuarine food web. Zooplankton

provide the trophic link between the phytoplankton and the intermediate level consumers such as aquatic

invertebrates, larval fish, and smaller forage fish species (Day et al., 1989). Microzooplankton appear to

be important consumers of bacterioplankton, which are typically enumerated primarily by culture and

microscopic techniques. Culture techniques are selective and invariably underestimate bacterial densities

(Day et al., 1989). The Cooperative Gulf of Mexico Estuarine Inventory and Study, Louisiana, prepared

by the Louisiana Wildlife and Fisheries Commission in 1971 provides a summary of plankton across the

coastal estuaries of Louisiana in the late 1960s (Perret et al., 1971). The dominant member of the

zooplankton community throughout that study was the copepod Acartia tonsa. The greatest

concentrations of zooplankton were encountered in Breton Sound. The lowest concentrations were

encountered in Chandeleur Sound and Lake Borgne east of the Mississippi River, Lakes Barre and

Raccourci, and Terrebonne and Timbalier Bays. Species diversity was greatest in the Breton Sound and

Mississippi River, East Bay, Garden Island Bay, and West Bay areas.

Historically, salinity appears to be the chief controlling factor in the number of species present, while

temperature, competition, and predation control the number of individuals present (Day et al., 1989). In

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addition, the abundance of certain zooplankton may be indicative of good fishing areas. While some

zooplankton are euryhaline, others have distinct salinity preferences (Day et al., 1989). Therefore,

introduction of river water into estuarine systems may have dramatic short-term impacts on plankton

populations in adjacent coastal waters (Hawes and Perry, 1978).

4.2.9 Fisheries

Fishery resources are institutionally significant because of the Fish and Wildlife Coordination Act of

1958, as amended; the ESA; the Magnuson-Stevens Fishery Conservation and Management Act of 1976

(Magnuson-Stevens Act), as amended; the Magnuson-Stevens Act Reauthorization of 2006; the Coastal

Zone Management Act; and the Estuary Protection Act. Fishery resources are technically significant

because: they are a critical element of many valuable freshwater and marine habitats; they are indicators

of the health of various freshwater and marine habitats; and many species are commercially important.

Fishery resources are publicly significant because of the high priority placed on their aesthetic,

recreational, and commercial value.

4.2.9.1 Historic Conditions

Prior to the twentieth century, the tremendous estuarine productivity of coastal Louisiana was sustained

by the rivers distributaries and periodic floodwaters, which deposited millions of tons of sediments and

nutrients on adjacent coastal marshes. The beneficial impact of this alluvial renourishment to fisheries

was recognized by early native inhabitants and is documented in formal reports dating back to 1906.

Levee construction and subsequent fortification through the twentieth century has resulted in major

disruption to the rivers natural deltaic cycle. Processes such as subsidence, saltwater intrusion, and wave

erosion were no longer offset by accretion, resulting in extensive loss of coastal wetlands (Caffey and

Schexnayder 2002). Despite this, Louisiana commercial fishery landings have increased significantly

since the early 1900s and recreational harvests have been relatively stable for the past 10 years. At the

same time, coastal habitats that support Louisiana fisheries have been increasingly impacted over the last

50 years by subsidence, sea level change, channelization of bayous, dredging of canals, and intensive

management of marshes for wildlife and waterfowl.

4.2.9.2 Existing Conditions

The MDWD project study area is located in LCA Subprovince 1 in the Breton Sound hydrologic basin in

Plaquemines Parish, Louisiana. The boundary of the project encompasses over 98,000 acres of

intermediate to brackish intertidal wetland habitats. The study area boundary follows distinct landscape

features beginning in the north with the confluence of the non-Federal back levee and the Forty-Arpent

canal, extending along the non-Federal back levee, the Mississippi River levee, the Federal back levee

and along the left descending natural bank of the Mississippi River to the west; past American Bay,

California Bay, and through Breton Sound, near Bay Gardene to the south; into and along River aux

Chenes to the east, and back to the point of beginning.

The majority of the MDWD study area is estuarine habitat. Estuarine fishery species may be resident

(inhabiting the estuary throughout their life cycle), such as killifishes, or transient (utilizing the estuary

for some portion of their life cycle) such as gulf menhaden, blue crab, or shrimp. Marine species are

found in offshore waters throughout the gulf coast and generally do not depend on estuaries to complete

any part of their life cycle. These species are in some ways dependent on the health and productivity of

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coastal estuaries, in that their prey often is made up of estuarine dependent species. In addition, some

marine species frequently inhabit the lower reaches of estuaries, where productivity is high. Noted finfish

species found in the Breton Sound Basin include speckled trout, red drum, black drum, sheepshead, sand

seatrout, Atlantic croaker, spot, gulf menhaden, and spotted seatrout.

Three species of crustaceans  brown shrimp, white shrimp, and blue crab  are of major commercial

and recreational importance in the coastal waters of Louisiana. Each of these species follows a circular

migration, which encompasses a broad range of estuarine salinities. Because commercial harvesting

targets the late juvenile and adult stages, productivity is often incorrectly equated with higher salinities.

Though higher salinities tend to favor harvestability, they are not directly linked to absolute productivity

(Caffey and Schexnayder 2002).

The American oyster is indigenous to coastal Louisiana and provides a substantial ecological and

commercial resource. This organism is notable in that it is sessile and cannot migrate like many other

estuarine species. Salinity plays a key role in oyster sustainability (Eastern Oyster Biological Review

Team [EOBRT], 2007). Adult oyster can tolerate salinities from 0 to 42 ppt, but the optimal range is 14 to

28 ppt (EOBRT, 2007). Oyster spat can settle out at salinities as low as 3 ppt, but will have difficulty

surviving. Fresher waters fail to support biological function, and more saline waters promote disease and

predation. The upper two-thirds of the study area and extended influence area are either not conducive for

spat settlement or suboptimal for natural oyster reef formation (Figure 4.1). Adult oysters are more prone

to impacts from changes in water quality than commercially harvested fishes and crustaceans because

they are sessile, and cannot relocate in response to changes in water quality parameters. Production of

oysters in Louisiana has been relatively stable for the last 50 years, with harvest from public beds

replacing the decreasing harvest from private leases. See Section 4.2.15.15.2 for a discussion of oyster

leases. The Louisiana oyster industry has been experiencing many stressors over the past several decades

that threaten the long-term sustainability of both the industry and the resource (Coleman, 2003).

Increasing coastal land loss is reducing the amount of marsh that provides shelter to reefs, and saltwater

intrusion is exacerbating disease and predation. In addition, the industry is faced with changing

environmental conditions, fluctuating market demands, public perception issues, and increased

competition.

4.2.10 Essential Fish Habitat (EFH)

This resource has statutory significance because of the Magnuson-Stevens Act (P.L. 104-297), which

intended to promote the protection, conservation, and enhancement of EFH. The EFH designation is an

important component of building and maintaining sustainable marine fisheries through habitat protection.

The Magnuson-Stevens Act defines EFH for federally managed fish species as those waters and

substrate necessary to fish for spawning, breeding, feeding or growth to maturity.

4.2.10.1 Historic Conditions

Emergent wetlands and shallow open water areas in the MDWD project area and adjacent areas of the

Breton Sound Basin provide transitional habitat between estuarine and marine environments used by

migratory and resident fish and other aquatic organisms for nursery, foraging, breeding and spawning,

and other life requirements. The marshes and shallow bays function as nursery grounds for stocks of

shrimp, oysters, crabs, and a variety of finfish (Louisiana Coastal Wetlands Conservation and Restoration

Task Force, 1993).

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4.2.10.2 Existing Conditions

By letter dated February 10, 2009, the NMFS provided information on EFH in the study area in support

of the public scoping effort for the project feasibility study and EIS. Aquatic and tidally influenced

wetland habitats in portions of the MDWD study area are designated as EFH for various federally

managed species, including white shrimp, brown shrimp, red drum, lane snapper, dog snapper, and Gulf

stone crab. These species are managed by the Gulf of Mexico Fishery Management Council (GMFMC).

Table 4.1 lists life stages and subcategories of EFH for these species that would potentially be benefited

or impacted by this project. Primary categories of EFH in the study area include estuarine emergent

wetlands; SAV; mud, sand, and shell substrates; and estuarine water column. Detailed information on

federally managed fisheries and their EFH is provided in the 2005 generic amendment of the Fisheries

Management Plans (FMPs) for the Gulf of Mexico prepared by the GMFMC. The generic amendment

was prepared as required by the Magnuson-Stevens Act (P.L. 104-297).

In addition to being designated as EFH for the species listed in Table 4.1, water bodies and wetlands in

the study area provide nursery and foraging habitats supportive of a variety of economically important

marine fishery species, such as striped mullet, Atlantic croaker, gulf menhaden, spotted seatrout, sand

seatrout, southern flounder, black drum, and blue crab. Some of these species also serve as prey for other

fish species managed under the Magnuson-Stevens Act by the GMFMC (e.g., mackerels, snappers, and

groupers) and highly migratory species managed by NMFS (e.g., billfishes and sharks). (NOAA 2009)

Table 4.1: Essential Fish Habitat (EFH) for Various Life Stages for Shrimp, Red Drum, Reef

Fish, and Stone Crab (NMFS Scoping Correspondence, 2009)

Species Life Stage System EFH

Brown Shrimp Larvae Marine <82 m; planktonic, sand/shell/soft bottom,

SAV, emergent marsh, oyster reef

Juvenile Estuarine <18 m; planktonic, sand/shell/soft bottom,

SAV, emergent marsh, oyster reef

White Shrimp Juvenile Estuarine <30 m; SAV, soft bottom, emergent marsh

Gulf Stone Crab Eggs Estuarine/Marine <18 m; sand/shell/soft bottom

Larvae/postlarvae Estuarine/Marine <18 m; planktonic/oyster reefs, soft bottom

Juvenile Estuarine <18 m; sand/shell/soft bottom, oyster reef

Red Drum Larvae/postlarvae Estuarine All estuaries planktonic, SAV,

sand/shell/soft bottom, emergent marsh

Juvenile Estuarine/Marine GOM <5 m W from Mobile Bay; all

estuaries SAV, sand/shell/soft/hard bottom,

emergent marsh

Adults Marine/Estuarine GOM 146 m W from Mobile Bay; all

estuaries SAV, pelagic, sand/shell/soft/hard

bottom, emergent marsh

Lane Snapper Larvae Estuarine/Marine 4132 m; reefs, SAV

Juvenile Estuarine/Marine <20 m; SAV, mangrove, reefs,

sand/shell/soft bottom

Dog Snapper Juvenile Estuarine/Marine SAV, mangrove, emergent marsh

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4.2.11 Threatened and Endangered Species

4.2.11.1 Historic Conditions

In Louisiana, Plaquemines parish has experienced some of the most dramatic environmental changes

within the state over the past century. These changes have stressed listed species in Louisiana as their

habitats are lost or modified. Some species that historically may have inhabited the area are the red wolf

(Canis rufus) and the Louisiana black bear (Ursus americanus luteolus). Other species that were listed on

the Endangered Species List, but have since then been de-listed because populations levels have

improved are the bald eagle (Haliaeetus Leucocephalus) and the brown pelican (Pelecanus occidentalis).

Red wolf (Canis rufus). The red wolf is one of the worlds most endangered wild canids. Once common

throughout the southeastern United States, red wolf populations were decimated by the 1960s due to

intensive predator control programs and loss of habitat. A remnant population of red wolves was found

along the Gulf Coast of Texas and Louisiana. The USFWS declared red wolves extinct in the wild in

1980 (USFWS 2007). At one time red wolves may have occurred in the project area, but no documented

sightings have occurred since they were declared extinct in the wild.

Louisiana Black Bear (Ursus americanus luteolus). The Louisiana black bear was listed as a threatened

species in 1992. The Louisiana black bear is a subspecies of the American black bear, found in Louisiana,

south Mississippi and east Texas. This bear is usually black in color and typically weighs 150 to 300

pounds as an adult (USFWS 2008). The Louisiana black bear was numerous during colonial times and

may have inhabited the project area, but no documented cases exist in this area for the twentieth century.

Bald Eagle (Haliaeetus leucocephalus). Bald eagles live near rivers, lakes, and marshes where they can

find fish, their staple food (USFWS 2009a). The successful recovery of bald eagle populations within the

continental United States resulted in the delisting of the species from the Endangered Species List by the

USFWS on August 9, 2007. Bald eagles may occur in the project area but no nest trees are documented

within the MDWD project area.

Brown Pelican (Pelecanus occidentalis). Brown pelicans live in coastal regions along the Gulf and feed

primarily of on fish. The successful recovery of the brown pelican population within the continental

United States resulted in the delisting of the species from the Endangered Species List by the USFWS on

November 17, 2009. Brown pelicans inhabit the area, but do not nest within areas directly affected by the

proposed action.

4.2.11.2 Existing Conditions

Within the study area there are several animal and plant species under the Federal jurisdiction of the

USFWS and/or the NMFS, presently classified as endangered or threatened. Within Plaquemines Parish,

location of the MDWD study area, federally listed species include the pallid sturgeon (Scaphirynchus

albus), Gulf sturgeon (Acipenser oxyrhynchus desotoi), West Indian manatee (Trichechus manatus),

piping plover (Charadrius melodus), green sea turtle (Chelonia mydas), Kemps ridley sea turtle

(Lepidochelys kempii), and loggerhead sea turtle (Caretta caretta)

Gulf Sturgeon (Acipenser oxyrhynchus desotoi). The Gulf sturgeon was listed as threatened throughout

its range on September 30, 1991. Gulf sturgeon live in the estuaries and coastal shelf regions of the Gulf

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of Mexico during the cooler months of the year, from October to March. Distribution of Gulf sturgeon in

Louisiana extends from the Mississippi River east to the Pearl River. The majority of sturgeon have their

origins in the Pearl River system, where the largest population occurs (Carr, Tatman, & Chapman, 1996).

Green Sea Turtle (Chelonia mydas). The green sea turtle was listed as threatened in U.S. waters, except

for the Florida breeding population which was listed as endangered, on July 28, 1978. Due to the inability

to distinguish between these populations away from the nesting beach, green turtles are considered

endangered wherever they occur in U.S. waters. The green sea turtle is one of the largest marine turtles

with adult weights averaging between 250 to 450 pounds (Dundee 1989). In the Atlantic and Gulf of

Mexico waters, the green sea turtle typically inhabits areas adjacent to the coastline and has been known

to have a range spanning from Texas to as far north as Massachusetts (NOAA-1).

Kemp’s Ridley Sea Turtle (Lepidochelys kempii). The Kemps ridley sea turtle was listed as endangered

throughout its range, on December 2, 1970. The Kemps ridley sea turtle is the smallest of the sea turtles

with adults reaching an approximate length of 2 to 21⁄2 feet and weighing around 110 pounds (Dundee

1989). During the months of May to October, this species can be found in and around the shore line of

Louisiana with adults occupying areas around the mouth of Mississippi during the spring and

summertime (LDWF 2005).

Loggerhead Sea Turtle (Caretta caretta). The loggerhead sea turtle was listed as threatened throughout

its range on July 28, 1978. The loggerhead sea turtle is also one the larger marine turtles with average

adult lengths ranging from 3 to 7 feet and weighing approximately 300 to 1,100 pounds (Dundee 1989).

In Louisiana, this species has been found nesting on the Chandeleur Islands and Grand Isle in Terrebonne

Parish (Dundee 1989).

Pallid Sturgeon (Scaphirynchus albus). The pallid sturgeon was listed as endangered throughout its

range on October 9, 1990. The pallid sturgeon is a bottom oriented, large river obligate inhabiting the

Missouri and Mississippi Rivers from Montana to Louisiana and the Atchafalaya River. The pallid

sturgeon is adapted to the predevelopment habitat conditions that historically existed in these large rivers

(USFWS 2009b).

West Indian Manatee (Trichechus manatus). The West Indian manatee was listed as endangered on

June 2, 1970. The West Indian manatee is a large gray or brown aquatic mammal. Adults average

approximately 10 feet in length and weigh up to 2,200 pounds. Manatees inhabit both salt and freshwater

of sufficient depth (5 feet to usually less than 20 feet) throughout their range. A few individuals have been

known to stray as far north as the northern Georgia coast and as far west as the coastal waters of

Louisiana (USFWS 2001).

Piping Plover (Charadrius melodus). The piping plover was listed as threatened and endangered on

December 11, 1985. The piping plover is a shorebird that inhabits open beaches, alkali flats, and sandflats

of North America. It breeds primarily along the Atlantic coast from North Carolina to southern Canada,

along rivers and wetlands of the northern Great Plains from Nebraska to the southern prairie provinces,

and along portions of the western Great Lakes. In winter, most individuals are found on coastal beaches

and sand flats from the Carolinas to Yucatan; some scatter through the Bahamas and West Indies (Haig,

1992).

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4.2.12 Cultural and Historic Resources

This resource is institutionally significant because of the National Historic Preservation Act of 1966

(NHPA), as amended, and the NEPA of 1969. Cultural resources are technically significant because of

their association or linkage to past events, to historically important persons, and to design and/or

construction values; and for their ability to yield significant information about prehistory and history.

Cultural resources are publicly significant because preservation groups and private individuals support

their protection, restoration, enhancement, or recovery.

4.2.12.1 Historic Conditions

According to the records at the Louisiana State Division of Archaeology there has only been one previous

cultural resource survey in the project area. This survey was a linear inventory for a proposed 24 inch

pipeline for Gulf Refining Company (Chance and Associates 1981). No sites were identified by this

survey. However this survey was not conducted to todays standards and any buried sites were most likely

missed. Besides the possibility of encountering historic and prehistoric period terrestrial sites there is also

the possibility of impacting historic period sunken ships in the main channel of the Mississippi River.

4.2.12.2 Existing Conditions

Four archaeological sites are known to exist in or near the project area. These are 16PL16, 16PL15,

16PL193, and 16PL25. One historic period site was thought to be within the project area, 16PL27, Fort

De Boulye. The three prehistoric sites were visited and two, 16PL15 and 16PL25 were found to be not

eligible to the National Register of Historic Places. 16PL16 has not been evaluated because it is located

just outside the Area of Potential Effect. 16PL27 is a National Historic Landmark but is not located where

it is shown on Louisiana Division of Archaeology records. By law any effect to a National Historic

Landmark has be the subject of consultation with the National Park Service. Consultation with the

National Park Service on this issue begin with the DEIS and coordination has occurred since. It is

believed that 16PL27, if it does still exist, is located outside the Area of Potential Effect. 16PL193 is a

standing structure and also was not found eligible for the National Register of Historic Places. At this

time the area along Oak River and the Mississippi River batture has been surveyed for cultural resources.

Bayou Garelle remains to be surveyed. A task order for this is in the process of being issued.

4.2.13 Aesthetics

This resource is institutionally important because of the laws and policies that affect visual resources,

most notably the 1969 NEPA. Visual resources are publicly and technically important because of the high

value placed on the preservation of unique natural and culture landscapes.

4.2.13.1 Historic Conditions

Based on available aerial photography (namely, comparisons between 2008 photography and 1992

photography), the visual conditions of the White Ditch Study Area have seen little change over the past

20 years as it pertains to aesthetic (visual) resources. The same public thoroughfares that are in place

today were in place then, along with similar view sheds. Primary view sheds, as they are today, were best

taken from atop the local levee system, and, in some instances, LA 39. With limited access to the site, the

only other alternative for viewing and enjoying the aesthetic qualities of the land becomes available via

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watercraft. Comparisons between the two sets of photography show that areas associated with view sheds

from the public thoroughfares have changed little, while areas to be accessed by watercraft have seen

dramatic change through land loss and conversion to larger open water areas. Without older aerial

photography, ground photographs of the site, or other historical visual data, further analysis of aesthetic

(visual) conditions will not be possible.

4.2.13.2 Existing Conditions

The landscape of the region is dominated by fields and marshland with a mixture of water tolerant

vegetation and some forestation. The flood side of the levees is moderate to densely vegetated offering

some minimal view sheds into the swamps and marshlands. For a significant portion of the study area,

view sheds are only offered from atop the levee system. For those who participate in outdoor activities,

such as recreational walking, hiking and biking, nature/ ecological study, fishing, and/ or birding the

visual characteristics are much more apparent and important when on the levees or the land on the flood

side.

The most likely scenario is that the local residents are the primary utilizers of the banks of the levees for

recreational purposes and would greatly benefit from an aesthetically pleasing recreational environment.

4.2.14 Recreational Resources

4.2.14.1 Historic Conditions

Due to the somewhat isolated nature of the project area and limited access, consumptive recreational use

pressures have been moderate. Historically, primary recreational activities in the study area have been

consumptive in nature, including fishing and hunting. Saltwater recreational activities have revolved

primarily around saltwater fishing and to a lesser degree recreational shrimping and crabbing. Freshwater

based recreational opportunities have primarily been waterfowl hunting and some limited freshwater

fishing. Historically, natural ridges in the study area have supported deer and small game hunting.

As throughout much of coastal Louisiana, the study area has experienced substantial coastal erosion, loss

of wetlands and increasing salinity levels. Some of the effects were exacerbated by past and recent

hurricanes.

Due to increased salinity levels, deterioration of freshwater and intermediate marsh habitats have resulted

in decreased opportunities for waterfowl hunting. According to duck hunters, waterfowl hunting

flourished in the 1980s when the existing White Ditch siphon operated at full capacity. In recent decades,

as marshes and SAV in the area have disappeared, waterfowl have shown less preference for the study

area and duck hunting success has decreased.

Similarly, the study area has experienced erosion and subsidence, which has threatened the natural ridges

in the area that have traditionally provided opportunities for hunting deer and small game.

The lower reaches of the study area have historically offered quality saltwater fishing opportunities as is

the situation today. After the 2005 hurricanes when salinity levels were very high, anglers reported that

the area experienced one of the best periods of recreational saltwater fishing.

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4.2.14.2 Existing Conditions

The most prominent recreational activities within the study area are consumptive uses, saltwater fishing

and waterfowl hunting. Other consumptive recreation uses include recreational crabbing and shrimping

with limited deer and small game hunting on natural ridges. Non-consumptive recreational activities

appear to be minimal and include wildlife observation.

Recreation resources are publicly significant because of the high value that the public places on fishing,

boating, and hunting as measured by the large number of fishing and hunting licenses sold in Louisiana

and the large per-capita number of recreational boat registrations in Louisiana. This is particularly

important as most of the recreational activities in the study area are only accessible by boat.

There are a variety of water features in the area including canals, tributaries, bayous, wetlands and

marshes. Within the study area, recreational walking, nature/ecological study and birding are activities in

which residents and visitors may participate. Recreational sport fishing and boating in the waters is

available and encouraged where public access is available.

Tables 4-2, 4-3, and 4-4 below show the number of recreational fishing and hunting licenses and boat

registrations, respectively, within the study area. The fishing and hunting license and boat registration

data are provided by the LDWF (http://www.wlf.louisiana.gov/education/economics/).

Table 4.2: Fishing Licenses Year 2009

All Resident

Fishing Privileges

All Resident Saltwater

Privileges

All NR* Fishing

Privileges

All NR*

Saltwater

Privileges

St. Bernard 3,739 3,748 581 570

Plaquemines 3,647 3,678 1,266 1,261

Orleans 6,264 6,238 1,069 1,039

Jefferson 47,645 47,500 9,649 9,296

* Non-Resident

Table 4.3: Hunting Licenses Year 2009

Parish

Hunting Licenses

Resident

NonResident

St. Bernard 1,335 12

Plaquemines 1,023 24

Orleans 1,858 45

Jefferson 13,681 253

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Table 4.4: Boat Registrations

Year 2008

Parish

Boat

Registrations

St. Bernard 2,294

Plaquemines 3,340

Orleans 4,157

Jefferson 19,258

There are two boat launches located within the White Ditch project area (Figure 4.4):

 The Belair Pump Station launch provides a gravel ramp approximately 18 feet wide by 15 feet in

length. There is parking for 15 vehicles; however, no lighting, power, water or services are

available.

 The Pointe à la Hache Marina Boat Launch provides two concrete boat ramps each 15 feet wide

by 20 feet in length and an electric boat lift. The launch provides lighting, power, and water along

with a fuel station, a small retail store, and bait shop. The marina has a launch as well as in-water

slips.

4.2.15 Socioeconomics and Human Resources

This resource is institutionally significant because of the NEPA of 1969; the Estuary Protection Act; the

CWA; the River and Harbors Acts; the Watershed Protection and Flood Protection Act; and the Water

Resources Development Acts. Of particular relevance is the degree to which the proposed action affects

public health, safety, and economic well-being; and the quality of the human environment. This resource

is technically significant because the social and economic welfare of the nation may be positively or

adversely impacted by the proposed action. This resource is publicly significant because of the publics

concern for health, welfare, and economic and social well-being from water resources projects.

Nearly two million people, representing approximately 43 percent of the States population, reside within

the LCA Study area. The rich soil conditions, mild climate, natural waterways, and abundance of water

and other natural resources have long attracted and supported economic development in coastal

Louisiana. The diversified economy that exists in the region today includes oil and gas production and

transportation, navigation, commercial fishing, agriculture, recreation, and tourism. Employment has

varied widely with periods of rapid growth and contraction; in 2000 there were more than 800,000 jobs in

coastal Louisiana. The most influential industries for the study areas economy include oil and gas;

navigation; commercial and recreational fishing and hunting; and agriculture, all of which are essential

for supporting Louisianas economy.

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Figure 4.4: LCA White Ditch Boat Launch/Marina

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4.2.15.1 Population and Housing

4.2.15.1.1 Historic Conditions

Native American settlement in the area goes back to unknown dates. The earliest European settlement in

the area was by the French about 1700.

Phoenix is a rural town of 600 families in Plaquemines Parish on the East Bank of the Mississippi River.

It is on the opposite side of the river from Myrtle Grove. It is the closest town to the Fort De La Boulave

Site, a National Historic Landmark. In the foot-shaped delta region, locals call Plaquemines Parish the

big toe dat slipped out da boot.

Pointe à la Hache is a rural community. The name "Pointe à la Hache" is French for "cape of the axe." In

1915 a major hurricane devastated the area, busting levees and flooding the region, and 31 died in the

area. The Parish Courthouse was destroyed, but some of its material was salvaged for reuse in the new

Courthouse completed the same year. In 1965 Hurricane Betsy damaged the area with severe flooding.

The 1930 census showed the Point à la Hache area having a population of 404. The area was again

severely damaged by Hurricane Katrina at the end of August 2005. As of mid 2009, only a small number

of people have returned to live full time here

The communities of Phoenix and Pointe à la Hache are relatively old communities consisting

predominantly of mobile homes and some permanent housing, some dating back to the 1960s. There is a

sparse population within the area, with most of the residents residing between LA Hwy 15 and LA Hwy

39.

There is no new residential development, and some of the existing facilities are abandoned and in

disrepair. There is a high school in the Phoenix community which services the residents of lower East

Plaquemines Parish.

4.2.15.1.2 Existing Conditions

Population for Plaquemines Parish, location of the MDWD study area, was estimated at approximately

21,540 in 2007 (U.S. Census Bureau, 2009). This represents a decline of about 19.5 percent from the

2000 Census. The largest age category was persons between 18 and 64 years old, at approximately 62.7

percent. The White population represented an estimated 70.8 percent of the total population, African

Americans 22.2 percent, persons of Hispanic or Latino origin 3.3 percent, Asians 3.1 percent, American

Indian and Alaska native persons 2.4 percent, and persons reporting two or more races 1.3 percent.

Housing units in the parish were estimated at 8,680 in 2007, and the 2007 median household income was

estimated at $44,896.

4.2.15.2 Employment, Business, and Industrial Activity

4.2.15.2.1 Historic Conditions

Employment and businesses operating in the diversion area have been limited due to its remote location

and limited population. The area along the East Bank of the Mississippi River in the Phoenix and Pointe à

la Hache vicinity has been used as a remote site for commercial storage of chemical and fuel related

products. Barges and Ships use the area for mooring and storage.

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Prior to the Hurricanes Betsy and Katrina, the area did maintain better employment and business

opportunities for the populace, but many of the residents have not returned since these storms devastated

the area, and there is very limited opportunity existing for the few residents remaining in the local area.

There are now only two businesses in the project area consisting of a crude material storage facility in the

Phoenix area, and a fuel storage facility in the Pointe à la Hache area. There are several barges and some

ships that moor along the Mississippi River, but they do not provide sustainable employment

opportunities for the residents. There is a small boat harbor located near Pointe à la Hache on the Eastern

side of LA Hwy 39. There are very limited small businesses in the area, consisting of older convenience

stores servicing the local community. There is one gas station in the area.

4.2.15.2.2 Existing Conditions

The most influential industries for the study area economy, and the ones most likely to be impacted by

coastal wetland losses or by restoration efforts, include oil and gas, navigation (transportation); and

commercial and recreational fishing and hunting.

Of interest to the coastal degradation issue are those pipelines that exist within the coastal areas that are

vitally important as a conveyance means to move oil, gas, or chemical products from point of production

to refineries, gas plants, and intrastate and interstate pipelines. Many thousands of miles of pipelines can

be found in coastal Louisiana ranging from small gathering lines connecting production wells with

storage tanks to larger pipelines carrying very large quantities of gas or oil.

Areas east of the Mississippi River and the Barataria Basin dominate oyster production in Louisiana. St.

Bernard and Plaquemines Parishes encompass virtually all of the oyster producing areas east of the river,

and Plaquemines Parish also includes part of the Barataria Basin. From 1988 through 1997, these two

parishes accounted for approximately 50 percent of the oysters landed in Louisiana, and approximately 47

percent of landings from private leases in Louisiana. Monitoring data from the existing Caernarvon

diversion structure has shown that production of both oysters and menhaden has increased.

4.2.15.3 Community Cohesion

Community cohesion refers to the common vision and sense of belonging within a community that is

created and sustained by the extensive development of individual relationships that are social, economic,

cultural, and historical in nature. The degree to which these relationships are facilitated and made

effective is contingent upon the physical and spatial configuration of the community itself: the

functionality of the community owes much to the physical landscape within which it is set. The viability

of community cohesion is compromised to the extent to which these physical features are exposed to

interference from outside sources.

4.2.15.3.1 Historic Conditions

The downstream unincorporated communities of Phoenix and Pointe à la Hache are relatively old. Pointe

à la Hache, one of the largest settlements between English Turn and the Gulf during the first half of the

nineteenth century, was selected as the parish seat in 1846. The first church in the town was built in 1820,

the jail in 1835, and the courthouse in 1890. The first newspaper in the parish, The Rice Planter, was

published at Pointe à la Hache during the decade preceding the Civil War.

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4.2.15.3.2 Existing Conditions

With the exception of a decline in population, existing conditions in the downstream communities of

Phoenix and Pointe à la Hache are largely unchanged from the historic condition, consisting

predominantly of mobile homes and some permanent housing, some dating back into the 1960s. There

has been little employment mobility for the population. There had been, and still remains, a sparse

population within the area, with most of the residents residing between LA 15 and LA 39.

4.2.15.4 Environmental Justice

Environmental Justice (EJ) is institutionally significant because of Executive Order 12898 of 1994 (E.O.

12898) and the Department of Defenses Strategy on Environmental Justice of 1995, which direct Federal

agencies to identify and address any disproportionately high adverse human health or environmental

effects of Federal actions to minority and/or low-income populations. Minority populations are those

persons who identify themselves as Black, Hispanic, Asian American, American Indian/Alaskan Native,

and Pacific Islander. A minority population exists where the percentage of minorities in an affected area

either exceeds 50 percent or is meaningfully greater than in the general population. Low-income

populations as of 2000 are those whose income are $22,050.00 for a family of four and are identified

using the Census Bureaus statistical poverty threshold. The Census Bureau defines a poverty area as a

Census tract with 20 percent or more of its residents below the poverty threshold and an extreme poverty

area as one with 40 percent or more below the poverty level. This is updated annually at

http://aspe.hhs.gov/poverty/09poverty.shtml. This resource is technically significant because the social

and economic welfare of minority and low-income populations may be positively or disproportionately

impacted by the proposed actions. This resource is publicly significant because of public concerns about

the fair and equitable treatment (fair treatment and meaningful involvement) of all people with respect to

environmental and human health consequences of Federal laws, regulations, policies, and actions.

A potential disproportionate impact may occur when the percent minority (50 percent) and/or percent

low-income (20 percent) population in an EJ study area are greater than those in the reference

community. For purposes of this analysis, all Census Block Groups within the project footprint are

defined as the EJ study area. Plaquemines Parish, of which the LCA Medium Diversion at White Ditch

(MDWD) project is located, is considered the reference community of comparison, whose population is

therefore considered the EJ reference population for comparison purposes. Parish figures were used for

unincorporated areas located within 1 mile of the proposed project footprint. Where applicable, parish

figures were used for unincorporated areas (Census Block Groups) located within 1 mile of the proposed

project footprint if the block group numbers are so small as to not meet the requirements for further

consideration.

The methodology, consistent with E.O. 12898, to accomplish this EJ analysis includes, identifying lowincome and minority populations within the LCA-MDWD project area using up-to-date economic

statistics, aerial photographs, 2000 U.S. Census records, Environmental Systems Research Institute, Inc.

(ESRI) estimates, as well as conducting community outreach activities such as public meetings. Despite

the 2000 U.S. Census being 9 years old, it serves as a logical baseline of information and is the primary

deciding variable per data accuracy and reliability for the following reasons:

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 Census 2000 data is the most accurate source of data available due to the sample size of the

Census decennial surveys. With one of every six households surveyed, the margin of error is

negligible.

 The Census reports data at a much smaller geographic level than other survey sources, providing

a more defined and versatile option for data reporting.

 Census information sheds light upon the demographic and economic framework of the area preHurricane Katrina. By accounting for the absent population, the analysis does not exclude

potentially low income and minority families that wish to return home.

Due to the considerable impact of Hurricane Katrina upon the New Orleans metropolitan area, and the

likely shift in demographics and income, the 2000 Census data are supplemented with more current data,

including 2007 and 2008 estimates provided by ESRI. The 2007 and 2008 estimates are utilized for

reference purposes only to show changing trends in population since 2000.

4.2.15.4.1 Historic Conditions

The concept of environmental justice is rooted in Title VI of the Civil Rights Act of 1964, which

prohibited discrimination based on race, color and national origin, and other nondiscrimination statutes as

well as other statutes including the NEPA of 1969, the Uniform Relocations Assistance and Real Property

Acquisition Policies Act of 1970, and 23 U.S.C Section 109 (h). In 1971, the CEQ annual report

acknowledged racial discrimination adversely affects the environment of the urban poor. During the next

10 years, activists maintained that toxic waste sites were disproportionately located in low-income and

areas populated by people of color. By the early 1980s, the environmental justice movement had

increased its visibility and broadened its support base (Commission for Environmental Equality 2009).

This led to the United Church of Christ (UCC) undertaking a nationwide study and publishing Toxic

Waste and Race in the United States (UCC 1987). This eventually gained the attention of the Federal

Government and in 1992 the USEPAs Office of Environmental Equity was established. In 1994, EJ was

institutionalized within the Federal Government through Executive Order 12898 (EPA 1995a), which

focused Federal attention on human-health and environmental conditions in minority and low-income

communities (EPA 1995a, 1995b, 1995c, 1995d).

Executive Order 12898 requires greater public participation and access to environmental information in

affected communities. The results of early efforts and research (UCC 1987) into EJ suggested that

environmental amenities and toxic waste sites were not uniformly distributed among income groups,

classes, or ethnic communities. Disparities of this nature may have been and continue to be the result of

historical circumstances, lack of community participation, or simply inadequate or inappropriate

oversight. Consequently, dialogue with some community groups were not conducted and their concerns

not considered in the decision making process on local or Federal actions.

Residential areas and businesses for minority and low-income populations have historically been limited

within the White Ditch Diversion study area due to the area being predominantly surrounded by brackish

marsh and unsuitable for building. Some areas were drained and later inhabited, but the areas adjacent to

the diversion area remain uninhabited.

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4.2.15.4.2 Existing Conditions

The total population of this parish, according to the 2000 U.S. Census Bureau is 26,757. Because the area

has such a low population density, the Plaquemines Parish and Louisiana state census figures were used

to determine whether the White Ditch Diversion area meets the requirements set under Executive Order

12898 for further consideration. For 2008 the U.S. Census Bureaus population estimates were 21,276.

This represents a slight population decline possibly due to the effects of Hurricanes Katrina and Rita in

2005.

According to the 2000 U.S. Census, the LCA MDWD project boundary in Plaquemines Parish is located

within Census Tract 501, Block Group 1. The 2000 Census demographic profile records indicate that the

minority population in Louisiana was 38.7 percent of the total population and the low-income population

was 19.6 percent of the total population. The minority population in Plaquemines Parish was 31.8 percent

and the low-income population was 18.0 percent in 2000. The 2008 estimates were approximately 32.1

percent minority and 11.2 percent low-income (http://censtats.census.gov, accessed November 11, 2009).

Analyses of the above information show that the percentage of the population that is minority is

comparable to that of state figures and low-income populations are lower than state figures. Because there

are few residential neighborhoods in the proposed project area, and based on the aforementioned 2000

U.S. Census figures, as well as field visits conducted in November 2009 to the proposed project area, it

has been determined that the proposed LCA MDWD project area is not a minority and/or low income

population per Executive Order 12898.

4.2.15.5 Infrastructure

4.2.15.5.1 Historic Conditions

Infrastructure in the project area has historically been limited due to the remote and low-elevation

location as well as low population in this part of southeastern Louisiana.

4.2.15.5.2 Existing Conditions

Infrastructure in the project area includes the Federal Mississippi River levee, LA 39, and non-Federal

back levees to the north and south of the proposed diversion location. An overhead power-line operated

by Entergy has three poles that are located in the vicinity of the proposed construction area. A buried

telephone cable is also located in the vicinity.

4.2.15.6 Business and Industry

4.2.15.6.1 Historic Conditions

Business and industry had historically been limited within White Ditch Diversion area. The early

predominant industries have been trapping and hunting. However, oil production, commercial fishing

activities and oyster harvesting have had some impact within the area.

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4.2.15.6.2 Existing Conditions

There are no industries located in the inhabited areas adjacent to the White Ditch Diversion area. The two

significant business operations consist of a chemical storage facility near Phoenix and a fuel storage

operation near Pointe à la Hache. There is also a small boat harbor near Pointe à la Hache. Most other

businesses are small operations supporting the local populations. The area adjacent to the White Ditch

Diversion area is protected by a levee system. Pipelines and oyster leases exist within the project area.

4.2.15.7 Traffic and Transportation

4.2.15.7.1 Historic Conditions

The communities east of LA Hwy 39 are remote and receive little vehicle traffic. LA Hwy 39 services

local residents but is used mostly for commercial vehicles traveling to the two commercial chemical and

fuel storage facilities located in the area.

4.2.15.7.2 Existing Conditions

LA Hwy 39 is a two-lane sparsely traveled highway which terminates at Pointe à la Hache. Traffic

consists predominately of commercial vehicles traveling to the two commercial chemical and fuel storage

facilities located in the area. It also provides egress for the residents of Phoenix and Pointe à la Hache.

There is additional recreational traffic from vehicles transiting to the Pointe à la Hache Boat Harbor. The

area adjacent to the White Ditch Diversion area is protected by a levee system.

4.2.15.8 Public Facilities and Services

4.2.15.8.1 Historic Conditions

The inhabited area adjacent to the White Ditch project area is sparsely populated with the heaviest

concentration of residents residing in the Phoenix and Pointe à la Hache areas. There are few public

facilities or services provided within the populated areas. There is a public high school servicing the

students in the lower portion of East Plaquemines Parish. There is also a volunteer fire department located

in Phoenix.

The community of Pointe à la Hache once contained the Plaquemines Parish Public Courthouse, built in

1915. It was damaged by recurring hurricanes, and was finally burned by arson in 2002.

4.2.15.8.2 Existing Conditions

There are a limited number of public facilities in the vicinity of the proposed Phoenix diversion area.

These facilities include a volunteer fire department and the Phoenix High School.

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4.2.15.9 Tax Revenues and Property Values

4.2.15.9.1 Historic Conditions

The White Ditch diversion area is an under-developed marsh. The area East of LA Hwy 39 consisted of

marsh and bayous, with some man-made canals. The majority of tax revenues have been derived from

taxes on oil production and seafood products harvested in the area.

4.2.15.9.2 Existing Conditions

The proposed White Ditch project area is located near Phoenix, Louisiana. No economic data is available

for the specific project area, but the nearest available data is at the parish level. Median household income

in Plaquemines Parish in 2007 was estimated at $44,896 (statewide average was estimated at $40,866 for

the same year). The median value of owner-occupied homes in Plaquemines Parish in 2000 was $110,100

(compared with the state average of $85,000) (Source: U.S. Census Bureau: State and County QuickFacts.

Data derived from Population Estimates, Census of Population and Housing, Small Area Income and

Poverty Estimates, State and County Housing Unit Estimates, County Business Patterns, Nonemployer

Statistics, Economic Census, Survey of Business Owners, Building Permits, Consolidated Federal Funds

Report, Last Revised November 17, 2009).

4.2.15.10 Community and Regional Growth

4.2.15.10.1 Historic Conditions

The communities adjacent to the White Ditch Diversion area were originally populated by trappers and

hunters. Over time, Phoenix and Pointe à la Hache experienced limited economic growth primarily

consisting of local small businesses supporting the areas population.

There is little population within the project area. The area is used primarily for recreational activity and

there are oil and gas wells and commercial oyster leases existing in portions of the affected area.

4.2.15.10.2 Existing Conditions

Community and regional growth are generally influenced by national trends, but otherwise depend

significantly upon relatively local attributes that allow it to be evaluated apart from the national economy.

For the purposes of socioeconomic impact analysis, the project area is first described in summary terms

with respect to prevailing trends in the growth of population, housing, income, and employment. Against

this baseline, the relative effects of the proposed and alternative actions are evaluated.

Data for Plaquemines Parish, East Bank is not easily discernable through census data. The nearest

impacted areas with available census data is St. Bernard Parish. According to U.S. Census data from 1990

and 2000 the following trends were observed in St. Bernard Parish: population grew from 66,631 to

67,229; employment grew from 30,738 to 31,267; and median household income grew from $25,482 to

$35,939.

Preliminary 2010 Census data will be available in 2011 at the earliest. However, intermediate census

estimates reported by the Greater New Orleans Data Center indicated a population in St. Bernard Parish

of 19,826 in 2007.

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4.2.15.11 Land Use Socioeconomics

4.2.15.11.1 Agriculture

4.2.15.11.1.1 Historic Conditions

Agriculture in Plaquemines Parish (excluding commercial fishing as discussed in Section 4.2.15.15)

consists mainly of citrus and nursery crops, as well as livestock (primarily cattle) production. Agriculture

on the east bank of the parish is limited by the availability of land suitable for cultivation of crops or

livestock. Loss of marsh and marsh land in the project area during the past several decades has limited the

potential for agricultural production in the project area. Reports from long-time residents of the east bank

of Plaquemines Parish indicate that some portions of the project area may have been used for livestock

grazing. No current agricultural production is known to be located within the immediate White Ditch

project area, with the exception of alligator farming (egg harvesting), which occurs seasonally in portions

of the project area and adjacent parts of the northern Breton Sound Basin under permits issued by the

Louisiana Department of Fish and Wildlife.

4.2.15.11.1.2 Existing Conditions

Louisianas alligator farming program began in the early 1970s, but production did not significantly

increase until the early 1990s. In the last few years, production has exceeded 200,000 skins. Nearly all of

this production is the result of collecting eggs from nests in the wild. To compensate for the removal of

eggs, a proportion of the alligators raised on the farm are returned to the marshland where the eggs were

originally collected.

Statewide data collected by the LDWF showed that in 2008 a total of 530,579 eggs were collected,

459,887 were hatched, and 45,578 of these hatchlings were returned to the wild. While statewide

estimates indicated an increase in nest production of 3.1 percent over 2007 figures, estimates for

southeastern Louisiana (which includes the White Ditch project area) indicated a 0.3 percent decrease

from 20072008, compared with an estimated 8.7 percent increase for southwestern Louisiana for the

same period.

4.2.15.11.2 Forestry

4.2.15.11.2.1 Historic Conditions

None.

4.2.15.11.2.2 Existing Conditions

The MDWD project has no commercial forestry production located within the proposed project area.

4.2.15.11.3 Public Lands

4.2.15.11.3.1 Historic Conditions

None.

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4.2.15.11.3.2 Existing Conditions

The MDWD project has no public lands located within the proposed project area.

4.2.15.12 Water Use and Supply

4.2.15.12.1 Historic Conditions

The Mississippi River has historically been the primary source of freshwater in the project area.

4.2.15.12.2 Existing Conditions

The Mississippi River is the primary source of public water supply in Plaquemines Parish. Water use and

supply facilities located within the vicinity of the White Ditch project area include a water tower servicing

the residents of the Pointe à la Hache and Phoenix communities.

4.2.15.13 Navigation

4.2.15.13.1 Historic Conditions

Annual U.S. port tonnage statistics consistently rank the Ports of New Orleans, South Louisiana, and

Baton Rouge fourth, first, and ninth, respectively. Primary inbound cargos at the Port of Baton Rouge are

petroleum and chemicals. Outbound cargos are grain, chemicals, and petroleum products. Primary

inbound cargos at the Port of South Louisiana are crude oil and petroleum products, while corn, wheat,

and animal feed dominate the ports exports. At the Port of New Orleans, principal inbound cargos consist

of steel, crude, and refined petroleum products and outbound cargos include grain, forest products, and

steel. The river reach adjacent to the MDWD project area is within the Port of Plaquemines. In 2008, U.S.

port tonnage statistics ranked the Port of Plaquemines tenth in the nation, with estimated cargos totally

over 63,744 million short tons.

4.2.15.13.2 Existing Conditions

The Mississippi River is the major navigable waterway in the vicinity of the proposed project.

Commercial navigation is a critical activity in the river bordering the west side of the White Ditch project

area. On the east bank of the Mississippi River, the water bodies within the project area have not been

used extensively for shallow water navigation, and there is no deep water navigation possible in the area.

There are man-made canals once used by oil companies, but commercial use of these canals is limited and

they are now used mostly for recreational purposes.

4.2.15.14 Man-Made Resources

4.2.15.14.1 Oil, Gas, Utilities, Pipelines

4.2.15.14.1.1 Historic Conditions

Louisiana is laced with thousands of pipelines conveying oil, gas, and other liquid and gaseous materials

for short and long distances. Included are 25,000 miles (40,250 km) of pipe moving natural gas through

interstate pipelines, 7,600 miles (12,236 km) of pipe carrying natural gas through intrastate pipelines to

users within the states boundaries, 3,450 miles (5,554 km) of pipe transporting crude oil and crude oil

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products, and thousands of miles of flowlines carrying oil and gas from the wellhead to separating

facilities.

The petroleum industry in the state accounts for almost 25 percent of the total state revenues and employs

more than 116,000 people (about 6 percent of the states total workforce). These workers earn almost 12

percent of the total wages paid in Louisiana. The oil and gas production industry, and the numerous

associated support industries, are an important part of the socioeconomic landscape of the project area

(see Employment and Income section). Indirect employment levels in support industries make this

economic sector more important than is indicated by the direct employment figures.

Of interest to the coastal degradation issue are those pipelines existing within the coastal areas that are

vitally important as a conveyance means to move oil, gas, or chemical products from point of production

to refineries, gas plants, and intrastate and interstate pipelines. Pipelines found in coastal Louisiana range

from small gathering lines connecting production wells with storage tanks to larger pipelines carrying

very large quantities of gas or oil.

4.2.15.14.1.2 Existing Conditions

The MDWD project area contains some pipelines that cross LA Hwy 39. There are utility service lines

that traverse the length of LA Hwy 39 servicing the communities located south of the proposed diversion

structure. There are no oil refineries or rigs located within the diversion area. State database records show

several oil wells in the vicinity of proposed construction features (Figure 4.5). As noted in Appendix J

(Real Estate Plan), there are two oil wells located within the proposed channel, and one oil well located

within the proposed marsh creation/wetland restoration. All wells located within the right-of-way limits of

the project are closed/abandoned and, therefore, not productive or in use. Closed/abandoned wells within

the project area are not anticipated to cause real estate issues or delays for the project.

The impacts of the Deepwater Horizon oil spill on coastal Louisiana are uncertain at this time (August 5,

2010). This spill could potentially adversely impact USACE water resources projects and studies within

the Louisiana coastal area. Potential impacts could include factors such as changes to existing or baseline

conditions, as well as changes to future-without and future with project conditions. The USACE will

continue to monitor and closely coordinate with other Federal and state resource agencies and local

sponsors in determining how to best address any potential problems associated with the oil spill that may

adversely impact USACE water resources development projects/studies. This could include revisions to

proposed actions as well as the generation of supplemental environmental analysis and documentation for

specific projects/studies as warranted by changing conditions.

4.2.15.14.2 Flood Control and Hurricane Protection

4.2.15.14.2.1 Historic Conditions

None.

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Figure 4.5: LCA White Ditch Oil/Gas Wells and Pipelines

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4.2.15.14.2.2 Existing Conditions

Protection from high Mississippi River levels in the vicinity of the proposed project is provided by the

Federal levee that runs the length of the western border of the White Ditch project area. Residences and

businesses upstream and downstream of the proposed diversion construction site are protected from Gulf

storm surges by non-Federal back levees.

4.2.15.15 Natural Resources

4.2.15.15.1 Commercial Fisheries

4.2.15.15.1.1 Historic Conditions

Louisianas coastal wetlands are the richest estuaries in the country for fisheries production.

Commercially and recreationally important species such as brown and white shrimp, blue crabs, eastern

oysters, and menhaden are abundant, but these species populations are threatened if land loss continues.

Louisiana has historically been an important contributor to the nations domestic fish and shellfish

production, and is one of the primary contributors to the nations food supply for protein. While

Louisiana has long been the nations largest shrimp and menhaden producer, it has also recently become

the leading producer of blue crabs and oysters. Total landings in Louisiana were 1.2 billion pounds (0.54

billion kg) in 2001. The percentage contribution of total landings for the Gulf region was 74 percent and

for the nation was 12.5 percent. Dockside revenues for commercial fisheries in coastal Louisiana were

$343 million in 2001 (NMFS 2003b). These revenues were the largest for any state in the contiguous

United States, second only to Alaska.

4.2.15.15.1.2 Existing Conditions

The MDWD project area along with the larger Breton Sound Basin contains important commercial

fishery resources including saltwater fish, shellfish and oysters.

4.2.15.15.2 Oyster Leases

4.2.15.15.2.1 Historic Conditions

Louisiana is the top producer of the eastern oyster in the United States, averaging approximately 13.1

million pounds per year since 2000, with an average value of $34.0 million (NMFS Fisheries Statistics

Division, personal communication, 2009). The fishery has two main sources: privately leased grounds

and public seed grounds. The State of Louisiana owns the water bottoms and leases out acreage to oyster

fishermen. The public grounds are open to harvesting by all licensed fishermen, but are only open during

the public season, which runs from September through March. Oysters can be harvested from the private

grounds throughout the year.

4.2.15.15.2.2 Existing Conditions

Areas east of the Mississippi River and the Barataria Basin dominate oyster production in Louisiana. St.

Bernard and Plaquemines parishes encompass virtually all of the oyster producing areas east of the river.

From 1988 through 1997, these two parishes accounted for approximately 50 percent of the oysters

landed in Louisiana, and approximately 47 percent of landings from private leases in Louisiana. Oyster

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leases in Plaquemines Parish have 15-year terms and are leased from the state for $2 per acre per year.

The White Ditch project area contains 311 oyster leases at the Gulf end of the proposed freshwater

diversion area. Figure 4.6 below, and also found in Appendix J (Real Estate Plan, Exhibit B) of this

report, shows the locations of these oyster leases. When existing conditions salinities are overlaid on the

leases, approximately seven of the leases could experience suboptimal salinities for high oyster

production.

4.2.16 Hazardous, Toxic, and Radioactive Wastes

4.2.16.1 Historic Conditions

The USACE is obligated under Engineer Regulation (ER) 1165-2-132 to assume responsibility for the

reasonable identification and evaluation of all HTRW contamination within the vicinity of the proposed

action. ER 1165-2-132 identifies the USACE policy to avoid the use of project funds for HTRW removal

and remediation activities. Costs for necessary special handling or remediation of wastes (e.g., those

regulated by the Resource Conservation and Recovery Act of 1976 [RCRA]), pollutants and other

contaminants, which are not regulated under the CERCLA, will be treated as project costs if the

requirement is the result of a validly promulgated Federal, state or local regulation.

HTRW investigations facilitate early identification and consideration of HTRW problems. The Civil

Works Project Plan routinely includes a phased and documented review to provide for early identification

of HTRW potential at project sites. ER 1165-2-132 requires that viable options to avoid HTRW problems

be determined and a procedure for resolution of HTRW concerns be established.

The discharge of dredged material into waters of the U.S. is regulated under the CWA, and the Marine

Protection and Sanctuaries Act governs the transportation of dredged material to ocean waters for the

purpose of disposal. The RCRA hazardous waste management regulations, promulgated pursuant to

RCRA (42 U.S.C. 6905) specifically exempt dredge material from the hazardous waste definition if that

material is covered by:

1) a permit issued under Section 404 of the CWA, 33 U.S.C. 1344;

2) a permit issued under Section 103 of the Marine Protection, Research and Sanctuaries Act of

1972 33 U.S.C. 1413; or

3) the administrative equivalent of such permits where the work involves an Army Corps of

Engineers civil works project, 40 C.F.R. 261.4(g), 63 F.R. 65874, 65921; November 30, 1998.

ER1165-2-132 states, dredged material and sediments beneath navigable waters proposed for

dredging qualify as HTRW only if they are within the boundaries of a site designated by the EPA

or a state for a response action (either a removal or a remedial action) under CERCLA, or if they

are a part of a NPL site under CERCLA.

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Figure 4.6: LCA White Ditch Existing Condition Salinities – July 2009

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4.2.16.2 Existing Conditions

As reported in the Phase I ESA, during records research and site reconnaissance it was determined that

areas adjacent to some of the project features contained RECs that presented a low to moderate risk of

affecting potential project features, albeit that no Recognized Environmental Conditions (RECs) were

noted within direct proximity of land associated with any of the potential project features.

Should at anytime during the project HTRW concerns arise, the CEMVN would take immediate actions

to investigate the concerns. Should an HTRW issue be determined and the development of a response

action required, CEMVN would coordinate with the appropriate Federal and state authorities to

implement an approved response action.

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5.0 ENVIRONMENTAL CONSEQUENCES

This chapter describes the potential environmental consequences of implementing alternative plans

considered for freshwater diversion and marsh restoration in the project study area. The following

analysis compares the No Action Alternative to four alternatives carried over for detailed analysis:

Alternative Plans 1, 2, 3, and 4. Alternative 4 is the Recommended Plan. Alternatives developed and

evaluated in this study are described in Chapter 3, Alternatives. If this diversion were operated fully open

outside the 2-month window that is described in the document, then there could be significantly different

impacts with some potentially being very negative.

A comparison of the direct, indirect, and cumulative impacts for wetland creation and enhancement is

presented herein. Direct impacts would be those effects that would be caused by the proposed action and

occur at the same time and place (Section 1508.8(a) of 40 CFR Parts 15001508). For example, the use of

excavated material from construction of outfall management features would be used directly to create

acres of emergent wetland habitat. Indirect impacts would be those effects that would be caused by the

action and would be later in time or further removed in distance, but would be still reasonably foreseeable

(Section 1508.8(b) of 40 CFR Parts 15001508). For example, shoreline protection features reduce the

long-term rate of erosion to interior wetlands. Cumulative impacts would be the aggregate of impacts to

the environment resulting from the proposed action in combination with other ongoing actions, and

actions being considered within the reasonably foreseeable future. Cumulative impacts would be the

effects on the environment that would result from the incremental impact of the action when added to

other past, present, and reasonably foreseeable future actions, regardless of what agency (Federal or nonFederal) or person undertakes such actions. Cumulative impacts can result from actions that individually

would be minor, but collectively result in significant actions taking place over time (Section 1508.7 40

CFR Parts 15001508). For example, the incremental impacts of emergent wetland creation at several

localized areas could significantly modify an entire basins habitat diversity. The cumulative impact

analysis followed the 11-step process described in the 1997 report by the Council of Environmental

Quality entitled Considering Cumulative Effect Under the National Environmental Policy Act. Section

5.21 summarizes cumulative impacts for all important resources.

This environmental analysis evaluates and compares, from a qualitative and quantitative perspective, the

four alternatives carried over for detailed analysis. Impact analysis described in this chapter is based on a

combination of scientific and engineering analyses, professional judgment, and previously compiled

information.

The operational scenario used in the evaluation of all alternatives, including the Recommended Plan,

involves operating the diversion structure at full flow capacity for 2 months each year, and at a reduced

maintenance flow for the remainder of the year. High river flows (with corresponding high suspended

sediment levels) historically occurred in the early spring on the lower Mississippi River, and prior to

construction of the Federal levee system would have naturally replenished coastal wetlands in the project

study area with freshwater, sediment and nutrients. In addition, both historical information and more

recent scientific investigations of freshwater diversions such as the Caernarvon freshwater diversion

suggest that potential negative consequences of reintroduction of river inflows in the MDWD project

would be more likely to be reduced or minimized if flows would be limited in duration and would be

timed to avoid sensitive periods in the annual life cycles of marsh vegetation and associated aquatic

organisms.

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The impacts of the Deepwater Horizon oil spill on coastal Louisiana are uncertain at this time (August 5,

2010). This spill could potentially adversely impact USACE water resources projects and studies within

the Louisiana coastal area. Potential impacts could include factors such as changes to existing or baseline

conditions, as well as changes to future-without and future with project conditions. The USACE will

continue to monitor and closely coordinate with other Federal and state resource agencies and local

sponsors in determining how to best address any potential problems associated with the oil spill that may

adversely impact USACE water resources development projects/studies. This could include revisions to

proposed actions as well as the generation of supplemental environmental analysis and documentation for

specific projects/studies as warranted by changing conditions.

5.1 SOILS AND WATERBOTTOMS

5.1.1 Soils and Waterbottoms

5.1.1.1 No Action Alternative (Future Without Project Conditions)

5.1.1.1.1 Direct

No direct alteration of soils or substrate would occur under the No Action Alternative and associated

water management features. No conversion of prime or unique farmland would occur, and the No Action

Alternative would have no direct impact on these resources.

5.1.1.1.2 Indirect

Under the No Action Alternative, existing patterns of soil erosion and land loss would continue into the

future. Organic soils in the project area would not be able to maintain their elevations due to subsidence,

decreased plant productivity, wave erosion, and relative sea level rise. Net primary productivity within the

project area would continue to decline and existing wetland vegetation would continue to diminish. The

ongoing conversion of existing fragmented emergent wetlands to shallow open water would continue with

associated indirect impacts on coastal vegetation, fish and wildlife resources, EFH, recreation, aesthetic,

and socioeconomic resources. In the future, if no actions would be taken to restore and protect marsh

habitat within the project area, any prime and unique farmland that remains outside of the protection of

existing Federal and non-Federal back levees would continue to be subject to further degradation and

possible loss.

5.1.1.1.3 Cumulative

Under the No Action Alternative, as erosion continued, there would be a continued loss of marsh soils.

Waterbodies would grow larger and wave erosion would accelerate causing further land loss, thus making

remaining marsh lands in the project area and the larger Breton Sound Basin more vulnerable to tropical

storms. In addition to land loss in coastal Louisiana, a large percentage of the nations wetlands would

continue to disappear with accompanying impacts to wildlife, fisheries, coastal communities, and

socioeconomic resources.

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5.1.1.2 Alternative 1 – 5,000 cfs max Diversion

5.1.1.2.1 Direct

Construction of the 5,000 cfs maximum diversion would directly impact approximately 324 acres in the

intermediate zone (136 acres of marsh and 188 acres of shallow open water). Approximately 153 acres of

marsh and shallow water area would be excavated to enlarge the outfall channel for the structure. This

excavated material would be placed on organic marsh soils and aquatic substrates to create approximately

32 acres of ridges lining the outfall channels, and 139 acres of created marsh in locations adjacent to the

outfall channels.

5.1.1.2.2 Indirect

Loss of marsh soils would continue in the project area; however, indirect impacts of implementing the

5,000 cfs max diversion would include reducing the rate of marsh soil loss in the project area compared to

the projected rate of loss under the FWOP condition over the 50-year period following construction.

5.1.1.2.3 Cumulative

This alternative would have positive synergistic effects on soil resources when combined with other

Federal, state, local, and private restoration efforts, including the nearby Caernarvon diversion.

Implementing the 5,000 cfs diversion alternative would contribute to reducing regional rates of marsh soil

loss over the 50-year project life.

5.1.1.3 Alternative 2 – 10,000 cfs max Diversion

5.1.1.3.1 Direct

Construction of the 10,000 cfs maximum diversion would directly impact approximately 375 acres in the

intermediate zone (155 acres of marsh and 220 acres of shallow open water). Approximately 167 acres of

marsh and shallow water area would be excavated to enlarge the outfall channel for the structure. This

excavated material would be placed on organic marsh soils and aquatic substrates to create approximately

32 acres of ridges lining the outfall channels, and 176 acres of created marsh in locations adjacent to the

outfall channels.

5.1.1.3.2 Indirect

Indirect impacts of implementing the 10,000 cfs max diversion would include substantially reducing the

rate of marsh soil loss in the project area compared to the projected loss rate under FWOP conditions over

the 50-year period following construction.

5.1.1.3.3 Cumulative

This alternative would have positive synergistic effects on soil resources when combined with other

Federal, state, local, and private restoration efforts, including the nearby Caernarvon diversion.

Implementing the 10,000 cfs diversion alternative would contribute to reducing regional rates of marsh

soil loss over the 50-year project life.

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5.1.1.4 Alternative 3 – 15,000 cfs max Diversion

5.1.1.4.1 Direct

Construction of the 15,000 cfs maximum diversion would directly impact approximately 449 acres in the

intermediate zone (199 acres of marsh and 250 acres of shallow open water). Approximately 182 acres of

marsh and shallow water area would be excavated to enlarge the outfall channel for the structure. This

excavated material would be placed on organic marsh soils and aquatic substrates to create approximately

32 acres of ridges lining the outfall channels, and 235 acres of created marsh in locations adjacent to the

outfall channels.

5.1.1.4.2 Indirect

Indirect impacts of implementing the 15,000 cfs max diversion would include the expected restoration of

emergent marsh soils at a rate that would exceed the projected loss rate under the FWOP condition over

the 50-year period following project construction.

5.1.1.4.3 Cumulative

This alternative would have positive synergistic effects on soil resources when combined with other

Federal, state, local, and private restoration efforts, including the nearby Caernarvon diversion.

Implementing the 15,000 cfs diversion alternative would contribute to reducing regional rates of marsh

soil loss over the 50-year project life.

5.1.1.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.1.1.5.1 Direct

Construction of the 35,000 cfs maximum diversion would directly impact approximately 640 acres in the

intermediate zone (277 acres of marsh and 363 acres of shallow open water). Approximately 223 acres of

marsh and shallow water area would be excavated to enlarge the outfall channel for the structure. This

excavated material would be placed on organic marsh soils and aquatic substrates to create approximately

32 acres of ridges lining the outfall channels, and 385 acres of created marsh in locations adjacent to the

outfall channels.

5.1.1.5.2 Indirect

Indirect impacts of implementing the 35,000 cfs max diversion would include the expected restoration of

emergent marsh soils at a rate that would substantially exceed the projected loss rate under the FWOP

condition over the 50-year period following project construction.

5.1.1.5.3 Cumulative

This alternative would have positive synergistic effects on soil resources when combined with other

Federal, state, local, and private restoration efforts, including the nearby Caernarvon diversion.

Implementing the 35,000 cfs diversion alternative would provide the highest potential contribution of the

four alternatives evaluated in detail in this study to reducing regional rates of marsh soil loss.

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5.2 HYDROLOGY

5.2.1 Flow and Water Levels

5.2.1.1 No Action Alternative (Future Without Project Conditions)

5.2.1.1.1 Direct

The No Action Alternative would have no direct impacts on flow or water levels within the surrounding

marsh or historic distributaries such as River aux Chenes.

5.2.1.1.2 Indirect

Indirect impacts of the No Action Alternative, not implementing the diversion, would result in the

persistence of existing conditions. Consequences would include further degradation of the existing marsh

from saltwater intrusion due to short circuited hydrologic processes present in the basin, as well as the

continued lack of sediments, nutrients, and freshwater. With the absences of these inputs, the marsh

would not be able to sustain itself against subsidence and prolonged inundation from increasing sea level

rise rates, Figure 5-1.

E s tim a t e d S e a L e v el R is e fo r W h ite 's D it c h IA W E C - 1 1 6 5 - 2 - 2 1 1

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

2000 20 10 202 0 2030 2 040 2050 2060 2070

Yea r

E stim ated Sea L e vel Ri

L o w cu r ve (h i s to ri c ) In te rm e dia te cu rve H igh cu rve

Figure 5.1: Sea Level Rise Rates for the White Ditch Study Area

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The No Action Alternative would result in the existing marsh persisting with minimal circulation of

water, nutrients, and sediment. The sediment deficit has and would continue to result in both subsidence

and a disruption of natural processes that promote productivity and diversity in the marsh ecosystem.

Increases in relative sea level due to continued subsidence and sea level rise would continue to inundate

plant communities with saltwater, which would induce stress and lead to further degradation.

Current guidance for incorporating the direct and indirect physical effects of projected future sea-level

change in all aspects of USACE projects (i.e., managing, planning, engineering, designing, constructing,

operating, and maintaining) is established by Circular No. 1165-2-211, dated July 1, 2009. Under this

direction, the no action and action alternatives must be evaluated under low, intermediate, and high

projected rates of future sea-level change. Scenarios differ in whether and how eustatic sea-level rise

accelerates over time. Accordingly, the low estimate is based on an extrapolation of the historic rate of

RSLR for the study area. Against the high sea level rise scenario, all marsh would be gone in

approximately 45 years under the No Action Alternative.

5.2.1.1.3 Cumulative

Cumulative impacts would be the synergistic effect of the No Action Alternative on flow and water levels

with the added combination of similar wetland degradation and wetland loss impacts to flow and water

levels throughout coastal Louisiana, as well as the benefits and impacts of other state and Federal coastal

restoration projects in the vicinity. The Caernarvon Diversion does freshen the White Ditch project area,

albeit to an unknown extent. It could potentially impact the flow patterns in and near the study area, but

would not likely affect water levels. The proposed CWPPRA project for the rehabilitation and expansion

of the existing siphon at White Ditch could have impacts on the project area, but conclusive detail as to

those extents would not be available at this time. Other diversion along the Mississippi River would

collectively have impacts on Mississippi River stages and possibly sediment and nutrient loads available

to the Breton Sound Basin.

5.2.1.2 Alternative 1 – 5,000 cfs max Diversion

5.2.1.2.1 Direct

The direct impact of a diversion with the potential of operating up to 5,000 cfs in the area between River

aux Chenes and the Mississippi River would be increased water levels and flows within the project area

while the structure is being operated. During operations, Mississippi River water would flow through

River aux Chenes, Bayou Garelle, and numerous other natural and man-made channels. Stages would be

elevated near the outfalls of where water is leaving the Bayou Garelle and flowing into larger, more open,

bodies of water.

The direct impact of the diversion of water from the Mississippi River at the proposed diversion site

would be a very small decrease in the flow in the Mississippi River. Based on data from 1978 to 2008, the

average spring (March 1  May 31) flow at Tarbert Landing is 813,333 cfs ± 283,377 cfs (Mean + SD),

vs. a diversion rate of 5,000 cfs. The small decrease in flow at this intake location would have no impact

on water levels in the Mississippi.

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5.2.1.2.2 Indirect

Indirect impacts of a 5,000 cfs diversion would be the slight inundation of lands while the structure is

being operated. During operations lands that would not always be inundate during the period would

become submerged. With this submergence, there would be an opportunity for the lands to collect

sediments that would be carried by the diverted Mississippi River water, thus renewing historic deltaic

processes.

The indirect impact of the diversion of water into the project area would be a very small decrease in the

flow in the Mississippi River. The small decrease in flow at this intake location should have no impact on

water levels in the Mississippi River, particularly during typical spring discharge.

5.2.1.2.3 Cumulative

Cumulative impacts would be the synergistic and combined effect of the 5,000 cfs diversion with all past,

present, and reasonably foreseeable activities causing changes to or maintaining hydrology in and around

the project area.

Operations of the White Ditch structure would need to be done in concert with the existing Caernarvon

diversion, as well as the proposed CWPPRA project for the rehabilitation and expansion of the existing

siphon at White Ditch. Coordinated operations of all structures would be necessary to optimize potential

benefits within the Breton Sound Basin.

The proposed Myrtle Grove diversion, which if constructed would be directly across the river from the

proposed White Ditch structure could have cumulative effects with the 5,000 cfs diversion. The

combination of the two structures working in proximity to each other on opposite sides of the Mississippi

River could potentially create changes in flow patterns. The risk of this is low due to the relatively small

percentage of water actually that would actually be diverted from the river.

Other existing and proposed diversions along the Mississippi River could collectively have impacts on

sediment levels and flows. While many of the projects along the Mississippi River would be considered

small diversions (1005,000 cfs), the collective impacts of the whole assemblage could have effects on

flows and stages. System-wide coordination would be necessary to ensure avoidance of potentially

undesirable impacts. An overall operating plan for diversions would allow beneficial use of the river for

multiple uses and goals.

5.2.1.3 Alternative 2 – 10,000 cfs max Diversion

5.2.1.3.1 Direct

The direct impact of a diversion with the potential of operating up to 10,000 cfs in the area between River

aux Chenes and the Mississippi River would be increased water levels and flows within the project area

while the structure is being operated. During operations, Mississippi River water would flow through

River aux Chenes, Bayou Garelle, and numerous other natural and man-made channels. Flows through

these channels would have velocities similar to those in the 5,000 cfs diversion due to the proposed

channel improvements (i.e. deepening or widening) as described in the Engineering Appendix (Appendix

L). Stages would be elevated near the outfalls of where diverted water is leaving the Bayou Garelle and

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flowing into larger, more open, bodies of water. Results from hydrodynamic modeling yield that these

stages would be higher than those from the 5,000 cfs diversion.

5.2.1.3.2 Indirect

Indirect impacts of a 10,000 cfs diversion would be the slight inundation of lands while the structure is

being operated. During operations these lands would be submerged deeper than the 5,000 cfs diversion.

Lands that would not always be inundated during the period would become submerged. With this

submergence, there would be an opportunity for the lands to collect sediments, more than the 5,000 cfs

diversion, that would be carried by the diverted Mississippi River water, thus renewing historic deltaic

processes.

5.2.1.3.3 Cumulative

Cumulative impacts would be the synergistic and combined effect of the 10,000 cfs diversion with all

past, present, and reasonably foreseeable activities causing changes to or maintaining hydrology in and

around the project area.

Operations of the White Ditch structure would need to be done in concert with the existing Caernarvon

diversion, as well as the proposed CWPPRA project for the rehabilitation and expansion of the existing

siphon at White Ditch. Coordinated operations of all structures would be necessary to optimize potential

benefits within the Breton Sound Basin.

The proposed Myrtle Grove diversion, which if constructed would be directly across the river from the

proposed White Ditch structure could have cumulative effects with the 10,000 cfs diversion. The

combination of the two structures working in proximity to each other on opposite sides of the Mississippi

River could potentially create changes in flow patterns. The risk of this is low due to the relatively small

percentage of water actually that would actually be diverted from the river.

Other existing and proposed diversions along the Mississippi River could collectively have impacts on

sediment levels and flows. While many of the projects along the Mississippi River would be considered

small diversions (1005,000 cfs), the collective impacts of the whole assemblage could have effects on

flows and stages. System-wide coordination would be necessary to ensure avoidance of potentially

undesirable impacts. An overall operating plan for diversions would allow beneficial use of the river for

multiple uses and goals.

5.2.1.4 Alternative 3 – 15,000 cfs max Diversion

5.2.1.4.1 Direct

The direct impact of a diversion with the potential of operating up to 15,000 cfs in the area between River

aux Chenes and the Mississippi River would be increased water levels and flows within the project area

while the structure is being operated. During operations, Mississippi River water would flow through

River aux Chenes, Bayou Garelle, and numerous other natural and man-made channels. Flows through

these channels would have velocities similar to those in the 10,000 cfs diversion due to the proposed

channel improvements (i.e. deepening or widening) as described in the Engineering Appendix. Stages

would be elevated near the outfalls of where diverted water is leaving the Bayou Garelle and flowing into

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larger, more open, bodies of water. Results from hydrodynamic modeling yield that these stages would be

higher than those from the 10,000 cfs diversion.

5.2.1.4.2 Indirect

Indirect impacts of a 15,000 cfs diversion would be the slight excess inundation of lands while the

structure is being operated. During operations these lands would be submerged deeper than those from the

10,000 cfs diversion. Lands that would not always be inundated during the period would become

submerged. With this submergence, there would be an opportunity for the lands to collect sediments,

more than from the 10,000 cfs alternative, that would be being carried by the diverted Mississippi River

water thus renewing historic deltaic processes.

5.2.1.4.3 Cumulative

Cumulative impacts would be the synergistic and combined effect of the 15,000 cfs diversion with all

past, present, and reasonably foreseeable activities causing changes to or maintaining hydrology in and

around the project area.

Operations of the White Ditch structure would need to be done in concert with the existing Caernarvon

diversion, as well as the proposed CWPPRA project for the rehabilitation and expansion of the existing

siphon at White Ditch. Coordinated operations of all structures would be necessary to optimize potential

benefits within the Breton Sound Basin.

The proposed Myrtle Grove diversion, which if constructed would be directly across the river from the

proposed White Ditch structure could have cumulative effects with the 15,000 cfs diversion. The

combination of the two structures working in proximity to each other on opposite sides of the Mississippi

River could potentially create changes in flow patterns. The risk of this is low due to the relatively small

percentage of water actually that would actually be diverted from the river.

Other existing and proposed diversions along the Mississippi River could collectively have impacts on

sediment levels and flows. While many of the projects along the Mississippi River would be considered

small diversions (1005,000 cfs), the collective impacts of the whole assemblage could have effects on

flows and stages. System-wide coordination would be necessary to ensure avoidance of potentially

undesirable impacts. An overall operating plan for diversions would allow beneficial use of the river for

multiple uses and goals.

5.2.1.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.2.1.5.1 Direct

The direct impact of a diversion with the potential of operating up to 35,000 cfs in the area between River

aux Chenes and the Mississippi River would be increased water levels and flows within the project area

while the structure is being operated. During operations, Mississippi River water would flow through

River aux Chenes, Bayou Garelle, and numerous other natural and man-made channels. Flows through

these channels would have velocities similar to those in the 15,000 cfs diversion due to the proposed

channel improvements (i.e., deepening or widening) as described in the Engineering Appendix. Stages

would be elevated across large portions of the project area surrounding the outfalls of where diverted

water is leaving the Bayou Garelle. Results from hydrodynamic modeling yield that these stages would be

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higher than those from the 15,000 cfs diversion. Large areas of the marsh (from approximately 1 mile

south and west of Bayou Garelle and the main outfall channel, extending to the northern extent of the

project boundary, and being contained by the River aux Chenes and Mississippi River ridges) would be

inundated on the order of 0.3 to 0.6 foot during maximum diversion operations. The model indicates that

these areas would quickly drain to the normally inundated extent on the order of 5 to 7 days when

operations would be shifted from maximum flow to the proposed 1,000 cfs maintenance flow at the end

of the MarchApril pulse.

5.2.1.5.2 Indirect

Indirect impacts of a 35,000 cfs diversion would be the slight inundation of lands while the structure is

being operated. During operations these lands would be submerged deeper than those from the 15,000 cfs

diversion. Lands that would not always be inundated during the period would become submerged. With

this submergence, there would be an opportunity for the lands to collect beneficial sediments, more than

from the 15,000 cfs diversion, that would be being carried by the diverted Mississippi River water thus

renewing historic deltaic processes.

5.2.1.5.3 Cumulative

Cumulative impacts would be the synergistic and combined effect of the 35,000 cfs diversion with all

past, present, and reasonably foreseeable activities causing changes to or maintaining hydrology in and

around the project area.

Operations of the White Ditch structure would need to be done in concert with the existing Caernarvon

diversion, as well as the proposed CWPPRA project for the rehabilitation and expansion of the existing

siphon at White Ditch. Coordinated operations of all structures would be necessary to optimize potential

benefits within the Breton Sound Basin.

The proposed Myrtle Grove diversion, which if constructed would be directly across the river from the

proposed White Ditch structure could have cumulative effects with the 35,000 cfs diversion. The

combination of the two structures working in proximity to each other on opposite sides of the Mississippi

River could potentially create changes in flow patterns. The risk of this is low due to the relatively small

percentage of water actually that would actually be diverted from the river.

Other existing and proposed diversions along the Mississippi River could collectively have impacts on

sediment levels and flows. While many of the projects along the Mississippi River would be considered

small diversions (1005,000 cfs), the collective impacts of the whole assemblage could have effects on

flows and stages. System-wide coordination would be necessary to ensure avoidance of potentially

undesirable impacts. An overall operating plan for diversions would allow beneficial use of the river for

multiple uses and goals. See Appendix L for additional information.

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5.2.2 Sedimentation and Erosion

5.2.2.1 No Action Alternative (Future Without Project Conditions)

5.2.2.1.1 Direct

The No Action Alternative, i.e., not implementing a diversion in the White Ditch Study Area, would have

a direct impact on sedimentation and erosion within the area between the Mississippi River and River aux

Chenes through the continuation of existing degradation of marsh. The absence of a supply of freshwater,

sediment, and nutrients combined with the ongoing pressures of wind and wave action, storm surges, and

human activities would continue to erode marsh soils and reduce the ability of the project area to maintain

a balance of emergent wetland and shallow water.

5.2.2.1.2 Indirect

Indirect impacts of the No Action Alternative would result in the persistence of existing conditions.

Consequences would include further degradation of the existing marsh from saltwater intrusion due to

impaired hydrologic processes present in the basin; as well as the continued lack of sediments, nutrients,

and freshwater. With the absences of these processes, the marsh would not be able to sustain itself against

subsidence and prolonged inundation from sea level rise.

The No Action Alternative would cause the marsh to continue with minimal inputs of freshwater,

nutrients, and sediment. The sediment deficit would continue to result in subsidence and a disruption of

natural processes that promote productivity and diversity in the marsh ecosystem. Increases in relative sea

level (i.e., subsidence plus sea level rise) would continue to permanently inundate marsh communities,

which would ultimately lead to substantial losses of acreage.

5.2.2.1.3 Cumulative

Cumulative impacts would be the synergistic and combined effect of the No Action Alternative with all

past, present, and reasonably foreseeable activities causing changes to or maintaining sedimentation and

erosion in and around the project area.

5.2.2.2 Alternative 1 – 5,000 cfs max Diversion

5.2.2.2.1 Direct

The direct impact of a diversion with the potential of operating up to 5,000 cfs in the area between River

aux Chenes and the Mississippi River would be increased availability of freshwater, sediments, and

nutrients. The sediments in the waters would be available to help fill in areas of open water that were

historically marsh. The areas that would receive the most potential benefits from the sediments would be

the open water areas that would be adjacent to the Bayou Garelle. As sediments reach these areas their

velocities begin to decrease and particles would begin to fall out.

Assuming the diversion operated at maximum capacity (5,000 cfs) for 2 months in the spring and 1,000

cfs for the remainder of the year, 74,000 tons of sediment would be expected annually. This amount of

sediment would be beneficial to the project area, but it would not be a sufficient amount to offset the rate

of marsh loss the project area has historically experienced.

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Measures would be taken to prevent erosion of existing features. Restoration of historic ridge features as

well as armoring of necessary channels would be done to prevent degradation of the project area from

erosive hydraulic forces that would result from diverted flows. The sediments that would be deposited

from the diversion would be subject to erosive forces due to their lack of cohesion or consolidation. This

is not deemed as a negative impact, but rather a natural process.

5.2.2.2.2 Indirect

Increased sediment introduction into the project area would result in the filling-in of open water areas

adjacent to the Bayou Garelle. With these areas filling in, there would be more opportunity for SAV to

establish themselves across the project area. As time progress in the project area, these areas would likely

transition from SAVs to emergent vegetation as more sediment is brought into the area.

With the inundation of land from diverted flows, there would be an opportunity for the lands to collect

sediments through overland flow. This process would help established marsh keep pace with the relative

sea level rise by aiding in accretion.

5.2.2.2.3 Cumulative

Cumulative impacts would be the synergistic and combined effect of the 5,000 cfs Alternative with all

past, present, and reasonably foreseeable activities causing changes to or maintaining sedimentation and

erosion in and around the project area.

The Caernarvon Diversion inputs sediments into the Breton Sound Basin. These sediments likely fall out

long before they reach River aux Chenes having no impact on the project area. The CWPPRA project for

the rehabilitation of the existing siphon at White Ditch would have direct sediment introduction into the

project area, specifically in the northern extents.

The proposed Myrtle Grove diversion, which if constructed would be directly across the river from the

proposed White Ditch structure could have cumulative effects with the 5,000 cfs diversion. The

combination of the two structures working in proximity to each other on opposite sides of the Mississippi

River could potentially create changes in sedimentation and erosion patterns. The risk of this is low due to

the relatively small percentage of water actually that would actually be diverted from the river.

Other existing and proposed diversions along the Mississippi River could collectively have impacts on

sedimentation and erosion. While many of the projects along the Mississippi River would be considered

small diversions (1005,000 cfs), the collective impacts of the whole assemblage could have effects on

flows and stages. System-wide coordination would be necessary to ensure avoidance of potentially

undesirable impacts. An overall operating plan for diversions would allow beneficial use of the river for

multiple uses and goals.

5.2.2.3 Alternative 2 – 10,000 cfs max Diversion

5.2.2.3.1 Direct

The direct impact of a diversion with the potential of operating up to 10,000 cfs in the project area would

be increased availability of freshwater, sediments, and nutrients. The sediments in the waters would be

available to help fill in areas of open water that were historically marsh. The areas that would receive

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the most potential benefits from the sediments would be the open water areas that would be adjacent to

the Bayou Garelle. As sediments reach these areas velocities would decrease and particles would fall out.

Assuming the diversion operated at maximum capacity (10,000 cfs) for 2 months in the spring and 1,000

cfs for the remainder of the year, 108,000 tons of sediment would be expected annually. This amount of

sediment would be beneficial to the project area and would be sufficient maintain existing acreage against

the current rate of loss.

Measures would be taken to prevent erosion of existing features. Restoration of historic ridge features as

well as armoring of necessary channels would be done to prevent degradation of the project area from

erosive hydraulic forces that would result from increased velocities of diverted flows. The sediments that

would be deposited from the diversion would be subject to erosive forces due to their lack of cohesion or

consolidation. This is not deemed as a negative impact, but rather a natural process.

5.2.2.3.2 Indirect

Increased sediment introduction into the project area would result in the filling-in of open water areas

adjacent to the Bayou Garelle. This effect would be roughly twice that of the 5,000 cfs diversion

(assuming a MarchApril Pulse). With these areas filling in, there would be more opportunity for SAV to

establish themselves across the project area. As time progress in the project area, these areas would begin

to transition from SAVs to emergent vegetation as more sediment would be brought into the area.

With the inundation of land from diverted flows, there would be an opportunity for the lands to collect

sediments through overland flow. This effect would be roughly twice that of the 5,000 cfs diversion

(assuming similar operational schemes). This process would help established marsh keep up with relative

sea level rise by aiding in accretion.

5.2.2.3.3 Cumulative

Cumulative impacts would be the synergistic and combined effect of the 10,000 cfs Alternative with all

past, present, and reasonably foreseeable activities causing changes to or maintaining sedimentation and

erosion in and around the project area.

The Caernarvon Diversion inputs sediments into the Breton Sound Basin. These sediments likely fall out

long before they reach River aux Chenes having no impact on the project area. The CWPPRA project for

the rehabilitation of the existing siphon at White Ditch would have direct sediment introduction into the

project area, specifically in the northern extents.

The proposed Myrtle Grove diversion, which if constructed would be directly across the river from the

proposed White Ditch structure could have cumulative effects with the 10,000 cfs diversion. The

combination of the two structures working in proximity to each other on opposite sides of the Mississippi

River could potentially create changes in sedimentation and erosion patterns. The risk of this is low due to

the relatively small percentage of water actually that would actually be diverted from the river.

Other existing and proposed diversions along the Mississippi River could collectively have impacts on

sedimentation and erosion. While many of the projects along the Mississippi River would be considered

small diversions (1005,000 cfs), the collective impacts of the whole assemblage could have effects on

flows and stages. System-wide coordination would be necessary to ensure avoidance of potentially

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undesirable impacts. An overall operating plan for diversions would allow beneficial use of the river for

multiple uses and goals.

5.2.2.4 Alternative 3 – 15,000 cfs max Diversion

5.2.2.4.1 Direct

The direct impact of a diversion with the potential of operating up to 15,000 cfs in the project area would

be increased availability of freshwater, sediments, and nutrients. The sediments in the waters would be

available to help fill in areas of open water that were historically marsh. The areas that would receive

the most potential benefits from the sediments would be the open water areas that would be adjacent to

the Bayou Garelle. As sediments reach these areas velocities would decrease and particles would fall out.

Assuming the diversion operated at maximum capacity (15,000 cfs) for 2 months in the spring and 1,000

cfs for the remainder of the year, 143,000 tons of sediment would be expected annually. This amount of

sediment would be beneficial to the project area and would be sufficient maintain existing acreage against

the current rate of loss.

Measures would be taken to prevent erosion of existing features. Restoration of historic ridge features as

well as armoring of necessary channels would be done to prevent degradation of the project area from

erosive hydraulic forces that would result from increased velocities of diverted flows. The sediments that

would be deposited from the diversion would be subject to erosive forces due to their lack of cohesion or

consolidation. This is not deemed as a negative impact, but rather a natural process.

5.2.2.4.2 Indirect

Increased sediment introduction into the project area would result in the filling-in of open water areas

adjacent to the Bayou Garelle. This effect would be roughly three times that of the 5,000 cfs diversion

(assuming a MarchApril Pulse). With these areas filling in, there would be more opportunity for SAV to

establish themselves across the project area. As time progress in the project area, these areas would begin

to transition from SAVs to emergent vegetation as more sediment is brought into the area.

With the inundation of land from diverted flows, there would be an opportunity for the lands to collect

sediments through overland flow. This effect would be roughly three times that of the 5,000 cfs diversion

(assuming similar operational schemes). This process would help established marsh keep up with the

relative sea level rise by aiding in accretion.

5.2.2.4.3 Cumulative

Cumulative impacts would be the synergistic and combined effect of the 15,000 cfs Alternative with all

past, present, and reasonably foreseeable activities causing changes to or maintaining sedimentation and

erosion in and around the project area.

The Caernarvon Diversion inputs sediments into the Breton Sound Basin. These sediments likely fall out

long before they reach River aux Chenes having no impact on the project area. The CWPPRA project for

the rehabilitation of the existing siphon at White Ditch would have direct sediment introduction into the

project area, specifically in the northern extents.

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The proposed Myrtle Grove diversion, which if constructed would be directly across the river from the

proposed White Ditch structure could have cumulative effects with the 15,000 cfs diversion. The

combination of the two structures working in proximity to each other on opposite sides of the Mississippi

River could potentially create changes in sedimentation and erosion patterns. The risk of this is low due to

the relatively small percentage of water actually that would actually be diverted from the river.

Other existing and proposed diversions along the Mississippi River could collectively have impacts on

sedimentation and erosion. While many of the projects along the Mississippi River would be considered

small diversions (1005,000 cfs), the collective impacts of the whole assemblage could have effects on

flows and stages. System-wide coordination would be necessary to ensure avoidance of potentially

undesirable impacts. An overall operating plan for diversions would allow beneficial use of the river for

multiple uses and goals.

5.2.2.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.2.2.5.1 Direct

The direct impact of a diversion with the potential of operating up to 35,000 cfs in the project area would

be increased availability of freshwater, sediments, and nutrients. The sediments in the waters would be

available to help fill in areas of open water that were historically marsh. The areas that would receive

the most potential benefits from the sediments would be the open water areas that would be adjacent to

the Bayou Garelle. As sediments reach these areas velocities would decrease and particles would fall out.

Assuming the diversion operated at maximum capacity (35,000 cfs) for 2 months in the spring and 1,000

cfs for the remainder of the year, 279,000 tons of sediment would be expected annually. This amount of

sediment would be sufficient to exceed the current rate of marsh loss and would have potential to recreate

acreage comparable to that present in the 1950s.

Measures would be taken to prevent erosion of existing features. Restoration of historic ridge features as

well as armoring of necessary channels would be done to prevent degradation of the project area from

erosive hydraulic forces that would result from increased velocities of diverted flows. The sediments that

would be deposited from the diversion would be subject to erosive forces due to their lack of cohesion or

consolidation. This is not deemed as a negative impact, but rather a natural process.

5.2.2.5.2 Indirect

Increased sediment introduction into the project area would result in the filling-in of open water areas

adjacent to the Bayou Garelle. This effect would be roughly seven times that of the 5,000 cfs diversion

(assuming a MarchApril Pulse). With these areas filling in, there would be more opportunity for SAV to

establish themselves across the project area. As time progress in the project area, these areas would begin

to transition from SAVs to emergent vegetation as more sediment is brought into the area.

With the inundation of land from diverted flows, there would be an opportunity for the lands to collect

sediments through overland flow. This effect would be roughly seven times that of the 5,000 cfs diversion

(assuming similar operational schemes). This process would help established marsh keep up with the

relative sea level rise by aiding in accretion.

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5.2.2.5.3 Cumulative

Cumulative impacts would be the synergistic and combined effect of the 35,000 cfs Alternative with all

past, present, and reasonably foreseeable activities causing changes to or maintaining sedimentation and

erosion in and around the project area.

The Caernarvon Diversion inputs sediments into the Breton Sound Basin. These sediments likely fall out

long before they reach River aux Chenes having no impact on the project area. The CWPPRA project for

the rehabilitation of the existing siphon at White Ditch would have direct sediment introduction into the

project area, specifically in the northern extents.

The proposed Myrtle Grove diversion, which if constructed would be directly across the river from the

proposed White Ditch structure could have cumulative effects with the 35,000 cfs diversion. The

combination of the two structures working in proximity to each other on opposite sides of the Mississippi

River could potentially create changes in sedimentation and erosion patterns. The risk of this is low due to

the relatively small percentage of water actually that would actually be diverted from the river.

Other existing and proposed diversions along the Mississippi River could collectively have impacts on

sedimentation and erosion. While many of the projects along the Mississippi River would be considered

small diversions (1005,000 cfs), the collective impacts of the whole assemblage could have effects on

flows and stages. System-wide coordination would be necessary to ensure avoidance of potentially

undesirable impacts. An overall operating plan for diversions would allow beneficial use of the river for

multiple uses and goals.

5.2.3 Water Use and Supply

5.2.3.1 No Action Alternative (Future Without Project Conditions)

5.2.3.1.1 Direct

Under the No Action Alternative no direct impacts to water use and supply of the project area would

occur.

5.2.3.1.2 Indirect

Indirect impacts of not implementing restoration features would result in the persistence of existing

conditions for the Mississippi River and White Ditch project area.

5.2.3.1.3 Cumulative

Cumulative impacts would be the synergistic effect on the No Action Alternative for water use and supply

with the added combination of similar wetland degradation and wetland loss impacts to water use and

supply throughout coastal Louisiana, as well as the benefits and impacts of other state and Federal coastal

restoration projects in the vicinity.

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5.2.3.2 Alternative 1 – 5,000 cfs max Diversion

5.2.3.2.1 Direct

Under the 5,000 cfs diversion, no significant direct impacts to water use and supply of the project area

would occur.

5.2.3.2.2 Indirect

Under the 5,000 cfs diversion, no significant indirect impacts to water use and supply of the project area

would occur.

5.2.3.2.3 Cumulative

Cumulative impacts would be the synergistic effect on the 5,000 cfs diversion for water use and supply

with the added combination of similar wetland degradation and wetland loss impacts to water use and

supply throughout coastal Louisiana, as well as the benefits and impacts of other state and Federal coastal

restoration projects in the vicinity.

5.2.3.3 Alternative 2 – 10,000 cfs max Diversion

5.2.3.3.1 Direct

Under the 10,000 cfs diversion, no direct impacts to water use and supply of the project area would occur.

5.2.3.3.2 Indirect

Under the 10,000 cfs diversion, no indirect impacts to water use and supply of the project area would

occur.

5.2.3.3.3 Cumulative

Cumulative impacts would be the synergistic effect on the 10,000 cfs diversion for water use and supply

with the added combination of similar wetland degradation and wetland loss impacts to water use and

supply throughout coastal Louisiana, as well as the benefits and impacts of other state and Federal coastal

restoration projects in the vicinity.

5.2.3.4 Alternative 3 – 15,000 cfs max Diversion

5.2.3.4.1 Direct

Under the 15,000 cfs diversion, no direct impacts to water use and supply of the project area would occur.

5.2.3.4.2 Indirect

Under the 15,000 cfs diversion, no indirect impacts to water use and supply of the project area would

occur.

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5.2.3.4.3 Cumulative

Cumulative impacts would be the synergistic effect on the 15,000 cfs diversion for water use and supply

with the added combination of similar wetland degradation and wetland loss impacts to water use and

supply throughout coastal Louisiana, as well as the benefits and impacts of other state and Federal coastal

restoration projects in the vicinity.

5.2.3.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.2.3.5.1 Direct

Under the 35,000 cfs diversion, no direct impacts to water use and supply of the project area would occur.

5.2.3.5.2 Indirect

Under the 35,000 cfs diversion, no indirect impacts to water use and supply of the project area would

occur.

5.2.3.5.3 Cumulative

Cumulative impacts would be the synergistic effect on the 35,000 cfs diversion for water use and supply

with the added combination of similar wetland degradation and wetland loss impacts to water use and

supply throughout coastal Louisiana, as well as the benefits and impacts of other state and Federal coastal

restoration projects in the vicinity.

5.2.4 Groundwater

5.2.4.1 No Action Alternative (Future Without Project Conditions)

5.2.4.1.1 Direct

Under the No Action Alternative no direct impacts to groundwater of the project area would occur.

5.2.4.1.2 Indirect

Under the No Action Alternative no indirect impacts to groundwater of the project area would occur.

5.2.4.1.3 Cumulative

Cumulative impacts would be the synergistic effect of the No Action Alternative on groundwater with the

added combination of similar wetland degradation and wetland loss impacts to groundwater, as well as

the benefits and impacts of other state and Federal coastal restoration projects in the vicinity. No

cumulative impacts would be anticipated.

5.2.4.2 Alternative 1 – 5,000 cfs max Diversion

5.2.4.2.1 Direct

Under the 5,000 cfs diversion, no direct impacts to groundwater of the project area would occur.

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5.2.4.2.2 Indirect

Under the 5,000 cfs diversion, no indirect impacts to groundwater of the project area would occur.

5.2.4.2.3 Cumulative

Cumulative impacts would be the synergistic effect of the 5,000 cfs diversion on groundwater with the

added combination of similar wetland degradation and wetland loss impacts to groundwater, as well as

the benefits and impacts of other state and Federal coastal restoration projects in the vicinity. No

cumulative impacts would be anticipated.

5.2.4.3 Alternative 2 – 10,000 cfs max Diversion

5.2.4.3.1 Direct

Under the 10,000 cfs diversion, no direct impacts to groundwater of the project area would occur.

5.2.4.3.2 Indirect

Under the 10,000 cfs diversion, no indirect impacts to groundwater of the project area would occur.

5.2.4.3.3 Cumulative

Cumulative impacts would be the synergistic effect of the 10,000 cfs diversion on groundwater with the

added combination of similar wetland degradation and wetland loss impacts to groundwater, as well as

the benefits and impacts of other state and Federal coastal restoration projects in the vicinity. No

cumulative impacts would be anticipated.

5.2.4.4 Alternative 3 – 15,000 cfs max Diversion

5.2.4.4.1 Direct

Under the 15,000 cfs diversion, no direct impacts to groundwater of the project area would occur.

5.2.4.4.2 Indirect

Under the 15,000 cfs diversion, no indirect impacts to groundwater of the project area would occur.

5.2.4.4.3 Cumulative

Cumulative impacts would be the synergistic effect of the 15,000 cfs diversion on groundwater with the

added combination of similar wetland degradation and wetland loss impacts to groundwater, as well as

the benefits and impacts of other state and Federal coastal restoration projects in the vicinity. No

cumulative impacts would be anticipated.

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5.2.4.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.2.4.5.1 Direct

Under the 35,000 cfs diversion, no direct impacts to groundwater of the project area would occur.

5.2.4.5.2 Indirect

Under the 35,000 cfs diversion, no indirect impacts to groundwater of the project area would occur.

5.2.4.5.3 Cumulative

Cumulative impacts would be the synergistic effect of the 35,000 cfs diversion on groundwater with the

added combination of similar wetland degradation and wetland loss impacts to groundwater, as well as

the benefits and impacts of other state and Federal coastal restoration projects in the vicinity. No

cumulative impacts would be anticipated.

5.3 WATER QUALITY AND SALINITY

5.3.1 Water Quality

5.3.1.1 No Action Alternative (Future Without Project Conditions)

5.3.1.1.1 Direct

Under the No Action Alternative, no diversion of river water and no input of river sediments and nutrients

would occur in the MDWD project area. None of the potential negative effects of river inflows to this

portion of the Breton Sound Basin would result; however, the project area would continue to be isolated

from natural riverine processes critical to maintaining functioning and sustainable coastal wetlands and

estuaries.

5.3.1.1.2 Indirect

The most notable indirect impact from no action is the ongoing erosion/subsidence and land loss of the

coastal areas. This would continue to expose the pipelines of the expansive oil and gas infrastructure

along the coast of Louisiana. This would be a precarious situation, especially during storm events and

within navigable waterways. Exposed pipelines would be vulnerable to navigation vessels striking them,

which could lead to discharges into waters of the project area. In the event of discharges, extensive

ecological damage would probably occur. The owner(s) of the infrastructure could incur expensive fines

and cleanup costs; and vessel operators could be seriously injured. There would be other forms of

infrastructure that could potentially be exposed due to coastal erosion including wastewater collection

systems and other commercial industry related systems.

5.3.1.1.3 Cumulative

Without the proposed actions of White Ditch Medium Diversion Project the Breton Sound Basin would

still be affected by activities, natural and man-influenced, that would have both beneficial and detrimental

effects to water quality conditions. Some of these activities include: other Federal, state, local, and private

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restoration efforts such as CWPPRA, USACE ecosystem restoration projects, various NRCS programs

(e.g., Coastal Wetlands Restoration Program), and CPRA projects; state and local water quality

management programs; national level programs to address hypoxia in the northern Gulf of Mexico; the

continued erosion/subsidence of the coast; oil and gas development; industrial, commercial, and

residential development; and Federal, state, and municipal navigation and flood-damage reduction

projects. There would be a number of present and future activities that would continue to occur without

the proposed actions of the LCA Plan and would affect surface water quality conditions within the White

Ditch Project Area. The cumulative impact of these activities without the LCA Plan is discussed below.

Passage of the Federal Water Pollution Control Act (FWPCA) in 1948 and its amendments including the

CWA and the Water Quality Act of 1987 and the establishment of state and Federal environmental

protection agencies resulted in water pollution control regulations, including:

 The National Pollutant Discharge Elimination System (NPDES) permit program controls water

pollution. In 1997 the USEPA granted NPDES delegation to LDEQ, which is known as the

Louisiana Pollutant Discharge Elimination System (LPDES).

 LDEQs Nonpoint Source Pollution Program is continuing to implement watershed initiatives to

address nonpoint source pollution sources such as agriculture, home sewage treatment, hydro

modification, urban runoff, construction activities, and resource extraction.

 LDNRs Coastal Nonpoint Pollution Program is responsible for identifying Best Management

Practices (BMPs) appropriate for all applicable pollutant source categories and carrying out

initiatives of public education, technical assistance, and development of enforcement protocols.

 Total Maximum Daily Loads (TMDLs)  Section 303(d) of the CWA requires states to identify,

list, and rank for development of TMDLs waters that do not meet applicable water quality

standards after implementation of technology-based controls.

The programs discussed above would continue to develop or remain in place with or without MDWD

project features to ensure protection of Louisianas public health and natural resources. Water quality

conditions would likely improve with the programs in place. However, some activities that could

potentially have negative effects on water quality would also continue to occur with or without the

proposed MDWD Plan. Other efforts that would probably improve water quality conditions would be the

present and future Federal, state, local, and private ecosystem restoration projects.

Industrial, commercial, and residential development along the coast could contribute to adverse impacts

to water quality within the MDWD project area. With this activity comes increased point and nonpoint

source pollution from sources such as wastewater treatment facilities and urban runoff from new

development. Also, activities associated with maintaining and improving navigation along the coast

would continue to occur.

Flood-damage reduction projects would continue to be planned, designed, and constructed especially in

areas highly susceptible to flood damages due to hurricanes and tropical storm events. With these

activities, more alterations to the hydrology of the coast would potentially occur leading to areas of

degraded water quality. Some projects, such as the Southeast Louisiana Urban Flood Control Project,

would be providing flood protection for a 10-year rainfall event. However, this is also increasing the flow

of urban runoff that is diverted into Lake Pontchartrain and other surrounding water bodies without

providing pollutant reduction measures as seen in many stormwater collection systems across the nation.

Unfortunately, metro New Orleans unique geographic setting does not allow for incorporating many

pollutant reduction methods; however, the NPDES Storm Water Program and the continued development

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of TMDLs could require stormwater professionals to find innovative methods, such as subsurface

structural BMP to drain the populated areas effectively while protecting the receiving water bodies as

much as practicable. Adverse impacts to water quality by these Federal projects would be mitigated as

legally mandated.

5.3.1.2 Alternative 1 – 5,000 cfs max Diversion

5.3.1.2.1 Direct

The direct impacts of this alternative would have the similar effects as the 35,000 cfs diversion, but they

would be on a lesser scale due to the amount of water being diverted.

5.3.1.2.2 Indirect

The indirect impacts of this alternative would have the similar effects as the 35,000 cfs diversion, but they

would be on a lesser scale due to the amount of water being diverted.

5.3.1.2.3 Cumulative

The cumulative impacts of this alternative would have the similar effects as the 35,000 cfs diversion, but

they would be on a lesser scale due to the amount of water being diverted.

5.3.1.3 Alternative 2 – 10,000 cfs max Diversion

5.3.1.3.1 Direct

The Direct impacts of this alternative would have the similar effects as the 35,000 cfs diversion, but they

would be on a lesser scale due to the amount of water being diverted.

5.3.1.3.2 Indirect

The indirect impacts of this alternative would have the similar effects as the 35,000 cfs diversion, but they

would be on a lesser scale due to the amount of water being diverted.

5.3.1.3.3 Cumulative

The cumulative impacts of this alternative would have the similar effects as the 35,000 cfs diversion, but

they would be on a lesser scale due to the amount of water being diverted.

5.3.1.4 Alternative 3 – 15,000 cfs max Diversion

5.3.1.4.1 Direct

The Direct impacts of this alternative would have the similar effects as the 35,000 cfs diversion, but they

would be on a lesser scale due to the amount of water being diverted.

5.3.1.4.2 Indirect

The indirect impacts of this alternative would have the similar effects as the 35,000 cfs diversion, but they

would be on a lesser scale due to the amount of water being diverted.

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5.3.1.4.3 Cumulative

The cumulative impacts of this alternative would have the similar effects as the 35,000 cfs diversion, but

they would be on a lesser scale due to the amount of water being diverted.

5.3.1.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.3.1.5.1 Direct

In general, river diversions could cause short- to long-term adverse impacts due to construction of

restoration features including: increased total suspended sediments, turbidity, and organic/nutrient

enrichment of the water column; disturbance and release of possible contaminants; decrease in water

temperatures; and the possible release of oxygen depleting substances (organic or anaerobic sediments) as

well as possibly decreasing dissolved oxygen (DO) levels. Note that many of the direct impacts could also

be indirect effects (see below). These impacts would be minimized, as much as practicable, through the

implementation of stormwater pollution prevention plans (SWPPPs), the ITM protocols, and other

applicable best management practices (BMPs).

Generally, four water quality conditions could change with implementation of the proposed restoration

alternative. The four water quality conditions that would change include:

1. Freshwater would be moved throughout the entire MDWD project area;

2. Salinities would decrease throughout the entire project area, especially during and after the

months of maximum diversion;

3. Sediments in the project area would increase allowing the maximum amount of marsh creation of

all the alternatives, along with accompanying minor increases in trace metals associated with

suspended and bed sediments; and

4. Agrochemicals/Nutrients in the project area could increase.

Introduction of river water into the Breton Sound Basin would immediately change the water chemistry of

receiving areas. Change could be beneficial or detrimental, depending the water uses. The change from a

less fresh to a fresher system could be perceived as beneficial to wetland nourishment, but detrimental to

recreational use because of water color changes, and possible changes in fish species assemblages.

However, the changes in water chemistry would mimic what occurred naturally prior to the construction

of levees.

Data has been collected from the Mississippi River at the Luling Water Plant Collection Site, Site WSS 1,

coordinates N 29.56.076, W 90.21.602, for the Davis Pond Diversion project. This data has been

reviewed with respect to nutrients and atrazine, and an estimated load was calculated based on the TSP of

35,000 CFS for the months of March and April along with the loads associated with a 1,000 CFS

diversion for the rest of the months of the year. This data captures the estimated average Mississippi River

water quality for the 10 years that data has been collected for Total Nitrogen and Total Phosphate. The

estimated Atrazine loads were calculated on data that was collect from the years 2001 through 2008;

however, during 2005 there was no Atrazine data collected and for the years prior to 2001 the observed

values were below the detection limit of the laboratory. Table 5.1 shows the estimated average total load

per month. The anticipated loads to the project area are estimated values due to the fact that daily values

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were not collected, so a monthly value was used for the calculations. During PED, more data will be

collected in the project area and analyzed. See Section 3.8.8 for more details.

Table 5.1: Estimated Average Total Load (Tonnes)/Month

Month Total Nitrogen Total Phosphate Total Atrazine

January 169 20 35.4

February 179 15 53.7

March 6927 712 1954.6

April 8131 517 2490.5

May 195 18 78.2

June 225 19 79.1

July 196 22 58.0

August 192 16 66.0

September 137 18 53.1

October 96 16 49.3

November 136 15 48.6

December 159 13 48.7

Total per year 16742 1401 5015.2

Load (mg) = mg/L x (L/ft3) x (ft3/sec) x (secs/day) x days

There could be potential chemical effects due to either an increase or decrease in the methylation of

mercury. The potential for increase in mercury methylation would occur during the initial construction of

the structure, the outfall canals and the creation of new wetlands due to sediment disturbance. This would

be a short term adverse impact. Reintroduction of river water could increase the risk of conditions

favorable to the causes of methylation by changing the levels of dissolved organic carbon and changing

the pH of the water. This would be a potential long term adverse impact. At the same time the increased

sediment load would trap mercury in the soil as new marsh is created by the diversion as well as the

accumulation of the mercury in the plants would be a long term positive impact.

The reintroduction of streambed sediments into the MDWD project area could add some contaminants;

these could include primarily trace metals and hydrophobic organic compounds from Mississippi River

streambed sediments. Trace metals and hydrophobic organic compounds such as pyrenes,

hexachlorobenzene, and chlorinated hydrocarbons such as DDT, or its degradates, would adsorb onto

sediment particles or the organic coatings of sediment particles (Demas and Demcheck 2003).

5.3.1.5.2 Indirect

Indirect effects of changes to water quality could include: nutrient enrichment possibly leading to

increased algae blooms and freshwater tolerant aquatic organisms; increased turbidity leading to

disruption of freshwater and marine organisms; decreased water temperatures; increased DO; freshwater

areas would increase thereby providing additional habitats for aquatic organisms; salinities would

stabilize or decrease; sediments in the coastal zone would increase, with accompanying minor increases in

trace metals associated with bed sediments; and agrichemicals in the water could increase.

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A model of nitrate-nitrogen retention by wetlands in the Mississippi River Basin was developed

combining 24 wetland-years of nitrate-nitrogen data from Ohio and Louisiana with nitrate reduction data

from another 26 wetland-years of data from additional wetlands in Ohio, Illinois and Louisiana (Phipps

and Crumpton, 1994; Kovacic et al., 2000; Lane et al., 2002; Fink and Mitsch, 2004; Mitsch and Day, in

press). The study shows that wetlands in their study area in Louisiana have an average retention of 46 g-N

per square meter per year. All of these studies received either Mississippi River diversion water or

agricultural runoff. The wetland would be expected to reduce nutrient concentrations by about 45%

(William J. Mitsch, et al.). There are approximately 56,000 acres (226,622,200 square meters) of wetlands

in the MDWD study area. Table 5.2 shows the estimated residual nitrogen in the water in wetlands in the

study area. Hydraulic modeling results show that some of the diversion water would pass through the

ridge into the extended influence boundary. From this we can infer that some of the remaining nitrogen

would be taken up by the wetlands in that area. The hydraulic model also shows that some of the water

would also flow south in to America Bay and Brenton Sound.

Table 5.2: Estimated Residual N After Wetland Uptake

Month

Estimated Avg.

Total Load N

input water (g-N)

Grams-N/Square

Meter wetlands

in Study Area

Potential Uptake of

Wetlands

(g-N/m2 month)

Residual N in

Water

(g-N/m2 month)

January 169,000,000 0.75 3.83 0

February 179,000,000 0.79 3.83 0

March 6,927,000,000 30.57 3.83 26.73

April 8,131,000,000 35.88 3.83 32.05

May 195,000,000 0.86 3.83 0

June 225,000,000 0.99 3.83 0

July 196,000,000 0.86 3.83 0

August 192,000,000 0.85 3.83 0

September 137,000,000 0.60 3.83 0

October 96,000,000 0.42 3.83 0

November 136,000,000 0.60 3.83 0

December 159,000,000 0.70 3.83 0

Total per year 16,742,000,000 73.88 46.00 g-N/m2 year 27.88 g-N/m2 year

The uptake of nutrients by wetland plants and sediments would lower the potential for eutrophication of

waters in the study area. In addition, long term experience with the operation of the Caernarvon and Davis

Pond freshwater diversion structures indicates that the operation of these projects has not been related to

eutrophication and fish kills. In 2010 the State of Louisiana operated both of these structures near their

maximum capacity for an extended period, contributing greatly to freshening their respective receiving

areas with river water. During this time period there were no eutrophication issues or fish kills related to

this operation.

At a pulse flow rate of 35,000 cfs at White Ditch, river water would displace the water in the White Ditch

receiving area. During these maximum pulse diversions, conditions would not be conducive for algae

bloom formation because water movement would keep suspended material in the water column, inhibiting

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light penetration. Also, water temperatures would not be at their peak in March and April. After flow is

reduced to 1,000 cfs, the potential for algae blooms would increase. However, this would be similar to the

conditions that occurred in summer 2010 in the Caernarvon and Davis Pond receiving areas after the flow

rates for those structures were reduced to minimum levels.

Monitoring and management of the MDWD project through adaptive management would help to ensure

that operation of the project would minimize the potential for algae blooms and eutrophication of the

receiving waters. Coordination with LDEQ, USEPA, and other stakeholders would also contribute to

minimizing impacts to receiving waters.

This nutrient pulse from the diversion and the associated reduction would have a direct influence on

increased plant production within the project area. A concept of nutrient potential energy is used to

describe the energy or nutrition available to potentially support biomass production per unit area of

marsh. The analysis generates an estimate of the maximum biomass production that can be expected in a

given marsh type (e.g., fresh, brackish, or salt) from the nutrients available in a volume of water from a

given water source (Boustany, Ronald G.). This analysis is part of the ERDC-SAND2 model that was

used to identify the potential of the diversion to create marsh. For more information on this model and

how it was used, see sections 3.3.4.1, 3.5.4.2, 3.5.4.3, 3.8.2, 3.8.3, and Appendix L.

Estimated atrazine loads were calculated (Table 5.2) based on the Recommended Plan. There are no

direct ways to calculate the impacts to water quality associated with the estimated loads into the Breton

Sound Basin. However research performed at the University of South Carolina found the following:

The fate and transport of pesticides in aquatic systems are facilitated to a large degree by physical,

biological and chemical processes such as oxidation, sorption, volatilization, microbial degradation and

photolysis. Atrazine, a preemergent triazine herbicide has the potential to persist in the environment due

to its slight water solubility and long half-life. Deethylatrazine (DEA) and deisopropylatrazine (DIA), the

two major microbial breakdown products, have been measured extensively in surface and groundwater.

The biodegradation of atrazine was monitored in sediments collected from coastal South Carolina by

examining the distribution into three chemical fractions over time. Due to sorption to sediment organic

matter after 80 days only 5070% of the total added atrazine was recovered. Of this, between 20 and 30%

of the activity measured was associated with the aqueous fraction indicating degradation to more watersoluble metabolites. Another 2050% of the remaining activity, depending on site, was associated with

the basic fraction indicative of sorption of atrazine and/or its metabolites to sediment organic matter.

These results suggest that degradation and sorption account for the fate of greater than 80% of the

atrazine recovered in these coastal sediments (Kelly L. Smalling and C. Marjorie Aelion).

Similar results are anticipated to occur within the project area based on the estimated atrazine loads

calculated to enter the project based on the operations of the Recommended Plan. However the fate would

be dependent on the actual load into the project area and the retention time of the diversion within the

project area. Furthermore in the article Atrazine Fate Processes in a Constructed Emergent marsh 1998

research updates, it is stated that restoration or creation of wetlands adjacent to rivers has been proposed

as a means of treating agricultural runoff and protecting downstream surface waters from the effects of

non-point pollutants (Detenbeck et al.).

Although the water quality impacts associated with the predicted atrazine loads into Breton Sound cannot

be directly calculated, the risk of adverse ecological impacts attributable to the atrazine loading is

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anticipated to be low. EPA has developed draft ambient water quality criteria for atrazine for the

protection of aquatic life through its authority under section 304(a) of the Clean Water Act (CWA). These

water quality criteria are guidance for Sates and Tribes and in themselves have no binding legal effect.

The criteria may form the basis for State and Tribal water quality standards and in turn become

enforceable through National Pollutant Discharge Elimination System (NPDES) permits or other

environmental programs. The EPA has identified 10 to 20 ppb as a level of ecological concern as part of

the corn and sorghum monitoring program. Maximum atrazine concentrations in the Mississippi River are

less than 3 ppb, lower than not only the ecological level of concern but also the Maximum Contaminant

Level for atrazine under the Safe Drinking Water Act (33 U.S.C. section 300f et seq.). Therefore it is not

predicted at this time that the projects operation will elevate atrazine concentrations to levels that could

cause adverse impacts.

Reduction in salinities could improve water quality by reducing chelating potential of metals since total

dissolved solids would be decreased. Also, reduction in salinity would decrease temperature variations in

the fresher waters. It should be noted that there has been some discussion in the scientific community of

the potential for negative effects due to Mississippi River diversions introducing excessive amounts of

nutrients. However, monitoring and management through the adaptive management approach would be

necessary to ensure that proper assimilation is occurring in the receiving areas. Coordination with LDEQ,

USEPA, and other stakeholders would be necessary to ensure the applicable water bodies would be

protected.

5.3.1.5.3 Cumulative

The introduction of agrochemicals into the MDWD project area would be a management issue.

Agricultural chemicals, primarily herbicides and fertilizers, would be introduced into the area from the

Mississippi River system. These agricultural chemicals would then be further distributed into portions of

the basin via the Caernarvon diversion. This input of agrochemicals, known as the spring flush, would be

further distributed, to varying degrees, into the Breton Sound Basin area. Adaptive management would be

important in addressing this issue. A water quality concern would be the herbicide atrazine, which is

known to have endocrine disruption effects. The overall effect of this herbicide on the project area would

be unknown. Acute effects, such as marsh plant death would not occur, as evidenced by plants in Breton

Sound Basin that are presently exposed to atrazine-laced water from the Mississippi River, with no

readily obvious detrimental effects. The fertilizers in the spring flush would have both beneficial and

detrimental effects, depending on site-specific areas. In review of nutrient data collected by the USGS

from the years 1999 to present it is shown that the highest nutrient loads based on data published in U.S.

Geological Survey Open-File Report 2007-1080 at the Mississippi River near St. Francisville, Louisiana

(Station ID 07373420) are during the months of March through June. There are slight variations through

the years that can be attributed to differences in rainfall and the timing of application of agrochemicals in

the upper Mississippi River Basin. Also in reviewing the Caernarvon Freshwater Diversion Structure

Hydrologic, Water, and Sediment Quality Monitoring Program 1994 post construction Report, Dated

September 1995, it is noted that albeit at a lesser diversion rate there was no significant degradation of

water quality or impairment of designated uses in the receiving area such as fish kills or eutrophication.

These nutrients would be strongly implicated in the formation of the hypoxic zone off the mouth of the

Mississippi River; however a diversion of this magnitude could aid in reducing the size or duration of the

gulf hypoxic zone. But, the reintroductions could have the potential to contribute to eutrophication within

the Breton Sound Basin. There would be a monitoring plan developed that would monitor not only

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nutrients but also metals, agrochemicals and dissolved oxygen for three years prior to construction and ten

years after construction to adequately gauge the water quality impacts in the basin. Monitoring efforts and

adaptive management actions would be key to addressing and controlling the effects of the diversion

pulses into the MDWD project area.

Implementing the MDWD, the Breton Sound Basin and Subprovince 1 would be affected by other

activities and programs that would cumulatively have both beneficial and detrimental effects on water

quality conditions. Some of these past, present, and foreseeable future activities include state and local

water quality management programs; oil and gas development; industrial, commercial, and residential

development; and Federal, state, and local navigation and flood-damage reduction projects.

Management officials should consider these other activities, and ensure that all activities including the

other LCA projects complement each other. This is critical to ensure the protection of Louisianas coastal

waters and the health of the public that utilizes these waters.

The LDEQ TMDL program is an example of a present program that would be affected by the

implementation of some LCA Plan project elements. Consequently, the incremental impact of both would

affect water quality conditions. Section 303(d) of the CWA requires the state to identify, list, and rank for

development of TMDLs waters that do not meet applicable water quality standards after implementation

of technology based controls. Other programs that could be affected by the MDWD and, simultaneously,

cumulatively impact water quality conditions include LDEQs LPDES program, LDEQs Nonpoint

Source program, LDNRs Coastal Nonpoint Source program and others.

The direct and indirect impacts discussed previously would cumulatively impact water quality conditions

along with other coastal activities. The proposed diversion could independently elevate water quality

constituents such as nutrients and sediment in receiving areas. Other activities such as development would

potentially increase point and nonpoint source pollution in the same water bodies, therefore, causing a

cumulative effect. However, continued state and Federal programs tasked with regulating water quality

impacts would benefit the same water bodies. It is not possible to quantify the effects to the Breton Sound

Basin and Subprovince 1 from all of the coastal activities; however, during the project implementation

phase testing and analysis would be conducted to better assess the effects.

In summation the cumulative impacts to water quality would primarily be related to the incremental

impact of all past, present, and future actions effecting water quality within the Basin such as:

 Increase in freshwater areas;

 Stabilization or decrease in salinities;

 Increase in sediment introduction to the coastal zone, with accompanying minor increases in trace

metals associated with bed sediments;

 Increase in agrichemicals in the water;

 Increased total suspended sediments;

 Increased turbidity;

 Increased organic/nutrient enrichment of the water column;

 Disturbance and release of possible contaminants;

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 Decrease in water temperatures along with fewer water temperature fluctuations; and

 Less potential for chelating metals due to reduced total dissolved solids.

However the cumulative impacts to the water quality of the Breton Sound Basin from this alternative

would be a synergistic positive result over and above the additive combination of impacts and benefits of

the other alternatives.

5.3.2 Salinity

5.3.2.1 No Action Alternative (Future Without Project Conditions)

5.3.2.1.1 Direct

Under the No Action Alternative no direct impacts to salinity levels of the project area would occur.

5.3.2.1.2 Indirect

Indirect impacts of no action would be the persistence of existing conditions and continued degradation of

the White Ditch project area with respect to increasing salinities over time. Over the 50-year planning

horizon, baseline salinity values of 4.4 ppt in the intermediate marsh zone would be anticipated to

increase to approximately 5.0 ppt, the baseline of 6.6 ppt in the brackish marsh zone would be expected to

increase to approximately 8.0 ppt, and the saline zone baseline of 13.0 ppt would increase to

approximately 15.0.

5.3.2.1.3 Cumulative

Cumulative impacts would be the synergistic effect of the No Action Alternative on salinity levels when

considered in context with all past, present, and reasonably foreseeable acts of nature and/or the actions

private entities, state government, and Federal Government. The No Action Alternative would contribute

in a negative manner to the cumulative effects on salinity experienced by most marsh areas in Southern

Louisiana.

5.3.2.2 Alternative 1 – 5,000 cfs max Diversion

5.3.2.2.1 Direct

Year-long hydrological model simulations were performed to determine salinity changes resulting from

diversion operation. Model runs consisted of a MarchApril open operation (i.e., pulse up to 35,000 cfs)

(Figure 5.2) and maintenance flow (i.e., 1,000 cfs) (Figure 5.3) for the MayFebruary period. Flows for

the Caernarvon Structure were set to yearly averages. During the MarchApril open operation period,

model results indicated that the fresh-intermediate and brackish zones would become completely fresh

and the saline marsh zone would average approximately 1 ppt.

In the fresh marsh areas salinities would remain at 0 ppt during the 2-month pulse and for approximately

2 months afterwards. During the rest of the growing season, salinities would range up to 1.5 ppt. An

overall mean salinity during the growing season was calculated to be approximately 0.5 ppt, which is

within the optimal range for fresh marsh. Based on the modeling results, a portion of the existing

intermediate marsh area would convert to fresh marsh.

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The intermediate marsh area is projected to be at 0 ppt during the 2-month pulse and for approximately 1

month afterwards. Salinities begin to increase during the maintenance flow period resulting in a mean

salinity during the growing season of 1.6 ppt.

For the brackish area, salinities are projected to be 0 ppt during the 2-month pulse, increase to 2 ppt in the

following month, and 4 ppt the next month. Salinities are projected to average approximately 6.6 ppt

during the remainder of the year, resulting in a mean annual salinity of 5 ppt.

For the saline area, salinities are projected to average near 1 ppt during the 2-month pulse, then increase

to 5 ppt in the following month and 10 ppt in the next month, and average approximately 13 ppt during

the remainder of the year. Mean annual salinity would be approximately 10 ppt.

Operation and management measures could work toward establishing target zones for optimum marsh

type production throughout the project area. Of the implementation alternatives considered, the 5,000 cfs

diversion would have the least amount of flexibility in terms of controlling and manipulating the salinity

regime. Consequently, it would present the least amount of options for adaptive management.

5.3.2.2.2 Indirect

Indirect impacts of implementing restoration features into the project area would be the possible

permanent transition of marsh types. These changes could have short term consequences, such as

displacement of one type of marsh vegetation by another, but have long term benefits by providing a

sustainable marsh and delta forming functions. Based on a review of hydrologic modeling output, which

provided predicted salinities across the project area, it was determined that a portion of the intermediate

marsh area would transition to fresh marsh. The transition line from fresh to intermediate was determined

by reviewing the salinity modeling results and reviewing habitat data for the Caernarvon Diversion outfall

area to determine the range of fresh marsh in the outfall area. The fresh-intermediate marsh boundary was

delineated at the approximate 1.0 ppt isohaline. Based on the modeling results, it was assumed that the

intermediate-brackish and brackish-saline marsh boundaries would remain as shown on the 2001 Coastal

Marsh Vegetative Type Map.

5.3.2.2.3 Cumulative

Cumulative impacts would be the synergistic effect of the 5,000 cfs Alternative on salinity levels when

considered in context with all past, present, and reasonably foreseeable acts of nature and/or the actions

private entities, state government, and Federal Government. The operations of the Caernarvon Diversion,

the CWPPRA rehabilitation of the existing White Ditch Siphon, and the proposed White Ditch structure

would need a coordinated operations effort to manage salinity levels throughout the Breton Sound Basin.

5.3.2.3 Alternative 2 – 10,000 cfs max Diversion

5.3.2.3.1 Direct

Salinity levels within the White Ditch project area would be affected. Significant freshening of the project

area as well as the entire Breton Sound Basin would occur with maximum operations of the structure.

Since all build alternatives completely freshen the Breton Sound, anticipated salinity changes are the

same as described in Section 5.3.2.2.1. Operation and management measures could work toward

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Figure 5.2: Modeled Salinities Following Maximum Diversions at White Ditch and Caernarvon – Approximately May 1st UnderOur Proposed Operational Scheme

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Figure 5.3: Modeled Salinities Two Months After Maximum Diversions at White Ditch and Caernarvon – Approximately July1st Under Our Proposed Operational Scheme

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establishing target zones for optimum marsh type production throughout the project area. Of the

implementation alternatives considered, the 10,000 cfs diversion would have more flexibility in terms of

controlling and manipulating the salinity regime than the 5,000 cfs but less than the 15,000 cfs.

5.3.2.3.2 Indirect

Indirect impacts of implementing restoration features into the project area would be the possible

permanent transition of marsh types. These changes could have short-term consequences, such as

displacement of one type of marsh vegetation by another, but have long-term benefits by providing a

sustainable marsh and delta forming functions. Indirect impacts to marsh zones of the 10,000 cfs

alternative would be anticipated to be as described in Section 5.3.2.2.2 under the proposed operating plan;

however, the operations of the Caernarvon Diversion, the CWPPRA rehabilitation of the existing White

Ditch Siphon, and the proposed White Ditch structure would need a coordinated operations effort to

manage salinity levels throughout the Breton Sound Basin. With these structures running concurrently for

an extended period of time, there could be undesired consequences in the Breton Sound.

5.3.2.3.3 Cumulative

Cumulative impacts would be the synergistic effect of the 10,000 cfs Alternative on salinity levels when

considered in context with all past, present, and reasonably foreseeable acts of nature and/or the actions

private entities, state government, and Federal Government. The operations of the Caernarvon Diversion,

the CWPPRA rehabilitation of the existing White Ditch Siphon, and the proposed White Ditch structure

would need a coordinated operations effort to manage salinity levels throughout the Breton Sound Basin.

5.3.2.4 Alternative 3 – 15,000 cfs max Diversion

5.3.2.4.1 Direct

Under the 15,000 cfs diversion, direct impacts to salinity levels in the Mississippi River would not occur.

The proposed operating plan would result in the diversion only operating at maximum flows during

spring flood pulses. There would be no salt wedge intrusion from the gulf during this time.

Salinity levels within the White Ditch project area would be affected. Significant freshening of the project

area as well as the entire Breton Sound Basin would occur with maximum operations of the structure.

Since all build alternatives completely freshen the Breton Sound, anticipated salinity changes are the

same as described in Section 5.3.2.2.1. Operation and management measures could work toward

establishing target zones for optimum marsh type production throughout the project area. Of the

implementation alternatives considered, the 15,000 cfs diversion would have more flexibility in terms of

controlling and manipulating the salinity regime than the 10,000 cfs but less than the 35,000 cfs.

5.3.2.4.2 Indirect

Indirect impacts of implementing restoration features into the project area would be the possible

permanent transition of marsh types. These changes could have short-term consequences, such as

displacement of one type of marsh vegetation by another, but have long-term benefits by providing a

sustainable marsh and delta forming functions. Indirect impacts to marsh zones of the 15,000 cfs

alternative would be anticipated to be as described in Section 5.3.2.2.2 under the proposed operating plan;

however, the operations of the Caernarvon Diversion, the CWPPRA rehabilitation of the existing White

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Ditch Siphon, and the proposed White Ditch structure would need a coordinated operations effort to

manage salinity levels throughout the Breton Sound Basin. With these structures running concurrently for

an extended period of time, there could be undesired consequences in the Breton Sound.

5.3.2.4.3 Cumulative

Cumulative impacts would be the synergistic effect of the 15,000 cfs Alternative on salinity levels when

considered in context with all past, present, and reasonably foreseeable acts of nature and/or the actions

private entities, state government, and Federal Government. The operations of the Caernarvon Diversion,

the CWPPRA rehabilitation of the existing White Ditch Siphon, and the proposed White Ditch structure

would need a coordinated operations effort to manage salinity levels throughout the Breton Sound Basin.

5.3.2.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.3.2.5.1 Direct

Salinity levels within the White Ditch project area would be affected. Significant freshening of the project

area as well as the entire Breton Sound Basin would occur with maximum operations of the structure.

Since all build alternatives completely freshen the Breton Sound, anticipated salinity changes are the

same as described in Section 5.3.2.2.1. Operation and management measures could work toward

establishing target zones for optimum marsh type production throughout the project area. Of the

implementation alternatives considered, the 35,000 cfs diversion would have the most flexibility in terms

of controlling and manipulating the salinity regime. In relation, it would present the most options for

adaptive management.

5.3.2.5.2 Indirect

Indirect impacts of implementing restoration features into the project area would be the possible

permanent transition of marsh types. These changes could have short-term consequences, such as

displacement of one type of marsh vegetation by another, but have long-term benefits by providing a

sustainable marsh and delta forming functions. Indirect impacts to marsh zones of the 15,000 cfs

alternative would be anticipated to be as described in Section 5.3.2.2.2 under the proposed operating plan;

however, the operations of the Caernarvon Diversion, the CWPPRA rehabilitation of the existing White

Ditch Siphon, and the proposed White Ditch structure would need a coordinated operations effort to

manage salinity levels throughout the Breton Sound Basin. With these structures running concurrently for

an extended period of time, there could be undesired consequences in the Breton Sound.

5.3.2.5.3 Cumulative

Cumulative impacts would be the synergistic effect of the 35,000 cfs Alternative on salinity levels when

considered in context with all past, present, and reasonably foreseeable acts of nature and/or the actions

private entities, state government, and Federal Government. The operations of the Caernarvon Diversion,

the CWPPRA rehabilitation of the existing White Ditch Siphon, and the proposed White Ditch structure

would need a coordinated operations effort to manage salinity levels throughout the Breton Sound Basin.

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5.4 AIR QUALITY

5.4.1 No Action Alternative (Future Without Project

Conditions)

The No Action Alternative would have no direct impacts on air quality. Indirect impacts of not

implementing the diversion and outfall management features would result in the persistence of existing

conditions. The project area is a remote and largely uninhabited marsh. Air quality would continue to be

subject to institutional recognition and further regulations. However, air quality in the project area would

likely decline for the following reasons: continued population growth, further commercialization and

industrialization, increased numbers of motor vehicles, and increased emissions from various engines.

These impacts would be coupled with the continued loss of Louisiana coastal wetland vegetation that

would no longer be available to remove gaseous pollutants. Nevertheless, air quality degradation is not

anticipated to be a significant problem in the project area under the No Action Alternative during the 50-

year period of analysis. Cumulative impacts would be the synergistic effect of the No Action Alternative

on air quality with the additive combination of similar air quality impacts from wetland loss and

degradation throughout coastal Louisiana, as well as the benefits and impacts of other state and Federal

projects in the vicinity.

5.4.2 Alternative 1 – 5,000 cfs max Diversion

5.4.2.1 Direct

Direct impacts of the 5,000 cfs diversion alternative on air quality would be similar to, but lesser in

magnitude, than those expected to result from the Recommended Plan.

5.4.2.2 Indirect

Over the 50-year period of analysis, the 5,000 cfs diversion is projected to reduce anticipated future losses

of emergent wetlands that help to improve local air quality by reducing particulates and gaseous air

pollutants. Impacts of the wetland restoration on air quality would be expected to be similar to, but lesser

in magnitude than, those expected to result from implementation of the Recommended Plan.

5.4.2.3 Cumulative

Cumulative impacts of the 5,000 cfs diversion alternative on air quality would be similar to, but lesser in

magnitude, than those expected to result from the Recommended Plan.

5.4.3 Alternative 2 – 10,000 cfs max Diversion

5.4.3.1 Direct

Direct impacts of the 10,000 cfs diversion alternative on air quality would be similar to, but lesser in

magnitude, than those expected to result from the Recommended Plan.

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5.4.3.2 Indirect

Over the 50-year period of analysis, the 10,000 cfs diversion is projected to reduce anticipated future

losses of emergent wetlands that help to improve local air quality by reducing particulates and gaseous air

pollutants. Impacts of the wetland restoration on air quality would be expected to be similar to, but lesser

in magnitude than, those expected to result from implementation of the Recommended Plan.

5.4.3.3 Cumulative

Cumulative impacts of the 10,000 cfs diversion alternative would be similar to, but lesser in magnitude,

than those expected to result from the Recommended Plan.

5.4.4 Alternative 3 – 15,000 cfs max Diversion

5.4.4.1 Direct

Direct impacts of the 15,000 cfs diversion alternative on air quality would be similar to, but lesser in

magnitude, than those expected to result from the Recommended Plan.

5.4.4.2 Indirect

Over the 50-year period of analysis, the 15,000 cfs diversion is projected to reduce anticipated future

losses of emergent wetlands that help to improve local air quality by reducing particulates and gaseous air

pollutants. Impacts of the wetland restoration on air quality would be expected to be similar to, but lesser

in magnitude than, those expected to result from implementation of the Recommended Plan.

5.4.4.3 Cumulative

Cumulative impacts of the 15,000 cfs diversion alternative would be similar to, but lesser in magnitude,

than those expected to result from the Recommended Plan.

5.4.5 Alternative 4 – 35,000 cfs max Diversion

(Recommended Plan)

5.4.5.1 Direct

Direct impacts to ambient air quality resulting from construction of the 35,000 cfs diversion and outfall

management features would be temporary and localized, resulting primarily from the emissions of

construction equipment within the project area. Total emissions generally do not exceed the threshold

limit applicable to volatile organic compounds (VOC) for parishes where the most stringent requirement

(50 tons per year [49.38 metric tons per year] in serious non-attainment parishes) is in effect.

Additionally, these effects to air quality would be temporary, and air quality would return to preconstruction conditions shortly after the completion of construction activities.

5.4.5.2 Indirect

Over the 50-year period of analysis, the 35,000 cfs diversion is projected to restore a substantial portion

of emergent wetlands that historically existed in the project area, and protect emergent wetlands that help

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to improve local air quality by reducing particulates and gaseous air pollutants, from future losses that

would be expected to occur if the project was not constructed. Studies of the effects of common wetland

plants on removing or reducing air pollution in the coastal Louisiana area have yet to be done. However,

it is reasonable to extrapolate from the findings of researchers such as David J. Nowak (personal

communication, Mr. David J. Nowak, Project Leader, USDA Forest Service, Northeastern Research

Station, 5 Moon Library, SUNY-CESF, Syracuse, New York) that vegetation in coastal Louisiana would

improve air quality. Improvement of air quality would provide positive benefits for humans overall,

although this relative difference would be minimal because of the size of the project area and distance

from population centers.

5.4.5.3 Cumulative

Implementation of the 35,000 cfs diversion would work synergistically with other ecosystem restoration

projects in coastal Louisiana to provide greater longevity for wetlands in the region. Although unlikely to

greatly impact air quality alone, the project would provide some air quality improvement from the

cumulative effects of creating, nourishing and protecting these wetlands in conjunction with other

restoration efforts.

5.5 NOISE

5.5.1 No Action Alternative (Future Without Project

Conditions)

There would be no direct, indirect, or cumulative impacts of the No Action Alternative on noise. Not

implementing the proposed river diversion and outfall management features would result in the

persistence of existing conditions. The project area is a remote and largely uninhabited marsh. The noise

from nearby urban areas has little, if any, impact on the project area. This is expected to continue in the

future.

5.5.2 Alternative 1 – 5,000 cfs max Diversion

5.5.2.1 Direct

Direct impacts to noise levels resulting from construction of the 5,000 cfs diversion and associated

features would be expected to be similar to those anticipated to result from construction of the

Recommended Plan.

5.5.2.2 Indirect

Noise could temporarily cause some local fish and wildlife species to relocate during construction

activities. However, any indirect impacts due to noise would be expected to be localized, temporary, and

minor in nature.

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5.5.2.3 Cumulative

Cumulative impacts to noise levels resulting from construction of the 5,000 cfs diversion and associated

features would be expected to be similar to those anticipated to result from construction of the

Recommended Plan.

5.5.3 Alternative 2 – 10,000 cfs max Diversion

5.5.3.1 Direct

Direct impacts to noise levels resulting from construction of the 10,000 cfs diversion and associated

features would be expected to be similar to those anticipated to result from construction of the

Recommended Plan.

5.5.3.2 Indirect

Noise could temporarily cause some local fish and wildlife species to relocate during construction

activities. However, any indirect impacts due to noise would be expected to be localized, temporary, and

minor in nature.

5.5.3.3 Cumulative

Cumulative impacts to noise levels resulting from construction of the 10,000 cfs diversion and associated

features would be expected to be similar to those anticipated to result from construction of the

Recommended Plan.

5.5.4 Alternative 3 – 15,000 cfs max Diversion

5.5.4.1 Direct

Direct impacts to noise levels resulting from construction of the 15,000 cfs diversion and associated

features would be expected to be similar to those anticipated to result from construction of the

Recommended Plan.

5.5.4.2 Indirect

Noise could temporarily cause some local fish and wildlife species to relocate during construction

activities. However, any indirect impacts due to noise would be expected to be localized, temporary, and

minor in nature.

5.5.4.3 Cumulative

Cumulative impacts to noise levels resulting from construction of the 15,000 cfs diversion and associated

features would be expected to be similar to those anticipated to result from construction of the

Recommended Plan.

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5.5.5 Alternative 4 – 35,000 cfs max Diversion

(Recommended Plan)

5.5.5.1 Direct

Construction activities associated with implementing the 35,000 cfs diversion and outfall management

features would temporarily increase the noise level in the project area. However, the project area is

remote and sparsely populated so the noise level would not affect any nearby human communities. Once

construction activities would be completed, noise levels would be expected return to preconstruction

conditions.

Potential noise impacts concerns could be expected from construction activities, although construction

equipment is limited in the level of noise that can be emitted. Institutional recognition of noise, such as

provided by the regulations for Occupational Noise Exposure (29 CFR Part 1910.95) under the

Occupational Safety and Health Act of 1970, as amended, would continue. This section mandates that

noise levels emitted from construction equipment be below 90 dB for exposures of 8 hours per day or

more.

Localized and temporary noise impacts would likely result in wildlife and fishery resources temporarily

leaving the project area during construction activities. In some instances, noise impacts could directly

impact fish and wildlife species. These organisms would generally avoid the construction area. At this

point, no sensitive species have been determined to be present in the project area. However, if ever it is

determined that a key species of concern is present, then the team would follow feasible administrative

and or engineering controls, determine and implement appropriate buffer zones, and implement

construction activity windows.

5.5.5.2 Indirect

Noise could temporarily cause some local fish and wildlife species to relocate during construction

activities. However, any indirect impacts due to noise would be expected to be localized, temporary, and

minor in nature.

5.5.5.3 Cumulative

Cumulative impacts to noise levels resulting from implementation of the 35,000 cfs diversion would

principally be related to the potential short-term disruption of fish and wildlife species and similar

impacts by other similar Federal, state, local and private restoration activities as well as other humaninduced noise disruptions to these organisms. Cumulative impacts would be a synergistic result over and

above the additive combination of impacts and benefits of this alternative and other Federal, state, local,

and private restoration efforts. Long-term adverse cumulative impacts due to noise levels would not be

expected with implementation of the diversion.

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5.6 VEGETATIVE RESOURCES

5.6.1 Riparian Vegetation Resources

5.6.1.1 No Action Alternative (Future Without Project Conditions)

5.6.1.1.1 Direct

Under the No Action Alternative, no construction of diversion structure or associated outfall management

features would occur, and no BLH would be cleared or filled by construction activities. No opportunities

for beneficial use of dredged material for construction features would occur. Existing BLH in the project

footprint would continue to degrade and convert to intermediate marsh.

5.6.1.1.2 Indirect

With no action, no input of sediment, freshwater and nutrients to the project area would occur. This would

result in the persistence of existing conditions including continued erosion of marsh soils, and continued

fragmentation and conversion of BLH to intermediate and brackish marsh habitats. Both man-made and

natural processes would contribute to the continued loss of vegetated habitats, including: continued

erosion and subsidence, increased saltwater intrusion, and increased water velocities. Over the next 50

years, the remaining BLH species in the study area would experience continued subsidence, sea level rise,

and salinity increases. The BLH would eventually diminish and convert to marsh.

5.6.1.1.3 Cumulative

Cumulative impacts would be the same effect of the No Action Alternative with land loss rates of

approximately 274.5 acres per year throughout the 50-year project life. In addition, cumulative impacts

would include the additive combination of coast wide BLH loss and degradation, as well as the benefits

and impacts of other local, state, Federal, and private projects summarized in Section 1.5. The existing

freshwater diversion at Caernarvon would freshen the surrounding waters, albeit to an unknown extent. In

addition, the LCA Caernarvon Freshwater Diversion Modification (CFDM) project could potentially

result in a selected plan having features that create and restore BLH ridges from the secondary use of

channel dredging to redirect water flows. Some Section 10 and 404 permits have been issued by the

CEMVN for maintenance dredging canals northeast of the WDWD project. Some dredged material

placement areas from this dredging would likely reforest with BLH species.

5.6.1.2 Alternative 1 – 5,000 cfs max Diversion

5.6.1.2.1 Direct

Construction of the 5,000 cfs diversion structure would have direct negative impacts to 2.5 acres of BLH

between the Mississippi River Levee and the Mississippi River. The proposed 2.5 acres of BLH loss has a

value of 1.25 AAHUs. The placement of dredged material would provide direct positive benefit of 16.91

AAHUs by establishing approximately 32 acres of BLH ridge creation.

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5.6.1.2.2 Indirect

Operation of the 5,000 cfs diversion alternative would indirectly provide an inflow of freshwater,

sediments and nutrients to the project area and redistribute sediments along existing and created BLH

ridges during pulses. A net loss of acreage of all habitat types in the project area is expected to continue

under this alternative; however, riparian vegetation on the created BLH ridges could persist through much

of the 50-year period following project construction.

5.6.1.2.3 Cumulative

Cumulative impacts would be the synergistic combination of the project with coast wide BLH loss and

degradation, as well as the benefits and impacts of other state, Federal, or private projects summarized in

Section 1.5. Modification of the operation of the Caernarvon structure project could potentially result in a

selected plan that would have features that create and restore BLH ridges from the secondary use of

channels dredged to redirect water flows. Some Section 10 and 404 permits have been issued by the

CEMVN for maintenance dredging canals northeast of the WDWD project. Some dredged material

placement areas from this dredging would likely reforest with BLH species.

5.6.1.3 Alternative 2 – 10,000 cfs max Diversion

5.6.1.3.1 Direct

Construction of the 10,000 cfs diversion structure would have direct negative impacts to 2.5 acres of BLH

between the Mississippi River Levee and the Mississippi River. The proposed 2.5 acres of BLH loss has a

value of 1.25 AAHUs. The placement of dredged material would provide direct positive benefit of 16.91

AAHUs by establishing approximately 32 acres of BLH ridge creation.

5.6.1.3.2 Indirect

Operation of the 10,000 cfs diversion alternative would indirectly provide an inflow of freshwater,

sediments and nutrients to the project area and redistribute sediments along existing and created BLH

ridges during pulses. No net loss of total acreage of vegetation in the project area is expected to occur

with this alternative; however, it is possible that existing remnants of BLH in the project area could

continue to deteriorate with this alternative.

5.6.1.3.3 Cumulative

Cumulative impacts would be the synergistic combination of the project with coast wide BLH loss and

degradation, as well as the benefits and impacts of other state, Federal, or private projects summarized in

Section 1.5. Modification of the operation of the Caernarvon structure project could potentially result in a

selected plan that would have features that create and restore BLH ridges from the secondary use of

channels dredged to redirect water flows. Some Section 10 and 404 permits have been issued by the

CEMVN for maintenance dredging canals northeast of the WDWD project. Some dredged material

placement areas from this dredging would likely reforest with BLH species.

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5.6.1.4 Alternative 3- 15,000 cfs max Diversion

5.6.1.4.1 Direct

Construction of the 15,000 cfs diversion structure would have direct negative impacts to 5 acres of BLH

between the Mississippi River Levee and the Mississippi River. The proposed 5 acres of BLH loss has a

value of 2.50 AAHUs in the study area. The placement of dredged material would provide direct

positive benefit of 16.91 AAHUs by establishing approximately 32 acres of BLH ridge creation.

5.6.1.4.2 Indirect

Operation of the 15,000 cfs diversion alternative would indirectly provide an inflow of freshwater,

sediments and nutrients to the project area and redistribute sediments along existing and created BLH

ridges during pulses. Increases in overall coverage of vegetation would occur in the project area;

however, increases in BLH beyond the created ridges is expected to be negligible in the project area.

5.6.1.4.3 Cumulative

Cumulative impacts would be the synergistic combination of the project with coast wide BLH loss and

degradation, as well as the benefits and impacts of other state, Federal, or private projects summarized in

Section 1.5. Modification of the operation of the Caernarvon structure project could potentially result in a

selected plan that would have features that create and restore BLH ridges from the secondary use of

channels dredged to redirect water flows. Some Section 10 and 404 permits have been issued by the

CEMVN for maintenance dredging canals northeast of the WDWD project. Some dredged material

placement areas from this dredging would likely reforest with BLH species.

5.6.1.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.6.1.5.1 Direct

Construction of the 35,000 cfs diversion structure would have direct negative impacts to 5 acres of BLH

between the Mississippi River Levee and the Mississippi River. The proposed 5 acres of BLH loss has a

value of 2.50 AAHUs in the study area. The placement of dredged material would provide direct

positive benefit of 15.99 AAHUs by establishing approximately 31 acres of BLH ridge creation.

5.6.1.5.2 Indirect

Operation of the 35,000 cfs diversion alternative would indirectly provide an inflow of freshwater,

sediments and nutrients to the project area and redistribute sediments along existing and created BLH

ridges during pulses. No net loss of acreage of all land types in the project area is expected to occur with

this alternative. Additionally, the WVA assessment of proposed diversion alternatives projected that the

35,000 cfs diversion would produce overall gains in vegetation coverage in the project area; however, no

substantial gains in BLH coverage beyond the created ridges would be expected.

5.6.1.5.3 Cumulative

Cumulative impacts would be the synergistic combination of the project with coast wide BLH loss and

degradation, as well as the benefits and impacts of other state, Federal, or private projects summarized in

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Section 1.5. Modification of the operation of the Caernarvon structure project could potentially result in a

selected plan that would have features that create and restore BLH ridges from the secondary use of

channels dredged to redirect water flows. Some Section 10 and 404 permits have been issued by the

CEMVN for maintenance dredging canals northeast of the WDWD project. Some dredged material

placement areas from this dredging would likely reforest with BLH species.

5.6.2 Wetland Vegetation Resources

5.6.2.1 No Action Alternative (Future Without Project Conditions)

5.6.2.1.1 Direct

Under the No Action Alternative, no direct impacts to existing wetland vegetation resulting from

construction of the proposed diversion and associated features would occur. No opportunities for

beneficial reuse of marsh soil and substrate excavated for construction would be realized.

5.6.2.1.2 Indirect

With no action, no increase in input of sediment, freshwater and nutrients to the project area would occur.

This would result in the persistence of existing conditions including continued erosion of marsh soils, and

continued fragmentation and conversion of existing intermediate, brackish and saline marsh to shallow

open-water habitats. Both man-made and natural processes would contribute to the continued loss of

vegetated habitats, including: continued erosion and subsidence, increased saltwater intrusion, increased

water velocities, and increased herbivory. Over the next 50 years, substantial acreage of wetland

vegetation is projected to be lost.

5.6.2.1.3 Cumulative

Cumulative impacts would be the synergistic effect of implementing the No Action Alternative with the

additive combination of coast wide wetland loss and degradation, as well as the benefits and impacts of

other state and Federal projects in the vicinity. The existing freshwater diversion at Caernarvon would

freshen the surrounding waters, albeit to an unknown extent. Modification of the operation of the

Caernarvon structure could result in a conversion of some intermediate marsh to fresh marsh in areas

adjacent to the MDWD project area. However, such wetland conversion would probably have little effect

on the species composition of the wetlands in the project area other than a slight shift towards less salttolerant species. The introduction of nutrients would likely increase the productivity of the nearby

marshes, but any potential effects on productivity within the MDWD project area would be unknown at

this time.

5.6.2.2 Alternative 1 – 5,000 cfs max Diversion

5.6.2.2.1 Direct

Construction of the 5,000 cfs diversion and associated outfall management features would have an initial

negative impact on existing wetland vegetation within the construction footprint, primarily through the

excavation of outfall channels and placement of excavated material on existing marsh. However, this

placement of excavated material would provide a base for the regeneration of approximately 171 acres of

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wetland vegetation, 32 acres of which (ridge creation) is expected to be suitable for the re-establishment

of bottomland hardwoods.

5.6.2.2.2 Indirect

Operation of the 5,000 cfs diversion alternative would provide an inflow of freshwater, sediments and

nutrients to the project area and support the re-establishment and nourishment of wetland vegetation in

the project area. Loss of acreage of all marsh types in the project area is expected to continue under this

alternative. However, the WVA assessment of proposed diversion alternatives projected that the 5,000 cfs

diversion would reduce overall wetland vegetation losses in the project area compared to the expected

overall loss for the No Action Alternative. It is expected that this alternative would show a gain of

approximate 5,197 AAHUs and 35,638 acres. It was anticipated that a small portion (less than 14%; see

discussion in Alternative 4) of the project area currently classified as intermediate marsh would be

converted to fresh marsh within approximately 5 years following project implementation. If this diversion

were operated fully open outside the 2-month window that is described in the document, then there could

be significantly different impacts with some potentially being very negative.

5.6.2.2.3 Cumulative

Cumulative impacts would be the synergistic combination of the project with coast wide wetland

vegetation loss and degradation, as well as the benefits and impacts of other state, Federal, or private

projects summarized in Section 1.5. Implementing Alternative 1 would result in a small incremental

reduction to the rate of loss of wetland vegetation resources in the overall region.

5.6.2.3 Alternative 2 – 10,000 cfs max Diversion

5.6.2.3.1 Direct

Construction of the 10,000 cfs diversion and associated outfall management features would have an initial

negative impact on existing wetland vegetation within the construction footprint, primarily through the

excavation of outfall channels and placement of excavated material on existing marsh. However, this

placement of excavated material would provide a base for the regeneration of approximately 208 acres of

wetland vegetation, 32 acres of which (ridge creation) is expected to be suitable for the re-establishment

of bottomland hardwoods.

5.6.2.3.2 Indirect

Operation of the 10,000 cfs diversion alternative would provide an inflow of freshwater, sediments and

nutrients to the project area and support the re-establishment and nourishment of wetland vegetation in

the project area. It was anticipated that a small portion (less than 14%; see discussion in Alternative 4) of

the project area currently classified as intermediate marsh would be converted to fresh marsh within

approximately 5 years following project implementation. The expectation of this alternative is to create

approximately 5,936 AAHUs and 40,419 acres. No net loss of acreage of wetland vegetation in the

project area is expected to occur with this alternative over the 50-year period following project

construction. If this diversion were operated fully open outside the 2-month window that is described in

the document, then there could be significantly different impacts with some potentially being very

negative.

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5.6.2.3.3 Cumulative

Cumulative impacts would be the synergistic combination of the project with coast wide wetland

vegetation loss and degradation, as well as the benefits and impacts of other state, Federal, or private

projects summarized in Section 1.5. Implementing Alternative 2 would result in a reduction to the rate of

loss of wetland vegetation resources in the overall region.

5.6.2.4 Alternative 3 – 15,000 cfs max Diversion

5.6.2.4.1 Direct

Construction of the 15,000 cfs diversion and associated outfall management features would have an initial

negative impact on existing wetland vegetation within the construction footprint, primarily through the

excavation of outfall channels and placement of excavated material on existing marsh. However, this

placement of excavated material would provide a base for the regeneration of approximately 267 acres of

wetland vegetation, 32 acres of which (ridge creation) is expected to be suitable for the re-establishment

of bottomland hardwoods.

5.6.2.4.2 Indirect

Operation of the 15,000 cfs diversion alternative would provide an inflow of freshwater, sediments and

nutrients to the project area and support the re-establishment and nourishment of wetland vegetation in

the project area. It was anticipated that a small portion (less than 14%; see discussion in Alternative 4) of

the project area currently classified as intermediate marsh would be converted to fresh marsh within

approximately 5 years following project implementation. The expectation of this alternative is to create

approximately 7,742 AAHUs and 45,046 acres. No loss of overall acreage of wetland vegetation in the

project area is expected to occur with this alternative, and some net gain in wetland vegetation is

anticipated over the 50-year planning horizon. If this diversion were operated fully open outside the 2-

month window that is described in the document, then there could be significantly different impacts with

some potentially being very negative.

5.6.2.4.3 Cumulative

Cumulative impacts would be the synergistic combination of the project with coast wide wetland

vegetation loss and degradation, as well as the benefits and impacts of other state, Federal, or private

projects summarized in Section 1.5. Implementing Alternative 4 would result in an incremental increase

in wetland vegetation resources in the overall region.

5.6.2.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.6.2.5.1 Direct

Construction of the 35,000 cfs diversion and associated outfall management features would have an initial

negative impact on existing wetland vegetation within the construction footprint, primarily through the

excavation of outfall channels and placement of excavated material on existing marsh. However, this

placement of excavated material would provide a base for the regeneration of approximately 416 acres of

wetland vegetation, 31 acres of which (ridge creation) is expected to be suitable for the re-establishment

of bottomland hardwoods.

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5.6.2.5.2 Indirect

Operation of the 35,000 cfs diversion alternative would provide an inflow of freshwater, sediments and

nutrients to the project area and support the re-establishment and nourishment of wetland vegetation in

the project area. It was anticipated that approximately 14% of the project area and 4% of the expanded

area of influence currently classified as intermediate marsh would be converted to fresh marsh within

approximately 5 years following project implementation. Substantial net gains compare to no net loss in

acreage of wetland vegetation in the project area is expected to occur with this alternative. This gain is

approximately 13,355 AAHUs and 59,902 acres. If this diversion were operated fully open outside the 2-

month window that is described in the document, then there could be significantly different impacts with

some potentially being very negative.

5.6.2.5.3 Cumulative

Cumulative impacts would be the synergistic combination of the project with coast wide wetland

vegetation loss and degradation, as well as the benefits and impacts of other state, Federal, or private

projects summarized in Section 1.5. Implementing Alternative 3 would result in a small incremental

increase in wetland vegetation resources in the overall region.

5.6.3 Upland Vegetation Resources

There would be no upland vegetation resources in the project area.

5.6.4 Submerged Aquatic Vegetation (SAV)

5.6.4.1 No Action Alternative (Future Without Project Conditions)

5.6.4.1.1 Direct

Under the No Action Alternative, no direct impacts to SAV would occur. Baseline SAV coverage was

estimated at approximately 15% of open water areas in the vicinity of the proposed construction footprint

(25% in the overall project area). Existing SAV in the project footprint would continue to degrade and die

off as increased salinities enter the study area and marsh continues to decrease in acreage.

5.6.4.1.2 Indirect

Under the No Action Alternative, no input of sediment, freshwater and nutrients to the project area would

occur. This would result in the persistence of existing conditions including continued erosion of marsh

soils, and continued fragmentation and conversion of existing intermediate, brackish and saline marsh to

shallow open-water habitats. Both man-made and natural processes would contribute to the continued loss

of vegetated habitats, including: continued erosion and subsidence, increased saltwater intrusion,

increased water velocities, and increased turbidity. Over the next 50 years, SAV is projected to be

reduced from the estimated baseline of 25% of open water areas to approximately 15% as the area

deteriorates.

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5.6.4.1.3 Cumulative

Cumulative impacts would be the same effect of the No Action Alternative with the additive combination

of coast wide SAV loss, as well as the benefits and impacts of other state, Federal, or private projects

summarized in Section 1.5. The proposed projects have borrow areas, channel dredging, and marsh

restoration sites in and adjacent to Lake Lery that would impact SAV from dredging and filling. CFDM

could result in a conversion of some intermediate marsh to fresh marsh in areas adjacent to the MDWD

project area. The Duffy (1997) study showed that SAV abundance (Eurasian watermilfoil and coontail)

has increased in the Breton Sound Basin in response to diversions. The introduction of nutrients would

likely increase the productivity of the nearby SAV, but any potential effects on productivity within the

MDWD project area would be unknown at this time.

5.6.4.2 Alternative 1 – 5,000 cfs max Diversion

5.6.4.2.1 Direct

Direct impacts to SAV would be expected to result from construction of outfall management features.

Baseline SAV coverage is anticipated to decrease to near 0% in the outfall channel footprint. In the marsh

creation footprint, little open water would remain, but any remnants would likely experience an increase

in the percentage of SAV. This is because SAV would be well adapted to the environmental conditions

likely to be present after project implementation.

5.6.4.2.2 Indirect

Operation of the 5,000 cfs diversion is anticipated to result in an increase in SAV coverage in the fresh,

intermediate, and brackish zones as a consequence of delivery of nutrients and sediments throughout the

project area (no increase in SAV coverage was anticipated to occur in the saline zone). The Habitat

Evaluation Team (HET) assumed that maintenance flow conditions (set at 1,000 cfs for all diversion

alternatives), rather than maximum pulse, would be the determining factor in effects on SAV. Based on

research that Rozas et al. (2005) conducted in the nearby Caernarvon Diversion outfall management area,

SAV coverage in the fresh and intermediate zones is expected to increase from the baseline 25% to

approximately 70%. In the brackish zone, SAV coverage was expected to increase from the estimated

15% baseline to approximately 30 percent.

5.6.4.2.3 Cumulative

The Alternative 1 outfall management features would impact some SAV during channel dredging and

filling open water areas for marsh restoration. Alternative 1 would increase overall SAV abundance in the

project area by maintaining a 1,000 cfs maintenance flow. Shallow waterbodies within the proposed

converted intermediate to fresh marsh areas would be expected to begin filling in, creating the opportunity

for SAV to establish across the project area. Cumulative impacts also include the combination of coast

wide SAV loss, as well as the benefits and impacts of other state, Federal, or private projects summarized

in Section 1.5. The proposed projects have borrow areas, channel dredging, and marsh restoration sites in

and adjacent to Lake Lery that would impact SAV from dredging and filling. The MDWD WVA results

show a conversion of some intermediate marsh to fresh marsh in areas adjacent to the MDWD project

area. The Duffy (1997) study showed that SAV abundance (Eurasian watermilfoil and coontail) has

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increased in the Breton Sound Basin in response to diversions. The introduction of sediments and

nutrients would likely increase the productivity of the nearby SAV.

5.6.4.3 Alternative 2 – 10,000 cfs max Diversion

5.6.4.3.1 Direct

Direct impacts of the 10,000 cfs diversion alternative would be essentially the same as for the 5,000 cfs

alternative; however, the extent of the affected area would be greater in proportion to the increased

construction footprint for this alternative.

5.6.4.3.2 Indirect

Operation of the 10,000 cfs diversion is expected to have the same effect on SAV in the overall project

area as the 5,000 cfs alternative. The HET assumed that maintenance flow conditions (set at 1,000 cfs for

all diversion alternatives), rather than maximum pulse, would be the determining factor in effects on

SAV.

5.6.4.3.3 Cumulative

Cumulative impacts of Alternative 2 would be similar to cumulative impacts described for Alternative 1,

except Alternative 2 outfall management features would impact more SAV during construction.

5.6.4.4 Alternative 3 – 15,000 cfs max Diversion

5.6.4.4.1 Direct

Direct impacts of the 15,000 cfs diversion alternative would be essentially the same as for the 5,000 cfs

alternative; however, the extent of the affected area would be greater in proportion to the increased

construction footprint for this alternative.

5.6.4.4.2 Indirect

Operation of the 15,000 cfs diversion is expected to have the same effect on SAV in the overall project

area as the 5,000 cfs alternative. The HET assumed that maintenance flow conditions (set at 1,000 cfs for

all diversion alternatives), rather than maximum pulse, would be the determining factor in effects on

SAV.

5.6.4.4.3 Cumulative

Cumulative impacts of Alternative 3 would be similar to cumulative impacts described for Alternative 1,

except Alternative 3 outfall management features would impact more SAV during construction.

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5.6.4.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.6.4.5.1 Direct

Direct impacts of the 35,000 cfs diversion alternative would be essentially the same as for the 5,000 cfs

alternative; however, the extent of the affected area would be greater in proportion to the increased

construction footprint for this alternative.

5.6.4.5.2 Indirect

Operation of the 35,000 cfs diversion is expected to have the same effect on SAV in the overall project

area as the 5,000 cfs alternative. The HET assumed that maintenance flow conditions (set at 1,000 cfs for

all diversion alternatives), rather than maximum pulse, would be the determining factor in effects on

SAV.

5.6.4.5.3 Cumulative

Cumulative impacts of Alternative 4 would be similar to cumulative impacts described for Alternative 1,

except Alternative 4 outfall management features would impact more SAV during construction.

5.6.5 Invasive Species – Vegetation

5.6.5.1 No Action Alternative (Future Without Project Conditions)

5.6.5.1.1 Direct

Under the No Action Alternative, invasive plant species known to occur in the project area would not be

affected.

5.6.5.1.2 Indirect

Indirect impacts to invasive plant species anticipated under the No Action Alternative would be

essentially the same as for noninvasive native plant species.

5.6.5.1.3 Cumulative

Cumulative impacts would be the same effect of the No Action Alternative with the additive combination

of coast wide invasive species distribution from other state, Federal, or private projects summarized in

Section 1.5. The proposed projects have borrow areas, channel dredging, and marsh restoration sites in

and adjacent to Lake Lery that would impact and potentially distribute invasive species from dredging

and filling. The Duffy (1997) study showed that SAV abundance (Eurasian watermilfoil and coontail) has

increased in the Breton Sound Basin in response to diversions. The introduction of nutrients would likely

increase the productivity of the nearby invasive species in the surrounding area.

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5.6.5.2 Alternative 1 – 5,000 cfs max Diversion

5.6.5.2.1 Direct

Direct impacts to invasive plant species resulting from construction of the 5,000 cfs diversion alternative

would be expected to be essentially the same as anticipated for other wetland vegetation and SAV in the

construction footprint.

5.6.5.2.2 Indirect

Operation of the 5,000 cfs diversion alternative would introduce fresh river water, sediment and nutrients

into the constructed outfall channels and existing distributary channels within the project area. Under the

operational plan used for the evaluation of alternatives, during the majority of the growing season the

diversion inflow was assumed to be 1,000 cfs for all alternatives. This continuous inflow of freshwater

has the potential to promote increased growth of freshwater invasive exotics such as water hyacinth in

outfall and distributary channels.

5.6.5.2.3 Cumulative

Cumulative impacts would be the same effect of Alternative 1 with the additive combination of coast

wide invasive species distribution from other state, Federal, or private projects summarized in Section 1.5.

The proposed projects have borrow areas, channel dredging, and marsh restoration sites in and adjacent to

Lake Lery that would impact and potentially distribute invasive species from dredging and filling. The

Duffy (1997) study showed that SAV abundance (Eurasian watermilfoil and coontail) has increased in the

Breton Sound Basin in response to diversions. The introduction of nutrients would likely increase the

productivity of the nearby invasive species in the surrounding area. The MDWD project, even if generally

beneficial to native marsh plant communities and animal populations, it could have the unintended

consequence of increasing the spatial coverage and density of invasive plant species.

5.6.5.3 Alternative 2 – 10,000 cfs max Diversion

5.6.5.3.1 Direct

Direct impacts to invasive plant species resulting from construction of the 10,000 cfs diversion alternative

would be expected to be essentially the same as anticipated for other wetland vegetation and SAV in the

construction footprint.

5.6.5.3.2 Indirect

Operation of the 10,000 cfs diversion alternative would introduce fresh river water, sediment and

nutrients into the constructed outfall channels and existing distributary channels within the project area.

Under the operational plan used for the evaluation of alternatives, during the majority of the growing

season the diversion inflow was assumed to be 1,000 cfs for all alternatives. This continuous inflow of

freshwater has the potential to promote increased growth of freshwater invasive exotics such as water

hyacinth in outfall and distributary channels.

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5.6.5.3.3 Cumulative

Cumulative impacts of Alternative 2 would be similar to cumulative impacts described for Alternative 1.

5.6.5.4 Alternative 3 – 15,000 cfs max Diversion

5.6.5.4.1 Direct

Direct impacts to invasive plant species resulting from construction of the 15,000 cfs diversion alternative

would be expected to be essentially the same as anticipated for other wetland vegetation and SAV in the

construction footprint.

5.6.5.4.2 Indirect

Operation of the 15,000 cfs diversion alternative would introduce fresh river water, sediment and

nutrients into the constructed outfall channels and existing distributary channels within the project area.

Under the operational plan used for the evaluation of alternatives, during the majority of the growing

season the diversion inflow was assumed to be 1,000 cfs for all alternatives. This continuous inflow of

freshwater has the potential to promote increased growth of freshwater invasive exotics such as water

hyacinth in outfall and distributary channels.

5.6.5.4.3 Cumulative

Cumulative impacts of Alternative 3 would be similar to cumulative impacts described for Alternative 1.

5.6.5.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.6.5.5.1 Direct

Direct impacts to invasive plant species resulting from construction of the 35,000 cfs diversion alternative

would be expected to be essentially the same as anticipated for other wetland vegetation and SAV in the

construction footprint.

5.6.5.5.2 Indirect

Operation of the 35,000 cfs diversion alternative would introduce fresh river water, sediment and

nutrients into the constructed outfall channels and existing distributary channels within the project area.

Under the operational plan used for the evaluation of alternatives, during the majority of the growing

season the diversion inflow was assumed to be 1,000 cfs for all alternatives. This continuous inflow of

freshwater has the potential to promote increased growth of freshwater invasive exotics such as water

hyacinth in outfall and distributary channels.

5.6.5.5.3 Cumulative

Cumulative impacts of Alternative 4 would be similar to cumulative impacts described for Alternative 1.

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5.7 WILDLIFE AND HABITAT

5.7.1 No Action Alternative (Future Without Project

Conditions)

5.7.1.1 Direct

Under the No Action Alternative, no construction of diversion structure or associated outfall management

features would occur.

5.7.1.2 Indirect

Indirect impacts of the No Action Alternative would result in the persistence of existing conditions

including the continued degradation of existing wetlands used as foraging, nesting, and over-wintering

habitat to open-water habitats; and the decline in habitat quality as wetlands continue to deteriorate and

fragment. As interior wetlands convert to open water, there would be an expected loss of species richness.

5.7.1.3 Cumulative

Cumulative impacts would be the synergistic effect of implementing the No Action Alternative with the

additive combination of coast wide wildlife habitat losses and degradation, as well as the benefits and

impacts of other state and Federal projects in the vicinity.

5.7.2 Alternative 1 – 5,000 cfs max Diversion

5.7.2.1 Direct

Construction of the diversion structure and associated outfall management features of the 5,000 cfs

diversion alternative could disrupt or displace wildlife in the immediate vicinity. However, any such

impacts would be localized and temporary, and most wildlife species would move to an area with more

favorable conditions and return after construction is completed. While some species could be permanently

displaced from the construction footprint by channel excavation and placement of excavated material in

nearby marsh and shallow water areas, the long-term impact of construction is expected to be beneficial

to overall habitat quality. The WVA analysis of outfall management features projected a net benefit of

58.04 AAHUs for the outfall management features associated with this alternative.

5.7.2.2 Indirect

Implementation of the 5,000 cfs diversion alternative would introduce river sediments, freshwater, and

nutrients into the project area. Indirect impacts to wildlife resources resulting from the diversion would

include the creation, restoration, and protection of wetland habitats utilized by resident and migratory

wildlife for nesting, rearing of young, resting, and foraging activities. An increase in wetland acreage

would provide increased nesting, brood-rearing, and foraging habitat for resident and migrant avian

species. Wetland creation/nourishment and shoreline protection would also help to increase and preserve

important stopover habitat for neotropical migrants and wintering habitat for waterfowl. The WVA

analysis of the potential effects of the diversion projected a net benefit of 5,399.43 AAHUs for operation

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of the diversion, for a total projected net benefit of 5,457.48 AAHUs including benefits projected for the

outfall management features.

5.7.2.3 Cumulative

Implementation of the 5,000 cfs diversion alternative would have positive synergistic effects on wildlife

resources when combined with other Federal, state, local, and private restoration efforts, including the

Caernarvon diversion. This alternative would protect, create and nourish important and essential wildlife

habitats. Migratory birds could increase their use of the project area as critical migratory habitat is

protected, created, and nourished. Local populations of game animals, furbearers, reptiles, amphibians,

and invasive species such as nutria would benefit from the cumulative effects of protecting, creating and

nourishing important and essential transitional wetlands. However, the incremental effect of this

alternative is unlikely to benefit populations of these species on a continental scale.

5.7.3 Alternative 2 – 10,000 cfs max Diversion

5.7.3.1 Direct

Construction of the diversion structure and associated outfall management features of the 10,000 cfs

diversion alternative could disrupt or displace wildlife in the immediate vicinity. However, any such

impacts would be localized and temporary, and most wildlife species would move to an area with more

favorable conditions and return after construction is completed. While some species could be permanently

displaced from the construction footprint by channel excavation and placement of excavated material in

nearby marsh and shallow water areas, the long-term impact of construction is expected to be beneficial

to overall habitat quality. The WVA analysis of outfall management features projected a net benefit of

70.79 AAHUs for the outfall management features associated with this alternative.

5.7.3.2 Indirect

Implementation of the 10,000 cfs diversion alternative would introduce river sediments, freshwater, and

nutrients into the project area. Indirect impacts to wildlife resources resulting from the diversion would

include the creation, restoration, and protection of wetland habitats utilized by resident and migratory

wildlife for nesting, rearing of young, resting, and foraging activities. An increase in wetland acreage

would provide increased nesting, brood-rearing, and foraging habitat for resident and migrant avian

species. Wetland creation/nourishment and shoreline protection would also help to increase and preserve

important stopover habitat for neotropical migrants and wintering habitat for waterfowl. The WVA

analysis of the potential effects of the diversion projected a net benefit of 6,024.84 AAHUs for operation

of the diversion, for a total projected net benefit of 6,095.63 AAHUs including benefits projected for the

outfall management features.

5.7.3.3 Cumulative

Implementation of the 10,000 cfs diversion alternative would have positive synergistic effects on wildlife

resources when combined with other Federal, state, local, and private restoration efforts, including the

Caernarvon diversion. This alternative would protect, create and nourish important and essential wildlife

habitats to a greater degree than Alternative 1. Migratory birds could increase their use of the project area

as critical migratory habitat is protected, created and nourished. Local populations of game animals,

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furbearers, reptiles, amphibians, and invasive species such as nutria would benefit from the cumulative

effects of protecting, creating and nourishing important and essential transitional wetlands. However, the

incremental effect of this alternative is unlikely to benefit populations of these species on a continental

scale.

5.7.4 Alternative 3 – 15,000 cfs max Diversion

5.7.4.1 Direct

Construction of the diversion structure and associated outfall management features of the 15,000 cfs

diversion alternative could disrupt or displace wildlife in the immediate vicinity. However, any such

impacts would be localized and temporary, and most wildlife species would move to an area with more

favorable conditions and return after construction is completed. While some species could be permanently

displaced from the construction footprint by channel excavation and placement of excavated material in

nearby marsh and shallow water areas, the long-term impact of construction is expected to be beneficial

to overall habitat quality. The WVA analysis of outfall management features projected a net benefit of

88.45 AAHUs for the outfall management features associated with this alternative.

5.7.4.2 Indirect

Implementation of the 15,000 cfs diversion alternative would introduce river sediments, freshwater, and

nutrients into the project area. Indirect impacts to wildlife resources resulting from the diversion would

include the creation, restoration, and protection of wetland habitats utilized by resident and migratory

wildlife for nesting, rearing of young, resting, and foraging activities. An increase in wetland acreage

would provide increased nesting, brood-rearing, and foraging habitat for resident and migrant avian

species. Wetland creation/nourishment and shoreline protection would also help to increase and preserve

important stopover habitat for neotropical migrants and wintering habitat for waterfowl. The WVA

analysis of the potential effects of the diversion projected a net benefit of 7,833.06 AAHUs for operation

of the diversion, for a total projected net benefit of 7,921.51 AAHUs including benefits projected for the

outfall management features.

5.7.4.3 Cumulative

Implementation of the 15,000 cfs diversion alternative would have positive synergistic effects on wildlife

resources when combined with other Federal, state, local, and private restoration efforts, including the

Caernarvon diversion. This alternative would protect, create and nourish important and essential wildlife

habitats to a greater degree than Alternatives 1 or 2. Migratory birds could increase their use of the project

area as critical migratory habitat is protected, created and nourished. Local populations of game animals,

furbearers, reptiles, amphibians, and invasive species such as nutria would benefit from the cumulative

effects of protecting, creating and nourishing important and essential transitional wetlands. However, the

incremental effect of this alternative is unlikely to measurably benefit populations of these species on a

continental scale.

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5.7.5 Alternative 4 – 35,000 cfs max Diversion

(Recommended Plan)

5.7.5.1 Direct

Construction of the diversion structure and associated outfall management features of the 35,000 cfs

diversion alternative could disrupt or displace wildlife in the immediate vicinity. However, any such

impacts would be localized and temporary, and most wildlife species would move to an area with more

favorable conditions and return after construction is completed. While some species could be permanently

displaced from the construction footprint by channel excavation and placement of excavated material in

nearby marsh and shallow water areas, the long-term impact of construction is expected to be beneficial

to overall habitat quality. The WVA analysis of outfall management features projected a net benefit of

152.25 AAHUs for the outfall management features associated with this alternative.

5.7.5.2 Indirect

Implementation of the 35,000 cfs diversion alternative would introduce river sediments, freshwater, and

nutrients into the project area. Indirect impacts to wildlife resources resulting from the diversion would

include the creation, restoration, and protection of wetland habitats utilized by resident and migratory

wildlife for nesting, rearing of young, resting, and foraging activities. An increase in wetland acreage

would provide increased nesting, brood-rearing, and foraging habitat for resident and migrant avian

species. Wetland creation/nourishment and shoreline protection would also help to increase and preserve

important stopover habitat for neotropical migrants and wintering habitat for waterfowl. The WVA

analysis of the potential effects of the diversion projected a net benefit of 13,423.01 AAHUs for operation

of the diversion, for a total projected net benefit of 13,575.26 AAHUs, including benefits projected for the

outfall management features. Nutria currently exist in the project area and would be expected to

negatively impact marsh vegetation in the project area under this and all other alternatives, including the

No Action Alternative. The existing State bounty program will continue to function as a control measure

on the proliferation of nutria, and the long-term restoration of healthy marsh in the project area is

expected to enhance existing natural controls (alligator predation) on nutria populations.

5.7.5.3 Cumulative

Implementation of the 35,000 cfs diversion alternative would have positive synergistic effects on wildlife

resources when combined with other Federal, state, local, and private restoration efforts, including the

Caernarvon diversion. This alternative would protect, create and nourish important and essential wildlife

habitats to the greatest degree of the four alternatives evaluated in detail. Migratory birds could increase

their use of the project area as critical migratory habitat is protected, created and nourished. Local

populations of game animals, furbearers, reptiles, amphibians, and invasive species such as nutria would

benefit from the cumulative effects of protecting, creating and nourishing important and essential

transitional wetlands. However, the incremental effect of this alternative is unlikely to measurably benefit

populations of these species on a continental scale.

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5.8 AQUATIC RESOURCES

5.8.1 Benthic

These resources would be institutionally significant because of the NEPA of 1969; the Coastal Zone

Management Act; and the Estuary Protection Act. These resources would be technically significant

because benthic animals would be directly or indirectly involved in most physical and chemical processes

that occur in estuaries (Day et al. 1989). Benthic resources would be publicly significant because

members of the epibenthic community (mussels, etc.) provide commercial and recreational fisheries as

well as creating oyster reef habitats used by many marine and estuarine organisms.

5.8.1.1 No Action Alternative (Future Without Project Conditions)

5.8.1.1.1 Direct

Without construction or operation of the project features, or diversion of river water and sediments into

the White Ditch Project Area, no direct impacts would occur to the present benthic community.

5.8.1.1.2 Indirect

As stated in the LCA Study  Main Report, under the no action alternative, marine (saltwater) influences

would continue to take hold and convert freshwater wetlands into intermediate, brackish, and saline

marsh. As freshwater inputs continue to decline and allow marine influences to predominate over riverine

influence, salinity levels rise, resulting in the conversion of low-lying vegetated areas to open water and

the redistribution of marine sediment. These actions eventually lead to conditions that expedite interior

marsh loss. According to Mitsch and Gosselink (1993), the salt marsh is a major producer of detritus for

both the salt marsh system and the adjacent estuary. Most plant biomass dies and decays and its energy is

processed through the detrital pathway by the benthic community. The bottom estuarine substrate or

benthic zone regulates or modifies most physical, chemical, geological, and biological processes

throughout the entire estuarine system via what is commonly called a "benthic effect" (Day et al. 1989).

As detrital inputs lessen due to the loss of SAV from saltwater intrusion, the benthic community and

benthic processes would shift from that of an estuarine community to a more open water marine

community.

5.8.1.1.3 Cumulative

Over the long term, without renewed inputs of freshwater, sediment, and nutrients to restore and maintain

emergent marsh habitat, the project area is likely to convert from a predominately estuarine habitat to a

predominately marine habitat. The benthic community which support the estuarine system processes

would be adversely affected by the reduction and eventual loss of this habitat. The species richness

(variety of organisms) of the benthic community typically declines as one progresses from ocean waters

upstream into lower salinities, and often reaches a minimum between 4 and 6 ppt (Day et al. 1989).

Hence, it is expected that increases in marine benthic community species diversity would occur in the

project area as marsh loss continues.

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5.8.1.2 Alternative 1 – 5,000 cfs max Diversion

5.8.1.2.1 Direct

For the 5,000 cfs diversion alternative, the existing benthic communities in the footprint of the proposed

construction and dredging activities would be destroyed. This area would encompass 144 acres of

intermediate marsh and 187 acres of shallow open water. Temporary increases in turbidity, temperatures,

and biological oxygen demand (BOD), as well as temporary decreases in DO would contribute to further

mortality and displacement of the benthic community in the project area. In addition, ridge creation would

result in approximately 32 acres becoming unavailable for benthic aquatic fauna. However, following

construction, benthic organisms would likely recolonize aquatic habitats in the project area, and the

enhancement of freshwater marsh habitat by the diversion should be beneficial to numerous benthic

species. Introduction of additional freshwater into estuarine systems could have short-term impacts on

benthic populations in receiving waters as well. Introduction of freshwater flows from proposed features

would be expected to change benthic abundance, species composition, and species distribution. Changes

in benthic species assemblages would likely be similar to what is observed along present day estuarine

salinity gradients except that increased freshwater flows would shift the benthic community, displacing

marine species in favor of fresher and more estuarine, euryhaline species. In addition, some benthic

organisms from the Mississippi River would be expected to be entrained in the immediate vicinity of the

diversion inflow while it is in operation.

5.8.1.2.2 Indirect

Each of the 5,000, 10,000, 15,000, and 35,000 alternatives would freshen the entire project area, with

maximum flows being diverted in MarchApril, and a base flow of 1,000 cfs the remainder of the year.

Diversion of freshwater, sediments, and nutrients for the 5,000 cfs alternative is expected to increase SAV

and decrease marsh loss compared to the No Action Alternative. Increased SAV would create more

biomass and detrital inputs for the benthic community to process, furthering estuarine processes for the

benefit of the salt marsh community. The detritus export by the benthic community and the shelter found

along marsh edges make salt marshes important nursery areas for many commercially important fish and

shellfish.

The diversion of freshwater is expected to decrease salinities throughout the project area, particularly

during full flow in March and April and the weeks immediately following. A substantial portion of this

zone is expected to convert to fresh marsh within the first several years after project implementation. The

overall decrease in salinity is expected to displace benthic species less tolerant of freshwater. In addition,

the increase in sediment inputs over the project area could disrupt the benthic community and benthic

processes where accretion occurs. Nutrient inputs would likely impact the chemical and biological

processes of the benthic community, increasing blooms of phytoplankton, and subsequently

decomposition.

5.8.1.2.3 Cumulative

The reintroduction of freshwater, sediments, and nutrients from the Mississippi River is expected to

restore and maintain emergent marsh habitat over the long term in the project area. The increase in marsh

habitat and SAV would increase production of detritus and thereby, increase opportunity for the estuarine

benthic community to process energy through the detrital pathway. According to Mitsch and Gosselink

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(1993), the salt marsh is a major producer of detritus for both the salt marsh system and the adjacent

estuary. They point out that the detritus material exported from the marsh is more important to the estuary

than the phytoplankton-based production in the estuary. The cumulative impacts would include the

shifting of the benthic abundance, species composition, and species distribution toward those adapted to

fresher habitats, and increasing chemical, physical, and biological processes performed by the benthic

community. The enhancement of the benthic community through restoration and maintenance of

emergent marsh habitat would also benefit fish and other aquatic organisms that depend on estuarine

habitat and detritus export to meet all or part of their life cycles.

The cumulative impacts to the benthic resources would have a positive effect, particularly when evaluated

in concert with other Federal, state, local, and private conservation and restoration efforts. The positive

synergistic effect on the benthic resources in the project area would be greatest for the 35,000 cfs

alternative as compared the lower volume alternatives.

5.8.1.3 Alternative 2 – 10,000 cfs max Diversion

5.8.1.3.1 Direct

Direct impacts under the 10,000 cfs diversion alternative include the complete loss of existing benthic

communities in the footprint of the proposed construction and dredging activities. This area would

include 159 acres of intermediate marsh and 223 acres of shallow open water. Temporary increases in

turbidity, temperatures, and BOD, as well as temporary decreases in DO would contribute to further

mortality and displacement of the benthic community in the project area. In addition, ridge creation would

result in approximately 32 acres becoming unavailable for benthic aquatic fauna. However, following

construction, benthic organisms would likely recolonize aquatic habitats in the project area, and the

enhancement of freshwater marsh habitat by the diversion should be beneficial to numerous benthic

species. Introduction of additional freshwater into estuarine systems could have short-term impacts on

benthic populations in receiving waters as well. Introduction of freshwater flows from proposed features

would be expected to change benthic abundance, species composition, and species distribution. Changes

in benthic species assemblages would likely be similar to what is observed along present day estuarine

salinity gradients except that increased freshwater flows would shift the benthic community, displacing

marine species in favor of fresher and more estuarine, euryhaline species.

In addition, some benthic organisms from the Mississippi River would be expected to be entrained in the

immediate vicinity of the diversion inflow while it is in operation.

5.8.1.3.2 Indirect

Each of the 5,000, 10,000, 15,000, and 35,000 alternatives would freshen the entire project area, with

maximum flows being diverted in MarchApril, and a base flow of 1,000 cfs the remainder of the year.

Diversion of freshwater, sediments, and nutrients at a maximum of 10,000 cfs is expected to increase

SAV and decrease marsh loss to a greater degree than Alternative 1. Increased SAV would create more

biomass and detrital inputs for the benthic community to process, furthering estuarine processes for the

benefit of the salt marsh community. The detritus export by the benthic community and the shelter found

along marsh edges make salt marshes important nursery areas for many commercially important fish and

shellfish.

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The diversion of freshwater is expected to decrease salinities throughout the project area, particularly

during full flow in MarchApril and the weeks immediately following. A substantial portion of this zone

is expected to convert to fresh marsh within the first several years after project implementation. The

overall decrease in salinity is expected to displace benthic species less tolerant of freshwater. In addition,

the increase in sediment inputs over the project area could disrupt the benthic community and benthic

processes where accretion occurs. Nutrient inputs would likely impact the chemical and biological

processes of the benthic community, increasing blooms of phytoplankton, and subsequently

decomposition.

5.8.1.3.3 Cumulative

The reintroduction of freshwater, sediments, and nutrients from the Mississippi River is expected to

restore and maintain emergent marsh habitat over the long term in the project area. The increase in marsh

habitat and SAV would increase production of detritus and thereby, increase opportunity for the estuarine

benthic community to process energy through the detrital pathway. According to Mitsch and Gosselink

(1993), the salt marsh is a major producer of detritus for both the salt marsh system and the adjacent

estuary. They point out that the detritus material exported from the marsh is more important to the estuary

than the phytoplankton-based production in the estuary. The cumulative impacts would include the

shifting of the benthic abundance, species composition, and species distribution toward those adapted to

fresher habitats, and increasing chemical, physical, and biological processes performed by the benthic

community. The enhancement of the benthic community through restoration and maintenance of

emergent marsh habitat would also benefit fish and other aquatic organisms that depend on estuarine

habitat and detritus export to meet all or part of their life cycles.

The cumulative impacts to the benthic resources would have a positive effect, particularly when evaluated

in concert with other Federal, state, local, and private conservation and restoration efforts. The positive

synergistic effect on the benthic resources in the project area would be greater for the 35,000 cfs

alternative than for the lower volume alternatives.

5.8.1.4 Alternative 3 – 15,000 cfs max Diversion

5.8.1.4.1 Direct

Direct impacts under the 15,000 cfs diversion alternative include the complete loss of existing benthic

communities in the footprint of the proposed construction and dredging activities (203 acres of

intermediate marsh and 253 acres of shallow open water). Temporary increases in turbidity, temperatures,

and BOD, as well as temporary decreases in DO would contribute to further mortality and displacement

of the benthic community in the project area. In addition, ridge creation would result in approximately 32

acres becoming unavailable for benthic aquatic fauna. However, following construction, benthic

organisms would likely recolonize aquatic habitats in the project area, and the enhancement of freshwater

marsh habitat by the diversion should be beneficial to numerous benthic species. Introduction of

additional freshwater into estuarine systems could have short-term impacts on benthic populations in

receiving waters as well. Introduction of freshwater flows from proposed features would be expected to

change benthic abundance, species composition, and species distribution. Changes in benthic species

assemblages would likely be similar to what is observed along present day estuarine salinity gradients

except that increased freshwater flows would shift the benthic community, displacing marine species in

favor of fresher and more estuarine, euryhaline species.

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In addition, some benthic organisms from the Mississippi River would be expected to be entrained in the

immediate vicinity of the diversion inflow while it is in operation.

5.8.1.4.2 Indirect

Each of the 5,000, 10,000, 15,000, and 35,000 alternatives would freshen the entire project area, with

maximum flows being diverted in MarchApril, and a base flow of 1,000 cfs the remainder of the year.

Diversion of freshwater, sediments, and nutrients at a maximum of 10,000 cfs is expected to increase

SAV and decrease marsh loss to a greater degree than Alternatives 1 or 2. Increased SAV would create

more biomass and detrital inputs for the benthic community to process, furthering estuarine processes for

the benefit of the salt marsh community. The detritus export by the benthic community and the shelter

found along marsh edges make salt marshes important nursery areas for many commercially important

fish and shellfish.

The diversion of freshwater is expected to decrease salinities throughout the project area, particularly

during full flow in MarchApril and the weeks immediately following. A substantial portion of this zone

is expected to convert to fresh marsh within the first several years after project implementation. The

overall decrease in salinity is expected to displace benthic species less tolerant of freshwater. In addition,

the increase in sediment inputs over the project area could disrupt the benthic community and benthic

processes where accretion occurs. Nutrient inputs would likely impact the chemical and biological

processes of the benthic community, increasing blooms of phytoplankton, and subsequently

decomposition.

5.8.1.4.3 Cumulative

The reintroduction of freshwater, sediments, and nutrients from the Mississippi River is expected to

restore and maintain emergent marsh habitat over the long term in the project area. The increase in marsh

habitat and SAV would increase production of detritus and thereby, increase opportunity for the estuarine

benthic community to process energy through the detrital pathway. According to Mitsch and Gosselink

(1993), the salt marsh is a major producer of detritus for both the salt marsh system and the adjacent

estuary. They point out that the detritus material exported from the marsh is more important to the estuary

than the phytoplankton-based production in the estuary. The cumulative impacts would include the

shifting of the benthic abundance, species composition, and species distribution toward those adapted to

fresher habitats, and increasing chemical, physical, and biological processes performed by the benthic

community. The enhancement of the benthic community through restoration and maintenance of

emergent marsh habitat would also benefit fish and other aquatic organisms that depend on estuarine

habitat and detritus export to meet all or part of their life cycles.

The cumulative impacts to the benthic resources would have a positive effect, particularly when evaluated

in concert with other Federal, state, local, and private conservation and restoration efforts. The positive

synergistic effect on the benthic resources in the project area would be greatest for the 35,000 cfs

alternative when compared to the lower volume alternatives.

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5.8.1.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.8.1.5.1 Direct

Under the 35,000 cfs diversion alternative, the existing benthic communities in the footprint of the

proposed construction and dredging activities would be lost. This area would encompass 283 acres of

intermediate marsh and 363 acres of shallow open water. Temporary increases in turbidity, temperatures,

and BOD, as well as temporary decreases in DO would contribute to further mortality and displacement

of the benthic community in the project area. In addition, ridge creation would result in approximately 31

acres becoming unavailable for benthic aquatic fauna. However, following construction, benthic

organisms would likely recolonize aquatic habitats in the project area, and the enhancement of freshwater

marsh habitat by the diversion should be beneficial to numerous benthic species. Introduction of

additional freshwater into estuarine systems could have short-term impacts on benthic populations in

receiving waters as well. Introduction of freshwater flows from proposed features would be expected to

change benthic abundance, species composition, and species distribution. Changes in benthic species

assemblages would likely be similar to what is observed along present day estuarine salinity gradients

except that increased freshwater flows would shift the benthic community, displacing marine species in

favor of fresher and more estuarine, euryhaline species.

In addition, some benthic organisms from the Mississippi River would be expected to be entrained in the

immediate vicinity of the diversion inflow while it is in operation.

5.8.1.5.2 Indirect

Each of the 5,000, 10,000, 15,000, and 35,000 alternatives would freshen the entire project area, with

maximum flows being diverted in MarchApril, and a base flow of 1,000 cfs the remainder of the year.

Diversion of freshwater, sediments, and nutrients at a maximum of 35,000 cfs is expected to increase

SAV and decrease marsh loss to the greatest degree of all the alternatives evaluated in detail. Increased

SAV would create more biomass and detrital inputs for the benthic community to process, furthering

estuarine processes for the benefit of the salt marsh community. The detritus export by the benthic

community and the shelter found along marsh edges make salt marshes important nursery areas for many

commercially important fish and shellfish.

The diversion of freshwater is expected to decrease salinities throughout the project area, particularly

during full flow in MarchApril and the weeks immediately following. A substantial portion of this zone

is expected to convert to fresh marsh within the first several years after project implementation. The

overall decrease in salinity is expected to displace benthic species less tolerant of freshwater. In addition,

the increase in sediment inputs over the project area could disrupt the benthic community and benthic

processes where accretion occurs. Nutrient inputs would likely impact the chemical and biological

processes of the benthic community, increasing blooms of phytoplankton, and subsequently

decomposition.

5.8.1.5.3 Cumulative

The reintroduction of freshwater, sediments, and nutrients from the Mississippi River is expected to

restore and maintain emergent marsh habitat over the long term in the project area. The increase in marsh

habitat and SAV would increase production of detritus and thereby, increase opportunity for the estuarine

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benthic community to process energy through the detrital pathway. According to Mitsch and Gosselink

(1993), the salt marsh is a major producer of detritus for both the salt marsh system and the adjacent

estuary. They point out that the detritus material exported from the marsh is more important to the estuary

than the phytoplankton-based production in the estuary. The cumulative impacts would include the

shifting of the benthic abundance, species composition, and species distribution toward those adapted to

fresher habitats, and increasing chemical, physical, and biological processes performed by the benthic

community. The enhancement of the benthic community through restoration and maintenance of

emergent marsh habitat would also benefit fish and other aquatic organisms that depend on estuarine

habitat and detritus export to meet all or part of their life cycles.

The cumulative impacts to the benthic resources would have a positive effect, particularly when evaluated

in concert with other Federal, state, local, and private conservation and restoration efforts. The positive

synergistic effect on the benthic resources in the project area would be greatest for this alternative when

compared to the lower volume alternatives.

5.8.2 Plankton

This resource is institutionally significant because of the NEPA of 1969, the Coastal Zone Management

Act, and the Estuary Protection Act. This resource is technically significant because plankton provide a

major, direct food source for animals in the water column and in the sediments; plankton would be

responsible for at least 40 percent of the photosynthesis occurring on the earth; plankton would be

important for their role in nutrient cycling; plankton productivity is a major source of primary foodenergy for most estuarine systems throughout the world; and phytoplankton production is the major

source of autochthonous organic matter in most estuarine ecosystems (Day et al., 1989). This resource is

publicly significant because plankton form part of the lowest trophic food level for many larger organisms

important to commercial and recreational fishing. Historically, salinity appears to be the chief controlling

factor in the number of species present, while temperature, competition, and predation control the number

of individuals present (Perret et al. 1971). Further, the abundance of certain zooplankton could be

indicative of good fishing areas.

5.8.2.1 No Action Alternative (Future Without Project Conditions)

The No Action Alternative would result in the persistence of existing conditions including the continued

degradation and eventual loss of salt marsh and concomitant loss of long-term estuarine sustainability.

None of the potential negative effects of freshwater inflows to the project area would result.

5.8.2.1.1 Direct

Current rates of salt marsh loss would be expected to continue or increase with no additional input of

sediment, freshwater and nutrients from river water to the project area. No direct impacts to existing salt

marsh vegetation resulting from construction of the proposed diversion and associated features would

occur. No opportunities for beneficial reuse of marsh soil and substrate excavated for construction would

be realized.

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5.8.2.1.2 Indirect

Under the No Action Alternative, both man-made and natural processes would contribute to continued

loss of habitat/vegetation as the salt marshes convert to more open water conditions. This in turn would

lead to additional reductions in salt marsh plankton production and thus a loss in primary and secondary

food sources for salt marsh fish and wildlife. Plankton assemblages that currently inhabit the project area

would experience reductions in population as salinities increased. Further, under the No Action

Alternative it would be anticipated that the continued loss of salt marsh would eventually result in a

decrease of available nutrients and detritus, ultimately affecting plankton population dynamics. No

indirect benefits or impacts would occur as a result of construction and freshwater diversion into the salt

marsh.

In addition, there is a public health concern associated with the No Action Alternative. For example,

phytoplankton in more saline environments can cause blooms of Karenia breve (formerly known as

Gymnodinium breve), a dinoflagellate that has been associated with red tides. Red tides would be so

named because the prolific growth stains the water red. Toxins associated with red tides would be capable

of killing fish and shellfish. Red tide populations well below the fish kill level pose a serious problem for

public health through shellfish contamination. Bivalve shellfish, especially oysters, clams, and coquinas,

can accumulate so many toxins that they become toxic to humans. Public health concerns also emerge

from studies that show that the presence of airborne toxins have an impact on the human respiratory

system. Freshwater diversion has been utilized in some instances to attempt to reduce the spread of red

tides into coastal waters.

5.8.2.1.3 Cumulative

Cumulative impacts to plankton resources would primarily be related to the incremental impact of all

past, present, and future actions affecting plankton resources. Both man-made and natural processes

would contribute to the continued loss of vegetated habitats, including: continued erosion and subsidence,

increased saltwater intrusion, increased water velocities, and increased herbivory. It is predicted that

within the foreseeable future the lack of any reintroduction of nutrients and sediments to the estuarine

system would continue to produce conditions for significant losses of all marsh types throughout the

project area. As a result open-water habitats would continue to grow allowing for further intrusion of

saltwater into the marsh. This loss of emergent salt marsh habitat would have significant changes on

plankton communities and the organisms that depend on them for their life history requirements. Plankton

populations would continue to convert from primarily estuarine-dependent plankton species assemblages

and biomass to more marine and open water plankton species.

5.8.2.2 Alternative 1 – 5,000 cfs max Diversion

5.8.2.2.1 Direct

Direct impacts, primarily during the construction phase, of Alternative 1 would be similar to Alternative

4; however, the extent of the affected area would be greater in proportion to the increased construction

footprint. Operation of the 5,000 cfs diversion alternative would introduce fresh river water, sediment and

nutrients into the constructed outfall channels and existing distributary channels within the project area.

Impacts would result from the placement of three 15-ft x 15-ft box culverts. Additionally, there would be

direct impacts to plankton associated with the 32 acres of ridge and terrace creation and 139 acres of

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marsh creation  all developed utilizing dredged material from an adjacent 153 acres of canal being

reconfigured to convey freshwater, nutrient and sediments.

5.8.2.2.2 Indirect

Indirect impacts would also be similar to Alternative 4. Primary differences would be associated with the

period and depth of freshwater inundation. Increases in submersed aquatic vegetation (SAV) would likely

contribute to and be correlated with changes in plankton production and composition, especially in the

fresh, intermediate, and brackish zones (see submersed aquatic vegetation section 1.1.1). Changes in

plankton as a result of freshwater inundation would be expected to positively influence EFH within and

beyond the immediate outfall area of the diversion. Sediment delivery to the system would likely fall

short of the project goal.

5.8.2.2.3 Cumulative

Cumulative impacts to plankton resources would primarily be related to the synergistic effect of all past,

present, and future actions affecting plankton resources. Alternative 1 would have positive synergistic

effects on estuarine plankton resources when combined with other Federal, state, local, and private

restoration efforts. Notably, any future management actions would likely have cumulative impacts

relative to plankton species abundances, composition, and distribution.

5.8.2.3 Alternative 2 – 10,000 cfs max Diversion

5.8.2.3.1 Direct

Direct impacts, primarily during the construction phase, of Alternative 1 would be similar to Alternative

4; however, the extent of the affected area would be greater in proportion to the increased construction

footprint. Operation of the 10,000 cfs diversion alternative would introduce fresh river water, sediment

and nutrients into the constructed outfall channels and existing distributary channels within the project

area. Impacts would result from the placement of three 15-ft x 15-ft box culverts. Additionally, there

would be impacts to plankton associated with the 32 acres of ridge and terrace creation and 176 acres of

marsh creation  all developed utilizing dredged material from an adjacent 167 acres of canal being

reconfigured to convey freshwater, nutrient and sediments.

5.8.2.3.2 Indirect

Indirect impacts would also be similar to Alternative 4. Primary differences would be associated with the

period and depth of freshwater inundation. Increases in submersed aquatic vegetation (SAV) would likely

contribute to and be correlated with changes in plankton production and composition, especially in the

fresh, intermediate, and brackish zones (see submersed aquatic vegetation section 1.1.1). Changes in

plankton as a result of freshwater inundation would be expected to positively influence EFH within and

beyond the immediate outfall area of the diversion. Sediment delivery to the system would likely fall

short of the project goal.

5.8.2.3.3 Cumulative

Cumulative impacts to plankton resources would primarily be related to the synergistic effect of all past,

present, and future actions affecting plankton resources. Alternative 4 would have positive synergistic

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effects on estuarine plankton resources when combined with other Federal, state, local, and private

restoration efforts. Notably, any future management actions would likely have cumulative impacts

relative to plankton species abundances, composition, and distribution.

5.8.2.4 Alternative 3 – 15,000 cfs max Diversion

5.8.2.4.1 Direct

Direct impacts, primarily during the construction phase, of Alternative 1 would be similar to Alternative

4; however, the extent of the affected area would be greater in proportion to the increased construction

footprint. Operation of the 15,000 cfs diversion alternative would introduce fresh river water, sediment

and nutrients into the constructed outfall channels and existing distributary channels within the project

area. Impacts would result from the placement of ten 15-ft x 15-ft box culverts. Additionally, there would

be impacts to plankton associated with the 32 acres of ridge and terrace creation and 235 acres of marsh

creation  all developed utilizing dredged material from an adjacent 182 acres of canal being

reconfigured to convey freshwater, nutrient and sediments.

5.8.2.4.2 Indirect

Indirect impacts would also be similar to Alternative 4. Primary differences would be associated with the

period and depth of freshwater inundation. Increases in submersed aquatic vegetation (SAV) would likely

contribute to and be correlated with changes in plankton production and composition, especially in the

fresh, intermediate, and brackish zones (see submersed aquatic vegetation section 1.1.1). Changes in

plankton as a result of freshwater inundation would be expected to positively influence EFH within and

beyond the immediate outfall area of the diversion. Sediment delivery to the system would likely fall

short of the project goal.

5.8.2.4.3 Cumulative

Cumulative impacts to plankton resources would primarily be related to the synergistic effect of all past,

present, and future actions affecting plankton resources. Alternative 4 would have positive synergistic

effects on estuarine plankton resources when combined with other Federal, state, local, and private

restoration efforts. Notably, any future management actions would likely have cumulative impacts

relative to plankton species abundances, composition, and distribution.

5.8.2.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.8.2.5.1 Direct

Operation of the 35,000 cfs diversion alternative would introduce fresh river water, sediment and

nutrients into the constructed outfall channels and existing distributary channels within the project area.

During actual construction activities of project features there would be short-term direct impacts to

plankton populations due to increases in turbidity, low DO, and introduction of dredged sediments into

shallow open water areas. Impacts would result from the placement of ten 15-ft x 15-ft box culverts.

Additionally, there would be impacts to plankton associated with the 31 acres of ridge and terrace

creation and 385 acres of marsh creation  all developed utilizing dredged material from an adjacent 223

acres of canal being reconfigured to convey freshwater, nutrient and sediments. There would be long-term

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loss of shallow water habitats in some areas due to dredge disposal activities. However, overall, there is

an abundance of shallow open-water habitat in the project area available for use by plankton.

5.8.2.5.2 Indirect

Increases in freshwater flows and associated sediments and nutrients, along with changes in the salinity

gradient from proposed features would be expected to change plankton species assemblage, composition,

and distribution within a relatively short time frame. Plankton population dynamics would respond to

associated changes in nutrient cycling, enrichment, and fluxes, especially under different annual flow

regimes. Changes in plankton species assemblages would likely resemble what is observed along present

day estuarine salinity gradients as increased freshwater flows displace marine species in favor of fresher

and more estuarine, euryhaline species. Additionally, hypoxic conditions would be expected to occur less

often with the introduction of freshwater to the system which would contribute to increased abundances

of plankton, especially zooplankton. For example, while some zooplankton would be euryhaline, others

have distinct salinity preferences. Therefore, introduction of river water into estuarine systems can have

dramatic short-term impacts on plankton populations in adjacent coastal waters (Hawes and Perry, 1978).

Under this alternative, it is anticipated that the longer inundation period and more sediment would lead to

more plankton production  correlated with growth and establishment of more aquatic vegetation. In

addition, changes in plankton as a result of freshwater inundation would be expected to positively

influence EFH within and beyond the immediate outfall area of the diversion.

Increases in submersed aquatic vegetation (SAV) would contribute to changes in plankton production and

composition especially in the fresh, intermediate, and brackish zones (see submersed aquatic vegetation

section 1.1.1). Increased plant growth would result in greater production of organic detritus and

production of phytoplankton and zooplankton would increase particularly in areas where turbidity is not

limiting. These increases in plankton production would benefit larval and juvenile fishes and other aquatic

animals and, as a result, the harvest of sport and commercial finfish and shellfish that depend on these

microorganisms would increase.

Indirect impacts to plankton resources would primarily be related to increases in the export of dissolved

organic compounds and detritus from enhanced marsh habitats that would benefit local plankton

populations by increasing the planktonic food web. It is unknown whether proposed diversion flows and

associated nutrients would result in noxious blooms of blue-green algae, but there is likely some upper

limit to the assimilation of nutrients into estuarine waters, beyond which blooms would occur. Potentially,

freshwater diversion would increase sediments in the project area with accompanying minor increases in

trace metals and also increase agrochemicals. This nutrient enrichment could potentially lead to increased

algal blooms.

5.8.2.5.3 Cumulative

Cumulative impacts to plankton resources would primarily be related to the synergistic effect of all past,

present, and future actions affecting plankton resources. Alternative 4 would have positive synergistic

effects on estuarine plankton resources when combined with other Federal, state, local, and private

restoration efforts. It is anticipated that intertidal restoration efforts would result in greater resources for

phytoplankton and zooplankton due to export of dissolved organic compounds and detritus. Notably, any

future management actions would likely have cumulative impacts relative to plankton species

abundances, composition, and distribution.

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Additionally, public concerns have been raised regarding potential excessive changes in the salinity

gradient that would convert the existing estuarine habitats into purely freshwater and intermediate types.

Although there would be many proponents of freshwater and sediment diversions, some members of the

public would be concerned about possible unintended consequences of implementing this type of

restoration feature. Commercial and recreational fishermen would be concerned that the change in the

salinity regime often associated with a freshwater diversion, would cause loss or displacement of current

recreational and commercially valuable fishery species. As mentioned, in addition to altering salinity,

diversions could increase the amount of nutrients supplied to lakes and bays. Increased nutrients create

the possibility of algal blooms, which would be potentially detrimental to many aquatic organisms

including fish, shellfish, and invertebrates, and could contribute to the formation of hypoxic zones.

5.8.3 Other Aquatic Resources

No other aquatic communities would be anticipated to be significantly impacted by implementation of

any one of the alternatives in the MDWD project area.

5.9 FISHERIES

Although freshwater fisheries and long-term estuarine sustainability would be expected to benefit from

freshwater diversions, the potential for short-term losses to estuarine fisheries (e.g., oysters) must also be

considered in the evaluation of project alternatives.

5.9.1 No Action Alternative (Future Without Project

Conditions)

5.9.1.1 Direct

Under the No Action Alternative no direct impacts to freshwater, estuarine or marine fisheries would

occur. Current rates of marsh loss would be expected to continue with no additional input of sediment,

freshwater and nutrients from river water to the project area. Louisiana coastal marshes including the

MDWD project area would be recognized as an important and productive fisheries nursery habitat, and

conversion to open water reduces availability of this habitat. Moreover, juvenile fish and invertebrates

would be important food sources for migratory birds, such as wading birds and waterfowl, and the

conversion of marsh to open water can only reduce food abundance for these species.

5.9.1.2 Indirect

Continued conversion of emergent marsh to open water is expected to have long-term adverse impacts to

many fish species that depend on estuarine wetlands in the project area to meet life stage requirements.

Freshwater fish species that currently inhabit the project area would experience reductions in population

as salinities increase. Over time, indirect impacts of the No Action Alternative would result in a

substantial decrease in the quality of EFH in the project area, including nursery habitat and marsh edge in

the project area, and reduce the areas ability to support federally managed species. The abundances of

aquatic organisms would decrease, indirectly impacting species that would be linked in the food web to

directly affected species. The reduction in emergent wetlands would also result in shifts in predator/prey

relationships, a decline in fishery productivity, and reduced recreational fishing opportunities.

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5.9.1.3 Cumulative

Over the long term, without reintroduction of Mississippi River flows of sediment and nutrients to restore

and maintain emergent marsh habitat, the project area is likely to convert from a predominately estuarine

habitat to a predominately marine habitat, and populations of fish and other aquatic organisms that depend

on estuarine habitat in the project area to meet all or part of their life cycles would be adversely affected

by the reduction and eventual loss of this habitat.

5.9.2 Alternative 1 – 5,000 cfs diversion

5.9.2.1 Direct

Construction of the 5,000 cfs alternative is expected to have substantial but localized impacts to fisheries

resources in the immediate vicinity of the outfall management features. Sessile or slow moving

individuals or species in the construction footprint would likely suffer complete, albeit temporary, losses

during excavation of outfall channels and placement of excavated material into marsh creation areas. No

direct impacts to oyster would be anticipated to result from construction of Alternative 1, primarily

because the construction footprint is located in the upper portion of the project area, where existing

salinity conditions would be not favorable for oysters. Construction activities would temporarily increase

turbidity and BOD, and decrease DO. These temporary conditions would likely displace more mobile

fisheries species from the construction areas. Following construction, displaced fish would likely return to

the project area and some sessile or slow-moving species would recolonize enlarged channels. The

notched weirs included as an outfall management feature could have some modifying impact on fisheries

access to the area causing species to use other routes. As reflected in the WVA assessment (included with

Appendix B), aquatic organism access under with project conditions is expected to be approximately 60

percent of optimum (without project access is assumed to be at optimum level, or 100 percent). Negative

impacts to fisheries resulting from construction of this alternative would be less than for the 10,000,

15,000, and 35,000 cfs alternatives (except for restrictions on fish access due to notched weirs, which

would be the same for all alternatives), but positive impacts from marsh creation using excavated material

would also be less than those expected for the larger diversion alternatives.

5.9.2.2 Indirect

Implementation of the 5,000 cfs alternative following the operational plan evaluated in the hydraulic

modeling and WVA analysis (full flow in MarchApril; 1,000 cfs rest of year) is expected to freshen the

entire project area while the diversion is at full flow and for several weeks after the return to maintenance

flow operation. Water levels, velocities, and turbidity in outfall areas would be all expected to increase

during full flow conditions. Entrainment of eggs, larvae or fry of Mississippi River fish species in the

immediate vicinity of the diversion inflow could occur during operation of the structure. To mitigate for

these impacts, one or more of the box culverts could be modified to accommodate fish passage.

The notched weirs are expected to slow channel flow velocities and retain sediment and some nutrients

within the project area. While these structures will reduce channel cross-sections where they are located,

they are not anticipated to completely block fisheries access between the project area and River aux

Chenes. Additional details on the expected effects of notched weirs is provided in the WVA analysis at

the end of Appendix B. The impact to natural oyster settlement and growth will be less than the 35,000

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cfs alternative due to the quicker recovery from the lower pulse. See Section 5.15.15.2 for a discussion on

impacts to oyster leases.

Freshwater fishery species, such as crawfish, catfish, largemouth bass, and other sunfish should benefit

from implementation of the diversion.

Freshwater inflow is an important component of circulation and flushing processes in estuaries that assist

in the transportation of planktonic organisms, nutrients, and detritus to the Gulf of Mexico. Over the long

term, operation of the diversion is expected to help support the aquatic food web of marine fishery

species. An aquatic model will be conducted during PED to help evaluate potential impacts (see Section

3.8.9).

5.9.2.3 Cumulative

Implementation of the 5,000 cfs diversion alternative would have positive synergistic effects on fishery

resources when combined with other Federal, state, local, and private restoration efforts, including the

Caernarvon diversion. This alternative would protect, create and nourish important and essential estuarine

wetland habitats used by fishery populations for spawning, cover, nursery, and other life stage

requirements. Localized increases in important fishery habitats could contribute to increased productivity

on a local (basin) scale. However, the incremental effect of this alternative is unlikely to benefit

populations of these species on a continental scale.

5.9.3 Alternative 2 – 10,000 cfs max Diversion

5.9.3.1 Direct

Construction of the 10,000 cfs alternative is expected to have substantial but localized impacts to fisheries

resources in the immediate vicinity of the outfall management features. Sessile or slow moving

individuals or species in the construction footprint would likely experience complete, albeit temporary,

losses during excavation of outfall channels and placement of excavated material into marsh creation

areas. No direct impacts to oysters would be anticipated to result from construction of Alternative 2,

primarily because the construction footprint is located in the upper portion of the project area, where

existing salinity conditions would be not favorable for oysters. Construction activities would temporarily

increase turbidity, temperatures and BOD; and decrease DO. These temporary conditions would likely

displace more mobile fisheries species from the construction area. Following construction, displaced fish

would likely return to the project area and some sessile or slow-moving species would recolonize

enlarged channels. The notched weirs included as an outfall management feature could have some

negative impact on fisheries access to the area. As reflected in the WVA assessment (included with

Appendix B), aquatic organism access under with project conditions is expected to be approximately 60

percent of optimum (without-project access is assumed to be at optimum level, or 100 percent). Negative

impacts to fisheries resulting from construction of this alternative would be less than for the 15,000 and

35,000 cfs alternatives (except for restrictions on fish access due to notched weirs, which would be the

same for all alternatives), but positive impacts from marsh creation using excavated material would also

be less than those expected for the larger diversion alternatives.

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5.9.3.2 Indirect

Implementation of the 10,000 cfs alternative following the operational plan evaluated in the hydraulic

modeling and WVA analysis (full flow in MarchApril; 1,000 cfs rest of year) is expected to freshen the

entire project area and beyond River aux Chenes to a portion of the Caernarvon sub basin while the

diversion is at full flow and for several weeks after the return to maintenance flow operation. Water

levels, velocities, and turbidity in outfall areas would be all expected to increase during full flow

conditions. Entrainment of eggs, larvae or fry of Mississippi River fish species in the immediate vicinity

of the diversion inflow could occur during operation of the structure. To mitigate for these impacts, one or

more of the box culverts could be modified into a fish passage.

The notched weirs are expected to slow channel flow velocities and retain sediment and some nutrients

within the project area. While these structures will reduce channel cross-sections where they are located,

they are not anticipated to completely block fisheries access between the project area and River aux

Chenes. Additional details on the expected effects of notched weirs is provided in the WVA analysis at

the end of Appendix B. The impact to natural oyster settlement and growth will be less than the 35,000

cfs alternative due to the quicker recovery from the lower pulse. See Section 5.15.15.2 for a discussion on

impacts to oyster leases.

Freshwater fishery species, such as crawfish, catfish, largemouth bass, and other sunfish should benefit

from implementation of the diversion. However, decreases in salinity resulting from operation of the

diversion could disrupt nursery functions of some marine species by affecting food and habitat

availability. Some fishery species would be impacted by anticipated decreases in salinity and water

temperature, and increased turbidity during maximum flow periods. Less freshwater tolerant species, such

as brown shrimp and spotted seatrout, could be displaced from the northwestern portion of the project

area. An aquatic model will be conducted during PED to help evaluate potential impacts (see Section

3.8.9).

5.9.3.3 Cumulative

Implementation of the 10,000 cfs diversion alternative would have positive synergistic effects on fishery

resources when combined with other Federal, state, local, and private restoration efforts, including the

Caernarvon diversion. This alternative would protect, create and nourish important and essential estuarine

wetland habitats used by fishery populations for spawning, cover, nursery, and other life stage

requirements. Localized increases in important fishery habitats could contribute to increased productivity

on a local (basin) scale. However, the incremental effect of this alternative is unlikely to benefit

populations of these species on a continental scale.

5.9.4 Alternative 3 – 15,000 cfs max Diversion

5.9.4.1 Direct

Construction of the 15,000 cfs alternative is expected to have substantial but localized impacts to fisheries

resources in the immediate vicinity of the outfall management features. Sessile or slow moving

individuals or species in the construction footprint would likely experience complete, albeit temporary,

losses during excavation of outfall channels and placement of excavated material into marsh creation

areas. No direct impacts to oysters would be anticipated to result from construction of Alternative 3,

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primarily because the construction footprint is located in the upper portion of the project area, where

existing salinity conditions would be not favorable for oysters. Construction activities would temporarily

increase turbidity, temperatures and BOD; and decrease DO. These temporary conditions would likely

displace more mobile fisheries species from the construction area. Following construction, displaced fish

would likely return to the project area and some sessile or slow-moving species would recolonize

enlarged channels. The notched weirs included as an outfall management feature could have some

negative impact on fisheries access to the area. As reflected in the WVA assessment (included with

Appendix B), aquatic organism access under with project conditions is expected to be approximately 60

percent of optimum (without project access is assumed to be at optimum level, or 100 percent). Negative

impacts to fisheries resulting from construction of this alternative would be less than for the 35,000 cfs

alternative (except for restrictions on fish access due to notched weirs, which would be the same for all

alternatives), but positive impacts from marsh creation using excavated material would also be less than

those expected for the larger diversion alternatives.

5.9.4.2 Indirect

Implementation of the 15,000 cfs alternative following the operational plan evaluated in the hydraulic

modeling and WVA analysis (full flow in MarchApril; 1,000 cfs rest of year) is expected to freshen the

entire project area and beyond River aux Chenes to a portion of the Caernarvon sub basin while the

diversion is at full flow and for several weeks after the return to maintenance flow operation. Water

levels, velocities, and turbidity in outfall areas would be all expected to increase during full flow

conditions. Entrainment of eggs, larvae or fry of Mississippi River fish species in the immediate vicinity

of the diversion inflow could occur during operation of the structure. To mitigate for these impacts, one or

more of the box culverts could be modified to accommodate fish passage.

The notched weirs are expected to slow channel flow velocities and retain sediment and some nutrients

within the project area. While these structures will reduce channel cross-sections where they are located,

they are not anticipated to completely block fisheries access between the project area and River aux

Chenes. Additional details on the expected effects of notched weirs is provided in the WVA analysis at

the end of Appendix B. The impact to natural oyster settlement and growth will be less than the 35,000

cfs alternative due to the quicker recovery from the lower pulse. See Section 5.15.15.2 for a discussion on

impacts to oyster leases.

Freshwater fishery species, such as crawfish, catfish, largemouth bass, and other sunfish should benefit

from implementation of the diversion. However, decreases in salinity resulting from operation of the

diversion could disrupt nursery functions of some marine species by affecting food and habitat

availability. Some fishery species would be impacted by anticipated decreases in salinity and water

temperature, and increased turbidity during maximum flow periods. Less freshwater tolerant species, such

as brown shrimp and spotted seatrout, could be displaced from the northwestern portion of the project

area.

Freshwater inflow is an important component of circulation and flushing processes in estuaries that assist

in the transportation of planktonic organisms, nutrients, and detritus to the Gulf of Mexico. Over the long

term, operation of the diversion is expected to help support the aquatic food web of marine fishery

species. An aquatic model will be conducted during PED to help evaluate potential impacts (see Section

3.8.9).

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5.9.4.3 Cumulative

Implementation of the 15,000 cfs diversion alternative would have positive synergistic effects on fishery

resources when combined with other Federal, state, local, and private restoration efforts, including the

Caernarvon diversion. This alternative would protect, create and nourish important and essential estuarine

wetland habitats used by fishery populations for spawning, cover, nursery, and other life stage

requirements. Localized increases in important fishery habitats could contribute to increased productivity

on a local (basin) scale. However, the incremental effect of this alternative is unlikely to measurably

benefit populations of these species on a continental scale.

5.9.5 Alternative 4 – 35,000 cfs max Diversion

(Recommended Plan)

5.9.5.1 Direct

Construction of the 35,000 cfs alternative is expected to have substantial but localized impacts to fisheries

resources in the immediate vicinity of the outfall management features. Sessile or slow moving

individuals or species in the construction footprint would likely experience complete, albeit temporary,

losses during excavation of outfall channels and placement of excavated material into marsh creation

areas. No direct impacts to oysters would be anticipated to result from construction of Alternative 4,

primarily because the construction footprint is located in the upper portion of the project area, where

existing salinity conditions would be not favorable for oysters. Construction activities would temporarily

increase turbidity, temperatures and BOD; and decrease DO. These temporary conditions would likely

displace more mobile fisheries species from the construction area. Following construction, displaced fish

would likely return to the project area and some sessile or slow-moving species would recolonize

enlarged channels. The notched weirs included as an outfall management feature could have some

negative impact on fisheries access to the area. As reflected in the WVA assessment (included with

Appendix B), aquatic organism access under with project conditions is expected to be approximately 60

percent of optimum (without project access is assumed to be at optimum level, or 100 percent). Negative

impacts to fisheries resulting from construction of this alternative would be greater than for the 5,000,

10,000, and 15,000 cfs alternatives (except for restrictions on fish access due to notched weirs, which

would be the same for all alternatives), but positive impacts from marsh creation using excavated material

would also be greater than those expected for the smaller diversion alternatives.

5.9.5.2 Indirect

Implementation of the 35,000 cfs alternative following the operational plan evaluated in the hydraulic

modeling and WVA analysis (full flow in MarchApril; 1,000 cfs rest of year) is expected to freshen the

entire project area and beyond River aux Chenes to a substantial portion of the Caernarvon sub basin

while the diversion is at full flow and for several weeks after the return to maintenance flow operation.

Water levels, velocities, and turbidity in outfall areas would be all expected to increase during full flow

conditions. Entrainment of eggs, larvae or fry of Mississippi River fish species in the immediate vicinity

of the diversion inflow could occur during operation of the structure. To mitigate for these impacts, one or

more of the box culverts could be modified to accommodate fish passage.

The notched weirs are expected to slow channel flow velocities and retain sediment and some nutrients

within the project area. While these structures will reduce channel cross-sections where they are located,

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they are not anticipated to completely block fisheries access between the project area and River aux

Chenes. Additional details on the expected effects of notched weirs is provided in the WVA analysis at

the end of Appendix B.

Freshwater fishery species, such as crawfish, catfish, largemouth bass, and other sunfish should benefit

from implementation of the diversion. However, decreases in salinity resulting from operation of the

diversion could disrupt nursery functions of some marine species by affecting food and habitat

availability. Some fishery species would be impacted by anticipated decreases in salinity and water

temperature, and increased turbidity during maximum flow periods. Less freshwater tolerant species, such

as brown shrimp and spotted seatrout, could be displaced from the northwestern portion of the project

area. Comparison of Figures 4.6 and 5.3 demonstrates that there is very little potential to impact natural

oyster settlement or growth. See Section 5.15.15.2 for a discussion on impacts to oyster leases. If this

diversion were operated fully open outside the 2-month window that is described in the document, then

there could be significantly different impacts with some potentially being very negative.

Freshwater inflow is an important component of circulation and flushing processes in estuaries that assist

in the transportation of planktonic organisms, nutrients, and detritus to the Gulf of Mexico. Over the long

term, operation of the diversion is expected to help support the aquatic food web of marine fishery

species. An aquatic model will be conducted during PED to help evaluate potential impacts (see Section

3.8.9).

5.9.5.3 Cumulative

Implementation of the 35,000 cfs diversion alternative would have positive synergistic effects on fishery

resources when combined with other Federal, state, local, and private restoration efforts, including the

Caernarvon diversion. This alternative would protect, create and nourish important and essential estuarine

wetland habitats used by fishery populations for spawning, cover, nursery, and other life stage

requirements. Localized increases in important fishery habitats could contribute to increased productivity

on a local (basin) scale. However, the incremental effect of this alternative is less likely to measurably

benefit populations of these species on a continental scale.

5.10 ESSENTIAL FISH HABITAT (EFH)

5.10.1 No Action Alternative (Future Without Project

Conditions)

5.10.1.1 Direct

The No Action Alternative (no construction of river diversion structure or associated outfall management

features) would have no direct impact on EFH.

5.10.1.2 Indirect

Indirect impacts of not implementing wetland creation/nourishment and shoreline protection features

would result in the persistence of existing conditions resulting in the conversion of categories of EFH,

such as estuarine marsh and SAV, to marine water column and mud, sand, or shell substrates is expected

to continue. Over time, the No Action Alternative would result in the conversion of emergent marsh to

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open water. Substantial decreases in the quality of EFH in the project area would reduce the areas ability

to support federally managed species.

5.10.1.3 Cumulative

Cumulative impacts would be the synergistic effect of the No Action Alternative on EFH with the

additive combination of similar EFH degradation and losses throughout coastal Louisiana, as well as the

benefits and impacts of other state and Federal projects in the vicinity. Continued conversion of existing

marsh to shallow open-water habitats anticipated with the No Action Alternative would contribute to

declining quality of EFH, particularly nursery habitat for larval and juvenile fish and shrimp species.

5.10.2 Alternative 1 – 5,000 cfs max Diversion

5.10.2.1 Direct

Direct impacts associated with construction of the 5,000 cfs diversion and associated outfall management

features include the disturbance and displacement of managed species in the construction footprint (144

acres of intermediate marsh and 187 acres of shallow open water). Adult and juvenile fish would be

expected to move out of the area during construction. Ridge creation would result in approximately 32

acres becoming unavailable for fishery species, and notched weirs at River aux Chenes and at the end of

the outfall channel could reduce fisheries access into the project area. However, this loss of EFH would

be offset by expected increases in the quality of EFH in the marsh creation sites.

5.10.2.2 Indirect

Implementation of the 5,000 cfs diversion following the operational plan evaluated in the hydraulic

modeling and WVA analysis (full flow in MarchApril; 1,000 cfs rest of year) is expected to freshen the

entire project area while the diversion is at full flow and for several weeks after the return to maintenance

flow operation. The accretion of sediment and input of nutrients is expected to benefit estuarine EFH

within and beyond the immediate outfall area of the diversion. This alternative is projected to increase

SAV in the project area and decrease emergent marsh loss across all marsh zones (intermediate, brackish,

and saline) over the 50-year planning horizon. These changes in the project area would not only increase

the areal extent of EFH, but would also improve the quality of EFH for several managed species.

Diversion of freshwater, sediments and nutrients into the project area under the evaluated operational plan

is expected to decrease salinities throughout the project area, particularly within the existing intermediate

marsh zone. A substantial portion of this zone is expected to convert to fresh marsh within the first

several years after project implementation. Water levels, velocities, and turbidity in outfall areas would be

all expected to increase during full flow conditions. High nutrient levels could result in blooms of algae

and phytoplankton, and subsequent decomposition of these organisms could decrease DO levels of water

bodies within the project area. These changes could result in localized adverse impacts to marine fishery

productivity, particularly when the diversion is at full flow. The operational plan used to evaluate all

diversion alternatives was developed to avoid or minimize these adverse impacts to marine fisheries and

EFH while maximizing sediment and nutrient input to the extent practicable to meet project objectives.

While this alternative has similar potential for negative impacts to marine fisheries and EFH as the

10,000, 15,000, and 35,000 diversions, its capacity for positive impacts to these resources would be less

than for the larger alternatives.

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5.10.2.3 Cumulative

Cumulative impacts would be the synergistic effect with the additive combination of impacts and benefits

for overall net acres created, nourished, and protected by other Federal, state, local, and private restoration

efforts. Implementation of this alternative would be expected to have a positive synergistic effect on EFH

in the project area, but to a lesser extent than the effect anticipated for the larger diversion alternatives.

5.10.3 Alternative 2 – 10,000 cfs max Diversion

5.10.3.1 Direct

Direct impacts associated with construction of the 10,000 cfs diversion and associated outfall

management features include the disturbance and displacement of managed species in the construction

footprint (159 acres of intermediate marsh and 223 acres of shallow open water). Adult and juvenile fish

would be expected to move out of the area during construction. Ridge creation would result in

approximately 32 acres becoming unavailable for fishery species, and notched weirs at River aux Chenes

and at the end of the outfall channel could reduce fisheries access into the project area. However, this loss

of EFH would be offset by expected increases in the quality of EFH in the marsh creation sites.

5.10.3.2 Indirect

Implementation of the 10,000 cfs diversion following the operational plan evaluated in the hydraulic

modeling and WVA analysis (full flow in MarchApril; 1,000 cfs rest of year) is expected to freshen the

entire project area while the diversion is at full flow and for several weeks after the return to maintenance

flow operation. The accretion of sediment and input of nutrients is expected to benefit estuarine EFH

within and beyond the immediate outfall area of the diversion. This alternative is projected to increase

SAV in the project area and decrease emergent marsh loss across all marsh zones (intermediate, brackish,

and saline) over the 50-year planning horizon. These changes in the project area would not only increase

the aerial extent of EFH, but would also improve the quality of EFH for several managed species.

Diversion of freshwater, sediments and nutrients into the project area under the evaluated operational plan

is expected to decrease salinities throughout the project area, particularly within the existing intermediate

marsh zone. A substantial portion of this zone is expected to convert to fresh marsh within the first

several years after project implementation. Water levels, velocities, and turbidity in outfall areas would be

all expected to increase during full flow conditions. High nutrient levels could result in blooms of algae

and phytoplankton, and subsequent decomposition of these organisms could decrease DO levels of water

bodies within the project area. These changes could result in localized adverse impacts to marine fishery

productivity, particularly when the diversion is at full flow. The operational plan used to evaluate all

diversion alternatives was developed to avoid or minimize these adverse impacts to marine fisheries and

EFH while maximizing sediment and nutrient input to the extent practicable to meet project objectives.

While this alternative has similar potential for negative impacts to marine fisheries and EFH as the 15,000

and 35,000 diversions, its capacity for positive impacts to these resources is less than for the larger

alternatives.

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5.10.3.3 Cumulative

Cumulative impacts would be the synergistic effect with the additive combination of impacts and benefits

for overall net acres created, nourished, and protected by other Federal, state, local, and private restoration

efforts. Implementation of this alternative would be expected to have a positive synergistic effect on EFH

in the project area, but to a lesser extent than the effect anticipated for the larger diversion alternatives.

5.10.4 Alternative 3 – 15,000 cfs max Diversion

5.10.4.1 Direct

Direct impacts associated with construction of the 15,000 cfs diversion and associated outfall

management features include the disturbance and displacement of managed species in the construction

footprint (203 acres of intermediate marsh and 253 acres of shallow open water). Adult and juvenile fish

would be expected to move out of the area during construction. Ridge creation would result in

approximately 32 acres becoming unavailable for fishery species, and notched weirs at River aux Chenes

and at the end of the outfall channel could reduce fisheries access into the project area. However, this loss

of EFH would be offset by expected increases in the quality of EFH in the marsh creation sites.

5.10.4.2 Indirect

Implementation of the 15,000 cfs diversion following the operational plan evaluated in the hydraulic

modeling and WVA analysis (full flow in MarchApril; 1,000 cfs rest of year) is expected to freshen the

entire project area while the diversion is at full flow and for several weeks after the return to maintenance

flow operation. The accretion of sediment and input of nutrients is expected to benefit estuarine EFH

within and beyond the immediate outfall area of the diversion. This alternative is projected to increase

SAV in the project area and decrease emergent marsh loss across all marsh zones (intermediate, brackish,

and saline) over the 50-year planning horizon. These changes in the project area would not only increase

the aerial extent of EFH, but would also improve the quality of EFH for several managed species.

Diversion of freshwater, sediments and nutrients into the project area under the evaluated operational plan

is expected to decrease salinities throughout the project area, particularly within the existing intermediate

marsh zone. A substantial portion of this zone is expected to convert to fresh marsh within the first

several years after project implementation. Water levels, velocities, and turbidity in outfall areas would be

all expected to increase during full flow conditions. High nutrient levels could result in blooms of algae

and phytoplankton, and subsequent decomposition of these organisms could decrease DO levels of water

bodies within the project area. These changes could result in localized adverse impacts to marine fishery

productivity, particularly when the diversion is at full flow. The operational plan used to evaluate all

diversion alternatives was developed to avoid or minimize these adverse impacts to marine fisheries and

EFH while maximizing sediment and nutrient input to the extent practicable to meet project objectives.

While this alternative has similar potential for negative impacts to marine fisheries and EFH as the 35,000

diversion, its capacity for positive impacts to these resources is less than for the larger alternative.

5.10.4.3 Cumulative

Cumulative impacts would be the synergistic effect with the additive combination of impacts and benefits

for overall net acres created, nourished, and protected by other Federal, state, local, and private restoration

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efforts. Implementation of this alternative would be expected to have a positive synergistic effect on EFH

in the project area, but to a lesser extent than the effect anticipated for the largest diversion alternative.

5.10.5 Alternative 4 – 35,000 cfs max Diversion

(Recommended Plan)

5.10.5.1 Direct

Direct impacts associated with construction of the 35,000 cfs diversion and associated outfall

management features include the disturbance and displacement of managed species in the construction

footprint (283 acres of intermediate marsh and 363 acres of shallow open water). Adult and juvenile fish

would be expected to move out of the area during construction. Ridge creation would result in

approximately 31 acres becoming unavailable for fishery species, and notched weirs at River aux Chenes

and at the end of the outfall channel could reduce fisheries access into the project area. However, this loss

of EFH would be offset by expected increases in the quality of EFH in the marsh creation sites.

5.10.5.2 Indirect

Implementation of the 35,000 cfs diversion following the operational plan evaluated in the hydraulic

modeling and WVA analysis (full flow in MarchApril; 1,000 cfs rest of year) is expected to freshen the

entire project area while the diversion is at full flow and for several weeks after the return to maintenance

flow operation. The accretion of sediment and input of nutrients is expected to benefit estuarine EFH

within and beyond the immediate outfall area of the diversion. This alternative is projected to increase

SAV in the project area and decrease emergent marsh loss across all marsh zones (intermediate, brackish,

and saline) over the 50-year planning horizon. These changes in the project area would not only increase

the aerial extent of EFH, but would also improve the quality of EFH for several managed species.

Diversion of freshwater, sediments and nutrients into the project area under the evaluated operational plan

is expected to decrease salinities throughout the project area, particularly within the existing intermediate

marsh zone. A substantial portion of this zone is expected to convert to fresh marsh within the first

several years after project implementation. Water levels, velocities, and turbidity in outfall areas would be

all expected to increase during full flow conditions. High nutrient levels could result in blooms of algae

and phytoplankton, and subsequent decomposition of these organisms could decrease DO levels of water

bodies within the project area. These changes could result in localized adverse impacts to marine fishery

productivity, particularly when the diversion is at full flow. The operational plan used to evaluate all

diversion alternatives was developed to avoid or minimize these adverse impacts to marine fisheries and

EFH while maximizing sediment and nutrient input to the extent practicable to meet project objectives.

While this alternative has similar potential for negative impacts to marine fisheries and EFH as the 5,000,

10,000, or 15,000 diversions, its capacity for positive impacts to these resources is greater than for the

smaller alternatives.

5.10.5.3 Cumulative

Cumulative impacts would be the synergistic effect with the additive combination of impacts and benefits

for overall net acres created, nourished, and protected by other Federal, state, local, and private restoration

efforts. Implementation of this alternative would be expected to have a higher positive synergistic effect

on EFH in the project area than the effect anticipated for the smaller diversion alternatives.

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5.11 THREATENED AND ENDANGERED SPECIES

5.11.1 No Action Alternative (Future Without Project

Conditions)

5.11.1.1 Direct

No federally listed threatened or endangered species would be known to occur within the project area

boundary (USFWS, 2010). The No Action Alternative (no construction of a river diversion structure and

associated outfall management features in the project area) would have no direct impacts on listed species

or their critical habitat in the project area.

5.11.1.2 Indirect

The primary consequence of not implementing a river diversion in the project area would be the

continued degradation and loss of estuarine wetland habitats used by many different fish and wildlife

species for shelter, nesting, feeding, roosting, cover, nursery, and other life requirements. The loss and

deterioration of transitional wetland habitats over time could continue to indirectly affect, to an

undetermined degree, all listed species that could potentially utilize the Breton Sound basin including:

Gulf sturgeon, green sea turtle, hawksbill sea turtle, Kemps ridley sea turtle, leatherback sea turtle,

loggerhead sea turtle, brown pelican, piping plover, and the West Indian manatee.

5.11.1.3 Cumulative

Adverse cumulative impacts associated with the No Action Alternative would be the additive effect of the

continued deterioration of habitat quality and quantity in the project area with continued coastal land

losses and deterioration of critical habitats in other parts of southeastern Louisiana and the Gulf Coast.

Cumulative effects on listed species would be offset, to some degree, by the positive impacts of

implementing other state and Federal projects.

5.11.2 Alternative 1 – 5,000 cfs max Diversion

5.11.2.1 Direct

Direct impacts associated with construction of the 5,000 cfs diversion and associated outfall management

features could potentially include disturbance and displacement of individuals of some threatened or

endangered species that could potentially occur within the project area boundary. The construction

footprint for this alternative is limited in size relative to the project area (<1.0 percent) and does not

encroach on critical habitat for any listed species. For these reasons, construction of the proposed

diversion and associated outfall management features would not jeopardize the continued existence of any

listed species or destroy or adversely modify critical habitat.

5.11.2.2 Indirect

Implementation of the 5,000 cfs diversion alternative would divert water, sediments and nutrients from

the Mississippi River into the project area. Water diversions are used for flood control, water supply, and

habitat restoration in the lower Mississippi River (LMR) but their impacts on imperiled sturgeon

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populations are unknown. Corps-sponsored sampling efforts have shown catch data that suggests that

pallid sturgeon populations decline as you progress further downstream (RM 0 to RM 320). Pallid and

shovelnose sturgeon, as well as evidence of recruitment, are noticeably present with RM 80160 of the

LMR. The proposed diversion at Violet will be located at RM 85. This falls within a reach of the MRGO

that ERDC has shown has a population of pallid sturgeon that are showing signs of recruitment. This

increased presence of adult, sub-adult, post-larval, and larval pallid sturgeon within the LMR suggests

that there is an increased potential of entrainment of small sized sturgeon in diversions. The extent of

impacts to this sturgeon population from entrainment in water diversion structures is currently not

quantifiable. Further population analysis is needed to be able to project the size of the LMR pallid

population and what impact pallid sturgeon entrainment has on this population. Given this current

information CEMVN concludes that there is a risk of entrainment of pallid sturgeon by this diversion

structure and that therefore the proposed MDWD project May Affect the species. Appendix A presents

a Biological Assessment that describes those factors used in determining the potential impacts of the

proposed action on pallid sturgeon. No critical habitat for pallid sturgeon has been identified in the

vicinity of the White Ditch project area.

5.11.2.3 Cumulative

Cumulative impacts to listed species would be related to the incremental impacts of the anticipated

restoration features being constructed within the vicinity of the proposed action. The combination of this

effort with the numerous other restoration projects occurring in southeastern Louisiana will be the

slowing of the rate of shoreline retreat and restoring some of the delicate wetland habitats within the area.

These coastal habitats are requisites for some portion of the life cycle of all of the listed species that occur

within the project area. The improvement of this habitat will reduce at least one stressor that is hindering

the recovery of these T&E species. Cumulative impacts to the pallid sturgeon resulting from entrainment

by freshwater diversion structures cannot be determined at this time. Further population analysis is

needed to be able to determine what the additive effect entrainment from all the existing and proposed

freshwater and sediment diversion structures being constructed in the lower Mississippi River would have

on the species.

5.11.3 Alternative 2 – 10,000 cfs max Diversion

5.11.3.1 Direct

Impacts would be similar to Alternative 1 except this alternative includes additional restoration measures

and a larger diversion structure not identified in Alternative 1. Direct impacts associated with construction

of the 10,000 cfs diversion and associated outfall management features could potentially include

disturbance and displacement of individuals of some threatened or endangered species that could

potentially occur within the project area boundary. The construction footprint for this alternative is

limited in size relative to the project area (<1.0 percent) and does not encroach on critical habitat for any

listed species. For these reasons, construction of the proposed diversion and associated outfall

management features would not jeopardize the continued existence of any listed species or destroy or

adversely modify critical habitat.

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5.11.3.2 Indirect

Impacts would be similar to Alternative 1 except this alternative includes additional restoration measures

and a larger diversion structure not identified in Alternative 1. Implementation of the 10,000 cfs diversion

alternative would divert water, sediments and nutrients from the Mississippi River into the project area.

This could potentially result in the entrainment of larval and YOY, and adult fish into the marsh and open

water of the project area, particularly when the diversion is flowing at full capacity. Entrainment of larval

YOY, and adult fish could potentially include individual specimens of federally listed species such as the

pallid sturgeon, if these would be present in the immediate vicinity of the diversion intake. Appendix A

presents a Biological Assessment that describes those factors used in determining the potential impacts of

the proposed action on pallid sturgeon. No critical habitat for pallid sturgeon has been identified in the

vicinity of the White Ditch project area. While there is a potential for individuals of the species to be

adversely affected by entrainment during operation of the diversion, the proposed project is not

considered likely to jeopardize the continued existence of pallid sturgeon in the lower Mississippi River.

5.11.3.3 Cumulative

Impacts would be similar to Alternative 1 except this alternative includes additional restoration measures

and a larger diversion structure not identified in Alternative 1. Implementation of the diversion project is

anticipated to have positive synergistic effects on listed species when combined with other Federal, state,

local, and private restoration efforts. Cumulative impacts to listed species would be related to the

incremental impacts of the anticipated restoration of wetland habitat, compared to all past, present, and

future restoration activities that have or would increase and enhance all coastal wetland habitats.

5.11.4 Alternative 3 – 15,000 cfs max Diversion

5.11.4.1 Direct

Impacts would be similar to Alternative 2 except this alternative includes additional restoration measures

and a larger diversion structure not identified in Alternative 2. Direct impacts associated with construction

of the 15,000 cfs diversion and associated outfall management features could potentially include

disturbance and displacement of individuals of some threatened or endangered species that could

potentially occur within the project area boundary. With the increased diversion size there is a

corresponding increase in the likelihood of entraining a larval, YOY or adult pallid sturgeon that may be

in the project area.

5.11.4.2 Indirect

Impacts would be similar to Alternative 2 except this alternative includes additional restoration measures

and a larger diversion structure not identified in Alternative 2.

5.11.4.3 Cumulative

Impacts would be similar to Alternative 2 except this alternative includes additional restoration measures

and a larger diversion structure not identified in Alternative 2.

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5.11.5 Alternative 4 – 35,000 cfs max Diversion

(Recommended Plan)

5.11.5.1 Direct

Impacts would be similar to Alternative 2 except this alternative includes additional restoration measures

and a larger diversion structure not identified in Alternative 2. On May 14, 2010, CEMVN sent a letter to

the USFWS requesting the initiation of consultation regarding potential impacts from the Recommended

Plan to the pallid sturgeon. A response letter from the USFWS was received on July 1, 2010, requesting

that CEMVN provide additional data regarding the proposed action and the pallid sturgeon species, and

that CEMVN initiation formal consultation with the USFWS. In a July 15, 2010, dated letter, CEMVN

provided all supplemental data, as requested by the USFWS, and requested that formal consultation for

the MDWD project be initiated. On July 16, 2010, the USFWS responded via letter acknowledging the

receipt of the supplemental data provided and initiated the formal consultation process. Consultation was

completed on September 23, 2010, for the MDWD project. The USFWS Biological Opinion can be found

in Appendix A. The document concludes:

“After reviewing the current status of the pallid sturgeon, the effects of the current

freshwater diversions and the proposed Medium Diversion at White Ditch, and the

cumulative effects, it is the Service’s biological opinion that construction and subsequent

operation of a new freshwater diversion at White Ditch between RM 64 and 59 is not

likely to jeopardize the continued existence of the species. No critical habitat has been

designated for the pallid sturgeon; therefore, none will be affected.”

REASONABLE AND PRUDENT MEASURES

The Service believes the following reasonable and prudent measures (RPMs) are

necessary and appropriate to minimize the incidental take of pallid sturgeon by

entrainment through the medium diversion at White Ditch.

1. Gate operations should minimize velocity through the structure by maximizing the

open cross-section, especially at Mississippi River stages of 6 feet mean sea level or

less (equates to velocities at the culvert face of 7.2 fps or less).

2. Any gate operation that would significantly increase or decrease the velocity (change

greater than 500 cfs) should be implemented over several hours to allow fish

sufficient time to migrate back to the river or swim away from the structure.

3. Once the end of the annual discharge period is reached minimal gate openings

should be maintained for several days to allow passage of any sturgeon that may

have emigrated downstream.

4. The downstream edge of the culverts should have a slope to act as a ramp and/or

sufficient erosion protection that would prevent scour from forming a vertical ledge

greater than 6 inches at the downstream end of the culvert.

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5. In channel refuge consisting of several submerged wing dikes (or similar structures)

on both banks should be constructed no further downstream than 75 feet from the

structure. Minimal spacing between the structures should be 10 feet but can be

moved to account for scour. The maximum suggested height is 24 inches, but the

length extending into the channel is not yet determined.

6. The downstream side walls should be angled towards the culverts so they will guide

fish back into the culverts at lower velocities.

7. The two outer most culverts should have fish passage baffles constructed on the floor

of the culverts.

8. Monitoring to determine take and to reduce potential take by returning pallid

sturgeon to the river should be undertaken

TERMS AND CONDITIONS

In order to be exempt from the prohibitions of section 9 of the Act, the Corps shall

execute the following terms and conditions, which implement the RPMs described above

and outline required reporting/monitoring requirements. These terms and conditions are

non-discretionary.

1. Manuals (or other similar documents) written to guide the daily operations and

maintenance activities of the diversion should be written in cooperation with the

Service. Any proposed changes to such document would require re-initiation of

consultation under Section 7 of the ESA

2. Detailed design of wing dikes and the scour protection to prevent development of a

vertical ledge should be coordinated with the Service. After construction annual

inspection (i.e., measurements) should be taken at the downstream edge of the culvert

to determine need to for maintenance. If maintenance is required funding should be

immediately requested.

3. Design of downstream side walls and detailed design of the fish passage baffles

should be coordinated with the Service.

4. Three days of sampling effort will be made each quarter. Sampling will consist of at

minimum utilizing otter trawls, gillnets (i.e., 27.4 meter by 1.8 meter, six mesh panel

ranging from 23 to 76 centimeters), and trotlines (61 meters long with 60 dropper

lines at 0.9 meter intervals using 2/0 hooks baited with worms). Up to eight trotlines

will be fished on the bottom overnight and two gillnets will also be fish overnight. All

procedures and protocols for handling sturgeon should be followed and are available

at:

www.fws.gov/mountainpraire/endspp/protocoisIPallidSturgeonHandiingProtocol200

8B.pdf

All pallid sturgeon captures should be measured and tagged according to the protocol; if

permitted and when feasible, ageing and endoscopy to determine sex and reproductive

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stage should also be conducted. All pallid sturgeon captured should be returned to the

Mississippi River as soon as practicable. The number and size of each pallid sturgeon

caught by date and gear type should be provided to the Service. Unsuccessful sampling

efforts should also be reported by date and gear type.

Upon locating a dead or injured pallid sturgeon that may have been harmed or destroyed

as a direct or indirect result of the proposed project, the Corps and/or contractor shall be

responsible for notifying the Service’s Lafayette, Louisiana, Field Office (337/291-3100)

and the LDWF’s Natural Heritage Program (225/765-2821). Care shall be taken in

handling an injured sturgeon to ensure effective treatment or disposition and in handling

dead specimens to preserve biological materials in the best possible state for later

analysis. Disposition of dead sturgeon is also addressed in the protocols.”

5.11.5.2 Indirect

Impacts would be similar to Alternative 3 except this alternative includes additional restoration measures

and a larger diversion structure not identified in Alternative 3.

5.11.5.3 Cumulative

Impacts would be similar to Alternative 3 except this alternative includes additional restoration measures

and a larger diversion structure not identified in Alternative 3.

5.12 CULTURAL AND HISTORIC RESOURCES

A cultural resources survey of the Oak River landscape features was completed by contractors employed

by the USACE New Orleans District. Three archaeological sites and one standing structure (Site

16PL193) were identified during the survey. In consultation with the Louisiana State Historic

Preservation Officer (SHPO), two of the archaeological sites and the standing structure were determined

to be not eligible for inclusion in the National Register of Historic Places. The remaining archaeological

site was determined to be National Register eligible. In consultation with the Chitimacha Tribe of

Louisiana and the SHPO, it was decided that the White Ditch diversion would probably have no adverse

effect on this historic property as it is located just outside the project area. However, it was also agreed

that the site would be monitored to determine what effect the project has on the site and if the effect was

adverse then a treatment plan would be devised by the New Orleans District through consultation with the

Chitimacha Tribe of Louisiana and the SHPO. One other site, Fort De La Boulaye, is located outside the

project area and will not be affected by the White Ditch Diversion.

Two additional areas within the overall project area remain to be surveyed. These would be the Bayou

Garelle and the batture of the Mississippi River. Field conditions during the investigative period for this

study effort have prevented these two areas from being surveyed for cultural resources.

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5.12.1 No Action Alternative (Future Without Project

Conditions)

5.12.1.1 Direct

Under the No Action Alternative, no archeological sites would be impacted by construction activities.

5.12.1.2 Indirect

All archaeological sites within the project area would continue to be affected by erosion and subsidence.

5.12.1.3 Cumulative

Archaeological sites in southeast Louisiana would be all subjected to the same natural forces, subsidence

and erosion from natural wave action, storm surge and wakes created by motor boats. Eventually most

sites, unless protected would disappear from the archaeological record.

5.12.2 Alternative 1 – 5,000 cfs max Diversion

5.12.2.1 Direct

Construction of the 5,000 cfs diversion alternative and associated outfall management features would not

be expected to adversely affect archaeological sites.

5.12.2.2 Indirect

Indirect impacts of implementing the 5,000 cfs diversion alternative on archaeological sites would be

expected to be the same as for the No Action Alternative.

5.12.2.3 Cumulative

Cumulative impacts of the 5,000 cfs diversion alternative would be expected to be the same as for the No

Action Alternative.

5.12.3 Alternative 2 – 10,000 cfs max Diversion

5.12.3.1 Direct

Construction of the 10,000 cfs diversion alternative and associated outfall management features would not

be expected to adversely affect archaeological sites.

5.12.3.2 Indirect

Indirect impacts of implementing the 10,000 cfs diversion alternative on archaeological sites would be

expected to be the same as for the No Action Alternative.

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5.12.3.3 Cumulative

Cumulative impacts of the 10,000 cfs diversion alternative would be expected to be the same as for the

No Action Alternative.

5.12.4 Alternative 3 – 15,000 cfs max Diversion

5.12.4.1 Direct

Construction of the 15,000 cfs diversion alternative and associated outfall management features would not

be expected to adversely affect archaeological sites.

5.12.4.2 Indirect

Indirect impacts of implementing the 15,000 cfs diversion alternative on archaeological sites would be

expected to be the same as for the No Action Alternative.

5.12.4.3 Cumulative

Cumulative impacts of the 15,000 cfs diversion alternative would be expected to be the same as for the

No Action Alternative.

5.12.5 Alternative 4 – 35,000 cfs max Diversion

(Recommended Plan)

5.12.5.1 Direct

Construction of the 35,000 cfs diversion alternative and associated outfall management features would not

be expected to adversely affect archaeological sites.

5.12.5.2 Indirect

Indirect impacts of implementing the 35,000 cfs diversion alternative on archaeological sites would be

expected to be the same as for the No Action Alternative.

5.12.5.3 Cumulative

Cumulative impacts of the 35,000 cfs diversion alternative would be expected to be the same as for the

No Action Alternative.

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5.13 AESTHETICS

5.13.1 No Action Alternative (Future Without Project

Conditions)

5.13.1.1 Direct

The visual complexity surrounding the project area is related to its geomorphic structures including ridge,

swamp and marsh. All of these elements would be critical systems inclusive to the White Ditch Study

Area. Together, all of these elements provide a pleasing aesthetic view shed to the public, especially from

atop the existing levee system. Direct impacts would evolve from the natural conditions of the area and

the associated changes to these geomorphic structures.

5.13.1.2 Indirect

Indirect impacts can also be derived from the conversion of wetland and marshlands into open water.

These landscape types would be excellent habitat for a variety of wildlife and fisheries. Excellent

examples of habitat and their associated wildlife typically provide the viewer with focal points and

accents (typically made up of both the landscape and the wildlife) that make a view shed dynamic, scenic

and memorable. If loss of these habitats persists, then this is just one more element of the viewscape that

is lost along with it.

5.13.1.3 Cumulative

Cumulative impacts of the No Action Alternative in this instance include the incremental impacts to

aesthetic resources (not only in the project area, but to the hydrologic basin, Louisiana, and the U.S.)

resulting from the past, present and reasonably foreseeable future impacts associated with conversion and

loss of marsh, wetland and/or swamps. Without implementation of wetland creation and other protection

measures, continued conversion of existing fragmented wetlands to open-water habitats would persist.

Degradation of the land would convert existing view sheds of marsh and wetland to more open water

views. Open waters would be somewhat less desirable because they lack those vertical and horizontal

features which provide a viewer with the necessary elements of form, line, texture and color that make a

view scenic and memorable.

5.13.2 Alternative 1 – 5,000 cfs max Diversion

5.13.2.1 Direct

Direct Impacts to Aesthetic Resources would be similar to those presented under the Recommended Plan.

Differences between the plans include velocities and flow rates of the diversion. However, in terms of

direct impacts to aesthetics, these elements translate into how quickly the study area can rebuild itself

with the inflow of sediments and are not as relevant as the actual location of the diversion itself.

5.13.2.2 Indirect

Indirect Impacts to Aesthetic Resources would be similar to those presented under the Recommended

Plan. Differences between the plans include velocities and flow rates of the diversion.

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5.13.2.3 Cumulative

Cumulative Impacts to Aesthetic Resources would be similar to those presented under the Recommended

Plan. Differences between the plans include velocities and flow rates of the diversion.

5.13.3 Alternative 2 – 10,000 cfs max Diversion

5.13.3.1 Direct

Direct Impacts to Aesthetic Resources would be similar to those presented under the Recommended Plan.

Differences between the plans include velocities and flow rates of the diversion. However, in terms of

direct impacts to aesthetics, these elements translate into how quickly the study area can rebuild itself

with the inflow of sediments and are not as relevant as the actual location of the diversion itself.

5.13.3.2 Indirect

Indirect Impacts to Aesthetic Resources would be similar to those presented under the Recommended

Plan. Differences between the plans include velocities and flow rates of the diversion.

5.13.3.3 Cumulative

Cumulative Impacts to Aesthetic Resources would be similar to those presented under the Recommended

Plan. Differences between the plans include velocities and flow rates of the diversion.

5.13.4 Alternative 3 – 15,000 cfs max Diversion

5.13.4.1 Direct

Direct Impacts to Aesthetic Resources would be similar to those presented under the Recommended Plan.

Differences between the plans include velocities and flow rates of the diversion. However, in terms of

direct impacts to aesthetics, these elements translate into how quickly the study area can rebuild itself

with the inflow of sediments and are not as relevant as the actual location of the diversion itself.

5.13.4.2 Indirect

Indirect Impacts to Aesthetic Resources would be similar to those presented under the Recommended

Plan. Differences between the plans include velocities and flow rates of the diversion.

5.13.4.3 Cumulative

Cumulative Impacts to Aesthetic Resources would be similar to those presented under the Recommended

Plan. Differences between the plans include velocities and flow rates of the diversion.

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5.13.5 Alternative 4 – 35,000 cfs max Diversion

(Recommended Plan)

5.13.5.1 Direct

The visual resources of the project corridor would be temporarily impacted by construction activities

related to implementing the proposed action and by transport activities needed to move equipment and

materials to and from the site. Boating and other water traffic would most likely not be affected.

The creation of artificial, manmade features could decrease the natural, scenic quality in any area. In the

case of the proposed action, the diversion is an un-natural element and could work to decrease the scenic

quality. However, the potential benefits of reclaimed land mass and marsh area, and the need to protect

this marsh area outweigh the visual impacts of developing the diversion.

5.13.5.2 Indirect

With the implementation of the proposed action, the creation, or re-creation, of marsh and wetland would

indirectly impact the study area by increasing habitat for desirable land based wildlife. On the flip side, as

another indirect impact, open-water habitat would be decreased over time.

5.13.5.3 Cumulative

Long term negative impacts to the aesthetic (visual) resources would be negligible. Landscapes converted

or reorganized into natural or, in some cases, seminatural visual conditions similar to the proposed project

could be considered as visually superior. As a cumulative impact, the proposed scenario is desirable

throughout the hydrologic basin, Louisiana, and the U.S. for reclaiming lost land mass.

5.14 RECREATION

The following discussion addresses the potential recreational resource impacts of each MDWD

Alternative. There would be five alternatives for the project including No Action.

5.14.1 No Action Alternative (Future Without Project

Conditions)

5.14.1.1 Direct

Recreational resources in the region that would most likely be affected under the No Action Alternative

would be those related to loss of wetlands and habitat diversity.

Continued wetland fragmentation and the eventual conversion to shallow open-water habitat would likely

have negative consequences on a variety of recreational resources in the project area. Wildlife abundance

is directly related to the amount of wetlands present. As wetland deterioration and high rates of land loss

continues throughout the area, wildlife abundance would continue to decrease. Continued loss of essential

fish and wildlife habitat, especially marsh-edge habitat and transitional habitat between estuarine and

marine environments, would most likely result in a reduction in productivity. Lower quality fishery

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spawning, nursery, and foraging habitat would likely translate to a decline in recreational fishing,

shrimping, and crabbing catch rates in the future.

The local abundance of resident, transitional wetland-dependent wildlife, would likely decrease as these

species relocate to find more suitable transitional wetland habitats. Migratory birds would be required to

find other, more suitable stopover habitats on their trans-Gulf migrations. With the continued conversion

of transitional estuarine wetlands to open water, estuarine fishery abundance and diversity would be

expected to decline over time. With continued habitat deterioration, recreational waterfowl hunting would

likely decline with reduced bag limits much of it due to higher salinity levels and the loss of SAV.

Likewise, as usage of the study area by migratory birds declines, so would the opportunities for viewing.

Ridge habitat would also decline resulting in fewer opportunities for deer and small game hunting.

5.14.1.2 Indirect

Long term potential indirect impacts could include loss of associated recreational support facilities such

as marinas and bait shops that would be the basis for most recreational use. This would result in a

reduction in economic activity associated with recreation uses.

5.14.1.3 Cumulative

Cumulative impacts would be the impacts on the environment which result from the incremental impact

of the no action plan when added to other past, present, and reasonably foreseeable future actions

regardless of what agency or person undertakes such other actions. Existing and planned projects in the

project vicinity include the twenty year old Caernarvon Diversion and a proposed Caernarvon

modification. Cumulative effects of these projects on recreational resources in the White Ditch project

area would be expected to be minimal. Turbidity created by the Caernarvon Diversion could infiltrate the

southern part of the White Ditch project area during the high water pulse periods, which could be seen

during certain tidal flows. The effects on recreational resources would be expected to be minimal and

temporary.

Effects from the No Action Alternative would result in substantial changes in recreation opportunities and

potential loss of much of the recreational resource base in the project area, as described in the direct and

indirect impact sections.

5.14.2 Alternative 1 – 5,000 cfs max Diversion

5.14.2.1 Direct

Recreational uses in the study area such as fishing and hunting could be affected due to the

implementation and operations of the freshwater diversion.

During high flow pulse periods, large influxes of freshwater into the existing habitat in the project area

would increase turbidity and flow and reduce salinity levels in the project area. During these high pulse

periods and afterward, recreational activities would likely be curtailed.

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Due to lower salinity levels and turbidity, saltwater fish species would likely migrate to more desirable

locations. In turn, catch rates would potentially decrease in the project area during these high flow

periods.

While some habitat transition based on decreased salinity levels is anticipated, overall benefits associated

with marsh creation, and improved aquatic habitat for fisheries and waterfowl should result in improved

recreational experiences during normal flow conditions. Decreases in salinity within the intermediate

marsh zone could potentially enhance conditions for freshwater fish species within this portion of the

project area.

Waterfowl hunting within the study area would likely improve due to reduced salinity levels and

increased SAV. In addition, deer and other small game hunting could improve over time due to

stabilization and improved ridge habitat.

Channel dredging and placement of dredged material for marsh creation and ridge restoration would

displace resident fish and wildlife and could temporarily disrupt fishing and hunting activity in the

construction zone. Following construction, the created marsh, restored ridges, and enlarged outfall

channels could increase or enhance recreational resources within and adjacent to the construction

footprint. Marsh creation could benefit recreation by providing additional land for birding and hunting.

The marsh could also attract ducks and serve as a duck hunting area. The increase in habitat value would

likely result in increased species of fish and mammal wildlife usage of the area. This would enhance the

productivity of the marsh and sustain its longevity. Marsh creation could also be beneficial for protecting

interior areas, including any recreational structures, from the negative effects of storm surges.

In terms of recreational user days, no substantial change through year 5 is anticipated. After the two

month high flow pulse, water quality changes should, over time return to normal. There could be an

increase in user day values due to decreased salinity levels, and increased marsh acres and habitat units.

The net AAHUs would be expected to increase by 5,457. The increase in marsh acres is projected to

increase compared to future without project conditions. The increase is anticipated to be incremental until

project year 20; however, no increases would be anticipated after project year 20.

5.14.2.2 Indirect

Potential indirect impacts from the proposed action would primarily consist of effects on recreational

fishing from increased turbidity to the water bodies outside of the study area. These impacts could include

fish species temporarily migrating away from these disturbed conditions.

5.14.2.3 Cumulative

Implementation of the 5,000 cfs alternative would be expected to have positive synergistic effects on

recreation resources when combined with other Federal, state, local, and private restoration efforts,

including the Caernarvon diversion and its proposed modification. The incremental effects of this

alternative have the potential to support and sustain wetland-dependent recreation opportunities, provide

for a more stable localized recreation economy, and could result in a slight increase in local recreationrelated employment and income.

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The cumulative impacts would create and maintain critical marsh habitat within the project area necessary

for the viable protection of market fisheries and aquatics resources. The impacts should stabilize or

potentially improve recreational opportunities in the area.

This alternative would support and sustain a greater number of freshwater-based recreational

opportunities such as duck hunting and bass fishing, while maintaining saltwater fishing opportunities.

5.14.3 Alternative 2 – 10,000 cfs max Diversion

5.14.3.1 Direct

Alternative 2 incorporates a 10,000 cfs maximum flow diversion which is twice the flow of Alternative 1.

Impacts would be similar to Alternative 1 but could affect a larger area. The increase in flow rate would

be directly related to the increase in freshwater distributed through the project area. Therefore, the direct

effects to the surrounding marsh and aquatic habitats would likely cover a larger area and potentially

result in a prolonged recovery time once the 2-month pulse is complete.

Several fish species would be deterred from the turbid water, and as a result, would travel elsewhere.

Turbidity from the high pulse flows would also deter the waterfowl and other wildlife during the high

water levels. There would be a benefit to introducing freshwater into these areas, as long as the increased

currents do not contribute to marsh fragmentation in other areas. Bankline stabilization and notched weirs

would need to be monitored carefully to protect adjacent marsh habitats.

A slight reduction in recreational user days is possible through year 10 due to increased turbidity and flow

during the pulse period and longer recovery time. However beyond year 10, a slight increase above

without project conditions in recreation user days is anticipated due to improved quality and quantity of

habitat.

The increase in marsh acres is projected to be greater than the increase projected for Alternative 1. The

net AAHUs would be expected to rise to 6,096. The increase is incremental until project year 20;

however, there would be no increases after project year 20.

5.14.3.2 Indirect

This alternative would have similar indirect impacts to those described under Alternative 1. The main

difference is that indirect impacts associated with increased turbidity to water bodies outside of study area

would potentially be experienced in a larger area due to the increased water flows under the pulse

condition.

5.14.3.3 Cumulative

This alternative would have similar cumulative impacts to those described under Alternative 1.

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5.14.4 Alternative 3 – 15,000 cfs max Diversion

5.14.4.1 Direct

Alternative 3 incorporates a 15,000 cfs maximum flow diversion which is three times the flow of

Alternative 1. Impacts would be similar to Alternative 1 but could affect a larger area. The increase in

flow rate would be directly related to the increase in freshwater distributed through the project area.

Therefore, the direct effects to the surrounding marsh and aquatic habitats would cover a large area and

result in a prolonged recovery time once the 2-month pulse is achieved.

Several fish species would be deterred from the turbid water, and as a result, would migrate to a more

desirable location. Turbidity from the high pulse flows would also deter the waterfowl and other wildlife

during the high water levels. There would be a benefit to introducing freshwater into these areas, as long

as the increased velocities do not contribute to marsh fragmentation in other areas. Bankline stabilization

and notched weirs would need to be monitored carefully to protect the adjacent marsh habitats.

While freshwater-based recreational opportunities such as waterfowl hunting and bass fishing could

improve, brackish and saltwater-based recreation activities such as fishing and shrimping could migrate

further south and east in the project area possibly increasing the access distance to such opportunities.

A slight reduction in recreational user days is possible through year 10 due to increased turbidity and flow

during the pulse period and longer recovery time. However beyond year 10, a slight increase above

without project conditions in recreation user days is anticipated due to improved quality and quantity of

habitat.

The increase in marsh acres is projected to be greater than increases anticipated for Alternatives 1 or 2.

The net AAHUs would be expected to rise to 7,922. The increase is incremental until project year 20;

however, there would be no increases after project year 20.

5.14.4.2 Indirect

This alternative would have similar indirect impacts to those described under Alternative 2.

5.14.4.3 Cumulative

This alternative would have similar cumulative impacts to those described under Alternative 1 with the

exception that saltwater-based recreational opportunities could shift further south and east in the project

area potentially increasing the access distance to such opportunities.

5.14.5 Alternative 4 – 35,000 cfs max Diversion

(Recommended Plan)

5.14.5.1 Direct

The maximum flow of Alternative 4 is seven times greater than that of Alternative 1.

Impacts would be similar to Alternative 1 but could affect a larger area. The increased flows from the

diversion could cause high surge and back flow. The channels should be monitored carefully as to ensure

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they do not flood and cause direct impacts to recreational facilities and surrounding structures. The

turbidity impacts would likely be substantial and potentially be temporarily detrimental to fish and

waterfowl use in much of the project area specifically during and after the pulse.

While freshwater-based recreational opportunities could increase in the project area, brackish and

saltwater-based recreational opportunities could decline. In turn, a substantial reduction in recreational

user days would be anticipated over the initial 20 years of the project.

The increase in marsh acres is projected to be greater than increases expected for Alternatives 1, 2, or 3.

The increase is incremental until project year 20; however, there would be no increases after project year

20.

5.14.5.2 Indirect

This alternative would have similar indirect impacts to those described under Alternative 2.

5.14.5.3 Cumulative

This alternative would have similar cumulative impacts to those described under Alternative 1 with the

exception that saltwater-based recreational opportunities could shift further south and east in the project

area potentially increasing the access distance to such opportunities.

5.15 SOCIOECONOMICS AND HUMAN RESOURCES

5.15.1 Displacement of Population and Housing

5.15.1.1 No Action Alternative (Future Without Project Conditions)

5.15.1.1.1 Direct

There would be no direct impacts to population and housing around this diversion site if the proposed

diversion was not constructed.

5.15.1.1.2 Indirect

There would be no indirect impacts to population and housing around this diversion site if the proposed

action was not implemented.

5.15.1.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts to population and housing consist simply

of the sum of the direct and indirect impacts for this alternative added to all other local and regional

activities, including construction of the Federal Greater New Orleans Hurricane and Storm Damage Risk

Reduction System (GNOHSDRRS), and existing and in-progress elements of the LCA Ecosystem

Restoration program, including development of freshwater diversion projects. As noted in the FPEIS for

the LCA study, regional trends show population increases in urban and suburban areas, and retreat from

rural and coastal areas such as the White Ditch project area.

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Under the no action scenario, direct cumulative impacts remain no greater than the sum of those impacts

indicated individually for each project component of the aforementioned programs.

The exception to the foregoing would be the cumulative indirect impacts associated with the completion

of the GNOHSDRRS in its entirety. The lower flood risk that accrues to the much of the New Orleans

metropolitan area upon completion of the GNOHSDRRS could enhance the desirability of living within

the protected areas. As a result, a shift in the dispersion of population within the New Orleans

Metropolitan Statistical Area, or beyond, could occur. Also, to the extent that the completion of the

GNOHSDRRS encourages regional economic growth, any additional jobs thus created could manifest

itself in either in-migration to the area or an increase in commuting activity.

5.15.1.2 Alternative 1 – 5,000 cfs Diversion

5.15.1.2.1 Direct

There would be no direct impacts to population and housing around this diversion site if Alternative 1 is

constructed.

5.15.1.2.2 Indirect

Indirect impacts to population and housing in the study area if Alternative 1 is implemented, if any, would

be anticipated to be negligible and indistinguishable from other local and regional influences on

population growth and decline.

5.15.1.2.3 Cumulative

Cumulative impacts that include Alternative 1 would be expected to be similar to the No Action

Alternative.

5.15.1.3 Alternative 2 – 10,000 cfs max Diversion

5.15.1.3.1 Direct

There would be no direct impacts to population and housing around this diversion site if Alternative 2 is

constructed.

5.15.1.3.2 Indirect

Indirect impacts to population and housing in the study area associated with implementation of

Alternative 2 would be expected to be similar to those anticipated for Alternative 1.

5.15.1.3.3 Cumulative

Cumulative impacts that include Alternative 2 would be expected to be similar to the No Action

Alternative.

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5.15.1.4 Alternative 3 – 15,000 cfs max Diversion

5.15.1.4.1 Direct

There would be no direct impacts to population and housing around this diversion site if Alternative 3 is

constructed.

5.15.1.4.2 Indirect

Indirect impacts to population and housing in the study area associated with implementation of

Alternative 3 would be expected to be similar to those anticipated for Alternative 1.

5.15.1.4.3 Cumulative

Cumulative impacts that include Alternative 3 would be expected to be similar to the No Action

Alternative.

5.15.1.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.1.5.1 Direct

There would be no direct impacts to population and housing around this diversion site if Alternative 4 is

implemented.

5.15.1.5.2 Indirect

Indirect impacts to population and housing in the study area associated with implementation of

Alternative 4 would be expected to be similar to those anticipated for Alternative 1.

5.15.1.5.3 Cumulative

Cumulative impacts that include Alternative 4 would be expected to be similar to the No Action

Alternative.

5.15.2 Employment, Business, and Industrial Activity

5.15.2.1 No Action Alternative (Future Without Project Conditions)

5.15.2.1.1 Direct

There would be no direct impacts to employment, business, and industry in the Phoenix vicinity if the

proposed diversion is not constructed.

5.15.2.1.2 Indirect

There would be no indirect impacts to employment, business, and industry in the vicinity of the White

Ditch study area if the proposed action is not implemented.

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5.15.2.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts to employment, business and industry

consist simply of the sum of the direct and indirect impacts for this alternative added to all other local and

regional activities, including construction of the GNOHSDRRS, and existing and in-progress elements of

the LCA Ecosystem Restoration program, including development of freshwater diversion projects.

Under the no action scenario, direct cumulative impacts remain no greater than the sum of those impacts

indicated individually for each project component of the aforementioned programs. Cumulative indirect

impacts associated with the completion of the GNOHSDRRS in its entirety could occur. The lower flood

risk that accrues to the much of the New Orleans metropolitan area upon completion of the

GNOHSDRRS could have the effect of spurring additional economic growth in the region than would

otherwise occur. As a result, an increase in the number of firms and the output of business and industry

would likely manifest itself in such growth.

5.15.2.2 Alternative 1 – 5,000 cfs Diversion

5.15.2.2.1 Direct

There could be minor temporary increases in local employment and related business activity during the

construction period if Alternative 1 is implemented.

5.15.2.2.2 Indirect

Over the 50-year period of analysis Alternative 1 is expected to protect, create and nourish emergent

wetlands that would benefit, to some undetermined level, local employment in wetland-dependent jobs

such as commercial and recreational fisheries, and ecotourism; as well as provide benefits for supporting

economic activities such as marinas, bait and tackle shops, and others.

5.15.2.2.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts for employment, business and industry

consist simply of the sum of the direct and indirect impacts for this alternative added to all other local and

regional activities, including construction of the GNOHSDRRS, and existing and in-progress elements of

the LCA Ecosystem Restoration program, including development of freshwater diversion projects.

Cumulative impacts that include the proposed action would be no greater than the sum of those impacts

indicated individually for each project component of the aforementioned programs.

Alternative 1 would incrementally add to these other activities and programs help support coast wide

wetland-dependent employment. However, this incremental effect would be insignificant compared to

cumulative impacts to employment and income described under the No Action Alternative.

5.15.2.3 Alternative 2 – 10,000 cfs max Diversion

5.15.2.3.1 Direct

There could be minor temporary increases in local employment and related business activity during the

construction period if Alternative 2 is implemented.

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5.15.2.3.2 Indirect

Over the 50-year period of analysis Alternative 2 is expected to protect, create and nourish emergent

wetlands that would benefit, to some undetermined level, local employment in wetland-dependent jobs

such as commercial and recreational fisheries, and ecotourism; as well as provide benefits for supporting

economic activities such as marinas, bait and tackle shops, and others.

5.15.2.3.3 Cumulative

Cumulative impacts of Alternative 2 would be expected to be incrementally greater than Alternative 1,

but similarly insignificant compared to cumulative impacts to employment and income described under

the No Action Alternative.

5.15.2.4 Alternative 3 – 15,000 cfs max Diversion

5.15.2.4.1 Direct

There could be minor temporary increases in local employment and related business activity during the

construction period if Alternative 3 is implemented.

5.15.2.4.2 Indirect

Over the 50-year period of analysis Alternative 3 is expected to protect, create and nourish emergent

wetlands that would benefit, to some undetermined level, local employment in wetland-dependent jobs

such as commercial and recreational fisheries, and ecotourism; as well as provide benefits for supporting

economic activities such as marinas, bait and tackle shops, and others.

5.15.2.4.3 Cumulative

Cumulative impacts of Alternative 3 would be expected to be incrementally greater than Alternative 3,

but would be not anticipated to be significant compared to cumulative impacts to employment and income

described under the No Action Alternative.

5.15.2.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.2.5.1 Direct

There could be minor temporary increases in local employment and related business activity during the

construction period if Alternative 4 is implemented.

5.15.2.5.2 Indirect

Over the 50-year period of analysis Alternative 4 is expected to protect, create and nourish emergent

wetlands that would benefit, to some undetermined level, local employment in wetland-dependent jobs

such as commercial and recreational fisheries, and ecotourism; as well as provide benefits for supporting

economic activities such as marinas, bait and tackle shops, and others.

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5.15.2.5.3 Cumulative

Cumulative impacts of Alternative 4 would be expected to be incrementally greater than Alternative 3,

but would be not anticipated to be significant compared to cumulative impacts to employment and income

described under the No Action Alternative.

5.15.3 Community Cohesion

5.15.3.1 No Action Alternative (Future Without Project Conditions)

5.15.3.1.1 Direct

Without implementation of the proposed action there would be no direct impacts to community cohesion

in the vicinity of the proposed diversion site.

5.15.3.1.2 Indirect

Without implementation of the proposed action there would be no indirect impacts to community

cohesion in the vicinity of the proposed diversion site.

5.15.3.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts to community cohesion consist simply of

the sum of the direct and indirect impacts for this alternative added to all other local and regional

activities, including construction of the GNOHSDRRS, and existing and in-progress elements of the LCA

Ecosystem Restoration program, including development of freshwater diversion projects.

Under the no action scenario, direct cumulative impacts remain no greater than the sum of those impacts

indicated individually for each project component of the aforementioned programs. Cumulative indirect

impacts associated with the completion of the GNOHSDRRS in its entirety could occur. The lower flood

risk that accrues to the much of the New Orleans metropolitan area upon completion of the

GNOHSDRRS could have the effect of enhancing community cohesion. The reason for this is that the

lower incidence of flooding reduces the likelihood that patterns of social interaction and communication

within the community would be interrupted or permanently altered.

5.15.3.2 Alternative 1 – 5,000 cfs Diversion

5.15.3.2.1 Direct

There would be no direct impacts to community cohesion around this diversion site if Alternative 1 is

implemented.

5.15.3.2.2 Indirect

There would be no indirect impacts to community cohesion around this diversion site if Alternative 1 is

implemented.

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5.15.3.2.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts for community cohesion consist simply of

the sum of the direct and indirect impacts for this alternative added to all other local and regional

activities, including construction of the GNOHSDRRS, and existing and in-progress elements of the LCA

Ecosystem Restoration program, including development of freshwater diversion projects.

Cumulative impacts that include the proposed action would be no greater than the sum of those impacts

indicated individually for each project component.

5.15.3.3 Alternative 2 – 10,000 cfs max Diversion

5.15.3.3.1 Direct

There would be no direct impacts to community cohesion around this diversion site if Alternative 2 is

implemented.

5.15.3.3.2 Indirect

There would be no indirect impacts to community cohesion around this diversion site if Alternative 2 is

implemented.

5.15.3.3.3 Cumulative

Cumulative impacts for Alternative 2 would be expected to be similar to those anticipated for Alternative

1.

5.15.3.4 Alternative 3 – 15,000 cfs max Diversion

5.15.3.4.1 Direct

There would be no direct impacts to community cohesion around this diversion site if Alternative 3 is

implemented.

5.15.3.4.2 Indirect

There would be no indirect impacts to community cohesion around this diversion site if Alternative 3 is

implemented.

5.15.3.4.3 Cumulative

Cumulative impacts for Alternative 3 would be expected to be similar to those anticipated for Alternative

1.

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5.15.3.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.3.5.1 Direct

There would be no direct impacts to community cohesion around this diversion site if Alternative 4 is

implemented.

5.15.3.5.2 Indirect

There would be no indirect impacts to community cohesion around this diversion site if Alternative 4 is

implemented.

5.15.3.5.3 Cumulative

Cumulative impacts for Alternative 4 would be expected to be similar to those anticipated for Alternative

1.

5.15.4 Environmental Justice

5.15.4.1 No Action Alternative (Future Without Project Conditions)

5.15.4.1.1 Direct

Minority and/or low-income communities have not been identified in the study area of Plaquemines

Parish. In a future without project scenario, no anticipated disproportionately high or adverse human

health or environmental effects on minority or low-income populations would occur, as no property

would be acquired for construction of the proposed project within the study area.

5.15.4.1.2 Indirect

No disproportionately high or adverse human health or environmental indirect impacts on minority or

low-income populations would occur.

5.15.4.1.3 Cumulative

There would be no cumulative impacts on minority and/or low-income communities within the study area

per 2000 U.S. Census information and requirements of E.O. 12898. The No Action Alternative would not

contribute to any additional EJ issues when combined with other Federal, state, local, and private

restoration efforts.

5.15.4.2 Alternative 1 – 5,000 cfs Diversion

5.15.4.2.1 Direct

No minority populations have been identified within the study area of Plaquemines Parish. Per 2000 U.S.

Census information and requirements of E.O. 12898, this area is not an Environmental Justice

community. Direct impacts from construction activities such air quality, noise, traffic, safety, etc., would

occur in the study area; but as there would be no permanent residences along the proposed project area,

no direct impacts on human health or environmental effects would be expected for this Alternative.

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5.15.4.2.2 Indirect

Under Alternative 1 no indirect impacts on human health or environmental effects within the study area

would occur.

5.15.4.2.3 Cumulative

No minority and/or low-income communities have been identified within the proposed study area per

2000 U.S. Census information and requirements of E.O. 12898. Cumulative impacts would be the

synergistic effect of implementing Alternative 1 with the additive combination of impacts and benefits for

overall net acres created, nourished, and protected by other Federal, state, local and private activities and

restoration efforts as summarized in Section 1 of this report The cumulative impacts of Alternative 1

would be similar to those described for the No Action Alternative.

5.15.4.3 Alternative 2 – 10,000 cfs max Diversion

5.15.4.3.1 Direct

Direct impacts of Alternative 2 would be similar to Alternative 1.

5.15.4.3.2 Indirect

Indirect impacts of Alternative 2 would be similar to Alternative 1.

5.15.4.3.3 Cumulative

Cumulative impacts of Alternative 2 would be similar to Alternative 1

5.15.4.4 Alternative 3 – 15,000 cfs max Diversion

5.15.4.4.1 Direct

Direct impacts of Alternative 3 would be similar to Alternative 1.

5.15.4.4.2 Indirect

Indirect impacts of Alternative 3 would be similar to Alternative 1.

5.15.4.4.3 Cumulative

Cumulative impacts of Alternative 3 would be similar to Alternative 1

5.15.4.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.4.5.1 Direct

Direct impacts of Alternative 4 would be similar to Alternative 1.

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5.15.4.5.2 Indirect

Indirect impacts of Alternative 4 would be similar to Alternative 1.

5.15.4.5.3 Cumulative

Cumulative impacts of Alternative 4 would be similar to Alternative 1.

5.15.5 Infrastructure

5.15.5.1 No Action Alternative (Future Without Project Conditions)

5.15.5.1.1 Direct

There would be no direct impacts to infrastructure if the proposed diversion was not constructed.

5.15.5.1.2 Indirect

Under the No Action Alternative, continuing loss of marsh soils and vegetation in the project area over

the 50-year planning horizon could potentially result in increased vulnerability of existing infrastructure

to the erosive force of wind and wave action from the Gulf of Mexico. Beyond this, no indirect impacts to

infrastructure would be anticipated if the proposed action was not implemented.

5.15.5.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts to infrastructure consist simply of the sum

of the direct and indirect impacts for this alternative added to all other local and regional activities,

including construction of the Federal Greater New Orleans Hurricane and Storm Damage Risk Reduction

System (GNOHSDRRS), and existing and in-progress elements of the LCA Ecosystem Restoration

program, including development of freshwater diversion projects.

Under the no action scenario, direct cumulative impacts remain no greater than the sum of those impacts

indicated individually for each project component of the aforementioned programs.

5.15.5.2 Alternative 1 – 5,000 cfs Diversion

5.15.5.2.1 Direct

There would be short-term impacts to flood control infrastructure during construction of a box culvert

diversion structure either through or under the existing levee if Alternative 1 is implemented. Temporary

impacts to transportation infrastructure could occur if the existing highway system is partially closed

during construction. Construction practices would be implemented to avoid and minimize any potential

construction-related adverse impacts to existing infrastructure (e.g., pipelines, etc.), and to ensure that the

integrity of the Federal levee is not compromised at any time during or after construction.

5.15.5.2.2 Indirect

No long-term indirect negative or positive impacts to existing infrastructure in the project area would be

anticipated to occur if Alternative 1 is implemented.

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5.15.5.2.3 Cumulative

Cumulative impacts of Alternative 1 on existing infrastructure in the project area would be similar to

those anticipated for the No Action Alternative.

5.15.5.3 Alternative 2 – 10,000 cfs max Diversion

5.15.5.3.1 Direct

Direct impacts to infrastructure resulting from construction of Alternative 2 would be expected to be

similar to those anticipated for Alternative 1.

5.15.5.3.2 Indirect

Indirect impacts to infrastructure resulting from construction of Alternative 2 would be expected to be

similar to those anticipated for Alternative 1.

5.15.5.3.3 Cumulative

Cumulative impacts of Alternative 2 on existing infrastructure in the project area would be similar to

those anticipated for the No Action Alternative.

5.15.5.4 Alternative 3 – 15,000 cfs max Diversion

5.15.5.4.1 Direct

Direct impacts to infrastructure resulting from construction of Alternative 3 would be expected to be

similar to those anticipated for Alternative 1.

5.15.5.4.2 Indirect

Indirect impacts to infrastructure resulting from construction of Alternative 3 would be expected to be

similar to those anticipated for Alternative 1.

5.15.5.4.3 Cumulative

Cumulative impacts of Alternative 3 on existing infrastructure in the project area would be similar to

those anticipated for the No Action Alternative.

5.15.5.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.5.5.1 Direct

Direct impacts to infrastructure resulting from construction of Alternative 4 would be expected to be

similar to those anticipated for Alternative 1.

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5.15.5.5.2 Indirect

Indirect impacts to infrastructure resulting from construction of Alternative 4 would be expected to be

similar to those anticipated for Alternative 1.

5.15.5.5.3 Cumulative

Cumulative impacts of Alternative 3 on existing infrastructure in the project area would be similar to

those anticipated for the No Action Alternative.

5.15.6 Business and Industry

5.15.6.1 No Action Alternative (Future Without Project Conditions)

5.15.6.1.1 Direct

Without construction of the proposed action there would be no direct impacts to business and industry in

the vicinity of the project area.

5.15.6.1.2 Indirect

Without implementation of the proposed action there would be no indirect impacts to business and

industry in the vicinity of the project area.

5.15.6.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts to business and industry consist simply of

the sum of the direct and indirect impacts for this alternative added to all other local and regional

activities, including construction of the GNOHSDRRS, and existing and in-progress elements of the LCA

Ecosystem Restoration program, including development of freshwater diversion projects. Under the no

action scenario, direct cumulative impacts remain no greater than the sum of those impacts indicated

individually for each project component of the aforementioned programs.

Cumulative indirect impacts associated with the completion of the GNOHSDRRS in its entirety could

occur. The lower flood risk that accrues to the much of the New Orleans metropolitan area upon

completion of the GNOHSDRRS could have the effect of spurring greater economic growth in the region

than would otherwise occur. It follows that increases in business and industry would ensue given

additional economic growth. In addition, the lower incidence of flooding that the GNOHSDRRS is

designed to achieve would have the effect of preserving, if not enhancing, property values within the

protected areas.

5.15.6.2 Alternative 1 – 5,000 cfs Diversion

5.15.6.2.1 Direct

During construction of the diversion structure there could be a short-term disruption to fuel and storage

facilities located along the Mississippi River. However, such disruption would be minimal. There could

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be some disruption to pipelines located along the diversion site during construction, but no long-term

impact is expected to affect pipeline operations.

5.15.6.2.2 Indirect

There would be no indirect impacts to business and industry around this diversion site if Alternative 1 is

implemented.

5.15.6.2.3 Cumulative

Cumulative impacts of Alternative 1 on business and industry in the project area would be similar to those

anticipated for the No Action Alternative.

5.15.6.3 Alternative 2 – 10,000 cfs max Diversion

5.15.6.3.1 Direct

Direct impacts to business and industry resulting from construction of Alternative 2 would be expected to

be similar to those anticipated for Alternative 1.

5.15.6.3.2 Indirect

Indirect impacts to business and industry resulting from construction of Alternative 2 would be expected

to be similar to those anticipated for Alternative 1.

5.15.6.3.3 Cumulative

Cumulative impacts of Alternative 2 on business and industry in the project area would be similar to those

anticipated for the No Action Alternative.

5.15.6.4 Alternative 3 – 15,000 cfs max Diversion

5.15.6.4.1 Direct

Direct impacts to business and industry resulting from construction of Alternative 3 would be expected to

be similar to those anticipated for Alternative 1.

5.15.6.4.2 Indirect

Indirect impacts to business and industry resulting from construction of Alternative 3 would be expected

to be similar to those anticipated for Alternative 1.

5.15.6.4.3 Cumulative

Cumulative impacts of Alternative 3 on business and industry in the project area would be similar to those

anticipated for the No Action Alternative.

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5.15.6.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.6.5.1 Direct

Direct impacts to business and industry resulting from construction of Alternative 4 would be expected to

be similar to those anticipated for Alternative 1.

5.15.6.5.2 Indirect

Indirect impacts to business and industry resulting from construction of Alternative 4 would be expected

to be similar to those anticipated for Alternative 1.

5.15.6.5.3 Cumulative

Cumulative impacts of Alternative 4 on business and industry in the project area would be similar to those

anticipated for the No Action Alternative.

5.15.7 Traffic and Transportation

5.15.7.1 No Action Alternative (Future Without Project Conditions)

5.15.7.1.1 Direct

Without implementation of the proposed action there would be no direct impacts to transportation

resources in the vicinity of the proposed Phoenix diversion site.

5.15.7.1.2 Indirect

Without implementation of the proposed action there would be no indirect impacts to transportation

resources in the vicinity of the proposed Phoenix diversion site.

5.15.7.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts to transportation resources consist simply

of the sum of the direct and indirect impacts for this alternative added to all other local and regional

activities, including construction of the GNOHSDRRS, and existing and in-progress elements of the LCA

Ecosystem Restoration program, including development of freshwater diversion projects. Under the no

action scenario, direct cumulative impacts remain no greater than the sum of those impacts indicated

individually for each project component of the aforementioned programs.

The potential exists for cumulative indirect impacts associated with the completion of the GNOHSDRRS

in its entirety. The lower flood risk that accrues to the much of the New Orleans metropolitan area upon

completion of the GNOHSDRRS could have the effect of spurring additional economic growth in the

region than would otherwise occur. An increase in the demand for transportation resources usually

follows gains in economic activity and would thus be expected given any additional economic growth in

the region.

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5.15.7.2 Alternative 1 – 5,000 cfs Diversion

5.15.7.2.1 Direct

Activities associated with construction of the diversion structure and outfall management features of

Alternative 1 could result in increased activity by trucks along LA HWY 39. However, the relatively

remote location of the diversion site tends to render the potential for such traffic congestion effects to a

relatively low magnitude. Wear and tear on roadways used to transport materials to construction sites

would be expected to remain proportionate to the quantity of traffic emanating from all local and regional

activities.

5.15.7.2.2 Indirect

There would be no indirect impacts to transportation in the project area and vicinity if Alternative 1 is

implemented.

5.15.7.2.3 Cumulative

Cumulative impacts to traffic and transportation resulting from implementation of Alternative 1 would be

expected to be similar to those anticipated for the No Action Alternative.

5.15.7.3 Alternative 2 – 10,000 cfs max Diversion

5.15.7.3.1 Direct

Direct impacts to traffic and transportation resulting from construction of Alternative 2 would be expected

to be similar to those anticipated for Alternative 1.

5.15.7.3.2 Indirect

Indirect impacts to traffic and transportation resulting from construction of Alternative 2 would be

expected to be similar to those anticipated for Alternative 1.

5.15.7.3.3 Cumulative

Cumulative impacts to traffic and transportation resulting from construction of Alternative 2 would be

expected to be similar to those anticipated for Alternative 1.

5.15.7.4 Alternative 3 – 15,000 cfs max Diversion

5.15.7.4.1 Direct

Direct impacts to traffic and transportation resulting from construction of Alternative 3 would be expected

to be similar to those anticipated for Alternative 1.

5.15.7.4.2 Indirect

Indirect impacts to traffic and transportation resulting from construction of Alternative 3 would be

expected to be similar to those anticipated for Alternative 1.

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5.15.7.4.3 Cumulative

Cumulative impacts to traffic and transportation resulting from construction of Alternative 3 would be

expected to be similar to those anticipated for Alternative 1.

5.15.7.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.7.5.1 Direct

Direct impacts to traffic and transportation resulting from construction of Alternative 4 would be expected

to be similar to those anticipated for Alternative 1.

5.15.7.5.2 Indirect

Indirect impacts to traffic and transportation resulting from construction of Alternative 4 would be

expected to be similar to those anticipated for Alternative 1.

5.15.7.5.3 Cumulative

Cumulative impacts to traffic and transportation resulting from construction of Alternative 3 would be

expected to be similar to those anticipated for Alternative 1.

5.15.8 Public Facilities and Services

5.15.8.1 No Action Alternative (Future Without Project Conditions)

5.15.8.1.1 Direct

There would be no direct impacts to the availability of public facilities and services if the proposed action

is not implemented.

5.15.8.1.2 Indirect

There would be no indirect impacts to the availability of public facilities and services if the proposed

action is not implemented.

5.15.8.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts to the availability of public facilities and

services consist simply of the sum of the direct and indirect impacts for this alternative added to all other

local and regional activities, including construction of the GNOHSDRRS, and existing and in-progress

elements of the LCA Ecosystem Restoration program, including development of freshwater diversion

projects. Under the no action scenario, direct cumulative impacts remain no greater than the sum of those

impacts indicated individually for each project component of the aforementioned programs.

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5.15.8.2 Alternative 1 – 5,000 cfs Diversion

5.15.8.2.1 Direct

There would be no long-term direct impacts to public utilities and services around this diversion site if

Alternative 1 is constructed.

5.15.8.2.2 Indirect

There would be no indirect impacts to public utilities and services in the project area and vicinity if

Alternative 1 is implemented.

5.15.8.2.3 Cumulative

Cumulative impacts of Alternative 1 would be expected to be similar to those anticipated for the No

Action Alternative.

5.15.8.3 Alternative 2 – 10,000 cfs max Diversion

5.15.8.3.1 Direct

Direct impacts associated with construction of Alternative 2 would be expected to be similar to those

anticipated for Alternative 1.

5.15.8.3.2 Indirect

Indirect impacts of Alternative 2 would be expected to be similar to those anticipated for Alternative 1.

5.15.8.3.3 Cumulative

Cumulative impacts of Alternative 2 would be expected to be similar to those anticipated for the No

Action Alternative.

5.15.8.4 Alternative 3 – 15,000 cfs max Diversion

5.15.8.4.1 Direct

Direct impacts associated with construction of Alternative 3 would be expected to be similar to those

anticipated for Alternative 1.

5.15.8.4.2 Indirect

Indirect impacts of Alternative 3 would be expected to be similar to those anticipated for Alternative 1.

5.15.8.4.3 Cumulative

Cumulative impacts of Alternative 3 would be expected to be similar to those anticipated for the No

Action Alternative.

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5.15.8.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.8.5.1 Direct

Direct impacts associated with construction of Alternative 4 would be expected to be similar to those

anticipated for Alternative 1.

5.15.8.5.2 Indirect

Indirect impacts of Alternative 4 would be expected to be similar to those anticipated for Alternative 1.

5.15.8.5.3 Cumulative

Cumulative impacts of Alternative 4 would be expected to be similar to those anticipated for the No

Action Alternative.

5.15.9 Tax Revenues and Property Values

5.15.9.1 No Action Alternative (Future Without Project Conditions)

5.15.9.1.1 Direct

Without construction of the proposed action there would be no direct impacts to tax revenues and

property values in the vicinity of the proposed diversion site.

5.15.9.1.2 Indirect

Without implementation of the proposed action there would be no indirect impacts to tax revenues and

property values in the project area and vicinity.

5.15.9.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts to tax revenues and property values

consist simply of the sum of the direct and indirect impacts for this alternative added to all other local and

regional activities, including construction of the GNOHSDRRS, and existing and in-progress elements of

the LCA Ecosystem Restoration program, including development of freshwater diversion projects. Under

the no action scenario, direct cumulative impacts remain no greater than the sum of those impacts

indicated individually for each project component of the aforementioned programs.

Under the no action scenario, cumulative indirect impacts associated with the completion of the

GNOHSDRRS in its entirety could occur. The lower flood risk that accrues to the much of the New

Orleans metropolitan area upon completion of the GNOHSDRRS could have the effect of spurring

additional economic growth in the region than would otherwise occur. It follows that increases in tax

revenues would ensue given additional economic growth. In addition, the lower incidence of flooding that

the GNOHSDRRS is designed to achieve would have the effect of preserving, if not enhancing, property

values within the protected areas.

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5.15.9.2 Alternative 1 – 5,000 cfs Diversion

5.15.9.2.1 Direct

There would be no direct impacts to tax revenue and property around this diversion site if Alternative 1 is

constructed.

5.15.9.2.2 Indirect

There would be no indirect impacts to tax revenue and property in the project area and vicinity if

Alternative 1 is implemented.

5.15.9.2.3 Cumulative

Cumulative impacts of Alternative 1 would be expected to be similar to those anticipated for the No

Action Alternative.

5.15.9.3 Alternative 2 – 10,000 cfs max Diversion

5.15.9.3.1 Direct

Direct impacts associated with construction of Alternative 2 would be expected to be similar to those

anticipated for Alternative 1.

5.15.9.3.2 Indirect

Indirect impacts of Alternative 2 would be expected to be similar to those anticipated for Alternative 1.

5.15.9.3.3 Cumulative

Cumulative impacts of Alternative 2 would be expected to be similar to those anticipated for the No

Action Alternative.

5.15.9.4 Alternative 3 – 15,000 cfs max Diversion

5.15.9.4.1 Direct

Direct impacts associated with construction of Alternative 3 would be expected to be similar to those

anticipated for Alternative 1.

5.15.9.4.2 Indirect

Indirect impacts of Alternative 3 would be expected to be similar to those anticipated for Alternative 1.

5.15.9.4.3 Cumulative

Cumulative impacts of Alternative 3 would be expected to be similar to those anticipated for the No

Action Alternative.

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5.15.9.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.9.5.1 Direct

Direct impacts associated with construction of Alternative 4 would be expected to be similar to those

anticipated for Alternative 1.

5.15.9.5.2 Indirect

Indirect impacts of Alternative 4 would be expected to be similar to those anticipated for Alternative 1.

5.15.9.5.3 Cumulative

Cumulative impacts of Alternative 4 would be expected to be similar to those anticipated for the No

Action Alternative.

5.15.10 Disruption of Desirable Community and Regional

Growth

5.15.10.1 No Action Alternative (Future Without Project Conditions)

5.15.10.1.1 Direct

Without construction of the proposed action there would be no direct impacts to community and regional

growth in the vicinity of the proposed diversion site.

5.15.10.1.2 Indirect

Without implementation of the proposed action there would be no indirect impacts to community and

regional growth in the project area and vicinity.

5.15.10.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts to community and regional growth consist

simply of the sum of the direct and indirect impacts for this alternative added to all other local and

regional activities, including construction of the GNOHSDRRS, and existing and in-progress elements of

the LCA Ecosystem Restoration program, including development of Freshwater Diversion sites.

Under the no action scenario, direct cumulative impacts remain no greater than the sum of those impacts

indicated individually for each project component of the aforementioned programs.

5.15.10.2 Alternative 1 – 5,000 cfs Diversion

5.15.10.2.1 Direct

There would be no direct impacts to community and regional growth around this diversion site if

Alternative 1 is constructed.

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5.15.10.2.2 Indirect

There would be no indirect impacts to community and regional growth in the project area and vicinity if

Alternative 1 is implemented.

5.15.10.2.3 Cumulative

Cumulative impacts resulting from implementation of Alternative 1 would be expected to be similar to

those anticipated for the No Action Alternative.

5.15.10.3 Alternative 2 – 10,000 cfs max Diversion

5.15.10.3.1 Direct

Direct impacts associated with construction of Alternative 2 would be expected to be similar to those

anticipated for Alternative 1.

5.15.10.3.2 Indirect

Indirect impacts of Alternative 2 would be expected to be similar to those anticipated for Alternative 1.

5.15.10.3.3 Cumulative

Cumulative impacts of Alternative 2 would be expected to be similar to those anticipated for the No

Action Alternative.

5.15.10.4 Alternative 3 – 15,000 cfs max Diversion

5.15.10.4.1 Direct

Direct impacts associated with construction of Alternative 3 would be expected to be similar to those

anticipated for Alternative 1.

5.15.10.4.2 Indirect

Indirect impacts of Alternative 3 would be expected to be similar to those anticipated for Alternative 1.

5.15.10.4.3 Cumulative

Cumulative impacts of Alternative 3 would be expected to be similar to those anticipated for the No

Action Alternative.

5.15.10.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.10.5.1 Direct

Direct impacts associated with construction of Alternative 4 would be expected to be similar to those

anticipated for Alternative 1.

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5.15.10.5.2 Indirect

Indirect impacts of Alternative 4 would be expected to be similar to those anticipated for Alternative 1.

5.15.10.5.3 Cumulative

Cumulative impacts of Alternative 4 would be expected to be similar to those anticipated for the No

Action Alternative.

5.15.11 Land Use Socioeconomics

5.15.11.1 Agriculture

5.15.11.1.1 No Action Alternative (Future Without Project Conditions)

5.15.11.1.1.1 Direct

There would be no direct impacts on commercial agriculture in the vicinity of the freshwater diversion

site if the proposed diversion is not constructed.

5.15.11.1.1.2 Indirect

There would be no indirect impacts on commercial agriculture in the project area and vicinity if the

proposed action is not implemented.

5.15.11.1.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts on commercial agriculture consist simply

of the sum of the direct and indirect impacts for this alternative added to all other local and regional

activities, including construction of the GNOHSDRRS, and existing and in-progress elements of the LCA

Ecosystem Restoration program, including development of freshwater diversion projects.

Under the no action scenario, direct and indirect cumulative impacts remain no greater than the sum of

those impacts indicated individually for each project component of the aforementioned programs.

5.15.11.1.2 Alternative 1 – 5,000 cfs Diversion

5.15.11.1.2.1 Direct

There would be no substantial direct impacts on commercial agriculture in the vicinity of the diversion

site if Alternative 1 is constructed.

Any alligator nesting sites located within the construction footprint could be temporarily disrupted during

construction activities if these activities occur during nest-building and incubation periods. Excavation of

outfall channels could permanently disrupt nesting activity within the footprint of this feature. However,

creation of marsh and ridges using material dredged during construction and maintenance of outfall

channels also could directly provide additional nesting habitat.

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5.15.11.1.2.2 Indirect

There would be no substantial indirect impacts on commercial agriculture in the project area and vicinity

if Alternative 1 is implemented.

Maximum flows from this alternative would be planned to occur in the MarchApril timeframe and

would return to maintenance flows (1,000 cfs) by the beginning of May. This would be just prior to the

season for alligator mating and nesting in this region. Water levels would not be substantially elevated

during maximum flow operation and would not measurably differ from without-project levels during

maintenance flow operations. For these reasons, no impacts to alligator reproductive cycles or egg

production would be anticipated to result from implementation of this alternative.

5.15.11.1.2.3 Cumulative

Cumulative impacts of Alternative 1 on commercial agriculture would be expected to be similar to those

anticipated for the No Action Alternative.

5.15.11.1.3 Alternative 2 – 10,000 cfs max Diversion

5.15.11.1.3.1 Direct

Direct impacts associated with construction of Alternative 2 would be expected to be similar to those

anticipated for Alternative 1.

5.15.11.1.3.2 Indirect

Indirect impacts resulting from implementation of Alternative 2 would be expected to be similar to those

anticipated for Alternative 1.

5.15.11.1.3.3 Cumulative

Cumulative impacts of Alternative 2 on commercial agriculture would be expected to be similar to those

anticipated for the No Action Alternative.

5.15.11.1.4 Alternative 3 – 10,000 cfs max Diversion

5.15.11.1.4.1 Direct

Direct impacts associated with construction of Alternative 3 would be expected to be similar to those

anticipated for Alternative 1.

5.15.11.1.4.2 Indirect

Indirect impacts resulting from implementation of Alternative 3 would be expected to be similar to those

anticipated for Alternative 1.

5.15.11.1.4.3 Cumulative

Cumulative impacts of Alternative 3 on commercial agriculture would be expected to be similar to those

anticipated for the No Action Alternative.

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5.15.11.1.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.11.1.5.1 Direct

Direct impacts associated with construction of Alternative 4 would be expected to be similar to those

anticipated for Alternative 1.

5.15.11.1.5.2 Indirect

Indirect impacts resulting from implementation of Alternative 4 would be expected to be similar to those

anticipated for Alternative 1.

During maximum flow, large areas of the marsh extending from approximately 1 mile south and west of

Bayou Garelle and the main outfall channel, extending to the northern extent of the project boundary, and

being contained by the River aux Chenes and Mississippi River ridges would be inundated on the order of

0.3 to 0.6 foot during maximum diversion operations. Maximum flows from this alternative would be

planned to occur in the MarchApril timeframe and would return to maintenance flows (1,000 cfs) by the

beginning of May at the latest, just prior to the season for alligator mating and nesting in this region.

These areas would quickly drain out to their naturally inundated area on the order of 5 to 7 days (going

from maximum diversions to the proposed 1,000 cfs maintenance flow).

There would not be a measurable difference in water levels during the 1,000 cfs maintenance flows. Tidal

conditions would be the driver of stages within the project area during this time and would not

measurably differ from without-project levels during maintenance flow operations. For these reasons, no

impacts to alligator reproductive cycles or egg production would be anticipated to result from

implementation of this alternative.

5.15.11.1.5.3 Cumulative

Cumulative impacts of Alternative 4 on commercial agriculture would be expected to be similar to those

anticipated for the No Action Alternative.

5.15.11.2 Forestry

5.15.11.2.1 No Action Alternative (Future Without Project Conditions)

5.15.11.2.1.1 Direct

There would be no direct impacts on commercial forestry production in the project area and vicinity if the

proposed diversion is not constructed.

5.15.11.2.1.2 Indirect

There would be no indirect impacts on commercial forestry production in the project area and vicinity if

the proposed action is not implemented.

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5.15.11.2.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts on commercial forestry production consist

simply of the sum of the direct and indirect impacts for this alternative added to all other local and

regional activities, including construction of the GNOHSDRRS, and existing and in-progress elements of

the LCA Ecosystem Restoration program, including development of freshwater diversion projects.

Under the no action scenario, direct cumulative impacts remain no greater than the sum of those impacts

indicated individually for each project component of the aforementioned programs.

5.15.11.2.2 Alternative 1 – 5,000 cfs Diversion

5.15.11.2.2.1 Direct

There would be no substantial direct impacts on commercial forestry production around the diversion site

if Alternative 1 is constructed.

5.15.11.2.2.2 Indirect

There would be no substantial indirect impacts on commercial forestry production in the project area and

vicinity if Alternative 1 is implemented.

5.15.11.2.2.3 Cumulative

Cumulative impacts of Alternative 1 on commercial forestry production would be expected to be similar

to those anticipated for the No Action Alternative.

5.15.11.2.3 Alternative 2 – 10,000 cfs max Diversion

5.15.11.2.3.1 Direct

Direct impacts on commercial forestry production associated with construction of Alternative 2 would be

expected to be similar to those anticipated for Alternative 1.

5.15.11.2.3.2 Indirect

Indirect impacts on commercial forestry production resulting from implementation of Alternative 2 would

be expected to be similar to those anticipated for Alternative 1.

5.15.11.2.3.3 Cumulative

Cumulative impacts of Alternative 2 on commercial forestry production would be expected to be similar

to those anticipated for the No Action Alternative.

5.15.11.2.4 Alternative 3 – 15,000 cfs max Diversion

5.15.11.2.4.1 Direct

Direct impacts on commercial forestry production associated with construction of Alternative 3 would be

expected to be similar to those anticipated for Alternative 1.

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5.15.11.2.4.2 Indirect

Indirect impacts on commercial forestry production resulting from implementation of Alternative 3 would

be expected to be similar to those anticipated for Alternative 1.

5.15.11.2.4.3 Cumulative

Cumulative impacts of Alternative 3 on commercial forestry production would be expected to be similar

to those anticipated for the No Action Alternative.

5.15.11.2.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.11.2.5.1 Direct

Direct impacts on commercial forestry production associated with construction of Alternative 4 would be

expected to be similar to those anticipated for Alternative 1.

5.15.11.2.5.2 Indirect

Indirect impacts on commercial forestry production resulting from implementation of Alternative 4 would

be expected to be similar to those anticipated for Alternative 1.

5.15.11.2.5.3 Cumulative

Cumulative impacts of Alternative 4 on commercial forestry production would be expected to be similar

to those anticipated for the No Action Alternative.

5.15.11.3 Public Lands

5.15.11.3.1 No Action Alternative (Future Without Project Conditions)

5.15.11.3.1.1 Direct

There would be no direct impacts on public lands in the project area and vicinity if the proposed diversion

is not constructed.

5.15.11.3.1.2 Indirect

There would be no indirect impacts on public lands in the project area and vicinity if the proposed action

is not implemented.

5.15.11.3.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts on public lands consist simply of the sum

of the direct and indirect impacts for this alternative added to all other local and regional activities,

including construction of the GNOHSDRRS, and existing and in-progress elements of the LCA

Ecosystem Restoration program, including development of freshwater diversion projects.

Under the no action scenario, direct cumulative impacts remain no greater than the sum of those impacts

indicated individually for each project component of the aforementioned programs.

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5.15.11.3.2 Alternative 1 – 5,000 cfs Diversion

5.15.11.3.2.1 Direct

There would be no substantial direct impacts on public lands around the diversion site if Alternative 1 is

constructed.

5.15.11.3.2.2 Indirect

There would be no substantial indirect impacts on public lands in the project area and vicinity if

Alternative 1 is implemented.

5.15.11.3.2.3 Cumulative

Cumulative impacts of Alternative 1 on public lands would be expected to be similar to those anticipated

for the No Action Alternative.

5.15.11.3.3 Alternative 2 – 10,000 cfs max Diversion

5.15.11.3.3.1 Direct

Direct impacts on public lands associated with construction of Alternative 2 would be expected to be

similar to those anticipated for Alternative 1.

5.15.11.3.3.2 Indirect

Indirect impacts on public lands resulting from implementation of Alternative 2 would be expected to be

similar to those anticipated for Alternative 1.

5.15.11.3.3.3 Cumulative

Cumulative impacts of Alternative 2 on public lands would be expected to be similar to those anticipated

for the No Action Alternative.

5.15.11.3.4 Alternative 3 – 15,000 cfs max Diversion

5.15.11.3.4.1 Direct

Direct impacts on public lands associated with construction of Alternative 3 would be expected to be

similar to those anticipated for Alternative 1.

5.15.11.3.4.2 Indirect

Indirect impacts on public lands resulting from implementation of Alternative 3 would be expected to be

similar to those anticipated for Alternative 1.

5.15.11.3.4.3 Cumulative

Cumulative impacts of Alternative 3 on public lands would be expected to be similar to those anticipated

for the No Action Alternative.

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5.15.11.3.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.11.3.5.1 Direct

Direct impacts on public lands associated with construction of Alternative 4 would be expected to be

similar to those anticipated for Alternative 1.

5.15.11.3.5.2 Indirect

Indirect impacts on public lands resulting from implementation of Alternative 4 would be expected to be

similar to those anticipated for Alternative 1.

5.15.11.3.5.3 Cumulative

Cumulative impacts of Alternative 4 on public lands would be expected to be similar to those anticipated

for the No Action Alternative.

5.15.12 Water Use and Supply

5.15.12.1 No Action Alternative (Future Without Project Conditions)

5.15.12.1.1 Direct

There would be no direct impacts on water use and supply in the project area and vicinity if the proposed

diversion is not constructed.

5.15.12.1.2 Indirect

There would be no indirect impacts on water use and supply in the project area and vicinity if the

proposed action is not implemented.

5.15.12.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts on water use and supply consist simply of

the sum of the direct and indirect impacts for this alternative added to all other local and regional

activities, including construction of the GNOHSDRRS, and existing and in-progress elements of the LCA

Ecosystem Restoration program, including development of freshwater diversion projects.

Under the no action scenario, direct and indirect cumulative impacts remain no greater than the sum of

those impacts indicated individually for each project component of the aforementioned programs.

5.15.12.2 Alternative 1 – 5,000 cfs Diversion

5.15.12.2.1 Direct

Construction of Alternative 1 could require replacement of a water supply pipeline at the diversion site to

continue providing water services to the Pointe à la Hache and Phoenix communities. Short-term impacts

to water delivery could potentially occur during replacement; however, no long-term interruptions to

delivery of water supply would be anticipated.

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5.15.12.2.2 Indirect

Implementation of Alternative 1 is not anticipated to have any indirect impacts to water supply and use in

the project area and vicinity.

5.15.12.2.3 Cumulative

Cumulative impacts on water supply and use resulting from implementation of Alternative 1 would be

expected to be similar to those anticipated for the No Action Alternative.

5.15.12.3 Alternative 2 – 10,000 cfs max Diversion

5.15.12.3.1 Direct

Direct impacts of Alternative 2 would be expected to be similar to those anticipated for Alternative 1.

5.15.12.3.2 Indirect

Indirect impacts of Alternative 2 would be expected to be similar to those anticipated for Alternative 1.

5.15.12.3.3 Cumulative

Cumulative impacts on water supply and use resulting from implementation of Alternative 2 would be

expected to be similar to those anticipated for the No Action Alternative.

5.15.12.4 Alternative 3 – 15,000 cfs max Diversion

5.15.12.4.1 Direct

Direct impacts of Alternative 3 would be expected to be similar to those anticipated for Alternative 1.

5.15.12.4.2 Indirect

Indirect impacts of Alternative 3 would be expected to be similar to those anticipated for Alternative 1.

5.15.12.4.3 Cumulative

Cumulative impacts on water supply and use resulting from implementation of Alternative 3 would be

expected to be similar to those anticipated for the No Action Alternative.

5.15.12.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.12.5.1 Direct

Direct impacts of Alternative 4 would be expected to be similar to those anticipated for Alternative 1.

5.15.12.5.2 Indirect

Indirect impacts of Alternative 4 would be expected to be similar to those anticipated for Alternative 1.

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5.15.12.5.3 Cumulative

Cumulative impacts on water supply and use resulting from implementation of Alternative 4 would be

expected to be similar to those anticipated for the No Action Alternative.

5.15.13 Navigation

5.15.13.1 No Action Alternative (Future Without Project Conditions)

5.15.13.1.1 Direct

There would be no direct impacts on navigation in the project area and vicinity if the proposed diversion

is not constructed.

5.15.13.1.2 Indirect

There would be no indirect impacts on navigation in the project area and vicinity if the proposed action is

not implemented.

5.15.13.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts on navigation consist simply of the sum

of the direct and indirect impacts for this alternative added to all other local and regional activities,

including construction of the GNOHSDRRS, and existing and in-progress elements of the LCA

Ecosystem Restoration program, including development of freshwater diversion projects.

Under the no action scenario, direct and indirect cumulative impacts remain no greater than the sum of

those impacts indicated individually for each project component of the aforementioned programs.

5.15.13.2 Alternative 1 – 5,000 cfs Diversion

5.15.13.2.1 Direct

Construction of Alternative 1 could disturb current flow patterns in the Mississippi River adjacent to the

diversion site, requiring merchant vessels to compensate for the diverted current. The potential for

disruption in current patterns during construction is not anticipated to be substantial enough to require

alteration of the navigation channel or disruption in traffic on the waterway.

5.15.13.2.2 Indirect

Under the operation plan evaluated in this feasibility study and SEIS, implementation of Alternative 1

would involve diversion of Mississippi River flows into the project area at a rate of 5,000 cfs for up to 60

days in the spring (MarchApril) and at a rate of up to 1,000 cfs the remaining days of the year. Diversion

of river sediment and water with this operating plan is unlikely to increase the potential for sedimentation

and shoaling in the Mississippi River downstream of the diversion, or to require additional or increased

dredging. Based on the small size of the diversion relative to the average Mississippi River flows and the

limited number of days when the diversion would be operated at maximum capacity, no indirect adverse

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impacts would be expected to result from this alternative. Additional discussion of the potential effects of

the White Ditch diversion project would be provided in Appendix N of this report.

Channels and canals within the project area could be affected by project implementation. The alternative

would introduce sediment into the project area for the purpose of creating marsh. Most of this sediment

would accumulate in open water areas where there is little to no flow. However, some could accumulate

in channels and canals. It could potentially become necessary to perform maintenance dredging on some

channels and canals.

5.15.13.2.3 Cumulative

Cumulative impacts of Alternative 1 on navigation consists simply of the sum of the direct and indirect

impacts for this alternative added to all other local and regional activities, including construction of the

GNOHSDRRS, and existing and in-progress elements of the LCA Ecosystem Restoration program,

including development of freshwater diversion projects.

The unconstructed Myrtle Grove diversion would be directly across the river from the proposed White

Ditch structure. The combination effect of these two structures working in such close proximity to each

other on opposite sides of the river could create changes in the Mississippi River.

Other existing and proposed diversions on the Mississippi River could collectively have impacts on flows

and sediments. While many of the projects along the Mississippi River would be considered small

diversions (1005,000 cfs), the collective impacts of the whole could have effects on flows and stages

from the Mississippi River. System-wide coordination of diversion operations would likely be necessary.

5.15.13.3 Alternative 2 – 10,000 cfs max Diversion

5.15.13.3.1 Direct

Direct impacts to navigation resulting from construction of Alternative 2 would be expected to be similar

to those anticipated for Alternative 1.

5.15.13.3.2 Indirect

Under the operation plan evaluated in this feasibility study and SEIS, implementation of Alternative 2

would involve diversion of Mississippi River flows into the project area at a rate of 10,000 cfs for up to

60 days in the spring (MarchApril) and at a rate of up to 1,000 cfs the remaining days of the year.

Diversion of river sediment and water with this operating plan is unlikely to increase the potential for

sedimentation and shoaling in the Mississippi River downstream of the diversion, or to require additional

or increased dredging.

While the potential for indirect impacts of Alternative 2 is greater than for Alternative 1 based on the

difference in maximum flow capacity, because of the comparatively small size of the diversion relative to

the average Mississippi River flows and the limited number of days when the diversion would be

operated at maximum capacity, no indirect adverse impacts would be expected to result from this

alternative. Additional discussion of the potential effects of the White Ditch diversion project would be

provided in Appendix N of this report.

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Channels and canals within the project area could be affected by project implementation. The alternative

would introduce sediment into the project area for the purpose of creating marsh. Most of this sediment

would accumulate in open water areas where there is little to no flow. However, some could accumulate

in channels and canals. It could potentially become necessary to perform maintenance dredging on some

channels and canals.

5.15.13.3.3 Cumulative

Cumulative impacts of Alternative 1 on navigation consists simply of the sum of the direct and indirect

impacts for this alternative added to all other local and regional activities, including construction of the

GNOHSDRRS, and existing and in-progress elements of the LCA Ecosystem Restoration program,

including development of freshwater diversion projects.

The unconstructed Myrtle Grove diversion would be directly across the river from the proposed White

Ditch structure. The combination effect of these two structures working in such close proximity to each

other on opposite sides of the river could create changes in the Mississippi River.

Other existing and proposed diversions on the Mississippi River could collectively have impacts on flows

and sediments. While many of the projects along the Mississippi River would be considered small

diversions (1005,000 cfs), the collective impacts of the whole could have effects on flows and stages

from the Mississippi River. System-wide coordination of diversion operations would likely be necessary.

5.15.13.4 Alternative 3 – 15,000 cfs max Diversion

5.15.13.4.1 Direct

Direct impacts to navigation resulting from construction of Alternative 3 would be expected to be similar

to those anticipated for Alternative 1.

5.15.13.4.2 Indirect

Under the operation plan evaluated in this feasibility study and SEIS, implementation of Alternative 3

would involve diversion of Mississippi River flows into the project area at a rate of 15,000 cfs for up to

60 days in the spring (MarchApril) and at a rate of up to 1,000 cfs the remaining days of the year.

Diversion of river sediment and water with this operating plan is unlikely to increase the potential for

sedimentation and shoaling in the Mississippi River downstream of the diversion, or to require additional

or increased dredging.

While the potential for indirect impacts of Alternative 3 is greater than for Alternatives 1 or 2 based on

the difference in maximum flow capacity, because of the comparatively small size of the diversion

relative to the average Mississippi River flows and the limited number of days when the diversion would

be operated at maximum capacity, no substantial indirect adverse impacts would be expected to result

from this alternative. Additional discussion of the potential effects of the White Ditch diversion project

would be provided in Appendix N of this report.

Channels and canals within the project area could be affected by project implementation. The alternative

would introduce sediment into the project area for the purpose of creating marsh. Most of this sediment

would accumulate in open water areas where there is little to no flow. However, some could accumulate

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in channels and canals. It could potentially become necessary to perform maintenance dredging on some

channels and canals.

5.15.13.4.3 Cumulative

Cumulative impacts of Alternative 1 on navigation consists simply of the sum of the direct and indirect

impacts for this alternative added to all other local and regional activities, including construction of the

GNOHSDRRS, and existing and in-progress elements of the LCA Ecosystem Restoration program,

including development of freshwater diversion projects.

The unconstructed Myrtle Grove diversion would be directly across the river from the proposed White

Ditch structure. The combination effect of these two structures working in such close proximity to each

other on opposite sides of the river could create changes in the Mississippi River.

Other existing and proposed diversions on the Mississippi River could collectively have impacts on flows

and sediments. While many of the projects along the Mississippi River would be considered small

diversions (1005,000 cfs), the collective impacts of the whole could have effects on flows and stages

from the Mississippi River. System-wide coordination of diversion operations would likely be necessary.

5.15.13.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.13.5.1 Direct

Direct impacts to navigation resulting from construction of Alternative 4 would be expected to be similar

to those anticipated for Alternative 1.

5.15.13.5.2 Indirect

Under the operation plan evaluated in this feasibility study and SEIS, implementation of Alternative 4

would involve diversion of Mississippi River flows into the project area at a rate up to 35,000 cfs for up

to 60 days in the spring (MarchApril) and at a rate of up to 1,000 cfs the remaining days of the year.

Diversion of river sediment and water with this operating plan is unlikely to substantially increase the

potential for sedimentation and shoaling in the Mississippi River downstream of the diversion, or to

require additional or increased dredging over the 50-year planning horizon.

While the potential for indirect impacts of Alternative 4 is greater than for Alternatives 1, 2, or 3 based on

the difference in maximum flow capacity, because of the small size of the diversion relative to the

average Mississippi River flows during the maximum capacity operation period, and the limited number

of days when the diversion would be operated at maximum capacity, no substantial indirect adverse

impacts would be expected to result from this alternative. Additional discussion of the potential effects of

the White Ditch diversion project would be provided in Appendix N of this report.

Channels and canals within the project area could be affected by project implementation. The alternative

would introduce sediment into the project area for the purpose of creating marsh. Most of this sediment

would accumulate in open water areas where there is little to no flow. However, some could accumulate

in channels and canals. It could potentially become necessary to perform maintenance dredging on some

channels and canals.

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5.15.13.5.3 Cumulative

Cumulative impacts of Alternative 1 on navigation consists simply of the sum of the direct and indirect

impacts for this alternative added to all other local and regional activities, including construction of the

GNOHSDRRS, and existing and in-progress elements of the LCA Ecosystem Restoration program,

including development of freshwater diversion projects.

The unconstructed Myrtle Grove diversion would be directly across the river from the proposed White

Ditch structure. The combination effect of these two structures working in such close proximity to each

other on opposite sides of the river could create changes in the Mississippi River.

Other existing and proposed diversions on the Mississippi River could collectively have impacts on flows

and sediments. While many of the projects along the Mississippi River would be considered small

diversions (1005,000 cfs), the collective impacts of the whole could have effects on flows and stages

from the Mississippi River. System-wide coordination of diversion operations would likely be necessary.

5.15.14 Man-Made Resources

5.15.14.1 Oil, Gas, Utilities

5.15.14.1.1 No Action Alternative (Future Without Project Conditions)

5.15.14.1.1.1 Direct

There would be no direct impacts on oil, gas, and utilities in the project area and vicinity if the proposed

diversion is not constructed.

5.15.14.1.1.2 Indirect

There would be no indirect impacts on oil, gas, and utilities in the project area and vicinity if the proposed

action is not implemented.

5.15.14.1.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts on oil, gas, and utilities consist simply of

the sum of the direct and indirect impacts for this alternative added to all other local and regional

activities, including construction of the GNOHSDRRS, and existing and in-progress elements of the LCA

Ecosystem Restoration program, including development of freshwater diversion projects.

Under the no action scenario, direct cumulative impacts remain no greater than the sum of those impacts

indicated individually for each project component of the aforementioned programs.

5.15.14.1.2 Alternative 1 – 5,000 cfs Diversion

5.15.14.1.2.1 Direct

Construction of Alternative 1 could require avoidance or relocation or of several wells located near the

construction footprint of the diversion. There would be no pipelines located within or near the

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construction footprint. Construction activities would not be expected to result in direct impact to utilities

or oil services within the diversion area.

5.15.14.1.2.2 Indirect

No indirect impacts on oil or gas utilities would be expected to occur in the project area and vicinity if

Alternative 1 is not implemented.

5.15.14.1.2.3 Cumulative

Cumulative impacts on oil or gas utilities resulting from implementation of Alternative 1 would be

expected to be similar to those anticipated for the No Action Alternative.

5.15.14.1.3 Alternative 2 – 10,000 cfs max Diversion

5.15.14.1.3.1 Direct

Direct impacts on oil or gas utilities associated with construction of Alternative 2 would be expected to be

similar to those anticipated for Alternative 1.

5.15.14.1.3.2 Indirect

Indirect impacts to oil or gas utilities resulting from implementation of Alternative 2 would be expected to

be similar to those anticipated for Alternative 1.

5.15.14.1.3.3 Cumulative

Cumulative impacts on oil or gas utilities resulting from implementation of Alternative 2 would be

expected to be similar to those anticipated for the No Action Alternative.

5.15.14.1.4 Alternative 3 – 15,000 cfs max Diversion

5.15.14.1.4.1 Direct

Direct impacts on oil or gas utilities associated with construction of Alternative 3 would be expected to be

similar to those anticipated for Alternative 1.

5.15.14.1.4.2 Indirect

Indirect impacts to oil or gas utilities resulting from implementation of Alternative 3 would be expected to

be similar to those anticipated for Alternative 1.

5.15.14.1.4.3 Cumulative

Cumulative impacts on oil or gas utilities resulting from implementation of Alternative 3 would be

expected to be similar to those anticipated for the No Action Alternative.

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5.15.14.1.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.14.1.5.1 Direct

Direct impacts on oil or gas utilities associated with construction of Alternative 4 would be expected to be

similar to those anticipated for Alternative 1.

5.15.14.1.5.2 Indirect

Indirect impacts to oil or gas utilities resulting from implementation of Alternative 4 would be expected to

be similar to those anticipated for Alternative 1.

5.15.14.1.5.3 Cumulative

Cumulative impacts on oil or gas utilities resulting from implementation of Alternative 4 would be

expected to be similar to those anticipated for the No Action Alternative.

5.15.14.2 Flood Control and Hurricane Protection

5.15.14.2.1 No Action Alternative (Future Without Project Conditions)

5.15.14.2.1.1 Direct

There would be no direct impacts on flood control and hurricane protection in the project area and

vicinity if the proposed diversion is not constructed.

5.15.14.2.1.2 Indirect

There would be no indirect impacts on flood control and hurricane protection in the project area and

vicinity if the proposed action is not implemented.

5.15.14.2.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts on flood control and hurricane protection

consist simply of the sum of the direct and indirect impacts for this alternative added to all other local and

regional activities, including construction of the GNOHSDRRS, and existing and in-progress elements of

the LCA Ecosystem Restoration program, including development of Freshwater Diversion sites.

Under the no action scenario, cumulative impacts remain no greater than the sum of those impacts

indicated individually for each project component of the aforementioned programs.

5.15.14.2.2 Alternative 1 – 5,000 cfs Diversion

5.15.14.2.2.1 Direct

Construction of Alternative 1 would involve construction of a diversion structure through/under the

Federal Mississippi River levee, and excavation of outfall management channels leading away from the

diversion structure on the east side of the Federal levee. Construction activity would not directly affect

any non-Federal levees located to the north or south of the construction site. Construction specifications

would include measures to ensure that the integrity of the levee is not compromised and the level of

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protection during high river stages or storm surges is not lessened at any time during or after construction.

For these reasons, no adverse impacts to flood control and hurricane protection would be expected to

result from construction of this alternative.

5.15.14.2.2.2 Indirect

Indirect effects within the project area resulting from operation of Alternative 1 would include an increase

in water levels within interior distributaries such as River aux Chenes and Bayou Garelle, and minor

increased inundation of low-lying lands, particularly when the diversion is operated at maximum

capacity. These hydrologic alterations would be expected to distribute and deposit river sediments

throughout the project area. No significant adverse effects on existing Federal or non-Federal levees

would be expected to result from implementation of this alternative.

5.15.14.2.2.3 Cumulative

Cumulative impacts would be the synergistic effect of Alternative 1 on flow and water levels with the

added combination of similar wetland degradation and wetland loss impacts to flow and water levels

throughout coastal Louisiana, as well as the benefits and impacts of other state and Federal coastal

restoration projects in the vicinity.

Cumulative indirect impacts of this alternative combined with other state and Federal coastal restoration

projects could potentially benefit existing and proposed flood control and hurricane protection projects by

decreasing the vulnerability of protective works to wind and wave erosion from hurricane and tropical

storm surges.

Operations of the White Ditch structure would need to be done in consideration with the existing

Caernarvon diversion, as well as the proposed CWPPRA project for the rehabilitation and expansion of

the existing siphon at White Ditch. Coordinated operations of all three structures would be necessary to

optimize potential benefits within the Breton Sound Basin. Uncoordinated efforts could lead to prolonged

inundation, or excessively elevated water levels on Federal and non-Federal levees in the project area and

vicinity.

5.15.14.2.3 Alternative 2 – 10,000 cfs max Diversion

5.15.14.2.3.1 Direct

Direct impacts to flood control and hurricane protection in the project area and vicinity associated with

construction of Alternative 2 would be expected to be similar to those anticipated for Alternative 1.

5.15.14.2.3.2 Indirect

While the maximum inflow capacity of this alternative is incrementally greater than that of Alternative 1,

indirect impacts on flood control and hurricane protection resulting from implementation of Alternative 2

would be expected to be similar to those anticipated for Alternative 1.

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5.15.14.2.3.3 Cumulative

Cumulative impacts to flood control and hurricane protection resulting from implementation of

Alternative 2 would be expected to be similar to, though incrementally greater than, those anticipated for

Alternative 1.

5.15.14.2.4 Alternative 3 – 15,000 cfs max Diversion

5.15.14.2.4.1 Direct

Direct impacts to flood control and hurricane protection in the project area and vicinity associated with

construction of Alternative 3 would be expected to be similar to those anticipated for Alternative 1.

5.15.14.2.4.2 Indirect

While the maximum inflow capacity of this alternative is incrementally greater than that of Alternative 1,

indirect impacts on flood control and hurricane protection resulting from implementation of Alternative 3

would be expected to be similar to those anticipated for Alternative 1.

5.15.14.2.4.3 Cumulative

Cumulative impacts to flood control and hurricane protection resulting from implementation of

Alternative 3 would be expected to be similar to, though incrementally greater than, those anticipated for

Alternative 1.

5.15.14.2.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.14.2.5.1 Direct

Direct impacts to flood control and hurricane protection in the project area and vicinity associated with

construction of Alternative 4 would be expected to be similar to those anticipated for Alternative 1.

5.15.14.2.5.2 Indirect

While the maximum inflow capacity of this alternative is incrementally greater than that of Alternative 1,

indirect impacts on flood control and hurricane protection resulting from implementation of Alternative 4

would be expected to be similar to those anticipated for Alternative 1.

5.15.14.2.5.3 Cumulative

Cumulative impacts to flood control and hurricane protection resulting from implementation of

Alternative 4 would be expected to be similar to, though incrementally greater than, those anticipated for

Alternative 1.

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5.15.15 Natural Resources

5.15.15.1 Commercial Fisheries

5.15.15.1.1 No Action Alternative (Future Without Project Conditions)

5.15.15.1.1.1 Direct

There would be no direct impacts on natural resources and commercial fisheries within the project area

and vicinity if the proposed diversion is not constructed.

5.15.15.1.1.2 Indirect

Without implementation of the proposed diversion, indirect impacts on natural resources and commercial

fisheries would occur as a result of continuing loss of emergent wetland and increase in shallow open

water. Increased saltwater intrusion into some of the upper portions of the project area would be

anticipated as marshes continued to degrade. In time, this would result in a shift in the populations of

fishes and invertebrates, with more saline-dominated species replacing freshwater species in previously

intermediate-to-fresh areas. Over the 50-year planning horizon, essential fish habitat for many

commercial fishery species would likewise decline, leading to a net loss in fisheries population size and

diversity.

5.15.15.1.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts on commercial fisheries consist simply of

the sum of the direct and indirect impacts for this alternative added to all other local and regional

activities, including construction of the GNOHSDRRS, and existing and in-progress elements of the LCA

Ecosystem Restoration program, including development of Freshwater Diversion sites.

Under the no action scenario, cumulative impacts remain no greater than the sum of those impacts

indicated individually for each project component of the aforementioned programs.

Without the contribution of the proposed White Ditch diversion, continued wetland habitat losses would

incrementally decrease the productivity of Louisiana's coastal fisheries. The commercial fishing and

seafood industry could potentially suffer losses in employment as estuaries that would be necessary to

produce shrimp, oysters, and other valuable species, erode. Job losses could occur in the areas reliant on

fishing, harvesting, processing, and shipping of the seafood catch. Thus, changes in existing fisheries

habitat caused by wetland loss, saltwater intrusion, and reduced salinity gradients would likely increase

the risk of a decline in the supply of nationally distributed seafood products from Louisiana's coast.

5.15.15.1.2 Alternative 1 – 5,000 cfs Diversion

5.15.15.1.2.1 Direct

Construction of the outfall management features required for Alternative 1 could have a direct impact on

natural resources and commercial fishing in the immediate vicinity of the construction site as a result of

excavation of material for channel construction, placement of excavated material to create marsh and

ridge habitat, and construction notched flow restrictors at selected canal connections to River aux Chenes.

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During and after construction, direct impacts to commercial fisheries of Alternative 1 would primarily be

related to reduced or impeded access to fishing areas.

5.15.15.1.2.2 Indirect

Implementation of Alternative 1 would have indirect impacts on commercial fisheries by affecting the

location of target species. Changes in salinity levels in the project area as a result of project operation (see

Section 5.3, Water Quality) would change the distribution of fish and shellfish species based on their

salinity tolerance. Changes in fisheries distribution would in turn impact commercial fishing patterns and

locations. There is also a potential for some indirect impact on commercial seafood processing facilities

located on the West Bank of Plaquemines Parish if Alternative 1 is implemented.

Over the 50-year planning horizon, implementation of Alternative 1 is expected to benefit commercial

fisheries by decreasing the rate of loss of marsh and associated critical nursery habitat in the project area

compared to the No Action Alternative. Alternative 1 is projected to provide a net benefit of

approximately 5,197 AAHUs over the period of analysis, thereby benefitting the nationally important

commercial fishing industry in the area.

5.15.15.1.2.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts on commercial fisheries consist simply of

the sum of the direct and indirect impacts for this alternative added to all other local and regional

activities, including construction of the GNOHSDRRS, and existing and in-progress elements of the LCA

Ecosystem Restoration program, including development of freshwater diversion sites.

Cumulative impacts on commercial fisheries resulting from implementation of Alternative 1 would

incrementally increase the availability of marsh and estuarine habitat essential to support several

commercially targeted species of fish and shellfish at critical life stages. This incremental effect combined

with existing and planned restoration efforts in the state (e.g., CWPPRA, the Community-based

Restoration Program sponsored by the NMFS Restoration Center, various state and local efforts, and

others) would continue to aid fisheries habitat. It is likely that the construction of levees, water control

structures and hurricane protection features, which can result in direct loss of habitat, alter water flow,

and have the potential to block fisheries access to habitat, would continue and/or increase, as coastal

residents protect themselves and their property from hurricane damage and flooding. Implementation of

Alternative 1 would contribute to an overall benefit to commercial fisheries compared to the future with

no action.

5.15.15.1.3 Alternative 2 – 10,000 cfs max Diversion

5.15.15.1.3.1 Direct

Construction of the outfall management features required for Alternative 2 could have a direct impact on

natural resources and commercial fishing in the immediate vicinity of the construction site as a result of

excavation of material for channel construction, placement of excavated material to create marsh and

ridge habitat, and construction of notched restrictors at selected canal connections to River aux Chenes.

During and after construction, direct impacts to commercial fisheries of Alternative 2 would primarily be

related to reduced or impeded access to fishing areas.

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5.15.15.1.3.2 Indirect

Implementation of Alternative 2 would have indirect impacts on commercial fisheries by affecting the

location of target species. Changes in salinity levels in the project area as a result of project operation (see

Section 5.3, Water Quality) would change the distribution of fish and shellfish species based on their

salinity tolerance. Changes in fisheries distribution would in turn impact commercial fishing patterns and

locations. There is also a potential for some indirect impact on commercial seafood processing facilities

located on the West Bank of Plaquemines Parish if Alternative 2 is implemented.

Over the 50-year planning horizon, implementation of Alternative 2 is expected to benefit commercial

fisheries by decreasing the rate of loss of marsh and critical nursery habitat in the project area compared

to the No Action Alternative. Alternative 2 is projected to provide a net benefit of approximately 5,936

AAHUs over the period of analysis, thereby benefitting the nationally important commercial fishing

industry in the area.

5.15.15.1.3.3 Cumulative

Cumulative impacts on commercial fisheries resulting from implementation of Alternative 2 would

incrementally increase the availability of marsh and estuarine habitat essential to support several

commercially targeted species of fish and shellfish at critical life stages. This incremental effect combined

with existing and planned restoration efforts in the state (e.g., CWPPRA, the Community-based

Restoration Program sponsored by the NMFS Restoration Center, various state and local efforts, and

others) would continue to aid fisheries habitat. It is likely that the construction of levees, water control

structures and hurricane protection features, which can result in direct loss of habitat, alter water flow,

and have the potential to block fisheries access to habitat, would continue and/or increase, as coastal

residents protect themselves and their property from hurricane damage and flooding. Implementation of

Alternative 2 would contribute to an overall benefit to commercial fisheries compared to the future with

no action.

5.15.15.1.4 Alternative 3 – 15,000 cfs max Diversion

5.15.15.1.4.1 Direct

Construction of the outfall management features required for Alternative 3 could have a direct impact on

natural resources and commercial fishing in the immediate vicinity of the construction site as a result of

excavation of material for channel construction, placement of excavated material to create marsh and

ridge habitat, and construction notched restrictors at selected canal connections to River aux Chenes.

During and after construction, direct impacts to commercial fisheries of Alternative 3 would primarily be

related to reduced or impeded access to fishing areas.

5.15.15.1.4.2 Indirect

Implementation of Alternative 3 would have indirect impacts on commercial fisheries by affecting the

location of target species. Changes in salinity levels in the project area as a result of project operation (see

Section 5.3, Water Quality) would change the distribution of fish and shellfish species based on their

salinity tolerance. Changes in fisheries distribution would in turn impact commercial fishing patterns and

locations. There is also a potential for some indirect impact on commercial seafood processing facilities

located on the West Bank of Plaquemines Parish if Alternative 2 is implemented.

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Over the 50-year planning horizon, implementation of Alternative 3 is expected to benefit commercial

fisheries by restoring marsh and critical nursery habitat in the project area compared to the No Action

Alternative. Alternative 3 is projected to provide a net benefit of approximately 7,742 AAHUs over the

period of analysis, thereby benefitting the nationally important commercial fishing industry in the area.

5.15.15.1.4.3 Cumulative

Cumulative impacts on commercial fisheries resulting from implementation of Alternative 3 would

incrementally increase the availability of marsh and estuarine habitat essential to support several

commercially targeted species of fish and shellfish at critical life stages. This incremental effect combined

with existing and planned restoration efforts in the state (e.g., CWPPRA, the Community-based

Restoration Program sponsored by the NMFS Restoration Center, various state and local efforts, and

others) would continue to aid fisheries habitat. It is likely that the construction of levees, water control

structures and hurricane protection features, which can result in direct loss of habitat, alter water flow,

and have the potential to block fisheries access to habitat, would continue and/or increase, as coastal

residents protect themselves and their property from hurricane damage and flooding. Implementation of

Alternative 3 would contribute to an overall benefit to commercial fisheries compared to the future with

no action.

5.15.15.1.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.15.1.5.1 Direct

Construction of the outfall management features required for Alternative 4 could have a direct impact on

natural resources and commercial fishing in the immediate vicinity of the construction site as a result of

excavation of material for channel construction, placement of excavated material to create marsh and

ridge habitat, and construction notched restrictors at selected canal connections to River aux Chenes.

During and after construction, direct impacts to commercial fisheries of Alternative 4 would primarily be

related to reduced or impeded access to fishing areas.

5.15.15.1.5.2 Indirect

Implementation of Alternative 4 would have indirect impacts on commercial fisheries by affecting the

location of target species. Changes in salinity levels in the project area as a result of project operation (see

Section 5.3, Water Quality) would change the distribution of fish and shellfish species based on their

salinity tolerance. Changes in fisheries distribution would in turn impact commercial fishing patterns and

locations. There is also a potential for some indirect impact on commercial seafood processing facilities

located on the West Bank of Plaquemines Parish if Alternative 2 is implemented.

Over the 50-year planning horizon, implementation of Alternative 4 is expected to benefit commercial

fisheries by restoring marsh and critical nursery habitat in the project area compared to the No Action

Alternative. Alternative 4 is projected to provide a net benefit of approximately 13,355 AAHUs over the

period of analysis, thereby benefitting the nationally important commercial fishing industry in the area.

5.15.15.1.5.3 Cumulative

Cumulative impacts on commercial fisheries resulting from implementation of Alternative 4 would

incrementally increase the availability of marsh and estuarine habitat essential to support several

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commercially targeted species of fish and shellfish at critical life stages. This incremental effect combined

with existing and planned restoration efforts in the state (e.g., CWPPRA, the Community-based

Restoration Program sponsored by the NMFS Restoration Center, various state and local efforts, and

others) would continue to aid fisheries habitat. It is likely that the construction of levees, water control

structures and hurricane protection features, which can result in direct loss of habitat, alter water flow,

and have the potential to block fisheries access to habitat, would continue and/or increase, as coastal

residents protect themselves and their property from hurricane damage and flooding. Implementation of

Alternative 4 would contribute to an overall benefit to commercial fisheries compared to the future with

no action.

5.15.15.2 Oyster Leases

5.15.15.2.1 No Action Alternative (Future Without Project Conditions)

5.15.15.2.1.1 Direct

There would be no direct impacts to oyster leases in the project area and vicinity if the proposed diversion

is not constructed.

5.15.15.2.1.2 Indirect

Without implementation of the proposed diversion, indirect impacts on natural resources and oyster leases

would occur as a result of continuing loss of emergent wetland and increase in shallow open water.

Increased saltwater intrusion into some of the upper portions of the project area would be anticipated as

marshes continued to degrade. In time, this would result in a shift in oyster population toward the middle

and upper reaches of the estuary. At the same time, currently productive oyster leases in the lower

portions of the project area could degrade in time if salinity shifts above the optimal range. Over the 50-

year planning horizon, optimal habitat for oyster production would likewise decline, leading to a net loss

in oyster lease productivity and harvest.

5.15.15.2.1.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts on oyster leases consist simply of the sum

of the direct and indirect impacts for this alternative added to all other local and regional activities,

including construction of the GNOHSDRRS, and existing and in-progress elements of the LCA

Ecosystem Restoration program, including development of Freshwater Diversion sites.

Under the no action scenario, cumulative impacts remain no greater than the sum of those impacts

indicated individually for each project component of the aforementioned programs.

Without the contribution of the proposed White Ditch diversion, continued wetland habitat losses would

incrementally decrease the productivity of Louisiana's coastal fisheries, including oyster beds. The

commercial fishing and seafood industry could potentially suffer losses in employment as estuaries that

would be necessary to produce shrimp, oysters, and other valuable species, erode. Job losses could occur

in the areas reliant on fishing, harvesting, processing, and shipping of the seafood catch. Thus, changes in

existing fisheries habitat caused by wetland loss, saltwater intrusion, and reduced salinity gradients would

likely increase the risk of a decline in the supply of nationally distributed seafood products from

Louisiana's coast.

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5.15.15.2.2 Alternative 1 – 5,000 cfs Diversion

5.15.15.2.2.1 Direct

No measurable direct impacts to oyster leases would be anticipated to result from construction of

Alternative 1, primarily because the construction footprint is located in the upper portion of the project

area, where existing salinity conditions would be not favorable for oysters and where no leases currently

exist, as determined from examination of state databases.

5.15.15.2.2.2 Indirect

Indirect impacts to oyster leases around this diversion site if Alternative 1 is implemented could include

increased rate of mortality and decrease in productivity in oyster leases located closest to the diversion

site, during the period when the diversion is at full operational capacity and for up to 2 months after the

return to maintenance flow conditions. This could result in a loss of revenue for commercial oyster

harvesters.

The operational plan proposed and evaluated in this feasibility study and SEIS limits the period of full

flow to no more than 2 months (60 days) in the spring timeframe (MarchApril was used in the analysis).

It was formulated in part to avoid or minimize the potential for incidental adverse effects (e.g. mortality,

interference with reproduction) to oysters and other invertebrate or fishery species that require brackish or

saline environments. Hydraulic modeling of the project area indicated that the return to maintenance

flows for the remainder of the year (10 months) should maintain brackish and saline zones in the project

area, though at somewhat reduced average salinities. The number of leases impacted should be less than

for the 35,000 cfs alternative because the recovery time should be quicker. For these reasons, indirect

adverse impacts to oyster leases would not be anticipated to be significant.

Over the 50-year planning horizon, potential beneficial effects to oyster populations could result if

reduced salinities resulting from diversion operation were to increase the spatial extent of habitats

experiencing salinities in the optimal range for oyster production. Continued water quality and biological

monitoring of the project area before and after project construction should assist in refining the operation

plan as needed to meet project objectives for restoring marsh while maintaining a functioning salinity

regime in the estuary.

5.15.15.2.2.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts on oyster leases consist simply of the sum

of the direct and indirect impacts for this alternative added to all other local and regional activities,

including construction of the GNOHSDRRS, and existing and in-progress elements of the LCA

Ecosystem Restoration program, including development of Freshwater Diversion sites.

Cumulative impacts on oyster leases resulting from implementation of Alternative 1 would incrementally

increase the ability of marsh and estuarine habitat essential to maintain salinity gradients and protect

against excessive salinities that could be detrimental to the long-term viability of oyster populations in

coastal Louisiana. This incremental effect combined with existing and planned restoration efforts in the

state (e.g., CWPPRA, the Community-based Restoration Program sponsored by the NMFS Restoration

Center, various state and local efforts, and others) would continue to aid fisheries habitat. Implementation

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of Alternative 1 would contribute to an overall long-term benefit to commercial fisheries, including oyster

harvesting, compared to the future with no action.

5.15.15.2.3 Alternative 2 – 10,000 cfs max Diversion

5.15.15.2.3.1 Direct

No measurable direct impacts to oyster leases would be anticipated to result from construction of

Alternative 2, primarily because the construction footprint is located in the upper portion of the project

area, where existing salinity conditions would be not favorable for oysters and where no leases currently

exist, as determined from examination of state databases.

5.15.15.2.3.2 Indirect

Indirect impacts to oyster leases around this diversion site if Alternative 2 is implemented could include

increased rate of mortality and decrease in productivity in oyster leases located closest to the diversion

site, during the period when the diversion is at full operational capacity and for up to 2 months after the

return to maintenance flow conditions. This could result in a loss of revenue for commercial oyster

harvesters.

The operational plan proposed and evaluated in this feasibility study and SEIS limits the period of full

flow to no more than 2 months (60 days) in the spring timeframe (MarchApril was used in the analysis).

It was formulated in part to avoid or minimize the potential for incidental adverse effects (e.g. mortality,

interference with reproduction) to oysters and other invertebrate or fishery species that require brackish or

saline environments. Hydraulic modeling of the project area indicated that the return to maintenance

flows for the remainder of the year (10 months) should maintain brackish and saline zones in the project

area, though at somewhat reduced average salinities. For these reasons, indirect adverse impacts to oyster

leases would not be anticipated to be significant. The number of leases impacted should be less than for

the 35,000 cfs alternative because the recovery time should be quicker.

Over the 50-year planning horizon, potential beneficial effects to oyster populations could result if

reduced salinities resulting from diversion operation were to increase the spatial extent of habitats

experiencing salinities in the optimal range for oyster production. Continued water quality and biological

monitoring of the project area before and after project construction should assist in refining the operation

plan as needed to meet project objectives for restoring marsh while maintaining a functioning salinity

regime in the estuary.

5.15.15.2.3.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts on oyster leases consist simply of the sum

of the direct and indirect impacts for this alternative added to all other local and regional activities,

including construction of the GNOHSDRRS, and existing and in-progress elements of the LCA

Ecosystem Restoration program, including development of Freshwater Diversion sites.

Cumulative impacts on oyster leases resulting from implementation of Alternative 2 would incrementally

increase the ability of marsh and estuarine habitat essential to maintain salinity gradients and protect

against excessive salinities that could be detrimental to the long-term viability of oyster populations in

coastal Louisiana. This incremental effect combined with existing and planned restoration efforts in the

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state (e.g., CWPPRA, the Community-based Restoration Program sponsored by the NMFS Restoration

Center, various state and local efforts, and others) would continue to aid fisheries habitat. Implementation

of Alternative 2 would contribute to an overall long-term benefit to commercial fisheries, including oyster

harvesting, compared to the future with no action.

5.15.15.2.4 Alternative 3 – 15,000 cfs max Diversion

5.15.15.2.4.1 Direct

No measurable direct impacts to oyster leases would be anticipated to result from construction of

Alternative 3, primarily because the construction footprint is located in the upper portion of the project

area, where existing salinity conditions would be not favorable for oysters and where no leases currently

exist, as determined from examination of state databases.

5.15.15.2.4.2 Indirect

Indirect impacts to oyster leases around this diversion site if Alternative 3 is implemented could include

increased rate of mortality and decrease in productivity in oyster leases located closest to the diversion

site, during the period when the diversion is at full operational capacity and for up to 2 months after the

return to maintenance flow conditions. This could result in a loss of revenue for commercial oyster

harvesters.

The operational plan proposed and evaluated in this feasibility study and SEIS limits the period of full

flow to no more than 2 months (60 days) in the spring timeframe (MarchApril was used in the analysis).

It was formulated in part to avoid or minimize the potential for incidental adverse effects (e.g. mortality,

interference with reproduction) to oysters and other invertebrate or fishery species that require brackish or

saline environments. Hydraulic modeling of the project area indicated that the return to maintenance

flows for the remainder of the year (10 months) should maintain brackish and saline zones in the project

area, though at somewhat reduced average salinities. For these reasons, indirect adverse impacts to oyster

leases would not be anticipated to be significant. The number of leases impacted should be less than for

the 35,000 cfs alternative because the recovery time should be quicker.

Over the 50-year planning horizon, potential beneficial effects to oyster populations could result if

reduced salinities resulting from diversion operation were to increase the spatial extent of habitats

experiencing salinities in the optimal range for oyster production. Continued water quality and biological

monitoring of the project area before and after project construction should assist in refining the operation

plan as needed to meet project objectives for restoring marsh while maintaining a functioning salinity

regime in the estuary.

5.15.15.2.4.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts on oyster leases consist simply of the sum

of the direct and indirect impacts for this alternative added to all other local and regional activities,

including construction of the GNOHSDRRS, and existing and in-progress elements of the LCA

Ecosystem Restoration program, including development of Freshwater Diversion sites.

Cumulative impacts on oyster leases resulting from implementation of Alternative 3 would incrementally

increase the ability of marsh and estuarine habitat essential to maintain salinity gradients and protect

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against excessive salinities that could be detrimental to the long-term viability of oyster populations in

coastal Louisiana. This incremental effect combined with existing and planned restoration efforts in the

state (e.g., CWPPRA, the Community-based Restoration Program sponsored by the NMFS Restoration

Center, various state and local efforts, and others) would continue to aid fisheries habitat. Implementation

of Alternative 3 would contribute to an overall long-term benefit to commercial fisheries, including oyster

harvesting, compared to the future with no action.

5.15.15.2.5 Alternative 4 – 35,000 cfs max Diversion (Recommended Plan)

5.15.15.2.5.1 Direct

No measurable direct impacts to oyster leases would be anticipated to result from construction of

Alternative 4, primarily because the construction footprint is located in the upper portion of the project

area, where existing salinity conditions would be not favorable for oysters and where no leases currently

exist, as determined from examination of state databases.

5.15.15.2.5.2 Indirect

Indirect impacts to oyster leases around this diversion site if Alternative 4 is implemented could include

increased rate of mortality and decrease in productivity in oyster leases located closest to the diversion

site, during the period when the diversion is at full operational capacity (Figure 5.2) and for up to 2

months after the return to maintenance flow conditions. This could result in a loss of revenue for

commercial oyster harvesters.

The operational plan proposed and evaluated in this feasibility study and SEIS limits the period of full

flow to no more than 2 months (60 days) in the spring timeframe (MarchApril was used in the analysis).

It was formulated in part to avoid or minimize the potential for incidental adverse effects (e.g. mortality,

interference with reproduction) to oysters and other invertebrate or fishery species that require brackish or

saline environments. Hydraulic modeling (Figure 5.3) of the project area indicated that the return to

maintenance flows for the remainder of the year (10 months) should maintain brackish and saline zones in

the project area, though at somewhat reduced average salinities. There will be approximately three oyster

leases in the study area and another five in the extended boundary that could be impacted by the project.

For these reasons, indirect adverse impacts to oyster leases would not be anticipated to be significant. If

this diversion were operated fully open outside the 2-month window that is described in the document,

then there could be significantly different impacts with some potentially being very negative.

Over the 50-year planning horizon, potential beneficial effects to oyster populations could result if

reduced salinities resulting from diversion operation were to increase the spatial extent of habitats

experiencing salinities in the optimal range for oyster production. Continued water quality and biological

monitoring of the project area before and after project construction should assist in refining the operation

plan as needed to meet project objectives for restoring marsh while maintaining a functioning salinity

regime in the estuary.

5.15.15.2.5.3 Cumulative

Unless otherwise indicated, cumulative socioeconomic impacts on oyster leases consist simply of the sum

of the direct and indirect impacts for this alternative added to all other local and regional activities,

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including construction of the GNOHSDRRS, and existing and in-progress elements of the LCA

Ecosystem Restoration program, including development of Freshwater Diversion sites.

Cumulative impacts on oyster leases resulting from implementation of Alternative 4 would incrementally

increase the ability of marsh and estuarine habitat essential to maintain salinity gradients and protect

against excessive salinities that could be detrimental to the long-term viability of oyster populations in

coastal Louisiana. This incremental effect combined with existing and planned restoration efforts in the

state (e.g., CWPPRA, the Community-based Restoration Program sponsored by the NMFS Restoration

Center, various state and local efforts, and others) would continue to aid fisheries habitat. Implementation

of Alternative 4 would contribute to an overall long-term benefit to commercial fisheries, including oyster

harvesting, compared to the future with no action.

5.16 HAZARDOUS, TOXIC, AND RADIOACTIVE WASTES

5.16.1 No Action Alternative (Future Without Project

Conditions)

The condition with the No Action Alternative regarding the potential for HTRW is dependent on sitespecific HTRW discovery. Based on the Phase I in the project action area, there is reason to believe that

the potential to encounter HTRW problems would be low.

5.16.2 Alternative 1 – 5,000 cfs max Diversion

5.16.2.1 Direct

Direct impacts would be slightly lower than Alternative 2.

5.16.2.2 Indirect

Indirect impacts would be slightly lower Alternative 2.

5.16.2.3 Cumulative

Cumulative impacts would be slightly lower Alternative 2.

5.16.3 Alternative 2 – 10,000 cfs max Diversion

5.16.3.1 Direct

Direct impacts would be slightly lower than Alternative 3.

5.16.3.2 Indirect

Indirect impacts would be slightly lower Alternative 3.

5.16.3.3 Cumulative

Cumulative impacts would be slightly lower Alternative 3.

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5.16.4 Alternative 3 – 15,000 cfs max Diversion

5.16.4.1 Direct

Direct impacts would be lower than Alternative 4.

5.16.4.2 Indirect

Indirect impacts would be lower than Alternative 4.

5.16.4.3 Cumulative

Cumulative impacts would be lower than Alternative 4.

5.16.5 Alternative 4 – 35,000 cfs max Diversion

(Recommended Plan)

5.16.5.1 Direct

Consistent with ER 1165-2-132, an HTRW investigation of the project area was conducted. Based upon

findings from this investigation, the potential for direct impacts to the project area from implementation

of Alternative 4 would be low and would likely continue to be low into the future.

5.16.5.2 Indirect

Consistent with ER 1165-2-132, an HTRW investigation of the project area was conducted. Based upon

findings from this investigation, the potential for direct impacts to the project area from implementation

of Alternative 4 would be low and would likely continue to be low into the future.

5.16.5.3 Cumulative

Consistent with ER 1165-2-132, an HTRW investigation of the project area was conducted. Based upon

findings from this investigation, the potential for direct impacts to the project area from implementation

of Alternative 4 would be low and would likely continue to be low into the future.

5.17 UNAVOIDABLE ADVERSE EFFECTS

Wetland impacts were avoided and minimized to the extent possible in the preliminary design of the

Recommended Plan. With avoidance and minimization of wetland impacts the Recommended Plan would

impact approximately 277 acres of intermediate marsh, 363 acres of shallow open water and 5 acres of

bottomland hardwoods for construction of the diversion and approximately 223 acres of intermediate

marsh and shallow open water would be impacted from excavation of the channel. The diversion channel

is the best way to divert water from the Mississippi River to American Bay, California Bay and Breton

Sound near Bay Gardens to the south. The creation of approximately 385 acres of intermediate marsh

habitat and creation of 32 acres of ridge habitat would mitigate for wetland impacts resulting from

construction activities. There would be no other unavoidable adverse impacts as a result of the

implementation of reasonable alternatives for this project.

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5.18 RELATIONSHIP OF SHORT-TERM USES AND LONG-TERM

PRODUCTIVITY

NEPA Section 102(2)(c)(iv) and 40 CFR 1502.16 requires that an EIS include a discussion of the

relationship between short-term uses of the environment and the maintenance and enhancement of longterm productivity. This section describes how the Proposed Action would affect the short-term use and

the long-term productivity of the environment.

In reference to the Proposed Action, short-term refers to the temporary phase of construction of the

proposed project, while long-term refers to the operational life of the proposed project and beyond.

Section 5 of this document evaluates the direct, indirect and cumulative effects that could result from the

Proposed Action.

Construction of the Proposed Action would result in short-term construction-related impacts within parts

of the project area and would include to some extent interference with local traffic, minor limited air

emissions, and increases in ambient noise levels, disturbance of fisheries and wildlife, increased storm

runoff, and disturbance of recreational and other public facilities. These impacts would be temporary and

would occur only during construction, and would not be expected to alter the long-term productivity of

the natural environment.

The Proposed Action would assist in the long-term productivity of the Breton Sound ecological

community by improving the water quantity, water quality, nutrients, and sediments. This in turn would

facilitate the growth and productivity of emergent intermediate marsh. The Proposed Action would also

result in enhancing the long-term productivity of the natural communities throughout the region. These

long-term beneficial effects of the Proposed Action would outweigh the impacts to the environment

resulting primarily from project construction.

5.19 IRREVERSIBLE AND IRRETRIEVABLE COMMITMENTS OF

RESOURCES

NEPA requires that environmental analysis include identification of any irreversible and irretrievable

commitments of resources which would be involved in the proposed action should it be implemented.

The proposed action would require the expenditure of human and fiscal resources and the potential

modification of natural resources. Construction would require the expenditure of materials that are

generally not retrievable. Considerable amounts of fossil fuels, labor, and construction materials such as

cement, aggregate, iron, and rock would be expended. Large amounts of labor and natural resources

would be necessary in the fabrication and preparation of construction materials. However, although these

materials are generally not retrievable, they are not in short supply and their use would not have an

adverse effect upon their continued availability. Other impacts that could have a longer effect can be

reduced through appropriate measures and best management practices (e.g., silt fencing to control

erosion). In addition, construction would require a large, one-time investment of Federal funds that are

not retrievable. The commitment of these resources is based on the concept that residents both within the

project area, as well as the region and nation, would benefit by improvements in the quality of the marsh

system. No irreversible or irretrievable commitment has occurred which would have the effect of

foreclosing the formulation or implementation of any reasonable and prudent alternative. No commitment

of resources has occurred that would prejudice the selection of any alternative before making a final

decision on this project.

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5.20 MITIGATION

Project plans and alternatives were developed in accordance with Corps planning guidance at ER 1105-2-

100, which directs that ecosystem restoration projects be designed to avoid the need for compensatory

fish and wildlife mitigation. Formulation of project alternatives, including diversion site location, design

of structures, and operating plans, was conducted in compliance with this guidance. Also in accordance

with Corps planning guidance, net ecosystem benefits expected to accrue if the proposed project is

implemented could not be used as wetland banks or mitigation credit by the non-Federal sponsor. The

possible addition of fish passages during the PED may be used to offset impacts to fishery resource and to

an endangered species.

5.21 ENVIRONMENTAL CONSEQUENCES SUMMARY

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EnvironmentalResources

Alternative Description

No Action Alternative 1 Alternative 2 Alternative 3 Alternative 4No Action/Without ProjectCondition.

Location 3  5,000 cfs diversion.Consisting of three 15-ft x 15-ft boxculverts, 32 acres of ridge andterrace creation, 139 acres of marshcreation utilizing dredged materialfrom an adjacent 153 acres of canalbeing reconfigured to conveyfreshwater.

Location 3  10,000 cfs diversionconsisting of three 15-ft x 15-ftbox culverts, 32 acres of ridgeand terrace creation, 176 acres ofmarsh creation using dredgedmaterial from adjacent 167 acresof canal reconfiguration toconvey freshwater.

Location 3  15,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 235acres of marsh creationutilizing dredged material froman adjacent 182 acres of canalreconfiguration to conveyfreshwater.

Location 3  35,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 385acres of marsh creationutilizing dredged material froman adjacent 223 acres of canalreconfiguration to conveyfreshwater.

1) Soils and WaterBottoms

Continued advanceddegradation of soils withinthe SA and increase inacreage of water bottoms.

Direct impact to 153 acres of marshand water bottom for construction ofdiversion, canal and ridge habitat.Beneficially creating 139 acresmarsh, nourish.

Direct impacts to 167 acres ofmarsh and water bottomCreation of 176 acres of marsh,32 acres of ridge/terrace.

Direct impacts to 182 acres ofmarsh and water bottomCreate 235 acres marsh; 32acres ridge/terrace.

Direct impact to 477 acres ofmarsh and water bottom forconstruction of diversion, canaland ridge habitat. Beneficiallycreating 385 acres marsh,nourish 35,000 acres and create31 acres of ridge/terracehabitat.

2) Hydrology: Flowsand Water Levels

Persistence of existingconditions including lack ofhydrologic connectivity tothe Mississippi River.Salinity intrusion wouldpersist and marsh habitatwould continue to declineand convert to open water.

No effect on Mississippi Riverflows anticipated.Increased hydrologic connectivitythat provide freshwater, nutrientsand sediment to marsh, improvingproductivity, accretion and improveconditions conducive to SAVdevelopment.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

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Alternative Description

No Action Alternative 1 Alternative 2 Alternative 3 Alternative 4No Action/Without ProjectCondition.

Location 3  5,000 cfs diversion.Consisting of three 15-ft x 15-ft boxculverts, 32 acres of ridge andterrace creation, 139 acres of marshcreation utilizing dredged materialfrom an adjacent 153 acres of canalbeing reconfigured to conveyfreshwater.

Location 3  10,000 cfs diversionconsisting of three 15-ft x 15-ftbox culverts, 32 acres of ridgeand terrace creation, 176 acres ofmarsh creation using dredgedmaterial from adjacent 167 acresof canal reconfiguration toconvey freshwater.

Location 3  15,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 235acres of marsh creationutilizing dredged material froman adjacent 182 acres of canalreconfiguration to conveyfreshwater.

Location 3  35,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 385acres of marsh creationutilizing dredged material froman adjacent 223 acres of canalreconfiguration to conveyfreshwater.

3) Hydrology:Sedimentation andErosion

Continued lack of sedimentinputs into SA.

Diversion of 5,000 cfs would deliver74,000 tons of sediment/yr. Increasesediment introduction could fill-inshallow water bodies adjacent toBayou Garelle. Increased deliveryof freshwater to the marsh woulddeliver nutrients and sediments thatwould enhance productivity andincrease SAV growth. Cumulativeeffects of multiple diversion couldalter sedimentation patterns ofMississippi River.

Diversion of 10,000 cfs woulddeliver 108,000 tons ofsediment/yr. Increase sedimentintroduction could fill-in shallowwater bodies adjacent to BayouGarelle. Increased delivery offreshwater to the marsh woulddeliver nutrients and sedimentsthat would enhance productivityand increase SAV growth.Cumulative effects of multiplediversion could altersedimentation patterns ofMississippi River.

Diversion of 15,000 cfs woulddeliver 143,000 tons ofsediment/yr. Increase sedimentintroduction could fill-inshallow water bodies adjacentto Bayou Garelle. Increaseddelivery of freshwater to themarsh would deliver nutrientsand sediments that wouldenhance productivity andincrease SAV growth.Cumulative effects of multiplediversion could altersedimentation patterns ofMississippi River.

Diversion of 35,000 cfs woulddeliver 279,000 tons ofsediment/yr. Increase sedimentintroduction could fill-inshallow water bodies adjacentto Bayou Garelle. Increaseddelivery of freshwater to themarsh would deliver nutrientsand sediments that wouldenhance productivity andincrease SAV growth.Cumulative effects of multiplediversion could altersedimentation patterns ofMississippi River.

4) Hydrology:Groundwater

Nearby human populationsand industry continue toincrease resulting inincreased groundwaterdemands and decrease ingroundwater resources.Continued decreasing marshhabitat no longer functions aseffectively as natural waterquality filtration system toaquifers.

Minor variations in groundwaterseepage due to head gradientscreated by the diversion. Restorationof marsh acts as natural waterquality filtration system to theaquifers.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

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EnvironmentalResources

Alternative Description

No Action Alternative 1 Alternative 2 Alternative 3 Alternative 4No Action/Without ProjectCondition.

Location 3  5,000 cfs diversion.Consisting of three 15-ft x 15-ft boxculverts, 32 acres of ridge andterrace creation, 139 acres of marshcreation utilizing dredged materialfrom an adjacent 153 acres of canalbeing reconfigured to conveyfreshwater.

Location 3  10,000 cfs diversionconsisting of three 15-ft x 15-ftbox culverts, 32 acres of ridgeand terrace creation, 176 acres ofmarsh creation using dredgedmaterial from adjacent 167 acresof canal reconfiguration toconvey freshwater.

Location 3  15,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 235acres of marsh creationutilizing dredged material froman adjacent 182 acres of canalreconfiguration to conveyfreshwater.

Location 3  35,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 385acres of marsh creationutilizing dredged material froman adjacent 223 acres of canalreconfiguration to conveyfreshwater.

5) Water Quality

Conversion of intermediatevegetation to open waterreduces natural water qualityfiltration. Water bodies instudy area meet designateduses.

Temporary negative impacts (e.g.,increased turbidity, decreaseddissolved oxygen) duringconstruction. Restoration of themarsh contributes to improvementsin water quality.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

6) Water Quality:Salinity

Taking no action wouldresult in continued salinityintrusion and loss of wetlandproductivity and conversionto open water.

Implementing this alternative wouldresult in direct benefits to theestuary in combating salinityintrusion and wetland loss.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

7) Air Quality Plaquemines Parish is in attainment. Temporary impacts to air quality associated with construction. Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.8) Noise

Limited increases in noisedue to limited transportation,development, and navigationin the study area.

Temporary increases in noise levelsduring construction activities. Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

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EnvironmentalResources

Alternative Description

No Action Alternative 1 Alternative 2 Alternative 3 Alternative 4No Action/Without ProjectCondition.

Location 3  5,000 cfs diversion.Consisting of three 15-ft x 15-ft boxculverts, 32 acres of ridge andterrace creation, 139 acres of marshcreation utilizing dredged materialfrom an adjacent 153 acres of canalbeing reconfigured to conveyfreshwater.

Location 3  10,000 cfs diversionconsisting of three 15-ft x 15-ftbox culverts, 32 acres of ridgeand terrace creation, 176 acres ofmarsh creation using dredgedmaterial from adjacent 167 acresof canal reconfiguration toconvey freshwater.

Location 3  15,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 235acres of marsh creationutilizing dredged material froman adjacent 182 acres of canalreconfiguration to conveyfreshwater.

Location 3  35,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 385acres of marsh creationutilizing dredged material froman adjacent 223 acres of canalreconfiguration to conveyfreshwater.

9) VegetationResources

Continued loss of wetlandhabitat, SAVs andbottomland hardwoodresources due to increasedsaltwater intrusion, floodduration, impoundment, andherbivory. Invasive specieswould continue to thrive.

Direct impacts to 477 acres marshand water bottom from construction.Benefits include restoring 32 acresof ridge habitat and 139 acres ofmarsh and nourishment of 10,603cumulative acres of existingvegetation. Diversion of freshwaterwould provide sediment andnutrients for improved marshproductivity, accretion) increase inSAV. Net average annualizedhabitat unit is 55.51.

Direct impacts to 477 acres marshand water bottom fromconstruction. Benefits includerestoring 32 acres of ridge habitatand 139 acres of marsh andnourishment of existingvegetation throughout projectarea. Diversion of freshwaterwould provide sediment andnutrients for improved marshproductivity, accretion) increasein SAV. Net average annualizedhabitat unit is 70.35.

Direct impacts to 631acresmarsh and water bottom and 5acres bottomland hardwoodsfrom construction. Benefitsinclude restoring 32 acres ofridge habitat and 235 acres ofmarsh and nourishment ofexisting vegetation throughoutproject area. Diversion offreshwater would providesediment and nutrients forimproved marsh productivity,accretion increase in SAV.Net average annualized habitatunit is 87.21.

Direct impacts to 863 acres ofmarsh and water bottom and 5acres of bottomland hardwoodsfor construction. Create 385acres of marsh, 32 acresridge/terrace habitat andnourish existing marshthroughout project area.Diversion of freshwater wouldprovide sediment and nutrientsfor improved marshproductivity, accretion,increased SAV. Net averageannualized habitat unit is139.94.

10) Wildlife

Continued decline in qualityof wildlife habitat adverselyimpacts wetland dependentwildlife populations.

Temporary impacts to wildlife dueto construction activities.Improvement and creation of habitatfor wetland dependent wildlife.Increases in populations of wildlifedependent on ridge habitat.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

11) Fisheries

Persistence of existingconditions including lowoxygen that could lead to fishkills and low speciesdiversity in the study area.Loss of wetland habitats usedby fish species for shelter,feeding, and life cyclerequirements.

Localized and temporary impacts tofisheries during construction.Overall increases in productivityand fisheries populations in thestudy area. Displacement of somefish species due to changes insalinity.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

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Alternative Description

No Action Alternative 1 Alternative 2 Alternative 3 Alternative 4No Action/Without ProjectCondition.

Location 3  5,000 cfs diversion.Consisting of three 15-ft x 15-ft boxculverts, 32 acres of ridge andterrace creation, 139 acres of marshcreation utilizing dredged materialfrom an adjacent 153 acres of canalbeing reconfigured to conveyfreshwater.

Location 3  10,000 cfs diversionconsisting of three 15-ft x 15-ftbox culverts, 32 acres of ridgeand terrace creation, 176 acres ofmarsh creation using dredgedmaterial from adjacent 167 acresof canal reconfiguration toconvey freshwater.

Location 3  15,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 235acres of marsh creationutilizing dredged material froman adjacent 182 acres of canalreconfiguration to conveyfreshwater.

Location 3  35,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 385acres of marsh creationutilizing dredged material froman adjacent 223 acres of canalreconfiguration to conveyfreshwater.

12) AquaticResources

A shift in plankton andbenthic populations tospecies assemblages thatprefer open water, marinehabitats as marsh converts toopen water and salinityintrusion continues.

Localized and temporary impacts toaquatic resources duringconstruction. Increases inpopulations due to increases inproductivity in the marsh.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

13) Essential FishHabitat (EFH)

Loss of more valuableproductive EFH due tocontinued subsidence,erosion and salinity intrusionas marsh converts to openwater. Potential decrease inhabitat for juvenile stages ofred drum and white shrimp.

Improved marsh productivityproviding a higher quality EFH.Increase in habitat for juvenilestages of red drum and whiteshrimp.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

14) Threatened andEndangered Species

Continued degradation,conversion, and eventual lossof important wetland habitatsused by threatened andendangered species.

Potential entrainment of pallidsturgeon in the intake structures.Potential creation of structuresbeneficial to pallid sturgeon.Potential to improve environmentfor gulf sturgeon. Ridge habitatwould be beneficial to bald eaglesand other raptors.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

15) CulturalResources

No impacts to culturalresources should occurwithin the study area as aresult of the No ActionAlternative.

No impacts to cultural resourcesshould occur within the study areaas a result of this alternative.Potential protection of culturalresources due to deposition ofsediment and restoration ofwetlands.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

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Alternative Description

No Action Alternative 1 Alternative 2 Alternative 3 Alternative 4No Action/Without ProjectCondition.

Location 3  5,000 cfs diversion.Consisting of three 15-ft x 15-ft boxculverts, 32 acres of ridge andterrace creation, 139 acres of marshcreation utilizing dredged materialfrom an adjacent 153 acres of canalbeing reconfigured to conveyfreshwater.

Location 3  10,000 cfs diversionconsisting of three 15-ft x 15-ftbox culverts, 32 acres of ridgeand terrace creation, 176 acres ofmarsh creation using dredgedmaterial from adjacent 167 acresof canal reconfiguration toconvey freshwater.

Location 3  15,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 235acres of marsh creationutilizing dredged material froman adjacent 182 acres of canalreconfiguration to conveyfreshwater.

Location 3  35,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 385acres of marsh creationutilizing dredged material froman adjacent 223 acres of canalreconfiguration to conveyfreshwater.

16) Aesthetics

Continued wetland loss andconversion of existingwetlands to open-waterhabitats resulting indecreased structuralcomplexity and habitatdiversity.

Improvement of the visual aestheticsof the study area through restorationmarsh and ridge habitat.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

17) Recreation

Continued degradation ofexisting wetlands woulddiminish the wildlife habitatof the area, which in turnwould adversely impact therecreational opportunities ofthe study area. Decreasingannual dollar revenues.

Localized and temporary impacts torecreation during construction.Overall, this alternative would serveto maintain and improve naturalhabitat, thereby maintaining andincreasing recreational opportunitieswithin the study area and leading toa substantial increase in recreationaleconomic value. $57,284 annualdollar revenues based on unit dayvalues.

Impacts similar to Alternative 1however recreational economicvalue would be $60,704 annualdollar revenues based on unit dayvalues.

Impacts similar to Alternative 1however recreational economicvalue would be $67,496 annualdollar revenues based on unitday values.

Impacts similar to Alternative 1however recreational economicvalue would be $40,517 annualdollar revenues based on unitday values.

19) Socioeconomics:Population andHousing

There would be no impactsto populations or housingunder the No ActionAlternative.

There would be no impacts topopulations or housing underAlternative 1.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

20) Socioeconomics:Employment,Business, andIndustrial Activity

Continued natural habitatdegradation would havelocalized impacts on fisheryand wildlife-relatedemployment and industries.

No direct, indirect or cumulativeimpacts anticipated fromimplementation of this alternative.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

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Alternative Description

No Action Alternative 1 Alternative 2 Alternative 3 Alternative 4No Action/Without ProjectCondition.

Location 3  5,000 cfs diversion.Consisting of three 15-ft x 15-ft boxculverts, 32 acres of ridge andterrace creation, 139 acres of marshcreation utilizing dredged materialfrom an adjacent 153 acres of canalbeing reconfigured to conveyfreshwater.

Location 3  10,000 cfs diversionconsisting of three 15-ft x 15-ftbox culverts, 32 acres of ridgeand terrace creation, 176 acres ofmarsh creation using dredgedmaterial from adjacent 167 acresof canal reconfiguration toconvey freshwater.

Location 3  15,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 235acres of marsh creationutilizing dredged material froman adjacent 182 acres of canalreconfiguration to conveyfreshwater.

Location 3  35,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 385acres of marsh creationutilizing dredged material froman adjacent 223 acres of canalreconfiguration to conveyfreshwater.

21) Socioeconomics:Availability of PublicFacilities andServices

No impacts to the availabilityof public facilities andservices should occur withinthe study area as a result ofthe No Action Alternative.

No impacts to the availability ofpublic facilities and services shouldoccur within the study area as aresult of the proposed action.

Impacts similar to Alternative 2. Impacts similar to Alternative 2. Impacts similar to Alternative 2.

22) Socioeconomics:Transportation

There would be no direct,indirect or cumulativeimpacts anticipated fromtaking no action.

Impacts on transportation resourceswould include temporary increase indemand of the transportationnetwork during construction.Overall, the proposed action wouldslow or reverse the trend of wetlanddegradation, thereby facilitatingtravel within the study area.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

23) Socioeconomics:Disruption ofDesirable Communityand Regional Growth(includingCommunityCohesion)

Continued natural habitatdegradation would havelocalized impacts on fisheryand wildlife-relatedemployment and industries,which could impedecommunity and regionalgrowth.

There would be no direct, indirect orcumulative impacts anticipated fromimplementation of this alternative.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

24) Socioeconomics:Tax Revenues andProperty Values

There would be no direct,indirect or cumulativeimpacts anticipated fromtaking no action.

There would be no direct, indirect orcumulative impacts anticipated fromimplementation of this alternative.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

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Alternative Description

No Action Alternative 1 Alternative 2 Alternative 3 Alternative 4No Action/Without ProjectCondition.

Location 3  5,000 cfs diversion.Consisting of three 15-ft x 15-ft boxculverts, 32 acres of ridge andterrace creation, 139 acres of marshcreation utilizing dredged materialfrom an adjacent 153 acres of canalbeing reconfigured to conveyfreshwater.

Location 3  10,000 cfs diversionconsisting of three 15-ft x 15-ftbox culverts, 32 acres of ridgeand terrace creation, 176 acres ofmarsh creation using dredgedmaterial from adjacent 167 acresof canal reconfiguration toconvey freshwater.

Location 3  15,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 235acres of marsh creationutilizing dredged material froman adjacent 182 acres of canalreconfiguration to conveyfreshwater.

Location 3  35,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 385acres of marsh creationutilizing dredged material froman adjacent 223 acres of canalreconfiguration to conveyfreshwater.

25) Socioeconomics:Infrastructure

Continued wetlanddegradation, includingcoastal land loss, wouldimpact infrastructure alongand leading to the coastline,affecting both relocationsand maintenance.

Potential impacts to watermanagement infrastructure fromconstruction of Diversion.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

26) Socioeconomics:Environmental Justice

There would be no direct,indirect or cumulativeimpacts anticipated fromtaking no action.

There would be no direct, indirect ofcumulative impacts anticipated fromimplementation of this alternative.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

27) Socioeconomics:Navigation

There would be no impactsto navigation as a result ofthe No Action Alternative.

Implementation of this alternativecould cause direct impacts to flowfrom Mississippi River, indirectimpacts resulting from potential toincrease shoaling.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

28) Socioeconomics:Agriculture

There would be no impactsto agriculture as a result ofthe No Action Alternative.

There would be no direct, indirect ofcumulative impacts anticipated fromimplementation of this alternative.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

29) Socioeconomics:Forestry

There would be no impactsto forestry from taking noaction.

Implementing this alternative woulddirectly impact 2.5 acres ofBottomland hardwoods. Benefitsinclude the restoration of 32 acres ofridge habitat that would beconducive to bottomland hardwoodregeneration.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

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Alternative Description

No Action Alternative 1 Alternative 2 Alternative 3 Alternative 4No Action/Without ProjectCondition.

Location 3  5,000 cfs diversion.Consisting of three 15-ft x 15-ft boxculverts, 32 acres of ridge andterrace creation, 139 acres of marshcreation utilizing dredged materialfrom an adjacent 153 acres of canalbeing reconfigured to conveyfreshwater.

Location 3  10,000 cfs diversionconsisting of three 15-ft x 15-ftbox culverts, 32 acres of ridgeand terrace creation, 176 acres ofmarsh creation using dredgedmaterial from adjacent 167 acresof canal reconfiguration toconvey freshwater.

Location 3  15,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 235acres of marsh creationutilizing dredged material froman adjacent 182 acres of canalreconfiguration to conveyfreshwater.

Location 3  35,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 385acres of marsh creationutilizing dredged material froman adjacent 223 acres of canalreconfiguration to conveyfreshwater.

30) Socioeconomics:Public Lands

Continued loss of public landand access resulting frommarsh degradation andconversion of marsh to openwater.

There would be no direct, indirect ofcumulative impacts anticipated fromimplementation of this alternative.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

31) Socioeconomics:Water Use andSupply

There would be no direct,indirect or cumulativeimpacts anticipated fromtaking no action.

Implementation of this alternativecould have direct and indirectimpacts to water supply pipeline.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

32) Socioeconomics:Oil, Gas, and Utilities

The effects of land loss anddegradation could lead toincreased costs formaintaining and repairingexisting oil, gas, and utilitiesin the study area.

Implementation of this alternativecould have direct and indirectimpacts to water supply pipeline.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

33) Socioeconomics:Flood Control andHurricane Protection

There would be no direct,indirect or cumulativeimpacts anticipated fromtaking no action.

Implementing this alternative couldhave direct and indirect impact onexisting levees in the area.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

34) Socioeconomics:Commercial Fisheries

Persistence of existingconditions including thecontinued conversion ofexisting wetlands to openwater habitats, restrictedwater circulation, anddecreased water qualitycould result in declines incommercial fisheries.

Overall increases in fisheriesproductivity due to increasednutrient inputs and wetland buildingprocesses. The potential short termdisplacement of some commercialfisheries and indirect impacts tolocal commercial seafoodprocessing facilities.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

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EnvironmentalResources

Alternative Description

No Action Alternative 1 Alternative 2 Alternative 3 Alternative 4No Action/Without ProjectCondition.

Location 3  5,000 cfs diversion.Consisting of three 15-ft x 15-ft boxculverts, 32 acres of ridge andterrace creation, 139 acres of marshcreation utilizing dredged materialfrom an adjacent 153 acres of canalbeing reconfigured to conveyfreshwater.

Location 3  10,000 cfs diversionconsisting of three 15-ft x 15-ftbox culverts, 32 acres of ridgeand terrace creation, 176 acres ofmarsh creation using dredgedmaterial from adjacent 167 acresof canal reconfiguration toconvey freshwater.

Location 3  15,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 235acres of marsh creationutilizing dredged material froman adjacent 182 acres of canalreconfiguration to conveyfreshwater.

Location 3  35,000 cfsdiversion consisting of ten 15-ftx 15-ft box culverts, 32 acres ofridge and terrace creation, 385acres of marsh creationutilizing dredged material froman adjacent 223 acres of canalreconfiguration to conveyfreshwater.

35) Socioeconomics:Oyster Leases

There would be no direct,indirect or cumulativeimpacts anticipated fromtaking no action.

Implementing this alternative couldresult in direct and indirect adverseimpacts to oyster leases andsignificant loss of revenue forparties holding those leases.

Impacts similar to Alternative 1. Impacts similar to Alternative 1. Impacts similar to Alternative 1.

36) HTRW

An HTRW Phase I in thestudy area was performed onthe study area, and identifieda low probability ofencountering contaminantsof concern.

Potential for impacts to the SA fromimplementation of Alternative 1 islow and would likely continue to below into the future.

Potential for impacts to the SAfrom implementation ofAlternative 1 is low and wouldlikely continue to be low into thefuture.

Potential for impacts to the SAfrom implementation ofAlternative 1 is low and wouldlikely continue to be low intothe future.

Potential for impacts to the SAfrom implementation ofAlternative 1 is low and wouldlikely continue to be low intothe future.

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6.0 PUBLIC INVOLVEMENT

6.1 NEPA SCOPING

Scoping is a critical component of the overall public involvement program to solicit input from affected

Federal, State, and local agencies, Indian Tribes, and interested stakeholders. The NEPA scoping process

is designed to provide an early and open means of determining the scope of issues (problems, needs, and

opportunities) to be identified and addressed in the Draft Environmental Impact Statement (DEIS).

Scoping is the process used to: a) identify the affected public and agency concerns; b) facilitate an

efficient DEIS preparation process; c) define the issues and alternatives that will be examined in detail in

the DEIS; and d) save time in the overall process by helping to ensure that relevant issues are adequately

addressed. Scoping is a process, not an event or a meeting; it continues throughout the EIS (draft and

final) process and may involve meetings, telephone conversations, and/or written comments.

A notice of intent (NOI) to prepare a draft EIS for the LCA MDWD Restoration Feasibility Study

(MDWD Study) was published in the Federal Register (volume 73, number 246) on December 22, 2008

A project kick-off meeting was held on December 12, 2008, and a public scoping meeting was organized

and hosted in accordance with NEPA on February 5, 2009. A scoping meeting announcement requesting

comments on the scope of the MDWD Study was mailed to Federal, State, and local agencies; and

interested groups and individuals on January 7, 2009. The media advisory announcing the scoping

meeting was provided to 350 media outlets. An advertisement for the public scoping meeting appeared in

the following publications:

 Baton Rouge Advocate, January 30, 2009

 St. Bernard Voice, January 30, 2009

 Times-Picayune, January 31, 2009

 Plaquemines Gazette, February 3, 2009

The public scoping meeting was held on:

Thursday, February 5, 2009

Phoenix High School

13073 Highway 15

Phoenix, LA 70040

The schedule for the scoping meeting was:

6:00  7:00 p.m. Open House

7:00  7:30 p.m. Presentations

7:30  8:00 p.m. Question and Answer Session

8:00  8:50 p.m. Open Forum for Comments

8:50  9:00 p.m. Wrap-up

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The open house session provided attendees with an opportunity to visit a series of poster stations staffed

by project team members and subject matter experts regarding the following topics: the LCA plan, the

NEPA process and milestones, an overview of the study and its goals and objectives, as well as maps of

the study area.

Following the open house, there was a brief presentation on the MDWD planned for the area and a

description of the NEPA process. During this segment, the LCA Environmental Manager and both the

USACE and CPRA Project Managers presented introductory remarks, including the agenda, purpose of

the meeting, public involvement under NEPA, a brief history leading to the study, the scope of the

analysis, and the intent to prepare a draft EIS for the MDWD study.

The question and answer portion focused on the study process and any other general questions presented

by attendees. Following this portion, the floor was opened for scoping comments. Individuals were

invited to present their verbal scoping comments to be recorded without interruption. The floor remained

open until no further scoping comments were given. During the wrap-up, attendees were reminded to pick

up self mailing comment cards, should they wish to submit additional comments at a later date, and to

drop off the meeting evaluation forms at the registration table.

A transcript of comments recorded at the scoping meeting was prepared by a court reporter. The scoping

comments were documented in a Scoping Report and describe the publics concerns about the restoration

effort and strategies for restoration efforts. See Appendix A for the Scoping Report. The Scoping Report

presents and summarizes the scoping comments expressed at the public scoping meeting, as well as all

other scoping comments received during the comment period beginning December 22, 2008, and ending

February 18, 2009. The Scoping Report indicates where in the draft EIS individual comments should be

addressed. This Scoping Report was provided to all scoping participants who provided their address, and

is published on the www.lca.gov Web site.

Approximately 26 people attended the MDWD scoping meeting. Names of those who signed in are listed

in the Scoping Report. A total of 16 multi-part comments were received during the comment period, of

which one was received via E-mail and two were copies of letters. Fourteen individuals expressed

comments at the scoping meeting. A total of three written comments (letter, email, Web site) were

received during the comment period.

A scoping comment may contain several specific statements directed at multiple areas of concern. Hence,

a single comment could potentially be generally addressed in multiple sections of the draft EIS. A total of

95 specific comments were expressed.

The comments were categorized according to their applicability to the EIS. EIS categories include:

Purpose and Need; Alternatives; Affected Environment; Environmental Consequences; and Consultation,

Coordination, and Compliance with Regulations. Although, an individual scoping comment may be

categorized under more than one EIS subject matter heading, no comment was assigned more than three

categories.

Purpose and Need

A majority of comments received in this category stressed the need for introducing more sediment into

the study area. In addition, several comments indicated that the storm surge was the root cause of the

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problems in this area: “The problem is the surge. If you can contain the sediment, you can protect the

surge from destroying what you built.” One respondent stressed a significant problem to be hyacinths in

the area: “A significant problem within the marshes is hyacinths. Hyacinths come into the open water,

which also has dugg grass. They cover the dugg grass and kill it. When the storm comes in, it kills the

hyacinths and then you are ultimately left with nothing but mud at the bottom.”

Alternatives

A number of respondent comments fell into this category. Converting the project to a sediment diversion

as opposed to a freshwater diversion was the most common suggestion. “It is extremely important that

this effort become a sediment diversion and the Corps reviews how sediments deposited initially by nature

create a marsh.” One commenter suggested adding new sections to the EIS to describe potential impacts

to the resources that could be impacted by the proposed project: “NOAA’s National Marine Fisheries

Service (NMFS) recommends the supplemental environmental impact statement (SEIS) include separate

sections titled, “Essential Fish Habitat” and “Marine Fishery Resources” that identify the EFH and

fisheries resources of the study area. These sections should describe the potential impacts, both positive

and negative, to those resources that could be caused by the proposed river diversion.” Other comments

included constructing a controlled diversion as an enhanced artificial crevasse for large discharge and

sediment pulses and designing a structure with a large operational range for river stages.

Affected Environment

Most comments relating to the natural resources in the project area focused on EFH and the water bodies

that provide nursery and foraging habitats: “Aquatic and tidally influenced wetland habitats in portions of

the study area are designated as essential fish habit for various federally managed species, including

white shrimp, brown shrimp, red drum, lane snapper, dog snapper, and gulf stone crab.”

Environmental Consequences

Several comments indicated the USACE consider the erosion effects from the water: Should consider

choking down areas to slow the water flow in and out so that the sediment can go up the bankline instead

of being washed out. Respondents also indicated the importance of sediment on the environment and this

project and stressed a need to keep it intact: Sediment is extremely important at the opening of the

diversion as is the distribution of that sediment so that it does not fall out 100 to 1,000 years from now at

the opening. In addition, concerns about impacts to oyster beds and other marine fisheries dominated the

comments received: NMFS believes adverse impacts to marine fishery productivity could be caused by

structure operations, especially during high flow periods. These impacts include: 1) displacement of less

freshwater tolerant, or cold water tolerant, marine fishery species from large areas of wetlands and water

bodies that serve as nursery and foraging areas; 2) destruction of productive oyster reefs that serve as

habitat and a food sources for some fishery species; 3) increased turbidity and associated decreases in

coverage of submerged aquatic vegetation in some areas; and 4) potential low dissolved oxygen levels in

areas water bodies caused by decomposition of large quantities of algae and/or phytoplankton resulting

from high nutrient levels in diverted river water.

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Consultation, Coordination, and Compliance with Regulations

The majority of comments received in this area concerned this project and the history of other projects:

Request the Corps analyze what was done on the Caernarvon diversion project as it destroyed the land in

20 years, but it should have naturally eroded in 100 years. Additional comments included the need for

the USACE to implement an evaluation program and to include additional sections within the report

regarding Essential Fish Habitat, Marine Fishery Resources, and Essential Fish Habitat sub-categories.

Table 6.1 displays the categorization of specific comments by EIS subject matter. The majority of the

comments addressed Alternatives followed by Affected Environment and Consultation, Coordination, and

Compliance with Regulations (tie); Purpose and Need; and Affected Environment.

Table 6.1: Categorization of Scoping Comments by Draft EIS Subject Matter

PN = Purpose and Need, ALT = Alternatives, AE = Affected Environment, EC = Environmental

Consequences, and CC = Consultation, Coordination, and Compliance with Regulations

Source of

Scoping Comment PN ALT AE EC CC Totals

Scoping Meeting 10 13 7 13 11 54

Scoping Comment Letters 3 16 5 3 8 35

Scoping Comments E-mails 2 0 2 2 0 6

Totals 15 29 14 18 19 95

NOTE: A single scoping comment may be categorized under multiple DPEIS subject matter headings.

6.2 OTHER PUBLIC COMMENTS

6.2.1 Federal and State Agencies

A project kick-off meeting was held on January 13, 2009, to present the study authority, purpose, goals

and objectives. Federal, State and local agencies from Louisiana participated in the discussions.

Representatives of Federal and State agencies were invited to be members of the Project Delivery Team

(PDT) and the Habitat Evaluation Team (HET). The PDT facilitates the interagency collaboration and

coordination necessary for study execution. Agency team members provide guidance and

recommendations throughout the planning process to assure the successful delivery of a quality product.

The HET is part of the PDT and is composed of resource agency representatives. The HET performs

planning and technical assessments consistent with their agency responsibilities and expertise. The HET

has been involved at all stages of the planning process, and has assisted with the development, evaluation,

and analysis of project alternatives. The HET has participated in the public information/involvement

program, exchanged study information, provided recommendations, and assisted in the resolution of any

interagency issues that may have surfaced in the study process. The HET was an integral part of the

Wetland Values Assessment process to determine the habitat value of the alternatives.

Federal and State agencies are also involved through the NEPA process, with some agencies serving as

official cooperating agencies and other agencies with official coordination and consultation roles.

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6.2.2 Land Owner, Non-Governmental Organization

(NGO), Parish and Other Involvement

The following meetings were held to provide opportunities for landowners, NGOs, the Parish and other

interested parties to see progress on the project and to solicit feedback from the attendees. Federal and

state agencies frequently attended as well.

April 28, 2009

On April 28, 2009, a presentation about the proposed project was given to the Maritime Navigation Safety

Association (MNSA) board members. Approximately 20 people attended the MNSA meeting. Attendees

included board members, Coastal Protection and Restoration Authority (CPRA) managers for the Myrtle

Grove Diversion project and representatives from the Environmental Defense Fund. The MDWD

presentation focused on the development and schedule of the project as well as the initial array of

measures. Since the project was still relatively early in the feasibility process at the time of the

presentation, few specifics were known. The project manager did specifically seek feedback from the

Board and committed to keeping them engaged with progress on the project. Numerous suggestions were

received regarding the importance of introducing sediments into the project area along with

recommendations for coordinating the MDWD with the Myrtle Grove Diversion project.

May 29, 2009

On May 29, 2009, site visits with eight local landowners, one land manager, and a representative from the

Plaqueminnes Parish Coastal Zone Management Department were conducted. The USACE was

represented by the project manager and two other members of the PDT. The proposed project was

discussed and land owner comments and concerns were solicited. Comments and concerns included the

need to maintain access for oil and gas lessees, control of invasive species and potential destruction of

private property by the project. Several landowners also recommended potential features including using

many smaller structures instead of one large structure and levee removal.

July 16, 2009

On July 16, 2009, a presentation was given about the proposed project to the LCA Science and

Technology board members. The meeting was assembled to present updates on numerous coastal

restoration efforts to the board and to solicit their input for review of the projects.

Approximately 50 people attended the LCA meeting. Attendees included board members, CPRA

managers for this and other LCA projects as well as representatives from numerous stakeholder,

consulting, and other interest groups. The MDWD presentation focused on the development of an initial

array of alternatives and the numerous measures being considered. Feedback was specifically sought from

the Board and a commitment to keeping them engaged with progress on the project was stressed. The

Board asked several questions about the project including how habitat benefits are realized and what

efforts are being considered to control invasive species. There was also discussion about the limits of the

WRDA authorization and how benefits from the project could easily reach beyond the current project

boundary.

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July 22, 2009

On July 22, 2009, the project manager gave a presentation about the proposed project to the Plaquemines

Parish Coastal Zone Advisory Committee. The monthly meeting was assembled to discuss several coastal

issues within the Parish and a specific request was made for an update on the MDWD project.

Approximately 15 people attended the meeting. Attendees included board members, the MDWD CPRA

manager, the H&H lead, the CZM director as well as other interested stakeholders and landowners. The

presentation focused on the development of an initial array of alternatives and the numerous measures

being considered. The project manager did specifically seek feedback from the Committee and pledged to

keep them engaged with progress on the project. The Committee asked several questions about the project

including what efforts are being considered to control invasive species and how the salinity isohalines

will be determined. A land manager spoke at length about the ill effects of the project and insisted that

some of the mistakes made on other diversion projects were not repeated. There was also discussion about

what the Committee could do to help advance the project and support it.

July 29, 2009

On July 29, 2009, the PM attended a modeling meeting hosted by the CPRA in conjunction with their

contractors in an effort to coordinate development of the MDWD with the proposed Myrtle Grove Water

Diversion (MG). Both MDWD and MG are looking at and evaluating large-scale freshwater diversions

(up to 100,000 cfs) at several locations on the Mississippi River, some of which could be directly across

from each other, east bank and west bank. Twenty five people were present at this meeting.

August 27, 2009

On August 27, 2009, an update was given about the proposed project features to the Delacroix

Corporation chairman and land manager. This update was a secondary discussion after meeting with

Delacroix and other land owners to acquire right-of-entry (ROE) for the MRGO Ecosystem Restoration

project.

Seven people attended the ROE meeting. Attendees included the Delacroix president, attorney and land

manager, two additional landowner reps, a COE real estate rep and an MRGO Eco rep. The MDWD

discussion focused on the development of a final array of alternatives that included the potential

elimination of three diversion sites as well as the different types and capacities for diversion structures.

The Delacroix president indicated his support for a large scale diversion structure that focused on

introducing as much sediment as possible into the project area and that he would be happy to see such a

project implemented as quickly as possible. He also indicated that other landowners in the area would

also likely be interested in maximizing sediment introduction. Graphics of potential diversion locations

with outfall management features were handed out for review. Discussion also ensued about the potential

for a nearby landowner to be especially interested in utilizing their property for placement of the

diversion.

September 14, 2009

On September 14, 2009, the project manager and the URS modeling contractor met with representatives

from the Delacroix Corporation and the Plaquemines Parish Government to discuss issues related to the

topography, hydrology, bathymetry, and general condition of the White Ditch project area. The purpose

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was to help inform the contractor of the unique project area characteristics in developing and refining the

hydraulic model to be used to estimate and simulate the effects of a diversion structure on the marsh.

Six people attended the meeting. Attendees included two Delacroix land managers and field staff, the

Plaquemines Parish Local Coastal Program Manager, Dr. Reed and Mr. MacInnes. The MDWD

discussion focused on the numerous elements that will affect the final calibration of the hydraulic model

including general marsh elevation, water depths across the project area including canals, bayous,

converted open water, ponds and lakes, general salinities, the flow of water across the marsh, areas that

have become water from marsh, etc. Considerable time was spent discussing the effects on water hyacinth

a diversion might have and the numerous problems the invasive species causes.

The land managers also discussed some of the potential options for a diversion structure with outfall

management features that could be constructed. Significant discussion focused on the operations of a

structure and how that is more important than what is built. They reiterated some of the problems

associated with the Caernarvon diversion and its flows, suggesting that a diversion should be run

minimally if even at all throughout the fall and winter. They supported the idea of a sediment diversion

but also suggested that the large amounts of water that would be diverted could have a severe negative

effect on the existing marsh if the structure is operated at high capacities for too long.

An outfall proposal was suggested that could help deliver beneficial sediments, nutrients, and freshwater

through an area experiencing high marsh-loss rates. The land managers felt this modification could have a

beneficial impact on the surrounding marshes.

November 13, 2009

On November 13, 2009, a focus group of 16 participants was interviewed about potential effects of a

freshwater diversion on recreation resources. Information discussed included the general effects of the

diversion, effects of culverts on fish access, effects of dredging, effects of marsh creation, and effects of

ridge restoration. A more-detailed discussion of these effects can be found in section 5.14.

March 26, 2010

A brief update on the current status of the project was presented to the Delacroix Corporation. Details of

the project were discussed, including the size, location, and potential operating scheme of the diversion.

Draft graphics were handed out and an update on the project schedule was provided.

March 31, 2010

A presentation was given to the Plaquemines Parish Coastal Zone Advisory Committee meeting held at

6:00 p.m. in Belle Chasse, Louisiana. Eleven members of the Committee and representatives from the

Parish Government and public were in attendance. The presentation focused on all project details

including the plan formulation, hydraulic modeling results, proposed operating scheme, size, location, and

potential effects. There was active participation at the meeting and numerous questions were asked about

project details.

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6.2.3 Public Comments on the Draft SEIS

Copies of this draft SEIS will be made available to all interested parties through mailings, advertisements,

media advisories, public meetings, and websites. All comments received during the 45-day public

comment period on the draft SEIS are documented and responded to in Appendix G. All commenters will

be sent a Notice of Availability of this Integrated Feasibility Study and SEIS after its completion.

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7.0 COORDINATION AND COMPLIANCE

This chapter documents the coordination and compliance efforts for this project regarding statutory

authorities including: environmental laws, regulations, executive orders, policies, rules, and guidance.

Consistency of the Recommended Plan and other Louisiana coastal restoration efforts is also addressed.

7.1 USACE PRINCIPLES AND GUIDELINES (P&G)

The guidance for conducting Civil Works planning studies (ER 1105-2-100) is based on the P&G adopted

by the Water Resources Council. The P&G are composed of two parts: The Economic and Environmental

Principles and Guidelines for Water and Related Land Implementation Studies and the Economic and

Environmental Guidelines for Water and Related Land Resources Implementation Studies. The P&G

require the systematic formulation of alternative plans to ensure all reasonable alternatives are evaluated.

The P&G also include guidance on the development and structure of the studies and reports for projects

requiring specific authorization.

Under the study guidance for projects requiring specific authorization, the feasibility study requirements

include documentation of the planning process and environmental compliance. The feasibility report is

required to document the planning process and all assumptions made during plan formulation along with

the rationale for decision making. The report should culminate in a recommended plan along with

documentation of how the plan relates to the NED, NER, or a combined NED/NER plan. If the project

deviates from those plans, the degree and reasons for the deviation must be documented. The feasibility

study is also required to document compliance with applicable environmental laws and regulations which

can be included as an EA or EIS included with the feasibility study or an integrated feasibility study

document with NEPA information.

Planning for this feasibility study has been conducted in accordance with the ER 1105-2-100 guidance.

This report is an integrated feasibility study and EIS. Policy reviews have been conducted to ensure

compliance with applicable USACE policies.

7.2 ENVIRONMENTAL COORDINATION AND COMPLIANCE

Following completion of the final integrated report, the Assistant Secretary of the Army for Civil Works

will issue a written Record of Decision (ROD) concerning the proposed action. The ROD will be issued

within a framework of laws, regulations, executive orders, policies, rules, and other guidance. These

authorities establish regulatory compliance standards for environmental resources pertaining directly to

USACE management of water resources development projects, or provide planning guidance for the

management of environmental resources. Relevant Federal statutory authorities and executive orders are

listed in Table 7.1. Relevant State of Louisiana statutory authorities are listed in Table 7.2. Full

compliance with statutory authorities will be accomplished upon review of the final integrated feasibility

report and Supplemental Environmental Impact Statement by appropriate agencies and the public and the

signing of a ROD, in compliance with the Fish and Wildlife Coordination Act (1958).

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Table 7.1: Relevant Federal Statutory Authorities and Executive Orders

(Note: This list is not complete or exhaustive)

Abandoned Shipwreck Act of 1987

American Indian Religious Freedom Act of 1978

Anadromous Fish Conservation Act of 1965

Archaeological Resources Protection Act of 1979

Archaeological and Historical Preservation Act of 1974

Bald Eagle Protection Act of 1940

Clean Air Act of 1970

Clean Water Act of 1977

Coastal Barrier Improvement Act of 1990

Coastal Barrier Resources Act of 1982

Coastal Wetlands Planning, Protection, and Restoration Act of 1990

Coastal Zone Management Act of 1972

Coastal Zone Protection Act of 1996

Comprehensive Environmental Response,

Compensation, and Liability Act of 1980

Consultation and Coordination with Indian Tribal Governments (EO

13175) of 2000

Deepwater Port Act of 1974

Emergency Planning and Community Right-to-Know

Act of 1986

Emergency Wetlands Restoration Act of 1986

Endangered Species Act of 1973

Environmental Quality Improvement Act of 1970

Estuaries and Clean Waters Act of 2000

Estuary Protection Act of 1968

Estuary Restoration Act of 2000

Exotic Organisms (EO 11987) of 1977

Farmland Protection Policy Act of 1981

Federal Actions to Address Environmental Justice in Minority

Populations & Low-Income Populations (EO 12898, 12948) of

1994, as amended

Federal Compliance with Pollution Control

Standards (EO 12088) of 1978

Federal Emergency Management (EO 12148) of 1979

Federal Water Pollution Control Act of 1972

Federal Water Project Recreation Act of 1965

Fish and Wildlife Conservation Act of 1980

Fish and Wildlife Coordination Act of 1958

Flood Control Act of 1944

Floodplain Management (EO 11988) of 1977

Food Security Act of 1985

Greening of the Government Through Leadership in Environmental

Management (EO 13148) of 2000

Historic Sites Act of 1935

Historical and Archaeological Data-Preservation

Act of 1974

Indian Sacred Sites (EO 13007) of 1996

Invasive Species (EO 13112) of 1999

Land & Water Conservation Fund Act of 1965

Magnuson-Stevens Fishery Conservation and Management Act of

1976, as amended

Marine Mammal Protection Act of 1972

Marine Protected Areas (EO 13158) of 2000

Marine Protection, Research, and Sanctuaries

Act of 1972

Migratory Bird Conservation Act of 1929

Migratory Bird Treaty Act of 1918

Migratory Bird Habitat Protection (EO 13186) of 2001

National Environmental Policy Act of 1969

National Historic Preservation Act of 1966

National Invasive Species Act of 1996

Native American Graves Protection and

Repatriation Act of 1990

Neotropical Migratory Bird Conservation Act of 2000

Noise Control Act of 1972

Nonindigenous Aquatic Nuisance Prevention and Control Act of

1996

North American Wetlands Conservation Act of 1989

Oil Pollution Act of 1990

Outer Continental Shelf Lands Act of 1953

Pollution Prevention Act of 1990

Prime or Unique Farmlands, 1980 CEQ

Memorandum

Protection and Enhancement of the Cultural Environment

(EO 11593) of 1971

Protection and Enhancement of Environmental Quality

(EO 11991) of 1977

Protection of Children from Environmental Health Risks and

Safety Issues (EO 13045) of 1997

Protection of Cultural Property (EO 12555) of 1986

Protection of Wetlands (EO 11990) of 1977

Reclamation Projects Authorization and Adjustments Act of 1992

Recreational Fisheries (EO 12962) of 1995

Resource Conservation and Recovery Act of 1976

Responsibilities of Federal Agencies to Protect Migratory Birds

(EO 13186) of 2001

Rivers and Harbors Acts of 1899, 1956

River and Harbor and Flood Control Act of 1970

Safe Drinking Water Act of 1974

Submerged Land Act of 1953

Sustainable Fisheries Act of 1996

Toxic Substances Control Act of 1976

Uniform Relocation Assistance and Real Property Acquisition

Policies Act of 1970 (Public Law 91-646)

Water Resources Development Acts of 1976, 1986, 1990, 1992,

and 2007

Water Resources Planning Act of 1965

Watershed Protection & Flood Prevention Act of 1954

Water Pollution Control Act Amendments of 1961

Wild and Scenic River Act of 1968

Wilderness Act of 1964

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Table 7.2: Relevant State Statutory Authorities

(Note: This list is not complete or exhaustive)

Air Control Act

Archeological Treasury Act of 1974

Louisiana Coastal Resources Program

Louisiana Natural and Scenic Rivers System Act

Louisiana Threatened and Endangered Species and Rare &

Unique Habitats

Protection of Cypress Trees

Water Control Act

7.2.1 U.S. Fish and Wildlife Coordination Act

The USACE has coordinated with the U.S. Fish and Wildlife Service, NMFS, and LDWF per the Fish

and Wildlife Coordination Act (16 U.S.C. 661-667e; the Act of March 10, 1934; Ch. 55; 48 Stat. 401), as

amended by the Act of June 24, 1936). A Final Coordination Act Report has been received and the

comments incorporated into the project plan. The Fish and Wildlife Coordination Act authorizes the

Secretaries of Agriculture and Commerce to provide assistance to and cooperate with Federal and State

agencies to protect, rear, stock, and increase the supply of game and fur-bearing animals, as well as to

study the effects of domestic sewage, trade wastes, and other polluting substances on wildlife.

The amendments enacted in 1946 require consultation with the Fish and Wildlife Service and the fish and

wildlife agencies of states where the waters of any stream or other body of water are proposed or

authorized, permitted or licensed to be impounded, diverted . . . or otherwise controlled or modified by

any agency under a Federal permit or license. Consultation is to be undertaken for the purpose of

preventing loss of and damage to wildlife resources.

Service Position and Recommendations

The Recommended Plan will benefit the fish and wildlife resources of the MDWD area by providing

fresh water, nutrients, and sediments to the study area thus facilitating sediment deposition, increasing

organic production, increasing biological productivity, and reducing marsh loss. Approximately 13,353

AAHUS and 35,146 net acres of fresh/intermediate, brackish, and saline marsh and ridge habitats would

benefit by the proposed project at the end of the project life. The Service supports implementation of a

35,000 cfs diversion at White Ditch provided the following fish and wildlife recommendations are

implemented concurrently with project implementation:

1. Future hydrological modeling should be conducted with longer-duration simulations (i.e., 13-

month simulations) to allow more complete projections of salinity change within the study area.

In addition, modeling of different operational plans should be conducted. We recommend the

following operational plans be evaluated; 1) MarchApril open operation with a 1,000 cfs

maintenance flow the remainder of the year, 2) March open operation with a 1,000 cfs

maintenance flow the remainder of the year, and 3) March 1 to March 14 open operation with a

1,000 cfs maintenance flow the remainder of the year.

USACE Response to Recommendation #1: Concur. Modeling of alternative operational plans will

be conducted during PED phase.

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2. To determine potential impacts to marine fishery resources in the study area, models which

simulate changes in nekton community composition based on changes in salinity should be

utilized. For example, the Ecopath/Ecosim (www.ecopath.org) models have been utilized to

simulate changes in the nekton community in the Caernarvon Diversion outfall area.

Hydrological modeling output could be used as input for the Ecopath/Ecosim models or other

similar models. The Corps will investigate the use of other aquatic models and will not limit

themselves to use of Ecopath/Ecosim.

USACE Response to Recommendation #2: Concur. Fishery modeling and habitat change modeling

will be performed during the PED phase. The cost and schedule for this will be incorporated into

the PMP being developed by the Corps for the PED Phase. At this time a SOW is being developed

as part of the Donaldsonville to the Gulf project to look a various models and develop a white paper

on the best use of them. The intent of these models is to support adaptive management of this

project.

3. The best available data and modeling tools should be utilized to select a more precise location

near Phoenix, Louisiana for the diversion structure to maximize the capture of suspended

sediment. The State of Louisiana Office of Coastal Protection and Restoration (OCPR) is funding

the development of a 3-dimensional river model which could greatly assist in determining the

optimal location for the diversion structure.

USACE Response to Recommendation #3: Concur. The precise location of the diversion structure

will be determined during the PED phase.

4. The Service has concerns regarding the Monitoring and Adaptive Management Plan and its

ability to ensure the goals and objectives are measured and achieved. The Corps should work with

the Service, NOAA's NMFS, and the LDWF during future planning efforts to address our

concerns.

USACE Response to Recommendation #4: Concur. The Corps appreciates the assistance of the

Service in continued development of the Monitoring and Adaptive Management Plan.

5. If a proposed project feature is changed significantly or is not implemented within one year of the

Endangered Species Act consultation letter, we recommend that the Corps reinitiate coordination

with each office to ensure that the proposed project would not adversely affect any Federally

listed threatened or endangered species or their habitat.

USACE Response to Recommendation #5: Concur. The Corps will reinitiate coordination with the

Service and NMFS if project features change significantly or if the project is not implemented

within a year after issuance of the Biological Opinion for this project.

6. Avoid adverse impacts to bald eagle nesting locations and wading bird colonies through careful

design of project features and timing of construction. A qualified biologist should inspect the

proposed work site for the presence of undocumented wading bird nesting colonies and bald

eagles during the nesting season (i.e., February 16 through October 31 for wading bird nesting

colonies, and October through mid-May for bald eagles).

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USACE Response to Recommendation #6: Concur. The proposed inspection will be scheduled

during the PED phase.

7. To minimize disturbance to colonies containing nesting wading birds (i.e., herons, egrets, nightherons, ibis, and roseate spoonbills), anhingas, and/or cormorants, all activity occurring within

1,000 feet of a rookery should be restricted to the non-nesting period (i.e., September 1 through

February 15, exact dates may vary within this window depending on species present). In addition,

we recommend that on-site contract personnel be informed of the need to identify colonial nesting

birds and their nests, and should avoid affecting them during the breeding season.

USACE Response to Recommendation #7: Concur. These restrictions will be included in project

plans and specifications.

8. If a bald eagle nest is discovered within or adjacent to the proposed project area, then an

evaluation must be performed to determine whether the project is likely to disturb nesting bald

eagles. That evaluation may be conducted on-line at: http://www.fws.gov/southeast/es/baldeagle.

Following completion of the evaluation, that website will provide a determination of whether

additional consultation is necessary and those results should be forwarded to this office.

USACE Response to Recommendation #8: Concur. Should a bald eagle nest be discovered in the

vicinity of construction activities, the Corps will conduct an on-line evaluation as directed and

utilize the results to determine whether additional consultation with the Service is necessary, and

will forward the results of the evaluation to the Lafayette Field Office.

9. Land clearing associated with project features should be conducted during the fall or winter to

minimize impacts to nesting migratory birds, when practicable.

USACE Response to Recommendation #9: Concur. Seasonal restrictions on land clearing will be

stipulated in project plans and specifications when practicable.

10. Further detailed planning of project features (e.g., Design Documentation Report, Engineering

Documentation Report, Plans and Specifications, or other similar documents) should be

coordinated with the Service and other State and Federal natural resource agencies, and shall be

provided an opportunity to review and submit recommendations on the all work addressed in

those reports.

USACE Response to Recommendation #10: Concur. Close coordination will be maintained with the

Service and NMFS during the PED phase.

11. A report documenting the status of implementation, maintenance and adaptive management

measures should be prepared every three years by the managing agency and provided to the

Corps, the Service, NMFS, U.S. Environmental Protection Agency (EPA), Louisiana Department

of Natural Resources (LDNR), OCPR, and LDWF. That report should also describe future

management activities, and identify any proposed changes to the existing management plan.

USACE Response to Recommendation #11: Concur. The Corps will coordinate with the listed

agencies to ensure preparation of the recommended report.

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12. The Service recommends a comprehensive examination of the river and all existing and proposed

diversions to coordinate their operation and ensure that their operation will maximize their

restoration capabilities. The ongoing Mississippi River Hydrodynamic and Delta Management

Study should be utilized to address this issue. The Service and other natural resource agencies

should be involved in this study.

USACE Response to Recommendation #12: Concur. The Corps will continue to coordinate with the

Service and other natural resource agencies to facilitate their involvement in the ongoing

Mississippi River Hydrodynamic and Delta Management Study.

13. The Service recommends establishment of a committee similar to the Caernarvon Interagency

Advisory Committee to review the operation and its results of the MDWD and when necessary,

provide recommendations regarding any future operational and maintenance changes. The

Service and other natural resource agencies should be on this committee.

USACE Response to Recommendation #13: Concur. The Corps will work with OCPR, the Service

and other natural resource agencies to establish an advisory committee for the White Ditch project.

7.2.2 Clean Water Act – Section 404(b)(1)

The USACE is responsible for administering regulations under Section 404(b)(1) of the CWA. Potential

project-related impacts subject to these regulations, such as the discharge of dredged material into

wetlands to create marsh and ridge habitat, have been evaluated in compliance with Section 404(b)(1) of

the CWA (Appendix D).

The evaluation of potential impacts to water quality indicated that, on the basis of the guidelines, the

proposed disposal sites for the discharge of dredged material comply with the requirement of these

guidelines, with the inclusion of appropriate and practicable methods to minimize adverse effects to the

aquatic ecosystem. The 404(b)(1) will be signed after the receipt of the 401 Water Quality Certificate

from the State of Louisiana.

7.2.3 Section 122 of the Rivers and Harbors Act

Section 122 of the Rivers and Harbors Act of 1970 (Public Law 91-611, 84 STAT. 1823) requires that

consideration be given to possible adverse economic, social and environmental effects. It also requires

that final decisions on the project be made in the best overall public interest, taking into consideration the

need for flood control, navigation and associated purposes; and the associated costs of eliminating or

minimizing the following adverse affects:

 Air, water and noise pollution;

 Destruction or disruption of man-made and natural resources, aesthetic values, community

cohesion, and availability of public facilities and services;

 Adverse employment effects;

 Tax and property value losses;

 Injurious displacement of people, businesses and farms;

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 Disruption of desirable community and regional growth.

Alternative 4 (Recommended Plan) would have no significant impacts on Section 122 identified

economic, social or environmental resources.

7.2.4 Coastal Zone Management Act of 1972

Section 307 of the Coastal Zone Management Act (CZM) of 1972 (16 U.S.C. 1456(c)(1)(A)) directs

Federal agencies proposing activities or development projects (including civil work activities), whether

within or outside the coastal zone, must assure that those activities or projects are consistent, to the

maximum extent practicable, with the approved state coastal zone management program. A Consistency

Determination is included with this report (Appendix E) and has been submitted to Louisiana Department

of Natural Department of Natural Resources (LDNR) for consistency review. Implementation of the

Recommended Plan is considered consistent, to the maximum extent practicable, with the approved

Louisiana state coastal management program. Concurance with our determination was received from

LDNR on July 29, 2010.

7.2.5 Endangered Species Act of 1973

Threatened and endangered species protected under the ESA, as amended, are present in the project area.

No critical habitats for those species would be directly affected, and no indirect adverse impacts are

expected to such habitats. As provided by the implementing regulations of the ESA, biological

assessments have been prepared and provided to the USFWS and NMFS to address the potential for the

proposed action to affect listed species. The biological assessments conclude that only one species, the

pallid sturgeon, may be adversely affected by the proposed action. The USACE will continue to consult

with the USFWS concerning the potential impacts to pallid sturgeon as necessary to comply with the

ESA. Formal consultation with USFWS began on July 16, 2010, and the Biological Opinion (BO) ending

it was signed on September 23, 2010. The BO can be found in Appendix A. All Reasonable and Prudent

Measures as well as Terms and Conditions provided in the USFWS biological opinion will be

implemented if feasible.

7.2.6 Magnuson-Stevens Fishery Conservation and

Management Act of 1996; and the MagnusonStevens Act Reauthorization of 2006 (Essential Fish

Habitat)

As directed by the Magnuson-Stevens Fishery Conservation and Management Act (Public Law 104-297),

the USACE has coordinated with NMFS and that agencys experts on various marine organisms as well

as EFH. The NMFS provided a letter dated February 10, 2009, to help guide the development of the

FS/SEIS for the proposed action (Appendix C). The NMFS identified white shrimp, brown shrimp, red

drum, lane snapper, dog snapper, and Gulf stone crab as species managed by the Gulf of Mexico Fishery

Management Council that have EFH in the proposed action area. They also listed estuarine emergent

wetlands, mud, sand and shell substrates, and estuarine and marine water column as primary categories of

EFH in the proposed action area. In accordance with NMFS recommendation by letter dated January 26,

2010, the USACE (MVN) commits to undertake and obtain output from ecological simulation modeling

and analysis of State fisheries data to assess the effects of this project individually as well as cumulatively

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with other projects involving the Breton estuary, as part of project Planning, Engineering, and Design

efforts, for use in developing an operation plan prior to implementation that will be applied under an

adaptive management plan. The analysis of potential impacts of the Recommended Plan on EFH is

described in Section 4.7 Essential Fish Habitat in the project vicinity.

7.2.7 Clean Air Act – Air Quality Determination

Compliance with the Clean Air Act (42 U.S.C.A. §§7401) has been fully coordinated with the Air Quality

Section of the LDEQ (see also Section 4.2.4 Air Quality). As required by Louisiana Administrative Code,

Title 33 (LAC 33:III.1405 B), an air quality applicability determination was made for the Recommended

Plan. This included consideration of the proposed action for the category of general conformity, in

accordance with the Louisiana General Conformity, State Implementation Plan (LDEQ, 1994). An air

quality determination has been calculated, based upon direct and indirect air emissions (Section 5.4).

Generally, since no other indirect Federal action, such as licensing or subsequent actions would likely be

required or related to the restoration construction actions, it is likely that indirect emissions, if they would

occur, would be negligible.

7.2.8 National Historic Preservation Act of 1966

In compliance with Section 106 of the NHPA, as amended, and 36 CFR 800, Federal agencies are

required to identify and consider potential effects that their undertakings might have on significant

historic properties, district, site, building, structure, or object that is included in or eligible for inclusion in

the National Register. Additionally, a Federal agency shall consult with any tribe that attaches religious

and cultural significance to such properties. Agencies shall afford the State Historic Preservation Office

(SHPO) and tribes a reasonable opportunity to comment before decisions are made. Accordingly,

coordination of the proposed action with the SHPO and tribes has been initiated.

7.2.9 Farmland Protection Policy Act (Prime and Unique

Farmlands)

The purpose of the Farmland Protection Policy Act (7 U.S.C. 658) is to minimize the extent to which

Federal programs contribute to the unnecessary and irreversible conversion of farmland to nonagricultural uses. There are no farmlands within the study area. Hence, there would be no unnecessary or

irreversible conversion of farmland to non-agricultural uses.

7.2.10 Executive Order 13186 – Migratory Bird Habitat

Protection

Executive Order 13186 proclaims the intent to support the conservation of previous migratory bird

conventions by integrating bird conservation principles, measures, and practices into agency activities and

by avoiding or minimizing, to the extent practicable, adverse impacts on migratory bird resources when

conducting agency actions. This Executive Order requires environmental analyses of Federal actions

required by NEPA or other established environmental review processes to evaluate the effects of actions

and agency plans on migratory birds, with emphasis on species of concern. In addition, each Federal

agency shall restore and enhance the habitat of migratory birds, as practicable. Implementation of the

Recommended Plan would result in a net increase in migratory bird habitat.

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7.2.11 Executive Order 12898 – Environmental Justice

Concern with EJ issues can be traced to Title VI, Section 601 of the Civil Rights Act of 1964 (Public Law

88-352):

No person in the United States shall, on the grounds of race, color, or national origin, be excluded

from participation in, be denied the benefits of, or be subjected to discrimination under any program or

activity receiving Federal financial assistance.

On February 11, 1994, President Clinton issued Executive Order 12898 regarding Federal actions to

address EJ issues in minority populations and low-income populations:

To the greatest extent practicable and permitted by law, and consistent with the principles set forth in

the report on the National Performance Review, each Federal agency shall make achieving

environmental justice part of its mission by identifying and addressing, as appropriate,

disproportionately high and adverse human health or environmental effects of its programs, policies,

and activities on minority populations and low-income populations in the United States and its

territories and possessions, the District of Columbia, the Commonwealth of Puerto Rico, and the

Commonwealth of the Mariana Islands.

Executive Order 12898 is designed to focus Federal attention on the environmental and human health

conditions in minority communities and low-income communities. The order is also intended to promote

non-discrimination in Federal programs substantially affecting human health and the environment, and to

provide minority communities and low income communities access to public information on, and an

opportunity for public participation in, matters relating to human health or environmental planning,

regulations, and enforcement. Potential EJ issues have been considered throughout the entire study

process, and will continue to be considered through project implementation. As part of the NEPA process,

a scoping input request was provided to the public and interested parties. The scoping comments did not

identify any potential EJ issues. The USACE is committed to ensuring that any potential EJ issues are

addressed as the study proceeds. The proposed ecosystem restoration measures would equally impact all

potential users in the area. There would be no potential EJ issues from implementing the Recommended

Plan.

7.2.12 Executive Order 13112 – Invasive Species

On February 3, 1999, President Clinton issued Executive Order 13112 to prevent the introduction of

invasive species and provide for their control and to minimize the economic, ecological, and human

health impacts that invasive species cause by establishing the National Invasive Species Council. The

Recommended Plan is consistent with Executive Order 13112 to the extent practicable and permitted by

law and subject to the availability of appropriations, and within Administration budgetary limits. The

Recommended Plan will use relevant programs and authorities to prevent the introduction of invasive

species and not authorize, fund, or carry out actions likely to cause or promote the introduction or spread

of invasive species in the United States or elsewhere, unless the USACE has determined and made public

its determination that the benefits of such actions clearly outweigh the potential harm caused by invasive

species, and that all feasible and prudent measures to minimize risk of harm will be taken in conjunction

with the actions.

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7.2.13 Executive Order 11990 – Floodplain Management

Executive Order 11988  Floodplain Management directs all Federal agencies to avoid, if possible,

development and other activities in the 100-year base floodplain. Where the base floodplain cannot be

avoided, special considerations and studies for new facilities and structures are needed.

Design and siting are to be based on scientific, engineering, and architectural studies; consideration of

human life, natural processes, and cultural resources; and the planned lifespan of the project. Federal

agencies are required to:

 Reduce the risk of flood loss

 Minimize the impact of floods on human safety, health, and welfare

 Restore and preserve the natural and beneficial values served by floodplains in carrying out

agency responsibility

The proposed action area is located in LCA Subprovince 1 in the Breton Sound hydrologic basin in

Plaquemines Parish, Louisiana; in Zone A (no base flood elevation determined) of the Special Flood

Hazard Areas inundated by 100-year flood (source: National Flood Insurance Program, Firm Flood

Insurance Rate Map, Plaquemines Parish, Louisiana, Unincorporated Areas, Community-Panel Number

220139 0165B and 220139 0170B, effective date September 30, 1993, Federal Emergency Management

Agency). Consistent with Executive Order 11988, implementing the Recommended Plan would have no

significant impacts on the risk of flood loss. Implementing the Recommended Plan would have no

significant flooding impacts on human safety, health and welfare. Implementing the Recommended Plan,

ecosystem restoration of over 98,000 acres of intermediate to brackish intertidal wetland habitats within

portions of the Breton Sound estuarine area, would contribute to restoring and preserving the natural and

beneficial values served by floodplains.

7.2.14 Executive Order 11988 – Protection of Wetlands

President Jimmy Carter issued Executive Order 11990: Protection of Wetlands on May 24, 1977 (42 FR

26961, 3 CFR, 1977 Comp., p. 121) in order to avoid, to the extent possible, the long and short term

adverse impacts associated with the destruction or modification of wetlands. Executive Order 11990

directs that each Federal agency shall take action to minimize the destruction, loss or degradation of

wetlands, and to preserve and enhance the natural and beneficial values of wetlands. Consistent with

Executive Order 11990, the following factors have been considered as part of the alternative plan

formulation process in developing the Recommended Plan for ecosystem restoration and avoiding

potential effects on the survival and quality of wetlands:

a) public health, safety, and welfare, including water supply, quality, recharge and discharge;

pollution; flood and storm hazards; and sediment and erosion;

b) maintenance of natural systems, including conservation and long term productivity of existing

flora and fauna, species and habitat diversity and stability, hydrologic utility, fish, wildlife,

timber, and food and fiber resources; and

c) other uses of wetlands in the public interest, including recreational, scientific, and cultural uses.

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7.2.15 Uniform Relocation Assistance and Real Property

Acquisition Policies Act of 1970 (Public Law 91-646)

All real estate interests acquired for construction of the Recommended Plan will be in accordance with the

provisions of the Uniform Relocation Assistance and Real Property Acquisition Policies Act of 1970

(Uniform Act), as amended in 42 USC 4601-4655, and the Uniform Regulations contained in 49 C.F.R.

Part 24. The Uniform Act sets forth procedures for the acquisition of private property for public use and

specifically requires that the acquiring agency appraise the real property interests it wishes to acquire and

provide the owner a written summary of the basis for the amount established as just compensation.

7.2.16 Louisiana State Rare, Threatened, and Endangered

Species, and Natural Communities Coordination

The USACE reviewed the database maintained by the Louisiana National Heritage Program (LNHP) that

provides the most recent listing and locations for rare, threatened and endangered species of plants and

animals and natural communities within the State of Louisiana. The proposed action would not adversely

impact any rare, threatened or endangered species, or unique natural communities. The proposed action

would increase the extent of fresh marsh within portions of the study area, which is identified as a rare

and imperiled natural community for certain regions of the state (see also Section 5.6 Vegetation

Resources).

7.2.17 Clean Water Act – Section 401 Water Quality

Under provisions of the CWA (33 U.S.C. § 1251), any project that involved placing dredged or fill

material in waters of the United States or wetlands, or mechanized clearing of wetlands would require a

water quality certification from the LDEQ, Office of Environmental Services. A final Supplemental

Environmental Impact Statement addressing impacts of all activities associated with the proposed White

Ditch Diversion Project has been prepared. The document includes an assessment of impacts of

excavation, dredging, and disposal operations. Application for certification has been submitted by the

U.S. Army Engineer District, New Orleans, to the LDEQ, Office of Environmental Services, in

accordance with statutory authority contained in LRS: 30:2074 A(3) and provisions of Section 401 of the

CWA (P.L. 92-500, as amended).

Under provisions of the CWA (33 U.S.C. § 1251), any project that involves placing dredged or fill

material in waters of the United States or wetlands, or mechanized clearing of wetlands would require a

water quality certification from the LDEQ, Office of Environmental Services. A public notice for the

proposed action has been issued. Along with a copy of this final FS/EIS, an application for water quality

certification has been provided to the LDEQ, stating that the proposed placement of fill material into

waters of the state will not violate established water quality standards. Issuance of an LDEQ state Water

Quality Certification is anticipated on October 4, 2010, prior to the start of the 30-day review period. The

401 Water Quality Certificate will be available for review and placed on www.LCA.Gov when it is

issued.

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8.0 CONCLUSIONS AND DETERMINATIONS

8.1 AREAS OF CONTROVERSY AND UNRESOLVED ISSUES

During the scoping meeting and throughout the alternative identification and evaluation a number of

issues have been raised regarding diversions in general and those under consideration in the study area.

Every effort has been made to address these concerns and clearly identify the impacts, both beneficial and

detrimental of the alternatives considered. Through public review of the document most of these issues

clarified and resolved. However, it is also likely that if construction and operation of the Recommended

Plan were to occur, these issues would continue to be raised. They are summarized as follows:

 Joint operation of the proposed White Ditch Diversion with the existing Caernarvon Diversion

would be key to maintaining the condition of the overall Breton Sound ecosystem. These two

projects should not be operated independently of one another. Modeling results and monitoring

data suggests that Caernarvon has the ability to substantially freshen the Breton Sound even

without freshwater inputs from another source. In order for Breton Sound salinities to rebound

after the MarchApril pulse from the White Ditch Diversion, flow from Caernarvon would have

to be closely controlled. This will mean a change to the current operational plan. It will be crucial

that future modeling during PED for White Ditch and during Feasibility for the LCA

Modification to Caernarvon investigate joint operation. The LCA 4 Modification to Caernarvon

will consider and account for the proposed Medium Diversion at White Ditch project during its

analysis. Additionally the existing and proposed operational plans for both White Ditch and

Caernarvon are subject to refinement based on any newly acquired data. If significant changes are

required, these would be properly disclosed to the public through the NEPA process.

 Potential negative impacts to oysters from over-freshening of the basin. An evaluation of the

impacts to the salinity regimes in the study area was conducted and the areas most important to

commercial oyster harvesting could experience significant changes as a result of the project,

especially if an unfavorable operational regime is implemented. During the PED phase, detailed

and extensive aquatic modeling using the fisheries modeling software will be used to thoroughly

evaluate the potential impacts to fisheries resources, including commercially important species

such as oysters. These results could assist in further refinement of the proposed operational

regime.

 Converting the estuary to fresh/intermediate marsh. Fresh and intermediate marsh types are an

important habitat type in coastal areas and specifically the study area. The loss of these areas has

diminished the ecological integrity of the study area. The restoration of fresh and intermediate

marsh types will not exceed historic trends and is not expected to displace significant areas of

brackish or saline marsh. Additionally the Recommended Plan has the potential to create new

areas of brackish and saline marsh through restoration of the functional processes that create and

sustain them.

 Creating 'flotant' marsh that is not anchored and provides no surge protection. The short duration

of the pulse (MarchApril) operating regime has the potential to saturate existing marsh.

However, due to the relatively short pulsing season, significant habitat switching is not expected

to occur.

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 Direct sediment delivery with dredging from the river. The cost of this approach would be

excessive. While building marsh directly would have an immediate benefit, it would not restore

the processes needed to sustain marsh within the study area.

 Impacts to pallid sturgeon. At this time, surveys are being conducted to determine whether pallid

sturgeon are present and whether the Recommended Plan will impact the species. Preliminary

indications are that the species is not present; however, the USFWS has not yet made a formal

determination. That information will be available before a public review draft of the report is

completed.

 Creating access and/or land use problems for private landowners. The Recommended Plan will

have immediate impacts in the area being considered for the location of the structure. Access

during construction may be limited but this would be temporary.

 Did we pick the best spot on the river to capture sediment? Based on the available information the

supply of sediment at the Phoenix Location would be adequate to meet the goals and objectives of

the project and operational requirements of the structure. The information used to predict project

benefits in the ERDC-Sand2 Model came from data obtained from the Belle Chasse station,

which represented the longest continuous dataset from a nearby location. When comparing the

ERDC-Sand2 Model inputs to data that have been collected within the project area itself, it is

seen that the programs estimates are conservative. Data collected by the USGS in the outfall canal

of the existing White Ditch Siphon suggests that more sediment is available to enter into the

project area than represented by the Belle Chasse Data. Using the Belle Chasse Data, it is

expected that the Recommended Plan will deliver approximately 16,600 tons of sediment per day

into the project area during the MarchApril Pulse. Using the USGS sediment loads and the same

pulse operation, approximately 17,900 tons of sediment per day could enter the project area. This

results in a potential 8% increase in sediment loads from what are currently being projected.

Current research being done by the University of Texas in conjunction with the State of Louisiana

also suggests that there will be further increased sediment concentrations specifically at the

Phoenix site. The Phoenix location of the Recommended Plan was selected because there is a

back-current in flows on the Mississippi River. This will enhance the amount of sediment

available in the area of the diversion as the back-current will continually pull sediments into the

diversion.

Additional analysis will be conducted during PED to determine the best orientation and

placement of the structure within close proximity of its presently proposed location. The project

would not move from the Phoenix Location.

 Relative Sea-Level Rise (RSLR). Extensive consideration of RSLR occurred during formulation.

Further, the impacts of the moderate and high sea-level rise scenarios on the Recommended Plan

were evaluated but it should be noted that no evaluated alternative is able to entirely offset the

high rate of sea-level rise.

 Induced shoaling effects and other effects to the navigation/shipping industry. No impacts are

expected to the day-to-day activities of the navigation/shipping industry. A qualitative analysis of

induced shoaling effects is included in Appendix N. Further analysis is recommended during

design to accurately assess and minimize, through the diversion structure design, potential

impacts.

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 The Recommended Plan for this project exceeds the cost authorization presented in the 2004

LCA Report. The District Commander recommends seeking additional authorization in order to

construct the Recommended/NER plan; however, the need to request additional authorization has

the potential to impact the project construction schedule.

 Fishery modeling and habitat change modeling will be performed during the PED phase. The cost

and schedule for this will be incorporated into the PMP being developed by the USACE for the

PED Phase. At this time, a SOW is being developed as part of the Donaldsonville to the Gulf

project to look at various models and develop a white paper on the best use of them. The intent of

these models is to support adaptive management of this project.

 The impacts of the Deepwater Horizon oil spill on coastal Louisiana are uncertain at this time

(August 2010). The impacts of the oil spill as well as the various emergency actions taken to

address oil spill impacts (e.g., use of oil dispersants, creation of sand berms, use of Hesco baskets,

rip-rap, sheet piling and other actions) could potentially impact USACE water resources projects

and studies within the Louisiana coastal area, including the MDWD project. Potential impacts

could include factors such as changes to existing, future-without, and future-with-project

conditions, as well as increased project costs and implementation delays. The USACE will

continue to monitor and closely coordinate with other Federal and state resource agencies and

local sponsors in determining how to best address any potential problems associated with the oil

spill that may adversely impact project implementation. Supplemental planning and

environmental documentation may be required as information becomes available. If at any time

petroleum or crude oil is discovered on project lands, all efforts will be taken to seek clean up by

the responsible parties, pursuant to the Oil Pollution Act of 1990 (33 U.S.C. 2701 et seq.).

Ongoing documentation of the impacts associated with the Deepwater Horizon Oil spill can be

found in several governmental sources. The USFWS Situation Report for August 2, 2010

(http://www.fws.gov/home/dhoilspill/pdfs/MondayAugust22010.pdf) indicates the following

environmental-related Deepwater Horizon oil spill information: 563 personnel are actively

engaged in the response, working to protect wildlife and their habitats, including 36 national

wildlife refuges. They are also assessing the damage from the oil spill in preparation for the work

that will be needed to restore the Gulf of Mexico. Some 1,643 visibly oiled birds have been

collected alive by the U.S. Fish and Wildlife Service, the states and our partners in response to the

Deepwater Horizon oil spill. Of those, 594 birds have been rehabilitated and released. Another

1,451 visibly oiled birds have been collected dead. Aerial operations over Louisiana observed an

oil sheen covering 300 acres in the northeastern portion of Barataria Bay. A heavily oiled

coastline covering about one-half mile was found at Bayou Chalond and heavy oil and tar balls

were observed on landfall east of Point-Au-Fer and along Timbalier Island. Beached bird surveys

were conducted in Texas, Louisiana, Mississippi, Alabama and Florida. Aerial missions are

scheduled for Southwest Pass, Chandeleur Islands, Biloxi Marsh, Barataria Bay, Terrebonne,

Marsh Islands, Atchafalaya Delta, Point-Au-Fer and Timbalier Bay.

 Overall number of personnel responding: approximately 30,100

 Total vessels responding: more than 4,500

 Total boom deployed: more than 2,155 miles

 Boom available: more than 856 miles

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 Oily water recovered: more than 34.7 million gallons

 Estimated 11.14 million gallons of oil burned

 Estimated total of more than 1.84 million gallons of dispersant used including:

+ Estimated more than 1.07 million gallons surface dispersant used

+ Estimated more than 771,000 gallons of sub-sea dispersant used

 Estimated approximately 632 miles of Gulf Coast shoreline is currently oiled-approximately

365 miles in Louisiana, 111 miles in Mississippi, 68 miles in Alabama, and 88 miles in

Florida.

The USACE, New Orleans District Regulatory Branch has considered and responded to

approximately 55 emergency permits related to the Deepwater Horizon oil spill. In addition, the

State of Louisiana is permitted to dredge and fill to construct a six sand berm reaches along the

shoreline of the Chandeleur Islands/Breton National Wildlife Refuge westward to Baptiste

Collette Bayou and along the seaward shoreline of Timbalier Island eastward to Sandy Pont.

Material to construct the berms would be dredged from Ship Shoal, South Pelto, the Mississippi

River Offshore Disposal Site, Pass a Loutre, St. Bernard Shoal and Hewes Point. Emergency

permits have the following clause that provides for removing, relocating or altering permitted

structures if necessary and upon due notice from the Corps. The clause would pertain to future

actions by the United States, such as proposed Louisiana Coastal Area restoration projects:

The permittee understands and agrees that, if future operations by the United

States require the removal, relocation, or other alteration, of the structure or

work herein authorized, or if, in the opinion of the Secretary of the Army or his

authorized representative, said structure or work shall cause unreasonable

obstruction to the free navigation of the navigable waters, the permittee shall be

required upon due notice from the Corps of Engineers, to remove, relocate, or

alter the structural work or obstructions caused thereby, without expense to the

United States. No claim shall be made against the United States on account of

any such removal or alteration.

As is evident from the numerous ongoing actions, the dynamic nature of the impacts associated

with the Deepwater Horizon oil spill will likely require additional consideration in the near future

for USACE Civil Works projects.

8.2 CONCLUSIONS

The Recommended Plan would create and nourish approximately 20,315 acres of fresh, intermediate,

brackish and saline wetlands. This alternative involves construction of a structure capable of diverting up

to 35,000 cfs consisting of ten 15-ft x 15-ft box culverts. Additionally, the project will have 31 acres of

ridge and terrace creation, 385 acres of marsh creation utilizing dredged material from an adjacent 223

acres of canal being reconfigured to convey freshwater, nutrient and sediments. Restoration of freshwater,

nutrient and sediment inputs to the project area will result in the creation and nourishment of a variety of

marsh types within the study area. Notched weirs would be installed in outflow canals to restrict flow into

the River aux Chenes and retain diverted water in the project area. The project will be operated in a

pulsed manner diverting up to 35,000 cfs during March and April and up to 1,000 cfs the rest of the year.

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The Recommended Plan is the plan that best meets the Louisiana Coastal Area goals and objectives as

well as those identified for the study area in partnership with the State of Louisiana. The Recommended

Plan is also the plan that best meets the P&Gs four criteria of completeness, effectiveness, efficiency,

and acceptability, as well as the Environmental Operating Principles of environmental sustainability,

interdependence, balance and synergy, accountability, knowledge, respect, and assessing and mitigating

cumulative impacts.

8.3 RECOMMENDATIONS

The District Commander has considered all the significant aspects of this study including the

environmental, social, and economic effects, the engineering feasibility, and the comments received from

other resource agencies, the Non-Federal Sponsors, and the public and has determined that the

Recommended Plan presented in this report is in the overall public interest and a justified expenditure of

Federal funds. As a comprehensive approach to restore and maintain ecological integrity, including

habitats, communities, and populations of native species, and the processes that sustain them by reversing

the trend of degradation and deterioration to the area between the Mississippi River and the River aux

Chenes ridges, the District Commander recommends the construction of a diversion structure capable of

diverting up to 35,000 cfs consisting of ten 15-x-15-ft box culverts. Additionally, 31 acres of ridge and

terrace creation, 385 acres of marsh creation utilizing dredged material from an adjacent 223 acres of

canal being reconfigured to convey freshwater, nutrient and sediments. Notched weirs would be installed

in outflow canals to restrict flow into the River aux Chenes and retain diverted water in the project area.

The project will be operated in a pulsed manner diverting up to 35,000 cfs during March and April and up

to 1,000 cfs the rest of the year.

The fully funded cost for the project is $387,620,000, inclusive of associated investigation,

environmental, engineering and design, construction, supervision and administration, and contingency

costs. The operations and maintenance of this project may be assumed by the State of Louisiana as the

non-Federal sponsor. The project is funded 65% by the Federal Government and 35% by the non-Federal

sponsor, and subject to the implementation requirements and responsibilities specified in Section 3.9 of

this report.

The recommendation contained herein reflects the information available at this time, March 2010 price

levels, and current Departmental policies governing the formulation of individual projects. They do not

reflect program and budgeting priorities inherent in the formulation of a national civil works construction

program, nor the perspective of higher levels of review within the Executive Branch. Consequently, the

recommendation may be modified before they are transmitted to the Congress as proposals for

authorization and/or implementation funding.

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9.0 DISTRIBUTION LIST AND OTHER

9.1 DISTRIBUTION LIST

The DEIS was distributed to Federal, state, parish, and local agencies; Tribes; businesses; libraries;

museums; universities; environmental organizations, groups and individuals; and scoping participants.

The complete distribution list is available upon request from the U.S. Army Corps of Engineers at the

following address:

U.S. Army Corps of Engineers

New Orleans District

P.O. Box 60267

New Orleans, Louisiana 70160-0267

This Integrated Feasibility Report and SEIS will be distributed to Federal, state, parish, and local

agencies; tribes; businesses; libraries; museums; universities; environmental organizations, groups and

individuals; and scoping participants. The complete distribution list will be available upon request from

the USACE at the following address.

U.S. Army Corps of Engineers

New Orleans District

P.O. Box 60267

New Orleans, Louisiana 70160-0267

9.2 LIST OF PREPARERS

Many individuals were involved with the completion of this document. The following table lists those

people who assisted in writing this Integrated Feasibility Study and EIS.

Table 9.1: List of Preparers

Name

Job Description/Experience/

Education/Registration Subject Matter

Baker, Ariele Coastal Resource Scientist (CPRA)/1 year/M.S.

Environmental Science, LSU

CPRA Study Manager

Boyce, Mayely Assistant District Counsel (MVN)/

3 years/J.D./M.E.M., Duke University

Legal Review

Brown, Michael Biologist/7 years/B.A. Biology

Southeastern Louisiana University

Vegetation Resources

Carmack, Charlene Community Planner (MVR)/25 years/

M.A. Geography, University of Iowa

Functional Team

Leader for EIS

Preparation

Clouse, Paul GIS Coordinator (MVS)/18 years/B.A

Computer Science, Huntingdon College/

Certified GIS Professional

Data Acquisition &

Support

Cook, Kenneth Fishery Biologist (MVS)/7 years/M.S. Zoology,

SIU-Carbondale

Plankton

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Name

Job Description/Experience/

Education/Registration Subject Matter

Dayan, Nathan Fisheries Biologist (MVN)/14 years/M.S

Marine Biology, University of Charleston

Environmental

Oversight

Demarcay, Gary Archaeologist/23 years/M.A.

Anthropology, Texas A&M University

Cultural Resources

Eagan, Timothy Civil Engineer Technician (MVS)/

3 years/B.A. Information Technology,

Lindenwood University

Geospatial Eng. Rept.

and Mapping

Farmer, Jason Project Manager (MVS)/2 years/M.S.

Wetland Ecology, /Professional Wetland

Scientist

Project Manager 

General Project

Oversight

Fiorentino, John Biologist/1year/ M.S. Marine Biology

Northeastern University

Coastal Zone

Consistency

Determination

Fitzgerald, Tye Engineer Intern (CPRA)/1 year/

B.S., Civil Engineering, LSU/E.I.T.

Project Engineer with

Louisiana

Henry, Donovan Ecologist (MVS)/1 year/M.S. Zoology,

Southern Illinois-Carbondale

Benthic Ecology

Hoerner, Melissa Realty Specialist (MVS)/13 years/M.B.A

Business, SIU-Edwardsville

Real Estate

William Klein Environmental Manager (MVN)/16 Years/ M.S.

Wildlife Management, West Virginia University

Environmental

Mach, Rodney Supervisory Civil Engineer (MVN)/30 Years/

B.S. Civil Engineering, Southeastern

Massachusetts University

MVN H&H Rep. on

Oversight Team

MacInnes, Andrew Project Planner (MVN)/10 years Coastal Zone

Management/B.S. Geography, Utah State

Project Manager

Mann, Joseph Regional Economist (MVN)/14 years/

D.B.A., Nova Southeastern-Ft. Lauderdale

Economics

McCaffrey, Kelly Landscape Architect (MVN)/8 years/

B.L.A. Landscape Architecture Mississippi

State University

Aesthetics/Visual

Resources

Parker, Thomas Environmental Resource Specialist/1 year/B.S.

Biology, University of Colorado-Denver

Biological Assessment

Perez, Andrew Outdoor Recreation Planner (MVN)/

5 Years/M.U.R.P.-UNC-Chapel Hill

Recreation/Incidental

Recreation Benefits

Plumley, Marshall Community Planner (MVR)/9 years/

B.S. History/Political Science, Illinois State

University

Plan Formulation Team

Leader

Richardson, Jerica Archaeologist (MVN)/12 years/ B.A.

Anthropology, Mississippi State University

Environmental Justice

Coordinator

Roy, Kevin Senior Field Biologist (USFWS)/15 years/

B.S. Louisiana Tech University

Habitat Evaluation Team

Leader

Slattery, Kevin Environmental Specialist (MVS)/

10 years/B.A. Environmental Studies,

Westminster College/ Certified

Professional in Stormwater Quality

HTRW and Water Quality

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Name

Job Description/Experience/

Education/Registration Subject Matter

Stohl, Melbourne Mechanical Engineer (MVS)/35 years/

B.S. Civil Engineering, Washington University

(St. Louis)

Mechanical Engineer

Terry, William Hydraulic Engineer (MVS)/1 year/

B.S. Civil Engineering, University of Missouri 

Rolla/E.I.T.

Functional Team Leader

Engineering; Hydraulic

Engineering

Tokraks, Nancy Civil Engineer (MVS)/18 years/B.S.

Civil Engineering, University of

Missouri-Rolla

Civil Design

Villarrubia, Chuck Coastal Resources Senior Scientist (CPRA)/

29 years/M.S. Wildlife and Fisheries Science,

University of Tennessee

CPRA Operations

Vosburg, Brian Geologist, III (CPRA)/5 years/B.S.

Geology, LSU

CPRA Geology Review

Wood, Cynthia Document Administration

MVN = New Orleans District; MVS = St. Louis District; MVE = Rock Island District; USFWS = U.S. Fish

and Wildlife Service; CPRA = Louisiana Coastal Protection and Restoration Authority

9.3 LITERATURE CITED

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Service, Twin Cities, Minnesota. 200 pp.

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and Mississippi. Gulf Research Reports 6:109124.

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adjacent wetlands. Environmental Geological Water Sciences 11:271281.

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Mississippi River prior to major human modification. Earth Surf. Process. Landf. 17:711722.

Kryter, K. D. 1994. The Handbook of Hearing and the Effects of Noise: Physiology, and Public Health.

McGraw Hill, New York.

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protection, and restoration act, wetland value assessment methodology: coastal chenier/ridge

community model.

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protection, and restoration act, wetland value assessment methodology: coastal marsh community

models.

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and D.J.P. Swift, 1994, Scientific Assessment of Coastal Wetland Loss, Restoration and

Management in South Louisiana, Journal of Coastal Research, Special Issue No. 20. 103 p.

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Mississippi Delta Plain, likely causes and future implications: U.S. Geological Survey Open-File

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Summary File 4 (SF4). Accessed at http://factfinder.census.gov on 28 October 2009.

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gov/poverty/09poverty.shtml on 28 October 2009.

U.S. Environmental Protection Agency (USEPA). 1995a; 1995b; 1995c; 1995d. Waiting for References

from Author.

U.S. Fish and Wildlife Service (USFWS). 1980. Habitat evaluation procedures (HEP). Div. Ecol. Serv.

ESM 102, U. S. Fish and Wildl. Serv., Washington, DC. 141 pp.

U.S. Fish and Wildlife Service (USFWS). 2001. Florida manatee recovery plan. Southeast Region, U.S.

Fish and Wildlife Service, Atlanta, Georgia. 144 pp. + Appendices.

U.S. Fish and Wildlife Service (USFWS). 2004. Final Fish and Wildlife Coordination Act Report, NearTerm Ecosystem Restoration Plan for the Louisiana Coastal Area. Ecological Services Office,

Lafayette, Louisiana.

U.S. Fish and Wildlife Service (USFWS). 2007. Red wolf recovery plan. Southeast Region. U.S. Fish and

Wildlife Service, Manteo, North Carolina. http://www.fws.gov/redwolf/

U.S. Fish and Wildlife Service (USFWS). 2008. Black Bear Critical Habitat Fact Sheet USFWS.

Southeast Region. U.S. Fish and Wildlife Service, Lafayette, Louisiana.

U.S. Fish and Wildlife Service (USFWS). 2009a. Bald Eagle Fact Sheet USFWS. Southeast Region. U.S.

Fish and Wildlife Service, Endangered Species Program, Arlington, Virginia.

U.S. Fish and Wildlife Service (USFWS). 2009b. Biological Opinion. 2008 Operation of the Bonnet

Carré Spillway. U.S. Fish and Wildlife Service, Lafayette, Louisiana.

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U.S. Geological Survey. 2006. USGS Reports Latest Land-Water Changes for Southeastern Louisiana.

U.S. Fish and Wildlife Service, Ecological Services, Lafayette, Louisiana. Final Fish and Wildlife

Coordination Act Report, Near-Term Ecosystem Restoration Plan for the Louisiana Coastal Area.

October 2004.

Wicker, K.M., 1980. The Mississippi Deltaic Plain habitat mapping study: U.S. Fish and Wildlife

Service, Office of Biological Services, FWS/OBS 79/07, 464 maps.

9.4 GLOSSARY

Acceptability  Adequate to satisfy a need, requirement, or standard. One of the U.S. Army Corps of

Engineers requirements for a project.

Adaptive management  An interdisciplinary approach acknowledging our insufficient information base

for decision-making; that uncertainty and change in managed resources are inevitable; and that new

uncertainties will emerge. An iterative approach that includes monitoring and involves scientists,

engineers and others who provide information and recommendations that are incorporated into

management actions; results are then followed with further research, recommendations and management

actions, and so on.

Aggradational Process of Plant Growth  Plant root material building elevation, usually in fresh marsh.

Air Quality Determination  The Louisiana Department of Environmental Quality ensures that projects

do not adversely affect air quality through this determination as a requirement of the Clean Air Act.

Alternative Plan  A set of one of more management measures within a subprovince functioning

together to address one or more objectives.

Amplitude  The maximum absolute value of a periodically varying quantity.

Anadromous  Ascending rivers from the sea for breeding.

Anoxia  Absence of oxygen.

Anthropogenic  Caused by human activity.

Average Annual Habitat Unit (AAHU)  Represent a numerical combination of habitat quality and

quantity (acres) existing at any given point in time. The habitat units resulting from the future withoutand future with-project scenarios are annualized, and averaged over the project life, to determine Average

Annual Habitat Units (AAHUs).

Aquaculture  The science and business of farming marine or freshwater food fish or shellfish, such as

oysters, crawfish, shrimp and trout, under controlled conditions.

Astronomical Tides  Daily tides controlled by the moon, as opposed to wind-generated tides.

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Barbary Soils  Soils in swamps (with logs and stumps) that are level, very poorly drained, with a thin

mucky surface layer and clayey underlying material.

Benefits  Valuation of positive performance measures.

Benthic  Living on or in sea, lake, or stream bottoms.

Biomass  The total mass of living matter (plant and animal) within a given unit of environmental area.

Bottomland Hardwood Forest  Low-lying forested wetlands found along streams and rivers.

Brackish Marsh (BRM)  Intertidal plant community typically found in the area of the estuary where

salinity ranges between 415 ppt.

Chenier Plain  Western part of coastal Louisiana with little influence from Mississippi and Atchafalaya

rivers.

Clean Water Act Section 404 (b) (1)  There are several sections of this Act that pertain to regulating

discharges into wetlands. The discharge of dredged or fill material into waters of the United States is

subject to permitting specified under Title IV (Permits and Licenses) of this Act and specifically under

Section 404 (Discharges of Dredge or Fill Material) of the Act.

Coastal Zone Consistency Determination  The U.S. Environmental Protection Agency reviews plans

for activities in the coastal zone to ensure they are consistent with federally approved State Coastal

Management Programs under Section 307(c)(3)(B) of the Coastal Zone Management Act.

Coast-wide Plan  Combination of alternative plans assembled to address an objective of set of

objectives across the entire Louisiana Coast.

Collocated Team  A collection of scientists and professionals from the U.S. Army Corps of Engineers,

U.S. Fish and Wildlife Service, NOAA Fisheries, Natural Resources Conservation Service, U.S.

Geological Survey, U.S. Environmental Protection Agency, Louisiana Department of Natural Resources,

and Louisiana Department of Wildlife and Fisheries that are located at the USACE, New Orleans District,

office and work together on the LCA Plan.

Compaction of Holocene Deposits  Deltaic mud that packs down under its own weight.

Completeness  The ability of a plan to address all of the objectives. One of the USACE four

requirements for a project.

Comprehensive Plan  Same as Coast-wide Plan.

Conditional Authorization  Authorization for implementation of a project subject to approval of the

project feasibility-level decision document by the Assistant Secretary of the Army for Civil Works.

Congressional Authorization  Authorization for investigation to prepare necessary feasibility-level

report to be recommended for authorization of potential future project construction by Congress.

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Connectivity  Property of ecosystems that allows for exchange of resources and organisms throughout

the broader ecosystem.

Continental Shelf  The edge of the continent under gulf waters; the shallow Gulf of Mexico fringing the

coast.

Control Structure  A gate, lock, or weir that controls the flow of water.

Crevasse  A breach or gap in the levee or embankment of a river (natural or manmade), through which

floodwaters flow.

Cumulative Impacts  The combined effect of all direct and indirect impacts to a resource over time.

Datum  A point, line, or surface used as a reference, as in surveying, mapping, or geology.

Deciduous Forest  Forest composed mostly of trees that lose their leaves in the winter.

Decomposition  Breakdown or decay of organic materials.

Degradation Phase  The phase of the deltaic cycle when sediments are no longer delivered to a delta,

and it experiences erosion, dieback, or breakup of marshes.

Deltaic Cycle  Capture of the Mississippi River by a distributary that offered a shorter route to the Gulf

of Mexico. After abandonment of an older delta lobe, which would cut off the primary supply of

freshwater and sediment, an area would undergo compaction, subsidence, and erosion. The old delta lobe

would begin to retreat as the gulf advanced, forming lakes, bays, and sounds. Concurrently, a new delta

lobe would begin its advance gulfward.

Deltaic Deposits  Mud and sand deposited at the mouth of a river.

Deltaic Plain  The land formed and reworked as the Mississippi River switched channels in the eastern

part of the Louisiana coastal area.

Demersal  Dwelling at or near the bottom of a body of water (e.g., a demersal fish).

Detritus  The remains of plant material that has been destroyed or broken up.

Dewatering  The process of dredged sediments compacting while losing water after being deposited.

Discharge  The volume of fluid passing a point per unit of time, commonly expressed in cubic feet per

second, millions of gallons per day, or gallons per minute.

Dissolved Oxygen  Oxygen dissolved in water, available for respiration by aquatic organisms. One of

the most important indicators of the condition of a water body.

Direct Impacts  Those effects that result from the initial construction of a measure (e.g., marsh

destroyed during the dredging of a canal). Contrast with Indirect Effects.

Diurnal  Relating to or occurring in a 24-hour period; daily.

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Diversion  A turning aside or alteration of the natural course or flow of water. In coastal restoration this

usually consists of such actions as channeling water through a canal, pipe, or conduit to introduce water

and water-borne resources into a receiving area.

Dredged material embankments (Spoil Banks, Side-cast Banks, Excavated Material Banks) 

Dredged material removed from canals and piled in a linear mound along the edge of canals.

Dynamic  Characterized by continuous change and activity.

Ecological  Refers to the relationship between living things and their environment.

Economic  Of or relating to the production, development, and management of material wealth, as of a

country, household, or business enterprise.

Ecosystem  An organic community of plants and animals viewed within its physical environment

(habitat); the ecosystem results from the interaction between soil, climate, vegetation and animal life.

Ecosystem Restoration  activities that seek to return a organic community of plants and animals and

their habitat to a previously existing or improved natural condition or function.

Effectiveness  Having an intended or expected effect. One of the USACE four requirements for a

project.

Efficiency  The quality of exhibiting a high ratio of output to input. One of the USACE four

requirements for a project.

Egress  A path or opening for going out; an exit.

Electrical Conductivity  The ability of a medium to conduct electricity. Salt water has a higher

electrical conductivity than freshwater, and this property allows the measurement of salinity through a

simple meter.

Embankment  A linear mound of earth or stone existing or built to hold back water or to support a

roadway.

Encroachment Entering gradually into an area not previously occupied, such as a plant species

distribution changing in response to environmental factors such as salinity.

Endangered Species  Animals and plants that are threatened with extinction.

Endpoints  see Objectives

Engineering News Record (ENR)  A magazine that provides news needed by anyone in or from the

construction industry.

Enhance  To augment or increase/heighten the existing state of an area.

Entrenchment  Being firmly embedded.

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Environmental Impact Statement (EIS)  A document that describes the positive and negative

environmental effects of a proposed action and the possible alternatives to that action. The EIS is used by

the Federal Government and addresses social issues as well as environmental ones.

Estuary  A semi-enclosed body of water with freshwater input and a connection to the sea where

freshwater and saltwater mix.

Estuarine  Related to an estuary.

Evaporation  The process by which any substance is converted from a liquid state into, and carried off

in, vapor; as, the evaporation of water.

Exotic Species  Animal and plant species not native to the area; usually undesirable (e.g., hyacinth,

nutria, tallow tree, giant salvinia).

Faulting  A fracture in the continuity of a rock formation caused by a shifting or dislodging of the

earth's crust, in which adjacent surfaces are displaced relative to one another and parallel to the plane of

fracture.

Feasibility Report  A description of a proposed action, previously outlined in a general fashion in a

Reconnaissance Report, that will satisfy the Federal interest and address the problems and needs

identified for an area. It must include an assessment of impacts to the environment (either in an

Environmental Assessment, or the more robust Environmental Impact Statement), an analysis of

alternative methods of completion, and the selection of a Recommended Plan through the use of a costeffectiveness analysis.

Feature  A constructible increment of an alternative plan.

Federal Principals Group (FPG) A collaboration among Federal agencies at the Washington level to

facilitate the flow of information, to provide guidance and recommendations to the USACE and LDNR

throughout the study process, and to facilitate resolution of any interagency issues that may be identified

in the conduct of the study.

Final Array  The final grouping of the most effective coast-wide plans from which a final

recommendation can be made.

Foreshore Dikes  An embankment of earth and rock built to prevent floods or erosion that is built in the

area of a shore that lies between the average high tide mark and the average low tide mark.

Framework Development Team (FDT)  A group of professionals from various Federal and state

agencies, academia and the public formed to provide a forum for individual members to discuss LCA

Comprehensive Study activities and technical issues and to provide comments to the Senior Management

Committee.

Fresh Marsh (FAM)  Intertidal herbaceous plant community typically found in that area of the estuary

with salinity ranging from 03 ppt.

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Furbearer  An animal whose skin is covered with fur, especially fur that is commercially valuable, such

as muskrat, nutria, and mink.

Geomorphic  Related to the geological surface configuration.

Geosynclinal Down-warping  The downward bend or subsidence of the earth's crust, which allows of

the gradual accumulation of sediment

Geotropically  Downward growth in response to gravity, as in plant roots.

Glycophytes  A plant that cannot live in high salinity environments, most plants.

Goals  Statements on what to accomplish and/or what is needed to address a problem without specific

detail.

Gradient  A slope; a series of progressively increasing or decreasing differences in a system or

organism.

Habitat  The place where an organism lives; part of physical environment in which a plant or animal

lives.

Habitat Loss  The disappearance of places where target groups of organisms live. In coastal restoration,

usually refers to the conversion of marsh or swamp to open water.

Habitat Units (HUs)  Represent a numerical combination of quality (HIS) and quantity (acres) existing

at any given point in time. The HUs resulting from the future without- and future with project scenarios

are annualized, and averaged over the project life, to determine Average Annual Habitat Units (ASHUs).

The benefit of a project can be quantified by comparing AAHUs between the future without- and future

with-project scenarios. The difference is AAHUs between the two scenarios represents the net benefit

attributable to the project in terms of habitat quantity and quality.

Hazardous, Toxic, and Radioactive Wastes (HTRW)  Projects features must be examined to ensure

that their implementation will not result in excessive exposure to pollutants possibly located in the study

area.

Headland  A point of land projecting into the sea or other expanse of water, still connected with the

mainland.

Herbaceous  A plant with no persistent woody stem above ground.

Hydrodynamic  The continuous change or movement of water

Hydrology  The pattern of water movement on the earth's surface, in the soil and underlying rocks, and

in the atmosphere.

Hypoxia  The condition of low dissolved oxygen concentrations.

Indemnification  Insurance against or compensation for loss or damage.

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Indirect Impacts  Those effects that are not as a direct result of project construction, but occur as

secondary impacts due to changes in the environment brought about by the construction. Contrast with

Direct Impacts.

Infrastructure  The basic facilities, services, and installations needed for the functioning of a

community or society, such as transportation and communications systems, water and power lines, and

public institutions including schools, post offices, and prisons.

Ingress  An entrance or the act of entering.

Inorganic  Not derived from living organisms; mineral; matter other than plant or animal.

Interdistributary Deposits  Sand and mud deposited between the river channels or between bayous.

Intermediate Marsh (INM)  Intertidal herbaceous plant community typically found in that area of the

estuary with salinity ranging from 25 ppt.

Intertidal  Alternately flooded and exposed by tides.

Invertebrates  Animals without backbones, including shrimp, crabs, oysters, and worms.

Keystone Strategy  A strategy that other strategies rely upon for successful implementation.

Land-water Ratio  The relative proportion or wetlands and uplands to water in an area.

Larvae  The stage in some animals life cycles between egg and adult (most invertebrates).

Leeward  Sheltered from the wind; away from the wind.

Levee  A linear mound of earth or stone built to prevent a river from overflowing; a long, broad, low

ridge built by a stream on its flood plain along one or both banks of its channel in time of flood.

Loamy  Soil composed of a mixture of sand, clay, silt, and organic matter.

Maintain  To keep in existing state.

Measure  A programmatic restoration feature that can be assembled with other measures to produce

alternative plans. See also Project.

Methodology  A set of practices, procedures, and rules.

Mineral Substrate  Soil composed predominately of mineral rather than organic materials; less than 20

percent organic material.

Mudflats  Flat, unvegetated wetlands subject to periodic flooding and minor wave action.

Myatt Series  Gray terrace soil, with whitish, pebbly subsoil.

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National Ecosystem Restoration (NER)  USACE standard for cost-effectiveness based on ecosystem,

not economic, benefits.

Near-shore Currents  Movement of water parallel to the shoreline. Usually generated by waves

breaking on the shore at an angle other than perpendicular.

National Environmental Policy Act (NEPA)  Ensures that Federal agencies consider the

environmental impacts of their actions and decisions. NEPA requires all Federal agencies to consider the

values of environmental preservation for all significant actions and prescribes procedural measures to

ensure that those values are fully respected.

Net Gain  The amount of cumulative land gain less land loss, when gain is greater than loss.

Net Loss  The amount of cumulative land gain less land loss, when gain is less than loss.

No Action Alternative  The alternative in the LCA Plan which describes the ecosystem of the coastal

area if no restoration efforts/projects were done.

Nursery  A place for larval or juvenile animals to live, eat, and grow.

Objectives  More specific statements than Goals, describing how to achieve the desired targets.

Oceanic-dumping  The discharge of wastes or pollutants into offshore waters.

Organic  Composed of or derived from living things.

Oscillations  Fluctuations back and forth, or up and down.

Oxidation of Organic Matter  The decomposition (rotting, breaking down) of plant material through

exposure to oxygen.

Oxygen-depleted  Situation of low oxygen concentrations where living organisms are stressed.

Petrochemical  Any compound derived from petroleum or natural gas.

Planning Scale  Planning term that reflects the degree to which environmental processes would be

restored or reestablished, and the resulting ecosystem and landscape changes that would be expected over

the next 50 years. This uppermost scale is referred to as Increase. No net loss of ecosystem function is

Maintain. Reducing the project rate of loss of function is Reduce. The lowest possible scale was no

further action above and beyond existing projects and programs.

Point-Bar Deposit  The shallow depositional area on the inside bank of a river bend.

Post-larval  Stage in an animals lifecycle after metamorphosis from the larval stage, but not yet fully

grown.

Potable Water  Water that is fit to drink.

ppt  parts per thousand. The salinity of ocean water is approximately 35 ppt.

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Primary Consolidation/Secondary Compression  Two processes acting on a substrate that has a load

applied to it to cause the sediment to increase in density, and decrease in volume.

Prime Farmland  Land that has the best combination of physical and chemical characteristics for

producing food, feed, fiber, forage, oilseed, and other agricultural crops with minimum inputs of fuel,

fertilizer, pesticides, and labor, and without intolerable soil erosion. One of the categories of concern in

the EIS.

Principles  Framing statements that can be used to evaluate alternatives while considering issues that

affect them. Used along with targets and assessments of ecosystem needs to provide guidance in

formulation of alternative plans.

Productivity  Growth of plants and animals.

Progradation  The phase during the deltaic cycle where land is being actively accreted through

deposition of river sediments near the mouth.

Programmatic Environmental Impact Statement (PEIS)  and Environmental Impact Statement that

supports a broad authorization for action, contingent on more specific detailing of impacts from specific

measures.

Project  A constructible increment of an alternative plan.

Project Implementation Report (PIR)  A project-specific follow-up report that expands on the

information contained in a Programmatic Feasibility Report to ensure NEPA compliance, such as

conducting public meetings, preparing the appropriate environmental documentation, and preparing the

engineering designs as specifications necessary to build the project.

Province  A major division of the coastal zone of Louisiana. (e.g., Deltaic Plain and Chenier Plain).

Pulsing  Letting a diversion flow periodically at a high rate for a short time, rather than continuously.

Quantitative  Able to assign a specific number; susceptible to measurement.

Radiocarbon Age Determination The use of the ratio of carbon isotopes to determine age.

Rebuild  To some extent build back a structure/landform that had once existed.

Reconnaissance Report  A document prepared as part of a major authorization that examines a problem

or need and determines if sufficient methods and Federal interest exists to address the problem/need. If so,

then a Feasibility Report is prepared, which details the solution and its impacts further.

Reduce  To diminish the rate or speed of a process.

Regional Working Group (RWG)  An interagency team formed to support the Washington-level

Federal Principals Group and to facilitate regional level collaboration and coordination on the LCA

study.

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Rehabilitate  To focus on historical or pre-existing ecosystems as models or references while

emphasizing the reparation of ecosystem processes, productivity and service.

Relative Sea Level Rise  The sum of the sinking of the land (subsidence) and eustatic sea level change;

the change in average water level with respect to the surface.

Restore  Return a wetland to a close approximation of its condition or function prior to disturbance by

modifying conditions responsible for the loss or change; re-establish the function and structure of that

ecosystem.

Sangamonian Interglacial Period  the last interglacial period before the Holocene period (the current

geological period).

Saline Marsh (SAW)  Intertidal herbaceous plant community typically found in that area of the estuary

with salinity ranging from 1232 ppt.

Salinity  The concentration of dissolved salts in a body of water, commonly expressed as parts per

thousand.

Salt Marshes  See Saline Marsh.

Scoping  Soliciting and receiving public input to determine issues, resources, impacts, and alternatives

to be addressed in the draft EIS.

Sea-Level  Long-term average position of the sea surface.

Sediment Plume  Caused by sediment rich rainwater runoff entering the ocean. The runoff creates a

visible pattern of brown water that is rich in nutrients and suspended sediments that forms a kind of cloud

in the water spreading out from the coastline. Commonly forms at river and stream mouths, near sloughs,

and along coasts where a large amount of rain runoff flows directly into the ocean.

Sheet Flow  Flow of water, sediment, and nutrients across a flooded wetland surface, as opposed to

through channels.

Shoaling  The shallowing of an open-water area through deposition of sediments.

Slikensides  The smooth or partially polished surface of rock caused by one rock mass sliding over

another in a fault plane.

Social  Relating to human society and its modes of organization.

Socioeconomic  Involving both social and economic factors.

Spoil Banks  Dredged material removed from canals and piled in a linear mound along the edge of

canals.

Stabilize  To fix the level or fluctuation of; to make stable.

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State Historic Preservation Office (SHPO)  The part of the Louisiana Department of Culture,

Recreation, and Tourism that deals with Indian sites and other archaeological remains.

Stillstand  A period of time when sea level did not change.

Storm Overwash  The process by which sand is transposed landward over the dunes during a storm

event by waves.

Storm Surge  An abnormal and sudden rise of the sea along a shore as a result of the winds of a storm.

Stough soils  Yellowish brown coarse-loamy soil.

Strategy  Ecosystem restoration concept from the Coast 2050 Plan.

Stream Gaging Data  Records of water levels in streams and rivers.

Submergence  Going under water.

Subprovince  The divisions of the two Provinces (see Province) into smaller groupings: 1) east of the

Mississippi River; 2) west of the Mississippi River to Bayou Lafourche; 3) Bayou Lafourche to

Freshwater Bayou; 4) Freshwater Bayou to Sabine River.

Subsidence  The gradual downward settling or sinking of the Earths surface with little or no horizontal

motion.

Sustain  To support and provide with nourishment to keep in existence; maintain.

Tarbert Flow  Stream gage data recorded at Tarberts Landing on the Mississippi River.

Target  A desired ecosystem state that meets and objective or set of objectives.

Terrestrial Habitat  The land area or environment where an organism lives; as distinct from water or

air habitats.

Third Delta  A proposed project that would divert up to 120,000 cubic feet of water per second from the

Mississippi River near Donaldsonville, Louisiana down a conveyance channel to the marshes in southern

Barataria and Terrebonne Basins.

Toxicity  The measure of how poisonous something is.

Transpiration  The process by which water passes through living plants into the atmosphere.

Turbidity  The level of suspended sediments in water; opposite of clarity or clearness.

Unique Farmland  Land other than Prime Farmland (see Prime Farmland) that is used for the

production of specific high-value food and fiber crops, such as citrus, tree nuts, olives, cranberries, fruits,

and vegetables.

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Upconing  The tendency of underground saltwater to move closer to the surface in the vicinity of a well

by drawing fresh ground water out.

Upland (UPL)  A general term for non-wetland elevated land above low areas along streams or between

hills.

Water Resource Units (WRU)  Stage-damage data developed as part of the Flood Damage Estimation

System (FDES) in 1980 for the Mississippi River and Tributaries (MR&T) project were used to estimate

the flood damages that are expected to occur in subprovinces 1, 2, and 3. The data collected for the FDES

were delineated into geographic areas with homogenous physical and hydraulic characteristics. These

geographic areas were numerically coded and designated as Water Resource Units (WRUs). Within each

WRU, land-use elements (structures, cropland, roads, bridges, railroads, etc.) were categorized by

location, value, and corresponding depth-damage relationship. The structural damage categories included

residential, commercial, industrial, public, and farm buildings.

Water Resources Development Act (WRDA)  A bill passed by Congress that provides authorization

and/or appropriation for projects related to the conservation and development of water and related

resources.

Weir  A dam placed across a canal or river to raise, divert, regulate or measure the flow of water.

9.5 ACRONYMS AND ABBREVIATIONS

ASA(CW) Assistant Secretary of the Army for Civil Works

ATR Agency Technical Review

CAA Clean Air Act

CE/ICA Cost Effectiveness/Incremental Cost Analysis

CEQ Council on Environmental Quality

CFR Code of Federal Regulations

cfs Cubic Feet per Second

CIAP Coastal Impact Assistance Program

CPRA Coastal Protection and Restoration Authority (State of Louisiana)

CRCL Coalition to Restore Coastal Louisiana

CWPPRA Coastal Wetlands Planning, Protection, and Restoration Act

CZM Coastal Zone Management

DEIS Draft Environmental Impact Statement

EA Environmental Assessment

EFH Essential Fish Habitat

EIS Environmental Impact Statement

EPA Environmental Protection Agency

ER Engineering Regulation

ESA Endangered Species Act

FHWA Federal Highway Administration

FMP Fisheries Management Plan

GIS Geographic Information System

GIWW Gulf Intracoastal Waterway

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GMFMC Gulf of Mexico Fishery Management Council

HET Habitat Evaluation Team

HSDRRS Hurricane and Storm Damage Risk Reduction System

HTRW Hazardous, Toxic, and Radioactive Waste

IPET Interagency Performance Evaluation Task force

IPDT Interagency Project Delivery Team

IWR Institute of Water Resources

LACPR Louisiana Coastal Protection and Restoration

LCA Louisiana Coastal Area (Ecosystem Restoration Study, 2004)

LCWRP Louisiana Coastal Wetlands Restoration Plan

LDNR Louisiana Department of Natural Resources

LDWF Louisiana Department of Wildlife and Fisheries

LERRD Land, Easements, Rights-Of-Way, Relocation, and Disposal Areas

LEQA Louisiana Environmental Quality Act

LNHP Louisiana Natural Heritage Program

LOSCO Louisiana Oil Spill Coordinators Office

LPBF Lake Pontchartrain Basin Foundation

MDWD Medium Diversion at White Ditch

MR&T Mississippi River and Tributaries

MSA Metropolitan Statistical Area

MVD USACE Mississippi Valley Division

MVN USACE New Orleans District

MVR USACE Rock Island District

MVS USACE St. Louis District

NAAQS National Ambient Air Quality Standards

NAC Noise Abatement Criteria

NAVD North American Vertical Datum

NEPA National Environmental Policy Act

NER National Ecosystem Restoration

NGO Non-Governmental Organization

NHPA National Historic Preservation Act

NMFS National Marine Fisheries Service

NOAA National Oceanic and Atmospheric Administration

NOI Notice of Intent

NRCS Natural Resources Conservation Service

NRHP National Register of Historic Places

NWRC National Wildlife Research Center

CPRA Coastal Protection and Restoration Authority

O&M Operation and Maintenance

OMRR&R Operation and Maintenance, Repair, Replacement and Rehabilitation

PEIS Programmatic Environmental Impact Statement

PDT Project Delivery Team

PPL Project Priority List

S&T Science and Technology

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SEIS Supplemental Environmental Impact Statement

USACE U.S. Army Corps of Engineers

USDA-SCS United States Department of Agriculture, Soil Conservation Service

USEPA U.S. Environmental Protection Agency

USFWS U.S. Fish and Wildlife Service

USGS U.S. Geological Survey

WCRF Wetlands Conservation and Restoration Fund

WVA Wetland Value Assessment

WRDA Water Resources Development Act

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Supplemental Enviro al Impact Statement nment

for the

LCA Medium Diversion at White Ditch

Plaquemines Parish, Louisiana

(APPENDICES A  N)

The responsible lead Federal agency for this study is the U. S. Army Corps of

Engineer District, New Orleans. The Non-Federal Sponsor for the study is the

Louisiana Coastal Protection and Restoration Authority. The responsible

cooperating Federal agency is the U.S. Fish and Wildlife Service. This report is a

combined feasibility report and supplemental environmental impact statement

complying with requirements of the U.S. Army Corps of Engineers (USACE) and

the Council of Environmental Quality (CEQ), and is intended to reduce duplication

and paperwork. An asterisk (*) in the table of contents notes paragraphs that are

required for National Environmental Policy Act (NEPA) compliance.

October 2010

U.S Army Corps of Engineers

New Orleans District Coastal Protection and Restoration

Authority

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Biological Assessment

U.S. Fish and Wildlife Service

411

U.S. ARMY CORPS

OF ENGINEERS

NEW ORLEANS DISTRICT

September 2010

BIOLOGICAL ASSESSMENT for LCA - Medium Diversion at White Ditch

Prepared by: U.S. Army Corps of Engineers

New Orleans District

Lead Contact: Thomas Parker

U.S. Army Corps of Engineers, PD-RP

Physical Address:

7400 Leake Ave. Room 363

New Orleans, LA 70118

Mailing Address:

P.O. Box 60267

New Orleans, LA 70160-0267

Email: thomas.w.parker@usace.army.mil

Phone: (504) 862-2526

Fax: (504) 862-2088

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Table of Contents

Introduction................................................................................................................................1

Threatened, Endangered, and Proposed Threatened or Endangered Species ............................1

Sensitive Species and Species of Concern.................................................................................1

Critical Habitat...........................................................................................................................2

Previous Consultation ................................................................................................................2

Purpose.......................................................................................................................................2

Location of the Proposed Action ...............................................................................................3

Proposed Action.........................................................................................................................5

Species Description....................................................................................................................8

Pallid Sturgeon.....................................................................................................................8

Status..............................................................................................................................8

Species and Habitat Description ....................................................................................8

Management and Protection ........................................................................................10

West Indian Manatee .........................................................................................................12

Status............................................................................................................................12

Species and Habitat Description ..................................................................................12

Management and Protection ........................................................................................13

Piping Plover......................................................................................................................14

Status............................................................................................................................14

Species and Habitat Description ..................................................................................14

Management and Protection ........................................................................................16

Bald Eagle..........................................................................................................................16

Status............................................................................................................................16

Brown Pelican....................................................................................................................17

Status............................................................................................................................17

Colonial Nesting Birds.......................................................................................................17

Status............................................................................................................................17

Effects of the Proposed Action ................................................................................................17

Pallid Sturgeon...................................................................................................................17

West Indian Manatee .........................................................................................................18

Piping Plover......................................................................................................................19

Conclusion ...............................................................................................................................19

Literature Cited ........................................................................................................................20

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Tables

Table 1: Summary of effort and number of sturgeon collected from the Mississippi

River during the period 2001-2009..........................................................................................12

Figures

Figure 1: Study Area Map..........................................................................................................4

Figure 2: Proposed Medium Diversion at White Ditch .............................................................6

Figure 3: Map of Proposed Medium Diversion at White Ditch.................................................7

Figure 4: Piping Plover Range.................................................................................................14

[Cover Photo: Existing siphon at White Ditch]

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Introduction

This Biological Assessment (BA) is submitted to the U.S. Fish and Wildlife Service

(USFWS) by the U.S. Army Corps of Engineers, New Orleans District (CEMVN) in order to

initiate formal consultation with USFWS regarding potential impacts to threatened and

endangered species from construction and operation of the LCA Medium Diversion at White

Ditch (MDWD) project. The following BA is promulgated in accordance with Section 7

(Interagency Consultation) of the Endangered Species Act of 1973, as amended (PL 93-205; 16

U.S.C. 1531 et. seq.). A separate BA has been prepared and will be submitted to the National

Marine Fisheries Service for species under their purview, including Gulf sturgeon (Acipenser

oxyrhynchus desotoi), green sea turtle (Chelonia mydas), hawksbill sea turtle (Eretmochelys

imbricate), Kemp’s ridley sea turtle (Lepidochelys kempii), leatherback sea turtle (Dermochylys

coriacea), and the loggerhead sea turtle (Caretta caretta).

The purpose of this biological assessment is to evaluate the possible effects of the

proposed construction and operation of the MDWD project on threatened, endangered and

proposed threatened and endangered species and their habitats. Threatened, endangered and

proposed threatened and endangered species are managed under the authority of the Federal

Endangered Species Act (ESA) (PL 93-205, as amended). Under provisions of the ESA, Federal

agencies shall use their authorities to carry out programs for the conservation of listed species,

and shall insure any action authorized, funded, or implemented by the agency is not likely to: (1)

adversely affect listed species or designated critical habitat; (2) jeopardize the continued

existence of proposed species; or (3) adversely modify proposed critical habitat (16 USC 1536).

The species of concern that are known to inhabit the area are:

Threatened, Endangered, and Proposed Threatened or Endangered Species

Pallid Sturgeon (Scaphirynchus albus), was listed as endangered throughout its range on

October 9, 1990 (55 FR 36641-36647)

West Indian Manatee (Trichechus manatus), was listed as endangered on June 2, 1970

(35 FR 8491, Appendix A)

Piping Plover (Charadrius melodus), was listed as threatened and endangered on

December 11, 1985 (50 FR, 50720-50734)

Sensitive Species and Species of Concern

Bald Eagle (Haliaeetus leucocephalus), was de-listed on August 9, 2007 (72 FR 37345

37372)

Brown Pelican (Pelecanus occidentalis), was de-listed on November 17, 2009 (74 FR

59443 59472)

Colonial Nesting Birds

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Critical Habitat

No critical habitat is currently designated for any of the threatened, endangered, or

sensitive species within the project area.

Previous Consultation

Informal coordination with the USFWS Lafayette, LA office, for the effects to pallid

sturgeon from entrainment through diversion structures, has been ongoing since the 2008

operation of the Bonnet Carre Spillway. There has been no coordination conducted for the

proposed action described in this document.

Purpose

This LCA Medium Diversion at White Ditch (MDWD) project is to help restore areas

where an altered supply and distribution of freshwater, lack of deltaic forming sediments, marsh

subsistence and human development in the White Ditch area have resulted in degraded and

unbalanced distribution of freshwater, brackish, and saltwater marsh habitats. Further, the

degradation of the existing marshes has made them more vulnerable to the range of Gulf storm

events; extreme and seasonal, resulting in accelerated degradation, altered hydrology and

changed salinity regimes.

Installation of the White Ditch diversion siphon was completed in 1963 with the

objective of enhancing muskrat and oyster habitat. In the absence of an outfall management

plan, the surrounding marsh received limited benefits from the diverted river water. Two 50-

inch steel pipes divert water from the Mississippi River through the White Ditch, into the Belair

Canal and then into the River aux Chenes, where it continues south and out of the project area.

Usage of the siphons was abandoned for many years and they degraded into a non-usable

condition. The siphons were recently refurbished and water was diverted into White Ditch as

part of research efforts.

Wetlands in the project area are deteriorating for several reasons: 1) subsidence, 2) lack

of sediment and nutrient deposition, 3) erosion via tidal exchange, 4) channelization, 5) saltwater

intrusion and 6) lack of freshwater. Recent hurricanes and tropical storms have also caused

significant damage to the project area. These activities have resulted in the loss of several

thousand acres of previously solid, vegetated marsh. Deterioration will continue unless

preventative measures are taken.

In the absence of supplemental freshwater and sediment from the Mississippi River,

subsidence, sea-level rise, wave erosion, and saltwater intrusion will continue to be problems.

Protection and enhancement of this area are dependent on providing a hydrologic and sediment

regime that minimizes the physiological stress to wetland vegetation from saltwater intrusion and

tidal energy and is conducive to the retention of locally provided freshwater and sediments

The historic geology of the project area indicates that the current course of the

Mississippi River has remained the same for the last 700 years and has directly influenced the

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development of the entire area. The project area is located on the east side of the Mississippi

River and was formed between two natural levee ridge systems, River aux Chenes on the east

and the Mississippi River on the west. There are also two unnamed bayou ridges found within

the project area. These ridges formed along the old natural bayous which were distributary

channels for the Mississippi River. These natural bayous once carried sediments and nutrients

into the project area during high river stages when the natural ridges were seasonally overtopped.

In the historical setting, floodwater from the river would recede and sediments and

nutrients would be deposited in the inter-distributary basins located between ridges. During

normal or low river stages the ridges along the distributary channels served like levees and

buffered the basin areas from the daily tidal influence. This buffering effect created a low

energy freshwater environment in the inter-distributary basins, forming deep organic soils.

Drainage to the area was provided by a high water event breaching the River aux Chenes ridge in

the southern part of the project area. This event caused the development of the Bayou Garelle

tributary channel.

The present day hydrology of the project area has been altered and no longer functions in

a historically natural pattern. Historically, water moved very slowly through the system.

Freshwater slowly exited the system through meandering pathways in the marsh and saltwater

was slow to intrude. Presently, changes in the marsh allow water to rapidly pass through the

system and saltwater is able to quickly intrude. The hydrologic balance within the marsh has

been disturbed due to the following man-made changes:

1. The Mississippi River can no longer overflow its banks into the project area due to the

Mississippi River protection levee. This has eliminated the introduction of freshwater

from the river and disrupted natural sediment deposition patterns.

2. Channels have been dredged through natural ridges which has increased drainage and

tidal exchange and exposed the soil to erosive forces.

This project was identified as a Near-term Critical Restoration Feature Recommended for

Study and Future Congressional Authorization in the LCA Main Report dated January 21, 2005.

In November 2007, the Water Resources Development Act of 2007 passed, authorizing this and

other projects from the LCA Main Report. The MDWD feasibility study is anticipated to result

in a Chief’s Report containing a recommended plan to construct a Mississippi River diversion in

the vicinity of White Ditch for the purposes of introducing freshwater, sediments, and nutrients

into the study area.

Location of the Proposed Action

The MDWD project study area is located in LCA Subprovince 1 in the Breton Sound

hydrologic basin in Plaquemines Parish, Louisiana (see Figure 1). The boundary of the project

encompasses over 98,000 acres of intermediate to brackish intertidal wetland habitats that has

been heavily influenced by both man-made and natural processes. Channel construction,

subsidence, erosion, saltwater intrusion, and storm-related damages have all significantly altered

the natural environment, causing extensive losses of wetland habitats. The study area boundary

follows distinct landscape features beginning in the north with the confluence of the non-Federal

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back levee and the forty-arpent canal, extending along the non-Federal back levee, the

Mississippi River levee, the Federal back levee and along the left descending natural bank of the

Mississippi River to the west; past American Bay, California Bay, and through Breton Sound,

near Bay Gardene to the south; into and along River aux Chenes to the east, and back to the point

of beginning. The area has been significantly impacted by recent tropical storms and hurricanes

and is currently isolated from the effects of the Caernarvon freshwater diversion, located at the

northern end of the Breton Sound basin.

There are two discreet project locations that will be considered for the purposes of the

feasibility study: The area along the Mississippi River where a freshwater diversion structure

might be located; and the project area that could be influenced and benefited by the diverted

freshwater. The area of interest where a diversion structure could be located occurs on the left

descending bank of the Mississippi River, between White Ditch to the north (river mile 64.5) and

the community of Phoenix to the south (river mile 59.8). This 4.7 mile stretch is unique in that

there is no hurricane protection levee (back levee) on the marsh side that protects existing homes

and infrastructure from elevated water levels (tidal or storm surge). The Mississippi River levee

is the only flood protection structure that keeps river water from entering the project study area.

This situation minimizes the amount of infrastructure that could be affected by construction of a

diversion structure and allows for a broader array of measures to be considered in addressing

problems in the project area.

Figure 1: Study Area Map

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Proposed Action

The tentatively selected plan proposes the construction of a medium sized diversion

structure capable of diverting up to 35,000 cfs consisting of 10 15-ft. x 15-ft. box culverts with

hydraulic operated sluice gates, and constructing an outfall channel to carry fresh water and

sediment to the desired locations in the marsh. Additionally, there will be 32 acres of ridge and

terrace creation and 385 acres of marsh creation utilizing dredged material from an adjacent 223

acres of canal being reconfigured to convey freshwater, nutrient and sediments.

The current operating plan for the tentatively selected plan at the White Ditch Diversion

is limited to a diversion pulse of 35,000 cfs in March-April of each year, during the normal high

flow period of the Mississippi River, and a diversion of 1,000 cfs the rest of the year. This flow

rate may not be experienced over the full 60-day period. The proposed 35,000 cfs diversion will

be the largest man-made diverted flow for wetland building on the Lower Mississippi River, but

the one to two month duration will be a modifying factor. The diversion should approximate five

percent or less of the main channel flow for most years.

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Figure 2: Proposed Medium Diversion at White Ditch

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Figure 3: Map of Proposed Medium Diversion at White Ditch

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Species Descriptions

Pallid Sturgeon (Scaphirynchus albus)

Status

The pallid sturgeon was listed as endangered throughout its range on October 9, 1990 (55

FR 36641-36647). The reasons for listing were habitat modification, apparent lack of natural

reproduction, commercial harvest, and hybridization in parts of its range. To date no critical

habitat has not been proposed or designated for this species.

Species and Habitat Description

The pallid sturgeon is a bottom oriented, large river obligate inhabiting the Missouri and

Mississippi Rivers from Montana to Louisiana and the Atchafalaya River. The pallid sturgeon is

adapted to the predevelopment habitat conditions that historically existed in these large rivers.

Those conditions can generally be described as large, free-flowing, warm water, turbid habitats

with a diverse assemblage of physical attributes that were in a constant state of change.

Floodplains, backwaters, chutes, sloughs, islands, sandbars and main channel waters formed the

large-river ecosystem that provided macrohabitat requirements for all life stages of pallid

sturgeon and other large river fish. Within this range, pallid sturgeon tend to select main channel

habitats in the Mississippi River and main channel areas with islands or sand bars in the upper

Missouri River (USFWS 2009).

Pallid sturgeon are Federally listed as endangered and have been described as one of the

rarest fish in North America. The pallid sturgeon was listed due to the apparent lack of

recruitment for over 15 years, and the habitat threats existing at the time of listing. Destruction

and alteration of habitats by human modification of the river system is believed to be the primary

cause of decline in reproduction, growth, and survival of the pallid sturgeon. The curtailment of

range and habitat destruction/modification were primarily attributed to the construction and

operation of dams on the upper Missouri River and modification of riverine habitat by

channelization of the lower main stem Missouri River and Mississippi Rivers. Dams

substantially fragmented pallid sturgeon range in the upper Missouri River. However, freeflowing riverine conditions currently exist throughout the lower 2,000 mi (3218 km) (60%) of

the pallid sturgeon’s historical range (USFWS 2009). Until this past decade, they were

considered a rare occurrence in the Lower Mississippi. New information from recent collection

efforts indicates that the Mississippi River currently supports substantial numbers of wild fish.

Since 1997, more than 200 pallid have been collected at more than 60 locations in the

Mississippi River between the confluence of the Missouri River and New Orleans, LA (Bettoli,

2006). When listed, there were only 28 recognized records of pallid sturgeon from the

Mississippi River, with no recognized records from the Atchafalaya River (USFWS 2009).

Pallid sturgeon feed on a range of animals from aquatic insects to fish depending upon

life stage. Individuals of the species can be long lived with females reaching sexual maturity

later than males. Spawning is thought to take place in side channels and backwaters and appears

to occur between June and August. Larval fish produced from the spawning event drift

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downstream from the hatching site and begin to settle from the lower portion of the water

column 11 to 17 days post hatch. Although morphologically distinct pallid sturgeon as small as

450 mm FL are occasionally captured, some young-of-year and sub-adult pallid sturgeon may be

misidentified as shovelnose or hybrids (USFWS 2007). Although pallid sturgeon captures in the

middle and lower reaches of the Mississippi River continue to increase with fishing effort,

habitat use, population levels and trends, and movement patterns within this portion of the

species range remain unknown. Extensive sampling in the lower Mississippi River is currently

being undertaken by U.S. Army Corps of Engineers Engineering Research and Development

Center (ERDC) so that a better understanding of population size, population density, habitat

preference, extent of range in lower Mississippi River, and impacts from entrainment on the

population can be quantified.

Forbes and Richardson (1905), Schmulbach et al. (1975), Kallemeyn (1983), and

Gilbraith et al. (1988) describe pallid sturgeon as being a fish well-adapted to life on the bottom

in swift water of large, turbid, free-flowing rivers. Mayden and Kuhajda (1997) describe the

natural habitats to which pallid sturgeon are adapted as: braided channels, irregular flow patterns,

flooding of terrestrial habitats, extensive microhabitat diversity and turbid waters. The historic

floodplain habitat of the Missouri and Mississippi Rivers provided important functions for the

native large-river fish. Floodplains were the major sources of organic matter, sediments, and

woody debris for the main stem rivers when flood flows crested their banks. The transition zone

between the vegetated floodplain and the main channel included habitats with varied depths

described as chutes, sloughs, or side channels. The chutes or sloughs between the islands and

shore were shallower and hand less current than the main channel. These areas provided

valuable diversity to the fish habitat, and probably served as nursery and feeding areas for many

aquatic species (Funk and Rovinson 1974). The still waters in this transition zone allow organic

matter accumulations; important to macroinvertebrate production. Both shovelnose and pallid

sturgeon have a high incidence of aquatic invertebrates in their diet (Carlson et al. 1985; Gardner

and Stewart 1987). Flood flows connected those important habitats and allowed fish from the

main channel to utilize those habitat areas and to exploit available food sources (USFWS 2009).

Captures of pallid sturgeon in the Mississippi River have been associated with islands,

sand bars, gravel bars, and dikes, in both the main channel and in secondary channels (USFWS

2007). On April 4, 2008, one week prior to the 2008 opening of the Bonnet Carre Spillway,

personnel of the LDWF captured at least one pallid sturgeon in willow trees along the flooded

bank of the river adjacent the Spillway structure. Although no diagnostic measurements were

taken of the sturgeon, experts who have reviewed the photographic evidence have all concluded

that the fish was a pallid sturgeon. This capture represents a very rare capture of a pallid

sturgeon from the flooded riverbank of the river. Prior to this capture, pallid sturgeon were

generally believed to inhabit only the main river channel and side slopes, not overbank areas

during high-water events. It is not known if pallid sturgeon might also be found in grassy or

revetted areas. Dr. Jack Killgore, who is in charge of the ERDC’s sampling efforts, believes that

pallid sturgeon could be found over nearly any flooded habitat, if enough sampling effort was

expended, but they are more likely to be found in open water than in flooded willows. Currently

as part of the sampling effort being performed by ERDC habitat data is being collected to better

understand what habitat features are attracting the pallid sturgeon to swim up in the water

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column and to the flooded river banks which makes them more prone to entrainment by

diversion structures.

Genetic and morphological data have been used to differentiate pallid sturgeon into three

groupings, an upper Missouri River group and two less differentiated groups in the lower

Missouri/middle Mississippi and Atchafalaya River (USFWS 2007). This data suggest that the

genetic structuring within the pallid sturgeon’s range represents two distinct groups at the

extremes of the species range with a middle intermediate group representing the lower Missouri

and middle Mississippi Rivers. This pattern is suggestive of a pattern of isolation by distance,

with gene flow more likely to occur between adjacent groups than among geographically distant

groups, and thus, genetic differences increase with geographical distance.

Management and Protection

Aquatic habitats in the Mississippi River have been modified though the construction of

flood control levees and channel modification through time, and some changes resulting from

those modifications have likely been detrimental to pallid sturgeon (USFWS 2007). Although

the river flows unobstructed for about 2,000 river miles (RM) from Gavins Point Dam in the

middle Missouri River to the Gulf of Mexico, tributary impoundments, bendway cutoffs, and

dike and levee construction have each changed localized patterns of channel erosion and

deposition in the Mississippi River; collectively they resulted in a degradation trend throughout

the system. Effects of these changes on pallid sturgeon are unknown, because there are no

historical data for comparison. In 1981, the USACE established the Lower Mississippi River

Environmental Program, with a goal of protecting fisheries and other natural resources in the

lower Mississippi River (USFWS 2007). Input from the Lower Mississippi River Environmental

Program resulted in experimentations with dike placement and notches as measures to protect

secondary channels and maintain shallow water and fisheries habitats.

The Pallid Sturgeon Lower Basin Recovery Workgroup has identified information gaps

essential to the consultation and recovery processes in the Lower Mississippi River Basin. These

include: relative abundance of pallid sturgeon, demographics, feeding habits, habitat use,

hybridization ratios, presence of fish diseases in the wild, population anomalies, and reliable

separation and identification of pallid sturgeon, shovelnose sturgeon, and hybrids. While recent

publications have contributed to filling some of these data gaps (e.g., Killgore et al., 2007)

incomplete knowledge of those areas remains. Therefore, the sturgeons’ response and the effect

to encountering the diversion flows (e.g., avoidance, actively sought) is unknown, which can

affect the number of sturgeon believed to be “taken” by a structure’s operation. It is not know if

the number of sturgeon that risk entrainment within a diversion structure are; only those located

near the structure during its opening (no increase in sturgeon entrained because of active

avoidance); are sturgeon that actively swam into the structure seeking velocity refuge from mainchannel flows and/or seeking food sources on the batture and/or in a perceived secondary

channel (i.e., spillway); or are entrained during down-river migration passively (i.e., no

avoidance) or actively (i.e., failed to resist entrainment) or a combination of any of the above.

There are no known topographic or hydrographic features that would appear to attract the

sturgeon to the vicinity of the MDWD (USFWS 2009).

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Water diversions are used for flood control, water supply, and habitat restoration in the

lower Mississippi River (LMR) but their impacts on imperiled sturgeon populations are

unknown. Comprehensive risk assessments for entrainment of sturgeon by water diversions

require substantial inputs including field data on local sturgeon populations, life history

information, output from population modeling simulations, and results of experimental studies.

These risk assessments, however, can provide probability of entrainment for specific

environmental scenarios (e.g., time of year, river stage, and flow fields generated by a structure).

After the entrainment of 14 pallid sturgeon by a diversion structure was documented during the

2008 operation of the Bonnet Carre Spillway the USFWS tasked CEMVN with researching what

effect diversion structures might have on the pallid sturgeon. CEMVN tasked ERDC with

analyzing the effects and a scope of work (SOW) was prepared. The SOW provided details on

materials and methods of sampling, duration, etc. and was provided to the USFWS Lafayette, LA

office for review. The USFWS provided its comments on the SOW. Since this time ERDC has

contracted USFWS Fisheries Biologist’s from the Baton Rouge, LA office as well as Dr. Dave

Shultz from Nicholls State University to assist in sampling river sites within the vicinity of

existing and proposed diversion structures.

ERDC has documented numerous shovelnose and pallid sturgeon within two of the three

reaches of the Mississippi River with proposed or existing diversions, and trotline data provide

estimates of relative abundance among adjacent reaches (Table 1). No sturgeon have been

collected from RM 0-70, the reach including White’s Ditch and the proposed Myrtle Grove

diversion. Only four adult sturgeon have been collected from RM 70-100, the reach containing

Violet siphon and Caernarvon. Catch-per-unit-effort (CPUE) values for shovelnose sturgeon

(0.14/trotline) and pallid sturgeon (0.05/trotline) are low, compared to those previously

documented (1.88-5.41/trotline and 0.12-0.31/trotline, respectively) suggesting that densities are

substantially lower than elsewhere in the free-flowing Mississippi River (Killgore et al., 2007).

Over 150 sturgeon have been collected from RM 100-200, the reach including Davis Pond and

Bonnet Carre, and the proposed Convent/Blind River and Hope Canal projects. CPUE is

relatively low in this reach for shovelnose sturgeon (0.79/trotline) but high for pallid sturgeon

(0.32/trotline). More than 200 sturgeon have been collected from RM 200-300 where no

diversions are under consideration. CPUE is relatively high in this reach for shovelnose sturgeon

(6.0/trotline) and pallid sturgeon (0.25/trotline). Trawling data are less robust than trotline data

but support a longitudinal trend of greater sturgeon abundance upriver.

The data indicates entrainment risk by diversions to pallid sturgeon. Although catch rates

are comparatively low in the affected reaches, ratios of pallid sturgeon to shovelnose sturgeon

are high: 1:3 in RM 70-100, 1: 2.4 in RM 100-200. These ratios are substantially greater than

the 1:6 ratio documented previously for RM 154-502 and 1:16 to 1:36 ratios observed elsewhere

(Killgore et al., 2007). Young-of-year sturgeon, with weaker swimming abilities than adults

(Adams et al., 1997; Adams et al., 1999) also occur and will be at greater risk of entrainment. To

date, entrainment of pallid sturgeon has been documented for the Davis Pond diversion and

Bonnet Carre spillway.

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Table 1: Summary of effort and number of sturgeon collected from the Mississippi

River during the period 2001-2009.

River

Mile

Gear Times

Deployed

Number of

Shovelnose

sturgeon

Number of

Pallid sturgeon

Number of

Sturgeon yoy

0-70 Trotline 21 0 0 0

Trawl 21 0 0 0

70-100 Trotline 21 3 1 0

Trawl 10 0 0 2

100-200 Trotline 150 118 49

Trawl 46 1 0 5

200-300 Trotline 31 186 8 0

Trawl 16 11 1 5

Commercial take of any species of sturgeon was prohibited by Mississippi and Louisiana

during the early 1990s to avoid incidental take of pallid sturgeon. Although some poaching of

the species probably still occurs this value is not quantifiable. Other factors which threaten the

species include: predation, disease, contaminants, tug boat propeller entrainment, and

hybridization.

West Indian Manatee (Trichechus manatus)

Status

The West Indian manatee was listed as endangered throughout its range for both the

Florida and Antillean subspecies on June 2, 1970 and received Federal protection with the

passage of the ESA in 1973. Critical habitat was designated in 1976, 1994, 1998, 2002, and

2003 for the Florida subspecies.

Species and Habitat Description

The West Indian manatee is a large gray or brown aquatic mammal. Adults average

approximately 10 feet in length and weigh up to 2,200 pounds. They have no hind limbs, and

their forelimbs are modified as flippers. Manatee tails are flattened horizontally and rounded.

Their body is covered with sparse hairs and their muzzles with stiff whiskers (USFWS 2001).

The nostrils, located on the upper snout, open and close by means of muscular valves as the

animal surfaces and dives (Husar 1977, Hartman 1979). Manatees will consume any aquatic

vegetation (i.e., submerged, floating, and emergent) available to them and sometimes even

shoreline vegetation. Although primarily herbivorous, they will occasionally feed on fish.

Manatees may spend about 5 hours a day feeding, and may consume 4 to 9 percent of their body

weight per day.

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Observations of mating herds indicate that females mate with a number of males during

their 2- to 4-week estrus period, and then they go through a pregnancy estimated to last 12 to 14

months (O’Shea et al. 1992). Births occur during all months of the year with a slight drop during

winter months. Manatee cows usually bear a single calf, but 1.5 percent of births are twins.

Calves reach sexual maturity at 3 to 6 years of age. Mature females may give birth every 2 to 5

years (USFWS 2001).

Manatees inhabit both salt and freshwater of sufficient depth (5 feet to usually less than

20 feet) throughout their range. Shallow grassbeds with ready access to deep channels are

preferred feeding areas in coastal and riverine habitats (USFWS 2001). They may also be

encountered in canals, rivers, estuarine habitats, saltwater bays, and have been observed as much

as 3.7 miles off the Florida Gulf Coast. Between October and April, Florida manatees

concentrate in areas of warmer water. Severe cold fronts have been known to kill manatees

when the animals did not have access to warm water refuges. During warmer months they

appear to choose areas based on an adequate food supply, water depth, and proximity to fresh

water. Manatees may not need fresh water, but they are frequently observed drinking water from

hoses, sewage outfalls, and culverts.

During winter months, the United States’ manatee population confines itself to the

coastal waters of the southern half of peninsular Florida and to springs and warm water outfalls

as far north as southeast Georgia. Power plant and paper mill outfalls created most of the

artificial warm water refuges utilized by manatees. During summer months, they migrate as far

north as coastal Virginia on the east coast and the Louisiana coast in the Gulf of Mexico.

During summer months, manatees disperse from winter aggregation areas, and are

commonly found almost anywhere in Florida where water depths and access channels are greater

than 3.3 to 6.6 feet (O’Shea 1988). In the warmer months, manatees usually occur alone or in

pairs, although interacting groups of 5 to 10 animals are not unusual (USFWS 2001). A few

individuals have been known to stray as far north as the northern Georgia coast and as far west as

the coastal waters of Louisiana.

In the early 1980s, scientists tried to develop procedures for estimating the overall

manatee population in the southeastern United States (USFWS 2001). The best estimate

throughout the State of Florida was 1,200 manatees (Reynolds and Wilcox 1987). In the early

1990s, the State of Florida initiated a statewide aerial survey in potential winter habitats during

periods of severe cold weather (Ackerman 1995), and the highest count of 3,276 manatees was

recorded in January 2001. Manatees were reported in Lake Pontchartrain prior to the landfall of

Hurricane Katrina, however, there were no reports of manatee mortality following the hurricane.

Management and Protection

The most significant problem faced by manatees in Florida is death or injury from boat

strikes (USFWS 2001). Minimum flows and levels for warm water refuges need to be

established to ensure their long-term availability for manatees. Their survival will depend on

maintaining the ecosystems and habitat sufficient to support a viable manatee population

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(USFWS 2001). The focus of recovery is on implementing, monitoring, and addressing the

effectiveness of conservation measures to reduce or remove threats that will lead to a healthy and

self-sustaining population (USFWS 2001).

The West Indian manatee is also protected under the Marine Mammal Protection Act

(MMPA) of 1972. The MMPA establishes a national policy for the maintenance of health and

stability of marine ecosystems and for obtaining and maintaining optimum sustainable

populations of marine mammals. It includes a moratorium on the taking of marine mammals.

The recovery planning under the ESA includes conservation planning under the MMPA

(USFWS 2001).

Piping Plover (Charadrius melodus)

Status

The USFWS determined the piping

plover to be endangered and threatened on

December 11, 1985. Endangered status was

determined for the plover in the watershed of

the Great Lakes (Illinois, Indiana, Michigan,

Minnesota, New York, Ohio, Pennsylvania,

Wisconsin, and Ontario). It was determined

to be threatened in the remainder of its range:

northern Great Plains (Iowa, northwestern

Minnesota, Montana, Nebraska, North

Dakota, South Dakota, Alberta, Manitoba, and

Saskatchewan); Atlantic coast (Quebec,

Newfoundland, Maritime Provinces, and

states from Maine to Florida); Gulf coast

(Florida to Mexico); Bahamas; and West

Indies.

Species and Habitat Description

The piping plover is a shorebird that inhabits open beaches, alkali flats, and sandflats of

North America. It breeds primarily along the Atlantic coast from North Carolina to southern

Canada, along rivers and wetlands of the northern Great Plains from Nebraska to the southern

prairie provinces, and along portions of the western Great Lakes. In winter, most individuals are

found on coastal beaches and sand flats from the Carolinas to Yucatan; some scatter through the

Bahamas and West Indies. (Haig, 1992)

This plover is divided into two subspecies based on geographic distribution and presence

or absence of complete neck bands, although there is little support for this designation (Haig and

Oring 1988a). Numerous breeding studies have been conducted across the species range, yet

habitat requirements and limiting factors remain poorly known. Conservation efforts are well

Figure 4: Piping

Plover Range

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organized in breeding areas across North America, whereas little has been attempted in winter

areas.

Ideal wintering habitat for the piping plover on the Gulf of Mexico coast would contain

large sand flats or sand-mud flats adjacent to a tidal pass or tidal inlet (Haig 1985, Nicholls

1989). A thin layer of mud covering the sand seems to attract plovers, due to possible food or

refuge association (Nicholls 1989). Nicholls observed that barrier beaches with over wash areas

or sections of old marshes also attract plovers. A gulf-facing beach having a very low gradient,

thus an increased intertidal zone, offers an almost equally attractive area (Haig 1985). Also

piping plovers will inhabit spoil islands on the Gulf Intracoastal Waterway on both Atlantic and

Gulf Coasts. Birds are frequently associated with bays, lagoons and inlets. Winter 2001 census

observations were in the following habitat type: mudflats (36.3%), sandy beaches (33.2%),

sand/salt flats (23.1%) algal mats (2.8%), oyster reefs (1.0%) and gravel shores (0.1%; Haig

2004).

Foraging habitat in winter is fairly consistent among numerous Gulf and Atlantic coast

sites. On Dauphin Island, AL: protected mudflats or sandflats exposed at low tide; at Texas sites:

primarily bayshore sand and algal flats. Comparison among 36 Atlantic winter sites (222 birds

observed once each) and 75 Gulf sites (1,508 birds observed once each) indicates foraging

activity most often associated with mudflats (25.6% of observations), sandflats (25.1%), and

sandy mudflats (31.8%; Haige, 2004).

The historical breeding range in North America of the piping plover included the Atlantic

coastal beaches from Newfoundland to South Carolina; beaches of the Great Lakes; and the

northern Great Plains region from Alberta to Ontario and south to Nebraska (USFWS, 1988).

These populations were reported to winter along the Gulf of Mexico, the Atlantic coast from

North Carolina to Florida, eastern Mexico, and in the Caribbean Islands (Haig and Oring, 1985).

Approximately 35 percent of the total breeding piping plover population winters along the gulf

coast from Florida to Texas and represents 56 percent of the Great Lakes/Great Plains population

(Natureserve 2002, 2003).

All populations could potentially occur within the proposed action areas since it falls

within the wintering range of the species. They arrive from their northern breeding grounds as

early as late July and may be present for 8 to 10 months of the year. Inland breeders appear to

migrate nonstop to the Gulf of Mexico or Atlantic Coast. Great Lakes and Northern Plains birds

are rare at seemingly appropriate inland stopover places: Great Salt Plains National Wildlife

Refuge, OK, and Cheyenne Bottoms National Wildlife Refuge, KS (Haig, 1986). Existing

stopover records suggest that migration routes are predominantly south/southeast in the fall. In

fall, birds depart Massachusetts breeding sites by late August (Haig, 2004). Some Manitoba and

North Dakota, but others with nests hatching late July or early August stay into September.

Generally, females go first, then unpaired males, males with fledglings, followed by

unaccompanied juveniles. Peak return to Texas beaches is in August and September, although

small numbers may arrive as late as November. Adults may arrive before juveniles as early

captures in Texas were of adult birds (sex unknown) and juveniles were not recorded until early

November; however, since sample size was small further research is needed.

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Management and Protection

Hunting in the early 1900s resulted in a drastic reduction of the piping plover population.

Ongoing destruction of historical nesting sites further reduced plover populations (USFWS

1988). The primary causes for decline of this species are listed as habitat loss and degradation

and human disturbance. Loss of breeding habitat has resulted from recreation and commercial

development of sandy beaches on the Great Lakes, Atlantic Coast, and Gulf of Mexico. Where

breeding does occur on coastal beaches, inland lakes, and river sites, reproductive success has

been reduced by disturbance from humans and pets. Additional habitat has been lost due to

construction and operation of reservoirs and river channelization.

Dune stabilization projects that result in steep beach slopes, narrower beach widths, or

increased vegetation to the water’s edge, reduce piping plover habitat (Haig 1985). In at least

one instance, stabilization of the backside of the dune on Padre Island, Texas, resulted in the

destruction of essential sand flat habitat (USFWS ESIS). Additionally, increased urbanization

has led to an increase in predation on the piping plover population (USFWS 1988). Recreational

activities in localized areas along the gulf coast have been correlated with a decrease in piping

plover use of those areas (Nicholls 1989).

Habitat loss is a problem on both breeding and wintering grounds. It occurs when nesting

beaches or basins become unsuitable or unavailable to piping plovers through natural causes

such as drought, vegetation encroachment, tides and floods, as well as through activities such as

beach visitation, housing developments, cattle ranching and water management. Natural factors

will undoubtedly continue to be an unpredictable challenge for piping plover recovery in the

future, and habitat loss due to human activity will increase with demands for more resources,

recreation and living space, as the human population continues to grow (National Recovery

Plan).

Bald Eagle (Haliaeetus leucocephalus)

Status

The successful recovery of bald eagle populations within the continental United States

resulted in the delisting of the species from the Endangered Species List by the FWS on August

9, 2007. The bald eagle may nest in some of the remaining large cypress trees within the project

area. Though delisted, bald eagles and other raptors are still protected by the Bald and Golden

Eagle Protection Act and the Migratory Bird Treaty Act. Following the National Bald Eagle

Management (NBEM) Guidelines to minimize potential adverse impacts to bald eagles, a “nowork” distance would be established within 660 feet of any bald eagle nests occurring in the

project area, during the breeding season, from October 1 thru May 15. In addition, the Division

of Migratory Birds for the Southeast Region of the FWS would be contacted prior to start of

project activities to update the status of known bald eagle nests and to ascertain if any new nest

are discovered within or adjacent to the proposed disposal site. It is expected that the tentatively

proposed plan is not likely to adversely affect the bald eagle.

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Brown Pelican (Pelecanus occidentalis)

Status

The successful recovery of the brown pelican population within the continental United

States resulted in the delisting of the species from the Endangered Species List bye the FWS on

November 17, 2009. Though delisted, brown pelicans are still protected by the Migratory Bird

Treaty Act. The brown pelican is a year-round resident of Louisiana that typically forages on

fishes throughout the study area. This colonial nester has established a colony on Raccoon Point

on Isles Dernieres, Queen Bess Island, Plover Island (Baptiste Collette), Wine Island, and islands

in the Chandeleur chain. In winter, spring, and summer, nests are built in mangrove trees or

other shrubby vegetation, although occasional ground nesting may occur. Small coastal islands

and sand bars are typically used as loafing areas and nocturnal roosting areas. It is expected that

the tentatively proposed plan is not likely to adversely affect the brown pelican.

Colonial Nesting Birds

Status

Colonial nesting birds may nest in the area. Colonial nesting marine birds and wading

birds (waterbirds) share the characteristic of typically nesting in colonies. They represent several

orders of waterbirds, (i.e. cormorants, herons, egrets, ibises, gulls, terns, and skimmers) and are

important and conspicuous components of coastal ecosystems. With there tendency to nest in

colonies disturbance and habitat modifications can affect large numbers of them at one time.

Colonial nesting wading birds (including, but not limited to herons, egrets, and ibis) and

seabirds/waterbirds (including, but not limited to terns, gulls, black skimmers, and brown

pelicans) should be avoided to reduce the risk of injuring birds. The nesting activity period

generally extends from February 15 through September 15. No colonial nesting bird colonies are

known to exist in areas that would be directly affected by the proposed action. The lack of

suitable colonial nesting habitat within the directly affected area strongly suggests that no nesting

colonies would be affected. The Corps has standard procedures in place to investigate

construction sites for the presence of colonial nesting birds prior to project construction. With

these procedures in place, and the low probability of encountering colonial bird nesting sites, the

proposed action is not likely to adversely affect these species.

Effects of the Proposed Action

Pallid Sturgeon (Scaphirynchus albus)

Unpublished data suggests that a pallid sturgeon may have been captured in the past in

the Delta National Wildlife Refuge near the Head of Passes of the Mississippi River (Walther,

personal communication.). However, due to the similarities of pallid sturgeon and shovelnose

sturgeon, this record could be considered as questionable. Other than this account no pallid

sturgeon have been captured and identified within the reach of river that abuts the proposed

MDWD. ERDC’s current sampling effort has not yielded any pallid or shovelnose captures

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south of RM 70 to date. Since the MDWD is located at RM 64.5, the risk of entrainment by this

diversion structure is low. Though it may be possible for pallid sturgeon to inhabit the river as

far south as the proposed MDWD, the population there is likely small if not non-existent. It is

still plausible that a sturgeon feeding or otherwise occurring in the vicinity of the structure while

it is operating may unwittingly be swept through the structure without even trying to offer any

resistance, not realizing that once they go through the structure they cannot return on their own.

The species evolved in an environment where there were no waterfalls or other natural

obstructions that would have prevented upstream movement, no matter how far individual fish

were swept downstream. So it may be possible that pallid (and shovelnose) sturgeon have no

positive or negative rheotaxis in relation to anthropogenic structures such as the MDWD.

Research at ERDC has been conducted on burst and long-term swimming speeds of pallid and

shovelnose sturgeon. But, it is not known if the sturgeon’s swimming ability is really a factor in

the numbers that would be entrained during a diversion. Only the continuation of extensive field

studies will be able to shed light on this subject. Given the results of our current sampling effort,

CEMVN concludes that the risk to pallid sturgeon entrainment is low and that therefore the

proposed MDWD may affect, but is not likely to adversely affect the species.

West Indian Manatee (Trichechus manatus)

Sightings of the West Indian manatee in Louisiana have primarily occurred in Lakes

Pontchartrain and Maurepas, and associated coastal waters and streams (i.e., Amite, Blind,

Tchefuncte, and Tickfaw Rivers) and a few rare sightings along the Gulf coast during the

summer months (i.e., June through September); however, there is no known resident population

in the State. To avoid potential impacts to manatees during restoration activities the following

standard protective measures would be implemented;

• All contract personnel associated with the project should be informed of the potential

presence of manatees and the need to avoid collisions with manatees, which are protected

under the Marine Mammal Protection Act of 1972 and the Endangered Species Act of 1973.

• All construction personnel are responsible for observing water-related activities for the

presence of manatee(s).

• Temporary signs should be posted prior to and during all construction/dredging activities to

remind personnel to be observant for manatees during active construction/dredging operations

or within vessel movement zones (i.e., work area), and at least one sign should be placed

where it is visible to the vessel operator.

• Siltation barriers, if used, should be made of material in which manatees could not become

entangled, and should be properly secured and monitored.

• If a manatee is sighted within 100 yards of the active work zone, special operating conditions

should be implemented, including: no operation of moving equipment within 50 feet of a

manatee; all vessels shall operate at no wake/idle speeds within 100 yards of the work area;

and siltation barriers, if used, should be re-secured and monitored. Once the manatee has left

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the 100-yard buffer zone around the work area on its own accord, special operating conditions

are no longer necessary, but careful observations would be resumed.

• Any manatee sighting should be immediately reported to the U.S. Fish and Wildlife Service

(337/291-3100) and the Louisiana Department of Wildlife and Fisheries, Natural Heritage

Program (225/765-2821).

Also, to prevent entrapment of manatee inside of dredged material receiving areas that

have dikes or other retention features that enclose an area of open water, the area would be

inspected for the presence of manatee: 1) before complete closure of the confining features, and

2) again before material is discharged in to the receiving area. Any manatee that is sighted

should be allowed to leave the area before work resumes.

Adherence to the before mentioned protection measures will help ensure that any

manatee that wanders into the project area would not be adversely affected. The disturbance to

the manatee would only be temporary during project construction, and would result in temporary

displacement. The manatees would likely move to another area for foraging or resting purposes,

and there would be other available areas to which the animals may relocate. Since Louisiana has

no resident population of West Indian manatee and the protection measures will be adhered to, it

is expected that the proposed MDWD is not likely to adversely affect the species.

Piping Plover (Charadrius melodus)

During construction activities associated with the project any piping plover within the

area will be temporarily displaced. The proposed action will create 235 acres of marsh in areas

that are currently open water which will provide temporary foraging habitat for the Piping Plover

until the mud flats become vegetated. The placement of this material will expose marine worms,

mollusks, crustaceans and other small marine animals within the area allowing for easy foraging

access to plovers in the area. As the marsh becomes vegetated there is potential for an increase

in the number of mudflats within these areas that are presently open water. It is expected that the

proposed MDWD is not likely to adversely affect the species.

Conclusion

Based on currently available historical and catch data, a review of current literature and

studies, and with the employment of avoidance measures recommended through guidelines set

up during coordination with USFWS, the CEMVN, believes that pallid sturgeon, West Indian

manatees, and piping plover populations are not likely to be adversely affected from creation and

operation of the MDWD in the project location detailed in this assessment.

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Literature Cited

Ackerman, B.B. 1995. Aerial surveys of manatees: a summary and progress report. Pages 13-

33 in T.J. O’Shea, B.B. Ackerman, and H.F. Percival (eds.). Population Biology of the

Florida Manatee. National Biological Service, Information and Technology Report No.

1. Washington, D.C.

Forbes and Richardson (1905), Schmulbach et al. (1975), Kallemeyn (1983), and Gilbraith et al.

(1988).

Funk, J.L., and J.W. Robinson. 1974. Changes in the channel of the lower Missouri River and

effects on fish and wildlife. Missouri Department of Conservation, Aquatic Series No. 11.

Haig, S.M. 1985. The status of the Piping Plover in Canada. Report to the Committee on the

Status of Endangered Wildlife in Canada (COSEWIC), National Museum of Canada,

Ottawa, Ontario.

Haig, S.M. and J.H. Plissner. 1992. The 1991 international piping plover census. U.S. Fish and

Wildlife Service, Twin Cities, Minnesota. 200 pp.

Haig, S.M. 1986. Piping Plover distribution. Endangered Species Information System

Workbook Part 1. U.S. Fish and Wildlife Service, Washington D.C.

Haig, S.M. and L.W. Oring. 1988a. Genetic differentiation of piping plovers across North

America. Auk 105(4): 260-267pp.

Haig, Susan M., and Elliott-Smith, E. 2004. Piping Plover. The Birds of North America Online.

(A. Poole, Ed.) Ithaca: Cornell Laboratory of Ornithology; Retrieved from The Birds of

North American Online database:

http://bna.birds.cornell.edu/BNA/account/Piping_Plover/.

Hartman, D.S. 1979. Ecology and behavior of the manatee (Trichechus manatus) in Florida.

American Society of Mammalogists Special Publication No. 5. 153 pp.

Husar, S.L. 1977. The West Indian manatee (Trichechus manatus). U.S. Fish and Wildlife

Service. Wildlife Resource Report No. 7: 1-22.

Killgore, K.J., J.J. Hoover, J.P. Kirk, S.G. George, B.R. Lewis, and C.E. Murphy. 2007. Age

and growth of pallid sturgeon in the free-flowing Mississippi River. Journal of Applied

Ichthyology. 23:452-456.

Killgore, K.J., J.J. Hoover, S.G. George, B.R. Lewis, C.E. Murphy, and W.E. Lancaster. 2007.

Distribution, relative abundance and movements of pallid sturgeon in the free-flowing

Mississippi River. Journal of Applied Ichthyology. 23:476-483.

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Feasibility Study / SEIS

Mayden, R.L., and B.R. Kuhajda. 1997. Threatened fishes of the world: Scaphirhynchus albus

(Forbes and Richardson 1905) (Acipenseridae). Environmental Biology of Fishes 48:

420-421.

NatureServe. 2006. NatureServe Explorer: An online encyclopedia of life [web application].

Version 6.1. NatureServe, Arlington, Virginia. Available

http://www.natureserve.org/explorer.

Nicholls, J.L. 1989. Distribution and other ecological aspects of Piping Plovers (Charadrius

melodus) wintering along the Atlantic and Gulf coasts. MS Thesis. Auburn University,

Auburn, Alabama. 164 pp.

O’Shea, T.J. 1988. The past, present, and future of manatees in the southeastern United States:

realities, misunderstandings, and enigmas. Pages 184-204 in Odum, R.R., K.A.

Riddleberger, and J.C. Ozier (eds.). Proceedings of the Third Southeastern Nongame and

Endangered Wildlife Symposium. Georgia Department of Natural Resources. Social

Circle, Georgia.

O’Shea, T.J., B.B. Ackerman, and H.F. Percival (eds.). 1992. Interim report of the technical

workshop on manatee population biology. Manatee Population Research Report No. 10.

Florida Cooperative Fish and Wildlife Research Unit. Gainesville, Florida. 83 pp.

USFWS. 1988. Great Lakes and Northern Great Plains Piping Plover Recovery Plan. US Fish

and Wildlife Service, Twin Cities, MN. 160 pp.

USFWS. 2001. Florida manatee recovery plan. Southeast Region, U.S. Fish and Wildlife

Service, Atlanta, Georgia. 144 pp. + Appendices.

USFWS. 2007. Pallid Sturgeon (Scaphirhynchus albus) 5-year review summary and evaluation.

U.S. Fish and Wildlife Service, Bismarck, North Dakota. 120pp.

USFWS. 2009. Biological Opinion. 2008 Operation of the Bonnet Carre Spillway. US Fish and

Wildlife Service, Lafayette, LA.

USFWS. (n.d.) Endangered Species Information System (ESIS): Piping Plover (Charadrius

melodus).

USFWS. Walther, David, Lafayette, LA USFWS Office. personal communication.

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Biological Assessment

National Marine Fisheries Service

438
U.S. ARMY CORPS

OF ENGINEERS

NEW ORLEANS DISTRICT

September 2010

BIOLOGICAL ASSESSMENT for LCA - Medium Diversion at White Ditch

Prepared by: U.S. Army Corps of Engineers

New Orleans District

Lead Contact: Thomas Parker

U.S. Army Corps of Engineers, PD-RP

Physical Address:

7400 Leake Ave., Room 363

New Orleans, LA 70118

Mailing Address:

P.O. Box 60267

New Orleans, LA 70160-0267

Email: thomas.w.parker@usace.army.mil

Phone: (504) 862-2526

Fax: (504) 862-2088

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Table of Contents

Introduction..............................................................................................................................22

Threatened, Endangered, and Proposed Threatened or Endangered Species ..........................22

Critical Habitat.........................................................................................................................23

Previous Consultation ..............................................................................................................23

Purpose.....................................................................................................................................23

Location of the Proposed Action .............................................................................................24

Proposed Action.......................................................................................................................26

Species Description..................................................................................................................29

Gulf Sturgeon.....................................................................................................................29

Status............................................................................................................................29

Species and Habitat Description ..................................................................................29

Management and Protection ........................................................................................30

Green Sea Turtle ................................................................................................................32

Status............................................................................................................................32

Species and Habitat Description ..................................................................................32

Management and Protection ........................................................................................33

Kemp’s Ridley Sea Turtle..................................................................................................33

Status............................................................................................................................33

Species and Habitat Description ..................................................................................34

Management and Protection ........................................................................................35

Loggerhead Sea Turtle.......................................................................................................37

Status............................................................................................................................37

Species and Habitat Description ..................................................................................37

Management and Protection ........................................................................................38

Effects of the Proposed Action ................................................................................................39

Gulf Sturgeon.....................................................................................................................39

Green Sea Turtle ................................................................................................................40

Kemp’s Ridley Sea Turtle..................................................................................................40

Loggerhead Sea Turtle.......................................................................................................40

Conclusion ...............................................................................................................................41

Literature Cited ........................................................................................................................42

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Figures

Figure 1: Study Area Map........................................................................................................25

Figure 2: Proposed Medium Diversion at White Ditch ...........................................................27

Figure 3: Map of Proposed Medium Diversion at White Ditch...............................................28

Figure 4: Louisiana Estuarine Critical Habitat ........................................................................31

[Cover Photo: Existing siphon at White Ditch]

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Introduction

This Biological Assessment (BA) is submitted to the National Marine Fisheries Service

(NMFS) by the U.S. Army Corps of Engineers, New Orleans District (CEMVN) in order to

initiate formal consultation with NMFS regarding potential impacts to threatened and

endangered species from construction and operation of the LCA Medium Diversion at White

Ditch (MDWD) project. The following BA is promulgated in accordance with Section 7

(Interagency Consultation) of the Endangered Species Act of 1973, as amended (PL 93-205; 16

U.S.C. 1531 et. seq.). A separate BA has been prepared and will be submitted to the US Fish and

Wildlife Service for species under their purview, including the Pallid Sturgeon (Scaphirynchus

albus), West Indian Manatee (Trichechus manatus), and the Piping Plover (Charadrius melodus)

The purpose of this biological assessment is to evaluate the possible effects of the

proposed construction and operation of the MDWD project on threatened, endangered and

proposed threatened and endangered species and their critical habitats. Threatened, endangered

and proposed threatened and endangered species are managed under the authority of the Federal

Endangered Species Act (ESA) (PL 93-205, as amended). Under provisions of the ESA, Federal

agencies shall use their authorities to carry out programs for the conservation of listed species,

and shall insure any action authorized, funded, or implemented by the agency is not likely to: (1)

adversely affect listed species or designated critical habitat; (2) jeopardize the continued

existence of proposed species; or (3) adversely modify proposed critical habitat (16 USC 1536).

The species of concern that are known to inhabit the area are:

Threatened, Endangered, and Proposed Threatened or Endangered Species

Gulf Sturgeon (Acipenser oxyrhynchus desotoi), was listed as threatened on September

30, 1991 (56 FR 49653)

Green Sea Turtle (Chelonia mydas), was listed as threatened in U.S. waters, except for

the Florida breeding population which was listed as endangered, on July 28, 1978

(43 FR 32800 32811)

Kemp’s Ridley Sea Turtle (Lepidochelys kempii), was listed as endangered throughout its

range, on December 2, 1970 (35 FR, 18320)

Loggerhead Sea Turtle (Caretta caretta) was listed as threatened through out its range on

July 28, 1978 (43 FR 32800 32811)

The likelihood of encountering hawksbill or leatherback sea turtles in the project area is

so remote that those species are not included in this list of species. No further discussion of these

species will occur.

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Critical Habitat

No critical habitat is currently designated for any of the threatened, endangered, or

sensitive species within the project area.

Previous Consultation

There has been no coordination conducted for the proposed action described in this

document.

Purpose

This LCA Medium Diversion at White Ditch (MDWD) project is to help restore areas

where an altered supply and distribution of freshwater, lack of deltaic forming sediments, marsh

subsistence and human development in the White Ditch area have resulted in degraded and

unbalanced distribution of freshwater, brackish, and saltwater marsh habitats. Further, the

degradation of the existing marshes has made them more vulnerable to the range of Gulf storm

events; extreme and seasonal, resulting in accelerated degradation, altered hydrology and

changed salinity regimes.

Installation of the White Ditch diversion siphon was completed in 1963 with the

objective of enhancing muskrat and oyster habitat. In the absence of an outfall management plan,

the surrounding marsh received limited benefits from the diverted river water. Two 50-inch steel

pipes divert water from the Mississippi River through the White Ditch, into the Belair Canal and

then into the River aux Chenes, where it continues south and out of the project area. Usage of the

siphons was abandoned for many years and they degraded into a non-usable condition. The

siphons were recently refurbished and water was diverted into White Ditch as part of research

efforts.

Wetlands in the project area are deteriorating for several reasons: 1) subsidence, 2) lack

of sediment and nutrient deposition, 3) erosion via tidal exchange, 4) channelization, 5) saltwater

intrusion and 6) lack of freshwater. Recent hurricanes and tropical storms have also caused

significant damage to the project area. These activities have resulted in the loss of several

thousand acres of previously solid, vegetated marsh. Deterioration will continue unless

preventative measures are taken.

In the absence of supplemental freshwater and sediment from the Mississippi River,

subsidence, sea-level rise, wave erosion, and saltwater intrusion will continue to be problems.

Protection and enhancement of this area are dependent on providing a hydrologic and sediment

regime that minimizes the physiological stress to wetland vegetation from saltwater intrusion and

tidal energy and is conducive to the retention of locally provided freshwater and sediments

The historic geology of the project area indicates that the current course of the

Mississippi River has remained the same for the last 700 years and has directly influenced the

development of the entire area. The project area is located on the east side of the Mississippi

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River and was formed between two natural levee ridge systems, River aux Chenes on the east

and the Mississippi River on the west. There are also two unnamed bayou ridges found within

the project area. These ridges formed along the old natural bayous which were distributary

channels for the Mississippi River. These natural bayous once carried sediments and nutrients

into the project area during high river stages when the natural ridges were seasonally overtopped.

In the historical setting, floodwater from the river would recede and sediments and

nutrients would be deposited in the inter-distributary basins located between ridges. During

normal or low river stages the ridges along the distributary channels served like levees and

buffered the basin areas from the daily tidal influence. This buffering effect created a low energy

freshwater environment in the inter-distributary basins, forming deep organic soils. Drainage to

the area was provided by a high water event breaching the River aux Chenes ridge in the

southern part of the project area. This event caused the development of the Bayou Garelle

tributary channel.

The present day hydrology of the project area has been altered and no longer functions in

a historically natural pattern. Historically, water moved very slowly through the system.

Freshwater slowly exited the system through meandering pathways in the marsh and saltwater

was slow to intrude. Presently, changes in the marsh allow water to rapidly pass through the

system and saltwater is able to quickly intrude. The hydrologic balance within the marsh has

been disturbed due to the following man-made changes:

1. The Mississippi River can no longer overflow its banks into the project area due to the

Mississippi River protection levee. This has eliminated the introduction of freshwater

from the river and disrupted natural sediment deposition patterns.

2. Channels have been dredged through natural ridges which has increased drainage and

tidal exchange and exposed the soil to erosive forces.

This project was identified as a Near-term Critical Restoration Feature Recommended for

Study and Future Congressional Authorization in the LCA Main Report dated January 21, 2005.

In November 2007, the Water Resources Development Act of 2007 passed, authorizing this and

other projects from the LCA Main Report. The MDWD feasibility study is anticipated to result

in a Chief’s Report containing a recommended plan to construct a Mississippi River diversion in

the vicinity of White Ditch for the purposes of introducing freshwater, sediments, and nutrients

into the study area.

Location of the Proposed Action

The MDWD project study area is located in LCA Subprovince 1 in the Breton Sound

hydrologic basin in Plaquemines Parish, Louisiana (see figure 1). The boundary of the project

encompasses over 98,000 acres of intermediate to brackish intertidal wetland habitats that has

been heavily influenced by both man-made and natural processes. Channel construction,

subsidence, erosion, saltwater intrusion, and storm-related damages have all significantly altered

the natural environment, causing extensive losses of wetland habitats. The study area boundary

follows distinct landscape features beginning in the north with the confluence of the non-Federal

back levee and the forty-arpent canal, extending along the non-Federal back levee, the

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Mississippi River levee, the Federal back levee and along the left descending natural bank of the

Mississippi River to the west; past American Bay, California Bay, and through Breton Sound,

near Bay Gardene to the south; into and along River aux Chenes to the east, and back to the point

of beginning. The area has been significantly impacted by recent tropical storms and hurricanes

and is currently isolated from the effects of the Caernarvon freshwater diversion, located at the

northern end of the Breton Sound basin.

There are two discreet project locations that will be considered for the purposes of the

feasibility study: The area along the Mississippi River where a freshwater diversion structure

might be located; and the project area that could be influenced and benefited by the diverted

freshwater. The area of interest where a diversion structure could be located occurs on the left

descending bank of the Mississippi River, between White Ditch to the north (river mile 64.5) and

the community of Phoenix to the south (river mile 59.8). This 4.7 mile stretch is unique in that

there is no hurricane protection levee (back levee) on the marsh side that protects existing homes

and infrastructure from elevated water levels (tidal or storm surge). The Mississippi River levee

is the only flood protection structure that keeps river water from entering the project study area.

This situation minimizes the amount of infrastructure that could be affected by construction of a

diversion structure and allows for a broader array of measures to be considered in addressing

problems in the project area.

Figure 1: Study Area Map

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Proposed Action

The tentatively selected plan proposes the construction of a medium sized diversion

structure capable of diverting up to 35,000 cfs consisting of 10 15ft. x 15ft. box culverts with

hydraulic operated sluice gates, and constructing an outfall channel to carry fresh water and

sediment to the desired locations in the marsh. Additionally, there will be 32 acres of ridge and

terrace creation and 385 acres of marsh creation utilizing dredged material from an adjacent 223

acres of canal being reconfigured to convey freshwater, nutrient and sediments.

The current operating plan for the tentatively selected plan at the White Ditch Diversion

is limited to a diversion pulse of 35,000 cfs in March-April of each year, during the normal high

flow period of the Mississippi River, and a diversion of 1,000 cfs the rest of the year. This flow

rate may not be experienced over the full 60 day period. The proposed 35,000 cfs diversion will

be the largest man-made diverted flow for wetland building on the Lower Mississippi River, but

the one to two month duration will be a modifying factor. The diversion should approximate five

percent or less of the main channel flow for most years.

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Figure 2: Proposed Medium Diversion at White Ditch

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Figure 3: Map of Proposed Medium Diversion at White Ditch

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Species Descriptions

Gulf Sturgeon (Acipenser oxyrinchus desotoi)

Status

The Gulf sturgeon was Federally listed as threatened throughout its range on September

30, 1991 and is also listed as a threatened species in Louisiana. The present range of the species

extends from east of the Mississippi River in Louisiana east to the Suwannee River in Florida

(USFWS and NMFS 2003).

Species and Habitat Description

Gulf sturgeon are light brown to dark brown in color with a pale underside (USFWS &

Gulf States Marine Fisheries Commission, 1995). They have elongate, fusiform bodies covered

by naked skin imbedded with bony plates or scutes. The average adult Gulf sturgeon ranges in

size from 120-225 cm in length with an average weight between 35-320 lbs. The largest recorded

Gulf sturgeon was caught at Cow Horn Reef near the mouth of the Mississippi in September

1936. Its reported mass was 228.2 kg with a length of 274 cm (Reynolds, 1993). Size is

dependant on the individual’s gender, age, and spawning condition (USFWS, 1980; Huff, 1975).

Females live longer than males and continue to grow with age, consequently they are larger and

weigh more than males (Huff, 1975). Females reach sexual maturity between 8 and 17 years of

age while males reach sexual maturity between the ages of 7 to 21 (Huff, 1975). Gulf sturgeon

are long lived, having the possibility of reaching at least 42 years old (Huff, 1975).

Gulf sturgeon live in the estuaries and coastal shelf regions of the Gulf of Mexico during the

cooler months from October to March. In March and early April, adult sturgeon start their

migration into the freshwater rivers in search of spawning habitat. Non-ripe adults, juveniles and

subadults also participate in this yearly migration, but usually lag behind the spawning adults,

moving into the rivers anywhere from days to months later. Sexually mature, ripe males and

females enter the rivers when the surface water temperatures reach 62-70o F (Carr, Tatman, &

Chapman, 1996). Fox et al. (2002), in their studies of Gulf sturgeon in the Choctawhatchee Bay,

found that male sturgeon enter the river earlier than female sturgeon and move greater distances

upstream. Males were also found to remain at the spawning grounds longer than females. Ripe

specimens of both sexes entered the Choctawhatchee River earlier and moved significantly

further upstream than non-ripe fish. After spawning, both males and females return to the lower

river reaches and join their non-spawning counterparts in summer holding areas where they

reside until the fall migration. After hatching, age-0 fish remain in riverine habitats through

January, moving into the estuaries in February as age-1 fish (Sulak et al., 1998).

Fall migration after spawning and river temperatures drive the return of sturgeon to the

Gulf of Mexico. When river temperatures approximate the fall temperatures of the Gulf of

Mexico (usually in late October or early November), and surface temperatures drop between 62-

72o F, sturgeon leave the rivers (Chapman, 2001; Foster & Clugston, 1997) for their winter

marine habitats. Sulak et al. (1999) reported that adult Gulf sturgeon in the Suwannee River

spend up to several weeks of pre-migratory staging (late November to early December) in the

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lower river and adjacent estuary. While it has been suggested that this kind of holding pattern

prior to the sturgeon’s movement between fresh and saline environments may be necessary due

to osmoregulatory functions (Murphy & Skaines, 1994), some rivers, like the Pearl River, report

sturgeon moving through the river/bay interface rapidly, requiring little if any time for

acclimatization (Howard Rogillio, LDWF personal communication). Altinok et al. (1998)

determined that, by age one, Gulf sturgeon have developed an active mechanism for

osmoregulation and ion balance in euryhaline environments.

Distribution of Gulf sturgeon in Louisiana extends from the Mississippi River east to the

Pearl River. The majority of these sturgeon have their origins in the Pearl River system, where

the largest population occurs. However, Gulf sturgeon have historically inhabited many of the

larger tributaries east of the Mississippi River, including some upstream of the Ross Barnett Dam

(Morrow et al., 1996). As a result of the channelization of the Mississippi River through its

extensive lock and levee system, any spawning habitat that may have existed in the Mississippi

River for Gulf sturgeon has since been severely degraded. There is no evidence indicating a

reproducing population in this river and no verified captures of Gulf sturgeon have occurred in

the Mississippi River. The movements of foraging sturgeon along the coast may occasionally

place them in the vicinity of the mouth of the Mississippi. At present there is no critical habitat

identified in this area for Gulf sturgeon.

The Gulf sturgeon, Acipenser oxyrinchus desotoi (Vladykov, 1955), is a separate

subspecies of the Atlantic sturgeon, Acipenser oxyrinchus oxyrinchus. Gulf sturgeon differ from

their Atlantic counterparts in relative head length, pectoral fin lengths, dorsal scute shape, as well

as spleen length and position. In 1996, Ong et al. presented genetic evidence that Atlantic and

Gulf sturgeon are different species using direct sequence analysis of the mitochondrial DNA

control region. Gulf sturgeon are anadromous fish (migrating seasonally between fresh and

saltwater) that range primarily from the Suwannee River in Florida to the Mississippi River in

Louisiana (Morrow et al, 1996). Their distribution is limited to the Gulf of Mexico by the

emergence of peninsular Florida, which led to the development of the separate species. This

speciation is maintained by the thermal barrier of the Gulf Stream around south Florida (Huff,

1975). Similarly, the Mississippi River also appears to limit their movements in the Gulf of

Mexico to east of the Mississippi River.

Management and Protection

Historically, Gulf sturgeon have supported both commercial and recreational fisheries

throughout most of their range from the Mississippi River east to Tampa Bay (U.S. Commission

of Fish and Fisheries, 1902, cited in Wooley and Crateau, 1985). Large-scale exploitation of Gulf

sturgeon began around 1860, when it was discovered that smoked sturgeon could be substituted

for smoked halibut and that Gulf sturgeon eggs could be made into high-quality caviar (Smith,

1990). Sturgeon have been harvested with gillnets, pound nets, otter trawls, harpoons, trammel

nets, weirs, stake row nets, and seines (Huff, 1975; Smith, 1985; Van Den Avyle, 1984; Smith &

Clugston, 1997). Gulf sturgeon populations have declined due to fisheries over-exploitation

(Barkuloo, 1988), spawning habitat loss via dam construction, and deterioration of water quality

in their natal rivers (Morrow et al., 1996). Sturgeon are particularly vulnerable to gill net

fisheries and are also found in the bycatch of shrimp trawls. Turtle excluder devices (TEDs) are

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thought to reduce sturgeon bycatch, though, to date no studies have been conducted to

specifically evaluate this possibility. Even though sturgeon fishing regulations are in place,

poaching of Gulf sturgeon still occurs (Collins et al., 2000). Restrictions applied to the sturgeon

fisheries have not resulted in the restoration of population size. This may be due to the reduction

of suitable spawning habitat. Poss (1998) notes that dredging operations reduce the deeper holes

and hard substrate sturgeon require for spawning. Dams and low water sills prevent the

movement of spawning adults to traditional spawning grounds. Low dissolved oxygen levels

from eutrophication also contribute to spawning habitat degradation. Adults and subadults are

not greatly affected by changes in salinity, dissolved oxygen, or high temperatures, however,

eggs and larval stages of the sturgeon have low tolerance ranges for these criteria (Collins et al.,

2000).

On March 19, 2003, the USFWS and NOAA Fisheries published a final rule in the

Federal Register (Volume 68, No. 53) designating critical habitat for the Gulf sturgeon in

Louisiana, Mississippi, Alabama, and Florida. Portions of the Pearl and Bogue Chitto Rivers,

Lake Pontchartrain east of the Lake Pontchartrain Causeway, all of Little Lake, The Rigolets,

Lake St. Catherine, and Lake Borgne within Louisiana were included in that designation, see

Figure 4. The proposed MDWD falls well outside of this habitat designation. None of the

primary constituent elements that are necessary to ensure the survival of the species currently

exist within the proposed project area. With the implementation of the project, improvements in

the hydrology and habitat within the area may begin to support some of these functions and

possibly may improve habitat on the eastern Louisiana coast.

Figure 4: Louisiana Estuarine Critical Habitat

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Green Sea Turtle (Chelonia mydas)

Status

The green sea turtle was listed as threatened in U.S. waters, except for the Florida

breeding population which is listed as endangered, on July 28, 1978. Due to the inability to

distinguish between these populations away from the nesting beach, green turtles are considered

endangered wherever they occur in U.S. waters. Commercial harvest, habitat degradation, coastal

development, disease, and predation have all contributed to the decline of the species.

Species and Habitat Description

The green sea turtle is one of the largest marine turtles with adult weights averaging

between 250 to 450 pounds (Dundee 1989). This species can live upwards of 50 years and

usually reaches sexual maturity between ages 20-50 years. The green sea turtle is considered to

be unique in regards to other sea turtles in that it is mostly herbivorous in its adult stage typically

feeding on underwater vegetation and algae (NOAA-1). On occasion, adult green sea turtles have

been known to eat carrion and other marine invertebrates such as jellyfish (LDWF-2 & Dundee

1989). During the yearling stages, the species lives in and around offshore areas and its diet is

primarily carnivorous (NOAA-1). In the Atlantic and Gulf of Mexico waters, the green sea turtle

typically inhabits areas adjacent to the coastline and has been known to have a range spanning

from Texas to as far north as Massachusetts. There are three types of environments that this

species is known to inhabit: oceanic beaches generally used for nesting; convergence zones in

the open ocean; and benthic feeding grounds in coastal areas (NOAA-1). In 1998, critical habitat

for this species was designated in and around the Culebra Islands, which are situated off the

eastern coast of Puerto Rico (NMFS 1998). One of the greatest impacts to this species has been

the harvest of eggs, juveniles and adults on both nesting and feeding grounds. Additional threats,

specifically in the U.S., include the erosion of the coastline and the barrier islands, which results

in the loss of suitable habitat for this species (LDWF-2). Fishing and dredging operations,

specifically hopper-type dredges, have also adversely impacted this species throughout the years.

In the western Atlantic, several major nesting assemblages have been identified and

studied (Peters, 1954; Carr and Ogren, 1960; Parsons, 1962; Pritchard, 1969; Carr et al., 1978).

In the continental United States, green turtle nesting occurs on the Atlantic coast of Florida

(Ehrhart, 1979). Occasional nesting has been documented along the Gulf coast of Florida, at

Southwest Florida beaches, as well as the beaches on the Florida Panhandle (Meylan et al.,

1995). Most documented green turtle nesting activity occurs on Florida index beaches, which

were established to standardize data collection methods and effort on key nesting beaches. The

pattern of green turtle nesting shows biennial peaks in abundance, with a generally positive trend

during the six years of regular monitoring since establishment of the index beaches in 1989,

perhaps due to increased protective legislation throughout the Caribbean (Meylan et al., 1995).

While nesting activity is obviously important in identifying population trends and

distribution, the majority portion of a green turtle's life is spent on the foraging grounds. Green

turtles are herbivores, and appear to prefer marine grasses and algae in shallow bays, lagoons and

reefs (Rebel, 1974). Some of the principal feeding pastures in the Gulf of Mexico include inshore

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south Texas waters, the upper west coast of Florida and the northwestern coast of the Yucatan

Peninsula. Additional important foraging areas in the western Atlantic include the Indian River

Lagoon System in Florida, Florida Bay, the Culebra archipelago and other Puerto Rico coastal

waters, the south coast of Cuba, the Mosquito coast of Nicaragua, the Caribbean coast of

Panama, and scattered areas along Colombia and Brazil (Hirth, 1971). The preferred food

sources in these areas are Cymodocea, Thalassia, Zostera, Sagittaria, and Vallisneria (Babcock,

1937; Underwood, 1951; Carr, 1952; 1954).

Management and Protection

Green turtles are distributed circumglobally, mainly in waters between the northern and

southern 20oC isotherms (Hirth, 1971). Green turtles were traditionally highly prized for their

flesh, fat, eggs, and shell, and fisheries in the United States and throughout the Caribbean are

largely to blame for the decline of the species. Green turtles were once abundant enough in the

shallow bays and lagoons of the Gulf to support a commercial fishery, which landed over one

million pounds of green turtles in 1890 (Doughty, 1984). Doughty (1984) reported the decline in

the turtle fishery throughout the Gulf of Mexico by 1902. Currently, green turtles are uncommon

in offshore waters of the northern Gulf, but abundant in some inshore embayments. Shaver

(1994) live-captured a number of green turtles in channels entering into Laguna Madre, in south

Texas. She noted the abundance of green turtle strandings in Laguna Madre inshore waters and

opined that the turtles may establish residency in the inshore foraging habitats as juveniles.

Algae along the jetties at entrances to the inshore waters of south Texas was thought to be

important to green turtles associated with a radio-telemetry project (Renaud et al., 1995).

Transmitter-equipped turtles remained near jetties for most of the tracking period. This project

was restricted to late summer months, and therefore may reflect seasonal influences. Coyne

(1994) observed increased movements of green turtles during warm water months.

In the Southeast United States, major nest protection efforts and beach habitat protection

are underway for most of the significant nesting areas, and significant progress has been made in

reducing mortality from commercial fisheries in U.S. waters with the enforcement of TED

regulations. Many coastal counties and communities in Florida have developed lighting

ordinances to reduce hatchling disorientations. Important U.S. nesting beaches have been and

continue to be acquired for long-term protection. The Fish and Wildlife Service and National

Marine Fisheries Service have been funding research on the fibropapilloma disease for several

years to expand our knowledge of the disease with the goal of developing an approach for

remedying the problem. Due to the long range migratory movements of sea turtles between

nesting beaches and foraging areas, long-term international cooperation is absolutely essential

for recovery and stability of nesting populations (USFWS North Florida Fact Sheet).

Kemp’s Ridley Sea Turtle (Lepidochelys kempii)

Status

The Kemp’s ridley sea turtle was listed as endangered throughout its range on December

2, 1970. Commercial harvest, habitat degradation, coastal development, disease, and predation

have all contributed to the decline of the species.

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Species and Habitat Description

Of the seven extant species of sea turtles of the world, the Kemp's ridley has declined to

the lowest population level. Kemp’s ridleys nest in daytime aggregations known as arribadas,

primarily at Rancho Nuevo, a stretch of beach in Mexico. Most of the population of adult

females nest in this single locality (Pritchard, 1969). When nesting aggregations at Rancho

Nuevo were discovered in 1947, adult female populations were estimated to be in excess of

40,000 individuals (Hildebrand, 1963). By the early 1970s, the world population estimate of

mature female Kemp's ridleys had been reduced to 2,500-5,000 individuals. The population

declined further through the mid-1980s. Recent observations of increased nesting, suggest that

the decline in the ridley population has stopped, and there is cautious optimism that the

population is now increasing.

The Kemp’s ridley sea turtle is the smallest of the sea turtles with adults reaching an

approximate length of 2 to 2 1⁄2 feet and weighing around 110 pounds (Dundee 1989). This

species has a single claw located on its front flippers and usually has one to two claws located on

its rear flippers (NOAA-3). The species’ is carnivorous and usually feeds upon crabs, clams, and

snails that inhabit the shallow coastal waters (Dundee 1989). During the months of May to

October, this species can be found in and around the shore line of Louisiana with adults

occupying areas around the mouth of Mississippi during the spring and summertime. As winter

approaches, adults and juveniles generally head to warmer waters offshore. The Kemp’s Ridley

sea turtle’s habitat is comprised of warm bays, coastal waters, sea grass beds, and sandy beaches

utilized for nesting (LDWF-4). This species has been observed within the Sabine and Calcasieu

Lakes as well as in Lake Borgne and areas around St. Bernard Parish (Dundee 1989). Similar to

other sea turtles, threats to this species include the harvest of eggs and nesting adults, incidental

trapping in fishing nets, and loss of suitable habitat. It has been suggested that sea turtles may

burrow into the estuarine mud along the Gulf coast during the winter, essentially when water

temperatures are too low for normal activity, but no dormant sea turtles have been reported in

coastal Louisiana.

The nearshore waters of the Gulf of Mexico are believed to provide important

developmental habitat for juvenile Kemp's ridley and loggerhead sea turtles. Ogren (1988)

suggests that the Gulf coast, from Port Aransas, Texas, through Cedar Key, Florida, represents

the primary habitat for subadult ridleys in the northern Gulf of Mexico. Stomach contents of

Kemp's ridleys along the lower Texas coast had a predominance of nearshore crabs and

mollusks, as well as fish, shrimp and other foods considered to be shrimp fishery discards

(Shaver, 1991). Analyses of stomach contents from sea turtles stranded on upper Texas beaches

apparently suggest similar nearshore foraging behavior (Plotkin, pers. comm.).

Research being conducted by Texas A&M University at Galveston has resulted in the

intentional live-capture of 516 sea turtles from 1991-1997. Green turtles comprise over 95% of

all sea turtle captures recorded by Texas A&M researchers from South Padre/Laguna Madre

studies. Conversely, the Kemp’s ridley dominates (92.2%) captures from more turbid, blue-crab

laden waters of the upper Texas and Louisiana coasts. Capture statistics readily justify Sabine

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and Calcasieu Passes being considered “index habitat” for the Kemp’s ridley (Landrey et al.,

1997).

The Texas A&M University research has resulted in the live-capture of 100s of Kemp’s

ridleys at Sabine Pass and the entrance to Galveston Bay. Between 1989 and 1993, 50 of the

Kemp's ridleys captured were tracked by biologists with the NMFS Galveston Laboratory using

satellite and radio telemetry. The tracking study was designed to characterize sea turtle habitat

and to identify small and large scale migration patterns. Preliminary analysis of the data

collected during these studies suggests that subadult Kemp's ridleys stay in shallow, warm,

nearshore waters in the northern Gulf of Mexico until cooling waters force them offshore or

south along the Florida coast (Renaud, NMFS Galveston Laboratory, pers. comm.).

Seasonal abundance of sea turtles utilizing nearshore waters of the northwest Gulf of

Mexico varies with species and location. Kemp’s ridleys are transient users of the coastal zone

who venture toward tidal passes and into bays during May-August when food sources and other

environmental factors are favorable. The May-August period has yielded over 80% of the sea

turtle captures (N=516) recorded by Texas A&M researchers, over 75% of which were Kemp’s

ridleys (Landry et al., 1997).

Management and Protection

The recent nesting increase can be attributed to full protection of nesting females and

their nests in Mexico, and the requirement to use turtle excluder devices in shrimp trawls both in

the United States and Mexico. In 1966, conservation efforts for the Kemp’s ridley were initiated

on the beach near Rancho Nuevo in Tamaulipas, Mexico. This locale is the only place in the

world where large nesting aggregations of this sea turtle were and are known to occur. From

1966 to 1987, conservation efforts focused on the area of Rancho Nuevo with one turtle

protection camp. In 1978, the U.S. joined with Mexico at Rancho Nuevo in a bi-national effort to

prevent the extinction of the Kemp’s ridley. In 1988, this bi-national program expanded to the

south and another camp was added. In 1989, a third camp was established when the program was

expanded to the north of Rancho Nuevo. By 1997, a total of seven camps had been established

along the Tamaulipas and Veracruz coasts to allow for increased nest protection efforts (USFWS

North Florida Fact Sheet).

The Mexico government also prohibits harvesting and is working to increase the

population through more intensive law enforcement, by fencing nest areas to diminish natural

predation, and by relocating all nests into corrals to prevent poaching and predation. While

relocation of nests into corrals is currently a necessary management measure, this relocation and

concentration of eggs into a "safe" area is of concern since it makes the eggs more susceptible to

reduced viability due to movement-induced mortality, disease vectors, catastrophic events like

hurricanes, and marine predators once the predators learn where to concentrate their efforts

(USFWS North Florida Fact Sheet).

In recent years, unprecedented numbers of Kemp's ridley carcasses have been reported

from Texas and Louisiana beaches during periods of high levels of shrimping effort. NMFS

established a team of population biologists, sea turtle scientists, and managers, known as the

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Expert Working Group (EWG) to conduct a status assessment of sea turtle populations. Analyses

conducted by the group have indicated that the Kemp’s ridley population is in the early stages of

recovery; however, strandings in some years have increased at rates higher than the rate of

increase in the Kemp’s population (Expert Working Group, June 1996). While many of the

stranded turtles observed in recent years in Texas and Louisiana are believed to have been

incidentally taken in the shrimp fishery, other sources of mortality exist in these waters. These

stranding events illustrate the vulnerability of Kemp's ridley and loggerhead turtles to the

impacts of human activities in nearshore Gulf of Mexico waters.

The EWG developed a population model to evaluate trends in the Kemp’s ridley

population through the application of empirical data and life history parameter estimates chosen

by the EWG. Model results identified three trends in benthic immature Kemp’s ridleys. Benthic

immatures are those turtles that are not yet reproductively mature but have recruited to feed in

the nearshore benthic environment, where they are available to nearshore mortality sources that

often result in strandings. Benthic immature ridleys are estimated to be 2-9 years of age and 20-

60 cm in length. Increased production of hatchlings from the nesting beach beginning in 1966

resulted in an increase in benthic ridleys that leveled off in the late 1970s. A second period of

increase followed by leveling occurred between 1978 and 1989 as hatchling production was

further enhanced by the cooperative program between the USFWS and Mexico’s Instituto

Nacional de Pesca (INP) to increase the nest protection and relocation program in 1978. A third

period of steady increase, which has not leveled off to date, has occurred since 1990 and appears

to be due to the greatly increased hatchling production and an apparent increase in survival rates

of immature turtles beginning in 1990 due, in part, to the introduction of TEDs. Adult ridley

numbers have now grown from a low of approximately 1,050 adults producing 702 nests in

1985, to greater than 3,000 adults producing 1940 nests in 1995 and about 3,425 nests in 1998.

The EWG was unable to estimate the total population size and current mortality rates for

the Kemp’s ridley population. However, they listed a number of preliminary conclusions. They

indicated that the Kemp's ridley population appears to be in the early stage of exponential

expansion. Over the period 1987 to 1995, the rate of increase in the annual number of nests

accelerated in a trend that would continue with enhanced hatchling production and the use of

TEDs. Nesting data indicated that the number of adults declined from a population that produced

6,000 nests in 1966 to a population that produced 924 nests in 1978 and a low of 702 nests in

1985. This trajectory of adult abundance tracks trends in nest abundance from an estimate of

9,600 in 1966 to 1,050 in 1985. The EWG estimated that in 1995 there were 3,000 adult ridleys.

The increased recruitment of new adults is illustrated in the proportion of neophyte, or first time

nesters, which has increased from 6% to 28% from 1981 to 1989 and from 23% to 41% from

1990 to 1994. The EWG’s population model projected that Kemp’s ridleys could reach the

intermediate recovery goal identified in the Recovery Plan, of 10,000 nesters by the year 2020 if

the assumptions of age to sexual maturity and age specific survivorship rates plugged into their

model are correct. They determined that the data they reviewed suggested that adult Kemp's

ridley turtles were restricted somewhat to the Gulf of Mexico in shallow near shore waters, and

benthic immature turtles of 20-60 cm straight line carapace length are found in nearshore coastal

waters including estuaries of the Gulf of Mexico and the Atlantic.

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The EWG identified an average Kemp’s ridley population growth rate of 13% per year

between 1991 and 1995. Total nest numbers have continued to increase. However, the 1996 and

1997 nest numbers reflected a slower rate of growth, while the increase in the 1998 nesting level

has been much higher. The population growth rate does not appear as steady as originally

forecasted by the EWG, but annual fluctuations, due in part to irregular internesting periods, are

normal for other sea turtle populations.

The area surveyed for ridley nests in Mexico was expanded in 1990 due to destruction of

the primary nesting beach by Hurricane Gilbert. The EWG assumed that the increased nesting

observed particularly since 1990 was a true increase, rather than the result of expanded beach

coverage. Because systematic surveys of the adjacent beaches were not conducted prior to 1990,

there is no way to determine what proportion of the nesting increase documented since that time

is due to the increased survey effort rather than an expanding ridley nesting range. As noted by

the EWG, trends in Kemp’s ridley nesting even on the Rancho Nuevo beaches alone suggest that

recovery of this population has begun but continued caution is necessary to ensure recovery and

to meet the goals identified in the Kemp’s ridley Recovery Plan.

Loggerhead Sea Turtle (Caretta caretta)

Status

The Loggerhead sea turtle was listed as endangered throughout its range on July 28,

1978. Commercial harvest, habitat degradation, coastal development, disease, and predation have

all contributed to the decline of the species.

Species and Habitat Description

The threatened loggerhead is the most abundant species of sea turtle occurring in U.S.

waters. The nearshore waters of the Gulf of Mexico are believed to provide important

developmental habitat for juvenile loggerheads. Studies conducted on loggerheads stranded on

the lower Texas coast (south of Matagorda Island) have indicated that stranded individuals were

feeding in nearshore waters shortly before their death (Plotkin et al., 1993).

The loggerhead sea turtle is also one the larger marine turtles with average adult lengths

ranging from 3 to 7 feet and weighing approximately 300 to 1,100 pounds (Dundee 1989). This

species usually reaches sexual maturity around age 35 and mating in the southeastern U.S. can

occur between late March and early June. The habitat for loggerheads consists of three different

zones throughout their lifetime: terrestrial zone, oceanic zone, and near shore or neritic zone

(NOAA-5). The lifecycle of the loggerhead, from hatchling to adult, begins when hatchlings

leave the ocean beach nesting site and migrate towards waters consisting of seaweed and sea

grass cover. The juveniles head into the neritic zone during the ages of 7 to 12 and remain there

maturing into adulthood. Coastal Areas not only provide an excellent food source for adults

inhabiting the area, but they also allow for easy access to migratory routes (NOAA-5). Large

nesting populations have been recorded along the coastal islands of the North and South

Carolinas, Georgia, and the Gulf coasts of Florida. In Louisiana, this species has been found

nesting on the Chandeleur Islands and Grand Isle in Terrebonne Parish (Dundee 1989). Threats

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to this species are fairly similar to threats posed other species of sea turtles, which include

incidental trapping in fishing nets, coastal erosion resulting in loss of nesting habitat, and

harvesting of eggs and juveniles (NOAA-5 & LDWF-6).

Management and Protection

In the Southeast United States, major nest protection efforts and beach habitat protection

are underway for most of the significant nesting areas, and significant progress has been made in

reducing mortality from commercial fisheries in U.S. waters with the enforcement of TED

regulations. Many coastal counties and communities in Florida, Georgia, and South Carolina

have developed lighting ordinances to reduce hatchling disorientations. Important U.S. nesting

beaches have been and continue to be acquired for long-term protection. The migratory nature of

loggerheads severely compromises these efforts once they move outside U.S. waters, however,

since legal and illegal fisheries activities in some countries are causing high mortality on

loggerhead sea turtle nesting populations of the western north Atlantic region. Due to the long

range migratory movements of sea turtles between nesting beaches and foraging areas, long-term

international cooperation is absolutely essential for recovery and stability of nesting populations

(USFWS North Florida Fact Sheet).

The EWG identified four nesting subpopulations of loggerheads in the western North

Atlantic based on mitochondrial DNA evidence. These include: (1) the Northern Subpopulation

producing approximately 6,200 nests/year from North Carolina to Northeast Florida; (2) the

South Florida Subpopulation occurring from just north of Cape Hatteras on the east coast of

Florida and extending up to Naples on the west coast and producing approximately 64,000

nests/year; (3) the Florida Panhandle Subpopulation, producing approximately 450 nests/year;

and (4) the Yucatan Subpopulation occurring on the northern and eastern Yucatan Peninsula in

Mexico and producing approximately 1,500-2,000 nests/year.

Genetic analyses of benthic immature loggerheads collected from Atlantic foraging

grounds identify a mix of the east coast subpopulations that is disproportionate to the number of

hatchlings produced in these nesting assemblages. Although the northern nesting subpopulation

produces only approximately 9% of the loggerhead nests, loggerheads on foraging grounds from

the Chesapeake Bay to Georgia are nearly equally divided in origin between the two

subpopulations (Sears, 1994; Sears et al., 1995; Norrgard, 1995). Of equal interest, 57% of the

immature loggerheads sampled in the Mediterranean were from the South Florida Subpopulation,

while only 43% were from the local Mediterranean nesting beaches (Laurent et al., 1993;

Bowen, 1995). Genetic work has not yet been done on nesting or foraging loggerheads in the

Gulf of Mexico.

The EWG considered nesting data collected from index nesting beaches to index the

population size of loggerheads and to consider trends in the size of the population. They

constructed total estimates by considering a ratio between nesting data (and associated estimated

number of adult females and therefore adults in nearshore waters), proportion of adults

represented in the strandings, and in one method, aerial survey estimates. These two methods

indicated that for the 1989-1995 period, there were averages of 224,321 or 234,355 benthic

loggerheads, respectively. The EWG listed the methods and assumptions in their report, and

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suggested that these numbers are likely underestimates. Aerial survey results suggest that

loggerheads in U.S. waters are distributed in the following proportions: 54% in the southeast

U.S. Atlantic, 29% in the northeast U.S. Atlantic, 12% in the eastern Gulf of Mexico, and 5% in

the western Gulf of Mexico.

The EWG considered long-term index nesting beach datasets when available to identify

trends in the loggerhead population. Overall, they determined that trends could be identified for

two loggerhead subpopulations. The Northern Subpopulation appears to be stabilizing after a

period of decline; the South Florida Subpopulation appears to have shown significant increases

over the last 25 years suggesting the population is recovering, although the trend could not be

detected over the most recent 7 years of nesting. An increase in the numbers of adult loggerheads

has been reported in recent years in Florida waters without a concomitant increase in benthic

immatures. These data may forecast limited recruitment to south Florida nesting beaches in the

future. Since loggerheads take approximately 20-30 years to mature, the effects of decline in

immature loggerheads might not be apparent on nesting beaches for decades. Therefore, the

EWG cautions against considering trends in nesting too optimistically.

Briefly, the EWG made a number of conclusions regarding the loggerhead population.

They concluded that four distinct nesting populations exist based on genetic evidence, although

separate management is not possible because of insufficient information on the in-water

distribution of each subpopulation. They concluded that the recovery goal of more than 12,800

nests for the Northern Subpopulation was not likely to be met. Currently, nests number about

6,200 and no perceptible increase has been documented. The recovery goal or “measurable

increases” for the south Florida (south of Canaveral and including southwest Florida) appears to

have been met, and this population appears to be stable or increasing. However, index nesting

surveys have been done for too short a time; therefore, it is difficult to evaluate trends throughout

the region. Recovery rates for the entire subpopulation cannot be determined with certainty at

this time. However, caution is warranted because, although nesting activity has been increasing,

catches of benthic immature turtles at the St. Lucie Nuclear Power Plant intake canal, which acts

as a passive turtle collector on Florida’s east coast, have not been increasing. The EWG

recommended establishing index nest survey areas in the Gulf of Mexico to monitor those

populations, which do not currently have recovery goals assigned to them.

Effects of Proposed Action

Gulf Sturgeon (Acipenser oxyrinchus desotoi)

Sturgeon have been collected in Breton Sound to the west and east of Mississippi River

Gulf Outlet (MRGO), and in a lagoon and two bayous connected to the MRGO. The Breton

Islands are very similar to the islands along the Mississippi Gulf Coast used by sturgeon to

forage around during the winter. Several sonic tagged sturgeon have been recorded by LDWF’s

remote tracking system off the northern-most tip of Chandeleur Island in Breton Sound, LA.

However, these fish are considered to be unverified cases since they were isolated recordings,

with only one reading per fish, recorded by a multidirectional hydrophone. USACE ERDC

biologists located one sonic tagged Gulf sturgeon in the MR-GO near Bayou La Loutre in

January of 2005 during telemetry searches of the channel. The fish was tracked moving from the

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MR-GO into the surrounding marshes before its signal was lost. Use of the MR-GO and its bar

channel by Gulf sturgeon would most likely be during migration to and from their winter habitats

and during their marine feeding period. The proposed MDWD project area is located to the south

of these sightings. Since Gulf sturgeon begin their migration to spawning habitat in March and

April, consideration was given to the possibility that the increase in freshwater flow (35,000 cfs

during March and April) could attract the species to the project area. It is possible, though

unlikely, that the freshwater flow from the diversion could confuse Gulf sturgeon. If a Gulf

sturgeon was disoriented and did make its way to the structure, then there is a potential for a

small population to miss the opportunity to spawn during a given year. It is unlikely any

individual sturgeon that finds itself in this position would be at risk for increased mortality. After

April, flow within the structure would return to 1,000cfs and it is assumed that an sturgeon

within the area would return to deeper waters in Breton Sound or the Gulf. This purely

hypothetical assumption is neither supported nor refuted by current literature searches. Due to

the small amount of recent and confirmed occurrences of Gulf sturgeon in the project area,

CEMVN foresees minimal likelihood of impact to Gulf sturgeon populations from the proposed

MDWD and therefore concludes the MDWD project would not adversely affect the species.

Green Sea Turtle (Chelonia mydas)

Given the lack of extensive sea grass beds and the low incidence of sightings in the

proposed project areas, adverse impacts to the green sea turtle population are not expected.

Additionally, the use of a hydraulic cutterhead-type dredge is not known to take sea turtles. With

the low risk of affects to green sea turtles from the MDWD project, CEMVN concludes that the

MDWD project would not adversely affect the species.

Kemp’s Ridley Sea Turtle (Lepidochelys kempii)

Impacts to Kemp’s ridley sea turtle population should be negligible or non-existent.

During March and April when the proposed MDWD project is flowing 35,000cfs though the

structure Kemp’s Ridley are not expected to be in the Louisiana coastal area. The potential

temporary removal of food sources by dredging operations may cause the Kemp’s ridley sea

turtle to forage elsewhere along the Gulf coast until the area is re-colonized by prey species.

Coastal erosion and habitat loss is one limiting factor for the successful recovery of sea turtle

populations in the Louisiana coastal zone. Coastal restoration efforts such as the MDWD project,

should prove to be beneficial to the Kemp’s ridley sea turtle. After assessing the MDWD project

area along with the needs of the Kemp’s ridley sea turtle, CEMVN concludes that the MDWD

project is not likely to adversely affect the species.

Loggerhead Sea Turtle (Caretta caretta)

Habitat in Louisiana that is suitable for Loggerheads to nest on is typically associated

with that of barrier islands. CEMVN believes that the proposed action will only temporarily

disrupt foraging loggerhead sea turtles that may be in the area. Coastal erosion and habitat loss is

one limiting factor for the successful recovery of sea turtle populations in the Louisiana coastal

zone. Coastal restoration efforts such as the MDWD project, should prove to be beneficial to the

loggerhead sea turtle. As previously stated, the use of a hydraulic cutterhead-type dredge is not

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known to take sea turtles. After assessing the MDWD project area and the needs of the

loggerhead sea turtle, CEMVN concludes that the MDWD project would not adversely affect the

species.

Conclusion

Based on currently available historical and catch data, a review of current literature and

studies, and with the employment of avoidance measures recommended through guidelines set

up during coordination with NMFS, the CEMVN, believes that Gulf sturgeon and green, Kemp’s

ridley, and loggerhead sea turtles would not adversely affected from construction and operation

of the MDWD in the project location detailed in this assessment.

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Appendix A-4

Formal Section 7 Consultation Receipt

U.S. Fish and Wildlife Service

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Appendix B

U.S. Fish and Wildlife Service

Coordination Act Report

and Wetland Value Assessment

Assumptions and Analysis

535

Final

Fish and Wildlife Coordination Act Report

Louisiana Coastal Area

Medium Diversion at White Ditch

Plaquemines Parish, Louisiana

PROVIDED TO

NEW ORLEANS DISTRICT

U.S. ARMY CORPS OF ENGINEERS

NEW ORLEANS, LOUISIANA

PREPARED BY

KEVIN ROY, SENIOR FIELD BIOLOGIST

AND

CATHERINE BREAUX, SENIOR FIELD BIOLOGIST

U.S. FISH AND WILDLIFE SERVICE

ECOLOGICAL SERVICES

LAFAYETTE, LOUISIANA

AUGUST 2010

U.S. FISH AND WILDLIFE SERVICE  SOUTHEAST REGION

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TABLE OF CONTENTS

Page

EXECUTIVE SUMMARY .......................................................................................................ES-1

INTRODUCTION ...........................................................................................................................1

DESCRIPTION OF THE STUDY AREA.......................................................................................1

FISH AND WILDLIFE RESOURCES ...........................................................................................3

ALTERNATIVES UNDER CONSIDERATION ...........................................................................7

EVALUATION METHOD .............................................................................................................9

PROJECT IMPACTS ....................................................................................................................10

FISH AND WILDLIFE CONSERVATION AND MITIGATION MEASURES .......................13

SERVICE POSITION AND RECOMMENDATIONS ................................................................13

LITERATURE CITED ..................................................................................................................16

No table of contents entries found.

ATTACHMENTS

Attachment A - WVA Assumptions and Analysis ..................................................................... A-1

FIGURES

Figure 1. Medium Diversion at White Ditch Study Area, Plaquemines Parish, Louisiana.............2

Figure 2. Tentatively Selected Plan for Medium Diversion at White Ditch Feasibility study, a

35,000cfs diversion near Phoenix , Louisiana.................................................................8

TABLES

Table 1: Initial Array of Alternatives .............................................................................................7

Table 2: Benefits for Final Array of Alternatives, in Average Annual Habitat Units ....................9

Table 3: Potential Estimated Impacts (AAHU and Net Acres) for the Tentatively Selected Plan

(35,000 cfs Diversion at White Ditch) ..........................................................................................10

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Executive Summary

The U.S. Fish and Wildlife Service (Service) has prepared this final Fish and Wildlife

Coordination Act Report (FWCAR) for the proposed Louisiana Coastal Area (LCA), Medium

Diversion at White Ditch Project (MDWD), Plaquemines Parish, Louisiana. The Corps of

Engineers, New Orleans District (Corps) is preparing a draft Environmental Impact Statement

and Feasibility Report.

This report contains a description of the existing fish and wildlife resources of the project area,

discusses future with- and without-project habitat conditions, identifies fish and wildlife related

impacts of the proposed project, and provides recommendations for the proposed project. This

document constitutes the final report of the Secretary of the Interior as required by Section 2(b)

of the Fish and Wildlife Coordination Act (48 Stat. 401, as amended; 16 U.S.C. 661 et seq.). A

draft report was provided to the Louisiana Department of Wildlife and Fisheries (LDWF) and the

National Oceanic and Atmospheric Administrations, National Marine Fisheries Service

(NOAAs NMFS) and their comments have been incorporated into this final report.

The White Ditch Diversion study area is located in Plaquemines Parish, Louisiana, east of the

Mississippi River in the Breton Sound Basin. The diversion structure itself would be located

along the east bank of the Mississippi River between the communities of Belair and Phoenix.

The purpose of the diversion is to provide fresh water, nutrients, and sediments to the area

between the Mississippi River and the River aux Chenes (former distributary of the Mississippi

River). Diversion of Mississippi River water into the study area will facilitate sediment

deposition, increase organic production, increase biological productivity, reduce marsh loss, and

improve fish and wildlife habitat. The study area encompasses emergent marsh and shallow

open water habitats. The primary area of benefit consists of marsh and open water habitats

between the Mississippi River and River aux Chenes. A secondary area of benefit would occur

east of the River aux Chenes. Study area wetlands support nationally important fish and wildlife

resources including intermediate, brackish, and saline marshes.

During the alternatives analysis, the no-action alternative and several diversion alternatives were

considered. Diversion sizes ranged from a 5,000 cubic feet per second (cfs) diversion to a

35,000 cfs diversion. Two locations along the Mississippi River and different types of diversion

structures (e.g., box culverts, siphons, gated structures) were also investigated. Also investigated

were certain types of outfall management features to distribute diversion flows more evenly

throughout the study area. Outfall management features included enlargement of existing

channels, plugs, weirs, and culverts. In addition, any material dredged to enlarge existing

channels would be used beneficially to create marsh and forested ridge habitat.

The tentatively selected plan (TSP) diversion structure consists of ten 15 foot by 15 foot box

culverts capable of passing flows as high as 35,000 cfs located in an area of the river with the

potential for high sediment load to promote sediment distribution through the structure. The

outfall management features consist of excavating 230 acres of marsh and shallow water area to

create a new channel and enlarge existing channels and distributaries to better distribute

diversion flows of up to 35,000 cfs. This excavated material will be placed on organic marsh

soils and aquatic substrates to create approximately 31 acres of ridges lining the outfall channels

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and following the historic Bayou Garelle distributary channel and 385 acres of created marsh in

locations adjacent to the outfall channels and distributary network. There will be weirs placed as

flow constrictors to retain as much fresh water and sediment as possible within the study area.

The TSP will benefit the fish and wildlife resources of the MDWD area by providing fresh

water, nutrients, and sediments to the study area thus facilitating sediment deposition, increasing

organic production, increasing biological productivity, and reducing marsh loss. Approximately

13,353 AAHUS and 35,146 net acres of fresh/intermediate, brackish, and saline marsh and ridge

habitats would benefit by the proposed project at the end of the project life. The Service

supports implementation of a 35,000 cfs diversion at White Ditch provided the following fish

and wildlife recommendations are implemented concurrently with project implementation:

1. Future hydrological modeling should be conducted with longer-duration simulations (i.e.,

13-month simulations) to allow more complete projections of salinity change within the

study area. In addition, modeling of different operational plans should be conducted. We

recommend the following operational plans be evaluated; 1) March-April open operation

with a 1,000 cfs maintenance flow the remainder of the year, 2) March open operation

with a 1,000 cfs maintenance flow the remainder of the year, and 3) March 1 to March 14

open operation with a 1,000 cfs maintenance flow the remainder of the year.

2. To determine potential impacts to marine fishery resources in the study area, models

which simulate changes in nekton community composition based on changes in salinity

should be utilized. For example, the Ecopath/Ecosim (www.ecopath.org) models have

been utilized to simulate changes in the nekton community in the Caernarvon Diversion

outfall area. Hydrological modeling output could be used as input for the

Ecopath/Ecosim models or other similar models.

3. The best available data and modeling tools should be utilized to select a more precise

location near Phoenix, Louisiana for the diversion structure to maximize the capture of

suspended sediment. The State of Louisiana Office of Coastal Protection and Restoration

(OCPR) is funding the development of a 3-dimensional river model which could greatly

assist in determining the optimal location for the diversion structure.

4. The Service has concerns regarding the Monitoring and Adaptive Management Plan and

its ability to ensure the goals and objectives are measured and achieved. The Corps

should work with the Service, NOAAs NMFS, and the LDWF during future planning

efforts to address our concerns.

5. If a proposed project feature is changed significantly or is not implemented within one

year of the Endangered Species Act consultation letter, we recommend that the Corps

reinitiate coordination with each office to ensure that the proposed project would not

adversely affect any Federally listed threatened or endangered species or their habitat.

6. Avoid adverse impacts to bald eagle nesting locations and wading bird colonies through

careful design of project features and timing of construction. A qualified biologist should

inspect the proposed work site for the presence of undocumented wading bird nesting

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colonies and bald eagles during the nesting season (i.e., February 16 through October 31

for wading bird nesting colonies, and October through mid-May for bald eagles).

7. To minimize disturbance to colonies containing nesting wading birds (i.e., herons, egrets,

night-herons, ibis, and roseate spoonbills), anhingas, and/or cormorants, all activity

occurring within 1,000 feet of a rookery should be restricted to the non-nesting period

(i.e., September 1 through February 15, exact dates may vary within this window

depending on species present). In addition, we recommend that on-site contract

personnel be informed of the need to identify colonial nesting birds and their nests, and

should avoid affecting them during the breeding season.

8. If a bald eagle nest is discovered within or adjacent to the proposed project area, then an

evaluation must be performed to determine whether the project is likely to disturb nesting

bald eagles. That evaluation may be conducted on-line at:

http://www.fws.gov/southeast/es/baldeagle. Following completion of the evaluation, that

website will provide a determination of whether additional consultation is necessary and

those results should be forwarded to this office.

9. Land clearing associated with project features should be conducted during the fall or

winter to minimize impacts to nesting migratory birds, when practicable.

10. Further detailed planning of project features (e.g., Design Documentation Report,

Engineering Documentation Report, Plans and Specifications, or other similar

documents) should be coordinated with the Service and other State and Federal natural

resource agencies, and shall be provided an opportunity to review and submit

recommendations on the all work addressed in those reports.

11. A report documenting the status of implementation, maintenance and adaptive

management measures should be prepared every three years by the managing agency and

provided to the Corps, the Service, NMFS, U.S. Environmental Protection Agency

(EPA), Louisiana Department of Natural Resources (LDNR), OCPR, and LDWF. That

report should also describe future management activities, and identify any proposed

changes to the existing management plan.

12. The Service recommends a comprehensive examination of the river and all existing and

proposed diversions to coordinate their operation and ensure that their operation will

maximize their restoration capabilities. The ongoing Mississippi River Hydrodynamic

and Delta Management Study should be utilized to address this issue. The Service and

other natural resource agencies should be involved in this study.

13. The Service recommends establishment of a committee similar to the Caernarvon

Interagency Advisory Committee to review the operation and its results of the MDWD

and when necessary, provide recommendations regarding any future operational and

maintenance changes. The Service and other natural resource agencies should be on this

committee.

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INTRODUCTION

The U.S. Army Corps of Engineers, New Orleans District (Corps) is preparing a draft

Environmental Impact Statement (DEIS) for the proposed Louisiana Coastal Area (LCA),

Medium Diversion at White Ditch Project (MDWD), Plaquemines Parish, Louisiana.

This report contains a description of the existing fish and wildlife resources of the project area,

discusses future with- and without-project habitat conditions, identifies fish and wildlife-related

impacts of the proposed project, and provides recommendations for the proposed project. This

document constitutes the final report of the Secretary of the Interior as required by Section 2(b)

of the Fish and Wildlife Coordination Act (48 Stat. 401, as amended; 16 U.S.C. 661 et seq.). A

draft report was provided to the Louisiana Department of Wildlife and Fisheries (LDWF) and the

National Oceanic and Atmospheric Administrations, National Marine Fisheries Service

(NOAAs NMFS), and their comments have been incorporated into this final report.

DESCRIPTION OF THE STUDY AREA

The MDWD study area is located in Plaquemines Parish, Louisiana, east of the Mississippi River

in the Breton Sound Basin (Figure 1). The diversion structure itself would be located along the

east bank of the Mississippi River between the communities of Belair, Louisiana and Phoenix,

Louisiana. The purpose of the diversion is to provide fresh water, nutrients, and sediments to the

area between the Mississippi River and the River aux Chenes. Diversion of Mississippi River

water into the study area will facilitate sediment deposition, increase organic production,

increase biological productivity, reduce marsh loss, and improve fish and wildlife habitat. The

study area encompasses emergent marsh and shallow open water habitats. The primary area of

benefit consists of marsh and open water habitats between the Mississippi River and River aux

Chenes. A secondary area of benefit would occur east of the River aux Chenes. Study area

wetlands support nationally important fish and wildlife resources including fresh, intermediate,

brackish, and saline marshes.

The project area encompasses over 98,000 acres of intermediate to saline intertidal wetland

habitats. The study area boundary follows distinct landscape features beginning in the north

with the confluence of the non-Federal back levee and the forty-arpent canal, extending south

(i.e., paralleling the Mississippi River) along the non-Federal back levee, the Mississippi River

Mainline levee, the New Orleans to Venice Federal back levee and along the left descending

natural bank of the Mississippi River, then it proceeds to the west; past American Bay,

California Bay, and through Breton Sound, near Bay Gardene to the south; into and along River

aux Chenes which forms the eastern boundary and returns back to the beginning point. The area

has been significantly impacted by recent tropical storms and hurricanes and is somewhat

isolated from the effects of the Caernarvon freshwater diversion, located at the northern end of

the Breton Sound Basin.

There are two discrete project areas that were considered for the purposes of the feasibility

study; the area along the Mississippi River where a freshwater diversion structure might be

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located and the project area that could be influenced and benefitted by the diverted freshwater.

The footprint of both of these areas depends upon the overall size and capacity of the diversion

structure recommended.

The area where a diversion structure could be located occurs on the left descending bank of the

Mississippi River, between Bertrandville to the north (river mile 69) and the community of

Davant to the south (river mile 51). An area of particular interest for this study is the stretch

between White Ditch (river mile 64.4) and Phoenix (river mile 59.7). This 4.7 mile stretch is

unique in that there is no hurricane protection levee (back levee) on the marsh side that protects

existing homes and infrastructure from elevated water levels (tidal or storm surge). The

Mississippi River levee is the only flood protection structure that keeps river water from entering

the project study area. This situation minimizes the amount of infrastructure that could be

affected by construction of a diversion structure and allows for a broader array of measures to be

considered in addressing problems in the project area. Channel construction, subsidence, erosion,

saltwater intrusion, and storm-related damages have all significantly altered the natural

environment, causing extensive losses of wetland habitats.

Figure 1. Medium Diversion at White Ditch Study Area, Plaquemines Parish, Louisiana.

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FISH AND WILDLIFE RESOURCES

Wildlife Resources

The coastal wetlands in the study area provide important and essential fish and wildlife habitats,

used for shelter, nesting, feeding, roosting, cover, nursery, and other life requirements. The

coastal marshes of Louisiana provide winter habitat for more than 50 percent of the duck

population of the Mississippi Flyway. Fresh and intermediate marshes support the greatest

concentrations of wintering waterfowl in coastal Louisiana. Wintering waterfowl use is high in

parts of the Breton Sound basin which includes the MDWD study area. Dabbling duck and

diving duck numbers are increasing in the vicinity of existing freshwater diversions, such as in

the Caernarvon area upriver of the study area.

Coastal Louisiana's wetlands also support millions of neotropical and other migratory avian

species such as rails, gallinules, shorebirds, wading birds and numerous songbirds. Louisiana

coastal wetlands provide neotropical migratory birds essential stopover habitat on their annual

migration route. Wading bird colonies are present where suitable habitat is found in the area and

numbers have been steady or increasing in those areas.

The wetlands of the study area provide habitat for many different furbearers, rabbits, and deer.

Game mammals and furbearers are generally associated with forested wetlands. The wetlands of

the Breton Sound basin were historically important for the production of furbearers. In recent

years, fur production has been on a downward trend. This decline is largely attributed to

saltwater intrusion and a corresponding reduction in carrying capacity for fur animals such as

muskrat and nutria (Kerlin 1979).

According to Dundee and Rossman (1989), several amphibians and reptiles occupy a wide

variety of habitats throughout the basin. American alligator abundance has been increasing in

the upper portions of the basin and declining in the lower portions, but overall has declined as

fresh marsh converted to intermediate and brackish marsh. The eastern portion of Plaquemines

Parish, which includes the MDWD study area, suffered major habitat damage from Hurricanes

Katrina and Rita in 2005, resulting in a severe reduction in alligator nest production in 2006.

Fisheries Resources

Louisianas coastal estuaries are the most productive in the Nation. The majority of the MDWD

study area is considered estuarine habitat. Even though extensive areas of marsh have been lost

in coastal Louisiana, commercial harvest and recreational catches of most estuarine fishery

species have not diminished (NMFS 2006). It is important to note that recreational catch and

commercial landings are fishery dependent data. The increase in Louisiana landings may reflect

the expansion of the commercial fishing industry, the growing efficiency in harvest technologies,

and the growing demand for seafood over the past century. One hypothesis to explain continued

high fisheries production is that as marshes have deteriorated, tremendous amounts of organic

detritus have been released into the estuarine system, consequently driving high levels of

primary productivity. High primary productivity increases the resources available for secondary

productivity. Additionally, an increase in marsh to water interface (i.e., marsh edge), and the

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formation of shallow, protected lagoons and ponds, has resulted in prime areas for growth and

development of estuarine species (Browder et al. 1985; Browder et al. 1989; Minello and Rozas

2002). At the same time, saltwater intrusion into previously low-salinity areas has increased the

amount of estuarine area available to estuarine and marine fishery species (Chesney et al. 2000;

Zimmerman et al. 2000). However, this intrusion can exacerbate marsh loss in those areas

(Chabreck and Linscombe 1982; McKee and Mendelssohn 1989).

The American oyster is indigenous to coastal Louisiana and provides a rich ecological and

commercial resource. This organism is unique in that it does not migrate like other estuarine

species. Salinity plays a key role in oyster sustainability. Typically, they proliferate in salinities

ranging from 5 to 15 parts per thousand. Fresher waters fail to support biological function, and

more saline waters promote disease and predation. Production of oysters in Louisiana has been

relatively stable for the last 50 years, with harvest from public beds replacing the decreasing

harvest from private leases. The Louisiana oyster industry has been experiencing many stressors

over the past several decades that threaten the long-term sustainability of both the industry and

the resource. Increasing coastal land loss is reducing the amount of marsh that provides shelter

to reefs, and saltwater intrusion is exacerbating disease and predation.

Essential Fish Habitat

The project is located within an area identified as Essential Fish Habitat (EFH) by the

Magnuson-Stevens Fishery Conservation and Management Act (MSFCMA, Magnuson-Stevens

Act; P.L. 104-297). The updated and revised 2006 generic amendment of the Fishery

Management Plans for the Gulf of Mexico, prepared by the Gulf of Mexico Fishery Management

Council, identifies EFH in the project area to be estuarine emergent wetlands, submerged aquatic

vegetation, mud, sand, shell, and rock substrates, and estuarine water column. Under the

MSFCMA, wetlands and associated estuarine waters in the project area are identified as EFH for

various Federally managed species including: juvenile brown and white shrimp; eggs,

larvae/postlarvae, and juvenile Gulf stone crab; and larvae/postlarvae, juvenile, and adult red

drum.

In addition to being designated as EFH for these species, water bodies and wetlands in the study

area provide nursery and foraging habitats supportive of a variety of economically important

marine fishery species, such as striped mullet, Atlantic croaker, gulf menhaden, spotted seatrout,

sand seatrout, southern flounder, black drum, and blue crab. Some of these species also serve as

prey for other fish species managed under the Magnuson-Stevens Act by the GMFMC (e.g.,

mackerels, snappers, and groupers) and highly migratory species managed by NMFS (e.g.,

billfishes and sharks). (NMFS 2008)

In the future without the project, estuarine marsh is the primary type of EFH impacted by

continued wetland loss and deterioration. Although an increase in some types of EFH (i.e., mud

bottom and estuarine water column) would occur, adverse impacts would occur to more

productive types of EFH (i.e., estuarine emergent wetlands). The loss of estuarine emergent

wetlands would result in negative impacts to juvenile brown and white shrimp; eggs,

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larvae/postlarvae, and juvenile Gulf stone crab; and larvae/postlarvae, juvenile and adult red

drum.

Threatened and Endangered Species and Species of Concern

Within the MDWD study area there are two endangered species, pallid sturgeon

(Scaphirhynchus albus) and West Indian manatee (Trichechus manatus) under the Federal

jurisdiction of the USFWS and/or the NMFS and several species of concern, including bald

eagle (Haliaeetus leucocephalus), brown pelican (Pelecanus occidentalis) and other colonial

wading birds protected under the Migratory Bird Treaty Act (40 Stat. 755, as amended; 16

U.S.C. 703 et seq.) and/or the Bald and Golden Eagle Act (54 Stat. 250, as amended, 16 U.S.C.

668a-d).

Species of Concern

Colonial nesting birds

The proposed project would be located in an area where colonial nesting waterbirds may be

present. Colonies may be present that are not currently listed in the database maintained by the

Louisiana Department of Wildlife and Fisheries. That database is updated primarily by

monitoring the colony sites that were previously surveyed during the 1980s. Until a new,

comprehensive coast-wide survey is conducted to determine the location of newly established

nesting colonies, we recommend that a qualified biologist inspect the proposed work site for the

presence of undocumented nesting colonies during the nesting season. To minimize disturbance

to colonial containing nesting wading birds (i.e., herons, egrets, night-herons, ibis, and roseate

spoonbills), anhingas, and/or cormorants, all activity occurring within 1,000 feet of a rookery

should be restricted to the non-nesting period (i.e., September 1 through February 15, exact dates

may vary within this window depending on species present). In addition, we recommend that

on-site contract personnel be informed of the need to identify colonial nesting birds and their

nests, and should avoid affecting them during the breeding season.

Brown Pelican

Brown pelicans were delisted (due to recovery) on December 17, 2009, and are no longer

protected under the ESA, but they are still protected by the Migratory Bird Treaty Act (MBTA).

Brown pelicans may occasionally feed in the shallow estuarine waters found within the project

area; however, no nesting colonies are known to occur there.

Bald Eagle

The project-area forested wetlands may provide nesting habitat for the bald eagle, which has

officially been removed from the List of Endangered and Threatened Species as of August 8,

2007. Bald eagles nest in Louisiana from October through mid-May. Eagles typically nest in

mature trees (e.g., bald cypress, sycamore, willow, etc.) near fresh to intermediate marshes or

open water in the southeastern Parishes. Major threats to this species include habitat alteration,

human disturbance, and environmental contaminants (i.e., organochlorine pesticides and lead).

Although the bald eagle has been removed from the threatened and endangered species list, it

continues to be protected under the Migratory Bird Treaty Act (MBTA) and the Bald and Gold

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Eagle Protection Act (BGEPA). The Service developed the National Bald Eagle Management

(NBEM) Guidelines to provide landowners, land managers, and others with information and

recommendations regarding how to minimize potential project impacts to bald eagles,

particularly where such impacts may constitute disturbance, which is prohibited by the

BGEPA. Those guidelines recommend maintaining: (1) a specified distance between the activity

and the nest (buffer area); (2) natural areas (preferably forested) between the activity and nest

trees (landscape buffers); and (3) avoiding certain activities during the breeding season. The

buffer areas serve to minimize visual and auditory impacts associated with human activities near

nest sites. Ideally, buffers would be large enough to protect existing nest trees and provide for

alternative or replacement nest trees. On-site personnel should be informed of the possible

presence of nesting bald eagles within the project boundary, and should identify, avoid, and

immediately report any such nests to this office. A copy of the NBEM Guidelines is available at:

http://www.fws.gov/migratorybirds/issues/BaldEagle/NationalBaldEagleManagementGuidelines

.pdf. If after consulting those guidelines you need further assistance in determining the

appropriate size and configuration of buffers or the timing of activities in the vicinity of a bald

eagle nest, please contact this office.

Threatened and Endangered Species

Pallid Sturgeon

Recent evidence raises the possibility that the Federally endangered pallid sturgeon could occur

in the Mississippi River adjacent to the project area. The pallid sturgeon is an ancient species of

fish that requires large, turbid, free-flowing riverine habitat with rocky or sand substrate. They

are usually found on the bottoms of the rivers on sand flats or gravel bars, and apparently prefer

areas with strong currents in or near the main channel. It is one of the largest and rarest fish in

the Mississippi and Missouri River basins. Pallid sturgeon are opportunistic feeders that eat

insects, crustaceans, mollusks, annelids, fish and eggs of other fish. Scant information exists on

the range and habitat preferences of pallid sturgeon for this part of the Mississippi River. Most

data are from populations in upper Missouri and other Midwest rivers, and also the Atchafalaya

River in Louisiana, however, it is possible that limited numbers of the species also exists in the

Red River. Surveys are currently being conducted to determine the presence/absence of this

species in the lower reaches of the Mississippi River, including the reach adjacent to the MDWD

study area.

West Indian Manatee

Federally listed as an endangered species, West Indian manatees occasionally enter Lakes

Pontchartrain and Maurepas, and associated coastal waters and streams during the summer

months (i.e., June through September). Manatee occurrences appear to be increasing, and they

have been regularly reported in the Amite, Blind, Tchefuncte, and Tickfaw Rivers, and in canals

within the adjacent coastal marshes of Louisiana. They have also been occasionally observed

elsewhere along the Louisiana Gulf coast. The manatee has declined in numbers due to

collisions with boats and barges, entrapment in flood control structures, poaching, habitat loss,

and pollution. Cold weather and outbreaks of red tide may also adversely affect these animals.

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If project construction has not been initiated within 1 year, follow-up consultation should be

accomplished prior to making expenditures for construction. If the scope or location of the

proposed work is changed, consultation should be reinitiated as soon as such changes are made.

ALTERNATIVES UNDER CONSIDERATION

During the alternatives analysis, the no-action alternative and several diversion alternatives were

considered. Diversion sizes ranged from a 5,000 cubic feet per second (cfs) to a 100,000 cfs

diversion. Five locations along the Mississippi River and different types of diversion structures

(e.g., box culverts, siphons) were also investigated. Also investigated were certain types of

outfall management features to better distribute diversion flows and retain as much fresh water

and sediment as possible within the study area. Outfall management features included

enlargement of existing channels, guide levees, distributaries, culverts, and channel

constrictions. In addition, any material dredged to enlarge existing channels would be used

beneficially to create marsh and ridge habitat.

Preliminary screening eliminated the 45,000, 75,000 and 100,000 cfs alternatives from further

consideration as well as all but two diversion locations. Therefore, an initial array of alternatives

was further evaluated for selection of a final array. Each diversion alternative was evaluated

under the assumption that the diversion would be open at all times unless the flow of the

Mississippi River dropped below 300,000 cfs. The initial array of alternatives is found in the

table below. Diversion size indicates the maximum flow that could occur through the diversion

structure.

Table 1: Initial Array of Alternatives.

Location/Alternative

Maximum

Diversion Flow

No Action

Location 2 - White Ditch 5,000 cfs

Location 2 - White Ditch 10,000 cfs

Location 2 - White Ditch 15,000 cfs

Location 2 - White Ditch 35,000 cfs

Location 3  Phoenix 5,000 cfs

Location 3  Phoenix 10,000 cfs

Location 3  Phoenix 15,000 cfs

Location 3 - Phoenix 35,000 cfs

The Medium Diversion at White Ditch Project Delivery Team (PDT) met on December 1, 2009,

to select the final array of alternatives to be evaluated. Based on the results of the incremental

cost/cost-effectiveness analysis, three alternatives were selected for the final array; 1) a 10,000

cfs diversion at Location 3, 2) a 15,000 cfs diversion at Location 3, and 3) a 35,000 cfs diversion

at Location 3. Those three alternatives, along with the No Action Alternative, were selected for

the final array. Subsequently, a 5,000 cfs diversion at Location 3 was added to the final array

because it was determined to be a cost-effective alternative and was the least expensive.

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The PDT met again on January 6, 2010, to review the results of the second incremental cost/costeffectiveness analysis that was conducted on the final array. The purpose of that meeting was to

select the Tentatively Selected Plan (TSP). Based on the results of the incremental cost/costeffectiveness analysis and consideration of the Corps Principles and Guidelines Criteria (i.e.,

acceptability, completeness, effectiveness, and efficiency), the 35,000 cfs diversion near

Phoenix, Louisiana was selected as the TSP.

The TSP (Figure 2) diversion structure consists of ten 15 foot by 15 foot box culverts capable of

flows as high as 35,000 cfs located in an area of the river with the potential for high sediment

load to promote sediment distribution through the structure. The intent of the diversion is to

have an operational plan which included a March-April diversion pulse (open structure) and a

flow of 1,000 cfs during the remainder of the year as long as Mississippi River flows exceeded

300,000 cfs. This operational plan was selected over an open operation plan utilized earlier for

several reasons; 1) a spring pulse reduces impacts from over-freshening that would occur to

estuarine-dependent fisheries; 2) open operation, while achieving no net loss of wetlands, would

not achieve the project goal of maintaining a gradient of marsh types in the study area, 3) a

pulsed operation is preferred by the public/stakeholders because of its reduced impacts to marine

fisheries and oyster production in the estuary. This operation would also closely resemble the

natural overbank flooding the occurred prior to the construction of the Mississippi River levees.

Figure 2. Tentatively Selected Plan for Medium Diversion at White Ditch Feasibility

Study, a 35,000 cfs diversion near Phoenix, Louisiana.

The outfall management features consist of excavating 230 acres of marsh and shallow water

area to creating a new channel and enlarge existing channels and distributaries to better

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distribute diversion flows of up to 35,000 cfs. This excavated material will be placed on organic

marsh soils and aquatic substrates to create approximately 31 acres of ridges lining the outfall

channels and following the historic Bayou Garelle distributary and 385 acres of created marsh in

locations adjacent to the outfall channels and distributary. There will be weirs placed as flow

constrictors to retain as much fresh water and sediment as possible within the study area (Figure

2).

EVALUATION METHOD

Direct impacts and benefits to coastal marsh habitats were quantified by acreage and habitat

quality (i.e., average annual habitat units or AAHUs) by the Service and are presented in Table

1. The Service used the Wetland Value Assessment (WVA) methodology to quantify benefits/

impacts. The WVA is used to evaluate proposed Coastal Wetlands Planning, Protection, and

Restoration Act (CWPPRA) projects, and is similar to the Services HEP, in that habitat quality

and quantity (acreage) are measured for baseline conditions, and predicted for future withoutproject and future with-project conditions. As with HEP, the WVA provides a quantitative

estimate of project-related impacts to fish and wildlife resources; however, the WVA is based on

separate models for fresh/intermediate marsh, brackish marsh, and saline marsh. WVAs and

assumptions for the TSP are available in Attachment A. WVA and assumption information on

the final array of alternatives are available for review at the Services Lafayette, Louisiana, field

office.

To determine wetland benefits (net acres) for each alternative, the Sediment and Nutrient

Delivery Model-Version 2 (SAND2), developed by the Engineering Research and Development

Center (ERDC) and Mr. Ron Boustany of the Natural Resources Conservation Service (NRCS)

was utilized by the Habitat Evaluation Team (HET). The SAND2 model estimates the benefits

resulting from the introduction of sediments and nutrients into the study area. Model predictions

are based on diversion flows into the project area and nutrient and sediment concentrations of the

diversion water. The model derives an estimate of the wetland acreage sustained and/or created

as a function of nutrients and sediments introduced into the system.

The final array was evaluated by the HET using the WVA (Table 2). The SAND2 model was

run for each final alternative and results (wetland acres) utilized in the WVA. Each final

alternative was evaluated under an operational plan which included a March-April diversion

pulse (open structure) and a flow of 1,000 cfs during the remainder of the year as long as

Mississippi River flows exceeded 300,000 cfs.

Table 2: Benefits for Final Array of Alternatives, in Average Annual Habitat Units

(AAHUs).

Alternative

Maximum

Diversion Flow

Net Average Annual

Habitat Units

Location 3  Phoenix 5,000 cfs 5,141

Location 3  Phoenix 10,000 cfs 5,865

Location 3  Phoenix 15,000 cfs 7,654

Location 3  Phoenix 35,000 cfs 13,215

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Feasibility Study / SEIS

PROJECT IMPACTS

Construction of the 35,000 cfs diversion structure and associated outfall management features

would have an initial negative impact on existing wetland vegetation within the construction

footprint, primarily through the excavation of outfall channels and placement of excavated

material on existing marsh. Implementation of the TSP would directly impact 651 acres of

existing marsh, open water, and bottomland hardwood habitats. According to the WVA, the TSP

would result in the direct loss of -45 AAHUs (-120 acres) at the end of 50 years, of intermediate

marsh and bottomland hardwood habitats due to the channel excavation/enlargement, ridge

construction, and diversion structure (Table 3). However, the placement of excavated material

will create 228 net acres (155 AAHUs) of fresh marsh and 31 acres (27 AAHUs) of ridge which

is expected to be suitable for the re-establishment of bottomland hardwoods (Table 3).

Table 3: Potential Estimated Impacts (AAHUs and Net Acres) for the Tentatively Selected

Plan (35,000 cfs diversion).

Project Feature AAHUs Net Acres

Marsh Creation 155.20 228

Channel Enlargement -31.25 -96

Ridge Footprint -11.37 -19

Ridge Creation 27.36 31

Bottomland Hardwood -2.50 -5

Total Net AAHUs and Net Acres 137.44 139

Diversion Benefits by Marsh Type AAHUs Net Acres

Fresh/Intermediate 8,802.11 21,472

Brackish 3,965.54 10,244

Saline 447.42 3,291

Total Net AAHUs and Net Acres 13,215.07 35,007

Total Net AAHUs and Net Acres 13,352.51 35,146

Operation of the 35,000 cfs diversion would provide an inflow of fresh water, sediments, and

nutrients to the project area and support the re-establishment and nourishment of wetland

vegetation in the project area. It was anticipated that a portion of the project area currently

classified as intermediate marsh would be converted to fresh marsh within approximately 5 years

following project implementation. No loss of marsh acreage is expected to occur in the project

area with this alternative. Additionally, the SAND2 model runs conducted in support of the

WVA, projected that the TSP would produce an overall net gain in fresh/intermediate, brackish,

and saline marsh of approximately 35,006 acres and 13,215 AAHUs by year 50 after project

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implementation (Table 3). Overall project benefits total 13,353 net AAHUs and 35,146 net acres

at the end of the project life.

Wildlife Resources

Construction of the diversion structure and associated outfall management features of the 35,000

cfs alternative may disrupt or displace wildlife in the immediate vicinity. However, the longterm impact of construction is expected to be beneficial to overall habitat quality. The WVA

analysis of project features projected a net benefit of 137 AAHUs (Table 3).

By the proposed diversion having a spring pulse (March-April), the salinity gradient is

maintained while sustaining and enhancing existing marsh in the study area. The TSP would

result in improved habitat conditions for several species of wildlife including migratory and

resident waterfowl, shorebirds, wading birds, and furbearers. Migratory waterfowl utilizing the

project area would benefit from a greater food supply resulting from the increased abundance

and diversity of emergent, submerged, and floating-leaved species. Enhanced marsh and marsh

edge would provide increased foraging opportunities for shorebirds and wading birds. Small

fishes and crustaceans are often found in greater densities along vegetated marsh edge

(Castellanos and Rozas 2001, Rozas and Minello 2001), and many of those species are important

prey items for wading birds such as the great blue heron, little blue heron, great egret, blackcrowned night-heron, and snowy egret.

Furbearers (such as muskrat) which feed on vegetation would benefit from the increased marsh

acreage in the project area. Representative furbearers such as the mink, river otter, and raccoon

have a diverse diet and feed on many different species of fishes and crustaceans. Those species

often feed along vegetated shorelines which provide cover for many of their prey species.

The WVA analysis of the potential effects of the diversion projected a net benefit of 13,215

AAHUs for operation of the diversion, for a total projected net benefit of 13,353 AAHUs

including benefits projected for the outfall management features (Table 3).

Fishery Resources

There would be negative impacts to fisheries resulting from channel and ridge construction of

the TSP, but there would be positive impacts from marsh creation. The channel constrictions

included as an outfall management feature would have some negative impact on fisheries access

to the area.

Implementation of the TSP following the operational plan evaluated in the hydraulic modeling

and WVA (open operation in March and April; 1,000 cfs the remainder of the year) is expected

to freshen the entire project area and beyond River aux Chenes to a substantial portion of the

Caernarvon subbasin while the diversion is at full flow and for several weeks after the return to

maintenance flow operation. The overall effect of the diversion is that it is expected to decrease

salinities throughout the project area and convert a substantial portion of the intermediate zone to

fresh marsh within the first several years after project implementation. Water levels, velocities,

and turbidity in outfall areas are all expected to increase during full flow conditions.

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Entrainment of eggs, larvae or fry of Mississippi River fish species in the immediate vicinity of

the diversion inflow may occur during operation of the structure.

High nutrient levels could result in blooms of algae and phytoplankton, and subsequent

decomposition of these organisms could decrease dissolved oxygen levels of water bodies within

the project area. These changes could result in localized adverse impacts to estuarine fishery

productivity, particularly when the diversion is at full flow. The operational plan used to

evaluate the TSP was developed to avoid or minimize these adverse impacts to marine fisheries

and EFH while maximizing sediment and nutrient input to the extent practicable to meet project

objectives.

Freshwater fishery species, such as crawfish, catfish, largemouth bass, and other sunfish should

benefit from implementation of the diversion. Some fishery species would be impacted by

anticipated decreases in salinity and water temperature, and increased turbidity during maximum

flow periods. Less freshwater tolerant species, such as brown shrimp and spotted seatrout, may

be displaced from the northwestern portion of the project area.

By following the operational plan to have a spring pulse (March-April) and flow 1,000 cfs

during the remainder of the year, estuarine-dependent fisheries may be enhanced by helping

combat high salinity spikes without an over-freshening while increasing organic production,

increasing biological productivity and improving fisheries habitat. The introduction of

freshwater to the MDWD project area would ensure that the project area continues to provide

important nursery functions beyond the 50-year project life. However some species, such as

oysters, may be slightly displaced to lower parts of the study area.

Historically, salinity appears to be the chief controlling factor in the number of plankton species

present, while temperature, competition, and predation control the numbers of individuals

present (Day et al. 1989). Therefore, introduction of large amounts of river water (pulsing) into

estuarine systems may have dramatic short-term impacts on plankton populations in adjacent

coastal waters (Hawes and Perry 1978).

Freshwater inflow is an important component of circulation and flushing processes in estuaries

that assist in the transportation of planktonic organisms, nutrients, and detritus to the Gulf of

Mexico. Over the long term, operation of the diversion is expected to help support the aquatic

food web of marine fishery species.

It should be noted that the TSP represents a diversion that is several times greater in maximum

flow capacity than any other diversion constructed to date in coastal Louisiana. At a maximum

flow of 35,000 cfs, the TSP is more than three times greater than the Davis Pond Freshwater

Diversion at 10,700 cfs. The effects on marine fishery species of diverting such large volumes

of water are not completely understood and no effort to quantify those impacts has been

undertaken thus far.

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Essential Fish Habitat

Direct impacts of channel and ridge construction would disturb and displace managed species in

the construction footprint. The marsh creation near the outfall would result in the loss of mud

bottom and estuarine water column as emergent marsh would replace those habitat types.

Although adverse impacts would occur to some types of EFH, more productive types of EFH

(i.e., estuarine emergent wetlands) would be created and enhanced with the diversion. The

accretion of sediment and input of nutrients is expected to benefit estuarine EFH within and

beyond the immediate outfall area of the diversion. The TSP is projected to increase SAV (from

25% to 70% in fresh/intermediate marsh areas and from 15% to 40% in the brackish marsh areas

during the project life) in the project area and decrease emergent marsh loss across all marsh

zones (intermediate, brackish, and saline) by approximately 35,146 net acres over the 50 year

planning horizon. These changes in the project area would not only increase the aerial extent of

EFH, but would also improve the quality of EFH for several managed species.

Threatened and Endangered Species

Possible entrainment of the endangered pallid sturgeon in the Mississippi River in the immediate

vicinity of the diversion inflow may occur during operation of the structure. In terms of

potential impact to the sturgeon, the Corps is responsible for determining whether the proposed

plan is likely (or not likely) to adversely affect any listed species and/or critical habitat, and for

requesting the Services concurrence with that determination. As such, by letter dated July 15,

2010, the Corps requested initiation of formal consultation in accordance with Section 7 of the

ESA. Section 7 allows the Service 90 calendar days to conclude formal consultation and an

additional 45 calendar days to prepare a biological opinion. Although this report constitutes the

final report of the Secretary of Interior, formal Section 7 consultation will continue as a separate

effort.

FISH AND WILDLIFE CONSERVATION AND MITIGATION MEASURES

Coastal marshes are considered by the Service to be aquatic resources of national importance due

to their increasing scarcity and high habitat value for fish and wildlife within Federal trusteeship

(i.e., migratory waterfowl, wading birds, other migratory birds, threatened and endangered

species, and interjurisdictional fisheries). Because of the Services close coordination with the

USACE on this project, and because the project is expected to have an overall benefit to the

marshes of the MDWD Area, the Service has no conservation measures to offer at this time.

SERVICE POSITION AND RECOMMENDATIONS

The TSP will benefit the fish and wildlife resources of the MDWD area by providing fresh

water, nutrients, and sediments to the study area thus facilitating sediment deposition, increasing

organic production, increasing biological productivity, and reducing marsh loss. Approximately

13,353 AAHUS and 35,146 net acres of fresh/intermediate, brackish, and saline marsh and ridge

habitats would benefit by the proposed project at the end of the project life. The Service

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supports implementation of a 35,000 cfs diversion at White Ditch provided the following fish

and wildlife recommendations are implemented concurrently with project implementation:

1. Future hydrological modeling should be conducted with longer-duration simulations (i.e.,

13-month simulations) to allow more complete projections of salinity change within the

study area. In addition, modeling of different operational plans should be conducted. We

recommend the following operational plans be evaluated; 1) March-April open operation

with a 1,000 cfs maintenance flow the remainder of the year, 2) March open operation

with a 1,000 cfs maintenance flow the remainder of the year, and 3) March 1 to March 14

open operation with a 1,000 cfs maintenance flow the remainder of the year.

2. To determine potential impacts to marine fishery resources in the study area, models

which simulate changes in nekton community composition based on changes in salinity

should be utilized. For example, the Ecopath/Ecosim (www.ecopath.org) models have

been utilized to simulate changes in the nekton community in the Caernarvon Diversion

outfall area. Hydrological modeling output could be used as input for the

Ecopath/Ecosim models or other similar models.

3. The best available data and modeling tools should be utilized to select a more precise

location near Phoenix, Louisiana for the diversion structure to maximize the capture of

suspended sediment. The State of Louisiana Office of Coastal Protection and Restoration

(OCPR) is funding the development of a 3-dimensional river model which could greatly

assist in determining the optimal location for the diversion structure.

4. The Service has concerns regarding the Monitoring and Adaptive Management Plan and

its ability to ensure the goals and objectives are measured and achieved. The Corps

should work with the Service, NOAAs NMFS, and the LDWF during future planning

efforts to address our concerns.

5. If a proposed project feature is changed significantly or is not implemented within one

year of the Endangered Species Act consultation letter, we recommend that the Corps

reinitiate coordination with each office to ensure that the proposed project would not

adversely affect any Federally listed threatened or endangered species or their habitat.

6. Avoid adverse impacts to bald eagle nesting locations and wading bird colonies through

careful design of project features and timing of construction. A qualified biologist should

inspect the proposed work site for the presence of undocumented wading bird nesting

colonies and bald eagles during the nesting season (i.e., February 16 through October 31

for wading bird nesting colonies, and October through mid-May for bald eagles).

7. To minimize disturbance to colonies containing nesting wading birds (i.e., herons, egrets,

night-herons, ibis, and roseate spoonbills), anhingas, and/or cormorants, all activity

occurring within 1,000 feet of a rookery should be restricted to the non-nesting period

(i.e., September 1 through February 15, exact dates may vary within this window

depending on species present). In addition, we recommend that on-site contract

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personnel be informed of the need to identify colonial nesting birds and their nests, and

should avoid affecting them during the breeding season.

8. If a bald eagle nest is discovered within or adjacent to the proposed project area, then an

evaluation must be performed to determine whether the project is likely to disturb nesting

bald eagles. That evaluation may be conducted on-line at:

http://www.fws.gov/southeast/es/baldeagle. Following completion of the evaluation, that

website will provide a determination of whether additional consultation is necessary and

those results should be forwarded to this office.

9. Land clearing associated with project features should be conducted during the fall or

winter to minimize impacts to nesting migratory birds, when practicable.

10. Further detailed planning of project features (e.g., Design Documentation Report,

Engineering Documentation Report, Plans and Specifications, or other similar

documents) should be coordinated with the Service and other State and Federal natural

resource agencies, and shall be provided an opportunity to review and submit

recommendations on the all work addressed in those reports.

11. A report documenting the status of implementation, maintenance and adaptive

management measures should be prepared every three years by the managing agency and

provided to the Corps, the Service, NMFS, U.S. Environmental Protection Agency

(EPA), Louisiana Department of Natural Resources (LDNR), OCPR, and LDWF. That

report should also describe future management activities, and identify any proposed

changes to the existing management plan.

12. The Service recommends a comprehensive examination of the river and all existing and

proposed diversions to coordinate their operation and ensure that their operation will

maximize their restoration capabilities. The ongoing Mississippi River Hydrodynamic

and Delta Management Study should be utilized to address this issue. The Service and

other natural resource agencies should be involved in this study.

13. The Service recommends establishment of a committee similar to the Caernarvon

Interagency Advisory Committee to review the operation and its results of the MDWD

and when necessary, provide recommendations regarding any future operational and

maintenance changes. The Service and other natural resource agencies should be on this

committee.

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Feasibility Study / SEIS

LITERATURE CITED

Browder, J.A., H.A. Barley, and K.S. Davis. 1985. A probabilistic model of the relationship

between marshland-water interface and marsh disintegration. Ecological Modeline

29:245-260.

Browder, J.A., L.N. May, A. Rosental, J.G. Gosselink, and R.H. Baumann. 1989. Modeling

future trends in wetland loss and brown shrimp production in Louisiana using thematic

mapper imagery. Remote Sensing of the Environment 28:45-59.

Castellanos, D.L. and L. P. Rozas. 2001. Nekton use of submerged aquatic vegetation, marsh,

and shallow unvegetated bottom in the Atchafalaya River delta, a Louisiana tidal

freshwater ecosystem. Estuaries. Vol. 24, No. 2, p. 184-197.

Chabreck, R.H., and G. Linscombe. 1982. Changes in vegetative types in Louisiana coastal

marshes over a ten-year period. Louisiana Academy of Sciences 45:98-102.

Chesney, E.J., D.M. Balz, and R.G. Thomas. 2000. Louisiana estuarine and coastal fisheries

and habitats: Perspectives from a fishs eye view. Ecological Applications 10:350-366.

Day, J. W., Jr., C. A. S. Hall, W. M. Kemp, A. Yanez-Arancibia. 1989. Estuarine Ecology. John

Wiley and Sons, New York. 558 pp.

Dundee, H.A., and D.A. Rossman. 1989. The amphibians and reptiles of Louisiana. Louisiana

State University Press, Baton Rouge. 300 pp.

Hawes, S. R., and H. M. Perry. 1978. Effects of 1973 floodwaters on plankton populations in

Louisiana and Mississippi. Gulf Research Reports 6(2):109-124.

Kerlin, C.W. 1979. Letter to Jack A. Stephens, Director-Secretary St. Bernard Parish Planning

Commission regarding the impact of the Mississippi River-Gulf Outlet (MRGO) on St.

Bernard Parishs wetlands and water bodies (31 May). In Report of the Environmental

Subcommittee to the MRGO Technical Committee, March 16, 2000. 20 pp.

McKee, K.L., and I.A. Mendelssohn. 1989. Response of a freshwater marsh plant community to

increased salinity and increased water levels. Aquatic Botany 34:301-316.

Minello, T. J. and L. P. Rozas. 2002. Nekton in gulf coast wetlands: fine-scale distributions,

landscape patterns, and restoration implications. Ecological Applications, 12(2), pp. 441-

455.

Mitsch, W. J. and J. G. Gosselink. 1993. Wetlands. 2nd Edition. Van Nostrand Reinhold, New

York, USA. 722 pp.

National Marine Fisheries Service (NMFS). 2006. Commercial Landings of Fish and Shellfish

by U.S. Fishing Craft, 2006. Accessed 16 May, 2008 from

http://www.st.nmfs.noaa.gov/st1/fus/fus06/02_commercial 2006.pdf.

557
Appendix B: U.S. Fish and Wildlife Service

Coordination Act Report Volume VI – Medium Diversion at White Ditch

Final Integrated 17 September 2010

Feasibility Study / SEIS

National Marine Fisheries Service (NMFS). 2008. Essential Fish Habitat: A Marine Fish

Habitat Conservation Mandate for Federal Agencies, Gulf of Mexico Region. Habitat

Conservation Division, St. Petersburg, Florida. August 2008.

Rozas, L. P. and T. J. Minello. 2001. Marsh terracing as a wetland restoration tool for creating

fishery habitat. Wetlands. Vol. 21, No. 3, pp. 327-341.

U.S. Fish and Wildlife Service, Ecological Services, Lafayette, Louisiana. Final Fish and

Wildlife Coordination Act Report, Near-Term Ecosystem Restoration Plan for the

Louisiana Coastal Area. October 2004.

Zimmerman, R.J., T.J. Minello, and L.P. Rozas. 2000. Salt marsh linkages to productivity of

penaeid shrimps and blue crabs in the ecology. Kluwer Academic Publishers, Dordrecht.

558
ATTACHMENT A

WETLAND VALUE ASSESSMENT ASSUMPTIONS AND ANALYSIS

Louisiana Coastal Area

Medium Diversion at White Ditch

Plaquemines Parish, Louisiana

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Attachment A: WVA Volume VI – Medium Diversion at White Ditch

Final Integrated A-1 September 2010

Feasibility Study / SEIS

Assumptions for Diversion WVAs

WVAs have been prepared to determine the benefits due to the diversion of water from the

Mississippi River. The benefited area encompasses the authorized Medium Diversion at White

Ditch study area. Benefits/impacts of the outfall management features (e.g., channel

enlargement) are included in separate WVAs.

Habitats within the benefited area include intermediate, brackish, and saline marsh and

associated open water. Habitat and land-water data were generated by USGS for the study area.

Separate WVAs will be conducted for each marsh type and each diversion size (i.e., 5k, 10k,

15k, and 35k cfs). Acreages of marsh and water within each marsh type were determined using

the 2006 TM/2001 marsh type data. Non-wetland habitat acreages and areas benefited/impacted

by the outfall management features were removed from the analysis. TY0 for the study is 2015.

Therefore, marsh loss was applied for 9 years to the 2006 marsh acreages to achieve baseline

(2015) acreages. The 1985-2006 loss rate (-274.5 ac/yr) was determined by linear regression

using land-water data for the entire study area. Marsh loss within each marsh type was assumed

to be proportional to the percentage of each marsh type within the study area. The intermediate

marsh area varies by diversion size because the acreage impacted by the outfall management

features is different for each diversion size.

Diversion

Size

Intermediat

e Marsh

Intermediat

e Water

Brackish

Marsh

Brackish

Water

Saline

Marsh

Saline

Water

Total

5k 19,909 15,277 11,935 6,425 6,922 36,845 97,313

10k 19,890 15,245 11,935 6,425 6,922 36,845 97,262

15k 19,846 15,215 11,935 6,425 6,922 36,845 97,188

35k 19,768 15,102 11,935 6,425 6,922 36,845 96,997

FWOP Intermediate Marsh Assumptions (same for all diversion sizes)

V1  Background loss rate (-274.5 ac/yr) applied throughout the 50-yr project life.

V2  A baseline value of 25% is proposed. That value is the mean of the SAV cover values from

the Monsecour Siphon Project (2009), Bertrandville Siphon Project (2008), and White Ditch

Siphon Project (2004) WVAs prepared by CWPPRA. Those WVAs encompass the majority of

the intermediate area covered under this WVA. SAV cover is assumed to decrease over the

project life to 15% as the area deteriorates. The percent marsh in the area drops from 57% to

41% which could allow greater fetch in open water areas and increase turbidity. In addition,

salinity is assumed to increase somewhat from 4.4 ppt to 5 ppt as marsh deteriorates to the south

and increase tidal influence and exchange in this area.

V3  Based on an examination of 2008 aerial photography, the area is classified as consisting of

interspersion classes 2 and 3. Class 2 is found within the upper portion of the area and along the

western boundary adjacent to the flood protection levee. The remainder of the area appears to fit

the Class 3 interspersion type. Acreages within each class were calculated using GIS. As the

area deteriorates over time, a downward shift in interspersion classes should occur. Some Class

3 will shift into Class 4 and some Class 2 will shift to Class 3.

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V4  The baseline value of 30% was determined from surveys conducted by NRCS for the

CWPPRA White Ditch Siphon Project. Those surveys encompassed a great deal of this area and

offer the best baseline data available for determining this value. In addition, the mean value

from the three CWPPRA project WVAs conducted in this area is 31%. As marsh deteriorates

throughout this area, it was assumed that shallow open water would decrease slightly to 20%.

V5  The baseline value of 4.4 ppt was determined from three Coastal Reference Monitoring

System stations within the project area. That value is the mean during the growing season

(March-November) from 2008-2009 and ranged from 3.7 ppt in the upper portion of the area to

5.7 near the lower end. Due to marsh deterioration to the south, salinity is assumed to increase

somewhat to 5.0 ppt over the project life.

V6  There are some areas that are under structural marsh management resulting in a reduction

in fisheries access. According to the Monsecour Siphon Project WVA, a total of 1,175 acres are

under management. The table below contains structure ratings for each area under management.

Acreage Structure Structure Rating

297 ac Flap-gated culvert 0.2

696 ac Weir with boat bay 0.5

182 ac Plug 0.0001

Weighted Access Value 0.35

The weighted access value for the entire area is 0.98.

FWOP Brackish Marsh Assumptions (same for all diversion sizes)

V1  Background loss rate (-274.5 ac/yr) applied throughout the 50-yr project life.

V2  A baseline value of 15% is proposed. That value is based on best professional judgment as

no SAV cover data has been collected in this area and there are no previous project WVAs that

have been conducted in this area. It is assumed that SAV cover would be somewhat less in this

area as compared to the intermediate area which was assigned a cover value of 25%. SAV cover

is assumed to decrease over the project life to 5% as the area deteriorates and salinities and tidal

exchange increase. The percent marsh in the area drops from 65% to 49% which could allow

greater fetch in open water areas and increase turbidity. In addition, salinity is assumed to

increase somewhat from 6.6 ppt to 8.0ppt as marsh deteriorates to the south and increase tidal

influence and exchange in this area.

V3  Based on an examination of 2008 aerial photography, the area is classified as consisting of

interspersion classes 1, 3, and 4. Class 1 is found along the western boundary adjacent to the

flood protection levee and extends nearly to the southern study area boundary. Marshes within

that area remain very well intact. The remainder of the area appears to fit either the Class 3 or

Class 4 interspersion classes. Acreages within each class were calculated using GIS. As the area

deteriorates over time, a downward shift in interspersion classes would occur.

V4  The baseline value of 20% is proposed and based on best professional judgment. It is

assumed that water depths are somewhat deeper in this area as compared to the intermediate area

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which has a baseline value of 30%. Brackish marshes tend to be somewhat deeper than fresher

marsh types which are located farther inland. As marsh deteriorates throughout this area, it was

assumed that shallow open water would decrease from 20% to 10%.

V5  The baseline value of 6.6 ppt was determined from three Coastal Reference Monitoring

System stations. Two of those stations are actually located outside the project area but within

brackish marsh in the Breton Sound Basin north of the study area. That value is the annual mean

from 2008-2009 and ranged from 5.0 ppt to 9.9 ppt. Due to marsh deterioration to the south,

salinity is assumed to increase somewhat to 8.0 ppt over the project life.

V6  Based on an examination of aerial photography, there appear to be no restrictions to

fisheries access in this area. Therefore, the access value is 1.0.

FWOP Saline Marsh Assumptions (same for all diversion sizes)

V1  Background loss rate (-274.5 ac/yr) applied throughout the 50-yr project life.

V2  A baseline value of 2% is proposed. That value is based on best professional judgment as

no SAV cover data has been collected in this area and there are no previous project WVAs that

have been conducted in this area. SAV cover is typically very low or non-existent within saline

marshes and this area contains very large open water areas which typically contain no SAV.

However, it is assumed that SAV cover may exist in some of the more isolated bodies of water.

There is assumed to be no SAV cover at the end of the project life as only 9% of the area will be

marsh.

V3  Based on an examination of 2008 aerial photography, the area is classified as consisting of

interspersion classes 4 and 5. The majority of the area is Class 5 with large open water areas and

isolated remnants of marsh. However, some Class 4 is found in the southern and northern

portions of the area. As the area deteriorates over time, the entire area would be Class 5.

V4  The baseline value of 5% is proposed and based on best professional judgment. It is

assumed that water depths are much deeper in this area as compared to the intermediate and

brackish areas. This area consists of very large open water areas which are typically greater than

1.5 ft deep. As marsh deteriorates throughout this area, it was assumed that shallow open water

would decrease from 5% to 1%. Perhaps there would still be some shallow water in the few

remaining remnants of marsh.

V5  One Coastal Reference Monitoring System station is located within the saline marsh area.

Mean annual salinity for 2008-2009 was 10.3 ppt. However, that station is located within an

isolated area of marsh and much of the saline zone encompasses large open water areas at the

lower extent of the estuary where salinities are believed to be higher. Therefore, a baseline of 13

ppt was used to better represent average conditions across this large open area. Due to marsh

deterioration in the area, salinity is assumed to increase to 15.0 ppt over the project life.

V6  Based on an examination of aerial photography, there appear to be no restrictions to

fisheries access in this area. Therefore, the access value is 1.0.

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FWP Assumptions

V1  Marsh acreages for each target year were taken from the SAND2 model output. Based on a

review of hydrologic modeling output which provided predicted salinities across the project area,

it was determined that a portion of the intermediate marsh area would transition to fresh marsh.

That transition was assumed to occur at TY5 for all diversion sizes. The transition line from

fresh to intermediate was determined by reviewing the salinity modeling results and reviewing

habitat data for the Caernarvon Diversion outfall area to determine the range of fresh marsh in

the outfall area. The fresh-intermediate marsh boundary was delineated at the approximate 1.0

ppt isohaline. Based on the modeling results, it was assumed that the intermediate-brackish and

brackish-saline marsh boundaries would remain as shown on the 2001 Coastal Marsh Vegetative

Type Map.

For the 5,000 cfs diversion, loss continues to occur according to SAND2 model output. Loss

was distributed proportionately among the various marsh types.

For the 10,000 cfs diversion, SAND2 model output indicates no marsh loss with some marsh

gain occurring over the project life. Results indicate that 1,675 acres of marsh gain would occur.

It was assumed that all of this marsh gain would occur within the fresh marsh zone.

For the 15,000 cfs diversion, SAND2 model output indicates no marsh loss with substantial

marsh gain occurring over the project life. Results indicate that 6,347 acres of marsh gain would

occur. It was assumed that all of this marsh gain would occur in the fresh marsh zone.

For the 35,000 cfs diversion, SAND2 model output indicates no marsh loss and tremendous

marsh gain over the project life. Results indicate that 21,282 acres of marsh gain would occur.

It was assumed that marsh gain would occur throughout the project area across all four marsh

zones. Beginning in the fresh marsh zone, marsh gain was allowed to continue in each marsh

zone until the percent marsh reached approximately 98%. It was assumed that some open water

would remain and that the area would not completely fill with marsh. Under that scenario, very

little marsh gain occurs in the saline zone.

V2  SAV cover was assumed to increase from baseline conditions for all diversion sizes in the

fresh, intermediate, and brackish marsh zones. SAV cover was not assumed to increase as

diversion size increased. It was assumed that maintenance flow conditions (1,000 cfs for all

alternatives) would be more important than the diversion pulse in determining SAV cover.

Based on research (Rozas et al., 2005) conducted in the Caernarvon Diversion outfall

management area, an SAV cover value of 70% was assumed for the fresh and intermediate

zones. That research indicated SAV cover of 66% in areas influenced by the diversion. Most

sample sites occurred in the intermediate marsh zone. SAV cover was assumed to be 30% in the

brackish zone based on best professional judgment. No increase in SAV cover was assumed to

occur in the saline marsh zone.

V3  Values were based on the amount of marsh projected (SAND2 model results) within each

zone in comparison to the baseline values determined within each area.

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V4  Within the fresh/intermediate zone, shallow open water was assumed to decrease to 25%

from the baseline value of 30% under the 5,000 cfs diversion because marsh loss continues to

occur. However, shallow open water was assumed to increase with increasing diversion size

which would deliver greater amounts of sediment. Since most of this zone fills with marsh under

the 35,000 cfs diversion, it was assumed that most of the open water (95%) would be shallow.

In the brackish zone, shallow open water was assumed to decrease to 15% from the baseline

value of 20% under the 5,000 cfs diversion because marsh loss continues to occur. For the

10,000 and 15,000 cfs diversions, it was assumed that sediment delivery would keep pace with

subsidence and maintain the baseline amount of shallow open water. As with the

fresh/intermediate zone, most of the brackish zone fills with marsh under the 35,000 cfs

diversion; therefore, a value of 95% was assumed.

In the saline zone, shallow open water was assumed to decrease to 2% from the baseline value of

5% under the 5,000 cfs diversion because marsh loss continues to occur. The 10,000 and 15,000

cfs diversions provide enough sediments and nutrients to stop marsh loss within this zone.

Therefore, it was assumed that the baseline amount of shallow open water would be maintained.

Under the 35,000 cfs diversion, some minor marsh growth is expected to occur within this zone.

Because only the finest sediments would reach the saline zone and because of its openness to the

bay, it was assumed that the percent shallow open water would remain at the baseline value of

5%.

V5  Year-long hydrological model simulations were not run due to time constraints. Model

runs consisted of a March-April open operation for all diversion sizes. During that period, even

the 5,000 cfs diversion freshened all of the fresh-intermediate and brackish zones and reduced

salinity in the saline zone to an average of approximately 1 ppt. Model results were also

provided for a 65-day period after the open operation (pulse) ended and maintenance flow (1,000

cfs) was initiated. An additional model run was conducted with the model grid set initially at 7

ppt (cold start run) and maintenance flow of 1,000 cfs. That run was conducted to simulate the

effect of the maintenance flow after salinities returned to normal after the open operation

period. All modeling results were utilized to determine FWP salinities. Changes in salinity were

assumed to occur at TY1 and remain throughout the project life.

Based on modeling results, fresh conditions (0 ppt) will exist throughout the fresh marsh area

during the 2-month pulse and for approximately 2 months afterwards. During the rest of the

growing season, salinities would range up to 1.5 ppt. A mean salinity during the growing season

was then assumed to be approximately 0.5 ppt which is within the optimal range for fresh marsh.

For the intermediate marsh area, modeling results indicated 0 ppt during the 2-month pulse and

for approximately one month afterwards. The following month, salinities average approximately

0.8 ppt. Salinities averaged approximately 3 ppt during the remaining 4 months of the growing

season. The weighted mean salinity during the growing season is 1.6 ppt.

For the brackish area, salinities were 0 ppt during the pulse, 2 ppt in the following month, and 4

ppt the next month. Based on the results of the cold start run, salinity would average

approximately 6.6 ppt during the remainder of the year. The weighted mean annual salinity is 5

ppt.

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For the saline area, salinities averaged approximately 1 ppt during the pulse, 5 ppt in the month

following and 10 ppt in the next month. Based on the results of the cold start run, salinity would

average approximately 13 ppt during the remainder of the year. The weighted mean annual

salinity is 10 ppt.

V6  For all diversion sizes, only the fresh marsh area would experience a reduction in fisheries

access due to the outfall management features (i.e., channel constriction structures). The channel

constrictions resemble a rock weir with a boat bay and would therefore have an access value of

0.6. Based on an examination of aerial photography it was determined than an area of 13,962

acres, 13,911 acres, 13,837 acres and 13,647 acres would be impacted by the channel

constrictions for the 5,000, 10,000, 15,000, and 35,000 cfs diversions, respectively. For each

diversion size, the area impacted by the outfall management features was removed as those areas

were evaluated under a separate WVA. In addition, an area of 1,175 acres has a FWOP access

value of 0.35 (see FWOP discussion). That area would have an access value of 0.21 (0.35x0.6).

The remainder of the fresh area has an access value of 1.0. The weighted access value for FWP

for each diversion size is found in the table below.

Diversion Size Access Value =

1.0

Access Value =

0.6

Access Value =

0.21

Weighted Access

Value

5k 8,137 13,962 1,175 0.72

10k 7,538 13,911 1,175 0.71

15k 7,568 13,837 1,175 0.71

35k 7,647 13,647 1,175 0.72

Benefits Summary

Marsh Type 5,000 cfs 10,000 cfs 15,000 cfs 35,000 cfs

Fresh/Intermediate 3,505.05 3,862.13 5,650.28 8,802.11

Brackish 1,359.93 1,655.31 1,656.16 3,965.54

Saline 276.26 347.78 347.97 447.42

Net AAHUs 5,141.24 5,865.22 7,654.41 13,215.07

Literature Cited

Rozas, P.R., T.J. Minello, I. Munuera-Fernandez, B. Fry, B. Wissel. 2005. Macrofaunal

distributions and habitat change following winter-spring releases of freshwater into the Breton

Sound estuary, Louisiana (USA). Estuarine Coastal and Shelf Science 65 (2005) pp. 319-336.

WVA Assumptions for Project Features

WVAs were prepared to determine the benefits/impacts for the diversion structure and outfall

management features. These WVAs are footprint WVAs in which the area directly

benefited/impacted is used as the project area. Features include 1) ridge creation, 2) marsh

creation, 3) outfall channels, 4) diversion structure, and 5) channel constrictions. Marsh and

ridge are created using material from the outfall channels. Separate WVAs were done for each

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feature and for each diversion size. There are no footprint impacts from the channel

constrictions. However, they do impact fisheries access (V6) in the marsh and open water areas.

The area impacted by each project feature is found in Table 1.

Habitats impacted are intermediate marsh, intermediate open water, and bottomland hardwoods.

Shape files of the impacted areas (except for the diversion structure) were provided to USGS and

habitat and land-water data were generated for each feature for each diversion size. Acreages of

marsh and water were determined using 2006 TM/2001 marsh type data. The area impacted by

the diversion structure was determined by Corps biologists. TY0 for the study is 2015.

Therefore, marsh loss was applied for 9 years to the 2006 marsh acreages to achieve baseline

(2015) acreages. The 1985-2006 loss rate (-0.28%/yr) was determined by linear regression using

land-water data for the entire study area.

Table 1. Acreages impacted by habitat type for each project feature.

5,000 cfs Diversion - 2015

footprint acres

Ridge

Creation

Marsh

Creation

Outfall

Channels

Diversion

Structure

Intermediate marsh 22 59 63

Water 10 80 97

Bottomland hardwoods 2.5

Total 32 139 160 2.5

10,000 cfs Diversion - 2015

footprint acres

Ridge

Creation

Marsh

Creation

Outfall

Channels

Diversion

Structure

Intermediate marsh 22 64 73

Water 10 112 101

Bottomland hardwoods 2.5

Total 32 176 174 2.5

15,000 cfs Diversion - 2015

footprint acres

Ridge

Creation

Marsh

Creation

Outfall

Channels

Diversion

Structure

Intermediate marsh 22 99 82

Water 10 136 107

Bottomland hardwoods 5

Total 32 235 189 5

35,000 cfs Diversion - 2015

footprint acres

Ridge

Creation

Marsh

Creation

Outfall

Channels

Diversion

Structure

Intermediate marsh 22 151 110

Water 9 234 120

Bottomland hardwoods 5

Total 31 385 230 5

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Ridge Creation Assumptions (same for all diversion sizes)

Under FWOP, the ridge footprint area consists of intermediate marsh and open water. Therefore

the intermediate marsh model was used. Under FWP, no marsh exists as the entire footprint is

ridge habitat. The coastal chenier/ridge model was used for FWP.

Marsh model - FWOP

V1  Background loss rate applied throughout the 50-yr project life.

V2  Baseline value was 5% from the Monsecour Siphon Project WVA which was prepared by

CWPPRA in 2009. SAV cover is assumed to be somewhat higher in this area because most of

the open water is adjacent to marsh edge which tends to be shallower and contain more SAV.

SAV cover was assumed to decrease over the project life as marsh deteriorates in the area.

V3  Baseline value determined from aerial photography. Marsh loss within this small footprint

over the project life is not likely to result in a change in interspersion.

V4  Based on this footprint being in shallow water next to marsh edge, it was assumed that a

high percentage (90%) of the open water is less than 1.5 ft. It was assumed to decrease slightly

over the project life as the area deteriorates.

V5  Baseline value of 3.7 ppt was taken from the Monsecour Siphon Project WVA which

determined the mean salinity during the growing season based on data from CRMS stations in

the area. Salinity is assumed to increase somewhat over the project life as marsh deteriorates

and tidal influence moves farther inland.

V6  Based on aerial photography, there are no restrictions to fisheries access.

Ridge Model

Under FWP, 32 acres (31 acres for 35k diversion) of ridge habitat is created. It is assumed that

the ridge will be planted with woody species and that no loss of ridge habitat will occur over the

project life. The assumptions used for the ridge model have been developed by the CWPPRA

Environmental Workgroup (EnvWG) for ridge restoration projects and assume plantings with 6

native species and recruitment of additional species over the project life. Cover values were

based on best professional judgment of workgroup members. It is also assumed that control of

Chinese tallow tree was implemented until planted species achieve adequate canopy cover to

shade out invasive species and reduce competition. Also, maintenance plantings were assumed

in case planted species experienced significant mortality.

V1  Tree Canopy Cover  Canopy cover of 20% was assumed at TY8 because at that time

many of the planted species would achieve sufficient height to provide some canopy cover.

Assumed to increase to 80% by TY20 and remain at that value to TY50.

V2  Shrub/Midstory Cover  A shrub/midstory layer would be present by TY3, increase to 65%

by TY15, but then decrease somewhat as canopy cover increases.

V3  Species Diversity  Six species would be planted initially and natural recruitment of other

species would occur over the project life.

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Marsh Creation Assumptions (same for all diversion sizes)

The marsh creation footprint consists of intermediate marsh and open water. Therefore the

intermediate marsh model was used for FWOP. Under FWOP, the area deteriorates as no

restoration action occurs. Under FWP, the entire footprint is filled with dredged material and

marsh is created. The created marsh is considered fresh marsh with the diversion in operation

and the fresh marsh model was used.

V1  For FWOP, the background loss rate was applied throughout 50-yr project life. For FWP,

assumptions for marsh creation projects developed by the CWPPRA EnvWG were assumed  a

50% reduction in the background loss rate was applied.

V2  The baseline value was 5% from the Monsecour Siphon Project WVA which was prepared

by CWPPRA in 2009. The baseline value is assumed to be somewhat higher (15%) because the

Monsecour Siphon project area encompasses over 12,000 acres and extends southward into areas

more open to tidal exchange and somewhat higher salinity. Under FWOP, cover is assumed to

decrease over the project life as marsh deteriorates in the area. Under FWP, very little open

water exists within the footprint, even at TY50. However, SAV cover is assumed to be high

within the open water areas within the marsh creation platform due to the operation of the

diversion. A cover value of 70% is suggested per research done in the Caernarvon Diversion

outfall management area (Rozas et al., 2005).

V3  Baseline value determined from aerial photography. Under FWOP, marsh loss within this

small footprint over the project life is not likely to result in a change in interspersion. Under

FWP, the marsh creation sites are classified as Class 5 at TY1, Class 3 at TY3, and Class 1 at

TY5. Class 1 is maintained throughout the project life.

V4  Based on surveys conducted by NRCS for the CWPPRA White Ditch Siphon Project, the

percent shallow open water is 30%. Under FWOP, that value is assumed to decrease as the area

deteriorates and subsidence occurs. Under FWP, the value is assumed to remain high as very

little loss of the created marsh is expected to occur and water depths will likely be very shallow

within the marsh platform.

V5  Baseline value of 3.7 ppt was taken from the Monsecour Siphon Project WVA which

determined the mean salinity during the growing season based on data from CRMS stations in

the area. Salinity is assumed to increase somewhat under FWOP as marsh deteriorates and tidal

influence moves farther inland. The FWP salinity is assumed to be 0.5 ppt as this area will be

within the immediate outfall of the diversion. A mean salinity of 0.0 ppt was not assumed

because there will be periods when the diversion is not in operation and salinities will likely

increase during those periods.

V6  Based on aerial photography, there are no restrictions to fisheries access under FWOP.

Under FWP, the marsh creation platform will have no access at TY1 but will at TY3 as the

platform subsides. The channel constrictions along River aux Chenes and at the end of the

outfall channel will reduce fisheries access into the project area. Based on the design info

provided, those structures are closest to a rock weir with a boat bay which has an access value of

0.6.

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Outfall Channel Assumptions (same for all diversion sizes)

The channel footprint area consists of intermediate marsh and open water. Therefore the

intermediate marsh model was used for FWOP. Under FWOP, marsh in the area deteriorates as

no restoration action occurs. Under FWP, the entire footprint is dredged to create outfall

channels and the footprint remains open water throughout the project life. Although there is no

marsh, the fresh marsh model is used for FWP due to the fresher conditions resulting from

diversion operation.

V1  For FWOP, the background loss rate is applied throughout project life. Under FWP, no

marsh exists.

V2  SAV cover is assumed to be very low in this area because a large portion of the footprint is

in an existing distributary channel. A baseline value of 5% is proposed and assumed to decrease

(2%) as marsh around the area deteriorates. It is assumed that no SAV would exist FWP as the

entire footprint will be an outfall channel.

V3  Baseline value determined from aerial photography. Marsh loss within this small footprint

over the project life is not likely to result in a change in interspersion. The entire footprint will

be open water (Class 5) under FWP.

V4  For baseline, it is proposed to use a value (20%) somewhat lower than used for the marsh

creation footprint because a portion of the footprint is in an existing distributary channel which

has little shallow water. It was assumed to decrease over the project life as the area deteriorates.

Under FWP, the footprint will be an outfall channel with little water less than 1.5 feet deep. A

value of 1% is suggested to account for shallow water along the channel edges.

V5  Baseline value of 3.7 ppt was taken from the Monsecour Siphon Project WVA which

determined the mean salinity during the growing season based on data from CRMS stations in

the area. Salinity is assumed to increase somewhat over the project life as marsh deteriorates

and tidal influence moves farther inland. Under FWP, salinity is assumed to average 0.5 ppt.

V6  No restrictions to fisheries access are present under FWOP. The channel constrictions have

an access rating of 0.6 for FWP.

Diversion Structure Bottomland Hardwoods Impacts

It is anticipated that construction of the proposed structure would impact adjacent bottomland

hardwoods (BLH) in the amount of 2.5 acres under the 5,000 and 10,000 cfs alternatives and 5.0

acres under the 15,000 and 35,000 cfs alternatives. A WVA was not completed for the proposed

structure location; however, a proportional calculation of Annual Average Habitat Units

(AAHUs) was created utilizing data obtained from a WVA performed in 2008 for a borrow site

(Q6a) with similar habitat characteristics located less than 1⁄2 mile south of the proposed White

Ditch Medium Diversion structure site.

The reference site (i.e. borrow site Q6a) used for the BLH AAHU proportional calculation was a

16.0 acre site located on the flood side portion of the east bank Mississippi River Levee at River

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Mile 60 (center point: Latitude 29°38'55.487"N, Longitude 89°56'58.861"W) in Plaquemines

Parish, Louisiana. Similar to the White Ditch Diversion structure site, the reference site is an

immature, semi-open, light-seeded tree species dominated, frequently flooded forest. Aerial

photography from the White Ditch Diversion structure site and the reference site were compared

and determined to have similar habitat features and site species composition.

On September 30, 2008, personnel from the Service and Corps of Engineers, New Orleans

District, visited borrow site Q6a and delineated two plots. Plot 1 was located on a ridge on the

river side of the proposed Q6a site of which approximately 6.5 acres or 41% of the proposed site

occurs as a portion of the ridge. Plot 2 was located on a lower/slough portion of the proposed

Q6a site of which approximately 9.5 acres or 59% of the proposed site occurs as a portion of the

slough. Utilizing the WVA Bottomland Hardwood Model, an AAHU value was calculated for

each plot, weighted accordingly for its respective size and location with respect to the overall

borrow site, and subsequently combined to give a total AAHU value for the 16.0 acre site.

Q6a Borrow Site (16.00 Acres) ► -8.01 AAHUs

- Plot 1 = -6.41 AAHUs (41% of the site)

= -2.63 AAHUs

- Plot 2 =-9.12 AAHUs (59% of the site)

= -5.38 AAHUs

A proportional calculation was performed to determine the per acre AAHU value for the Q6a

borrow site and the resulting per acre AAHU value was then multiplied by the respective

acreages contained under each diversion alternative to obtain a final AAHU value.

-8.01 AAHUs / 16.0 acres = 0.50 AAHUs/acre

-0.50 AAHUs x 2.5 acres = -1.25 AAHUs (5,000 and 10,000 cfs diversions)

-0.50 AAHUs x 5.0 acres = -2.50 AAHUs (15,000 and 35,000 cfs diversions)

Benefits Summary

Feature 5,000 cfs 10,000 cfs 15,000 cfs 35,000 cfs

Marsh Creation 54.59 72.52 92.19 155.20

Outfall Channel Impacts -15.99 -19.08 -21.89 -31.25

Ridge Impacts -11.33 -11.33 -11.33 -11.37

Ridge Creation 28.24 28.24 28.24 27.36

Bottomland Hardwood Impacts -1.25 -1.25 -2.5 -2.5

Total Net AAHUs 54.26 69.10 84.71 137.44

570
Appendix C

NOAA Fisheries Service Coordination Letter

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Appendix C: U.S. Fish and Wildlife

Coordination Letter and Support Volume VI  Medium Diversion at White Ditch

Final Integrated C-1 September 2010

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Appendix C: U.S. Fish and Wildlife

Coordination Letter and Support Volume VI  Medium Diversion at White Ditch

Final Integrated C-2 September 2010

Feasibility Study / SEIS

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Appendix C: U.S. Fish and Wildlife

Coordination Letter and Support Volume VI  Medium Diversion at White Ditch

Final Integrated C-3 September 2010

Feasibility Study / SEIS

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Appendix C: U.S. Fish and Wildlife

Coordination Letter and Support Volume VI  Medium Diversion at White Ditch

Final Integrated C-4 September 2010

Feasibility Study / SEIS

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Appendix C: U.S. Fish and Wildlife

Coordination Letter and Support Volume VI  Medium Diversion at White Ditch

Final Integrated C-5 September 2010

Feasibility Study / SEIS

577
Appendix C: U.S. Fish and Wildlife

Coordination Letter and Support Volume VI  Medium Diversion at White Ditch

Final Integrated C-6 September 2010

Feasibility Study / SEIS

578
Appendix D

404(b)(1) Water Quality Report

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Final Integrated D-1 September 2010

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SECTION 404(b)(1) EVALUATION

MEDIUM DIVERSION AT WHITE DITCH

PLAQUEMINES PARRISH, LOUISANA

I. INTRODUCTION

A. Purpose and General Description.

This project was identified as a Near-term Critical Restoration Feature Recommended for Study

and Future Congressional Authorization in the LCA Main Report dated January 21, 2005. In

November 2007, WRDA passed, authorizing this and other projects from the LCA Main Report.

The MDWD feasibility study is anticipated to result in a Chief’s Report containing a

recommended plan to construct a Mississippi River diversion in the vicinity of White Ditch for

the purposes of introducing freshwater, sediments, and nutrients into the study area. This project

will provide a source of river sediment, freshwater and nutrients to the River aux Chenes

subbasin and other nearby portions of the upper Breton Sound Basin, to restore and protect

marsh soils and vegetation and maintain a functional salinity regime.

The proposed 35,000 cfs diversion would be built just north of Phoenix Louisiana (see Figure 1).

Ten 15-ft by 15-ft box culverts with hydraulic operated sluice gates would be placed in the

Mississippi River levee. An outflow channel about 7,200 feet long, 545 feet wide and 16 feet

deep would be dredged to carry the flow. In addition about 8,600 feet of Bayou Garelle would be

deepened to allow passage of the diverted waters. All material removed from these channels

would be used beneficially. Some would be placed immediately adjacent to the outfall canal and

Bayou Garelle to guide the water and to create 31 acres of ridge habitat. The rest would be

placed in open water and marsh adjacent to the channels to nourish/create 385 acres of marsh.

The marsh nourishment/creation areas would be surrounded by containment berms built with

material from within the areas. Rip-rap will be placed along the outfall channel in key places for

stabilization. Rip-rap plugs would be placed in six major canals leading to River aux Chenes to

prevent diverted sediment from leaving the project area. The material that is removed would be

placed adjacent to the channel to nourish or create marsh. The diversion of fresh water,

sediments and nutrients would benefit 98,000 acres of wetlands and estuarine waters.

B. Location.

The boundary of the project encompasses over 98,000 acres of intermediate, brackish, and

intertidal wetland habitats. The study area boundary follows distinct landscape features

beginning in the north with the confluence of the non-Federal back levee and the Forty-Arpent

canal, extending along the non-Federal back levee, the Mississippi River levee, the Federal back

levee and along the left descending natural bank of the Mississippi River to the west; past

American Bay, California Bay, and through Breton Sound, near Bay Gardene to the south; into

and along River aux Chenes to the east, and back to the point of beginning.

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C. Authority.

Title VII of the Water Resources Development Act (WRDA) 2007 authorizes the Louisiana

Coastal Area (LCA) ecosystem restoration program. Included within that authority are

requirements for comprehensive coastal restoration planning, program governance, a Science and

Technology Program, a program for the beneficial use of dredged material, feasibility studies for

restoration plans, project modification investigations, and restoration project construction, in

addition to other program elements. This authorization was recommended by the Chief of

Engineer’s Report, dated January 31, 2005.

D. General Description of Dredged and Fill Material.

(1) General Characteristics of Material

The material placed to build the Marsh Berms would come from adjacent marsh land.

This material is primarily alluvium that was deposited by annual flooding of the

Mississippi River along with varying amounts of organic matter. Once the Marsh Berms

are constructed, the area within the berm perimeter will be filled with excavated material

from the Outfall Channel and Bayou Garelle to create/nourish marsh. In addition, some

material from the Outfall Channel would be placed adjacent and abutting to the channel

to create ridges. This material is primarily alluvium that was deposited by annual

flooding of the Mississippi River along with varying amounts of organic matter. The

canal plugs and Outfall Channel stabilization would be done with rip-rap.

(2) Quantity of Material.

Approximately 3.8 million cubic yards of material will be use to create the berms.

Approximately 5 million cubic yards of excavated spoil from the Outfall Channel will be

used create/nourish marsh. There will be approximately 150,000 cubic yards of spoil used

in the ridge restoration. About 250,000 tons of 400 lb rip rap will be placed in key

locations along the channel to aid in stabilization. The plugs in the canals will be

constructed with 1,000 tons of 400 pound rip rap and will not hinder boat traffic in the

project area.

(3) Source of Material.

All material excavated and placed within the project area is present or former swamp

floor native material deposited by historic and prehistoric annual flooding of the

Mississippi River. No material would be brought into the project area from outside

sources except material needed to stabilize the Outfall Channel and to construct the canal

plugs.

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E. Description of the Proposed Discharge Sites.

(1) Location and Size.

The marsh berms would be located at the edges of the marsh creation/nourishment areas.

They would cover a few acres. The created/nourished marsh and berms combined would

cover 385 acres located at various sites adjacent to the Outfall Channel and Bayou

Garelle The canal ridges would cover 31 acres adjacent to the Outfall Channel. All these

are indicated on Figure 1. The canal plugs would be placed where six major canals cross

the River aux Chenes ridge. The channel stabilization rip-rap would be placed as

necessary.

(2) Type of Site and Habitat.

Material to construct marsh berms, marsh, and canal ridges would. be placed on

intermediate marsh or in open water. The rip-rap for Outfall Channel would be placed at

the edge of the ridge adjacent to the channel. Rip-rap for the canal plugs would be placed

in six canals.

(3) Timing and Duration of Discharge.

Construction of the diversion and associated outfall management features is anticipated to

take 24–36 months.

F. Description of Disposal Method.

The marsh berms would be built by mechanical means (e.g. small bucket dredge). The marsh

would be created with a hydraulic dredge and pump system. Ridge creation would be conducted

along the outfall channel and Bayou Garelle by means of a mechanical dredge. The material

would be compacted to meet applicable engineering standards. The channel plugs would be built

by mechanical means.

II. FACTUAL DETERMINATIONS

A. Physical Substrate Determinations.

(1) Comparison of Existing Substrate and Fill.

Material placed to create marsh berms would be the same as exiting substrate. Material

placed to create/nourish marsh and create the ridges would come from the Outfall

Channel and would be essentially the same as the substrate – alluvium laid down by the

Mississippi River. The material needed to construct the channel plugs would be rip-rap

brought in from an outside source. The excavated material will be certified as clean fill to

adjacent marsh land.

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(2) Changes to Disposal Area Elevation.

The marsh berms would be constructed +6.0 NAVD88. Areas were assumed to have an

elevation of -1.0 NAVD and will be filled to +3.0 NAVD with initial construction.

Assumed compactions of 1.0 ft will occur within 10 years of completion of the marsh

creation areas.

(3) Migration of Fill.

The berms, marsh and ridges are not expected to migrate.

(4) Duration and Extent of Substrate Change.

The marsh berms and channel ridges would be above 0 NAVD 88 for the 50-year project

life. The marsh would likely reach 0 NAVD 88 in about 30 years.

(5) Changes to Environmental Quality and Value.

Direct impacts to environmental quality and value from placement for marsh and ridge

creation are expected to result in a net benefit of 139.94 Average Annual Habitat Units

(AAHUs) as calculated using the Wetland Values Assessment (WVA) methodology.

(6) Actions to Minimize Impacts.

Formulation of plans for the proposed placement focused on maximizing environmental

benefits to meet project objects while avoiding or minimizing any incidental negative

effects on aquatic areas and substrates.

B. Water Circulation, Fluctuation, and Salinity Determinations.

(1) Alteration of Current Patterns and Water Circulation.

Placement of marsh berms and marsh creation/nourishment will have very little effect on

water circulation. Channel ridges will prevent north to south movement of water in the

degraded marsh that can occur now. Construction of canal plugs will slow water moving

toward the east.

(2) Interference with Water Level Fluctuation.

Disposal of dredged material or rip-rap during project construction is unlikely to interfere

with water level fluctuation.

(3) Salinity Gradient Alteration.

Disposal of dredged material during project construction is not expected to influence

salinity.

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(4) Cumulative Effects on Water Quality.

a. Salinity.

Effects of the proposed action on salinity would occur once the project is

constructed the introduction of Mississippi River water into the MDWD would

reduce salinities in the project area. However, the reduction in salinity values

within the project area are highly dependent on how the structure will be operated

and the volume of water allowed to be diverted from the river. During diversion

operation salinities would be lowered across the project areas. Depending on the

intensity and duration of these operations, an effect on the salinities from the

diversion within the project area could be seen for up to 3-months.

Placement of dredged material during project construction would not influence

salinity. However, the purpose of this diversion is to introduce fresh water into the

basin. During diversion operation at maximum flow, salinities would be lowered

across the project area. The operation of the White Ditch Diversion would be

coordinated with that of the Caernarvon Diversion in the northern portion of the

Breton Basin.

b. Clarity.

Disposal associated with marsh berm construction, marsh creation/nourishment

and ridge building would reduce water clarity. However, reduction in clarity

caused by construction activities would be short duration and clarity would soon

return to pre-construction levels. Operation of the White Ditch and Caernarvon

Diversions would impact water clarity.

c. Color.

Placement of dredged material during construction would have no impact on the

color of the water. Operation of the White Ditch and Caernarvon Diversions

would impact water color.

d. Water Chemistry and Dissolved Gasses.

Materials excavated to provide features of the proposed action would contain

variable concentrations of organic material. Decomposition of organic material

within the placement sites may result in a local, temporary reduction in dissolved

oxygen or release of ammonia. However, hydrologic exchange between the marsh

and MDWD would reduce dissolved oxygen deficits and facilitate the

transformation of ammonia into non-toxic nitrate. The introduction of river water

into the Breton Sound Basin may increase dissolved oxygen concentrations,

particularly during summer.

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e. Temperature.

Placement of dredged material during construction would have no impact on

temp. However, the diverted Mississippi River water could lower water

temperature in much of the Breton Basin when the diversion is at full operation.

No significant negative impacts are expected.

f. Nutrients.

An existing problem with the marsh within the Breton Sound Basin is a lack of

nutrients. One of the objectives of the proposed action is to allow waters from the

Mississippi River to supply nutrients to the marsh within the basin. The project is

expected to have a positive impact on this parameter.

Placement of dredged material during construction would have no effect on

nutrients. However, one of the objectives of the proposed diversion is to allow

waters from the Mississippi River to supply nutrients to the marsh within the

basin. This would be in addition to nutrients brought in by the Caernarvon

Diversion.

(5) Changes to Environmental Quality and Value.

Deposition of dredged material may temporarily affect water quality by increasing

turbidity/suspended solids in the construction area. However, operation of the White

Ditch Diversion is expected to provide approximately 13,355 AAHUs in environmental

habitat benefits over 50 years of operation.

(6) Actions Taken to Minimize Impacts.

Material dredged from the Outfall Channel would be used beneficially to create./nourish

marsh and create ridge habitat.

C. Suspended Particulate / Turbidity Determinations.

(1) Alteration of Suspended Particulate Type and Concentration.

Material excavated from the existing White Ditch and the marsh is of similar physical

and chemical quality to existing substrates within the marshes. Particulates suspended

during project construction would dissipate after construction activities are complete.

(2) Particulate Plumes Associated with Discharge.

There would be essentially no particulate plumes associated with discharge during

construction.

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(3) Changes to Environmental Quality and Value.

Construction of the Outfall Channel would convert 223 acres of marsh to water.

However, dredged material from the Outfall Channel would be used to create 31 acres of

ridge and to create/nourish 385 acres of marsh. In addition, the diversion of Mississippi

River water is expected to provide approximately 13,355 AAHUs of habitat benefit over

50 years.

(4) Actions to Minimize Impacts.

See (3) above.

D. Contaminant Determinations.

Fill material is former marsh sediment that would be returned to the marsh

floor. A Phase I Environmental Site Assessment of the study revealed no potential sources of

contamination at or near the construction areas.

E. Aquatic Ecosystem and Organism Determinations.

(1) Effects on Plankton.

During actual construction activities of project features there would be short-term direct

impacts to plankton populations due to increases in turbidity, low DO, and introduction

of dredged sediments into shallow open water areas. Plankton populations should return

after construction.

(2) Effects on Benthos.

Disposal of dredged material to create marsh berms, create/nourish marsh and create

ridges would eliminate benthos in the project footprint.

(3) Effects on Nekton.

Disposal effects on nekton are likely to be minor as the fish and shellfish could leave the

disposal site.

(4) Effects on the Aquatic Food Web.

The marsh created/nourished by disposal from the Outfall channel would benefit the

aquatic food web. In addition, operation of the diversion would have a beneficial effect

on the aquatic food web in the project area. Nutrients and would be added to the food

web, providing a benefit to local area fisheries.

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(5) Effects on Threatened and Endangered Species.

No federally listed threatened or endangered species are known to occur within the

project area boundary (USFWS, 2010).

(6) Effects on Other Wildlife.

Placement of dredged material may disrupt or displace wildlife in the immediate vicinity.

However, any such impacts would be localized and temporary, and most wildlife species

would move to an area with more favorable conditions and return after construction is

completed.

(7) Actions to Minimize Impacts.

Placement of material excavated for construction of project features was designed in the

context of beneficial use, to be used for marsh and ridge creation which will directly

benefit the aquatic ecosystem.

F. Proposed Disposal Site Determinations.

Discussions pertaining to turbidity and suspended particulates are summarized under Section II.

C in this document. Contaminants were discussed previously under Section II. D of this

Evaluation. Implementation of the proposed project will have no significant adverse effects on

municipal or private water supplies; recreational or commercial fisheries; water related

recreation or aesthetics; parks; national monuments; or other similar preserves. Any adverse

impacts will be minor and of short-term duration. An application for State water quality

certification under Section 401 of the Clean Water Act is being submitted to the Louisiana

Department of Environmental Quality.

G. Determination of Cumulative Effects on the Aquatic Ecosystem.

The project would have long-term positive effects to aquatic resources found on the site.

Temporary turbidity impacts may occur on- and off-site during construction of project features,

but would be short-term in duration. No long-term, negative cumulative impacts are anticipated

to occur. Beneficial impacts are expected to occur on site for wetlands, wetland wildlife, and

fish. Long-term productivity would be enhanced with implementation of the project.

H. Determination of Secondary Effects on the Aquatic Ecosystem.

Most fish and wildlife utilizing these water bodies should benefit from the physical conditions

the White Ditch Diversion would create when operated to meet project objectives. However,

indirect impacts to oyster leases could include increased rate of mortality and decrease in

productivity in oyster leases located closest to the diversion site, during the period when the

diversion is at full operational capacity and for up to 3 months after the return to maintenance

flow conditions. This could result in a loss of revenue for commercial oyster harvesters. Over the

50-year planning horizon, potential beneficial effects to oyster populations could result if

reduced salinities resulting from diversion operation were to increase the spatial extent of

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habitats experiencing salinities in the optimal range (5–15 parts per thousand) for oyster

production. Continued water quality and biological monitoring of the project area before and

after project construction should assist in refining the operation plan as needed to meet project

objectives for restoring marsh while maintaining a functioning salinity regime in the estuary.

III. FINDINGS OF COMPLIANCE OR NON-COMPLIANCE WITH THE

RESTRICTIONS ON DISCHARGE

A. No significant adaptations of the guidelines were made relative to this evaluation

B. No practicable alternatives to the proposed discharges could be identified that would have

less adverse impacts on the aquatic ecosystem.

C. Chemical constituents of the dredged material released during dredging and disposal

operations are not expected to exceed LA Water Quality Standards.

D. The proposed action is compliant with the Endangered Species Act of 1973, as amended.

The proposed action would not adversely affect endangered or threatened species or their

critical habitats.

E. The proposed action is compliant with specified protection measures for marine

sanctuaries designated by the Marine Protection, Research, and Sanctuaries Act of 1972.

All disposal sites and effects are inland waters. No effects would occur in ocean waters

beyond the shoreline of the Gulf of Mexico.

F. Evaluation of Extent of Degradation of the Waters of the United States.

(1) Effects on Human Health and Welfare

a. Municipal and Private Water Supplies.

Implementation of the TSP may require replacement of a water supply pipeline at

the diversion site to continue providing water services to the Point la Hache and

Phoenix communities. Implementation of Alternative 4 may have a short term

indirect impact on water services if replacement of a water supply pipeline is

required at the diversion site.

b. Recreational and Commercial Fisheries.

There would be short-term direct impacts to recreational and commercial fishing

due to increases in turbidity, low DO, and introduction of dredged sediments into

shallow open water areas. The immediate area would be unavailable for fishing

during construction.

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c. Plankton.

There would be short-term direct impacts to plankton populations due to increases

in turbidity, low DO, and introduction of dredged sediments into shallow open

water areas. There would be long-term loss of shallow water habitats in some

areas due to dredge disposal activities. However, overall, there is an abundance of

shallow open water habitat in the project area available for use by plankton.

d. Fish.

Temporary conditions would likely displace more mobile fisheries species from

the construction area. Following construction, displaced fish would likely return

to the project area. However, the canal plugs could have some negative impact on

fisheries access to the area.

e. Shellfish.

No measurable direct impacts to oysters are anticipated to result from placement

of dredged material.

f. Wildlife.

Temporary low DO and turbidity caused by placement of dredged material is

unlikely to affect wildlife.

g. Special Aquatic Sites.

Wetlands are the major special aquatic sites in the project area. Disposal of

dredged material would create/nourish 385 acres of marsh.

(2) Effects on Life Stages of Aquatic Life and Other Wildlife Dependent on Aquatic

Ecosystems.

Impacts to early life stages may occur during placement of dredged material, but they are

expected to diminish after project completion. The created/nourished marsh would

provide a nursery area for early life stages of many fish and shellfish.

(3) Effects on Aquatic Ecosystem Diversity, Productivity and Stability.

Disposal of dredged material would create/nourish marsh. The diversion would increase

submersed aquatic vegetation, plankton, plant growth production of organic detritus. As a

result, ecosystem diversity and productivity would be expected to increase. Enhancement

of marsh habitats over the project life is expected to increase the long-term stability of the

aquatic ecosystem in this area.

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(4) Effects on Recreational, Aesthetic, and Economic Resources.

Disposal of dredged material would have very little impact on recreational, aesthetic, and

economic resources. The diversion is an un-natural element and may work to decrease the

scenic quality. However, the potential benefits of reclaimed land mass and marsh area,

and the need to protect this marsh area outweigh the visual impacts of developing the

diversion.

G. Appropriate and Practicable Steps Taken to Minimize Potential Adverse Impacts of the

Discharge on the Aquatic Ecosystem.

As stated in Section II. E. (7) of this evaluation, formulation of project plans and designs,

evaluation of alternative plans, and development of operational scenarios for the TSP, have all

been conducted with the objective of minimizing potential negative impacts to the aquatic

ecosystem. Placement of material excavated for construction of project features was designed in

the context of beneficial use, to be used for marsh and ridge creation which will directly benefit

habitat for wildlife and fish in the immediate vicinity of construction.

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IV. EVALUATION RESPONSIBILITY

A. Evaluation Prepared By:

B. Evaluation Review By:

The proposed plan for the MEDIUM DIVERSION AT WHITE DITCH PLAQUEMINES

PARRISH, LOUISANA, which incorporates sites for dredging and excavation and the

placement of fill, complies with the requirement of guidelines, and includes appropriate and

practicable methods to minimize adverse effects to the aquatic ecosystem.

Date:

Alvin B. Lee

Colonel, U.S. Army

District Commander

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Figure 1.

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Appendix E

Louisiana Coastal Resources Program

Consistency Determination

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CONSISTENCY DETERMINATION

Louisiana Coastal Use Guidelines

Medium Diversion at White Ditch

Plaquemines Parish, Louisiana

INTRODUCTION

Section 307 of the Coastal Zone Management Act of 1972, 16 U.S.C. 1451 et seq. requires that

"each federal agency conducting or supporting activities directly affecting the coastal zone shall

conduct or support those activities in a manner which is, to the maximum extent practicable,

consistent with approved state management programs." In accordance with Section 307, a

Consistency Determination has been prepared for the proposed construction of the Medium

Diversion at White Ditch (MDWD) project in Plaquemines Parish, Louisiana (Figure 1). This

project was identified as a Near-term Critical Restoration Feature Recommended for Study and

Future Congressional Authorization in the Louisiana Coastal Area (LCA) Main Report dated

January 21, 2005. The project is described in detail in the draft Integrated Feasibility Study and

Environmental Impact Statement for the MDWD, Plaquemines Parish, Louisiana. The proposed

action is located on the left descending bank of the Mississippi River, between the existing

White Ditch diversion siphon to the north (river mile 64.5) and the community of Phoenix to the

south (river mile 59.8) (Figure 2). Coastal Use Guidelines were written in order to implement

the policies and goals of the Louisiana Coastal Resources Program (LCRP), and serve as a set of

performance standards for evaluating projects. Compliance with the LCRP, and therefore,

Section 307, requires compliance with applicable Coastal Use Guidelines.

PURPOSE AND NEED FOR THE PROPOSED ACTION

The altered supply and distribution of freshwater, lack of deltaic forming sediments, marsh

subsistence and human development in the White Ditch area have resulted in degraded and

unbalanced distribution of freshwater, brackish, and saltwater marsh habitats. Further, the

degradation of the existing marshes has made them more vulnerable to the range of Gulf storm

events; extreme and seasonal, resulting in accelerated degradation, altered hydrology changed

salinity regimes.

Installation of the White Ditch diversion siphon was completed in 1963 with the objective of

enhancing muskrat and oyster habitat. In the absence of an outfall management plan, the

surrounding marsh received limited benefits from the diverted river water. Two 50-inch steel

pipes divert water from the Mississippi River through the White Ditch siphon, into the Belair

Canal and then into the River aux Chenes (Oak River), where it continues south and out of the

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project area. Usage of the siphons was abandoned for many years and they degraded into a nonusable condition. The siphons were recently refurbished and water was diverted into White

Ditch as part of research efforts.

Wetlands in the project area are deteriorating for several reasons: 1) subsidence, 2) lack of

sediment and nutrient deposition, 3) erosion via tidal exchange, 4) channelization, 5) saltwater

intrusion, and 6) lack of freshwater. Recent hurricanes and tropical storms have also caused

significant damage to the project area. These activities have resulted in the loss of several

thousand acres of solid, vegetated marsh. Deterioration will continue unless preventative

measures are taken.

In the absence of supplemental freshwater and sediment from the Mississippi River, subsidence,

sea-level rise, wave erosion, and saltwater intrusion will continue to be problems. Protection and

enhancement of this area are dependent on providing a hydrologic and sediment regime that

minimizes the physiological stress to wetland vegetation from saltwater intrusion and tidal

energy and is conducive to the retention of locally provided freshwater and sediments.

The historic hydrology of the project area indicates that the current course of the Mississippi

River has remained the same for the last 700 years and has directly influenced the development

of the entire area. The project area is located on the east side of the Mississippi River and was

formed between two natural levee ridge systems, River aux Chenes on the east and the

Mississippi River on the west. There are also two unnamed bayou ridges found within the

project area. These ridges formed along the old natural bayous which were distributary channels

for the Mississippi River. These natural bayous once carried sediments and nutrients into the

project area during high river stages when the natural ridges were seasonally overtopped.

In the historical setting, floodwater from the river would recede and sediments and nutrients

would be deposited in the inter-distributary basins located between ridges. During normal or

low river stages the ridges along the distributary channels served like levees and buffered the

basin areas from the daily tidal influence. This buffering effect created a low energy freshwater

environment in the inter-distributary basins, forming deep organic soils. Drainage to the area

was provided by a high water event breaching the River aux Chenes ridge in the southern part of

the project area. This event caused the development of the Bayou Garelle tributary channel.

The present day hydrology of the project area has been altered and no longer functions in a

historically natural pattern. Historically, water moved very slowly through the system.

Freshwater slowly exited the system through meandering pathways in the marsh and saltwater

was slow to intrude. Presently, changes in the marsh allow water to rapidly pass through the

system and saltwater is able to quickly intrude. The hydrologic balance within the marsh has

been disturbed due to the following man-made changes:

1. The Mississippi River can no longer overflow its banks into the project area due to the

Mississippi River protection levee. This has eliminated the introduction of freshwater

from the river and disrupted natural sediment deposition patterns.

2. Channels have been dredged through natural ridges which has increased drainage and

tidal exchange and exposed the soil to erosive forces.

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The MDWD project will provide opportunities to naturalize the distribution of freshwater and

deltaic forming sediments—including those necessary for the creation of sustainable marsh

communities, improve hydrologic distribution of freshwater, improve topographic diversity,

reduce the negative impacts of Gulf storm events, and inhibit invasive species in the Breton

Sound Basin.

Figure 1. The Medium Diversion at White Ditch project area and Breton Sound Basin,

Plaquemines Parish, Louisiana.

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Figure 2. The Medium Diversion at White Ditch project area, Plaquemines Parish, Louisiana.

DESCRIPTION OF THE PROPOSED ACTION

The MDWD project study area is located in LCA Subprovince 1 in the Breton Sound hydrologic

basin in Plaquemines Parish, Louisiana (Figure 1). The boundary of the project encompasses

over 98,000 acres of intermediate to brackish intertidal wetland habitats. The study area

boundary follows distinct landscape features beginning in the north with the confluence of the

non-Federal back levee and the forty-arpent canal, extending along the non-Federal back levee,

the Mississippi River levee, the Federal back levee and along the left descending natural bank of

the Mississippi River to the west; past American Bay, California Bay, and through Breton

Sound, near Bay Gardene to the south; into and along River aux Chenes to the east, and back to

the point of beginning. The area has been significantly impacted by recent tropical storms and

hurricanes and is currently isolated from the effects of the Caernarvon freshwater diversion,

located at the northern end of the Breton Sound Basin.

The proposed action involves construction of a structure capable of diverting up to 35,000 cubic

feet per second (cfs), which involves excavating a section of levee and constructing 10 each,

sized 15' x 15', box culverts with hydraulic operated sluice gates replacing the roadway, and

constructing a new outfall channel (i.e., main channel) and enlarging an existing channel (Figure

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3) to carry fresh water and sediment to the desired locations in the receiving marsh. Dimensions

of both the proposed outfall channel and the currently existing receiving channel to be enlarged

are shown in Table 1.

The operating plan for the MDWD project is limited to a diversion pulse of 35,000 cfs in MarchApril of each year, during the normal high flow period of the Mississippi River, and a diversion

of 1,000 cfs the rest of the year. This flow rate may not be experienced over the full 60 day

period. The proposed 35,000 cfs diversion will be the largest man-made diverted flow for

wetland building on the Lower Mississippi River, but the one to two month duration will be a

modifying factor. The diversion should approximate five percent or less of the main channel

flow for most years.

Construction of the 35,000 cfs diversion and associated outfall management features would have

an initial negative direct impact on existing wetland vegetation, wildlife and fisheries resources,

and essential fish habitat within the construction footprint (approximately 283 acres of

intermediate marsh; approximately 363 acres of open water; approximately 5 acres of

bottomland hardwood habitat), primarily through the excavation and enlargement of outfall

channels and placement of excavated material on deteriorating existing marsh and open water

areas adjacent to the channels. However, the beneficial use-placement of excavated dredge

material will provide a base for the regeneration of approximately 385 acres of wetland

vegetation and associated fisheries, wildlife, and essential fish habitat (EFH), and approximately

32 acres of ridge and terrace creation suitable for the re-establishment of bottomland hardwoods.

Operation of the proposed diversion structure would provide an inflow of freshwater, sediments

and nutrients to the project area and support the re-establishment and nourishment of wetland

vegetation in the project area. It is anticipated that a portion of the project area currently

classified as intermediate marsh would be converted to fresh marsh within approximately 5 years

following project implementation. No loss of acreage of all marsh types in the project area is

expected to occur with the proposed diversion. Additionally, the MDWD is expected to produce

an overall gain in marsh acreage of approximately 21,282 acres by year 50 after project

implementation. An increase in wetland acreage would provide increased nesting, rearing, and

foraging habitat for resident and migratory wildlife species. Wetlands creation would also

provide valuable foraging, breeding, and nursery habitat, as well as other essential fish habitat,

for finfish and shellfish in the project area. These changes in the project area would not only

increase the aerial extent of EFH, but would also improve the quality of EFH for several

managed species. Submerged aquatic vegetation (SAV) coverage in the fresh and intermediate

zones of the areas affected by the diversion are expected to increase from 25% (baseline) to

approximately 70%, while in the brackish zone SAV coverage is expected to increase from 25%

to approximately 30%.

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Figure 3. Cross-sectional map of the Medium Diversion at White Ditch, showing both the proposed

main outfall channel and the enlarged existing channel. Channel dimensions at each cross-section are

included in Table 1.

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Table 1. Proposed dimensions for the 35,000 cfs Medium Diversion at White Ditch main outfall channel

and existing receiving channel.

GUIDELINES APPLICABLE TO ALL USES

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These guidelines are acknowledged and have been addressed through the preparation of

responses to the guidelines contained within the specific use categories.

Guidelines 1.1 – 1.6: The guidelines have been read in their entirety, and all applicable

guidelines would be complied with. The proposed project would be in conformance with all

applicable water and air quality laws, standards and regulations, and with those other laws,

standards and regulations which have been incorporated into LCRP, and is deemed in

conformance with the program except to the extent that these guidelines would impose

additional requirements. The proposed activity shall not be carried out or conducted in such a

manner as to constitute a violation of the terms of a grant or donation of any lands or waterbottoms to the State or any subdivision thereof. Information regarding potential impacts of the

proposed action is provided herein and in the accompanying feasibility study and environmental

impact statement.

Guideline 1.7: Potential short- and long-term effects resulting from the diversion project include

increased total suspended sediments, turbidity, and organic/nutrient enrichment of the water

column; disturbance and release of possible contaminants; decrease in water temperatures; and

the possible release of oxygen depleting substances as well as possibly increasing dissolved

oxygen levels. Potential impacts would be minimized, as much as practicable, through the

implementation of stormwater pollution prevention plans (SWPPPs) and other applicable best

management practices (BMPs).

Generally, four water quality conditions could change with implementation of the proposed

diversion:

1) Freshwater would be moved throughout the entire WDMD project area;

2) Salinities would decrease throughout the entire project area;

3) Sediments in the project area would increase allowing for marsh platform development,

along with accompanying minor increases in trace metals associated with bed sediments;

and

4) Nutrients in the project area could increase.

Introduction of river water into the Breton Sound Basin would immediately change the water

chemistry of receiving areas. Change may be beneficial or detrimental, depending on human

perceptions and the water uses. The change from a less fresh to a fresher system could be

perceived as beneficial to wetland nourishment, but detrimental to recreational use because of

water color changes, and possible changes in fish species assemblages in the recreational area.

However, the changes in water chemistry would mimic natural conditions prior to the leveeing of

the Mississippi River. Stabilization of salinity regimes would probably aid resource managers,

commercial and recreational fisheries managers, and water users in making long-term decisions.

Salinity could be either beneficial or detrimental, depending on the user group. Salinity is not

necessarily a pollutant in coastal waters. Freshwater marshes however are sensitive to salinity

levels, but the varying levels of salinity have positive impacts on various commercial and

recreational fisheries. On balance, the stabilization of salinities, or the relocation of saltier water

zones gulfward, would achieve the goals of the MDWD project. The reintroduction of

streambed sediments into the MDWD project area may add some contaminants; these could

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include primarily trace metals and hydrophobic organic compounds from Mississippi River

streambed sediments.

Cumulative impacts to water quality would primarily be related to the incremental impact of all

past, present, and future actions effecting water quality within the Basin such as: increase in

freshwater areas; stabilization or decrease in salinities; increase in sediment introduction to the

coastal zone, with accompanying minor increases in trace metals associated with bed sediments;

increased total suspended sediments; increased turbidity; increased organic/nutrient enrichment

of the water column; disturbance and release of possible contaminants; decrease in water

temperatures along with fewer water temperature fluctuations; and increased dissolved oxygen

levels. However the cumulative impacts to the water quality of the Breton Sound Basin resulting

from this project would be a synergistic positive result over and above the additive combination

of impacts and benefits of the other alternatives.

Any increases in suspended solids and turbidity levels due to dredging related activities in the

immediate project area would be minor, temporary, and highly localized.

No adverse alteration or destruction of unique or valuable habitats, critical habitat for

endangered species, important wildlife or fishery breeding or nursery areas, designated wildlife

management or sanctuary areas, or forestlands is anticipated. No adverse cumulative or

secondary impacts to the biological productivity of wetland ecosystems are anticipated. Adverse

disruptions of coastal wildlife and fishery migratory patterns are not anticipated.

No adverse alteration or destruction of public parks, shoreline access points, public works,

designated recreation areas, scenic rivers, or other areas of public use and concern is anticipated.

No increases in the potential for flood, hurricane or other storm damage, or increases in the

likelihood that damage will occur from such hazards are anticipated.

No significant economic impacts on the locality or adverse disruptions of existing social patterns

would occur due to the proposed action. No cultural, historical, or recreational resource sites

would be impacted by construction. No proximal areas of special concern exist. No land loss,

erosion, or subsidence would occur. This project would not result in reduced long-term

biological productivity of the coastal ecosystem.

Guidelines 1.8 – 1.10: Acknowledged. Perceived adverse impacts listed above would clearly be

outweighed by the human and environmental benefits the MDWD project would provide through

the naturalization of the distribution of freshwater and deltaic forming sediments—including

those necessary for the creation of sustainable marsh communities, improvements to hydrologic

distribution of freshwater, improvements to topographic diversity, reduction in negative impacts

of Gulf storm events, and the inhibition of invasive species in the Breton Sound Basin.

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GUIDELINES FOR LEVEES

Guidelines 2.1 – 2.6: The proposed action would not involve the building of levees.

GUIDELINES FOR LINEAR FACILITIES

Guidelines 3.1 – 3.16: Acknowledged. Portions of the proposed diversion outfall channel will

utilize a currently existing ditch/canal, which will reduce the length of newly constructed linear

channel needed for the project and minimize adverse impacts to wetlands associated with

channel excavation. Material excavated during construction of the main outfall channel (i.e., the

linear facility) will be used to restore and create marsh and ridge habitat in the presently

deteriorating wetlands and open water areas adjacent to the proposed channel.

The proposed main outfall channel will improve natural hydrologic and sediment transport

patterns, sheet flow, and water quality, and will positively benefit the receiving wetlands and

associated fish and wildlife habitat, in the MDWD project area and Breton Sound Basin.

GUIDELINES FOR DREDGED MATERIAL DEPOSITION

Guideline 4.1: Dredged materials removed during excavation and enlargement of the diversion

outfall channels would be deposited in a manner that would avoid disruptions of water

movement, flow, circulation and quality. Dredged material deposition is not expected to result

in significant or persistent water quality impacts in the vicinity of construction activities. Any

minor increases in suspended sediment and turbidity levels during dredged material deposition

would be temporary and highly localized. Minor reductions in dissolved oxygen levels

associated with dredged material deposition would be temporary.

Guideline 4.2: Dredged materials removed during excavation and enlargement of the diversion

outfall channels will be used beneficially to provide a base for the regeneration of approximately

385 acres of wetland vegetation and associated fisheries, wildlife, and essential fish habitat

(EFH), and approximately 32 acres of ridge and terrace creation suitable for the re-establishment

of bottomland hardwoods. There are no nearby existing disposal areas or upland areas that could

be practicably used.

Guideline 4.3: Dredged materials will not be disposed of in a manner which could result in the

impounding or draining of wetlands or the creation of development sites.

Guideline 4.4: Approximately 283 acres of presently eroding wetlands will be impacted

primarily through the excavation of outfall channels and placement of excavated material on

adjacent deteriorating intermediate marsh. However, the beneficial use-placement of these

excavated materials will provide a base for the regeneration of approximately 385 acres of

emergent marsh vegetation and associated fisheries, wildlife, and essential fish habitat (EFH),

and approximately 32 acres of ridge and terrace creation suitable for the re-establishment of

bottomland hardwoods. Additionally, the MDWD is expected to produce an overall gain in

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marsh acreage of approximately 21,282 acres by year 50 after project implementation.

Guidelines 4.5 – 4.6: Acknowledged.

Guideline 4.7: Not applicable.

GUIDELINES FOR SHORELINE MODIFICATIONS

Guidelines 5.1 – 5.9: Acknowledged.

GUIDELINES FOR SURFACE ALTERATIONS

Guidelines 6.1 – 6.14: Acknowledged. Surface alterations in the proposed project’s

construction footprint (approximately 283 acres of intermediate marsh; approximately 363 acres

of open water; approximately 5 acres of bottomland hardwood habitat) will mainly entail the

excavation of a new outfall channel, enlargement of an existing channel for improved

conveyance, and placement of excavated material on deteriorating existing marsh. However, the

beneficial use-placement of dredged material will produce approximately 385 acres of marsh

platform for regeneration or colonization of emergent vegetation and associated fisheries,

wildlife, and essential fish habitat (EFH), and approximately 32 acres of ridge and terrace

creation suitable for the re-establishment of bottomland hardwoods.

GUIDELINES FOR HYDROLOGIC AND

SEDIMENT TRANSPORT MODIFICATIONS

Guidelines 7.1 – 7.9: Acknowledged. The MDWD is designed to introduce fresh water to

control salinities. The controlled diversion will also convey sediment and nutrients to the

marshes of the MDWD project area and elsewhere in the Breton Sound Basin to enhance fish

and wildlife habitat and productivity, and offset land loss. The operating plan for the MDWD

takes advantage of sediment-rich high-river stages flowing through the structure, with a

proposed diversion pulse of 35,000 cfs in March-April of each year, during the normal high flow

period of the Mississippi River, and a diversion of 1,000 cfs the rest of the year.

GUIDELINES FOR DISPOSAL OF WASTES

Guidelines 8.1 – 8.9: The proposed action would not involve the disposal of wastes; therefore,

these guidelines are not applicable.

GUIDELINES FOR USES THAT RESULT IN THE ALTERATION

OF WATERS DRAINING INTO COASTAL WATERS

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Guideline 9.1: The proposed action will minimally affect water quality and flows in the

Mississippi River, while providing benefits to the environment of the Breton Sound Basin

through the diversion of fresh water, sediments, and nutrient inputs that should enhance fish and

wildlife habitat and productivity, and reduce land loss.

Guidelines 9.2 – 9.3: Not applicable.

GUIDELINES FOR OIL, GAS, AND OTHER MINERAL ACTIVITIES

Guidelines 10.1 – 10.14: The proposed action would not involve oil, gas, and other mineral

activities; therefore, these guidelines are not applicable.

CONSISTENCY DETERMINATION

The proposed Medium Diversion at White Ditch will provide additional freshwater, nutrients,

and fine sediments to the area between the Mississippi River and the River aux Chenes ridges.

The proposed action will restore and maintain ecological integrity, including habitats,

communities, and populations of native species, and the processes that sustain them by reversing

the trend of degradation and deterioration in the project area, so as to contribute towards

achieving and sustaining a larger coastal ecosystem that can support and protect the

environment, economy, and culture of southern Louisiana and thus contribute to the economy

and well-being of the Nation. Based on this evaluation, the U. S. Army Corps of Engineers,

New Orleans District, has determined that the proposed action is consistent, to the maximum

extent practicable, with the State of Louisiana's Coastal Resources Program.

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Coordination Letter

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Appendix G

Responses to Comments

683

Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-1 September 2010

1. Your statement of support is noted.

1

685
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Final Integrated Feasibility Study / SEIS G-2 September 2010

686
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-3 September 2010

1. Concur in Part: The Corps agrees that the namingschemes for each project could cause confusion to thoseunfamiliar with the project details. However, since LCAauthorization is tied to WRDA 2007 which references theproject by a specific name, we must keep that namingconvention to avoid unnecessary legislative actions thatcould delay the project. The Corps will begin to anecdotallyrefer to the LCA project as being located in the Phoenixvicinity when discussing it with the public or otherinterested parties. The operation of White Ditch will becoordinated with the existing and new CWPPRA projects.2. Concur: The Corps' preliminary hydraulic modeling of theproject area determined that 35,000 cfs approximated themaximum flow that could be introduced to the project areawithout overtopping the River aux Chenes ridges. During thePED phase, additional survey and hydraulic modeling will beundertaken and these efforts may result in further refinements tothe project design or operating plan.3. Concur: Text has been corrected in the Final EIS.4. The different diversion alternative sizes would have similarvelocities in areas where there are channel improvements to bemade. This is a product of planned design. There was a targetrange of velocity to keep sediments moving while not erodingthe existing channels. For the different diversion alternatives,the proposed dredging and excavation of channels was done withthis in mind yielding similar velocities for the different sizediversions.

12

34

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1. Comment is noted.

1

688
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-5 September 2010

1. Your statement of support is noted.

1

689
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-6 September 2010

1. Your statement of support is noted.

1

690
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-7 September 2010

1. Your statement of support is noted.

1

691
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-8 September 2010

1. Your statement of support is noted.

1

692
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-9 September 2010

1. Your statement of support is noted.

1

693
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-10 September 2010

694
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-11 September 2010

1. A copy of the DEIS has been sent to the Seminole Tribe ofFlorida as per their request.

1

695
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-12 September 2010

1. Your statement of support is noted.

1

696
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-13 September 2010

697
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-14 September 2010

1. Your statement of support is noted.2. Concur in Part: The document has been revised to change allreferences to this model to the "ERDC-SAND2 model".3. Inconsistencies have been resolved where possible. RevisedWVA numbers and impacted acres have been included at the endof Appendix B.4. Your concern is noted. We may revisit the organizationalstructure and format during plan revision during PED.

1

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Final Integrated Feasibility Study / SEIS G-15 September 2010

5. Concur. Text added.6. Response: The AM Framework Team believes that the use ofLandsat Imagery is an appropriate method for monitoring thisobjective. The utilization of Landsat imagery is proposed primarily dueto the frequency of collection (up to six times per year), and for costefficiency. DOQQs do provide better spatial resolution, howevercollection of DOQQs at more frequent time intervals may beprohibitively expensive. The belief that Landsat images do not showchanges well is debatable. Spectral and temporal resolution of theseLandsat data actually provide the opportunity for change detectiontechniques which may not be possible with DOQQs. Additionally, thenext satellite in the Landsat Program, scheduled for launch inDecember 2012, will carry a panchromatic band at 15m spatialresolution. This band enables panchromatic sharpening of the other 8spectral bands, providing the value of increased spectral resolution,while improving the spatial resolution.7. Response: In preparation of the Fisheries sections, the bestavailable data was used to develop the existing conditions analysis.Based on the analysis, best professional judgement was used to definethe predicted impacts. During PED, ECO-SIM models will be used tofurther analyze the predicted effects of the project on fisheriesresources, including commercial species such as oysters. If impacts aresignificantly different that those described within this document, then aNEPA document may be prepared as appropriate. Although fisheriesresources were not considered in the objectives of the project, thesepopulations may be monitored before and after project completion.Since the primary objective of the project is marsh creation andrestoration of natural deltaic processes, the results of fisheriesmonitoring will not necessarily influence the operational regime of thestructure.

56789

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Final Integrated Feasibility Study / SEIS G-16 September 20108. Response: We concur. Language was changed to clarify thatvegetation sampling will be performed yearly beginning in PED fortwo years, during three years of construction, and ten years postconstruction.9. Concur. Language revised to better reflect the concern over excessnutrients. Definition of risk endpoint and other applicable AM termshave been added to section 4.2.10. Response: The LCA AM Framework team agrees with yourconcern and explanation. The effects of freshwater, sediment, andnutrient inputs from diversions on below ground biomass is debated inthe scientific literature. The White Ditch Diversion project yields anopportunity to more closely examine this relationship. Although datagathered on below ground biomass may inform diversion operations,that data will not be the only data utilized to inform decisions ondiversion operations. This issue will be more closely investigatedduring the plan revision during PED. As previously stated in theresponse to Page 1, Section 1,the USACE and State will continue tocoordinate with federal agencies during the PED plan revision toaddress this issue.11. Response: The AM Framework Team understands and agrees withmany of the concerns relating to water hyacinth and believes this isprimarily an O&M issue. However, the PMs do not believe eliminatingthis monitoring is a valid option due to intense public concerns overwater hyacinth. This issue can be further discussed and refined duringthe plan revision in PED.

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12. The 1,328,580 cubic yards of sediment represents an approximatedthreshold required to meet LCA Program goal of No Net Loss. It isthe approximate minimum amount of sediment needed to offset thecurrent rate of relative sea level rise. Identification of this minimumand clear establishment of it as a goal was necessary to facilitate thedecision on overall size of diversion structure and capacity of theoutfall canal. The issue of sediment distribution within the marsh is arelated but distinctly separate topic. The methods described in thecomment will be considered as potential monitoring methods foradaptive management purposes during the PED phase. The Objectivewill not be revised. The LCA AM Framework team agrees that thesetypes of analyses could be valuable. These analyses are complicated,but not impossible, for project areas obscured by vegetation structure.Because Landsat imagery is already proposed for utilization in thismonitoring and adaptive management plan, this additional informationcan be easily evaluated relatively economically. If the PDT determinesthis information is necessary, then it can be added during planmodification during PED.13. The 1,328,580 cubic yards of sediment represents an approximatedthreshold required to meet LCA Program goal of No Net Loss. It isthe approximate minimum amount of sediment needed to offset thecurrent rate of relative sea level rise. Identification of this minimumand clear establishment of it as a goal was necessary to facilitate thedecision on overall size of diversion structure and capacity of theoutfall canal. The amount of sediment required is directly related torelative sea level rise and the 2 cannot be separated. The objective willnot be split.14. Response: This supporting information need was eliminatedbecause it does not directly relate to Objective 1. In discussion with thePM, changes in fish and wildlife resources are not a project objective,and therefore it is not necessary to monitor fish and wildlife. Thisadditional monitoring can be reconsidered during PED.15. See response to comment #14 above.

1213141516

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Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-18 September 201016. Concur: Both CWPPRA projects have the potential for overlapwith the LCA project. Close coordination is necessary to ensure eachproject is developed properly and is consistent with the most probableoutcomes for future-without-project conditions. The LCA team willengage NRCS and EPA to give them an update on the LCA project.

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Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-19 September 2010

17. Non-Concur: Despite the significant impacts that could occur tothe coastal wetlands of Louisiana due to the BP oil spill, it is notrecommended that restoration projects be put on hold indefinitely untila damage assessment can be made. The problems facing coastalLouisiana have not changed since the spill and the LCA White Ditchrecommended plan offers tremendous flexibility for operationdepending on the needs of the estuary. Coastal restoration efforts mustproceed ahead as quickly as possible to design and construct featuresand get them operational. Time lost due to a re-analysis of spill effectswill only prolong the construction of restoration features.18. The Corps is working with the National Park Service to delist thisproperty and is currently waiting for direction from NPS. The evidencewe are using is contained in a report titled Archaeological Research tLocate and Identify the French “Fort on the Mississippi” 16PL27(1700 -1707), Plaquemines Parish, Louisiana.

19. See above response.20. Consultation on this issue begin with the DEIS and coordinationhas occurred since.

17181920

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Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

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21. SHPO has until July 25 to respond to our determination ofeffect and eligibility. Recent conversations with SHPO indicatethat there will be no problem.(Letter from SHPO dated 21 July 2010 concurred with thefindings of the cultural resources report is reproduced at the endof this appendix)

21

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Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-21 September 2010

705
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-22 September 2010

1. Concur: Formal consultation has been initiated with theUSFWS. CEMVN letter requesting the initiation of formalconsultation was submitted on July 15, 2010. USFWS responseletter starting formal consultation was received on July 16, 2010.

1 706
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-23 September 2010

707
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-24 September 2010

708
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-25 September 2010

709
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-26 September 2010

1. Scoring noted. Additional information has been provided inthe Final SEIS.2. Your statement of support is noted.

2

1

710
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-27 September 2010

3. Concur.

3

711
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-28 September 2010

712
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-29 September 2010

713
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-30 September 2010

714
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-31 September 2010

715
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-32 September 2010

716
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-33 September 2010

717
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-34 September 2010

718
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-35 September 2010

719
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-36 September 2010

4. Concur. The sentence on Page ES-11 has been reworded tostate, "...no evaluated alternative is able to entirely offset thehigh rate of sea-level rise."

4

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Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-37 September 2010

5. The sentence should read "are currently being studied andduring the PED phase this information along with all otherpertinent Water Quality information will be used to developmonitoring plans and determine what the operational scheme forthe proposed diversion".6. Response: Improving water quality is not a stated objectiveof the White Ditch project. However, excess nutrification is arisk endpoint and nutrient monitoring is proposed. The concernfor atrazine, metals and other pollutants are noted; however, theAdaptive Management Framework Team does not know howmonitoring information on these parameters would yield anyadaptive management actions. This additional monitoring can bereconsidered during PED.7. Section 5.3.2.2.1 was revised to more accurately andadequately explain the anticipated changes to salinity regimesbased on the year long modeling run. Figure 4.1 shows habitatchanges over the past century. Figure 4.2 shows the existinghabitat in the Breton Sound Area. A year long WVA analysiswas not possible due to time constraints. Even if a WVA hadbeen used predict habitat changes based on the year long run, itwould difficult to accurately predict where these would occur.Therefore a map of predicted changes will not be included.Changes in isohaline lines are also very difficult to accuratelypredict and could vary every year. The regime modeled was oneof a multitude that could have been considered. It could bemisleading to include a map of isohaline lines based solely onone operating scenario. In fact, it is likely that actual operationregimes would be different than those modeled. Structureoperations could be managed to achieve specific results.

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Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

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722
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Final Integrated Feasibility Study / SEIS G-39 September 2010

723
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Final Integrated Feasibility Study / SEIS G-40 September 2010

724
Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-41 September 2010

1. Comment is noted. The Corps will continue to work with theLADNR-OCPR and other State and Federal agencies during thePED phase of the project to identify and evaluate opportunitiesto avoid or minimize adverse impacts to EFH.2. Concur: The document will be updated to include thephrasing "Fishery modeling and habitat change modeling will beperformed during the PED phase. The cost and schedule for thiswill be incorporated into the PMP being developed by the Corpsfor the PED Phase. At this time a SOW is being developed aspart of the Donaldsonville to the Gulf project to look a variousmodels and develop a white paper on the best use of them. Theintent of these models is to support adaptive management of thisproject." 1

2

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Appendix G: Responses to Comments Volume VI – Medium Diversion at White Ditch

Final Integrated Feasibility Study / SEIS G-42 September 2010

3. Concur. The document has been edited to reduce or eliminateinconsistencies in terminology and labeling where possible.4. Concur: The suggested change has been incorporated into thereport document5. Concur. A summary of the sea level rise effects has beenadded to Page 2-5 as a contributing factor to wetland loss anddeterioration.

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6. Concur. Additional information on the design of flowconstrictors (now relabeled as notched weirs) has been added tothe text of the document.7. Revised WVA numbers and acres affected have been addedto Appendix B of the final document.8. Response: Section 1.3 of Appendix I states the intention ofthe USACE to engage NOAA/NMFS and other federal resourceagencies as participants in the adaptive management program forthis project. This engagement will include the selection of exactlocations for sampling sites. The Adaptive ManagementFramework Team is not clear as to how this additionalmonitoring information will guide adaptive managementdecisions. Therefore, it has not been added. This additionalmonitoring can be reconsidered during PED.9. Revised WVA numbers and acres affected have been addedto Appendix B of the final document.

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10. Dissolved oxygen levels throughout the project area arehighly variable and dependent on many factors. Fieldmonitoring protocols and techniques will be established in amonitoring plan developed cooperatively with appropriatestakeholders. This plan will address dissolved oxygen alongwith a multitude of other parameters within the projectboundaries. Pre-project DO levels will be captured during PEDto establish a baseline for adaptive management.11. Additional text has been added to Section 4.2.9 of the finaldocument.12. Concur: Text has been revised.13. The text referred to by the comment was removed Section5.3.1.5.1. Salinity is discussed in much more detail in thefollowing Section 5.3.2. 5.3.2.2.1 was revised to moreaccurately and adequately explain the anticipated changes tosalinity regimes.14. Pre-project monitoring would be scheduled during the PEDphase of the project. This will allow for modeling and loadingcalculations for nutrients and other parameters determined to beof value to the project. This will be included in the monitoringplan developed cooperatively with appropriate stakeholders toensure the best data is collected to aid in the adaptivemanagement of the project.

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15. The last bullet on dissolved oxygen was removed from thefinal document.16. Model results demonstrated that the results of the MarchApril pulse were fairly equivalent within the project arearegardless of the size of the diversion. The 5,000cfs diversion,with supplementary flows from the Caernarvon diversion, canfreshen the vast majority of the Breton Sound (0.0 - 5.0 ppt) aseffectively as the 35,000 cfs diversion. The difference betweenthe alternatives is seen outside of the project area where there isa difference in the distance freshwater moves out into the Bretonsounds before being diluted by saltwater. Further modeling tobetter analyze this extent for the Recommended Plan arescheduled during PED to allow for better adaptive managementof the diversion.17. The MDWD team did not have enough time to fullydescribe the complete cumulative and synergistic effects of allrelevant diversion projects. However; there is a separate LCAstudy that is scheduled to look at managing all the diversions onthe lower river together in a fashion that will minimize impactsto navigation while reestablishing a healthy delta. Due to thesize and scope of this effort, it is not realistic for the MDWDPDT to analyze such a project, but rather to have a separatestudy that will aide all current and upcoming ecosystemrestoration projects along the Lower Mississippi River.18. Concur. Additional detail concerning the timing of shortterm adverse impacts is provided in the revised WVAassessment documentation included at the end of Appenidix B.

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19. A total of 363 acres of open water habitat will be impactedby the ridge creation, marsh creation, and construction of outfallchannels. That open water is assumed to have 25% SAVcoverage which would amount to 91 acres of SAV habitat.Under FWP, 652 acres of fresh/intermediate open water exists atTY50 with 70% SAV coverage which amounts to 456 acres ofSAV habitat.20. Concur: Text has been revised in the Final EIS to betterreflect the impact on fishery resources in the constructionfootprint.21. Concur: Text has been revised in the Final EIS to provideadditional detail on the anticipated impact of flow constrictors(now referred to as "notched weirs" in the document) on aquaticresources.22. Concur: The document will be updated to include thephrasing "Fishery modeling and habitat change modeling will beperformed during the PED phase. The cost and schedule for thiswill be incorporated into the PMP being developed by the Corpsfor the PED Phase. At this time a SOW is being developed aspart of the Donaldsonville to the Gulf project to look a variousmodels and develop a white paper on the best use of them. Theintent of these models is to support adaptive management of thisproject."23. Comment is noted.

1920212223

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1. Your statement of support is noted.

1

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1. Chapter 3 and Section 3.5 specifically deal with why therecommended plan was chosen. Chapter 4 and 5 describeexisting conditions and anticipated impacts. Appendix Ldescribes in detail the engineering of the design. In essence, alarge diversion can be run for a short duration and achieve thegoals of the project while avoiding the scenario described in thecomment. Hydraulic modeling shows that a smaller diversionhas to be run for a much longer duration than a large diversion.It is the length and timing of diversion operations, not the size ofthe diversion, that have potential to cause the scenario described.The short march/april pulse of a large diversion coordinated withoptimal river conditions greatly minimizes potential impacts tosocioeconomic resources. The results of detailed modeling andanalysis lead us to respectfully disagree with this comment.Regardless, the comment is appreciated

1

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1. Your statement of opposition is noted. Dredging and directplacement of river sediments was considered in the early stagesof project planning but was eliminated from more detailedconsideration for reasons of efficiency as noted in Table 3.3 ofthe Draft EIS.

1

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1. Comment is noted.

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1. Your statement of concern is noted. However the schedulefor the LCA 6 projects was extremely accelerated and did notallow time for extensions without risking loss of authorization.

1

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1. Your statement of support is noted.

1

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2. Response: The AM Framework Team does not believe thatnatural channel formation vs. constructed conveyance channel isan adaptive management component. This is a decision that willfurther explored by the PDT during PED. 2

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1. Your statement of opposition is noted.

1. Your statement of support is noted.

1

1

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1. Comment is noted.

1

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1. Confirmation from NCRS that no prime farmland will beimpacted by the proposed project and copy of AD 1006 withSection II completed.

1

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1. Comment on cultural resources report submittal indicatingthat the project location exists beyond their scope of interests andtherefore no impacts to tribal assets are anticipated.

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1. The SHPO concurs with the findings in the LA Division ofArcheology Report No. 22-3516, Management Summary: PhaseI Cultural Resources Investigations of the White Ditch DiversionArea, Plaquemines Parish, Louisiana, R. Christopher Goodwinand Associates, Inc.

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Appendix H

Value Engineering Study Report

A Summary of the Value Engineering Study report

is listed below. Additional technical information

and data is on file and available on request.

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Value Engineering Study Report

Medium Diversion at White Ditch

Prepared by Value Management Strategies, Inc.

June 2009

Medium Diversion at White Ditch

Presently, loss of area in the marsh allows water to rapidly pass through the system and salt water is able

to quickly intrude. The absence of an outfall management plan related to the White Ditch diversion

siphon results in the surrounding marsh receiving limited benefits from the diverted river water. Also, the

lack of marsh-forming sediments from the Mississippi River has accelerated the degradation of all marsh

types. Sediment needs in the project area are extensive and plan strategies that increase diversion flows to

provide required sediment transport may not be sufficient to provide the necessary sediment.

Key VE alternatives identified to address these issues are as follows:

• Maximize sediment introduction

− Design diversion structures to maximize sediment introduction

− Install sediment introduction system into White Ditch diversion structure

• Diversion control structure size and location

− Construct a combination spillway with capacity controls to medium diversion levels

− Construct diversion structure approximately seven miles south of Phoenix

• Address fresh water source and transport

− Optimize flow conveyance in White Ditch to feed areas immediately adjacent to the south of

existing channel

General/Plan Formulation

• Develop Plan Strategies that account for much higher levels of global sea level (GSL) rise

One issue addressed by the VE team spans all three projects and has ramifications throughout the

LCA program. Currently, work is underway by the USACE, National Oceanic and Atmospheric

Administration (NOAA), and United States Geological Survey (USGS) to investigate the glacial

melt contribution to future GSL rise. Project benefits depend upon habitats maintained above sea

level. Consequently, benefits beyond the 50-year planning horizon will be lost if subsidence and

GSL rise exceed the current assumptions. The rate of GSL rise in the future is currently unknown,

but could be much greater than the current assumptions. As such, the projects should develop

specific Plan Strategies that consider the range of possible future GSL rates.

• Provide clarification and address the Water Resources Development Act of 2007 (WRDA 2007)

regarding specified authorized funding limits and the extent of planning development of LCA

projects

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Each LCA project has a specific level of funding to accomplish the authorized project goals and

objectives as described in the LCA Program. However, during the plan formulation phase of the

studies, stipulations (cost and/or size, as well as time) should not serve as planning constraints.

Consideration of all reasonable alternatives to achieve the goals and objectives of the project,

regardless of the time, cost, and/or size, is required by USACE policy. The USACE policy

guidance requires identification of a National Ecosystem Restoration (NER) plan that maximizes

ecosystem restoration benefits compared to costs, in addition to the identification of a Tentatively

Select Plan (TSP). In some cases, the NER plan may differ from the TSP by exceeding the

authorization stipulations resulting in time, cost, and/or size serving as constraints for the plan

selection phase of the study. This forces the TSP to be an alternative that would accomplish the

ecosystem benefits within the WRDA authorization.

SUMMARY OF VE ALTERNATIVE CONCEPTS

The table below summarizes all of the alternative concepts developed by the VE team. The items in red

text were identified by the VE team as items of particular note and key recommended strategies for the

Project Development Team (PDT) to consider.

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SUMMARY OF VE ALTERNATIVE CONCEPTS

Medium Diversion at White Ditch

Number Description

Medium Diversion at White Ditch

WD-1 Design diversion structures to maximize sediment introduction

WD-2 Optimize quantity of freshwater diverted at White Ditch in combination with other

proposed diversion projects

WD-3 Construct diversion structure approximately seven miles south of Phoenix

WD-4 Construct a combination spillway with capacity controls to medium diversion levels

WD-5 Install sediment introduction system into White Ditch diversion structure

WD-6 Optimize flow conveyance in White Ditch

WD-7 Identify and incorporate impacts effects of subsidence due to fluid withdrawal into project

analysis

General/Plan Formulation

G-1 Develop Plan Strategies accounting for rise in sea level

G-2 Provide clarification and address the WRDA 2007 regarding specified authorized

funding limits and the extent of planning development of LCA projects

G-3 Define plan alternatives that can be optimized within project authorization

G-4 Amend project authorizations to include additional federal funding for “first phase”

adaptive management measures

G-5 Establish permanent trust fund for project maintainability

G-6 Identify impacts of multiple diversion structures on Mississippi River and fresh water and

sediment requirements of project areas

G-7 Incorporate comprehensive monitoring of project benefits before, during, and after

completion of diversion measures

G-8 Identify and address potential real and perceived drainage impact of proposed diversion

flows

G-9 Redefine project constraints versus project issues

G-10 Revisit weighted matrix method of ranking initial alternatives and plan elements

G-11 Redefine structural versus non-structural items

G-12 Develop salt tolerant bald cypress variety for use in coastal swamp restoration efforts

G-13 Use Ascension Parish wastewater effluent to replenish cypress forests

G-14 Use self-regulating tide gates for flap gates

G-15 Consider using vinyl sheet pile in guide levees for proposed diversion outlet channels

G-16 Consider effects of nutria in project analysis

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Appendix I

Monitoring and Adaptive Management Plan

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Louisiana Coastal Area (LCA) Program:

Medium Diversion at White Ditch Project

Feasibility-Level Monitoring

and Adaptive Management Plan

September 2010

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TABLE OF CONTENTS

Page

1.0 INTRODUCTION .................................................................................................................... 1

1.1 Authorization for Adaptive Management in the LCA Program ........................................... 1

1.2 Procedure for Drafting Adaptive Management Plans for LCA Projects .............................. 1

1.3 LCA Communication Structure for Implementation of Adaptive Management .................. 3

2.0 PROJECT ADAPTIVE MANAGEMENT PLANNING ......................................................... 4

2.1 Project Goals and Objectives................................................................................................ 5

2.2 Management and Restoration Actions.................................................................................. 5

2.3 Conceptual Ecological Model for Monitoring and Adaptive Management.......................... 5

2.4 Sources of Uncertainty.......................................................................................................... 6

3.0 RATIONALE FOR ADAPTIVE MANAGEMENT................................................................ 6

3.1 Adaptive Management Program for the Medium Diversion at White Ditch Project ........... 7

4.0 MONITORING......................................................................................................................... 7

4.1 Rationale for Monitoring ...................................................................................................... 8

4.2. Monitoring Plan for the Medium Diversion at White Ditch Project ................................... 9

4.2.1 Monitoring Procedures................................................................................................. 11

4.2.2 Use of Monitoring Results and Analysis ..................................................................... 13

5.0 DATABASE MANAGEMENT ............................................................................................. 13

5.1 Description and Location........................................................................................................ 13

5.2 Data Storage and Retrieval ................................................................................................. 14

5.3 Analysis, Summarizing, and Reporting .............................................................................. 14

6.0 ASSESSMENT....................................................................................................................... 14

6.1 Assessment Process ............................................................................................................ 14

6.2 Variances and Success ........................................................................................................ 14

6.3 Frequency of Assessments.................................................................................................. 15

6.4 Documentation and Reporting ............................................................................................ 15

7.0 DECISION MAKING ............................................................................................................ 15

7.1 Decision Criteria ................................................................................................................. 16

7.2 Potential Adaptive Management Measures ........................................................................ 16

7.3 Project Close-Out................................................................................................................ 17

8.0 COSTS FOR IMPLEMENTATION OF MONITORING AND ADAPTIVE

MANAGEMENT PROGRAMS................................................................................................... 17

8.1 Costs for Implementation of Monitoring Program ............................................................. 17

8.2 Costs for Implementation of Adaptive Management Program........................................... 19

9.0 LITERATURE CITED ........................................................................................................... 20

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List of Figures

Figure 1. Set-up Phase of the LCA Adaptive Management Framework.

Figure 2. Implementation Phase of the LCA Adaptive Management Framework.

Figure 3. LCA Communication Structure for Implementation of Adaptive Management.

List of Tables

Table 1. Preliminary Cost Estimates for Implementation of the Monitoring Program for the LCA

Medium Diversion at White Ditch Project.

Table 2. Preliminary Cost Estimates for Set-up of Adaptive Management Program for the LCA

Medium Diversion at White Ditch Project.

Table 3. Preliminary Cost Estimates for Implementation of Adaptive Management Program for

the LCA Medium Diversion at White Ditch Project.

List of Attachments

Annex 1. LCA Medium Diversion at White Ditch Project Conceptual Ecological Model

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1.0 INTRODUCTION

This document outlines the feasibility level monitoring and adaptive management plan for the

Louisiana Coastal Area (LCA) Medium Diversion at White Ditch project. The LCA Adaptive

Management Framework Team developed this monitoring and adaptive management plan with

assistance from the Project Delivery Team (PDT). This plan identifies and describes the

monitoring and adaptive management activities proposed for the Medium Diversion at White

Ditch Project and estimates their cost and duration. This plan will be further developed in the

preconstruction, engineering, and design (PED) phase as specific design details are made

available.

1.1 Authorization for Adaptive Management in the LCA Program

The LCA Ecosystem Restoration Study Chief’s Report (2005) states (for the 15 near-term

features aimed at addressing the critical restoration needs)

“ ...the feasibility level of detail decision documents will identify specific sites, scales,

and adaptive management measures, and will optimize features and outputs necessary to

achieve the restoration objectives...to ensure that LCA ecosystem restoration objectives

are realized, monitoring and adaptive management must be a critical element of LCA

projects.”

Section 7003(a) of Water Resources Development Act of 2007 (WRDA 2007) stipulates:

“The Secretary may carry out a program for ecosystem restoration, Louisiana Coastal

Area, Louisiana, substantially in accordance with the report of the Chief of Engineers,

dated January 31, 2005.”

Additionally, Section 2039 of WRDA 2007 directs the Secretary of the Army to ensure that,

when conducting a feasibility study for a project (or component of a project) for ecosystem

restoration, the recommended project includes a plan for monitoring the success of the ecosystem

restoration. The implementation guidance for Section 2039, in the form of a CECW-PB Memo

dated 31 August 2009, also requires that an adaptive management plan be developed for all

ecosystem restoration projects.

At the programmatic level, knowledge gained from monitoring one project can be applied to

other projects. Opportunities for this type of adaptive management are common within the LCA,

Ecosystem Restoration Study (USACE 2004), which also builds upon lessons learned in other

related efforts such as the Coastal Wetlands Planning, Protection and Restoration Act

(CWPPRA). Oversight by the LCA Science and Technology (S&T) Program and the LCA

Adaptive Management Planning Team provides the basic structure to ensure that knowledge

gained is effectively shared across programs and projects.

1.2 Procedure for Drafting Adaptive Management Plans for LCA Projects

The U.S. Army Corps of Engineers, Mississippi Valley Division, New Orleans District (USACE

MVN), Louisiana Office of Coastal Protection and Restoration (OCPR), and the LCA S&T

Office collaborated to establish a general framework for adaptive management to be applied to

all LCA projects. The framework for adaptive management is consistent with the previously

mentioned implementation guidance, as well as with the guidance provided by the U.S. Fish and

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Wildlife Service (USFWS) and the National Oceanic and Atmospheric Administration's

(NOAA) "Availability of a Final Addendum to the Handbook for Habitat Conservation Planning

and Incidental Take Permitting Process” in Federal Register vol. 65, No. 106 35242. The LCA

adaptive management framework includes both a set-up phase (Figure 1) and an implementation

phase (Figure 2).

Figure 1. Set-up Phase of the LCA Adaptive Management Framework.

Figure 2. Implementation Phase of the LCA Adaptive Management Framework.

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1.3 LCA Communication Structure for Implementation of Adaptive Management

To execute an adaptive management strategy for the LCA Ecosystem Restoration Study, a

communication structure has been identified (Figure 3). The structure establishes clear lines of

communication between LCA Program Management, an Adaptive Management Planning Team,

the S&T Program, PDTs and stakeholders. Successful implementation will require the right

resources being coupled at the right time to support the framework components.

Figure 3. LCA Communication Structure for Implementation of Adaptive Management.

As part of the LCA Program communication structure for implementation of adaptive

management (Figure 3), an LCA Adaptive Management Planning Team will be established. This

team will be led jointly by a Senior Planner from the USACE and a counterpart from the OCPR.

Other team members include USACE and State support staff and representatives from USFWS,

NOAA, Natural Resources Conservation Service (NRCS), and Louisiana Department of Wildlife

and Fisheries (LDWF). These members will be selected on the basis of their knowledge of

ecosystem restoration, coastal Louisiana ecosystems and adaptive management. Other resources

and expertise will be brought in as needed. This team will be responsible for recommending

project and program adaptive management actions to the LCA Management Team.

The LCA Science and Technology (S&T) Program was established by the USACE and the State

of Louisiana (the non-Federal sponsor) to effectively address coastal ecosystem restoration needs

and to provide a strategy, organizational structure, and process to facilitate integration of science

and technology into the adaptive management process. Under the Adaptive Management

Framework, there are five primary elements in the LCA S&T Program, and each element differs

in emphasis and requirements. These elements include: (1) science information needs, (2) data

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acquisition and monitoring, (3) modeling, (4) research, and (5) data management and reporting

(assessment).

Under the LCA S&T Program, an Assessment Team will be established. This team will be led by

the S&T Director and a representative of the U.S. Geological Survey (USGS) who will also

serve as direct liaisons between the S&T Assessment Team and the LCA Adaptive Management

Planning Team. Other members will be identified from Federal and State agencies.

Responsibilities of this team include analysis and reporting of data to the LCA Adaptive

Management Planning Team and the LCA Program Management Team.

2.0 PROJECT ADAPTIVE MANAGEMENT PLANNING

Specific LCA PDTs assisted the LCA Adaptive Management Framework Team in developing

the monitoring and adaptive management plan for each specific project. The members of the

Adaptive Management Framework Team for this project were Tomma Barnes, USACE-MVN;

Steve Bartell, E2 Consulting Engineers; Laura Brandt, USFWS; Craig Fischenich,

USACE/Engineer Research and Development Center; Barbara Kleiss, USACE Mississippi

Valley Division; Carol Parsons Richards, OCPR; Greg Steyer, USGS National Wetlands

Research Center; and John Troutman, OCPR.

The resulting adaptive management plan for the Medium Diversion at White Ditch project

describes and justifies whether adaptive management is needed in relation to the tentatively

selected plan (TSP) identified in the Feasibility Study. The plan also identifies how adaptive

management would be conducted for the project and who would be responsible for this projectspecific adaptive management program. The developed plan outlines how the results of the

project-specific monitoring program would be used to adaptively manage the project, including

specification of conditions that will define project success.

The Adaptive Management Plan for this project reflects a level of detail consistent with the

project Feasibility Study. The primary intent was to develop monitoring and adaptive

management actions appropriate for the project’s restoration goals and objectives. The specified

management actions permit estimation of the adaptive management program costs and duration

for the project.

The following adaptive management plan section (1) identifies the restoration goals and

objectives identified for the Medium Diversion at White Ditch project, (2) outlines management

actions that can be undertaken to achieve the project goals and objectives, (3) presents a

conceptual ecological model that relates management actions to desired project outcomes, and

(4) lists sources of uncertainty that would recommend the use of adaptive management for this

project. Subsequent sections describe monitoring, assessment, decision-making, and data

management in support of adaptive management.

The level of detail in this plan is based on currently available data and information developed

during plan formulation as part of the feasibility study. Uncertainties remain concerning the

exact project features, monitoring elements, and adaptive management opportunities.

Components of the monitoring and adaptive management plan, including costs, were similarly

estimated using currently available information. Uncertainties will be addressed in the

preconstruction, engineering, and design (PED) phase, and a detailed monitoring and adaptive

management plan, including a detailed cost breakdown, will be drafted as a component of the

design document.

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2.1 Project Goals and Objectives

During initial stages of project development, the project delivery team, with stakeholder input,

developed restoration goals and objectives to be achieved by the Medium Diversion at White

Ditch project. These goal and objectives were subsequently refined through interactions with the

LCA Adaptive Management Framework Team. The overarching goal of this project is to restore

and maintain ecological integrity, including habitats, communities, and populations of native

species, and the processes that sustain them, by reversing the trend of degradation and

deterioration in the area between the Mississippi River and the River aux Chenes ridges. The

intent is to contribute towards achieving and sustaining a larger coastal ecosystem that can

support and protect the environment, economy, and culture of southern Louisiana and thus

contribute to the economy and well-being of the Nation. The specific restoration objectives of

the Medium Diversion at White Ditch project are to:

• Maintain the current area of marsh habitat, of all types (41,206 acres), which

provide life-requisite habitat conditions for native coastal marsh fish and wildlife.

• Restore adequate freshwater and nutrient inputs into the project area such that

sustainable areas of fresh, intermediate, brackish, and saline marsh are present and

existing areas of marsh acres are maintained.

• Restore sediment inputs into the into the project area equivalent to an average of

approximately 1,328,580 cubic yards of sediment per year.

2.2 Management and Restoration Actions

The PDT performed a thorough plan formulation process to identify potential management

measures and restoration actions that address the project objectives. Many alternatives were

considered, evaluated, and screened in producing a final array of alternatives. The PDT

subsequently identified a tentatively selected plan (TSP).

The TSP is Alternative 4, which is also the National Ecosystem Restoration (NER) plan. This

alternative is located at Phoenix, Louisiana and includes ten 15-foot x 15-foot box culverts

capable of diverting up to 35,000 cfs. Additionally, 31 acres of ridge and terrace creation, 385

acres of marsh creation utilizing dredged material from an adjacent 223 acres of canal being

reconfigured to convey freshwater, nutrient and sediments. The NER Plan has a primary

operating regime of a maximum 35,000 cfs pulse during March and April with a maximum 1,000

cfs maintenance flow throughout the remainder of the 12-month cycle (May–February). Optional

operating regimes include a maximum 35,000 cfs pulse from March through May with a

maximum 1,000 cfs maintenance flow throughout the remainder of the 12-month cycle (June–

February) and a maximum 35,000 cfs pulse in March with a maximum 1,000 cfs maintenance

flow throughout the remainder of the 12-month cycle (April–February).

2.3 Conceptual Ecological Model for Monitoring and Adaptive Management

As part of the planning process, members of the Medium Diversion at White Ditch project PDT

developed a conceptual ecological model to represent current understanding of ecosystem

structure and function in the project area, identify performance measures, and help select

parameters for monitoring (Annex 1). The model illustrates the effects of important natural and

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anthropogenic activities that result in different ecological stressors on the system. The effects of

concern can be measured for selected performance measures defined as specific physical,

chemical, and biological attributes of the system.

2.4 Sources of Uncertainty

Adaptive management provides a coherent process for making decisions in the face of

uncertainty. Scientific uncertainties and technological challenges are inherent with any largescale ecosystem restoration project. Below is a list of uncertainties associated with restoration of

the coastal wetland systems included in the Medium Diversion at White Ditch project.

• Ability of hydrologic model to predict project impacts/benefits

• Ability of Wetland Value Assessment (WVA) model to predict project impacts/benefits

• Ability of Modified Boustany model to predict project impacts/benefits

• Unknown sediment quantities in river

• Response of ecosystem to pulsed and/or sustained freshwater, sediment, and nutrient

inputs

• Correct engineering and design to address project objectives

• Correct operational regime to achieve project objectives

Potential climate change issues, such as sea level rise, in addition to regional subsidence rates are

significant scientific uncertainties for all LCA projects. These issues were incorporated in the

plan formulation process and will be monitored by gathering data on water levels, salinities, and

land elevation. These data will inform adaptive management actions, but future climate change

projections remain highly uncertain at this time.

3.0 RATIONALE FOR ADAPTIVE MANAGEMENT

The primary incentive for implementing an adaptive management program is to increase the

likelihood of achieving desired project outcomes given the identified uncertainties. All projects

face uncertainties with the principal sources of uncertainty including (1) incomplete description

and understanding of relevant ecosystem structure and function, (2) imprecise relationships

between project management actions and corresponding outcomes, (3) engineering challenges in

implementing project alternatives, and (4) ambiguous management and decision-making

processes.

Given these uncertainties, adaptive management provides an organized, coherent, and

documented process that suggests management actions in relation to measured project

performance compared to desired project outcomes. In the case of the Medium Diversion at

White Ditch, the adaptive management program will use the results of continued project

monitoring to manage the diversion in order to achieve the previously stated project goals and

objectives. Adaptive management establishes the critical feedback of information from project

monitoring to inform project management and promote learning through reduced uncertainty.

Several questions were considered to determine whether adaptive management should be applied

to the Medium Diversion at White Ditch project:

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1) Are the ecosystems to be restored sufficiently understood in terms of hydrology and

ecology, and can project outcomes be accurately predicted given recognized natural and

anthropogenic stressors?

2) Can the most effective project design and operation to achieve project goals and

objectives readily identified?

3) Are the measures of this restoration project performance well understood and agreed

upon by all parties?

4) Can project management actions be adjusted in relation to monitoring results?

A ‘NO’ answer to questions 1–3 and a “YES” answer to question 4 qualifies the project as a

candidate that could benefit from adaptive management. The Framework Team and the PDT

decided that the project meets these qualifications, and, therefore, is a candidate for adaptive

management.

For this project, there are a number of uncertainties associated with ecosystem function and how

the ecosystem components of interest will respond to the restoration project. In addition, there

are associated uncertainties about the best design and operation for the project. Using an adaptive

management approach during project planning provided a mechanism for building flexibility into

project design and for providing new knowledge to better define anticipated ecological

responses. This also enabled better selection of appropriate design and operating scenarios to

meet the project objectives. Additionally, an adaptive management approach will help define

project success and identify outcomes that should realistically be expected for the project.

3.1 Adaptive Management Program for the Medium Diversion at White Ditch

Project

An Adaptive Management Program for the Medium Diversion at White Ditch project is needed

to ensure proper implementation of adaptive management. The Program will also facilitate

coordination of projects within the LCA Program and coordination among PDTs, the LCA S&T,

and LCA Program Management. The LCA Adaptive Management Planning Team will lead all

LCA project and program adaptive management recommendations and actions. This team is

responsible for ensuring that monitoring data and assessments are properly used in the adaptive

management decision-making process. If this team determines that adaptive management actions

are needed, the team will coordinate a path forward with project planners and project managers.

Other PDT members may be solicited as needed; for instance, if the adaptive management

measure is operational, operations and hydraulics representatives might be asked to participate.

The LCA Adaptive Management Planning Team is also responsible for project documentation,

reporting, and external communication. Table 2 lists the cost estimates for these adaptive

management activities.

4.0 MONITORING

Independent of adaptive management, an effective monitoring program will be required to

determine whether the project outcomes are consistent with original project goals and objectives.

The power of a monitoring program developed to support adaptive management lies in the

establishment of feedback between continued project monitoring and corresponding project

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management. A carefully designed monitoring program is central component of the project

adaptive management program.

4.1 Rationale for Monitoring

Monitoring must be closely integrated with all other LCA adaptive management components

because it is the key to the evaluation and learning components of adaptive management. Project

and system level objectives must be identified to determine appropriate indicators to monitor. In

order to be effective, monitoring designs must be able to distinguish between ecosystem

responses that result from project implementation (i.e., management actions) and natural

ecosystem variability. In coastal Louisiana, there are many existing restoration and protection

projects already constructed, and many more are being planned under different authorizations

and programs. In combination, these projects will ultimately influence much of coastal

Louisiana. Monitoring must therefore be conducted across a range of carefully selected scales to

assess short-term project performance and to characterize longer-term, system-wide trends and

conditions.

Achieving monitoring objectives will require monitoring that focuses on different spatial and

temporal scales. Spatially, a project might achieve local objectives, but have little or no

measurable effect at larger scales. Temporally, monitoring designs need to consider the amount

of time it could take for slowly changing ecological variables to respond to management actions.

Additionally, monitoring should be designed to measure the persistence of near-term effects.

Larger-scale effects will generally take longer to develop and longer to detect than more

localized effects.

Monitoring for large scale effects can be more difficult than for local effects because the

ecological linkages become more complicated as factors outside project boundaries influence

processes and biota that affect desired project outcomes. The benefits of improved habitat in one

location may be counteracted by degradation at another location, thus showing no overall benefit

at large scales. In addition, monitoring at large scales can involve changes in underlying

conditions over time or space and be very labor intensive. When possible, specific monitoring

and large scale information needs should be interrelated. In some cases, large scale monitoring

may be just an extension of local monitoring in space and time, but it may also involve designs

and procedures that are separate from site specific monitoring and extend beyond the purview of

the project teams.

When possible, specific monitoring and large scale information needs should be integrated with

existing monitoring efforts that are underway in coastal Louisiana. For example, the CWPPRA

program has been monitoring restoration and protection projects in coastal Louisiana since 1990

(Steyer and Stewart 1992, Steyer et al. 1995). The monitoring program incorporates a systemlevel wetland assessment component called the Coast-wide Reference Monitoring System

(CRMS-Wetlands, Steyer et al. 2003). CRMS-Wetlands provides system-wide performance

measures that are evaluated to help determine the cumulative effects of restoration and protection

projects in coastal Louisiana. LCA monitoring plans will incorporate existing monitoring

networks to the extent practicable and participate in the implementation of CRMS-Wetlands.

Such participation can maintain the data consistencies necessary to conduct project and

programmatic adaptive management.

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4.2. Monitoring Plan for the Medium Diversion at White Ditch Project

According to the CECW-PB Memo dated 31 August 2009, “Monitoring includes the systemic

collection and analysis of data that provides information useful for assessing project

performance, determining whether ecological success has been achieved, or whether adaptive

management may be needed to attain project benefits.” The following discussion outlines key

components of a monitoring plan that will support the project Adaptive Management Program.

The plan identifies performance measures along with desired outcomes (i.e., targets) in relation

to specific project goals and objectives. A performance measure includes specific feature(s) to be

monitored to determine project performance. In addition, if applicable, a risk endpoint was

identified. Risk endpoints measure undesirable outcomes of a management or restoration action.

A monitoring design was established to determine whether the desired outcome or risk endpoint

is met.

Upon completion of the Medium Diversion at White Ditch project, monitoring for ecological

success and adaptive management will be initiated and will continue until ecological success is

achieved, as defined by the project-specific objectives. This monitoring plan includes the

minimum monitoring actions to evaluate success and to determine adaptive management needs.

Although the law allows for a 10-year cost-shared monitoring plan, ten years of monitoring may

not be required. Once ecological success has been achieved, which may occur in less than ten

years post-construction, no further monitoring will be performed. If success cannot be

determined within that 10-year period of monitoring, any additional monitoring will be a nonFederal responsibility. This plan estimated monitoring costs for a period of ten years because that

is the maximum allowed federal contribution to monitoring. As soon as ecological success is

achieved, monitoring will cease.

The following discussion outlines key components of a monitoring plan that will support the

LCA Medium Diversion at White Ditch project Adaptive Management Program. The plan

identifies performance measures along with desired outcomes and monitoring designs in relation

to specific project goals and objectives. Additional monitoring is identified as supporting

information needs that will help further understand and corroborate project effects.

Objective 1: Maintain the current area of marsh habitat, of all types, that provide life-requisite

habitat conditions for native coastal marsh fish and wildlife.

Performance Measure 1: Habitat and land:water classification

Desired Outcome: Reduce the rate of land loss (10-year post-construction trend) compared to

the pre-project condition (1985–2012), excluding tropical storm events.

Desired Outcome: Maintain and/or increase acreage of marsh habitats from pre-construction

estimates (41,206 acres).

Monitoring Design: Habitats will be classified using Landsat Thematic Mapper (TM) scenes

collected in 3 pre- and 10 post-project years and Digital Orthophoto Quadrangles (DOQQs) for 1

pre- and 2 post-project years, as well as any available field data in the study area to assess

land:water trends and habitat distribution.

Objective 2: Restore adequate freshwater and nutrient inputs into the project area such that

sustainable areas of fresh, intermediate, brackish, and saline marsh are present and existing areas

of marsh acres are maintained.

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Performance Measure 2a: Plant diversity and cover

Desired Outcome: Enhance floristic quality of marsh vegetation communities.

Monitoring Design: Permanent vegetation monitoring stations will be established for assessing

project area vegetation communities. These stations will be sampled annually beginning in PED

for two years, during three years of construction, and ten years post construction.

Supporting Information Need: Salinity and hydroperiod (the period of time during which the

wetland is covered by water, also known as frequency and duration of inundation) will be

assessed by establishing 9 hydrologic monitoring sites in project and reference areas.

Risk Endpoint: Nutrification

Desired Outcome: Excessive nutrient introductions do not contribute to reduced biomass of

belowground plant material when compared to pre-construction estimates.

Monitoring Design: Belowground biomass will be sampled quarterly at the 9 vegetation sites.

These stations will be sampled for 3 years prior to project completion to assess pre-project

conditions and sampled for 10 years post-construction. Nutrients (total nitrogen [TN], ammonia,

nitrate+nitrite, total phosphorous [TP]), metals, atrazine, and dissolved oxygen will be measured

every two months in the immediate project outfall channel and at the 9 hydrologic monitoring

sites for 3 years prior to project completion to assess pre-project conditions and sampled for 10

years post-construction.

Desired Outcome: Mississippi River water introductions do not contribute to expansion of

floating aquatic vegetation (water hyacinth) in project area when compared to pre-construction

estimates along with not increasing the occurrences of water use impairments in the receiving

waters.

Monitoring Design: The distribution of water hyacinth throughout the project area will be

tracked by visual assessment of water hyacinth cover from overflights during summer.

Objective 3: Restore sediment inputs into the into the project area equivalent to an average of

approximately 1,328,580 cubic yards of sediment per year.

Performance Measure 3a: Annual sediment discharge

Desired Outcome: Deliver 1.328M yard3 (equivalent to 1.422M tons) of sediment through the

White Ditch diversion each year.

Monitoring Design: Hourly turbidity recorders will be deployed in the outfall channel and at 9

hydrologic monitoring sites and correlated to total suspended solids (TSS) to investigate this

measure. The sites will be measured for 3 years prior to project completion to assess pre-project

conditions and sampled for 10 years post-construction.

Performance Measure 3b: Accretion and elevation

Desired Outcome: Maintain marsh elevation within tidal frame (relative sea level rise = 0 cm

yr1).

Monitoring Design: Surface elevation tables (SET)/feldspar stations will be sampled at 9

hydrologic monitoring sites for assessing project area accretion and marsh elevation changes for

3 years prior to project completion to assess pre-project conditions and sampled for 10 years

post-construction.

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4.2.1 Monitoring Procedures

The following monitoring procedures will provide the information necessary to evaluate the

previously identified project objectives for the Medium Diversion at White Ditch project:

Land:Water and Habitat Classification: Land/water and habitat summaries will be performed

on classified Landsat TM scenes for 1985, 1987, 1990, 1998, 1999, 2001, 2002, 2004, 2005,

2006, 2008, 2009, 2010, 2011, and 2012 in the project area. Linear regression will be used to

calculate land change trends based on those years, excluding anomalous data. Post-project trends

calculated from Landsat TM scenes classified annually will be compared to the pre-project

trends to determine whether conversion of land to open water is being reduced in the project

area. DOQQs of the project area will need to be flown and habitat analyses completed to capture

land cover for one pre-construction and two post-construction years.

Hydrology: Hourly turbidity, salinity, dissolved oxygen and water-level water monitoring will

be initiated 3 years prior to anticipated project construction completion and conducted for 10

years post-construction at six locations within the project area and three reference locations with

multi-parameter water quality sondes. Sondes will be surveyed to a vertical datum (NAVD 88),

and marsh elevations in the immediate vicinity of each sonde will also be surveyed. Sondes will

be serviced approximately 9 times per year. Hydroperiod metrics (depth, duration, and frequency

of flooding) will be obtained from marsh elevations and recorded water levels. TSS will be

predicted from turbidity measurements as described below.

Sediment Input and Distribution: Sediments introduced into the project area via riverine input

are expected to contribute to soil building and thus a net elevation increase or stabilization.

Water discharge through the diversion structure will be monitored hourly with an acoustic

Doppler current meter (ADCM). Hourly turbidity measurements will be measured with a logging

optical backscatter nephlometric turbidity sensor, which will be field serviced and calibrated

each month. During each field servicing event, a depth-integrated water sample will be taken

from the outfall channel, and the sample will be analyzed for total suspended solids (TSS) by

filtering 100–250 mL of each sample through pre-rinsed, pre-ashed, pre-weighed 47mm GF/F

microfiber filters. Filters will be dried for 24 hours at 105° C, then combusted for 1 hour and

550° C and weighed. Thus, the inorganic fraction of TSS will be used as the metric for

suspended solids in diverted river water. Linear regression will be used to estimate the

relationship between turbidity and TSS, and hourly turbidity data will then be used to obtain

hourly TSS values. Instantaneous sediment flux through the diversion structure fluxed will be

calculated as

fluxsed = qdiv × tss

where qdv and tss are the volume discharge and suspended sediment concentrations in the outfall

channel, respectively. Total sediment delivery Q over the time interval 0–T will be determined

as

where t is time.

Distribution of diverted sediments through the project area will be assessed by collection of

hourly turbidity time series at each hydrologic monitoring site (above) by affixing an optical

0

T

Q flux dt = sed

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backscatter nephlometric turbidity sensor to each water quality sonde. Water samples will be

collected during monthly servicing of the sensors, and these samples will be analyzed for TSS

and used to calibrate the turbidity sensors to TSS.

Water Quality: Measuring and monitoring various water quality parameters, including salinity,

nutrients, turbidity, metals, atrazine, and total suspended solids (TSS) will dictate whether inputs

from the Mississippi River are impacting water quality in the project area. Nutrients (TN,

ammonia, nitrate+nitrite, TP) will be measured every two months in the immediate project

outfall channel and at 9 hydrologic monitoring sites. Water samples will be collected in 500 mL

acid-washed polyethylene bottles, stored on ice and taken to laboratory for processing. Within 24

hrs, 60 mL from each water sample will be filtered through pre-rinsed 25 mm 0.45 μm Millipore

filters. Samples and filters will be frozen until analyzed within one month of collection. Nitrate

and nitrite will be determined separately using automated cadmium reduction method,

ammonium by automated phenate method and phosphate by automated ascorbic acid reduction

method (Standard Methods 1992). Metals will be analyzed using the EPA SW-846 7000 series

for analysis of metals is water. Atrazine will be analyzed using the EPA 600 series for the

analysis of Atrazine in water.

Sediment Accretion and Elevation: Sediment accretion and elevation will be assessed at the

nine hydrologic monitoring sites (above) semi-annually, beginning 3 years prior to anticipated

project construction completion. Sediment elevation within the project area will be measured

over time by using the rod-surface elevation table (RSET) technique which is described in Folse

et al. (2008) and references therein. The RSET allows for precise, repeated measurements of the

soil elevation. Marker horizons consisting of feldspar clay will be used to determine vertical

accretion/loss within the project area (Folse et al. 2008).

Vegetation: Vegetation sampling will occur annually at the nine hydrologic monitoring sites

(above), beginning in PED for two years, during three years of construction, and ten years post

construction. Sampling will occur annually between August and October at each site, and will

consist of sampling ten replicate 2 m x 2 m stations located along a transect within a 200 m x 200

m square. Vegetation stations will be located randomly on a 282.8-m transect that cuts

diagonally through the square from one corner to the opposite corner. Each 2 m x 2 m vegetation

station shall be spaced a minimum of 3 m apart giving a possible 94 establishment points along

the diagonal transect.

Species composition and percent cover for each station will be determined using visual estimates

of cover following the Braun-Blanquet cover scale (Mueller-Dombois and Ellenburg 1974). The

2 m x 2 m quadrat will be carefully placed on the vegetation and all vegetation within the

quadrat, whether rooted within the station or hanging over the station, will be included in the

sample. Species composition and percent cover data will be used to generate a Floristic Quality

Index (FQI) score (Cretini et al. 2010) which will be tracked over time. Species composition data

will be used to determine in situ marsh habitat classification, which will be used to ground-truth

classifications from Land:Water and Habitat Classification above.

Belowground biomass will be sampled quarterly at the nine hydrologic monitoring sites via 10-

cm diameter cores taken from each of three plots after the aboveground production has been

removed. The cores will be taken to a maximum depth of 50 cm, or the entire mat thickness.

Cores will be divided into 8 cm sections, and washed in a 0.5 mm sieve to remove soil particles.

Live roots and rhizomes will be separated from the remaining matrix of dead roots and other

organic material and dried at 65° C to a constant weight, and weighed.

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4.2.2 Use of Monitoring Results and Analysis

Project monitoring is the responsibility of the OCPR and the USACE. However, because of the

need to integrate monitoring for programmatic adaptive management, extensive agency

coordination is required. A monitoring workgroup, led by the LCA S&T Program and the USGS,

will be responsible for ensuring that project-specific monitoring plans are technically competent

and appropriately integrated within a system-wide assessment and monitoring plan (SWAMP).

The results of the monitoring program will be communicated to an Assessment Team that will

use the information to assess system responses to management, evaluate overall project

performance, and construct project report cards. Recommended modifications (i.e., adaptation)

of the Medium Diversion at White Ditch project will be provided as appropriate.

5.0 DATABASE MANAGEMENT

Database management is an important component of the monitoring plan and the overall

adaptive management program. Data collected as part of the monitoring and adaptive

management plans for the LCA projects will be archived as prescribed in the “LCA Data

Management Strategic Plan” developed for the LCA S&T Office, and further developed by the

LCA S&T Data Management Working Group.

Data standards, quality assurance and quality control procedures and metadata standards will be

prescribed by the LCA S&T Data Management Working Group. Data collected for LCA with

similar data types and collection frequencies as those data collected under the CRMS program

will be managed by the Louisiana Strategic Online Natural Resources Information System

(SONRIS). Pre-existing standard operating procedures built for SONRIS cover issues such as

data upload process and format, quality assurance/quality control, and public data release.

Storage of all other LCA collected data (spatial or non-spatial) will be handled by the LCA

project-specific data libraries on LCA.GOV.

Where applicable, Open Geospatial Consortium standards will be used to facilitate data sharing

among interested parties. Data analysis and reporting responsibilities will be shared between

project assessment and adaptive management efforts in order to provide Medium Diversion at

White Ditch project reports for the LCA Program Management Team.

5.1 Description and Location

The data management plan should identify the computing hardware and any specialized or

custom software used in data management for an adaptive management program. Opportunities

exist to develop either a centralized or distributed data management system. The data managers

with input from the Adaptive Management Planning Team should determine which approach

best suits the needs of the overall adaptive management program.

Individuals with responsibility for data management activities (data managers) in support of an

adaptive management program should be identified. The data managers should collaborate with

the Adaptive Management Planning Team in developing a data management plan to support the

adaptive management program. The data management plan should be incorporated into the

overall program adaptive management plan – either in the main body of the adaptive

management plan or as an appendix.

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5.2 Data Storage and Retrieval

Data standards, quality assurance and quality control procedures and metadata standards will be

prescribed by the Data Management Working Group, and will be complementary with the

CRMS-Wetlands program and SONRIS database. Data will be served using a map services tool,

similar to that currently employed by the CRMS-Wetlands project.

5.3 Analysis, Summarizing, and Reporting

Data analysis and reporting responsibilities will be shared between project and programmatic

adaptive management efforts in order to provide reports for the Medium Diversion at White

Ditch project Assessment Team, project managers, and decision-makers.

6.0 ASSESSMENT

The assessment phase of the framework describes the process by which the results of the

monitoring efforts will be compared to the desired project performance measures and/or

acceptable risk endpoints (i.e., decision criteria) that reflect the goals and objectives of the

management or restoration action. The assessment process addresses the frequency and timing

for comparison of monitoring results to the selected measures and endpoints. The nature and

format (e.g., qualitative, quantitative) of these comparisons are defined as part of this phase. The

resulting methods for assessment should be documented as part of the overall adaptive

management plan.

The results of the Medium Diversion at White Ditch project monitoring program will be

regularly assessed in relation to the desired project outcomes as described by the previously

specified project performance measures. This assessment process regularly measures the

progress of the project in relation to the stated project goals and objectives, and is critical to the

project adaptive management program. The assessments will continue through the life of the

project or until it is decided that the project has successfully achieved its goals and objectives.

6.1 Assessment Process

The Assessment Team assigned to the Medium Diversion at White Ditch project will identify a

combination of qualitative (i.e., professional judgment) and quantitative methods for comparing

the values of the performance measures produced by monitoring with the selected values of these

measures that define criteria for evaluating project effectiveness.

Appropriate statistical comparisons (e.g., hypothesis testing, ANOVA, multivariate methods,

etc.) will be used to summarize monitoring data as they are obtained and compare these data

summaries with the project decision criteria. These continued assessments will be documented as

part of the project reporting and data management system.

6.2 Variances and Success

The project Assessment Team will collaborate with project managers and decision-makers to

define magnitudes of difference (e.g., statistical differences, significance levels) between the

values of monitored performance measures and the desired values (i.e., decision criteria) that will

constitute variances. Meaningful comparisons between monitoring results and desired

performance will require characterization of historical and current spatial-temporal variability

that define baseline conditions. Variances (or their absence) will be used to recommend adaptive

management actions, including (1) continuation of the project without modification, (2)

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modification of the project within original design specifications, (3) development of new

alternatives, or (4) termination of operation of the White Ditch diversion structure.

Conceptual models have been developed for each project describing the linkages between

stressors and performance measures. The assessments will help determine whether the observed

responses are linked to the project. Each project has been formulated to address as many system

stressors as feasible. If the stressors targeted by the project have changed and the performance

measure has not, the linkages in the conceptual model should be examined to determine what

other factors may be influencing the performance measure response.

The assessments will also determine whether the responses are undesirable (e.g., are moving

away from restoration goals) and if the responses have met the success criteria for the project. If

performance measures are not responding as desired because the stressor has not changed

enough in the desired direction, then recommendations should be made concerning modifications

to the project. If the stressor has changed as expected/desired and the performance measure has

not, additional research may be necessary to understand why.

From a system-wide perspective, scientific and technical information would be generated from

the implementation of a system–wide monitoring effort. Information generated from this effort

should be linked to evaluation LCA performance and system response. From a project-level

perspective, monitoring plans should be designed to inform adaptive management decision

making by providing monitoring data that are relevant to addressing uncertainty.

Similarly, for multiple performance measures and corresponding monitoring results, the

Assessment Team will determine the number and magnitude of variances within a single

assessment that will be required to recommend modifications to the project.

6.3 Frequency of Assessments

Ideally, the frequency of assessments for the Medium Diversion at White Ditch project would be

determined by the relevant ecological scales of each performance measure. The project’s

technical support staff will identify for each performance measure the appropriate timescale for

assessment. The project should have a combination of short-, medium-, and long-term

performance measures. Assessments should be performed at a five year interval at a minimum;

however, depending on the timescale of expected responses of the specific measure and

frequency of data collection, it may be determined during PED that more frequent reporting may

be necessary.

6.4 Documentation and Reporting

The Assessment Team will document each of the performed assessments and communicate the

results of its deliberations to the managers and decision-makers designated for the Medium

Diversion at White Ditch project. The Assessment Team will work with the project monitoring

team and monitoring workgroup to produce periodic reports that will measure progress towards

project goals and objectives as characterized by the selected performance measures. The results

of the assessments will be communicated regularly to the project managers and decision-makers.

7.0 DECISION MAKING

Adaptive management is distinguished from more traditional monitoring in part through

implementation of an organized, coherent, and documented decision process. For the Medium

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Diversion at White Ditch project Adaptive Management Program, the decision process includes

(1) anticipation of the kinds of management decisions that are possible within the original project

design, (2) specification of values of performance measures that will be used as decision criteria,

(3) establishment of a consensus approach to decision making, and (4) a mechanism to

document, report, and archive decisions made during the timeframe of the Adaptive Management

Program.

7.1 Decision Criteria

Decision criteria, also referred to as adaptive management triggers, are used to determine

whether and when adaptive management opportunities should be implemented. These criteria are

usually ranges of expected and/or desirable outcomes. They can be qualitative or quantitative

based on the nature of the performance measure and the level of information necessary to make a

decision. Desired outcomes can be based on reference sites, predicted values, or comparison to

historic conditions. Several potential decision criteria are identified below, based on the project

objectives and performance measures. More specific decision criteria, possibly based on other

parameters such as land:water relationship, hydrology, water quality, and sediment accretion and

elevation; vegetation dynamics, will be developed during the pre-construction engineering and

design phase of the project.

Sediment loading requirements:

• Desired sediment loading rates (1.422M tons yr-1) are not achieved

To meaningfully manage this parameter, operations could be adjusted to increase the amount of

sediment being discharged through the White Ditch structure, either by increasing the amount of

river water discharged, or by timing diversions to better coincide with periods of high sediment

concentrations in the Mississippi River.

Vegetation Community Dynamics

• Maintenance of all marsh habitats is not achieved

Operations may need to be adjusted to decrease the amount of river water discharged, or by

timing diversions to better coincide with winter senescence of emergent vegetation. Additional

modeling or experimental efforts might be required to understand and manage observed

responses of belowground biomass.

To manage these outcomes, hydraulic models may need to be revisited and recalibrated based on

field data and observations prior to change in management of a diversion and/or in diversion

structures. Additional modeling or experimental efforts might be required to understand and

manage observed biotic responses.

7.2 Potential Adaptive Management Measures

The project report card, drafted by the Assessment Team, will be used to evaluate project status

and adaptive management needs. The Assessment Team may submit recommendations for

adaptive management actions to the Adaptive Management Planning Team. The Adaptive

Management Planning Team will investigate and further refine adaptive management

recommendations and present them to the Program Management Team. Some potential adaptive

management actions for this project may include modifying the operation of the existing

diversion structure or modifying operation of existing outfall management features.

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7.3 Project Close-Out

Close-out of the project would occur when it is determined that the project has been successful or

when the maximum 10-year monitoring period has been reached. Success would be considered

to have been achieved when the project objectives have been met, or when it is clear that they

will be met based upon the trends for the site conditions and processes. Project success would be

based on the following:

• Maintaining the pre-construction acreage and diversity of marsh types after 10 years.

• Meeting or exceeding 1,328,580 cubic yards of sediment per year into the project area.

There may be issues related to the sustainability of the project that would require some

monitoring and management beyond achieving these objectives. Due to the variable nature of the

Louisiana coastal zone, the monitoring baseline may change during the period of analysis.

Consequently, it may be appropriate to consider extending project specific monitoring and

adaptive management beyond 10 years.

8.0 COSTS FOR IMPLEMENTATION OF MONITORING AND

ADAPTIVE MANAGEMENT PROGRAMS

The costs associated with implementing these monitoring and adaptive management plans were

estimated based on currently available data and information developed during plan formulation

as part of the feasibility study. Because uncertainties remain as to the exact project features,

monitoring elements, and adaptive management opportunities, the costs estimated in Tables 1, 2,

and 3 (below) will be need to be refined in PED during the development of the detailed

monitoring and adaptive management plans.

8.1 Costs for Implementation of Monitoring Program

Costs to be incurred during the PED and construction phases include drafting of the detailed

monitoring plan, monitoring site establishment and pre-construction and construction data

acquisition to establish baseline conditions. Cost calculations for post-construction monitoring

are displayed as a 10-year (maximum) total. If ecological success is determined earlier (prior to

ten years post-construction), the monitoring program will cease and costs will decrease

accordingly.

It is intended that monitoring conducted under the LCA program will utilize centralized data

management, data analysis, and reporting functions. All data collection activities follow

consistent and standardized processes regardless of the organization responsible for monitoring.

Cost estimates include monitoring equipment, monitoring station establishment, data collection,

quality assurance/quality control, data analysis, assessment, and reporting for the proposed

monitoring elements (Table 1). These estimates account for a 2.6% annual inflation rate, adopted

from the CWPPRA Program. The current total estimate for implementing the monitoring and

assessment program is $9,363,400. Unless otherwise noted, costs will begin at the onset of the

PED phase and will be budgeted as construction costs.

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Table 1. Preliminary Cost Estimates for Implementation of the Monitoring Program for

the LCA Medium Diversion at White Ditch Project.

Category Activities

2 yr PED

Set-up &

Data

Acquisition

3 yr

Construction

10 yr PostConstruction Total

Monitoring:

planning and

management

Monitoring

workgroup,

drafting detailed

monitoring plan,

working with

PDTs on

performance

measures

$135,900 $53,200 $210,100 $399,200

Monitoring:

data

collection

Landrights, site

construction,

and surveying

$145,400 $145,400

Land:water $13,500 $21,600 $85,300 $120,400

Habitat

classification

$60,500 $145,000 $205,500

Hydrology $257,800 $412,400 $1,628,200 $2,298,400

Sediment input

& distribution

$37,400 $59,900 $236,300 $333,600

Water Quality $45,700 $73,200 $288,800 $407,700

Sediment

accretion and

elevation

$29,200 $46,700 $184,300 $260,200

Vegetation $145,900 $233,400 $921,600 $1,300,900

Fisheries $374,200 $598,600 $2,363,200 $3,336,000

Database

management

Database

development,

management,

and

maintenance,

webpage

development for

communication

of data to

stakeholders

$62,400 $99,800 $393,900 $556,100

TOTAL $1,247,400 $1,659,300 $6,456,700 $9,363,400

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8.2 Costs for Implementation of Adaptive Management Program

Costs for the project adaptive management program were based on estimated level of effort. The

current total estimate for implementing the adaptive management program is $1,780,000. Unless

otherwise noted, costs will begin at the onset of the PED phase and will be budgeted as

construction costs.

Table 2. Preliminary Cost Estimates for Set-up of Adaptive Management Program

for the LCA Medium Diversion at White Ditch Project.

Category

Annual

Cost 5 yr Total

Detailed AM Plan and Program Set-up

(during PED and construction) $100,000 $500,000

TOTAL $100,000 $500,000

Table 3. Preliminary Cost Estimates for Implementation of Adaptive Management

Program for the LCA Medium Diversion at White Ditch Project.

Category

Annual

Cost 10 yr Total

Management of AM Program (post- construction) $50,000 $500,000

Assessment $47,000 $470,000

Decision making $31,000 $310,000

TOTAL $128,000 $1,280,000

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9.0 LITERATURE CITED

Cretini, K.F., J.M. Visser, K.W. Krauss, and G.D. Steyer. 2010. CRMS Vegetation Analytical

Team Framework: Methods for Collection, Development, and Use of Vegetation Response

Variables. National Wetlands Research Center, Lafayette, LA, 64 p.

Folse, T.M., J.L. West, M.K. Hymel, J.P. Troutman, L. Sharp, D. Weifenbach, T. McGinnis, and

L.B. Rodrigue. 2008. A standard operating procedures manual for the Coast-wide

Reference Monitoring System-Wetlands: methods for site establishment, data collection,

and quality assurance/quality control: Baton Rouge, La., Louisiana Coastal Protection and

Restoration Authority, Office of Coastal Protection and Restoration, 191 p.

Mueller-Dombois, D. and H. Ellenberg 1974. Aims and Methods of Vegetation Ecology. New

York: John Wiley and Sons. 547 pp.

Standard Methods for the examination of water and wastewater. 18th edition, 1992. Greenberg,

A.E., R.R. Trussell, L.S. Clesceri, M.A.H. Franson, eds. American Public Health

Association. Washington D.C.

Steyer, G.D., and R.E. Stewart, Jr. 1992. Monitoring Program for Coastal Wetlands Planning,

Protection, and Restoration Act projects. U.S. Fish and Wildlife Service, National

Wetlands Research Center Open-File Report 93-01. 85 pp.

Steyer, G.D., R.C. Raynie, D.L. Steller, D. Fuller, and E. Swenson. 1995. Quality management

plan for Coastal Wetlands Planning, Protection, and Restoration Act monitoring program.

Open- File Report 95-01. Baton Rouge: Louisiana Department of Natural Resources,

Coastal Restoration Division. 97 pp.

Steyer, G.D., C.E. Sasser, J.M. Visser, E.M. Swenson, J.A. Nyman, and R.C. Raynie. 2003. A

Proposed Coast-wide Reference Monitoring System for Evaluating Wetland Restoration

Trajectories in Louisiana. Environmental Monitoring and Assessment. 81:107–117.

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ANNEX 1. LCA Medium Diversion at White Ditch Project

Conceptual Ecological Model

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TABLE OF CONTENTS

Page

1.0 INTRODUCTION ........................................................................................................A-1

1.1 Conceptual Ecological Model Definition .........................................................A-1

1.2 Purpose and Functions of Conceptual Ecological Models ...............................A-1

1.2.1 Ecosystem Simplification .....................................................................A-1

1.2.2 Communication.....................................................................................A-1

1.2.3 Plan Formulation...................................................................................A-2

1.2.4 Science, Monitoring, and Adaptive Management.................................A-3

1.2.5 Limitations of Conceptual Ecological Models .....................................A-3

1.3 Types of Conceptual Ecological Models ..........................................................A-4

1.3.1 Application of Conceptual Ecological Models to LCA Projects..........A-4

1.3.2 Model Components...............................................................................A-4

2.0 CONCEPTUAL ECOLOGICAL MODEL DEVELOPMENT....................................A-5

2.1 Methodology.....................................................................................................A-5

2.2 Project Background...........................................................................................A-6

2.2.1 Project Goals and Objectives................................................................A-6

2.2.2 Project Description................................................................................A-7

3.0 CONCEPTUAL ECOLOGICAL MODEL DISCUSSION..........................................A-8

3.1 DriversA-8

3.1.1 Anthropogenic Alterations – Altered Hydrology .................................A-8

3.1.2 Exotic and Invasive Species..................................................................A-9

3.1.3 Relative Sea Level Rise ......................................................................A-11

3.2 Ecological Stressors........................................................................................A-11

3.2.1 Decreased Freshwater and Sediments.................................................A-11

3.2.2 Increased Saltwater Intrusion..............................................................A-11

3.2.3 Increased Tidal Prism .........................................................................A-11

3.2.4 Habitat Conversion .............................................................................A-12

3.3 Ecological Effects ...........................................................................................A-12

3.3.1 Increased Submergence ......................................................................A-12

3.3.2 Decreased Wetland Health..................................................................A-12

3.3.3 Increased Wetland Loss ......................................................................A-12

3.3.4 Loss of Navigation..............................................................................A-12

3.4 Attributes and Performance Measures............................................................A-12

3.4.1 Elevation and Accretion......................................................................A-12

3.4.2 Land Cover..........................................................................................A-13

3.4.3 Navigation...........................................................................................A-13

3.4.4 Plant Diversity and Distribution .........................................................A-14

3.4.5 Water Quality......................................................................................A-14

3.4.6 Soil Stability........................................................................................A-15

4.0 LITERATURE CITED ...............................................................................................A-16

LIST OF FIGURES

1. Conceptual Ecological Model Schematic Diagram...........................................................A-5

2. Medium Diversion at White Ditch Project Study Area.....................................................A-8

3. Conceptual Ecological Model, LCA Medium Diversion at White Ditch Project ...........A-10

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1.0 INTRODUCTION

1.1 Conceptual Ecological Model Definition

Although the term “conceptual ecological model” (CEM) may be applied to numerous

disciplines, CEMs are generally simple, qualitative models, represented by a diagram, that

describe general functional relationships among the essential components of an ecosystem.

CEMs typically document and summarize current understanding of, and assumptions about,

ecosystem function. When applied specifically to ecosystem restoration projects, CEMs also

describe how restoration actions propose to alter ecosystem processes or components to improve

system health (Fischenich 2008). To describe ecosystem function, a CEM usually diagrams

relationships between major anthropogenic and natural stressors, biological indicators, and target

ecosystem conditions.

1.2 Purpose and Functions of Conceptual Ecological Models

CEMs can be particularly helpful with the Louisiana Coastal Area (LCA) Program and its

projects by providing assistance with four important tasks: ecosystem simplification,

communication, plan formulation, and science, monitoring and adaptive management.

1.2.1 Ecosystem Simplification

Because natural systems are inherently complex, resource managers must utilize tools that

simplify ecosystem relationships and functions within the target ecosystem. An understanding of

the target ecosystem is paramount to planning and constructing effective ecosystem restoration

projects. During CEM development, knowns and unknowns about the connections and

causalities in the systems are identified and delineated (Fischenich 2008).

CEMs can promote ecosystem simplification through the following processes:

• Organization of existing scientific information;

• Clear depiction of system components and interactions;

• Promotion of understanding of the ecosystem;

• Diagnosis of underlying ecosystem problems;

• Isolation of cause and effect relationships; and

• Identification of species most likely to demonstrate an ecosystem response.

1.2.2 Communication

CEMs are an effective tool for the communication of complex ecosystem processes to a large

diverse audience (Fischenich 2008). It is vitally important that project teams understand

ecosystem function in order to realistically predict accomplishments to be achieved by

restoration projects. CEMs can facilitate effective communication between project team

members about ecosystem function, processes, and problems, and can assist in reaching

consensus within the project team on project goals and objectives.

Because CEMs summarize relationships among the important attributes of complex ecosystems,

they can serve as the basis for sound scientific debate. Stakeholder groups, agency functions

(e.g., planning and operations), and technical disciplines typically relate to systems resource use

and management independently, but CEMs can be used to link these perspectives.

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The process of model development is at least as valuable as the model itself and affords an

opportunity to draw fresh insight as well as address unique concerns or characteristics for a given

project. Workshops to construct CEMs are brainstorming sessions that explore alternative ways

to compress a complex system into a small set of variables and functions. This interactive

process of system model construction facilitates communication between project team members

and almost always identifies inadequately understood or controversial model components.

CEMs can promote communication by facilitating the following:

• Integrating input from multiple sources and informing groups of the ideas, interactions,

and involvement of other groups (Fischenich 2008);

• Assembling project/study managers with the project team and stakeholders to discuss

ecosystem condition, problems, and potential solutions;

• Synthesizing current understanding of ecosystem function;

• Developing consensus on a working set of hypotheses that explain habitat changes;

• Developing consensus on indicators that can reflect project-specific ecological

conditions; and

• Establishing a shared vocabulary among project participants.

1.2.3 Plan Formulation

Formulating a plan for an effective ecosystem restoration project requires an understanding of

the following elements:

• The underlying cause(s) of habitat degradation;

• The manner in which causal mechanisms influence ecosystem components and dynamics;

and

• The manner in which intervening with a restoration project may reduce the effects of

degradation.

These three elements should form the basis of any CEM applied to project formulation

(Fischenich 2008).

CEMs can provide valuable assistance to the plan formulation process through the following:

• Supporting decision-making by assembling existing applicable science;

• Assisting with formulation of project goals and objectives, indicators, management

strategies, and results;

• Providing a common framework among team members from which to develop

alternatives;

• Supplementing numerical models to assess project benefits and impacts; and

• Identifying biological attributes or indicators that should be monitored to best interpret

ecosystem conditions, changes, and trends.

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1.2.4 Science, Monitoring, and Adaptive Management

Through the recognition of important physical, chemical, or biological processes in an

ecosystem, CEMs identify aspects of the ecosystem that should be measured. Hypotheses about

uncertain relationships or interactions between components may be tested and the model may be

revised through research and/or an adaptive management process. Indicators for this process may

occur at any level of organization, including the landscape, community, population, or genetic

levels; and may be compositional (i.e., referring to the variety of elements in a system), structural

(i.e., referring to the organization or pattern of the system), or functional (i.e., referring to

ecological processes) in nature.

CEMs can be helpful in restoration science, monitoring, and adaptive management through the

following:

• Making qualitative predictions of ecosystem response;

• Identifying possible system thresholds that can warn when ecological responses may

diverge from the desired effect;

• Outlining further restoration and/or research and development needs;

• Identifying appropriate monitoring indicators and metrics;

• Providing a basis for implementing adaptive management strategies;

• Interpreting and tracking changes in project targets;

• Summarizing the most important ecosystem descriptors, spatial and temporal scales, and

current and potential threats to the system;

• Facilitating open discussion and debate about the nature of the system and important

management issues;

• Determining indicators for monitoring;

• Helping interpret monitoring results and explore alternative courses of management;

• Establishing institutional memory of the ideas that inspired the management and

monitoring plan;

• Forecasting and evaluating effects on system integrity, stress, risks, and other changes;

• Identifying knowledge gaps and the prioritization of research;

• Interpreting and monitoring changes in target indicators; and

• Assisting in qualitative predictions and providing a key foundation for the development

of benefits metrics, monitoring plans, and performance measures.

1.2.5 Limitations of Conceptual Ecological Models

CEMs cannot identify the most significant natural resources within the target ecosystem or

prioritize project objectives. They do not directly contribute to the negotiations and trade-offs

common to ecosystem restoration projects. CEMs are not The truth, but are simplified depictions

of reality. They are not Final, but rather provide a flexible framework that evolves as

understanding of the ecosystem increases. CEMs are not Comprehensive because they focus only

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upon those components of an ecosystem deemed relevant while ignoring other important (but not

immediately germane) elements. CEMs do not, in and of themselves, quantify restoration

outcomes, but identify indicators that can be monitored to determine responses within the target

ecosystem to restoration outputs.

Good conceptual models effectively communicate which aspects of the ecosystem are essential

to the problem, and distinguish those outside the control of the implementing agency. The best

conceptual models focus on key ecosystem attributes, are relevant, reliable, and practical for the

problem considered, and communicate the message to a wide audience.

1.3 Types of Conceptual Ecological Models

CEMs can be classified according to both their composition and their presentation format. They

can take the form of any combination of narratives, tables, matrices of factors, or box-and-arrow

diagrams. The most common types of CEMs are narrative, tabular, matrix, and various forms of

schematic representations. A comprehensive discussion of these types of CEMs is provided in

Fischenich (2008). Despite the variety in types of CEMs, “no single form will be useful in all

circumstances” (Fischenich 2008). Therefore, it is of vital importance to establish the specific

plan formulation needs to be addressed by the CEM, and develop the CEM accordingly because

“[c]onceptual models . . . are most useful when they are adapted to solve specific problems”

(Fischenich 2008).

1.3.1 Application of Conceptual Ecological Models to LCA Projects

CEMs have been widely used in other regions of North America when planning large-scale

restoration projects (Barnes and Mazzotti 2005). The LCA team has decided to utilize the Ogden

model (Ogden and Davis 1999). The LCA team recognizes that CEM development, like plan

formulation, is likely to be an iterative process, and that CEMs developed for LCA projects

during early plan formulation may be dramatically changed before project construction.

1.3.2 Model Components

The CEM utilized for LCA projects follows the top-down hierarchy of information using the

components established by Ogden and Davis (1999). The schematic organization of the CEM is

depicted in Figure 1 and includes the following components:

• Drivers- This component includes major external driving forces that have large-scale

influences on natural systems. Drivers may be natural (e.g., eustatic sea level rise) or

anthropogenic (e.g., hydrologic alteration) in nature.

• Ecological Stressors- This component includes physical or chemical changes that occur

within natural systems, which are produced or affected by drivers and are directly

responsible for significant changes in biological components, patterns, and relationships

in natural systems.

• Ecological Effects- This component includes biological, physical, or chemical responses

within the natural system that are produced or affected by stressors. CEMs propose

linkages between one or more ecological stressors and ecological effects and attributes to

explain changes that have occurred in ecosystems.

• Attributes- This component (also known as indicators or end points) is a frugal subset of

all potential elements or components of natural systems representative of overall

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ecological conditions. Attributes may include populations, species, communities, or

chemical processes. Performance measures and restoration objectives are established for

each attribute. Post-project status and trends among attributes are measured by a systemwide monitoring and assessment program as a means of determining success of a

program in reducing or eliminating adverse effects of stressors.

• Performance measures- This component includes specific features of each attribute to be

monitored to determine the degree to which the attribute is responding to projects

designed to correct adverse effects of stressors (i.e., to determine success of the project).

Figure 1. Conceptual Ecological Model Schematic Diagram.

This CEM does not attempt to explain all possible relationships or include all possible factors

influencing the performance measure targets within natural systems in the study area. Rather, the

model attempts to simplify ecosystem function by containing only information deemed most

relevant to ecosystem monitoring goals.

2.0 CONCEPTUAL ECOLOGICAL MODEL DEVELOPMENT

2.1 Methodology

A CEM was developed for the Medium Diversion at White Ditch project by members of the

interagency Project Delivery Team. The creation of this CEM was an interactive and iterative

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process. Prior to model development, the project team reviewed existing information on the

ecosystem within the study area. A small team meeting was then convened to identify and

discuss causal hypotheses that best explain both natural and key anthropogenically driven

alterations in the study area. A list of appropriate stressors and consequent ecological effects in

the study area ecosystem was developed from these discussions. Additionally, a series of

attributes was identified that exhibited characteristics that ideally suited them to serve as key

indicators of project success through the measurement and analysis of performance measures

associated with these attributes. The project team used these hypotheses and lists of components

to develop an initial draft of the model and to prepare a supporting narrative document to explain

the organization of the model and science supporting the hypotheses.

Additional information about the components of this CEM is presented below.

2.2 Project Background

The Medium Diversion at White Ditch project was identified as a near-term critical feature in the

Louisiana Coastal Area (LCA), Louisiana – Ecosystem Restoration Study (2004 LCA Plan

[USACE 2004]). The 2004 LCA Plan was recommended to Congress by a Chief of Engineers

report dated January 31, 2005, which recommended a coordinated, feasible solution to the

identified critical water resource problems and opportunities in coastal Louisiana. This project

was included in that plan along with other near-term critical restoration features throughout

coastal Louisiana. Including this project, 10 additional projects were recommended for further

studies, in anticipation that such features would be subsequently recommended for future

Congressional authorization. The 2004 LCA Plan was developed by the State of Louisiana and

the United States Army Corps of Engineers (USACE) in order to implement some of the

restoration strategies outlined in the 1998 report Coast 2050: Toward a Sustainable Coastal

Louisiana.

The purpose of this study is to investigate the feasibility of restoring and maintaining ecological

integrity, including habitats, communities, and populations of native species, and the processes

that sustain them by reversing the trend of degradation and deterioration to the area between the

Mississippi River and the River aux Chenes ridges. This Feasibility Study was authorized by the

2004 LCA Plan and the 2007 Water Resources Development Act (WRDA 2007), which required

the completion of a Feasibility Study and the incorporation of the study findings into a signed

Chief of Engineers Report, which must be submitted to Congress by the Secretary of the Army

by December 31, 2010.

Pursuant to the completion of this Feasibility Study, a CEM was developed to establish causal

hypotheses that best explain the major alterations in the natural systems within the study area, to

identify attributes of the natural system that are likely to exhibit a response to project features,

and to identify performance measures that can be monitored to determine the degree of project

success with respect to countering or correcting the natural system alterations.

2.2.1 Project Goals and Objectives

In consultation with the non-Federal sponsor and other interested parties, Goals and Objectives

were developed in the first quarter of 2009. They are presented in Table 2.1.

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Table 1: Goals and Objectives

Overarching System Goal Objective

Restore and maintain ecological

integrity, including habitats,

communities, and populations of native

species, and the processes that sustain

them by reversing the trend of

degradation and deterioration to the area

between the Mississippi River and the

River aux Chenes ridges, so as to

contribute towards achieving and

sustaining a larger coastal ecosystem that

can support and protect the environment,

economy, and culture of southern

Louisiana and thus contribute to the

economy and well-being of the Nation.

A. Maintain the current area of marsh habitat, of all

types (41,206 acres) that provide life requisite

habitat conditions for native coastal marsh fish and

wildlife.

B. Restore adequate freshwater and nutrient inputs

into the project area such that sustainable areas of

fresh, intermediate, brackish and saline marsh are

present and existing areas of marsh acres are

maintained.

C. Restore sediment inputs into the project area

equivalent to an average of approximately 1,328,580

cubic yards of sediment per year.

2.2.2 Project Description

The Medium Diversion at White Ditch project study area is located in LCA Subprovince 1 in the

Breton Sound hydrologic basin in Plaquemines Parish, Louisiana (see figure 1.1). The boundary

of the project encompasses over 98,000 acres of intermediate to brackish intertidal wetland

habitats. The study area boundary follows distinct landscape features beginning in the north with

the confluence of the non-Federal back levee and the Forty-Arpent Canal, extending along the

non-Federal back levee, the Mississippi River levee, the Federal back levee and along the left

descending natural bank of the Mississippi River to the west; past American Bay, California Bay,

and through Breton Sound, near Bay Gardene to the south; into and along River aux Chenes to

the east, and back to the point of beginning. The area has been significantly impacted by recent

tropical storms and hurricanes and is currently isolated from the effects of the Caernarvon

freshwater diversion, located at the northern end of the Breton Sound basin.

The area of interest where a diversion structure could be located occurs on the left descending

bank of the Mississippi River, between White Ditch to the north (River Mile 64.5 above Head of

Passes [AHP]) and the community of Phoenix to the south (River Mile 59.8 AHP). This 4.7-mile

stretch is unique in that there is no hurricane protection levee (back levee) on the marsh side that

protects existing homes and infrastructure from elevated water levels (tidal or storm surge). The

Mississippi River levee is the only flood protection structure that keeps river water from entering

the project study area. This situation minimizes the amount of infrastructure that could be

affected by construction of a diversion structure and allows for a broader array of measures to be

considered in addressing problems in the project area. The diversion influence area is

approximately 98,000 acres encompassing an estuarine marsh system that has been heavily

influenced by both man-made and natural processes. Channel construction, subsidence, erosion,

saltwater intrusion, and storm-related damages have all significantly altered the natural

environment, causing extensive losses of wetland habitats.

The location selected for the Tentatively Selected Plan is just north of Phoenix, LA. There are no

known structures within the footprint of this area. It runs from the junction of the MR&T levee

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and the Federal back levee to a point approximately 9,200 feet north on the MR&T levee. The

White Ditch Value Engineering team identified this area as a good location to intake sediment

because it is on a point bar. Point bars are locations where sediments drop out of the water

column and settle. It is centrally located within the study area and could yield benefits to the

north and south.

Figure 2. Medium Diversion at White Ditch Project Study Area.

3.0 CONCEPTUAL ECOLOGICAL MODEL DISCUSSION

The CEM developed for the Medium Diversion at White Ditch project is presented in Figure 3.

Model components are identified and discussed in the following subsections.

3.1 Drivers

3.1.1 Anthropogenic Alterations – Altered Hydrology

The historic hydrology of the project area indicates that the current course of the Mississippi

River has remained the same for the last 700 years and has directly influenced the development

of the entire area. The project area is located on the east side of the Mississippi River and was

formed between two natural levee ridge systems, River aux Chenes on the east and the

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Mississippi River on the west. There are also two unnamed bayou ridges found within the project

area. These ridges formed along the old natural bayous which were distributary channels for the

Mississippi River. These natural bayous once carried sediments and nutrients into the project

area during high river stages when the natural ridges were seasonally overtopped.

In the historical setting, floodwater from the river would recede and sediments and nutrients

would be deposited in the inter-distributary basins located between ridges. During normal or low

river stages the ridges along the distributary channels served like levees and buffered the basin

areas from the daily tidal influence. This buffering effect created a low energy freshwater

environment in the inter-distributary basins, forming deep organic soils. Drainage to the area was

provided by a high water event breaching the River aux Chenes ridge in the southern part of the

project area. This event caused the development of the Bayou Garelle tributary channel.

The present day hydrology of the project area has been altered and no longer functions in a

historically natural pattern. Historically, water moved very slowly through the system.

Freshwater slowly exited the system through meandering pathways in the marsh and saltwater

was slow to intrude. Anthropogenic changes in the marsh allow water to rapidly pass through the

system and saltwater is able to quickly intrude. The hydrologic balance within the marsh has

been disturbed due to the following anthropogenic changes:

• The Mississippi River can no longer overflow its banks into the project area due to the

Mississippi River protection levee. This has eliminated the introduction of freshwater

from the river and disrupted natural sediment deposition patterns.

• Channels have been dredged through natural ridges, which has increased drainage and

tidal exchange and exposed the soil to erosive forces.

3.1.2 Exotic and Invasive Species

Water hyacinth is a common invasive species in the Breton Sound Basin. It has already been

demonstrated that areas supplied with freshwater from the river often becomes choked with

dense floating mats of water hyacinth. Water hyacinth can eliminate the ability to utilize all

propeller driven watercraft and can even restrict the mobility of airboats. During large storm

events these floating mats can be picked up and dumped on native marsh vegetation. The result

is that the native vegetation dies and the area is susceptible to erosive forces. Freshwater

introduction by the Medium Diversion at White Ditch project has the potential to improve

conditions for its growth. Opportunities exist to control this incursion through effective

diversion, flexible management, prescribed burns of marsh grass, and chemical control.

Nutria is a common invasive species throughout the project area. Nutria is an introduced rodent

that has proliferated throughout much of southern Louisiana. They are known to decimate marsh

vegetation. Any marsh created by the project would be susceptible to damage by nutria. It may

be necessary to deploy control measures if nutria become a problem in the project area.

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3.1.3 Relative Sea Level Rise

Relative sea level rise consists of eustatic sea level rise combined with subsidence. Eustatic sea

level rise is defined as the global increase in oceanic water levels primarily due to changes in the

volume of major ice caps and glaciers, and expansion or contraction of seawater in response to

temperature changes. Baseline (i.e., recent) eustatic sea level rise in the project area is

approximately 0.75 foot/century. Subsidence is the decrease in land elevations, primarily due to

consolidation of sediments, faulting, groundwater depletion, and possibly oil and gas withdrawal.

Subsidence in the project area is approximately 2.35 feet/century. Relative sea level rise affects

project area marshes by gradually inundating marsh plants. Marsh soil surfaces must vertically

accrete to keep pace with the rate of relative sea level rise or marshes eventually convert to open

water due to the depth of submergence.

3.2 Ecological Stressors

3.2.1 Decreased Freshwater and Sediments

The altered hydrology of the project area results in less freshwater and associated sediment and

nutrients being delivered to marsh vegetation. Lack of freshwater facilitates increased saltwater

intrusion and its associated effects on marsh vegetation. Vertical accumulation of wetland soils is

achieved by accretion of mineral sediment inputs and/or organic accumulation resulting from

above and below-ground plant productivity (DeLaune et al. 1983, DeLaune et al. 1990a). The

survival and productivity of marshes is reliant on these soil-building processes to offset

submergence and sea level rise (DeLaune et al. 1978, DeLaune et al. 1979, DeLaune et al.

1990b). As the natural hydrology of the project area marshes has become short-circuited by

levees and canals, the residence time of the limited freshwater inputs has also decreased. Shorter

residence times result in less settling of suspended sediments and less uptake of nutrients.

3.2.2 Increased Saltwater Intrusion

The altered hydrology of the project area facilitates increased saltwater intrusion and increased

tidal exchange by providing efficient conduits for loss of freshwater and intrusion of saltwater.

Wetland plant species have evolved different levels of tolerance to salinity and respond to

salinity with different mechanisms. Numerous studies have demonstrated that elevated salinity

can negatively affect all wetland species and can contribute to large-scale vegetation dieback

(Chabreck and Linscombe 1982, McKee and Mendelssohn 1989). Storm surge can also be a

mechanism for saltwater intrusion. This form of saltwater intrusion can be particularly

detrimental to areas that have been hydraulically isolated, leading to extended durations of

saltwater inundation.

3.2.3 Increased Tidal Prism

Degrading marsh and anthropogenic influences such as canals have resulted in an increased tidal

prism. Healthy marsh acts like a sponge and slowly releases and absorbs tidal fluctuations.

Impaired marsh cannot effectively slow water tidal movements and therefore there is increased

erosion. Water flows in and out of the marsh at a much faster pace. Significant and immediate

erosion of marsh vegetation and associated soils can occur as a result of tidal fluctuations. Losses

may be more significant in areas that are already under stress from other ecological stressors but

healthy marsh systems can be significantly impacted as well.

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3.2.4 Habitat Conversion

Habitat conversion can be the result of several drivers acting independently or collectively. The

conversion of habitat can make an area more susceptible to storms and erosion as well as altering

the type of fauna expected to occur in the area. Freshwater marsh can be susceptible to saltwater

intrusion. The effects of invasive species can damage or displace native vegetation.

3.3 Ecological Effects

3.3.1 Increased Submergence

Wetland plants employ different physical and/or metabolic mechanisms that enable them to

tolerate and grow in flooded soils. However, in almost all cases plants are dependent on the

maintenance of soil surface elevations to sustain the flooding regime to which they are adapted.

Increases in flooding depth and duration cause stress to plants by altering metabolic function and

negatively impacting productivity, survival, and regeneration. Relative sea level rise in the

project area combined with insufficient accretion results in marsh systems with reduced

productivity, survival, and regeneration due to submergence. Organic matter accumulation is also

reduced, further exacerbating the impacts of submergence.

3.3.2 Decreased Wetland Health

Decreased freshwater, decreased nutrients, decreased residence time, increased saltwater

intrusion, and increased submergence all act to decrease the overall health of the project area

marshes. As marsh plants become stressed by inundation and saltwater intrusion, their

productivity, survival, and regeneration are all negatively impacted. Over time, healthy marshes

gradually decline to more interspersed marshes and eventually convert to open water.

3.3.3 Increased Wetland Loss

Wetland loss in the project area can be the result of gradual decline of marsh vegetation due to

inundation and saltwater intrusion eventually leading to complete loss of marsh vegetation or the

result of storm surge events. As marsh vegetation is lost, underlying soils are more susceptible to

erosion and are typically lost as well, leading to deeper water and precluding marsh regeneration.

Significant accretion of sediments is then required in order for marsh habitat to reestablish.

3.3.4 Loss of Navigation

Navigation can be significantly impaired by the presence of dense mats of water hyacinth. Water

hyacinth can choke canals and open water areas to the point where propeller driven craft are

completely incapable of utilizing once navigable waterways. In some cases the mats can become

so thick that they are even impassable by airboat.

3.4 Attributes and Performance Measures

3.4.1 Elevation and Accretion

Ground surface elevation has been identified as a key indicator of project success with respect to

increasing sediment and nutrient load within the study area. Comparison of pre-project

elevations with post-project elevations would serve to determine whether sediment input and soil

accretion is occurring within the study area in response to project features. A post-project

decrease in the rate of elevation decline would implicitly indicate the introduction of sediment

into the marshes as a result of the project. Two performance measures have been identified for

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this attribute, including surface elevation table measurements and feldspar marker horizon

measurements.

• Surface Elevation Table (SET) measurements provide a constant reference plane in space

from which the distance to the sediment surface can be measured by means of pins

lowered to the sediment surface. Repeated measurements of elevation can be made with

high precision because the orientation of the table in space remains fixed for each

sampling. Elevation change measured by the SET is influenced by both surface and

subsurface processes occurring within the soil profile.

• Feldspar marker horizon measurements involve the placement of a cohesive layer of

feldspar clay on the ground surface. Soil borings are extracted at the marker horizon

location periodically to measure the amount of soil deposition and/or accretion that has

occurred above the horizon since placement. Significant quantities of soil atop marker

horizons are indicative of soil building within the area, which in turn indicates an

increase in relative elevation.

A post-project stabilization of elevation as evidenced by SET measurements or documented soil

accretion atop a marker horizon within the study area would be an indication of significant

project success, while a post-project decrease in the rate of decline in elevation would be an

indication of moderate project success. Conversely, no change in the rate of elevation decline

post-project within the study area would indicate that the project did not succeed in offsetting

subsidence and, by extension, habitat conversion, and future land loss.

3.4.2 Land Cover

Land cover has been identified as a key indicator of project success with respect to preventing,

reducing, or reversing wetland loss in the study area. Comparison of pre-project land cover

characteristics with post-project land cover characteristics would serve to determine whether the

rate of conversion of marsh habitat to open water within the study area declines post-project.

• Spatial analysis has been identified as a performance measure for the determination of

the response of land cover to the proposed project. Spatial analysis may involve

comparative analysis of pre-project and post-project aerial or satellite imagery and may

utilize thematic mapper analysis to determine relative changes in habitat composition

within the study area.

A post-project stabilization in the total area of marsh habitat would be an indication of

significant project success, while a post-project reduction in the rate of marsh loss within the

study area would be an indication of moderate project success. Conversely, no change in the rate

of marsh loss within the study area would indicate that the project did not succeed in preventing

habitat conversion and, by extension, future habitat loss. Concurrently these tools would analyze

navigable waterways in pre- and post -project conditions.

3.4.3 Navigation

Preservation of interior navigation by controlling invasive species would also be a key

consideration. It would be beneficial to detect an increase in invasive species in navigable

waterways.

• Spatial analysis has been identified as a performance measure for the determination of

the increase of invasive species in the internal navigation systems within the proposed

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project. Spatial analysis may involve comparative analysis of pre-project and post-project

aerial or satellite imagery and may utilize thematic mapper analysis to determine relative

changes within the study area.

3.4.4 Plant Diversity and Distribution

Plant diversity and distribution has been identified as a key indicator of project success with

respect to preventing, reducing, or reversing wetland loss in the study area. Comparison of preproject vegetation monitoring data with post-project vegetation monitoring data would serve to

determine whether plant communities within the study area change in response to project

features resulting in habitat changes. Relative abundance has been identified as the performance

measure for this attribute.

• Relative abundance is a measure of the abundance or dominance of each species present

in a sample. Relative abundance can be used to document the degree of impact in an area

by measuring both species dominance and evenness. Relative abundance can be used to

assess marsh health by comparing plant density before and after project implementation.

The Braun-Blanquet method (Mueller-Dombois and Ellenberg 1974) as described in

Steyer et al. (1995) will be utilized to measure relative abundance.

A post-project stabilization of relative abundance within the study area would be an indication of

significant project success, while a post-project reduction in the rate of decline of relative

abundance would be an indication of moderate project success. Conversely, no change in the rate

of decline of relative abundance post-project would indicate that the project did not succeed in

increasing vegetation productivity.

3.4.5 Water Quality

Water quality has been identified as a key indicator of project success with respect to reducing

salinity levels and increasing sediment and nutrient loads within the study area. Comparison of

pre-project water quality with post-project water quality would serve to determine whether

freshwater throughput is introducing sediments and nutrients and flushing out saline waters

within the study area in response to project features. Three performance measures have been

identified for this attribute, including total suspended solids, nutrients, and salinity.

• Total suspended solids is a measurement of the total volume of sediment and other solids

suspended in a given volume of water. Project features are designed to increase the

amount of freshwater and consequently suspended sediments delivered to marshes in the

study area.

• Nutrients are chemical compounds or minerals contained in surface waters that are

extracted by organisms for nourishment. Common nutrients in surface waters include

nitrates, phosphates, and ammonia. Project features are designed to increase the amount

of freshwater and consequently nutrients delivered to marshes in the study area.

• Salinity is a measure of the concentration of dissolved salt in a given volume of water.

Surface waters within the study area often exhibit elevated salinity levels with respect to

their historic levels due to the altered hydrology of the area and periodically due to storm

surge. Project features are designed to increase the amount of freshwater in the project

area and consequently reduce salinity levels.

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Post-project improvements in water quality within the study area, as evidenced by analyses of

these measures, would be an indication of significant project success, while a post-project

stabilization or decline in water quality within the study area would indicate that the project did

not succeed in increasing riverine influence on the study area.

3.4.6 Soil Stability

Soil stability is a key indicator of the susceptibility of a marsh to erosive forces. The more stable

a marsh is, the less vulnerable it is to erosion. The type of sediment that comprises a marsh as

well as the vegetation present can influence stability. Shear strength would be used to measure

soil stability throughout the marsh.

• Shear strength has been identified as a performance measure for the determination of the

response of soil stability to the proposed project. Shear strength may involve comparative

analysis of pre-project and post-project conditions along canals or waterbodies to

determine whether the project is having positive effects on soil stability.

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4.0 LITERATURE CITED

Barnes, T.K. and F.J. Mazzotti. 2005. Using Conceptual Models to Select Ecological Indicators

for Monitoring. Restoration and Management of Estuarine Ecosystems. In: S.A. Bortone

(ed.) Estuarine Indicators, CRC Press, Boca Raton, FL.

Chabreck, R.H. and G. Linscombe. 1982. Changes in vegetative types in Louisiana coastal

marshes over a 10-year period. Louisiana Academy of Sciences 45:98–102.

DeLaune, R.D., W.H. Patrick, Jr. & R.J. Buresh. 1978. Sedimentation rates determined by 137

Cs dating in a rapidly accreting salt marsh. Nature 275:12. pp. 532–533.

DeLaune, R.D., R.J. Buresh, and W.H. Patrick, Jr. 1979. Relationship of soil properties to

standing crop biomass of Spartina alterniflora in a Louisiana marsh. Estuarine Coastal

Marine Science 8: 477–487.

DeLaune, R.D., C. J. Smith, and W. H. Patrick. 1983. Relationship of marsh elevation, redox

potential, and sulfide to Spartina alterniflora productivity. Soil Sci. Soc. AM. J. 47:930–

935.

DeLaune, R.D., S. R. Pezeshki, J. H. Pardue, J. H. Whitcomb, and W. H. Patrick, Jr. 1990a.

Some influences of sediment addition to a deteriorating salt marsh in the Mississippi River

deltaic plain: A pilot study. Journal of Coastal Research 6:1:181–188.

DeLaune, R.D., W.H. Patrick, and N. Van Breemen. 1990b. Processes governing marsh

formation in a rapidly subsiding coastal environment. Catena 17:277–288. Cremlingen,

Germany.

Fischenich, J.C. 2008. The Application of Conceptual Models to Ecosystem Restoration.

Engineer Research and Development Center Publication TN-EMRRP-EBA-01. U.S. Army

Corps of Engineers, Vicksburg District, Vicksburg, MS.

McKee, K.L. and I.A. Mendelssohn. 1989. Response of a freshwater marsh plant community to

increased salinity and increased water level. Aquatic Botany 34:301–316.

Mueller-Dombois, D. and H. Ellenberg. 1974. Aims and Methods of Vegetation Ecology. New

York: John Wiley and Sons. 547 pp.

Ogden, J.C. and S.M. Davis. 1999. The Use of Conceptual Ecological Landscape Models as Planning

Tools for the South Florida Ecosystem Restoration Programs. South Florida Water

Management District, West Palm Beach, FL.

Steyer, G. D., R. C. Raynie, D. L. Steller, D. Fuller, and E. Swenson. 1995. Quality management

plan for Coastal Wetlands Planning, Protection, and Restoration Act monitoring program.

Open-file Series No. 95-01. Louisiana Department of Natural Resources, Coastal

Restoration Division, Baton Rouge.

U.S. Army Corps of Engineers. 2004. Louisiana Coastal Area (LCA) Ecosystem Restoration

Study. Volume I: Main Report. New Orleans District, New Orleans, LA.

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Real Estate Plan

Louisiana Coastal Area Near-Term Ecosystem Restoration Plan

Medium Diversion at White Ditch

1. PURPOSE

Title VII of the Water Resources Development Act of 2007 (Public Law 110-114) authorizes

the Louisiana Coastal Area Program. The authority includes requirements for comprehensive

planning, program governance, implementation, and other program components.

Coastal wetlands in Louisiana are a national significant environmental and economic resource.

Erosion of these wetlands threatens the long-term stability of human populations in the area as well as

important fish and wildlife resources.

This Real Estate Plan (REP) has been prepared to present the real estate requirements and

support the Louisiana Coastal Area Near-Term Ecosystem Restoration Plan, Medium Diversion at

White Ditch, Feasibility Report. Information contained within this report is based on preliminary data

and is subject to change. THE NON-STANDARD ESTATES PRESENTED IN THIS REP ARE

NOT APPROVED AS PART OF THIS REAL ESTATE PLAN AND FURTHER REVIEW,

REVISION, AND APPROVAL OF SUCH ESTATES ARE REQUIRED.

2. DESCRIPTION OF LANDS, EASEMENTS, AND RIGHTS-OF-WAY (LER)

a. Description of Lands, Easements and Rights-of-Way (LER) required for the

construction, operation and maintenance of the project

The White Ditch project area is located in the Breton Sound estuary and covers the area

extending north and south from just south of Belair, Louisiana, to the coastline of Louisiana and

extending east and west from the Mississippi River to the Oak River. This area extends about 50 km in

the NW-SE directions and about 30 km in the SW-NE direction. Subsidence, erosion, channelization,

saltwater intrusion, storm damage and the absence of fresh water, sediments and nutrients from the

Mississippi River have all caused significant adverse impacts to the White Ditch project area resulting

in extensive wetland loss and ecosystem degradation. There is an existing siphon at the mouth of White

Ditch that was built in 1963 and has not been in operation since 1991, except for two brief episodes.

The absence of a supply of fresh water, sediment, and nutrients has caused the marsh to

degrade. This degradation coupled with the subsidence and sea level rise rate of approximately 1.04 cm

per year has led to an increase in saltwater intrusion. The additional influx of saltwater from the Gulf of

Mexico through the vast canal network in the project area has further damaged the marsh vegetation. In

August and September 2005 Louisiana was hit by hurricanes Katrina and Rita. These hurricanes

brought high winds and high tidal surges and destroyed thousands of acres of already weakened marsh.

In September of 2008 hurricanes Ike and Gustav also hit the Gulf coast. While they did not make direct

landfall in the project area, the tidal surges from these storms caused the loss of additional marsh

acreage.

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This restoration project would reverse the trend of habitat degradation between the Mississippi

River and the River Aux Chenes Ridges through Mississippi River re-introduction. This will be

accomplished by re-connecting the Mississippi River to the project area through the use of a river

diversion. The material obtained through deepening/widening of the channel will be used to stabilize

ridges on either side of the channel acting as containment. Dredge material will also be placed in

strategic locations to build marsh. Any excess dredged material is to be used for beneficial marsh

creation.

b. Total LER required for each project purpose and feature

There are thirteen (13) landowners of the twenty-two (22) parcels within the right-of-way

needs for the project. All of the land needed for the project is privately owned. Landowners consist of

three companies (Delacroix Corporation, Shayot Land Co, LLC, & Haspel & Davis), one church (St.

John Baptist Church of Phoenix), and eight individuals in addition to State claimed water bottoms.

In the project area, lots/parcels are narrow and long extending back from the Mississippi River

through the marsh. A typical parcel in the area is 40 arpents long. Because of the configuration of

parcels, both the conveyance channel and the marsh creation/restoration features will affect 11 of the

13 landowners.

There is a total of 1,161.2 acres required for this project. The diversion structure will require

approximately 7.2 acres, and is located within a single parcel, therefore affecting one landowner.

Approximately 317.7 acres are necessary for the dredging of channels and improvement/enhancement

of associated channel ridges needed to maximize the conveyance of fresh water and sediment. This

feature affects 11 landowners on 15 parcels. This feature is also within NFS-owned water bottoms,

and further addressed in section 3. below. Approximately 381 acres are required to accommodate

marsh restoration efforts, affecting 18 parcels and 12 landowners. Approximately 3 acres are needed

to install notched dike flow restrictors (canal plugs) to redirect and restrict a certain level of flow

entering surrounding marshlands from the freshwater diversion. There are 6 of these features

proposed for the project, two of which are located on State claimed water bottoms. Three of the

plugs are proposed in canals owned by Delacroix Corporation (3 separate parcels) and one is located

on property owned by a private individual. The additional 452.3 acres is required for temporary work

area, which will affect all required tracts.

Construction of the project will also require the temporary relocation of State Highway 39

and a powerline adjacent to the highway. These relocations may cause temporary delays because of

land records issues that are not uncommon since hurricane Katrina; right-of-way documentation no

longer exists.

c. Estates to be acquired.

The Chief’s Report that was approved in January 2005 for the 2004 LCA Ecosystem

Restoration Study, contained several estates (both standard and non-standard) to be used for the LCA

projects. The District acknowledges that it is Corps of Engineers policy to acquire fee simple title for

ecosystem restoration projects in order to reduce the risk that incompatible uses on project land will

occur after project construction and to ensure that ownership rights vested in the project are clear and

enforceable (ER 1105-2-100, Appendix F, Amendment #2, F-20b(2)(a). However, regulations also

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indicate that a lesser interest, such as, a specific type of permanent easement, may be appropriate

depending upon the operational requirements of the project and other circumstances relevant to

project implementation, including landowner preference (EP 1165-2-502, 17b). Circumstances

wherein the acquisition of interests less than fee may be appropriate is where only select and easily

identifiable and narrow affirmative rights are required for successful implementation of the project

(ER 1105-2-100, Appendix F, Amendment # 2, F-20b(2)(b)i.).

Where project features exist, the proposed permanent estate acquisition is sufficient to

accomplish construction, operation and maintenance of the features. The project has specific

features in defined areas, and the necessary real estate rights are narrow, affirmative rights that can

easily be defined. It is believed that a real estate interest is not necessary outside the project feature

areas because the estates proposed herein provide sufficient rights to the Government to construct the

project and also protect the interests of the Government by prohibiting use of the surface for mineral

exploration or construction of improvements. In addition, because the project area is coastal

wetlands, the project features are further protected through the police powers of the Federal

Government through Section 404 of the Clean Water Act which require a permit from the Corps of

Engineers for any activity that could negatively impact a wetland. Lastly, due to the topography of

the project area, it is highly unlikely that the benefitted marshes could be developed. These three

protections combined greatly reduce the risk that incompatible uses on project lands will occur after

construction.

All documentation associated with the approval request of to deviate from fee simple title

acquisition is included as Exhibit E.

Any activity that may have a detrimental effect to the benefits area of the project is regulated,

therefore the risks over time would be minimal - aside from uncontrollable forces such as nature

(hurricanes, etc.). The types of activities that could be considered risks (oil/gas surface exploration,

excavation and fill activities, etc.) are currently regulated by the Louisiana Department of Natural

Resources, Office of Coastal Management, under Title 43, Chapter 7 of the Louisiana Administrative

Code. Specifically, Subchapter C, Section 723.A.2. requires permits for dredging or filling, urban

developments, energy development activity(exploration and transmission of oil/gas), mining

activities(surface & subsurface), surface water control, shoreline modification, recreational

developments, industrial development, drainage projects and "any other activities or projects that

would require a permit or other form of consent or authorization from the U.S. Army Corps of

Engineers, the Environmental Protection Agency, or the Louisiana Department or Natural

Resources." Additionally, activities in the marshes (wetlands) are regulated by Section 404 of the

Clean Water Act under the purview of the USACE. Certain other activities are regulated by the U.S.

Fish and Wildlife Service, the National Marine Fisheries Service, the EPA, and the Louisiana

Department of Environmental Quality.

There are five (5) estates proposed for use for this project; three standard and two nonstandard. The recommended estates to be acquired are explained below.

Temporary Work Area Easement (standard estate)

A temporary easement and right-of-way in, on, over and across (the land described in Schedule

A )(Tract No__); for a period not to exceed two (2) years, beginning with the date possession of the

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land is granted to the United States, for use by the United States, its representatives, agents, and

contractors as a work area, including the right to (borrow and/or deposit fill, spoil and waste material

thereon) move, store and remove equipment and supplies, and erect and remove temporary structures

on the land and to perform any other work necessary and incident to the construction the White Ditch

Project, together with the right to trim, cut, fell and remove therefrom all trees, underbrush,

obstructions, and any other vegetation, structures, or obstacles within the limits of the right-of-way;

reserving, however, to the landowners, their heirs and assigns, all such rights and privileges as may be

used without interfering with or abridging the rights and easement hereby acquired; subject, however,

to existing easements for public roads and highways, public utilities, railroads and pipelines.

Fee excluding minerals (with restriction on use of the surface) (standard estate)

The fee simple title to (the land described in Schedule A)(Tract No __), subject, however, to

existing easements for public roads and highways, public utilities, railroads and pipelines; excepting

and excluding from the taking all oil and gas, in and under said land and all appurtenant rights for the

exploration, development, production and removal of said oil and gas, but without the right to enter

upon or over the surface of said land for the purpose of drilling and extracting therefrom said oil and

gas.

Channel improvement easement (standard estate)

A perpetual and assignable right and easement to construct, operate, and maintain channel

improvement works on, over and across (the land described in Schedule A)(Tract No) for the purposes

as authorized by the Act of Congress approved _______________, including the right to clear, cut, fell,

remove and dispose of any and all timber, trees, underbrush, buildings, improvements and/or other

obstructions therefrom; to excavate, dredge, cut away, and remove any or all of said land and to place

thereon dredge or spoil material; and for such other purposes as may be required in connection with

said work of improvement; reserving, however, to the owners, their heirs and assigns, all such rights

and privileges as may be used without interfering with or abridging the rights and easement hereby

acquired; subject, however to existing easements for public roads and highways, public utilities,

railroads and pipelines.

Canal alteration easement (non-standard estate)

A perpetual and assignable right and easement in (the land described in Schedule A)(Tract

No__) to deposit materials within and around the canal, to place plugs or fully close the canal, to cut

gaps in the canal, or make other alterations to the canal, in order to restore the hydrology and /or to

stabilize the spoil banks along the canal; and for such other purposes as may be required in connection

with said work of improvement; reserving, however, to the owners, their heirs and assigns, all such

rights and privileges as may be used without interfering with or abridging the rights and easement

hereby acquired; and expressly excepting and excluding all oil, gas and other minerals occurring naturally

in liquid or gaseous form, in and under said land and all appurtenant rights for the exploration,

development, production and removal of said oil, gas and other minerals occurring naturally in liquid or

gaseous form, but without the right to enter upon or over the surface of said land for the purpose of

exploration, development, production and removal therefrom of said oil, gas and other minerals occurring

naturally in liquid or gaseous form; provided however, that the rights, interests and privileges, associated

with the original canal right-of-way, hereinabove excepted and reserved are hereby subordinated to the

right of this canal alteration easement.

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Wetland Creation and Restoration Easement (non-standard estate)

A perpetual and assignable easement and right-of-way in, on, over and across (the land

described in Schedule A) (Tract No. -) to construct, operate, maintain, patrol, repair, renourish, and

replace wetlands and associated coastal habitats, including the right to borrow and/or deposit fill; to

accomplish any alterations of contours on said land; to plant vegetation on said land; to excavate,

dredge, cut away, and remove any or all of said land and to place thereon dredge or spoil material; to

construct dikes and to install, alter, relocate, repair or plug cuts in the banks of dikes; to construct,

operate and maintain pipelines for the purpose of dredge or spoil material transport and deposition; to

move, store and remove equipment and supplies; to plug, fill or alter pipeline canals located within the

limits of the easement; to trim, cut, fell and remove therefrom all trees, underbrush, obstructions, and

any other vegetation, structures, or obstacles within the limits of the easement (excepting the structures

now existing on the land, described as _________), provided that no other structures shall be

constructed or maintained on the land except as may be approved in writing by the representative of the

United States in charge of the project, that no excavation shall be conducted and no landfill placed on

the land without such approval as to the location and method of excavation and/or placement of

landfill, [that no vehicles shall be operated within the limits of the easement without such approval,

except as may be required to operate and maintain the easement,] and that no trimming, cutting, felling

or removal of trees, underbrush, and any other vegetation shall be conducted without such approval;

the above estate is taken subject to existing easements for public roads and highways, public utilities,

railroads and pipelines; reserving, however, to the grantor(s), (his) (her) (its) (their) (heirs,) successors

and assigns, all such rights and privileges as may be used without interfering with or abridging the

rights and easement hereby acquired; and expressly excepting and excluding all oil, gas and other

minerals occurring naturally in liquid or gaseous form, in and under said land and all appurtenant rights

for the exploration, development, production and removal of said oil, gas and other minerals occurring

naturally in liquid or gaseous form, but without the right to enter upon or over the surface of said land

for the purpose of exploration, development, production and removal therefrom of said oil, gas and

other minerals occurring naturally in liquid or gaseous form.

d. Breakdown of Acreage by Estate

Temporary Work Area Easement

Approximately 452.3 acres are required for the temporary work area associated with the

construction of this project.

Fee excluding minerals

Approximately 7.2 acres of fee will be required for the structure location.

Channel Improvement Easement

Approximately 317.7 acres of permanent easement will be required to accommodate the

conveyance channel features of this project. Channels will be dredged to allow for a greater volume

of water to be conveyed. The dredged material will be used to restore the ridges along the conveyance

channel in order to properly stabilize and contain the channel, thereby eliminating the need for dredge

disposal areas.

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Canal Alteration Easement

Approximately 3 acres of permanent easement will be required for placement of notched dike

flow restrictors (plugs) to be placed in existing canals. These plugs will be utilized to redirect and

restrict the amount of freshwater conveyed to certain locations with the project area.

Wetland Creation and Restoration Easement

Approximately 381 acres of permanent easement will be required for wetland creation and

restoration. Dredged material obtained from deepening/widening the conveyance channel will be

used for beneficial marsh creation.

3. LERRD OWNED BY THE NON-FEDERAL SPONSOR

The non-federal sponsor for this project is the Coastal Protection and Restoration Authority of

Louisiana (CPRA), through the Office of Coastal Protection and Restoration. There are NFS-owned

water bottoms required for this project.

A significant portion of the LERRD required for this project is located on NFS-owned water

bottoms. Nearly the entire conveyance channel located east of the 40-arpent line is located within

NFS-owned water bottoms, which equates to approximately half of the proposed channel improvement

easement. In addition, two of the proposed channel plugs depicted in the attached Exhibit A are

located on State water bottoms (the second northernmost plug, and the southernmost plug).

The above-referenced water bottoms are available for the project but not sufficient to cover the

entire right-of-way necessary, therefore additional easements will be necessary. At this time, none of

the right-of-way identified as NFS-owned water bottoms has been previously provided as an item of

cooperation for another Federal project. Credit will be received for the required LERRD.

4. NON-STANDARD ESTATES DISCUSSION

The proposed non-standard estates, Wetland Creation and Restoration Easement and Canal

Alteration Easement, are included herein, 2.c. above. Approval of these non-standard estates is

requested as part of document approval. All documentation associated with the approval request of

the non-standard estates is included as Exhibit E.

5. EXISTING FEDERAL PROJECTS WITHIN THE LERRD REQUIRED FOR THE

PROJECT

There are no existing federal projects within the LERRD required for this project.

6. FEDERALLY OWNED LAND REQUIRED FOR PROJECT

There is no federally owned land within the project area. Therefore, no federally owned land

is required for this project.

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Feasibility Study / SEIS

7. NAVIGATION SERVITUDE

Navigational Servitude allows acquisition of shore lands extending to the ordinary high-water

mark thereof and may be exercised under statutory rights and powers without obligation for

compensation to the riparian landowners. Navigational Servitude will not be exercised for this

project.

8. MAPS

Exhibit A contains maps of the project area. Page 1 of Exhibit A is a Project Area map

showing the geographic location of the project area. Page 2 of Exhibit A is a map depicting the

proposed project features, and generally conveys the anticipated LER required to accommodate those

features. Page 3 of Exhibit A is a map depicting the proposed projects features in a wider view so that

all plug locations are also depicted.

9. INDUCED FLOODING

It is not anticipated that induced flooding will rise to the level of a taking for which just

compensation will be owed. Induced flooding is largely dependent on the operation of the diversion.

The proposed diversion structure is recommended to be operated by a “pulse” introduction of fresh

water during seasonal high sediment loads being carried by the Mississippi River (March – May).

Although the White Ditch diversion will increase the frequency of inundation in the interior

marshes during the March-April pulse, no substantial damage to private property is anticipated to

occur. The benefited area consists of low-lying marsh and shallow open water accessible only by boat

and vulnerable to tidal surges. The area was once subject to inundation by the Mississippi River

during spring high water events, until levees were constructed along the river by the Mississippi River

and Tributaries project. The White Ditch diversion is formulated to mimic these natural,

land-building flood events by reintroducing freshwater, sediment and nutrients to the marshes in the

project area. Over the 50-year period of analysis, the project is anticipated to prevent the loss of

approximately 13,750 acres of emergent marsh in the project area and could potentially lead to a net

gain in marsh acres. The current land uses are likely to be enhanced through operation of the

diversion because it will improve fish and wildlife habitat in the benefited area.

Alligator egg harvesting is the only known current land use that has the potential to be

impacted by a proposed freshwater diversion. However, due to the proposed operation of the

diversion, alligator life cycle requirements (courtship, mating, nest building, egg laying, hatching, and

rearing of young) within the project area are not expected to be altered.

The recommended “pulse” is anticipated to “freshen” (or dramatically reduce salinity in) the

project area for a period of approximately four to five months, whereas currently, the area maintains a

certain level of salinity during that time frame. After the seasonal “pulse”, the diversion could be

operated with a maintenance flow of 1,000 cfs. Salinity appears to be determined more by

maintenance flows than by the approximate 2-month “pulse” activity. From the data evaluated up to

this point, it appears that the overall salinity boundaries with the operation of the project are not

drastically changed from the current salinity boundaries. However, the timing of the fresh waster

introduction will drive the consequence to certain crops, specifically oysters.

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Feasibility Study / SEIS

There are no oyster leases within the LERRDs required for this project. There are oyster

leases near the outer limits of the project boundary, as depicted in Exhibit B. The alteration of salinity

during the spring months may affect the production of those oyster beds. However, Louisiana law

does not require the State to ensure adequate salinity levels for the leased oyster beds.

There are no structures upon lands known to be impacted by the project. In addition, it is not

likely or anticipated that any induced flooding that may occur will impact any structures.

All existing viable uses of the marshlands are not expected to be detrimentally affected by the

periodic change in water elevation. Therefore, flowage easements are not necessary within the project

area.

10. BASELINE COST ESTIMATE

A cost estimate of the real property interests required for this project is attached as Exhibit C

and indicates the required interests for construction, operation and maintenance of this project. The

Unit Value used to generate Total Real Estate Project Costs was derived from a Gross Appraisal that

was performed in November 2009. Information used in the Gross Appraisal was obtained from the

Parish Assessor’s office, comparable sales, and interviews with local appraisers and landowners. The

Sales Comparison Approach was used in the appraisal to derive current fair market value.

11. RELOCATION ASSISTANCE BENEFITS

It is not anticipated that there will be any residents eligible for relocation benefits. There are

no structures in the vicinity of the proposed project alternative impacted area. Any required

relocations will be performed in accordance with the provisions of Public Law 91-646, the Uniform

Relocation Act, as amended.

12. MINERAL ACTIVITY/TIMBER HARVESTING IN PROJECT AREA

There is mineral activity (oil/gas wells and pipelines) within the vicinity of the proposed

project area. There are two oil wells located within the proposed channel, and one oil well located

within the proposed marsh creation/wetland restoration. All wells located within the right-of-way

limits of the project are closed/abandoned and therefore, not productive or in use.

Closed/abandoned wells within the project area are not anticipated to cause real estate issues or

delays for the project.

There is also one line (believed to be formerly used for oil) that has a coastal permit. This

permitted line lies across the proposed diversion channel. Although not documented within the

State’s system, after speaking with the Coastal Permits Section, it is believed that the line is no longer

in use because the wells that previously served the line have been closed/abandoned. In fact, it is

unknown whether the line has been removed because the use or abandonment of such lines is not a

reporting requirement of the coastal permit. Although possible existence of the line is not anticipated to

cause real estate issues, removal of the line, if necessary, may cause brief construction delays.

It is not anticipated that any merchantable timer will be impacted by the proposed project.

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Feasibility Study / SEIS

13. NON-FEDERAL SPONSOR ASSESSMENT

The Non-Federal sponsor for this project is the Coastal Protection and Restoration Authority of

Louisiana (CPRA), through the Office of Coastal Protection and Restoration. As the non-federal

sponsor, CPRA must provide all real estate interests required for the project, i.e., all lands, easements,

rights-of-way, relocations, and any other interest, including suitable borrow and dredged or excavated

material disposal areas (LERRDs).

The Non-Federal Sponsor is assessed to be fully capable to perform all acquisition activities

associated with this project. The Sponsor has the capability to acquire and hold real estate as well as

the ability to contract for real estate services to supplement its staff in order to meet project schedules.

However, it must be recognized herein that CPRA is the non-federal sponsor for all New Orleans

District coastal restoration projects and all hurricane risk reduction projects. Therefore, if all LCA

projects and several hurricane risk reduction projects are authorized for construction under concurrent

schedules, there is a possibility that CPRA may not be able to accomplish LER acquisition due to the

massive amount of work required for such an undertaking. If that were the case, it is possible that

CPRA may request that the Federal Government accomplish acquisition of LER on their behalf.

The Assessment of the Non-Federal Sponsor’s Real Estate Acquisition Capabilities is

attached as Exhibit D.

14. ZONING IN LIEU OF ACQUISITION

There will be no zoning ordinances enacted to facilitate acquisition of land for the project.

15. SCHEDULE

A detailed schedule will be developed when the final ROW is determined. Normally, an

estimate of one year is allowed to acquire ROW for a project.

16. FACILITY OR UTILITY RELOCATION

A brief survey was conducted of utilities/facilities that will be impacted by the proposed

project. A determination of compensable interests has not been made as of the date of this report.

However, an estimate of likely utility/facility relocation costs are included. The following

facilities/utilities are anticipated to be impacted by the proposed project: State Highway 39, an

Entergy power line along Highway 39, and a telephone cable that appears to be in the same

right-of-way corridor and share the same poles as the power line. Estimated relocation costs for the

State Highway and the Entergy powerline are $101,000 and $107,000 respectively.

17. HTRW AND OTHER ENVIRONMENTAL CONSIDERATIONS

Investigation for contaminants within the project boundaries was conducted in accordance

with CERCLA, RCRA, and applicable State law, by the St. Louis District. Soil and water quality

sampling is required prior to construction. It is not anticipated that any clean-up or response actions

will be required.

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Feasibility Study / SEIS

However, if it is discovered that clean-up or response actions are necessary, in accordance with

Article II. H. of the Feasibility Cost Sharing Agreement (FCSA), executed on 6 November 2008, “The

non-federal sponsor shall be responsible for the total cost of developing a response plan for addressing

any hazardous substances regulated under the Comprehensive Environmental Response,

Compensation and Liability Act of 1980, Pub. L. No. 96-510, 94 Stat. 2767, (codified at 42 U.S.C.

Sections 9601-9675), as amended, existing in, on, or under any lands, easements of rights-of-way that

the Government determines to be required for the construction, operation, and maintenance of the

project. Such costs shall not be included in total study costs.”

18. LANDOWNER ATTITUDE

There is a great deal of landowner support for this project. That support is driven by the fact

that the area in the vicinity of the proposed project is degrading at an alarming rate and that the

potential exists to not only stop, but reverse the trend of degradation with the project area.

Even though there is a great deal of support for this project, there continues to be a great deal

of concern from landowners regarding current land uses and harvesting activities that take place on

the affected properties. Activities of concern include, but are not necessarily limited to oyster

harvesting, alligator nesting and hunting activities. The concern is based on the fact that the

afore-mentioned activities have the potential to adversely impact certain landowners financially.

19. NOTIFICATION TO THE NFS REGARDING THE RISKS ASSOCIATED WITH

ACQUIRING LAND BEFORE EXECUTION OF THE PROJECT PARTNERSHIP

AGREEMENT (PPA)

As project alternatives are clearly selected, the non-federal sponsor will be issued a risk letter

explaining the risk of acquiring lands prior to the execution of the PCA and advised to wait on

coordination of the acquisition plan and notice to proceed with acquisition.

20. OTHER REAL ESTATE ISSUES RELEVANT TO THE PROJECT

There are no other known real estate issues, other than those mentioned in this report.

ANNE L. KOSEL

Chief, Real Estate Division

USACE, St. Louis District

Prepared by:

Real Estate Plan – Lynn Hoerner, Realty Specialist

Cost Estimate – Timothy Nelson, Appraiser

810
EXHIBIT A

MAPS

811
Exhibit A-1

812
Exhibit A-2

813
Exhibit A-3

814
EXHIBIT B

OYSTER LEASE LOCATION MAP

815
816
EXHIBIT C

REAL ESTATE COST ESTIMATE

817
818
EXHIBIT D

NON FEDERAL SPONSOR ASSESSMENT

819
820
821
EXHIBIT E

DEVIATION FROM FEE TAKING AND

NON-STANDARD ESTATES APPROVAL REQUEST

822
LCA: MEDIUM DIVERSION AT WHITE DITCH

REQUEST FOR APPROVAL TO DEVIATE FROM FEE TAKING AND

REQUEST FOR APPROVAL OF NON-STANDARD ESTATE

1. This is a request for approval to deviate from acquisition of the Fee estate for the LCA Medium

Diversion at White Ditch project and request for approval to acquire a Channel Improvement Easement

(standard estate), a Canal Alteration Easement (non-standard estate), and a Wetland Creation and

Restoration Easement (non-standard estate) to accomplish the project.

2. The detailed project purpose and description is contained within the Real Estate Plan. The project

entails re-connecting the Mississippi River to the project area through the use of a river diversion. The

material obtained through deepening/widening of the channel will be used to stabilize ridges on either

side of the channel acting as containment. Dredge material will also be placed in strategic locations to

build marsh. Any excess dredge material is to be used for beneficial marsh creation.

3. Maps depicting the locations of project features are included in the Real Estate Plan as Exhibit A,

pages 2 and 3.

4. The District acknowledges that it is Corps of Engineers policy to acquire fee simple title for ecosystem

restoration projects in order to reduce the risk that incompatible uses on project land will occur after

project construction and to ensure that ownership rights vested in the project are clear and enforceable

(ER 1105-2-100, Appendix F, Amendment #2, F-20b(2)(a). However, regulations also indicate that a

lesser interest, such as, a specific type of permanent easement, may be appropriate depending upon the

operational requirements of the project and other circumstances relevant to project implementation,

including landowner preference (EP 1165-2-502, 17b). Circumstances wherein the acquisition of

interests less than fee may be appropriate is where only select and easily identifiable and narrow

affirmative rights are required for successful implementation of the project (ER 1105-2-100, Appendix

F, Amendment # 2, F-20b(2)(b)i.).

5. It is the opinion of the Non-Federal Sponsor, The Coastal Protection and Restoration Authority

(CPRA), and the District that construction of this project can be accomplished through the acquisition

of perpetual easements rather than fee. The project has specific features in defined areas, and the

necessary real estate rights are narrow, affirmative rights that can easily be defined. The standard

Channel Improvement Easement would allow the Government sufficient rights to construct the cuts

necessary to form the conveyance channel. District Office of Counsel has prepared a non-standard

Wetland Creation and Restoration Easement that would allow the Government necessary rights to place

dredged material in the marsh to improve the habitat and would protect the environment by prohibiting

construction of structures, excavation of the property or placement of fill without approval by the

United States. The estate also prohibits use of the surface to explore for minerals. District Office of

Counsel has also prepared a non-standard Canal Alteration Easement which would allow the placement

of plugs in existing canals, to redirect and restrict freshwater flow, and specifically prohibits the use of

the surface for mineral exploration in addition to prohibiting any activity that interferes with the rights

of the easement.

6. It is the opinion of the District that the estates proposed herein provide sufficient rights to the

Government to construct the project and also protect the interests of the Government by prohibiting use

823
of the surface for mineral exploration or construction of improvements. In addition, because the

project area is coastal wetlands, the project features are further protected through the police powers of

the Federal Government through Section 404 of the Clean Water Act which require a permit from the

Corps of Engineers for any activity that could negatively impact a wetland. Lastly, due to the

topography of the project area, it is highly unlikely that the benefitted marshes could be developed.

These three protections combined greatly reduce the risk that incompatible uses on project lands will

occur after construction.

7. The District proposes the acquisition of easements rather than fee considering that this project is one of

15 Louisiana Coastal Area (LCA) projects which collectively encompass thousands of acres. The

decisions regarding which estates to acquire for ARTM will impact the other 14 LCA projects. The

non-federal sponsor, The Coastal Protection Restoration Authority, is not in favor of owning fee

interest over the project area for ARTM. The mission of the non-federal sponsor is to oversee all

hurricane risk reduction projects and all coastal restoration projects in south Louisiana. The sponsor is

willing to acquire a fee estate when it is absolutely necessary for the project. However, owning fee

lands for public access is not within the authorized missions of the non-federal sponsor.

8. Approval of the non-standard Wetland Creation and Restoration Easement is requested because there is

no standard easement that includes the real estate rights necessary for construction of certain project

features. The project includes using dredged material for stabilization of ridges on either side of the

conveyance channel and disposal of additional dredged material in designated areas to use it

beneficially to enhance existing marsh and to propagate the growth of marsh in waterbottoms

• The Wetland Creation and Restoration Easement provides all the necessary rights to protect the

marsh as well as the marsh that will naturally propagate in the project areas. The only potential

use of the property, given its location and physical characteristics, is for recreation (fishing and

hunting) and mineral development. Recreational uses will not impact the viability of the project.

The Wetland Creation and Restoration Easement prohibits the construction of structures, operation

of vehicles, excavation of the land, disposal of material, cutting of trees, and the use of the surface

for mineral exploration without prior approval by the United States

• The cost of acquiring the Wetland Creation and Restoration Easement is less than the cost of

acquiring Fee. For the purposes of this project the Wetland Creation and Restoration Easement is

valued at 25% of Fee value

• The Wetland Creation and Restoration Easement was written using language from several standard

estates such as the Perpetual Beach Nourishment Easement, the Perpetual Beach Storm Damage

Reduction Easement , the Fee Excluding Minerals (with restrictions on use of the surface), and the

Flowage Easement (Permanent Flooding).

• For ease of review, attached as Exhibit A is a highlighted version of the Wetland Creation and

Restoration Easement indicating which language was taken from standard estates and which

language is non-standard. Also attached as Exhibit B is a final version of the estate. Exhibit C is

a written statement from Office of Counsel (MVN), indicating the legal sufficiency of the

Non-Standard Estate.

824
9. Approval is also requested for a non-standard Canal Alteration Easement because there is no standard

easement that includes the real estate rights necessary for the construction of certain project features.

The project includes placing plugs in designated areas/canals to redirect freshwater within surrounding

marshlands.

• The Canal Alteration Easement provides all the necessary rights to construct, operate and maintain

the plugs as well as adaptively manage the water restriction and conveyance associated with the

project. The potential uses of the property given the location and physical characteristics are

recreation (hunting and fishing) and mineral development. The Canal Alteration Easement

specifically prohibits the use of the surface for mineral exploration in addition to prohibiting any

activity that interferes with the rights of the easement.

• For ease of review, attached as Exhibit D is a highlighted version of the Canal Alteration Easement

which indicates which language was taken from standard estates and which language is

non-standard. Also attached as Exhibit E is a final version of the estate. Exhibit F is a written

statement from Office of Counsel (MVN), indicating the legal sufficiency of the Non-Standard

Estate.

10. Similar non-standard Wetland Creation and Restoration Easement and Canal Alteration were

previously included in the approved 2004 LCA Project Report.

11. Also enclosed as Exhibit G is a Quality Control Checklist, Request to Deviate from Guidance as to

Appropriate Interest to Acquire and/or Request for Approval of Use of Non-Standard Estate.

12. Point of contact for this request is Ms. Lynn Hoerner, 314-331-8157.

Prepared by:

_________________________________

Lynn Hoerner, Realty Specialist

Approved by:

__________________________________

Anne Kosel

Chief, Real Estate Division

St. Louis District

825
WETLAND CREATION AND RESTORATION EASEMENT

(based on the standard Perpetual Beach Nourishment Easement and other standard estates)

A perpetual and assignable easement and right-of-way in, on, over and across (the land described in

Schedule A) (Tract No. -) to construct, operate, maintain, patrol, repair, renourish, and replace

wetlands and associated coastal habitats, including the right to borrow and/or deposit fill; to

accomplish any alterations of contours on said land; to plant vegetation on said land; to excavate,

dredge, cut away, and remove any or all of said land and to place thereon dredge or spoil material;

to construct dikes and to install, alter, relocate, repair or plug cuts in the banks of dikes; to

construct, operate and maintain pipelines for the purpose of dredge or spoil material transport and

deposition; to move, store and remove equipment and supplies; to trim, cut, fell and remove

therefrom all trees, underbrush, obstructions, and any other vegetation, structures, or obstacles

within the limits of the easement (excepting the structures now existing on the land, described as

_________); provided that no structures for permanent human habitation shall be constructed or

maintained on the land; that no other structures shall be constructed or maintained on the land

except as may be approved in writing by the representative of the United States in charge of the

project, that no excavation shall be conducted and no landfill placed on the land without such

approval as to the location and method of excavation and/or placement of landfill, and that no

trimming, cutting, felling or removal of trees, underbrush, and any other vegetation shall be

conducted without such approval; the above estate is taken subject to existing easements for public

roads and highways, public utilities, railroads and pipelines; reserving, however, to the grantor(s),

(his) (her) (its) (their) (heirs,) successors and assigns, all such rights and privileges as may be used

without interfering with or abridging the rights and easement hereby acquired; and expressly

excepting and excluding all oil, gas and other minerals occurring naturally in liquid or gaseous

form, in and under said land and all appurtenant rights for the exploration, development,

production and removal of said oil, gas and other minerals occurring naturally in liquid or gaseous

form, but without the right to enter upon or over the surface of said land for the purpose of

exploration, development, production and removal therefrom of said oil, gas and other minerals

occurring naturally in liquid or gaseous form.

Exhibit A

826
WETLAND CREATION AND RESTORATION EASEMENT

(based on the standard Perpetual Beach Nourishment Easement and other standard estates)

A perpetual and assignable easement and right-of-way in, on, over and across (the land described

in Schedule A) (Tract No. -) to construct, operate, maintain, patrol, repair, renourish, and replace

wetlands and associated coastal habitats, including the right to borrow and/or deposit fill; to

accomplish any alterations of contours on said land; to plant vegetation on said land; to excavate,

dredge, cut away, and remove any or all of said land and to place thereon dredge or spoil material;

to construct dikes and to install, alter, relocate, repair or plug cuts in the banks of dikes; to

construct, operate and maintain pipelines for the purpose of dredge or spoil material transport and

deposition; to move, store and remove equipment and supplies; to plug, fill or alter pipeline canals

located within the limits of the easement; to trim, cut, fell and remove therefrom all trees,

underbrush, obstructions, and any other vegetation, structures, or obstacles within the limits of the

easement (excepting the structures now existing on the land, described as _________), provided

that no other structures shall be constructed or maintained on the land except as may be approved

in writing by the representative of the United States in charge of the project, that no excavation

shall be conducted and no landfill placed on the land without such approval as to the location and

method of excavation and/or placement of landfill, [that no vehicles shall be operated within the

limits of the easement without such approval, except as may be required to operate and maintain

the easement,] and that no trimming, cutting, felling or removal of trees, underbrush, and any other

vegetation shall be conducted without such approval; the above estate is taken subject to existing

easements for public roads and highways, public utilities, railroads and pipelines; reserving,

however, to the grantor(s), (his) (her) (its) (their) (heirs,) successors and assigns, all such rights and

privileges as may be used without interfering with or abridging the rights and easement hereby

acquired; and expressly excepting and excluding all oil, gas and other minerals occurring naturally

in liquid or gaseous form, in and under said land and all appurtenant rights for the exploration,

development, production and removal of said oil, gas and other minerals occurring naturally in

liquid or gaseous form, but without the right to enter upon or over the surface of said land for the

purpose of exploration, development, production and removal therefrom of said oil, gas and other

minerals occurring naturally in liquid or gaseous form.

Exhibit B

827
STATEMENT OF REVIEW AND APPROVAL

LCA MEDIUM DIVERSION AT WHITE DITCH

WETLAND CREATION AND RESTORATION EASEMENT

NON-STANDARD ESTATE

This is to certify that the Wetland Creation and Restoration Easement, a non-standard

estate, has been reviewed and is legally sufficient for the requirements of the above referenced

project.

__________________________________

Attorney Name, Title

__________________________________

Date

Exhibit C

828
CANAL ALTERATION EASEMENT

A perpetual and assignable right and easement in (the land described in Schedule A)(Tract No__)

to deposit materials within and around the canal, to place plugs or fully close the canal, to cut gaps

in the canal, or make other alterations to the canal, in order to restore the hydrology and /or to

stabilize the spoil banks along the canal; and for such other purposes as may be required in

connection with said work of improvement; reserving, however, to the owners, their heirs and

assigns, all such rights and privileges as may be used without interfering with or abridging the

rights and easement hereby acquired; and expressly excepting and excluding all oil, gas and other

minerals occurring naturally in liquid or gaseous form, in and under said land and all appurtenant

rights for the exploration, development, production and removal of said oil, gas and other minerals

occurring naturally in liquid or gaseous form, but without the right to enter upon or over the

surface of said land for the purpose of exploration, development, production and removal

therefrom of said oil, gas and other minerals occurring naturally in liquid or gaseous form;

provided however, that the rights, interests and privileges, associated with the original canal

right-of-way, hereinabove excepted and reserved are hereby subordinated to the right of this canal

alteration easement.

Exhibit D

829
CANAL ALTERATION EASEMENT

A perpetual and assignable right and easement in (the land described in Schedule A)(Tract No__)

to deposit materials within and around the canal, to place plugs or fully close the canal, to cut gaps

in the canal, or make other alterations to the canal, in order to restore the hydrology and /or to

stabilize the spoil banks along the canal; and for such other purposes as may be required in

connection with said work of improvement; reserving, however, to the owners, their heirs and

assigns, all such rights and privileges as may be used without interfering with or abridging the

rights and easement hereby acquired; and expressly excepting and excluding all oil, gas and other

minerals occurring naturally in liquid or gaseous form, in and under said land and all appurtenant

rights for the exploration, development, production and removal of said oil, gas and other minerals

occurring naturally in liquid or gaseous form, but without the right to enter upon or over the

surface of said land for the purpose of exploration, development, production and removal

therefrom of said oil, gas and other minerals occurring naturally in liquid or gaseous form;

provided however, that the rights, interests and privileges, associated with the original canal

right-of-way, hereinabove excepted and reserved are hereby subordinated to the right of this canal

alteration easement.

Exhibit E

830
STATEMENT OF REVIEW AND APPROVAL

LCA MEDIUM DIVERSION AT WHITE DITCH

CANAL ALTERATION EASEMENT

NON-STANDARD ESTATE

This is to certify that the Canal Alteration Easement, a non-standard estate, has been

reviewed and is legally sufficient for the requirements of the above referenced project.

__________________________________

Attorney Name, Title

__________________________________

Date

Exhibit F

831
Quality Control Checklist

Request to Deviated from Guidance as to Appropriate

Interest to Acquire

and/or

Request for Approval of Use of Non-standard Estate

ER 405-1-12, paragraphs 12-9 and 12-10

It is the policy of USACE to either acquire or to require a non-Federal sponsor to provide the

minimum interest in real property necessary to support a project. The interests described in

paragraph 12-9 of ER 405-1-12, have been determined to represent the minimum interest generally

required to support the described purposes or features and must be utilized unless otherwise

approved. Greater or lesser interests may be appropriate depending on the purposes of a project

or a particular acquisition.

Standard estates approved for use in either full Federal or cost shared projects are contained in the

RE Handbook. Once the appropriate interest needed is identified, the corresponding standard

estate must be used as found in the regulations. Where there is no corresponding standard estate

for the interest to be acquired or where changes to the corresponding standard estate are desired, a

non-standard estate (NSE) must be drafted and approved. For all NSEs not within the scope of

District’s approval authority, or requests to deviate from guidance as to appropriate interest to

acquire, approval may be obtained either by placing the language of the NSE, or request to deviate,

in the Real Estate Plan (REP) of a feasibility report or other study decision document that is to be

approved by HQUSACE or by request for approval by memorandum forwarded through MVD to

HQ, Real Estate Community of Practice, for appropriate coordination, review, and final

determination.

PROJECT: LCA – MEDIUM DIVERSION AT WHITE DITCH

Title and date of Decision Document which contains the REP requesting approval of estate

deviation or NSE approval: LCA – Medium Diversion at White Ditch

Feasibility Study

Subject line and date of memorandum requesting approval of estate deviation or NSE approval

N/A – requested as an exhibit in the Real Estate Plan

1. Does the proposed estate, whether standard or non-standard; provide sufficient interest for

the construction, operation, and maintenance of the project? _________YES___________

2. Coordination has been made with the following and they concur with use of the proposed

estate:

Project Management ________X________ E&C __________X___________

Operations _______N/A____________ Office of Counsel_______X____

Coordination was made with the following other functional groups. Environmental

Exhibit G

832
3. A statement of legal sufficiency from OC is attached to the REP or memo requesting

approval by HQ ____Yes_____.

4. Is the cost to acquire the proposed estate more than the cost of acquiring a standard interest

with a standard estate? ____NO____ Is this discussed in the request? ____Yes___

5. Did the Non-Federal Sponsor (NFS) propose the deviation from appropriate interest or use

of a NSE? ___NO_____

If so, why? ____________

If not, was the deviation or NSE coordinated with the NFS? ________YES_____________

6. Can the non-standard estate be approved by the district Chief of RE? ______NO______

If so, it must:

Serve the intended project purpose ______________

Substantially conform with and not materially deviate from the corresponding standard estate

__________________

Does not increase the costs no potential liability of the Government? ________________

7. Does the NSE conform to format of standard estate __________YES_______________?

8. Does the request for approval which goes through MVD to HQ contain a detailed

explanation of a justification for the deviation as to interest to be acquired? ___Yes_____

9. Does the request contain a detailed explanation of each non-standard clause in the

estate? ___Yes_____. The request must detail the need for the language in relation to

project requirements. Each non-standard right to be acquired, restriction/prohibition placed

on fee owner’s interest and/or reservation to the fee owner must be fully discussed. Is the

acquisition or reservation of mineral rights held by the fee owner or outstanding 3rd party

mineral rights fully discussed in relation to the estate language and project requirements?

___Yes___

If there are clauses found in the corresponding standard estate which have been deleted, is

there an explanation of the deletion? ___N/A_____

10. Has the district deviated as to the appropriate interest on similar projects in the past?

____Yes____. If so, which project(s)? The Wetland Creation and Restoration Easement

and Canal Alteration Easement is proposed for approval for other LCA projects.

11. Has the proposed NSE been previously approved by HQ for use for a project in your

district? ___NO___. If so, which project(s)? ______________

Provide a copy of the previous approval.

A copy of this Checklist is attached to the REP or memorandum requesting a deviation as to

interest to be acquired or approval of a NSE. _____Yes_____

__________________________________ ________________________________

Realty Specialist or Appraiser Date

__________________________________ _________________________________

Branch or Section Chief Date

833

Louisiana Coastal Area (LCA) Program:

Medium Diversion at White Ditch Project

Appendix K

Cost Effectiveness & Incremental Cost Analysis

August 2010

DRAFT

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TABLE OF CONTENTS

1.0 PURPOSE................................................................................................................................ 1

2.0 DESCRIPTION OF ALTERNATIVE PLANS.................................................................... 1

2.1 Screening / Evaluation of Alternative Plans .................................................................... 2

2.2 CE/IC Analysis ................................................................................................................... 6

2.3 Alternative Plans not Carried for Further Analysis....................................................... 7

3.0 FINAL ARRAY OF ALTERNATIVES ............................................................................... 7

3.1 No Action (Future without Project Conditions).............................................................. 7

3.1.1 Soils and Waterbottoms ............................................................................................... 9

3.1.2 Sedimentation and Erosion......................................................................................... 10

3.1.3 Subsidence.................................................................................................................. 10

3.1.4 Salinity ....................................................................................................................... 10

3.1.5 Vegetation Resources................................................................................................. 11

3.1.6 Benthics...................................................................................................................... 12

3.1.7 Essential Fish Habitat................................................................................................. 12

3.2 Alternative 1 – 5,000 cfs diversion.................................................................................. 13

3.3 Alternative 2 – 10,000 cfs Max Diversion....................................................................... 14

3.4 Alternative 3 – 15,000 cfs Max Diversion....................................................................... 15

3.5 Alternative 4 – 35,000 cfs Max Diversion (TSP)............................................................ 16

4.0 COMPARISON OF ALTERNATIVE PLANS.................................................................. 16

4.1 Incremental Cost/Cost Effectiveness Analysis Process................................................. 16

4.2 Wetland Value Assessment (WVA) ................................................................................ 17

4.2.1 WVA Concept ............................................................................................................ 18

4.2.2 Community Model Variable Selection....................................................................... 18

4.2.3 Suitability Index Graphs............................................................................................. 19

4.2.4 Habitat Suitability Index Formula.............................................................................. 19

4.2.5 Benefit Assessment .................................................................................................... 19

4.2.5 MDWD Summary ...................................................................................................... 20

4.3 Cost Estimates for Habitat Improvement Measures. ................................................... 22

4.4 Results of the Incremental Cost/Cost Effectiveness Analysis ...................................... 23

4.5 Other Factors.................................................................................................................... 25

4.5.1 Recreational Benefits ................................................................................................. 26

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4.5.2 Desired Future Condition........................................................................................... 26

4.5.3 Relative Sea Level Rise.............................................................................................. 27

4.5.4 Breton Sound Benefits ............................................................................................... 29

4.5.5 Adaptive Management ............................................................................................... 29

4.5.6 Acceptability, Completeness, Effectiveness, and Efficiency..................................... 30

4.5.7 Recommendation of the Tentatively Selected Plan.................................................... 30

LIST OF TABLES

Table 1. LCA: White Ditch Incremental Cost/Cost Effectiveness Step 1a .................................... 4

Table 2. LCA: White Ditch Incremental Cost/Cost Effectiveness Step 1b .................................... 5

Table 3. Direct Footprint Acreage Impacts................................................................................... 20

Table 4a: WVA Benefits Summary .............................................................................................. 21

Table 4b. Acreage Summary......................................................................................................... 22

Table 5. LCA: White Ditch Cost Estimates.................................................................................. 22

Table 6. White Ditch Incremental Cost/Cost Effectiveness Step 2 .............................................. 23

Table 7. White Ditch Incremental Cost/Cost Effectiveness Step 2 .............................................. 25

Table 8. Net Increase in Recreation Benefits................................................................................ 26

Table 9. ERDC-SAND2 Model Calculations of Acreages for the MDWD Project Area under

Historical Sea Level Rise Rates.................................................................................................... 28

Table 10. ERDC-SAND2 Model Calculations of Acreages for the MDWD Project Area under

the Intermediate and High Sea Level Rise Rates.......................................................................... 29

LIST OF FIGURES

Figure 1. White Ditch CE/IC Analysis – Open Diversion.............................................................. 6

Figure 2. White Ditch CE/IC Analysis Step 1 – Mar/May Pulse ................................................... 7

Figure 3. Louisiana Coastal Area: Medium Diversion at White Ditch – Future Without Project

Condition......................................................................................................................................... 8

Figure 4. Relative Sea Level Rise: Medium and High Scenario Impacts on Future Without

Project Condition ............................................................................................................................ 9

Figure 5. Alternative 1 Location 3................................................................................................ 13

Figure 6. Alternative 2 Location 3................................................................................................ 14

Figure 7. Alternative 3 Location 3................................................................................................ 15

Figure 8. Alternative 4 Location 3................................................................................................ 16

Figure 9. CE/IC Analysis of Final Alternatives............................................................................ 24

Figure 10. CE/IC Best Buy Plans ................................................................................................. 25

Figure 11. FWP Acres at TY50 per Operational Plan .................................................................. 27

Figure 12. Comparison of Relative Sea Level Rise Effects.......................................................... 28

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1.0 PURPOSE

The purpose of this appendix is to describe the process by which alternatives for the White Ditch

were developed, and compared. A Cost Effectiveness & Incremental Cost Analysis (CE/IC) was

utilized.

2.0 DESCRIPTION OF ALTERNATIVE PLANS

Conceptual alternatives were integrated with the suitable locations for diversion structures to

yield an array of alternatives that meet the goals and objectives of the project and are likely to

restore the impaired deltaic processes. The alternatives are:

1. White Ditch (WD) 1: No Action. Over a 50-year period of analysis, if nothing were

done, we would see significant losses of all marsh types throughout the project area.

More major storms could accelerate this loss. As a result open water habitats would

continue to grow allowing for further intrusion of saltwater into the marsh.

2. White Ditch (WD) 2: Location 2 – 5,000 cfs. This alternative involves construction of a

structure capable of diverting up to 5,000 cfs. Additionally, once the preliminary

freshwater and sediment supply benefits of the structure are determined, measures from

the hydraulic distribution (H), sediment supply & distribution (S), and protection and

sustainability (P) will be refined to improve beneficial distribution of freshwater and

sediments to create and restore marsh habitat and improve its sustainability.

3. White Ditch (WD) 3: Location 2 – 10,000 cfs. This alternative involves construction of

a structure capable of diverting up to 10,000 cfs. Additionally, once the preliminary

freshwater and sediment supply benefits of the structure are determined, measures from

the hydraulic distribution (H), sediment supply & distribution (S) and protection and

sustainability (P) will be refined to improve beneficial distribution of freshwater and

sediments to create and restore marsh habitat and improve its sustainability.

4. White Ditch (WD) 4: Location 2 – 15,000 cfs. This alternative involves construction of

a structure capable of diverting up to 15,000 cfs. Additionally, once the preliminary

freshwater and sediment supply benefits of the structure are determined, measures from

the hydraulic distribution (H), sediment supply & distribution (S) and protection and

sustainability (P) will be refined to improve beneficial distribution of freshwater and

sediments to create and restore marsh habitat and improve its sustainability.

5. White Ditch (WD) 5: Location 2 – 35,000 cfs. This alternative involves construction of

a structure capable of diverting up to 35,000 cfs. Additionally, once the preliminary

freshwater and sediment supply benefits of the structure are determined, measures from

the hydraulic distribution (H), sediment supply & distribution (S) and protection and

sustainability (P) will be refined to improve beneficial distribution of freshwater and

sediments to create and restore marsh habitat and improve its sustainability.

6. White Ditch (WD) 6: Location 3 – 5,000 cfs. This alternative involves construction of a

structure capable of diverting up to 5,000 cfs. Additionally, once the preliminary

freshwater and sediment supply benefits of the structure are determined, measures from

the hydraulic distribution (H), sediment supply & distribution (S) and protection and

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sustainability (P) will be refined to improve beneficial distribution of freshwater and

sediments to create and restore marsh habitat and improve its sustainability.

7. White Ditch (WD) 7: Location 3 – 10,000 cfs. This alternative involves construction of

a structure capable of diverting up to 10,000 cfs. Additionally, once the preliminary

freshwater and sediment supply benefits of the structure are determined, measures from

the hydraulic distribution (H), sediment supply & distribution (S) and protection and

sustainability (P) will be refined to improve beneficial distribution of freshwater and

sediments to create and restore marsh habitat and improve its sustainability.

8. White Ditch (WD) 8: Location 3 – 15,000 cfs. This alternative involves construction of

a structure capable of diverting up to 15,000 cfs. Additionally, once the preliminary

freshwater and sediment supply benefits of the structure are determined, measures from

the hydraulic distribution (H), sediment supply & distribution (S) and protection and

sustainability (P) will be refined to improve beneficial distribution of freshwater and

sediments to create and restore marsh habitat and improve its sustainability.

9. White Ditch (WD) 9: Location 3 – 35,000 cfs. This alternative involves construction of

a structure capable of diverting up to 35,000 cfs. Additionally, once the preliminary

freshwater and sediment supply benefits of the structure are determined, measures from

the hydraulic distribution (H), sediment supply & distribution (S) and protection and

sustainability (P) will be refined to improve beneficial distribution of freshwater and

sediments to create and restore marsh habitat and improve its sustainability.

2.1 Screening / Evaluation of Alternative Plans

The ERDC-SAND2 model was originally known as the Boustany Model. The Boustany Model

was developed for evaluating the marsh creation potential. ERDC modified and refined the

Boustany model to specifically measure the marsh creation potential of diversion structures. The

modified version became known as the SAND model. The SAND was refined further and

became the SAND2. The ERDC-SAND2 Model was the tool used by the MDWD team to

predict changes in marsh acreages for all alternatives over a 50 year planning horizon. It is an

ecohydraulic engineering model specifically designed to assess the effectiveness of potential

diversion projects on restoration of land in the coastal marsh. The ERDC- SAND2 model is

fundamentally based on three processes impacting marsh accretion:

1. Historical land loss rates are applied to account for marsh loss due to all negatively

impacting system processes (e.g. sea level rise, compaction, subsidence, etc.) along

with background processes existing prior to the diversion operation (e.g. marsh

nutrient cycling, net tidal and groundwater inputs, etc.).

2. Inorganic benefits of flow diversion from the addition of sediment.

3. Organic benefits of flow diversion due to plant growth, mortality, and burial

stimulated by addition of the limiting nutrient (nitrogen).

The model applies these processes to assess Future With Project and Future Without Project

conditions for alternative comparison. Since the FWOP condition is without diversion, FWOP

marsh acreage is a function of land loss only. The model processes these categories and projects

acres of marsh within a specified project area. With some slight modifications, the model can

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also project acreages with accelerated sea level rise rates. Further information concerning the

ERDC-SAND2 Model can be found in Appendix L.

The outputs (net and average annual acres) from the ERDC-SAND2 model become a key

component of the WVA ecosystem model. Also, a defined operating plan had yet to be

evaluated, so three such operating schemes were proposed to begin to characterize the potential

range of benefits of various operating regimes for each diversion and the ability of each

alternative to achieve the goals and objectives of the project. The Open Diversion reflects the

upper threshold in terms of potential impacts. The other two regimes focus on maximizing

sediment capture during the highest sediment load in the River based on available information.

They are:

• Open Diversion Year Round

• A March 1–May 30 Maximum Pulse with no Maintenance Flow

• A March only pulse with a 1,000 cfs Monthly Maintenance Flow

Finally, the likelihood existed that these large diversion alternatives may have impacts beyond

the immediate study area. Therefore the ERDC-SAND2 Model was run on the original study

area as well as the entire Breton Sound Basin. The Institute for Water Resources (IWR) Planning

Suite was used for the analysis.

Table 1 displays the costs and net acres of marsh created at the end of the 50-year period of

analysis in order to compare alternatives that can achieve no net loss of marsh acres. The most

cost effective alternatives and operating schemes that achieve a no net loss or desired future

condition are highlighted in green. The desired future condition would be equivalent to the

current marsh acres (2009) of 41,206. The Location 3 – 10,000 cfs alternative achieves this at the

end of the period of analysis only for the year round open diversion operating regime. It does this

more cost effectively than the same size diversion at Location 2. The Location 3 – 15,000

alternative achieves the desired future condition at the end of the period of analysis for the year

round open diversion and the Mar/May Pulse. It does this more cost effectively than the same

size diversion at Location 2. The Location 3 – 35,000 alternative achieves the desired future

condition at the end of the period of analysis for all three operating regimes and more cost

effectively than the same size diversion at Location 2. The 35,000 cfs diversion also achieves a

no net loss of marsh within the expanded Breton Sound Basin if operated at full capacity year

round.

It should be noted that the major difference in cost between Location 2 alternatives and Location

3 is the length of conveyance channels needed to move freshwater, nutrients and sediments.

While Location 2 has an existing conveyance channel (White Ditch) Hydrologic and Hydraulic

modeling indicated that it requires considerably more dredging and placement of material to

make it effective at moving diversion flows to the majority of the study area. Location 3, while it

does involve dredging of new conveyance channels, they are much shorter and more efficient at

distributing diversion flows of freshwater, nutrients and sediments. A complete discussion of this

can be found in the Engineering Appendix L.

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Final Integrated K-4 September 2010Feasibility Study / SEIS

Table 1. LCA: White Ditch Incremental Cost/Cost Effectiveness Step 1a

Operating Regimes Gross/Net Acres

(Original Study Area)

Year 50

Operating Regimes Gross/Net

Acres (Expanded Study Area)

Year 50

Alternative

Total First

Cost*

Annualized

Cost**

Original Project Area

- Open Diversion

Original Project Area -

Mar/May Pulse

Original Project Area

- March Pulse +

1,000 CFS

Expanded Project

Area Open

Diversion

Expanded

Project Area

Mar/May

Pulse

Location 2 - 5,000 CFS Box $181,800,000 $9,013,128 35,241/-5,965 32,676/-8,530 34,484/-6,722 69,251 64,481Location 2 - 10,000 CFS Box $230,000,000 $11,402,748 43,448/2,242 38,071/-3,135 36,318/-4,888 80,924 70,298Location 2 - 15,000 CFS Box $398,600,000 $19,761,458 51,445/10,239 43,327/2,121 38,111/-3,095 92,668 76,099Location 2 - 35,000 CFS Box $493,400,000 $24,461,373 76,174/34,968 59,670/18,464 44,364/3,155 139,965 98,909Location 3 - 5,000 CFS Box $140,600,000 $6,970,549 35,241/-5,965 32,676/-8,530 34,484/-6,722 69,251 64,481Location 3 - 10,000 CFS Box $165,000,000 $8,180,232 43,448/ 2,242 38,071/-3,135 36,318/-4,888 80,924 70,298Location 3 - 15,000 CFS Box $229,400,000 $11,373,001 51,445/10,239 43,327/2,121 38,111/-3,095 92,668 76,099Location 3 - 35,000 CFS Box $334,800,000 $16,598,435 76,174/34,968 59,670/18,464 44,364/3,155 139,965 98,909*Excludes Real Estate and O&MRRR**FY 2010 Discount Rate 4 3/8%

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Appendix K: Benefit/Cost – Incremental Cost Analysis Volume VI – Medium Diversion at White Ditch

Final Integrated K-5 September 2010Feasibility Study / SEIS

Table 2. LCA: White Ditch Incremental Cost/Cost Effectiveness Step 1b

Incremental Cost/Cost Effectiveness Analysis

- Open Operation

Incremental Cost/Cost Effectiveness Analysis

Mar/May Pulse

Alternative

Open

Diversion

(Average

Annual Acres) Incremental Cost

Incremental

Acres

Incremental

Cost per Acre

Mar/May

Pulse

(Average

Annual

Acres)

Incremental

Cost

Incremental

Acres

Incremental

Cost per Acre

Location 2 - 5,000 CFS Box 5,276 Non Cost 2,715 Non CostLocation 2 - 10,000 CFS Box 11,553 Effective 5,853 EffectiveLocation 2 - 15,000 CFS Box 17,860 Plans 8,984 PlansLocation 2 - 35,000 CFS Box 42,731 21,282Location 3 - 5,000 CFS Box 5,276 $6,970,549 5,276 $1,321 2,715 $6,970,549 2,715 $2,567Location 3 - 10,000 CFS Box 11,553 $1,209,683 6,277 $193 5,853 $1,209,683 3,138 $385Location 3 - 15,000 CFS Box 17,860 $10,163,318 11,583 $877 8,984 $10,163,318 5,846 $1,739Location 3 - 35,000 CFS Box 42,731 $6,435,117 31,148 $207 21,282 $6,435,117 15,436 $417*Excludes Real Estate and O&MRRR**FY 2010 Discount Rate 4 3/8%

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2.2 CE/IC Analysis

In order to refine the preliminary alternatives further a two-step Cost Effectiveness &

Incremental Cost (CE/IC) Analysis was utilized. The first step used preliminary cost estimates

developed for each action alternative and outputs from the ERDC SAND2 Model. Table 2

displays the CE/IC analysis of the action alternatives. Average Annual Acres of Marsh is

compared against the annualized first cost of the action alternatives. Average Annual Acres of

Marsh produced by each size of diversion structure is the same for each location. All of the

alternatives at location 2 were not cost effective while the 5, 10 and 15 thousand cfs diversions at

location 3 were found to be cost effective. The 35,000 cfs diversion was considered a best buy.

Figure 1. White Ditch CE/IC Analysis – Open Diversion

WD 6

WD 7

WD 8

WD 9

No Action

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Figure 2. White Ditch CE/IC Analysis Step 1 – Mar/May Pulse

2.3 Alternative Plans not Carried for Further Analysis

Based on the above analysis it was determined that the following alternatives would not further

evaluated:

• White Ditch (WD) 2: Location 2 – 5,000 cfs.

• White Ditch (WD) 3: Location 2 – 10,000 cfs.

• White Ditch (WD) 4: Location 2 – 15,000 cfs.

• White Ditch (WD) 5: Location 2 – 35,000 cfs.

3.0 FINAL ARRAY OF ALTERNATIVES

3.1 No Action (Future without Project Conditions)

No Action The future without project condition for White Ditch will continue to see declines in

overall wetland acres of all types. The current altered deltaic process will result in the lack of

freshwater, nutrients and sediments in the project are that are critical to sustain existing marsh

and build additional areas. Overall the study area is expected to see an average loss of 274.5

WD 6

WD 7

WD 8

WD 9

No Action

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acres of marsh per year. This land loss will, during the 50 year period of analysis, result in a

further loss of 13,725 acres of marsh from the 2009 acreage of 41,206.

Figure 3. Louisiana Coastal Area: Medium Diversion at White Ditch – Future Without Project

Condition

Waterbodies would grow larger and wave erosion would accelerate causing further land loss,

making remaining marsh lands in the project area and the larger Breton Sound Basin more

vulnerable to tropical storms. The Future Without Project Condition will likely see the existing

marsh persist with minimal circulation of water, nutrients, and sediment. The sediment deficit

has and would continue to result in both subsidence and a disruption of natural processes that

promote productivity and diversity in the marsh ecosystem. Increases in relative sea level due to

continued subsidence and sea level rise would continue to inundate plant communities, which

would ultimately lead to substantial losses. The Study Area will likely see additional salt water

intrusion and conversion of the remaining intermediate and brackish marsh to saline marsh types

with the associated salt-tolerant or marine fauna.

The remaining marsh acreage of 27,481 does not account for any losses that may be incurred by

moderate or high rates of sea level rise. The figure below depicts the impacts of both the

moderate and high rates of sea level rise on the project area.

50,590

Marsh

Acres

1985

2008 2059

41,206

Marsh

Acres

27,481

Marsh

Acres

Time: 50-years period

of analysis

Future without project condition

Quality

(acres)

Loss of 9,384

Acres (1985-

2008)

Loss of

13,725 Acres

(2009-2059)

Window of

Uncertainty

Louisiana Coastal Area: Medium Diversion at White Ditch

Future Without Project Condition

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Figure 4. Relative Sea Level Rise: Medium and High Scenario Impacts on Future Without Project

Condition

Marsh acres are the result of a variety of physical structure and functions within the larger

ecosystem. Some of these components include soils and waterbottoms, sediment, subsidence,

salinity, riparian vegetation, benthics and fishery resources. Summaries of the future without

project condition for these resources are below with more details provided in Section 4.

3.1.1 Soils and Waterbottoms

No direct alteration of soils or substrate would occur under the No Action alternative and

associated water management features. No conversion of prime or unique farmland would occur,

and the No Action alternative would have no direct impact on these resources.

The indirect impacts of the No Action alternative, would be that the existing patterns of soil

erosion and land loss would continue into the future. Organic soils in the project area would not

be able to maintain their elevations due to subsidence, decreased plant productivity, wave

erosion, and relative sea level rise. Net primary productivity within the project area would

continue to decline and existing wetland vegetation would continue to diminish. The ongoing

conversion of existing fragmented emergent wetlands to shallow open water would continue with

associated indirect impacts on coastal vegetation, fish and wildlife resources, EFH, recreation,

aesthetic, and socioeconomic resources. In the future, if no actions are taken to restore and

protect marsh habitat within the project area, any prime and unique farmland that remains

outside of the protection of existing Federal and non-Federal back levees would continue to be

subject to further degradation and possible loss.

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Cumulative impacts under the No Action alternative include continuing erosion and loss of

marsh soils. Waterbodies would grow larger and wave erosion would accelerate causing further

land loss, thus making remaining marsh lands in the project area and the larger Breton Sound

Basin more vulnerable to tropical storms. In addition to land loss in coastal Louisiana, a large

percentage of the Nation’s wetlands would continue to disappear with accompanying impacts to

wildlife, fisheries, coastal communities, and socioeconomic resources.

3.1.2 Sedimentation and Erosion

The No Action Alternative, i.e. not implementing a sediment and freshwater diversion in the

White Ditch Study Area, would have a direct impact on sedimentation or erosion within the area

between the Mississippi River and River aux Chenes through the continuation of existing

degradation of marsh. The absence of a supply of fresh water, sediment, and nutrients combined

with the ongoing pressures of wind and wave action, storm surges, and human activities has

severely eroded marsh soils and reduced the ability of the project area to maintain a balance of

emergent wetland and shallow water.

Indirect impacts of the No Action Alternative, not implementing the diversion, are the

persistence of existing conditions. Consequences would include further degradation of the

existing marsh from saltwater intrusion due to short circuited hydrologic processes present in the

basin; as well as the continued lack of sediments, nutrients, and freshwater River aux Chenes and

the Mississippi River. With the absences of these features, the marsh would not be able to sustain

itself against subsidence and prolonged inundation from sea level rise. The No Action

Alternative would cause the existing marsh to persist with minimal circulation of water,

nutrients, and sediment. The sediment deficit has and would continue to result in both subsidence

and a disruption of natural processes that promote productivity and diversity in the marsh

ecosystem. Increases in relative sea level due to continued subsidence and sea level rise would

continue to inundate plant communities, which would ultimately lead to substantial losses.

Cumulative impacts would be the synergistic effect of the No Action Alternative on other

sedimentation and erosive forces with the added combination of similar wetland degradation and

wetland loss impacts to sedimentation and erosion throughout coastal Louisiana, as well as the

benefits and impacts of other state and Federal coastal restoration projects in the vicinity.

3.1.3 Subsidence

The Future Without Project Condition will likely see the existing marsh to persist with minimal

circulation of water, nutrients, and sediment. The sediment deficit has and would continue to

result in both subsidence and a disruption of natural processes that promote productivity and

diversity in the marsh ecosystem. Increases in relative sea level due to continued subsidence and

sea level rise would continue to inundate plant communities, which would ultimately lead to

substantial losses.

3.1.4 Salinity

Under the No Action Alternative no direct impacts to salinity levels of the Mississippi River or

the White Ditch project area would occur.

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Indirect impacts of not implementing restoration features would result in the persistence of

existing conditions for the Mississippi River and continued degradation of the White Ditch

project area.

Cumulative impacts would be the synergistic effect of the No Action Alternative on salinity

levels when considered in context with all past, present, and reasonably foreseeable acts of

nature and/or the actions private entities, state government, and Federal government. The No

Action Alternative would not contribute in a positive or negative manner to the cumulative

effects on salinity.

3.1.5 Vegetation Resources

Direct impacts under the No Action Alternative, no construction of diversion structure or

associated outfall management features would occur, and no BLH would be cleared or filled by

construction activities. No opportunities for beneficial use of dredged material for construction

features would occur. Existing BLH in the project footprint would continue to degrade and

convert to intermediate marsh. No direct impacts to existing wetland vegetation resulting from

construction of the proposed diversion and associated features would occur. No opportunities for

beneficial reuse of marsh soil and substrate excavated for construction would be realized. No

direct impacts to Submerged Aquatic Vegetation (SAV) would occur. Baseline SAV coverage

was estimated at approximately 15% of open water areas in the vicinity of the proposed

construction footprint (25% in the overall project area). Existing SAV in the project footprint

would continue to degrade and die off as increased salinities enter the Study Area and marsh

continues to decrease in acreage

Without implementation of the proposed diversion, no input of sediment, freshwater and

nutrients to the project area would occur. This would result in indirect impacts including the

continued erosion of marsh soils and continued fragmentation and conversion of BLH to

intermediate and brackish marsh habitats. Both man-made and natural processes would

contribute to the continued loss of vegetated habitats, including: continued erosion and

subsidence, increased saltwater intrusion, and increased water velocities. Over the next 50 years,

the remaining BLH species in the Study Area would experience continued subsidence, sea level

rise, and salinity increases. The BLH would eventually diminish and convert to marsh. Over the

next 50 years, approximately 13,750 acres of emergent marsh is projected to be lost, and it is

likely that all remaining remnants of bottomland hardwood vegetation would disappear over the

same period. Over the next 50 years, SAV is projected to be reduced from the estimated baseline

of 25% of open water areas to approximately 15% as the area deteriorates.

Cumulative impacts would be the same effect of the No-Action alternative with land loss rates of

approximately 274.5 acres per year throughout the 50-year project life. In addition, cumulative

impacts would include the additive combination of coast wide BLH loss and degradation, as well

as the benefits and impacts of other local, state, Federal, and private projects summarized in

Section 1.5. The existing freshwater diversion at Caernarvon would freshen the surrounding

waters, albeit to an unknown extent. In addition, the LCA Caernarvon Freshwater Diversion

Modification (CFDM) project could potentially result in a selected plan having features that

create and restore BLH ridges from the secondary use of channel dredging to redirect water

flows. Some Section 10 and 404 permits have been issued by the CEMVN for maintenance

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dredging canals northeast of the WDWD project. Some dredged material placement areas from

this dredging would likely reforest with BLH species.

Cumulative impacts on wetland vegetation would be the synergistic effect of implementing the

No-Action Alternative with the additive combination of coast wide wetland loss and degradation,

as well as the benefits and impacts of other state and Federal projects in the vicinity. The existing

freshwater diversion at Caernarvon would freshen the surrounding waters, albeit to an unknown

extent. Modification of the operation of the Caernarvon structure could result in a conversion of

some intermediate marsh to fresh marsh in areas adjacent to the MDWD project area. However,

such wetland conversion would probably have little effect on the species composition of the

wetlands in the project area other than a slight shift towards less salt-tolerant species. The

introduction of nutrients would likely increase the productivity of the nearby marshes, but any

potential effects on productivity within the MDWD project area are unknown at this time.

Cumulative impacts would be the same effect of the No-Action alternative with the additive

combination of coast wide SAV loss, as well as the benefits and impacts of other state, Federal,

or private projects summarized in the FS/EIS. The proposed projects have borrow areas, channel

dredging, and marsh restoration sites in and adjacent to Lake Lery that would impact SAV from

dredging and filling. CFDM could result in a conversion of some intermediate marsh to fresh

marsh in areas adjacent to the MDWD project area. The Duffy (1997) study showed that SAV

abundance (Eurasian watermilfoil and coontail) has increased in the Breton Sound Basin in

response to diversions. The introduction of nutrients would likely increase the productivity of the

nearby SAV, but any potential effects on productivity within the MDWD project area are

unknown at this time.

3.1.6 Benthics

The Future Without Project Condition will likely see marine (saltwater) influences continue to

take hold and convert freshwater wetlands into intermediate, brackish, and saline marsh. As

freshwater inputs continue to decline and allow marine influences to predominate over riverine

influence, salinity levels rise, resulting in the conversion of low-lying vegetated areas to open

water and the redistribution of marine sediment. These actions eventually lead to conditions that

expedite interior marsh loss and the benthic community and benthic processes would shift from

that of an estuarine community to a more open water marine community. Over the long term,

without renewed inputs of fresh water, sediment, and nutrients to restore and maintain emergent

marsh habitat, the project area is likely to convert from a predominately estuarine habitat to a

predominately marine habitat. The benthic community which support the estuarine system

processes would be adversely affected by the reduction and eventual loss of this habitat.

3.1.7 Essential Fish Habitat

The No Action alternative (no construction of river diversion structure or associated outfall

management features) would have no direct impact on EFH.

Indirect impacts of not implementing wetland creation/nourishment and shoreline protection

features would result in the persistence of existing conditions resulting in the conversion of

categories of EFH, such as estuarine marsh and SAV, to marine water column and mud, sand, or

shell substrates is expected to continue. Over time, the No Action alternative would result in the

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conversion of an estimated 13,724 acres of emergent marsh to open water. Substantial decreases

in the quality of EFH in the project area would reduce the area’s ability to support federally

managed species.

Cumulative impacts would be the synergistic effect of the No-Action Alternative on EFH with

the additive combination of similar EFH degradation and losses throughout coastal Louisiana, as

well as the benefits and impacts of other state and Federal projects in the vicinity. Continued

conversion of existing marsh to shallow open water habitats anticipated with the No Action

alternative would contribute to declining quality of EFH, particularly nursery habitat for larval

and juvenile fish and shrimp species.

3.2 Alternative 1  5,000 cfs diversion

Location 3 – 5,000 cfs. This alternative involves construction of a structure capable of diverting

up to 5,000 cfs consisting of 3 15ft. x 15ft. box culverts. Additionally, 32 acres of ridge and

terrace creation, 139 acres of marsh creation utilizing dredged material from an adjacent 153

acres of canal being reconfigured to convey freshwater, nutrient and sediments.

Figure 5. Alternative 1 Location 3

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3.3 Alternative 2  10,000 cfs Max Diversion

Location3–10,000 cfs. This alternative involves construction of a structure capable of

diverting up to 10,000 cfs consisting of 3 15ft. x 15ft. box culverts. Additionally, 32 acres of

ridge and terrace creation, 176 acres of marsh creation utilizing dredged material from an

adjacent 167 acres of canal being reconfigured to convey freshwater, nutrient and sediments.

Figure 6. Alternative 2 Location 3

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3.4 Alternative 3  15,000 cfs Max Diversion

Location3–15,000 cfs. This alternative involves construction of a structure capable of

diverting up to 15,000 cfs consisting of 10 15ft. x 15ft. box culverts. Additionally, 32 acres of

ridge and terrace creation, 235 acres of marsh creation utilizing dredged material from an

adjacent 182 acres of canal being reconfigured to convey freshwater, nutrient and sediments.

Figure 7. Alternative 3 Location 3

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3.5 Alternative 4  35,000 cfs Max Diversion (TSP)

Location3–35,000 cfs. This alternative involves construction of a structure capable of

diverting up to 35,000 cfs consisting of 10 15ft. x 15ft. box culverts. Additionally, 31 acres of

ridge and terrace creation, 385 acres of marsh creation utilizing dredged material from an

adjacent 223 acres of canal being reconfigured to convey freshwater, nutrient and sediments.

Figure 8. Alternative 4 Location 3

4.0 COMPARISON OF ALTERNATIVE PLANS

This section describes the alternative plans and the process used to determine the potential costs,

habitat benefits, incremental cost/cost effectiveness, and other factors leading to a recommended

plan.

4.1 Incremental Cost/Cost Effectiveness Analysis Process.

Cost effectiveness analysis was used to determine what project features should be built, based on

habitat benefits (outputs) that meet the goals and objectives of the project and at the same time

are the most cost effective. The Corps has incorporated cost effectiveness analysis into its

planning process for all ecosystem restoration planning efforts. A cost effectiveness analysis is

conducted to ensure that least cost alternatives are identified for various levels of output. After

the cost effectiveness of the alternatives has been established, incremental cost analysis is

conducted to reveal and evaluate changes in cost for increasing levels of environmental output.

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Cost effectiveness and incremental analysis is a three step procedure: (1) calculate the

environmental outputs of each alternative; (2) determine a cost estimate for each alternative; (3)

combine the alternatives to evaluate the best overall project alternative based on habitat benefits

and cost. While cost and environmental outputs are necessary factors, other factors such as the

ability to construct, schedule, likelihood to achieve projected results, unmeasurable

environmental benefits, ancillary benefits etc., are very important in deciding on the preferred

alternative.

Environmental outputs were calculated as Average Annual Habitat Units (AAHUs). The

annualized costs were calculated by applying a 4-3/8% annual interest rate to the construction

costs over the 50-year period of analysis. What is described below is the second step of the

process introduced in Section 1.1.1 above.

4.2 Wetland Value Assessment (WVA)

The Wetland Value Assessment (WVA) methodology is a quantitative habitat-based assessment

methodology developed for use in determining wetland benefits of project proposals submitted

for funding under the Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA).

The WVA quantifies changes in fish and wildlife habitat quality and quantity that are expected to

result from a proposed wetland restoration project. The results of the WVA, measured in

Average Annual Habitat Units (AAHUs), can be combined with cost data to provide a measure

of the effectiveness of a proposed project in terms of annualized cost per AAHU gained. In

addition, the WVA methodology provides an estimate of the number of acres benefited or

enhanced by the project and the net acres of habitat protected/restored. See Appendix B for a

complete description of the WVA and its application to this project.

The WVA was developed by the Environmental Work Group (EnvWG) assembled under the

Planning and Evaluation Subcommittee of the CWPPRA Technical Committee; the EnvWG

includes members from each agency represented on the CWPPRA Task Force and members of

the Academic Assistance Subcommittee. The WVA was designed to be applied, to the greatest

extent possible, using only existing or readily obtainable data.

The WVA has been developed strictly for use in determining the wetland benefits of proposed

CWPPRA projects; it is not intended to provide a detailed, comprehensive methodology for

establishing baseline conditions within a project area. Some aspects of the WVA have been

defined by policy and/or functional considerations of the CWPPRA; therefore, user-specific

modifications may be necessary if the WVA is used for other purposes.

The WVA is a modification of the Habitat Evaluation Procedures (HEP) developed by the U.S.

Fish and Wildlife Service (U.S. Fish and Wildlife Service 1980). HEP is widely used by the Fish

and Wildlife Service and other Federal and State agencies in evaluating the impacts of

development projects on fish and wildlife resources. A notable difference exists between the two

methodologies, however, in that HEP generally uses a species-oriented approach, whereas the

WVA utilizes a community approach.

The WVA has been developed for application to several habitat types along the Louisiana coast

and community models have been developed for fresh marsh, intermediate marsh, brackish

marsh, saline marsh, fresh swamp, barrier islands, and barrier headlands (Attachments 1-4). A

WVA Procedural Manual has also been prepared by the EnvWG to provide guidance to project

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planners in the use of the various community models. Two other habitat assessment models for

bottomland hardwoods and coastal chenier/ridge habitat were developed outside of the

CWPPRA arena and are periodically used by the EnvWG.

Habitat types impacted by construction of the MDWD outfall management features (channel

enlargement, marsh creation, and ridge creation) are intermediate marsh and open water in the

intermediate salinity zone. Habitat types impacted by operation of the MDWD are intermediate,

brackish, and saline marsh, and open water in the intermediate, brackish, and saline zones.

Project implementation will create two habitat types found historically but not currently present

in the impacted area – fresh marsh and ridge. Consequently, the WVA assessment for MDWD

utilized community models for fresh/intermediate marsh, brackish marsh, saline marsh, and

coastal chenier/ridge habitat.

4.2.1 WVA Concept

The WVA operates under the assumption that optimal conditions for fish and wildlife habitat

within a given coastal wetland habitat type can be characterized, and that existing or predicted

conditions can be compared to that optimum to provide an index of habitat quality. Habitat

quality is estimated or expressed through the use of community models developed specifically

for each habitat type. Each model consists of 1) a list of variables that are considered important

in characterizing fish and wildlife habitat, 2) a Suitability Index graph for each variable, which

defines the assumed relationship between habitat quality (Suitability Index) and different

variable values, and 3) a mathematical formula that combines the Suitability Index for each

variable into a single value for habitat quality; that single value is referred to as the Habitat

Suitability Index, or HSI. The output of each model (the HSI) is assumed to have a linear

relationship with the suitability of a coastal wetland system in providing fish and wildlife habitat.

The WVA models have been developed for determining the suitability of Louisiana coastal

wetlands in providing resting, foraging, breeding, and nursery habitat to a diverse assemblage of

fish and wildlife species. The models have been designed to function at a community level and

therefore attempt to define an optimum combination of habitat conditions for common fish and

wildlife species utilizing a given habitat type. Earlier attempts to capture other wetland functions

and values such as storm-surge protection, flood water storage, water quality functions, and

nutrient import/export were abandoned due to the difficulty in defining unified model

relationships and meaningful model outputs for such a variety of wetland benefits. However, the

ability of a Louisiana coastal wetland to provide those functions and values may be generally

assumed to be positively correlated with fish and wildlife habitat quality as predicted through the

WVA.

4.2.2 Community Model Variable Selection

Habitat variables considered appropriate for describing habitat quality in each wetland type were

selected according to the following criteria:

• The condition described by the variable had to be important in characterizing fish and

wildlife habitat quality in the wetland type under consideration;

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• Values had to be easily estimated and predicted based on existing or readily obtainable

data (e.g., aerial photography, habitat classification data, water quality monitoring

stations, interviews with knowledgeable individuals, etc.); and

• The variable had to be sensitive to the types of changes expected to be brought about by

typical wetland restoration projects proposed under the CWPPRA.

• The marsh community models used in the WVA assessment for the MDWD

(fresh/intermediate, brackish, and saline) all utilize the same habitat variables. These are:

1) percent of wetland (marsh) covered by emergent vegetation; 2) percent of open water

covered by submerged and floating-leaved aquatic vegetation; 3) Marsh edge and

interspersion with open water; 4) percent of open water less than or equal to 1.5 feet

deep in relation to marsh surface; 5) salinity; and 6) aquatic organism access.

4.2.3 Suitability Index Graphs

A suitability index graph is a graphical representation of how fish and wildlife habitat quality or

"suitability" of a given habitat type is predicted to change as values of the given variable change,

and allows the model user to numerically describe, through a Suitability Index, the habitat

quality of a wetland area for any variable value. Each Suitability Index ranges from 0.1 to 1.0,

with 1.0 representing the optimal condition for the variable in question. Suitability Index (SI)

graphs were constructed for each variable. While the three marsh community models used for

the MDWD utilize the same six variables, the suitability graphs for each variable differ

according to the marsh community type (fresh/intermediate, brackish, or saline).

4.2.4 Habitat Suitability Index Formula

The final step in model development was to construct a mathematical formula that combines all

Suitability Indices into a single Habitat Suitability Index value. Because the Suitability Indices

range from 0.1 to 1.0, the HSI also ranges from 0.1 to 1.0, and is a numerical representation of

the overall or "composite" habitat quality of the particular wetland area being evaluated. The

HSI formula defines the aggregation of Suitability Indices in a manner unique to each wetland

type depending on how the formula is constructed.

Within an HSI formula, any Suitability Index can be weighted by various means to increase the

power or "importance" of that variable relative to the other variables in determining the HSI.

Additionally, two or more variables can be grouped together into subgroups to further isolate

variables for weighting.

4.2.5 Benefit Assessment

The net benefits of a proposed project are estimated by predicting future habitat conditions under

two scenarios: future without-project and future with-project. Specifically, predictions are made

as to how the model variables will change through time under the two scenarios. Through that

process, HSIs are established for baseline (pre-project) conditions and for future without- and

future with-project scenarios for selected "target years" throughout the expected life of the

project. Those HSIs are then multiplied by the project area acreage at each target year to arrive

at Habitat Units (HUs). Habitat Units represent a numerical combination of quality (HSI) and

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quantity (acres) existing at any given point in time. The HUs resulting from the future withoutand future with-project scenarios are annualized, averaged over the project life, to determine

Average Annual Habitat Units (AAHUs). The "benefit" of a project can be quantified by

comparing AAHUs between the future without- and future with-project scenarios. The

difference in AAHUs between the two scenarios represents the net benefit attributable to the

project in terms of habitat quantity and quality. The starting point for the WVA 50 year period

of analysis was assumed to be 2015 based upon the current schedule to complete Plans &

Specifications and Construction. This 2015 date differs slightly from the 2009 used in the

previous iterations of the planning process. While the starting point of the analysis has changes

between steps (2015 compared to 2009) the entire final array of alternatives was evaluated on

equal terms and therefore the comparison of alternatives and their respective benefits is valid.

The WVA assessment for the MDWD utilized habitat and land-water data generated by USGS

for the project area, aerial photography, monitoring and hydrodynamic modeling data (for

salinity) and also used field survey data collected for WVAs recently conducted for other,

smaller CWPPRA projects within and adjacent to the MDWD project area. Separate WVA

analyses were conducted for each marsh type and each diversion size alternative, and for each

outfall management feature type. Target year 0 (TY0) was assumed to be 2015. The WVA

analyses conducted for the future-without-project (FWOP) condition used two target years – 1

(TY1) and 50 (TY50) to assess changes in the project area over the 50-year planning horizon.

Analyses of the future-with-project (FWP) condition also used TY1 and TY50, but added a

target year 5 (TY5) within the 50-year planning horizon. TY5 was used in the FWP analyses

because review of hydrodynamic modeling outputs projecting salinities indicated that a portion

of the intermediate marsh area would transition to fresh marsh within a few years following the

start of project operation. More detailed information concerning data sources, variable

assumptions, anticipated habitat changes, and performance of the diversion alternatives over time

is presented in an appendix to the USFWS Coordination Act Report at Appendix B.

4.2.5 MDWD Summary

Following the multiple operating regimes analyzed as part of Step 1 described previously, an

optimal operating regime was established based on the best available supplies of freshwater,

nutrients and sediments while avoiding the negative impacts of open diversions on the public,

oyster and alligator resources. A March/April Open Pulse with a 1,000 cfs maintenance flow the

rest of the year would achieve these ends. The WVA for the MDWD project is summarized

below:

Table 3. Direct Footprint Acreage Impacts

Ridge

Creation

Marsh

Creation

Channel

Enlargement

Alternative 1: Location 3 – 5,000 cfs Diversion 32 139 153

Alternative 2: Location 3 – 10,000 cfs Diversion 32 176 167

Alternative 3: Location 3 – 15,000 cfs Diversion 32 235 182

Alternative 4: Location 3 – 35,000 cfs Diversion 31 385 223

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Table 4a: WVA Benefits Summary

Benefits Summary

Outfall Management Features

Feature 5,000 cfs 10,000 cfs 15,000 cfs 35,000 cfs

Marsh Creation 54.59 72.52 92.19 155.20

Channel Enlargement -15.99 -19.08 -21.89 -31.25

Ridge Footprint -11.33 -11.33 -11.33 -11.37

Ridge Creation 28.24 28.24 28.24 27.36

Net AAHUs 55.51 70.35 87.21 139.94

Diversion Benefits

Marsh Type 5,000 cfs 10,000 cfs 15,000 cfs 35,000 cfs

Fresh/Intermediate 3,505.05 3,862.13 5,650.28 8,802.11

Brackish 1,359.93 1,655.31 1,656.16 3,965.54

Saline 276.26 347.78 347.97 447.42

Net AAHUs 5,141.24 5,86522 7,65441 13,215.07

Total Net AAHUs 5,196.75 5,935.57 7,741.62 13,355.01

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Table 5b. Acreage Summary

MDWD Final Array of Alternatives

WVA AAHU’s

March/Aprl Open +

1,000 cfs Maintenance Flow

Year 0 = 2015

Gross/Net Acres

March/Aprl Open +

1,000 cfs Maintenance Flow

Year 0 = 2015

No Net Loss Acres = 39,587

Location 3 – 5,000 cfs 5,197 35,638 / -3,949

Location 3 – 10,000 cfs 5,936 40,419 / 562

Location 3 – 15,000 cfs 7,742 45,046 / 5,459

Location 3 – 35,000 cfs 13,555 59,902 /20,315

4.3 Cost Estimates for Habitat Improvement Measures.

Cost estimates were developed to conduct the cost effectiveness and incremental cost analysis of

the various alternative plans. Items included in the first cost construction estimated are

mobilization, dredging, placement, demobilization, contingency, Engineering and Design during

Construction (EDC), Supervision & Administration (S&A), Real Estate and Operations and

Maintenance. Table 3.12 summarizes the costs associated with each alternative plan. Following

selection of the TSP, the design will be refined and a feasibility level cost estimate prepared in

MCACES. Therefore, the cost of the recommended plan may differ from the numbers used

during IC/CE analysis. Further details can be found in the Engineering and Cost Appendices.

Table 6. LCA: White Ditch Cost Estimates

Alternative

Total First

Cost*

Annualized

O&MRRR

Annualized

First Cost**

Total

Annualized

Cost

Location 3 - 5,000 CFS Box $152,900,000 $781,804 $7,580,348 $8,362,152

Location 3 - 10,000 CFS Box $174,200,000 $871,463 $8,636,342 $9,507,805

Location 3 - 15,000 CFS Box $241,700,000 $1,131,044 $11,982,801 $13,113,845

Location 3 - 35,000 CFS Box $329,300,000 $1,467,836 $16,325,760 $17,793,596

*Includes Real Estate

**FY 2010 Discount Rate 4 3/8%

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4.4 Results of the Incremental Cost/Cost Effectiveness Analysis

The analyses showed that alternative plans 1, 2, 3, and 4 are cost effective. Aside from the No

Action alternative, Alternative 4 exhibited the lowest cost per Unit of all alternatives, $1,332 per

AAHU. Alternative 3 exhibited the highest cost per Unit at $1,694 per AAHU.

Table 7. White Ditch Incremental Cost/Cost Effectiveness Step 2

Alternative

Total

Annualized

Cost WVA AAHU

Average Cost

per AAHU

Location 3 - 5,000 CFS Box $8,362,152 5,197 $1,609

Location 3 - 10,000 CFS Box $9,507,805 5,936 $1,602

Location 3 - 15,000 CFS Box $13,113,845 7,742 $1,694

Location 3 - 35,000 CFS Box $17,793,596 13,355 $1,332

*Includes Real Estate

**FY 2010 Discount Rate 4 3/8%

Overall, alternative 4 was considered a best buy plan. However, as the plans are linear in benefits

and costs, a CE/IC analysis was conducted on all of the alternatives. These plans provide the

greatest increase in benefits for the least increase in cost.

The No Action Alternative (FWOP) is cost effective, however provides no improvement in

habitat quality resulting in steep declines in marsh. Alternative plan 1 provides 5,197 AAHUs

over and above the No Action Alternative (FWOP) at an annualized incremental cost of

$8,362,152 (tables 3.11 and 3.12). Alternative plan 2 provides 739 additional AAHUs, at an

annualized incremental cost of $1,145,653. Alternative plan 3 provides 1,806 additional AAHUs,

at an annualized incremental cost of $3,606,040. Alternative Plan 4 provides 5,613 additional

AAHUs at an annualized incremental cost of $4,679,752. Alternative 4 has the lowest

incremental cost per AAHU of $834.

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Figure 9. CE/IC Analysis of Final Alternatives

No Action

Alt 1

Alt 2

Alt 3

Alt 4

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Table 8. White Ditch Incremental Cost/Cost Effectiveness Step 2

Incremental Cost/Cost Effectiveness

Analysis of Cost Effective Plans

Alternative

Total

Annualized

Cost WVA AAHU

Incremental

Cost

Incremental

AAHU

Incremental

Cost per

AAHU

Location 3 - 5,000 CFS Box $8,362,152 5,197 $8,362,152 5,197 $1,609

Location 3 - 10,000 CFS Box $9,507,805 5,936 $1,145,653 739 $1,550

Location 3 - 15,000 CFS Box $13,113,845 7,742 $3,606,040 1,806 $1,997

Location 3 - 35,000 CFS Box $17,793,596 13,355 $4,679,752 5,613 $834

*Includes Real Estate

**Discount Rate 4 3/8%

Figure 10. CE/IC Best Buy Plans

4.5 Other Factors

As part of the process to determine whether additional increments of ecosystem investment are

worth the cost, other factors were considered.

Alt 4

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4.5.1 Recreational Benefits

The primary purpose of the White Ditch Study is to determine a cost effective ecosystem

restoration plan, however there are potential ancillary benefits to recreation. Recreation benefits

are not being claimed to justify the project but are useful in discerning among the final

alternatives. A complete analysis can be found in the Recreation Benefits Analysis Annex to

Appendix K.

Given that the study area has 90,109 unit days per year and that each unit day is valued at $8.99,

the total annual monetary value of the recreational resource that would be affected by the White

Ditch project is $810,256. Given that the likelihood at success with fishing will increase and that

environmental factors will improve over time if the proposed project is implemented, the total

annual monetary value of the recreational resource will increase in the future compared to the

annual monetary value of the recreational resource should the proposed project not be

implemented.

To better understand the economic impact of the proposed project on recreation, the analysis

considered effects over a 50-year period. The analysis uses the Federal discount rate for 2009 of

4 3/8%. The following table summarizes the potential net present value of recreational resources

for each alternative.

Table 9. Net Increase in Recreation Benefits

Without

Project Alternative 1 Alternative 2 Alternative 3 Alternative 4

Net Present Value

of Benefits over 50

years

$0 $1,206,000 $1,278,000 $1,421,000 $853,000

Annualized

Benefits $0 $57,284 $60,704 $67,496 $40,517

4.5.2 Desired Future Condition

The desired future established early on in the study was to achieve a no net loss of marsh acres at

the end of the 50-year period of analysis. While it was desirable to maximize the acres of marsh,

it was uncertain if that was possible given the various physical and operational constraints. The

outputs of the ERDC SAND model are one of the key components in the WVA. Based on the

ERDC SAND results, Alternative 4 provided the most net acres at the end of period of analysis.

In fact it is probable, based on the modeling, that the study area could see a return to historic

marsh acreages. Finally, the IC/CE analysis of the final array of alternatives utilized WVA

benefits based in part on an operation regime of Open Diversion during March-April with a

1,000 cfs maintenance flow the remainder of the year. As can be seen in the Figure below, under

a variety of operating regimes, Alternative 4 is the most capable at achieving no net loss.

Alternative 3 has the potential to achieve no net loss but there is no room for error. This

uncertainty was viewed by the PDT and stakeholders as unacceptable.

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Figure 11. FWP Acres at TY50 per Operational Plan

4.5.3 Relative Sea Level Rise

An analysis of the high sea level rise scenario was conducted utilizing the ERDC-SAND2 model.

The model was used to determine whether a net loss or gain of marsh acreage would occur

assuming a high sea level rise scenario. Alternative 4 was the most effective at countering the

effects of high sea level rise. Alternative 4 could maintain marsh acreage out to approximately

year 20 of the analysis which was then quickly followed by a sharp decline and eventual collapse

of the marsh and near total conversion to open water. This result was based on the March/April

Pulse plus a 1,000 cfs maintenance flow the rest of the year. Table 9 and Table 10 display these

details. It should be noted however, that in the event high sea level rise becomes a reality,

Alternative 4 alone has the capability (assuming an open diversion) to divert large enough

quantities of freshwater, nutrients and sediments to overcome high sea level rise. Longer term

pulses of freshwater may result in large scale habitat switching to predominately freshwater

types. Further, long term freshwater pulses can saturate marsh vegetation and soils such that they

are less resilient to storm surge from seasonal events resulting in marsh displacement and

conversion to open water. There is strong public feeling that the prolonged operation of

Caernarvon prior to Katrina contributed to the severe loss of marsh. While not publicly

acceptable at present (due to the anticipated negative consequences of over-freshening the basin),

if the collapse of the marsh within the study areas was imminent, then having the ability to

respond accordingly with a year round open diversion would be critical.

FWP Acres at TY50 per Operational Plan

39,587 acres needed to achieve no net loss

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

5k 10k 15k 35k

F

W

P

T

Y

5

0

A

c

r

e

s

March‐May + 1,000

March‐April + 1,000

March + 1,000

No Net Loss

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Feasibility Study / SEIS

Figure 12. Comparison of Relative Sea Level Rise Effects

Table 10. ERDC-SAND2 Model Calculations of Acreages for the MDWD Project Area under

Historical Sea Level Rise Rates

Historic RSLR Gross Acres of Marsh

Project Life Years 0 10 20 30 40 50

No Action Alternative (FWOP) 38,700 36,000 33,300 30,500 27,800 25,000

5,000 cfs Diversion Alternative 38,700 38,300 37,800 37,000 36,600 35,600

10,000 cfs Diversion Alternative 38,700 39,300 39,900 39,900 40,700 40,400

15,000 cfs Diversion Alternative 38,700 40,300 41,900 42,700 44,600 45,000

35,000 cfs Diversion Alternative 38,700 43,800 48,800 52,200 57,300 59,900

*** The total project area for the Medium Diversion at White Ditch is 98,000 acres

0

10000

20000

30000

40000

50000

60000

1 5 9 13 17 21 25 29 33 37 41 45 49

Wetland Acres

Period of Analysis

Comparison of Relative

Sea Level Rise Effects

Future Without Project -

Medium Sea Level Rise

Scenario: Wetland

Acres

Alternative 3: 15,000 cfs

Diversion with Moderate

Sea Level Rise

Scenario

Tentatively Selected

Plan: 35,000 cfs

Diversion with Moderate

Sea Level Rise

Scenario Future Without Project -

High Sea Level Rise

Scenario: Wetland

Acres

Alternative 3: 15,000 cfs

Diversion with High Sea

Level Rise Scenario

866
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Table 11. ERDC-SAND2 Model Calculations of Acreages for the MDWD Project Area under the

Intermediate and High Sea Level Rise Rates

Intermediate RSLR Gross Acres of Marsh

Project Life Years 0 10 20 30 40 50

No Action Alternative (FWOP) 38,700 34,900 30,900 26,500 21,800 16,900

35,000 cfs Diversion Alternative 38,700 42,800 46,600 48,500 51,800 52,400

High RSLR Gross Acres of Marsh

Project Life Years 0 10 20 30 40 50

No Action Alternative (FWOP) 38,700 31,500 23,700 14,000 2,900 0

35,000 cfs Diversion Alternative 38,700 39,500 39,600 36,300 33,800 27,600

*** The total project area for the Medium Diversion at White Ditch is 98,000 acres

4.5.4 Breton Sound Benefits

During the initial ERDC SAND evaluation of alternatives in Step 2, it was determined that

Alternative 4 has the capability to create marsh in the larger Breton Sound basin through nutrient

transfer. The modification of the Caernarvon Diversion is currently being evaluated in an effort

to address the design deficiency in capturing sediment. It may be possible, with further analysis,

to claim benefits to the Caernarvon project area as a result of implementing Alternative 4. This

may lead to cost savings for the Caernarvon project.

4.5.5 Adaptive Management

Alternative 4 provides the most robust capability for adapting to future risk and uncertainty. As

discussed above, Alternative 4 provides the most flexible management of operations to respond

to sea level rise. The difference between alternatives 3 and 4 is the outfall canals, ridges and

flow constrictions that are responsible for distributing flows at 15,000 and 35,000 cfs

respectively. Just as sea level rise represents uncertainty at one end of the spectrum, it is also

possible that the sea level rise will not be any more pronounced than historic levels. Also, as the

science of operating large diversion structures is refined throughout the period of analysis, it is

possible maximize environmental outputs with smaller diversions. Finally, it is expected that as

the project is actually operated and benefits are achieved, it will be of value for the federal, state

and local partnership to revisit the goals and objectives associated with the project area. If the

project is proving to be very successful at creating marsh it may no longer necessary to maintain

a 35,000 cfs diversion capability. To achieve this, O&M could be reduced resulting in outfall

canals, ridges and flow constrictions necessary to support a decreased diversion flow.

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Feasibility Study / SEIS

4.5.6 Acceptability, Completeness, Effectiveness, and Efficiency.

Alternative 4 meets the four evaluation criteria of the Economic and Environmental Principles

and Guidelines for Water and Related Land Resources Implementation Studies. Special

consideration is also given to these criteria within the larger context of the LCA Report (2004).

The four criteria are acceptability, completeness, effectiveness, and efficiency.

Acceptability

The plan is acceptable to Federal, state, tribal, local entities, and the public. It is

compatible with existing laws, regulations, and policies.

Completeness

The plan is complete. Realization of the plan does not depend on implementation of

actions outside the plan.

Effectiveness

The plan is effective. It addresses all the project objectives. It improves marsh habitat by

restoring deltaic process related to freshwater, nutrient and sediments. It does this by

introducing the quantities of freshwater, nutrients and sediments required (objectives) to

achieve no net loss of marsh during the period of analysis.

Efficiency

The plan is efficient. It is a cost-effective solution to the stated problems and objectives.

No other plan produces the same level of output more cost effectively. The plan is cost

effective and provides the greatest increase in benefits for the least increase in costs.

4.5.7 Recommendation of the Tentatively Selected Plan.

The interagency team recommends Alternative Plan 4 as the tentatively selected plan. This

alternative best meets the study objectives. It would result in restoration of deltaic processes

within the project area. In cooperation with the USFWS, NOAA, and the State of Louisiana the

Corps has planned and would design a project that serves the needs of the nation.

868
Final Integrated 1 September 2010

Feasibility Study / SEIS

ANNEX 1

Incidental Recreation Benefits

Introduction and Methodology

This report summarizes the potential incidental recreational benefits of the White Ditch Diversion

project, which is the development of a freshwater diversion from the Mississippi River into

marshland. The White Ditch Study Area is between the River aux Chenes and the Mississippi River

in Plaquemines Parish, Louisiana.

The methodology for estimating the potential incidental recreational benefits of the White Ditch

diversion is described by the USACE in publication number ER 1105-2-100, Planning - Planning

Guidance Notebook. ER 1105-2-100 authorizes the use of three separate procedures to estimate

recreation benefits. These are the travel cost method, the contingent valuation method, and the unit

day value method. The first two require a variety of data that are not readily available for the White

Ditch Project; therefore, the unit day value (UDV) method has been utilized. A model using the

UDV method was developed to estimate the value of recreational benefits in the Study Area for the

with- and without-project condition.

Annually, USACE publishes unit day values for both specialized recreation and general recreation.

For this project, the general recreation unit day values for general recreation published in Economic

Guidance Memorandum Number 10-03 (EGM 10-03) are used. The term “general recreation”

refers to an area that provides access to a variety of recreational activities, is widely used, and

provides supportive facilities, such as marinas.

Estimating Recreational Use Based Upon State of Louisiana Data

The Louisiana Statewide Comprehensive Outdoor Recreation Plan (SCORP) is published every five

years by the Office of State Parks within the Louisiana Department of Culture, Recreation and

Tourism. The SCORP is based upon in field and telephone surveys and is used to prioritize the

funding of recreation facilities within the state and is prepared to comply with National Park Service

guidelines. The 2003-2008 SCORP contains more detailed information, and more regional

information than the 2009-2013 SCORP, so both were consulted for this analysis.

The 2003-2008 SCORP explains how facility use standards were developed. The 2003-2008

SCORP facility use standard is based upon a turnover of 20 boats per boat ramp daily, with three

persons per boat. Hunting facility use is based upon a turnover of one hunter for every 25 acres per

day. The 2009-2013 SCORP states that fishing and hunting are both declining recreational

activities, with fishing declining 20% since the last SCORP.

The percentage of the population participating in saltwater fishing by boat based upon either SCORP

differs significantly from that indicated by licensing, which is managed by the Louisiana Department

of Wildlife and Fisheries (LADWF). The LADWF requires a saltwater endorsement to a fishing

license when fishing south of Interstate 10. For this analysis, the midpoint between the two figures

869
Appendix K: Annex 1 Volume VI – Medium Diversion at White Ditch

Final Integrated 2 September 2010

Feasibility Study / SEIS

(SCORP estimate and LADWF licensed population) is used to estimate the annual use of the study

area for recreational fishing.

For each parish, the number of activity days for fishing in a boat was estimated based upon parish

population in the latest Census estimate, the percentage of the population that participate in fishing

from a boat provided in the SCORP, and the number of people in the parish with a fishing license

and saltwater endorsement provided by LADWF. This number was multiplied by the average

number of activity days for fishing in a boat per person in the region, which is provided in the

SCORP, to estimate annual activity days by parish residents. The proportion of activity days for

fishing from a boat was allocated to the study area for each parish. This figure was allocated 60% to

weekends and 40% to weekdays. The result is that the number of weekday visitors annually in this

area is estimated at 54,101; the number of weekend visitors annually is estimated at 36,063. The

weekend visitation rate was compared with the study area capacity. The capacity of this study area is

driven primarily by the availability of boat launches and parking for boat trailers. After reviewing

the capacity of the two baot launches in the study area and the water access from outside the study

area, a judgement was made that capacity constraints did not impact weekend visitation. Thus, the

total number of visitors using this area for a day or the number of unit days is 90,164 annually.

A portion of the activity days for each parish were also allocated to the neighboring area to the

northeast. This is the recreational area closest to the White Ditch Study Area and the area most

likely to be used as an alternative, such as during the pulse period. The allocation of activity days to

the two areas listed, Study Area and Adjacent Area, are less than 100%, because parish residents

will spend some activity days in totally different regions. The White Ditch Study Area is in

Plaquemines Parish, where the majority of the population lives on the west bank of the Mississippi

River. A large portion of this population is unlikely to travel across the Mississippi River to the

White Ditch Study Area or the adjacent area.

During the pulse period a portion of the activity days that would have been spent in the White

Ditch Study Area might be spent in the adjacent area to the northeast, for the alternatives of

10,000 cfs (Alternative 2) or greater. The assumption is made that 10% of the activity days will be

shifted from the Study Area to the adjacent area at Year 5 for Alternatives 2 and 3 and 20% for

Alternative 4. At Year 10 the assumption is made that Alternatives 2 and 3 would have benefitted

the study area enough to increase annual activity days to the original amount, despite the

dislocation during the pulse period. Alternative 4 has a high diversion rate of 35,000 cfs during

the pulse period, and this rate would significantly reduce visitation through the entire planning

period. In comparison to the Caernarvon and Davis Pond Diversion Projects, the flow with

Alternative 4 would be much higher, and, according to focus group members, recreational

fishing would be greatly impacted for an extended period during and after the pulse period.

These shifts in user days, between the study area and the adjacent area are shown in the two

tables below.

870
Recreation Resource Year 5

July 1, 2017 Without Project Alternative 1 Alternative 2 Alternative 3 Alternative 4

White Ditch Study Area

Unit Day Value (2010 value) $8.38 $8.73 $8.90 $9.08 $9.30

Number of Unit Days 90,164 90,164 81,148 81,148 72,131

Total Annual Monetary Value $755,213 $786,951 $722,538 $736,820 $670,820Total Benefit / Loss with Project n/a $31,738 -$32,675 -$18,393 -$84,393

Outside of Study Area

Unit Day Value (2010 value) $8.38 $8.38 $8.38 $8.38 $8.38

Number of Unit Days 167,106 167,106 176,122 176,122 185,138

Total Annual Monetary Value $1,399,676 $1,399,676 $1,475,197 $1,475,197 $1,550,718Total Benefit / Loss with Project n/a $0 $75,521 $75,521 $151,043

Net Monetary Benefit / Loss n/a $31,738 $42,846 $57,128 $66,649

Total Number of Unit Days - Both Areas 257,269 257,269 257,269 257,269 257,269

871
Recreation Resource Year 10

July 1, 2022 Without Project Alternative 1 Alternative 2 Alternative 3 Alternative 4

White Ditch Study Area

Unit Day Value (2010 value) $8.38 $8.82 $8.99 $9.12 $9.34

Number of Unit Days 90,164 90,164 90,164 90,164 81,148

Total Annual Monetary Value $755,213 $794,885 $810,754 $822,656 $758,243Total Benefit / Loss with Project n/a $39,672 $55,541 $67,443 $3,030

Outside of Study Area

Unit Day Value (2010 value) $8.38 $8.38 $8.38 $8.38 $8.38Number of Unit Days 167,106 167,106 167,106 167,106 176,122

Total Annual Monetary Value $1,399,676 $1,399,676 $1,399,676 $1,399,676 $1,475,197Total Benefit / Loss with Project n/a $0 $0 $0 $75,521

Net Monetary Benefit / Loss n/a $39,672 $55,541 $67,443 $78,551

Total Number of Unit Days - Both Areas 257,269 257,269 257,269 257,269 257,269

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There are three general activities in the study area. One activity, recreational fishing, is of

high value. Recreational fishing is almost exclusively from boats, as there are no piers and

bank fishing is difficult. The only other recreational activities are duck hunting, which has a

short, 60 day season, and wildlife watching. The focus group attendees stated that most duck

hunting was outside the White Ditch Study Area, in the Mississippi River Gulf Outlet area.

The model was used to estimate the number of unit value days for duck hunting and wildlife

watching. Based upon the estimates, as shown in the table below, the number of user days for

these activities was approximately 6% of the number for recreational fishing. Therefore

separate unit day values were not estimated for these activities and recreational benefits were

not included for these activities.

873
White Ditch Study Area - Potential Visiting Population

Parish of Residence

Potential Recreational Users Plaquemines

St.

Bernard Orleans Jefferson Total

Potential Visitors to Study Area Annually - Fishing 15,237 9,633 14,418 50,876 90,164Potential Visitors to Adjacent Area Annually - Fishing 7,618 28,899 28,837 101,752 167,106Potential Visitors to Study Area Annually - Duck Hunting 33 28 9 94 164

Potential Visitors to Adjacent Area Annually - Duck Hunting 66 56 17 188 327

Potential Visitors to Study Area Annually - Nature Study 1,155 1,024 1,693 2,368 6,241Potential Visitors to Adjacent Area Annually - Nature Study 578 1,024 8,467 11,842 21,911Potential Visitors to Study Area Annually - Total 16,425 10,685 16,121 53,338 96,569Potential Visitors to Adjacent Area Annually - Total 8,262 29,979 37,321 113,781 189,343

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The time in transit for the recreational fishers using the study area would change with the

alternatives, based upon the species sought. During the pulse, saltwater species are expected

to migrate away from the diversion towards open water. The drive time to boat launches

would remain the same, but the time in transit by boat to fishing spots would increase for

those seeking saltwater species. Within the White Ditch Study Area the additional transit time

would not be significant. An additional 10 minutes of transit time by boat each way is not

significant compared with the total preparation and transit time needed to spend the day

fishing. Therefore the unit day value is not changed based upon transit time or “steaming

time.” However, some fishers will go to another area, outside the study area, rather than fish

in more open water, which has more choppy conditions

Estimate of Unit Day Value

The study area is assumed to be stable in the without-project condition, meaning the unit day values

for recreation remain constant.. The net changes in unit day values are determined by comparing the

future condition with the current condition. The estimates of annual use are combined with unit day

values to estimate annual recreation benefits. Unit day values were estimated using the most recent

values available in EGM 10-03.

The Unit Day Value method involves assigning points in each of five categories or criteria.

The five criteria are:

• Recreation Experience, the number of high quality recreational activities possible in the area;

• Availability of Opportunity, the availability of similar opportunities nearby;

• Carrying Capacity, the degree to which an area provides services to support recreation;

• Accessibility, the degree to which the area is readily accessible; and

• Environmental Quality, the aesthetic qualities of the area including water and vegetation, air and

water quality, scenery, and climate.

Points were assigned for each of these five criteria. The determination of points for each criterion

is described below. Two of the five criteria are impacted by the project.

Recreation Experience: A maximum of 30 points may be assigned for this criterion. Point values

to be assigned are described in the table below.

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For this analysis, 16 points are assigned because there are three activities; wildlife watching, fishing

and hunting, and because fishing in this area is, according to Focus Group participants, some of the

best in the country. None of the alternatives affect the points assigned for this criterion.

Availability of Opportunity and Likelihood of Fishing Success: A maximum of 18 points may be

assigned for this criterion. Point values to be assigned are described in the table below. Availability

of Opportunity is equated with likelihood of success at fishing and hunting, as stated in Table 2 of

EGM 10-03. During the annual pulse period and for a short period afterwards, likelihood of fishing

success will diminish. During the other months, the likelihood of fishing success would not be

impacted. The diversion is intended to improve the marsh and wildlife, so the long term impact on

recreation should be beneficial. When the beneficial impacts to wildlife become apparent after ten

years the likelihood of fishing and hunting success will increase.

For the White Ditch Study Area, the net increase in average annual habitat units and marsh acres are

considered when estimating the improved likelihood of success at fishing and hunting. Other factors

could be considered dependent upon data availability. The model does not use a direct correlation

between these factors and the likelihood of fishing success but is dependent upon a subjective

interpretation of the data.

Thus, 10 points are assigned for the without-project condition and additional points are assigned for

each of the alternative’s subsequent years based upon the environmental outputs of the project. The

Availability of Opportunity

Description Several similar

opportunities

within one

hour and a few

within 30 min

travel time

Several

similar

opportunities

within one

hour but

none within

30 min travel

time

One or

two

within one

hour

travel

time but

none

within 45

min

No similar

opportunities

within one

hour travel

time

No similar

opportunities

within two

hour travel

time

Range of

Points

0–3 4–6 7–10 11–14 15–18

Recreation Experience

Description Two general

activities

available

Several

general

activities

available

Several

general

activities

available

with one

high quality

Several

general

activities

available,

more than

one high

quality

Numerous

high quality

activities

available

Range of Points 0–4 5–10 11–16 17–23 24–30

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Feasibility Study / SEIS

outputs of the ecosystem restoration, Average Annual Habitat Units (AAHUs) and marsh acres, are

used in assigning points for this criteria. Increasing AAHUs and marsh acres indicate increased

likelihood of fishing success and increased esthetics. The correlation of these outputs to

improvements in recreational fishing has been determined through previous research but the direct

conversion of AAHUs and marsh acres to points is subjective. The model is consistent, in that more

of these outputs result in more points. Within coastal Louisiana, different projects have different

outputs, and sometimes these projects are adjacent to each other. For that reason the unit day values

for the MRGO Ecosystem Restoration project are considered when determining the point assignment

for the White Ditch Project.

The points assigned for Availability of Opportunity/Likelihood of Fishing Success are shown in the

table below. Based upon increases in AAHUs and input from the focus group, each alternative is

expected to increase the likelihood of fishing success significantly. Alternative 4 results in the

highest number of points, 16 out of 18, compared to the other alternatives.

877
White Ditch Study Area General Recreation Points - Year 5

Criteria Without Project Alternative 1 Alternative 2 Alternative 3 Alternative 4

Recreation Experience (Number of Activities) 16 16 16 16 16Availability of Opportunity * 10 11 12 13 16Carrying Capacity 5 5 5 5 5

Accessibility 10 10 10 10 10

Environmental (Esthetic Quality) * 11 14 15 16 18

Total Points 52 56 58 60 65

Unit Day Value $8.38 $8.73 $8.90 $9.08 $9.30

Variable - Availability of OpportunityLikelihood of Fishing Success (Net Change from Base) 0 1 2 3 6Additional (Net Change) Marsh AAHUs 0 < 5457 < 6095 < 7921 < 13575

Marsh Creation (Acres) 0 < 55 < 70 < 91 < 163

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Carrying Capacity: A maximum of 14 points may be assigned for this criterion. Point values to be

assigned are described in the following table:

Carrying Capacity

Description Minimum

facility

development

for public

health and

safety

Basic

facilities to

conduct

activity

Adequate

facilities to

conduct

activity

Optimum

facilities to

conduct

activity

Ultimate

facilities to

conduct

activity

Range of Points 0 - 2 3 - 5 6 - 8 9 - 11 12 - 14

For this analysis, 5 points are assigned because facilities to support recreation in this area are

currently adequate. However, should the proposed White Ditch project and resulting changes in

salinity levels reduce the amount of fishers utilizing existing marinas and causing them to go out of

business, there may be negative impacts to recreational fishing because there will be fewer services

available in the area. Since these closures are considered unlikely, the assumption is made that the

marinas will remain in business and recreational users will be able to obtain the services they need.

Accessibility: A maximum of 18 points may be assigned for this criterion. Point values to be

assigned are described in the following table:

Accessibility

Description Limited Access

by any means to

site

Fair access

to site;

limited

access

within site

Fair access

to site; fair

access

within site

Good

access to

site; fair

access

within site

Good

access to

site; good

access

within site

Range of Points 0 - 3 4 - 6 7 - 10 11 - 14 15 - 18

For this analysis, 10 points are assigned because the study area has one highway providing access to

the two boat launches within the site. None of the alternatives will affect this criterion.

Environmental: A maximum of 20 points may be assigned for this criterion. Point values to be

assigned are described in the following table:

Environmental

Description Low aesthetic

factors

Average

aesthetic

factors

Above

average

esthetic

factors

High

aesthetic

factors

Outstanding

aesthetic

factors

Range of Points 0–2 3–6 7–10 11–15 16–20

For this analysis, 11 points are assigned because while the area is considered to be very beautiful, the

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proposed project will affect some aesthetic factors during the pulse period and for several weeks

afterward. In particular, increased turbidity may affect water quality and decreased salinity will kill

some existing vegetation during the pulse period. However, because vegetation that can tolerate

changing salinity levels will eventually be established in the area, the aesthetic quality of the area

will recover. Thus over time, the number of points that can be assigned for this criterion will

increase. The table below shows that increase at Year 10 of the project.

880
Study Area

General Recreation Points - Year 10

Criteria Without Project Alternative 1 Alternative 2 Alternative 3 Alternative 4

Recreation Experience (Number of Activities) 16 16 16 16 16Availability of Opportunity * 10 12 13 14 17

Carrying Capacity 5 5 5 5 5

Accessibility 10 10 10 10 10

Environmental (Esthetic Quality) * 11 14 15 16 18

Total Points 52 57 59 61 66

Unit Day Value $8.38 $8.80 $8.99 $9.12 $9.34

Variable - ( Environmental - Esthetic Quality )Esthetic Quality (Net Change from Base) 0 3 4 5 7

Additional (Net Change) Marsh AAHUs 0 < 5457 < 6095 < 7921 < 13575

Marsh Creation (Acres) 0 < 55 < 70 < 91 < 163

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Recreational Benefits

EGM 10-03 provides a table showing how to relate points assigned using the five criteria to dollar

values. Since this project is evaluated to have a total of 52 points under the without-project

condition, using linear interpolation and the values provided by EGM 10-03 for either 50 or 60

points, we assign a dollar value of $8.38 as the general recreation unit day value. Unit day value

increases through year 50 for each alternative, based upon the evaluation points criteria discussed

above to $8.90 for Alternative 1, $9.08 for Alternative 2, $9.17 for Alternative 3 and $9.34 for

Alternative 4 (TSP).

The annualized benefits are based upon changes in both the number of unit days and the unit day

value, occurring over a fifty period. Both of these figures were input into the model at the time of

project completion, as well as five years, ten years, twenty years, and fifty years after project

completion. The benefits for every year during the fifty year planning period were based on the

outputs of the model for these years, with equal incremental changes between these years. The net

present value (NPV) of the annual benefits is calculated and the NPV is annualized.

Given that the area has 90,164 unit days per year and that each unit day is valued at $8.38, the total

annual monetary value of the recreational resource that would be affected by the White Ditch project

is $755,213. Given that the likelihood at success with fishing will increase and that environmental

factors will improve over time if the proposed project is implemented, the total annual monetary

value of the recreational resource will increase in the future compared to the annual monetary value

of the recreational resource should the proposed project not be implemented. A combination of an

increase in unit day value and user-days for the with-project condition results in an increase in net

benefits for each alternative. A combination of an increase in unit day value and total user-days for

Alternatives 1-3 results in increased recreational benefits. Alternatives 1 through 3 are expected to

increase user days by 9,000 in the study area by year 50, whereas annual visitation will not increase

for Alternative 4 because of users shifting out of the study area during the pulse period. This annual

decrease results from adverse conditions during the pulse period and for several weeks after. The

number of unit value days and the value of those days at Year 50 are shown in the next table

The following table shows the net present value and total annualized benefits for each alternative,

both inside the study are and outside the study area. There is a net positive benefit outside the study

area from the displaced users during the pulse period.

882
Recreation Resource Year 50

July 1, 2062 Without Project Alternative 1 Alternative 2 Alternative 3 Alternative 4

White Ditch Study Area

Unit Day Value (2010 value) $8.38 $8.90 $9.08 $9.17 $9.34

Number of Unit Days 90,164 99,180 99,180 99,180 90,164

Total Annual Monetary Value $755,213 $883,102 $900,557 $909,285 $842,492Total Benefit / Loss with Project n/a $127,889 $145,344 $154,072 $87,279

Outside of Study Area

Unit Day Value (2010 value) $8.38 $8.38 $8.38 $8.38 $8.38Number of Unit Days 167,106 167,106 167,106 167,106 167,106

Total Annual Monetary Value $1,399,676 $1,399,676 $1,399,676 $1,399,676 $1,399,676Total Benefit / Loss with Project n/a $0 $0 $0 $0

Net Monetary Benefit / Loss n/a $127,889 $145,344 $154,072 $87,279

Total Number of Unit Days - Both Areas 257,269 266,286 266,286 266,286 257,269

883
Total Recreation Resource Annualized Benefits

Without Project Alternative 1 Alternative 2 Alternative 3 Alternative 4

White Ditch Study Area

Total Net Present Value (NPV) all 50 years 15,345,000 16,815,000 16,795,000 16,983,000 15,831,000Total Annualized Rec Benefits - 50 years 728,873 798,697 797,747 806,677 751,958

Net Present Value Increase / Decrease 1,470,000 1,450,000 1,638,000 486,000

Annualized Benefits Increase / Decrease 69,824 68,874 77,803 23,085

Outside of Study Area

Total Net Present Value (NPV) all 50 years 28,344,000 28,344,000 28,637,000 28,637,000 29,262,000Total Annualized Rec Benefits - 50 years 1,346,314 1,346,314 1,360,231 1,360,231 1,389,918Net Present Value Increase / Decrease 0 293,000 293,000 918,000Annualized Benefits Increase / Decrease 0 13,917 13,917 43,604

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Final Integrated 17 September 2010

Feasibility Study / SEIS

To better understand the economic impact of the proposed project on recreation, the analysis

considered effects over a 50-year period. The analysis uses the Federal discount rate for 2009 of

0.04625. The following table summarizes the potential net present value of recreational resources for

each alternative.

Net Increase in Recreation Benefits

Without

Project

Alternative 1 Alternative 2 Alternative 3 Alternative 4

Net Present

Value of

Benefits over

50 years

$0 1,470,000 1,743,000 1,931,000 1,404,000

Annualized

Benefits

$0 69,824 82,791 91,721 66,689

Alternative 3 has the highest benefits. Unit day values increase more for Alternative 3 than for

Alternatives 1 and 2 and it has a higher number of unit days than Alternative 4. Alternative 4 has the

highest unit day value for each year modeled because it has the highest level of environmental

outputs . However, the high water flow for Alternative 4 is expected to cause the greatest reduction

in visitation. To summarize, Alternative 3 has the highest benefits based upon the combination of

both unit day values and annual visitation.

References

2006 National Survey of Fishing, Hunting, and Wildlife Related Recreation, U.S. Fish and Wildlife

Service, Louisiana, issued March 2008.

Louisiana Statewide Comprehensive Outdoor Recreation Plan 2003-2008, Louisiana Department of

Recreation and Tourism, December 2004.

Louisiana Statewide Comprehensive Outdoor Recreation Plan 2009-2013, Louisiana Department of

Recreation and Tourism, July 2009.

Net Economic Values of Wildlife Related Recreation in 2006, U.S. Fish and Wildlife Service,

Report 2006-05, July 2009.

Army Corps of Engineers, Economic Guidance Memorandum 10-03: Unit Day Values for

Recreation, Fiscal Year 2010, November 2009.

Army Corps of Engineers, ER 1105-2-100, Chapter 3: Corps Civil Works Missions, April 2000.

885
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Final Integrated 18 September 2010

Feasibility Study / SEIS

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APPENDIX L:

Engineering Investigations

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Volume VI

APPENDIX L:

Engineering

5 Medium Diversion at White Ditch Final Feasibility Report

Appendix L1 – Engineering Investigations and Cost Estimates

Table of Contents

10 L1. GENERAL ............................................................................................................................. 3

L2. HYDRAULICS AND HYDROLOGY................................................................................. 3

L2.1 CLIMATOLOGY ................................................................................................................................................3

L2.2 SELECTION OF A HYDRODYNAMIC MODELING PROGRAM ............................................................................4

L2.3 DATA COLLECTION FOR MODELING PURPOSES ............................................................................................5

15 L2.3.1 Bathymetry 6

L2.3.2 Tidal Stages 6

L2.3.3 Salinity 8

L2.3.4 Meteorological Data 8

L2.3.5 Caernarvon Flows 9

20 L2.3.6 URS Field Investigation 11

L2.4 HYDRODYNAMIC MODEL DOMAIN AND GRID GENERATION.................................................................14

L2.5 BOUNDARY CONDITIONS .........................................................................................................................26

L2.6 HYDRODYNAMIC MODEL CALIBRATION ................................................................................................26

L2.7 HYDRODYNAMIC ALTERNATIVES ANALYSIS..........................................................................................31

25 L2.7.1 Initial Screening Analysis 34

L2.8 ECOHYDRAULIC MODELING ...................................................................................................................45

L3. SURVEYING, MAPPING, AND GEOSPATIAL DATA REQUIREMENTS.............. 48

L3.1 GEOSPATIAL DATA ........................................................................................................................................48

L3.2 AERIAL PHOTOGRAPHY AND LIDAR ...........................................................................................................48

30 L3.2.1 2008 DOQQ Aerial Photography 48

L3.2.2 1992 Landsat Thermatic Satellite Image of Louisiana, UMT 15 NAD27 49

L3.2.3 2007 Mississippi River LIDAR 49

L3.3 GROUND TOPOGRAPHIC SURVEYS................................................................................................................50

L4. GEOLOGY .......................................................................................................................... 50

35 L5. GEOTECHNICAL INVESTIGATIONS AND DESIGN................................................ 54

L5.1 GENERAL..................................................................................................................................................54

L5.2 GEOTECHNICAL DESIGN FOR DIVERSION FACILITY..............................................................................54

L5.2.1 Stability Analyses 54

L5.2.2 Construction Excavation 58

40 L5.2.3 Pile Foundations 58

L5.2.4 Lateral Earth Pressures 61

L5.2.5 Hydrostatic Uplift 61

L5.2.6 Backfill 61

L5.3 GEOTECHNICAL DESIGN FOR TRANSMISSION SYSTEM..........................................................................62

45 L5.4 LABORATORY TESTING PROGRAM AND EVALUATIONS.........................................................................63

L6. ENVIRONMENTAL ENGINEERING........................................................................... 280

L7. CIVIL DESIGN CRITERIA............................................................................................ 280

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L7.1 SITE RECOMMENDATIONS.....................................................................................................................280

L7.2 CIVIL SITE DESIGN FOR DIVERSION FACILITY ....................................................................................281

50 L7.2.1 General 281

L7.2.2 Alternatives Array 282

L7.2.3 Description of Civil Site alternatives 282

C8. STRUCTURAL DESIGN CRITERIA............................................................................ 294

L8.1 FOUNDATION RECOMMENDATIONS ...............................................................................................294

55 L8.1.1 General 294

L8.1.2 Description of Feature Foundations 294

L8.2 STRUCTURAL DESIGN FOR DIVERSION FACILITY......................................................................295

L8.2.1 General 295

L8.2.2 Description of Structural Features 296

60 L9. ELECTRICAL AND MECHANICAL REQUIREMENTS.......................................... 301

L9.1 ELECTRICAL SOURCES AND SUPPLY REQUIREMENTS.............................................................301

L9.1.1 GENERAL ..................................................................................................................................................301

L9.1.2 Electrical Requirements Per Site 301

L9.2 SOLAR POWER SUPPLY SYSTEMS.....................................................................................................302

65 L9.2.1 General 302

L9.3 ELECTRICAL AND MECHANICAL DESIGN FOR DIVERSION FACILITY.................................302

L9.3.1 General 303

L9.3.2 Electrical/Mechanical Requirements Per Site 303

L10. CONSTRUCTION PROCEDURES.............................................................................. 304

70 L11. OPERATIONS AND MAINTENANCE ....................................................................... 304

L11.1 OPERATIONS......................................................................................................................................304

L11.2 MAINTENANCE.......................................................................................................................................307

L12. COST ESTIMATES........................................................................................................ 307

L12.1 BASIS OF COST ESTIMATE.....................................................................................................................307

75 L12.2 DETAILED ESTIMATE.....................................................................................................................308

L12.3 CONTINGENCIES ....................................................................................................................................310

L12.4 RISK ANALYSIS ......................................................................................................................................310

ANNEX 1: Quantifying Benefits of Freshwater Flow Diversions to Coastal Marshes

80 ANNEX 2: ERDC-SAND2 Model Verification

ANNEX 3: MCASES Cost Analysis

ANNEX 4: Hydrodynamic Modeling Analysis by URS Corporation

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85 L1. General

The White Ditch project area is located in the Breton Sound estuary and covers the area

extending north and south from just south of Belair, Louisiana to the coastline of Louisiana and

extending east and west from the Mississippi River to the Oak River. This area extends about 50

90 km in the NW-SE directions and about 30 km in the SW-NE direction. Subsidence, erosion,

channelization, saltwater intrusion, storm damage and the absence of fresh water, sediments and

nutrients from the Mississippi River have all caused significant adverse impacts to the White

Ditch project area resulting in extensive wetland loss and ecosystem degradation. There is an

existing siphon at the mouth of White Ditch that was built in 1963 and has not been in operation

95 since 1991, except for two brief episodes.

The absence of a supply of fresh water, sediment, and nutrients has caused the marsh to degrade.

This degradation coupled with the subsidence and sea level rise rate of approximately 1.04 cm

per year has led to an increase in saltwater intrusion. The additional influx of saltwater from the

100 Gulf of Mexico through the vast canal network in the project area has further damaged the marsh

vegetation. In August and September of 2005 Louisiana was hit by hurricanes Katrina and Rita.

These hurricanes brought high winds and high tidal surges and destroyed thousands of acres of

already weakened marsh. In September of 2008 hurricanes Ike and Gustav also hit the Gulf

coast. While they did not make direct landfall in the project area, the tidal surges from these

105 storms caused the loss of additional marsh acreage.

The White Ditch area is part of the Breton Sound estuary system. Breton Sound estuary is

located in southern Louisiana, between Breton Sound Bay and approximately the last 85 miles of

the Mississippi River before it discharges into the Gulf of Mexico. The estuary consists of about

110 430 square miles (1,100 km2) of fresh and brackish coastal wetlands that are made up of shallow

water ponds, lakes, bays, and a man-made canal system (Figure 1). The major rivers in the

estuary are the Oak River (also known as River aux Chenes) and Bayou Terra aux Boeufs. The

larger water bodies are Big Mar, Lake Leary, Spanish Lake, Grand Lake, and Little Lake.

115 The project is examining alternative designs for a fresh water diversion from the Mississippi

River to the White Ditch Project area. Different alternative locations, channel depths and widths

are considered for different peak diversion flow rates, ranging from 5,000 to 100,000 cfs.

L2. Hydraulics and Hydrology

120

L2.1 Climatology

The climate of the White Ditch study area is subtropical marine with long humid summers and

short moderate winters. The climate is strongly influenced by the water surface of many sounds,

125 bays, lakes and the Gulf of Mexico and seasonal changes in atmospheric circulation. During the

fall and winter, the study area experiences cold continental air masses which produce frontal

passages with temperature drops. During the spring and summer, the study area experiences

tropical air masses which produce a warm, moist airflow conducive to thunderstorm

development (USACE 2008a (MRGO LEIS)). The study area is also subject to periods of both

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130 drought and flood, and the climate rarely seems to truly exhibit “average” conditions (MsCIP

2008).

The study area is susceptible to tropical waves, tropical depressions, tropical storms and

hurricanes. These weather systems can cause considerable property and environmental damage

135 and loss of human life. Historical data from 1899 to 2007 indicate that 30 hurricanes and 41

tropical storms have made landfall along the Louisiana coastline (NOAA 2009). The largest

recent hurricanes were Katrina and Rita in 2005, which caused devastating damage in the study

area. Hurricane Gustav, while much smaller and less intense, caused additional damage in the

study area. Hurricane Ike, which made landfall in Galveston, Texas in 2008, caused flooding

140 and wind damage in coastal areas as it passed the Louisiana Coast.

The total amount of marsh lost as a result of Hurricanes Katrina and Rita was over one third of

the total predicted wetland losses predicted by the Coast 2050 Report (1999). Within the study

area, about 40,910 acres of wetlands were converted to open water (Barras 2006). This loss rate

145 exceeded the average background loss rate of about 2,160 acres per year for the period from

1956 to 2004 (Wicker 1980; Barras et al. 1994; Barras et al. 2003; Morton et al. 2005). New

water bodies formed and existing water bodies expanded north and west of Lake Lery (USGS

2006). These changes occurred largely as a result of Hurricanes Katrina and Rita. The combined

land-water changes caused by Hurricanes Katrina and Rita exceeded coastal land change from

150 previous recent hurricanes combined, such as Hurricanes Andrew (1992), Lili (2002), and

Tropical Storm Isidore (2002) (Barras 2006).

L2.2 Selection of a Hydrodynamic Modeling Program

155 A modeling program for a hydrologic study is primarily selected based on the following factors:

a. The configuration of water bodies, channels, and flow control structures in the study area;

b. The nature of water movement inside the system; and

c. The parameters to be studied (e.g., water level, velocity, sediment movement, and/or

salinity etc.).

160

The project area is comprised of areas of marsh and open water with bounding channels and

several intersecting interior channels. Since the project area is shallow, the vertical movement of

water is insignificant relative to that in the longitudinal and transverse directions and can be

ignored during hydrodynamic and salinity computations without loss of accuracy in the final

165 results. The marsh system is assumed to be well mixed vertically. Sediment transportation is an

important feature that the model must have; however, due to time constraints hydrodynamic

sediment modeling will not be conducted as a part of this study. The project delivery team wants

to ensure the opprotunity for this modeling to be done in the future to investigate likely

sedimentation patterns within the project area. Therefore, a modeling program that can simulate

170 2D, vertically averaged movement of water and salinity is the most appropriate for the study.

A number of hydraulic models meet the above criteria and were considered for use in simulating

the White Ditch diversion alternatives. The candidate models are listed below and organized

into finite element and finite volume categories. In general, the finite element models have

unstructured meshing capabilities that allow for the efficient detailed resolution of small features,

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175 However, they are difficult to implement in projects with large areas of wetting and drying, often

requiring excessive bathymetric and topographic smoothing to achieve a stable solution.

Finite Element Models include:

180 ADCIRC – Advanced Circulation Model for Oceanic, Coastal and Estuarine Waters:

unstructured mesh, no salinity, poor wetting and drying.

FESWMS – Finite Element Surface Water Modeling System: unstructured mesh, no salinity,

poor wetting and drying.

185

RMA2 – Resource Management Associates: unstructured mesh, salinity transport, poor

wetting and drying

Finite Volume Models include:

190 CMS– Coastal Modeling System: salinity transport, good wetting and drying, rectilinear

mesh

EFDC – Environmental Fluid Dynamics Code: salinity transport, good wetting and drying,

curvilinear mesh

195

FVCOM – Finite Volume Community Ocean Model: unstructured mesh, good wetting and

drying, commercial availability

POM– Princeton Ocean Model: salinity transport, good wetting and drying, curvilinear mesh

200

The finite difference models typically will not have any stability problems when considering

wetting and drying, but often do not have the benefits of unstructured meshes since they typically

use rectilinear or curvilinear structured meshes. The FVCOM model is unique in that it is a

205 finite volume model that uses an unstructured mesh and therefore can realize the mesh

generation benefits often associated with finite elements. However, the model is relatively new

and limited to research applications. Non-research applications are occurring but model

documentation and general industrial familiarity with the model are not mature. The remaining

three finite volume models (CMS, EFDC and POM) all have similar capabilities and are suitable

210 for the project.

OF those three, the CMS is supported by the USACE and therefore was selected for the project.

CMS-Flow is a process-based 2D depth-averaged hydrodynamic, sediment transport and

morphology model developed by the USACE for application in and around inlets and channels.

215 It is accessible via the Surfacewater Modeling System (SMS) graphical user interface.

L2.3 Data Collection for Modeling Purposes

There were a number of existing data sets available to support the configuration, calibration and

220 application of the hydrodynamic and salinity transport model. In addition to the existing data

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sets, a bathymetric survey and a field measurement program were conducted prior to the

modeling analysis in order to provide site-specific data. Each of these data sets is briefly

described below.

225 L2.3.1 Bathymetry

There was sparse data within the coverage area, and the resolution of any available data was

insufficient for model use. Digital Elevation Model (DEM) and contoured elevation coverages

were available at http://atlas.lsu.edu/rasterdown.htm for portions of the modeled area, however

230 the elevation values available in these datasets did not contain the precision necessary for use in

the model.

The USACE conducted a bathymetric survey of the White Ditch area to both support of the

modeling analysis and the alternative designs. The survey transects are shown in Figure C2.1.

235 These data provide information on the channel depths and widths, the lake depths, ridges

bounding the channels as well as the characteristics of the inter-tidal and land areas.

Figure L2.1: Surveys contract by the USACE to assist in Hydrodynamic modeling analysis of the

White Ditch project area.

240 L2.3.2 Tidal Stages

Real-time tide data were downloaded from http://waterdata.usgs.gov/nwis for three U.S.

Geological Survey (USGS) stations. Station locations include: Northeast Bay Gardene (Station

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ID: 7374527), Black Bay near Snake Island (Station ID: 7374526) and Cow Bayou at American

245 Bay (Station ID: 73745258). Tide data were also obtained from http://tidesonline.nos.noaa.gov/

for the National Atmospheric Oceanic and Atmospheric Administration (NOAA) Station Pilot

East (Station ID: 8761305). Station locations are shown in Figure L2.2.

A review of the tide gages revealed that there were no suitable gage locations in the proximity of

250 the White Ditch area. The closest gages were Cow Bayou at American Bay and Northeast Bay

Gardene. Data from the Bay Gardene station was chosen for model use since it provided the

most available data with the fewest data gaps.

Utilization of the Bay Gardene data was not without difficulty. A downward shift of 0.5 feet was

255 done on the gage by the USGS in January 2010. They note that there is a level of uncertainty

surrounding this gage considering its datum has been tied to a nearby telephone pole which has

been through multiple hurricanes and is continually experiencing the effects of subsidence and

erosion. In addition, although NOAA often publishes datum conversion between geodetic (i.e.

NAV 88) and tidal datum for many gages along the US coast, its website Benchmark Page and

260 does not contain the NAVD 88 and tidal datum conversion for the Bay Gardene station. This is

likely due to accuracy and or data issues. NOAA does provide the VDATUM software for

converting data to various datum along the US coastline and the coastal regions of the Great

Lakes. It also provides estimates of the accuracy in the conversions. The published VDATUM

accuracy information for the East Louisiana/Mississippi area is +/- 17.1 cm.

265

When the Bay Gardene data was averaged over a period multi-year period of time, it was

discovered that the average was approximately 1.0 feet above sea level (0.0 feet NAVD88).

Using standard modeling practices, all data was shifted downward by 1.0’ for the average to

coincide with approximate sea level. This 1.0 downward shift falls within the acceptable range

270 established by coupling the USGS’ 0.5 downward shift with the NOAA +/- 17.1 cm accuracy

range. Most importantly, this adjustment reflects locally observed conditions and results in an

accurately responding model.

It is important to note that the results of the model and its calibration are completely dependent

275 on the accuracy of the tidal data that is used as input. Although it was the best available, there is

a level of uncertainty surrounding the datum of the Bay Gardene gage which was used in the

White Ditch Hydrodynamic Model. The USGS plans to re-survey the gage with state-of-the-art

GPS in the near future, with possible publishing of the results in April 2010. It is recommended

that the issue of calibration be revisited when this more accurate survey data is complete. It is

280 also recommended that a sensitivity analysis be performed with different levels of tidal drivers

(i.e. 0.5 feet above and below the level the model is currently calibrated at) to examine changes

in salinity distribution. This sensitivity analysis should demonstrate that the tidal driver used in

the model was indeed accurate. These efforts should be conducted before or as part PED phase.

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Figure L2.2: Salinity and Tidal gages used in the modeling process

285

L2.3.3 Salinity

Salinity data are available from the USGS. Data was accessed from http://waterdata.usgs.gov.

Data originate from three Louisiana stations including: Northeast Bay Gardene (Station ID

290 7374527), Black Bay near Snake Island (Station ID 7374526), and Cow Bayou at American Bay

(Station ID 73745258). Station locations are shown in Figure L2.2. Another salinity data set was

available from Strategic Online Natural Resources Information System (SONRIS). This data set

included hourly or monthly salinity measurements and stations were located throughout the

Breton Sound with varying periods of record Figure L2.3. The average, max and minimum

295 salinity values at stations with sufficient data are shown in the table in Figure 10. The data

reflect the freshwater source of the Caernarvon Diversion.

L2.3.4 Meteorological Data

300 Wind data are available from various stations in the project area. The wind data were collected

by NOAA from 1999 through 2009 (http://www.ncdc.noaa.gov/oa/ncdc.html). Louisiana wind

station locations include: Grand Isle (Station Number 8762417), Pilot East (Station Number

8760922) and Shell Beach (Station Number 8761305). The location of these stations is shown in

Figure 6. Hourly data was available from the Pilot East station and was downloaded for the time

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305 period of 3/25/2004 through 7/23/2009. Acquired data is noncontiguous in content, containing a

number of dates with no recorded data.

Figure L2.3: Salinity gages used in the modeling process

Rainfall data were obtained from the NOAA Port Sulfer Station (Station 167471) and from a

310 Bell Chasse station. Station locations are shown in Figure L2.4.The data included a daily sum of

rainfall in inches for 1/1/2004 through 8/27/2009 for Port Sulfur and 9/28/2006 through

8/20/2009 for Belle Chasse.

There were no daily evaporation data available from stations near the project area. In order to

315 provide some information for evaporation rates, data in the literature was reviewed. A study

conducted by Cooke et. al. (2008) provided measured data at a variety of stations in Louisiana.

The nearest station was Houma for which summer evaporation rates were available. The data

indicate some daily fluctuations do occur, ranging between 2 and 8 mm/day, with an average rate

on the order of 5 mm/day.

320

L2.3.5 Caernarvon

On the northern edge of Breton Sound estuary is the Caernarvon freshwater diversion structure.

It is located on the east bank of a Mississippi River oxbow at river mile 81.5. The diversion

325 structure began operating in 1991 as a means for establishing optimal salinity conditions for

oyster production, and can also be used to prevent saltwater intrusion during storms or droughts.

The 23-meter-wide structure has the capacity to divert up to about 8,000cfs (226m3

/s) of

Mississippi River water into the Breton Sound estuary, and has been managed at many different

discharge rates since its commencement.

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330

Figure L2.4: NOAA rainfall and wind stations used in the modeling process

The Louisiana Department of Natural Resources manages the Caernarvon Freshwater Diversion

Project and provides daily flow data in cubic feet per second (cfs) from 1992 through 2009.

335 Average monthly flows from the diversion are shown in Figure L2.5.

Based on discussions with local land managers, it is believed that the flow from the diversion

followed two dominant paths from the diversion. The main one is to the south through the

Bayou Mandeville area. The second one is directed to the west, through the Delacroix Canal,

340 and ultimately merges with the Oaks River. It is believed that about 20 to 30 percent of the

diversion flows went through the western path until Hurricane Katrina impacted the area. After

Katrina, many of the smaller channels to the west were clogged with debris, and it is believed

that only 5 to 10 percent of the diversion flow now flows westward.

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345 Figure L2.5: Average monthly flows from the Caernarvon Diversion.

L2.3.6 URS Field Investigation

The White Ditch field investigation was conducted from July 20, 2009 through July 23, 2009 to

350 collect necessary calibration data for the CMS-Flow hydrodynamic model of the study area. The

field investigation was conducted by two crews of URS field staff operating from airboats hired

for the project. The field crews were accompanied by William Terry of the U.S. Army Corps of

Engineers (USACE) St. Louis District Office for most of the field investigation. A summary of

the two data sets explicitly used in the modeling analysis, the water elevations and the salinity

355 data, are summarized here.

The study area and sampling stations are shown in Figure L2.6. Measurements of flow velocity,

temperature, salinity and turbidity were collected periodically between July 21 and 23, 2009 at

the primary stations (N1, N2, N3, S1, S2, and S3). Water level measurements were collected at

360 stations N3 and S3 from July 20 to July 23, 2009 using temporary staff gauges and recording

pressure transducers that were installed at these locations. Less frequent flow velocity,

temperature and salinity measurements were collected at the secondary locations (Oak River

Channel, N4, N5, N6, S4, S5, S6, S7, S8, S9, S10, and S11). Water depth measurements were

collected at each of the primary and secondary locations, and at additional field locations (S12-

365 S33) shown on Figure L2.7.

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Figure L2.6: URS data collection stations for the modeling process.

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Figure L2.7: Additional URS field stations for the modeling process.

370 Staff gauges and recording pressure transducers were installed at locations S3 and N3 to measure

water level fluctuations within the study area. The transducers used were Micro-Diver

Dataloggers (Model DI601) manufactured by the Schlumberger Corporation. The data loggers

were initially programmed to collect pressure measurements every five minutes in feet of water.

The sample interval was changed to 30 seconds after approximately 24 hours.

375

Staff gauges constructed of 1-inch diameter PVC pipe was also installed at locations S3 and N3.

Periodic measurements of the water level at each staff gauge were recorded. When compared to

the tides at the Bay Gardene Station, it is evident that there is s significant loss of tidal amplitude

as the tides propagate into the White Ditch area.

380

Salinity data (as well as temperature and turbidity measurements) were collected at each primary

location and other select locations using a HydroLab Quanta system. The mean, maximum and

minimum salinity at each station was also recorded. The SONRIS salinity data are also shown in

Figure L2.3, and although the data represent different time periods, they show a general trends in

385 the salinity patterns. The trends show a basic low to higher salinity gradient from offshore to the

NW as well as a high to low gradient from the east bank of the Mississippi River to the NE. The

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general gradients, even those in the White Ditch area, point towards the Caernarvon Diversion,

indicating that it is a significant source of freshwater in the area.

Salinity measurements were also made at surface and bottom. The data indicates a very minor

390 difference between the two; less than 0.5 ppt.

L2.4 Hydrodynamic Model Domain and Grid Generation

The model domain is shown in Figure L2.8. The domain includes all of the white ditch area as

395 well as an extensive portion of Breton Sound. A primary reason for including the larger portion

of Breton Sound was the potential influence of the diversion peak flows on the east of the Oaks

River. Also, the channels providing flow pathways from the Caernarvon Diversion to the White

Ditch area required inclusion since the Caernarvon Diversion flows provided a significant

portion of the freshwater to the White Ditch area (the other being rainfall).

400

To provide bathymetric data for the model grid, a project-specific bathymetric and topographic

data set was developed. This data was used to set the bottom elevation of the cells in the model

grid. Initial experiments with the model indicated that the grid resolution in the White

405 Ditch area would need to be on the order of 10 to 30 meters. This level of resolution would

provide sufficient resolution of the channel features but allow for reasonable simulation times on

high-end workstations. Therefore, the bathymetric and topographic data should have a minimum

resolution of 10 meters in the White Ditch area.

410 The area bathymetry and topography were developed from existing bathymetric data, land/water

boundary data and results from the project field survey. It was determined early in the

bathymetric data development that existing bathymetric data were limited to areas above MSL

and sets did not provide sufficient resolution for direct use in the grid generation. Therefore the

following approach was used to develop the bathymetric and topographic data set:

415 • Acquire the most recent land/water boundary data

• Update the land/water boundary data for Post Katrina conditions

• Divide the land/water boundaries into small polygons representing channels, lakes, land

segments and other features

• Assign depths to each polygon

420 • Convert the polygons to a 10 meter grid and export

• Import the 10 meter grid into SMS and use to populate the CMS

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Figure L2.8: Grid/Model extents.

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Figure L2.9: Marsh loss attributed to Hurricanes Katrina and Rita

425

Several datasets of land and water polygons were obtained for use in developing the bathymetric

dataset; one from the Louisiana GIS Digital Map Compilation DVD (2007) and one from the

ESRI Streetmap dataset. The land/water polygon data from the LA GIS Digital Map Compilation

DVD was used to start the bathymetric data processing. This polygon data represents pre430 Katrina conditions and is shown in Figure L2.9 overlaying post-Katrina aerial images. It is clear

that there were some significant changes in the land mass in the White Ditch area, especially in

the NW region. These changes were confirmed in a USGS study, the results of which are shown

in Figure L2.10. Therefore In order to update the land/water polygons to reflect post-Katrina

conditions, polygons from the ESRI dataset were used in compliment and this set was further

435 modified. Additional digitizing was conducted so that the final set of polygons reflected the land

and water boundaries as depicted in the most current aerial photography available for the area.

Additional reviews of the polygon data set indicated that not all of the canals in the study area

were completely represented in the processing. Canals not represented were digitized and canal

water body connections that were inaccurate were modified. The final set of polygons is shown

440 in Figure L2.11a and L2.11b.

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Figure L2.10: USGS Water Area Change in Southeastern Louisiana

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Figure L2.11a: Land analysis polygons

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Figure L2.11b: Land analysis polygons

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445 Figure L2.12: Distributed survey data developed by URS Corp.

The next step was to assign depth values to each of the polygons in the data set. As pointed out

in Section 2, there was no comprehensive bathymetric data set available. In order to assign

depths, information from the project bathymetric survey and NOAA nautical chart data were

450 used. The first step was to set the land elevation. For this purpose, all of the survey data was

pooled and sorted to identify the distribution and range. The distribution of the data is shown in

Figure L2.12. There is a distinctive break in the distribution at elevation 0 ft (NAVD 88) that is

likely representative of MSL, where the channel and lake banks are steepest. Assuming that

most of the inter-tidal zones and land segments lie at or above 0 ft elevation, the data was filtered

455 to eliminate values below 0 feet, and then resorted. The results are also shown in Figure L2.12,

and indicate that the median land elevation is 1 foot NAVD 88. This value was adopted as the

land elevation and all land polygons were assigned a depth of -1 ft.

In order to assign depth values to the canals and lakes, the survey data transects were processed

460 and used to develop a suitable average depth for each cross-section. Each transect cross-section

was clipped so that the only the portion below MSL remained. Then the hydraulic radius of the

cross-section was calculated. Then the cross-section effective depth was calculated so that it

would yield the same hydraulic radius as the original cross-section. This value was then

assigned to the center point of the cross-section transect and used to assign depth values in the

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465 canal and lake polygons. The effective depths and their locations, as obtained by this procedure,

are shown in Figure L2.13. The effective depth data did not provide sufficient information to

assign depths to all canal and lake polygons. Therefore a generalized template for canal and lake

depths was developed and used to assign the depths to the remaining polygons. A review of

Figure L2.13 indicates that there is a general increase in the canal and lake depths from the NW

470 to the SE. A template, shown in Figure L2.14, was developed using this trend.

After completing the depth assignments to each polygon, the depth data were interpolated from

the polygons to a point grid. The point grid consisted of 10 m spacing in the White Ditch area

and expanded to 50 m spacing to the east of the Oaks River and to the SE. The 50 m resolution

475 was necessary to keep the file size manageable and still provide sufficient resolution of key

features. A view of the bathymetric data as reflected by the point grid is shown in Figure L2.15.

An enlarged portion of the point grid data is shown in Figure L2.16, where the points are color

coded by the assigned depths.

480 The point grid bathymetry dataset was imported into SMS, triangulated, and the depths were

interpolated on to the CMS grid. Based on trials in the focus area near White Ditch, a 20 meter

resolution was determined to be optimal for areas in the vicinity of the proposed diversion.

The grid was designed with 20 meter spacing in the White Ditch area with the cell spacing

485 expanding to the SE and SW. In these regions of grid expansion, the grid was allowed to

increase to a maximum grid cell size of 500 meters in order to keep the number of cells as low as

possible and help manage simulation run time while still providing detailed resolution in the

White Ditch study area. Certain cells are ‘inactive’ and represent areas protected by levees or

that are above 4 feet elevation. These cells are not used in the model simulations and are a by490 product of the inherent CMS rectangular grid structure. A QAQC process was performed in

order to ensure canal connections and other components necessary for accurate flow simulation,

and cell properties were adjusted manually where appropriate. The final grid contains 866,791

active cells in 992 Columns and 569 Rows. After some initial testing, a time step of 1.5 seconds

was found to provide numerically stable solutions, and the model simulations (including salinity

495 transport) were determined to take about two days (48 hours) in order to simulate a one month

period on an HP Workstation Z400 with an Intel 2.93 Ghz Xeon Quad processor and 8gb DD3

SDRam.

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Figure L2.13: Measured water depths within the White Ditch project area 500

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Figure L2.14: Water depth trend used for modeling purposes

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Figure L2.15: A view of the bathymetric data for the White Ditch project area, as reflected by the point grid

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Figure L2.16: An enlarged portion of the point grid data for the White Ditch hydrodynamic model

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505

L2.5 Boundary Conditions

The boundary conditions required for the White Ditch model simulations included:

• Offshore tide elevation

510 • Offshore salinity values

• Flow boundaries (flow rate and salinity)

• Rainfall and Evaporation

• Wind Forcing

515 As discussed in the Section L2.3, it was not possible to obtain a tidal calibration to measured

data in the White Ditch area without shifting the reported elevation of the tide data. The Bay

Gardene tide data is reported as NAVD 88 and the mean tide elevation for one or more year

period is approximately one foot above sea level; therefore, a shift of 1.0 feet down was made to

set the average at approximately sea level.

520

Local survey data in the White Ditch area indicates that the median land elevation (based on

numerous survey points on transects across the area) is about 1 foot. During the rising tide, it

would be expected that land would become inundated and during a falling tide the inundated

areas would become dry. When this was reproduced in the model simulations it caused a severe

525 attenuation of the tide range in the White Ditch area. The effect was so severe that there was no

possibility of matching the measured tide range in the White Ditch area. Local knowledge of the

area, based on discussion with airboat operators who spend a sufficient amount of time in the

White Ditch area, indicates that during normal tides the land areas do not become submerged,

even at high tides. These two factors further supported the decision to shift the Bay Gardene

530 data downward by 1.0 feet.

Note that during the model calibration, it was found that the salinity calibration was sensitive to

both the total flow rate from the Caernarvon Diversion as well as the split between the amounts

assumed to flow through the Delacroix Canal to the west and the through Bayou Mandeville to

535 the south. Therefore, the grid was modified slightly in the region of the Caernarvon Diversion so

that the flow splits could be assigned directly.

The actual values assigned to each boundary condition varied for the model calibrations and the

alternatives and the specific values used are discussed in the subsequent sections.

540

L2.6 Hydrodynamic Model Calibration

A model calibration was conducted for both hydrodynamics and salinity transport, with the

hydrodynamic calibration completed first. The hydrodynamic and salinity calibration were

545 conducted simultaneously. This was necessary because it was learned in the preliminary salinity

calibration simulations that the salinity calibration was sensitive to the total flow and flow split

assumed for the Caernarvon Diversion. Since these flow rates may influence the tidal response

in the project area, it was necessary to conduct the hydrodynamic and salinity calibration

simultaneously.

550

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The hydrodynamic calibration period was selected to coincide with the period for which the

stage data was available from the project field program, namely the four day period July 20

through July 24th. Preliminary testing with the model indicated that the tidal flows required a

relatively short spin-up period, on the order of one-week, but it was found that the salinity

555 simulations required a much longer spin-up period.

The salinity calibration focused on the same period for data comparison, July 20th through July

24th, for which salinity data was available from the project field program. After some

preliminary testing with the model, it was found that a two-month spin-up was required to

560 eliminate the effects of the initial conditions on the solution.

For the calibration simulation, the model was configured with measured wind, tide, rainfall,

evaporation, salinity and Caernarvon flow data corresponding to the calibration period. For the

evaporation, the average value of 5 mm/day adopted from the Cooke et al. (2008) study was

565 used. For the Caernarvon diversion flows, freshwater was assumed, and the corresponding

salinity was assigned a value of zero.

The key calibration parameters are:

• Bottom Fiction (Manning’s n)

570 • Lateral Dispersion

• Fresh Water flow and flow split from Caernarvon

• Fresh Water from Caernarvon reaching River Aux Chenes

The calibration simulations indicated that the hydrodynamic calibration was most sensitive to the

575 bottom friction, with a minor sensitivity to the Caernarvon flow splits. The salinity calibration

was most sensitive to the Caernarvon Diversion flow rate and flow split, with a lower level of

sensitivity to the lateral dispersion.

An initial range for the lateral dispersion was obtained by considering the length scales of the

580 water bodies in the White Ditch area and the length-scale dependent dispersion values from a

study by URS. For this analysis, a length scale was developed by taking the square-root of the

area of each of the polygons used to represent each water body and then selecting the median

value. The median value is approximately 300 meters, for which the associated dispersion

coefficient is 10m2

/s.

585

The rational for adjusting the total Caernarvon flow is that the model grid domain does not

contain the entire area influenced by the diversion flow. Therefore, only a portion of the flow

actually drains through the region covered by the model grid. The remaining portion of the flow

drains towards the MRGO channel that is not represented in the model grid. Thus it is

590 appropriate to reduce the Caernarvon flow rates so that they better represent the flow entering the

area covered by the model gird. The ‘best’ reduction level was determined via the salinity

calibration.

It was found the salinity calibration was sensitive, albeit to a smaller degree, to the assumed split

595 in Caernarvon flows that go off to the west and south. Historically the portion flowing to the

west, directly towards the White Ditch area, was about 20 to 30 percent. However, it is believed

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by local land managers that after Hurricane Katrina, the percentage flowing directly to the west

is lower, due to blockage of many of the smaller canals, and is currently about 5 to 10 percent.

600 After assigning the dispersion value, a sequence of final calibration simulations were completed

in which the bottom friction and the total flow and flow split for the Caernarvon were

systematically altered. The final calibration was obtained with the following parameter values:

• Manning’s n: 0.012

• Dispersion Coefficient: 10 m2/s

605 • Amount of Measured Caernarvon Flow applied: 58%

• Amount of Applied Caernarvon Flow directed to the west: 5%

The final stage calibration is shown in Figure L2.17 and the final salinity calibration is shown in

Figure L2.18. The simulated stage calibration indicates that the model represents the measured

610 tide amplitude reduction and phase shifts at stations S3 and N3. The salinity calibration results

shown in Figure L2.18 represent the time-averaged salinity values over the last four days of the

simulation, which correspond to the time period of the measured values obtained during the

project field program. The spatial gradients and the actual salinity levels are well represented in

the simulated results. The largest discrepancy occurs in the southern station (Simulated Salinity

615 Point 37) where the model results slightly under-predict the salinity levels.

620

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Figure L2.17: Final Stage Calibration

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Figure L2.18: Final Salinity calibration results

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625 L2.7 Hydrodynamic Alternatives Analysis

The hydrodynamic model’s primary purpose is to compare the different alternatives developed

by the project delivery team and support the quantification of environmental benefits. Each

series of simulations were established with the same background, or boundary conditions, to

630 allow for a direct comparison of benefits between each diversion alternative. There were thirteen

total alternatives being modeled as shown in Figure L2.19. Alternatives at each location consist

of a similar layout with expanded channels for the larger flow diversions. Layouts for Location

2 at the existing White Ditch are shown in Figure L2.20. Layouts for Location 3 at the existing

White Ditch are shown in Figure L2.21. Specifics showing channel cross-sections and

635 dimensions of the features involved please see section L7 - Civil Design Criteria.

640

645

650

Location 2 Location 3

White Ditch, LA Phoenix, LA

5,000 cfs X X

10,000 cfs X X

15,000 cfs X X

35,000 cfs X X

70,000 cfs X X

100,000 cfs X X

NO ACTION X

Figure L2.19

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Figure L2.20: General Layout of Outfall Features for Location 2

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Figure L2.21: General Layout of Outfall Features for Location 3

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655 L2.7.1 Initial Screening Analysis

The initial screening of alternatives was conducted to narrow down the number of alternatives to

be run for the WVA Analysis based on time constraints. These simulations were setup to

examine a hypothetical spring pulse period and allow for the comparison of results between all

660 runs. Each simulation was to run for a one month duration with “maximum” flows from the

proposed new diversion as well as from the existing Caernarvon diversion (8,000cfs). Other

parameters are as follows:

• Average spring (March-May) tidal conditions.

• Average spring (March-May) wind forcing conditions for Plaquemines Parish, LA.

665 • Average spring (March-May) rainfall inputs.

• An average evaporation constant of 5mm/day.

• Starting salinity over the entire grid of 7ppt.

Images of the salinity results can be seen on Figure L2.21 thru Figure L2.28. It is very apparent

670 that any diversion alternative will greatly freshen the project area, particularly if the diversion is

operated in conjunction with Caernarvon. Other conclusions that were drawn from this initial

modeling are that the larger diversions, 70,000cfs and 100,000cfs, will overtop the River Aux

Chene ridge which violates our project scope.

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Figure L2.21: Initial screening analysis at Location 2 with a 5,000cfs outfall 675

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Figure L2.22: Initial screening analysis at Location 2 with a 10,000cfs outfall

680

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Figure L2.23: Initial screening analysis at Location 2 with a 15,000cfs outfall

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Figure L2.24: Initial screening analysis at Location 2 with a 35,000cfs outfall

685

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Figure L2.25: Initial screening analysis at Location 3 with a 5,000cfs outfall

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Figure L2.26: Initial screening analysis at Location 3 with a 10,000cfs outfall 690

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Figure L2.27: Initial screening analysis at Location 3 with a 15,000cfs outfall

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Figure L2.28: Initial screening analysis at Location 3 with a 35,000cfs outfall

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700 L2.7.2 WVA Screening Analysis

Based off of a preliminary screening involving costs and benefits for each alternative by the

project delivery team, it was assessed that only the diversions at Phoenix, LA of 35,000cfs and

less would have further analysis conducted on them. These runs are conducted to analyze how

705 salinities would encroach back into the Breton Sound with “maintenance” flows coming from the

proposed diversion (1000cfs) and Caernarvon (800cfs). For these runs, simulations would start

following the final results of their particular runs from the initial screening of alternatives using

the salinities that were estimated there. These simulations would continue for a 3 month period

with the following parameters:

710 • Average summer (June-August) tidal conditions.

• Average summer (June-August) wind forcing conditions for Plaquemines Parish, LA.

• Average summer (June-August) rainfall inputs.

• An average evaporation constant of 5mm/day.

715 Images of the salinity result show the models progression back to a natural salinity state can be

seen in Figure L2.29. It appears that no matter the maximum diversion capacity, salinities will

still re-regulate themselves in the sound with the maintenance flows.

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Figure L2.29: Results from the WVA Analysis of Location 3 Alternatives

720

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L2.8 Ecohydraulic Modeling

The ERDC-SAND2 Model is the tool used to project marsh acreages throughout the life of the

project. It is an ecohydraulic model specifically designed to estimate impacts from flow

725 diversions on the land loss rates of coastal marsh. The ERDC-SAND2 Model is fundamentally

based on three processes impacting marsh accretion due to flow diversion:

1) Historical land loss rates are applied to account for marsh loss due to all negatively

impacting system processes (e.g. sea level rise, compaction, subsidence, etc.) along with

730 background processes existing prior to the diversion operation (e.g. marsh nutrient

cycling, net tidal and groundwater inputs, etc.).

2) Inorganic benefits of flow diversion from the addition of sediment.

735 3) Organic benefits of flow diversion due to plant growth, mortality, and burial

stimulated by addition of the limiting nutrient (nitrogen).

The model applies these processes to assess Future With Project (FWP) and Future WithOut

Project (FWOP) conditions for alternative comparison. Since the FWOP condition is without

740 diversion, FWOP marsh acreage is a function of land loss only. The model processes these

categories and projects acres of marsh within a specified project area.

For the Medium Diversion at White Ditch (MDWD) there were three different land loss rates

745 that were examined. These land loss rates were developed for the three relative sea level rise

rates that were specified by the by USACE New Orleans District (MVN). The projected sea

level rise rates that were used for analysis are shown in Figure 2.8.1 and are:

• Low Scenario (Historic Rate) – 0.40 inches per year

• Intermediate Scenario – 0.50 inches per year

750 • High Scenario – 0.81 inches per year

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755

Benefits from sediment introduction, or inorganic benefits, come from calculations within the

model. The model has 25 years of flow and suspended sediment load data from the Mississippi

River built in. This data set is rolled forward to allow for a 50 year project life. With the

760 MDWD, project maximum operations of the diversion are only proposed for March and April;

throughout the remainder of the year there is a 1,000cfs maintenance flow. During March and

April, the modeler assumed that 3% of the total flow in the Mississippi River would be diverted

(The flow through the diversion will be driven by the head difference between the river and

marsh; however, there is no good correlation between stage and flow built into the model) up to

765 the maximum capacity of the diversion. The modeler also assumed that the diversion would be

shut down at any time the Mississippi River went below 300,000cfs to protect navigational

interests. Calculations within the model distribute the sediment over open water areas.

Benefits from increased plant productivity are derived from higher nutrient rates entering into the

770 marsh. Nutrient levels are pulled from existing Mississippi River flow data and correspond to

diverted flows into the project area. Benefits from increased plant productivity result in vertical

accretion for areas of existing marsh.

For land building to occur in the ERDC-SAND2 Model, you must simply have more accretion

775 than sea level rise. With the MDWD, the majority of the benefits come from sediment

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

2010 2020 2030 2040 2050 2060 2070

Estimated Relative Sea Level Rise (feet)

Year

Figure 2.8.1: Projected Sea Level Rise for White Ditch, LA

Low Scenario (Historic Rate) Intermediate Scenario High Scenario

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deposition. Greater diversion capacities allow for more sediment deposition and more benefits.

Results from the model for the MDWD can be seen in Table 2.8.1 and Table 2.8.2.

Table 2.8.1: ERDC-SAND2 Model Calculations of Acreages for the MDWD Project Area

under Historical Sea Level Rise Rates

Historic RSLR Gross Acres of Marsh

Project Life Years 0 10 20 30 40 50

No Action Alternative (FWOP) 38,700 36,000 33,300 30,500 27,800 25,000

5,000 cfs Diversion Alternative 38,700 38,300 37,800 37,000 36,600 35,600

10,000 cfs Diversion Alternative 38,700 39,300 39,900 39,900 40,700 40,400

15,000 cfs Diversion Alternative 38,700 40,300 41,900 42,700 44,600 45,000

35,000 cfs Diversion Alternative 38,700 43,800 48,800 52,200 57,300 59,900

*** The total project area for the Medium Diversion at White Ditch is 98,000 acres

Table 2.8.2: ERDC-SAND2 Model Calculations of Acreages for the MDWD Project Area

under the Intermediate and High Sea Level Rise Rates

Intermediate RSLR Gross Acres of Marsh

Project Life Years 0 10 20 30 40 50

No Action Alternative (FWOP) 38,700 34,900 30,900 26,500 21,800 16,900

35,000 cfs Diversion Alternative 38,700 42,800 46,600 48,500 51,800 52,400

High RSLR Gross Acres of Marsh

Project Life Years 0 10 20 30 40 50

No Action Alternative (FWOP) 38,700 31,500 23,700 14,000 2,900 0

35,000 cfs Diversion Alternative 38,700 39,500 39,600 36,300 33,800 27,600

*** The total project area for the Medium Diversion at White Ditch is 98,000 acres

780

Further information on the ERDC-SAND2 Model concerning data from the runs used in the

MDWD Analysis, model verification, and the equations behind the model can be found in

Annexes of Appendix L.

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L3. Surveying, Mapping, and Geospatial Data Requirements

L3.1 Geospatial Data

790 The data which represents the potential features in the project were created using ArcGIS 9.3.

The horizontal coordinate system used for the features is NAD 1983 StatePlane Louisiana South

FIPS 1702 Feet. The data that were created during this project references the 2008 Digital

Orthophoto Quarter Quadrangles, for further information on that data set see C.3.2.

795 Plaquemine Parish provided oil gas well data, and landowner data. The horizontal coordinate

system for both sets of data is NAD 1983 StatePlane Louisiana South FIPS 1702 Feet.

Additional landowner data were provided by Ralph Gipson of Fenstermaker & Associates, Inc.

The horizontal coordinate system for the Fenstermaker data is NAD 1927 StatePlane Louisiana

South FIPS 1702 Feet. General base data is licensed for use from Tele Atlas North America.

800 The horizontal coordinate system for the Tele Atlas data is GCS WGS 1984. The Mississippi

Valley- New Orleans District provided pipeline data. This data set was produced by the Coastal

Management Division (CMD) of the Louisiana Department of Natural Resources in a

cooperative agreement with the U.S. Minerals Management Service (MMS). The data set is a

map and database of all of the pipelines that could be identified in the data available to the CMD.

805 The data sets used included the Coastal Use Permit files, State Land Office Right Of Way files,

the DNR Office of Conservation files, and MMS records. Also used were wall maps produced by

the Louisiana Geological Survey and maps and information from individual companies. The

horizontal coordinate system for the pipeline data is NAD 1983 UTM Zone 15N.

810 ArcGIS software provided the capabilities of transforming the data and aerial photography into

one uniform coordinate system for analysis of features and map production. The uniform

coordinate system used for these tasks was NAD 1983 StatePlane Louisiana South FIPS 1702

Feet.

815 L3.2 Aerial Photography and LIDAR

L3.2.1 2008 DOQQ Aerial Photography

The 2008 Digital Orthophoto Quarter Quadrangles (DOQQs) were provided by the Mississippi

820 Valley- New Orleans District. The following information is provided in the metadata of the

DOQQ data set. This data set was produced in accordance with USGS Standards for Digital

Orthophotos, 1996. Review was provided by the USGS National Geospatial Technical

Operations Center (NGTOC). The data set was created by Photo Science, Inc. in 2009 for the

USGS National Wetlands Research Center and CWPPRA Task Force.

825

The horizontal coordinate system is projected coordinate system NAD 1983 UTM Zone 15N.

The DOQQ horizontal positional accuracy and the assurance of that accuracy depend, in part, on

the accuracy of the data inputs to the rectification process. These inputs consist of the digital

elevation model (DEM), aero triangulation control and methods, sensor calibration, and aerial

830 imagery that meet National Aerial Photography Program (NAPP) standards. The vertical

accuracy of the verified USGS format DEM is equivalent to or better than a USGS level 1 or 2

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DEM, with a root mean square error (RMSE) of no greater than 7.0 meters. Field control is

acquired by third-order class 1 or better survey methods sufficiently spaced to meet National

Map Accuracy Standards (NMAS) for 1:12,000-scale products. Photo-identifiable ground test

835 points are identified in the orthorectified image and measured. The image coordinates are

compared to the known positions of these points and the radial differences for each point

computed. A radial RMSE value is then calculated for the DOQQ. Note: Adjacent DOQQ's,

when displayed together in a common planimetric coordinate system, and may exhibit positional

discrepancies across common DOQQ boundaries. Linear features, such as streets, may be offset

840 between images. However, these edge mismatches still conform to NMAS positional horizontal

accuracy requirements. The estimated accuracy is 3.34 meters which was determined by the

Federal Geographic Data Committee, 1998, Geospatial Positioning Accuracy Standard, Part 3,

National Standard for Spatial Data Accuracy, FGDC-STD-007.3-1998.

845 L3.2.2 1992 Landsat Thermatic Satellite Image of Louisiana, UMT 15 NAD27

The 1992 Landsat Imagery was provided by the Mississippi Valley- New Orleans District. The

following information is provided in the metadata of the Landsat data set. The originator of the

data is Louisiana Oil Spill Coordinator’s Office (LOSCO) and the publication date is 1996.

850

The horizontal coordinate system is projected coordinate system NAD 1983 UTM Zone 15N.

This data set is comprised of a pair of satellite images of Louisiana that were produced from ten

scenes of 30-meter resolution TM imagery. The original image data were geo-rectified and resampled to 25-meter cells by the Earth observation Satellite Corporation, EOSAT. These data

855 were obtained by LSU from the Baton Rouge office of the USGS National Wetlands Research

Center through a cooperative agreement. The processing to make a seamless enhanced image

was performed by LSU and funded by the Louisiana Oil Spill Coordinator's Office. The

locational accuracy of the satellite imagery is approximately 98 feet (30 meters). The image was

constructed from a red, green, blue (RGB) composite of bands 7,5 & 3 which has the relative

860 appearance of a normal color image, unlike typical false color composites using infrared light in

which vegetation is red instead of green. The image is a simulation of the natural environment

and is not an accurate representation of "true-color" as perceived by humans. Band 7 is midinfrared, band 5 is near-infrared, and band 3 is red-visible light. The 3-band, 24-bit composite

images were contrast stretched, histogram corrected, and color-matched, and then reduced to a

865 single band, 8-bit image resembling the original composites. They were mosaicked and clipped

to fit the 'state boundary'. That data set, which was in UTM zone 15, NAD27 coordinates, was

published on the Louisiana Oil Spill Contingency Plan Map CD in 1996. This pair of images in

UTM zone 15, NAD83 coordinates was derived by projecting and clipping splitting that UTM

zone 15 NAD27 image. The images are in GeoTIFF format, but are accompanied by world files

870 (.tfw) so they can be used in GIS that support TIFF but do not read georeferencing information

from GeoTIFF format files.

L3.2.3 2007 Mississippi River LIDAR

The LIDAR was provided by the Mississippi Valley- New Orleans District. The following

875 information is provided in the metadata of the LIDAR data set. The originator of the data is

NGS and the date is 2006.

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This data set was created to evaluate the condition of the Mississippi River Levee System and

river banks as a part of a larger levee assessment process to determine encroachments and

880 calculate slope stability. Data were collected through John Chance and Associates FLI-MAP

system, in which a helicopter flies over a given corridor at a low altitude, collecting GPS

coordinates and laser rangings. These coordinates and elevations are validated against a video

simultaneously recorded by the helicopter. The horizontal controls are “B” order or better and

the absolute accuracy is on the order of 15cm. The vertical control references the revised 2003

885 Geoid (revised in 2005 for South Louisiana) and the absolute accuracy is on the order of 10cm.

L3.3 Ground Topographic Surveys

No surveying was conducted during the feasibility stage of this project.

890

L4. Geology

The study area is from the Mississippi River, at approximately Mississippi River Mile 60, near

the Plaquemines Parish town of Phoenix and extending into the marsh towards Oak River. This

895 is an area of low relief ranging from below sea level to approximately +7 NGVD in elevation on

the area adjacent to the river.

Fine grained material make up the majority of the stratigraphy with deposits in the area

consisting of a silt to sandy silt layer with clay seams extending from ground surface to

900 approximately -80 and -40 NGVD in elevation for borings R-59.75-LU and R-60.3-UL,

respectively, shown in Figure L4.1. The silt to sandy silt layers are underlain by a clay layer

with silt seams. After an average depth of -108 NGVD for the previously two mentioned

borings, various silt and clay seams layers alternate until the end of the two borings. Borings R59.75-LU and R-60.3-UL can be seen in Figures L4.2 and L4.3, respectively.

905

Ground water is at or near the surface in the study area and is directly connected to the

Mississippi River.

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910

Figure L4.1 Overview of the project area with the boring locations used for the subsurface

evaluation.

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Figure L4.2 Subsurface exploration details for Borings R-59.75-LU.

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Figure L4.3 Subsurface exploration details for Borings R-60.3-UL.

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L5. Geotechnical Investigations and Design

915 L5.1 General

The project area is located on the east bank of the Mississippi River near the town of Phoenix

and the unincorporated area of Plaquemines Parish, Louisiana. See the vicinity map on Figure

L4.1 and Section L4 for the regional geology of the area. (This report was written after Location

920 3 was selected for the area of construction, and substantially, this geotechnical investigation and

design only refers to Location 3.) This section describes the results of geotechnical investigation

and designs performed for the diversion facility (box culvert) and transmission system (dredged

canals), discussed in Sections L5.2 and L5.3, respectively. The subsurface information available

for the design of the diversion facility and transmission system is for a general design and cost

925 estimate purposes only. A significant subsurface exploration will be needed in the future to

accurately determine the geology of the construction area. The analyses shall be revised using

the newly collected data including slope stability analyses, settlement analyses, pile foundation

design, etc. Construction considerations shall include all aspects of construction including

backfilling, dewatering, pile installation, culvert construction, and dredging. The subsequent

930 geotechnical design on the detail features will be presented in a Design Report (DR) in an

appropriate time prior to the preparation of the Plans and Specifications of the project.

L5.2 Geotechnical Design for Diversion Facility

935 L5.2.1 Stability Analyses

The results of the soil borings and laboratory test data were evaluated and the shear strength and

density parameters were selected for design. In general, design shear strengths were based on the

results of unconfined compression tests (UCT) and recommendation from the Hurricane and

940 Storm Damage Reduction System Design Guidelines (HSDRSDG). The boring locations used

for design are located in Location 3 and are shown in Figure L4.1. In addition, the available soil

design shear strengths and stratification from the borings are shown on Figures L5.1 and L5.2.

Global stability of the diversion facility was analyzed using the Spencer Method in GeoStudio

945 2007 (Version 7.14, Build 4606) for the slope stability analysis. Design requirements are such

that a minimum factor of safety of 1.4 evaluated by unconsolidated-undrained (Q) shear strength

parameters is required for low water conditions, where the Q-tests are supplemented by UCT

tests. Due to time constraints, no new borings were drilled and design was based on existing

borings with UCT test results. The analyses are shown on Plate L5.1. The results for the global

950 stability analysis showed that there were no unbalanced loads and the required factors or safety

were met. A summary of the results are presented in Table L5.1.

955

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960 Table L5.1 Global stability summary for the diversion facility

Case Boring

Number

Factor of Safety

Required Obtained

Water at Project Grade

(levees)

R-59.75-LU 1.4 7.38

R-60.3-UL 1.4 7.08

Low Water

(non-hurricane condition) S-Case

R-59.75-LU 1.4 10.23*

R-60.3-UL 1.4 5.11*

Note: * indicates that analysis was performed using an infinitely strong and weightless material

to prevent the failure surface from cutting into the diversion facility

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Figure L5.1 Strength lines shown for Borings R-59.75-LU.

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Figure L5.2 Subsurface exploration details for Borings R-60.3-UL.

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L5.2.2 Construction Excavation

There was determined to be sufficient land both riverside and landside of the Mississippi River

965 Levee (MRL) for construction of temporary flood protection, which consists of natural ground.

Excavated material from the degrading of the MRL will be used to construct this temporary

earthen barrier. The diversion facility will be constructed using an engineered staged design. A

carefully planned construction excavation should consider the following:

970 a. Risk of flooding.

b. Historical river elevations in the area of construction.

c. Excavation will be to Elevation –20 NGVD.

975

d. The approximate prevailing ground surface elevation is 6.5 NGVD.

e. Ground water outside the excavation is dependent on the river level of the

Mississippi River (Approximate Elevation is 4 NGVD).

980

Following completion of the diversion facility construction, the temporary earthen barrier can be

recycled into the MRL.

L5.2.3 Pile Foundations

985

A deep pile foundation is recommended for the diversion facility. The type of pile to be used

and the estimated ultimate pile load capacity versus tip elevation curves for cost estimate

purposes is presented. The final design should be verified in the forthcoming DR after site

specific subsurface exploration and testing is completed. The overburden pressure will be limited

990 to approximately 3500 psf in accordance with the HSDRSDG.

Analyses have been made to determine the estimated allowable single pile load capacities in

compression and tension for square, prestressed, precast concrete piles (12”x12” and 14”x14”)

and steel H-piles (HP14x73) for support of the proposed structures, as indicated by the Structural

995 Design Section. The results of the estimated pile load capacities are given on Figures L5.3 and

L.5.4 and consider the two design borings (R-59.75-LU and R-60.3-UL). The allowable load

capacities assume the piles are installed vertically and neglect skin friction along the top 2 feet to

allow for embedment in the concrete and seal slab. These allowable load capacities contain an

estimated factor of safety shown in the table below against failure of a single pile through the

1000 soil. The output for the pile design spreadsheet for both borings is shown in Plate L5.2. The pile

capacities, which accounted for the factor of safety, for the two borings were combined and the

lower, more conservative strength was chosen for design.

The Structural Design Section determined from the pile capacity charts that all piles tips would

1005 terminate at EL. -90.0’ (a total pile length of ≈ 70’, excluding the 2’ placed in the pile cap). Due

to lack of boring information, negative skin friction was not accounted for. Negative skin

friction from dragdown should be considered in subsequent design reports.

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Recommended factors-of-safety for compression and tension design loads are:

1010

Design Case With Pile Load Test Without Pile Load Test

Q-Case 2.0 3.0

S-Case 1.5 1.5

Note: Q-Case is characterized as a short term undrained case relative to the soil.

S-Case is characterized as a long term consolidated drained case relative to the

soil.

(a)

(b)

Figure L5.3 Pile design charts for piles in compression without load tests (a) and with load tests

(b).

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(a)

(b)

Figure L5.3 Pile design charts for piles in tension without load tests (a) and with load tests

(b).

1015 Precast concrete piles should meet the requirements outlined in Section 805.14 of the LSSRB.

The design of the pile should consider allowable driving stresses.

Analyses for pile capacities are based only on a soil-pile relationship. Therefore, the structural

capacity of the piles and their connections to transmit these loads should be determined by a

1020 structural engineer.

The piles will derive the majority of their supporting capacity from skin friction. Therefore, it is

necessary to consider the effect of group action. In this regard, the supporting value of friction

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piles installed in groups should be investigated on the basis of group perimeter. All piles should

1025 be installed to the same tip embedment in order to minimize differential foundation settlements.

All pile driving operations should be supervised by experienced personnel to ensure proper

procedures are followed and accurate records are kept during all pile driving operations. The

driving records should include the date, type of pile, pile size, hammer model, driving energy,

1030 and number of blows per foot of penetration for the embedment of the pile. An accurate driving

record is especially important to verify piles are installed to the required tip embedment and to

give an indication of any unusual driving characteristics which may include pile breakage.

L5.2.4 Lateral Earth Pressures

1035

Lateral earth pressures and lateral fluid pressures from ground water should be calculated prior to

design of the diversion facility.

L5.2.5 Hydrostatic Uplift

1040

Hydrostatic uplift during construction should be controlled by dewatering using sumps and

pumps, piezometers, positive cutoff, well points and/or deep wells if required. A passive trench

collection system (French drain) with gravel fill is recommended; however the contractor is

responsible for designing the necessary dewatering system. A registered professional engineer

1045 having qualifications and experience in similar dewatering and pressure relief systems shall

design this system. If a trench collection system is chosen, the trenches should not be continuous

from the riverside to the landside as to allow for uncontrollable seepage during a flood event

after construction. For cost estimating purposes, the trapezoidal trench was 3 feet deep with an 8

foot width on top and a 2 foot width on the bottom. The design along with assumptions,

1050 computations, figures and detail plans, shall be submitted for review. Piezometric levels in the

foundation strata should be reduced to no higher than the excavation surface. Adequate

temporary piezometers shall be required to monitor the performance of the dewatering system.

Because dewatering and pressure relief operations will lower the ground water level in the

vicinity of the excavations and thus result in settlement of the adjacent ground surface, measures

1055 such as cutoff walls, recharge wells, and/or some other method may be necessary design of the

dewatering system and excavation cofferdam to minimize these effects. Minimizing the duration

of dewatering and pressure relief will also minimize these effects. The pressure relief system

should be designed, installed and operated by a contractor experienced and qualified in the field

of pressure relief

1060

Hydrostatic uplift will act upon the box culvert after construction due to the return of normal

ground water levels. The total weight of the culvert plus overlying overburden must counteract

this hydrostatic uplift. A minimum factor of safety against flotation, found in the HSDRSDG and

based on total weights, should be provided at all times.

1065

L5.2.6 Backfill

Placement of approved materials as backfill should be completed according to current

recommended guidelines.

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1070 L5.3 Geotechnical Design for Transmission System

Due to the time constraints and limited existing borings away from the Mississippi River levee,

limited soil data is known for the marsh wetlands. The previously mentioned two borings (R60.3-UL and R-59.75-LU) were assumed to be representative of the entire marsh. It is

1075 recommended that additional subsurface exploration and testing be completed to verify these

assumptions.

The results of the soil borings and laboratory test data were evaluated and the shear strength and

density parameters were selected for design. In general, design shear strengths were based on the

1080 results of UCT. The available soil design shear strengths and stratification are located on the

previously mentioned Figures L5.1 and L5.2.

Stability of earth cuts were analyzed using the Spencer Method in GeoStudio 2007 (Version

7.14, Build 4606) for the slope stability analysis. Design requirements are such that a minimum

1085 factor of safety of 1.4 evaluated by unconsolidated-undrained (Q) shear strength parameters is

required for low water conditions, where the Q-tests are supplemented by UCT tests. Due to

time constraints, no new borings were drilled and design was based off of existing borings with

UCT test results. This analysis is shown on Plate L.5.3.

1090 The main channel leading away from the diversion facility was analyzed for slope stability. For

the 35,000 cfs outflow option, the slope for the main channel extends from +6 to -16 NGVD with

a 10 foot wide access berm above the slope. Using this cross-section with the boring

information, the maximum slope, meeting the required factors of safety, was determined to be 1

on 4.5 (Vertical on Horizontal). The results are summarized in Table L5.2.

1095

For cost estimating purposes, a 50% reduction factor was assumed for the consolidation of

dredged material. In subsequent design reports, additional borings need to be taken along the

transmission system in order to determine accurate material information. This additional

information will be used for determining the transmission system’s slope stability and for the

1100 settlement of the foundation and placement of the ridges lining the canals.

Table L5.2 Slope stability summary of the transmission system

Boring/Slope Case Factor of Safety

Required Obtained

R-59.75-LU

1 on 3.5

Low Water (hurricane condition) 1.4 1.84

Low Water(non-hurricane condition) 1.4 1.81

Water at Project Grade (levees) 1.4 3.48

R-60.3-UL

1 on 4.5

Low Water (hurricane condition) 1.4 2.64

Low Water(non-hurricane condition) 1.4 1.48

Water at Project Grade (levees) 1.4 5.15

1105

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L5.4 Laboratory Testing Program and Evaluations

Soil mechanics laboratory tests consisting of natural water content, unit weight, Atterberg liquid

and plastic limits, and unconfined compression shear were performed on undisturbed samples

1110 obtained from the borings. There were two 5 inch diameter borings used in this evaluation. The

borings are both in the vicinity of Location 3 and are shown on Figure L4.1. Boring R-59.75-LU

is located 290 FT. R.S. from STA.1126+00 of MRL and Boring R-60.3-UL is located 152 FT.

R.S. from STA. 1695+00 of the MRL. The results of these laboratory tests are presented on the

boring logs in Figures L4.2 and L4.3. It is recommended that additional site specific subsurface

1115 exploration and testing be completed to verify the results of these two borings.

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Top of Levee

Report generated using GeoStudio 2007, version 7.15. Copyright © 1991‐2009 GEO‐SLOPE International Ltd. 155

1.0 FILE INFORMATION

Created By: Goetz, Ryan MVSRevision Number: 90Last Edited By: Goetz, Ryan MVSDate: 3/3/2010 160Time: 3:29:48 PM

File Name: Location 3 ‐ 35k cfs ‐ Global Stability_R‐59.75‐LU.gsz

Directory: C:\Documents and Settings\B3ECGRPG\My Documents\White Ditch\Last Solved Date: 3/3/2010

Last Solved Time: 3:31:00 PM 165

2.0 PROJECT SETTINGS

Length(L) Units: feet

Time(t) Units: Seconds

Force(F) Units: lbf

Pressure(p) Units: psf 170

Strength Units: psfUnit Weight of Water: 62.4 pcfView: 2D

3.0 ANALYSIS SETTINGS3.1 Top of Levee 175

Kind: SLOPE/WMethod: Spencer

Settings

Apply Phreatic Correction: NoPWP Conditions Source: Piezometric Line 180

Use Staged Rapid Drawdown: No

SlipSurface

Direction of movement: Left to RightUse Passive Mode: NoSlip Surface Option: Block 185

Critical slip surfaces saved: 1

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Optimize Critical Slip Surface Location: YesTension Crack

Tension Crack Option: (none)

FOS Distribution 190

FOS Calculation Option: Constant

Restrict Block Crossing: YesAdvanced

Number of Slices: 75Optimization Tolerance: 0.01 195

Minimum Slip Surface Depth: 0.1 ftOptimization Maximum Iterations: 5000

Optimization Convergence Tolerance: 1e-007

Starting Optimization Points: 8Ending Optimization Points: 16 200Complete Passes per Insertion: 1Driving Side Maximum Convex Angle: 5 °Resisting Side Maximum Convex Angle: 1 °

4.0 MATERIALS4.1 Layer 1-ML 205

Model: Mohr-Coulomb

Unit Weight: 117 pcf

Cohesion: 200 psf

Phi: 15 °Phi-B: 0 ° 210

Pore Water Pressure

Piezometric Line: 1

4.2 Layer 2-SP

Model: Mohr-Coulomb

Unit Weight: 122 pcf 215

Cohesion: 0 psfPhi: 33 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1 220

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4.3 Layer 3-CL

Model: Mohr-Coulomb

Unit Weight: 105 pcf

Cohesion: 1580 psfPhi: 0 ° 225Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

4.4 Layer 4-ML

Model: Mohr-Coulomb 230Unit Weight: 117 pcf

Cohesion: 200 psf

Phi: 15 °Phi-B: 0 °

Pore Water Pressure 235

Piezometric Line: 1

5.0 SLIP SURFACE LIMITS

Left Coordinate: (-500, -16) ftRight Coordinate: (1000, -16) ft

6.0 SLIP SURFACE BLOCK 240

Left Grid

Upper Left: (-140.5428, -29.3568) ftLower Left: (-140.5428, -137.335) ftLower Right: (-1.358, -137.335) ftX Increments: 10 245

Y Increments: 10Starting Angle: 115 °Ending Angle: 135 °Angle Increments: 3

Right Grid 250

Upper Left: (532.9439, -32.40831) ft

Lower Left: (532.9439, -136.39582) ftLower Right: (684.9054, -136.39582) ftX Increments: 10Y Increments: 10 255

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Starting Angle: 0 °Ending Angle: 45 °Angle Increments: 3

7.0 PIEZOMETRIC LINES7.1 Piezometric Line 1 260

7.1.1 Coordinates

X (ft) Y (ft)

-500 15

0 150 -20

534 -20534 -16534 -2

1000 -2

8.0 REGIONS

Material Points Area (ft2)

Region 1 Layer 1-ML 1,2,3,4,5,6,11,7 35364Region 2 Layer 2-SP 7,11,12,8 63000Region 3 Layer 3-CL 9,8,12,13 43500Region 4 Layer 4-ML 10,9,13,14 57000Region 5 17,15,16,19,20,21,22,23,24,25,26 1182.5Region 6 3,2,18,17,26,25,24,27,28,5,4 12973

9.0 POINTS

X (ft) Y (ft)

Point 1 -500 -16Point 2 0 -16

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Point 3 0 -20Point 4 534 -20Point 5 534 -16Point 6 1000 -16Point 7 -500 -41Point 8 -500 -83Point 9 -500 -112Point 10 -500 -150Point 11 1000 -41Point 12 1000 -83Point 13 1000 -112Point 14 1000 -150Point 15 260 15Point 16 275 15Point 17 235 7Point 18 0 7Point 19 310 6Point 20 325 5Point 21 335 6Point 22 340 7Point 23 407 7Point 24 435 2Point 25 245 2Point 26 245 7

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Point 27 534 2Point 28 534 -2Point 29 0 15Point 30 -500 15

10.0 CRITICAL SLIP SURFACES

Slip Surface FOS Center (ft) Radius (ft) Entry (ft) Exit (ft)

1 Optimized 7.379 (273.321, -16) 272.7444 (-128.336, -16) (591.648, -16)2 17388 14.640 (273.321, -16) 282.839 (-101.097, -16) (647.738, -16)

10.1 Slices of Slip Surface: Optimized 265

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 Optimized -123.90385 -19.125 2129.4231 2263.9411 36.043996 2002 Optimized -115.03955 -25.375 2519.424 2982.4463 124.06645 2003 Optimized -106.17525 -31.625 2909.4248 3701.0436 212.11361 2004 Optimized -97.31094 -37.875 3299.4257 4419.5487 300.13606 2005 Optimized -87.70344 -44.649 3722.1245 5183.4177 948.97486 06 Optimized -77.38865 -52.63575 4220.4652 6096.5083 1218.3167 07 Optimized -67.10975 -61.31125 4761.8517 7112.6674 1526.6376 08 Optimized -56.83085 -69.98675 5303.1638 8128.9752 1835.1034 09 Optimized -46.55195 -78.66225 5844.5503 9144.5395 2143.0381 0

10 Optimized -37.090075 -86.648175 6342.8683 10113.69 0 158011 Optimized -28.445225 -93.94452 6798.1214 10873.918 0 158012 Optimized -19.56274 -101.1945 7250.5169 11646.947 0 158013 Optimized -10.442624 -108.39815 7700.012 12398.113 0 158014 Optimized -3.3970835 -113.9632 8047.2428 13007.31 1329.0459 200

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15 Optimized -0.4558 -116.2457 8189.6958 13297.755 1368.7004 20016 Optimized 0.0404 -116.5933 6027.4621 10954.322 1320.1483 20017 Optimized 4.8526085 -116.3976 6015.201 11156.434 1377.5893 20018 Optimized 14.396224 -115.94955 5987.2549 11104.101 1371.0547 20019 Optimized 23.93984 -115.5015 5959.3089 11051.767 1364.5201 20020 Optimized 33.48346 -115.0535 5931.3629 10999.434 1357.9856 20021 Optimized 43.027075 -114.60545 5903.4168 10947.101 1351.451 20022 Optimized 52.57069 -114.1574 5875.4708 10894.767 1344.9164 20023 Optimized 62.2438 -113.7759 5851.6512 10845.605 1338.126 20024 Optimized 72.0464 -113.4609 5831.9727 10808.899 1333.5635 20025 Optimized 81.849 -113.1459 5812.2942 10771.174 1328.7278 20026 Optimized 91.6516 -112.8309 5792.6158 10734.468 1324.1653 20027 Optimized 101.4542 -112.5159 5773.0392 10697.762 1319.5754 20028 Optimized 111.8586 -112.2709 5757.6636 10664.46 1314.7721 20029 Optimized 122.8648 -112.09585 5746.762 10643.565 1312.0944 20030 Optimized 133.2148 -112.00845 5741.2826 10628.413 1309.5027 20031 Optimized 142.90865 -112.0088 5741.3857 10628.413 1309.4751 20032 Optimized 152.6025 -112.00915 5741.3857 10628.413 1309.4751 20033 Optimized 162.2963 -112.0095 5741.3857 10628.413 1309.4751 20034 Optimized 171.9901 -112.00985 5741.3857 10628.413 1309.4751 20035 Optimized 181.68395 -112.0102 5741.3857 10629.445 1309.7515 20036 Optimized 191.3778 -112.01055 5741.4889 10629.445 1309.7239 20037 Optimized 201.0716 -112.0109 5741.4889 10629.445 1309.7239 20038 Optimized 210.7654 -112.01125 5741.4889 10629.445 1309.7239 200

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39 Optimized 220.45925 -112.0116 5741.4889 10629.445 1309.7239 20040 Optimized 230.1531 -112.01195 5741.592 10629.445 1309.6962 20041 Optimized 240 -112.0123 5741.6 10629 1309.5749 20042 Optimized 248.75 -112.0126 5741.6 10629.2 1309.6285 20043 Optimized 256.25 -112.01285 5741.6 10629.333 1309.6642 20044 Optimized 263.75 -112.01315 5741.6 10629.333 1309.6642 20045 Optimized 271.25 -112.01345 5741.6 10629.333 1309.6642 20046 Optimized 279.375 -112.01375 5741.6 10629.371 1309.6744 20047 Optimized 288.125 -112.01405 5741.7143 10629.371 1309.6438 20048 Optimized 296.875 -112.01435 5741.7143 10629.486 1309.6744 20049 Optimized 305.625 -112.01465 5741.7143 10629.486 1309.6744 20050 Optimized 314.02885 -112.01495 5741.7129 10629.46 1309.6679 20051 Optimized 321.5351 -112.06035 5744.6104 10631.037 1309.3141 20052 Optimized 325.71125 -112.1178 5748.1717 10636.654 1309.8649 20053 Optimized 327.78545 -112.065 5744.8768 10649.5 1314.1899 20054 Optimized 329.28115 -111.9943 5740.2673 10641.691 0 158055 Optimized 332.2007 -111.55325 5712.9393 10628.478 0 158056 Optimized 337.5 -110.72905 5661.5325 10541.857 0 158057 Optimized 344.7857 -109.5959 5590.7689 10422.75 0 158058 Optimized 354.35715 -108.10725 5497.8561 10266.244 0 158059 Optimized 363.9286 -106.61855 5405.0466 10109.737 0 158060 Optimized 373.5 -105.1299 5312.1338 9953.2308 0 158061 Optimized 383.0714 -103.64125 5219.221 9796.7244 0 158062 Optimized 392.64285 -102.1526 5126.3082 9640.1147 0 1580

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63 Optimized 402.2143 -100.66396 5033.3954 9483.6083 0 158064 Optimized 412.3263 -99.09121 4935.3148 9318.5303 0 158065 Optimized 422.9789 -97.434395 4831.8889 9144.0513 0 158066 Optimized 431.6526 -96.1431 4751.3452 9003.3198 0 158067 Optimized 439.69645 -95.03077 4681.8775 8886.3396 0 158068 Optimized 449.08935 -93.731885 4600.8846 8749.7694 0 158069 Optimized 458.4823 -92.433 4519.7862 8613.1993 0 158070 Optimized 467.87525 -91.134115 4438.7932 8476.7346 0 158071 Optimized 477.26815 -89.83523 4357.6948 8340.1645 0 158072 Optimized 486.6611 -88.536345 4276.7019 8203.5943 0 158073 Optimized 496.05405 -87.23746 4195.6035 8067.0242 0 158074 Optimized 505.44695 -85.938575 4114.6105 7930.4541 0 158075 Optimized 511.5134 -84.144565 4002.6619 7939.2243 0 158076 Optimized 518.16255 -78.58949 3655.9989 7372.3253 2413.4106 077 Optimized 528.72085 -69.76847 3105.5639 6244.9984 2038.7726 078 Optimized 539.9296 -60.404015 3644.436 6418.2556 1801.3395 079 Optimized 551.78885 -50.49612 3026.1263 5152.2576 1380.7258 080 Optimized 560.32685 -43.271085 2575.3772 4236.0574 1078.4584 081 Optimized 567.72065 -36.833335 2173.6081 3399.7299 328.53833 20082 Optimized 577.29155 -28.5 1653.6096 2401.8906 200.50129 20083 Optimized 586.8625 -20.166665 1133.611 1404.13 72.485353 200

10.2 Slices of Slip Surface: 17388

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 17388 -96.930715 -20.166665 2194.3792 2386.7406 51.543076 200

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2 17388 -88.59736 -28.5 2714.4422 3346.511 169.36232 2003 17388 -80.264025 -36.833335 3234.4204 4306.2814 287.20429 2004 17388 -70.84736 -46.25 3822.0138 5390.0402 1018.2882 05 17388 -60.34736 -56.75 4477.1988 6635.6258 1401.6989 06 17388 -49.84736 -67.25 5132.3839 7881.2114 1785.1095 07 17388 -39.34736 -77.75 5787.5689 9127.0664 2168.695 08 17388 -29.264025 -87.833335 6416.7751 10305.96 0 15809 17388 -19.59736 -97.499985 7020.0348 11313.222 0 1580

10 17388 -9.930695 -107.16665 7622.8555 12320.483 0 158011 17388 -3.22768 -113.8697 8041.4065 13044.003 1340.4416 20012 17388 -0.679 -115.7392 8158.3211 13466.863 1422.4195 20013 17388 4.8958335 -115.73775 5974.0594 11064.51 1363.9822 20014 17388 14.687499 -115.73525 5973.8551 11063.489 1363.7633 20015 17388 24.479165 -115.73275 5973.753 11063.489 1363.7907 20016 17388 34.270835 -115.73025 5973.5487 11063.489 1363.8454 20017 17388 44.0625 -115.7277 5973.4466 11063.489 1363.8727 20018 17388 53.854165 -115.72515 5973.2423 11062.468 1363.6538 20019 17388 63.645835 -115.72265 5973.1402 11062.468 1363.6812 20020 17388 73.4375 -115.72015 5972.936 11062.468 1363.7359 20021 17388 83.229165 -115.71765 5972.7317 11061.446 1363.517 20022 17388 93.020835 -115.71515 5972.6296 11061.446 1363.5444 20023 17388 102.81249 -115.71265 5972.4253 11061.446 1363.5991 20024 17388 112.60415 -115.71015 5972.3232 11061.446 1363.6265 20025 17388 122.39585 -115.7076 5972.1189 11060.425 1363.4075 200

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26 17388 132.1875 -115.70505 5972.0168 11060.425 1363.4349 20027 17388 141.97915 -115.70255 5971.8126 11060.425 1363.4896 20028 17388 151.77085 -115.70005 5971.7104 11059.404 1363.2433 20029 17388 161.5625 -115.69755 5971.5062 11059.404 1363.2981 20030 17388 171.35415 -115.69505 5971.4041 11059.404 1363.3254 20031 17388 181.14585 -115.69255 5971.1998 11058.383 1363.1065 20032 17388 190.9375 -115.69 5971.0977 11058.383 1363.1339 20033 17388 200.72915 -115.68745 5970.8934 11058.383 1363.1886 20034 17388 210.52085 -115.68495 5970.7913 11058.383 1363.216 20035 17388 220.3125 -115.68245 5970.587 11057.361 1362.9971 20036 17388 230.10415 -115.67995 5970.3828 11057.361 1363.0518 20037 17388 240 -115.6774 5970.3 11057 1362.9772 20038 17388 248.75 -115.67515 5970.1333 11056.8 1362.9682 20039 17388 256.25 -115.67325 5970 11056.667 1362.9682 20040 17388 263.75 -115.67135 5969.8667 11056.4 1362.9325 20041 17388 271.25 -115.6694 5969.7333 11056.133 1362.8968 20042 17388 279.375 -115.6673 5969.6 11055.886 1362.8661 20043 17388 288.125 -115.66505 5969.4857 11055.657 1362.8355 20044 17388 296.875 -115.6628 5969.3714 11055.429 1362.8049 20045 17388 305.625 -115.66055 5969.2571 11055.2 1362.7743 20046 17388 313.75 -115.65845 5969.0667 11054.933 1362.7539 20047 17388 321.25 -115.65655 5968.9333 11054.667 1362.7181 20048 17388 330 -115.6543 5968.8 11054 1362.5752 20049 17388 337.5 -115.65235 5968.8 11054.2 1362.6288 200

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50 17388 344.7857 -115.6505 5968.5967 11053.731 1362.5576 20051 17388 354.35715 -115.64805 5968.3878 11053.731 1362.6136 20052 17388 363.9286 -115.6456 5968.2833 11053.731 1362.6416 20053 17388 373.5 -115.64315 5968.1788 11052.686 1362.3896 20054 17388 383.0714 -115.6407 5967.9699 11052.686 1362.4456 20055 17388 392.64285 -115.63825 5967.8654 11052.686 1362.4736 20056 17388 402.2143 -115.63575 5967.6564 11052.686 1362.5296 20057 17388 411.66665 -115.6333 5967.5353 11051.785 1362.3206 20058 17388 421 -115.63095 5967.321 11051.785 1362.378 20059 17388 430.33335 -115.6286 5967.2139 11051.785 1362.4067 20060 17388 439.95 -115.6261 5967.0707 11051.515 1362.3728 20061 17388 449.85 -115.62355 5966.8687 11050.505 1362.1563 20062 17388 459.75 -115.621 5966.7677 11050.505 1362.1833 20063 17388 469.65 -115.61845 5966.5657 11050.505 1362.2375 20064 17388 479.55 -115.61595 5966.4646 11049.495 1361.9939 20065 17388 489.45 -115.6134 5966.2626 11049.495 1362.048 20066 17388 499.35 -115.61085 5966.1616 11049.495 1362.0751 20067 17388 509.25 -115.6083 5965.9596 11049.495 1362.1292 20068 17388 519.15 -115.60575 5965.7576 11048.485 1361.9127 20069 17388 529.05 -115.6032 5965.6566 11048.485 1361.9397 20070 17388 541.07 -115.6001 7088.3766 12389.631 1420.4668 20071 17388 549.9392 -113.79915 6976.3146 12385.459 1449.3759 20072 17388 556.5717 -107.16665 6562.4147 11657.022 0 158073 17388 566.23835 -97.499985 5959.2282 10634.399 0 1580

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74 17388 575.90505 -87.833335 5355.9686 9611.7764 0 158075 17388 585.9884 -77.75 4726.7739 8515.5873 2460.4842 076 17388 596.4884 -67.25 4071.5888 7194.981 2028.3546 077 17388 606.9884 -56.75 3416.4038 5874.4421 1596.2687 078 17388 617.4884 -46.25 2761.2188 4553.7011 1164.0516 079 17388 626.90505 -36.833335 2173.5902 3372.4759 321.24046 20080 17388 635.23835 -28.5 1653.6121 2381.31 194.98607 20081 17388 643.5717 -20.166665 1133.6339 1390.144 68.73168 200

270

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Water at Project Grade (levee)Report generated using GeoStudio 2007, version 7.15. Copyright © 1991-2009 GEO-SLOPE International Ltd. 285

11.0FILE INFORMATION

Created By: Goetz, Ryan MVSRevision Number: 96Last Edited By: Goetz, Ryan MVSDate: 3/7/2010 290Time: 11:30:30 AMFile Name: Location 3 - 35k cfs - Global Stability_R-60.3-LU.gszDirectory: C:\Documents and Settings\B3ECGRPG\My Documents\White Ditch\Last Solved Date: 3/7/2010Last Solved Time: 11:30:55 AM 295

12.0PROJECT SETTINGS

Length(L) Units: feet

Time(t) Units: Seconds

Force(F) Units: lbf

Pressure(p) Units: psf 300

Strength Units: psfUnit Weight of Water: 62.4 pcfView: 2D

13.0ANALYSIS SETTINGS13.1 Low Water (hurricane condition) 305

Description: Active and Passive Wedge MethodKind: SLOPE/WMethod: Spencer

Settings

Apply Phreatic Correction: No 310

PWP Conditions Source: Piezometric LineUse Staged Rapid Drawdown: No

SlipSurface

Direction of movement: Left to RightUse Passive Mode: No 315

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Slip Surface Option: BlockCritical slip surfaces saved: 1Optimize Critical Slip Surface Location: YesTension Crack

Tension Crack Option: (none) 320

FOS Distribution

FOS Calculation Option: Constant

Restrict Block Crossing: YesAdvanced

Number of Slices: 75 325

Optimization Tolerance: 0.01Minimum Slip Surface Depth: 0.1 ftOptimization Maximum Iterations: 5000

Optimization Convergence Tolerance: 1e-007

Starting Optimization Points: 8 330Ending Optimization Points: 16Complete Passes per Insertion: 1Driving Side Maximum Convex Angle: 5 °Resisting Side Maximum Convex Angle: 1 °

14.0MATERIALS 33514.1 Layer 5 - ML

Model: Mohr-Coulomb

Unit Weight: 117 pcf

Cohesion: 200 psf

Phi: 15 ° 340

Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

14.2 Layer 4 - CL

Model: Mohr-Coulomb 345Unit Weight: 107 pcf

Cohesion: 550 psf

Phi: 0 °

Phi-B: 0 °

Pore Water Pressure 350

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Piezometric Line: 1

14.3 Layer 6 - CL

Model: Mohr-Coulomb

Unit Weight: 101 pcf

Cohesion: 780 psf 355Phi: 0 °

Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

14.4 Layer 7 - CL 360

Model: S=f(depth)Unit Weight: 101 pcf

C-Top of Layer: 500 psfC-Rate of Change: 14 psf/ftLimiting C: 1200 psf 365

Pore Water Pressure

Piezometric Line: 1

14.5 Layer 3 - SM

Model: Mohr-Coulomb

Unit Weight: 122 pcf 370

Cohesion: 0 psfPhi: 30 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1 375

14.6 Layer 9 - CL

Model: Mohr-Coulomb

Unit Weight: 115 pcf

Cohesion: 900 psf

Phi: 0 ° 380

Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

14.7 Layer 10 - SM

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Model: Mohr-Coulomb 385Unit Weight: 122 pcf

Cohesion: 0 psfPhi: 30 °Phi-B: 0 °

Pore Water Pressure 390

Piezometric Line: 1

14.8 Layer 8 - ML

Model: Mohr-Coulomb

Unit Weight: 117 pcf

Cohesion: 200 psf 395Phi: 15 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

15.0SLIP SURFACE LIMITS 400

Left Coordinate: (-500, -15) ftRight Coordinate: (1000, -16) ft

16.0SLIP SURFACE BLOCK

Left Grid

Upper Left: (-21.2598, -24) ft 405

Lower Left: (-21.2598, -126) ftLower Right: (57.7899, -126) ftX Increments: 5Y Increments: 10Starting Angle: 115 ° 410Ending Angle: 135 °Angle Increments: 3

Right Grid

Upper Left: (531.875, -24) ftLower Left: (531.875, -126) ft 415

Lower Right: (631.067, -126) ftX Increments: 5Y Increments: 10Starting Angle: 0 °

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Ending Angle: 45 ° 420Angle Increments: 3

17.0PIEZOMETRIC LINES17.1 Piezometric Line 1

17.1.1 Coordinates

X (ft) Y (ft)

-500 15

0 150 -20

534 -20534 -2

1000 -2

18.0 REGIONS 425

Material Points Area (ft2)

Region 1 Layer 10 - SM 17,18,12,8 28500Region 2 Layer 9 - CL 17,7,11,18 16500Region 3 Layer 8 - ML 7,6,10,11 16500Region 4 Layer 5 - ML 15,16,9,21 17250Region 5 Layer 4 - CL 5,15,21,20 8250Region 6 Layer 3 - SM 14,23,3,4,24,19,20,5 10364Region 7 Layer 6 - CL 16,25,26,9 13500Region 8 Layer 7 - CL 25,6,10,26 81000Region 9 29,27,28,31,32,33,34,35,36,37,38 1182.5Region 10 3,23,22,2,30,29,38,37,36,39,40,24,4 12973

19.0 POINTS

X (ft) Y (ft)

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Point 1 -500 2Point 2 0 2Point 3 0 -20Point 4 534 -20Point 5 -500 -24Point 6 -500 -104Point 7 -500 -115Point 8 -500 -145Point 9 1000 -41Point 10 1000 -104Point 11 1000 -115Point 12 1000 -145Point 13 -500 -10Point 14 -500 -15Point 15 -500 -29.5Point 16 -500 -41Point 17 -500 -126Point 18 1000 -126Point 19 1000 -16Point 20 1000 -24Point 21 1000 -29.5Point 22 0 -10Point 23 0 -15Point 24 534 -16

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Point 25 -500 -50Point 26 1000 -50Point 27 260 15Point 28 275 15Point 29 235 7Point 30 0 7Point 31 310 6Point 32 325 5Point 33 335 6Point 34 340 7Point 35 407 7Point 36 435 2Point 37 245 2Point 38 245 7Point 39 534 2Point 40 534 -2Point 41 1000 -2Point 42 -500 15Point 43 0 15

20.0 CRITICAL SLIP SURFACES

Slip Surface FOS Center (ft) Radius (ft) Entry (ft) Exit (ft)

1 Optimized 7.079 (273.642, -14.75) 198.0375 (-14.4499, -15) (561.731, -16)2 170 7.079 (273.642, -14.75) 198.038 (-14.4499, -15) (561.731, -16)

20.1 Slices of Slip Surface: Optimized

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Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 Optimized -9.94986 -19.5 2152.8262 2386.9572 135.17557 02 Optimized -2.72493 -24 2433.6405 2970.3515 309.87026 03 Optimized 3.7903225 -24 249.59618 488.12469 137.7145 04 Optimized 11.370967 -24 249.59618 488.12469 137.7145 05 Optimized 18.951615 -24 249.59618 488.12469 137.7145 06 Optimized 26.53226 -24 249.59618 488.12469 137.7145 07 Optimized 34.112905 -24 249.59618 488.12469 137.7145 08 Optimized 41.69355 -24 249.59618 488.12469 137.7145 09 Optimized 49.274195 -24 249.59618 488.12469 137.7145 0

10 Optimized 56.85484 -24 249.59618 488.12469 137.7145 011 Optimized 64.435485 -24 249.59618 488.12469 137.7145 012 Optimized 72.01613 -24 249.59618 488.12469 137.7145 013 Optimized 79.596775 -24 249.59618 488.12469 137.7145 014 Optimized 87.17742 -24 249.59618 488.12469 137.7145 015 Optimized 94.758065 -24 249.59618 488.12469 137.7145 016 Optimized 102.3387 -24 249.59618 488.12469 137.7145 017 Optimized 109.91935 -24 249.59618 488.12469 137.7145 018 Optimized 117.5 -24 249.59618 488.12469 137.7145 019 Optimized 125.08065 -24 249.59618 488.12469 137.7145 020 Optimized 132.6613 -24 249.59618 488.12469 137.7145 021 Optimized 140.24195 -24 249.59618 488.12469 137.7145 022 Optimized 147.8226 -24 249.59618 488.12469 137.7145 023 Optimized 155.4032 -24 249.59618 488.12469 137.7145 0

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24 Optimized 162.98385 -24 249.59618 488.12469 137.7145 025 Optimized 170.5645 -24 249.59618 488.12469 137.7145 026 Optimized 178.14515 -24 249.59618 488.12469 137.7145 027 Optimized 185.7258 -24 249.59618 488.12469 137.7145 028 Optimized 193.30645 -24 249.59618 488.12469 137.7145 029 Optimized 200.8871 -24 249.59618 488.12469 137.7145 030 Optimized 208.46775 -24 249.59618 488.12469 137.7145 031 Optimized 216.0484 -24 249.59618 488.12469 137.7145 032 Optimized 223.62905 -24 249.59618 488.12469 137.7145 033 Optimized 231.2097 -24 249.59618 488.12469 137.7145 034 Optimized 240 -24 249.6 488.12 137.70959 035 Optimized 248.75 -24 249.6 488.12 137.70959 036 Optimized 256.25 -24 249.6 488.12 137.70959 037 Optimized 263.75 -24 249.6 488.12 137.70959 038 Optimized 271.25 -24 249.6 488.12 137.70959 039 Optimized 278.5 -24 249.6 488.12857 137.71453 040 Optimized 285.5 -24 249.6 488.12857 137.71453 041 Optimized 292.5 -24 249.6 488.12857 137.71453 042 Optimized 299.5 -24 249.6 488.12857 137.71453 043 Optimized 306.5 -24 249.6 488.12857 137.71453 044 Optimized 313.75 -24 249.6 488.12 137.70959 045 Optimized 321.25 -24 249.6 488.12 137.70959 046 Optimized 330 -24 249.6 488.12 137.70959 047 Optimized 337.5 -24 249.6 488.12 137.70959 0

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48 Optimized 343.7222 -24 249.59554 488.12242 137.71356 049 Optimized 351.16665 -24 249.59554 488.12242 137.71356 050 Optimized 358.6111 -24 249.59554 488.12242 137.71356 051 Optimized 366.05555 -24 249.59554 488.12242 137.71356 052 Optimized 373.5 -24 249.59554 488.12242 137.71356 053 Optimized 380.94445 -24 249.59554 488.12242 137.71356 054 Optimized 388.3889 -24 249.59554 488.12242 137.71356 055 Optimized 395.83335 -24 249.59554 488.12242 137.71356 056 Optimized 403.2778 -24 249.59554 488.12242 137.71356 057 Optimized 410.5 -24 249.6 488.12857 137.71453 058 Optimized 417.5 -24 249.6 488.12857 137.71453 059 Optimized 424.5 -24 249.6 488.12857 137.71453 060 Optimized 431.5 -24 249.6 488.12857 137.71453 061 Optimized 438.72595 -24 249.6 488.12904 137.7148 062 Optimized 446.17785 -24 249.6 488.12904 137.7148 063 Optimized 453.6298 -24 249.6 488.12904 137.7148 064 Optimized 461.08175 -24 249.6 488.12904 137.7148 065 Optimized 468.53365 -24 249.6 488.12904 137.7148 066 Optimized 475.98555 -24 249.6 488.12904 137.7148 067 Optimized 483.4375 -24 249.6 488.12904 137.7148 068 Optimized 490.88945 -24 249.6 488.12904 137.7148 069 Optimized 498.34135 -24 249.6 488.12904 137.7148 070 Optimized 505.79325 -24 249.6 488.12904 137.7148 071 Optimized 513.2452 -24 249.6 488.12904 137.7148 0

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72 Optimized 520.69715 -24 249.6 488.12904 137.7148 073 Optimized 528.14905 -24 249.6 488.12904 137.7148 074 Optimized 532.9375 -23.715305 231.83582 459.14429 131.23661 075 Optimized 537.46645 -22.501785 1279.3044 1678.5985 230.53257 076 Optimized 544.3993 -20.64413 1163.3992 1448.9894 164.88561 077 Optimized 551.33215 -18.786475 1047.48 1219.4639 99.294951 078 Optimized 558.265 -16.928825 931.56088 989.89664 33.680165 0

20.2 Slices of Slip Surface: 170

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 170 -9.94986 -19.5 2152.8262 2386.9572 135.17557 02 170 -2.72493 -24 2433.6405 2970.3515 309.87026 03 170 3.7903225 -24 249.59618 488.12469 137.7145 04 170 11.370967 -24 249.59618 488.12469 137.7145 05 170 18.951615 -24 249.59618 488.12469 137.7145 06 170 26.53226 -24 249.59618 488.12469 137.7145 07 170 34.112905 -24 249.59618 488.12469 137.7145 08 170 41.69355 -24 249.59618 488.12469 137.7145 09 170 49.274195 -24 249.59618 488.12469 137.7145 0

10 170 56.85484 -24 249.59618 488.12469 137.7145 011 170 64.435485 -24 249.59618 488.12469 137.7145 012 170 72.01613 -24 249.59618 488.12469 137.7145 013 170 79.596775 -24 249.59618 488.12469 137.7145 014 170 87.17742 -24 249.59618 488.12469 137.7145 015 170 94.758065 -24 249.59618 488.12469 137.7145 0

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16 170 102.3387 -24 249.59618 488.12469 137.7145 017 170 109.91935 -24 249.59618 488.12469 137.7145 018 170 117.5 -24 249.59618 488.12469 137.7145 019 170 125.08065 -24 249.59618 488.12469 137.7145 020 170 132.6613 -24 249.59618 488.12469 137.7145 021 170 140.24195 -24 249.59618 488.12469 137.7145 022 170 147.8226 -24 249.59618 488.12469 137.7145 023 170 155.4032 -24 249.59618 488.12469 137.7145 024 170 162.98385 -24 249.59618 488.12469 137.7145 025 170 170.5645 -24 249.59618 488.12469 137.7145 026 170 178.14515 -24 249.59618 488.12469 137.7145 027 170 185.7258 -24 249.59618 488.12469 137.7145 028 170 193.30645 -24 249.59618 488.12469 137.7145 029 170 200.8871 -24 249.59618 488.12469 137.7145 030 170 208.46775 -24 249.59618 488.12469 137.7145 031 170 216.0484 -24 249.59618 488.12469 137.7145 032 170 223.62905 -24 249.59618 488.12469 137.7145 033 170 231.2097 -24 249.59618 488.12469 137.7145 034 170 240 -24 249.6 488.12 137.70959 035 170 248.75 -24 249.6 488.12 137.70959 036 170 256.25 -24 249.6 488.12 137.70959 037 170 263.75 -24 249.6 488.12 137.70959 038 170 271.25 -24 249.6 488.12 137.70959 039 170 278.5 -24 249.6 488.12857 137.71453 0

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40 170 285.5 -24 249.6 488.12857 137.71453 041 170 292.5 -24 249.6 488.12857 137.71453 042 170 299.5 -24 249.6 488.12857 137.71453 043 170 306.5 -24 249.6 488.12857 137.71453 044 170 313.75 -24 249.6 488.12 137.70959 045 170 321.25 -24 249.6 488.12 137.70959 046 170 330 -24 249.6 488.12 137.70959 047 170 337.5 -24 249.6 488.12 137.70959 048 170 343.7222 -24 249.59554 488.12242 137.71356 049 170 351.16665 -24 249.59554 488.12242 137.71356 050 170 358.6111 -24 249.59554 488.12242 137.71356 051 170 366.05555 -24 249.59554 488.12242 137.71356 052 170 373.5 -24 249.59554 488.12242 137.71356 053 170 380.94445 -24 249.59554 488.12242 137.71356 054 170 388.3889 -24 249.59554 488.12242 137.71356 055 170 395.83335 -24 249.59554 488.12242 137.71356 056 170 403.2778 -24 249.59554 488.12242 137.71356 057 170 410.5 -24 249.6 488.12857 137.71453 058 170 417.5 -24 249.6 488.12857 137.71453 059 170 424.5 -24 249.6 488.12857 137.71453 060 170 431.5 -24 249.6 488.12857 137.71453 061 170 438.72595 -24 249.6 488.12904 137.7148 062 170 446.17785 -24 249.6 488.12904 137.7148 063 170 453.6298 -24 249.6 488.12904 137.7148 0

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64 170 461.08175 -24 249.6 488.12904 137.7148 065 170 468.53365 -24 249.6 488.12904 137.7148 066 170 475.98555 -24 249.6 488.12904 137.7148 067 170 483.4375 -24 249.6 488.12904 137.7148 068 170 490.88945 -24 249.6 488.12904 137.7148 069 170 498.34135 -24 249.6 488.12904 137.7148 070 170 505.79325 -24 249.6 488.12904 137.7148 071 170 513.2452 -24 249.6 488.12904 137.7148 072 170 520.69715 -24 249.6 488.12904 137.7148 073 170 528.14905 -24 249.6 488.12904 137.7148 074 170 532.9375 -23.715305 231.83582 459.14429 131.23661 075 170 537.46645 -22.501785 1279.3044 1678.5985 230.53257 076 170 544.3993 -20.64413 1163.3992 1448.9894 164.88561 077 170 551.33215 -18.786475 1047.48 1219.4639 99.294951 078 170 558.265 -16.928825 931.56088 989.89664 33.680165 0

430435

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Top of Levee - S-Case

Report generated using GeoStudio 2007, version 7.15. Copyright © 1991-2009 GEO-SLOPE International Ltd.

21.0FILE INFORMATION 440

Created By: Goetz, Ryan MVSRevision Number: 100Last Edited By: Goetz, Ryan MVSDate: 3/8/2010Time: 4:40:55 PM 445File Name: Location 3 - 35k cfs - Global Stability_R-59.75-LU.gszDirectory: C:\Documents and Settings\B3ECGRPG\My Documents\White Ditch\Last Solved Date: 3/8/2010Last Solved Time: 4:42:13 PM

22.0PROJECT SETTINGS 450

Length(L) Units: feet

Time(t) Units: Seconds

Force(F) Units: lbf

Pressure(p) Units: psfStrength Units: psf 455

Unit Weight of Water: 62.4 pcfView: 2D

23.0ANALYSIS SETTINGS23.1 Top of Levee - S-Case (2)

Kind: SLOPE/W 460Method: Spencer

Settings

Apply Phreatic Correction: NoPWP Conditions Source: Piezometric LineUse Staged Rapid Drawdown: No 465

SlipSurface

Direction of movement: Left to RightUse Passive Mode: NoSlip Surface Option: BlockCritical slip surfaces saved: 1 470

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Optimize Critical Slip Surface Location: YesTension Crack

Tension Crack Option: (none)

FOS Distribution

FOS Calculation Option: Constant 475

Restrict Block Crossing: YesAdvanced

Number of Slices: 75Optimization Tolerance: 0.01Minimum Slip Surface Depth: 0.1 ft 480

Optimization Maximum Iterations: 5000

Optimization Convergence Tolerance: 1e-007

Starting Optimization Points: 8Ending Optimization Points: 16Complete Passes per Insertion: 1 485Driving Side Maximum Convex Angle: 5 °Resisting Side Maximum Convex Angle: 1 °

24.0MATERIALS24.1 Concrete

Model: Mohr-Coulomb 490Unit Weight: 0.001 pcfCohesion: 2e+005 psfPhi: 0 °

Phi-B: 0 °

Pore Water Pressure 495

Piezometric Line: 1

24.2 Layer 1 -ML - S Case

Model: Mohr-Coulomb

Unit Weight: 117 pcf

Cohesion: 0 psf 500Phi: 28 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

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24.3 Layer 2-SP - S Case 505

Model: Mohr-Coulomb

Unit Weight: 122 pcf

Cohesion: 0 psfPhi: 33 °Phi-B: 0 ° 510Pore Water Pressure

Piezometric Line: 1

24.4 Layer 3 - CL - S Case

Model: Mohr-Coulomb

Unit Weight: 105 pcf 515

Cohesion: 0 psfPhi: 23 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1 520

24.5 Layer 4 -ML - S Case

Model: Mohr-Coulomb

Unit Weight: 117 pcf

Cohesion: 0 psfPhi: 28 ° 525Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

25.0SLIP SURFACE LIMITS

Left Coordinate: (-500, -16) ft 530Right Coordinate: (1000, -16) ft

26.0SLIP SURFACE BLOCK

Left Grid

Upper Left: (-87.8848, -30.20441) ftLower Left: (-87.8848, -135.18302) ft 535

Lower Right: (38.9764, -135.18302) ft

X Increments: 10Y Increments: 10

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Starting Angle: 115 °Ending Angle: 135 ° 540Angle Increments: 3

Right Grid

Upper Left: (524.8026, -30.69344) ft

Lower Left: (524.8026, -136.65011) ftLower Right: (627.3109, -136.65011) ft 545X Increments: 10Y Increments: 10Starting Angle: 0 °Ending Angle: 45 °Angle Increments: 3 550

27.0PIEZOMETRIC LINES27.1 Piezometric Line 1

27.1.1 Coordinates

X (ft) Y (ft)

-500 15

0 150 -20

534 -20534 -16534 0

1000 0

28.0 REGIONS

Material Points Area (ft2)

Region 1 Layer 1 -ML - S Case 1,2,3,4,5,6,11,7 35364Region 2 Layer 2-SP - S Case 7,11,12,8 63000Region 3 Layer 3 - CL - S Case 9,8,12,13 43500Region 4 Layer 4 -ML - S Case 10,9,13,14 57000

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Region 5 17,15,16,19,20,21,22,23,24,25,26 1182.5Region 6 Concrete 3,2,18,17,26,25,24,27,28,5,4 12973

29.0 POINTS 555

X (ft) Y (ft)

Point 1 -500 -16Point 2 0 -16Point 3 0 -20Point 4 534 -20Point 5 534 -16Point 6 1000 -16Point 7 -500 -41Point 8 -500 -83Point 9 -500 -112Point 10 -500 -150Point 11 1000 -41Point 12 1000 -83Point 13 1000 -112Point 14 1000 -150Point 15 260 15Point 16 275 15Point 17 235 7Point 18 0 7Point 19 310 6Point 20 325 5

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Point 21 335 6Point 22 340 7Point 23 407 7Point 24 435 2Point 25 245 2Point 26 245 7Point 27 534 2Point 28 534 -2Point 29 0 15Point 30 -500 15

30.0 CRITICAL SLIP SURFACES

Slip Surface FOS Center (ft) Radius (ft) Entry (ft) Exit (ft)

1 Optimized 10.228 (271.193, -16) 214.4399 (-36.4704, -16) (578.855, -16)2 3131 10.228 (271.193, -16) 214.44 (-36.4704, -16) (578.855, -16)

30.1 Slices of Slip Surface: Optimized

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 Optimized -32.353305 -20.117045 2191.286 2363.3806 91.504308 02 Optimized -24.119215 -28.351135 2705.0794 3288.6036 310.26535 03 Optimized -15.885125 -36.585225 3218.9586 4213.8266 528.98074 04 Optimized -5.88404 -40.708585 3476.1801 4826.4417 717.94683 05 Optimized 4.051724 -40.71925 1292.9056 2360.9688 567.89928 06 Optimized 12.155174 -40.727945 1293.3992 2426.1262 602.28163 07 Optimized 20.25862 -40.73664 1294.0163 2427.2369 602.54409 08 Optimized 28.362065 -40.74534 1294.5099 2428.2241 602.80655 0

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9 Optimized 36.465515 -40.754035 1295.0035 2429.2113 603.06901 0

10 Optimized 44.568965 -40.76273 1295.6205 2430.1986 603.26586 011 Optimized 52.672415 -40.77143 1296.1141 2431.3092 603.59393 012 Optimized 60.775865 -40.780125 1296.7312 2432.2965 603.79078 013 Optimized 68.87931 -40.78882 1297.2248 2433.2837 604.05324 014 Optimized 76.982755 -40.797515 1297.7184 2434.2709 604.3157 015 Optimized 85.086205 -40.80621 1298.3354 2435.3816 604.57816 016 Optimized 93.189655 -40.81491 1298.829 2436.3688 604.84062 017 Optimized 101.29309 -40.823605 1299.4461 2437.356 605.03747 018 Optimized 109.39655 -40.8323 1299.9397 2438.3433 605.29993 019 Optimized 117.5 -40.841 1300.4333 2439.4539 605.628 020 Optimized 125.60345 -40.849695 1301.0503 2440.4411 605.82485 021 Optimized 133.7069 -40.85839 1301.5439 2441.4284 606.08731 022 Optimized 141.81035 -40.86709 1302.1609 2442.4156 606.28415 023 Optimized 149.9138 -40.875785 1302.6546 2443.5262 606.61223 024 Optimized 158.01725 -40.88448 1303.1482 2444.5135 606.87469 025 Optimized 166.1207 -40.89318 1303.7652 2445.5007 607.07154 026 Optimized 174.22415 -40.901875 1304.2588 2446.4879 607.334 027 Optimized 182.3276 -40.91057 1304.8758 2447.5986 607.59646 028 Optimized 190.43105 -40.919265 1305.3695 2448.5858 607.85892 029 Optimized 198.5345 -40.92796 1305.8631 2449.573 608.12138 030 Optimized 206.63795 -40.93666 1306.4801 2450.5603 608.31822 031 Optimized 214.7414 -40.945355 1306.9737 2451.6709 608.6463 032 Optimized 222.84485 -40.95405 1307.5907 2452.6581 608.84315 0

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33 Optimized 230.9483 -40.96275 1308.0843 2453.6454 609.10561 034 Optimized 240 -40.972465 1308.6987 2454.7975 609.39157 035 Optimized 248.75 -40.981855 1309.266 2455.8654 609.65771 036 Optimized 256.25 -40.989905 1309.7726 2456.7987 609.88457 037 Optimized 262.82985 -40.996965 1310.205 2457.7166 610.14273 038 Optimized 270.32985 -41.00501 1310.6668 2458.8117 745.61406 039 Optimized 279.375 -41.014715 1311.3135 2459.9986 745.9648 040 Optimized 288.125 -41.024105 1311.885 2461.1415 746.33589 041 Optimized 296.875 -41.033495 1312.4564 2462.2843 746.70698 042 Optimized 305.625 -41.042885 1313.0278 2463.4272 747.07807 043 Optimized 313.75 -41.051605 1313.626 2464.532 747.40713 044 Optimized 321.25 -41.059655 1314.1193 2465.4654 747.69287 045 Optimized 330 -41.069045 1314.6987 2466.6975 748.1168 046 Optimized 337.5 -41.077095 1315.2192 2467.5985 748.36387 047 Optimized 344.1875 -41.084275 1315.7007 2468.5358 748.65989 048 Optimized 352.5625 -41.093265 1316.1783 2469.6105 749.04759 049 Optimized 360.9375 -41.10225 1316.7753 2470.6851 749.35776 050 Optimized 369.3125 -41.111235 1317.3723 2471.8791 749.74547 051 Optimized 377.6875 -41.120225 1317.85 2472.9537 750.13317 052 Optimized 386.0625 -41.129215 1318.447 2474.0284 750.44334 053 Optimized 394.4375 -41.138205 1319.044 2475.103 750.7535 054 Optimized 402.8125 -41.14719 1319.641 2476.1776 751.06366 055 Optimized 411.66665 -41.15669 1320.2135 2477.3556 751.4569 056 Optimized 421 -41.16671 1320.7492 2478.6414 751.94396 0

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57 Optimized 430.33335 -41.176725 1321.3921 2479.8199 752.29185 058 Optimized 439.125 -41.18616 1322.0598 2480.9682 752.60391 059 Optimized 447.375 -41.195015 1322.5447 2482.0591 752.99749 060 Optimized 455.625 -41.203865 1323.1507 2483.15 753.31235 061 Optimized 463.875 -41.21272 1323.6356 2484.2409 753.70593 062 Optimized 472.125 -41.221575 1324.2416 2485.3318 754.0208 063 Optimized 480.375 -41.230425 1324.7265 2486.4227 754.41438 064 Optimized 488.625 -41.23928 1325.3325 2487.5136 754.72924 065 Optimized 496.875 -41.248135 1325.9386 2488.4833 754.96539 066 Optimized 505.125 -41.25699 1326.4234 2489.5742 755.35897 067 Optimized 513.375 -41.265845 1327.0295 2490.6652 755.67383 068 Optimized 521.625 -41.274695 1327.5143 2491.7561 756.06741 069 Optimized 529.875 -41.28355 1328.1204 2510.9076 768.11096 070 Optimized 534.5267 -41.288545 2576.4383 3960.0126 898.50362 071 Optimized 535.3038 -41.144555 2567.3885 4040.1996 956.45471 072 Optimized 539.8843 -38.5 2402.4 3711.3 695.95448 073 Optimized 548.54455 -33.5 2090.4 3110.9 542.60948 074 Optimized 557.2048 -28.5 1778.4 2510.5 389.26447 075 Optimized 565.86505 -23.5 1466.4 1910.1 235.91947 076 Optimized 574.5253 -18.5 1154.4 1309.8 82.627646 0

30.2 Slices of Slip Surface: 3131

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 3131 -32.353305 -20.117045 2191.286 2363.3806 91.504308 02 3131 -24.119215 -28.351135 2705.0794 3288.6036 310.26535 0

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3 3131 -15.885125 -36.585225 3218.9586 4213.8266 528.98074 04 3131 -5.88404 -40.708585 3476.1801 4826.4417 717.94683 05 3131 4.051724 -40.71925 1292.9056 2360.9688 567.89928 06 3131 12.155174 -40.727945 1293.3992 2426.1262 602.28163 07 3131 20.25862 -40.73664 1294.0163 2427.2369 602.54409 08 3131 28.362065 -40.74534 1294.5099 2428.2241 602.80655 09 3131 36.465515 -40.754035 1295.0035 2429.2113 603.06901 0

10 3131 44.568965 -40.76273 1295.6205 2430.1986 603.26586 011 3131 52.672415 -40.77143 1296.1141 2431.3092 603.59393 012 3131 60.775865 -40.780125 1296.7312 2432.2965 603.79078 013 3131 68.87931 -40.78882 1297.2248 2433.2837 604.05324 014 3131 76.982755 -40.797515 1297.7184 2434.2709 604.3157 015 3131 85.086205 -40.80621 1298.3354 2435.3816 604.57816 016 3131 93.189655 -40.81491 1298.829 2436.3688 604.84062 017 3131 101.29309 -40.823605 1299.4461 2437.356 605.03747 018 3131 109.39655 -40.8323 1299.9397 2438.3433 605.29993 019 3131 117.5 -40.841 1300.4333 2439.4539 605.628 020 3131 125.60345 -40.849695 1301.0503 2440.4411 605.82485 021 3131 133.7069 -40.85839 1301.5439 2441.4284 606.08731 022 3131 141.81035 -40.86709 1302.1609 2442.4156 606.28415 023 3131 149.9138 -40.875785 1302.6546 2443.5262 606.61223 024 3131 158.01725 -40.88448 1303.1482 2444.5135 606.87469 025 3131 166.1207 -40.89318 1303.7652 2445.5007 607.07154 026 3131 174.22415 -40.901875 1304.2588 2446.4879 607.334 0

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27 3131 182.3276 -40.91057 1304.8758 2447.5986 607.59646 028 3131 190.43105 -40.919265 1305.3695 2448.5858 607.85892 029 3131 198.5345 -40.92796 1305.8631 2449.573 608.12138 030 3131 206.63795 -40.93666 1306.4801 2450.5603 608.31822 031 3131 214.7414 -40.945355 1306.9737 2451.6709 608.6463 032 3131 222.84485 -40.95405 1307.5907 2452.6581 608.84315 033 3131 230.9483 -40.96275 1308.0843 2453.6454 609.10561 034 3131 240 -40.972465 1308.6987 2454.7975 609.39157 035 3131 248.75 -40.981855 1309.266 2455.8654 609.65771 036 3131 256.25 -40.989905 1309.7726 2456.7987 609.88457 037 3131 262.82985 -40.996965 1310.205 2457.7166 610.14273 038 3131 270.32985 -41.00501 1310.6668 2458.8117 745.61406 039 3131 279.375 -41.014715 1311.3135 2459.9986 745.9648 040 3131 288.125 -41.024105 1311.885 2461.1415 746.33589 041 3131 296.875 -41.033495 1312.4564 2462.2843 746.70698 042 3131 305.625 -41.042885 1313.0278 2463.4272 747.07807 043 3131 313.75 -41.051605 1313.626 2464.532 747.40713 044 3131 321.25 -41.059655 1314.1193 2465.4654 747.69287 045 3131 330 -41.069045 1314.6987 2466.6975 748.1168 046 3131 337.5 -41.077095 1315.2192 2467.5985 748.36387 047 3131 344.1875 -41.084275 1315.7007 2468.5358 748.65989 048 3131 352.5625 -41.093265 1316.1783 2469.6105 749.04759 049 3131 360.9375 -41.10225 1316.7753 2470.6851 749.35776 050 3131 369.3125 -41.111235 1317.3723 2471.8791 749.74547 0

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51 3131 377.6875 -41.120225 1317.85 2472.9537 750.13317 052 3131 386.0625 -41.129215 1318.447 2474.0284 750.44334 053 3131 394.4375 -41.138205 1319.044 2475.103 750.7535 054 3131 402.8125 -41.14719 1319.641 2476.1776 751.06366 055 3131 411.66665 -41.15669 1320.2135 2477.3556 751.4569 056 3131 421 -41.16671 1320.7492 2478.6414 751.94396 057 3131 430.33335 -41.176725 1321.3921 2479.8199 752.29185 058 3131 439.125 -41.18616 1322.0598 2480.9682 752.60391 059 3131 447.375 -41.195015 1322.5447 2482.0591 752.99749 060 3131 455.625 -41.203865 1323.1507 2483.15 753.31235 061 3131 463.875 -41.21272 1323.6356 2484.2409 753.70593 062 3131 472.125 -41.221575 1324.2416 2485.3318 754.0208 063 3131 480.375 -41.230425 1324.7265 2486.4227 754.41438 064 3131 488.625 -41.23928 1325.3325 2487.5136 754.72924 065 3131 496.875 -41.248135 1325.9386 2488.4833 754.96539 066 3131 505.125 -41.25699 1326.4234 2489.5742 755.35897 067 3131 513.375 -41.265845 1327.0295 2490.6652 755.67383 068 3131 521.625 -41.274695 1327.5143 2491.7561 756.06741 069 3131 529.875 -41.28355 1328.1204 2510.9076 768.11096 070 3131 534.5267 -41.288545 2576.4383 3960.0126 898.50362 071 3131 535.3038 -41.144555 2567.3885 4040.1996 956.45471 072 3131 539.8843 -38.5 2402.4 3711.3 695.95448 073 3131 548.54455 -33.5 2090.4 3110.9 542.60948 074 3131 557.2048 -28.5 1778.4 2510.5 389.26447 0

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75 3131 565.86505 -23.5 1466.4 1910.1 235.91947 076 3131 574.5253 -18.5 1154.4 1309.8 82.627646 0

560

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Low Water S-Case

Report generated using GeoStudio 2007, version 7.15. Copyright © 1991-2009 GEO-SLOPE International Ltd.

31.0FILE INFORMATION 565

Created By: Goetz, Ryan MVSRevision Number: 98Last Edited By: Goetz, Ryan MVS

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Date: 3/8/2010Time: 4:56:57 PM 570File Name: Location 3 - 35k cfs - Global Stability_R-60.3-LU.gszDirectory: C:\Documents and Settings\B3ECGRPG\My Documents\White Ditch\Last Solved Date: 3/8/2010Last Solved Time: 4:58:20 PM

32.0PROJECT SETTINGS 575

Length(L) Units: feet

Time(t) Units: Seconds

Force(F) Units: lbf

Pressure(p) Units: psfStrength Units: psf 580

Unit Weight of Water: 62.4 pcfView: 2D

33.0ANALYSIS SETTINGS33.1 Low Water S-Case

Description: Active and Passive Wedge Method 585Kind: SLOPE/WMethod: Spencer

Settings

Apply Phreatic Correction: NoPWP Conditions Source: Piezometric Line 590

Use Staged Rapid Drawdown: No

SlipSurface

Direction of movement: Left to RightUse Passive Mode: NoSlip Surface Option: Block 595

Critical slip surfaces saved: 1Optimize Critical Slip Surface Location: YesTension Crack

Tension Crack Option: (none)

FOS Distribution 600

FOS Calculation Option: Constant

Restrict Block Crossing: YesAdvanced

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Number of Slices: 75Optimization Tolerance: 0.01 605Minimum Slip Surface Depth: 0.1 ftOptimization Maximum Iterations: 5000

Optimization Convergence Tolerance: 1e-007

Starting Optimization Points: 8Ending Optimization Points: 16 610Complete Passes per Insertion: 1Driving Side Maximum Convex Angle: 5 °Resisting Side Maximum Convex Angle: 1 °

34.0MATERIALS34.1 Concrete 615

Model: Mohr-Coulomb

Unit Weight: 0.001 pcfCohesion: 2e+005 psfPhi: 0 °

Phi-B: 0 ° 620Pore Water Pressure

Piezometric Line: 1

34.2 Layer 3 - SM - S Case

Model: Mohr-Coulomb

Unit Weight: 122 pcf 625

Cohesion: 0 psfPhi: 30 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1 630

34.3 Layer 4 - CL - S Case

Model: Mohr-Coulomb

Unit Weight: 105 pcf

Cohesion: 0 psfPhi: 23 ° 635Phi-B: 0 °

Pore Water Pressure

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Piezometric Line: 1

34.4 Layer 5 - ML - S Case

Model: Mohr-Coulomb 640Unit Weight: 117 pcf

Cohesion: 0 psfPhi: 28 °Phi-B: 0 °

Pore Water Pressure 645

Piezometric Line: 1

34.5 Layer 6 - CL - S Case

Model: Mohr-Coulomb

Unit Weight: 105 pcf

Cohesion: 0 psf 650Phi: 23 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

34.6 Layer 7 - CL - S Case 655

Model: Mohr-Coulomb

Unit Weight: 105 pcf

Cohesion: 0 psfPhi: 23 °Phi-B: 0 ° 660Pore Water Pressure

Piezometric Line: 1

34.7 Layer 8 - ML - S Case

Model: Mohr-Coulomb

Unit Weight: 117 pcf 665

Cohesion: 0 psfPhi: 28 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1 670

34.8 Layer 9 - CL - S Case

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Model: Mohr-Coulomb

Unit Weight: 105 pcf

Cohesion: 0 psfPhi: 23 ° 675Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

34.9 Layer 10 - SM - S Case

Model: Mohr-Coulomb 680Unit Weight: 122 pcf

Cohesion: 0 psfPhi: 30 °Phi-B: 0 °

Pore Water Pressure 685

Piezometric Line: 1

35.0SLIP SURFACE LIMITS

Left Coordinate: (-500, -15) ftRight Coordinate: (1000, -16) ft

36.0SLIP SURFACE BLOCK 690

Left Grid

Upper Left: (-99.2758, -24) ftLower Left: (-99.2758, -126) ftLower Right: (24.6802, -126) ftX Increments: 10 695

Y Increments: 10Starting Angle: 115 °Ending Angle: 135 °Angle Increments: 3

Right Grid 700

Upper Left: (528.863, -24) ftLower Left: (528.863, -126) ftLower Right: (629.013, -126) ftX Increments: 10Y Increments: 10 705Starting Angle: 0 °

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Ending Angle: 45 °Angle Increments: 3

37.0PIEZOMETRIC LINES37.1 Piezometric Line 1 710

37.1.1 Coordinates

X (ft) Y (ft)

-500 15

0 150 -20

534 -20534 0

1000 0

38.0 REGIONS

Material Points Area (ft2)

Region 1 Layer 10 - SM - S Case 17,18,12,8 28500Region 2 Layer 9 - CL - S Case 17,7,11,18 16500Region 3 Layer 8 - ML - S Case 7,6,10,11 16500Region 4 Layer 5 - ML - S Case 15,16,9,21 17250Region 5 Layer 4 - CL - S Case 5,15,21,20 8250Region 6 Layer 3 - SM - S Case 14,23,3,4,24,19,20,5 10364Region 7 Layer 6 - CL - S Case 16,25,26,9 13500Region 8 Layer 7 - CL - S Case 25,6,10,26 81000Region 9 29,27,28,31,32,33,34,35,36,37,38 1182.5Region 10 Concrete 3,23,22,2,30,29,38,37,36,39,40,24,4 12973

39.0 POINTS

X (ft) Y (ft)

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Point 1 -500 2Point 2 0 2Point 3 0 -20Point 4 534 -20Point 5 -500 -24Point 6 -500 -104Point 7 -500 -115Point 8 -500 -145Point 9 1000 -41Point 10 1000 -104Point 11 1000 -115Point 12 1000 -145Point 13 -500 -10Point 14 -500 -15Point 15 -500 -29.5Point 16 -500 -41Point 17 -500 -126Point 18 1000 -126Point 19 1000 -16Point 20 1000 -24Point 21 1000 -29.5Point 22 0 -10Point 23 0 -15Point 24 534 -16

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Point 25 -500 -50Point 26 1000 -50Point 27 260 15Point 28 275 15Point 29 235 7Point 30 0 7Point 31 310 6Point 32 325 5Point 33 335 6Point 34 340 7Point 35 407 7Point 36 435 2Point 37 245 2Point 38 245 7Point 39 534 2Point 40 534 -2Point 41 1000 -2Point 42 -500 15Point 43 0 15

40.0 CRITICAL SLIP SURFACES

Slip Surface FOS Center (ft) Radius (ft) Entry (ft) Exit (ft)

1 Optimized 5.114 (263.877, -14.75) 196.2609 (-19.311, -15) (547.063, -16)2 3480 5.114 (263.877, -14.75) 196.261 (-19.311, -15) (547.063, -16)

40.1 Slices of Slip Surface: Optimized 715

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Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 Optimized -14.811 -19.5 2152.8262 2347.8306 112.58582 02 Optimized -7.561 -26.75 2605.2384 3145.7251 229.42299 03 Optimized -2.4055 -31.85 2923.391 3669.6274 396.78092 04 Optimized 3.7903225 -34.2 886.08555 1541.1617 348.31019 05 Optimized 11.370967 -34.2 886.08555 1617.1447 388.71105 06 Optimized 18.951615 -34.2 886.08555 1617.1447 388.71105 07 Optimized 26.53226 -34.2 886.08555 1617.1447 388.71105 08 Optimized 34.112905 -34.2 886.08555 1617.1447 388.71105 09 Optimized 41.69355 -34.2 886.08555 1617.1447 388.71105 0

10 Optimized 49.274195 -34.2 886.08555 1617.1447 388.71105 011 Optimized 56.85484 -34.2 886.08555 1617.1447 388.71105 012 Optimized 64.435485 -34.2 886.08555 1617.1447 388.71105 013 Optimized 72.01613 -34.2 886.08555 1617.1447 388.71105 014 Optimized 79.596775 -34.2 886.08555 1617.1447 388.71105 015 Optimized 87.17742 -34.2 886.08555 1617.1447 388.71105 016 Optimized 94.758065 -34.2 886.08555 1617.1447 388.71105 017 Optimized 102.3387 -34.2 886.08555 1617.1447 388.71105 018 Optimized 109.91935 -34.2 886.08555 1617.1447 388.71105 019 Optimized 117.5 -34.2 886.08555 1617.1447 388.71105 020 Optimized 125.08065 -34.2 886.08555 1617.1447 388.71105 021 Optimized 132.6613 -34.2 886.08555 1617.1447 388.71105 022 Optimized 140.24195 -34.2 886.08555 1617.1447 388.71105 023 Optimized 147.8226 -34.2 886.08555 1617.1447 388.71105 0

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24 Optimized 155.4032 -34.2 886.08555 1617.1447 388.71105 025 Optimized 162.98385 -34.2 886.08555 1617.1447 388.71105 026 Optimized 170.5645 -34.2 886.08555 1617.1447 388.71105 027 Optimized 178.14515 -34.2 886.08555 1617.1447 388.71105 028 Optimized 185.7258 -34.2 886.08555 1617.1447 388.71105 029 Optimized 193.30645 -34.2 886.08555 1617.1447 388.71105 030 Optimized 200.8871 -34.2 886.08555 1617.1447 388.71105 031 Optimized 208.46775 -34.2 886.08555 1617.1447 388.71105 032 Optimized 216.0484 -34.2 886.08555 1617.1447 388.71105 033 Optimized 223.62905 -34.2 886.08555 1617.1447 388.71105 034 Optimized 231.2097 -34.2 886.08555 1617.1447 388.71105 035 Optimized 240 -34.2 886.08 1617.1 388.69023 036 Optimized 248.75 -34.2 886.08 1617.0667 388.67251 037 Optimized 256.25 -34.2 886.08 1617.0667 388.67251 038 Optimized 263.75 -34.2 886.08 1617.0667 388.67251 039 Optimized 271.25 -34.2 886.08 1617.0667 388.67251 040 Optimized 278.5 -34.2 886.08571 1617.1429 388.70998 041 Optimized 285.5 -34.2 886.08571 1617.1429 388.70998 042 Optimized 292.5 -34.2 886.08571 1617.1429 388.70998 043 Optimized 299.5 -34.2 886.08571 1617.1429 388.70998 044 Optimized 306.5 -34.2 886.08571 1617.1429 388.70998 045 Optimized 313.75 -34.2 886.08 1617.0667 388.67251 046 Optimized 321.25 -34.2 886.08 1617.0667 388.67251 047 Optimized 330 -34.2 886.08 1617.1 388.69023 0

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48 Optimized 337.5 -34.2 886.08 1617.1 388.69023 049 Optimized 343.7222 -34.2 886.08363 1617.0449 388.65898 050 Optimized 351.16665 -34.2 886.08363 1617.0449 388.65898 051 Optimized 358.6111 -34.2 886.08363 1617.0449 388.65898 052 Optimized 366.05555 -34.2 886.08363 1617.0449 388.65898 053 Optimized 373.5 -34.2 886.08363 1617.0449 388.65898 054 Optimized 380.94445 -34.2 886.08363 1617.0449 388.65898 055 Optimized 388.3889 -34.2 886.08363 1617.0449 388.65898 056 Optimized 395.83335 -34.2 886.08363 1617.0449 388.65898 057 Optimized 403.2778 -34.2 886.08363 1617.0449 388.65898 058 Optimized 410.5 -34.2 886.08571 1617.1429 388.70998 059 Optimized 417.5 -34.2 886.08571 1617.1429 388.70998 060 Optimized 424.5 -34.2 886.08571 1617.1429 388.70998 061 Optimized 431.5 -34.2 886.08571 1617.1429 388.70998 062 Optimized 438.91095 -34.2 886.07435 1617.1228 388.70534 063 Optimized 446.73285 -34.2 886.07435 1617.1228 388.70534 064 Optimized 454.5548 -34.2 886.07435 1617.1228 388.70534 065 Optimized 462.37675 -34.2 886.07435 1617.1228 388.70534 066 Optimized 470.19865 -34.2 886.07435 1617.1228 388.70534 067 Optimized 478.02055 -34.2 886.07435 1617.1228 388.70534 068 Optimized 485.84245 -34.2 886.07435 1617.1228 388.70534 069 Optimized 493.66435 -34.2 886.07435 1617.1228 388.70534 070 Optimized 501.4863 -34.2 886.07435 1617.1228 388.70534 071 Optimized 509.30825 -34.2 886.07435 1617.1228 388.70534 0

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72 Optimized 517.13015 -34.2 886.07435 1617.1228 388.70534 073 Optimized 524.95205 -34.2 886.07435 1617.1228 388.70534 074 Optimized 531.213 -31.85 739.43808 1447.4776 376.4713 075 Optimized 533.7815 -29.2815 579.16417 1562.3501 417.33766 076 Optimized 536.5315 -26.5315 1655.5489 2350.7845 295.10999 077 Optimized 543.063 -20 1248.0433 1556.165 177.89417 0

40.2 Slices of Slip Surface: 3480

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 3480 -14.811 -19.5 2152.8262 2347.8306 112.58582 02 3480 -7.561 -26.75 2605.2384 3145.7251 229.42299 03 3480 -2.4055 -31.85 2923.391 3669.6274 396.78092 04 3480 3.7903225 -34.2 886.08555 1541.1617 348.31019 05 3480 11.370967 -34.2 886.08555 1617.1447 388.71105 06 3480 18.951615 -34.2 886.08555 1617.1447 388.71105 07 3480 26.53226 -34.2 886.08555 1617.1447 388.71105 08 3480 34.112905 -34.2 886.08555 1617.1447 388.71105 09 3480 41.69355 -34.2 886.08555 1617.1447 388.71105 0

10 3480 49.274195 -34.2 886.08555 1617.1447 388.71105 011 3480 56.85484 -34.2 886.08555 1617.1447 388.71105 012 3480 64.435485 -34.2 886.08555 1617.1447 388.71105 013 3480 72.01613 -34.2 886.08555 1617.1447 388.71105 014 3480 79.596775 -34.2 886.08555 1617.1447 388.71105 015 3480 87.17742 -34.2 886.08555 1617.1447 388.71105 016 3480 94.758065 -34.2 886.08555 1617.1447 388.71105 0

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17 3480 102.3387 -34.2 886.08555 1617.1447 388.71105 018 3480 109.91935 -34.2 886.08555 1617.1447 388.71105 019 3480 117.5 -34.2 886.08555 1617.1447 388.71105 020 3480 125.08065 -34.2 886.08555 1617.1447 388.71105 021 3480 132.6613 -34.2 886.08555 1617.1447 388.71105 022 3480 140.24195 -34.2 886.08555 1617.1447 388.71105 023 3480 147.8226 -34.2 886.08555 1617.1447 388.71105 024 3480 155.4032 -34.2 886.08555 1617.1447 388.71105 025 3480 162.98385 -34.2 886.08555 1617.1447 388.71105 026 3480 170.5645 -34.2 886.08555 1617.1447 388.71105 027 3480 178.14515 -34.2 886.08555 1617.1447 388.71105 028 3480 185.7258 -34.2 886.08555 1617.1447 388.71105 029 3480 193.30645 -34.2 886.08555 1617.1447 388.71105 030 3480 200.8871 -34.2 886.08555 1617.1447 388.71105 031 3480 208.46775 -34.2 886.08555 1617.1447 388.71105 032 3480 216.0484 -34.2 886.08555 1617.1447 388.71105 033 3480 223.62905 -34.2 886.08555 1617.1447 388.71105 034 3480 231.2097 -34.2 886.08555 1617.1447 388.71105 035 3480 240 -34.2 886.08 1617.1 388.69023 036 3480 248.75 -34.2 886.08 1617.0667 388.67251 037 3480 256.25 -34.2 886.08 1617.0667 388.67251 038 3480 263.75 -34.2 886.08 1617.0667 388.67251 039 3480 271.25 -34.2 886.08 1617.0667 388.67251 040 3480 278.5 -34.2 886.08571 1617.1429 388.70998 0

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41 3480 285.5 -34.2 886.08571 1617.1429 388.70998 042 3480 292.5 -34.2 886.08571 1617.1429 388.70998 043 3480 299.5 -34.2 886.08571 1617.1429 388.70998 044 3480 306.5 -34.2 886.08571 1617.1429 388.70998 045 3480 313.75 -34.2 886.08 1617.0667 388.67251 046 3480 321.25 -34.2 886.08 1617.0667 388.67251 047 3480 330 -34.2 886.08 1617.1 388.69023 048 3480 337.5 -34.2 886.08 1617.1 388.69023 049 3480 343.7222 -34.2 886.08363 1617.0449 388.65898 050 3480 351.16665 -34.2 886.08363 1617.0449 388.65898 051 3480 358.6111 -34.2 886.08363 1617.0449 388.65898 052 3480 366.05555 -34.2 886.08363 1617.0449 388.65898 053 3480 373.5 -34.2 886.08363 1617.0449 388.65898 054 3480 380.94445 -34.2 886.08363 1617.0449 388.65898 055 3480 388.3889 -34.2 886.08363 1617.0449 388.65898 056 3480 395.83335 -34.2 886.08363 1617.0449 388.65898 057 3480 403.2778 -34.2 886.08363 1617.0449 388.65898 058 3480 410.5 -34.2 886.08571 1617.1429 388.70998 059 3480 417.5 -34.2 886.08571 1617.1429 388.70998 060 3480 424.5 -34.2 886.08571 1617.1429 388.70998 061 3480 431.5 -34.2 886.08571 1617.1429 388.70998 062 3480 438.91095 -34.2 886.07435 1617.1228 388.70534 063 3480 446.73285 -34.2 886.07435 1617.1228 388.70534 064 3480 454.5548 -34.2 886.07435 1617.1228 388.70534 0

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65 3480 462.37675 -34.2 886.07435 1617.1228 388.70534 066 3480 470.19865 -34.2 886.07435 1617.1228 388.70534 067 3480 478.02055 -34.2 886.07435 1617.1228 388.70534 068 3480 485.84245 -34.2 886.07435 1617.1228 388.70534 069 3480 493.66435 -34.2 886.07435 1617.1228 388.70534 070 3480 501.4863 -34.2 886.07435 1617.1228 388.70534 071 3480 509.30825 -34.2 886.07435 1617.1228 388.70534 072 3480 517.13015 -34.2 886.07435 1617.1228 388.70534 073 3480 524.95205 -34.2 886.07435 1617.1228 388.70534 074 3480 531.213 -31.85 739.43808 1447.4776 376.4713 075 3480 533.7815 -29.2815 579.16417 1562.3501 417.33766 076 3480 536.5315 -26.5315 1655.5489 2350.7845 295.10999 077 3480 543.063 -20 1248.0433 1556.165 177.89417 0

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720

725

730

735 Plate L5.2

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745

750

Boring

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12x12 Concrete Pile Capacities

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Q-CASE CAPACITY

-140

-120

-100

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-60

-40

-20

0

20

0 50 100 150 200 250

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Elevation (ft)

Compression

Tension

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-140

-120

-100

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-60

-40

-20

0

20

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Tension

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770

775

780

Boring

R-60.3-UL

12x12 Concrete Pile Capacities

785

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-140

-120

-100

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-60

-40

-20

0

20

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0

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795

800

805

Boring

810 R-59.75-LU

14x14 Concrete Pile Capacities

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Q-CASE CAPACITY

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-120

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-40

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20

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830

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Boring

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840 14x14 Concrete Pile Capacities

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850

855

860

865 Boring

R-59.75-LU

HP14x73 Steel Pile Capacities

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Q-CASE CAPACITY

-140

-120

-100

-80

-60

-40

-20

0

20

0 50 100 150 200 250 300 350 400

Capacity (Tons)

Elevation (ft)

Compression

Tension

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870

S-CASE CAPACITY

-140

-120

-100

-80

-60

-40

-20

0

20

0 50 100 150 200 250 300 350 400 450

Capacity (Tons)

Elevation (ft)

Compression

Tension

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875

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885

890

Boring

R-60.3-LU

HP14x73 Steel Pile Capacities

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Q-CASE CAPACITY

-140

-120

-100

-80

-60

-40

-20

0

20

0 50 100 150 200 250 300

Capacity (Tons)

Elevation (ft)

Compression

Tension

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S-CASE CAPACITY

-140

-120

-100

-80

-60

-40

-20

0

20

0 50 100 150 200 250 300 350

Capacity (Tons)

Elevation (ft)

Compression

Tension

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910

915

920 Plate L5.3

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930

935

Boring

R-59.75-LU

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945

950

955

960

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Low Water (hurricane condition)

Report generated using GeoStudio 2007, version 7.15. Copyright © 1991-2009 GEO-SLOPE International Ltd.

41.0FILE INFORMATION 970

Created By: Goetz, Ryan MVSRevision Number: 76Last Edited By: Goetz, Ryan MVSDate: 3/5/2010Time: 2:46:08 PM 975File Name: Location 3 - 35k cfs - MC_R-59.75-LU_1on3.5 Slope.gszDirectory: C:\Documents and Settings\B3ECGRPG\My Documents\White Ditch\Last Solved Date: 3/5/2010Last Solved Time: 2:47:01 PM

42.0PROJECT SETTINGS 980

Length(L) Units: feet

Time(t) Units: Seconds

Force(F) Units: lbf

Pressure(p) Units: psfStrength Units: psf 985

Unit Weight of Water: 62.4 pcfView: 2D

43.0ANALYSIS SETTINGS43.1 Low Water (hurricane condition)

Kind: SLOPE/W 990Method: Spencer

Settings

Apply Phreatic Correction: NoPWP Conditions Source: Piezometric LineUse Staged Rapid Drawdown: No 995

SlipSurface

Direction of movement: Left to RightUse Passive Mode: NoSlip Surface Option: Block

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Critical slip surfaces saved: 1 000Optimize Critical Slip Surface Location: YesTension Crack

Tension Crack Option: (none)

FOS Distribution

FOS Calculation Option: Constant 005

Restrict Block Crossing: YesAdvanced

Number of Slices: 75Optimization Tolerance: 0.01Minimum Slip Surface Depth: 0.1 ft 010

Optimization Maximum Iterations: 5000

Optimization Convergence Tolerance: 1e-007

Starting Optimization Points: 8Ending Optimization Points: 16Complete Passes per Insertion: 1 015Driving Side Maximum Convex Angle: 5 °Resisting Side Maximum Convex Angle: 1 °

44.0MATERIALS44.1 Layer 1 - ML

Model: Mohr-Coulomb 020Unit Weight: 117 pcf

Cohesion: 200 psf

Phi: 15 °Phi-B: 0 °

Pore Water Pressure 025

Piezometric Line: 1

44.2 Layer 2 - SP

Model: Mohr-Coulomb

Unit Weight: 122 pcf

Cohesion: 0 psf 030Phi: 33 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

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44.3 Layer 3 - CL 035

Model: Mohr-Coulomb

Unit Weight: 105 pcf

Cohesion: 1580 psfPhi: 0 °

Phi-B: 0 ° 040

Pore Water Pressure

Piezometric Line: 1

44.4 Layer 4 - ML

Model: Mohr-Coulomb

Unit Weight: 117 pcf 045

Cohesion: 200 psf

Phi: 15 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1 050

45.0SLIP SURFACE LIMITS

Left Coordinate: (-200, 2) ft

Right Coordinate: (300, -16) ft

46.0SLIP SURFACE BLOCK

Left Grid 055

Upper Left: (5, -16) ft

Lower Left: (25, -83) ftLower Right: (55, -83) ftX Increments: 10Y Increments: 10 060

Starting Angle: 115 °Ending Angle: 135 °Angle Increments: 3

Right Grid

Upper Left: (50, -16) ft 065

Lower Left: (113, -83) ftLower Right: (143, -83) ftX Increments: 10Y Increments: 10

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Starting Angle: 0 ° 070Ending Angle: 45 °Angle Increments: 3

47.0PIEZOMETRIC LINES47.1 Piezometric Line 1

47.1.1 Coordinates 075

X (ft) Y (ft)

-200 2

-2 2

43 050 -2

300 -2

48.0 REGIONS

Material Points Area (ft2)

Region 1 Layer 1 - ML 1,2,3,4,25,7,8,5,6,13,9 17411Region 2 Layer 2 - SP 9,13,14,23,22,21,24,10 21000Region 3 Layer 3 - CL 11,10,24,21,22,23,14,15 14500Region 4 Layer 4 - ML 12,11,15,16 19000

49.0 POINTS

X (ft) Y (ft)

Point 1 -200 2Point 2 -2 2Point 3 12 6Point 4 22 6Point 5 99 -16Point 6 300 -16

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Point 7 43 0Point 8 50 -2Point 9 -200 -41Point 10 -200 -83Point 11 -200 -112Point 12 -200 -150Point 13 300 -41Point 14 300 -83Point 15 300 -112Point 16 300 -150Point 17 36 -16Point 18 50 -16Point 19 80 -16Point 20 6 -16Point 21 56 -83Point 22 113 -83Point 23 143 -83Point 24 26 -83Point 25 29 4

50.0 CRITICAL SLIP SURFACES

Slip Surface FOS Center (ft) Radius (ft) Entry (ft) Exit (ft)

1 Optimized 1.844 (56.457, 9.639) 44.17684 (7.41969, 4.69134) (98.9963, -15.9989)2 3678 1.973 (56.457, 9.639) 44.081 (6.78889, 4.51111) (99.3047, -16)

50.1 Slices of Slip Surface: Optimized

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Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 Optimized 8.1455825 3.881579 -145.54597 7.2864937 1.9524101 2002 Optimized 9.597375 2.262059 -48.515322 195.39003 52.354602 2003 Optimized 11.161635 0.51708 56.031921 404.58431 93.39433 2004 Optimized 12.248425 -0.6952645 128.66829 547.27083 112.16421 2005 Optimized 13.06283 -1.6159035 183.8568 634.71523 120.80715 2006 Optimized 14.194795 -2.902931 261.02729 762.31172 134.31876 2007 Optimized 15.326765 -4.189959 338.19779 889.96655 147.84599 2008 Optimized 16.45873 -5.4769865 415.37412 1017.563 161.35603 2009 Optimized 17.64662 -6.708378 488.91753 1190.4811 187.98338 200

10 Optimized 18.89044 -7.8841335 558.83551 1309.9615 201.26361 20011 Optimized 20.134265 -9.059889 628.77685 1429.5004 214.55323 20012 Optimized 21.37809 -10.235644 698.65393 1548.9809 227.84441 20013 Optimized 22.56526 -11.357845 765.3991 1647.5976 236.38437 20014 Optimized 23.695775 -12.426495 828.97344 1725.3138 240.17368 20015 Optimized 24.8534 -13.37356 884.85524 1882.0401 267.19487 20016 Optimized 26.038145 -14.19904 933.05586 1934.7422 268.40104 20017 Optimized 27.22289 -15.024525 981.25647 1987.4443 269.60721 20018 Optimized 28.40763 -15.85001 1029.5263 2040.1464 270.79483 20019 Optimized 29.73613 -16.775655 1083.5982 2099.2626 272.14644 20020 Optimized 31.10362 -17.584995 1130.2679 2244.6216 298.59017 20021 Optimized 32.366345 -18.177865 1163.8168 2270.8586 296.63094 20022 Optimized 33.62907 -18.770735 1197.294 2297.0955 294.69092 20023 Optimized 34.891795 -19.363605 1230.7712 2323.3325 292.7509 200

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24 Optimized 36.15452 -19.956475 1264.2484 2349.5694 290.81088 20025 Optimized 37.3735 -20.434415 1290.7076 2442.556 308.63684 20026 Optimized 38.548735 -20.797425 1310.1381 2446.1331 304.38895 20027 Optimized 39.72397 -21.160435 1329.4873 2449.629 300.14105 20028 Optimized 40.899205 -21.523445 1348.9179 2453.2062 295.89316 20029 Optimized 42.07444 -21.886455 1368.2671 2456.702 291.64526 20030 Optimized 42.83103 -22.096955 1379.3204 2526.6639 307.42977 20031 Optimized 43.62076 -22.232465 1376.2422 2516.3893 305.5015 20032 Optimized 44.86228 -22.445495 1367.4303 2500.1945 303.52325 20033 Optimized 46.103795 -22.65853 1358.539 2483.9203 301.545 20034 Optimized 47.34531 -22.871565 1349.7271 2467.7255 299.56675 20035 Optimized 48.474555 -23.011175 1338.3154 2503.1473 312.11577 20036 Optimized 49.49152 -23.077365 1324.2837 2477.0463 308.88182 20037 Optimized 50.63841 -23.15201 1319.8689 2459.2015 305.28325 20038 Optimized 51.91523 -23.23511 1325.1053 2449.6667 301.32533 20039 Optimized 53.19205 -23.31821 1330.2634 2440.1319 297.38836 20040 Optimized 54.495005 -23.37417 1333.7596 2450.0527 299.10983 20041 Optimized 55.824095 -23.40299 1335.5649 2433.2029 294.11122 20042 Optimized 57.15318 -23.431815 1337.3702 2416.4285 289.13278 20043 Optimized 58.482265 -23.46064 1339.1756 2399.5788 284.13418 20044 Optimized 59.811355 -23.48946 1340.9057 2382.7291 279.15573 20045 Optimized 61.08876 -23.479885 1340.3117 2393.9086 282.31046 20046 Optimized 62.314475 -23.431915 1337.3769 2369.2888 276.49998 20047 Optimized 63.54019 -23.383945 1334.3605 2344.5875 270.68951 200

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48 Optimized 64.76591 -23.33598 1331.3442 2319.9677 264.90088 20049 Optimized 65.99163 -23.288015 1328.4094 2295.3479 259.0904 20050 Optimized 67.217345 -23.240045 1325.393 2270.7281 253.30177 20051 Optimized 68.44306 -23.192075 1322.3767 2246.1083 247.51314 20052 Optimized 69.66708 -23.10344 1316.8525 2249.6976 249.95509 20053 Optimized 70.889405 -22.974145 1308.7981 2214.9579 242.80479 20054 Optimized 72.11173 -22.84485 1300.7437 2180.2182 235.6545 20055 Optimized 73.33405 -22.71555 1292.6893 2145.4786 228.5042 20056 Optimized 74.556375 -22.586255 1284.5535 2110.7389 221.37571 20057 Optimized 75.7787 -22.45696 1276.4992 2075.9993 214.22542 20058 Optimized 77.04339 -22.27818 1265.3334 2066.5579 214.68747 20059 Optimized 78.350455 -22.049925 1251.0891 2017.871 205.4586 20060 Optimized 79.65752 -21.82167 1236.8447 1969.184 196.22972 20061 Optimized 80.96458 -21.59341 1222.6004 1920.4971 187.00085 20062 Optimized 82.271645 -21.365155 1208.3561 1871.8101 177.77197 20063 Optimized 83.57871 -21.1369 1194.1117 1823.1231 168.5431 20064 Optimized 84.89841 -20.848375 1176.1263 1803.1081 167.99926 20065 Optimized 86.230745 -20.499585 1154.3435 1738.1227 156.42317 20066 Optimized 87.56308 -20.150795 1132.6333 1673.1374 144.82762 20067 Optimized 88.895415 -19.802005 1110.8505 1608.152 133.25153 20068 Optimized 90.27097 -19.39268 1085.2736 1560.9339 127.45279 20069 Optimized 91.689745 -18.922825 1055.9672 1478.3005 113.16388 20070 Optimized 93.10852 -18.45297 1026.6608 1395.6672 98.874968 20071 Optimized 94.46521 -17.940655 994.70555 1341.326 92.87667 200

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72 Optimized 95.759805 -17.38588 960.05771 1248.1034 77.181616 20073 Optimized 97.0544 -16.831105 925.48086 1154.9518 61.486562 20074 Optimized 98.348995 -16.27633 890.83302 1061.7293 45.791508 200

50.2 Slices of Slip Surface: 3678 080

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 3678 7.548062 3.751938 -135.80059 19.260306 5.1607834 2002 3678 9.066408 2.233592 -45.266865 205.27964 55.004515 2003 3678 10.369186 0.93081415 32.413339 368.09305 89.945108 2004 3678 11.456395 -0.15639535 97.239367 507.69863 109.98223 2005 3678 12.625 -1.325 166.92245 640.75186 126.96221 2006 3678 13.875 -2.575 241.4515 767.23912 140.88437 2007 3678 15.125 -3.825 315.98621 893.66981 154.78985 2008 3678 16.375 -5.075 390.52092 1020.1571 168.7105 2009 3678 17.625 -6.325 465.05563 1146.6443 182.63114 200

10 3678 18.875 -7.575 539.58469 1273.1316 196.5533 20011 3678 20.125 -8.825 614.10808 1399.6188 210.47697 20012 3678 21.375 -10.075 688.66542 1526.0495 224.3764 20013 3678 22.583335 -11.283335 760.70539 1632.4467 233.58239 20014 3678 23.75 -12.45 830.28469 1718.7542 238.06468 20015 3678 24.916665 -13.616665 899.80338 1805.001 242.54697 20016 3678 26.083335 -14.783335 969.38268 1891.3084 247.02925 20017 3678 27.25 -15.95 1038.962 1977.5552 251.4953 20018 3678 28.416665 -17.116665 1108.5413 2063.8626 255.97759 20019 3678 29.625 -18.325 1180.5855 2153.2249 260.61797 200

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20 3678 30.875 -19.575 1255.0862 2245.6579 265.42289 20021 3678 32.125 -20.825 1329.6436 2338.0909 270.21266 20022 3678 33.375 -22.075 1404.2009 2430.5239 275.00243 20023 3678 34.642855 -22.7 1439.667 2968.234 409.57829 20024 3678 35.92857 -22.7 1436.0892 2924.6784 398.86628 20025 3678 37.214285 -22.7 1432.5114 2881.1229 388.15426 20026 3678 38.5 -22.7 1428.9337 2837.5673 377.44225 20027 3678 39.785715 -22.7 1425.3559 2794.0117 366.73023 20028 3678 41.07143 -22.7 1421.8559 2750.4562 355.99738 20029 3678 42.357145 -22.7 1418.2781 2706.9006 345.28536 20030 3678 43.583335 -22.7 1406.0567 2665.4564 337.45512 20031 3678 44.75 -22.7 1385.3139 2626.1992 332.49423 20032 3678 45.916665 -22.7 1364.4853 2586.9421 327.55631 20033 3678 47.083335 -22.7 1343.6568 2547.685 322.61839 20034 3678 48.25 -22.7 1322.9139 2508.4279 317.6575 20035 3678 49.416665 -22.7 1302.0853 2469.1707 312.71959 20036 3678 50.6075 -22.7 1291.6872 2440.2469 307.75564 20037 3678 51.8225 -22.7 1291.6872 2421.6461 302.77156 20038 3678 53.0375 -22.7 1291.6872 2403.1276 297.80954 20039 3678 54.2525 -22.7 1291.6872 2384.5267 292.82546 20040 3678 55.4675 -22.7 1291.6872 2366.0082 287.86344 20041 3678 56.6825 -22.7 1291.6872 2347.4074 282.87937 20042 3678 57.8975 -22.7 1291.6872 2328.8889 277.91734 20043 3678 59.1125 -22.7 1291.6872 2310.2881 272.93327 200

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44 3678 60.3275 -22.7 1291.6872 2291.6872 267.94919 20045 3678 61.5425 -22.7 1291.6872 2273.1687 262.98717 20046 3678 62.7575 -22.7 1291.6872 2254.5679 258.00309 20047 3678 63.9725 -22.7 1291.6872 2236.0494 253.04107 20048 3678 65.1875 -22.7 1291.6872 2217.4486 248.057 20049 3678 66.4025 -22.7 1291.6872 2198.93 243.09498 20050 3678 67.6175 -22.7 1291.6872 2180.3292 238.1109 20051 3678 68.8325 -22.7 1291.6872 2161.8107 233.14888 20052 3678 70.0475 -22.7 1291.6872 2143.2099 228.1648 20053 3678 71.2625 -22.7 1291.6872 2124.6091 223.18073 20054 3678 72.4775 -22.7 1291.6872 2106.0905 218.2187 20055 3678 73.6925 -22.7 1291.6872 2087.4897 213.23463 20056 3678 74.9175 -22.53454 1281.3574 2172.6684 238.82608 20057 3678 76.1525 -22.203625 1260.7093 2111.5844 227.9913 20058 3678 77.3875 -21.87271 1240.0611 2050.5003 217.15653 20059 3678 78.6225 -21.54179 1219.413 1989.3381 206.3008 20060 3678 79.8575 -21.21087 1198.7649 1928.254 195.46602 20061 3678 81.0925 -20.879955 1178.1167 1867.0917 184.61029 20062 3678 82.3275 -20.54904 1157.4686 1806.0077 173.77552 20063 3678 83.5625 -20.21812 1136.8205 1744.8454 162.91979 20064 3678 84.7975 -19.8872 1116.1723 1683.7613 152.08501 20065 3678 86.0325 -19.556285 1095.5242 1622.6773 141.25024 20066 3678 87.2675 -19.22537 1074.8761 1561.515 130.39451 20067 3678 88.5025 -18.89445 1054.2279 1500.431 119.55974 200

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68 3678 89.7375 -18.563535 1033.5798 1439.2687 108.70401 20069 3678 90.9725 -18.23262 1012.9317 1378.1846 97.869232 20070 3678 92.2075 -17.9017 992.28354 1317.0224 87.013502 20071 3678 93.4425 -17.57078 971.63541 1255.9383 76.178728 20072 3678 94.6775 -17.239865 950.98728 1194.8542 65.343954 20073 3678 95.9125 -16.90895 930.33915 1133.692 54.488224 20074 3678 97.1475 -16.57803 909.69101 1072.6079 43.65345 20075 3678 98.3825 -16.24711 889.04288 1011.4456 32.797719 20076 3678 99.15237 -16.040825 876.1595 947.00157 18.982075 200

085

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Low Water (non-hurricane condition) S-Case

Report generated using GeoStudio 2007, version 7.15. Copyright © 1991-2009 GEO-SLOPE International Ltd. 090

51.0FILE INFORMATION

Created By: Goetz, Ryan MVSRevision Number: 76Last Edited By: Goetz, Ryan MVSDate: 3/5/2010 095Time: 2:46:08 PMFile Name: Location 3 - 35k cfs - MC_R-59.75-LU_1on3.5 Slope.gszDirectory: C:\Documents and Settings\B3ECGRPG\My Documents\White Ditch\Last Solved Date: 3/5/2010Last Solved Time: 2:48:02 PM 100

52.0PROJECT SETTINGS

Length(L) Units: feet

Time(t) Units: Seconds

Force(F) Units: lbf

Pressure(p) Units: psf 105

Strength Units: psfUnit Weight of Water: 62.4 pcfView: 2D

53.0ANALYSIS SETTINGS53.1 Low Water (non-hurricane condition) S-Case 110

Kind: SLOPE/WMethod: Spencer

Settings

Apply Phreatic Correction: NoPWP Conditions Source: Piezometric Line 115

Use Staged Rapid Drawdown: No

SlipSurface

Direction of movement: Left to RightUse Passive Mode: NoSlip Surface Option: Block 120

Critical slip surfaces saved: 1

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Optimize Critical Slip Surface Location: YesTension Crack

Tension Crack Option: (none)

FOS Distribution 125

FOS Calculation Option: Constant

Restrict Block Crossing: YesAdvanced

Number of Slices: 75Optimization Tolerance: 0.01 130

Minimum Slip Surface Depth: 0.1 ftOptimization Maximum Iterations: 5000

Optimization Convergence Tolerance: 1e-007

Starting Optimization Points: 8Ending Optimization Points: 16 135Complete Passes per Insertion: 1Driving Side Maximum Convex Angle: 5 °Resisting Side Maximum Convex Angle: 1 °

54.0MATERIALS54.1 Layer 2 - SP 140

Model: Mohr-Coulomb

Unit Weight: 122 pcf

Cohesion: 0 psfPhi: 33 °Phi-B: 0 ° 145Pore Water Pressure

Piezometric Line: 1

54.2 Layer 1 - ML - S Case

Model: Mohr-Coulomb

Unit Weight: 117 pcf 150

Cohesion: 0 psfPhi: 28 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1 155

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54.3 Layer 3 - CL - S Case

Model: Mohr-Coulomb

Unit Weight: 105 pcf

Cohesion: 0 psfPhi: 23 ° 160Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

54.4 Layer 4 - ML - S Case

Model: Mohr-Coulomb 165Unit Weight: 117 pcf

Cohesion: 0 psfPhi: 28 °Phi-B: 0 °

Pore Water Pressure 170

Piezometric Line: 1

55.0SLIP SURFACE LIMITS

Left Coordinate: (-200, 2) ft

Right Coordinate: (300, -16) ft

56.0SLIP SURFACE BLOCK 175

Left Grid

Upper Left: (5.2803, -16.2114) ftLower Left: (25.2901, -82.6562) ftLower Right: (56.3051, -83.1814) ftX Increments: 10 180

Y Increments: 10Starting Angle: 115 °Ending Angle: 135 °Angle Increments: 3

Right Grid 185

Upper Left: (50.0021, -14.6356) ftLower Left: (112.8326, -83.1814) ft

Lower Right: (143.1473, -83.5754) ftX Increments: 10Y Increments: 10 190

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Starting Angle: 0 °Ending Angle: 45 °Angle Increments: 3

57.0PIEZOMETRIC LINES57.1 Piezometric Line 1 195

57.1.1 Coordinates

X (ft) Y (ft)

-200 2

-2 2

43 0

300 0

58.0 REGIONS

Material Points Area (ft2)

Region 1 Layer 1 - ML - S Case 1,2,3,4,25,7,8,5,6,13,9 17411Region 2 Layer 2 - SP 9,13,14,23,22,21,24,10 21000Region 3 Layer 3 - CL - S Case 11,10,24,21,22,23,14,15 14500Region 4 Layer 4 - ML - S Case 12,11,15,16 19000

59.0 POINTS

X (ft) Y (ft)

Point 1 -200 2Point 2 -2 2Point 3 12 6Point 4 22 6Point 5 99 -16Point 6 300 -16Point 7 43 0

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Point 8 50 -2Point 9 -200 -41Point 10 -200 -83Point 11 -200 -112Point 12 -200 -150Point 13 300 -41Point 14 300 -83Point 15 300 -112Point 16 300 -150Point 17 36 -16Point 18 50 -16Point 19 80 -16Point 20 6 -16Point 21 56 -83Point 22 113 -83Point 23 143 -83Point 24 26 -83Point 25 29 4

60.0 CRITICAL SLIP SURFACES

Slip Surface FOS Center (ft) Radius (ft) Entry (ft) Exit (ft)

1 Optimized 1.814 (58.624, 11.257) 39.36311 (13.6629, 6) (95.8818, -15.1091)2 1933 2.049 (58.624, 11.257) 39.345 (13.5587, 6) (95.6036, -15.0296)

60.1 Slices of Slip Surface: Optimized 200

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

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1 Optimized 14.171655 5.4559975 -260.50041 45.366879 24.121997 02 Optimized 15.189125 4.3679925 -195.43069 136.10064 72.365992 03 Optimized 16.2066 3.2799875 -130.36097 226.83439 120.60999 04 Optimized 17.224075 2.1919825 -65.294606 317.56815 168.85398 05 Optimized 17.991895 1.373968 -16.380069 387.1074 205.82865 06 Optimized 18.875815 0.43912265 39.503025 473.13687 230.5672 07 Optimized 20.12549 -0.88254435 118.50962 599.36534 255.67552 08 Optimized 21.375165 -2.2042115 197.51787 725.53884 280.75373 09 Optimized 22.38843 -3.2758525 261.57299 818.59072 296.17158 0

10 Optimized 23.306425 -4.1045975 310.74577 931.26639 329.93667 011 Optimized 24.365555 -4.9404725 359.96614 987.2239 333.51886 012 Optimized 25.424685 -5.7763475 409.18652 1043.1814 337.10106 013 Optimized 26.483815 -6.6122225 458.40689 1099.1389 340.68326 014 Optimized 27.510035 -7.324373 500.0013 1195.7381 369.92984 015 Optimized 28.503345 -7.912799 533.96355 1229.172 369.6489 016 Optimized 29.513105 -8.51097 568.48964 1263.2078 369.38822 017 Optimized 30.539315 -9.1188855 603.57642 1297.7497 369.09846 018 Optimized 31.565525 -9.7268015 638.6632 1332.2915 368.8087 019 Optimized 32.591735 -10.334715 673.74998 1366.8333 368.51895 020 Optimized 33.617945 -10.94263 708.83675 1401.3751 368.22919 021 Optimized 34.68081 -11.44973 737.53905 1497.2931 403.96838 022 Optimized 35.78033 -11.85601 759.83934 1508.4688 398.05335 023 Optimized 36.87985 -12.262285 782.13963 1519.5592 392.09296 024 Optimized 37.979375 -12.66856 804.43992 1530.735 386.17794 0

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25 Optimized 39.0789 -13.07484 826.74875 1541.8254 380.21301 026 Optimized 40.17842 -13.48112 849.04904 1553.0012 374.29798 027 Optimized 41.296135 -13.81673 866.85751 1604.8567 392.40111 028 Optimized 42.432045 -14.081665 880.23203 1598.6838 382.00759 029 Optimized 43.52619 -14.33686 894.61868 1601.9389 376.08882 030 Optimized 44.578575 -14.582315 909.93385 1614.6167 374.68651 031 Optimized 45.63096 -14.82777 925.24902 1627.2945 373.2842 032 Optimized 46.68334 -15.073225 940.56419 1639.9723 371.8819 033 Optimized 47.67461 -15.231855 950.46297 1705.1759 401.28796 034 Optimized 48.604765 -15.303665 954.9435 1699.602 395.94194 035 Optimized 49.53492 -15.37547 959.42404 1693.9209 390.53893 036 Optimized 50.19992 -15.426805 962.62197 1689.9496 386.72699 037 Optimized 50.958185 -15.454835 964.39129 1704.4264 393.48366 038 Optimized 52.074875 -15.48002 965.91326 1690.2811 385.15319 039 Optimized 53.191565 -15.505205 967.52476 1676.0462 376.72752 040 Optimized 54.33328 -15.54119 969.79123 1655.6847 364.69604 041 Optimized 55.500015 -15.587975 972.703 1643.3525 356.59067 042 Optimized 56.66675 -15.63476 975.61477 1631.0203 348.4853 043 Optimized 57.773945 -15.661875 977.30969 1629.9949 347.03887 044 Optimized 58.82159 -15.66932 977.78694 1614.7229 338.66487 045 Optimized 59.869235 -15.67676 978.26419 1599.3555 330.24012 046 Optimized 60.91688 -15.684205 978.74144 1583.9881 321.81537 047 Optimized 61.964525 -15.69165 979.12324 1568.6207 313.44137 048 Optimized 63.012175 -15.699095 979.60049 1553.3488 305.06737 0

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49 Optimized 64.05982 -15.706545 980.07773 1537.9814 296.64262 050 Optimized 65.107465 -15.71399 980.55498 1522.6139 288.21786 051 Optimized 66.15511 -15.72143 981.03223 1507.2465 279.79311 052 Optimized 67.202755 -15.728875 981.50948 1491.8791 271.36836 053 Optimized 68.27925 -15.727635 981.37309 1480.3825 265.328 054 Optimized 69.384595 -15.71771 980.73983 1461.9275 255.852 055 Optimized 70.48994 -15.70779 980.19703 1443.4724 246.3279 056 Optimized 71.595285 -15.697865 979.56377 1425.1079 236.9 057 Optimized 72.70063 -15.687935 978.93051 1406.6529 227.424 058 Optimized 73.805975 -15.67801 978.29725 1388.2883 217.9961 059 Optimized 74.915375 -15.660235 977.15541 1372.8481 210.39355 060 Optimized 76.028825 -15.63461 975.62903 1352.2868 200.27251 061 Optimized 77.14227 -15.608985 974.01286 1331.7255 190.19921 062 Optimized 78.255715 -15.58336 972.39668 1311.254 180.17365 063 Optimized 79.369165 -15.557735 970.78051 1290.6927 170.10035 064 Optimized 80.475775 -15.527915 968.91845 1271.6543 160.96753 065 Optimized 81.57555 -15.4939 966.82811 1250.2965 150.72282 066 Optimized 82.675325 -15.459885 964.73777 1228.9387 140.47812 067 Optimized 83.775095 -15.425875 962.55654 1207.49 130.23341 068 Optimized 84.874865 -15.391865 960.4662 1186.1321 119.9887 069 Optimized 85.97464 -15.35785 958.28498 1164.6834 109.744 070 Optimized 87.074415 -15.323835 956.19463 1143.3256 99.499292 071 Optimized 88.174895 -15.291735 954.24057 1121.5413 88.955381 072 Optimized 89.27609 -15.261545 952.33427 1100.572 78.819391 0

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73 Optimized 90.37729 -15.231355 950.42796 1079.6027 68.6834 074 Optimized 91.478485 -15.201165 948.52166 1058.7241 58.595677 075 Optimized 92.51067 -15.176445 947.01519 1038.4335 48.607955 076 Optimized 93.47385 -15.1572 945.81109 1020.9947 39.975862 077 Optimized 94.437035 -15.137955 944.60699 1003.5976 31.365846 078 Optimized 95.40022 -15.11871 943.40289 986.21076 22.76135 0

60.2 Slices of Slip Surface: 1933

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 1933 14.172415 5.3862865 -256.15781 53.095785 28.23153 02 1933 15.39984 4.15886 -182.96575 159.28851 84.695202 03 1933 16.627265 2.9314335 -109.77945 265.47893 141.15765 04 1933 17.854695 1.7040065 -36.593726 371.66934 197.6201 05 1933 19.057005 0.50169418 35.095918 481.58077 237.40021 06 1933 20.2342 -0.67550332 105.29136 595.21543 260.49725 07 1933 21.4114 -1.852701 175.47959 708.85008 283.59812 08 1933 22.583335 -3.0246335 245.35795 807.55626 298.92615 09 1933 23.75 -4.1913 314.92512 891.3181 306.47358 0

10 1933 24.916665 -5.3579665 384.48624 975.07994 314.02424 011 1933 26.083335 -6.5246335 454.05342 1058.9024 321.6039 012 1933 27.25 -7.6913 523.61454 1142.6642 329.15456 013 1933 28.416665 -8.8579665 593.18171 1226.4261 336.702 014 1933 29.521095 -9.962395 659.03236 1305.7434 343.86238 015 1933 30.56328 -11.00458 721.16119 1380.5803 350.61935 016 1933 31.605465 -12.046765 783.31037 1455.4171 357.3655 0

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17 1933 32.64765 -13.08895 845.45955 1530.254 364.11165 018 1933 33.689835 -14.131135 907.60873 1605.0908 370.8578 019 1933 34.73202 -15.17332 969.75791 1679.9276 377.60395 020 1933 35.774205 -16.215505 1031.9071 1754.7645 384.3501 021 1933 36.854025 -16.714935 1060.1007 2221.2485 617.39325 022 1933 37.971475 -16.671605 1054.2882 2176.9845 596.94819 023 1933 39.088925 -16.628275 1048.4758 2132.7205 576.50313 024 1933 40.206375 -16.584945 1042.6634 2088.4565 556.05807 025 1933 41.323825 -16.541615 1036.8509 2044.1925 535.61301 026 1933 42.441275 -16.498285 1031.0385 1999.9285 515.16795 027 1933 43.583335 -16.454 1026.7716 1965.9233 499.35582 028 1933 44.75 -16.40876 1023.9452 1942.1126 488.1983 029 1933 45.916665 -16.36352 1021.1187 1918.3876 477.08633 030 1933 47.083335 -16.31828 1018.2923 1894.6626 465.97435 031 1933 48.25 -16.27304 1015.4658 1870.8519 454.81683 032 1933 49.416665 -16.2278 1012.6394 1847.1268 443.70486 033 1933 50.54137 -16.184185 1009.9146 1824.1772 432.95113 034 1933 51.624115 -16.1422 1007.2382 1802.2125 422.69535 035 1933 52.70686 -16.100215 1004.6541 1780.1555 412.34142 036 1933 53.7896 -16.05823 1002.07 1758.0986 401.9875 037 1933 54.87234 -16.016245 999.39366 1736.0416 391.68264 038 1933 55.955085 -15.97426 996.80958 1713.9846 381.32872 039 1933 57.03783 -15.932275 994.13321 1691.9276 371.02386 040 1933 58.12057 -15.89029 991.54913 1669.8706 360.66993 0

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41 1933 59.203315 -15.848305 988.96505 1647.8136 350.31601 042 1933 60.28606 -15.80632 986.28868 1625.8489 340.06022 043 1933 61.3688 -15.764335 983.7046 1603.792 329.7063 044 1933 62.45154 -15.72235 981.12051 1581.735 319.35237 045 1933 63.534285 -15.680365 978.44414 1559.678 309.04752 046 1933 64.61703 -15.63838 975.86006 1537.621 298.69359 047 1933 65.69977 -15.596395 973.18369 1515.564 288.38874 048 1933 66.782515 -15.55441 970.59961 1493.507 278.03481 049 1933 67.86526 -15.512425 968.01553 1471.45 267.68088 050 1933 68.948 -15.47044 965.33916 1449.4854 257.4251 051 1933 70.03074 -15.428455 962.75507 1427.4284 247.07117 052 1933 71.113485 -15.38647 960.0787 1405.3714 236.76632 053 1933 72.19623 -15.344485 957.49462 1383.3144 226.41239 054 1933 73.27897 -15.3025 954.91054 1361.2574 216.05847 055 1933 74.361715 -15.260515 952.23417 1339.2004 205.75361 056 1933 75.44446 -15.21853 949.65009 1317.1434 195.39968 057 1933 76.5272 -15.176545 946.97372 1295.0865 185.09483 058 1933 77.60994 -15.13456 944.38964 1273.1218 174.78997 059 1933 78.692685 -15.092575 941.80555 1251.0648 164.43605 060 1933 79.77543 -15.05059 939.12918 1229.0078 154.13119 061 1933 80.862755 -15.0296 937.80279 1200.4608 139.65776 062 1933 81.95467 -15.0296 937.80279 1183.6097 130.69785 063 1933 83.046585 -15.0296 937.80279 1166.7586 121.73794 064 1933 84.1385 -15.0296 937.80279 1149.8158 112.72933 0

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65 1933 85.230415 -15.0296 937.80279 1132.9647 103.76942 066 1933 86.32233 -15.0296 937.80279 1116.1135 94.809505 067 1933 87.414245 -15.0296 937.80279 1099.1708 85.800898 068 1933 88.506155 -15.0296 937.80279 1082.3197 76.840986 069 1933 89.59807 -15.0296 937.80279 1065.3769 67.832379 070 1933 90.689985 -15.0296 937.80279 1048.5258 58.872466 071 1933 91.7819 -15.0296 937.80279 1031.6747 49.912554 072 1933 92.873815 -15.0296 937.80279 1014.7319 40.903947 073 1933 93.96573 -15.0296 937.80279 997.88079 31.944035 074 1933 95.057645 -15.0296 937.80279 981.02964 22.984123 0

205

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Water at Project Grade (levee)

Report generated using GeoStudio 2007, version 7.15. Copyright © 1991-2009 GEO-SLOPE International Ltd.

61.0FILE INFORMATION 215

Created By: Goetz, Ryan MVSRevision Number: 76Last Edited By: Goetz, Ryan MVSDate: 3/5/2010Time: 2:46:08 PM 220File Name: Location 3 - 35k cfs - MC_R-59.75-LU_1on3.5 Slope.gszDirectory: C:\Documents and Settings\B3ECGRPG\My Documents\White Ditch\Last Solved Date: 3/5/2010Last Solved Time: 2:48:58 PM

62.0PROJECT SETTINGS 225

Length(L) Units: feet

Time(t) Units: Seconds

Force(F) Units: lbf

Pressure(p) Units: psfStrength Units: psf 230

Unit Weight of Water: 62.4 pcfView: 2D

63.0ANALYSIS SETTINGS63.1 Water at Project Grade (levee)

Kind: SLOPE/W 235Method: Spencer

Settings

Apply Phreatic Correction: NoPWP Conditions Source: Piezometric LineUse Staged Rapid Drawdown: No 240

SlipSurface

Direction of movement: Right to LeftUse Passive Mode: NoSlip Surface Option: BlockCritical slip surfaces saved: 1 245

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Optimize Critical Slip Surface Location: YesTension Crack

Tension Crack Option: (none)

FOS Distribution

FOS Calculation Option: Constant 250

Restrict Block Crossing: YesAdvanced

Number of Slices: 75Optimization Tolerance: 0.01Minimum Slip Surface Depth: 0.1 ft 255

Optimization Maximum Iterations: 5000

Optimization Convergence Tolerance: 1e-007

Starting Optimization Points: 8Ending Optimization Points: 16Complete Passes per Insertion: 1 260Driving Side Maximum Convex Angle: 5 °Resisting Side Maximum Convex Angle: 1 °

64.0MATERIALS64.1 Layer 1 - ML

Model: Mohr-Coulomb 265Unit Weight: 117 pcf

Cohesion: 200 psf

Phi: 15 °Phi-B: 0 °

Pore Water Pressure 270

Piezometric Line: 1

64.2 Layer 2 - SP

Model: Mohr-Coulomb

Unit Weight: 122 pcf

Cohesion: 0 psf 275Phi: 33 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

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64.3 Layer 3 - CL 280

Model: Mohr-Coulomb

Unit Weight: 105 pcf

Cohesion: 1580 psfPhi: 0 °

Phi-B: 0 ° 285

Pore Water Pressure

Piezometric Line: 1

64.4 Layer 4 - ML

Model: Mohr-Coulomb

Unit Weight: 117 pcf 290

Cohesion: 200 psf

Phi: 15 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1 295

65.0SLIP SURFACE LIMITS

Left Coordinate: (-200, 2) ft

Right Coordinate: (300, -16) ft

66.0SLIP SURFACE BLOCK

Left Grid 300

Upper Left: (-22, 0.75) ftLower Left: (-22, -44) ftLower Right: (3.25, -44) ftX Increments: 10Y Increments: 10 305Starting Angle: 135 °Ending Angle: 180 °Angle Increments: 3

Right Grid

Upper Left: (9.5, 0.75) ft 310

Lower Left: (9.5, -44) ftLower Right: (31.7145, -44) ftX Increments: 10Y Increments: 10

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Starting Angle: 45 ° 315Ending Angle: 65 °Angle Increments: 3

67.0PIEZOMETRIC LINES67.1 Piezometric Line 1

67.1.1 Coordinates 320

X (ft) Y (ft)

-200 2

-2 2

12 6

300 6

68.0 REGIONS

Material Points Area (ft2)

Region 1 Layer 1 - ML 1,2,3,4,25,7,8,5,6,13,9 17411Region 2 Layer 2 - SP 9,13,14,23,22,21,24,10 21000Region 3 Layer 3 - CL 11,10,24,21,22,23,14,15 14500Region 4 Layer 4 - ML 12,11,15,16 19000

69.0 POINTS

X (ft) Y (ft)

Point 1 -200 2Point 2 -2 2Point 3 12 6Point 4 22 6Point 5 99 -16Point 6 300 -16Point 7 43 0

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Point 8 50 -2Point 9 -200 -41Point 10 -200 -83Point 11 -200 -112Point 12 -200 -150Point 13 300 -41Point 14 300 -83Point 15 300 -112Point 16 300 -150Point 17 36 -16Point 18 50 -16Point 19 80 -16Point 20 6 -16Point 21 56 -83Point 22 113 -83Point 23 143 -83Point 24 26 -83Point 25 29 4

70.0 CRITICAL SLIP SURFACES

Slip Surface FOS Center (ft) Radius (ft) Entry (ft) Exit (ft)

1 Optimized 3.482 (4.595, 7) 13.00373 (19.7249, 6) (-7.62206, 2)2 3565 3.719 (4.595, 7) 13.359 (19.225, 6) (-9.19099, 2)

70.1 Slices of Slip Surface: Optimized

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

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1 Optimized -7.4328265 1.8498675 9.3682715 77.713247 18.312981 2002 Optimized -7.054362 1.5496025 28.105435 116.80998 23.768311 2003 Optimized -6.6758975 1.2493375 46.840322 155.90672 29.224252 2004 Optimized -6.2974325 0.9490725 65.577279 195.00345 34.679638 2005 Optimized -5.908756 0.654508 83.957735 226.37665 38.161032 2006 Optimized -5.509868 0.365644 101.98421 263.6357 43.314384 2007 Optimized -5.11098 0.07678 120.00866 300.87444 48.46284 2008 Optimized -4.712092 -0.212084 138.0331 338.11319 53.611296 2009 Optimized -4.313204 -0.500948 156.05958 375.37224 58.764649 200

10 Optimized -3.9253275 -0.77269125 173.01627 404.3591 61.988125 20011 Optimized -3.5484625 -1.0273138 188.90393 436.9875 66.473794 20012 Optimized -3.1715975 -1.281936 204.79378 469.59391 70.952982 20013 Optimized -2.7947325 -1.5365585 220.68144 502.20033 75.43276 20014 Optimized -2.454725 -1.7543395 234.26958 519.17336 76.339738 20015 Optimized -2.151575 -1.935278 245.56002 542.08848 79.454561 20016 Optimized -1.8355415 -2.123906 260.26415 571.93682 83.512442 20017 Optimized -1.506625 -2.3202235 278.37148 608.69449 88.509785 20018 Optimized -1.1777085 -2.516541 296.48925 645.47827 93.511326 20019 Optimized -0.82208 -2.695074 313.96675 653.80404 91.059129 20020 Optimized -0.43974 -2.8558215 330.81998 687.22118 95.497414 20021 Optimized -0.0574 -3.0165685 347.67321 720.6142 99.929238 20022 Optimized 0.32494 -3.177316 364.52644 754.03133 104.36752 20023 Optimized 0.695751 -3.30288 378.97243 755.40758 100.86549 20024 Optimized 1.055033 -3.39326 391.01101 778.75595 103.89594 200

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25 Optimized 1.414315 -3.48364 403.04959 802.13132 106.93362 20026 Optimized 1.773597 -3.57402 415.08818 825.50668 109.97131 20027 Optimized 2.132879 -3.6644 427.15375 848.88204 113.00176 20028 Optimized 2.501518 -3.725149 437.49293 840.78901 108.06286 20029 Optimized 2.879514 -3.756267 446.19375 857.2942 110.15403 20030 Optimized 3.25751 -3.787385 454.8682 873.77302 112.24521 20031 Optimized 3.635506 -3.818503 463.54265 890.27821 114.34345 20032 Optimized 4.013502 -3.849621 472.2171 906.75703 116.43462 20033 Optimized 4.3700325 -3.851335 478.6929 891.50381 110.61235 20034 Optimized 4.7050975 -3.823645 482.94623 899.38585 111.58466 20035 Optimized 5.0401625 -3.795955 487.16982 907.29764 112.57291 20036 Optimized 5.3752275 -3.768265 491.42315 915.20943 113.55319 20037 Optimized 5.7102925 -3.740575 495.67648 923.12122 114.53347 20038 Optimized 6.0453575 -3.712885 499.92981 931.03301 115.51375 20039 Optimized 6.408551 -3.649795 502.47085 908.12015 108.6934 20040 Optimized 6.799873 -3.551305 503.28864 909.6566 108.88597 20041 Optimized 7.191195 -3.452815 504.13121 911.16828 109.06525 20042 Optimized 7.582517 -3.354325 504.949 912.67995 109.25118 20043 Optimized 7.973839 -3.255835 505.79157 914.19163 109.43047 20044 Optimized 8.3715985 -3.1224835 504.54257 886.35857 102.30729 20045 Optimized 8.775796 -2.954271 501.25342 880.46551 101.60957 20046 Optimized 9.1799935 -2.786059 497.96426 874.57244 100.91186 20047 Optimized 9.584191 -2.6178465 494.67511 868.65653 100.20802 20048 Optimized 9.9767 -2.421651 489.44743 834.2715 92.395332 200

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49 Optimized 10.35752 -2.1974735 482.22871 821.59914 90.934033 20050 Optimized 10.738345 -1.9732965 475.03261 808.92678 89.466671 20051 Optimized 11.11917 -1.749119 467.83652 796.27704 88.005372 20052 Optimized 11.482185 -1.5021405 458.89045 755.15496 79.383836 20053 Optimized 11.827395 -1.232361 448.23131 736.73543 77.304445 20054 Optimized 12.186105 -0.95203195 433.79742 711.89602 74.516297 20055 Optimized 12.558315 -0.6611538 415.65549 680.60808 70.993832 20056 Optimized 12.93052 -0.37027555 397.51356 649.32013 67.471368 20057 Optimized 13.302725 -0.07939731 379.35046 618.03219 63.954575 20058 Optimized 13.674935 0.21148089 361.20854 586.74424 60.43211 20059 Optimized 14.035995 0.50915085 342.629 545.33463 54.31481 20060 Optimized 14.385905 0.8136125 323.63478 512.88707 50.709998 20061 Optimized 14.735815 1.1180742 304.64056 480.43951 47.105186 20062 Optimized 15.085725 1.422536 285.62478 447.99195 43.506151 20063 Optimized 15.435635 1.7269975 266.63056 415.54439 39.901339 20064 Optimized 15.785545 2.031459 247.63634 383.09683 36.296528 20065 Optimized 16.13198 2.34798 227.89379 342.00912 30.57711 20066 Optimized 16.47494 2.67656 207.3825 307.29026 26.770204 20067 Optimized 16.817895 3.00514 186.87964 272.59247 22.966682 20068 Optimized 17.16085 3.33372 166.37678 237.87361 19.157519 20069 Optimized 17.50381 3.6623 145.87181 203.16318 15.351176 20070 Optimized 17.84677 3.99088 125.36895 168.45275 11.54427 20071 Optimized 18.188915 4.339653 103.60628 124.17395 5.5110895 20072 Optimized 18.530245 4.708619 80.581561 85.670755 1.3636455 200

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73 Optimized 18.87157 5.077585 57.558826 47.167559 -2.7843316 20074 Optimized 19.212895 5.446551 34.536091 8.6631694 -6.9326286 20075 Optimized 19.554225 5.815517 11.511765 -29.840822 -11.080392 200

70.2 Slices of Slip Surface: 3565 325

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 3565 -9.0017545 1.890744 6.817487 53.457116 12.497051 2002 3565 -8.623281 1.6722325 20.45269 81.08494 16.246362 2003 3565 -8.2448075 1.453721 34.087435 108.71048 19.995183 2004 3565 -7.8663345 1.2352095 47.722867 136.3383 23.744434 2005 3565 -7.4878615 1.016698 61.358299 163.96384 27.493071 2006 3565 -7.1093885 0.7981862 74.99373 191.58937 31.241708 2007 3565 -6.730915 0.5796746 88.629162 219.21719 34.990958 2008 3565 -6.3524415 0.361163 102.26231 246.85188 38.742661 2009 3565 -5.9739685 0.14265137 115.89774 274.47055 42.489458 200

10 3565 -5.5954955 -0.07586028 129.53317 302.08923 46.236256 20011 3565 -5.2170225 -0.2943719 143.1686 329.73078 49.989185 20012 3565 -4.838549 -0.5128835 156.80403 357.34945 53.735983 20013 3565 -4.4600755 -0.7313951 170.43946 384.96812 57.48278 20014 3565 -4.0816025 -0.94990645 184.0749 412.60967 61.235709 20015 3565 -3.7031295 -1.168418 197.71033 440.22834 64.982507 20016 3565 -3.3246565 -1.38693 211.34347 467.84702 68.729918 20017 3565 -2.946183 -1.6054415 224.9789 495.48857 72.482847 20018 3565 -2.5677095 -1.823953 238.61433 523.10724 76.229644 20019 3565 -2.1892365 -2.042465 252.25205 550.72591 79.975829 200

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20 3565 -1.805357 -2.264098 269.5389 585.7955 84.740702 20021 3565 -1.4160715 -2.488852 290.51737 628.26412 90.498968 20022 3565 -1.026786 -2.713606 311.4736 670.73274 96.263196 20023 3565 -0.6375 -2.93836 332.45207 713.2236 102.02742 20024 3565 -0.24821426 -3.1631145 353.4083 755.69222 107.79165 20025 3565 0.14107144 -3.387869 374.36453 798.18308 113.56184 20026 3565 0.53035715 -3.612623 395.343 840.6517 119.32011 20027 3565 0.915761 -3.725 409.22967 774.2941 97.818718 20028 3565 1.2972825 -3.725 416.01828 787.08498 99.427024 20029 3565 1.678804 -3.725 422.83309 799.87587 101.02831 20030 3565 2.060326 -3.725 429.6217 812.66675 102.63661 20031 3565 2.441848 -3.725 436.43651 825.45763 104.2379 20032 3565 2.8233695 -3.725 443.22512 838.24852 105.8462 20033 3565 3.204891 -3.725 450.03993 851.0394 107.44748 20034 3565 3.586413 -3.725 456.82854 863.83029 109.05579 20035 3565 3.967935 -3.725 463.64335 876.62117 110.65707 20036 3565 4.3494565 -3.725 470.43196 889.41206 112.26538 20037 3565 4.730978 -3.725 477.24677 902.20294 113.86666 20038 3565 5.1125 -3.725 484.03538 914.99383 115.47497 20039 3565 5.494022 -3.725 490.85019 927.78471 117.07625 20040 3565 5.8755435 -3.725 497.6388 940.5756 118.68456 20041 3565 6.257065 -3.725 504.45361 953.36648 120.28584 20042 3565 6.638587 -3.725 511.24222 966.15736 121.89415 20043 3565 7.020109 -3.725 518.05703 978.94825 123.49543 200

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44 3565 7.4016305 -3.725 524.84564 991.73913 125.10373 20045 3565 7.783152 -3.725 531.66045 1004.53 126.70502 20046 3565 8.164674 -3.725 538.44906 1017.3209 128.31332 20047 3565 8.546196 -3.725 545.26387 1030.1118 129.91461 20048 3565 8.9277175 -3.725 552.07869 1042.9289 131.52291 20049 3565 9.309239 -3.725 558.86729 1055.7198 133.13122 20050 3565 9.6785715 -3.5464285 554.31229 890.51892 90.086295 20051 3565 10.035716 -3.1892855 538.3939 863.71109 87.168477 20052 3565 10.39286 -2.8321425 522.47552 836.92305 84.255964 20053 3565 10.75 -2.475 506.55713 810.11522 81.338147 20054 3565 11.10714 -2.1178575 490.63874 783.32719 78.425634 20055 3565 11.464285 -1.7607145 474.72035 756.53916 75.513122 20056 3565 11.82143 -1.4035715 458.80197 729.73133 72.595304 20057 3565 12.19013 -1.0348684 438.9768 696.3715 68.968703 20058 3565 12.570395 -0.65460525 415.24933 656.42902 64.623904 20059 3565 12.95066 -0.27434212 391.52186 616.48654 60.279105 20060 3565 13.33092 0.10592104 367.79438 576.54406 55.934306 20061 3565 13.711185 0.4861842 344.06691 536.60158 51.589507 20062 3565 14.09145 0.8664474 320.33944 496.65909 47.244708 20063 3565 14.47171 1.2467105 296.61197 456.71661 42.899909 20064 3565 14.851975 1.6269735 272.8845 416.77413 38.55511 20065 3565 15.23224 2.0072365 249.15703 376.83165 34.21031 20066 3565 15.6125 2.3875 225.41097 336.88917 29.870494 20067 3565 15.99276 2.7677635 201.6835 296.94669 25.525695 200

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68 3565 16.373025 3.1480265 177.96347 257.00421 21.178903 20069 3565 16.75329 3.5282895 154.23414 217.06172 16.834602 20070 3565 17.13355 3.9085525 130.50667 177.11552 12.488806 20071 3565 17.513815 4.2888155 106.77734 137.17304 8.1445053 20072 3565 17.89408 4.669079 83.049865 97.230562 3.7997062 20073 3565 18.27434 5.0493425 59.320535 57.28808 -0.54459466 20074 3565 18.654605 5.4296055 35.593065 17.345413 -4.8894436 20075 3565 19.03487 5.8098685 11.864293 -22.596882 -9.2338441 200

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330

335

340

345 Boring

R-60.3-UL

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350

Low Water (hurricane condition)

Report generated using GeoStudio 2007, version 7.15. Copyright © 1991-2009 GEO-SLOPE International Ltd.

71.0FILE INFORMATION 355

Created By: Goetz, Ryan MVSRevision Number: 74Last Edited By: Goetz, Ryan MVSDate: 3/5/2010Time: 10:57:29 AM 360File Name: Location 3 - 35k cfs - Main Channel_R-60.3-LU_1on4.5 Slope.gszDirectory: C:\Documents and Settings\B3ECGRPG\My Documents\White Ditch\Last Solved Date: 3/5/2010

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Last Solved Time: 11:01:41 AM

72.0PROJECT SETTINGS 365

Length(L) Units: feet

Time(t) Units: Seconds

Force(F) Units: lbf

Pressure(p) Units: psfStrength Units: psf 370

Unit Weight of Water: 62.4 pcfView: 2D

73.0ANALYSIS SETTINGS73.1 Low Water (hurricane condition)

Description: Active and Passive Wedge Method 375Kind: SLOPE/WMethod: Spencer

Settings

Apply Phreatic Correction: NoPWP Conditions Source: Piezometric Line 380

Use Staged Rapid Drawdown: No

SlipSurface

Direction of movement: Left to RightUse Passive Mode: NoSlip Surface Option: Block 385

Critical slip surfaces saved: 1Optimize Critical Slip Surface Location: YesTension Crack

Tension Crack Option: (none)

FOS Distribution 390

FOS Calculation Option: Constant

Restrict Block Crossing: YesAdvanced

Number of Slices: 75Optimization Tolerance: 0.01 395

Minimum Slip Surface Depth: 0.1 ftOptimization Maximum Iterations: 5000

Optimization Convergence Tolerance: 1e-007

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Starting Optimization Points: 8Ending Optimization Points: 16 400Complete Passes per Insertion: 1Driving Side Maximum Convex Angle: 5 °Resisting Side Maximum Convex Angle: 1 °

74.0MATERIALS74.1 Layer 1 - CL 405

Model: Mohr-Coulomb

Unit Weight: 100 pcf

Cohesion: 400 psf

Phi: 0 °

Phi-B: 0 ° 410

Pore Water Pressure

Piezometric Line: 1

74.2 Layer 4 - CL

Model: Mohr-Coulomb

Unit Weight: 107 pcf 415

Cohesion: 550 psf

Phi: 0 °

Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1 420

74.3 Layer 6 - CL

Model: Mohr-Coulomb

Unit Weight: 101 pcf

Cohesion: 780 psf

Phi: 0 ° 425

Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

74.4 Layer 7 - CL

Model: S=f(depth) 430Unit Weight: 101 pcf

C-Top of Layer: 500 psf

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C-Rate of Change: 14 psf/ftLimiting C: 1200 psfPore Water Pressure 435

Piezometric Line: 1

74.5 Layer 9 - CL

Model: Mohr-Coulomb

Unit Weight: 115 pcf

Cohesion: 900 psf 440Phi: 0 °

Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

74.6 Layer 2 - ML 445

Model: Mohr-Coulomb

Unit Weight: 117 pcf

Cohesion: 200 psf

Phi: 15 °Phi-B: 0 ° 450

Pore Water Pressure

Piezometric Line: 1

74.7 Layer 5 - ML

Model: Mohr-Coulomb

Unit Weight: 117 pcf 455

Cohesion: 200 psf

Phi: 15 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1 460

74.8 Layer 8 - ML

Model: Mohr-Coulomb

Unit Weight: 117 pcf

Cohesion: 200 psf

Phi: 15 ° 465

Phi-B: 0 °

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Pore Water Pressure

Piezometric Line: 1

74.9 Layer 3 - SM

Model: Mohr-Coulomb 470Unit Weight: 122 pcf

Cohesion: 0 psfPhi: 30 °Phi-B: 0 °

Pore Water Pressure 475

Piezometric Line: 1

74.10 Layer 10 - SM

Model: Mohr-Coulomb

Unit Weight: 122 pcf

Cohesion: 0 psf 480Phi: 30 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

75.0SLIP SURFACE LIMITS 485

Left Coordinate: (-200, 2) ft

Right Coordinate: (300, -16) ft

76.0SLIP SURFACE BLOCK

Left Grid

Upper Left: (7, -10) ft 490

Lower Left: (15, -115) ftLower Right: (55, -115) ftX Increments: 15Y Increments: 15Starting Angle: 115 ° 495Ending Angle: 135 °Angle Increments: 3

Right Grid

Upper Left: (60, -10) ftLower Left: (100, -115) ft 500

Lower Right: (135, -115) ft

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X Increments: 15Y Increments: 15Starting Angle: 0 °Ending Angle: 45 ° 505Angle Increments: 3

77.0PIEZOMETRIC LINES77.1 Piezometric Line 1

77.1.1 Coordinates

X (ft) Y (ft)

-160 2

-6 2

49 058 -2

300 -2

78.0 REGIONS 510

Material Points Area (ft2)

Region 1 Layer 10 - SM 20,21,15,11 9500Region 2 Layer 9 - CL 20,10,14,21 5500Region 3 Layer 8 - ML 10,9,13,14 5500Region 4 Layer 5 - ML 18,19,12,23 5750Region 5 Layer 4 - CL 8,18,23,22 2750Region 6 Layer 1 - CL 1,2,3,4,28,7,24,16 3316Region 7 Layer 2 - ML 17,16,24,25 1212Region 8 Layer 3 - SM 17,25,5,6,22,8 4633Region 9 Layer 6 - CL 19,26,27,12 4500Region 10 Layer 7 - CL 26,9,13,27 27000

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79.0 POINTS

X (ft) Y (ft)

Point 1 -200 2Point 2 -6 2Point 3 12 6Point 4 22 6Point 5 121 -16Point 6 300 -16Point 7 58 -2Point 8 -200 -24Point 9 -200 -104Point 10 -200 -115Point 11 -200 -145Point 12 300 -41Point 13 300 -104Point 14 300 -115Point 15 300 -145Point 16 -200 -10Point 17 -200 -14Point 18 -200 -29.5Point 19 -200 -41Point 20 -200 -126Point 21 300 -126Point 22 300 -24

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Point 23 300 -29.5Point 24 94 -10Point 25 112 -14Point 26 -200 -50Point 27 300 -50Point 28 49 0

80.0 CRITICAL SLIP SURFACES

Slip Surface FOS Center (ft) Radius (ft) Entry (ft) Exit (ft)

1 Optimized 2.638 (76.138, 6.5) 75.4855 (-6.32844, 2) (157.054, -16)2 27631 2.758 (76.138, 6.5) 79.983 (-14.4667, 2) (164.021, -16)

80.1 Slices of Slip Surface: Optimized

Slip

Surface X (ft) Y (ft) PWP (psf)

Base

Normal

Stress (psf)

Frictional

Strength

(psf)

Cohesive

Strength (psf)

1 Optimized -6.1642215 1.794791 12.805052 -156.18089 0 4002 Optimized -5.006771 0.34845795 100.80397 3.2180647 0 4003 Optimized -3.0203135 -2.1337901 251.18582 282.77513 0 4004 Optimized -1.0338562 -4.616038 401.57396 562.33565 0 4005 Optimized 0.95260125 -7.098286 551.95581 841.89932 0 4006 Optimized 2.500418 -9.169705 677.68177 1028.0652 0 4007 Optimized 4.3908875 -12 850.02155 1396.5026 146.42915 2008 Optimized 6.8136695 -15.62724 1070.8537 1814.1401 429.13661 09 Optimized 8.98747 -18.88172 1269.0038 2184.2246 528.40303 0

10 Optimized 11.037185 -21.7788 1445.1415 2559.2361 643.22282 011 Optimized 12.36067 -23.52432 1551.0343 2757.9899 696.83615 0

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12 Optimized 13.76389 -25.375 1663.3499 3021.6383 0 55013 Optimized 15.848995 -28.125 1830.2238 3302.4177 0 55014 Optimized 17.646385 -30.49554 1974.0641 3523.588 415.19368 20015 Optimized 19.300915 -32.51975 2096.6182 3795.9016 455.32161 20016 Optimized 21.100305 -34.577085 2220.9043 4016.5212 481.13411 20017 Optimized 23.17948 -36.954315 2364.549 4248.7423 504.86807 20018 Optimized 25.59142 -39.712015 2531.1368 4497.9766 527.01314 20019 Optimized 27.98083 -42.005455 2668.8234 4839.9829 0 78020 Optimized 30.29473 -43.774065 2773.9598 4963.592 0 78021 Optimized 32.60863 -45.542675 2879.0619 5087.2011 0 78022 Optimized 34.92253 -47.311285 2984.164 5211.1535 0 78023 Optimized 37.23643 -49.079895 3089.266 5334.7626 0 78024 Optimized 39.68681 -50.39752 3165.9271 5651.3991 0 505.8225 Optimized 42.220245 -51.246265 3213.1436 5679.2721 0 517.4526 Optimized 44.70025 -52.07711 3259.3685 5706.4183 0 529.0827 Optimized 47.470125 -52.750555 3295.2375 5779.9593 0 538.5128 Optimized 49.910215 -53.162095 3304.6736 5767.1589 0 544.2729 Optimized 51.73065 -53.469125 3298.6069 5757.4088 0 548.5730 Optimized 53.551085 -53.776155 3292.5402 5748.2004 0 552.8731 Optimized 55.345975 -53.920115 3276.6058 5798.4021 0 554.8832 Optimized 57.115325 -53.901005 3250.8917 5757.1464 0 554.6133 Optimized 59.05812 -53.88002 3237.3021 5726.3387 0 554.3234 Optimized 61.174355 -53.85716 3235.8846 5706.4934 0 55435 Optimized 63.29059 -53.8343 3234.4671 5686.648 0 553.68

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36 Optimized 65.40683 -53.81144 3233.0496 5667.2751 0 553.3637 Optimized 67.52307 -53.78858 3231.5848 5647.4297 0 553.0438 Optimized 69.639305 -53.76572 3230.1673 5627.5843 0 552.7239 Optimized 71.75554 -53.74286 3228.7497 5607.7389 0 552.440 Optimized 73.872975 -53.637525 3222.1847 5611.8126 0 550.9341 Optimized 75.99161 -53.44971 3210.4778 5575.1403 0 548.342 Optimized 78.110245 -53.261895 3198.7238 5538.4679 0 545.6743 Optimized 80.22888 -53.07408 3187.0169 5501.7955 0 543.0444 Optimized 82.347515 -52.886265 3175.3099 5465.1232 0 540.4145 Optimized 84.466145 -52.69845 3163.603 5428.4508 0 537.7846 Optimized 86.58478 -52.510635 3151.849 5391.7784 0 535.1547 Optimized 88.703415 -52.32282 3140.142 5355.1061 0 532.5248 Optimized 90.82205 -52.135005 3128.4351 5318.4337 0 529.8949 Optimized 92.940685 -51.947195 3116.7281 5281.7613 0 527.2650 Optimized 94.246845 -51.831405 3109.4004 5258.3994 0 525.6451 Optimized 95.50457 -51.62857 3096.8447 5257.8099 0 522.852 Optimized 97.52633 -51.266665 3074.2535 5196.4631 0 517.7353 Optimized 99.548105 -50.90476 3051.6623 5134.6294 0 512.6754 Optimized 101.56985 -50.542855 3029.0711 5072.7958 0 507.655 Optimized 103.6358 -50.173035 3006.0138 5009.9453 0 502.5356 Optimized 105.9091 -49.33031 2953.4203 5093.4259 0 78057 Optimized 108.34545 -48.02259 2871.7968 4928.5152 0 78058 Optimized 110.7818 -46.71487 2790.2094 4763.9661 0 78059 Optimized 112.3072 -45.896125 2739.139 4660.6952 0 780

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60 Optimized 113.82185 -44.9427 2679.6314 4597.3983 0 78061 Optimized 116.23675 -43.36562 2581.1999 4401.5061 0 78062 Optimized 118.6516 -41.78854 2482.8031 4205.9607 0 78063 Optimized 120.4295 -40.62744 2410.3317 4015.5073 430.10549 20064 Optimized 122.27035 -39.425265 2335.3298 3850.0894 405.8786 20065 Optimized 124.69765 -37.83768 2236.2765 3653.3213 379.69599 20066 Optimized 127.0115 -36.32174 2141.6719 3464.9435 354.56955 20067 Optimized 129.32535 -34.805795 2047.0673 3276.4211 329.40436 20068 Optimized 131.63925 -33.28985 1952.4989 3087.9349 304.23918 20069 Optimized 133.95315 -31.77391 1857.8943 2899.4487 279.08367 20070 Optimized 136.32305 -30.22129 1760.9991 2706.7892 253.42369 20071 Optimized 138.50255 -28.74831 1669.076 2577.9683 0 55072 Optimized 140.43565 -27.39165 1584.4323 2428.9633 0 55073 Optimized 142.36875 -26.03499 1499.7887 2280.0006 0 55074 Optimized 144.30185 -24.67833 1415.1451 2130.9957 0 55075 Optimized 145.84915 -23.59244 1347.3991 1946.8539 346.0954 076 Optimized 147.4923 -22.46639 1277.0987 1786.2385 293.95198 077 Optimized 149.6171 -21.029415 1187.434 1589.3269 232.033 078 Optimized 151.74195 -19.59244 1097.7693 1392.3764 170.09151 079 Optimized 153.8668 -18.155465 1008.1045 1195.4648 108.17253 080 Optimized 155.9916 -16.71849 918.43979 998.51429 46.231038 0

80.2 Slices of Slip Surface: 27631

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 27631 -13.408335 0.94166665 66.04154 -32.957631 0 400

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2 27631 -11.291665 -1.1749999 198.12128 171.58974 0 4003 27631 -9.1749985 -3.2916665 330.20102 376.12509 0 4004 27631 -7.0583335 -5.4083335 462.28076 580.6738 0 4005 27631 -4.2333335 -8.2333335 634.55495 891.63495 0 4006 27631 -1.4666669 -11 800.90453 1260.8068 123.23044 2007 27631 0.53333315 -13 921.1834 1517.5219 159.78843 2008 27631 2.783333 -15.25 1056.4741 1802.3303 430.62029 09 27631 5.283333 -17.75 1206.805 2118.407 526.31368 0

10 27631 7.783333 -20.25 1357.1359 2434.4837 622.00708 011 27631 10.283331 -22.75 1507.4385 2750.5605 717.71681 012 27631 11.766665 -24.233335 1596.5967 3010.6083 0 55013 27631 13.258335 -25.725 1686.3514 3169.8989 0 55014 27631 15.775 -28.241665 1837.6816 3430.0768 0 55015 27631 18.275 -30.741665 1988.0044 3666.8941 449.85713 20016 27631 20.758335 -33.225 2137.3226 3936.8285 482.17616 20017 27631 23.08889 -35.555555 2277.4538 4168.3943 506.67599 20018 27631 25.26667 -37.73333 2408.402 4362.2353 523.52807 20019 27631 27.444445 -39.91111 2539.3502 4556.0764 540.38015 20020 27631 29.65833 -42.125 2672.4861 4727.8724 0 78021 27631 31.90833 -44.375 2807.7792 4899.4636 0 78022 27631 34.15833 -46.625 2943.0723 5070.7405 0 78023 27631 36.40833 -48.875 3078.3653 5242.0175 0 78024 27631 38.53333 -51 3206.1637 5493.5128 0 51425 27631 40.716665 -52 3263.577 5923.9428 0 528

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26 27631 43.083335 -52 3258.2108 5871.1259 0 52827 27631 45.45 -52 3252.8446 5818.7316 0 52828 27631 47.816665 -52 3247.4784 5765.9147 0 52829 27631 50.125 -52 3229.2 5714.6667 0 52830 27631 52.375 -52 3198 5664.8889 0 52831 27631 54.625 -52 3166.8 5614.6667 0 52832 27631 56.875 -52 3135.6 5564.8889 0 52833 27631 59.2 -52 3120 5529.5833 0 52834 27631 61.6 -52 3120 5510 0 52835 27631 64 -52 3120 5490 0 52836 27631 66.4 -52 3120 5470.4167 0 52837 27631 68.8 -52 3120 5450.4167 0 52838 27631 71.2 -52 3120 5430.8333 0 52839 27631 73.6 -52 3120 5410.8333 0 52840 27631 76 -52 3120 5391.25 0 52841 27631 78.4 -52 3120 5371.25 0 52842 27631 80.8 -52 3120 5351.6667 0 52843 27631 83.2 -52 3120 5331.6667 0 52844 27631 85.6 -52 3120 5312.0833 0 52845 27631 88 -52 3120 5292.0833 0 52846 27631 90.4 -52 3120 5272.5 0 52847 27631 92.8 -52 3120 5252.5 0 52848 27631 95.27778 -52 3119.9864 5227.4339 0 52849 27631 97.833335 -52 3119.9864 5196.5208 0 528

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50 27631 100.3889 -52 3119.9864 5165.9991 0 52851 27631 103.39875 -51 3057.5 5241.5 0 51452 27631 106.27565 -49.33901 2953.9681 5094.9917 0 78053 27631 108.5654 -48.017025 2871.4784 4930.8445 0 78054 27631 110.85515 -46.69504 2788.9888 4766.3191 0 78055 27631 113.0899 -45.404795 2708.4764 4604.6442 0 78056 27631 115.2697 -44.14628 2629.9312 4445.7264 0 78057 27631 117.4495 -42.887765 2551.3861 4286.8085 0 78058 27631 119.6293 -41.629255 2472.8807 4127.8907 0 78059 27631 120.8596 -40.918945 2428.5464 4001.1055 421.36593 20060 27631 122.22735 -40.129275 2379.2774 3894.5497 406.016 20061 27631 124.6821 -38.71204 2290.8307 3719.9142 382.92177 20062 27631 127.13685 -37.2948 2202.3839 3545.6314 359.92207 20063 27631 129.59155 -35.877565 2113.9725 3371.1369 336.8562 20064 27631 132.04625 -34.46033 2025.5257 3196.713 313.8187 20065 27631 134.501 -33.04309 1937.079 3022.2891 290.78119 20066 27631 136.95575 -31.625855 1848.6675 2847.83 267.72477 20067 27631 139.41045 -30.20862 1760.2208 2673.4061 244.68726 20068 27631 141.8286 -28.8125 1673.0909 2537.5636 0 55069 27631 144.21015 -27.4375 1587.3091 2387.4545 0 55070 27631 146.5917 -26.0625 1501.4909 2237.3091 0 55071 27631 148.9733 -24.6875 1415.7091 2087.1636 0 55072 27631 151.3188 -23.333335 1331.2123 1875.7123 314.36718 073 27631 153.6282 -22 1247.9998 1697.2498 259.37458 0

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74 27631 155.9376 -20.666665 1164.7874 1518.8248 204.40362 075 27631 158.247 -19.333335 1081.6124 1340.3623 149.38936 076 27631 160.5564 -18 998.39988 1161.8999 94.396757 077 27631 162.8658 -16.666665 915.18739 983.43738 39.404151 0

515520525530535

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540

Low Water S-Case - Flood Side - Shallow

Report generated using GeoStudio 2007, version 7.15. Copyright © 1991-2009 GEO-SLOPE International Ltd.

81.0FILE INFORMATION

Created By: Goetz, Ryan MVSRevision Number: 74 545Last Edited By: Goetz, Ryan MVSDate: 3/5/2010Time: 10:57:29 AMFile Name: Location 3 - 35k cfs - Main Channel_R-60.3-LU_1on4.5 Slope.gszDirectory: C:\Documents and Settings\B3ECGRPG\My Documents\White Ditch\ 550Last Solved Date: 3/5/2010Last Solved Time: 11:06:07 AM

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82.0PROJECT SETTINGS

Length(L) Units: feet

Time(t) Units: Seconds 555

Force(F) Units: lbf

Pressure(p) Units: psfStrength Units: psfUnit Weight of Water: 62.4 pcfView: 2D 560

83.0ANALYSIS SETTINGS83.1 Low Water S-Case - Flood Side - Shallow

Description: Active and Passive Wedge MethodKind: SLOPE/WMethod: Spencer 565Settings

Apply Phreatic Correction: NoPWP Conditions Source: Piezometric LineUse Staged Rapid Drawdown: No

SlipSurface 570

Direction of movement: Left to RightUse Passive Mode: NoSlip Surface Option: BlockCritical slip surfaces saved: 1Optimize Critical Slip Surface Location: Yes 575Tension Crack

Tension Crack Option: (none)

FOS Distribution

FOS Calculation Option: Constant

Restrict Block Crossing: Yes 580

Advanced

Number of Slices: 75Optimization Tolerance: 0.01Minimum Slip Surface Depth: 0.1 ftOptimization Maximum Iterations: 5000 585

Optimization Convergence Tolerance: 1e-007

Starting Optimization Points: 8

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Ending Optimization Points: 16Complete Passes per Insertion: 1Driving Side Maximum Convex Angle: 5 ° 590Resisting Side Maximum Convex Angle: 1 °

84.0MATERIALS84.1 Layer 1 - CL - S-Case

Model: Mohr-Coulomb

Unit Weight: 105 pcf 595

Cohesion: 0 psfPhi: 23 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1 600

84.2 Layer 4 - CL - S-Case

Model: Mohr-Coulomb

Unit Weight: 105 pcf

Cohesion: 0 psfPhi: 23 ° 605Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

84.3 Layer 6 - CL - S-Case

Model: Mohr-Coulomb 610Unit Weight: 105 pcf

Cohesion: 0 psfPhi: 23 °Phi-B: 0 °

Pore Water Pressure 615

Piezometric Line: 1

84.4 Layer 9 - CL - S-Case

Model: Mohr-Coulomb

Unit Weight: 105 pcf

Cohesion: 0 psf 620Phi: 23 °

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Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

84.5 Layer 2 - ML - S-Case 625

Model: Mohr-Coulomb

Unit Weight: 117 pcf

Cohesion: 0 psfPhi: 28 °Phi-B: 0 ° 630Pore Water Pressure

Piezometric Line: 1

84.6 Layer 5 - ML - S-Case

Model: Mohr-Coulomb

Unit Weight: 117 pcf 635

Cohesion: 0 psfPhi: 28 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1 640

84.7 Layer 8 - ML - S-Case

Model: Mohr-Coulomb

Unit Weight: 117 pcf

Cohesion: 0 psfPhi: 28 ° 645Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

84.8 Layer 3 - SM - S-Case

Model: Mohr-Coulomb 650Unit Weight: 122 pcf

Cohesion: 0 psfPhi: 30 °Phi-B: 0 °

Pore Water Pressure 655

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Piezometric Line: 1

84.9 Layer 10 - SM - S-Case

Model: Mohr-Coulomb

Unit Weight: 122 pcf

Cohesion: 0 psf 660Phi: 30 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

84.10 Layer 7 - CL - S-Case 665

Model: Mohr-Coulomb

Unit Weight: 105 pcf

Cohesion: 0 psfPhi: 23 °Phi-B: 0 ° 670Pore Water Pressure

Piezometric Line: 1

85.0SLIP SURFACE LIMITS

Left Coordinate: (-200, 2) ft

Right Coordinate: (300, -16) ft 675

86.0SLIP SURFACE BLOCK

Left Grid

Upper Left: (24.6008, 0) ftLower Left: (19.9471, -33.5) ft

Lower Right: (31.5812, -33.5) ft 680

X Increments: 15Y Increments: 15Starting Angle: 115 °Ending Angle: 135 °Angle Increments: 3 685

Right Grid

Upper Left: (36.6357, 0) ftLower Left: (47.9905, -33.5) ft

Lower Right: (68.6991, -33.5) ftX Increments: 15 690

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Y Increments: 15Starting Angle: 0 °Ending Angle: 45 °Angle Increments: 3

87.0PIEZOMETRIC LINES 69587.1 Piezometric Line 1

87.1.1 Coordinates

X (ft) Y (ft)

-200 2

-6 2

49 0

300 0

88.0 REGIONS

Material Points Area (ft2)

Region 1 Layer 10 - SM - S-Case 20,21,15,11 9500Region 2 Layer 9 - CL - S-Case 20,10,14,21 5500Region 3 Layer 8 - ML - S-Case 10,9,13,14 5500Region 4 Layer 5 - ML - S-Case 18,19,12,23 5750Region 5 Layer 4 - CL - S-Case 8,18,23,22 2750Region 6 Layer 1 - CL - S-Case 1,2,3,4,28,7,24,16 3316Region 7 Layer 2 - ML - S-Case 17,16,24,25 1212Region 8 Layer 3 - SM - S-Case 17,25,5,6,22,8 4633Region 9 Layer 6 - CL - S-Case 19,26,27,12 4500Region 10 Layer 7 - CL - S-Case 26,9,13,27 27000

89.0 POINTS

X (ft) Y (ft)

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Point 1 -200 2Point 2 -6 2Point 3 12 6Point 4 22 6Point 5 121 -16Point 6 300 -16Point 7 58 -2Point 8 -200 -24Point 9 -200 -104Point 10 -200 -115Point 11 -200 -145Point 12 300 -41Point 13 300 -104Point 14 300 -115Point 15 300 -145Point 16 -200 -10Point 17 -200 -14Point 18 -200 -29.5Point 19 -200 -41Point 20 -200 -126Point 21 300 -126Point 22 300 -24Point 23 300 -29.5Point 24 94 -10

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Point 25 112 -14Point 26 -200 -50Point 27 300 -50Point 28 49 0

90.0 CRITICAL SLIP SURFACES 700

Slip Surface FOS Center (ft) Radius (ft) Entry (ft) Exit (ft)

1 Optimized 1.484 (52.6, 9.175) 28.67836 (20.6797, 6) (85.4425, -8.09833)2 16117 1.650 (52.6, 9.175) 25.958 (21.8286, 6) (79.15, -6.7)

90.1 Slices of Slip Surface: Optimized

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 Optimized 21.00979 5.6961825 -291.92407 23.756726 10.084132 02 Optimized 21.66993 5.0885475 -255.51158 71.270177 30.252395 03 Optimized 22.390885 4.424935 -215.73999 116.36388 49.393538 04 Optimized 23.17265 3.705345 -172.60705 159.05448 67.514622 05 Optimized 23.954415 2.985755 -129.48352 201.73567 85.631712 06 Optimized 24.742605 2.323275 -89.93029 252.0771 107.00038 07 Optimized 25.537215 1.717905 -53.958174 287.31444 121.95774 08 Optimized 26.33183 1.1125348 -17.986058 322.55178 136.91511 09 Optimized 27.21776 0.43759719 22.119914 365.01317 145.54955 0

10 Optimized 28.195 -0.30690761 66.359742 414.69039 147.85759 011 Optimized 29.142185 -0.931291 103.1708 481.92552 160.77184 012 Optimized 30.05931 -1.435553 132.56081 511.4493 160.82862 013 Optimized 30.976435 -1.939815 161.94127 540.96353 160.8854 014 Optimized 31.89356 -2.444077 191.32173 570.47775 160.94218 0

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15 Optimized 32.810685 -2.948339 220.71174 599.99197 160.99491 016 Optimized 33.72914 -3.382438 245.71217 648.21306 170.85149 017 Optimized 34.64892 -3.746374 266.33561 664.49952 169.01055 018 Optimized 35.568705 -4.11031 286.95906 680.78598 167.16961 019 Optimized 36.48849 -4.474246 307.5825 697.08254 165.33296 020 Optimized 37.40827 -4.838182 328.20595 713.369 163.49201 021 Optimized 38.31437 -5.136275 344.75156 748.60464 171.42546 022 Optimized 39.206785 -5.368525 357.22252 752.3893 167.73834 023 Optimized 40.0992 -5.600775 369.68264 756.16312 164.05123 024 Optimized 40.991615 -5.833025 382.1536 759.94779 160.36412 025 Optimized 41.88403 -6.065275 394.62456 763.73245 156.677 026 Optimized 42.809035 -6.25524 404.37163 782.91013 160.68006 027 Optimized 43.766625 -6.40292 411.42078 776.32541 154.89283 028 Optimized 44.724215 -6.5506 418.45962 769.73038 149.10559 029 Optimized 45.61221 -6.6486935 422.57046 777.96925 150.85784 030 Optimized 46.430615 -6.6972 423.74142 763.78355 144.33932 031 Optimized 47.24902 -6.7457065 424.90019 749.59785 137.82598 032 Optimized 47.993665 -6.764812 424.40113 748.08225 137.39449 033 Optimized 48.664555 -6.754516 422.24007 730.7044 130.93534 034 Optimized 49.45014 -6.74246 420.72833 717.01072 125.76441 035 Optimized 50.350425 -6.7286435 419.86204 707.00396 121.88451 036 Optimized 51.250715 -6.714827 419.00685 696.98609 117.99518 037 Optimized 52.151 -6.701011 418.14056 686.97932 114.11528 038 Optimized 53.05128 -6.6871945 417.28538 676.96145 110.22595 0

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39 Optimized 53.951565 -6.673378 416.41909 666.95469 106.34605 040 Optimized 54.854935 -6.660895 415.64508 656.57781 102.26988 041 Optimized 55.761385 -6.649745 414.93909 646.80416 98.420884 042 Optimized 56.667835 -6.638595 414.24412 637.0305 94.567209 043 Optimized 57.56053 -6.633044 413.89628 626.20884 90.121334 044 Optimized 58.44488 -6.633093 413.90937 617.88572 86.582825 045 Optimized 59.33464 -6.6331425 413.90937 609.51268 83.028679 046 Optimized 60.2244 -6.6331915 413.90937 601.13963 79.474532 047 Optimized 61.11416 -6.6332405 413.90937 592.76659 75.920386 048 Optimized 62.00392 -6.6332895 413.92061 584.39354 72.361468 049 Optimized 62.89368 -6.6333385 413.92061 576.0205 68.807322 050 Optimized 63.78344 -6.6333875 413.92061 567.64746 65.253175 051 Optimized 64.6732 -6.6334365 413.93185 559.27441 61.694258 052 Optimized 65.56296 -6.6334855 413.93185 550.90137 58.140112 053 Optimized 66.411265 -6.6383875 414.23378 542.12885 54.288235 054 Optimized 67.218115 -6.6481425 414.84103 535.61016 51.263454 055 Optimized 68.02497 -6.6578975 415.44829 529.09148 48.238674 056 Optimized 68.831825 -6.6676525 416.05554 522.5604 45.208633 057 Optimized 69.728485 -6.687035 417.27569 514.58023 41.303328 058 Optimized 70.71496 -6.716045 419.07931 508.48033 37.948481 059 Optimized 71.61636 -6.753485 421.41237 501.71983 34.088496 060 Optimized 72.43268 -6.799355 424.27438 499.02906 31.731478 061 Optimized 73.249 -6.845225 427.13639 496.33828 29.374461 062 Optimized 74.06532 -6.891095 429.9984 493.65973 27.022635 0

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63 Optimized 74.88164 -6.936965 432.87264 490.96896 24.660425 064 Optimized 75.69796 -6.982835 435.73464 488.27818 22.303408 065 Optimized 76.531585 -7.046219 439.68918 484.40334 18.980032 066 Optimized 77.38251 -7.127117 444.73152 485.11698 17.142614 067 Optimized 78.233435 -7.208015 449.78555 485.84233 15.305196 068 Optimized 79.08436 -7.288913 454.82788 486.56768 13.472744 069 Optimized 79.935285 -7.369811 459.88192 487.28133 11.63036 070 Optimized 80.784225 -7.467599 465.97442 487.10509 8.9694346 071 Optimized 81.63118 -7.582277 473.13498 491.39908 7.7526508 072 Optimized 82.478135 -7.696955 480.29554 495.68138 6.5309006 073 Optimized 83.325085 -7.8116325 487.4444 499.96367 5.3141168 074 Optimized 84.17204 -7.92631 494.60495 504.24596 4.0923666 075 Optimized 85.018995 -8.040988 501.75381 508.53996 2.8805493 0

90.2 Slices of Slip Surface: 16117

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 16117 21.914275 5.9142765 -307.59021 6.638973 2.8180768 02 16117 22.35926 5.469294 -280.83756 34.917467 14.821585 03 16117 23.07778 4.7507755 -237.62497 78.196979 33.192648 04 16117 23.7963 4.0322565 -194.42222 121.47944 51.564964 05 16117 24.514815 3.313738 -151.21947 164.76092 69.936863 06 16117 25.23333 2.5952195 -108.01672 208.03256 88.304584 07 16117 25.95185 1.8767005 -64.808063 251.31404 106.67648 08 16117 26.67037 1.1581818 -21.60236 294.59552 125.04838 09 16117 27.404575 0.42397638 22.545799 342.53396 135.82691 0

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10 16117 28.15447 -0.32591587 67.637396 395.13139 139.01295 011 16117 28.904365 -1.075808 112.72899 447.72882 142.19899 012 16117 29.654255 -1.8257 157.82059 500.33569 145.38903 013 16117 30.404145 -2.5755925 202.91219 552.93312 148.57507 014 16117 31.154035 -3.325485 248.00379 605.53056 151.76111 015 16117 31.90393 -4.075377 293.09538 658.12799 154.94715 016 16117 32.653825 -4.825269 338.18698 710.72543 158.13319 017 16117 33.403715 -5.5751615 383.27858 763.32286 161.31923 018 16117 34.153605 -6.325054 428.37018 815.92029 164.50526 019 16117 34.90938 -6.7 450.05935 1052.7862 255.84238 020 16117 35.671035 -6.7 448.32628 1034.4446 248.79246 021 16117 36.43269 -6.7 446.59322 1016.103 241.74254 022 16117 37.194345 -6.7 444.87328 997.77445 234.69262 023 16117 37.956 -6.7 443.14021 979.43282 227.64271 024 16117 38.717655 -6.7 441.40714 961.10431 220.59836 025 16117 39.47931 -6.7 439.6872 942.76268 213.54287 026 16117 40.240965 -6.7 437.95413 924.42104 206.49295 027 16117 41.00262 -6.7 436.22107 906.09253 199.44861 028 16117 41.764275 -6.7 434.50113 887.7509 192.39311 029 16117 42.52593 -6.7 432.76806 869.40926 185.34319 030 16117 43.287585 -6.7 431.04812 851.08076 178.29328 031 16117 44.04924 -6.7 429.31505 832.73912 171.24336 032 16117 44.810895 -6.7 427.58199 814.39749 164.19344 033 16117 45.57255 -6.7 425.86205 796.06898 157.14352 0

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34 16117 46.334205 -6.7 424.12898 777.72735 150.0936 035 16117 47.09586 -6.7 422.39591 759.39884 143.04926 036 16117 47.857515 -6.7 420.67597 741.05721 135.99376 037 16117 48.61917 -6.7 418.9429 722.71557 128.94385 038 16117 49.392705 -6.7 418.07394 709.8701 123.86012 039 16117 50.178115 -6.7 418.07394 702.49817 120.73092 040 16117 50.963525 -6.7 418.07394 695.13897 117.60712 041 16117 51.74894 -6.7 418.07394 687.76703 114.47792 042 16117 52.534355 -6.7 418.07394 680.40783 111.35413 043 16117 53.319765 -6.7 418.07394 673.0359 108.22493 044 16117 54.105175 -6.7 418.07394 665.6767 105.10113 045 16117 54.890585 -6.7 418.07394 658.3175 101.97734 046 16117 55.675995 -6.7 418.07394 650.94556 98.848137 047 16117 56.461405 -6.7 418.07394 643.58636 95.724341 048 16117 57.427055 -6.7 418.07787 634.52155 91.874892 049 16117 58.37768 -6.7 418.0804 625.61138 88.091675 0

50 16117 59.133035 -6.7 418.0804 618.52864 85.085229 051 16117 59.88839 -6.7 418.0804 611.4459 82.078783 052 16117 60.64375 -6.7 418.0804 604.36315 79.072337 053 16117 61.39911 -6.7 418.0804 597.28041 76.065891 054 16117 62.154465 -6.7 418.0804 590.19767 73.059445 055 16117 62.90982 -6.7 418.0804 583.11493 70.053 056 16117 63.66518 -6.7 418.0804 576.03218 67.046554 057 16117 64.420535 -6.7 418.0804 568.94944 64.040108 058 16117 65.17589 -6.7 418.0804 561.8667 61.033662 0

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59 16117 65.93125 -6.7 418.0804 554.77072 58.021596 060 16117 66.68661 -6.7 418.0804 547.68797 55.01515 061 16117 67.441965 -6.7 418.0804 540.60523 52.008705 062 16117 68.19732 -6.7 418.0804 533.52249 49.002259 063 16117 68.95268 -6.7 418.0804 526.43975 45.995813 064 16117 69.708035 -6.7 418.0804 519.357 42.989367 065 16117 70.46339 -6.7 418.0804 512.27426 39.982921 066 16117 71.21875 -6.7 418.0804 505.19152 36.976475 067 16117 71.97411 -6.7 418.0804 498.10878 33.970029 068 16117 72.729465 -6.7 418.0804 491.02603 30.963583 069 16117 73.48482 -6.7 418.0804 483.94329 27.957137 070 16117 74.24018 -6.7 418.0804 476.86055 24.950691 071 16117 74.995535 -6.7 418.0804 469.7778 21.944245 072 16117 75.75089 -6.7 418.0804 462.69506 18.937799 073 16117 76.50625 -6.7 418.0804 455.61232 15.931354 074 16117 77.26161 -6.7 418.0804 448.52958 12.924908 075 16117 78.016965 -6.7 418.0804 441.44683 9.9184618 076 16117 78.77232 -6.7 418.0804 434.36409 6.9120158 0

705

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Low Water S-Case - Flood Side

Report generated using GeoStudio 2007, version 7.15. Copyright © 1991-2009 GEO-SLOPE International Ltd.

91.0FILE INFORMATION 710

Created By: Goetz, Ryan MVSRevision Number: 76Last Edited By: Goetz, Ryan MVSDate: 3/5/2010Time: 1:00:10 PM 715File Name: Location 3 - 35k cfs - Main Channel_R-60.3-LU_1on4.5 Slope.gszDirectory: C:\Documents and Settings\B3ECGRPG\My Documents\White Ditch\Last Solved Date: 3/5/2010Last Solved Time: 1:01:27 PM

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92.0PROJECT SETTINGS 720

Length(L) Units: feet

Time(t) Units: Seconds

Force(F) Units: lbf

Pressure(p) Units: psfStrength Units: psf 725

Unit Weight of Water: 62.4 pcfView: 2D

93.0ANALYSIS SETTINGS93.1 Low Water S-Case - Flood Side

Description: Active and Passive Wedge Method 730Kind: SLOPE/WMethod: Spencer

Settings

Apply Phreatic Correction: NoPWP Conditions Source: Piezometric Line 735

Use Staged Rapid Drawdown: No

SlipSurface

Direction of movement: Left to RightUse Passive Mode: NoSlip Surface Option: Block 740

Critical slip surfaces saved: 1Optimize Critical Slip Surface Location: YesTension Crack

Tension Crack Option: (none)

FOS Distribution 745

FOS Calculation Option: Constant

Restrict Block Crossing: YesAdvanced

Number of Slices: 75Optimization Tolerance: 0.01 750

Minimum Slip Surface Depth: 0.1 ftOptimization Maximum Iterations: 5000

Optimization Convergence Tolerance: 1e-007

Starting Optimization Points: 8

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Ending Optimization Points: 16 755Complete Passes per Insertion: 1Driving Side Maximum Convex Angle: 5 °Resisting Side Maximum Convex Angle: 1 °

94.0MATERIALS94.1 Layer 1 - CL - S-Case 760

Model: Mohr-Coulomb

Unit Weight: 105 pcf

Cohesion: 0 psfPhi: 23 °Phi-B: 0 ° 765Pore Water Pressure

Piezometric Line: 1

94.2 Layer 4 - CL - S-Case

Model: Mohr-Coulomb

Unit Weight: 105 pcf 770

Cohesion: 0 psfPhi: 23 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1 775

94.3 Layer 6 - CL - S-Case

Model: Mohr-Coulomb

Unit Weight: 105 pcf

Cohesion: 0 psfPhi: 23 ° 780Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

94.4 Layer 9 - CL - S-Case

Model: Mohr-Coulomb 785Unit Weight: 105 pcf

Cohesion: 0 psfPhi: 23 °

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Phi-B: 0 °

Pore Water Pressure 790

Piezometric Line: 1

94.5 Layer 2 - ML - S-Case

Model: Mohr-Coulomb

Unit Weight: 117 pcf

Cohesion: 0 psf 795Phi: 28 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

94.6 Layer 5 - ML - S-Case 800

Model: Mohr-Coulomb

Unit Weight: 117 pcf

Cohesion: 0 psfPhi: 28 °Phi-B: 0 ° 805Pore Water Pressure

Piezometric Line: 1

94.7 Layer 8 - ML - S-Case

Model: Mohr-Coulomb

Unit Weight: 117 pcf 810

Cohesion: 0 psfPhi: 28 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1 815

94.8 Layer 3 - SM - S-Case

Model: Mohr-Coulomb

Unit Weight: 122 pcf

Cohesion: 0 psfPhi: 30 ° 820Phi-B: 0 °

Pore Water Pressure

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Piezometric Line: 1

94.9 Layer 10 - SM - S-Case

Model: Mohr-Coulomb 825Unit Weight: 122 pcf

Cohesion: 0 psfPhi: 30 °Phi-B: 0 °

Pore Water Pressure 830

Piezometric Line: 1

94.10 Layer 7 - CL - S-Case

Model: Mohr-Coulomb

Unit Weight: 105 pcf

Cohesion: 0 psf 835Phi: 23 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

95.0SLIP SURFACE LIMITS 840

Left Coordinate: (-200, 2) ft

Right Coordinate: (300, -16) ft

96.0SLIP SURFACE BLOCK

Left Grid

Upper Left: (5.2803, -16.2114) ft 845

Lower Left: (25.2901, -82.6562) ftLower Right: (56.3051, -83.1814) ftX Increments: 10Y Increments: 10Starting Angle: 115 ° 850Ending Angle: 135 °Angle Increments: 3

Right Grid

Upper Left: (50.0021, -14.6356) ftLower Left: (112.8326, -83.1814) ft 855

Lower Right: (143.1473, -83.5754) ftX Increments: 10

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Y Increments: 10Starting Angle: 0 °Ending Angle: 45 ° 860Angle Increments: 3

97.0PIEZOMETRIC LINES97.1 Piezometric Line 1

97.1.1 Coordinates

X (ft) Y (ft)

-160 2

-6 2

49 0

300 0

98.0 REGIONS 865

Material Points Area (ft2)

Region 1 Layer 10 - SM - S-Case 20,21,15,11 9500Region 2 Layer 9 - CL - S-Case 20,10,14,21 5500Region 3 Layer 8 - ML - S-Case 10,9,13,14 5500Region 4 Layer 5 - ML - S-Case 18,19,12,23 5750Region 5 Layer 4 - CL - S-Case 8,18,23,22 2750Region 6 Layer 1 - CL - S-Case 1,2,3,4,28,7,24,16 3316Region 7 Layer 2 - ML - S-Case 17,16,24,25 1212Region 8 Layer 3 - SM - S-Case 17,25,5,6,22,8 4633Region 9 Layer 6 - CL - S-Case 19,26,27,12 4500Region 10 Layer 7 - CL - S-Case 26,9,13,27 27000

99.0 POINTS

X (ft) Y (ft)

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Point 1 -200 2Point 2 -6 2Point 3 12 6Point 4 22 6Point 5 121 -16Point 6 300 -16Point 7 58 -2Point 8 -200 -24Point 9 -200 -104Point 10 -200 -115Point 11 -200 -145Point 12 300 -41Point 13 300 -104Point 14 300 -115Point 15 300 -145Point 16 -200 -10Point 17 -200 -14Point 18 -200 -29.5Point 19 -200 -41Point 20 -200 -126Point 21 300 -126Point 22 300 -24Point 23 300 -29.5Point 24 94 -10

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Point 25 112 -14Point 26 -200 -50Point 27 300 -50Point 28 49 0

100.0 CRITICAL SLIP SURFACES

Slip Surface FOS Center (ft) Radius (ft) Entry (ft) Exit (ft)

1 Optimized 2.187 (67.933, 11.218) 47.02012 (13.4298, 6) (120.99, -15.9979)2 1917 2.602 (67.933, 11.218) 45.214 (13.5587, 6) (115.924, -14.872)

100.1 Slices of Slip Surface: Optimized

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 Optimized 14.23555 5.186277 -244.74054 67.100292 28.482384 02 Optimized 15.847045 3.558831 -146.8452 201.30088 85.447152 03 Optimized 17.458535 1.9313855 -48.949855 335.50146 142.41192 04 Optimized 18.5473 0.8318415 17.192643 428.56681 174.61797 05 Optimized 19.62274 -0.1226788 74.3154 533.43518 194.88478 06 Optimized 21.20758 -1.4600763 154.17154 657.51118 213.655 07 Optimized 22.78061 -2.7875095 233.43631 765.80151 225.97562 08 Optimized 24.341835 -4.104978 312.10181 858.32036 231.85602 09 Optimized 25.90306 -5.422446 390.7673 950.8392 237.73642 0

10 Optimized 27.45553 -6.4077485 448.72873 1090.859 272.56812 011 Optimized 28.99925 -7.060885 485.98558 1122.5377 270.20036 012 Optimized 30.542965 -7.7140215 523.23646 1154.1568 267.80981 013 Optimized 32.08668 -8.3671585 560.48734 1185.8356 265.44459 014 Optimized 33.6304 -9.020295 597.72032 1217.4547 263.06164 0

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15 Optimized 35.17412 -9.6734315 635.007 1249.0738 260.65589 016 Optimized 36.543555 -10.25283 668.04446 1271.1446 320.67406 017 Optimized 37.73871 -10.758495 696.87947 1301.1201 321.28045 018 Optimized 38.93387 -11.26416 725.72219 1331.0956 321.88274 019 Optimized 40.274185 -11.710655 750.55093 1393.3592 341.7872 020 Optimized 41.759655 -12.097985 771.3308 1404.1725 336.48791 021 Optimized 43.245125 -12.485315 792.11068 1414.9859 331.18861 022 Optimized 44.7306 -12.872645 812.9557 1425.7992 325.85468 023 Optimized 46.216075 -13.259975 833.73558 1436.5474 320.52075 024 Optimized 47.701545 -13.647305 854.51545 1447.3608 315.22146 025 Optimized 48.72214 -13.871935 866.24487 1491.2353 332.31328 026 Optimized 49.43561 -13.95145 870.57374 1490.0459 329.37918 027 Optimized 50.70291 -14.09269 879.3822 1495.2126 355.54987 028 Optimized 52.154375 -14.19252 885.5854 1524.9687 369.14812 029 Optimized 53.393925 -14.2068 886.47276 1515.1271 362.95374 030 Optimized 54.678085 -14.22952 887.94792 1502.1834 354.62901 031 Optimized 56.00685 -14.260685 889.90409 1493.6064 348.54767 032 Optimized 57.335615 -14.29185 891.78501 1485.0293 342.50976 033 Optimized 58.388745 -14.31655 893.34783 1478.1977 337.66325 034 Optimized 59.453825 -14.350665 895.4699 1468.4643 330.81844 035 Optimized 60.80649 -14.400655 898.57276 1462.0369 325.31618 036 Optimized 62.159155 -14.45065 901.74949 1455.6096 319.77126 037 Optimized 63.511825 -14.500645 904.85235 1449.1822 314.26899 038 Optimized 65.121885 -14.529585 906.62914 1447.0403 312.00653 0

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39 Optimized 66.74872 -14.5343 906.92348 1433.245 303.87185 040 Optimized 68.134945 -14.53584 907.06776 1420.4043 296.37501 041 Optimized 69.52117 -14.537385 907.13989 1407.4916 288.87817 042 Optimized 70.907395 -14.53893 907.21203 1394.6509 281.42298 043 Optimized 72.29362 -14.54047 907.35631 1381.8103 273.92615 044 Optimized 73.68717 -14.543025 907.49517 1368.6309 266.23685 045 Optimized 75.088055 -14.546595 907.70932 1355.9247 258.77727 046 Optimized 76.48894 -14.550165 907.92347 1343.2185 251.31769 047 Optimized 77.889825 -14.55374 908.13762 1330.4409 243.8169 048 Optimized 79.29071 -14.557315 908.35177 1317.7347 236.35733 049 Optimized 80.691595 -14.560885 908.56592 1305.0284 228.89775 050 Optimized 82.09248 -14.564455 908.85145 1292.2508 221.35575 051 Optimized 83.493365 -14.568025 909.0656 1279.5446 213.89617 052 Optimized 84.89425 -14.571595 909.27975 1266.8384 206.43659 053 Optimized 86.295135 -14.57517 909.4939 1254.1322 198.97701 054 Optimized 87.69602 -14.578745 909.70805 1241.3546 191.47622 055 Optimized 89.096905 -14.582315 909.9222 1228.6484 184.01665 056 Optimized 90.49779 -14.585885 910.13635 1215.9422 176.55707 057 Optimized 91.898675 -14.589455 910.3505 1203.1646 169.05628 058 Optimized 93.29956 -14.593025 910.63603 1190.4583 161.55549 059 Optimized 94.75608 -14.59674 910.8133 1175.1363 152.60696 060 Optimized 96.26824 -14.600595 911.07783 1157.2811 142.14554 061 Optimized 97.7804 -14.60445 911.34235 1139.4259 131.68411 062 Optimized 99.29254 -14.608305 911.54074 1121.5046 121.22269 0

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63 Optimized 100.8047 -14.61216 911.80526 1103.6494 110.76127 064 Optimized 102.3169 -14.616015 912.06978 1085.7942 100.29985 065 Optimized 103.82905 -14.61987 912.26817 1067.939 89.876603 066 Optimized 105.2684 -14.653655 914.38855 1048.5242 77.443261 067 Optimized 106.63495 -14.717365 918.33587 1039.9717 70.226477 068 Optimized 108.00145 -14.781075 922.35628 1031.4923 63.009694 069 Optimized 109.20845 -14.840075 926.02267 1023.6282 56.352578 070 Optimized 110.29915 -14.910655 930.43665 1016.2609 49.550642 071 Optimized 111.43305 -14.997525 935.8886 1013.447 44.778346 072 Optimized 112.67175 -15.09242 941.73475 1009.5687 39.163975 073 Optimized 114.0152 -15.195345 948.1916 1004.6705 32.60808 074 Optimized 115.47485 -15.34069 957.2809 998.99496 24.083622 075 Optimized 117.0507 -15.52845 969.00116 1001.5154 18.772128 076 Optimized 118.62655 -15.71621 980.72143 1004.0359 13.460635 077 Optimized 120.2024 -15.90397 992.37868 1006.5564 8.1855211 0

100.2 Slices of Slip Surface: 1917

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 1917 14.169825 5.388874 -257.23088 51.316585 21.782598 02 1917 15.392075 4.166622 -183.74047 153.95207 65.348776 03 1917 16.61433 2.94437 -110.24428 256.58292 108.91299 04 1917 17.836585 1.722118 -36.747516 359.21957 152.47966 05 1917 19.03976 0.51894348 35.600248 464.41856 182.02258 06 1917 20.223855 -0.66515402 106.80373 572.17776 197.53956 07 1917 21.40795 -1.8492515 178.00422 679.93696 213.05781 0

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8 1917 22.62989 -3.0711915 251.47578 779.41045 224.09497 09 1917 23.889675 -4.330975 327.22778 870.56432 230.63268 0

10 1917 25.14946 -5.5907585 402.97979 961.66205 237.14655 011 1917 26.40924 -6.8505415 478.73179 1052.8159 243.68425 012 1917 27.669025 -8.110325 554.4838 1143.9698 250.22196 013 1917 28.92881 -9.3701085 630.21897 1235.1236 256.7668 014 1917 30.225365 -10.666665 708.20283 1317.287 323.85578 015 1917 31.5587 -12 788.38874 1425.7395 338.88539 016 1917 32.892035 -13.333335 868.57465 1534.1389 353.88681 017 1917 34.24285 -14.68415 949.78574 1638.237 397.47752 018 1917 35.61115 -16.05245 1032.0568 1754.4086 417.05005 019 1917 37.001115 -16.69534 1068.9915 2179.9903 641.43543 020 1917 38.41275 -16.612815 1060.6467 2135.4372 620.53059 021 1917 39.824385 -16.53029 1052.3018 2090.8841 599.62576 0

22 1917 41.236015 -16.44777 1043.9569 2046.2603 578.68009 023 1917 42.64765 -16.365245 1035.6121 2001.7072 557.77526 024 1917 44.059285 -16.28272 1027.2672 1957.1541 536.87043 025 1917 45.470915 -16.2002 1018.9223 1912.5302 515.92476 026 1917 46.88255 -16.117675 1010.5775 1867.9771 495.01993 027 1917 48.294185 -16.03515 1002.1619 1823.3533 474.1151 028 1917 49.642855 -15.95631 995.64488 1790.2662 458.77486 029 1917 50.92857 -15.88115 990.98616 1768.6032 448.95741 030 1917 52.214285 -15.805985 986.32745 1746.9402 439.13997 031 1917 53.5 -15.73082 981.59109 1725.2772 429.36736 032 1917 54.785715 -15.65566 976.93238 1703.5365 419.50509 0

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33 1917 56.07143 -15.5805 972.19602 1681.8735 409.73248 034 1917 57.357145 -15.50534 967.5373 1660.2105 399.91504 035 1917 58.727925 -15.425205 962.53868 1637.1455 389.48441 036 1917 60.18377 -15.340095 957.1901 1612.5969 378.39927 037 1917 61.639615 -15.254985 951.91009 1588.0483 367.27454 038 1917 63.09546 -15.169875 946.63009 1563.4996 356.14981 039 1917 64.551305 -15.08477 941.28151 1538.951 345.06466 040 1917 66.00715 -14.999665 936.0015 1514.4024 333.93993 041 1917 67.462995 -14.914555 930.65292 1489.9224 322.89438 042 1917 68.870105 -14.872 928.02198 1454.7551 304.10949 043 1917 70.22848 -14.872 928.02198 1442.0192 296.75646 044 1917 71.586855 -14.872 928.02198 1429.357 289.44593 045 1917 72.945225 -14.872 928.02198 1416.6212 282.0929 046 1917 74.303595 -14.872 928.02198 1403.8854 274.73986 047 1917 75.66197 -14.872 928.02198 1391.1496 267.38683 048 1917 77.020345 -14.872 928.02198 1378.4874 260.0763 049 1917 78.378715 -14.872 928.02198 1365.7515 252.72327 050 1917 79.737085 -14.872 928.02198 1353.0157 245.37024 051 1917 81.09546 -14.872 928.02198 1340.2799 238.01721 052 1917 82.453835 -14.872 928.02198 1327.6177 230.70668 053 1917 83.812205 -14.872 928.02198 1314.8818 223.35365 054 1917 85.170575 -14.872 928.02198 1302.146 216.00062 055 1917 86.52895 -14.872 928.02198 1289.4838 208.69009 056 1917 87.887325 -14.872 928.02198 1276.748 201.33706 057 1917 89.245695 -14.872 928.02198 1264.0122 193.98403 058 1917 90.604065 -14.872 928.02198 1251.2763 186.63099 0

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59 1917 91.96244 -14.872 928.02198 1238.6141 179.32047 060 1917 93.320815 -14.872 928.02198 1225.8783 171.96743 061 1917 94.69231 -14.872 927.98359 1211.167 163.49602 062 1917 96.076925 -14.872 927.98359 1194.4114 153.82219 063 1917 97.46154 -14.872 927.98359 1177.6559 144.14836 064 1917 98.846155 -14.872 927.98359 1160.9003 134.47454 065 1917 100.23078 -14.872 927.98359 1144.217 124.84241 066 1917 101.6154 -14.872 927.98359 1127.4614 115.16858 067 1917 103 -14.872 927.98359 1110.7059 105.49475 068 1917 104.3846 -14.872 927.98359 1093.9503 95.820926 069 1917 105.7692 -14.872 927.98359 1077.1947 86.147099 070 1917 107.15385 -14.872 927.98359 1060.5114 76.514969 071 1917 108.5385 -14.872 927.98359 1043.7558 66.841142 072 1917 109.9231 -14.872 927.98359 1027.0003 57.167315 073 1917 111.3077 -14.872 927.98359 1010.2447 47.493488 074 1917 112.654 -14.872 927.98165 993.27217 37.695499 075 1917 113.962 -14.872 927.98165 975.91743 27.675735 076 1917 115.27 -14.872 927.98165 958.63914 17.700111 0

870

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Water at Project Grade (levees) 875

Report generated using GeoStudio 2007, version 7.15. Copyright © 1991-2009 GEO-SLOPE International Ltd.

101.0 FILE INFORMATION

Created By: Goetz, Ryan MVSRevision Number: 74Last Edited By: Goetz, Ryan MVS 880Date: 3/5/2010Time: 10:57:29 AMFile Name: Location 3 - 35k cfs - Main Channel_R-60.3-LU_1on4.5 Slope.gszDirectory: C:\Documents and Settings\B3ECGRPG\My Documents\White Ditch\Last Solved Date: 3/5/2010 885Last Solved Time: 11:07:39 AM

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102.0 PROJECT SETTINGS

Length(L) Units: feet

Time(t) Units: Seconds

Force(F) Units: lbf 890

Pressure(p) Units: psfStrength Units: psfUnit Weight of Water: 62.4 pcfView: 2D

103.0 ANALYSIS SETTINGS 895103.1 Water at Project Grade (levees)

Description: Active and Passive Wedge MethodKind: SLOPE/WMethod: Spencer

Settings 900

Apply Phreatic Correction: NoPWP Conditions Source: Piezometric LineUse Staged Rapid Drawdown: No

SlipSurface

Direction of movement: Right to Left 905

Use Passive Mode: NoSlip Surface Option: BlockCritical slip surfaces saved: 1Optimize Critical Slip Surface Location: YesTension Crack 910

Tension Crack Option: (none)

FOS Distribution

FOS Calculation Option: Constant

Restrict Block Crossing: YesAdvanced 915

Number of Slices: 75Optimization Tolerance: 0.01Minimum Slip Surface Depth: 0.1 ftOptimization Maximum Iterations: 5000

Optimization Convergence Tolerance: 1e-007 920

Starting Optimization Points: 8

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Ending Optimization Points: 16Complete Passes per Insertion: 1Driving Side Maximum Convex Angle: 5 °Resisting Side Maximum Convex Angle: 1 ° 925

104.0 MATERIALS104.1 Layer 1 - CL

Model: Mohr-Coulomb

Unit Weight: 100 pcf

Cohesion: 400 psf 930Phi: 0 °

Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

104.2 Layer 4 - CL 935

Model: Mohr-Coulomb

Unit Weight: 107 pcf

Cohesion: 550 psf

Phi: 0 °

Phi-B: 0 ° 940

Pore Water Pressure

Piezometric Line: 1

104.3 Layer 6 - CL

Model: Mohr-Coulomb

Unit Weight: 101 pcf 945

Cohesion: 780 psf

Phi: 0 °

Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1 950

104.4 Layer 7 - CL

Model: S=f(depth)Unit Weight: 101 pcf

C-Top of Layer: 500 psfC-Rate of Change: 14 psf/ft 955

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Limiting C: 1200 psfPore Water Pressure

Piezometric Line: 1

104.5 Layer 9 - CL

Model: Mohr-Coulomb 960Unit Weight: 115 pcf

Cohesion: 900 psf

Phi: 0 °

Phi-B: 0 °

Pore Water Pressure 965

Piezometric Line: 1

104.6 Layer 2 - ML

Model: Mohr-Coulomb

Unit Weight: 117 pcf

Cohesion: 200 psf 970Phi: 15 °Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

104.7 Layer 5 - ML 975

Model: Mohr-Coulomb

Unit Weight: 117 pcf

Cohesion: 200 psf

Phi: 15 °Phi-B: 0 ° 980

Pore Water Pressure

Piezometric Line: 1

104.8 Layer 8 - ML

Model: Mohr-Coulomb

Unit Weight: 117 pcf 985

Cohesion: 200 psf

Phi: 15 °Phi-B: 0 °

Pore Water Pressure

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Piezometric Line: 1 990

104.9 Layer 3 - SM

Model: Mohr-Coulomb

Unit Weight: 122 pcf

Cohesion: 0 psfPhi: 30 ° 995Phi-B: 0 °

Pore Water Pressure

Piezometric Line: 1

104.10 Layer 10 - SM

Model: Mohr-Coulomb 000Unit Weight: 122 pcf

Cohesion: 0 psfPhi: 30 °Phi-B: 0 °

Pore Water Pressure 005

Piezometric Line: 1

105.0 SLIP SURFACE LIMITS

Left Coordinate: (-200, 2) ft

Right Coordinate: (300, -16) ft

106.0 SLIP SURFACE BLOCK 010

Left Grid

Upper Left: (-22, 0.75) ftLower Left: (-22, -44) ftLower Right: (3.25, -44) ftX Increments: 10 015

Y Increments: 10Starting Angle: 135 °Ending Angle: 180 °Angle Increments: 3

Right Grid 020

Upper Left: (9.5, 0.75) ftLower Left: (9.5, -44) ftLower Right: (31.7145, -44) ftX Increments: 10

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Y Increments: 10 025Starting Angle: 45 °Ending Angle: 65 °Angle Increments: 3

107.0 PIEZOMETRIC LINES107.1 Piezometric Line 1 030

107.1.1Coordinates

X (ft) Y (ft)

-160 2

-6 2

12 622 6

300 6

108.0 REGIONS

Material Points Area (ft2)

Region 1 Layer 10 - SM 20,21,15,11 9500Region 2 Layer 9 - CL 20,10,14,21 5500Region 3 Layer 8 - ML 10,9,13,14 5500Region 4 Layer 5 - ML 18,19,12,23 5750Region 5 Layer 4 - CL 8,18,23,22 2750Region 6 Layer 1 - CL 1,2,3,4,28,7,24,16 3316Region 7 Layer 2 - ML 17,16,24,25 1212Region 8 Layer 3 - SM 17,25,5,6,22,8 4633Region 9 Layer 6 - CL 19,26,27,12 4500Region 10 Layer 7 - CL 26,9,13,27 27000

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109.0 POINTS

X (ft) Y (ft)

Point 1 -200 2Point 2 -6 2Point 3 12 6Point 4 22 6Point 5 121 -16Point 6 300 -16Point 7 58 -2Point 8 -200 -24Point 9 -200 -104Point 10 -200 -115Point 11 -200 -145Point 12 300 -41Point 13 300 -104Point 14 300 -115Point 15 300 -145Point 16 -200 -10Point 17 -200 -14Point 18 -200 -29.5Point 19 -200 -41Point 20 -200 -126Point 21 300 -126Point 22 300 -24

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Point 23 300 -29.5Point 24 94 -10Point 25 112 -14Point 26 -200 -50Point 27 300 -50Point 28 49 0

110.0 CRITICAL SLIP SURFACES

Slip Surface FOS Center (ft) Radius (ft) Entry (ft) Exit (ft)

1 Optimized 5.148 (-0.197, 5.597) 22.84998 (27.7539, 4.72135) (-21.8475, 2)2 7261 5.447 (-0.197, 5.597) 24.266 (27.0523, 4.87727) (-27.2178, 2)

110.1 Slices of Slip Surface: Optimized 035

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 Optimized -21.49106 1.6675915 20.742061 110.4554 0 4002 Optimized -20.778165 1.002774 62.227208 178.61419 0 4003 Optimized -20.06527 0.33795625 103.71543 246.77297 0 4004 Optimized -19.352375 -0.32686125 145.19135 314.9215 0 4005 Optimized -18.628945 -0.984035 186.20427 378.02018 0 4006 Optimized -17.89497 -1.633565 226.73049 444.52317 0 4007 Optimized -17.160995 -2.283095 267.2669 511.02615 0 4008 Optimized -16.42702 -2.932625 307.79311 577.53934 0 4009 Optimized -15.699745 -3.5610085 347.00806 637.79273 0 400

10 Optimized -14.97918 -4.168245 384.89359 699.89528 0 40011 Optimized -14.258615 -4.7754815 422.78972 761.99783 0 40012 Optimized -13.53108 -5.371695 459.99868 818.30547 0 400

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13 Optimized -12.796585 -5.956885 496.51192 878.07474 0 40014 Optimized -12.062095 -6.542075 533.02516 937.85466 0 40015 Optimized -11.3276 -7.127265 569.5384 997.62392 0 40016 Optimized -10.622345 -7.675958 603.7853 1049.4703 0 40017 Optimized -9.946339 -8.188154 635.73786 1101.7381 0 40018 Optimized -9.270335 -8.70035 667.7022 1153.9941 0 40019 Optimized -8.594329 -9.212546 699.66654 1206.2972 0 40020 Optimized -7.918323 -9.724742 731.61909 1258.5296 0 40021 Optimized -7.177338 -10.22512 762.84827 1289.0446 140.99387 20022 Optimized -6.387178 -10.7041 792.73822 1346.7406 148.44449 20023 Optimized -5.6616215 -11.14392 824.86688 1407.6529 156.15703 20024 Optimized -4.984865 -11.55416 859.85603 1472.7284 164.21865 20025 Optimized -4.3081085 -11.9644 894.84517 1537.8039 172.28027 20026 Optimized -3.633315 -12.28104 923.95438 1558.7577 170.09504 20027 Optimized -2.960485 -12.504075 947.20384 1600.5165 175.05459 20028 Optimized -2.287655 -12.72711 970.4533 1642.2752 180.01413 20029 Optimized -1.614825 -12.950145 993.70275 1684.0339 184.97368 20030 Optimized -0.941995 -13.17318 1016.9381 1725.7927 189.93701 20031 Optimized -0.24735 -13.31199 1035.2437 1726.4268 185.20195 20032 Optimized 0.46911 -13.36657 1048.5764 1748.8335 187.63332 20033 Optimized 1.18557 -13.421155 1061.923 1771.2402 190.06097 20034 Optimized 1.90203 -13.47574 1075.2556 1793.6468 192.49234 20035 Optimized 2.61849 -13.53032 1088.6022 1816.0535 194.91998 20036 Optimized 3.333657 -13.492205 1096.1466 1795.4956 187.39002 200

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37 Optimized 4.047531 -13.36139 1097.8827 1796.0468 187.07251 20038 Optimized 4.761405 -13.230575 1099.6188 1796.5979 186.755 20039 Optimized 5.475279 -13.09976 1101.3549 1797.2869 186.47441 20040 Optimized 6.189153 -12.968945 1103.091 1797.838 186.1569 20041 Optimized 6.883003 -12.749075 1098.9832 1755.238 175.84293 20042 Optimized 7.556829 -12.44015 1089.0543 1734.4628 172.93668 20043 Optimized 8.230655 -12.131225 1079.1253 1713.8224 170.06657 20044 Optimized 8.904481 -11.8223 1069.1829 1693.1821 167.20008 20045 Optimized 9.578307 -11.513375 1059.254 1672.4068 164.29382 20046 Optimized 10.213105 -11.132425 1044.279 1610.3449 151.6769 20047 Optimized 10.80887 -10.679455 1024.2766 1572.1306 146.79703 20048 Optimized 11.404635 -10.226485 1004.2743 1533.7827 141.88136 20049 Optimized 11.85126 -9.88691 989.29305 1498.3361 0 40050 Optimized 12.29563 -9.54905 970.26688 1468.4735 0 40051 Optimized 12.886885 -9.09951 942.20876 1424.3129 0 40052 Optimized 13.528845 -8.575649 909.52568 1361.5405 0 40053 Optimized 14.221515 -7.9774675 872.19012 1303.0842 0 40054 Optimized 14.914185 -7.379286 834.86549 1244.5186 0 40055 Optimized 15.60686 -6.781104 797.54086 1186.0623 0 40056 Optimized 16.299535 -6.1829225 760.21623 1127.606 0 40057 Optimized 16.992205 -5.584741 722.89159 1069.0841 0 40058 Optimized 17.636515 -5.004634 686.6832 1004.2731 0 40059 Optimized 18.232465 -4.442602 651.6233 949.42488 0 40060 Optimized 18.82842 -3.88057 616.5512 894.58886 0 400

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61 Optimized 19.424375 -3.318538 581.4791 839.75284 0 40062 Optimized 20.020325 -2.756506 546.407 784.90462 0 40063 Optimized 20.598585 -2.193963 511.3012 724.2217 0 40064 Optimized 21.15915 -1.6309085 476.17316 669.3711 0 40065 Optimized 21.719715 -1.0678541 441.03253 614.52051 0 40066 Optimized 22.32385 -0.4610388 403.17016 552.74136 0 40067 Optimized 22.971555 0.189538 362.5721 484.03947 0 40068 Optimized 23.61926 0.8401147 321.97405 415.33759 0 40069 Optimized 24.26696 1.4906915 281.37599 346.6357 0 40070 Optimized 24.90712 2.1065175 242.94941 288.5148 0 40071 Optimized 25.53974 2.687592 206.69734 226.56963 0 40072 Optimized 26.17236 3.2686665 170.43363 164.62445 0 40073 Optimized 26.80498 3.8497415 134.18156 102.6851 0 40074 Optimized 27.4376 4.430816 97.916682 40.739924 0 400

110.2 Slices of Slip Surface: 7261

Slip

Surface X (ft) Y (ft) PWP (psf) Base Normal Stress (psf) Frictional Strength (psf) Cohesive Strength (psf)

1 7261 -26.85949 1.7931035 12.909833 66.031792 0 4002 7261 -26.142775 1.3793105 38.730709 108.05158 0 4003 7261 -25.426065 0.96551735 64.551584 150.075 0 4004 7261 -24.709355 0.55172415 90.372459 192.08875 0 4005 7261 -23.992645 0.13793104 116.19333 234.1025 0 4006 7261 -23.275935 -0.27586206 142.01542 276.12834 0 4007 7261 -22.559225 -0.68965515 167.8375 318.14209 0 4008 7261 -21.842515 -1.1034484 193.65958 360.16792 0 400

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9 7261 -21.125805 -1.5172415 219.48167 402.18167 0 400

10 7261 -20.409095 -1.9310345 245.29167 444.2075 0 40011 7261 -19.692385 -2.3448275 271.11375 486.22125 0 40012 7261 -18.975675 -2.7586205 296.93584 528.24709 0 40013 7261 -18.258965 -3.1724135 322.75792 570.26084 0 40014 7261 -17.542255 -3.5862065 348.58 612.27459 0 40015 7261 -16.825545 -4 374.40209 654.30042 0 40016 7261 -16.10883 -4.4137935 400.22417 696.31417 0 40017 7261 -15.392115 -4.8275865 426.04625 738.34001 0 40018 7261 -14.675405 -5.2413795 451.85625 780.35376 0 40019 7261 -13.958695 -5.6551725 477.67834 822.37959 0 40020 7261 -13.241985 -6.0689655 503.50042 864.39334 0 40021 7261 -12.525275 -6.4827585 529.3225 906.40709 0 40022 7261 -11.808565 -6.8965515 555.14459 948.43292 0 40023 7261 -11.091855 -7.3103445 580.96667 990.44667 0 40024 7261 -10.375145 -7.7241375 606.78876 1032.4725 0 40025 7261 -9.6584345 -8.137931 632.61084 1074.4863 0 40026 7261 -8.9417235 -8.5517245 658.43292 1116.5121 0 40027 7261 -8.2250125 -8.9655175 684.24292 1158.5258 0 40028 7261 -7.508302 -9.3793105 710.06501 1200.5396 0 40029 7261 -6.7915915 -9.7931035 735.88709 1242.5292 0 40030 7261 -6.216618 -10.125065 756.61004 1271.4447 137.94953 20031 7261 -5.65 -10.4522 781.87246 1318.8329 143.87813 20032 7261 -4.95 -10.856345 816.79802 1383.5374 151.85736 200

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33 7261 -4.25 -11.26049 851.72359 1448.2419 159.83659 20034 7261 -3.55 -11.664635 886.64915 1513.0701 167.84897 20035 7261 -2.85 -12.06878 921.57472 1577.7745 175.82821 20036 7261 -2.15 -12.472925 956.50029 1642.479 183.80744 20037 7261 -1.446875 -12.675 978.86018 1616 170.7211 20038 7261 -0.740625 -12.675 988.64425 1631.7168 172.31077 20039 7261 -0.034375 -12.675 998.44248 1647.292 173.85871 20040 7261 0.671875 -12.675 1008.2407 1663.0088 175.44459 20041 7261 1.378125 -12.675 1018.0248 1678.7257 177.03427 20042 7261 2.084375 -12.675 1027.823 1694.4425 178.62015 20043 7261 2.790625 -12.675 1037.6212 1710.1593 180.20603 20044 7261 3.496875 -12.675 1047.4053 1725.8761 181.7957 20045 7261 4.203125 -12.675 1057.2035 1741.5929 183.38158 20046 7261 4.909375 -12.675 1067.0018 1757.3097 184.96746 20047 7261 5.615625 -12.675 1076.7858 1773.0265 186.55714 20048 7261 6.321875 -12.675 1086.5841 1788.7434 188.14302 20049 7261 7.028125 -12.675 1096.3823 1804.3186 189.69096 200

50 7261 7.734375 -12.675 1106.1664 1820.0354 191.28063 20051 7261 8.440625 -12.675 1115.9646 1835.7522 192.86651 20052 7261 9.146875 -12.675 1125.7628 1851.469 194.45239 20053 7261 9.916665 -12.258335 1110.4691 1708.5118 160.24508 20054 7261 10.75 -11.425 1069.9943 1633.1625 150.90048 20055 7261 11.583335 -10.591665 1029.5195 1557.8132 141.55588 20056 7261 12.0875 -10.0875 1003.8491 1510.3799 135.72453 20057 7261 12.525895 -9.649107 976.50832 1455.0494 0 400

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58 7261 13.22768 -8.9473215 932.70873 1386.6346 0 40059 7261 13.929465 -8.245536 888.91921 1318.3205 0 40060 7261 14.63125 -7.54375 845.12969 1249.9057 0 40061 7261 15.333035 -6.841964 801.34016 1181.5916 0 40062 7261 16.03482 -6.1401785 757.55064 1113.1768 0 40063 7261 16.736605 -5.438393 713.75105 1044.7619 0 40064 7261 17.438395 -4.736607 669.96153 976.41764 0 40065 7261 18.14018 -4.0348215 626.17201 908.04312 0 40066 7261 18.841965 -3.333036 582.38249 839.65851 0 40067 7261 19.54375 -2.63125 538.59297 771.28399 0 40068 7261 20.245535 -1.929464 494.80345 702.90946 0 40069 7261 20.94732 -1.2276783 451.00385 634.53494 0 40070 7261 21.649105 -0.52589285 407.21433 566.16041 0 40071 7261 22.360875 0.1858766 362.80522 493.85087 0 40072 7261 23.08263 0.9076296 317.76807 417.59045 0 40073 7261 23.804385 1.629383 272.73092 341.33983 0 40074 7261 24.526135 2.3511365 227.69378 265.07941 0 40075 7261 25.24789 3.0728895 182.64684 188.82879 0 40076 7261 25.969645 3.7946425 137.60969 112.57817 0 40077 7261 26.691395 4.516396 92.576464 36.322649 0 400

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L6. Environmental Engineering

The proposed project will make beneficial use of dredge spoil produced. Dredged material from

3040 the proposed channel enhancement features, in addition to any other spoil available, will allow

new areas of marsh to be created.

Regenerative planting, with native species, will be done to stabilize the placed dredge spoil and

prevent return of the material to the waterway. The use of native species plantings to quickly

3045 establish targeted vegetative communities will assist in reducing the risk of invasive species

impacts. Native vegetation will trap sediment following into the marsh from the proposed

project, accreting additional marsh area over time.

3050 L7. Civil Design Criteria

L7.1 Site Recommendations

Multiple features were considered to reintroduce and distribute Mississippi River water into the

3055 marsh. An inlet and outfall channel, working in conjunction with a structure, would feed

distributary channels containing strategically positioned culverts or openings that allow sediment

and freshwater to flow into the marsh. Notched dikes to constrict flow, but still allow boat traffic

through, would be placed in key locations to prevent the loss of the valuable sediments and

nutrients from the freshwater diversion. Areas of new marsh would be created from dredged

3060 material out of the proposed channel enhancement features as well as any other beneficial spoil

that is available.

Four alternatives, utilizing box culverts described in section C8, were considered at Location 2,

White Ditch, LA. Six alternatives, utilizing box culverts and siphons, also described in section

3065 C8, were considered at Location 3, Phoenix, LA.

Modeling was done with Bentley InRoads XM Edition v08. Data used for the modeling

included a topographic survey of the marsh area performed by FTN Associates, LTD (July 2009)

and LIDAR flown within approximately 250 feet of the levee corridor. The topographic survey

3070 contained points, but the cross-sectional data was spread out over a large area, with crosssections ranging from 915 feet apart to 3850 feet apart. Quantities were prepared by analyzing

the proposed channel areas and using the closes cross-sectional data along the channel until the

proposed channel changed.

3075 The following assumptions were made concerning Marsh Creation:

• Berm: 6’ tall (feasibility quantities only – during construction contractor shall maintain a

berm height of 5’), 10’ crown, 1 on 6 side slopes.

• This material will be pushed up from the interior of the footprint of the marsh creation area.

• Excavation will be in the wet, material will settle under its own weight.

3080 • 1 unit of material pushed up with no compaction will result in 0.75 units in the containment

dike.

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• In marsh areas with no compaction, 1 unit dredged from the channel will result in 1 unit in

the marsh creation area.

• All material for marsh creation will be all excess material dredged from the channel not

3085 used for the side berms on the channel.

• Marsh areas are calculated to be 4’ thick

L7.2 Civil Site Design for Diversion Facility

3090 L7.2.1 General

Ten alternatives were studied for this proposed diversion project. Each alternative consists of, at

a minimum, an inlet channel, structure, outfall structure with a concrete apron, outfall channel,

system of distributary channels in the marsh with culverts or cutoffs to smaller channels and

3095 plugs at Oak River. Following is a description of the features that will hold constant for each

alternative, although quantities will change according to design template:

• Inlet: entire length will be reinforced with rock, on both side slopes and 15 feet past the

top of the new bank. Top of rock should be the same elevation as the top of natural

3100 ground. Layers will match 400lb rip protection.

• Outlet: at the end of the concrete apron for 100 feet there will be 1000 lb rip protection.

At 100 feet, transitions to 400lb rip rap protection.

• At culverts and cutoffs to smaller channels, anywhere there is a velocity change there will

be 400lb rip rap for a minimum of 100 feet each side of cutoff.

3105 • Rock protection, 400lb rip rap, will be placed adjacent to the box culvert and as

protection for the proposed road perpendicular to the structure.

• 400lb protection:

Geotextile

12” bedding material

3110 Geogrid

12” bedding material

30” 400lb rip rap

• 1000lb protection:

Geotextile

3115 12” bedding material

Geogrid

12” bedding material

42” 1000lb rip rap

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3120 L7.2.2 Alternatives Array

Below are the alternatives for the proposed diversion project:

Alternative Location Outfall Capacity Structure

2B 2 5,000 cfs 3-box culvert

2D 2 10,000 cfs 3-box culvert

2E 2 15,000 cfs 10-box culvert

2F 2 35,000 cfs 10-box culvert

3A 3 5,000 cfs 30-pipe siphon

3B 3 5,000 cfs 3-box culvert

3C 3 10,000 cfs 30-pipe siphon

3D 3 10,000 cfs 3-box culvert

3E 3 15,000 cfs 10-box culvert

3F 3 35,000 cfs 10-box culvert

Table 1

3125

L7.2.3 Description of Civil Site Alternatives

Plan views of the alternatives are shown on the following plates:

Alternative Location Outfall Capacity Sheet

2B 2 5,000 cfs C1

2D 2 10,000 cfs C2

2E 2 15,000 cfs C3

2F 2 35,000 cfs C4

3B 3 5,000 cfs C5

3D 3 10,000 cfs C6

3E 3 15,000 cfs C7

3F 3 35,000 cfs C8

3130 Table 2

Quantities for the alternatives are shown in the tables below:

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3135 Location 2

15’ x 15’ Box Culverts

3310 10

5,000 cfs 10,000 cfs 15,000 cfs 35,000 cfs

Excavation CY 1,487,300 2,316,200 4,962,000 6,278,700

Berm Fill CY 116,600 98,300 99,600 122,900

Marsh Creation CY 1,371,000 2,218,000 4,863,000 6,156,000

Bedding Material TN 487,300 528,200 595,200 746,400

400 lb. Riprap TN 444,200 478,700 545,500 692,000

1000lb. RipRap TN 12,100 13,500 13,400 19,200

Geotextile SY 179,900 218,500 290,100 368,100

Geogrid SY 179,900 218,500 290,100 368,100

36" Culvert Pipe LF 3,000 3,130 5,220 7,830

36" Flared End Section EA 104 156 260 390

Striping AC 75 75 75 75

Clearing & Grubbing AC 15 15 15 15

Road Removal SY 270 270 270 270

9" Cement Treated SY 270 270 270 270

Sand Shell Base

3.5" Asphaltic SY 270 270 270 270

Concrete Binder Course

1.5" Asphaltic SY 270 270 270 270

Concrete Wearing Course

Remove & Dispose of SY 950 950 950 950

Articulated Concrete Mat

Install Articulated SY 950 950 950 950

Concrete Mat

Dewatering LS 1 1 1 1

Real Estate Costs LS 1 1 1 1

Table 3

3140

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Location 2

30 Pipe Siphon

5,000 cfs 10,000cfs

Excavation CY 1,506,800 2,237,300

Berm Fill CY 116,600 98,300

Marsh Creation CY 1,390,000 2,139,000

Bedding Material TN 326,500 363,700

400 lb. Riprap TN 256,400 324,500

1000lb. RipRap TN 12,100 13,500

Geotextile SY 123,500 149,300

Geogrid SY 123,500 149,300

Striping AC 75 75

Clearing & Grubbing AC 15 15

36" Culvert Pipe LF 2,100 3,130

36" Flared End Section EA 104 156

Road Removal SY 1,210 1,210

9" Cement Treated Sand Shell Base SY 1,210 1,210

Sand Shell Base

3.5" Asphaltic SY 1,210 1,210

Concrete Binder Course

1.5" Asphaltic Concrete Wearing Course SY 1,210 1,210

Concrete Wearing Course

Remove & Dispose of SY 1,880 1,880

Articulated Concrete Mat

Install Articulated SY 1,880 1,880

Concrete Mat

Dewatering LS 1 1

Real Estate Costs LS 1 1

Table 4

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3145

Location 3

15’ x 15’ Box Culverts

3 3 10 10

5,000 cfs 10,000 cfs 15,000 cfs 35,000 cfs

Excavation CY 2,081,200 2,562,600 3,377,300 5,241,500

Fill CY 2,080,500 2,561,500 3,370,500 524,500

Berms for Marsh Creation CY 912,900 1,215,000 2,144,000 3,766,000

Bedding Material TN 264,300 269,800 271,700 279,200

400 lb. Riprap TN 268,000 272,700 273,500 284,300

1000lb. RipRap TN 4,700 6,100 7,700 11,800

Geotextile SY 197,800 199,700 201,500 202,500

Geogrid SY 197,800 199,700 201,500 202,500

Striping AC 35 35 35 35

Clearing & Grubbing AC 8 10 13 19

Road Removal SY 725 725 1,130 1,130

9" Cement Treated SY 725 725 1,130 1,130

Sand Shell Base

3.5" Asphaltic SY 725 725 1,130 1,130

Concrete Binder Course

1.5" Asphaltic SY 725 725 1,130 1,130

Concrete Wearing Course

Remove & Dispose of SY 610 610 940 940

Articulated Concrete Mat

Install Articulated SY 610 610 940 940

Concrete Mat

Dewatering LS 1 1 1 1

Real Estate Costs LS 1 1 1 1

Table 5

3150

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Location 3

30 Pipe Siphon

5,000 cfs 10,000cfs

Excavation CY 2,114,300 2,575,800

Fill CY 2,114,300 2,575,800

Berms for Marsh Creation CY 912,900 1,215,500

Bedding Material TN 266,900 268,400

400 lb. Riprap TN 268,300 269,500

1000lb. RipRap TN 8,800 9,000

Geotextile SY 262,300 263,100

Geogrid SY 262,300 263,100

Striping AC 35 35

Clearing & Grubbing AC 8 10

Road Removal SY 1,370 1,370

9" Cement Treated Sand Shell Base SY 1,370 1,370

Sand Shell Base

3.5" Asphaltic SY 1,370 1,370

Concrete Binder Course

1.5" Asphaltic Concrete Wearing Course SY 1,370 1,370

Concrete Wearing Course

Remove & Dispose of SY 0 0

Articulated Concrete Mat

Install Articulated SY 0 0

Concrete Mat

Dewatering LS 1 1

Real Estate Costs LS 1 1

3155 Table 6

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L-290

160

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L8. Structural Design Criteria

3165

L8.1 FOUNDATION RECOMMENDATIONS

L8.1.1 General

3170 Development of this proposed diversion project would require various proposed features to

accomplish the intended purpose. Among those would be a variety of structures. A description of

the foundations for each structural feature will be shown below. The pile founded structures

would incorporate the use of steel H-piles and sheet piles, precast prestressed concrete (PPC)

piles, timber piles, and steel pipe piles where indicated on the drawings. Preliminary assumptions

3175 of pile sizes, spacing, and pile tip elevations were based on the design of similar structures found

in the vicinity. Verification of the pile assumptions, along with any adjustments, was

accomplished with the use of pile capacity curves that were developed for similar soils. A more

accurate determination of soil properties was not possible due to the absence of reliable borings;

therefore pile tip elevations may be adjusted in the next stage of design. All cast-in-place

3180 concrete structure monoliths exposed to lateral loadings were analyzed using the COE CASE

program “CPGA” (X0080), Pile Group Analysis Program to determine adequacy of pile pattern

assumptions. All designs were performed in accordance with applicable COE and technical

publications, and industry codes. All structures will be constructed using conventional

construction equipment and techniques. The contractor will be required to provide dewatering

3185 systems (where necessary) in order to construct foundations in a near dry atmosphere. The

contractor will also be required to provide a system of shoring or open excavation to safely

facilitate construction procedures.

L8.1.2 Description of Feature Foundations

3190

a. Project Feature 3-15’x15’ Gated Box Culverts. – The proposed concrete monolithic

structures at this location will be supported on a combination of steel HP14x73 piles,

12”x12” PPC piles, and 14”x14” PPC piles. Location, spacing, and pile tip elevations of

the piling is shown on drawings S-102, and S-103. A 4” stabilization slab will be placed

3195 between the concrete substructures and the soil foundation to act as a stable working

surface during construction. A steel sheet pile seepage cut-off wall will be placed

around the perimeter of the concrete substructures. The pile tip elevations of the cut-off

walls are shown on drawing S-201.

3200 b. Project Feature 10-15’x15’ Gated Box Culverts. – The proposed concrete monolithic

structures at this location will be supported on a combination of steel HP14x73 piles,

12”x12” PPC piles, and 14”x14” PPC piles. Location, spacing, and pile tip elevations of

the piling is shown on drawings S-111, S-112, and S-113. A 4” stabilization slab will be

placed between the concrete substructures and the soil foundation to act as a stable

3205 working surface during construction. A steel sheet pile seepage cut-off wall will be

placed around the perimeter of the concrete substructures. The pile tip elevations of the

cut-off walls are shown on drawing S-210.

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c. Project Feature 4,000’ Gated Weir. – The proposed concrete monolithic structures at

3210 this location will be supported on 18”x18” PPC piles. Location, spacing, and pile tip

elevations of the piling is shown on drawing S-220. A 4” stabilization slab will be

placed between the concrete substructures and the soil foundation.

d. Project Feature 3,000’ Gated Weir. – The proposed concrete monolithic structures at

3215 this location will be supported on 18”x18” PPC piles. Location, spacing, and pile tip

elevations of the piling is shown on drawing S-230. A 4” stabilization slab will be

placed between the concrete substructures and the soil foundation.

e. Project Feature 2,000’ Gated Weir. – The proposed concrete monolithic structures at

3220 this location will be supported on 18”x18” PPC piles. Location, spacing, and pile tip

elevations of the piling is shown on drawing S-240. A 4” stabilization slab will be

placed between the concrete substructures and the soil foundation.

f. Project Feature 19-6’ Dia. Pipe Siphon. – The substructures for this proposed feature

3225 will be 16 inch diameter steel pipe piles located at the intake end of the siphon which

will provide a support system for the 6’ diameter pipes, and 16 inch dia. steel pipe piles

located at the riverward end of the excavated inlet channel which will support a

protective dolphin and floating boom system. The support system for the 6’ diameter

pipes, and the protective dolphins will be supported with both vertical and battered pipe

3230 piles. The pile tip elevation of the vertical pipe piles for the 6’ dia. pipe support system

will be El.-90.0, and the pile tip elevation for the battered pipe piles will be El.-85.0.

The pile tip elevation of the vertical pipe piles for the protective dolphins will be El.-

80.0, and the pile tip elevation for the battered pipe piles will be El.-85.0. It is assumed

the bedding system for the 6’ diameter pipe will be determined at a later design stage.

3235 Location and pile tip elevations for the pipe piling is shown on drawing S-250.

g. Project Feature 30-6’ Dia. Pipe Siphon. – The substructures for this proposed feature

will be 16 inch diameter steel pipe piles located at the intake end of the siphon, which

will provide a support system for the 6’ diameter pipes, and 16 inch dia. steel pipe piles

3240 located at the riverward end of the excavated inlet channel which will support a

protective dolphin and floating boom system. The support system for the 6’ diameter

pipes, and the protective dolphins will be supported with both vertical and battered pipe

piles. The pile tip elevation of the vertical pipe piles for the 6’ dia. pipe support system

will be El.-90.0, and the pile tip elevation for the battered pipe piles will be El.-85.0.

3245 The pile tip elevation of the vertical pipe piles for the protective dolphins will be El.-

80.0, and the pile tip elevation for the battered pipe piles will be El.-85.0. It is assumed

the bedding system for the 6’ diameter pipe will be determined at a later design stage.

Location and pile tip elevations for the pipe piling is shown on drawing S-260.

3250

L8.2 STRUCTURAL DESIGN FOR DIVERSION FACILITY

L8.2.1 General

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3255 The general physical configuration of structures for this proposed diversion project were based

on a variety of considerations, among them hydraulic requirements, similar structures performing

the same function, and utilizing existing designs from other projects. All concrete structures will

be reinforced and cast-in-place. Concrete and structural steel member sizes were assumed based

on similar structures of equivalent size with similar loadings, therefore, no stress analyses were

3260 performed in this design phase.

L8.2.2 Description of Structural Features

a. Project Feature 3-15’x15’ Gated Box Culverts. – The proposed structures at this

3265 location will be a series of reinforced cast-in-place concrete box culverts constructed

monolithically in conjunction with inflow, roller gate, bulkhead, and T-wall monoliths.

These structures will be located under an existing earth levee. There will be three box

culvert barrels, each 15 feet high and 15 feet wide (inside dimensions). The flow line

elevation inside the barrels will be El.-15.0. The box culverts base slab will be 4.0 feet

3270 thick, the top slab will be 3.0 feet thick, the interior vertical walls will be 2.5 feet thick,

and the exterior vertical walls will be 3.0 feet thick. The length of the box culverts will

be 160.0 feet. The concrete inflow monoliths on the upstream end of the structure will

be comprised of a 4.0 foot thick base slab and two 3.0 foot thick vertical guidewalls

providing a length of 150.0 feet. The upstream end of the inflow monoliths will flare

3275 from 56.0 to 96.0 feet in width. The roller gate monolith will be 59.0 feet long and 56.0

feet wide. The concrete bulkhead monolith on the downstream end of the structure will

also be comprised of a 4.0 foot thick base slab and two 3.0 foot thick vertical

guidewalls providing a length of 95.0 feet and a width of 56.0 feet. The concrete Twalls which retain the earth embankment, will be located at the downstream end of the

3280 bulkhead monolith, on both sides of the channel. Two T-walls will be located on each

side of the channel, and oriented 55 degrees from the centerline of the channel. Each Twall will be 36.0 feet long, with a top of stem elevation of El.+6.0. All the T-wall bases

will be 3.0 feet thick, and the vertical stem thicknesses will vary. The foundation

elevation of the T-walls nearest the bulkhead monolith will be El.-23.0, and the

3285 remaining T-walls will be founded at El.-15.0. The inflow channel bottom will be El.-

16.0, with a width of 96.0 feet and side slopes of 1 vert. on 3 horiz. The outflow

channel bottom will transition from El.-16.0 at the bulkhead monolith to El.-20.0, 100.0

feet from the concrete structure with a width of 50.0 feet and side slopes of 1 vert. on 3

horz. Vertical slots and structural steel roller guides will be provided in the concrete

3290 walls at each end of the barrels for the placement of a bulkhead, when required. A 15

foot high and 15 foot wide fabricated structural steel roller gate will be located at the

upstream end of each barrel. A flush bottom closure for the gates will be accomplished

by providing a steel sill beam assembly at El. -15.0. Vertical slots will be provided in

the concrete sidewalls for the installation of structural steel roller guides. A concrete

3295 platform will be located at El.+17.5 to support the roller gate operators. A machinery

building will be located adjacent to the support platform, also at El.+17.5. A 2.0 foot

thick vertical concrete seepage cut-off wall extending from the top of the box culverts

toEl.+13.0 will be located on the roller gate monolith near the centerline of the earth

levee. A 17.0 foot wide and 34.0 foot long timber pile supported concrete bulkhead

3300 storage slab will be located on the landside of the levee.

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b. Project Feature 10-15’x15’ Gated Box Culverts. – The proposed structures at this

location will be a series of reinforced cast-in-place concrete box culverts constructed

monolithically in conjunction with inflow, roller gate, bulkhead, and T-wall monoliths.

3305 These structures will be located under an existing earth levee. There will be ten box

culvert barrels, each 15 feet high and 15 feet wide (inside dimensions). The flow line

elevation inside the barrels will be El.-15.0. The box culverts base slab will be 4.0 feet

thick, the top slab will be 3.0 feet thick, the interior vertical walls will be 2.5 feet thick,

and the exterior vertical walls will be 3.0 feet thick. The length of the box culverts will

3310 be 160.0 feet. The concrete inflow monoliths on the upstream end of the structure will

be comprised of a 4.0 foot thick base slab and two 3.0 foot thick vertical guidewalls

providing a length of 150.0 feet. The upstream end of the inflow monoliths will flare

from 178.5 to 218.5 feet in width. The roller gate monolith will be 59.0 feet long and

178.5 feet wide. The concrete bulkhead monolith on the downstream end of the

3315 structure will also be comprised of a 4.0 foot thick base slab and two 3.0 foot thick

vertical guidewalls providing a length of 95.0 feet and a width of 178.5 feet. The

concrete T-walls which retain the earth embankment, will be located at the downstream

end of the bulkhead monolith, on both sides of the channel. Two T-walls will be located

on each side of the channel, and oriented 55 degrees from the centerline of the channel.

3320 Each T-wall will be 36.0 feet long, with a top of stem elevation of El.+6.0. All the Twall bases will be 3.0 feet thick, and the vertical stem thicknesses will vary. The

foundation elevation of the T-walls nearest the bulkhead monolith will be El.-23.0, and

the remaining T-walls will be founded at El.-15.0. The inflow channel bottom will be

El.-16.0, with a width of 218.5 feet and side slopes of 1 vert. on 3 horiz. The outflow

3325 channel bottom will transition from El.-16.0 at the bulkhead monolith to El.-20.0, 100.0

feet from the concrete structure with a width of 172.5 feet and side slopes of 1 vert. on

3 horz. Vertical slots and structural steel roller guides will be provided in the concrete

walls at each end of the barrels for the placement of a bulkhead, when required. A 15

foot high and 15 foot wide structural steel roller gate will be located at the upstream

3330 end of each barrel. A flush bottom closure for the gates will be accomplished by

providing a steel sill beam assembly at El.-15.0. Vertical slots will be provided in the

concrete sidewalls for the installation of structural steel roller guides. A concrete

platform will be located at El.+17.5 to support the roller gate operators. A machinery

building will be located adjacent to the support platform, also at El.+17.5. A 2.0 foot

3335 thick vertical concrete seepage cut-off wall extending from the top of the box culverts

toEl.+13.0 will be located on the roller gate monolith near the centerline of the earth

levee. A 17.0 foot wide and 34.0 foot long timber pile supported concrete bulkhead

storage slab will be located on the landside of the levee.

3340

c. Project Feature 4,000’ Gated Weir. - The proposed structure at this location will be a

reinforced cast-in-place concrete fresh water diversion control structure incorporating

vertical lift gates, a rail mounted gantry crane and crane bridge, and a highway vehicle

bridge. The 3.5 thick substructure base slab will be founded at El.-5.5, extend 4,007.0

3345 feet, and will be parallel to the vehicle, and gantry crane bridges. The upstream end of

the base slab will include an elevated spillway with a top elevation of El.+8.0. The

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remaining portion of the base slab will serve as a stilling basin with a top of slab

elevation of El.-2.0. The stilling basin will include two rows of baffle blocks located

near the mid point of the stilling basin. The top elevation of the baffle blocks will be

3350 El.+3.0. Concrete divider walls will be located parallel to flow at 22.0 feet on center to

form 182 gate bays, which will contain the vertical lift gates. The divider walls will be

3.0 feet thick and are approx. 45.0 feet long. The divider walls will also provide a

support foundation for the vehicle, and gantry crane bridges. The bridges will extend

43.5 feet beyond each end of the substructure for a total length of 4094.0 feet. The

3355 gantry crane bridge will be located toward the upstream end of the structure, above the

spillway, with a top elevation of El.+20.0. The gantry crane bridge will be constructed

of 4.0 feet deep reinforced cast-in-place T-beams. A steel crane rail will be installed on

each T-beam. The highway vehicle bridge will provide two 12.0 foot driving lanes,

with a top of deck elevation of El.+19.0 and total bridge width of 28.0 feet. The bridge

3360 deck and supporting beams will be reinforced cast-in-place concrete. The top elevation

of the divider walls supporting the bridge beams will be El.+15.5. The vertical

orientation of the lift gates will be made possible with the use of the gantry crane.

When the lift gates are in their lowest position they will rest on the spillway at El.+8.0,

and the top of the gates will be at El.+15.0. When the gates are at their highest position

3365 the bottom of the gate will be at El.+16.0, and the top of the gates will be at El.+23.0.

The lift gates will be fabricated from structural steel and utilize steel rollers. Vertical

slots will be provided in the concrete divider walls for the structural steel lift gate

guides. Also, provisions will be made for installation of dogging devices in the divider

walls in order to retain the lift gates in an open position.

3370

d. Project Feature 3,000’ Gated Weir. - The proposed structure at this location will be a

reinforced cast-in-place concrete fresh water diversion control structure incorporating

vertical lift gates, a rail mounted gantry crane and crane bridge, and a highway vehicle

bridge. The 3.5 thick substructure base slab will be founded at El.-5.5, extend 2.995.0

3375 feet, and will be parallel to the vehicle, and gantry crane bridges. The upstream end of

the base slab will include an elevated spillway with a top elevation of El.+8.0. The

remaining portion of the base slab will serve as a stilling basin with a top of slab

elevation of El.-2.0. The stilling basin will include two rows of baffle blocks located

near the mid point of the stilling basin. The top elevation of the baffle blocks will be

3380 El.+3.0. Concrete divider walls will be located parallel to flow at 22.0 feet on center to

form 136 gate bays, which will contain the vertical lift gates. The divider walls will be

3.0 feet thick and are approx. 45.0 feet long. The divider walls will also provide a

support foundation for the vehicle, and gantry crane bridges. The bridges will extend

43.5 feet beyond each end of the substructure for a total length of 3,082.0 feet. The

3385 gantry crane bridge will be located toward the upstream end of the structure, above the

spillway, with a top elevation of El.+20.0. The gantry crane bridge will be constructed

of 4.0 feet deep reinforced cast-in-place T-beams. A steel crane rail will be installed on

each T-beam. The highway vehicle bridge will provide two 12.0 foot driving lanes,

with a top of deck elevation of El.+19.0 and total bridge width of 28.0 feet. The bridge

3390 deck and supporting beams will be reinforced cast-in-place concrete. The top elevation

of the divider walls supporting the bridge beams will be El.+15.5. The vertical

orientation of the lift gates will be made possible with the use of the gantry crane.

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When the lift gates are in their lowest position they will rest on the spillway at El.+8.0,

and the top of the gates will be at El.+15.0. When the gates are at their highest position

3395 the bottom of the gate will be at El.+16.0, and the top of the gates will be at El.+23.0.

The lift gates will be fabricated from structural steel and utilize steel rollers. Vertical

slots will be provided in the concrete divider walls for the structural steel lift gate

guides. Also, provisions will be made for installation of dogging devices in the divider

walls in order to retain the lift gates in an open position.

3400

e. Project Feature 2,000’ Gated Weir. - The proposed structure at this location will be a

reinforced cast-in-place concrete fresh water diversion control structure incorporating

vertical lift gates, a rail mounted gantry crane and crane bridge, and a highway vehicle

bridge. The 3.5 thick substructure base slab will be founded at El.-5.5, extend 2.005.0

3405 feet, and will be parallel to the vehicle, and gantry crane bridges. The upstream end of

the base slab will include an elevated spillway with a top elevation of El.+8.0. The

remaining portion of the base slab will serve as a stilling basin with a top of slab

elevation of El.-2.0. The stilling basin will include two rows of baffle blocks located

near the mid point of the stilling basin. The top elevation of the baffle blocks will be

3410 El.+3.0. Concrete divider walls will be located parallel to flow at 22.0 feet on center to

form 91 gate bays, which will contain the vertical lift gates. The divider walls will be

3.0 feet thick and are approx. 45.0 feet long. The divider walls will also provide a

support foundation for the vehicle, and gantry crane bridges. The bridges will extend

43.5 feet beyond each end of the substructure for a total length of 2,092.0 feet. The

3415 gantry crane bridge will be located toward the upstream end of the structure, above the

spillway, with a top elevation of El.+20.0. The gantry crane bridge will be constructed

of 4.0 feet deep reinforced cast-in-place T-beams. A steel crane rail will be installed on

each T-beam. The highway vehicle bridge will provide two 12.0 foot driving lanes,

with a top of deck elevation of El.+19.0 and total bridge width of 28.0 feet. The bridge

3420 deck and supporting beams will be reinforced cast-in-place concrete. The top elevation

of the divider walls supporting the bridge beams will be El.+15.5. The vertical

orientation of the lift gates will be made possible with the use of the gantry crane.

When the lift gates are in their lowest position they will rest on the spillway at El.+8.0,

and the top of the gates will be at El.+15.0. When the gates are at their highest position

3425 the bottom of the gate will be at El.+16.0, and the top of the gates will be at El.+23.0.

The lift gates will be fabricated from structural steel and utilize steel rollers. Vertical

slots will be provided in the concrete divider walls for the structural steel lift gate

guides. Also, provisions will be made for installation of dogging devices in the divider

walls in order to retain the lift gates in an open position.

3430

f. Project Feature 19-6’ Dia. Pipe Siphons. - The proposed fresh water diversion

control structure at this location will be comprised of multiple components. The major

component of this structure will be 19-6’ dia. steel discharge pipes spaced at 10.0 feet

on center, and will transport water over an existing levee. The approx. elevation of the

3435 top of the levee is El.+15.0. The pipes will be soil founded at various elevations on the

landside of the levee. The pipes on the riverside of the levee at the water intake point

will be supported with a pile founded structural steel component. The discharge pipe

support structure will be located approx. 90.0 feet riverward from the centerline of the

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existing levee. An inlet channel will be excavated between the waterway and the pipe

3440 support structure. The flow line elevation of the discharge pipes at the support structure

will be El.-10.0. The inlet end of the discharge pipes will be fabricated as a horizontal

line with a bottom elevation of El.-12.5. The pipe support structure will be supported

with 16 inch dia. steel pipe piles placed in pairs between the discharge pipes. The

riverward pile will be placed vertical, and the landward pile will be battered toward the

3445 levee. The support structure will be constructed of various sized structural steel

members fastened to 24 inch dia. steel pipe sleeves. The pipe sleeves will be fastened

over the end of the pipe piles. The pipe piles located at each end of the support structure

will be battered either upstream or downstream depending on the location. Another

component of this structure will be a system comprised of dolphins and floating booms,

3450 designed to restrain or deflect floating debris at the riverward end of the excavated inlet

channel. A total of seven dolphins will be required and spaced at approximately 40.0

feet on center. Each dolphin will be attached to a cluster of three 16 inch dia. steel pipe

piles. Two of the piles adjacent to the floating boom will be oriented in a vertical

position, the third pile will be battered away from the boom. The top elevation of the

3455 vertical piles will be El.+14.0, and the top elevation of the battered piles will be

El.+10.0. The upper portion of the dolphins will be a system constructed of structural

steel members fastened to 24 inch dia. steel pipe sleeves. The pipe sleeves will be

fastened over the end of the pipe piles. A floating boom placed horizontally will extend

between every two dolphins. The booms will be constructed of watertight 24 inch steel

3460 pipe filled with foam, and fastened to the dolphins in a manner to allow the booms to

rise and fall with the surrounding water elevation changes. A platform will be provided

on top of two dolphins to support solar powered lanterns and storage batteries. The

elevation of the top of the platform will be El.+12.5. One lantern will be located at each

end of the dolphin group.

3465

g. Project Feature 30-6’ Dia. Pipe Siphons. - The proposed fresh water diversion control

structure at this location will be comprised of multiple components. The major

component of this structure will be 19-6’ dia. steel discharge pipes spaced at 10.0 feet

on center, and will transport water over an existing levee. The approx. elevation of the

3470 top of the levee is El.+15.0. The pipes will be soil founded at various elevations on the

landside of the levee. The pipes on the riverside of the levee at the water intake point

will be supported with a pile founded structural steel component. The discharge pipe

support structure will be located approx. 90.0 feet riverward from the centerline of the

existing levee. An inlet channel will be excavated between the waterway and the pipe

3475 support structure. The flow line elevation of the discharge pipes at the support structure

will be El.-10.0. The inlet end of the discharge pipes will be fabricated as a horizontal

line with a bottom elevation of El.-12.5. The pipe support structure will be supported

with 16 inch dia. steel pipe piles placed in pairs between the discharge pipes. The

riverward pile will be placed vertical, and the landward pile will be battered toward the

3480 levee. The support structure will be constructed of various sized structural steel

members fastened to 24 inch dia. steel pipe sleeves. The pipe sleeves will be fastened

over the end of the pipe piles. The pipe piles located at each end of the support structure

will be battered either upstream or downstream depending on the location. Another

component of this structure will be a system comprised of dolphins and floating booms,

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3485 designed to restrain or deflect floating debris at the riverward end of the excavated inlet

channel. A total of ten dolphins will be required and spaced at approximately 40.0 feet

on center. Each dolphin will be attached to a cluster of three 16 inch dia. steel pipe

piles. Two of the piles adjacent to the floating boom will be oriented in a vertical

position, the third pile will be battered away from the boom. The top elevation of the

3490 vertical piles will be El.+14.0, and the top elevation of the battered piles will be

El.+10.0. The upper portion of the dolphins will be a system constructed of structural

steel members fastened to 24 inch dia. steel pipe sleeves. The pipe sleeves will be

fastened over the end of the pipe piles. A floating boom placed horizontally will extend

between every two dolphins. The booms will be constructed of watertight 24 inch steel

3495 pipe filled with foam, and fastened to the dolphins in a manner to allow the booms to

rise and fall with the surrounding water elevation changes. A platform will be provided

on top of three dolphins to support solar powered lanterns and storage batteries. The

elevation of the top of the platforms will be El.+12.5. One lantern will be located at

each end of the dolphin group, and one at the mid-point.

3500

L9. Electrical and Mechanical Requirements

L9.1 ELECTRICAL SOURCES AND SUPPLY REQUIREMENTS

3505 L9.1.1 General

Development of this proposed diversion project will require various proposed structural features

to accomplish the intended purpose. All the structural features will require either a single or

multiple type of electrical power source depending on the operational requirements at each site.

3510 The ability to furnish electrical power to each structural feature from an off site location has not

been determined at this time, and will be investigated in another design stage. The possible

electrical requirements at each feature site have been presented below.

L9.1.2 Electrical Requirements Per Site

3515

a. Project Feature 3-15’x15’ Gated Box Culverts. – An electrical power supply will be

required to operate the roller gate operators. Whether the operators will be electrically

or hydraulically operated has not been determined at this time. In either case an

electrical power source will be required for the operator motors, or for the electrical

3520 motors driving the hydraulic pumps for the operators. In addition, a power source will

be required for the machinery building lighting, and switchboard equipment in the

building.

b. Project Feature 10-15’x15’ Gated Box Culverts. – An electrical power supply will be

3525 required to operate the roller gate operators. Whether the operators will be electrically

or hydraulically operated has not been determined at this time. In either case an

electrical power source will be required for the operator motors, or for the electrical

motors driving the hydraulic pumps for the operators. In addition, a power source will

be required for the machinery building lighting, and switchboard equipment in the

3530 building.

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c. Project Feature 4,000’ Gated Weir. – An electrical power supply will be required to

operate the movable gantry crane. The power supply will operate the drive motors

which move the crane, the lifting hoist motors which position the lift gates, the jib crane

3535 motor, and the motor which operates the clamshell bucket.

d. Project Feature 3,000’ Gated Weir. – An electrical power supply will be required to

operate the movable gantry crane. The power supply will operate the drive motors

which move the crane, the lifting hoist motors which position the lift gates, the jib crane

3540 motor, and the motor which operates the clamshell bucket.

e. Project Feature 2,000’ Gated Weir. – An electrical power supply will be required to

operate the movable gantry crane. The power supply will operate the drive motors

which move the crane, the lifting hoist motors which position the lift gates, the jib crane

3545 motor, and the motor which operates the clamshell bucket.

f. Project Feature 19-6’ Dia. Pipe Siphon. – Operation of the siphon will not require an

electrical power source. In the event a decision is made, at a later date, to provide

exterior lighting or a lighted maintenance building, an electrical power source may be

3550 required.

g. Project Feature 30-6’ Dia. Pipe Siphon. – Operation of the siphon will not require an

electrical power source. In the event a decision is made, at a later date, to provide

exterior lighting or a lighted maintenance building, an electrical power source may be

3555 required.

h. Electric Power Source(s). – Electric power source(s) can be either commercial utility

electric power or diesel engine generators. Location of commercial utility power and

the cost to supply this power will be compared to the cost of a diesel engine generator

3560 set, including estimated O&M costs to determine the recommended source of the

required electrical power.

L9.2 SOLAR POWER SUPPLY SYSTEMS

3565 L9.2.1 General

The only project features that would incorporate a solar power system will be the two siphon

structures mentioned above. The siphon features will include protective dolphins placed in the

waterway. Warning lanterns will be mounted on top of the dolphins and powered with electrical

3570 storage batteries which will be charged with solar panels. Exterior lighting and a maintenance

building are not proposed to be included in this project at this time, but in the event they are

included, solar power may be provided in lieu of extending a conventional power supply to the

sites.

3575 L9.3 ELECTRICAL AND MECHANICAL DESIGN FOR DIVERSION FACILITY

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L9.3.1 General

The size and type of electrical and mechanical components for the project features were selected

based on a variety of considerations, among them hydraulic requirements, similar features

3580 performing the same function, and utilizing existing designs from other projects.

L9.3.2 Electrical/Mechanical Requirements Per Site

a. Project Feature 3-15’x15’ Gated Box Culverts. – Regulation of flow thru the culverts

3585 will be controlled with the use of three 15’x15’ fabricated structural steel roller gates.

The gates will be raised/lowered with the use of a gate hoist supplied by a known and

acceptable gate manufacturer. Selection of either electric motor operated or

hydraulically operated gate hoists will be determined in a later project design stage.

Two fabricated structural steel bulkheads approximately 15 feet square will be provided

3590 and stored on site when not in use. The bulkheads will be fitted with rollers, and

vertical steel roller guides will be cast in slots in the concrete walls.

b. Project Feature 10-15’x15’ Gated Box Culverts. – Regulation of flow thru the culverts

will be controlled with the use of ten 15’x15’ fabricated structural steel roller gates. The

3595 gates will be raised/lowered with the use of a gate hoist supplied by a known and

acceptable gate manufacturer. Selection of either electric motor operated or

hydraulically operated gate hoists will be determined in a later project design stage.

Two fabricated structural steel bulkheads approximately 15 feet square will be provided

and stored on site when not in use. The bulkheads will be fitted with rollers, and

3600 vertical steel roller guides will be cast in slots in the concrete walls.

c. Project Feature 4,000’ Gated Weir. – Regulation of flow thru the weir structure will be

controlled by the operational use of one hundred eighty two fabricated structural steel

vertical lift gates. The gates will be approx. 19.0 feet wide and 7.0 feet high. The gates

3605 will be fitted with steel rollers, and vertical steel roller guides will be cast in slots in the

concrete divider walls. Dogging devices will be attached to the gates to lock them in a

raised position. The gates will be raised with the use of a fabricated structural steel

lifting beam, connected with steel cables to a movable rail mounted gantry crane. The

crane size and lifting capacity to be determined during a later design phase. The gantry

3610 crane assembly will include a jib crane, and clamshell bucket suspended from a boom

with a 180 degree swing capability.

d. Project Feature 3,000’ Gated Weir. – Regulation of flow thru the weir structure will be

controlled by the operational use of one hundred thirty eight fabricated structural steel

3615 vertical lift gates. The gates will be approx. 19.0 feet wide and 7.0 feet high. The gates

will be fitted with steel rollers, and vertical steel roller guides will be cast in slots in the

concrete divider walls. Dogging devices will be attached to the gates to lock them in a

raised position. The gates will be raised with the use of a fabricated structural steel

lifting beam, connected with steel cables to a movable rail mounted gantry crane. The

3620 crane size and lifting capacity to be determined during a later design phase. The gantry

crane assembly will include a jib crane, and clamshell bucket suspended from a boom

with a 180 degree swing capability.

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e. Project Feature 2,000’ Gated Weir. – Regulation of flow thru the weir structure will be

3625 controlled by the operational use of ninety one fabricated structural steel vertical lift

gates. The gates will be approx. 19.0 feet wide and 7.0 feet high. The gates will be

fitted with steel rollers, and vertical steel roller guides will be cast in slots in the

concrete divider walls. Dogging devices will be attached to the gates to lock them in a

raised position. The gates will be raised with the use of a fabricated structural steel

3630 lifting beam, connected with steel cables to a movable rail mounted gantry crane. The

crane size and lifting capacity to be determined during a later design phase. The gantry

crane assembly will include a jib crane, and clamshell bucket suspended from a boom

with a 180 degree swing capability.

3635 L10. Construction Procedures

The MRT levee protects the project area from Mississippi River floods. A temporary levee will

be in place, with the appropriate level of protection, when the levee is breached for construction

to protect the evacuation route. Appropriate erosion control measures will be in place for the

3640 duration of the construction.

Highway 39 is the emergency evacuation route for areas south of the diversion site. Continued

access to the project area during construction will be necessary to ensure the population will not

be isolated. Temporary detours of Highway 39 will be constructed, with appropriate safety

3645 measures in place. Secondary road detours will be made to allow local residents access to their

property during the construction of the project.

L11. Operations and Maintenance

3650 L11.1 Operations

Operations for the diversion are yet to be determined. It is assumed that there will be some type

of seasonal pulse in the spring of the year lasting from possibly two weeks to three months

depending on conditions. For this pulse, water will be gradually introduced so as to minimize

3655 scour without affecting the sediment load. The current proposed operations are to have a March

and April pulse of the maximum amount of water possible (up to 35,000cfs). Figure L11.1

shows the proposed hydrograph of the diversion structure.

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Figure L11.1 – Proposed diversion hydrograph

3660

The operation of this structure will be closely tied to the operation of the Caernarvon Diversion

as well other diversions along the Mississippi River. Interrelated operations between these

different diversions are critical to provide benefits to the different coastal marshes and not create

3665 undesired impacts to the Mississippi River such as induced shoaling.

The diversion will be driven based off of the head differential between the Mississippi River and

the coastal marsh where we are diverting water. The outfall of the diversion is in an estuary and

assumed to have an average stage equal to sea level (0.00 NAD88) throughout the course of the

3670 year. Therefore, the river stage will typically be the head that the diversion can utilize. Figure

11.2 shows the average stage of the river at the Alliance, LA gage. The Alliance, LA gage is

approximately 5 miles upstream from the proposed diversion site and is assumed to have the

same stage. Figure 11.3 shows the rating curve for the 10 – 15’x15’ Box Culvert Diversion.

0

5000

10000

15000

20000

25000

30000

35000

40000

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Figure 11.2 – Average Mississippi River stage at Alliance, LA

3675

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Figure 11.3 – Diversion Rating Curve

3680 For more information operations of the diversion, please consult chapter 3.0 Plan Formulation of

the White Ditch Feasibility Study.

L11.2 Maintenance

3685 With the proposed diversion there will be needs for channel maintenance dredging, removal of

sediment buildup in box culverts and sluice gate maintenance. It is estimated that there will need

to be significant channel dredging every 10 years on the proposed channel enhancement features.

Sediment removed from box culverts and dredged from channels shall be placed in sediment

deficient areas near the dredge site. It is also assumed that there will be annual maintenance and

3690 lubrication needs provided to the sluice gates.

L12. Cost Estimates

L12.1 Basis of Cost Estimate

3695

An initial array of alternatives was developed by the PDT. The initial array of alternatives

included at Location 2 are:

• Alternative 2A: 30 pipe siphon with a 5,000 cfs outfall capacity

3700 • Alternative 2B: 3 box culverts with a 5,000 cfs outfall capacity

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

0 1 2 3 4 5 6 7 8 9 10

Flow through Structure

Feet of Head between River and Marsh

10 - 15'x15' Box Culvert Diversion Potential

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• Alternative 2C: 30 pipe siphon with a 10,000 cfs outfall capacity

• Alternative 2D: 3 box culverts with a 10,000 cfs outfall capacity

• Alternative 2E: 10 box culverts with a 15,000 cfs outfall capacity

• Alternative 2F: 10 box culverts with a 35,000 cfs outfall capacity

3705

The initial array of alternatives include at Location 3 are:

• Alternative 3A: 30 pipe siphon with a 5,000 cfs outfall capacity

• Alternative 3B: 3 box culverts with a 5,000 cfs outfall capacity

3710 • Alternative 3C: 30 pipe siphon with a 10,000 cfs outfall capacity

• Alternative 3D: 3 box culverts with a 10,000 cfs outfall capacity

• Alternative 3E: 10 box culverts with a 15,000 cfs outfall capacity

• Alternative 3F: 10 box culverts with a 35,000 cfs outfall capacity

3715 Each alternative consists of a structure paired with an appropriately sized outfall channel to

convey a desired flow of fresh water and sediment into the weakened marsh area.

The preliminary cost estimates for the initial array of alternatives are unit price estimates based

on preliminary design and associated quantity take-offs with price data from recent bid results,

3720 historical costs, and the expertise of the district’s cost estimators and engineers. Appropriate

contingencies are applied. The price level for these cost estimates is November 2009. The cost

estimates for the initial array of alternatives can be found in Annex 3.

The final array of alternatives included four alternatives at Location 3. The alternatives were

3725 selected from the initial array of alternatives and had to meet the project goals outlined in the

main report. The final alternatives chosen are:

• Alternative 3B: 3 box culverts with a 5,000 cfs outfall capacity

• Alternative 3D: 3 box culverts with a 10,000 cfs outfall capacity

3730 • Alternative 3E: 10 box culverts with a 15,000 cfs outfall capacity

• Alternative 3F: 10 box culverts with a 35,000 cfs outfall capacity

The preliminary cost estimates for the final array of alternatives are also based on further refined

preliminary design and associated quantity take-offs with price data from recent bid results,

3735 historical costs, and the expertise of the district’s cost estimators and engineers. Appropriate

contingencies are applied. The price level for these cost estimates is December 2009. The cost

estimates for the final array of alternatives can be found in Annex 3. In addition to the four final

alternatives, the cost estimates for the siphons at Location 3 were included. These estimates

were included for quantity clarification purposes only.

3740

L12.2 DETAILED ESTIMATE

The tentatively selected plan for the White Ditch Marsh Restoration project is Alternative 3F, 10

each, sized 15 feet x 15 feet box culverts, with an outfall capacity of 35,000 cfs. The selected

3745 plan involves excavating a section of levee and road to construct the 10 box culvert structure,

replacing the levee and road on top of the structure, and excavating an outfall channel system to

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convey 35,000 cfs of fresh water and sediment to the damaged marsh. The structure also has ten

sluice gates with hydraulic operators that will be used to regulate the flow of fresh water and

sediment through the structure.

3750

The preferred alternative cost estimate is a detailed estimate based on the expertise of the

district’s cost estimators and engineers. The cost estimate for the recommended plan was

prepared utilizing the MCACES software. The MCACES estimate is included in Annex 3. The

estimated costs were based upon an analysis of each line item evaluating quantity, production

3755 rate, and time, together with the appropriate equipment, labor, and material costs. Appropriate

contingencies are applied. The price level for this cost estimate is January 2010.

The detailed estimate meets the requirements and recommendations of the following documents

and sources:

3760 • ER 1110-2-1150, Engineering and Design for Civil Works Projects.

• ER 1110-2-1302, Civil Works Cost Engineering.

• ETL 1110-2-573, Construction Cost Estimating Guide for Civil Works.

The detailed estimate assumes that the marsh and main outfall excavation will be completed by

two small dredges and the side berms will be formed by several amphibious excavators. The

3765 detailed estimate also assumes that all construction elements associated with the box culvert will

be completed on land.

Planning, Engineering and Design costs and Construction Management costs are included in the

detailed estimates. These costs are calculated as a percentage rate of the construction cost. The

3770 rates are 17.5% for planning, engineering and design, which includes engineering and design

during construction, and 10% for construction management. The planning, engineering, and

design rate was calculated based on percentages for Engineering, Project Management,

Estimating, Construction, and Planning & Environmental Compliance. The construction

management rate is based on average expenditures for construction management.

3775

A plan construction schedule was developed based on the production rates used in the detailed

estimate and the expertise of the district’s cost estimators and engineers. The plan construction

schedule was used in the Cost and Schedule Risk Analysis discussed below. The anticipated

construction duration based on the plan schedule is four years and one month. The plan

3780 construction schedule is included in Annex 3.

The Total Project Cost table was developed based on the detailed estimate, the completed cost

and schedule risk analysis, and the civil works work breakdown structure (CWWBS) elements

included in the detailed estimate. Those elements are:

3785 • 01 LANDS AND DAMAGES

• 02 RELOCATIONS

• 15 FLOODWAY CONTROLS AND DIVERSION STRUCTURES

• 30 PLANNING, ENGINEERING & DESIGN

• 31 CONSTRUCTION MANAGEMENT

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3790

The Total Project Cost table shows the effective price level for the detailed estimate of January

2010, the Budget Year effective price level of October 2010, and the Fully Funded Project Cost

with a construction midpoint date of April 2014. Escalation for the price level years is based on

the Army Corps of Engineers Engineering Manual (EM) 1110-2-1304 Civil Works Construction

3795 Cost Index System (CWCCIS) revised 30 September 2009. The Total Project Cost table is

included in Annex 3.

L12.3 Contingencies

3800 Contingencies are based on a Cost Rick Analysis using Crystal Ball software. Results of this

analysis are discussed in the Risk Analysis Section below.

L12.4 Risk Analysis

3805 A cost risk analysis was performed for this project in accordance with ER 1110-2-1302

paragraph 7.3.2 and ER 1110-2-1302, appendix B, paragraph 4. The results of the cost risk

analysis are shown in the Project Cost and Schedule Risk Analysis Report included in Annex 3.

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ANNEX 1

3810

Quantifying Benefits of Freshwater Flow Diversions to Coastal Marshes

1199
Quantifying Benefits of Freshwater Flow Diversion to Coastal

Marshes: Theorya and Applicationsb

S. Kyle McKay1, J. Craig Fischenich2, S. Jarrell Smith3, and Ronald Paille4

1

U.S. Army Engineer Research and Development Center (ERDC)

Environmental Laboratory

187 Oglethorpe Ave. Apt. B

Athens, Georgia, 30606

Email: Kyle.McKay@usace.army.mil

2

U.S. Army Engineer Research and Development Center (ERDC)

Environmental Laboratory

3909 Halls Ferry Rd.

Vicksburg, Mississippi, 39180

Email: Craig.J.Fischenich@usace.army.mil

3

U.S. Army Engineer Research and Development Center (ERDC)

Coastal and Hydraulics Laboratory

3909 Halls Ferry Rd.

Vicksburg, Mississippi, 39180

Email: Jarrell.Smith@usace.army.mil

4

U.S. Fish and Wildlife Service

646 Cajundome Boulevard, Suite 400

Lafayette, Louisiana 70506

Email: Ronald_Paille@fws.gov

Keywords: wetland, Louisiana, accretion, uncertainty, organic, inorganic, coastal

restoration, operation,

Abstract

The combination of relative sea level rise and river/marsh disconnection has created a

deficit of available soil and accompanying land loss in a large portion of coastal

Louisiana. The U.S. Congress recently charged the U.S. Army Corps of Engineers, State

of Louisiana, and other federal and local agencies with restoring the coastal wetlands of

Louisiana and Mississippi. Many alternative combinations of restoration measures have

been proposed, and assessment of the advantages and disadvantages of these efforts must

be made to determine the optimal design. One technique being applied for coastal

restoration is the reconnection of rivers to coastal marshes through flow diversions.

a Based on material from McKay, S.K., J.C. Fischenich, and S.J. Smith. (2008). “Quantifying Benefits of

Flow Diversion to Coastal Marshes. I: Theory.” In draft for submission to Ecological Engineering.

b Based on material from McKay, S.K., J.C. Fischenich, and R. Paille. (2008). “Quantifying Benefits of

Flow Diversion to Coastal Marshes. II: Application to Louisiana Coastal Protection and Restoration.” In

draft for submission to Ecological Engineering.

1

1200
Freshwater flow diversions offer significant nutrient and sediment inputs to marshes that

induce both organic and inorganic accumulation of soil. Boustany (2007) presented a

screening level model for assessing both the nutrient and sediment benefits of flow

diversion over long time scales. This paper has presented the adaptation of Boustany’s

(2007) model to include daily variation in sediment processes in order to optimize

diversion structure design and operation. The model was verified using an existing

diversion to prove the ability of the model to track land evolution associated with flow

diversion. This paper also demonstrates the application of the model to diversion

operational and structural optimization.

Introduction

In the fall of 2005, Hurricanes Katrina and Rita awakened the United States public to the

natural protection that coastal wetlands provide in reducing of the effects of hurricanes on

coastal communities. In response to these catastrophic events, the U.S. Congress directed

the U.S. Army Corps of Engineers (USACE) to “conduct a comprehensive hurricane

protection analysis and design...to develop and present a full range of flood control,

coastal restoration, and hurricane protection measures” (USACE, 2006). This paper

focuses on interagency efforts to assess and weigh benefits of coastal restoration via

freshwater flow diversion. The paper will focus on the development and adaptation of a

screening level model to quantify the benefits of flow diversion to coastal marshes and

will describe the assessment of various diversion operational and structural scenarios.

Coastal Marsh Accretion and Flow Diversion

The tidal marshes of coastal Louisiana are receding at alarming rates as high as 115

km2

/yr (Barras et al., 1994). Submergence of these valuable ecological assets (Figure 1)

was once counteracted by vertical accretion due to the addition of freshwater, nutrient,

and mineral inputs from riverine environments; however, eustatic sea level rise (ESLR)

and basin subsidence now exceed the current rate of vertical accretion, and coastal

marshes have been disconnected from their freshwater and sediment sources, distributary

channels of the Mississippi and Atchafalya Rivers. ESLR has been attributed to global

increase in ocean volume and has been estimated as 1.0-2.4 mm/yr (Church et al., 2001).

Subsidence of the Mississippi delta has been attributed to multiple factors, namely:

regional isostasy, faulting, sediment consolidation, and soil dewatering (Dokka et al.,

2006). Previous researchers identified other potential sources of subsidence as

groundwater and petroleum extraction (Morton et al., 2002); however, Dokka et al.

(2006) renounce these hypotheses as unlikely due to the relative lack of groundwater

extraction from the highly saltwater intruded groundwater table of most of southern

Louisiana and the lack of coincidence between petroleum extraction and subsidence. The

synergy of ESLR and basin subsidence has created an apparent local change in sea level

known as Relative Sea Level Rise (RSLR) that has been measured in the Mississippi

Delta at rates as high as 10 mm/yr (Snedden et al., 2007).

In addition to RSLR, the disconnection of coastal marshes from their sediment and

nutrient source is equally disconcerting. Over geologic time scales, large-scale delta lobe

switching has lead to alternating episodes of delta building and redistribution of sediment

2

1201
and nutrients throughout the coastal plain (Coleman, 1988; Coleman et al., 1998);

however, in the last two centuries, the Mississippi River has been controlled by levees

and other structures in order to maintain a consistent navigation channel for commerce

and protect infrastructure against floods (Coleman et al., 1998; Parker et al., 2006).

Presently, much of the sediment and nutrient load of the Mississippi River is discharged

directly into the northern Gulf of Mexico through the birdsfoot delta, providing little

benefit to protective delta building and contributing to an increasing zone of hypoxia near

the river mouth (Mitsch et al., 2001). In addition to problems associated with fate of

river sediment and nutrients, this disconnection starves coastal wetlands of historic

nutrient and sediment inputs necessary for marsh sustainment. Although the relative

importance of this multitude of factors has yet to be rigorously quantified throughout the

Louisiana coastal plain, the combination of RSLR and river/marsh disconnection has led

to high land loss rates and conversion of many freshwater marshes to shallow saltwater

bays.

In recent years, freshwater flow diversions from river sources to coastal marshes have

been offered as a tool for combating RSLR and disconnection of rivers and wetlands. In

these diversions, river water is released into marshes to simulate flooding of a river onto

its floodplain and increase hydrologic connectivity. Potential benefits have been

observed from pulsing diversion discharges to simulate natural flood regimes (Day et al.,

2003; Reyes et al., 2003; Snedden et al., 2007). Many studies have also shown that flow

diversion is a plausible remedy to reconnect rivers to tidal marshes and deltas and induce

organic and inorganic deposition (Parker et al., 2006; Snedden et al., 2007). An ancillary

benefit of these flow diversions is potentially reduction of the nutrient loading to the Gulf

of Mexico with associated reduction in the hypoxic zone (Lane et al., 1999; Mitsch et al.,

2001).

Vertical accretion of marshes has been identified as highly dependent upon both

inorganic and organic accumulation (Figure 2; Delaune et al., 1981; Nyman et al., 1993;

Day et al., 1995; Reed, 1995; Foote and Reynolds, 1997; Nyman et al., 2006; Morris,

2007). Often accretion is only accounted for through sedimentation (e.g. Parker et al.,

2006); however locations have been identified that depend more upon organic inputs than

sediment inputs (Nyman et al., 2006). The characteristics of the receiving marsh and

associated hydrologic connectivity are likely to influence whether inorganic or organic

inputs control (Boustany, 2007). For instance, if a region is initially unvegetated,

sediment inputs will be necessary to establish a soil platform for dense vegetative growth;

however, once vegetation is well established, the vegetative inputs are likely to dominate

while at the same time inducing higher retention of sediment in the process. This

complex feedback system necessitates the inclusion of both inorganic (sediment) and

organic (vegetative) inputs to any calculation of vertical accretion (Reed, 1995).

Vegetative accumulation in coastal marshes involves a delicate balance of above and

belowground plant productivity (Gosselink, 1984; Edwards and Mills, 2005), salinity

(Visser et al., 2004), nutrient availability (Delaune et al., 2005), flood frequency (Nyman

et al., 2006), vegetation type (Gosselink, 1984), and seasonality (Visser et al., 2004),

among other factors. Freshwater reintroduction has been shown to increase nutrient

3

1202
inputs to coastal marshes (Lane et al., 1999) and stimulate growth in these ecosystems

(Cardoch et al., 2002), further causing vegetative inputs to contribute to accretion. In

coastal Louisiana most marshes are nutrient limited (Nyman et al., 1990; Delaune et al.,

2005), so the introduction of limiting nutrients such as nitrogen and phosphorous from

flow diversion is a topic of great importance when considering flow diversion alternatives

and benefits (Lane et al., 1999; Hyfield, 2004; Hyfield, 2008); however, excessive

nutrient loading to coastal wetlands could potentially induce harmful water quality effects

such as eutrophication (Delaune et al., 2005) or stimulation of invasive plant species

(Carter and Bernard, 2007), so diversion of flow to coastal wetlands must be carefully

balanced and planned.

The accretion of sediment on coastal marshes and deltas has also been studied

extensively (Stumpf, 1983; Wang, 1997; Rybczyk and Cahoon, 2002; Reyes et al., 2003;

Parker et al., 2006; Snedden et al., 2007). Relevant sedimentation processes have been

identified as sediment loading from floods/diversions (Reed, 1995; Parker et al., 2006),

sediment settling properties (Stumpf, 1983; Soulsby, 1997; Winterwerp and van

Kesteren, 2004), tidal erosion (Stumpf, 1983; Wang et al., 1997), wind and storm induced

erosion and deposition (Wang, 1997), sediment export through canals and bayous (Wang,

1997; Baustian and Turner, 2006), and vegetation induced settling (Gleason et al., 1979;

Stumpf, 1983; Reed, 1995; Leonard and Luther, 1995).

Although flow diversions have proved useful for combating coastal land loss, the

optimization of flow diversion locations and operation has been difficult due to the

complexity in data needs of a coupled ecological and hydrodynamic model (Reyes et al.,

2003; Delaune et al., 2003; Snedden et al., 2007). These complexities encourage the

development of a simple, screening-level model that includes the effects of vegetation

and sediment dynamics and allows for straightforward examination and optimization of

flow diversion feasibility and operational benefits.

Boustany (2007) Landscape Evolution Model

Boustany (2007) developed a composite nutrient and sediment model to assess the

feasibility of flow diversions and screen diversion alternatives under the Coastal Wetland

Planning, Protection, and Restoration Act (CWPPRA; Boustany, Personal

Communication). This model, herein referred to as the Boustany Model (BM), presents

all benefits of flow diversion in terms of marsh area by assuming all nutrient and

sediment benefits additive to the existing area and land change rate:

+1 ii δ nut i ++= AAAA sed

Equation 1

Where Ai is the marsh area at time i, δnut is the fractional change in land area due to

RSLR and river-marsh disconnection (value may be positive or negative) that has been

adjusted to account for the benefits associated with nutrient addition, and Ased is the area

benefit of sediment addition.

The BM was developed to compare long term relative benefits of many flow diversion

locations and was implemented with an annual time step to provide quick estimates of the

potential benefits of diversions. The BM is sufficient for quick estimation of flow

4

1203
diversion benefits and initial screening of alternatives, but the LACPR program required

greater temporal resolution in order to assess not only the relative benefits of diversion

locations, but also the effects of diversion structure type, diversion operational regimes,

and hydrologic variability. Ideally a detailed two- or three-dimensional model coupling

nutrient and sediment processes would be used to account for the complex mechanisms

governing coastal marsh accretion (Reyes et al., 2000; Dortch et al., 2007); however, the

vast number of alternatives and short time scale of the LACPR report to Congress

precluded development of such models for every alternative and marsh. As such, the BM

was adapted to include processes deemed most critical to LACPR alternatives analysis.

The following sections provide further details of the nutrient and sediment models

implemented in the landscape evolution calculations, but the two major adaptations of the

BM were:

• High temporal variability in sediment processes encouraged the refinement of the

temporal resolution of the sediment model to include daily impacts of the

diversion on the marsh.

• In order to maintain model simplicity, the BM required estimation of a number of

parameters to account for nutrient and sediment processes (e.g. sediment retention

and average annual suspended sediment concentration). The adaptation of the

model has also included the calculation of many of these inputs in order to

account for temporal variance, reduce data requirements, and minimize potential

input errors.

Nutrient Benefits

Nutrient addition to coastal marshes has proven to be a source of vegetation stimulation

and strengthening and biomass creation (Deegan et al., 2007). Boustany (2007) proposes

a model that accounts for the ability of nutrients to stimulate vegetation to better resist

erosional processes. This model determines the percent of the vegetated area that is

strengthened from nutrient addition. This parameter is found by examining the annual

nutrient requirements of the marsh relative to the nutrients loaded to the marsh.

The nutrients required by the marsh for vegetative growth are assumed to be the mass of

the nutrients held in plant biomass. This quantity may be assessed by examining the rate

of biomass production (annual primary productivity, Pr) and the percent of biomass

containing these nutrients (γ). Since most Louisiana coastal marshes are nitrogen or

phosphorous limited, Boustany proposes that the total concentration of nitrogen and

phosphorous (TNP) be used to account for nutrient benefits.

LRreq Pr TNP = γ

Equation 2

Where LRreq is the marsh required nutrient loading rate [ML-2T-1], Pr is primary

productivity [ML-2T-1], and γTNP is the percent of plant biomass containing nitrogen and

phosphorous [1].

The nutrient loading rate of the diversion to plant biomass, LRdiv, may be calculated from

the volumetric discharge of water to the marsh from the diversion, Qdiv [L3

T-1], the

5

1204
concentration of nutrients in the source water, Csource [ML-3], the retention rate of

nutrients in plant biomass, Rnut [1], and the vegetated marsh area, Aveg [L2

].

nut

veg

div source

div R

A

CQ LR =

Equation 3

In addition to nutrient loading from the diversion, there is ambient nutrient loading to the

marsh from other ongoing processes (e.g. atmospheric deposition, stormwater runoff,

current plant decomposition, denitrification, etc.). These processes will be accounted for

by a loading rate for background sources, LRbackground. The net loading of nutrients to the

marsh, LRnet, is therefore the sum of the background and diversion loading rates.

net div += LRLRLR background

Equation 4

From knowledge of the loading rates applied, LRnet, and required, LRreq, one may obtain

the fraction of wetlands sustained by nutrient addition, Es.

req

net

s LR

LR E =

Equation 5

In this model, nutrients are assumed to be unable to freely construct land; however, they

can reduce the loss rate by strengthening vegetated areas against erosion. This

assumption produces conservative estimates of the organically-induced benefits of the

diversion. For instance, in an environment with a low land loss rate, according to the

model, the diversion could potentially reduce the land loss to zero; however, no land gain

would be associated with organic inputs. The percentage of wetland sustained by nutrient

addition serves as a reduction ratio to the land loss rate in the form of Equation 6.

( )

⎩

⎨

⎧

≥

− < = 0 11 1

s

s s

nut ForE

δ E ForE

δ

Equation 6

Where δ is the land change rate prior to the diversion and δnut is the nutrient adjusted land

change rate.

Sediment Benefits

The accumulation of diverted sediments is determined by a sediment budgeting model

utilizing the input concentration of sediment from the source water and calculated

hydrodynamics of the system to determine the quantity of diverted sediment retained in

the marsh. As previously specified, the BM implemented sedimentation calculations on

an annual timescale, and while this assumption is reasonable for preliminary screening of

alternatives, further refinement is necessary for more detailed analyses of flow diversion

benefits. The sediment model implemented herein relies on calculation of sediment

inputs and sediment settling theory on a daily timescale over a single representative year

and reapplies that year throughout the proposed project life cycle.

Sediment Input

In order to minimize costs and maximize benefits of flow diversion in coastal Louisiana,

diversion structures often withdraw water from one of the region’s major rivers (e.g.

6

1205
Mississippi, Atchafalya, Calcasieu). These rivers are located throughout the coastal

plain, carry large water and sediment loads, and serve as a virtually infinite source of

diversion resources.

River discharge and suspended sediment concentration have often been shown to be

positively correlated (Mossa, 1996; Snedden et al., 2007). The relationship between

discharge and sediment load may be determined by analytical and partially analytical

models (e.g. Meyer-Peter Muller, Einstein, Yang; Richardson et al., 2001) or by

empirical models for a given set of observed discharge and sediment concentration values

(Mossa, 1996; Snedden et al., 2007). In coastal Louisiana, there exists enough recorded

sediment discharge data to generate empirical models of sediment concentration for some

of the major rivers of the region. For this analysis, a power function was found to

provide enough resolution in sediment concentration variation (Equation 7). Table 1

presents a number of sediment ratings of this form for coastal Louisiana.

2

, 1

a

s river = QaQ river

Equation 7

Where Qs,river is sediment load (ton/da), Qriver is river discharge (cfs), a1 is a dimensional

coefficient, and a2 is a dimensionless coefficient. From this sediment rating, flowaveraged suspended sediment concentration of the river, Criver, may be

calculated ⎟

⎠

⎞ ⎜

⎝

⎛ = river

s river

river Q

Q C , and transformed to the desired units.

Regardless of the model defining this relationship, the sediment concentration has been

shown to be highly dependent upon discharge; therefore, in order to capture the temporal

variance in sediment discharge through a diversion, the sediment concentration must vary

with river discharge at an appropriate time scale (Snedden et al., 2007). For the purposes

of this analysis, daily variation in discharge provides sufficient temporal resolution for

accurate calculation of sediment loading to marshes by diversions.

One of the purposes for adapting the BM is the desire to examine relative diversion

structure operation. In order to do this, daily estimates of diversion discharge are also

required. These daily diversion discharges, Qdiv, are combined with the daily predictions

of river suspended sediment concentration, Criver, to determine the mass loading rate of

sediment to the marsh, Qs,div (Equation 8). This increase in temporal resolution allows for

examination of diversion discharge operation such that sediment benefits may be

maximized by coinciding diversion discharges with periods of high river suspended

sediment concentration.

s,div = divCQQ river

Equation 8

Sediment Retention

After sediment laden water has been diverted to a coastal wetland, a portion of the

sediment load is expected to settle from suspension and deposit. Sediment that remains in

suspension is then subject to being transported outside the system boundaries. Sediment

retention defines the fraction of diverted sediments retained within the coastal wetland.

7

1206
Retention is dependent upon system properties such as: wetland geometry, diversion

discharge, tidal velocities (Stumpf, 1983), wind and storm events (Wang, 1997), settling

velocity of diverted sediments (Soulsby, 1997; Winterwerp and van Kesteren, 2004),

vegetation coverage (Stumpf, 1983), and canal-induced sediment import/export (Wang,

1997). The approach taken by Boustany (2007) is to apply retention factors estimated for

other sites (e.g. Wax Lake Outlet) or allow the analyst to choose a retention factor based

on knowledge of the receiving area and best professional judgment. Building upon the

suggestion of Stumpf (1983), an alternative to this approach is to use a simple calculation

which includes effects of wetland geometry, sediment properties, and flow

hydrodynamics at the site. The effects of vegetation and channels are ignored in this

analysis in order to maintain model simplicity; however, vegetation would likely increase

roughness, reduce turbulence, and induce greater sediment deposition leading to

conservatively low estimates of sediment retention, while the influence of channels may

serve as pathways to sediment export and thus produce non-conservatively high estimates

of sediment retention.

Consider suspended sediments in a water body. The time required for a given particle to

settle from the water surface to the bed is given as:

Ws eff

H T

,

=

Equation 9

Where T is the time required for sediment to completely settle, H is the local depth, and

Ws,eff is the effective settling velocity of a specific sediment class.

As the particle settles, it is also transported by tidal and diversion currents, so the distance

traveled by the particle is:

s eff

div div W

H UTUX

,

==

Equation 10

Where U is the diversion induced mean velocity. As the averaging timescale of the

model is greater than the tidal period and net tidal flow is zero, Equation 10 neglects the

influence of tidal velocities, and the net displacement of water within the marsh is

described by the diversion flow.

For this analysis the wetland is assumed to have rectangular planform and cross-sectional

geometries described by the average length (L), width (B), and depth (H). The fraction of

sediment retained in the wetland then becomes a function of wetland length relative to

transport distance prior to full deposition of the sediment fraction in question (Stumpf,

1983). If all diverted sediment is retained within the system, the retention factor is 1.

Since this analysis takes a macroscopic view of the total sediment retained in the system

and location of deposit is not considered, the retention factor becomes 1 if the length of

the wetland is greater than the transport length, and the retention of a given sediment

particle class, Rj, may be expressed as:

⎟

⎠

⎞ ⎜

⎝

⎛ = min 1, X

L Rj

8

1207
Equation 11

Due to variation in fall velocity with sediment size, coarse particles may be retained

while fines are flushed from the system; therefore, the combined retention of the entire

grain size distribution must be made. Retention over all sediment classes may be

expressed as:

T = ∑ jj fRR

Equation 12

Where RT is the combined total retention factor and fj is the mass fraction associated with

each sediment class.

Fall Velocity

A key element of the sediment budgeting model presented is the calculation of the

effective fall velocity of a given sediment size class, which is a function of the fall

velocity of that sediment in a static body of water, Ws, and the turbulence of the flow.

Fall velocity of sediment is dependent upon both sediment properties (shape, size,

density, concentration, ability to flocculate) and fluid properties (viscosity, density,

temperature, salinity). In the natural environment, turbulence is generated by flow over

the sediment bed. The presence of turbulence acts to vertically mix suspended sediments,

which reduces the effective settling velocity of suspended particles. The steady-state

vertical flux balance at a point in the water column is given by:

=+ 0

dz

dC s KCW z

Equation 13

Where C is the suspended sediment concentration, Kz is the vertical diffusivity, and z is

the vertical distance from the bed.

For the purposes of this tool to estimate retention, it is convenient to combine the terms in

Equation 13 to define an effective settling velocity (Equation 14).

dz

dC s,eff s += KCWCW z

Equation 14

Vertical diffusivity varies with turbulent intensity and height above the bed. Rouse

proposes that diffusivity varies parabolically with height above the bed in the form

(Richardson et al., 2001):

⎟

⎠

⎞ ⎜

⎝

⎛ −= H

z z κ * zuK 1

Equation 15

Where κ is the von Karman constant (~0.4) and u* is the total friction velocity (a measure

of turbulent intensity).

Given the sediment flux balance in Equation 13, the vertical concentration profile is: b

a

a

a zH

zH

z

z CC

−

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

−

− =

Equation 16

9

1208
Where b is the Rouse parameter ⎟

⎠

⎞ ⎜

⎝

⎛ = u*

W b s

κ and za is a reference height above the bed

with a known sediment condition, Ca.

The turbulent shear velocity is estimated from the depth-averaged velocity by the

logarithmic boundary layer (law of the wall) (Kundu, 1990).

⎟

⎟

⎟

⎠

⎞

⎜

⎜

⎜

⎝

⎛ =

0

*

3 ln z

H

U u κ

Equation 17

Where U is the daily mean wetland velocity with both tidal and diversion related

components and z0 is the hydraulic roughness length.

For the diurnal tidal cycle of coastal Louisiana, the tide is assumed to have approximately

sinusoidal periodicity. The mean instantaneous wetland velocity can then be determined

by considering both tidal and diversion components (Figure 3).

max, sinω max,tide sinω divi div tide U

HB

Q += UUU +=

Equation 18

Where Ui is the instantaneous mean velocity with tidal and diversion components and

Umax,tide is the maximum tidal velocity (or tidal amplitude), and ω is tide phase.

For the use in the flow diversion model, the velocity is integrated over the tidal cycle (0

to 2π) to obtain the daily mean velocity, U.

{ } ( ) ( ) () ( ) 201 max, 2 1 0 2 cos 2cos cos 2

1 ωωω ω ωω π = UU div +−− U tide − + ( )

Equation 19

Where ω0 is the tide phase at zero up-crossing ⎟

⎠

⎞ ⎜

⎝

⎛ ⎟

⎠

⎞ ⎜

⎝

⎛− = −

tide

div

U

U

max,

1

0 ω sin , ω1 is the tide

phase at zero down-crossing ( ) ω1 π −= ω0 , and ω2 is the completed tidal

phase ( ) ω ω02 += 2π (Figure 3).

In order to estimate the shear velocity, the hydraulic roughness must also be estimated

from local sediment grain size, form roughness, and vegetative coverage. In this

analysis, a lumped parameter accounting for both grain size and form roughness is

implemented based on marsh surface character (Table 2). Vegetative roughness is

incredibly important in coastal marshes where emergent plants are encountered

throughout the marsh, and although basing this parameter on bed material ignores the

effects of vegetation, this will provide an estimate of sediment settling in open water and

will therefore provide conservative estimates of settling in vegetated or partially

vegetated marsh.

10

1209
Combining Equation 13 – Equation 17, one may obtain an expression for the effective

settling velocity of sediment in coastal marshes.

( ) ⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

− ⎟

⎠

⎞ ⎜

⎝

⎛

− ⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ − −=

− −−

2

1

,

zH

H

zH

z

z

zH bKWW

b b

a

a

s eff zs

Equation 20

For incorporation into the flow diversion model, vertical mixing has been computed at a

height above the bed equal to 1/10 of water depth ( ) 10 z = H and za is approximated as

1/100 of the depth ( ) 100 z H a = . These values provide an estimate of the settling velocity

of particles very near the bed that are assumed to settle. Insertion of these relations into

Equation 20 yields:

( ) ⎟

⎠

⎞ ⎜

⎝

⎛ ⎟

⎠

⎞ ⎜

⎝

⎛ −=

−−

−

H

bKWW

b

b

s eff zs

81.0

9

1 99

1

,

Equation 21

Where K Hu z * = 009.0 κ .

Net Sediment Benefit

By accounting for sediment loading to the marsh and sediment retention within the

marsh, the mass loading rate of sediment retained in the marsh may be determined by:

s,net = s,divRQQ T

Equation 22

Where Qs,net is the net mass loading rate of sediment to the marsh.

This loading rate may then be used to calculate the net aerial sediment benefit due to flow

diversion, Ased, for a given time period.

bd

s net

sed H

dtQ A

ρ

, =

Equation 23

Where dt is the time step (da) and ρbd is the average bulk density of the receiving area.

Bulk density in coastal marshes varies significantly with depth due to sediment

consolidation. For our analysis, we assumed that the bulk density was a depth averaged

value based on the depth of marsh being filled with sediment (i.e. flow depth, H). Bulk

density profiles were obtained from literature (Nyman et al., 1990; Nyman et al., 1993;

Delaune et al., 2003) and available data (Michael Channel, personal communication).

Application: Caernarvon Diversion and Breton Sound Estuary

In order to verify the ability of the model to account for landscape evolution due to flow

diversion, the model was applied to an existing diversion structure and marsh, the

Caernarvon Diversion to Upper Breton Sound Estuary (Figure 4). The Caernarvon

Diversion is located on the east bank of the Mississippi River at river mile 81.5 (131.2

km) (approximately 12.5 river miles (20.1 km) downstream of New Orleans) and

11

1210
discharges Mississippi River water into Breton Sound through five 15-ft (4.57-m) box

culverts with vertical lift gates (Lane et al., 1999; Snedden et al., 2007). The diversion

was constructed between 1988 and 1991 and opened for operation in August of 1991 with

goals of reducing the salinity in Breton Sound for commercial shell fisheries. An

ancillary benefit of the diversion has been sediment and nutrient loading to the marsh and

corresponding reduction in land loss (Snedden et al., 2007).

Upper Breton Sound is approximately 231 mi2 (599 km2

) in area with a length of 18.8 mi

(30.2 km) and a width of 12.3 mi (19.8 km). This estuary was historically an

intermediate marsh, but due to RSLR and river/marsh disconnection, marsh salinity

elevated to brackish conditions before the diversion became operational (Carter and

Bernard, 2007). The current marsh is dominated by brackish species (e.g. S. patens) near

the diversion and saline marsh species (e.g. S. alterniflora) far from the diversion

(Snedden et al., 2007).

Breton Sound is hydrologically isolated from surrounding marshes by levees on both the

eastern and western borders; therefore accounting for inflows and outflows to the marsh

is relatively straightforward with water budgets for Upper Breton Sound revealing major

hydrologic processes to be precipitation, evaporation, and freshwater diversion.

Groundwater and stormwater inflows have been shown to be relatively small compared to

precipitation and diversion (Hyfield, 2004).

In order to maximize the retention time of diverted water and induce desirable sediment

settling and nutrient uptake, the State of Louisiana has initiated outfall management for

the Caernarvon Diversion. Management actions have included restoration and

backfilling of man-made canals, installation of control structures throughout the marsh

(Carter and Bernard, 2007), and operational adjustment to test theories of marsh

sedimentation processes (Snedden et al., 2007).

Snedden et al. (2007) have shown that a large majority (nearly 99%) of Caernarvon’s

discharge flows downmarsh through two major flow routes for low discharges. These

authors indicate that below 3500 cfs, the diverted waters remain almost entirely in these

canals. When diversion discharge exceeds this threshold value, diverted waters appear to

exceed canal banks and flow over the marsh as sheet flow (Snedden et al., 2007). This

indicates that large pulses of discharge may be more effective in distributing sediments

throughout the estuary. These authors also applied a local river sediment rating based on

near-surface suspended sediment concentrations of the Mississippi River approximately 5

mi (8 km) downstream of the Caernarvon structure at Belle Chase, Louisiana. By

examining sediment loading rates through the diversion, these authors concluded that

pulsing of discharges in phase with high river sediment concentrations not only induces

sheet flow over the marsh, but also has the ability to load much greater quantities of

sediment to the marsh (Snedden et al., 2007).

The Caernarvon Diversion provides an excellent test case for the model developed herein

due to the variable discharge inputs and extensive knowledge of current system

processes. Table 3 presents the inputs to the model for the Caernarvon Diversion and

12

1211
Breton Sound. Many of these inputs have a significant amount of variability and have

been presented with standard deviations in order to provide the reader with a scale of

parameter uncertainty. When data was not available, parameters and ranges were

estimated by best professional judgment. Since many of the input parameters contain a

significant amount of uncertainty and forecasting land evolution in such a complex

system is difficult, model uncertainty has been characterized by a Monte Carlo risk

analysis. In this analysis, parameter uncertainty was estimated and assumed normal about

the mean. Random errors were then introduced in each parameter for 10,000

calculations. Model results were computed with each set of randomly induced errors, and

the range of area predictions was analyzed to determine 90% confidence intervals.

In order to apply the model to Breton Sound, the diversion and river hydrographs must be

estimated to indicate marsh nutrient and sediment availability. The river hydrograph may

be estimated by using a representative water year or by averaging flows for many years

and determining mean daily discharges over a period of record. The diversion

hydrograph may be estimated by applying historic operational records, assuming an input

hydrograph, testing various operational theories (e.g. pulses timed with river discharge),

or linking the discharge to the diversion structure type (e.g. diversion discharge

dependence upon river stage using a weir equation). A sample representative diversion

and river hydrograph are displayed (Figure 5) for operation of the Caernarvon structure in

1994. Both the diversion and river hydrographs for this year output very near average

annual discharge volumes and the peak magnitudes of the hydrographs were well

represented; therefore, for this analysis, the diversion and river hydrographs were

assumed to be that of the 1994 calendar year for each year of the simulation.

Figure 6 presents the evolution of land area within Upper Breton Sound from before the

diversion was opened (1 November 1990) until the end of 2006 (31 December 2006).

This figure shows the observed values of marsh area along with estimates by the current

model with associated parameter uncertainty alongside the Boustany Model. The

estimated future without project (FWOP) is presented to provide the reader with the

magnitude of marsh area benefit the Caernarvon Diversion is providing Breton Sound.

Vertical lines indicate the beginning of diversion operation and hurricanes making

landfall in Louisiana. It is clear that hurricanes create significant perturbations to the

system; however, hurricanes may provide both import and export to a given marsh

depending upon the location of landfall and are, for the purpose of this screening level

model, assumed to create no net import or export of sediment over a long planning

horizon.

In addition to model verification at Caernarvon, readers may be interested in the benefits

provided by nutrient and sediment components separately; therefore Figure 7 presents the

model predictions with nutrient only and sediment only scenarios for the Caernarvon

Diversion application.

Optimization of Implemented Diversion

The focus of LACPR has been the analysis of alternatives and the decision support

framework associated with choosing diversion sites and quantities. The land evolution

13

1212
model has been applied as tool for assisting in this framework and has provided relative

benefits of various flow diversion sites and scenarios. The utility of the tool, however,

has not yet been fully exploited. Following the narrowing of alternatives, the land

evolution model may then be used in the initial optimization of the selected diversions by

examining different operational and structural scenarios. This type of analysis has not yet

been conducted for each of the alternatives of the LACPR, but this section provides a

sample of how these analyses might be conducted for a given diversion site. The model

will be applied to an existing diversion (Caernarvon) to assess the land gain benefits of

six operational and five structural scenarios with near equal annual discharge volumes.

As previously stated, the Caernarvon Diversion discharges Mississippi River water to

Upper Breton Sound through five 15 ft box culverts with vertical lift gates which can be

used to control diversion discharges to the marsh. For this analysis the diversion is

merely used to demonstrate the ability of the land evolution model to provide relative

benefits of different operational and structural conditions. Table 3 provides the model

inputs used for these optimization exercises. For these analyses, the 1994 Mississippi

River hydrograph was found to be representative of the average annual discharge volume,

peak magnitude, and seasonality of flow in the river and has been used throughout the

duration of the model simulations in these exercises.

Operational Optimization of Gate Structures

The continuous hydrographic inputs of the model provide a tool for optimizing gate-type

diversion operation to obtain the greatest land evolution benefits. In this section, the

model will be applied to demonstrate the operational benefits for the six approximately

equal-volume discharge scenarios that follow (Figure 8). These annual hydrographs were

chosen based on previous research indicating that pulsing and timing of diversions may

be critical to land evolution (Day et al., 2003; Snedden et al., 2007).

1. Historic operation based on 2003 operational conditions (a “pulsed” diversion

year with a large portion of the annual sediment load derived from two twoweek pulses)

2. Simulated operation with a large pulse of one-month duration timed in phase

with high river sediment discharges

3. Simulated operation with a large pulse of one-month duration timed out of

phase with high river sediment discharges

4. Simulated operation with a small pulse of six-month duration timed in phase

with high river sediment discharges

5. Simulated operation with a small pulse of six-month duration timed out of

phase with high river sediment discharges

6. Constant diversion discharge

Each of the annual hydrographs was input to the model, and land evolution estimates

were made for a 50 year time period starting at the arbitrary starting date of January 1,

2001 (Figure 9). These results indicate that, for the inputs considered, the magnitude and

timing of the diversion discharges is critical to suppression of the land loss rate.

Therefore, for this hypothetical diversion scenario at Caernarvon, the diversion of flows

14

1213
could be altered to be in phase with high river sediment discharges and should occur from

later winter to early summer (February – June). These periods of high sediment

discharge may not, however, align with other project goals of a given diversion (e.g.

reduction of salinity for maintenance of commercial fisheries). This analysis indicates a

time period over which the greatest land evolution benefits may be obtained, and

diversion operation may be optimized within that timeframe to include multiple project

goals.

Structure Selection

Not only will operational considerations impact diversion benefits, but structure type will

also have a drastic impact on the selection and operation of a given diversion. For

instance, a gate-type structure (such as the one at Caernarvon) may be controlled to

achieve the desired water and sediment discharges, but the cost and maintenance may be

high. Whereas a broad-crested weir may have low cost, but control of diversion

discharges is relatively minimal. A siphon is a third common diversion structure that

may require significant maintenance and operational effort, but the suspended sediment

concentration of the diverted water may be higher and the size gradation of the sediment

diverted may be significantly larger inducing more land gain on both accounts. This

section will demonstrate the ability of the model to assess land evolution by applying the

model to the Caernarvon Diversion for the following five hypothetical structural

scenarios:

1. Gate structure with pulsed operation based on the 2003 hydrograph

2. 100-ft wide broad-crested weir

3. 200-ft wide broad-crested weir structure

4. 1 – 15 ft siphon with a single short duration (113 day) discharge event

5. 1 – 6 ft siphon with continuous operation throughout the year

The weir structures have been assumed to behave as theoretical broad-crested weirs

(Equation 24) and the discharge was determined based on the Mississippi River stage for

the representative hydrograph (1994). The weir elevations were adjusted to produce

annual discharge volumes approximately equal to the average annual diversion discharge

volume from 1991-2006.

( ) 2/3

div weirweir river weir = − zzBCQ

Equation 24

Where Cweir is a weir coefficient (~4.37 ft0.5/s), BB

weir is the width of the weir (ft), zriver is

the elevation of the river for a given flow rate (ft), zweir is the elevation of the weir (ft)

(White, 2003).

In order to calculate the discharge of the diversion by siphoning, Bernoulli’s equation

was implemented (Equation 25). Frictional losses in the pipe were assumed negligible

due to the qualitative nature of this analysis. As with the weir, the marsh elevation was

optimized to produce annual discharge volumes approximately equal to the average

annual diversion discharge volume from 1991-2006. Figure 10 presents diversion

discharge hydrographs for the five scenarios considered.

15

1214
( ) ⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ = = − 4

2

2 d AVQ zzg div siphon siphon river marsh

π

Equation 25

Where zmarsh is the elevation of the marsh and d is the pipe diameter.

The land evolution model was applied using these annual diversion hydrographs and the

parameters from the Caernarvon Diversion (Table 3). The only alteration of the

Caernarvon model inputs was the sediment rating curve and size fraction applied to the

siphon calculations. A weir or gate structure diverts surface waters of the Mississippi

River to the marsh, and the Belle Chase surface sediment rating presented in Table 1 was

determined as such (Snedden et al., 2007), but a siphon could draw water from lower in

the water column, producing a larger sediment concentration and a more coarse sediment

size fraction. As such, the total sediment rating at Belle Chase was applied with an

assumed size fraction distribution based on the observed fraction of silt and clay (fsand =

0.12, fsilt = 0.44, fclay = 0.44, ffloc = 0.3).

As evident by the land evolution calculations (Figure 11), the benefits of flow diversion

are extremely sensitive to the size fraction and concentration of the river water diverted.

Therefore, the choice of structure type from a land evolution perspective is

overwhelmingly in favor of siphons which divert higher concentrations of coarser

sediment. However, logistical difficulties associated with operation and maintenance of a

siphon (e.g. maintaining head differential, priming the siphon, air intrusion) may

eliminate this structure type from consideration in many instances. It is also important to

note that the results presented herein likely offer overly optimistic benefits of siphon

structures due to the exclusion of friction in the siphon and the use of the total suspended

sediment rating at Belle Chase. Although the siphon will be able to draw water from

lower in the Mississippi River water column than a gate or weir, in order to maintain

appropriate pressure differential for flow to the marsh, the siphon inlet will likely be

required to draw in the upper half of the water column where suspended sediment

concentrations are lower. The land evolution benefits of a siphon may also be

overshadowed by other project objectives which may be detrimentally impacted by high

turbidity or suspended sediment concentrations, such as fisheries production and marsh

vegetation stimulation.

Summary of Diversion Optimization

The purpose of this exercise was not to identify an operational condition or structural

alternative that is ideal for all flow diversions in coastal Louisiana, but was instead to

demonstrate the land evolution model’s ability to maximize land gain benefits for various

operational and structural alternatives. Land gain (or suppression of land loss) is often

not the only objective in the large-scale, long-term projects of the LACPR, and many

other factors may be included in the selection of a diversion operational or structural

scheme, some of which include:

• Cost of diversion with both structural and operation/maintenance components

• Desire to control diversion releases

• Commercial fisheries impacts

• Public recreational land use patterns

16

1215
Conclusions

This paper has presented the adaptation of a model for quantifying flow diversion

benefits and demonstrated the model’s ability to estimate the relative benefits of various

flow diversion locations, structures, and operational regimes; however, the model results

are limited due to the exclusion of a variety of important system processes. Some of the

major assumptions and limitations of the model were:

• Benefits of flow diversion are independent (in reality the benefits are likely nonlinearly coupled due to vegetation inducing sediment deposition and

sedimentation increasing suitable habitat for vegetation)

• Nutrients serve as a reduction in land loss, not a source of land gain benefits

(Deposition of particulate organic matter neglected)

• Spatial uniformity - vegetation, roughness, bulk density, and other parameters are

highly heterogeneous in coastal marshes

• Temporal resolution is only represented intra-annually, not contiuously

• Rectangular wetland geometry

• No vegetative component to settling/roughness

• Organic accumulation is not considered as a function of time even through

biomass production is highly seasonal

• No habitat switching with time

• Canals are not accounted for as a sediment loss mechanism

• Sheetflow was assumed for all diversion flow rates

• No sediment resuspension due to rainfall, tidal flows, waves, or hurricanes

• Uniform distribution of sedimentation.

• Nutrient recycling neglected

Although these assumptions significantly limit the model’s ability to quantify the benefits

of flow diversion, approximations had to be made due to the time and resource

constraints under which the model was developed. Further refinement of model

processes and algorithms are recommended and should address the above limitations

specifically focusing on the following:

• Temporal distribution of nutrient benefits to account for seasonality and storage

• Nutrients as a source of benefit, not just a source of loss reduction. Refer to the

organic accumulation models of Blum et al. (1978), Mitsch and Reeder (1991),

and Reyes et al. (2000) for examples of organic benefit frameworks

• Nutrient retention calculations inclusive of marsh nutrient cycling processes (e.g.

denitrification, burial)

• Division of nutrients – nutrients should be divided into individual components

(e.g. nitrogen and phosphorous) due to marsh limitation to a single nutrient

• Salinity is roughly covered in the model by the adjustment of bulk density and

primary productivity, but the parameter is not explicitly covered and habitat

switching is not tracked

• Spatial complexity/geometry improvements

• Inclusion of coastal currents and erosion, major storm events, and wind erosion

• Better methods of accounting for hydraulic resistance

17

1216
Acknowledgements

This effort was developed and funded under the Louisiana Coastal Protection and

Restoration (LACPR) Program of the U.S. Army Corps of Engineers. The authors would

like to acknowledge the LACPR Habitat Evaluation Team (HET), and their extensive

technical guidance of the development of the technology presented herein. In particular,

Ronald Paille and Tamieka Armstrong provided critical feedback on formulation and

application of the model. Ron Boustany provided the basis for the nutrient model

presented herein and the authors are grateful for his willingness to assist in this effort.

Gregg Snedden, Joann Mossa, Robert Lane, and Mike Channell all provided valuable

data and knowledge resources throughout the development of this model.

18

1217
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1222
Figures

Figure 1. Typical coastal Louisiana marsh community with a patchwork of dense

vegetation and open water

24

1223
Figure 2. Conceptual model of coastal Louisiana marsh accretionary processes

(from Day et al., 1995)

25

1224
-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

-3.14 -1.57 0 1.57 3.14 4.71 6.28

Tide Phase, ω

Velocity, u

udiv utide utotal

ω0 ω1 ω2

Figure 3. Wetland velocity with diversion and tidal components

26

1225
Figure 4. Aerial view of Breton Sound displaying Caernarvon Diversion and

project division areas for tracking land evolution. In this analysis only the following

areas were considered to be directly influenced by the Caernarvon Diversion in

order to maintain relative uniformity in conditions: Upper Reference Outfall East,

Upper Project Outfall, Upper Reference West, Middle Reference West, and Middle

Project Area.

27

1226
0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

J FMAMJ J ASOND

Date

Diversion Discharge, Qdiv (cfs)

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

Mississippi River Discharge, Qriver (cfs)

Diversion River

Figure 5. Representative diversion and river hydrographs for land evolution

forecasting associated with the Caernarvon Diversion (1994 hydrographs)

28

1227
54,000

56,000

58,000

60,000

62,000

64,000

66,000

68,000

70,000

72,000

74,000

76,000

78,000

80,000

82,000

84,000

86,000

88,000

90,000

N-90 N-91 N-92 N-93 N-94 N-95 N-96 N-97 N-98 N-99 N-00 N-01 N-02 N-03 N-04 N-05 N-06 N-07

Date

Land Area (ac)

Observed Hurricanes First Diversion FWOP Median 90% Confidence Boustany

Figure 6. Marsh area prediction for the Caernarvon Diversion from 1990-2006 with

observed acreages, model predictions with parameter uncertainty bounds, as well as

the Boustany Model predictions

29

1228
68,000

70,000

72,000

74,000

76,000

78,000

80,000

82,000

84,000

86,000

88,000

N-90 N-92 N-94 N-96 N-98 N-00 N-02 N-04 N-06 N-08 N-10 N-12 N-14 N-16 N-18 N-20 N-22 N-24 N-26 N-28 N-30 N-32 N-34 N-36 N-38 N-40

Date

Land Area (ac)

FWOP Sediment Only Nutrient Only Synergistic

Figure 7. Marsh area prediction for the Caernarvon Diversion from 1990-2040 with

isolated nutrient and sediment benefits

30

1229
0

2000

4000

6000

8000

10000

12000

14000

16000

J FMAMJ J ASOND

Date

Diversion Discharge, Qdiv (cfs)

0

200000

400000

600000

800000

1000000

1200000

1400000

Mississippi River Discharge, Qriver (cfs)

2003 Large - In Large - Out Small - In Small - Out Constant MS River - 1994

Figure 8. Hydrographs considered in Caernarvon Diversion operational

optimization

31

1230
72000

74000

76000

78000

80000

82000

84000

86000

88000

2001 2006 2011 2016 2021 2026 2031 2036 2041 2046

Date

Marsh Area (ac)

2003 Large - In Large - Out Small - In Small - Out Constant

Figure 9. Land evolution predictions for multiple operational scenarios at the

Caernarvon Diversion

32

1231
0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

J FMAMJ J ASOND

Date

Diversion Discharg,e Qdiv (cfs)

0

200000

400000

600000

800000

1000000

1200000

1400000

Gate - 2003 Weir - 100ft Weir - 200ft Siphon-1 X 15ft Pipe Siphon- 1 X 6ft Pipes MS River - 1994

Figure 10. Calculated hydrographs for various structure types at the Caernarvon

Diversion

33

1232
75000

80000

85000

90000

95000

100000

105000

110000

115000

2001 2006 2011 2016 2021 2026 2031 2036 2041 2046

Date

Marsh Area (ac)

Gate - 2003 Weir - 100ft Weir - 200ft Siphon-1 X 15ft Pipe Siphon-1 X 6ft Pipe

Figure 11. Land evolution predictions for various structure types at the

Caernarvon Diversion

34

1233
Tables

Table 1. Sediment Ratings for Rivers on the Louisiana Coastal Plain

River Gauge Location a1 a2 R2

Mississippi Belle Chase Surface* 3.205E-07 2.000 0.6648

Belle Chase 1.237E-08 2.320 0.7302

Tarbert - 1949-1975 1.192E-04 1.702 0.7945

Tarbert - 1975-2007 7.096E-03 1.342 0.7689

St. Francisville 6.501E-04 1.507 0.7357

Atchafalaya Melville 4.941E-06 1.937 0.7764

Simmesport 8.286E-04 1.563 0.8138

All ratings developed from suspended sediment concentrations and water

discharges from USGS Website except "Belle Chase Surface"

*

Surface concentrations of suspended sediment at Belle Chase and Tarbert's

Landing Discharges (Snedden et al., 2007)

35

1234
36

Table 2. Hydraulic roughness height as a function of bed material grain size

Channel Boundary Roughness Height, z0

1

ft mm m

Mud 6.6E-04 0.2 2.0E-04

Mud/Sand 2.3E-03 0.7 7.0E-04

Silt/Sand 1.6E-04 0.05 5.0E-05

Sand (unrippled) 1.3E-03 0.4 4.0E-04

Sand (rippled) 2.0E-02 6 6.0E-03

Sand/Shell 9.8E-04 0.3 3.0E-04

Sand/Gravel 9.8E-04 0.3 3.0E-04

Mud/Sand/Gravel 9.8E-04 0.3 3.0E-04

Gravel 9.8E-03 3 3.0E-03

1

Adapted from Soulsby (1983, Table 5.4)

1235
Table 3. System properties and land evolution model parameters for the Caernarvon Diversion to Breton Sound Estuary

Parameter

Best

Estimate

Approximate

Standard Deviation

General System Properties

Initial Land Area (ac)# 86,591 -

Project Area (ac)# 148,018 -

Average Water Depth,

H (ft)* 3 0.5

Average Water Width,

B (ft) 65,000# 1,000*

Maximum Tidal Velocity,

Utide,max (ft/s)* 0.6 0.1

Roughness Height, zo (ft)* 0.005 0.0005

Land Loss Rate (%/y)1 -0.42 0.042

Bulk Density,

ρbd (g/cm3

) 0.26 -

Sediment Rating of Surface Concentrations of the Mississippi River at Belle Chase2

Coefficient 3.205E-07 3.21E-08

Exponent 2.000 -

Size Fraction of Belle Chase Rating2

Sand 0.01 0.0017

Silt 0.63 0.1050

Clay 0.36 -

Floc Fraction* 0.3 0.0667

37

1236
38

Parameter

Best

Estimate

Approximate

Standard Deviation

Approximate Fall Velocity3 (m/s)

Sand 1.00E-02 8.33E-04

Silt 3.00E-04 2.50E-05

Clay 7.00E-06 5.83E-07

Floc Fraction 2.00E-04 4.00E-05

Marsh Nutrient Requirements

Plant Productivity Rate, Pr (g/m2yr)* 4,150 415

Percent of N and P in Plant Biomass, γTNP(%)4 0.72 0.072*

Nutrient Loading to Marsh

Background Concentration of N and P, Cbackground (mg/L)5 0.34 0.034*

Sourcewater Concentration of N and P, Csource (mg/L)# 2.28 0.5*

Nutrient Retention, Rnut (%)* 50 10

1Land loss rate calculated from observed marsh acreage from 1978-1990

2Data for rating and size fraction from Snedden et al. (2007)

3Calculated from method of Soulsby (1997)

4Foote and Reynolds (1997)

5Hyfield (2004)

#Available data

*Best professional judgment

1237
Symbols

b = Rouse parameter

d = Diameter of siphon

fi = Sediment size fraction i

g = Acceleration due to gravity

u* = Shear velocity

x = Longitudinal or down-marsh coordinate

y = Horizontal or cross-marsh coordinate

z = Vertical coordinate

z0 = Hydraulic roughness length

za = Reference depth

zriver = River stage

zmarsh = Marsh Elevation

zweir = Weir Elevation

A = Marsh area

Aveg = Vegetated area of receiving area

Anut = Total aerial nutrient benefit from flow diversion

Ased = Total aerial sediment benefit from flow diversion

Asiphon = Cross-sectional area of siphon

B = Average marsh width

Bweir B = Weir width

C = Suspended sediment concentration

Ca = Suspended sediment concentration at reference elevation za

Criver = Suspended sediment concentration of river

Csource = Nutrient concentration of source water

Cweir = Theoretical weir coefficient

Esus = Percent of wetland sustained by nutrient loading

H = Average marsh depth

Kz = Vertical diffusivity

L = Average marsh length

LRreq = Marsh required nutrient loading rate

LRdiv = Loading rate of nutrients from the flow diversion

LRbackground = Background loading rate of nutrients from preexisting marsh sources

LRnet = Net loading rate of nutrients from diversion and background sources (=LRdiv -

LRbackground)

Pr = Primary Production

Qdiv = Volumetric water discharge through diversion

Qs,river = Sediment discharge of river

Qs,div = Sediment discharge of diversion

Qs,net = Rate of sediment discharged to and retained in marsh

Ri = Sediment retention of size fraction i

RT = Total sediment retention factor

T = Time required for particle settling

U = Daily mean velocity with tidal and diversion related components

Ui = Instantaneous mean velocity with tidal and diversion related components

39

1238
Udiv = Diversion induced velocity (= Qdiv / HB)

Umax,tide = Maximum tidal velocity (tidal velocity amplitude)

Vsiphon = Velocity of flow in siphon

Ws = Natural settling velocity

Ws,eff = Effective settling velocity due to natural settling and turbulence

X = Transport distance of suspended sediment

δ = Land change rate (% / time)

δnut = Nutrient suppressed land change rate (% / time)

γnut = Percent of plant biomass made up of nutrients

κ = von Karman’s constant (0.4)

ω = Tide phase

ω0 = Tide phase of the up-crossing zero velocity

ω1 = Tide phase of the down-crossing zero velocity (=ω0+ π)

ω2 = ω0+ 2π

40

1239
Appendix L (Vol VI) Engineering

______________________________________________________________________________

EIS WRDA 2007 Section 7006(e)(3) August 2010

L-313

ANNEX 2

3815

ERDC-SAND2 Model Verification

1240
Appendix L (Vol VI) Engineering

______________________________________________________________________________

EIS WRDA 2007 Section 7006(e)(3) August 2010

L-314

ERDC-SAND2 Model Verification

Verification of the SAND2 model was conducted by simulating the effects of the

freshwater diversions (siphons) at Naomi and West Pointe a la Hache, both of which

began operating in 1993 (Figure A), and the larger Caernarvon Freshwater

Diversion Project, which began operating in 1991.

Figure A. Locations of the diversions simulated using the SAND2 model.

Daily discharge information from each of these diversions was used as input into

the SAND2 model. Wetland acreages from the respective influence areas, from

1956 to 1990 were used to determine pre-diversion wetland loss rates. The SAND2

model was then used to predict post-operation wetland acreages. Those predicted

acreages were then compared to post-operation observed wetland acreages to verify

model results.

The SAND2 model did a reasonably good job forecasting Caernarvon benefits until

2005 when Hurricane Katrina caused severe marsh loss in the influence area.

Because the model does not incorporate effects of major storm impacts, the modelpredicted acreages differed dramatically from observed acreages following Katrina

(Figure B).

1241
Appendix L (Vol VI) Engineering

______________________________________________________________________________

EIS WRDA 2007 Section 7006(e)(3) August 2010

L-315

Figure B. SAND2 simulation of the Caernarvon Freshwater Diversion (1991-2006).

Compared to the 8,000 cubic feet per second (cfs) design maximum discharge for the

Caernarvon Diversion structure, the maximum discharge of the 2 siphons is roughly

2,000 cfs. Although the SAND2 model did a fairly good job predicting the effects of

the West Pointe a la Hache Siphon (Figure C), the predicted results tended to

underestimate actual observed wetland acreages.

54,000

59,000

64,000

69,000

74,000

79,000

84,000

89,000

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Time (yr)

Marsh Area (ac)

Diversion Begins

Observed

Predicted FWOP

Predicted FWP

1242
Appendix L (Vol VI) Engineering

______________________________________________________________________________

EIS WRDA 2007 Section 7006(e)(3) August 2010

L-316

Figure C. SAND2 simulation of the West Pointe a la Hache Siphon (1993-2007).

Likewise, the SAND2 results also underestimated wetland acreage in the area

influenced by the Naomi Freshwater Diversion Siphon (Figure D). The

underestimate for the Naomi Siphon may be related in part to the large and

relatively deep open water included within the siphons influence area. Exclusion of

this area, or a reduction in the influence area size, may have improved the accuracy

of model results. This issue highlights the influence of project area selection on

model results. Ideally, a hydrologic model or other systematic method to

determining the project area (diversion influence area) is needed to achieve the best

model results. Unfortunately, there was not sufficient time to conduct model runs

to determine the potential ARTM diversion influence areas for each freshwater

introduction measure. Instead, influence area polygons were determined using best

professional judgment.

The SAND2 verification work, and other work with the SAND2 model indicates that

it is most applicable in interior marsh systems. When applied to open bays or large

lakes, it appears to substantially overestimate land-building. This may be related

to resuspension and export of deposited sediments, a process that the model does

not address. The ARTM measures, however, are all generally interior locations

which are handled well by the SAND2 model. Unfortunately, no examples of

freshwater introductions without sediment are available to verify the application of

the SAND2 model for nutrient-only situations.

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

10,000

11,000

12,000

13,000

14,000

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

Time (yr)

Marsh Area (ac)

Diversion Begins

Observed

Predicted FWOP

Predicted FWP

1243
Appendix L (Vol VI) Engineering

______________________________________________________________________________

EIS WRDA 2007 Section 7006(e)(3) August 2010

L-317

Figure D. SAND2 simulation of the Naomi Freshwater Diversion Siphon (1993-

2006).

24,000

24,500

25,000

25,500

26,000

26,500

27,000

27,500

28,000

28,500

29,000

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

Time (yr)

Marsh Area (ac)

Diversion Begins

Observed

Predicted FWOP

Predicted FWP

1244
Appendix L (Vol VI) Engineering

______________________________________________________________________________

EIS WRDA 2007 Section 7006(e)(3) August 2010

L-318

ANNEX 3

MCASES Cost Analysis

For Internal Use Only

1245
 	


USACE WHITE DITCH

EVALUATION AND DESIGN

HYDRODYNAMIC AND SALINITY TRANSPORT MODELING

Prepared for

USACE

June 4, 2010

URS Corporation

1625 Summit Lake Drive, Ste. 200

Tallahassee, FL 32317

1246

  

i

 	 

		

  
 	

2.1 Bathymetry............................................................................................... 2-1

2.2 Tide Stage ................................................................................................ 2-1

2.3 Meteorological Data................................................................................. 2-1

2.4 Salinity..................................................................................................... 2-2

2.5 Caernarvon Flows .................................................................................... 2-2

2.6 Bathymetric Survey Data......................................................................... 2-3

2.7 URS Field Investigation........................................................................... 2-3

2.7.1 Water Level.................................................................................. 2-3

2.7.2 Salinity......................................................................................... 2-3

  
 	

    	

4.1 Model Selection ....................................................................................... 4-1

4.2 Model Domain and Grid Generation ....................................................... 4-2

4.3 Boundary Conditions ............................................................................... 4-4

     	

 ! " #
!	

6.1 Alternatives Analysis............................................................................... 6-1

6.2 Preliminary Evaluation/Initial Screening................................................. 6-1

6.3 Sea Level Rise Simulations ..................................................................... 6-2

6.4 Long Term Simulations at Location 3 ..................................................... 6-2

 $ 
$	

 % &' %	

1247
  
   

ii

Tables

Table A Grid Configurations and Flow Capacities

Table B No Project Simulations Boundary Conditions

Table C Sea Level Rise Scenarios

Table D Boundary Condition Inputs for Long-Term Simulations at Location 3

Table E Time Period and Naming Convention for Long-term Simulations at

Location 3

Figures

Figure 1 Study Area

Figure 2 Alternative Locations

Figure 3 Existing DEM and Contour Data

Figure 4 Station Locations

Figure 5 Sample Tide Record

Figure 6 Monthly Average Tide Stage at the Bay Gardene Station for Period 2000-

2009

Figure 7 Wind and Rainfall Station Locations

Figure 8 Pilot East 2008 Wind Rose

Figure 9 Belle Chasse Rainfall Data

Figure 10a Monthly Average Salinity at the Bay Gardene Station for Year 2009

Figure 10b SONRIS Salinity Data

Figure 11 Seasonal Flows from Caernarvon Freshwater Diversion

Figure 12 Transect Locations

Figure 13 Sample of the Surveyed Cross-Sections

Figure 14 Sample of the Surveyed Cross-Sections

Figure 15 Salinity and Velocity Sampling Stations

Figure 16 Additional URS Field Locations

Figure 17 Measured Stage Data

Figure 18 Salinity Sampling Results

Figure 19 Model Domain

Figure 20 Water Polygon Data from the LA GIS Digital Map Compilation DVD

Figure 21 USGS Water Area Changes Study Results

Figure 22a Final Polygon Set

1248
  
   

iii

Figure 22b Final Polygon Set in White Ditch Study Area

Figure 23 Survey Data Distribution

Figure 24 Effective Depths and Locations from Cross-Section Transect Data

Figure 25 Template of Water Body Depths

Figure 26 Scatter Set Used for Grid Generation

Figure 27 Enlarged Portion of Point Grid Data

Figure 28 Final Grid and Grid Information

Figure 29 Depth Contours

Figure 30 Grid Cell Resolution in area of interest (top) and showing number of cells

in canals and rivers (right)

Figure 31 Grid with Boundary Cellstring Locations

Figure 32 Boundary Input Data

Figure 33 Sensitivity of the Tide Calibration to the Datum Shifts in the Bay Gardene

Stage Data

Figure 34 Final Stage Calibration

Figure 35 Typical Response of Salinity During a Calibration Simulation

Figure 36 Final Salinity Calibration

Figure 37 Location 2

Figure 38 Location 3

Figure 39 Location 2 5000 cfs Capacity Cross-Sections

Figure 40a Location 3 5000 cfs Capacity Cross-Sections

Figure 40b Location 3 5000 cfs Capacity Cross-Sections

Figure 40c Location 3 5000 cfs Capacity Cross-Sections

Figure 41 35,000 cfs Capacity Alternative 2 Depth Contours

Figure 42 35,000 cfs Capacity Alternative 3 Depth Contours

Figure 43 Sequence of Salinity Distributions at Location 2 with 35,000 cfs Capacity

Grid.

Figure 44 Sequence of Salinity Distributions at Location 3 with 35,000 cfs Capacity

Grid.

Figure 45 Time-averaged Salinities for Final 7 days of the Simulation at Location 2.

Figure 46 Time-averaged Water Depths for Final 7 days of the Simulation at

Location 2.

Figure 47a Salinity Time Series Results at Points throughout the White Ditch Area

Figure 47b Salinity Time Series Results at Points throughout the White Ditch Area

1249
  
   

iv

Figure 48 Final Week Salinity Simulation Results from the 35,000 cfs Capacity at

Location 3 Summer Simulation at Maximum Flow

Appendices

Appendix A Discussion of Bay Gardene Tide Gage Datum

1250

 
ONE 

1-1

1. Section 1 ONE Introduction

The White Ditch project area is located in the Breton Sound estuary and covers the area

extending north and south from just south of Belair, Louisiana to the coastline of Louisiana and

extending east and west from the Mississippi River to the Oak River. This area extends about 50

km in the NW-SE directions and about 30 km in the SW-NE direction. Subsidence, erosion,

channelization, saltwater intrusion, storm damage and the absence of fresh water, sediments and

nutrients from the Mississippi River have all caused significant adverse impacts to the White

Ditch project area resulting in extensive wetland loss and ecosystem degradation. There is an

existing siphon at the mouth of White Ditch that was built in 1963 and has not been in operation

since 1991, except for two brief episodes.

The absence of a supply of fresh water, sediment, and nutrients has caused the marsh to degrade.

This degradation coupled with the subsidence and a sea level rise rate of approximately 1.04 cm

per year has led to an increase in saltwater intrusion. The additional influx of saltwater from the

Gulf of Mexico through the vast canal network in the project area has further damaged the marsh

vegetation. In August and September of 2005 Louisiana was hit by hurricanes Katrina and Rita.

These hurricanes brought high winds and high tidal surges and destroyed thousands of acres of

already weakened marsh. In September of 2008 hurricanes Ike and Gustav also hit the Gulf

coast. While they did not make direct landfall in the project area, the tidal surges from these

storms caused the loss of additional marsh acreage.

The White Ditch area is part of the Breton Sound estuary system. Breton Sound estuary is

located in southern Louisiana, between Breton Sound Bay and approximately the last 85 miles of

the Mississippi River before it discharges into the Gulf of Mexico. The estuary consists of about

430 square miles (1,100 km2) of fresh and brackish coastal wetlands that are made up of shallow

water ponds, lakes, bays, and a man-made canal system (Figure 1). The major rivers in the

estuary are the Oak River (also known as River aux Chenes) and Bayou Terra aux Boeufs. The

larger water bodies are Big Mar, Lake Leary, Spanish Lake, Grand Lake, and Little Lake.

On the northern edge of Breton Sound estuary is the Caernarvon freshwater diversion structure.

It is located on the east bank of a Mississippi River oxbow at river mile 81.5. The diversion

structure began operating in 1991 as a means for establishing optimal salinity conditions for

oyster production, and can also be used to prevent saltwater intrusion during storms or droughts.

The USACE is investigating alternative designs for a fresh water diversion from the Mississippi

River to the White Ditch project area. Two alternative locations (Locations 2 and 3) are proposed

for the diversion near White Ditch and are shown in Figure 2. Location 2 uses a modification of

the existing siphon at White Ditch. Location 3 is located farther to the south. At both alternative

locations, different channel depths and widths are considered for different peak diversion flow

rates, ranging from 5,000 to 100,000 cfs. Location 2 also includes culverts located throughout

the modified channels to provide connectivity with the marsh areas.

The alternatives are evaluated in terms of their impact on water depths and salinities throughout

the study area. A hydrodynamic and salinity model has been developed to quantify the impacts

of each alternative and evaluate the effects of diversion flow operations on the water depth and

salinity. The results of the hydrodynamic and salinity model simulations were post-processed

and used as input for the Wetland Value Assessment model to quantify the environmental

benefits of the diversion. In addition to assessing environmental benefits such as the impacts on

plant and animal communities in the project area, the stage data was also used to estimate

potential flooding impacts for each alternative.

1251

 
ONE 

1-2

This report describes the hydrodynamic and salinity modeling analyses used to evaluate

alternative designs and flow rates. The application of the wetland value assessment and other

analyses were conducted by the USACE and are reported separately.

1252

 
TWO   !

2-1

2. Section 2 TW O Backgrou nd D ata

There were a number of existing data sets available to support the configuration, calibration and

application of the hydrodynamic and salinity transport model. In addition to the existing data

sets, a bathymetric survey and a field measurement program were conducted prior to the

modeling analysis in order to provide site-specific data. Each of these data sets is briefly

described below.

	 ()*+(&*

There was sparse existing data within the coverage area, and the resolution and precision of any

available data was insufficient for model use. Digital Elevation Model (DEM) and contoured

elevation coverages were available at http://atlas.lsu.edu/rasterdown.htm for portions of the

modeled area (Figure 3), however the elevation values available in these datasets did not contain

the resolution necessary for use in the model.

 (
+ (,+

Real-time tide data were downloaded from http://waterdata.usgs.gov/nwis for three U.S.

Geological Survey (USGS) stations. Station locations include: Northeast Bay Gardene (Station

ID: 7374527), Black Bay near Snake Island (Station ID: 7374526) and Cow Bell at American

Bay (Station ID: 73745258). Tide data were also obtained from http://tidesonline.nos.noaa.gov/

for the National Oceanic and Atmospheric Administration (NOAA) Station Pilot East (Station

ID: 8761305). Station locations are shown in Figure 4. Time series plots of sample portions of

the tide data are shown in Figure 5.

A review of the tide gages revealed that there were no suitable gage locations in the proximity of

the White Ditch area. The closest gages were Cow Bell at American Bay and Northeast Bay

Gardene. Data from the Bay Gardene station was chosen for use in the modeling analysis since it

provided the widest date range of available data with the fewest data gaps.

A plot of the monthly average water elevations for the period 2000-2009 for the Bay Gardene

station is shown in Figure 6. The data show that the stage tends to be higher in the fall, which

corresponds to the period when the winds are predominantly from the Southeast.

 +(+-&-.-,
. (

Wind data are available from various stations in the project area. The wind data were collected

by NOAA from 1999 through 2009 (http://www.ncdc.noaa.gov/oa/ncdc.html). Louisiana wind

station locations include: Grand Isle (Station Number 8762417), Pilot East (Station Number

8760922) and Shell Beach (Station Number 8761305). The locations of these stations are shown

in Figure 7. Hourly data was available from the Pilot East station and was downloaded for the

time period of 3/25/2004 through 7/23/2009. A wind rose based on data collected at the Pilot

East station during the year 2008 is shown in Figure 8.

Rainfall data were obtained from the NOAA Port Sulfer Station (Station 167471) and from a

Belle Chasse station. Station Locations are shown in Figure 7. The data included a daily sum of

rainfall in inches for 1/1/2004 through 8/27/2009 for Port Sulfur and 9/28/2006 through

8/20/2009 for Belle Chasse. Annual and seasonal rainfall patterns are shown in Figure 9 for the

Belle Chasse data set.

1253

 
TWO   !

2-2

There were no daily evaporation data available from stations near the project area. In order to

provide some information for evaporation rates, data in the literature was reviewed. A study

conducted by Cooke et al. (2008) provided measured data at a variety of stations in Louisiana.

The nearest station for which summer evaporation rates were available was Houma. The data

indicate some daily fluctuations do occur, ranging between 2 and 8 mm/day, with an average rate

on the order of 5 mm/day.

 .
/
(*

Salinity data are available from the USGS and were obtained from the website:

http://waterdata.usgs.gov. Data from three Louisiana stations including Northeast Bay Gardene

(Station ID 7374527), Black Bay near Snake Island (Station ID 7374526), and Cow Bell at

American Bay (Station ID 73745258) were obtained. The station locations are shown in Figure

4. The monthly average salinities for 2009 for the Bay Gardene station are shown in Figure 10a.

Another salinity data set was available from Strategic Online Natural Resources Information

System (SONRIS). This data set included hourly or monthly salinity measurements and stations

were located throughout the Breton Sound with varying periods of record). Station locations are

shown in Figure 10b, and average, max and minimum salinity values at stations with sufficient

data are shown in the table in Figure 10b. The average salinity is lowest in the spring and is

controlled by Freshwater from the Caernarvon Diversion and the Mississippi River, which are

the two freshwater sources for this area.

 +&/&0-/ 1.-2

On the northern edge of Breton Sound estuary is the Caernarvon freshwater diversion structure.

It is located on the east bank of a Mississippi River oxbow at river mile 81.5. The diversion

structure began operating in 1991 as a means for establishing optimal salinity conditions for

oyster production, and can also be used to prevent saltwater intrusion during storms or droughts.

The 23-meter-wide structure has the capacity to divert up to about 8,000 cfs (226 m3

/s) of

Mississippi River water into the Breton Sound estuary, and has been managed at many different

discharge rates since its commencement.

The US Army Corps of Engineers (USACE), New Orleans District, manages the Caernarvon

Freshwater Diversion Project and provided daily flow data in cfs from 1992 through 2009. The

seasonal flows from the diversion are shown in Figure 11.

Based on discussions with local land managers, it is believed that the flow from the diversion

followed two dominant paths form the diversion. The main one is to the south through the

Bayou Mandeville area. The second one is directed to the west, through the Delacroix Canal,

and ultimately merges with the Oaks River. It is believed that about 20 to 30 percent of the

diversion flows went through the western path until Hurricane Katrina impacted the area. After

Katrina, many of the smaller channels to the west were clogged with debris, and it is believed

that only 5 to 10 percent of the diversion flow now flows westward.

1254

 
TWO   !

2-3

! ()*+(&
 3&0+* (

The USACE conducted a bathymetric survey of the White Ditch area to support both the

modeling analysis and the alternative designs. The survey transects are shown in Figure 12. The

surveyed cross-sections are shown in a sequence of plots in Figures 13 and 14. These data

provide information on the channel depths and widths, the lake depths, elevations of ridges

bounding the channels as well as the characteristics of the inter-tidal and land areas.

$ 3&1
+. 
/0+(
,(
-/

The White Ditch field investigation was conducted from July 20 through July 23, 2009 to collect

necessary calibration data for the CMS-Flow hydrodynamic model of the study area. The field

investigation was conducted by two crews of URS field staff operating from airboats hired for

the project. The field crews were accompanied by William Terry of the U.S. Army Corps of

Engineers (USACE) St. Louis District Office for most of the field investigation. A detailed

report of the field program, its implementation and an analysis of the data were provided to the

USACE as a deliverable on 9/28/2009 (URS, 2009). The two data sets explicitly used in the

modeling analysis, the water elevations and the salinity data, are summarized here.

The study area and sampling stations are shown in Figure 15. Measurements of flow velocity,

temperature, salinity and turbidity were collected periodically between July 21 and 23, 2009 at

the primary stations (N1, N2, N3, S1, S2, and S3). Water level measurements were collected at

stations N3 and S3 from July 20 to July 23, 2009 using temporary staff gauges and recording

pressure transducers that were installed at these locations.

Less frequent flow velocity, temperature and salinity measurements were collected at the

secondary locations (Oak River Channel, N4, N5, N6, S4, S5, S6, S7, S8, S9, S10, and S11).

Water depth measurements were collected at each of the primary and secondary locations, and at

additional field locations (S12-S33) shown on Figure 16.

$	 2 ."

Staff gauges and recording pressure transducers were installed at locations S3 and N3 to measure

water level fluctuations within the study area. The transducers used were Micro-Diver

Dataloggers (Model DI601) manufactured by the Schlumberger Corporation. The data loggers

were initially programmed to collect pressure measurements every five minutes in the units of

feet of water. The sample interval was changed to 30 seconds after approximately 24 hours.

Staff gauges constructed of 1-inch diameter PVC pipe were also installed at locations S3 and N3.

Periodic measurements of the water level at each staff gauge were recorded. The measured stage

data collected at the two stations are shown in Figure 17. When compared to the tides at the Bay

Gardene Station, it is evident that there is a significant loss of tidal amplitude as the tides

propagate into the White Ditch area.

$ 4

Salinity data (as well as temperature and turbidity measurements) were collected at each primary

location and other select locations (shown on Figure 15) using a HydroLab Quanta system. The

median, maximum and minimum salinity at each station are shown in Figure 18. The SONRIS

1255

 
TWO   !

2-4

salinity data are also shown in Figure 10b, and although the data represent different time periods,

they show a general trend in the salinity patterns. The trends show a basic low to high salinity

gradient from offshore to the NW as well as a high to low gradient from the east bank of the

Mississippi River to the NE. The general gradients, even those in the White Ditch area, point

towards the Caernarvon Diversion, indicating that it is a significant source of freshwater in the

area.

Salinity measurements were also made at surface and bottom – the data indicate a very minor

difference between top and bottom – less than 0.5 ppt.

1256

 
THREE  "

3-1

3. Section 3 THR EE Conceptual Models

A conceptual model for the analysis has been developed based on the project goals and the data

summary. The key points considered in developing the conceptual model are discussed below:

• The area of interest is large with a network of inter-connecting channels and lakes with

varying widths and depths. The land elevations and tide ranges indicate that the tidal

flows will be contained to the channels during lower tide stages but may inundate the

land segments during higher tide stages.

• The proposed Alternatives include relatively high flow rates, up to 100,000 cfs that will

likely flood the land areas, at least in the vicinity of the discharge.

• The salinities are controlled by rainfall and evaporation and freshwater from the

Caernarvon Diversion and the Mississippi River. The effects of the Mississippi river are

inherent in the salinity data at the USGS gages near the southern extent of the study area.

• Salinity transport in the White Ditch area will also be affected by wind driven circulation.

• The time scale for salinity to reach steady state is relatively large for ambient conditions

(including Caernarvon), on the order of one month but will be shorter for high-flow

White Ditch diversions

• The proposed Alternatives include culverts to route freshwater to the White Ditch area

and therefore these structures will require representation in the modeling analysis.

• The salinity data available from the field study indicate that there is very little vertical

stratification, indicating the depth-averaged modeling is suitable

The components of the conceptual model that were developed based on the above considerations

are described below:

• The model boundaries should extend from the Mississippi River levees from the

northwest and southwest to the Mississippi River-Gulf Outlet (MRGO) channel to the

northeast and to the general vicinity of the Bay Gardene USGS station to the southeast.

This domain includes the majority of the area influenced by the Caernarvon Diversion,

which is important to properly represent its influence on the White Ditch area.

• The details of the intricate network of channels will need resolution in the model grid.

The most detailed resolution should focus on White Ditch area but at least include large

conveyance channels in the area to the east of the Oak River. This component will

require grid cell dimension on the order of 10 to 30 meters in the White Ditch area.

• The model needs to include a simulation of tides, winds, diversion discharges, rainfall

and evaporation and salinity transport.

• The simulations will require the representation of significant wetting and drying of land

segments throughout the area, especially during larger White Ditch diversion flows

• The modeling analysis needs to represent the location and conveyance of culverts on the

flow

• A 2D depth-average model is suitable for the analysis

1257

 
FOUR " #

4-1

4. Section 4 F OUR Modelin g Appro ach

	 -+. +.+(
-/

A number of hydraulic models were considered for use in simulating the White Ditch diversion

alternatives. The candidate models are listed below and organized into finite element and finite

volume categories. In general, the finite element models have unstructured meshing capabilities

that allow for the efficient detailed resolution of small features, However, they are difficult to

implement in projects with large areas of wetting and drying, often requiring excessive

bathymetric and topographic smoothing to achieve a stable solution.

finite element models

ADCIRC – unstructured mesh

no salinity, poor wetting and drying

FESWMS – unstructured mesh,

no salinity, poor wetting and drying

RMA2 – unstructured mesh, salinity transport

poor wetting and drying

finite volume models

CMS– salinity transport, good wetting and drying

rectilinear mesh

EFDC – salinity transport, good wetting and drying

curvilinear mesh

FVCOM – unstructured mesh, good wetting and drying

commercial availability

POM– salinity transport, good wetting and drying

curvilinear mesh

The finite difference models typically will not have any stability problems when considering

wetting and drying, but often do not have the benefits of unstructured meshes since they typically

use rectilinear or curvilinear structured meshes. The FVCOM model is unique in that it is a

finite volume model that uses an unstructured mesh and therefore can realize the mesh

generation benefits often associated with finite elements. However, the model is relatively new

and limited to research applications. Non-research applications are occurring but model

documentation and general industrial familiarity with the model are not mature. The remaining

three finite volume models (CMS, EFDC and POM) all have similar capabilities and are suitable

for the project.

Of those three, CMS is supported by the USACE and therefore was selected for the project.

CMS-Flow is a process-based 2D depth-averaged hydrodynamic, sediment transport and

morphology model developed by the USACE for application in and around inlets and channels.

It is accessible via the Surfacewater Modeling System (SMS) graphical user interface (Militello,

2004; Buttolph, 2006).

1258

 
FOUR " #

4-2

 -+. -
/ / ,&
 ,+/+&(
-/

The model domain is shown in Figure 19. The domain includes all of the white ditch area as

well as an extensive portion of Breton Sound. A primary reason for including the larger portion

of Breton Sound was the potential influence of the diversion peak flows on the east of the Oaks

River. Also, the channels providing flow pathways from the Caernarvon Diversion to the White

Ditch area required inclusion since the Caernarvon Diversion flows provided a significant

portion of the freshwater to the White Ditch area (the other freshwater source being rainfall).

To provide bathymetric data for the model grid, a project-specific bathymetric and topographic

data set was developed. This data was then used to set the bottom elevation of the cells in the

model grid. Initial experiments with the model indicated that the grid resolution in the White

Ditch area would need to be on the order of 10 to 30 meters. This level of resolution would

provide sufficient resolution of the channel features but allow for reasonable simulation times on

high-end workstations. Therefore, the bathymetric and topographic data should have a minimum

resolution of 10 meters in the White Ditch area.

The area bathymetry and topography were developed from existing bathymetric data, land/water

boundary data and results from the project field survey. It was determined early in the

bathymetric data development that existing bathymetric data were limited to areas above MSL

and sets did not provide sufficient precision or resolution for direct use in the grid generation.

Therefore the following approach was used to develop the bathymetric and topographic data set.

1. Acquire the most recent land/water boundary data

2. Update the land/water boundary data for Post Katrina conditions

3. Divide the land/water boundaries into small polygons representing channels, lakes, land

segments and other features

4. Assign depth/elevation to each polygon

5. Convert the polygons to a 10 meter grid and export

6. Import the 10 meter grid into SMS and use to populate the CMS grid

Several datasets of land and water polygons were obtained for use in developing the bathymetric

dataset; one from the Louisiana GIS Digital Map Compilation DVD (2007) and one from the

ESRI Streetmap dataset. The land/water polygon data from the LA GIS Digital Map Compilation

DVD was used to start the bathymetric data processing. This polygon data represents preKatrina conditions and is shown in Figure 20 overlaying post-Katrina aerial images. It is clear

that there were some significant changes in the land mass as a result of Katrina in the White

Ditch area, especially in the NW region. These changes were confirmed in a USGS study, the

results of which are shown in Figure 21. Therefore, in order to update the land/water polygons,

polygons from the ESRI dataset were merged with the LA GIS data and subsequently modified

to best reflect the post-Katrina conditions. Additional digitizing was conducted so that the final

set of polygons reflected the land and water boundaries as depicted in the most current aerial

photography available for the area. Additional reviews of the polygon data set indicated that not

all of the canals in the study area were completely represented in the processing up to this point.

Canals not represented were digitized and canal water body connections that were inaccurate

were modified. The final set of polygons is shown in Figures 22a and 22b.

1259

 
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The next step is to assign depth values to each of the polygons in the data set. As pointed out in

Section 2, there was no comprehensive bathymetric data set available. In order to assign depths,

information from the project bathymetric survey and NOAA nautical chart data were used. The

first step was to set the land elevation. For this purpose, all of the survey data was pooled and

sorted to identify the distribution and range. The distribution of the data is shown in Figure 23.

There is a distinctive break in the distribution at elevation 0 ft (NAVD 88) that is likely

representative of MSL, where the channel and lake banks are steepest. Assuming that most of

the inter-tidal zones and land segments lie at or above 0 ft elevation, the data was filtered to

eliminate values below 0 feet, and then resorted. The results are also shown in Figure 23, and

indicate that the median land elevation is 1 foot NAVD 88. This value was adopted as the land

elevation and all land polygons were assigned a depth of one foot.

In order to assign depth values to the canals and lakes, the survey data transects were processed

and used to develop a suitable average depth for each cross-section. Each transect cross-section

was clipped so that the only the portion below MSL remained. Then the hydraulic radius of the

cross-section was calculated. Then the cross-section effective depth was calculated so that it

would yield the same hydraulic radius as the original cross-section. This value was then

assigned to the center point of the cross-section transect and used to assign depth values in the

canal and lake polygons. The effective depths and their locations, as obtained by this procedure,

are shown in Figure 24. The effective depth data did not provide sufficient information to assign

depths to all canal and lake polygons. Therefore a generalized template for canal and lake depths

was developed and used to assign the depths to the remaining polygons. A review of Figure 24

indicates that there is a general increase in the canal and lake depths from the NW to the SE. A

template, shown in Figure 25, was developed using this trend.

After completing the depth assignments to each polygon, the depth data were interpolated from

the polygons to a point grid. The point grid consisted of 10 m spacing in the White Ditch area

and expanded to 50 m spacing to the east of the Oak River and to the SE. The 50 m resolution

was necessary to keep the file size manageable and still provide sufficient resolution of key

features. A view of the bathymetric data as reflected by the point grid is shown in Figure 26. An

enlarged portion of the point grid data is shown in Figure 27, where the points are color coded by

the assigned depths.

The point grid bathymetry dataset was imported into SMS, triangulated, and the depths were

interpolated on to the CMS grid. Based on trials in the focus area near White Ditch, a 20 meter

resolution was determined to be optimal for areas in the vicinity of the proposed diversion.

The grid was designed with 20 meter spacing in the White Ditch area with the cell spacing

expanding to the SE and SW. In these regions of grid expansion, the grid was allowed to

increase to a maximum grid cell size of 500 meters in order to keep the number of cells as low as

possible and help manage simulation run time while still providing detailed resolution in the

White Ditch study area. The final grid is shown in Figure 28. The green cells are ‘inactive’ and

represent areas protected by levees or that are above 4 feet elevation. These cells are not used in

the model simulations and are a by-product of the inherent CMS rectangular grid structure. A

QAQC process was performed in order to ensure canal connections and other components

necessary for accurate flow simulation were correctly implemented. Cell properties were

adjusted manually where appropriate. The final grid contains 866,791 active cells in 992

Columns and 569 Rows. The bathymetry as represented in the final grid is shown in Figures 29

and 30. After some initial testing, a time step of 1.5 seconds was found to provide numerically

1260

 
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4-4

stable solutions, and the model simulations (including salinity transport) were determined to take

about two days (48 hours) in order to simulate a one month period on an HP Workstation Z400

with an Intel 2.93 Ghz Xeon Quad processor and 8gb DD3 SDRam.

 -3/&* -/
(
-/

The boundary conditions required for the White Ditch model simulations included:

1. Offshore tide elevation

2. Offshore salinity values

3. Flow boundaries (flow rate and salinity)

4. Rainfall and Evaporation

5. Wind Forcing

The location of each boundary application (for White Ditch location 3) is shown in Figure 31.

Note that during the model calibration, it was found that the salinity calibration was sensitive to

both the total flow rate from the Caernarvon Diversion as well as the split between the amounts

assumed to flow through the Delacroix Canal to the west and the through Bayou Mandeville to

the south. Therefore, the grid was modified slightly in the region of the Caernarvon Diversion so

that the flow splits could be assigned directly.

1261

 
FIVE " 


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5. Section 5 F IVE Model C alibration

The hydrodynamic and salinity calibration were conducted simultaneously. This was necessary

because it was learned in the preliminary salinity calibration simulations that the salinity

calibration was sensitive to the total flow and flow split assumed for the Caernarvon Diversion.

Since these flow rates may influence the tidal response in the white ditch area, it was necessary

to conduct the hydrodynamic and salinity calibration simultaneously.

The hydrodynamic calibration period was selected to coincide with the period for which the

stage data was available from the project field program, namely the four day period July 20

through July 24th. Preliminary testing with the model indicated that the tidal flows required a

relatively short spin-up period, on the order of one-week, but it was found that the salinity

simulations required a much longer spin-up period.

The salinity calibration focused on the same period for data comparison, July 20th through July

24th, for which salinity data was available from the project field program. After some

preliminary testing with the model, it was found that a two-month spin-up was required to

eliminate the effects of the initial conditions on the solution.

For the calibration simulation, the model was configured with measured wind, tide, rainfall,

evaporation, salinity and Caernarvon flow data corresponding to the calibration period. For the

evaporation, the average value of 5 mm/day adopted from the Cooke et al. (2008) study was

used. The tide, wind and Caernarvon flow data are shown in Figure32. For the Caernarvon

diversion flows, freshwater was assumed, and the corresponding salinity was assigned a value of

zero. The initial salinity in the grid domain was set to 7.0 ppt which was an approximate average

value of the calibration data.

The key calibration parameters are:

1. Bottom Fiction (Manning’s n)

2. Lateral Dispersion

3. Fresh Water flow and flow split from Caernarvon

The calibration simulations indicated that the hydrodynamic calibration was most sensitive to the

bottom friction, with a minor sensitivity to the Carnarvon flow splits. The salinity calibration

was most sensitive to the Caernarvon Diversion flow rate and flow split, with a lower level of

sensitivity to the lateral dispersion.

An initial range for the lateral dispersion was obtained by considering the length scales of the

water bodies in the White Ditch area and the length-scale dependent dispersion values from data

summarized by Fischer (1979). For this analysis, a length scale was developed by taking the

square-root of the area of each of the polygons used to represent each water body and then

selecting the median value. The median value is approximately 300 meters, for which the

associated dispersion coefficient is 10 m2

/s.

During some initial sensitivity simulations, it was found that the stage calibration was difficult to

obtain using a reasonable range of values to the friction and dispersion parameters. Eventually,

the difficulty was traced to the gage Datum of the Bay Gardene stage data used as a boundary

condition on the southeast boundary of the grid. After some investigation and discussions with

USGS staff familiar with the gage it was determined that there was some uncertainty in the gage

datum, and therefore an adjustment to the gage data was developed. More details of the

investigation are discussed in Appendix A. The adjustment to the gage data consisted of a shift in

1262

 
FIVE " 


5-2

the stage that was based on some sensitivity of the calibration to the measured stage data. Figure

33 shows the results of the sensitivity analysis for the cases of no shift, a 0.5 foot shift and a one

foot shift in the Bay Gardene stage data. For the 0.5 and 1.0 shifts, the simulated response shows

a much smaller tide range. This is caused by the inundation of the land segments when the water

elevations are higher. The inundation dampens the tide signal causing the lower tide range. The

1.0 shift for the Bay Gardene data was adopted for the modeling calibration and all subsequent

alternatives analysis simulations.

The rational for adjusting the Carnarvon total flow is that the model grid domain does not

contain the entire area influenced by the diversion flow. Therefore, only a portion of the flow

actually drains through the region covered by the model grid. The remaining portion of the flow

drains towards the MRGO channel that is not represented in the model grid. Thus, it is

appropriate to reduce the Carnarvon flow rates so that they better represent the flow entering the

area covered by the model gird. The “best” reduction level was determined via the salinity

calibration.

It was also found that the salinity calibration was sensitive, albeit to a smaller degree, to the

assumed split of the Caernarvon flow to the west and the south. As discussed in Section 2,

historically the portion flowing to the west, directly towards the White Ditch area, was about 20

to 30 percent. However, it is believed by local land managers that after Hurricane Katrina, the

percentage flowing directly to the west is lower, due to blockage of many of the smaller canals,

and is currently about 5 to 10 percent.

After assigning the dispersion value, a sequence of final calibration simulations were completed

in which the bottom friction and the total flow and flow split for the Caernarvon were

systematically altered. The final calibration was obtained with the following parameter values:

• Manning’s n: 0.021

• Dispersion Coefficient: 10 m2

/s

• Amount of Measured Caernarvon Flow applied: 58.2%

• Amount of Applied Caernarvon Flow directed to the west: 5%

The final stage calibration is shown in Figure 34. The simulated stage calibration indicates that

the model represents the measured tide amplitude reduction and phase shifts at stations S3 and

N3. A typical time series of the salinity response in the White Ditch area is shown in Figure 35.

The decrease in the salinity values for all but the most offshore station from the initial conditions

and the asymptotic characteristic of the final values are evident in the time series data. The

values for station 39 increase, because it is closest to the offshore boundary and less influenced

by the freshwater flow from the Caernarvon diversion. The influence of the tidal excursion is

also most evident at this station.

The final salinity calibration results are shown in Figure 36 and represent the time-averaged

salinity values over the last four days of the simulation, which correspond to the time period of

the measured values obtained during the project field program. The spatial gradients and the

actual salinity levels are well represented in the simulated results. The largest discrepancy

occurs in the southern station (Simulated Salinity Point 37) where the model results slightly

under-predict the salinity levels.

1263

 
SIX $ %

6-1

6. Section 6 SIX Alt ern atives Simu lations

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The calibrated CMS hydrodynamic and salinity transport model was configured to simulate the

impacts of 12 alternative diversion designs. The alternatives are located in either of two

locations referred to as Location 2 and Location 3 as indicated in Figure 2. The USACE initially

considered another location (Location 1) but that location was discarded and not considered for

modeling evaluation.

The alternative design at Location 2 is connected to the Mississippi River with a box culvert and

consists of two main outfall channels and three distribution channels, as indicated in Figure 37.

Culverts are distributed along the channels to enhance the connectivity to the wetlands, and plugs

are placed at some junctures to control the flow. There is a short final outfall channel connecting

the second main outfall channel and the Oak River

The configuration for Location 3 is shown in Figure 38. At this location, there is one main

outfall channel connected to a second channel with a natural alignment. Ridges align the

channels and some plugs are included.

At each alternative location, six design diversion flow rates were considered. For each flow rate

a different channel cross-sectional area was used and therefore a flow-specific model grid was

configured for each of the six different flow capacities at each of the two locations (for a total of

12 grids). Flow capacities for the twelve unique grid configurations are shown in Table A.

For each alternative location and flow rate, the channels were represented in the model grid by

adjusting the grid cell elevations within the footprint of each channel. Examples of crosssections for the 5000 cfs capacity flow rate at Location 2 are shown in Figure 39 and shown for

the 5000 cfs capacity flow rate at Location 3 in Figures 40a – 40c. In general the cross-section

widths and depths increased as the design flow rates increased. An example of the 35,000 cfs

flow-rate grid at Location 2 is shown in Figure 41. The corresponding grid for the 35,000 cfs

flow-rate grid is shown in Figure 42.

The boundary conditions locations and implementation for these alternatives grids were identical

to those used in the model calibration grid (i.e. existing conditions grid) except for the addition

of the White Ditch diversion flow. A flow rate boundary condition cell string was created at the

beginning of the main diversion channel for application of the diversion flow rate in the model

simulations.

The evaluation of the alternatives was implemented in three phases:

1. Preliminary Evaluation/Initial Screening

2. Sea-level Rise Simulations

3. Long-term Simulations of the 35,000 cfs Flow Rate at Location 3

Each of these evaluations is described below.

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/,

A preliminary evaluation of the alternatives was conducted with a 29 day simulation. These

simulations provided evaluations of the impact of the diversion flow on water elevations and

salinity levels through-out the White Ditch area. For these simulations, the Caernarvon

1264

 
SIX $ %

6-2

Diversion flow was set to 8000 cfs and the water elevations for the Bay Gardene station for the

period of July 2009 were used at the offshore boundary.

Instantaneous plots of the salinity distribution during the start-up of the diversions are shown in

Figure 43 for Location 2 and in Figure 44 for Location 3. The freshwater flow through the

diversion channels and culverts into the wetlands is evident in the sequence of plots.

As the simulations were completed, the model results were processed and delivered to the

USACE for subsequent analysis. The main post-processing for these simulations were maps of

the time-averaged salinity and water depth over the last week of simulation, during which

conditions were quasi-steady, and varying only due to tidal effects. An example of the average

salinity conditions for Location 2 35,000 flow-rate design conditions is shown in Figure 45. The

corresponding plot of the time-average water depths is shown in Figure 46.

! + .+0+. &
+ 3.(
-/

Twelve 90-day sea-level rise simulations were configured and are described in Table B. For

these simulations, the existing no project conditions were used and there was no flow simulated

from White Ditch. As indicated in Table B, both the Caernarvon flow rate and tide (sea) level

were varied. Each sea-level rise was implemented by adding the rise to the water elevation time

series used at the offshore boundary condition. The water elevations for the Bay Gardene station

for the period of June through August were used for these simulations. Details of the sea-level

rise scenarios designated in Table B are listed in Table C.

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-/( .-(
-/ 

Seven additional alternatives were completed using the 35000 cfs capacity grid at Location 3.

Three simulations represented a 90 day period using the Bay Gardene water elevation data for

June – August, 2009 at the offshore boundary conditions. The diversion flows were steady at

10000, 15000, and then 35000 cfs, respectively. The flow at the Caernarvon Diversion was 1200

cfs. The results of these simulations were delivered to the USACE for further evaluation.

The remaining four simulations were 17 months long and were completed using the Location 3

35000 cfs flow capacity model grid. These model runs simulated conditions beginning during a

Spring season and continuing through the Summer of the following year. Flow rates at both the

White Ditch diversion and the Caernarvon diversion were varied throughout the simulation

period. The flow conditions for each scenario are shown in Table D.

The 17 months of simulation time was divided into eight consecutive simulations. The first seven

(a through g) each simulated two months time and the eighth simulation (h) simulated the final

three-month period. The labels a through h at the top of Table D indicates the simulation period.

For simulations 1 and 2, the simulations were started at period d, using the solutions at the end of

the previous 90 day simulations.

Tide inputs for these long term simulations were taken from measured data at Bay Gardene

Station for the entire year 2009. Data from March through December 2009 were used for the

initial ten months of simulation, and then data from January through July 2009 were used during

the last seven months of simulation.

1265

 
SIX $ %

6-3

Time series plots of salinity at seven observation locations within the model grid are shown for

simulation 3 in Figure 47a and simulation 4 in Figure 47b. The impact of the high White Ditch

Diversion flow rates during period a and f and g are very evident in the time series and the

response time of the salinity levels in the White Ditch area can be inferred from these time series.

A plot of the time-averaged salinity over the final three months of simulation period (Simulation

3h) for long-term Simulation 3 is shown in Figure 48.

1266

 
SEVEN 

7-1

7. Section 7 SEVEN Conclu sion s

The CMS Flow model was successfully configured and calibrated for the White Ditch area for

simulations of tide, flow and salinity. The model was subsequently used to evaluate various

alternative designs and operational scenarios for the White Ditch diversion.

During the calibration and implementation of the CMS Flow model, a number of assumptions

and data limitations were identified that were required in order to complete the modeling analysis

within the project schedule. In anticipation of a need for additional modeling analysis, it is

recommended that additional data collection be completed to reduce the number of assumptions

and limitations. The data categories are:

1. Additional bathymetric and topographic data

2. Additional water level and salinity data

3. Flow measurements geared towards verifying westward flow patterns from the

Caernarvon Diversion

4. Better understanding of rainfall and evaporation runoff from the land segments

Each of these topics is discussed below.

Bathymetric and topographic data

The original survey data focused on the areas adjacent to the proposed diversion. Scheduling

considerations and access rights prevent survey data collection from areas to the northwest,

southeast and across the Oaks River area. Aerial images since the impact of Hurricane Katrina

have provided suitable data for delineating the dense network of canals, streams and lakes, but

the water depths and land elevations are not well documented. For the development of the

existing model, assumptions for the water depths and land elevations were made based on the

spatial patterns derived from the available project surveys. It is recommended that additional

data, similar to the survey data collected as part of this project, also be collected. The ridge along

the Oaks River north and south of the previous survey area should also be surveyed, as this is an

important feature in the project area, controlling flows from the project area into the Oaks River.

Another area for survey data collection is along the canals that connect the Caernarvon Diversion

to the Oaks River. During the model calibration it was found that Caernarvon Diversion flow

westward to the Oaks River area had a strong impact on the salinity in the project area. Thus, an

improved delineation of the flow-ways would enhance the reliability of the model.

Additional Water Level and Salinity Data

The model calibration data set consisted of a few days of continuous water elevations at two

stations in the central area of the project. Salinity data consisted of point measurements at about

eight stations around the central project area. Although this data set did provide reasonable

constraints of water elevation and salinity, a more rigorous model calibration could be made if

continuous water elevation and salinity data could be obtained. It is recommended that

continuous monitoring of water elevation and salinity be made at stations spanning the entire

project area, and in the vicinity of the flow-ways connecting the Caernarvon Diversion flows to

the Oaks River. At least three stations would be located in the projected area, one each in the

north, central and southern portion of the project area. An additional station should be located

east of the Oaks River, in one of the major flow-ways connecting the Caernarvon Diversion

flows to the Oaks River. Measurements should be made for at least two weeks (a complete

spring-neap tide cycle), and preferably over a month or more to collect data under a larger

1267

 
SEVEN 

7-2

variety of conditions. Consideration should be given to collecting data during high and low

Caernarvon Diversion flows.

The need for sensor maintenance during deployment in a marine environment should be

considered in identifying station locations.

All water elevation sensors should be surveyed so that they can be referenced to the same

vertical datum of the bathymetric and topographic survey data.

Flow measurements for verifying westward flow patterns from the Caernarvon Diversion

During the model calibration, it was found that the simulated salinities in the project area were

sensitive to assumptions as to the total amount of Caernarvon Diversion flow that traveled

westward and south-westward towards the Oaks River and project area. At that time, only

antidotal estimates of the flow rates were available, mainly from observations of persons familiar

with the area. Thus, additional data collection to establish the flow rates would be very useful in

enhancing the model calibration. Flow measurements should be made at 2 to 5 stations in flowways connecting the Caernarvon Diversion to the Oaks River. Measurements should be made

every 1 to 2 hours over a 24-hour period. (or 12-hour period if access is not feasible at night). At

least one set of flow measurements should be collected during a spring tide and one during a

neap tide.

Better understanding of rainfall and evaporation runoff from the land segments

Another model parameter that affected the salinity in the project area was the rainfall and

evaporation rates. During the model calibration, assumption of the rainfall water balance

(evaporation, direct run-off and infiltration and groundwater discharge) had to be made. It is

recommended that two or three pressure gages be installed in shallow wells to provide

continuous water table surface elevation and salinity data during the same period that the

continuous surface water measurements are being recorded. The well should be able to be

installed using a hand auger due to the shallow depths. The pressure sensors should also be

surveyed to provide the data referenced to the same vertical datum as the bathymetric and

topographic data. The installation of automatic rainfall gages and pan evaporation measurement

systems should considered at each of the well locations.

1268

 
EIGHT 

8-1

8. Section 8 EIGHT Referen ces

Buttolph, A. M.; Reed, C. W.; Kraus, N. C.; Ono, N.; Larson, M.; Camenen, B.; Hanson, H.;

Wamsley, T. and Zundel, A. K., 2006. Two-Dimensional Depth-Averaged Circulation

Model CMS-M2D: Version 3.0, Report 2, Sediment Transport and Morphology Change.

Coastal and Hydraulics Laboratory Technical Report ERDC/CHL-TR-06-7. Vicksburg,

MS: US Army Engineer Research and Development Center.

Cooke, William H. III, Katarzna Grala, Charles L. Wax, A Method for Estimating Pan

Evaporation for Inland and Coastal Regions of the Southeastern U.S. , Southeastern

geographer, 48(2) 2008: pp. 149–171.

Fischer, H., List, J., Koh, R., Imberger, J., Brooks, N., Mixing in Inland and Coastal Waters,

(Academic Press, Inc., Orlando) 1979.

Militello, A., Reed, C.W., Zundel, A.K., and Kraus, N.C. 2004. Two-Dimensional DepthAveraged Circulation Model M2D: Version 2.0, Report 1, Technical Documentation and

User’s Guide, ERDC/CHL TR-04-2, U.S. Army Research and Development Center,

Coastal and Hydraulics Laboratory, Vicksburg, MS.

URS, White Ditch Filed Program Results, 2009, Submitted to the USACE.

1269
TABLES

1270
Table A. Grid Configurations and Flow Capacities.

Flow Rate

(cfs)

5,000 cfs

10,000 cfs

15,000 cfs

35,000 cfs

Location 2

70,000 cfs

100,000 cfs

5,000 cfs

10,000 cfs

15,000 cfs

35,000 cfs

Location 3

70,000 cfs

100,000 cfs

Table B. No Project Simulations Boundary Conditions.

Simulation

ID

Caernarvon

Flow (cfs)

Sea Level Rise

Scenario

2000 8,000 2009 Low

2500 2,800 2009 Low

3000 200 2009 Low

3500 8,000 2065 Low

4000 2,800 2065 Low

4500 200 2065 Low

5000 8,000 2065 Moderate

5500 2,800 2065 Moderate

6000 200 2065 Moderate

6500 8,000 2065 High

7000 2,800 2065 High

7500 200 2065 High

1271
Table C. Sea Level Rise Scenarios.

Scenario

Year Low feet Intermediate

feet High feet

2009 0 0 0

2015 0.2 0.2 0.3

2020 0.3 0.4 0.5

2025 0.5 0.6 0.8

2030 0.7 0.8 1.1

2035 0.8 1 1.4

2040 1 1.2 1.8

2045 1.2 1.4 2.1

2050 1.3 1.6 2.5

2055 1.5 1.8 2.9

2060 1.7 2.1 3.3

2065 1.8 2.3 3.7

1272
Table D. Boundary Condition Inputs for Long-Term Simulations at Location 3.

a bcde f g h Simulation Model Run By Flow Input Location

March April May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb. March April May June July

White Ditch 1000 1000 1000 1000 1000 1000 1000 35000 1000 1000 1000 Simulation

1 USACE

Caernarvon 500 450 750 1750 2600 3000 2000 1500 1050 950 1000

White Ditch 0 0 0 0 0 0 0 35000 0 0 0 Simulation

2 USACE

Caernarvon 500 450 750 1750 2600 3000 2000 1500 1050 950 1000

White Ditch 35000 0 0 0 0 0 0 0 0 0 15000 20000 35000 0 0 0 0 Simulation

3 URS

Caernarvon 2000 1500 1050 950 1000 650 500 450 750 1750 500 500 500 1500 1050 950 1000

White Ditch 35000 1000 1000 1000 1000 1000 1000 1000 1000 1000 15000 20000 35000 1000 1000 1000 1000 Simulation

4 URS

Caernarvon 2000 1500 1050 950 1000 650 500 450 750 1750 500 500 500 1500 1050 950 1000

Table E. Time Period and Naming Convention for Long-term Simulations at Location 3.

Total Hours Begin Month End Month

SIM 3a, 4a 1464 March AprilSIM 3b, 4b 1464 May June

SIM 3c, 4c 1488 July August

SIM 1d, 2d, 3d, 4d 1464 September OctoberSIM 1e, 2e, 3e, 4e 1464 November December

SIM 1f, 2f, 3f, 4f 1416 January February

SIM 1g, 2g, 3g, 4g 1464 March AprilSIM 1h, 2h, 3h, 4h 2208 May July

1273
FIGURES

1274
Figure 1. Study Area.

1275
Figure 2. Alternative Locations.

1276
Figure 3. Existing DEM and Contour Data.

1277
Figure 4. Station Locations.

1278
Figure 5. Sample Tide Record.

1279
Figure 6. Monthly Average Tide Stage at the Bay Gardene Station for Period 2000–2009.

1280
Figure 7. Wind and Rainfall Station Locations.

1281
Figure 8. Pilot East 2008 Wind Rose.

1282
Figure 9. Belle Chasse Rainfall Data.

1283
Figure 10a. Monthly Average Salinity at the Bay Gardene Station for Year 2009.

1284
Figure 10b. SONRIS Salinity Data.

1285
Figure 11. Seasonal Flows from Caernarvon Freshwater Diversion.

1286
Figure 12. Transect Locations.

1287
Figure 13. Sample of the Surveyed Cross-Sections.

1288
Figure 14. Sample of the Surveyed Cross-Sections.

1289
Figure 15. Salinity and Velocity Sampling Stations.

1290
Figure 16. Additional URS Field Locations.

1291
Figure 17. Measured Stage Data.

1292
Figure 18. Salinity Sampling Results.

1293
Figure 19. Model Domain.

1294
Figure 20. Water Polygon Data from the LA GIS Digital Map Compilation DVD.

1295
Figure 21. USGS Water Area Changes Study Results.

1296
Figure 22a. Final Polygon Set.

1297
Figure 22b. Final Polygon Set in White Ditch Study Area.

1298
Figure 23. Survey Data Distribution.

1299
Figure 24. Effective Depths and Locations from Cross-Section Transect Data.

1300
Figure 25. Template of Water Body Depths.

1301
Figure 26. Scatter Set Used for Grid Generation.

  	
  
 
  

 
  
 





3.02.41.81.30.70.2-0.3






1302

  
  	
 


  


Figure 27. Enlarged Portion of Point Grid Data.

1303
     
  !!" #

 "$   % 
  $! &	'	(('))* + #
 *$$'!	 , 
 #


 -
  .
  ($$"
  
  
  



  
 /

Figure 28. Final Grid and Grid Information.

1304
Figure 29. Depth Contours.

1305
Figure 30. Grid Cell Resolution in area of interest (top) and showing number of cells in canals and rivers (right).

1306
Figure 31. Grid with Boundary Cellstring Locations.

#

0 &
0 1

2
  3  ( 0&
 0 1

+ 2
4 
5
0 1

1307
Figure 32. Boundary Input Data.

1308
Figure 33. Sensitivity of the Tide Calibration to the Datum Shifts in the Bay Gardene Stage Data.

1309
Figure 34. Final Stage Calibration.

1310
Figure 35. Typical Response of Salinity During a Calibration Simulation (Point locations are shown on Figure 36).

1311
Figure 36. Final Salinity Calibration (all values in ppt).

1312
Figure 37. Location 2.

1313
Figure 38. Location 3.

1314
Figure 39. Location 2 5000 cfs Capacity Cross-Sections.

1315
Figure 40a. Location 3 5000 cfs Capacity Cross-Sections.

1316
Figure 40b. Location 3 5000 cfs Capacity Cross-Sections.

1317
Figure 40c. Location 3 5000 cfs Capacity Cross-Sections.

1318
Figure 41. 35,000 cfs Capacity Alternative 2 Depth Contours.

1319
Figure 42. 35,000 cfs Capacity Alternative 3 Depth Contours.

1320
Figure 43. Sequence of Salinity Distributions at Location 2 with 35,000 cfs Capacity Grid.

Simulation hour 6 Simulation hour 7Simulation hour 8 Simulation hour 12

Salinity

(ppt)

1321
Figure 44. Sequence of Salinity Distributions at Location 3 with 35,000 cfs Capacity Grid.

Simulation hour 6 Simulation hour 7Simulation hour 8 Simulation hour 12

Salinity

(ppt)

1322
Figure 45. Time-averaged Salinities for Final 7 days of the Simulation at Location 2.

1323
Figure 46. Time-averaged Water Depths for Final 7 days of the Simulation at Location 2.

1324
Figure 47a. Simulation 3 Salinity Time Series Results at Points throughout the White Ditch Area (Point

Locations shown on Figure 36).

1325
Figure 47b. Simulation 4 Salinity Time Series Results at Points throughout the White Ditch Area

(Point Locations shown on Figure 36).

1326
Figure 48. Time-averaged Salinity Distribution for Long-term Simulation 3.

1327
& 

!  ' (  ( !%

1328
The White Ditch hydrodynamic and salinity model developed by URS uses the USGS

Bay Gardene tide data for the offshore water elevation boundary condition. During the

model calibration it was not possible to obtain a tidal calibration to measured data in the

White Ditch area without shifting the reported elevation of the tide data. The shift used

was approximately 1 foot downward.

The Bay Gardene tide data is reported as NAVD 88 and the mean tide elevation for one

or more year period is approximately one foot. The typical spring tide range is about 2

feet. The local survey data in the White Ditch are indicates that the median land

elevation (based on numerous survey points on transects across the area) is about 1 foot.

Thus during the rising tide, it is expected that the land will be inundated and during a

falling tide the inundated areas would become dry. This was reproduced in the model

simulations, but it causes a severe attenuation of the tide range in the White Ditch area, so

much so that there was no possibility of matching the measured tide range in the area

with adjustments to the friction or mixing parameters.

Local knowledge of the area, based on discussion with airboat operators who spend a

significant amount of time in the area indicate that during normal tides the land areas do

not become submerged, even at high tides. The only exception is during the month of

September when high offshore water levels associate with predominant southeasterly

winds causes a setup in the White Ditch area. In order to reconcile some of these findings

an investigation of the tidal datum for the Bay Gardene gage was made. The findings of

this investigation are summarized as follows:

• The USGS indicates that the gage was reset with the last year and there is larger

than normal uncertainty in the accuracy of the gage datum (NAVD88)

• NOAA is not aware of or is not using the datum data that the USGS generated (no

MSL to NAVD 88 info). NOAA has no published website Benchmark Page and

they do not publish a NAVD to MSL conversion for the Bay Gardene gage.

• The NOAA VDATUM software quotes the uncertainty of datum conversions in

the east Louisiana and Mississippi area as 17.1 cm (65% chance that actual area is

below this level)

• Discussion with Garron Ross of USGS (referred to by Scott Beddingfield)

indicates that there is a good degree of uncertainty in the tidal benchmark at Bay

Gardene and that the USGS plans to re-survey it using a state-of-the-art GPS

system in the near future, possibly publishing it in Summer 2010. The current

gage was remounted about a year ago, and an expedient method of establishing

the gage datum was used. Mr. Ross also pointed out that the Bay Gardene data of

summer 2009 is still provisional, and noted that there was a sudden 0.5 foot shift

in the data back in January.

These findings indicate that there is sufficient uncertainty in the Bay Gardene gage datum

to allow for some adjustment of the stage levels in the modeling analysis.

1329

Appendix M

Hazardous, Toxic, and Radioactive

Waste Initial Assessment Documentation

A Summary of the HTRW Initial Assessment

Documentation is listed below. Additional technical

information and data is on file and available on request.

1331

Final Integrated M-1 September 2010

Feasibility Study / SEIS

LCA White Ditch

Mississippi River Delta, Louisiana

HTRW Initial Assessment (IA) Documentation

Prepared by ARDL, Inc.

Revised 24 February 2010

8.0 ASSESSMENT FINDINGS

8.1 Summary of Results

ARIDL, Inc., has performed HTRW Initial Assessment documentation for the restoration project to

implement a medium diversion at White Ditch in conformance with the scope and limitations of ASTM

Practice 1527-05. Exceptions to or deletions from this practice are documented in Section 9.0 of this

report. This assessment has revealed no evidence of Recognized Environmental Conditions in connection

with the property, except for the following:

1. Oil/gas pipeline running through target area

2. Oil/gas wells within target boundary and adjoining properties

3. Presence of sunken boats in canals within target boundary

4. Presence of Petroleum Refining Facility on property within 1 mile of target area

5. Presence of ASTs on adjacent property

6. Maritime transportation traffic in nearby Mississippi River

8.2 Risk Assessment

The environmental professionals who have conducted the site visit and reviewed the results of the data

collection effort have concluded that the following are “Recognized Environmental Conditions” which

may have the following range of qualitative impacts on the soil and water resources on the subject

properties. It is the responsibility of the user of this report, based on his or her risk tolerance, fiduciary

responsibility or the applicable law, to determine the extent of further inquiry.

Recognized Environmental Condition Potential Environmental Impact

Oil/gas pipeline within target area Low to Moderate

Oil/gas wells within target area and adjacent property Low to Moderate

Sunken boats in canals Low

Presence of refinery within 1 mile of target area Low to Moderate

ASTs on Adjacent property Low

Maritime transportation traffic on Mississippi River Low

1333
Appendix M: Hazardous, Toxic, and Radioactive

Waste Initial Assessment Documentation Volume VI – Medium Diversion at White Ditch

Final Integrated M-2 September 2010

Feasibility Study / SEIS

8.3 Recommendations

Based upon the data reviewed and observations made within the immediate target area, no further

environmental actions are warranted at this time. There was evidence of RECs within the target area as

stated in Section 8.1.

According to information collected for this EA, the presence of at least one known pipeline is located

within the project target area. A ConocoPhillips pipeline enters the target area from the west, trends to the

northeast, and then turns due north towards Lake Borne. Other unreported pipelines are located within the

target area, as evidenced by topographic map review and the presence of access canals. The reported

oil/gas pipeline poses a low risk of environmental impact on the subject property, as long as the pipeline

operates in a secure and environmentally compliant manner. Any reported incident would be required to

be fully remediated by the responsible oil and gas well operators/owners as mandated by state and Federal

regulations. No such incidents have been reported within or in close proximity to the project area.

The oil and gas wells pose a low risk of environmental impact on the subject property. Any reported

incident would be required to be fully remediated by the responsible oil and gas well operators/owners as

mandated by state and Federal regulations. No such incidents have been reported within or in close

proximity to the project area.

The sunken boats present in the canals within the target property may have potential environmental

impact due to the presence of unused or leaking diesel fuel on board. Any accidental release, leak, or

rupture would be considered an REC. However, in the event that this should occur, the incident would be

fully remediated by the responsible parties, Louisiana Department of Environmental Quality, or the U.S.

Coast Guard, according to state and Federal regulations.

The ConocoPhillips refinery located west of the Mississippi River and west of the target areas may have

potential environmental impact due to the presence of large capacity ASTs, treatment ponds and other

known environmental waste streams. During the course of this BA, no major violations, environmental

liens or pending litigation could be found concerning this facility. Although the ConocoPhillips refinery

has the potential to be a major REC, research conducted for the purpose of this BA found the refinery to

be operating in compliance with state and Federal guidelines. Any accidental release, leak, or rupture

would be considered an REC. However, in the event that this should occur, the incident would be fully

remediated by ConocoPhillips, other possible responsible parties, Louisiana Department of

Environmental Quality, or the U.S. Coast Guard according to state and Federal regulations. Because of

the potential for the ConocoPhillips refinery to be a future REC, this facility is considered to be a low to

moderate risk.

Aboveground tanks can pose an environmental hazard due to possible leakage, spills or ruptures. The

ASTs mentioned by individuals interviewed were also observed during the site visit at the pumping

station off of Belair Pump Road. No containment structures were observed around the tanks; thus any

leakage, spill or rupture could environmentally impact the surrounding area. Since the tanks appeared to

be in proper working order and no spills had been reported, the assignment of low level impact was

assigned to this REC.

1334
Appendix M: Hazardous, Toxic, and Radioactive

Waste Initial Assessment Documentation Volume VI – Medium Diversion at White Ditch

Final Integrated M-3 September 2010

Feasibility Study / SEIS

The maritime barge traffic on the Mississippi River poses a low risk of environmental impact to the

subject property. Any reported incident which may occur would be required to be fully remediated by the

responsible barge line or U.S. Coast Guard, as mandated by state and Federal regulations.

9.0 LIMITATIONS AND DATA GAPS

9.1 Purpose

The purpose of this report was to assess the physical characteristics of the subject site with respect to the

presence in the environment of hazardous waste or material, oil, or petroleum products according to

ASTME 1527-05 and 1528.

No specific attempt was made to check on the compliance of present or past owners or operators of the

site with Federal, state, or local laws and regulations, environmental or otherwise. Non-ASTM scope

issues (i.e., asbestos, lead-based paint, etc.) were not addressed.

The scope of this assessment did not include any additional environmental investigation, which were not

outlined herein, or any analysis for the presence or absence of hazardous or toxic materials in the soil,

groundwater, surface water, air, in, on, under or above the subject tract.

Specifically, ARDL, Inc., does not and cannot represent that the site contains no hazardous waste or

material, oil (including petroleum products), or other latent condition beyond that observed by ARDL,

Inc., during its site assessment.

The observations described in this report were made under the conditions stated therein. The conclusions

and data presented in the report were based solely upon the services of the time and budgetary constraints

imposed by the client. Furthermore, such conclusions are based solely on the site condition, and the rules

and regulations in effect, at the time of the study. The findings and conclusions stated herein must be

considered not as scientific certainties, but rather as professional opinions regarding the limited data

obtained during the course of the environmental site assessment. No other warranty, expressed or implied,

is made.

In preparing this report, ARDL, Inc., relied on certain information provided by Federal, state or local

officials and other parties referenced therein, and on information contained in the files of Federal, state or

local agencies at the time of the site assessment. Although there may have been some degree of overlap in

the information provided by these various sources, an attempt to independently verify the accuracy or

completeness of all information reviewed or received during the course of this site assessment was not

made.

Observations were made of the site and of structures on the site as indicated within the report. Where

access to portions of the site or to structures on the site was unavailable or limited, ARDL, Inc., renders

no opinion as to the presence of indirect evidence relating to hazardous waste or material, oil, or other

petroleum products in that section of the site or structure. In addition, ARDL, Inc., renders no opinion as

to the presence of hazardous waste or material, oil or other petroleum products or to the presence of

indirect evidence relating to hazardous material, oil, or petroleum products where direct observation of

the interior walls, roof, or ceiling of a structure on a site was obstructed by objects or coverings on or over

these surfaces.

1335
Appendix M: Hazardous, Toxic, and Radioactive

Waste Initial Assessment Documentation Volume VI – Medium Diversion at White Ditch

Final Integrated M-4 September 2010

Feasibility Study / SEIS

Unless otherwise specified in the report, ARDL, Inc., did not perform testing or analyses to determine the

presence or concentration of asbestos, radon, formaldehyde, lead-based paint, lead in drinking water,

electromagnetic fields (EMFs) or polychlorinated biphenyls (PCBs) at the site or in the environment at

the site.

The ASTM standard requires that the history of the subject property be traced from the present back to

when the property first contained structures or was used for residential, commercial, industrial or

governmental purposes. This requires the investigator to review sources that are publicly available, within

a reasonable time and cost, reasonably ascertainable and considered practically reviewable, as defined

under the ASTM standard. In addition, these criteria are applied keeping in mind sources that are likely to

provide information concerning possible recognized environmental conditions at the subject property.

ARDL, Inc., has reviewed all sources of information that are considered to meet these criteria. in cases

where history of the property is not traced to a prior or its first developed use, this condition is considered

to be a data gap, and not an exception to the required scope of work.

In addition, the ASTM standard does not require a search interval of less than 5 years. This search interval

is not guaranteed to identify all prior tenants or occupants of the subject property.

9.2 The Degree of Obviousness of the Presence or Likely Presence of Contamination

(a) Persons to whom this part is applicable per 40 CFR§312.1(b) and environmental professionals

conducting an inquiry of a property on behalf of such persons must take into account the information

collected under §312.23 through 312.30 (historical information, interviews, records search) in considering

the degree of obviousness of the presence of releases or threatened releases at the subject property. (b)

Persons to whom this part is applicable per §312.1(b) and environmental professionals conducting an

inquiry of a property on behalf of such persons must take into account the information collected under

§312.23 through 312.30 in considering the ability to detect contamination by appropriate investigation.

The inquiry of the environmental professional should include an opinion regarding additional appropriate

investigation, if any.

Environmental Recommendation for Further Action

Property Name and Address Pertinent Information

White Ditch Property has concerns as to the obvious

presence or likely presence of contamination

as a finding of this investigation.

This Phase I ESA did identify Recognized Environmental

Conditions (RECs) associated with the Property.

1336
Appendix M: Hazardous, Toxic, and Radioactive

Waste Initial Assessment Documentation Volume VI – Medium Diversion at White Ditch

Final Integrated M-5 September 2010

Feasibility Study / SEIS

9.3 Data Gaps

Data Gaps

Resource Pertinent Information

Neighboring owners Interviews Multiple attempts, no response within time

constraints.

Owner interview Multiple attempts, no response.

City directories Property not listed.

Public Health Specialist, Multiple attempts, no response

Plaquemines Parish, LA within time constraints.

U.S. Department of Transportation, Multiple attempts, no response within time

Pipelines Information constraints.

Various Plaquemines Parish Agencies Multiple attempts, no response

Information Request Form within time constraints.

Purchase price comparison, if property Not supplied by User to the Environmental

was found to be environmentally Professional.

impacted Property was not found to be environmentally

impacted to an extent that the fair market

value of the property would be adversely

affected.

1337

Appendix N

Qualitative Induced Shoaling Analysis

1339

Final Integrated N-1 September 2010

Feasibility Study / SEIS

Appendix N

Induced Shoaling Analysis

The continuing loss of coastal wetlands in Louisiana has led to a call for more

Mississippi River diversions of water, nutrients and sediment to at least offset the continuing

losses, if not to regain some of the lost wetlands. Natural and man-made diversions have been in

place for some time now, both upstream and downstream of the proposed site at RM 60 AHP.

Several more are in the study and design stage. The diversion of significant quantities of river

sediments and water typically leads to unintended consequences, in that the diverted water and

sediment concentrations are not in the same proportion as in the river. The typical response is

sedimentation and shoaling in the main river downstream of the diversion. In the receiving

diversion channel, sedimentation or erosion could take place, depending on a variety of factors.

Complex analytical or physical models are needed to gain insight into what the impacts of a

diversion might be. However, such modeling has not yet been done for the White Ditch project.

The proposed White Ditch Diversion will be located on the inside of a bend in the river at

about RM 60 AHP. This location currently exhibits shoaling and sand deposition tendencies. If

the design of the diversion encourages the entrance of significant sand concentrations,

downstream sand deposition could be minimal on a year-round basis in the Mississippi channel.

Diverting significant amounts of sand is important in that deposition downstream of a diversion

will consist primarily of sand particles, as silts and clays tend to stay in suspension until the

velocity approaches zero.

The current operating plan for the White Ditch Diversion is limited to a diversion pulse

of 35,000 cfs in March–April of each year, during the normal high flow period of the Mississippi

River, and a diversion of 1,000 cfs the rest of the year. This flowrate may not be experienced

over the full 60 day period. The proposed 35,000 cfs diversion will be the largest man-made

diverted flow for wetland building on the Lower Mississippi River, but the one to two month

duration will be a modifying factor. The diversion should approximate five percent or less of the

main channel flow for most years. Although some deposition in the downstream channel will

occur, the one to two month duration should result in minimal shoaling, especially in the

navigation channel. Although the peak monthly sediment concentration normally occurs in

March, the peak monthly water discharge occurs in April with high flows typically continuing

into May and later. When the diversion is reduced to 1,000 cfs, some of this deposition will be

re-suspended by the Mississippi flow and carried on downstream in the following months. On an

annual basis, the net gain in downstream deposition could be minimal. Specific sediment

transport studies for the White Ditch Diversion are required to better address the amount of

deposition expected.

A brief review of available technical information along with a general literature search on

diversions and sediment effects yielded little hard technical information on this subject. The

greatest amount of this type effort has been performed by the Corps of Engineers over the past

20 years. White Ditch has not been addressed, but other, similar diversions may be reviewed for

applicability to White Ditch. Past sediment transport studies on the impacts of diversions for the

entire Lower Mississippi reach were described in a report by the Corps of Engineersi

The study

found that a diversion up to 15,000 cfs had no measurable impact on downstream deposition, so

only the March–April diversion pulse would affect the Mississippi. The study utilized the

1341
Appendix N: Qualitative Induced

Shoaling Analysis Volume VI  Medium Diversion at White Ditch

Final Integrated N-2 September 2010

Feasibility Study / SEIS

HEC-6ii computer program to evaluate the impacts of various actual and proposed diversions

both upstream and downstream of New Orleans. The three potential future diversion sites and

discharges examined for sedimentation impacts included: Fort Jackson (15,000 cfs), Bohemia

(100,000 cfs) and Myrtle Grove (15,000 cfs). The latter is across the river from the location of

White Ditch Diversion. Although Bohemia was only to be operated during a 3–4 year frequency

flood or rarer, its operation resulted in the most deposition over a simulated 96 year period of

record (75,000 cubic yards dredged annually). The total annual maximum increase from the three

diversions was 105,000 cubic yards requiring dredging. The White Ditch Diversion dredging

requirements should be a small fraction of this total. The study also found that deposition in the

Pilottown anchorage caused by the diversions took many years to reach this location. The further

upstream the diversion, the more years required to impact the Pilottown anchorage and adjacent

areas. In addition, the study highlighted the importance of diverting a large amount of sand. If

the diverted flow contained more than 50% of the river’s normal sand concentration, channel

changes near Head of Passes were small. If the sand concentration diverted was less than 50% of

the normal river concentration, channel changes were significantly greater at Head of Passes.

An ongoing study of the impact of West Bay Diversion on downstream deposition in the

anchorage area is in the draft phase. West Bay is a year-round flow diversion of 20,000 cfs just

upstream of Head of Passesiii, although flows approaching 30,000 cfs through the diversion have

been recorded. Future increased diversions at West Bay could reach 50,000 cfs, although the

Breaux Task Force has voted to close the project (possibly by the end of 2010) due to excessive

shoaling downstreamiv. A Corps draft report has concluded that West Bay is responsible for 15–

55%v of the shoaling in the anchorage area near Head of Passes. As the White Ditch Diversion

would only operate at flows in this range for one to two months of the year, the project would

increase shoaling in the anchorage area by a fraction of West Bay totals, perhaps 2–10%. It

would also take many years for the impact to reach Pilottown, since the White Ditch diversion is

about 60 river miles upstream.

An additional consideration will be the sedimentation that may take place in interior

distribution channels after the flow is diverted. The March discharge will be directed into marsh

and open water areas and the portion of the diverted sediment load that is sand will settle quickly

when the flow velocity decreases. If it is desired for the sand load to be carried well away from

the diversion point, the diversion channel(s) must be carefully designed to maintain the velocity

necessary to keep the sand load in suspension. Similarly, silts and clays will begin depositing as

velocities approach zero, so the diversion channel design should minimize the creation of eddies

or areas of low velocity.

i Corps of Engineers, July 2000. Mississippi River Sediment, Nutrient and Freshwater Redistribution Study, pp 147-151.

ii Corps of Engineers Hydrologic Engineering Center computer program HEC-6. Scour and Deposition in Rivers and Reservoirs, 1993

iii Louisiana Coastal Wetlands Conservation and Restoration Task Force, West Bay Sediment Diversion (MR-04), Project Status iv New Orleans Times-Picayune, Jan 21, 2010 v New Orleans Times-Picayune, Dec 8, 2009

1342