U.S. GOVERNMENT PRINTING OFFICE

68–495 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 I OF VI 

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

Infrastructure and ordered to be printed 

2:52 Sep 29 2011 Jkt 068495 PO 00000 Frm 00003 Fmt 4012 Sfmt 4012 E:\HR\OC\HD043V1 XXX HD043V1

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Volume I of VI – Summary

LOUISIANA COASTAL AREA, LOUISIANA

ECOSYSTEM RESTORATION

Six Projects Authorized by Section 7006(e)(3) of

Water Resources Development Act of 2007

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

District (USACE), New Orleans (MVN). The non-Federal sponsor for the study is

the Louisiana Coastal Protection and Restoration Authority (CPRA). The

responsible cooperating Federal agencies vary by project and include the U.S. Fish

and Wildlife Service (USFWS), National Atmospheric and Oceanic Administration

(NOAA), the U.S. Environmental Protection Agency (USEPA), and the National

Resource Conservation Service (NRCS). This report is a summary of the combined

feasibility studies and supplemental environmental impact statements completed

for each of the six conditionally authorized projects and complying with

requirements of the U.S. Army Corps of Engineers and the Council of

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

paperwork.

October 2010

U.S Army Corps of Engineers

New Orleans District

Louisiana Coastal Protection

and Restoration Authority

(1)
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2
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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

This report contains six volumes.

You are at Volume I which is the Summary Document:

Volume I: Summary

The remaining volumes are project-specific documents for the following:

Volume II: Amite River Diversion Canal Modification

Volume III: Convey Atchafalaya River Water to Northern Terrebonne

Marshes and 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

3
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4
Table of Contents Volume I – Summary

WRDA 2007 Section 7006(e)(3) i October 2010

Table of Contents1

Volume I – Summary

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

1.0 Forward..................................................................................................................................1-1

1.1 Introduction and Purpose .............................................................................................. 1-1

1.2 Louisiana Coastal Area Program .................................................................................. 1-4

1.3 Study Authority ..............................................................................................................1-5

1.4 Water Resources Development Act of 2007 Requirements.......................................... 1-6

1.5 Organization of Report................................................................................................... 1-6

1.6 U.S. Army Corps of Engineers Campaign Plan............................................................ 1-7

2.0 Introduction and Study Information..............................................................................2-1

2.1 Purpose and Scope.......................................................................................................... 2-1

2.2 Deepwater Horizon Oil Spill.......................................................................................... 2-1

2.3 Planning Process ............................................................................................................ 2-1

2.3.1 Plan Formulation Rationale ...................................................................................... 2-2

2.3.1.1 Plan Formulation Criteria...................................................................................2-3

2.3.1.2 Environmental Operating Principles..................................................................2-3

2.4 National Objectives ........................................................................................................ 2-4

2.5 Study Areas..................................................................................................................... 2-5

2.5.1 Amite River Diversion Canal Modification .............................................................. 2-5

2.5.2 Convey Atchafalaya River Water to Northern Terrebonne Marshes and

Multipurpose Operation of Houma Navigation Lock.............................................. 2-6

2.5.3 Small Diversion at Convent/Blind River .................................................................. 2-7

2.5.4 Terrebonne Basin Barrier Shoreline Restoration.................................................... 2-7

2.5.5 Medium Diversion at White Ditch ............................................................................ 2-8

3.0 Amite River Diversion Canal Modification...................................................................3-1

3.1 Purpose and Scope* ........................................................................................................ 3-1

3.1.1 Study Area Background*........................................................................................... 3-1

3.1.1.1 Study Area Significance.......................................................................................3-4

3.1.2 History of Investigation ............................................................................................. 3-4

3.1.3 Prior Reports and Existing Projects.......................................................................... 3-5

3.2 Need for and Objectives of Action*................................................................................ 3-9

3.2.1 Public Concerns.......................................................................................................... 3-9

3.2.2 Problems, Needs, and Opportunities* ...................................................................... 3-9

3.2.3 Planning Objectives ................................................................................................. 3-10

3.2.4 Planning Constraints............................................................................................... 3-10

3.3 Existing and Future Without Project Condition * ..................................................... 3-11

3.3.1 Existing Condition ................................................................................................... 3-11

3.3.1.1 Location ..............................................................................................................3-11

3.3.1.2 Climate................................................................................................................3-12

3.3.1.3 Geomorphic and Physiographic Setting ...........................................................3-12

3.3.1.4 Soils.....................................................................................................................3-12

3.3.1.5 Water Bottoms....................................................................................................3-13

3.3.1.6 Hydraulics and Hydrology.................................................................................3-13

3.3.1.7 Sedimentation and Erosion ...............................................................................3-14

3.3.1.8 Vegetation Resources.........................................................................................3-15

3.3.1.9 Salinity................................................................................................................3-18

3.3.1.10 Threatened and Endangered Species ...............................................................3-18

1 An asterisk (*) in the table of contents notes information that is required for National Environmental Policy Act

(NEPA) compliance.

5
Table of Contents Volume I – Summary

WRDA 2007 Section 7006(e)(3) ii October 2010

3.3.1.11 Cultural and Historic Resources.......................................................................3-19

3.3.1.12 Recreation...........................................................................................................3-20

3.3.1.13 Socioeconomic Resources – Gas, Oil, Utilities and Pipelines..........................3-20

3.3.2 Future Without Project Condition .......................................................................... 3-20

3.3.2.1 Soils.....................................................................................................................3-22

3.3.2.2 Water Bottoms....................................................................................................3-22

3.3.2.3 Hydraulics and Hydrology.................................................................................3-22

3.3.2.4 Sedimentation and Erosion ...............................................................................3-26

3.3.2.5 Vegetation Resources.........................................................................................3-26

3.3.2.6 Salinity................................................................................................................3-27

3.3.2.7 Threatened and Endangered Species ...............................................................3-27

3.3.2.8 Cultural and Historic Resources.......................................................................3-28

3.3.2.9 Recreation...........................................................................................................3-28

3.3.2.10 Socioeconomic Resources- Gas, Oil and Pipelines............................................3-28

3.4 Alternatives *................................................................................................................ 3-28

3.4.1 Plan Formulation Rationale .................................................................................... 3-28

3.4.2 Management Measures............................................................................................ 3-29

3.4.2.1 Description of Management Measures .............................................................3-29

3.4.2.2 Screening of Management Measures................................................................3-30

3.4.3 Preliminary Alternative Plans ................................................................................ 3-32

3.4.4 Identification of the Final Array of Alternatives ................................................... 3-32

3.4.5 Environmental Consequences* ............................................................................... 3-34

3.4.6 Comparison of Alternative Plans ............................................................................ 3-35

3.4.7 National Ecosystem Restoration Plan .................................................................... 3-39

3.4.8 Plan Selection – Recommended Plan...................................................................... 3-39

3.4.8.1 Components ........................................................................................................3-42

3.4.8.2 Design, Environmental, and Construction Considerations.............................3-45

3.4.8.3 Real Estate Requirements.................................................................................3-46

3.4.8.4 Operation and Maintenance Considerations....................................................3-46

3.4.8.5 Monitoring Plan and Adaptive Management...................................................3-46

3.4.8.6 Effectiveness of Recommended Plan in Meeting Goals and Objectives .........3-50

3.4.8.7 Effectiveness of Recommended Plan on Meeting Environmental

Operating Principles ..........................................................................................3-51

3.4.8.8 Compensatory Mitigation Measures.................................................................3-51

3.4.9 Risk and Uncertainty............................................................................................... 3-51

3.4.10 Implementation Requirements ............................................................................... 3-54

3.4.10.1 Schedule..............................................................................................................3-54

3.4.10.2 Implementation Responsibilities ......................................................................3-54

3.4.10.3 Cost Sharing.......................................................................................................3-55

3.4.10.4 Environmental Commitments...........................................................................3-55

3.5 Public Involvement * .................................................................................................... 3-56

3.5.1 National Environmental Policy Act Scoping .......................................................... 3-56

3.5.2 Other Public Comments, Areas of Controversy, Unresolved Issues..................... 3-56

3.6 Coordination and Compliance *................................................................................... 3-57

3.6.1 U.S. Army Corps of Engineers Principles and Guidelines .................................... 3-56

3.6.2 Environmental Coordination and Compliance....................................................... 3-57

4.0 Convey Atchafalaya River water to Northern Terrbonne Marshes and

Multipurpose Operation of Houma Navigation Lock.................................................4-1

4.1 Purpose and Scope* ........................................................................................................ 4-1

4.1.1 Study Area Background*........................................................................................... 4-1

4.1.1.1 Study Area Significance.......................................................................................4-3

4.1.2 History of Investigation ............................................................................................. 4-3

4.1.3 Prior Reports and Existing Projects.......................................................................... 4-4

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Table of Contents Volume I – Summary

WRDA 2007 Section 7006(e)(3) iii October 2010

4.1.3.1 Federal ..................................................................................................................4-6

4.1.3.2 State ....................................................................................................................4-11

4.1.3.3 Local....................................................................................................................4-12

4.1.3.4 Existing and Likely Future Water Projects .....................................................4-12

4.2 Need for and Objectives of Action *............................................................................. 4-19

4.2.1 Public Concerns........................................................................................................ 4-19

4.2.2 Problems, Needs, and Opportunities* .................................................................... 4-19

4.2.3 Planning Objectives ................................................................................................. 4-24

4.2.4 Planning Constraints............................................................................................... 4-25

4.3 Existing and Future Without Project Condition* ...................................................... 4-27

4.3.1 Existing Condition ................................................................................................... 4-27

4.3.1.1 Location ..............................................................................................................4-27

4.3.1.2 Climate................................................................................................................4-27

4.3.1.3 Geomorphic and Physiographic Setting ...........................................................4-28

4.3.1.4 Soils and Water Bottoms ...................................................................................4-28

4.3.1.5 Hydrology............................................................................................................4-29

4.3.1.6 Sedimentation and Erosion ...............................................................................4-30

4.3.1.7 Vegetation Resources.........................................................................................4-30

4.3.1.8 Salinity................................................................................................................4-34

4.3.1.9 Essential Fish Habitat.......................................................................................4-34

4.3.1.10 Threatened and Endangered Species ...............................................................4-34

4.3.1.11 Cultural Resources.............................................................................................4-37

4.3.1.12 Recreation...........................................................................................................4-37

4.3.1.13 Socioeconomic Resources – Navigation.............................................................4-38

4.3.1.14 Socioeconomic Resources – Oil, Gas, and Utilities ..........................................4-38

4.3.1.15 Socioeconomic Resources – Commercial Fisheries ..........................................4-39

4.3.1.16 Socioeconomic Resources – Oyster Leases .......................................................4-39

4.3.2 Future Without Project Condition .......................................................................... 4-39

4.3.2.1 Soils and Water Bottoms ...................................................................................4-39

4.3.2.2 Hydrology............................................................................................................4-40

4.3.2.3 Sedimentation and Erosion ...............................................................................4-40

4.3.2.4 Vegetation Resources.........................................................................................4-41

4.3.2.5 Salinity................................................................................................................4-42

4.3.2.6 Essential Fish Habitat.......................................................................................4-43

4.3.2.7 Threatened and Endangered Species ...............................................................4-44

4.3.2.8 Cultural and Historic Resources.......................................................................4-44

4.3.2.9 Recreation...........................................................................................................4-44

4.3.2.10 Socioeconomics Resources – Navigation...........................................................4-45

4.3.2.11 Socioeconomics Resources – Oil, Gas, and Utilities.........................................4-46

4.3.2.12 Socioeconomics Resources – Commercial Fisheries.........................................4-47

4.3.2.13 Socioeconomics Resources – Oyster Leases......................................................4-47

4.4 Alternatives *................................................................................................................ 4-47

4.4.1 Plan Formulation Rationale .................................................................................... 4-47

4.4.2 Management Measures............................................................................................ 4-48

4.4.2.1 Screening of Management Measures................................................................4-49

4.4.3 Preliminary Alternative Plans ................................................................................ 4-50

4.4.4 Identification of the Final Array of Alternatives ................................................... 4-53

4.4.5 Environmental Consequences * .............................................................................. 4-56

4.4.6 Comparison of Alternative Plans ............................................................................ 4-59

4.4.7 National Ecosystem Restoration Plan .................................................................... 4-62

4.4.8 Environmentally Preferable Alternative................................................................ 4-62

4.4.9 Plan Selection – Recommended Plan...................................................................... 4-62

4.4.9.1 Components ........................................................................................................4-64

7
Table of Contents Volume I – Summary

WRDA 2007 Section 7006(e)(3) iv October 2010

4.4.9.2 Design, Environmental, and Construction Considerations.............................4-66

4.4.9.3 Real Estate Requirements.................................................................................4-66

4.4.9.4 Operations and Maintenance Considerations..................................................4-67

4.4.9.5 Monitoring Plan and Adaptive Management...................................................4-67

4.4.9.6 Effectiveness of Recommended Plan in Meeting Goals and Objectives .........4-70

4.4.9.7 Effectiveness of Recommended Plan in Meeting Environmental

Operating Principles ..........................................................................................4-70

4.4.9.8 Compensatory Mitigation Measures.................................................................4-71

4.4.10 Risk and Uncertainty............................................................................................... 4-71

4.4.11 Implementation Requirements / Adaptive Management ...................................... 4-77

4.4.11.1 Schedule..............................................................................................................4-77

4.4.11.2 Implementation Responsibilities ......................................................................4-78

4.4.11.3 Cost Sharing .......................................................................................................4-78

4.4.11.4 Environmental Commitments...........................................................................4-79

4.5 Public Involvement * .................................................................................................... 4-80

4.5.1 NEPA Scoping .......................................................................................................... 4-80

4.5.2 Other Public Comments, Areas of Controversy, Unresolved Issues.....................4-80

4.6 Coordination and Compliance *................................................................................... 4-82

4.6.1 USACE Principles and Guidelines.......................................................................... 4-82

4.6.2 Environmental Coordination and Compliance....................................................... 4-82

5.0 Small Diversion at Convent/Blind River .......................................................................5-1

5.1 Purpose and Scope* ........................................................................................................ 5-1

5.1.1 Study Area Background*........................................................................................... 5-1

5.1.1.1 Study Area Significance.......................................................................................5-3

5.1.2 History of Investigation ............................................................................................. 5-3

5.1.3 Prior Reports and Existing Projects.......................................................................... 5-3

5.2 Need for and Objectives of Action *............................................................................... 5-9

5.2.1 Public Concerns.......................................................................................................... 5-9

5.2.2 Problems, Needs, and Opportunities* ...................................................................... 5-9

5.2.3 Planning Objectives ................................................................................................. 5-10

5.2.4 Planning Constraints............................................................................................... 5-11

5.3 Existing and Future Without Project Condition * ..................................................... 5-11

5.3.1 Existing Condition ................................................................................................... 5-12

5.3.1.1 Location ..............................................................................................................5-12

5.3.1.2 Climate................................................................................................................5-12

5.3.1.3 Geomorphic and Physiographic Setting ...........................................................5-12

5.3.1.4 Soils.....................................................................................................................5-13

5.3.1.5 Hydraulics and Hydrology.................................................................................5-14

5.3.1.6 Sedimentation and Erosion ...............................................................................5-16

5.3.1.7 Vegetation Resources.........................................................................................5-17

5.3.1.8 Threatened and Endangered Species ...............................................................5-22

5.3.1.9 Cultural and Historic Resources.......................................................................5-24

5.3.1.10 Recreation...........................................................................................................5-25

5.3.1.11 Socioeconomics Resources – Oil, Gas, and Utilities.........................................5-25

5.3.2 Future Without Project Condition .......................................................................... 5-26

5.3.2.1 Soils.....................................................................................................................5-26

5.3.2.2 Hydraulics and Hydrology.................................................................................5-27

5.3.2.3 Sedimentation and Erosion ...............................................................................5-29

5.3.2.4 Vegetation Resources.........................................................................................5-30

5.3.2.5 Threatened and Endangered Species ...............................................................5-32

5.3.2.6 Cultural and Historic Resources.......................................................................5-32

5.3.2.7 Recreation...........................................................................................................5-32

5.3.2.8 Socioeconomics Resources – Oil, Gas, and Utilities.........................................5-34

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Table of Contents Volume I – Summary

WRDA 2007 Section 7006(e)(3) v October 2010

5.4 Alternatives*................................................................................................................. 5-34

5.4.1 Plan Formulation Rationale .................................................................................... 5-34

5.4.2 Management Measures............................................................................................ 5-35

5.4.3 Preliminary Alternative Plans ................................................................................ 5-38

5.4.4 Identification of the Final Array of Alternatives ................................................... 5-42

5.4.5 Environmental Consequences* ............................................................................... 5-43

5.4.6 Comparison of Alternative Plans ............................................................................ 5-45

5.4.7 National Ecosystem Restoration Plan .................................................................... 5-46

5.4.8 Plan Selection – Recommended Plan...................................................................... 5-47

5.4.8.1 Components ........................................................................................................5-50

5.4.8.2 Design, Environmental, and Construction Considerations.............................5-52

5.4.8.3 Real Estate Requirements.................................................................................5-53

5.4.8.4 Operation and Maintenance Considerations....................................................5-53

5.4.8.5 Monitoring Plan and Adaptive Management...................................................5-54

5.4.8.6 Effectiveness of Recommended Plan in Meeting Goals and Objectives .........5-58

5.4.8.7 Effectiveness of Recommended Plan in Meeting Environmental

Operating Principles ..........................................................................................5-58

5.4.8.8 Compensatory Mitigation Measures.................................................................5-58

5.4.9 Risk and Uncertainty............................................................................................... 5-58

5.4.10 Implementation Requirements ............................................................................... 5-65

5.4.10.1 Schedule..............................................................................................................5-65

5.4.10.2 Implementation Responsibilities ......................................................................5-66

5.4.10.3 Cost Sharing .......................................................................................................5-66

5.4.10.4 Environmental Commitments...........................................................................5-67

5.5 Public Involvement* ..................................................................................................... 5-70

5.5.1 NEPA Scoping .......................................................................................................... 5-70

5.5.2 Other Public Comments, Areas of Controversy, Unresolved Issues.....................5-70

5.6 Coordination and Compliance *................................................................................... 5-70

5.6.1 USACE Principles and Guidelines.......................................................................... 5-70

5.6.2 Environmental Coordination and Compliance....................................................... 5-70

6.0 Terrebonne Basin Barrier Shoreline Restoration ......................................................6-1

6.1 Purpose and Scope* ........................................................................................................ 6-1

6.1.1 Study Area Background*........................................................................................... 6-1

6.1.1.1 Study Area Significance.......................................................................................6-3

6.1.2 History of Investigation ............................................................................................. 6-3

6.1.3 Prior Reports and Existing Projects.......................................................................... 6-4

6.1.3.1 Federal ..................................................................................................................6-6

6.1.3.2 State ....................................................................................................................6-11

6.2 Need for and Objectives of Action *............................................................................. 6-11

6.2.1 Public Concerns........................................................................................................ 6-11

6.2.2 Problems, Needs, and Opportunities* .................................................................... 6-12

6.2.3 Planning Objectives ................................................................................................. 6-14

6.2.4 Planning Constraints............................................................................................... 6-15

6.3 Existing and Future Without Project Condition* ...................................................... 6-15

6.3.1 Existing Condition ................................................................................................... 6-15

6.3.1.1 Location ..............................................................................................................6-15

6.3.1.2 Climate................................................................................................................6-16

6.3.1.3 Geomorphic and Physiographic Setting ...........................................................6-16

6.3.1.4 Soils.....................................................................................................................6-17

6.3.1.5 Water Bottoms....................................................................................................6-17

6.3.1.6 Coastal Processes and Hydrology .....................................................................6-18

6.3.1.7 Sedimentation and Erosion ...............................................................................6-19

6.3.1.8 Vegetation Resources.........................................................................................6-21

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Table of Contents Volume I – Summary

WRDA 2007 Section 7006(e)(3) vi October 2010

6.3.1.9 Salinity................................................................................................................6-21

6.3.1.10 Essential Fish Habitat.......................................................................................6-22

6.3.1.11 Threatened and Endangered Species ...............................................................6-22

6.3.1.12 Cultural Resources.............................................................................................6-24

6.3.1.13 Recreation...........................................................................................................6-28

6.3.1.14 Socioeconomic Resources – Navigation.............................................................6-28

6.3.1.15 Socioeconomic Resources – Oil, Gas, and Utilities ..........................................6-29

6.3.1.16 Socioeconomic Resources – Commercial Fisheries ..........................................6-29

6.3.1.17 Socioeconomic Resources – Oyster Leases .......................................................6-30

6.3.2 Future Without Project Condition .......................................................................... 6-30

6.3.2.1 Land loss.............................................................................................................6-30

6.3.2.2 Soils.....................................................................................................................6-32

6.3.2.3 Water Bottoms....................................................................................................6-32

6.3.2.4 Coastal Processes and Hydrology .....................................................................6-32

6.3.2.5 Sedimentation and Erosion ...............................................................................6-33

6.3.2.6 Vegetation Resources.........................................................................................6-34

6.3.2.7 Salinity................................................................................................................6-34

6.3.2.8 Essential Fish Habitat.......................................................................................6-35

6.3.2.9 Threatened and Endangered Species ...............................................................6-35

6.3.2.10 Cultural Resources.............................................................................................6-35

6.3.2.11 Recreation...........................................................................................................6-36

6.3.2.12 Socioeconomic Resources – Navigation.............................................................6-36

6.3.2.13 Socioeconomic Resources – Oil, Gas, and Utilities ..........................................6-36

6.3.2.14 Socioeconomic Resources – Commercial Fisheries: .........................................6-37

6.3.2.15 Socioeconomic Resources – Oyster Leases .......................................................6-37

6.4 Alternatives *................................................................................................................ 6-37

6.4.1 Plan Formulation Rationale .................................................................................... 6-37

6.4.2 Management Measures............................................................................................ 6-38

6.4.2.1 Screening of Management Measures................................................................6-38

6.4.2.2 Screening/Evaluation of Borrow Areas.............................................................6-42

6.4.3 Preliminary Alternative Plans ................................................................................ 6-45

6.4.4 Identification of the Intermediate Array of Alternatives ...................................... 6-48

6.4.5 Environmental Consequences * .............................................................................. 6-49

6.4.6 Comparison of Alternative Plans ............................................................................ 6-53

6.4.7 National Ecosystem Restoration Plan .................................................................... 6-53

6.4.7.1 Renourishment...................................................................................................6-58

6.4.7.2 Components ........................................................................................................6-59

6.4.7.3 Design, Environmental, and Construction Considerations.............................6-65

6.4.7.4 Real Estate Requirements.................................................................................6-67

6.4.7.5 Operations and Maintenance Considerations..................................................6-68

6.4.7.6 Monitoring Plan and Adaptive Management...................................................6-69

6.4.7.7 Effectiveness in Meeting Goals and Objectives................................................6-71

6.4.7.8 Effectiveness in Meeting Environmental Operating Principles .....................6-72

6.4.8 Recommended Component of Construction............................................................ 6-72

6.4.8.1 Renourishment...................................................................................................6-74

6.4.8.2 Components ........................................................................................................6-74

6.4.8.3 Design, Environmental, and Construction Considerations.............................6-76

6.4.8.4 Real Estate Requirements.................................................................................6-76

6.4.8.5 Operations and Maintenance Considerations..................................................6-76

6.4.8.6 Monitoring Plan and Adaptive Management...................................................6-77

6.4.8.7 Effectiveness in Meeting Goals and Objectives................................................6-77

6.4.8.8 Effectiveness in Meeting Environmental Operating Principles .....................6-78

6.4.8.9 Compensatory Mitigation Measures.................................................................6-78

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WRDA 2007 Section 7006(e)(3) vii October 2010

6.4.9 Risk and Uncertainty............................................................................................... 6-78

6.4.10 Implementation Requirements ............................................................................... 6-80

6.4.10.1 Schedule..............................................................................................................6-80

6.4.10.2 Implementation Responsibilities ......................................................................6-82

6.4.10.3 Cost Sharing .......................................................................................................6-82

6.4.10.4 Environmental Commitments...........................................................................6-84

6.5 Public Involvement * .................................................................................................... 6-87

6.5.1 NEPA Scoping .......................................................................................................... 6-87

6.5.2 Other Public Comments, Areas of Controversy, Unresolved Issues.....................6-88

6.6 Coordination and Compliance *................................................................................... 6-88

6.6.1 USACE Principles and Guidelines.......................................................................... 6-88

6.6.2 Environmental Coordination and Compliance....................................................... 6-89

7.0 Medium Diversion at White Ditch ...................................................................................7-1

7.1 Purpose and Scope* ........................................................................................................ 7-1

7.1.1 Study Area Background*........................................................................................... 7-1

7.1.1.1 Study Area Significance.......................................................................................7-3

7.1.2 History of Investigation ............................................................................................. 7-4

7.1.3 Prior Reports and Existing Projects.......................................................................... 7-4

7.1.3.1 Federal ..................................................................................................................7-5

7.1.3.2 State/Parish..........................................................................................................7-6

7.1.3.3 Local......................................................................................................................7-7

7.2 Need for and Objectives of Action *............................................................................... 7-8

7.2.1 Public Concerns.......................................................................................................... 7-8

7.2.2 Problems, Needs, and Opportunities* ...................................................................... 7-9

7.2.3 Planning Objectives ................................................................................................. 7-11

7.2.4 Planning Constraints............................................................................................... 7-12

7.3 Existing and Future Without Project Condition * ..................................................... 7-13

7.3.1 Existing Conditions.................................................................................................. 7-13

7.3.1.1 Location ..............................................................................................................7-14

7.3.1.2 Climate................................................................................................................7-14

7.3.1.3 Geomorphic and Physiographic Setting ...........................................................7-14

7.3.1.4 Soils.....................................................................................................................7-15

7.3.1.5 Hydraulics and Hydrology.................................................................................7-15

7.3.1.6 Sedimentation and Erosion ...............................................................................7-16

7.3.1.7 Vegetation Resources.........................................................................................7-16

7.3.1.8 Salinity................................................................................................................7-17

7.3.1.9 Essential Fish Habitat.......................................................................................7-17

7.3.1.10 Threatened and Endangered Species ...............................................................7-19

7.3.1.11 Cultural Resources.............................................................................................7-20

7.3.1.12 Recreation...........................................................................................................7-20

7.3.1.13 Socioeconomic Resources – Navigation.............................................................7-20

7.3.1.14 Socioeconomic Resources – Oil, Gas, and Utilities ..........................................7-20

7.3.1.15 Socioeconomic Resources – Commercial Fisheries ..........................................7-20

7.3.1.16 Socioeconomic Resources – Oyster Leases .......................................................7-20

7.3.2 Future Without Project Condition .......................................................................... 7-20

7.3.2.1 Soils.....................................................................................................................7-21

7.3.2.2 Hydraulics and Hydrology.................................................................................7-21

7.3.2.3 Sedimentation and Erosion ...............................................................................7-23

7.3.2.4 Vegetation Resources.........................................................................................7-23

7.3.2.5 Salinity................................................................................................................7-25

7.3.2.6 Essential Fish Habitat.......................................................................................7-25

7.3.2.7 Threatened and Endangered Species ...............................................................7-26

7.3.2.8 Cultural Resources.............................................................................................7-26

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WRDA 2007 Section 7006(e)(3) viii October 2010

7.3.2.9 Recreation...........................................................................................................7-26

7.3.2.10 Socioeconomic Resources – Navigation.............................................................7-27

7.3.2.11 Socioeconomic Resources – Oil, Gas, and Utilities ..........................................7-27

7.3.2.12 Socioeconomic Resources – Commercial Fisheries ..........................................7-27

7.3.2.13 Socioeconomic Resources – Oyster Leases .......................................................7-28

7.4 Alternatives *................................................................................................................ 7-28

7.4.1 Plan Formulation Rationale .................................................................................... 7-28

7.4.2 Management Measures............................................................................................ 7-29

7.4.3 Preliminary Alternative Plans ................................................................................ 7-32

7.4.3.1 Location for Diversion........................................................................................7-33

7.4.4 Identification of the Final Array of Alternatives ................................................... 7-38

7.4.5 Environmental Consequences * .............................................................................. 7-38

7.4.6 Comparison of Alternative Plans ............................................................................ 7-42

7.4.7 National Ecosystem Restoration Plan .................................................................... 7-43

7.4.8 Plan Selection – Recommended Plan...................................................................... 7-43

7.4.8.1 Components ........................................................................................................7-47

7.4.8.2 Design, Environmental, and Construction Considerations.............................7-47

7.4.8.3 Real Estate Requirements.................................................................................7-48

7.4.8.4 Operation and Maintenance Considerations....................................................7-48

7.4.8.5 Monitoring Plan and Adaptive Management Plan ..........................................7-49

7.4.8.6 Effectiveness of Recommended Plan in Meeting Goals and Objectives .........7-51

7.4.8.7 Effectiveness of Recommended Plan in Meeting Environmental

Operating Principles ..........................................................................................7-52

7.4.8.8 Compensatory Mitigation Measures.................................................................7-52

7.4.9 Risk and Uncertainty............................................................................................... 7-53

7.4.10 Implementation Requirements ............................................................................... 7-58

7.4.10.1 Schedule..............................................................................................................7-58

7.4.10.2 Implementation Responsibilities ......................................................................7-59

7.4.10.3 Cost Sharing .......................................................................................................7-59

7.4.10.4 Environmental Commitments...........................................................................7-60

7.5 Public Involvement * .................................................................................................... 7-63

7.5.1 NEPA Scoping .......................................................................................................... 7-63

7.5.2 Other Public Comments, Areas of Controversy, Unresolved Issues.....................7-63

7.6 Coordination and Compliance *................................................................................... 7-64

7.6.1 USACE Principles and Guidelines.......................................................................... 7-64

7.6.2 Environmental Coordination and Compliance....................................................... 7-64

8.0 Conclusions and Recommendations ...............................................................................8-1

8.1 Amite River Diversion Canal Modification................................................................... 8-2

8.2 Convey Atchafalaya River Water to Northern Terrebonne Marshes and

Multipurpose Operation of the Houma Navigation Lock.................................... 8-3

8.3 Small Diversion at Convent/Blind River....................................................................... 8-4

8.4 Terrebonne Basin Barrier Shoreline Restoration ........................................................ 8-5

8.5 Medium Diversion at White Ditch................................................................................. 8-6

8.6 Financial Requirements................................................................................................. 8-6

8.7 Views of Non-Federal Sponsor....................................................................................... 8-7

8.8 Area of Controversy and Unresolved Issues................................................................. 8-7

8.9 Overall Recommendation............................................................................................... 8-9

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FIGURES

Figure ES-1: Historical and projected land loss in Louisiana (USGS, 2003) .................................... ES-2

Figure ES-2: LCA - Project Study Areas.............................................................................................. ES-4

Figure ES-3: Study Area with subunits - LCA ARDC Modification .................................................. ES-6

Figure ES-4: LCA ARDC Modification recommended plan (Alternative 33) .................................... ES-9

Figure ES-5: Study Area with subunits - LCA ARTM and MOHNL .............................................. ES-13

Figure ES-6: LCA ARTM recommended plan features (Alternative 2) ........................................... ES-17

Figure ES-7: Study Area with subunits - LCA Small Diversion at Convent / Blind River ............ ES-21

Figure ES-8: LCA Small Diversion at Convent / Blind River recommended plan features

(Alternative 2) .............................................................................................................. ES-24

Figure ES-9: Study Area - LCA TBBSR............................................................................................. ES-28

Figure ES-10: LCA TBBSR Whiskey Island Plan C ......................................................................... ES-32

Figure ES-11: LCA TBBSR Trinity Island Plan C .......................................................................... ES-33

Figure ES-12: LCA TBBSR Raccoon Island - Plan E with Terminal Groim .................................. ES-34

Figure ES-13: LCA TBBSR Timbalier Island Plan E ....................................................................... ES-35

Figure ES-14: Study Area - LCA MDWD........................................................................................... ES-38

Figure ES-15: LCA MDWD recommended plan features (Alternative 4)........................................ ES-42

Figure 1-1: Historical and projected land loss in Louisiana (USGS, 2003) .......................................... 1-3

Figure 2-1: LCA subprovinces (USACE, 2004a) ..................................................................................... 2-5

Figure 2-2: LCA - Study Areas ................................................................................................................ 2-9

Figure 3-1: LCA ARDC Study Area with subunits................................................................................. 3-2

Figure 3-2: Related LCA projects near the Study Area ......................................................................... 3-8

Figure 3-3: LCA ARDC Predicted Study Area habitat conversions .................................................... 3-21

Figure 3-4: Sea level rise for Study Area .............................................................................................. 3-23

Figure 3-5: Impacts of low sea level rise, subsidence, and accretion .................................................. 3-25

Figure 3-6: Impacts of Intermediate Sea Level Rise, Subsidence, and Accretion .............................. 3-25

Figure 3-7: Impacts of high sea level rise, subsidence, and accretion................................................. 3-25

Figure 3-8: LCA ARDC Recommended Plan (Alternative 33) ............................................................. 3-41

Figure 3-9: Comparison of HUs over the period of analysis ................................................................ 3-44

Figure 4-1: Study Area with subunits- LCA ARTM and MOHNL ........................................................ 4-2

Figure 4-2: Flows and constrictions in the Western subunit............................................................... 4-26

Figure 4-3: Flows and constrictions in the East subunit .................................................................... 4-26

Figure 4-4: Land gain/loss rates in the Study Area – percent per year based on 1985 to 2008

rates and 1985 acreage (based on Barras et al. 2008 and Barras 2009) .....................4-33

Figure 4-5: LCA ARTM - recommended plan (Alternative 2).............................................................. 4-63

Figure 5-1: Lake Pontchartrain Basin and Sub-Basins......................................................................... 5-2

Figure 5-2: Study Area - LCA Small Diversion at Convent/Blind River .............................................. 5-4

Figure 5-3: Related LCA projects near the Study Area .........................................................................5-8

Figure 5-4: Habitat condition map for Study Area............................................................................... 5-21

Figure 5-5: Projected RSLR over project life.........................................................................................5-29

Figure 5-6: LCA Small Diversion at Convent/Blind River Recommended Plan (Alternative 2) .......5-49

Figure 5-7: Accretion and sea level rise forecasts ................................................................................ 5-61

Figure 5-8: Accretion minus sea level rise for the recommended plan ............................................... 5-61

Figure 6-1: Study Area - LCA Terrebonne Basin Barrier Shoreline Restoration ................................ 6-2

Figure 6-2: Location of authorized CWPPRA projects in Planning Unit 3a......................................... 6-9

Figure 6-3: Location of proposed CIAP projects (LDNR, 2009c) ......................................................... 6-10

Figure 6-4: Final level screening: Borrow Area Locations................................................................... 6-44

Figure 6-5: Whiskey Island Plan C........................................................................................................ 6-61

Figure 6-6: Trinity Island Plan C .......................................................................................................... 6-62

Figure 6-7: Raccoon Island Plan E with Terminal Groim.................................................................... 6-63

Figure 6-8: Timbalier Island Plan E...................................................................................................... 6-64

Figure 7-1: Study Area - LCA MDWD..................................................................................................... 7-2

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WRDA 2007 Section 7006(e)(3) x October 2010

Figure 7-2: Sea level rise rates for the White Ditch Study Area......................................................... 7-22

Figure 7-3: Potential diversion structure locations.............................................................................. 7-37

Figure 7-4: LCA MDWD - recommended plan (Alternative 4) ............................................................ 7-46

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WRDA 2007 Section 7006(e)(3) xi October 2010

TABLES

Table ES-1: LCA ARDC Modification Comparison of NER and Recommended Plan..................... ES-10

Table ES-2: LCA ARDC Modification Cost Sharing.......................................................................... ES-11

Table ES-3: LCA ARTM/MOHNL NER and Recommended Plan.................................................... ES-18

Table ES-4: LCA ARTM Cost Sharing ............................................................................................... ES-19

Table ES-5: LCA Small Diversion at Convent/Blind River NER / Recommended Plan ................ ES-25

Table ES-6: LCA Small Diversion at Convent/Blind River Cost Sharing....................................... ES-26

Table ES-7: LCA TBBSR NER Plan and Recommended Component of Construction ................... ES-31

Table ES-8: LCA TBBSR Cost Sharing for NER Plan ..................................................................... ES-36

Table ES-9: LCA TBBSR Cost Sharing for Recommended Component of Construction................ ES-36

Table ES-10: LCA MDWD NER and Recommended Plan ................................................................ ES-43

Table ES-11: LCA MDWD Cost Sharing............................................................................................ ES-43

Table 3-1: Hydrologic Subunits ............................................................................................................... 3-3

Table 3-2: Relevance of Prior Studies, Reports, Programs, and Water Projects to the LCA

ARDC Modification Integrated FS/SEIS ......................................................................... 3-5

Table 3-3: Common Plant Species in Study Area................................................................................. 3-16

Table 3-4: Federally Threatened and Endangered Plant and Animal................................................ 3-18

Table 3-5: LNHP Rare, Threatened, and Endangered Species and Natural Communities in

Ascension and Livingston Parishes-January 2010 ....................................................... 3-19

Table 3-6: Identified Archaeological Sites Within the Study Area ..................................................... 3-20

Table 3-7: Summary of Five-Year Sea Level Rise for Each Case ........................................................ 3-24

Table 3-8: Years to Permanent Inundation .......................................................................................... 3-24

Table 3-9: Final Array of Alternatives .................................................................................................. 3-32

Table 3-10: Comparison of Final Array of Alternatives....................................................................... 3-34

Table 3-11: Summary of Costs Estimates for the Final Array ............................................................ 3-36

Table 3-12: Alternatives Costs and Benefits.........................................................................................3-37

Table 3-13: IWR Planning Suite Results ..............................................................................................3-38

Table 3-14: Ranking of Final Array....................................................................................................... 3-38

Table 3-15 Comparison of the NER and the Recommended Plan ....................................................... 3-40

Table 3-16: Maximum Cost Including Inflation through Construction .............................................. 3-42

Table 3-17: Effect of RSLR on Alternatives .......................................................................................... 3-44

Table 3-18: LCA ARDC Modification Project Implementation Schedule ........................................... 3-54

Table 3-19: Cost Share Amounts for the Recommended Plan ............................................................ 3-55

Table 4-1: Relevance of Prior Studies, Reports, Programs, and Water Projects to the ARTM

Feasibility Study ...............................................................................................................4-4

Table 4-2: Salinity Ranges for the Four Coastal Wetland Types ....................................................... 4-31

Table 4-3: Habitat Types in the Study Area from 1956 to 2008 (based on Barras et al., 2008

and Barras, 2009)............................................................................................................ 4-32

Table 4-4: Federally Listed Threatened and Endangered Species in the Study Area....................... 4-34

Table 4-5: LNHP Threatened and Endangered Species in the Study Area........................................ 4-36

Table 4-6: Management Measures and Associated Alternatives ........................................................ 4-51

Table 4-7: Alternatives Costs and Benefits........................................................................................... 4-60

Table 4-8: Summary of WVA Analysis AAHUs, IWR Planning Benefits for Alternatives in the

Final Array. ..................................................................................................................... 4-61

Table 4-9: Maximum Cost Including Inflation through Construction ................................................ 4-64

Table 4-10: Costs and Benefits for Combined LCA ARTM Project .................................................... 4-64

Table 4-11: Sea Level Rise Results for Alternative 2.......................................................................... 4-72

Table 4-12 : Estimates of Project Habitat Benefits without the HNC Lock Implementation ...........4-75

Table 4-13: Milestone Schedule ............................................................................................................. 4-77

Table 4-14: Cost Sharing Split............................................................................................................... 4-79

Table 5-1: Relevance of Prior Studies, Reports, Programs, and Water Projects to the LCA

Small Diversion at Convent/Blind River, Louisiana Feasibility Study......................... 5-5

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WRDA 2007 Section 7006(e)(3) xii October 2010

Table 5-2: Threatened and Endangered Species in Study Area.......................................................... 5-23

Table 5-3: LNHP Rare, Threatened, and Endangered Species and Natural Communities in

Ascension and St. James Parishes (April 2008)............................................................ 5-24

Table 5-4: Summary of Pipeline Information in Study Area............................................................... 5-26

Table 5-5: Projected Relative Sea Level Rise........................................................................................ 5-28

Table 5-6: Diversion Locations Not Carried Forward .......................................................................... 5-39

Table 5-7: Contribution of 1,500 cfs Diversion Alternatives to the Objectives................................... 5-41

Table 5-8: Cost of Final Array Alternatives......................................................................................... 5-45

Table 5-9: Summary of WVA Analysis AAHUs, IWR Planning Benefits, and Wetland

Impacts for Final Array Alternatives ............................................................................ 5-46

Table 5-10: Recommended Plan Cost ................................................................................................... 5-47

Table 5-11: Maximum Cost Including Inflation through Construction .............................................. 5-48

Table 5-12: Milestone Schedule ............................................................................................................. 5-65

Table 5-13: Cost Sharing........................................................................................................................ 5-66

Table 6-1: Relevance of Prior Studies, Reports, Programs, and Water Projects to the LCA

TBBSR Feasibility Study.................................................................................................. 6-4

Table 6-2: CWPPRA Projects in Study Area.......................................................................................... 6-7

Table 6-3: Summary of Acreage and Erosion Rates ............................................................................. 6-16

Table 6-4: Threatened and Endangered Species in Study Area.......................................................... 6-23

Table 6-5: Summary of Potential Island Strategiesa

Table 6-6: Final Level Borrow Area Screening..................................................................................... 6-43

........................................................................... 6-41

Table 6-7: Intermediate Array of Alternatives ..................................................................................... 6-48

Table 6-8: CE/ICA for Intermediate Array of Alternatives................................................................. 6-54

Table 6-9: Summary of WVA Analysis AAHUs, IWR Planning Benefits, and Cost for

Intermediate Array of Alternatives ............................................................................... 6-55

Table 6-10: Fully Funded NER Plan Cost Summary .......................................................................... 6-57

Table 6-11: Renourishment Sequencing and Quantities .................................................................... 6-58

Table 6-12 Fully Funded Recommended Component of Construction Cost Summary......................6-73

Table 6-13: Maximum Cost including Inflation through Construction............................................... 6-73

Table 6-14: Acerages for Whiskey Island Renourishment.................................................................. 6-74

Table 6-15: LCA TBBSR Project Cost Sharing for NER Plan ............................................................ 6-83

Table 6-16: LCA TBBSR Project Cost Sharing for Recommended Component of Construction......6-84

Table 7-1: Relevance of Prior Studies, Reports, Programs, and Water Projects to the LCA

MDWD Feasibility Study.................................................................................................. 7-4

Table 7-2: Additional Water Related Projects ....................................................................................... 7-7

Table 7-3: EFH for Various Life Stages for Shrimp, Red Drum, Reef Fish, and Stone Crab

(NMFS Scoping Correspondence, 2009)......................................................................... 7-18

Table 7-4: Federally Listed Threatened and Endangered Species in the Study Area.......................7-19

Table 7-5: Conceptual Alternatives Screened from Further Consideration ....................................... 7-33

Table 7-6: Benefits Summary (in AAHUs)a

Table 7-7: Acerage Summary

.......................................................................................... 7-41 a

Table 7-8: Incremental Cost/ Cost Effectiveness Step .........................................................................7-42

................................................................................................................ 7-41

Table 7-9: Summary of WVA Analysis AAHUs and IWR Planning Benefits for Final

Alternative Array ............................................................................................................ 7-42

Table 7-10: Direct Footprint Acreage Impacts...................................................................................... 7-43

Table 7-11: Maximum Cost Including Inflation Throuh Construction .............................................. 7-47

Table 7-12: OMRR&R Annualization for Recommended Plan ............................................................ 7-49

Table 7-13 : LCA MDWD Implementation Schedule .......................................................................... 7-58

Table 7-14: Cost Sharing........................................................................................................................ 7-60

Table 8-1: Summary of Project Benefits, Costs, and Authorizations .................................................... 8-2

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APPENDICES

Appendix A – References

Appendix B – Glossary

Appendix C – Acronyms

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WRDA 2007 Section 7006(e)(3) xiv October 2010

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WRDA 2007 Section 7006(e)(3) ES-1 October 2010

EXECUTIVE SUMMARY

Louisiana’s loss of wetlands, cheniers, and barrier islands to open water is now a

well-documented fact in numerous studies and anecdotal observations. Since the

1930,s Louisiana has lost 1,900 square miles of land (Barras et al., 1994; Barras et

al., 2003; Dunbar et al., 1992). From 1990 to 2000, approximately 24 square miles

of coastal land were lost each year.

The 2004 Louisiana Coastal Area, Ecosystem Restoration Study (LCA Report)

projected that 513 square miles of land would disappear by 2050, including a gain of

161 square miles from Coastal Wetlands Planning, Protection, and Restoration Act

projects (Barras et al., 2003). Tropical storms and hurricanes can accelerate the

land loss rate. During the 2005 hurricane season, 203 square miles of land were

lost (Barras, 2009), representing 40% of the forecasted 2000 to 2050 loss n the LCA

Report. Figure ES-1 shows historical and projected Louisiana land loss.

The 2004 LCA Report summarizes land loss causes and ecosystem degradation in

coastal Louisiana. Ten major natural and human-induced factors that contribute to

coastal land loss are identified in that report.

1. Barrier island degradation

2. Tropical storm events

3. Eustatic sea level change

4. Relative sea level change

5. Flood control

6. Navigation

7. Oil and gas infrastructure

8. Hypoxia

9. Saltwater intrusion

10.Sediment reduction / vertical accretion deficit (USACE, 2004a)

Natural processes must be taken into consideration in project planning. Humaninduced factors present opportunities where change could help reverse coastal

degradation trends. The six projects included in this study examine the feasibility

of reintroducing riverine influence, removing hydrologic impediments, and restoring

form to a group of barrier islands.

In 2004, the United States (U.S.) Army Corp of Engineers (USACE) completed the

LCA Report, culminating other studies that had examined long-term solutions for

preserving and restoring Louisiana coastal ecosystems. While large-scale systemic

restoration measures are needed to sustain coastal ecosystems, the 2004 LCA

Report was developed to identify cost-effective, near-term restoration features

addressing the most critical needs of coastal Louisiana.

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WRDA 2007 Section 7006(e)(3) ES-2 October 2010

Figure ES-1: Historical and projected land loss in Louisiana (USGS, 2003)

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Executive Summary Volume I – Summary

WRDA 2007 Section 7006(e)(3) ES-3 October 2010

The 2004 LCA Report identifies critical projects, multiple programmatic

authorizations, and 10 additional required feasibility studies for the Louisiana

Coastal Area (LCA). When the Water Resources Development Act (WRDA) of 2007

was passed, it included authorization under Title VII for the LCA Program and

specific authorization for additional feasibility-level reports. Six of the elements

included in Section 7006 (e)(3)(A) as projects identified for additional study were:

Convey Atchafalaya River Water to Northern Terrebonne Marshes

Multipurpose Operation of the Houma Navigation Lock

Amite River Diversion Canal Modification

Small Diversion at Convent/Blind River

Terrebonne Basin Barrier Shoreline Restoration

Medium Diversion at White Ditch

Each of these six elements are each required to have a feasibility study completed.

In the course of initiating these studies, two elements were determined to be

hydrologically intertwined and the planning efforts were combined:

Convey Atchafalaya River Water to Northern Terrebonne Marshes

Multipurpose Operation of the Houma Navigation Lock

As a result, this feasibility report was structured into six primary volumes including

this Summary Report. This summary report (Volume I) integrates the following

elements:

Amite River Diversion Canal Modification (Volume II)

Convey Atchafalaya River Water to Northern Terrebonne Marshes and

Multipurpose Operation of the Houma Navigation Lock (Volume III)

Small Diversion at Convent/Blind River (Volume IV)

Terrebonne Basin Barrier Shoreline Restoration (Volume V)

Medium Diversion at White Ditch (Volume VI)

This report summarizes the integrated feasibility study (FS) and supplemental

environmental impact statement (SEIS) conducted for each of the six critical, nearterm restoration features. Each SEIS is a supplement to the Final Programmatic

Environmental Impact Statement (FPEIS) completed for the LCA Report (USACE,

2004b). Figure ES-2 shows each Study Area.

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Executive Summary Volume I – Summary

WRDA 2007 Section 7006(e)(3) ES-4 October 2010Figure ES-2: LCA - Project Study Areas

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WRDA 2007 Section 7006(e)(3) ES-5 October 2010

AMITE RIVER DIVERSION CANAL MODIFICATION

The LCA Amite River Diversion Canal (ARDC) Modification Study Area is located

approximately 30 miles southeast of the city of Baton Rouge and west of Lake

Maurepas. The project referred to here as the LCA ARDC Modification Study was

referred to as the "Increase Amite River Diversion Canal influence by gapping

banks" project in the 2004 LCA Report (USACE, 2004a). Prior studies and reports

document degradation in Maurepas Swamp adjacent to the ARDC and demonstrate

a need for ecosystem restoration that simulates historical hydrologic conditions.

Figure ES-3 shows the LCA ARDC Modification Study Area.

The Maurepas Swamp complex is the second largest continuous coastal forest in

Louisiana, comprising over 190,000 acres of freshwater swamp habitat. The LCA

ARDC Modification Study Area is an essential ecosystem since it includes wetland

habitats and provides high fish and wildlife value as well as habitat for migratory

birds and other aquatic organisms, including threatened or endangered species.

Need for and Objectives of Action: The natural hydrology within the Study

Area was modified by the construction of the ARDC and a railroad grade. Sea level

rise and subsidence have compounded the effects of these modifications. This has

led to deterioration of the swamp ecosystem from impoundment of water; lack of

freshwater, sediment, and nutrients; and surge-related saltwater intrusion.

Deterioration of the swamp will eventually lead to conversion of the swamp to

freshwater marsh and then to open water.

Investigation led to the establishment of the following planning objectives within

the Study Area over the 50-year period of analysis:

Increase hydrologic connectivity between the degraded swamp and

bottomland hardwood habitats within the Study Area and the ARDC by

increasing the exchange of freshwater, sediments, and nutrients over the 50-

year period of analysis.

Reduce habitat conversion of swamp to open water within the Study Area

over the 50-year period of analysis.

Facilitate natural hydrologic cycle within the Study Area over the 50-year

period of analysis by reducing impoundment in degraded swamp and

bottomland hardwood habitats adjacent to the ARDC to improve tree

productivity and seedling germination.

Improve fish and wildlife habitat within the Study Area over the 50-year

period of analysis.

The LCA ARDC Modification Study is designed to be within the scope of the 2004

LCA Report. The goal of the 2004 LCA Report is to reverse the current trend of

degradation of the coastal ecosystem using restoration strategies that reintroduce

historical flows of river water, nutrients, and sediment to coastal wetlands; restore

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Executive Summary Volume I – Summary

WRDA 2007 Section 7006(e)(3) ES-6 October 2010

Figure ES-3: Study Area with subunits - LCA ARDC Modification

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Executive Summary Volume I – Summary

WRDA 2007 Section 7006(e)(3) ES-7 October 2010

coastal hydrology to minimize saltwater intrusion; and maintain the structural

integrity of the coastal ecosystem (USACE, 2004a).

Existing Condition: Historically, hydrology within the LCA ARDC Modification

Study Area was dominated by overbank flows from the Mississippi and Amite

rivers. The construction of flood control projects, including the Mississippi River

and Tributaries (MR&T) (1928) and the Amite River and Tributaries (AR&T) (1956)

projects, disrupted the natural hydrology of the area. Construction of the ARDC,

which was included in the AR&T, resulted in deposition of dredged-material along

the banks of the new canal. The dredged-material berm has isolated the bald

cypress-tupelo swamp habitat within the LCA ARDC Modification Study Area and

effectively ended overbank flooding from the Mississippi and Amite rivers while

preventing the swamp from draining during low flow periods.

There are 1,600 acres of freshwater swamp habitat that converted to marsh and

open water in the Amite and Blind River mapping units between 1932 and 1990

(LCWCRTF and WCRA, 1999). Soil loss is continuing in the Study Area due to

natural and man-made causes. As a result, swamp and wetland forests have

deteriorated and become increasingly stressed. Due to degradation and decreased

vegetation productivity, soil accretion is insufficient to offset regional subsidence,

and the degraded swamp habitat is susceptible to conversion to freshwater marsh

or open water. While measured salinities are currently low, elevated salinities

caused by impoundment of storm-driven higher-salinity waters likely contribute to

the degradation of the forested swamp and to its eventual conversion to marsh and,

ultimately, open water (Shaffer et al., 2009).

Approximately 25,634 acres (91.6%) of the LCA ARDC Modification Study Area is

composed of wetland communities, including forested and nonforested wetlands.

Bald cypress-tupelo swamp habitat makes up most of the forested wetlands.

Future Without Project Condition: Without Federal action, the swamp habitat

surrounding the ARDC would continue converting from a forested freshwater

swamp to a freshwater marsh and open water. The direct impacts would be the

continued impoundment of swamp water within the Study Area, decreased

hydrologic connectivity, and a transition toward marsh and salinity-tolerant

vegetation. The demographics and economic conditions would remain stable within

the Study Area. Salinity levels would increase due to saltwater inundation, which

is expected to increase with relative sea level rise (RSLR) and due to storm surges

from tropical cyclone events.

Shoreline erosion and land loss would result in a projected conversion of 18,204

acres of forested freshwater swamp to freshwater marsh and, subsequently, open

water in the next 50 years. Water flows into and out of the swamp would continue

to be impeded, water levels would increase due to coastal wetland loss, and runoff

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WRDA 2007 Section 7006(e)(3) ES-8 October 2010

would continue to increase due to urbanization of the Pontchartrain Basin. A

future without project scenario would include declines in wildlife, fishery, and

vegetative resources. There would be increased exposure of existing oil, gas, and

utility pipelines to coastal land loss, which would increase operations and repair

costs as well as increase the required investment in facilities and pipelines.

Alternatives: During the first step of the planning process, a list of measures was

developed based on the strategies of freshwater reintroduction, channel restoration,

and habitat restoration. Many methods to achieve those strategies were explored

and the final list included a mix of 105 separate structural and nonstructural

measures. Of the original list of 105 measures, 91 were screened out.

Fourteen measures were retained for further study. The 14 measures were

combined and developed into an initial array of 45 alternatives in addition to the No

Action Alternative. These 45 alternatives were screened based on their ability to

address project objectives, information from field reconnaissance, effectiveness of

the alternative, and any potential adverse impacts.

The final array of alternatives included seven alternatives and the No Action

Alternative. Excluding the No Action Alternative, each of the final alternatives

includes openings in the north and/or south banks of the ARDC, bifurcated

conveyance channels, sidecasting of dredged material in alternating berms along

the proposed conveyance channels, cuts in an existing railroad grade, and

vegetative plantings for the dredged material berm and swamp floor.

National Ecosystem Restoration Plan: Based on the results of the Wetland

Value Assessment (WVA) modeling, the IWR Planning Suite analysis, and the

impacts of alternative plans listed in this study, Alternative 39 was chosen to be the

National Ecosystem Restoration (NER) plan. This plan includes all the areas in the

final array, including the areas with the critical need of restoration (have already

begun converting to marsh) and an additional area that is expected to need

restoration in the next 20 years. This proposed action, which was deemed a Best

Buy, would provide 1,602 Average Annual Habitat Units (AAHUs) for the impact

areas with an estimated fully funded cost of construction of $15,200,000. However,

Alternative 39 exceeds the authorized funding limit and, thus, was not the

recommended plan.

Recommended Plan: After evaluation of the final array, Alternative 33 was

chosen as the recommended plan and is shown in Figure ES-4. Table ES-1

summarizes the project costs and benefits.

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WRDA 2007 Section 7006(e)(3) ES-9 October 2010Figure ES-4: LCA ARDC Modification recommended plan (Alternative 33)

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WRDA 2007 Section 7006(e)(3) ES-10 October 2010

Recommended plan components:

Three dredged material bank openings and three bifurcated conveyance

channels would be constructed in the north bank of the ARDC in NE-2 with

the westernmost channel in the north bank of the ARDC also extending

through the railroad grade into NE-1 to add connectivity between NE-1, NE2, and the ARDC.

Dredged material (5.0 acres) from the bank openings and the conveyance

channel would be sidecast in alternating berms so sheet flow is not reduced.

One cut would be created in the railroad grade approximately 0.9 miles north

of the ARDC to improve sheet flow.

Plant bottomland hardwood / freshwater swamp tree species on 5.0 acres of

dredged material berms.

Plant freshwater swamp tree species within 438 acres of the swamp floor.

Install nutria guards on all newly planted trees to protect against tree loss.

Alternative 33 (Recommended Plan) would meet the established project objectives

by restoring and benefitting 1,602 acres of freshwater swamp habitat, creating a net

of 679 AAHUs, creating 5.0 acres of bottomland hardwood habitat, establishing

hydrologic connectivity between the ARDC and the western Maurepas Swamp,

reducing the likelihood of the swamp being converted to marsh or open water by

promoting the germination and survival of the seedlings of bald cypress and other

trees, and improving biological productivity and reducing further habitat

deterioration.

Alternative 33 addresses the most degraded portion of the Study Area (NE-2).

Alternative 33 is an implementable increment of the NER plan, is within the cost

and scope of the WRDA 2007 authorization, has stand-alone utility, and can be

justified based on sustainable ecosystem restoration benefits. The estimated fully

funded project cost is $8,540,000.

Table ES-1: LCA ARDC Modification Comparison of NER and

Recommended Plan

Alt. 33a

(Recommended

Plan)

Alt. 39

(NER)

AAHUs 679 1,602

Cost effective (Yes/No/Best Buy) Yes Best Buy

$Annualized cost/AAHU b $660 $480

Fully funded project costc $8,540,000 $15,200,000

Authorized cost in WRDA Title VII, Section 7006

(e)(3)(A) for the LCA ARDC Modification Study $5,600,000

Maximum cost limited by Section 902 $10,760,000

a Alt. = Alternative

b Based on preliminary construction cost, not the fully funded cost. c Fully funded project cost includes inflation adjusted from the October 2006 price levels through the projected

midpoint of project construction.

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WRDA 2007 Section 7006(e)(3) ES-11 October 2010

Cost Sharing: Following the feasibility phase, the cost share for the planning,

design, and construction of the project as well as adaptive monitoring would be 65%

Federal and 35% non-Federal. The State of Louisiana, represented by the Coastal

Protection and Restoration Authority (CPRA), would be responsible for 100% of

land, easements, rights-of-way, relocation, and disposal areas (LERRDs) cost and,

following construction, the future operating, maintaining, repairing, replacing, and

rehabilitating (OMRR&R) costs. Table ES-2 shows the cost sharing amounts based

on the first cost of construction.

Table ES-2: LCA ARDC Modification Cost Sharing

Project Feature Total Cost Non-Federal Federal

% Cost % Cost

Total first cost of

constructiona $8,136,000 35 $2,848,000 65 $5,288,000

LERRD credit $180,000 100 $180,000 0 $0

Monitoring & adaptive

management $2,970,000 35 $1,040,000 65 $1,930,000

OMRR&R b $10,000 100 $10,000 0 $0

a Total first cost of construction is based on the sum of the planning, engineering, and design; construction management

(i.e. supervisions and administration); LERRDs; and monitoring and adaptive management and is based on October 2010

price levels.

b Average annual cost based on October 2010 price levels

*Costs in this table represent first costs not the fully funded cost through the mid-point of construction ($8,540,000)

Public Involvement: A notice of intent (NOI) to prepare a draft Supplemental

Environmental Impact Statement (SEIS) for the LCA ARDC Modification was

published in the Federal Register in December 2008. A public scoping meeting was

held in February 2009. Various other meetings have occurred with local landowners, the Lake Pontchartrain Basin Foundation, the Coalition to Restore Coastal

Louisiana, the Louisiana Conservation Fund, and Ascension and Livingston

Parishes. The Draft FS/SEIS was released to the public in May 2010, followed by a

45-day public review period, which included a public meeting. Public comments

were received during the scoping meeting and Draft FS/SEIS public review and

have been incorporated into the report.

Coordination and Compliance: Following completion of the Final FS/SEIS, the

Assistant Secretary of the Army for Civil Works would issue a Record of Decision

(ROD) concerning the proposed action. Full compliance with statutory authorities

would be accomplished upon review of the Final FS/SEIS by appropriate agencies

and the public and the signing of the ROD, in compliance with the National

Environmental Policy Act (NEPA). The USACE has coordinated with the U.S. Fish

and Wildlife Service (USFWS), the National Marine Fisheries Service (NMFS), and

the Louisiana Department of Wildlife and Fisheries (LDWF) as per the Fish and

Wildlife Coordination Act. A coordination act letter report has been received and

the comments incorporated into the project plan. State certifications for coastal

zone consistency and 401 water quality have also been received.

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WRDA 2007 Section 7006(e)(3) ES-12 October 2010

Area of Controversy and Unresolved Issues: Meetings and discussions with

the public; local, state and federal agencies; and the Project Development Team

(PDT) indicate support for the project and did not identify any areas of controversy

or unresolved issues.

Conclusions and Recommendations: The LCA ARDC Modification Project,

Alternative 33, recommended in this report is in the overall public interest and

would work to restore the natural hydrology and ecology within Maurepas Swamp.

The fully funded project cost is estimated at $8,540,000, and this project would be

cost shared by the non-Federal sponsor, the State of Louisiana, at 35% non-Federal

and 65% Federal. Additionally, the non-Federal sponsor would be 100% responsible

for the OMRR&R.

CONVEY ATCHAFALAYA RIVER WATER TO NORTHERN TERREBONNE

MARSHES AND MULTIPURPOSE OPERATION OF THE HOUMA

NAVIGATION LOCK

The LCA Convey Atchafalaya River Water to Northern Terrebonne Marshes

(ARTM) and Multipurpose Operation of the Houma Navigation Lock (MOHNL)

Study Area is located east of Morgan City, south of Houma, and south of LaRose.

These two projects were hydrologically intertwined and, consequently, were

combined for analysis; the combined project is referred to as the LCA ARTM

Project. The wetland communities within the northwestern portion of Terrebonne

Basin, including those located north and south of the Gulf Intracoastal Water Way

(GIWW), have been, in part, separated from the influence of the Atchafalaya River.

Instead, the hydrology of these areas is influenced by a widely variable pattern of

Atchafalaya River backwater effect, rainfall runoff events, and marine processes.

Major navigation channels in the subprovince are the Atchafalaya River, Wax Lake

Outlet, Houma Navigation Canal, GIWW, and Lower Atchafalaya River (south of

Morgan City). Figure ES-5 shows the LCA ARTM Study Area.

Necessity for and Objectives of Action: The natural processes of subsidence,

habitat switching, and erosion, combined with human activities, have caused

significant adverse impacts to the Northern Terrebonne Marshes, including

accelerated wetland loss and ecosystem degradation. In habitat switching, one

habitat will convert to another habitat through succession. In Louisiana, this

process is frequently due to changes in salinity levels or inundation. Examples of

habitat switching may be a forested system converting to a freshwater marsh or a

freshwater marsh converting to a saline marsh. The changes in habitat structure

and/ or composition result in a loss of one group of ecosystem services and may

result in local rarity of a habitat type.

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WRDA 2007 Section 7006(e)(3) ES-13 October 2010 Figure ES-5: Study Area with subunits - LCA ARTM and MOHNL

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WRDA 2007 Section 7006(e)(3) ES-14 October 2010

Wetlands in the Study Area are deteriorating for several reasons: 1) subsidence and

sea level rise, 2) lack of sediment and nutrient deposition, 3) erosion via tidal

exchange, 4) channelization, and 5) saltwater intrusion. These activities have

resulted in the loss of several thousand acres of solid, vegetated marsh.

Deterioration will continue unless preventative measures are taken.

The objective of the project is to provide additional freshwater, nutrients, and fine

sediment to the area. The introduction of additional freshwater could facilitate

organic sediment deposition, improve biological productivity, and prevent further

deterioration of the marshes. Specific project objectives include, but are not limited

to, the following, which are applicable to all three subunits:

Prevent, reduce, and/or reverse future wetland loss

Achieve and maintain characteristics of sustainable marsh hydrology

Reduce salinity levels in Study Area

Increase sediment and nutrient load to surrounding wetlands

Increase residence time of freshwater

Sustain productive fish and wildlife habitat

Existing Conditions: The overall Study Area is located mostly in Terrebonne

Parish in southeast Louisiana at the northern edge of the Gulf of Mexico and

encompasses approximately 1,100 square miles (700,000 acres). The Study Area

lies within the southern end of the Terrebonne Basin and contains a complex of

habitat types, including natural levees, lakes, swamps, marshes, and bayous formed

from sediments of abandoned Mississippi River deltas.

The Atchafalaya Basin Floodway; GIWW; Atchafalaya River; Bayous Chene, Boeuf,

and Black Navigation Channel; HNC; and Houma area levees and pump systems,

drainage canals, and access canals have altered the hydrology of the Study Area.

Flows within the Study Area are generally driven by stages in the Lower

Atchafalaya River. Major flow channels within the Study Area are the Atchafalaya

River, the GIWW, and the HNC.

Historically, the Atchafalaya River and Bayou Lafourche were sources of sediment

to the Study Area. Sediment would be delivered throughout the Study Area during

annual floods through systems of distributary channels and through overland flow.

Since that time, the altered hydrology due to the construction of the Atchafalaya

Basin Floodway; GIWW; Atchafalaya River; Bayous Chene, Boeuf, and Black

Navigation Channel; Houma Navigation Canal; and Houma area levees and pump

systems, drainage canals, and access canals have altered sediment distribution

within the Study Area. Today, suspended sediments in the Atchafalaya River,

Bayou Lafourche, and Bayou Boeuf water are the sources of new sediment to the

Study Area. The small amounts of sediments that enter the basin are not well

distributed. U.S. Geological Survey (USGS) estimated land loss for the period from

1956 to 2008 to be 2,597 acres/year (approximately 0.3% per year); land loss is

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WRDA 2007 Section 7006(e)(3) ES-15 October 2010

variable across the subunits with eastern and southern areas generally exhibiting

more land loss.

Future Without Project: In the absence of supplemental freshwater from the

Atchafalaya River, subsidence, sea level rise, wave erosion, and saltwater intrusion

will continue to be problems. Building of the Atchafalaya River delta would

continue to impact stages on the lower Atchafalaya River. As stages increase,

eastward flows along the GIWW would increase, carrying with them suspended

sediments. These sediments would be distributed through the Study Area

according to the flow patterns we see today, resulting in localized areas of land

building but not on a large scale. Federal, state, and local programs may

beneficially use dredged materials within the Study Area. Construction of channels

and maintenance of existing channels would be sources of sediment from within the

Study Area. Additionally, sediment may be brought from sources outside the Study

Area.

In the central and eastern subareas, wetlands would continue to be lost because of

subsidence, inundation of marsh plants, and subsequent erosion in brackish and

saline marshes. As these marshes disappear, salt water would begin to move

northward more rapidly, further stressing fresh and intermediate marshes. The

overall habitat value and acreage of remaining wetlands would decline, and 102,000

acres (18%) of remaining vegetated wetlands in the Study Area are predicted to be

lost over the next 50 years. Several of the subareas are predicted to lose all

emergent wetlands in the next 50 years.

Loss of wetlands will have negative impacts on essential fish habitat (EFH) and

threatened and endangered species as well as potential impacts to oil and gas

infrastructure and navigable waterways, which currently benefit from protection

provided by the wetlands.

Alternatives: The PDT developed an initial list of 17 measures based on the

strategies of freshwater supply and distribution, sediment supply and distribution,

restore/maintain historic geomorphic features, invasive species management,

navigation management, and vegetation management. Measures were screened

and evaluated on potential benefits to each subunit.

From the suites of remaining general measures, 97 specific measures were

combined to form eight project alternatives. The interagency PDT then evaluated

these alternatives and their specific measures. After screening, 35 of the 97

measures were eliminated because they were beyond the scope of the study

authorization, cost prohibitive, environmentally damaging, their benefits could not

be determined, or another feature accomplished the same purpose.

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WRDA 2007 Section 7006(e)(3) ES-16 October 2010

The eight preliminary alternatives were analyzed in terms of the AAHUs produced

and the initial cost calculations for construction and operations and maintenance;

an additional alternative was added based on an increment between two other

alternatives.

National Ecosystem Restoration Plan: Based on the results of the WVA

modeling, the IWR Planning Suite analysis, and the impacts of alternative plans

listed in this study, Alternative 2 was chosen as the NER plan as well as the

recommended plan.

Recommended Plan: After analysis, Alternative 2 was determined to be a Best

Buy and was chosen as the recommended plan. This alternative includes a variety

of measures in the three subunits and is shown in Figure ES-6. Table ES-3

summarizes the project costs and benefits both by the individual LCA ARTM and

LCA MOHNL projects and by total cost of the combined project.

Recommended plan components:

Elimination of GIWW constrictions

Measures to restrict, increase, and control water for each of the three

subunits:

o West - Bayou Penchant Area

Dredging

Sediment plug

Weir

o Central - Lake Boudreaux Area

Culverts

Levees

Dredging

Marsh terraces and berms

Sediment plugs

Modified operation of the future HNC Lock Complex

Sluice gated box culvert

o East - Grand Bayou Area

Culverts

Dredging

Gaps in canal spoil banks

Marsh berms

Sediment plugs

Removal of a weir and soil plug

Alternative 2 meets most of the study objectives. The recommended plan would

decrease the rate of decline of the wetlands to ensure their ability to provide

geomorphic and hydrologic form and function for the 50-year period of analysis.

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WRDA 2007 Section 7006(e)(3) ES-17 October 2010 Figure ES-6: LCA ARTM recommended plan features (Alternative 2)

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WRDA 2007 Section 7006(e)(3) ES-18 October 2010

Marsh habitat for essential fish and wildlife species would be sustained, mimicking

as closely as possible conditions that occur naturally in the area. The alternatives

were designed to work with the natural, fluid, soft environment of coastal

Louisiana.

The recommended plan / NER plan includes the entire Study Area with the most

critical need of restoration and meets the intent of the plan as described in the 2004

LCA Report. The recommended plan would result in a net gain of 9,655 acres of

marsh habitat and would yield 3,220 AAHUs. Benefits would include increased

freshwater flows and nutrients into the Study Area. The estimated fully funded

project cost is $305,500,000.

Table ES-3: LCA ARTM/MOHNL NER and Recommended Plan

Alt. 2

(Recommended

Plan / NER)

ARTM MOHNL Total

AAHUs 2,977 243 3,220

Cost effective (Yes/No/Best Buy) Best Buy

$ Annualized cost/AAHUa $3,272

MCACES fully funded project costb $303,900,000 $1,600,000 $305,500,000

Authorized cost in WRDA Title VII,

Section 7006 (e)(3)(A) for LCA ARTM $221,200,000 $18,100,000 $239,300,000

Maximum cost limited by Section

902c $325,496,000 $24,500,000 $349,995,500

a Based on preliminary construction cost, not the fully funded cost.

b Fully funded project cost includes inflation adjusted from the October 2006 price levels through the projected midpoint

of project construction.

c This total includes the authorized cost for the ARTM and MOHNL projects

Cost Sharing: Following the feasibility phase, the cost share for the planning,

design, and construction of the project as well as adaptive monitoring would be 65%

Federal and 35% non-Federal. The State of Louisiana, represented by the CPRA,

would be responsible for 100% of LERRDs cost and, following construction, the

future OMRR&R costs. Table ES-4 shows the cost sharing amounts based on the

first cost of construction.

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WRDA 2007 Section 7006(e)(3) ES-19 October 2010

Table ES-4: LCA ARTM Cost Sharing

Project Feature Total Cost

ARTM

Total Cost

MOHNL

Non-Federal Federal

% Cost % Cost

Total first cost of

constructiona $283,534,000 $1,496,000 35 $99,760,000 65 $185,270,0

00

LERRD credit $8,168,000 $0 100 $8,168,000 0 $0

Monitoring and

adaptive

management

$18,776,000 $2,428,000 35 $7,456,000 65 $13,846,00

0

OMRR&R b $0 $73,000 100 $73,000 0 $0

a Total first cost of construction is based on the sum of the planning, engineering, and design; construction

management (i.e. supervisions and administration); LERRDs; and monitoring and adaptive management and

is based on October 2010 price levels.

b Average annual cost based on October 2010 price levels.

Public Involvement: An NOI to prepare a draft SEIS for the LCA Convey

Atchafalaya River Water to Northern Terrebonne Marshes Restoration FS was

published in the Federal Register in December 2008. A public scoping meeting was

held in February 2009. The Draft FS/SEIS was released to the public in May 2010,

followed by a 45-day public review period which included a public meeting. Public

comments were received during the scoping meeting and Draft FS/SEIS public

review and have been incorporated into the report.

Coordination and Compliance: Following completion of the Final FS/SEIS, the

Assistant Secretary of the Army for Civil Works would issue a ROD concerning the

proposed action. Full compliance with statutory authorities would be accomplished

upon review of the Final FS/SEIS by appropriate agencies and the public and the

signing of the ROD, in compliance with NEPA. The USACE has coordinated with

the USFWS, NMFS, and LDWF as per the Fish and Wildlife Coordination Act. A

coordination act letter report has been received and the comments incorporated into

the project plan. State certifications for coastal zone consistency and 401 has also

been received.

Areas of Controversy and Unresolved Issues: Potential areas of controversy

include construction of the HNC Lock Complex under an authority other than the

LCA Program. The recommend plan / NER plan relies on the operation of the HNC

Lock Complex for environmental purposes after 2025. The impact to the project in

the event the HNC is not constructed is estimated at 243 AAHUs.

RSLR rates higher than the historical rate have the potential to greatly reduce or

even eliminate the benefits of this project. Intermediate RSLR rates would reduce

benefits by 66% and high RSLR rates would eliminate benefits. Determining the

risk of higher sea level rise is not possible at this time. The degree to which Study

Area marshes would respond to increased freshwater inputs associated with project

features remains unresolved since there are no similar projects in the Study Area to

use for verification.

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Fisheries access impacts on project benefits are currently unresolved; inclusion of

fish impacts in the calculations of the AAHUs may have resulted in negative

AAHUs for all alternatives. The decision to eliminate these potential impacts was

made in calculating benefits and potential modifications to the methodology are

being investigated by various natural resource agencies.

Conclusions and Recommendations: The LCA ARTM / MOHNL Project

recommended in this report, Alternative 2, is in the overall public interest and

would work to restore some deltaic processes within the Study Area. The fully

funded project cost is estimated at $305,500,000, and this project would be cost

shared by the non-Federal sponsor, the State of Louisiana, at 35% non-Federal and

65% Federal. Additionally, the non-Federal sponsor would be 100% responsible for

the OMRR&R.

SMALL DIVERSION AT CONVENT/BLIND RIVER

The LCA Convent/Blind River Diversion Study Area is located approximately

equidistant between Baton Rouge and New Orleans, Louisiana; St. James Parish

contains most of the Study Area, but the northwest portion of the distribution area

extends into Ascension Parish. The project would facilitate the restoration of a

portion of the Maurepas Swamp in the headwaters of the Blind River watershed

that is deteriorating due to lack of freshwater, sediments, and nutrients. Figure

ES-7 shows the LCA Small Diversion at Convent/Blind River Study Area.

The Maurepas Swamp is one of the largest remaining tracts of coastal freshwater

swamps in Louisiana. The Maurepas Swamp is used for fishing, hunting, and other

recreational activities; as a large contiguous tract of bald cypress-tupelo swamp

near the New Orleans metropolitan area, it has considerable cultural significance.

Necessity for and Objectives of Action: Construction of the MR&T flood control

system has cut off the Maurepas Swamp (and Blind River) from the natural,

periodic, near-annual flooding by the Mississippi River. This has resulted in a

degradation/deterioration process and reduced biological productivity in the swamp

due to lack of freshwater, nutrients, and sediment input from the Mississippi River.

The swamp is also subsiding due to natural causes and possibly due to man-made

activities such as oil, gas, and groundwater withdrawals. The reduced biological

productivity combined with the lack of sediment from the river has reduced soil

formation (accretion) to a rate less than the subsidence. Other disruptions to the

natural drainage patterns have occurred to the hydrology of the area due to

construction of logging trails, drainage channels, pipelines and other utilities, and

roads through the swamp.

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WRDA 2007 Section 7006(e)(3) ES-21 October 2010 Figure ES-7: Study Area with subunits - LCA Small Diversion at Convent / Blind River

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The overall objective of the LCA Small Diversion at Convent/Blind River Project is

to reverse the trend of deterioration of southeastern portion of Maurepas Swamp

and Blind River.

Specific project objectives are:

Promote water distribution in the southeastern portion of Maurepas Swamp

Facilitate swamp building

Establish hydro period fluctuation in the swamp

Improve fish and wildlife habitat in the swamp and in Blind River

Existing Conditions: Hydrology and water levels in the Study Area differ

substantially from historical conditions due to isolation from Mississippi River

floods in conjunction with further human modifications. Flow directions in general

correspond to historical patterns for the Study Area and vicinity. However,

drainage features have altered the rates at which runoff and tidal inflow enter and

leave the Blind River, adjoining channels, and the adjacent swamp.

Existing habitat types in the Study Area include bald cypress-tupelo swamp,

bottomland hardwood forest, freshwater marsh, scrub-shrub swamp, and aquatic

bed floating vascular. Habitat structure has changed over time; however, bald

cypress-tupelo swamp has remained the dominant habitat type, predating human

disturbance and persisting today. The area has abundant fish and wildlife

resources.

Future Without Project Conditions: The future without project conditions

would result in the persistence of existing conditions. This includes a limited ability

of the swamp to drain, which results in persistent flooding that conflicts with

historical drying cycles in the swamp, short circuiting of the natural drainage

patterns, ponding and stagnant waters in some areas, and minimal contribution

and circulation of nutrients and sediments in the swamp. Blind River and

Maurepas Swamp would continue to deteriorate.

Minimal soil building and subsidence that have resulted in a net lowering of ground

surface elevation would continue and the swamp will continue to be persistently

inundated. The limited ability to drain and the persistent flooding that exists in the

swamp would continue. Under the existing conditions, the frequency of dry out

conditions (water levels below 0.5 feet [ft]) would occur only 1% of the time. This

occurrence interval would limit seed germination and sapling survival. The

sediment deficit has and would continue to result in increased subsidence, increased

water depths, and decreased productivity and diversity in the swamp ecosystem.

Increases in relative sea level due to subsidence and sea level rise would continue to

extend flood duration and elevate flood stage within Maurepas Swamp,

accompanied by impoundment of hypoxic, nutrient-deficient water.

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Without action, the swamp is predicted to continue to deteriorate at the same or

accelerated rates, with approximately 21,400 acres of bald cypress-tupelo swamp

projected to be lost over the next 50 years, including 3,300 acres of bald cypresstupelo swamp that would become marsh in 20 to 30 years, 7,900 acres of bald

cypress-tupelo swamp that would become marsh in 30 to 50 years, and 10,140 acres

of bald cypress-tupelo swamp that would become marsh at a point beyond 50 years.

As interior forested wetlands convert to marsh and open water, there would be an

expected loss of habitat for species dependent on swamp forest habitat. Increased

impoundment and limited circulation due to limited freshwater inputs and sea level

rise would continue to result in anoxic conditions detrimental to fish and other

aquatic organisms.

Other diversion projects in the area may work to offset some of the changes in water

quality, such as decreases in dissolved oxygen and nutrients. Because of the spatial

separation between those diversion projects and the Blind River / Maurepas

Swamp, the effects of those diversion projects on the Study Area may be minimal.

Alternatives: A list of structural and nonstructural measures was developed.

Structural measure strategies included water management modifications,

distribution systems, transmission systems, diversion systems, methods and

locations of crossing the Mississippi River Levee, water quality management

methods, and sediment management methods. Nonstructural measure strategies

included water quality management, vegetation management, recreational access

and enhancements, and real estate acquisitions. An initial list of 99 measures was

screened, and 51 measures were retained.

A preliminary array of 12 alternatives and the No Action Alternative were

developed from the measures to achieve the overall project goals and objectives.

The 12 alternatives were formulated to consider 11 different options for the

diversion point, different diversion methods, the transmission system, the

distribution system, and the benefit area. Through iterative screening of the

alternatives with respect to their viability to meet project goals, five alternatives

including the No Action Alternative were considered for further detailed analysis in

the final array.

National Ecosystem Restoration Plan: Based on the results of the WVA

modeling, the IWR Planning Suite analysis, and the impacts of alternative plans

listed in this study, Alternative 2 was chosen as the project NER plan as well as the

recommended plan.

Recommended Plan: The four alternatives in the final array and the No Action

Alternative were screened and Alternative 2, a 3,000 cubic feet per second (cfs)

diversion at Romeville, was identified as the recommended plan. The recommended

plan is shown in Figure ES- 8. Table ES-5 summarizes project benefits and costs.

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Figure ES- 8: LCA Small Diversion at Convent / Blind River recommended plan features (Alternative 2)

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Recommended plan components:

Diversion culverts and inlet canal

Transmission canal and culverts

Control structures

Multiple berm gaps

Cross culverts at 4 locations on Highway 61

Instrumentation for control and monitoring

The recommended plan best meets the screening criteria; would accomplish the

planning objectives and goals; would be consistent with the USACE Environmental

Operating Principles; and would contribute to reversing the trend of deterioration

in the southeast part of the Maurepas Swamp. The recommended plan would

improve a total of 21,369 acres of bald cypress-tupelo swamp that are in various

stages of deterioration and generate 6,421 AAHUs of benefit. The recommended

plan would improve 3,295 acres of bald cypress-tupelo swamp that would become

marsh in 20 to 30 years without project implementation, 7,934 acres of bald cypresstupelo swamp that would become marsh in 30 to 50 years without project

implementation, and 10,140 acres of bald cypress-tupelo swamp that would become

marsh in greater than 50 years without project implementation. The estimated

fully funded project cost is $123,140,000.

Table ES-5: LCA Small Diversion at Convent/Blind River NER /

Recommended Plan

Alt. 2

(Recommended plan

/NER)

AAHUs 6,421

Cost effective (Yes/No/Best Buy) Best Buy

$Annualized cost/AAHUa $879

Fully funded project costb $123,140,000

Authorized cost in WRDA Title VII, Section 7006

(e)(3)(A) for the LCA Small Diversion at

Convent/Blind River

$88,000,000

Maximum cost limited by Section 902 $124,230,000

a Based on preliminary construction cost, not the fully funded cost

b Fully funded project cost includes inflation adjusted from the October 2006 price levels through the

projected midpoint of project construction.

Cost Sharing: Following the feasibility phase, the cost share for the planning,

design, and construction of the project as well as adaptive monitoring would be 65%

Federal and 35% non-Federal. The State of Louisiana, represented by the CPRA,

would be responsible for 100% of LERRDs cost and, following construction, the

future OMRR&R costs. Table ES-6 shows the cost sharing amounts based on the

first cost of construction.

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Table ES-6: LCA Small Diversion at Convent/Blind River Cost Sharing

Project Feature Total Cost Non-Federal Federal

% Cost % Cost

Total first cost of

constructiona $116,791,000 35 $40,877,000 65 $75,914,000

LERRD credit $3,920,000 100 $3,920,000 0 $0

Monitoring and adaptive

management $6,620,000 35 $2,317,000 65 $4,303,000

OMRR&R b,c $2,754,000 100 $2,754,000 0 $0

a Total first cost of construction is based on the sum of the planning, engineering, and design; construction management

(i.e. supervision and administration); LERRDs; and monitoring and adaptive management and is based on October 2010

price levels.

b Average annual cost based on October 2010 price levels.

c Includes annual operation & maintenance as well as annual dredging.

*Costs in this table represent first costs not the fully funded cost through the mid-point of construction ( $123,140,000)

Public Involvement: An NOI to prepare a draft SEIS for the LCA Small

Diversion at Convent/Blind River was published in the Federal Register in

December 2008. A public scoping meeting was held in February 2009. The Draft

FS/SEIS was released to the public in May 2010, followed by a 45-day public review

period, which included a public meeting. Public comments were received during the

scoping meeting and Draft FS/SEIS public review and have been incorporated into

the report.

Coordination and Compliance: Following completion of the Final FS/SEIS, the

Assistant Secretary of the Army for Civil Works would issue a ROD concerning the

proposed action. Full compliance with statutory authorities would be accomplished

upon review of the Final FS/SEIS by appropriate agencies and the public and the

signing of the ROD, in compliance with NEPA. The USACE has coordinated with

the USFWS, NMFS, and LDWF as per the Fish and Wildlife Coordination Act. A

coordination act letter report and biological opinion have been received and the

comments incorporated into the project plan. State certifications for coastal zone

consistency and 401 water quality have also been received.

Areas of Controversy and Unresolved Issues: Meetings and discussions with

the public; local, state, and federal agencies; and the PDT indicate support for the

project and did not identify any areas of controversy or unresolved issues.

Conclusions and Recommendations: The LCA Small Diversion at Convent/

Blind River Project recommended in this report, Alternative 2, is in the overall

public interest and would work to restore the natural hydrology and ecology within

Maurepas Swamp. The fully funded project cost is estimated at $123,140,000, and

this project would be cost shared by the non-Federal sponsor, the State of

Louisiana, at 35% non-Federal and 65% Federal. Additionally, the non-Federal

sponsor would be 100% responsible for the OMRR&R.

TERREBONNE BASIN BARRIER SHORELINE RESTORATION

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WRDA 2007 Section 7006(e)(3) ES-27 October 2010

The LCA Terrebonne Basin Barrier Shoreline Restoration (TBBSR) Study Area is

located approximately 36 miles south of Houma, Louisiana, and 5 miles west of Port

Fourchon. The Terrebonne Basin barrier shoreline is composed of two barrier

island reaches in Terrebonne and Lafourche parishes: Isles Dernieres and the

Timbalier Islands. These barrier islands have undergone significant reductions in

size due to a number of natural processes and human actions, including lack of

sediment, storm-induced erosion and breaching, subsidence, sea level rise, and

hydrologic modifications (such as navigation and oil and gas canals). Figure ES-9

shows the LCA TBBSR Study Area.

Need for and Objectives of Action: Natural processes and human actions, such

as the construction of oil field canals and the containment of waterways, have

threatened the long-term viability of the Study Area. These processes and activities

have caused significant adverse impacts to the Terrebonne Basin barrier island

shoreline, resulting in extensive barrier island habitat loss and ecosystem

degradation (USACE, 2004a).

Based on the function of these barrier islands and problems identified for the

Terrebonne islands during this study, the following planning objectives were

developed to assist the development and evaluation of alternative plans.

Restore the minimized barrier island conditions that provide the geomorphic

form and ecologic function of the Terrebonne Basin barrier island, reducing

volume loss within the LCA TBBSR Study Area below the historical average

(1880 through 2005).

Restore and improve various barrier island habitats that provide essential

habitats for fish, migratory birds, and other terrestrial and aquatic species,

mimicking, as closely as possible, conditions that occur naturally in the area

for the 50-year period of analysis.

Increase sediment input to supplement long-shore sediment transport

processes along the Gulf shoreline by mechanically introducing compatible

sediment and increasing the ability of the restored area to continue to

function and provide habitat for the 50-year period of analysis with minimum

continuing intervention.

Existing Conditions: The Study Area includes the Isles Dernieres and Timbalier

Barrier island reaches located in Terrebonne and Lafourche parishes, Louisiana.

These barrier islands define the southern boundary of the Terrebonne Basin and

separate the shallow estuarine bays and saline marshes from the Gulf of Mexico.

The islands are generally described as a thin cap of sand over a thick mud platform

and vary from 0.1 to 1.2 miles wide. Oil and gas production facilities are prevalent

in the East Timbalier Islands, while only a few scattered facilities are present along

Timbalier Island. Oil and gas canals are present on both islands.

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WRDA 2007 Section 7006(e)(3) ES-28 October 2010 Figure ES-9: Study Area - LCA TBBSR

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WRDA 2007 Section 7006(e)(3) ES-29 October 2010

Louisiana's barrier islands are eroding at a rate of up to 20 meters per year;

according to recent USGS estimates, several will disappear by the end of the

century (LACPR, 2009). The barrier islands in the Study Area currently exist in a

sediment-starved environment typical of the erosional barrier arc stage of the

deltaic cycle. The lack of sediment is also attributed to the islands being cut off

from a potential sediment source by the MR&T flood control system and other

navigation projects, such as the Belle Pass jetties to the east of the Study Area.

Navigation channels, control of the Mississippi River and its distributaries, and

canals dredged for oil and gas extraction have also dramatically altered the

hydrology of the Study Area. By altering salinity gradients and patterns of water

and sediment flow through marshes, canal dredging not only directly changed land

to open water, but also indirectly changed the processes essential to a healthy

coastal ecosystem. The relative mean sea level (MSL) trend at Grand Isle,

Louisiana, is an increase of 9.24 millimeters/year. With the USACE projections of

future changes in MSL (2009b), these rates are the highest rates projected along the

contiguous United States (USACE, 2004c).

The area has state and national significance. The Louisiana Natural Heritage

Program lists imperiled vegetative communities occurring in the Study Area,

including coastal mangrove thicket, coastal dune grassland, and coastal dune shrub

thicket. Fish and wildlife resources of the barrier islands are important to

threatened and endangered species as well as commercial fisheries.

Future Without Project Conditions: Without Federal action, the barrier island

habitat within the Terrebonne Basin will continue to be subjected to the factors and

processes that are contributing to the loss of the Timbalier and Isles Dernieres

barrier island chains and will result in a direct loss of the barrier islands to open

water. Land loss along Terrebonne Basin Barrier Shoreline would likely continue

at rates similar to present, resulting in the projected loss of 3,220 acres of the

barrier island will be converted to open water by 2062. Lost habitats would include

beach pioneer, frontier zone, dune, barrier grassland, and salt marsh, associated

with barrier and coastal wetland habitats.

Impacts would also include a decline in wetland vegetation and primary

productivity inland of the Study Area. 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,

recreation, aesthetic, and socioeconomic resources. Impacts would also occur to

navigation, the oil and gas industry, and commercial fisheries.

Alternatives: An initial list of measures was developed including 19 hard

structural measures (e.g., revetments, groins, canal plugs) and 12 soft-structural

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WRDA 2007 Section 7006(e)(3) ES-30 October 2010

measures (e.g., dune restoration, marsh creation, herbivore control). After

screening of the initial list of 31 measures, 16 were retained for further analysis.

Secondary screening of the measures was conducted with combinations of measures

to address specific project objectives. As a result of the secondary screening, it was

determined that a combination of beach, dune, and marsh restoration measures

would be needed to achieve the primary objective of restoring geomorphic form and

ecologic function of the barrier islands.

From the eight screened measures remaining, nine alternative plans were

developed. Five restoration plans, denoted as Plans A through E, were developed as

part of plan formulation.

Plan A - No Action Alternative

Plan B - Minimum Design Plan

Plans C through E - Design Plan Scalar increments of 5 years of advanced fill

based on Plan B (e.g., Plan D had 5 years of additional advanced fill

compared to Plan C)

For the LCA TBBSR, borrow areas were also located and screened to provide

material for the project. The borrow area map developed by Khali and Cantu (2008)

was used as a starting point for the PDT’s borrow area search effort. Their tabular

compilation included the location of the borrow area, estimated volume of available

fill material, volume of material already dredged from the borrow area, and

pertinent geotechnical and geophysical references. Seven criteria were used in the

initial screening of the borrow areas. Some sites were immediately screened out

due to being close to the depth of closure. The borrow areas that were carried

forward were outside the depth of closure, had adequate capacity of compatible

material, and included cultural survey information.

National Ecosystem Restoration Plan: Analysis of the five alternatives in the

final array and the No Action Plan resulted in Alternative 5 being chosen as the

NER plan. The NER plan, which consists of Raccoon Plan E with Terminal Groin,

Whiskey Plan C, Trinity Plan C, and Timbalier Plan E, was chosen because it is

cost effective and a Best Buy that fulfills the planning objectives of the project.

Immediately after construction, the NER plan would add 3,283 acres of habitat

(dune, intertidal, and supratidal) to the existing island footprints of Raccoon,

Whiskey, Trinity, and Timbalier Islands, increasing the total size of the islands to

5,840 acres. The NER plan would provide essential habitat for many species

(including threatened and endangered species), complement and sustain other

exiting restoration projects in the Study Area, and provide a system-wide approach

for the restoration of the Terrebonne Basin barrier islands. The NER plan would

generate 2,063 AAHUs for the impact areas at a fully funded project cost estimated

at $689,000,000. However, this NER plan exceeds the WRDA 2007 authorization.

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WRDA 2007 Section 7006(e)(3) ES-31 October 2010

Table ES-7 summarizes project benefits and costs of the NER plan. Figure ES-10

through Figure ES-13 show the four island plans included in the NER plan.

Beach renourishment events would be needed at staggered intervals for the

different islands over the 50-year period of analysis to maintain the benefits. The

cost of Alternative 5 exceeds the authorization for this project; however, additional

authority for implementation is recommended.

Recommended Component of Construction: Analysis of the individual islands

included in the NER plan (Alternative 5) resulted in Whiskey Island Plan C

(Alternative 11) being chosen as the recommended component of construction of the

NER plan. Whiskey Island Plan C would add 469 acres of habitat (dune, intertidal,

and supratidal) to the existing island footprint, increasing the size of the island to

1,272 acres. The plan was designed to create 379 AAHUs at a fully funded project

cost of $119,000,000. The plan represents an implementable increment of the NER

plan, is cost effective, and is within the cost and scope of the authorization.

Renourishment events would be needed for Whiskey Island in target year (TY) 20

and TY40 to maintain the benefits. The non-Federal sponsor fully supports

Alternative 11 as the recommended component of construction of the NER plan

under the current authorization. Whiskey Plan C (Alternative 11) is shown in

Figure ES-10. Table ES-7 summarizes project benefits and costs of the

recommended component of construction.

Table ES-7: LCA TBBSR NER Plan &

Recommended Component of Construction

Alt. 11

(Recommended Component

of Construction)

Alt. 5

(NER)

AAHUs 379 2,063

Cost effective (Yes/No/Best Buy) Yes Best Buy

$Annualized cost/AAHU a $210,121 $197,704

Fully funded project costb $119,000,000 $689,000,000

Authorized cost in WRDA Title VII,

Section 7006 (e)(3)(A) for the LCA

TBBSR

$124,600,000

Maximum cost limited by Section 902 $180,900,000

a Based on preliminary construction cost, not the fully funded cost

b Fully funded project cost includes inflation adjusted from the October 2006 price levels through the projected midpoint of project construction.

Cost Sharing: Following the feasibility phase, the cost share for the planning,

design, and construction of the project as well as adaptive monitoring would be 65%

Federal and 35% non-Federal. The State of Louisiana, represented by the CPRA,

would be responsible for 100% of LERRDs cost and, following construction, the

future OMRR&R costs. Table ES-8shows the cost sharing amounts for the NER

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WRDA 2007 Section 7006(e)(3) ES-32 October 2010 Figure ES-10: LCA TBBSR Whiskey Island Plan C

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WRDA 2007 Section 7006(e)(3) ES-33 October 2010 Figure ES-11: LCA TBBSR Trinity Island Plan C

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WRDA 2007 Section 7006(e)(3) ES-34 October 2010 Figure ES-12: LCA TBBSR Raccoon Island - Plan E with Terminal Groim

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WRDA 2007 Section 7006(e)(3) ES-35 October 2010

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WRDA 2007 Section 7006(e)(3) ES-36 October 2010

Plan. Table ES-9 shows the cost sharing amounts for the recommended component

of construction.

Table ES-8: LCA TBBSR Cost Sharing for Recommended Plan

Project Feature Total Cost Non-Federal Federal

% Cost % Cost

Total first cost of

constructiona $646,931,000 35 $226,426,000 65 $420,505,000

LERRD credit $692,000 100 $692,000 0 $0

Monitoring and adaptive

management $9,960,000 35 $3,486,000 65 $6,474,000

OMRR&Rb,c $11,300,000 100 $11,300,000 0 $0

a Total first cost of construction is based on the sum of the planning, engineering, and design; construction management (i.e.

supervision and administration); LERRDs; and monitoring and adaptive management and is based on October 2010 price levels.

b Average annual cost based on October 2010 price levels

c Includes multiple renourishment events

Table ES-9: LCA TBBSR Cost Sharing for

Recommended Component of Construction

Project Feature Total Cost Non-Federal Federal

% Cost % Cost

Total first cost of

constructiona $113,434,000 35 $39,702,000 65 $73,732,000

LERRD credit $65,000 100 $65,000 0 $0

Monitoring and adaptive

management $5,820,000 35 $2,037,000 65 $3,783,000

OMRR&Rb,c $6,900,000 100 $6,900,000 0 $0

a Total first cost of construction is based on the sum of the planning, engineering, and design; construction management (i.e.

supervision and administration); LERRDs; and monitoring and adaptive management and is based on October 2010 price levels.

b Average annual cost based on October 2010 price levels.

c Includes multiple renourishment events.

Public Involvement: An NOI to prepare a draft SEIS for the LCA TBBSR Project

was published in the Federal Register in December 2008. A public scoping meeting

was held in February 2009. The Draft FS/SEIS was released to the public in June

2010, followed by a 45-day public review period, which included a public meeting.

Public comments were received during the scoping meeting and Draft FS/SEIS

public review and have been incorporated into the report.

Coordination and Compliance: Following completion of the Final FS/SEIS, the

Assistant Secretary of the Army for Civil Works would issue a ROD concerning the

proposed action. Full compliance with statutory authorities would be accomplished

upon review of the Final FS/SEIS by appropriate agencies and the public and the

signing of the ROD, in compliance with NEPA. The USACE has coordinated with

the USFWS, NMFS, and LDWF as per the Fish and Wildlife Coordination Act. A

coordination act letter report and a biological opinion have been received and the

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WRDA 2007 Section 7006(e)(3) ES-37 October 2010

comments incorporated into the project plan. State certifications for coastal zone

consistency and 401 water quality have also been received.

Area of Controversy and Unresolved Issues: An area of controversy that exists

is the cost effectiveness of hardened structures, most notably rock breakwaters and

revetments, in achieving the project goals. These measures are supported by the

local Parish Government as well as groups and individuals in the scientific

community. Analysis for this project indicates renourishment is a more effective

method for addressing the erosion on most of the islands and a terminal groin was

only considered cost effective for Raccoon Island.

Conclusions and Recommendations: The LCA TBBSR Project, Alternative 5, as

the NER plan is recommended in this report and is in the overall public interest

and would work to restore geomorphic form and ecologic function of Raccoon,

Whiskey, Trinity, and Timbalier islands. The fully funded project cost is estimated

at $689,000,000. As a recommended component of construction of the NER plan,

Whiskey Island Plan C (Alternative 11) is recommended. The fully funded cost of

Alternative 11 is $119,000,000. This project would be cost shared by the nonFederal sponsor, the State of Louisiana, at 35% non-Federal and 65% Federal.

Additionally, the non-Federal sponsor would be 100% responsible for the OMRR&R.

MEDIUM DIVERSION AT WHITE DITCH

The LCA Medium Diversion at White Ditch (MDWD) Study Area is located near

Phoenix, Louisiana, which is approximately 23 miles south-southeast of the city of

New Orleans along the Mississippi River and includes the Breton Sound. The

White Ditch Study Area is located just north and east of the MR&T flood control

system. Wetlands in the Study 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 Study 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. Figure ES-14 shows the MDWD Study Area.

Need for and Objectives of Action: The altered supply and distribution of

freshwater, lack of 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. Degradation of the existing

marshes has made them more vulnerable to Gulf storm events (extreme and

seasonal), resulting in accelerated degradation, altered hydrology, and changed

salinity regimes.

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WRDA 2007 Section 7006(e)(3) ES-38 October 2010 Figure ES-14: Study Area - LCA MDWD

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WRDA 2007 Section 7006(e)(3) ES-39 October 2010

The overarching project goal 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

to the area between the Mississippi River and the River aux Chenes ridges. This

would contribute to 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.

Specific project objectives include 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.

Restore adequate freshwater and nutrient inputs into the Study 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 Study Area equivalent to an average of

approximately 1,300,000 cubic yards of sediment per year.

Existing Conditions: Historically, the lower Mississippi River was prone to

frequent spring floods that caused catastrophic damage and loss of life post

settlement (Davis, 1993; USACE, 2009a). Federal flood control and navigation

measures that began in earnest with the authorization of the MR&T flood control

system by the Flood Control Act of 1928 have since regulated the river’s stage and

flow and mitigated damage (USACE, 2009a).

The absence of a supply of freshwater, sediment, and nutrients from the Mississippi

River floods 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

Study Area to maintain a balance of emergent wetland and shallow water.

The majority of the LCA MDWD Study Area is estuarine habitat, including

extensive marshes. Intermediate marsh is the lowest in salinity and varies slightly

in species dominance from freshwater marshes. Approximately 18,771 acres of

intermediate marsh are present in the Study Area. Brackish marsh is present at

slightly higher salinity and includes approximately 9,338 acres in the Study Area.

The saline marsh community is about 13,274 acres of the Study Area. There are

limited amounts of riparian and upland habitat in the Study Area. From 1956 to

2008, approximately 12,762 marsh acres of all types have been converted to open

water.

The marsh ecosystem supports a diverse fishery. Aquatic and tidally influenced

wetland habitats in portions of the LCA MDWD Study Area are designated as EFH

for various federally managed species.

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Future Without Project Conditions: The future without project condition for

White Ditch would continue to see declines in overall wetland acres of all types.

The current altered deltaic process would result in the lack of freshwater, nutrients

and sediments in the Study Area 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 would, 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. 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.

Water bodies would grow larger, and wave erosion would accelerate, causing further

land loss, making remaining marshlands in the Study Area and the larger Breton

Sound Basin more vulnerable to tropical storms. The future without project

condition would 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

would likely see additional salt water intrusion and conversion of the remaining

intermediate and brackish marsh to saline marsh types with the associated salttolerant or marine fauna.

Alternatives: An initial list of 22 measures was developed, which includes the

categories of freshwater supply, hydraulic distribution, sediment supply and

distribution, protection and sustainability, and invasive species management. After

screening, eight measures were carried forward and those measures were used to

develop five alternative plans.

The five alternatives include river diversions, which ranged in size from 15,000 to

100,000 cfs. Additional analysis and investigation resulted in a group of diversions

ranging from 5,000 to 35,000 cfs carried forward for further analysis. Five potential

locations for diversions of the various sizes were considered. Based on this

screening, two locations were included in the final array.

The remaining location options and the diversion sizes were combined to develop

the preliminary alternative plans. Eight alternatives and the No Action Alternative

were analyzed. The eight alternatives included two locations and diversions from

5,000 to 35,000 cfs. Analysis of the eight alternatives resulted in Alternative 4, a

35,000 cfs diversion at Location 3, being chosen as the NER and recommended plan.

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National Ecosystem Restoration Plan: Based on the results of the WVA

modeling, the IWR Planning Suite analysis, and the impacts of alternative plans

listed in this study, Alternative 4 was the project NER plan as well as the

recommended plan.

Recommended Plan: The recommended plan, Alternative 4, cost exceeds the

authorization for this project in WRDA 2007. The recommended plan / NER plan

has been determined to reasonably maximize ecosystem restoration benefits

compared to costs, consistent with the Federal objective. Due to the nature of the

diversion and the analyses completed, a separable element of the NER could not be

identified. The recommended plan would have 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 (May-February).

The USACE District Commander recommends seeking additional authorization in

order to construct the recommended plan / NER plan. Alternative 4 is shown in

Figure ES-15. Table ES-10 summarizes project costs and benefits.

Recommended plan components:

Multiple box culverts with hydraulic operated sluice gates

Replacing the roadway

Construction of an outfall channel

Creation of ridge and terrace features (31 acres)

Creation of marsh from dredge material (385 acres)

The project would deliver freshwater, sediment, and nutrients and improve habitat

function by 13,355 AAHUs and achieve no-net-loss of marsh acreages during the

period of analysis (2015-2065). 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. Alternative 4

would generate 13,355 AAHUs of benefit at a estimated fully funded project cost of

$387,620,000. This alternative best meets the study objectives, is the most flexible,

and has the most robust sustainable capability against RSLR over the length of the

50-year planning horizon.

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WRDA 2007 Section 7006(e)(3) ES-42 October 2010 Figure ES-15: LCA MDWD recommended plan features (Alternative 4)

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WRDA 2007 Section 7006(e)(3) ES-43 October 2010

Table ES-10: LCA MDWD NER and Recommended Plan

Alt. 4

(Recommended

plan / NER)

AAHUs 13,355

Cost effective (Yes/No/Best Buy) Best Buy

$Annualized cost/AAHUa $1,332

Fully funded project costb $387,620,000

Authorized cost in WRDA Title VII, Section 7006

(e)(3)(A) for the LCA MDWD $86,100,000

Maximum cost limited by Section 902b $126,686,400

a Based on preliminary construction cost, not the fully funded cost

b Fully funded project cost includes inflation adjusted from the October 2006 price levels through the

projected midpoint of project construction.

Cost Sharing: Following the feasibility phase, the cost share for the planning,

design, and construction of the project as well as adaptive monitoring would be 65%

Federal and 35% non-Federal. The State of Louisiana, represented by the CPRA,

would be responsible for 100% of LERRDs cost and, following construction, the

future OMRR&R costs. Table ES-11 shows the cost sharing amounts based on the

first cost of construction.

Table ES-11: LCA MDWD Cost Sharing

Project Feature Total Cost Non-Federal Federal

% Cost % Cost

Total first cost of

constructiona $365,201,000 35 $127,820,000 65 $237,381,000

LERRD credit $494,000 100 $494,000 0 $0

Monitoring and adaptive

management $11,143,000 35 $3,900,000 65 $7,243,000

OMRR&R b $1,468,000 100 $1,468,000 0 $0

a Total first cost of construction is based on the sum of the planning, engineering, and design; construction management (i.e.

supervision and administration); LERRDs; and monitoring and adaptive management and is based on October 2010 price

levels.

b Average annual cost based on October 2010 price levels.

Public Involvement: An NOI to prepare a draft SEIS for the LCA MDWD was

published in the Federal Register in December 2008. A public scoping meeting was

held in February 2009. The Draft FS/SEIS was released to the public in May 2010,

followed by a 45-day public review period, which included a public meeting. Public

comments were received during the scoping meeting and Draft FS/SEIS public

review and have been incorporated into the report.

Coordination and Compliance: Following completion of the Final FS/SEIS, the

Assistant Secretary of the Army for Civil Works would issue a ROD concerning the

proposed action. Full compliance with statutory authorities would be accomplished

upon review of the Final FS/SEIS by appropriate agencies and the public and the

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signing of the ROD, in compliance with NEPA. The USACE has coordinated with

the USFWS, NMFS, and LDWF as per the Fish and Wildlife Coordination Act. A

coordination act letter report and biological opinion have been received and the

comments incorporated into the project plan. State certifications for coastal zone

consistency has also been received.

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 have been clarified and resolved.

They are summarized as follows:

Coordinating joint operation of the LCA MDWD and Caernarvon Diversion

Potential negative impacts to oysters from over-freshening of the basin

Converting the estuary to fresh/intermediate marsh

Creating flotant marsh that is not anchored and provides no surge protection

Direct sediment delivery with dredging from the river

Impacts to pallid sturgeon

Creating access and/or land use problems for private landowners

Determining best location to capture sediment

RSLR

Induced shoaling effects and other effects to the navigation/shipping industry

Need to seek additional authorization of project

Fishery modeling and habitat change model are currently under development

Impacts from the Deepwater Horizon oil spill

The recommended plan for this project exceeds the cost authorization for this

project. The USACE 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.

Conclusions and Recommendations: The LCA MDWD Project, Alternative 4,

recommended in this report is in the overall public interest and would work to

achieve no-net-loss of marsh acreages during the period of analysis (2015-2065).

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. Since the Alternative 4 cost exceeds the authorization

for this project, the USACE District Commander recommends seeking additional

authorization in order to construct the recommended plan / NER plan. The

recommended plan / NER plan has been determined to reasonably maximize

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ecosystem restoration benefits compared to costs, consistent with the Federal

objective. Due to the nature of the diversion and the analyses completed, an

increment of the NER could not be identified. The fully funded project cost is

estimated at $387,620,000, and this project would be cost shared by the non-Federal

sponsor, the State of Louisiana, at 35% non-Federal and 65% Federal. Additionally,

the non-Federal sponsor would be 100% responsible for the OMRR&R.

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1.0FORWARD

1.1 Introduction and Purpose

“... On the drive into town that morning I passed the Leeville

Cemetery, the one by the bridge, and was startled to see only eight

crypts still visible above the water. By my count the crumbling

remains of at least four tombs, all barely above water when I visited

here the year before, were now gone. Completely submerged. With

just ten months separating my two visits, I’m already a veteran of

Louisiana land loss...”

Excerpt from Bayou Farewell by Mike Tidwell, 2007

Louisiana’s loss of wetlands, cheniers, and barrier islands to open water is now a

well-documented fact in numerous studies and anecdotal observations. Since the

1930’s, Louisiana has lost 1,900 square miles of land (Barras et al., 1994, Barras et

al., 2003, Dunbar et al., 1992). From 1990 to 2000, approximately 24 square miles

of coastal land were lost each year.

The 2004 Louisiana Coastal Area, Ecosystem Restoration Study (LCA Report)

projected that 513 square miles of land would disappear by 2050 which included a

gain of 161 square miles from Coastal Wetlands Planning, Protection, and

Restoration Act (CWPPRA) projects (Barras et al., 2003). However, tropical storms

and hurricanes can accelerate the land loss rate. During the 2005 hurricane season,

203 square miles of land were lost (Barras, 2009), representing 40% of the

forecasted loss by the LCA Report from 2000 to 2050. Figure 1-1 shows historical

and projected Louisiana land loss.

The 2004 LCA Report summarized the land loss causes and ecosystem degradation

in coastal Louisiana (USACE, 2004a). Ten major natural and human-induced

factors have contributed to coastal land loss.

1. Barrier island degradation

2. Tropical storm events

3. Eustatic sea level change

4. Relative sea level change

5. Flood control

6. Navigation

7. Oil and gas infrastructure

8. Hypoxia

9. Saltwater intrusion

10.Sediment reduction / vertical accretion deficit

Factors 1 through 4 are natural processes or events that occur in the coastal area.

Barrier island degradation is the natural erosion of islands from wave action.

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Storms affect the coast by increasing wave erosion, saltwater intrusion during

storm surge, and vegetation removal or scouring. Eustatic sea level change is the

global change in sea level due to global temperature. Relative sea level change is

the difference between eustatic sea level change and land subsidence. Compaction

and consolidation of sediments, geologic faulting, and/or groundwater depletion lead

to land elevation decreases (subsidence). While these are natural coastal zone

processes, the ability of the ecosystems to regenerate and offset them is impacted by

the human-induced factors.

Factors 5 through 10 are human-induced factors that have changed the coastal area

directly and indirectly. Flood control systems include the construction of levees and

water-control structures along the Mississippi River and other waterways. Levees

impact the coast by reducing or eliminating the riverine influences that sustained

adjacent ecosystems through inputs of freshwater, sediment, and nutrients.

Navigation canals have provided conduits for saltwater. Oil and gas exploration

have also created a canal network. Canals allow saltwater intrusion into

freshwater habitats, and remnant dredged material berms have altered water flow

across the marsh.

Natural processes must be taken into consideration in project planning. Humaninduced factors present opportunities where change could help reverse coastal

degradation trends. The six projects included in this study examine the feasibility

of reintroducing riverine influence, removing hydrologic impediments, and restoring

form to barrier islands.

The coastal Louisiana ecosystem and resources are valuable on local, state, and

national levels. Over 2 million residents, representing 41% of Louisiana’s citizens,

live in coastal Louisiana parishes (U.S. Census Bureau, 2007). Hunting and fishing

account for a combined $2.68 billion annually in related expenditures while wildlife

watching accounts for another $517 million (LDWF, 2006a).

Louisiana’s coastal ecosystem is valuable for commercial industries and commerce.

Commercial fishing has a dockside landing value of $202 million annually and

makes up 21% of the total catch by weight in the lower 48 states. The coastal

ecosystems provide protection for waterborne commerce to 5 of the top 15 largest

ports in the United States; in 2007, those ports carried 457 million tons of cargo,

accounting for 18% of United States (U.S.) waterborne commerce (USACE, 2007).

Those same ports help supply and service energy production facilities on the

Louisiana Coast and on the outer continental shelf (OCS). Including the production

of outer continental shelf facilities, Louisiana is first in U.S. crude oil production

and second in natural gas production (LDNR, 2007).

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WRDA 2007 Section 7006(e)(3) 1-3 October 2010Figure 1-1: Historical and projected land loss in Louisiana (USGS, 2003)

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In 2004, USACE completed the LCA Report, culminating other studies that had

examined long-term solutions for preserving and restoring Louisiana ecosystems.

While large-scale, systemic restoration measures are needed to sustain coastal

ecosystems, the 2004 LCA Report was developed to identify cost effective, near-term

restoration features addressing the most critical needs of coastal Louisiana.

The 2004 LCA Report identified five critical projects, multiple programmatic

authorizations, and additional feasibility studies. This report summarizes the

feasibility studies of six near-term critical restoration features authorized in the

2007 Water Resources and Development Act (WRDA).

1.2 Louisiana Coastal Area Program

Numerous reports have documented Louisiana coastal wetlands deterioration. In

1990, CWPPRA was passed providing authorization and funding for coastal

restoration projects. The experiences from projects under CWPPRA led to the

development of the “Coast 2050: Toward a Sustainable Coastal Louisiana” report

(Coast 2050 Plan). The basis of that report was coastal restoration by mimicking

natural process on a larger scale. The Coast 2050 Plan led to a reconnaissance-level

report evaluating the plan and Federal interest in proceeding to a feasibility phase.

The feasibility phase was envisioned as multiple basin-scale studies across the coast

(LCWCRTF and WCRA, 1999).

In 2002, the feasibility study direction was changed to focus on creating a blueprint

for future comprehensive coastal restoration to submit to Congress. Concerns about

budget constraints in 2004 as well as uncertainties in science and engineering led

decision makers to conclude that restoration should begin with a plan that

identifies cost effective features addressing the most critical needs (USACE, 2004a).

The LCA Report includes the following recommended components:

1. Specific Congressional authorization for five near-term critical restoration

features for which construction can begin within 5 to 10 years, with

implementation subject to approval of feasibility-level decision documents

by the Secretary of the Army (hereinafter referred to as “conditional

authorization” in the Report and accompanying Programmatic

Environmental Impact Statement);

2. Programmatic Authorization of a Science and Technology Program;

3. Programmatic Authorization of Science and Technology Program

Demonstration Projects;

4. Programmatic Authorization for the Beneficial Use of Dredged Material;

5. Programmatic Authorization for Investigations of Modification of Existing

Structures;

6. Approval of investigations and preparation of necessary feasibility-level

reports of 10 additional near-term critical restoration features to be used

to present recommendations for potential future Congressional

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authorization (hereinafter referred to as “Congressional authorization”);

and

7. Approval of investigations for assessing six potentially promising largescale and long-term restoration concepts.

Item 6 refers to 10 additional near-term critical restoration features requiring

feasibility reports. The 6 projects summarized in this document are included in

those 10 additional projects. Under the LCA Report these proposed restoration

features employ a variety of strategies and could begin construction within the next

10 years.

1.3 Study Authority

Title VII of 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 2004 LCA Report.

Under the 2007 WRDA Section 7006, the LCA Program has authority for feasibilitylevel reports of near-term critical restoration features. The excerpt below from the

WRDA outlines the project authority for the six near-term critical restoration

features that are summarized in this comprehensive report:

SEC. 7006. CONSTRUCTI ON.

(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 Transportation and Infrastructure of the House of Representatives and the Committee on

Environment and Public Works of the Senate.

This report summarizes the integrated feasibility study (FS) and supplemental

environmental impact statement (SEIS) conducted for the six critical, near-term

restoration features. The SEIS is a supplement to the Final Programmatic

Environmental Impact Statement (FPEIS) completed for the LCA Report (USACE,

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WRDA 2007 Section 7006(e)(3) 1-6 October 2010

2004b). This report meets the requirement of Section 7006(e)(3)(A) directing the

Secretary of the Army to submit feasibility studies on six projects by December 31,

2008. Implementation of the six is authorized for construction provided a favorable

Chief of Engineers’ Report is completed no later than December 31, 2010.

1.4 Water Resources Development Act of 2007 Requirements

In November 2007, the WRDA became law authorizing an LCA Program. WRDA

2007 requirements for six projects covered in this summary include:

Submittal of a favorable Chief’s Report no later than December 31, 2010, to

the Secretary [Section 7006(e)(3)(A)]

Projects are required to be in accordance with the LCA 2004 Report and are

subject to its conditions [Section 7006(e)(3)(A)]

Preparation of the feasibility studies will be cost-shared between the Federal

and non-Federal sponsor at 50% each; implementation of the projects will be

cost-shared at 65% Federal and 35% non-Federal [Section 7006(e)(3)(A)]

Projects must be determined to be justified by the environmental benefit

derived to coastal Louisiana and be cost effective [Section 7008]

Section 7006 also required submittal of FSs to the Committee on Transportation

and Infrastructure of the House of Representatives and the Committee on

Environment and Public Works of the Senate no later than December 31, 2008, and

a favorable Chief of Engineer’s Report completed by December 31, 2010. However,

the cost-share agreement between U.S. Army Corps of Engineers (USACE) and the

Louisiana Coastal Protection and Restoration Authority (CPRA) was not signed

until November 6, 2008, a year after enactment of WRDA 2007 and less than 2

months before the first deadline. Consequently, the initial submittal did not occur;

however, the FSs will be completed and Chief’s Report prepared prior to the

December 31, 2010, deadline.

1.5 Organization of Report

WRDA 2007 included authorization under Title VII, the LCA, for feasibility-level

reports of six near-term elements. Those elements are included in Section 7006

(e)(3)(A) as projects identified for additional study. The six elements identified in

WRDA were:

Convey Atchafalaya River Water to Northern Terrebonne Marshes

Multipurpose Operation of the Houma Navigation Lock

Amite River Diversion Canal Modification

Small Diversion at Convent/Blind River

Terrebonne Basin Barrier Shoreline Restoration

Medium Diversion at White Ditch

These six elements are each required to have a FS completed. In the course of

initiating the studies, two elements were determined to be hydrologically

intertwined and the planning efforts were combined:

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Convey Atchafalaya River Water to Northern Terrebonne Marshes

Multipurpose Operation of the Houma Navigation Lock

As a result, this FS was structured in six primary volumes including this Summary

Report. This summary report (Volume I) integrates the following elements:

Amite River Diversion Canal (ARDC) Modification (Volume II)

Convey Atchafalaya River Water to Northern Terrebonne Marshes (ARTM)

and Multipurpose Operation of the Houma Navigation Lock (MOHNL)

(Volume III)

Small Diversion at Convent/Blind River (Volume IV)

Terrebonne Basin Barrier Shoreline Restoration (TBBSR) (Volume V)

Medium Diversion at White Ditch (MDWD)(Volume VI)

1.6 U.S. Army Corps of Engineers 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 Nation’s security energize

the economy and reduce risk from disasters.” This Campaign Plan shapes USACE

command priorities, focusing transformation initiatives, measuring and guiding

progress, and helps the USACE adapt to the needs of the future.

USACE Campaign Plan goals and objectives:

1. Deliver USACE support to combat, stability and disaster operations through

forward deployed and reach back capabilities.

2. Deliver enduring and essential water resource solutions through

collaboration with partners and stakeholders.

3. Deliver innovative, resilient, sustainable solutions to the Armed Forces and

the Nation.

4. Build and cultivate a competent, disciplined, and resilient team equipped to

deliver high quality solutions.

The six projects summarized in this report address two points of the USACE

Campaign Plan. The second goal of the USACE Campaign Plan is addressed by

these projects since they are an element of the LCA Report for ecosystem

restoration on the Gulf Coast. These projects also address 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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2.0INTRODUCTION AND STUDY INFORMATION

2.1 Purpose and Scope

The goal of the LCA Report was to reverse the degradation trend of the coastal

ecosystem of Louisiana. The plan that resulted from the LCA Report focused on the

restoration strategies that would:

Reintroduce historical flows of river water, nutrients, and sediments

Restore hydrology to minimize saltwater intrusion

Maintain structural integrity of coastal ecosystems

The integrated FS/SEISs presented here fulfill the original purpose of the LCA

Report since these projects were identified as critical near-term restoration projects.

The studies presented here also fulfill the goal of the LCA Report by accomplishing

the projects through the reintroduction of historical river flows, restoration of

hydrology, and maintaining structural integrity of the ecosystems.

2.2 Deepwater Horizon Oil Spill

The impacts of the Deepwater Horizon oil spill on coastal Louisiana are uncertain

at this time. 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. 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.).

2.3 Planning Process

These studies followed the six-step planning process prescribed in Engineering

Regulation (ER) 1105-2-100 “The Planning Guidance Notebook” (USACE, 2000a).

Step 1: Identifying Problems and Opportunities

Initial efforts investigated existing data from studies, plans, and projects in

the areas. Site-specific information was used to identify Study Area problems

and opportunities. Then the Project Delivery Teams (PDTs) identified

project-specific goals, objectives, and constraints.

Step 2: Inventory and Forecast

Based on the extensive literature review and field investigations, historical

and existing conditions of resources were established. Where applicable, the

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resources were quantified. Land loss data were used to extrapolate the likely

future without project scenarios for each area over a 50-year period of

analysis. The data were used to refine and further characterize the problems

and opportunities identified in Step 1.

Step 3: Formulation of Alternative Plans

Each PDT utilized the available information regarding identified problems,

opportunities, and constraints to identify a range of structural and

nonstructural measures. Combinations of the measures were used to develop

initial alternative plans. The alternative plans were screened based on their

completeness, efficiency, effectiveness, and acceptability.

Step 4: Evaluating Alternative Plans

Alternative plan benefits were analyzed by forecasting with project

conditions. Potential outputs and effects for the alternative plans were

analyzed. Beneficial and adverse effects were characterized regarding

magnitude, location, timing, and duration. A Final Alternatives Array was

identified.

Step 5: Comparing Alternative Plans

The Final Alternatives Array and a No Action Alternative were compared.

Outputs and effects were compared for the plans, including the projected

average annual habitat units (AAHUs), cost effectiveness, and the

incremental cost analysis of the plans.

Step 6: Selecting a Plan

For each of the projects a national ecosystem restoration (NER) plan and a

recommended plan were identified. The NER plan chosen was the

alternative plan that reasonably maximized the ecosystem restoration

benefits compared to cost while addressing the project objectives. In some

cases, the NER plan and recommended plan were the same plan; however, in

some cases, the NER plan exceeds the WRDA 2007 cost authorization.

Where the cost of the NER plan exceeds the 2007 WRDA authorization, a

recommended plan that was an implementable increment of the NER was

identified, if possible. As an implementable increment of the NER, the

recommended plan was still required to be cost effective, within the cost and

scope of the authorization, have stand-alone utility, and justified based on

benefits to the aquatic ecosystem.

2.3.1 Plan Formulation Rationale

Alternatives for the proposed action were formulated in consideration of each Study

Area’s 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 (USACE,

2000a). In addition, plan formulation for these six projects considered the scope of

the projects as defined in the original LCA Report and the cost authorized in WRDA

2007.

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2.3.1.1 Plan Formulation Criteria

2.3.1.1.1 Completeness

Completeness is the extent that an alternative provides and accounts for all

investments and actions required to ensure the planned output is achieved. This

criterion 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, operations and

maintenance (O&M), monitoring, and sponsorship factors. Adaptive management

plans formulated to address project uncertainties also have to be considered.

2.3.1.1.2 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.

2.3.1.1.3 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.

2.3.1.1.4 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.

2.3.1.2 Environmental Operating Principles

In 2002, the USACE formalized a set of Environmental Operating Principles (EOPs)

applicable to decision-making in all programs. The principles are consistent with

the National Environmental Policy Act (NEPA), the Army Strategy for the

Environment, other environmental statutes, and the WRDAs that govern USACE

activities.

The USACE EOPs are as follow:

1. Strive to achieve environmental sustainability, and recognize that an

environment maintained in a healthy, diverse, and sustainable condition is

necessary to support life.

2. Recognize the interdependence of life and the physical environment, and

proactively consider environmental consequences of USACE programs and

act accordingly in all appropriate circumstances.

3. Seek balance and synergy among human development activities and natural

systems by designing economic and environmental solutions that support and

reinforce one another.

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4. 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.

5. 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.

6. Build and share an integrated scientific, economic, and social knowledge base

that supports a greater understanding of the environment and impacts of our

work.

7. 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 Nation’s problems that also protect and

enhance the environment.

The EOPs inform the plan formulation process and were integrated into the project

management processes. Sustainability is a critical issue for the LCA and all

projects were analyzed regarding the sustainability of the chosen plan and the

sustainability of benefits from the projects over the period of analysis.

Environmental and socioeconomic consequences were analyzed for all alternative

plans during the comparisons of alternatives. The project effects, both positive and

negative, were also considered during plan selection.

Consistent with the EOPs, the goal of these projects is to reverse the trend of

coastal degradation that has occurred, in part, due to the cumulative impacts of

human-induced factors. Through the reintroduction of natural processes or the

restoration of hydrology or structure, these projects will help reverse the coastal

degradation. Lessons learned through the study and construction of these projects

as well as information that will be gathered during the monitoring and adaptive

management will add to the database of existing knowledge about coastal

restoration in Louisiana.

These projects have been untaken with the non-Federal sponsor and have been

informed by the initial feasibility scoping meeting. Public review of the FS/SEIS

reports occurred in June and July 2010. Information and comments obtained from

the public, interested nongovernmental organizations (NGOs), and other agencies

have been incorporated into the project plan formulation.

2.4 National Objectives

The USACE planning process is based on the economic and environmental

Principals and Guidelines (P&G). 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 output,

NER output, or a combination of NED/NER output.

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The LCA Report projects are ecosystem restoration projects, and the project benefits

are quantified as NER output. 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. For these six conditionally authorized projects, the NER

was measured as AAHUs.

2.5 Study Areas

Each project has a defined Study Area, which includes locations of any structures

included in the plans as well as the area that will benefit from the planned project.

LCA subprovinces are shown in Figure 2-1, and the Study Area for each project is

shown in Figure 2-2.

2.5.1 Amite River Diversion Canal Modification

The LCA ARDC Modification Study Area is located approximately 28 miles

southeast of the city of Baton Rouge and west of Lake Maurepas. The project area

is within LCA Subprovince 1 in the Lake Pontchartrain Basin and the Upper Lake

Figure 2-1: LCA subprovinces (USACE, 2004a)

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Pontchartrain Sub-basin. The Upper Lake Pontchartrain Sub-basin, located

northwest of Lake Pontchartrain, includes Lake Maurepas, Maurepas Swamp,

Blind River, and portions of the Amite River. ARDC is located north of the LCA

Small Diversion at Blind River (see Figure 2-2).

The ARDC flows through the western portion of Maurepas Swamp. The Study Area

for this project is composed of some developed areas but is mostly undeveloped

wetland areas. Several wetland habitat types exist in the area, including cypresstupelo forest, marsh, and scrub shrub. Cypress-tupelo forests make up the majority

of the area.

Authorization of the Amite River and Tributaries (AR&T) flood control project in

1956 included construction of the ARDC. Construction of the canal included

placement of dredged material along the canal banks. The dredged material berms

have altered the hydrology of the Study Area by isolating portions of Maurepas

Swamp from the ARDC. Consequently, the adjacent cypress-tupelo swamps are

prevented from receiving floodwater during high channel flow and are unable to

drain during low channel flows.

2.5.2 Convey Atchafalaya River Water to Northern Terrebonne Marshes

and Multipurpose Operation of Houma Navigation Lock

The LCA ARTM and MOHNL Study Area is located mostly east of Morgan City,

south of Houma, and south of LaRose. These two projects were hydrologically

intertwined and consequently were combined for analysis; the combined project is

referred to as the LCA ARTM Project. As shown in Figure 2-2, the Study Area is

bordered on the west by the Lower Atchafalaya River, on the north by the Bayou

Black Ridge, and to the east by the Bayou Lafourche Ridge. At 1,100 square miles,

it encompasses a large area within LCA Subprovince 3.

Much of the Study Area is dominated by herbaceous wetlands, including freshwater

marsh, intermediate marsh, brackish marsh, and saline marsh. The Study Area

also includes significant areas of open water and a small amount of swamp. This

project is bordered by the LCA TBBSR Study Area to the south.

This area of coastal wetlands provides an essential place for migratory birds to rest

and feed during spring and fall migrations. The Study Area shelters various

threatened and endangered wildlife and provides storm protection for Houma,

Morgan City, and LaRose in addition to other communities. This area has

undergone significant deterioration of the wetland habitats through the process of

subsidence, lack of sediment and nutrients, erosion by tidal exchange,

channelization, and saltwater intrusion.

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2.5.3 Small Diversion at Convent/Blind River

The LCA Convent/Blind River Diversion Study Area is located approximately

halfway between the cities of New Orleans and Baton Rouge between the

Mississippi River and Lake Maurepas. The project area is within LCA Subprovince

1 in the Lake Pontchartrain Basin and the Upper Lake Pontchartrain Sub-basin.

The Upper Lake Pontchartrain Sub-basin, located northwest of Lake Pontchartrain,

includes Lake Maurepas, Maurepas Swamp, Blind River, and portions of the Amite

River. This projected is located south of the LCA ARDC Modification Project (see

Figure 2-2).

Convent is a small, unincorporated community along the Mississippi River located

south of Romeville, Louisiana. Blind River begins east of the Mississippi River,

near Convent, and flows north-northwest until it intersects with the Petite Amite

River and eventually flows into Lake Maurepas. The swamp includes a variety of

wetlands habitats, including bottomland hardwoods in drier areas, cypress-tupelo

swamps, and marsh. The Maurepas Swamp is one of the largest remaining tracts of

coastal freshwater swamp in Louisiana.

Hydrologic flow in this area was originally influenced by seasonal overbank events

from the Mississippi River, which would then flow down Blind River and through

Maurepas Swamp. Flows and water levels in the Study Area differ substantially

from historical conditions due to isolation from Mississippi River floods in

conjunction with further human modifications. Lack of freshwater, nutrients, and

sediments contribute to the continued loss of vegetated wetland habitats, including

loss of bald cypress-tupelo and bottomland hardwood resources, increased saltwater

intrusion, increased flood duration and impoundment, and increased herbivory.

2.5.4 Terrebonne Basin Barrier Shoreline Restoration

The LCA TBBSR Study Area is located approximately 36 miles south of Houma,

Louisiana, and 5 miles west of Port Fourchon. The project is located in LCA

Subprovince 3 and includes the Timbalier and Isles Dernieres Barrier Island

reaches located at the seaward edge of the subprovince. The subject islands are

located in Terrebonne and Lafourche Parishes, Louisiana.

Isles Dernieres includes a barrier island arc approximately 22 miles long that

extends from Caillou Bay in the east to Cat Island Pass in the west. The islands in

the chain include Raccoon, Whiskey, Trinity, East, and Wine. The islands range

from 0.1 to 0.85 miles wide, and typical composition is a thin sand cap over a thick

mud platform. They have low elevation and are frequently overwashed (USACE,

2004a). Isles Dernieres is located west of the Timbalier Reach.

The Timbalier Reach includes Timbalier Island and East Timbalier Island, which

are on the western edge of Lafourche Parish. This barrier island reach is

approximately 20 miles long from Raccoon Pass to the east to Cat Island Pass in the

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west. The islands are 0.1 to 0.6 miles wide with low elevation. Oil and gas canals

are present on both islands. The Timbalier Reach is located east of the Isles

Dernieres (USACE, 2004a).

Man-made and natural processes have resulted in reduced sediment in the barrier

island system. Consequently, the barrier islands are disappearing.

2.5.5 Medium Diversion at White Ditch

The LCA MDWD Study Area is located near Phoenix, Louisiana, which is

approximately 23 miles south-southeast of the city of New Orleans along the

Mississippi River and includes the Breton Sound area. The MDWD project Study

Area is located in LCA Subprovince 1 in the Breton Sound hydrologic basin in

Plaquemines Parish, Louisiana, on the east bank of the Mississippi River. The

Caernarvon Diversion is located at the northern end of the Breton Sound Basin;

however, the Study Area is isolated from the effects of that diversion. The Myrtle

Grove Diversion Project is located on the west bank of the Mississippi River near

the Study Area and will affect areas south and west of the Mississippi River.

The east bank of the Mississippi River includes some developed areas, including the

settlements of Phoenix, Harlem, and Davant. The Study Area is dominated by over

98,000 acres of herbaceous wetlands, including freshwater marsh, intermediate

marsh, brackish marsh, and saline marsh. Some bottomland hardwood areas are

also present at higher elevations.

Hydrologic flow in the Study Area was originally down the River aux Chenes (Oak

River), small bayous, and as sheet flow across the marsh toward the Gulf of Mexico.

The River aux Chenes originally was a crevasse of the Mississippi River and

provided an outlet for flooding events from the Mississippi River. Currently, the

Mississippi River Levee prevents flooding events from reaching the river, and the

construction of oil and gas canals throughout the Study Area has further altered the

hydrology. Hydrologic impacts have enabled salt water intrusion farther into the

system, and lack of sediments has exacerbated subsidence issues.

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3.0AMITE RIVER DIVERSION CANAL MODIFICATION

3.1 Purpose and Scope*

This is a summary of the FS/SEIS for the LCA ARDC Modification Project (Volume

II). In the original LCA Report (USACE, 2004a), this project was referred to as

“Increase Amite River Diversion Canal Influence by Gapping Banks.”

The LCA ARDC Modification Project was proposed to reverse the current decline of

swamp in western Maurepas Swamp and prevent transition of the swamp to

freshwater marsh and open water. This study evaluates different methods for

establishing hydrologic connectivity between the ARDC and the adjacent swamp,

allowing the swamp to drain during seasonal low-flow conditions in the ARDC and

promoting the germination and survival of the seedlings of bald cypress and other

trees. This connectivity would also allow nutrients and sediments to be introduced

from the ARDC into the adjacent swamp during flood events and from runoff during

localized rainfall events. Nutrients and sediment delivered to the swamp would

improve biological productivity. Finally, the establishment of hydrologic

connectivity would reduce the likelihood of the swamp converting to marsh or open

water. Reversing this decline would help develop more sustainable ecosystems,

which can serve to protect the local environment, economy, and culture.

This project would complement, but is independent of, two other proposed LCA

projects (LCA Small Diversion at Hope Canal and LCA Small Diversion at

Convent/Blind River) and two proposed Coastal Impact Assistance Program (CIAP)

projects (Hydrologic Restoration in Swamps West of Lake Maurepas and Bald

Cypress/Tupelo Coastal Forest Protection). The LCA ARDC Modification PDT

coordinated with the staff of these other projects to identify all known interactions

between projects.

The environmental consequences of the proposed project are evaluated in Volume

II, Section 5 and are summarized here. The integrated NEPA documentation and

SEIS is a supplement to the Final Programmatic Environmental Impact Statement,

LCA Report (FPEIS) (USACE, 2004b). The Record of Decision (ROD) for the FPEIS

was signed on November 18, 2005. The FPEIS is incorporated by reference.

3.1.1 Study Area Background*

In the 1950s, in an effort to relieve flooding along the upper Amite River, the ARDC

was constructed to enhance the flow of water from the meandering Amite River to

Lake Maurepas. The 10.6-mile long canal is 300 feet (ft) wide and was dug to a

depth of 25 ft. The Study Area (Figure 3-1, Table 3-1) is located in LCA

Subprovince 1 and is situated along the ARDC in Ascension and Livingston

parishes, in the vicinity of Head of Island, Louisiana (USACE, 2004a).

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Table 3-1: Hydrologic Subunits

Hydrologic

Subunit Acres Description

NW-1 2,332

This subunit is one of the healthier portions of the western Maurepas

Swamp and is connected hydrologically by Bayou Pierre and the Amite

River. This area also contains an extensive housing development. It is

surrounded by Old River to the north, the ARDC to the south, and a

developed natural ridge to the east.

NW-2 4,289

This subunit contains the healthiest portion of the western Maurepas

Swamp. It is surrounded by Old River to the north, the ARDC to the

south, a developed natural ridge to the west, and a natural ridge to the

east. It is connected hydrologically by Old River and the Petite Amite

River.

NE-1 3,351

This subunit exhibits some degradation and has little to no hydrologic

connectivity with the ARDC, but is hydrologically connected by Bayou

Chene Blanc and the Chinquapin Canal. The subunit is surrounded by the

Chinquapin Canal to the north, the ARDC to the south, an abandoned

railroad embankment to the east, and an undeveloped natural ridge to the

west.

NE-2 2,309

This subunit has a high degree of habitat degradation and has little to no

hydrologic connectivity with the ARDC. The subunit is surrounded by the

Chinquapin Canal to the north, an abandoned railroad embankment to the

west, the ARDC to the south, and Little Bayou Chene Blanc and Blind

River to the east. This subunit is highly degraded and is one of the areas

in most need of restoration.

NE-3 358

This subunit has some degree of habitat degradation and is hydrologically

connected by Bayou Chene Blanc, Little Bayou Chene Blanc. A portion of

Blind River, which is hydrologically connected to this subunit as well,

borders to the south.

SW-1 1,300

This subunit contains a series of culverts that provide hydrologic

connectivity between the swamp and the ARDC and is one of the healthier

portions of the western Maurepas Swamp. The subunit is bordered by the

ARDC to the north and natural ridges to the south and west.

SW-2 8,106

This subunit appears to have some areas of degradation along with some

areas of healthy swamp. The subunit is hydrologically connected by the

Petite Amite River to the east and New River Canal to the south. It is also

bordered by the ARDC to the north, and a developed natural ridge to the

west.

SE-1 4,875

This subunit exhibits some degradation, mainly due to the lack of

freshwater, sediment, and nutrient input caused by the ARDC dredged

material berms. This subunit is hydrologically connected by Blind River on

the south and the Petite Amite River to the west side. This subunit is

bordered by the ARDC to the north and an abandoned railroad

embankment to the east.

SE-2 1,062

This subunit exhibits some degradation, mainly due to the lack of

freshwater, sediment, and nutrient input caused by the ARDC dredged

material berms. The subunit is surrounded by the ARDC to the north, an

abandoned railroad embankment to the west, and Blind River to the east.

This subunit is highly degraded and is one the areas in most need of

restoration.

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The Study Area is bounded to the north by the old channel of the Amite River, Old

River, Chinquapin Canal and Bayou Chene Blanc; to the east by the Blind River; to

the south by the Petite Amite River and the New River Canal; and to the west by

the Sevario Canal, Ascension Parish flood protection levees, and the Laurel Ridge

Canal.

For planning purposes, the Study Area has been divided into nine separate

hydrologic subunits. Each subunit was developed based on natural and man-made

hydrologic boundaries.

3.1.1.1 Study Area Significance

Louisiana contains one of the largest expanses of coastal wetlands in the contiguous

United States. The Maurepas Swamp complex is the second largest continuous

coastal forest in Louisiana, comprising over 190,000 acres of freshwater swamp

habitat. The Study Area is an essential ecosystem since it includes wetland

habitats and provides high fish and wildlife value as well as habitat for migratory

birds and other aquatic organisms, including threatened or endangered species.

The restoration of the freshwater swamp habitat surrounding the ARDC would

protect these national assets from further degradation. The restoration and

protection of this swamp system would further protect the human infrastructure

from the damages of storm surges.

3.1.2 History of Investigation

The USACE and the State of Louisiana initiated the LCA Report to coordinate the

separate ecosystem restoration studies for coastal Louisiana. In fiscal year (FY)

2004, recognition of Federal and state funding constraints and scientific and

engineering uncertainties pertaining to some of the restoration features under

consideration led to the determination that the coastal area ecosystem restoration

effort should begin with the development and implementation of a restoration plan

that identifies highly cost effective restoration features that address the most

critical needs of coastal Louisiana, as well as large-scale and long-term restoration

concepts. The resulting near-term restoration plan was released in 2004 as the

LCA Report. This project was identified in the 2004 LCA Report and authorized by

WRDA 2007. Other reports and plans that led to the development of the LCA

Report are described in Volume II.

In November 2008, the USACE and the State of Louisiana, represented through

CPRA, executed a single Feasibility Cost-Share Agreement covering the six LCA

near-term plan projects listed in Section 7006(e)(3) of the WRDA 2007. Each of the

six features underwent a separate feasibility analysis and environmental

compliance review. This is a summary of the feasibility analysis and environmental

compliance review completed for the LCA ARDC Modification Project.

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This study is designed to address ecosystem restoration problems and opportunities

in the LCA ARDC Modification Study Area. These have been documented since

1998 through numerous comprehensive planning studies. Specifically, this study

builds upon the following comprehensive planning efforts for the LCA which are

discussed further in the FS/SEIS (Volume II):

Coast 2050 Plan (LCWCRTF and WCRA, 1999)

LCA Report (USACE, 2004a)

Louisiana Coastal Protection and Restoration Report (USACE, 2009c)

Integrated Ecosystem Restoration and Hurricane Protection: Louisiana’s

Comprehensive Master Plan for a Sustainable Coast (LACPR, 2007)

3.1.3 Prior Reports and Existing Projects

A number of prior water resources development efforts are relevant to the LCA

Program. These efforts, along with the comprehensive planning studies in the

FS/SEIS, are listed in Table 3-2 and further described in Volume II.

Planning for this project utilizes data from these previous reports and studies.

Specifically, alternative plans for this study were formulated based upon the 2004

LCA Report and the project description contained within that report. Several other

existing and authorized navigation, flood control, and coastal restoration projects

are specifically related to the study. These projects are also briefly described below.

Table 3-2: Relevance of Prior Studies, Reports, Programs, and Water

Projects to the LCA ARDC Modification Integrated FS/SEIS

Prior Studies, Reports, Programs, and Water

Projects

Relevance to LCA ARDC

Data Source

Consistency

Structural

Measures

NonStructural

Measures

Future

Without

Project

Condition

Comprehensive Planning Studies

Coast 2050 Plan, 1999 X X X

LCA Report, 2004 X X X X X

Louisiana’s Comprehensive Master Plan for a Sustainable

Coast, 2007 X XXX X

LACPR, 2009 X X X

Prior Studies, Reports, and Water Projects

Prior studies and reports incorporated by reference X X X

Amite River and Bayou Manchac, 1928 X X X

Mississippi River &Tributaries (MR&T), 1928 X X X

AR&T, 1956 X X X

Comite River Diversion X X X

LCA Small Diversion at Hope Canal (1,000 – 5,000 cfs) X X X X X

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Prior Studies, Reports, Programs, and Water

Projects

Relevance to LCA ARDC

Data Source

Consistency

Structural

Measures

NonStructural

Measures

Future

Without

Project

Condition

LCA Small Diversion at Convent/Blind River (1,000 –

5,000 cfs) X XXX X

Hydrologic Restoration in Swamps West of Lake Maurepas X X X X X

Bald Cypress/Tupelo Coastal Forest, Pontchartrain Basin X X X X X

CWPPRA projects authorized for design X X X X X

Related Laws and Programs

Louisiana Coastal Management Program, 2008 X X

Louisiana Coastal Wetlands Conservation, Restoration

and Management Act, 1989 X X

CWPPRA, 1990 X X X X X

CIAP, 2001 and 2005 X X X X X

Act 8 of the First Extraordinary Session of 2005 X X

Various plans and programs of NGOs X X X X

Note: cfs = cubic feet per second

AR&T, 1956: The ARDC was authorized by Congress in 1956 as a component of

the AR&T Federal flood control project. The ARDC was constructed from mile 25.3

of the Amite River to mile 4.8 of the Blind River. The ARDC is 10.6 miles long, 300

ft wide, and was originally dredged to 25 ft deep. The ARDC is connected to the

Amite River by a control weir at French Settlement that was designed to retain low

flows in the Amite River. A small navigation channel through the control weir

allows small boats to pass to and from the Amite River and the ARDC.

Maintenance of portions of the AR&T within their respective boundaries is the

responsibility of the Ascension and Livingston Parish police juries and the East

Baton Rouge Parish Council. No dredging activities have occurred in the ARDC

since its construction. Construction of this project was initiated in 1957 and

completed in 1964. The dredged material berms created alongside the ARDC as a

result of this project provide interference with natural hydrologic exchange within

the LCA ARDC Modification Study Area.

LCA Report, 2004: In 2000, the USACE and State of Louisiana initiated the LCA

Report to address Louisiana’s severe coastal land loss problem. In 2004, the LCA

Report was completed; it identified various projects across the coastal area of

Louisiana to address the most critical needs. This project was formulated to

address this description and scope. The report described the LCA ARDC

Modification Project as follows:

Increase Amite River Diversion Canal influence by gapping banks. This

restoration feature involves the construction of gaps in the existing dredged

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material banks of the ARDC. The objective of this feature is to allow

floodwaters to introduce additional nutrients and sediment into western

Maurepas Swamp. The exchange of flow would occur during flood events on

the river and from the runoff of localized rainfall events. This feature would

provide nutrients and sediment to facilitate organic deposition in the swamp,

improve biological productivity, and prevent further swamp deterioration

(USACE, 2004a).

Other projects included in the LCA Report that are near the LCA ARDC

Modification are shown in Figure 3-2 and include the following (USACE, 2004a):

LCA Small Diversion at Hope Canal: The LCA Small Diversion at Hope

Canal is located east of the project. The LCA Small Diversion at Hope Canal

consists of diverting approximately 1,500 cfs from the Mississippi River into

the Hope Canal at Garyville. The Hope Canal will be improved, and water

management features will be included to distribute the flow into the

Maurepas Swamp. The project service area is approximately 36,000 acres

(56.25 square miles). The project is being investigated under the CWPPRA

program.

This project will benefit a different portion of the Maurepas Swamp than the

LCA ARDC Modification Project. Both of the projects are independent but

their effects will be additive in restoring the swamp.

LCA Small Diversion at Convent/Blind River: The LCA Small Diversion

at Convent/Blind River project is located south of the Study Area and is

described in Section 5.0 of this report. The LCA Small Diversion at

Convent/Blind River project consists of diverting approximately 1,000–5,000

cfs from the Mississippi River into the Blind River and the Maurepas Swamp.

The objective of this feature is to introduce sediment and nutrients into the

swamp to reverse swamp decline in that area.

The LCA ARDC Modification Project will restore a different portion of the

Maurepas Swamp than the LCA Small Diversion at Convent/Blind River

Project. The Study Areas for both projects are hydrologically independent;

therefore any proposed actions would not result in ecosystem benefits or

impacts between the two projects. The LCA ARDC Modification Project will

add to the restoration benefits of the LCA Small Diversion at Convent/Blind

River and Small Diversion at Hope Canal Projects. All projects will aid in

restoring the second largest stand of continuous swamp in Louisiana.

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Figure 3-2: Related LCA projects near the Study Area

CIAP Projects, 2008: The Energy Policy Act of 2005 was signed into law on

August 8, 2005. Section 384 of the Act established the CIAP, which authorizes funds

to be distributed to OCS oil and gas producing states to mitigate the impacts of OCS

oil and gas activities. CIAP projects located within or near the Study Area include

the following:

Hydrologic Restoration in Swamps West of Lake Maurepas: This

proposed project would be located within portions of the LCA ARDC

Modification project study area. The CIAP project received study funding in

September 2010 to begin design but has not yet been awarded construction

funding. The CIAP project proposes to facilitate water exchange between the

ARDC and portions of the adjacent Maurepas Swamp. Additionally, the

project proposes to facilitate better hydraulic conductivity between portions of

the interior Maurepas Swamp and the ARDC. The LCA ARDC Modification

project PDT, the CIAP project team, and representatives of Livingston Parish

have coordinated these separate efforts to ensure that implementation of the

proposed CIAP project and the LCA ARDC Modification project would result

in the maximum benefits for the Maurepas Swamp area. Based on the

aforementioned coordination, once the CIAP project is authorized for

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construction funding, the actions proposed by this project will represent a

separate effort from the actions recommended by the LCA ARDC

Modification project. To date no formal request for the use of CIAP funds as

a cost share for this project has been made. Proposed study area is shown in

Figure 3-2.

Bald Cypress/Tupelo Coastal Forest, Pontchartrain Basin: This

proposed CIAP project would be located nearby the LCA ARDC study area.

The project proposes to purchase a portion of the existing bald cypress-tupelo

swamp in the western Maurepas Swamp northeast of the study area to

protect the habitat from future logging. This CIAP project was awarded

funding for initial work including land appraisal and legal documents

however has not yet been awarded final funding to acquire land.

3.2 Need for and Objectives of Action*

3.2.1 Public Concerns

Public input was received through coordination with the local sponsor, coordination

with other agencies, public review of draft and interim products, workshops, and

public meetings. A NEPA scoping meeting was held on February 12, 2009, in

French Settlement, Louisiana, at which the LCA Report, the NEPA process and

milestones, an overview of the study goals and objectives, and maps of the Study

Area were presented. Overall, the public has expressed its general approval and

support for the LCA ARDC Modification Project. A discussion of public involvement

is included in the FS/SEIS (Volume II), Section 6, Public Involvement, Review and

Consultation.

The Integrated Draft FS / SEIS was released to the public on May 21, 2010; the

release was followed by a 45-day public review period ending on July 6, 2010. A

public meeting was held on June 24, 2010, in French Settlement, Louisiana.

Comments received and the responses to them are included in Appendix G of

Volume II.

3.2.2 Problems, Needs, and Opportunities*

Study Area Problems and Needs

The primary problem within the LCA ARDC Modification Study Area is ecosystem

degradation of the freshwater swamps adjacent to the ARDC. During construction

of the ARDC, material dredged from the ARDC was deposited along the canal

banks, thereby disturbing the natural hydrology within the area. Hydrology was

also modified by the construction of the railroad grade during the 1800s. The

material dredged and deposited along the ARDC and the railroad grade are barriers

between the ARDC and the adjacent ecosystems and have resulted in impoundment

of the swamp leading to semi-permanent ponding in areas. Sea level rise and

geological subsidence have compounded the effects of these modifications (Gornitz

et al., 1982). The modification of the hydrology within the Study Area has led to

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hydrologic isolation; impoundment of water including storm surge-related, higher

salinity water; and lack of freshwater, sediment, and nutrient inputs, all of which

have contributed to the degradation and conversion of the freshwater swamps to

marsh and open water habitats.

Study Area Opportunities

Opportunities have been identified to improve habitat conditions and address many

of the problems identified in the Study Area:

Improve the hydrologic processes impaired by dredged material berm

construction, including connectivity, sheet flow, and freshwater nutrient

inflow and outflow;

Prevent future bald cypress swamp degradation and transition currently

predicted to occur;

Improve areas that have been degraded and transitioned to freshwater

marsh or open water; and

Protect vital socioeconomic and public resources.

3.2.3 Planning Objectives

Study goals, objectives, and constraints were developed to comply with the study

authority and to respond to Study Area problems and opportunities. The objectives

identified in 2004 and further investigation of the problems and opportunities in the

Study Area led to the establishment of the following planning objectives.

Increase hydrologic connectivity between the degraded swamp and

bottomland hardwood habitats within the Study Area and the ARDC by

increasing the exchange of freshwater, sediments, and nutrients over the 50-

year period of analysis.

Reduce habitat conversion of swamp to open water within the Study Area

over the 50-year period of analysis.

Facilitate natural hydrologic cycle within the Study Area over the 50-year

period of analysis by reducing impoundment in degraded swamp and

bottomland hardwood habitats adjacent to the ARDC to improve tree

productivity and seedling germination.

Improve fish and wildlife habitat within the Study Area over the 50-year

period of analysis.

Performance measures and desired outcomes to determine project success in

meeting these project objectives have been developed and are presented later in this

summary in Section 3.4.8.5.2 and in Volume II, Appendix I of the FS/EIS.

3.2.4 Planning Constraints

Development and evaluation of restoration alternatives for the proposed project are

constrained by a number of factors:

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Flood control: The ARDC is a component of the AR&T. Project plans must

not significantly decrease the performance and original intent of the ARDC

and the AR&T project.

Designated scenic rivers: Blind River, located on the perimeter of the

Study Area, is a state-designated Scenic River and protected by a set of use

restrictions.

Hydroperiod: Water levels within the ARDC exhibit seasonal high channel

flow and low channel flow intervals. Project design must function under a

variety of flow regimes.

Other items that were taken into consideration during plan development and plan

selections:

Drainage infrastructure: Existing drainage infrastructure within or

adjacent to the Study Area, such as culverts and canals, performs the vital

function of conveying excess water out of the area during heavy rainfall or

flood events. To minimize flooding, project design should not impair the

capacity of the existing drainage system.

Recreation: Minimize disruption of existing recreational use of the area and

ARDC vessel traffic to the extent practicable.

Existing development: This existing development along portions of the

ARDC dredge material berms will be considered as implementation of a

project in these areas would require the demolition and replacement of

certain residential structures and recreational facilities.

Water quality: Planning objectives of the proposed project include the

periodic draining of the swamp during low-flow intervals in the channel and

flushing the adjacent habitat during high-flow intervals. Previous studies

have indicated that swamps may release phosphorus sequestered within

their substrates when subjected to a freshwater reintroduction. Development

of a project design that minimizes potential negative impacts to downstream

water quality is recommended.

3.3 Existing and Future Without Project Condition *

This section described the existing and future without project conditions of the

Study Area as they relate to plan formulation and development of alternative

projects. Information regarding the existing condition was obtained from the

“Affected Environment” section of the FS/SEIS and information regarding the

future without project condition was obtained from the “Environmental

Consequences” Section of Volume II.

3.3.1 Existing Condition

3.3.1.1 Location

The Study Area is located in the southeastern portion of Louisiana, approximately

30 miles southeast of Baton Rouge, Louisiana, west of Lake Maurepas. The Study

Area for this project is composed of some developed areas but is mostly undeveloped

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wetland areas. Several wetlands habitat types exist in the area, including cypresstupelo forest, marsh, and scrub shrub. Cypress-tupelo forests make up the majority

of the Study Area.

3.3.1.2 Climate

The climate of the 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, bays, lakes, and the Gulf of Mexico and seasonal changes in

atmospheric circulation.

The Study Area is susceptible to tropical waves, tropical depressions, tropical

storms, and hurricanes. Historical data from 1899 to 2008 indicate that 31

hurricanes and 41 tropical storms made landfall along the Louisiana coastline

during this period (NOAA, 2009b). The 2005 hurricane season brought the most

substantial hurricane damage to the region in recent history, with the arrival of

Hurricanes Katrina and Rita. While much smaller and less intense, Hurricanes

Gustav and Ike brought additional damage to the region in 2008. While there was

extensive land loss due to the storms in parts of coastal Louisiana, negligible

wetland losses were detected for the Study Area (Wicker, 1980; Barras et al., 1994;

Barras et al., 2003; Morton et al., 2005).

3.3.1.3 Geomorphic and Physiographic Setting

The Study Area is located in the Maurepas Basin, a component of the Lake

Pontchartrain Basin, which is near the southern terminus of the Mississippi

Alluvial Plain physical province. The most significant geologic features in the basin

are Lakes Maurepas and Pontchartrain. These lakes occupy a portion of the St.

Bernard Delta complex, one of the oldest deltaic complexes within the Mississippi

Deltaic Plain Region. The St. Bernard Delta complex formed in what was then

Pontchartrain Bay, enclosing a portion of the bay to form Lake Pontchartrain

between 700 and 4,700 years ago. The majority of the remaining surface features

within the St. Bernard Delta complex are composed of inland swamp, tidal

channels, shallow lakes and bays, natural levee ridges along active and abandoned

distributaries, sandy barrier islands, and beaches.

Construction of the AR&T flood control project, which includes the ARDC, has

impacted the natural geomorphology and hydrology of the St. Bernard Delta

complex. Hydrologic analyses within the Study Area indicate that the ARDC and

its associated dredged material berms have hydrologically isolated the Study Area,

thereby preventing the adjacent bald cypress-tupelo swamp habitat from receiving

nutrient and sediment-laden floodwaters during high channel flow events and have

prevented the adjacent swamps from draining during low channel flow events in the

lower Amite River system.

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3.3.1.4 Soils

National Resource Council (NRC) data indicate that 19 soil types are found within

the Study Area. Soils are typically hydric clays or mucks that are frequently or

continuously flooded (NRCS, 1976; NRCS, 1971). Soils in the Barbary series

comprise a majority (62%) of the Study Area, and substantial quantities of soils

within the Maurepas series (12%) are also present.

Soil loss is continuing, particularly in the Barbary, Fausse, and Maurepas soils.

Due to loss of hydrologic connectivity causing degradation and decreased

productivity, soil accretion is insufficient to offset regional subsidence; consequently

the degraded swamp habitat is susceptible to conversion to freshwater marsh or

open water. According to guidance from Engineering Circular (EC) 1165-2-211, the

subsidence rate for the Study Area has been calculated to be 7.5 millimeters per

year (mm/yr) (USACE, 2009a).

3.3.1.5 Water Bottoms

Water bottoms in the Study Area are associated with the existing waterways and

channels, including the ARDC, bayous, canals, and creeks, and in open water areas

within the swamp. Portions of the swamp are impounded by dredged material

berms along the ARDC and maintain higher-than-normal water levels.

3.3.1.6 Hydraulics and Hydrology

The principal hydrologic influence on the Lake Maurepas watershed of the

Pontchartrain Basin is Lake Maurepas. Surface water flow within the basin is

generally from west to east to Lake Maurepas during normal conditions. However,

strong east winds can push water from Lakes Pontchartrain and Maurepas into the

Lower Amite River system (Hsu et al., 1997). Principal surface flow conduits

include the ARDC, the Amite River, Petite Amite River, and Blind River, into which

the flow from other water bodies is ultimately received and conveyed to Lake

Maurepas. From Lake Maurepas, surface waters are conveyed eastward through

Pass Manchac, North Pass, or gaps in the Manchac Land Bridge to Lake

Pontchartrain, from which they are conveyed eastward to the Gulf of Mexico via

Chef Menteur Pass or the Rigolets and Lake Borgne.

The swamp habitat along the left descending (north) bank of the ARDC in subunits

NE-1 and NE-2 is impounded (Shaffer et al., 2006). In a 2006 study, water levels

within this area never receded below 2.2 ft above sea level, even during periods in

which water levels within the canal receded below this level.

Within the eastern portion of the Study Area, the swamps adjacent to the right

descending (south) bank of the ARDC exhibit a lack of hydrologic connectivity. The

resulting lack of water flow between the ARDC and the adjacent swamp inhibits the

exchange of sediments and nutrients within the swamp, which is vital to tree

regeneration and growth.

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Swamp impoundment does not appear to occur in the western portion of the Study

Area. Numerous drainage culverts occur within the dredged material berms in the

northwestern portion of the study area within subunits NW-1 and SW-1.

Additionally, several small gaps were constructed in the dredged material berms,

and the confluence of Bayou Pierre with the ARDC provides additional hydrologic

exchange. Most of these hydrologic conduits are located northwest of the Louisiana

(LA) Highway 22 Bridge.

Sea level rise: Eustatic sea level refers to the global fluctuations in sea level

primarily due to changes in the volume of major ice caps and glaciers, and

expansion or contraction of seawater in response to temperature changes. Past

studies based on worldwide tide gauges estimate the rate of eustatic sea level rise at

1.2 mm/yr (Gornitz et al., 1982). Additional studies have estimated sea level rise

between 3 and 5 mm/yr (Penland et al., 1990). More recent studies have predicted

an increase in this rate to 1.7 mm/yr for the next 100 years due to climate change

(USACE, 2009b). Section 3.3.2.3 in this summary includes more information on sea

level rise in the future.

3.3.1.7 Sedimentation and Erosion

The Blind River, which bounds the Study Area to the southeast, is listed on the

2006 303(d) list of impaired water bodies as being impaired by excess sediments

from the source to the outfall at Lake Maurepas (LDEQ, 2006). Sediment Total

Maximum Daily Loads (TMDLs), as well as a nutrient TMDLs, are being required

by the U.S. Environmental Protection Agency (USEPA) to be developed by 2011 for

the Blind River.

To date, a limited amount of sediment samples within the ARDC and other water

bodies in the area (proximal upstream water bodies) have been collected for

analysis. The U.S. Geological Society (USGS) is currently collecting data on both

suspended sediments and bed sediments at five sites along the Amite River;

however, these data will not be available until late 2010 (Dennis Demcheck, USGS,

pers comm, 2009).

While limited sediment sampling data are available at this time, Louisiana

Department of Environmental Quality (LDEQ) has an ongoing program to resample

sediments of all water bodies currently identified as impaired due to the presence of

metals, using improved sampling methods to minimize sample contamination. In

the most recent 303(d) list of impaired water bodies (2006), all reaches of the Amite

River, the Blind River, and the ARDC are listed as impaired for the Fish and

Wildlife Propagation designated use because of mercury. While this was originally

determined by LDEQ using fish tissue sampling, LDEQ will likely conduct sediment

sampling for confirmation of this data prior to the 2011 TMDL deadline.

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3.3.1.8 Vegetation Resources

Riparian Vegetation: Depending on the elevation, riparian corridors are forested

with a myriad of tree species; the wettest areas are dominated by bald

cypress/tupelo while the highest elevation areas are dominated by hardwood tree

species such as oak, ash and elm. Riparian habitat along the ARDC is well defined;

a steep geological gradient limits the influence of the ARDC and the spread of

hydrophytes. This area has also remained relatively stable since the ARDC was

completed.

Wetland Vegetation: Wetland coverage data within the Study Area were obtained

from the National Wetlands Inventory (www.fws.gov/wetlands). The National

Wetlands Inventory is maintained by the U.S. Fish and Wildlife Service (USFWS)

and provides general wetland occurrence data for coastal regions in the United

States. Wetland habitat types within the Study Area are characterized into four

major categories: palustrine forested (92.77%); palustrine emergent, scrub-shrub,

unconsolidated bottom, and aquatic bed (1.2%); uplands (4.4%), and riverine

(lacustrine).

The most common wetland habitat in the Study Area is wetland forest. About

18,204 acres of primarily bald cypress-tupelo swamp habitat are presently

impounded at different levels within the Study Area. Existing swamp habitats are

converting to marsh and shallow open water habitats. The other dominant habitat

types include water (1,123 acres), upland forest (406 acres), agriculture/pasture

(375 acres), developed areas (251 acres), and freshwater marsh (249 acres).

Vegetation Communities: Common plant species are presented by habitat type in

Table 3-3. Many species occur in more than one habitat. Highly flood-tolerant bald

cypress and water tupelo dominate the overstory of much of the Study Area (Conner

and Day, 1976). This dominance is due in part to their ability to produce secondary

roots with the capacity to oxidize the area surrounding their roots in flooded,

anaerobic soils.

In addition to bald cypress and water tupelo, stems of swamp red maple, green ash,

swamp tupelo, and various oak species are also found in bald cypress-tupelo swamp

habitat, with swamp red maple and green ash comprising subdominant midstory

species (Conner and Day, 1976; Hoeppner, 2008; Shaffer et al., 2003). Scrub

species, including black willow, wax myrtle, and common buttonbush, are

sporadically present, particularly in areas with diminished canopy cover caused by

impaired health or mortality of overstory species.

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Table 3-3: Common Plant Species in Study Area

Common Name Scientific Name Habitat Type(s)

Bald cypress Taxodium distichum Bald cypress-tupelo

Black willow Salix nigra Bald cypress

Green ash Fraxinus pennsylvanica Bald cypress

Swamp tupelo Nyssa biflora Bald cypress

Tupelo gum Nyssa aquatica Bald cypress

Buttonbush Cephalanthus

occidentalis

Bald cypress-tupelo

Freshwater marsh

Bulltongue Sagittaria lancifolia Freshwater marsh

Intermediate marsh

Dwarf spikerush Eleocharis parvula Freshwater marsh

Intermediate marsh

Wax myrtle Myrica cerifera Freshwater marsh

Intermediate marsh

Alligator weed Alternanthera

philoxeroides Freshwater marsh

Arrow arum Peltandra virginica Freshwater marsh

Lizard’s tail Saururus cernuus Freshwater marsh

Maidencane Panicum hemitomon Freshwater marsh

Swamp smartweed Polygonum punctatum Freshwater marsh

Chinese privet Ligustrum sinense Upland ridge

Chinese tallowtree Triadica sebifera Upland ridge

Swamp red maple Acer rubrum var.

drummondii

Upland ridge

Bald cypress-tupelo

Water oak Quercus nigra Upland ridge

Bald cypress-tupelo

Laurel oak Quercus laurifolia Upland ridge

Bald cypress-tupelo

Much of the bald cypress-tupelo swamp habitat within the Study Area is not fully

stocked, suggesting that environmental stressors are affecting regeneration and

stand growth (Chambers et al., 2005). Altered hydrological conditions in

southeastern Louisiana have reduced or eliminated natural regeneration of bald

cypress and water tupelo, and reduced productivity. Neither bald cypress nor water

tupelo seeds germinate in water, and submerged cypress seedlings die within 3–6

weeks (Demaree, 1932; Souther, 2000). Flooding caused by relative sea level rise

(RSLR) (primarily as a result of regional subsidence) has decreased the probability

of natural regeneration of many stands of bald cypress-tupelo forest (Conner et al.,

1981; Chambers et al., 2005). The swamps in the Study Area and vicinity are

impacted by elevated levels of subsidence and consequent saltwater intrusion and

experience a lack of sediment and nutrient input. Tree recruitment is further

limited severely by the mammalian seedling predator nutria (Myocastor coypus),

and in many areas of the swamp, bald cypress and water tupelo are defoliated

annually by outbreaks of bald cypress leafrollers (Archips goyerana) and forest tent

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caterpillars (Malacosoma disstria) (Myers et al., 1995; Beville, 2002; Effler et al.,

2006).

Vegetative communities are affected by water level and RSLR. Within the Study

Area, sea level rise is predicted to occur from 1.5 ft (0.46 meter [m]) to 3.2 ft (0.97

m) over the 50-year period of analysis of the project. Whether marsh substrate

accretion can keep pace with sea level rise depends on processes involving sediment

deposition on the marsh surface and below ground production of organic matter

(DeLaune et al., 1983; Turner, 1990; Reed, 1995; Day et al., 2000). These processes

vary both spatially and temporally and are not well understood in many Louisiana

marsh systems (Jarvis C. Jessie, unpublished data). It is estimated that the net

accretion rate would be 8mm/year, within the healthiest portions of the Study Area

(Bernard Wood, pers com, 2009). These net accretion rates account for subsidence

but not eustatic sea level rise. Based on these estimates, accretion rates could

reduce the potential impacts of sea level rise.

Upland Vegetation: Several ridge remnants run through the Study Area. These

ridges are mostly near the midpoint of the east-west portion of the ARDC. In

addition, an old railroad grade and dredged material berms transect the Study Area

with similar habitats.

Upland vegetation on the natural ridges is being impacted due to increasing water

in impounded areas. This stresses existing trees and shifts the community toward a

wetter cypress/tupelo forest. This disturbance also provides an opportunity for

invasive species to gain a foothold and crowd out developing native vegetation.

Upland vegetation on the dredged material berms and the railroad grade are also

threatened by residential development.

Submerged Aquatic Vegetation (SAV): SAV communities within the Study Area

are largely confined to areas of higher water flow. This includes natural waterways

and natural cuts into the swamp interior. Shallow water habitats within the Study

Area that have insufficient flow have become choked with floating vegetation,

greatly limiting light penetration within the water column and SAV occurrence.

Invasive Species Vegetation: Invasive plant species include water hyacinth,

alligatorweed, hydrilla, common salvinia, giant salvinia, Chinese tallow, and

Chinese privet (Ligustrum sinense) (USACE, 2004b). Each of these invasive species

is well established within the Study Area. The impacts of each of these species on

the native flora include physical competition for resources, such as nutrients and

light, impacts to community structure and composition, and impact to ecosystem

processes and system wide parameters. Water hyacinth, common salvinia, giant

salvinia, and hydrilla all limit the amount of light penetrating the water column,

which in turn impacts plankton biomass production. Alligatorweed, Chinese tallow

and Chinese privet are of minimal wildlife value and can proliferate until nearly

monocultural stands exist, limiting food available for wildlife.

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Rare, Unique, and Imperiled Vegetative Communities: The unique

communities nestled within the broader vegetative habitats are important in that

they contribute to the extensive diversity of the coastal ecosystem, are the basis for

its productivity, and are essential to the stability of the bionetwork. According to

the Louisiana Natural Heritage Program (LNHP) database, administered by the

Louisiana Department of Wildlife and Fisheries (LDWF), the only rare, unique, and

imperiled communities present in the Study Area are cypress-tupelo swamp and

freshwater marsh.

3.3.1.9 Salinity

Storm surges from Lake Maurepas caused by tropical cyclones can exert severe

stress on the swamp habitat through salinity spikes in swamp surface waters.

Dredged material berms prevent higher salinity water from being flushed out of the

system (CWPPRA 445 Task Force, 2002). Storm surge waters remain in the

impounded swamps of the LCA ARDC Modification Study Area cumulatively

increasing salinities in impounded waters and soils. The subsequent absorption of

salt into the substrate contributes to the degradation of the swamp and its eventual

conversion to marsh and, ultimately, open water (Shaffer et al., 2006).

Salinity data were collected on the ARDC and the Blind River in 2006. Although

the data are extremely limited, the salinity at the Blind River was higher than at

the ARDC (LDEQ, 2009). The mean salinity at the ARDC was 0.175 parts per

thousand (ppt); the mean salinity at Blind River was 0.462 ppt, indicating that the

Blind River station was slightly more influenced by salt water than the ARDC.

Salinity data from the Coastwide Reference Monitoring System (CRMS) stations

confirm the LDEQ data.

3.3.1.10 Threatened and Endangered Species

Federal Designation: Several animal and plant species under the Federal

jurisdiction of the USFWS and/or the National Marine Fisheries Service (NMFS)

presently classified as endangered or threatened are within the Study Area (Table

3-4).

Table 3-4: Federally Threatened and Endangered Plant and Animal

Species in the Study Area

Species Critical

Habitat Status Jurisdiction

USFWS NMFS

Red-cockaded woodpecker (Picoides borealis) E X

West Indian manatee (Trichechus

manatus) E X

Gulf sturgeon (Acipenser oxyrhynchus

desotoi) T X X

Alabama shad (Alosa alabamae) C X

Inflated heelsplitter (Potamilus inflatus) T X

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Species Critical

Habitat Status Jurisdiction

USFWS NMFS

Note: Species with occurrences within Study Area as documented by USFWS and/or LNHP are denoted by a bold font.

E= Endangered; T= Threatened; C = Candidate;S1 = Critically Imperiled in LA; S2 = Imperiled in LA; S3 = Rare in LA;

S4 = Report in LA

State Designation: The LNHP maintains a directory of over 6,000 occurrences of

rare, threatened, or endangered species; unique natural communities; and other

distinctive elements of natural diversity; and has identified approximately 380

ecologically significant sites statewide. The LNHP lists rare species within

Ascension and Livingston parishes that may be present within the Study Area

(Table 3-5). Additionally, the LNHP lists the following species or rare elements as

occurring in the Study Area: bald cypress-tupelo swamp habitat, a bald eagle nest,

and two great blue heron rookeries.

Table 3-5: LNHP Rare, Threatened, and Endangered Species and Natural

Communities in Ascension and Livingston Parishes-January 2010

Scientific Name Common Name State Rank

Acipenser oxyrinchus desotoi Gulf sturgeon S1S2/Threatened

Aimophila aestivalis Bachman’s sparrow S3

Alosa alabamae Alabama shad S1

Bottomland hardwood forest Bottomland hardwood forest S4

Cypress-tupelo swamp Cypress-tupelo swamp S4

Haliaeetus leucocephalus Bald eagle S2N,S3B /

Endangered

Hemidactylium scutatum Four-toed salamander S1

Lampsilis ornata Southern pocketbook S3

Mustela frenata Long-tailed weasel S2S4

Ophisaurus ventralis Eastern glass lizard S3

Picoides borealis Red-cockaded woodpecker S2

Potamilus inflatus Inflated heelsplitter S1 / Threatened

Rhadinaea flavilata Pine woods snake S1

Rhynchospora miliacea Millet beakrush S2

Sorex longirostris Southeastern shrew S2S3

Spilogale putorius Eastern spotted skunk S1

Spruce pine-hardwood mesic

flatwoods

Spruce pine-hardwood mesic

flatwoods S2

Stewartia malacodendron Silky camellia S2S3

Trichechus manatus West Indian manatee SZN / Endangered

Trichomanes petersii Dwarf filmy-fern S2

Waterbird nesting colony Waterbird nesting colony SNR

Note: State element ranks: B = breeding occurrence; N = nonbreeding occurrence; S1 =Critically imperiled in LA; S2 =

Imperiled in LA; S3 = Rare and local throughout LA; S4 = Apparently secure in LA; SR = Reported in LA; SZ =

transient species

3.3.1.11 Cultural and Historic Resources

Human activities, as well as natural processes, can potentially destroy cultural and

historic resources. The loss of land threatens the existence and integrity of these

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resources. An inventory of identified cultural resource sites within the Study Area

was compiled through database and paper map searches located at the State

Historic Preservation Office (SHPO). The SHPO manages these resources through

the Divisions of Archaeology and Historic Preservation for use during the Section

106 review process.

After a preliminary archival research of recorded cultural resources in the

geodatabase layers and USGS quadrangle maps, a cultural resources survey for the

final array of alternatives was conducted. Five archaeological sites were identified

within or immediately adjacent to the Study Area (Table 3-6). While these sites are

near the Study Area, no impact to these identified sites is anticipated from project

activities. Findings have been coordinated with the SHPO in accordance with

Section 106 compliance. A letter of SHPO concurrence with these findings was

received and is included in the FS/SEIS (Volume II, Appendix E).

Table 3-6: Identified Archaeological Sites Within the Study Area

Site ID Description Location Comments NRHP

Status

16LV91 Destroyed mound site Bayou Chene Blanc

bankside Possible camp site Eligible

16LV92 Shell midden Bayou Chene Blanc

bankside Possible camp site Potentiallyeligible

16LV93 Shell midden Bayou Chene Blanc

bankside Possible camp site Potentiallyeligible

16LV5 Shell midden and

prehistoric scatter

Amite River

bankside

Possible prehistoric

hamlet or village Eligible

16AN16 Shell midden ARDC bankside Possible prehistoric

hamlet or village Unknown

Note: NRHP = National Register of Historic Places

3.3.1.12 Recreation

Recreation activities in the Study Area are centered on the area’s natural resources.

The waterways within and composing the boundaries of the Study Area are used

extensively for recreational purposes. According to the LDWF (pers comm), the

most important of these activities is pleasure boating, followed by fishing and then

by hunting. Water access is available from private docks along the waterways and

from public and private boat ramps.

3.3.1.13 Socioeconomic Resources – Gas, Oil, Utilities and Pipelines

Data from the Louisiana Department of Natural Resources (LDNR) Strategic

Online Natural Resources Information System (SONRIS) indicate that oil and gas

production activities within the LCA ARDC Modification Study Area have been

relatively light and occurred primarily in the late twentieth century. The oil and

gas wells in the Study Area are dry holes that have been plugged and abandoned.

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3.3.2 Future Without Project Condition

The future without project conditions are the same as conditions under the No

Action Alternative. Therefore, the No Action Alternative scenario was the basis for

comparison of the alternatives in Plan Formulation. Without Federal action, the

swamp habitat surrounding the ARDC would continue to degrade, resulting in the

eventual conversion from a freshwater swamp to a freshwater marsh and open

water. The future without project condition would be the continued impoundment

of swamp water within the Study Area, a reduction in tree canopy, water quality,

hydrologic connectivity, and a transition toward marsh and salinity-tolerant

vegetation. Storm surges from tropical cyclone events would increase salinity

levels, and the frequency of saltwater inundation is expected to increase with RSLR.

The lack of exchange of freshwater, sediments, and nutrients will continue to lead

to reduced tree vigor and growth, increased tree mortality, increased invasive

species stands, and loss of ecological functions. Likely, with the expected RSLR

rise, the swamp degradation would accelerate in the future. Major portions of

subunits NE-2, SE-2, and SE-1, would likely deteriorate to freshwater marsh within

30 years (Figure 3-3).

Figure 3-3: LCA ARDC Predicted Study Area habitat conversions

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3.3.2.1 Soils

The No Action Alternative, not implementing the LCA ARDC Modification Project,

would have no direct impacts on soil resources. Indirect impacts would include the

continued erosion and land loss would continue throughout the Study Area, eroding

primarily Barbary, Fausse, and Maurepas soils. Most of the erosion would occur in

the interfaces between open water with marsh and/or upland habitat. Soils would

be indirectly impacted by habitat conversion from swamp to marsh and the

eventual loss of existing soil resources converting to shallow open water.

In addition to the loss of soil resources throughout coast Louisiana; the cumulative

impacts of the No Action Alternative would result in continuing loss of soil

resources from the Study Area. The LCA Report estimated coastal Louisiana would

continue to lose land at a rate of approximately 6,600 acres per year over the next

50 years (USACE, 2004b). It is estimated that an additional net loss of 328,000

acres coastwide may occur by 2050, which represents nearly 10% of Louisiana's

remaining coastal wetlands. The conversion of 18,204 acres of swamp to a shallow

open water system within the Study Area would be additive with other swamp

losses and degradation impacts to soils throughout the region and state.

3.3.2.2 Water Bottoms

The No Action Alternative would have no direct impacts on water bottoms.

Indirectly, existing swamp habitat would continue to be converted to water bottoms.

The decomposition of swamp vegetation would initially increase the availability of

nutrients and detritus. However, the continued degradation from freshwater marsh

to shallow open water would ultimately decrease available nutrients and detritus.

Throughout coastal Louisiana and within the Study Area an increase in shallow

water bottom acreage would occur in response to wetland loss. Overall cumulative

impacts include the conversion of 18,204 acres of swamp to a shallow open water

system within the Study Area would be additive with other swamp losses and

degradation impacts to water bottoms throughout the region, state, and nation.

3.3.2.3 Hydraulics and Hydrology

Hydrologic change is the main measure by which the swamps can be restored in the

Study Area. The No Action Alternative would have no direct impacts to flow and

water levels as compared to the existing conditions except there would be an

increase in water levels due to sea level rise. Indirect impacts of not implementing

wetland restoration would result in the persistence of existing conditions. Water

flow into and out of the swamp would remain inhibited by the dredged material

berms, resulting in continued impoundment of and lack of connectivity to the

adjacent swamp habitat. This continued impoundment and lack of connectivity

would continue to stress and degrade the swamp habitat, converting from

freshwater marsh to open water.

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Cumulative impacts of not implementing restoration actions and reconnecting

hydrologic flows between the Maurepas Swamp and adjacent waters would result in

the continued degradation and conversion of 18,204 acres of existing swamp habitat

to marsh and shallow open water habitat. Water flows into and out of the swamp

would continue to be impeded by the existing dredged material berms along the

ARDC. Water levels within the impounded Study Area would likely increase due to

projected rise in sea level. The conversion of 18,204 acres would be in addition to

other swamp habitat losses and degradation impacts to flows and water levels

throughout the region, state and nation.

Relative Sea Level Rise: Hydrologic restoration must account for the RSLR. In

response to this concern, potential impacts of RSLR were evaluated based on three

estimates (low, intermediate, and high) of predicted RSLR. The evaluation adhered

to guidelines established in Incorporating Sea level Change Considerations in Civil

Works Programs, EC 1165-2-211 (USACE, 2009b). The following estimates of RSLR

account for both the eustatic rate of sea level rise and the local subsidence rate.

Table 3-7 presents a summary of the estimated total sea level rise in 5-year

increments through the 50-year period of analysis for each. Figure 3-4 shows the

estimated sea level rise.

Figure 3-4: Sea level rise for Study Area

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Table 3-7: Summary of Five-Year Sea Level Rise for Each Case

Project year Low Rate

(ft)

Intermediate Rate

(ft)

High Rate

(ft)

2012 0.0 0.0 0.0

2017 0.2 0.2 0.2

2022 0.3 0.3 0.5

2027 0.5 0.5 0.8

2032 0.6 0.7 1.1

2037 0.8 0.9 1.4

2042 0.9 1.1 1.7

2047 1.1 1.3 2.0

2052 1.2 1.5 2.4

2057 1.4 1.7 2.8

2062 1.5 1.9 3.2

The rates of sea level rise and the rate of accretion relative to the existing elevation

of the swamp are depicted in Figure 3-5 through Figure 3-7. The hydrologic

modeling shows that under the low RSLR estimate for the No Action Alternative,

the areas would be permanently inundated in 14 years (Table 3-8). Under the

future with project conditions, the area of impacts would not be considered

permanently inundated for 40 years. The project is able to substantially reduce the

impacts of RSLR as compared to the future without project condition. Low oxygen

and reducing conditions restrict tree growth in inundated conditions. Improved

flow would increase oxygen and improve tree vigor, even in fully inundated

conditions (Gary Shaffer, pers comm, 2009). The introduction of freshwater,

nutrients, and sediments, even if the future with project permanent inundation did

occur, would still improve that swamp habitat over the future without project

condition and produce sustainable project benefits (Gary Shaffer, pers comm, 2009).

Table 3-8: Years to Permanent Inundation

RSLR Case RSLR Year 50

(ft)

No Action

(years)

With Project

(years)

Low rate 1.5 14 40

Intermediate rate 1.9 12.5 31

High rate 3.2 8 17

Accretion will also play a role in reducing the effects of RSLR. It has been

estimated that a net accretion of 8 mm/year could be achieved within the Study

Area (Bernard Wood, pers comm, 2009). Through biomass accretion, the impacts of

RSLR would be reduced.

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Note: FWP = future with project

Figure 3-5: Impacts of low sea level rise, subsidence, and accretion

Figure 3-6: Impacts of Intermediate Sea Level Rise, Subsidence, and Accretion

Figure 3-7: Impacts of high sea level rise, subsidence, and accretion

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3.3.2.4 Sedimentation and Erosion

The No Action Alternative would have no direct impacts to sediment supply to and

from the swamp. The sediment in the waters of the ARDC is primarily suspended

fines that would be prevented from entering the swamp by the dredged material

berms of the ARDC. Lack of sediment would lead to increased erosion and swamp

degradation. Indirectly, the swamp health would continue to degrade due to the

lack of connectivity and lack of sediment and nutrient input.

Cumulative effects include the continued impaired sediment supply due to

urbanization and the resulting degradation of coastal wetlands, as well as the

benefits and impacts of other state and Federal projects in the vicinity. Subsidence

and RSLR would likely continue to occur at a rate greater than sediment deposition,

resulting in a net lowering of land surface throughout much of coastal Louisiana.

Within the Study Area, tropical storms may cause some redistribution of sediments

to and from the swamp and surrounding waterways, but the ARDC existing

dredged material berms would likely continue to block exchange and sedimentation.

Overall cumulative impacts include the conversion of 18,204 acres of swamp to a

shallow open water system in the Study Area.

3.3.2.5 Vegetation Resources

Riparian Vegetation: The No Action Alternative would have no direct impacts on

to riparian vegetation. The surface water salinity regime and nutrient deprivation

would continue to influence the existing riparian habitats. Without hydrologic

restoration, freshwater flow into these habitats would be limited. Nutrient

deprivation and salt water stress would likely continue to degrade these habitats.

Wetland Vegetation: The No Action Alternative would have no direct impacts to

wetland vegetation resources. The lack of connectivity for freshwater, nutrient, and

sediment exchange would continue to degrade the wetland habitat. Additionally,

impoundment caused by the dredged material berms would continue to degrade the

freshwater swamp habitat. The freshwater swamp would degrade to freshwater

marsh and, eventually, to open water. Functions lost would include habitat for

wildlife and aquatic species, recreational opportunities, aesthetics, and storm surge

protection. The freshwater marsh does offer some of the functions, but certain

functions are lost with the swamp, such as habitat for avian species and storm

surge protection. Cumulative impacts would be the continued degradation effects of

coastal land loss due to hydrologic impairment, development, subsidence, sea level

rise, and saltwater intrusion. Other cumulative impacts include the conversion of

18,204 acres of swamp to a shallow open water system within the Study Area,

which would be additive with other swamp losses and degradation impacts to

wetland vegetation throughout the region and state.

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Upland Vegetation: There would be no direct or indirect impacts to upland

vegetation. The significant amount of upland vegetation existing in the Study Area

is on the existing spoil bank and would likely remain even as the surrounding

swamp converts to open water. The upland vegetation existing in the Study Area is

on the existing spoil bank and would likely remain even as the surrounding swamp

converts to open water. Therefore, there would be no cumulative effect with the No

Action Alternative.

Submerged Aquatic Vegetation: The No Action Alternative, not implementing

the LCA ARDC Modification Project, would have no direct or indirect impacts to the

SAV vegetative community.

Invasive Species Vegetation: There would be no direct impacts to invasive

vegetation. Invasive species would continue to spread, as the swamp converts to

marsh and open water. Invasive vegetation would continue to increase.

3.3.2.6 Salinity

The No Action Alternative, not implementing the LCA ARDC Modification Project,

would have direct impacts on salinity. Storm surges from tropical cyclone events

would increase salinity levels. The existing impoundments would retain higher

salinity water within the Study Area allowing absorption into the substrate. The

frequency of saltwater inundation is expected to increase with RSLR. Indirectly,

vegetation within the impounded swamp areas could be subject to salt stress when

saline waters are not freely flushed from the system. Flora and fauna species may

change over time as salt-tolerant species replace freshwater species.

Cumulative impacts would include the negative impacts of increased salinity levels

moving further inland along coastal Louisiana, which leads to the degradation of

wetland vegetation and furthers coastal and bottomland habitat loss, together with

the benefits and impacts of other state and Federal projects in the vicinity. The

regional effects of RSLR may also play a role in increasing salinity levels within the

region. Within the Study Area, the continual impoundment and lack of hydrologic

connectivity would likely result in higher residence times and higher salinity levels.

Overall cumulative impacts include the conversion of 18,204 acres of swamp to a

shallow open water system within the Study Area would be additive with other

swamp losses and degradation throughout the region and state.

3.3.2.7 Threatened and Endangered Species

There would be no direct effects on threatened and endangered species or their

habitat. Indirect effects would include continuing general habitat loss for the Study

Area. Important habitat within the Study Area would continue to erode and convert

to shallow open water. Cumulatively, there would be a continued degradation and

loss of fish and wildlife habitat for shelter, nesting, feeding, roosting, cover, nursery,

and other life requirements in coastal Louisiana.

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3.3.2.8 Cultural and Historic Resources

The No Action Alternative, not implementing the LCA ARDC Modification Project,

would have no direct impacts on historic and cultural resources. Indirectly, land

loss in the Study Area threatens the existence and integrity of all cultural resources

in the area. Within the country and coastal Louisiana, the institutional recognition

of all cultural resources as a significant resource would likely continue, along with

their potential loss due to natural and human causes. The land loss within the

Study Area threatens the existence and integrity of these resources.

3.3.2.9 Recreation

There would be no direct or indirect effects on recreation within the Study Area.

Indirectly, there would be continued loss of habitat in the Study Area, resulting in

lost recreational opportunities. There would be a continued land loss in coastal

Louisiana of habitat resulting in lost recreational opportunities.

3.3.2.10 Socioeconomic Resources- Gas, Oil and Pipelines

There would be no direct, indirect, or cumulative impacts to oil, gas, utilities and

pipelines as a result of the No Action Alternative.

3.4 Alternatives *

3.4.1 Plan Formulation Rationale

The plan formulation process is iterative and comprehensive and includes a number

of detailed evaluations of potential measures and combinations of measures to

develop alternatives to address problems, needs, and opportunities; meet project

objectives; and stay within project constraints. Specifically, management measures

are presented, screening criteria are discussed, and initial alternative plans are

presented along with the screening process to obtain the final array of alternatives.

The alternative plans identified through the plan formulation process are then

evaluated, based on 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. Ecosystem benefits, cost effectiveness, and

environmental impacts were also considered to ensure that the recommended plan

best meets the project objectives and authorized project scope.

As part of plan formulation, a Value Engineering (VE) study was conducted to

identify potential modifications of restoration measures and plan configurations

that could improve the performance and cost effectiveness of the preliminary

measures. The results of the VE study for this project were fully considered and

were used to refine the measures and alternatives being considered. The VE study

is included in the FS/SEIS (Appendix H, Volume II).

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3.4.2 Management Measures

Management measures were developed to address planning objectives and Study

Area problems, and capitalize on Study Area opportunities. Management measures

were derived from a variety of sources including prior studies, the NEPA public

scoping process, the VE study, academia, and the expertise of the interagency PDT.

The management measures were screened based on project objectives, constraints,

effectiveness, and practicality. A total of 105 management measures were

developed, including structural and nonstructural measures. All management

measures considered were deemed consistent with Administration budget policy,

specific USACE policies for ecosystem restoration, and Federal laws, regulations,

and Executive Orders.

3.4.2.1 Description of Management Measures

Freshwater Reintroduction Measures

Bank Openings (BO)



: Discrete openings at various locations along the ARDC

dredged material berms, the relict railroad grade, and the natural banks of

other waterways. Bank openings included open cuts, culverts, or bridged

gaps. The locations for these openings would be chosen based on natural

topography within the Study Area. The placement of the dredged material

would create bottomland hardwood habitat as a means of combating the

effects of sea level rise within the Study Area.

Bank Degradation (BD)



: Degradation of the entire ARDC dredged material

berm complex, dredged material berm degradation, and degradation of the

relict railroad grade.

Conveyance Channel (CC)



: Construction of conveyance channels to establish

hydrologic connectivity between the ARDC and interior swamp. The

placement of the dredged material to create bottomland hardwood habitat

was also considered.

Hydraulic Pump (PU)



: Installation of hydraulic pumps between the ARDC

and interior swamp. Additionally, a ring levee could be utilized to help offset

the effects of RSLR.

Siphon Installation (SI)



: Installation of siphons to establish hydrologic

connectivity between the ARDC and interior swamp locations.

Weir Construction (WC)



: Construction of weirs along the ARDC dredged

material berms at various locations.

Weir Rehabilitation (WR)



: Rehabilitation of the existing weir at French

Settlement at the confluence of the ARDC and the Amite River. This

measure could reduce the flow down the ARDC.

Wastewater Reintroduction (WWR): The reintroduction of wastewater from

local industries and campsites was considered to add nutrients to the swamp.

The nutrients would increase the production of tree species within the

interior swamp.

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Maximize Lake Maurepas Freshwater Content to Act as a Saltwater Buffer

(MLM): Measures were considered which would increase the overall

freshwater content within Lake Maurepas in order to reduce saltwater

intrusion. A reduction in saltwater intrusion would result in lower salinity

levels within the swamp habitat and could allow for more production and

regeneration of native swamp tree species.

Channel Restoration Measures

Shoal Removal (SR)



: Removal of shoals or sediment plugs from the mouths of

Bayou Pierre, the lower Amite River, and the Blind River.

Clearing and Snagging (CS)



: Clearing and snagging of natural waterways

was considered at various locations.

Channel Dredging (CD): Channel dredging of natural waterways at various

locations.

Habitat Restoration Measures

Nonstructural Vegetative Planting (VP)



: Vegetative planting to restore bald

cypress-tupelo communities in degraded areas. Vegetative plantings could

also be combined with other measures to increase potential benefits.

Spray Dredging (SD)



: Spray dredging of degraded areas adjacent to the

ARDC. This measure is a form of marsh creation in which dredged material

is broadcast within a specific area in order to create marsh habitat. This

measure was also considered a means by which to combat the effects of sea

level rise within the Study Area.

Habitat Creation via Placement of Dredged Material (HC)



: The placement of

dredged material as additional upland and bottomland hardwood habitat.

These areas could serve as refuge for some species of wildlife during highwater events while also providing areas to implement supplemental plantings

of bottomland hardwood tree species.

Dedicated Dredging (DD): Dedicated dredging of Lake Maurepas for

beneficial use material in marsh creation. Dedicated dredging is a form of

marsh creation in which the material is mechanically or hydraulically placed

within a specified area in order to create marsh habitat. This measure was

also considered a means by which to combat the effects of sea level rise

within the Study Area.

3.4.2.2 Screening of Management Measures

All 105 measures were screened based on criteria, including project objectives and

constraints, expected subunit degradation, effectiveness, adverse environmental

impacts, and practicability. Even though each measure was evaluated against its

ability to accomplish the project objectives, no measure was eliminated if a specific

objective was not achieved. Additionally, consideration was given to measures that

could be combined with other measures to achieve the project objectives. The

effectiveness of each measure was considered to ensure that the objectives would be

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adequately met. If a measure resulted in overall negative environmental impacts, it

was screened out. The practicability of each measure was considered to ensure that

each measure or a combination of measures could achieve one or more of the stated

objectives, with a feasible amount of effort. Some measures originally considered,

such as the removal of the entire dredged material berm along the ARDC, were

screened out prior to the final development of all 105 management measures.

Conversely, upon further investigation, some measures were introduced after the

initial group of measures was developed, such as the clearing and snagging of

existing channels and bayous. Through this iterative process, the final 105

management measures were developed.

The screening strategy included evaluation of the Study Areas hydrologic subunits

(Figure 3-1) to determine subunits with the most near-term degradation, in keeping

with the overall LCA goals, to first address near-term degradation. The nine

hydrologic subunits (NW-1, NW-2, NE-1, NE-2, NE-3, SW-1, SW-2, SE-1, SE-2)

were examined to determine the degree of degradation, level of existing hydrologic

connectivity, and identification of hydrologic measures that would benefit the area.

Based on that analysis, subunits NE-1, NE-2, SE-1, and SE-2 were retained for

further study.

Generally, the most near-term degradation is expected to occur in the easternmost

subunits, and the opportunity to restore habitat is the greatest in these four

subunits (NE-1, NE-2, SE-1, and SE-2). Although there is some expected

degradation in NE-3, there is no major man-made degradation in this subunit and

no opportunities available in NE-3. The westernmost subunits, NW-1 and SW-1,

appear to be healthy; therefore, no restoration is needed. NW-2 is a very healthy

system due to the connectivity with the Petite Amite River. SW-2 is a healthy

system with some areas expected to become marsh within 20-30 years. Public

comments initially indicated that degradation had occurred within subunit SW-2.

However, based on analysis of aerial photography and discussions with the LDWF,

it was determined that any perceived degradation existed within the subunit prior

to the construction of the ARDC.

Conveyance channels were added to the proposed gaps to ensure that a hydraulic

connection between the ARDC and the swamp was achieved. The need for these

conveyance channels was based on the hydrological and hydraulic analysis, field

reconnaissance, and previous project experience on the Davis Pond Freshwater

Diversion project. The conveyance channel dimensions were based on the existing

conveyance channels within the study area and were designed using the width,

depth, and profile of existing sustainable channels. It was determined that if only

gaps were constructed, without conveyance channels, there likely would not be

enough water exchange to keep these gaps open or to improve the swamp habitat.

It was also concluded that gaps, with associated conveyance channels, would be

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sustainable and allow for adequate water exchange between the ARDC and the

impaired swamp.

Vegetative plantings were added to the alternatives. It was determined that

vegetative plantings along with the reestablishment of hydrologic connectivity are

both essential in highly degraded areas (NE-2 and SE-2) to reestablish a productive

stand and adequate canopy cover where natural regeneration likely would not occur

within the period of record and before the effects of RSLR permanently inundated

the system. Permanent inundation would prevent planted or naturally regenerated

species from becoming established; however, the added hydrologic connectivity will

allow for continued success of an already established swamp. Vegetative plantings

are also needed for native trees to become reestablished and overcome competition

from exotic and invasive species. Nutria exclusion methods will be included on all

plantings to prevent nutria from damaging or killing newly planted seedlings.

3.4.3 Preliminary Alternative Plans

Following screening, 91 measures were eliminated. Fourteen restoration measures

were retained for further consideration; they were combined and developed into an

initial array of 45 alternatives that collectively met study goals and authorized

scope and were within the defined study constraints. The preliminary alternatives

were evaluated based on the following criteria:

Ability to meet project objectives

Effectiveness

Field investigations

Adverse environmental impacts

3.4.4 Identification of the Final Array of Alternatives

The final array of alternatives includes seven alternatives plus the No Action

Alternative. The final array is listed in Table 3-9. Of the seven alternatives that

make up the final array, three are discrete alternatives, while the other four are

combinations of these three. Alternatives 33, 34, and 35 are the discrete separate

alternatives. Alternative 36 is a combination of Alternatives 33 and 34. Alternative

37 is a combination of Alternatives 34 and 35. Alternative 38 is a combination of

Alternatives 33 and 35. Alternative 39 is a combination of Alternatives 33, 34, and

35. The comparison of the features of the specific alternatives is shown in Table 3-9

and Table 3-10.

Table 3-9: Final Array of Alternatives

Alternative No. Description

No Action (future

without project)

The No Action Alternative consists of not implementing any restoration actions

in the LCA ARDC Study Area and is the future without project condition to

which each alternative in the Final Alternative Array will be compared.

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Alternative No. Description

33

Three openings in the north bank of the ARDC in NE-2 with the westernmost

cut also extending through the railroad grade into NE-1; bifurcated conveyance

channels; sidecasting of dredged material; one cut in the railroad grade located

approximately 0.9 miles north of the ARDC in NE-1/NE-2; dredged material

berm and swamp floor vegetative plantings (BO-14, MPDT-8, BO-23, VE-04,

CC-01, VP-01, VP-02, HC-01)a

34

.

One opening in the south bank of the ARDC in SE-1 west of and within close

proximity to the railroad grade that extends east and through the railroad grade

between SE-1/SE-2 into SE-2; bifurcated conveyance channels; sidecasting of

dredged material; two cuts in the railroad grade located 0.9 and 2 miles south of

the ARDC in SE-1/SE-2; dredged material berm and swamp floor vegetative

plantings (BO-24, VE-04, BO-15, BO-16, CC-03, VP-01, VP-02, HC-03)a

35

.

One opening in the south bank of the ARDC in SE-1; bifurcated conveyance

channels; sidecasting of dredged material; dredged material berm plantings

(BO-16, MPDT-8, VP-02, CC-03, HC-03)a

36

.

Three openings in the north bank of the ARDC in NE-2 with the westernmost

cut also extending through the railroad grade into NE-1; bifurcated conveyance

channels; sidecasting of dredged material; one cut in the railroad grade located

approximately 0.9 miles north of the ARDC in NE-1/NE-2; one opening in the

south bank of the ARDC in SE-1 west of and within close proximity to the

railroad grade that extends east and through the railroad grade between SE1/SE-2 into SE-2; two cuts in the railroad grade located 0.9 and 2 miles south of

the ARDC in SE-1/SE-2; dredged material berm and swamp floor vegetative

plantings (BO-14, MPDT-8, BO-23, VE-04, BO-24, BO-15, BO-16, CC-01, CC-03,

VP-01, VP-02, HC-01, HC-03)a

37

.

Two openings in the south bank of the ARDC in SE-1; bifurcated conveyance

channels; sidecasting of dredged material; one opening located just west of the

natural ridge that intersects the south bank of the ARDC and one west of and

within close proximity to the railroad grade, that extends east and through the

railroad grade between SE-1 and SE-2 into SE-2; two additional cuts in the

railroad grade located 0.9 and 2 miles south of the ARDC in SE-1/SE-2; dredged

material berm and swamp floor vegetative plantings (MPDT-8, BO-15, BO-16,

BO-24, VE-04, CC-03, VP-01, VP-02, HC-03)a

38

.

Three openings in the north bank of the ARDC in NE-2 with the westernmost

cut also extending through the railroad grade into NE-1; bifurcated conveyance

channels; sidecasting of dredged material; one cut located approximately 0.9

miles north of the ARDC in NE-1/NE-2; one opening in the south bank of the

ARDC in SE-1; dredged material berm and swamp floor vegetative plantings

(BO-14, MPDT-8, BO-16, BO-23, VE-04, CC-01, CC-03, VP-01, VP-02, HC-01,

HC-03)a

39

.

Three openings in the north bank of the ARDC in NE-2 with the westernmost

cut also extending through the railroad grade into NE-1; bifurcated conveyance

channels; sidecasting of dredged material; two openings in the south bank of the

ARDC in SE-1, with one cut located west of and within close proximity to the

railroad grade, that extends east and through the railroad grade between SE1/SE-2 into SE-2; three cuts in the railroad grade, one cut located approximately

0.9 miles north of the ARDC in NE-1/NE-2 and two additional cuts in the

railroad grade located 0.8 and 2 miles south of the ARDC in SE-1/SE-2; dredged

material berm and swamp floor vegetative plantings (BO-14, MPDT-8, BO-23,

BO-24, VE-04, BO-15, BO-16, CC-01, CC-03, VP-01, VP-02, HC-01, HC-03)a.

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Alternative No. Description

Note: Parentheses include references to the individual measures included in each alternative. Full descriptions of the

measures included are available in Volume II.

Table 3-10: Comparison of Final Array of Alternatives

Alternative

North

Bank

Openings

South

Bank

Openings

Additional

Railroad

Grade

Openings

Berm

Plantings

(Acres)

Swamp

Plantings

(Acres)

33 3 0 1 5.0 438

34 0 1 2 2.7 487

35 0 1 0 2.2 0

36 3 1 3 7.8 925

37 0 2 2 4.9 487

38 3 1 1 7.2 438

39 3 2 3 9.9 925

3.4.5 Environmental Consequences*

An analysis was conducted on the potential environmental consequences of

implementing alternative plans to reverse the trend of degradation in the western

portion of the Maurepas Swamp. The analysis compares the No Action Alternative

to the alternatives retained for detailed analysis. The No Action Alternative is

considered to be the same as the future without project condition (Volume I, Section

3.3.2) and analyzes the future conditions of the resource over a 50-year period of

analysis from 2012 to 2062.

A brief summary of that analysis is presented here to evaluate the No Action

Alternative against the alternatives proposed in the final array. The full analysis of

all environmental consequences for each alternative is included in Volume II,

Section 5.

No Action Alternative: Without Federal action, the swamp habitat surrounding

the ARDC will continue to degrade resulting in the eventual conversion from a

freshwater swamp to a freshwater marsh and open water. The direct impacts of

this action would be the continued impoundment of swamp water within the Study

Area; a reduction in tree canopy, water quality, hydrologic connectivity; and a

transition toward marsh and saline-tolerant vegetation. Indirect impacts resulting

from the continued habitat degradation would be the eventual decline of wildlife,

fishery, and vegetative resources. Cumulative impacts would be the continual

conversion of swamp habitat to freshwater marsh and open water habitat, along

with the additive results of this habitat degradation when combined with other

Federal, state and local actions.

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Alternative 33: Implementation of Alternative 33 would reverse the conversion of

swamp habitat to open water and would improve 1,602 acres of swamp habitat and

create 5.0 acres of upland habitat within the Study Area. Direct impacts would

include increased water flow into and out of the swamp area, improved water

quality within the areas of impact, and reduced overall salinity levels. Indirect

impacts would include an improvement in wildlife and aquatic habitat, the

regeneration of swamp vegetation and canopy, and increased nutrient and sediment

transport. Cumulative impacts would be the improvement of swamp habitat along

with the additive results of this habitat improvement when combined with other

Federal, state, and local actions.

Alternative 34: Impacts resulting from the implementation of Alternative 34

would be similar to those of Alternative 33 except 1,459 acres of swamp habitat

would be improved and 2.7 acres of upland habitat would be created.

Alternative 35: Impacts resulting from the implementation of Alternative 35

would be similar to those of Alternative 33 except 820 acres of swamp habitat would

be improved and 2.2 acres of upland habitat would be created.

Alternative 36: Impacts resulting from the implementation of Alternative 36

would be similar to those of Alternative 33 except 3,061 acres of swamp habitat

would be improved and 7.8 acres of upland habitat would be created.

Alternative 37: Impacts resulting from the implementation of Alternative 37

would be similar to those of Alternative 33 except 2,279 acres of swamp habitat

would be improved and 4.9 acres of upland habitat would be created.

Alternative 38: Impacts resulting from the implementation of Alternative 38

would be similar to those of Alternative 33 except 2,422 acres of swamp habitat

would be improved and 7.2 acres of upland habitat would be created.

Alternative 39: Impacts resulting from the implementation of Alternative 39

would be similar to those of Alternative 33 except 3,881 acres of swamp habitat

would be improved and 9.9 acres of upland habitat would be created.

3.4.6 Comparison of Alternative Plans

Preliminary construction costs were developed for the final array to use in the Cost

Effectiveness / Incremental Cost Analysis (CE/ICA) analysis. These costs are listed

in Table 3-11. The rationale and assumptions used for the development of unit

costs and all cost estimates are included in the FS/SEIS (Volume II).

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Table 3-11: Summary of Costs Estimates for the Final Array

Item Alt. 33 Alt. 34 Alt. 35 Alt. 36 Alt. 37 Alt. 38 Alt. 39

Mob/Demob $250,000 $150,000 $150,000 $300,000 $200,000 $300,000 $350,000

Earthwork $462,000 $332,000 $262,000 $788,000 $583,000 $698,000 $1,050,000

Erosion

protection $46,000 $23,000 $23,000 $69,000 $45,000 $69,000 $92,000

Vegetative

plantings $819,000 $906,000 $6,000 $1,720,000 $909,000 $822,000 $1,730,000

Surveying $54,000 $22,000 $22,000 $70,000 $70,000 $70,000 $86,000

Markups $631,000 $564,000 $176,000 $1,152,000 $695,000 $756,000 $1,289,000

Planning eng.

& design $189,000 $169,000 $53,000 $346,000 $209,000 $227,000 $387,000

Construction

management $110,000 $99,000 $31,000 $202,000 $122,000 $132,000 $226,000

Total

construction

costs

$2,560,000 $2,270,000 $720,000 $4,650,000 $2,830,000 $3,070,000 $5,210,000

25%

Contingency $640,000 $568,000 $180,000 $1,160,000 $708,000 $768,000 $1,300,000

Real estate $136,000 $144,000 $62,000 $259,000 $185,000 $178,000 $301,000

Costab $3,340,000 $2,980,000 $962,000 $6,070,000 $3,720,000 $4,020,000 $6,810,000

Interest during

construction $440,000 c $390,000 $126,000 $797,000 $489,000 $528,000 $894,000

Total

construction

cost

$3,780,000 3,370,000 $1,090,000 $6,870,000 $4,210,000 $4,550,000 $7,700,000

Annual

OMRR&R costs $10,000 $7,000 $7,000 $11,000 $8,000 $11,000 $12,000

Average annual

cost $197,000 c $174,000 $61,000 $351,000 $217,000 $236,000 $394,000

Note:

Alt. = Alternative

OMRR&R = Operating, Maintaining, Repairing, Replacing, and Rehabilitating

a Preliminary costs were developed for planning purposes only. Cost estimate is not the fully funded cost. b First Quarter 2010 Dollars;

c Average annual costs were determined over the six-year construction period with a discount rate of 4.375%.

The Wetland Value Assessment (WVA) models are ecological benefit models

designed to evaluate the existing, future without project, and future with project

conditions. The CWPPRA WVA Swamp model was chosen for this study area over

the Fresh Marsh model, even though portions of the Study Area have less than a

33% canopy cover, because the area provides functions and values more closely

associated with a freshwater swamp than a freshwater marsh. The WVA produced

AAHUs, a measure of change in habitat quality and/or quality, for the 50-year

period of analysis when comparing the future with project to the future without

project. The WVA analyses were run for each alternative within the final array to

determine the forecasted quantitative benefits of each alternative, including the

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areas impacted by the construction of the bank openings, conveyance channels, and

dredged material placement. Table 3-12 presents the acres of benefit and AAHUs

for each alternative. The WVA analysis was performed on the intermediate and

high RSLR scenarios for the NER and recommended plan. Since all alternatives

within the final array implement similar features in areas with very little

fluctuation in land elevations, it was determined that RSLR would have the same

effect on water levels for all alternatives in the final array and little to no variance

in water levels would occur.

Table 3-12: Alternatives Costs and Benefits

Alt.

Acres

of

Benefit

AAHUs

Total

Construction

Cost

Annualized

Cost a

Annualized a Cost/AAHU

35 820 334 $1,090,000 $61,000 $180

38 2,422 1,013 $4,550,000 $236,000 $230

37 2,279 922 $4,210,000 $217,000 $240

39 3,881 1,602 $7,700,000 $394,000 $250

36 3,061 1,268 $6,870,000 $351,000 $280

33 1,602 679 $3,780,000 $197,000 $290

34 1,459 589 $3,370,000 $174,000 $300

a

The WVA model is undergoing model certification in accordance with EC 1105-2-

407. The model has undergone external review, and the WVA revision

documentation and spreadsheets have been submitted to the National Ecosystem

Planning Center of Expertise (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 this project can be

found in Appendix K of Volume II.

Preliminary costs were developed for planning purposes only. Cost estimate is not the fully

funded cost.

The primary and secondary impact areas for the final array of alternatives were

developed after examining existing conveyance channels found within the study

area. These channels are considered to be in a state of hydrologic equilibrium due

to the lack of sediment buildup observed, when compared to other channels found

within the same general area. The benefit areas for the proposed conveyance

channels were developed by observing the dimensions and configurations of the

drainage areas found along these existing channels.

Each alternative within the final array was evaluated for cost effectiveness through

CE/ICA by utilizing the IWR Planning Suite software. The 50-year evaluation

period for the LCA ARDC Modification Project was used. This software utilizes the

annualized output from the WVA Model (AAHUs) and the annualized costs of each

alternative to determine which proposed actions are deemed cost effective.

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Of the actions considered cost effective by the CE/ICA analysis, some are given the

designation of being considered a Best Buy, meaning the proposed action provides

the greatest increase in output for the least increase in cost. By default, the No

Action Alternative and the largest cost effective alternative (i.e., the cost effective

alternative with the greatest annualized ecosystem outputs or benefits) are

considered to be Best Buy alternatives. Any of the proposed actions that are found

to be cost effective during this analysis may be considered for selection as the

recommended plan. Based on the results of the IWR Planning Suite analysis, no

alternatives were eliminated from consideration. The results of the IWR Planning

Suite analysis are listed in Table 3-13.

Table 3-13: IWR Planning Suite Results

Alternative Annualized Cost Output (AAHUs) a Cost Effective?

No Action Plan $0 0 Best Buy

35 $61,000 334 Best Buy

34 $174,000 589 Yes

33 $197,000 679 Yes

37 $217,000 922 Yes

38 $236,000 1013 Best Buy

36 $351,000 1268 Yes

39 $394,000 1602 Best Buy

a Preliminary costs were developed for planning purposes only. Cost estimate is not the fully funded cost.

The effects of the alternatives within the final array were evaluated against the No

Action Alternative (future without project conditions –Volume I, Section 3.3.2) in

order to determine their overall impact over the 50-year period of analysis of the

project. Alternatives were then compared to each other. This includes

environmental impacts to significant resources (Environmental Consequences–

Volume I, Section 3.4.5), WVA benefits, cost and contributions to project goals,

planning objectives and constraints, contributions to the Federal objective, and the

P&G’s four evaluation criteria (completeness, effectiveness, efficiency and

acceptability). After comparing the final array of alternatives, based on the

applicable criteria and analysis, the PDT ranked the alternatives in the order

depicted in Table 3-14 with Rank 1 being the first choice. These are rankings based

on restoration opportunities provided by each alternative and do not take into

account the WRDA 2007 authorized funding limit.

Table 3-14: Ranking of Final Array

Rank Alternative Reasoning

1 39 Produces the most benefits of any alternative and

addresses the two most critical areas, plus SE-1 and NE-1.

2 36 Produces the second-most benefits of any alternative and

addresses the most critical areas, plus SE-1 and NE-1.

3 38 Produces benefits within the most critical areas, plus SE-1.

SE-1 is not considered as degraded as SE-2.

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Rank Alternative Reasoning

4 33 Includes only the most critical area and benefits to NE-1

5 37 Includes benefits for SE-1 and SE-2. Does not include the

most critical area, NE-2.

6 34 Includes benefits in a smaller portion of SE-1 and SE-2.

Does not include the most critical area, NE-2.

7 35 Includes benefits in SE-1 only. Does not include the most

critical area.

8 No Action Does not produce benefits within the Study Area.

3.4.7 National Ecosystem Restoration Plan

Based on the results of the WVA modeling, the IWR Planning Suite analysis, and

the impacts of alternative plans along with comparisons to the future without

project condition, Alternative 39 was chosen to be the NER plan. This plan includes

all of the subunits in the final array, including the areas with the critical need of

restoration (NE-2 and SE-2 have already begun converting to marsh) and additional

subunits that are expected to need restoration within the next 20 years (SE-1 and

NE-1). The non-Federal sponsor supports Alternative 39 as the NER plan and

believes it represents the long term restoration need for the area.

The non-Federal sponsor supports the NER plan; therefore, no separate locally

preferred plan (LPP) is identified. The NER plan is also identified as the

environmentally preferable plan (EPP) since it maximizes the environmental

benefit.

3.4.8 Plan Selection – Recommended Plan

Alternative 33, which addresses the most-highly degraded portion of the Study Area

(NE-2) and provides benefits within NE-1, has been chosen as the recommended

plan (Figure 3-8). Alternative 33 is an implementable increment of the NER plan,

is within the cost and scope of the 2004 LCA Report and WRDA 2007 authorization

(See Table 3-15), has stand-alone utility, and can be justified based on ecosystem

restoration benefits. The recommended plan would generate 679 AAHUs through

improvement of 1,602 acres of existing swamp and creation of 5.0 acres of uplands

from dredged material placement. The non-Federal sponsor supports Alternative

33 as the recommended plan under the authorization provided.

It should be noted that there are other potential restoration efforts within the Study

Area that may provide an opportunity to build the remaining portions of the NER

plan and/or build additional restoration features in addition to the recommended

plan. The Livingston Parish CIAP project, Hydrologic Restoration in Swamps West

of Lake Maurepas, located within the study area received study funding in

September 2010 to begin design but has not yet been awarded construction funding.

Once authorized and construction funding is awarded, this CIAP project may

construct the bank openings proposed in SE-1 and SE-2 (remaining portions of NER

not included in the recommended plan) and/or construct additional bank openings

to benefit the Study Area.

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A comparison of the costs for the NER plan and the recommended plan is shown in

Table 3-15. The details behind the calculated authorized cost are located in Table

3-16.

Table 3-15 Comparison of the NER and the Recommended Plan

Alternative 39

(NER)

Alternative 33

(Recommended Plan)

Fully Funded Cost

Channels and canals

a

$9,210,000 $4,450,000

Monitoring $3,660,000 $2,970,000

Construction estimate total $12,870,000 $7,420,000

Federal share construction estimate $8,370,000 $4,820,000

Non-Federal share construction estimate $4,500,000 $2,600,000

Lands and damages $390,000 $180,000

Planning, engineering and design $1,110,000 $534,000

Construction management $829,000 $401,000

Project cost total $15,200,000 $8,540,000

Federal share cost total $9,880,000 $5,550,000

Non-Federal share cost total $5,320,000 $2,990,000

Benefits

Benefits (AAHUs) 1,602 679

Annualized cost/AAHU $480 $660

a Discount rate of 4.375% utilized for annualized costs. Fully funded project cost includes inflation adjusted from the

October 2006 price levels through the projected midpoint of project construction.

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WRDA 2007 Section 7006(e)(3) 3-41 October 2010 Figure 3-8 : LCA ARDC Recommended Plan (Alternative 33)

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Table 3-16: Maximum Cost Including Inflation through Construction

Authorized cost in WRDA 2007 Title VII, Section 7006

(e)(3)(A) $5,600,000

Cost index used

EM 1110-2-1304 (Revised 31 Mar 2010)

a CWBS Feature Code 09 – Channels and

Canals

Cost index ratio

1Q FY07 to 3Q FY15 1.20

Fully funded current project cost estimate

(Inflation applied from 10/2006 to 4/2015)

b

$6,711,849

20% of authorized cost: $1,120,000

Monitoring and adaptive managementc

(per WRDA 2007 Section 2039)

: $2,971,200- $45,000

= $2,926,200

Maximum cost limited by Section 902: $6,711,849+ $1,120,000 +2,926,000

= $10,760,000

Recommended plan cost $8,540,000

Note: Actual costs are used in calculations and final costs are rounded. a The cost index applied is derived from: EM 1110-2-1304, 31 Mar 10, Civil Works Construction Cost Index System (CWCCIS).

b For the purposes of applying the cost index to the WRDA authorized cost, each project was adjusted for inflation from

October 2006 price levels to the midpoint of construction for the project. c 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.

3.4.8.1 Components

Three dredged material berm openings and three bifurcated conveyance

channels in the north bank of the ARDC in NE-2 with the westernmost

channel in the north bank of the ARDC also extending through the railroad

grade into NE-1 to add connectivity between NE-1, NE-2, and the ARDC

Dredged material (5.0 acres) from the bank openings and the conveyance

channel would be sidecast on both sides of the proposed conveyance channel.

Gaps would be left in the disposal berms so sheet flow is not reduced

One cut would be created in the railroad grade approximately 0.9 mile north

of the ARDC to improve sheet flow

Vegetative plantings of bottomland hardwood/swamp tree species on

5.0 acres of dredged material berms

Vegetative plantings of freshwater swamp tree species within 438 acres of

the swamp floor

Installation of nutria guards on all newly planted trees to protect against tree

loss

Openings would enable impounded water to be drained from the swamp and provide

hydrologic connectivity between the swamp and the ARDC. Additionally, the

placement of a cut in the railroad grade would provide further hydrologic

connectivity between NE-1 and NE-2. Openings would promote the introduction of

freshwater, sediments, and nutrients into the swamp and allow the oxidation of

sediments and removal of toxic metabolites. This alternative is anticipated to

improve the degraded swamp and decrease the transition to marsh and, ultimately,

open water. This alternative represents the minimum effort that would meet the

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goals and objectives of the project. Alternative 33 would benefit approximately

1,602 acres of existing freshwater swamp, recreate 144 acres of freshwater swamp

from freshwater marsh, and create 5.0 acres of upland habitat from dredged

material placement.

The recommended plan would provide environmental benefits as follows:

Restoring and benefitting 1,602 acres of freshwater swamp habitat;

freshwater swamp habitat has been identified nationally as institutional,

public, and of technical significance. This significance is due to the ecosystem

functions, which include fish and wildlife habitat, water quality benefits,

pollutant filtration, groundwater charge and recharge, habitat for threatened

and endangered species, carbon sequestration, aesthetics, and recreations;

Creating a net of 679 AAHUs; AAHUs are a measure of ecological benefits as

output from the WVA. An AAHU is the equivalent of improving one acre

from a totally nonfunctioning habitat (0% functioning) to a fully functional

one (100%), as well has to take two acres from a 50% functional level to a

100% functional level. The benefits of this project would be to essentially

restore the equivalent on 679 acres of a 100% functioning freshwater swamp

from 679 acres of a completely nonfunctioning habitat.

Creating 5.0 acres of bottomland hardwood habitat

Establishing hydrologic connectivity between the ARDC and the western

Maurepas Swamp allowing the swamp to drain during seasonal low-flow

conditions in the Amite River and allowing nutrients and sediments to be

introduced from the ARDC into the adjacent swamp during flood events and

from runoff during localized rainfall events

Reducing the likelihood of the swamp being converted to marsh or open water

Promoting the germination and survival of the seedlings of bald cypress and

other trees

Improving biological productivity and reducing further habitat deterioration

The outputs provided by the recommended plan are technically recognized:

Scarcity: Louisiana's coastline represents 90% of the wetlands in the

contiguous United States. This unique and scarce habitat has high fish and

wildlife values.

Representativeness: The project footprint is uninhabited. The recommended

plan would restore the interior swamp habitat by restoring natural flow

regimes and using plantings of tree species native to the surrounding area.

Status and trends: The Study Area is exhibiting a decline in habitat.

Connectivity: The Maurepas Swamp complex is the second largest contiguous

coastal forest in Louisiana.

Limiting habitat: The Study Area is considered habitat for bald eagles, Gulf

sturgeon, and West Indian manatee.

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Sustainability of Recommended Plan: As discussed previously, over the 50-

year period of analysis, the RSLR could reduce the long-term functionality and

quality of the swamp habitat found within the Study Area. In order to fully

ascertain the impacts of the proposed actions an analysis of the sustainability of

benefits was performed. The WVA analysis was performed on all three scenarios of

predicted sea level rise for the NER plan and the recommended plan. Both the

recommended plan and NER reacted similarly and are expected to have similar

sustainability. As shown in Table 3-17, benefits would decrease by 7% and 10% for

the intermediate and high RSLR estimates, respectively. Benefits provided by the

WVA model for the No Action Alternative and the recommended plan, in terms of

nonannualized habitat units (HUs) are shown in Figure 3-9.

Table 3-17: Effect of RSLR on Alternatives

Alternative Low SLR

(AAHUs)

Intermediate RSLR

(AAHUs)

High RSLR

(AAHUs)

33 679 640 610

39 1,602 1,516 1,452

Note: SLR = sea level rise; RSLR = relative sea level rise

The results also show that the impacts resulting from RSLR are fairly consistent for

all estimates of RSLR and appear to begin near year 20 of the period of analysis.

Furthermore, for all three estimates of RSLR, the amount of benefits observed

appear to stabilize near year 25, with a continued, but gradual increase in benefits

over the next 25 years. This is an indicator that the proposed action achieves

sustainability for the remainder of the period of analysis, with no reduction in

benefits present.

Figure 3-9: Comparison of HUs over the period of analysis

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Even though RSLR does impact the area over the 50-year period of analysis,

benefits are observed in the short-term and maintained in the long-term frames of

analysis. In addition, accretion would increase with added tree growth and canopy,

but was not included in the analysis of RSLR shown in Figure 3-9. It is estimated

that the net accretion rate would be 8mm/year within the healthiest portions of the

Study Area (Bernard Wood, pers comm, 2009). Based on these estimates, accretion

rates could reduce the potential impacts of sea level rise within the healthiest

portions of the Study Area, thereby adding to the sustainability of the recommended

plan.

3.4.8.2 Design, Environmental, and Construction Considerations

Alternative 33(Recommended Plan) includes cuts in the north dredged material

berms along with bifurcated conveyance channels to reduce impoundment and

increase hydrologic connectivity between the ARDC and subunits NE-1 and NE-2.

All cut locations were placed to maximize the potential for flow into and out of the

impounded swamp habitat. Additionally, one cut is placed in the existing railroad

grade to further reduce impoundment and improve sheet flow within these areas.

All material dredged during construction of the conveyance channels would be

placed along the channels, with gaps included, to allow sufficient sheet flow to be

conveyed from the swamp.

The cross-sectional dimensions of the conveyance channels were designed to mimic

natural cuts found within the southern portion of SE-2 and along Blind River.

These natural cuts facilitate drainage for an area similar in size to those required in

NE-2 and are considered to be in a state of hydrologic equilibrium. The surveys of

the existing channels are presented in Volume II, Section 3. These cuts represent

natural equilibrium dimensions that have formed based on drainage requirements

similar to the hydrologic subunits involved in this restoration study. Additional

cross-sectional area was provided for the cut portion within the existing dredged

material berms, so as to allow high-water flows through this portion of proposed

conveyance system.

Vegetative plantings are added to the most highly degraded areas within NE-2 to

increase the potential for reversing habitat conversion and to further stabilize all

restoration activities within this portion of the study area. These plantings would

be implemented in two phases. A primary planting would be implemented in the

designated areas one year after the earthmoving phase of construction is completed.

The period of time between excavation and the primary plantings would allow the

disturbed material to compact into a more suitable substrate. This time would also

allow for the determination of an appropriate planting scheme. Sixteen months

after the primary plantings are completed, a mortality analysis would be conducted

to establish the quantity of plantings required for the secondary planting. It is

assumed that 50% of the initial plantings would perish. Four months after this

determination is made, a secondary planting would be implemented. Both the

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primary and secondary plantings would consist of 173 trees per acre. Each acre

planted would be composed of 75% bare-root, 15% 1-gallon potted, and 10% 3-gallon

potted plants. These plantings are considered an important component of the

restoration design due to the native regeneration they would provide for the highly

degraded areas of impact. Additionally, these plantings would provide a needed

seed source, prevent invasive species encroachment, and facilitate near-term

restoration within the study area. The planting should only occur during the nongrowing season (November to March), and it is recommended that at least 1 year

elapse after construction before planting such that soils in the impounded areas

could consolidate and the dredged material berms reach a stable elevation. The

plant list for the dredged material areas would be developed based upon this final

elevation.

3.4.8.3 Real Estate Requirements

Construction of Alternative 33 (Recommended Plan) would require the acquisition

of easements to allow for the construction of the project and to ensure that all

project benefits are protected. These real estate acquisitions include flowage,

wetland, and channel easements for the appropriate portions of the construction

footprint and are further described in Volume II, Appendix J.

3.4.8.4 Operation and Maintenance Considerations

OMRR&R requirements for Alternative 33 (Recommended Plan) include a yearly

inspection of the bank opening locations and conveyance channels to ensure that

there are no flow interruptions, such as from debris or fallen trees. Upon

inspection, it would be determined if blockage removal or some other appropriate

remedial operation is required. The conveyance channels would be naturally

altered over time, eventually reaching a state of hydrologic equilibrium similar to

the relict channels that they were designed to mimic. These changes would not

reduce the expected benefits the recommended plan. Therefore, it is anticipated

that little to no attempt to maintain the depth or shoreline geometry of the

conveyance channels would be necessary once they stabilize. The non-Federal

sponsor would be required to enforce any restrictions as identified in the easements

to ensure that the benefits are retained.

3.4.8.5 Monitoring Plan and Adaptive Management

3.4.8.5.1 Description of Monitoring Activity and Adaptive Management

Monitoring is critical to understanding how effective a project is with respect to

meeting its goals and objectives. Project and system level objectives must be

identified to determine appropriate indicators to monitor. A feasibility level

monitoring and adaptive management plan has been developed for the project

(Volume II, Appendix I). The monitoring and adaptive management plan was

developed to include the proposed monitoring and to consider and identify any

necessary adaptive management activities. The plan also estimates the costs and

duration of the monitoring and applicable adaptive management components.

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In the case of the LCA ARDC Modification project, the following questions were

considered to determine if adaptive management should be applied to the project. A

“NO” answer to questions 1 through 3 and a “YES” answer to question 4 indentify

the project as a candidate that could benefit from adaptive management.

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 be readily identified?

3. Are the measures of this restoration project’s performance well understood

and agreed upon by all parties?

4. Can project management actions be adjusted in relation to monitoring

results?

Answers to questions 1 through 3 were “NO.” However, the Adaptive Management

Framework Team determined that the Amite River Diversion Canal Modification

project was not a good candidate for adaptive management because there are no

actions that could be taken in response to monitoring results that the USACE would

define as adaptive management actions. That is, the answer to question 4 is “NO.”

Although some activities could be conducted to adjust project performance, these

actions would not be considered adaptive management activities. O&M for the

selected plan includes a yearly inspection of the bank opening locations and

conveyance channels to ensure that there are no flow interruptions, such as from

debris or fallen trees, which could improve project performance. However if

monitoring data indicate that actions beyond yearly O&M (i.e changing the shape,

size, branching, or number of conveyances channels or gaps) would be needed these

would be considered structural changes and are beyond the adaptive management

authority. The USACE and State of Louisiana can initiate the process for

developing a new water resources project or pursue a design deficiency under the

constructed project. The Framework Team also considered opportunities for active

adaptive management by designing the project as a management experiment. The

Team determined there were minimal active adaptive management opportunities

for the project and that any lessons learned would be limited and would not likely

apply to other coastal Louisiana restoration projects. While there are currently no

apparent adaptive management opportunities, the Adaptive Management Planning

Team can examine the performance of the project in the future. If it is determined

during PED that adaptive management could help achieve any unfulfilled project

objectives, the Team can recommend adaptive management for the project at that

time.

Independent of adaptive management, an effective monitoring program would be

required to determine if the project outcomes are consistent with original project

goals and objectives. The power of a monitoring program developed to support

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adaptive management lies in the establishment of feedback between continued

project monitoring and corresponding project management. A carefully designed

monitoring program is central to properly assessing the effects of the LCA ARDC

Modification Project.

3.4.8.5.2 Performance Measures for Monitoring

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 needs to help further

understand and corroborate project effects.

Objective 1: Increase hydrologic connectivity between the degraded swamp and

bottomland hardwood habitats within the study area and the ARDC by increasing

the exchange of freshwater, sediments, and nutrients.

Performance Measure 1: Freshwater distribution during operational

events

Desired Outcome: Increase hydrologic connectivity and area of extent of

freshwater movement into Study Area above pre-project conditions.

Monitoring Design: Synoptic hydrologic surveys, using salinity,

temperature, dissolved oxygen, and velocity as tracers, would be conducted

during selected low flow and high flow operational events to track

distribution of freshwater. Sampling would be conducted twice annually in

the first 3 years and as required thereafter.

Objective 2: Facilitate natural hydrologic cycles within the study area by reducing

impoundment in degraded swamp and bottomland hardwood habitats adjacent to

the ARDC which would improve tree productivity and seedling germination.

Performance Measure 2a: Swamp vegetation production and extent.

Desired Outcome: Increase in basal area increment of bald cypress and

tupelo in the swamp from existing conditions (existing conditions defined

from preconstruction measurements from coastwide reference monitoring

system (CRMS) and Southeastern Louisiana University historical

monitoring).

Monitoring Design: Diameter at breast height and overstory tree cover

would be measured in the fall in 2 preconstruction years and 4 postconstruction years (within the first 10 years).

Performance Measure 2b: Number of bald cypress and tupelo saplings.

Desired Outcome: A 25% increase in the number of naturally recruited bald

cypress and tupelo saplings per acre from pre-project conditions 10 years

after project implementation. Performance of this measure is most dependent

on achieving extended dry periods in the swamp.

Monitoring Design: Understory vegetation (herbaceous, seedling, and

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construction years (within the first 10 years) to assess regeneration and

changes in cover classes.

Performance Measure 2c: Depth, duration and frequency of flooding in the

swamp.

Desired Outcome: Increase or decrease from pre-project conditions average

flood durations (existing conditions defined from preconstruction

measurements from CRMS-Wetlands stations).

Desired Outcome: Maintain dry periods (moist soils) in the swamp for a

minimum 7-35 days during summer and early fall for seed germination and

maintain water levels below seedling height to promote seedling survival.

Monitoring Design: Water-level recorders would be deployed in six key

areas to measure water depths at the needed frequencies. Recorders would be

established 3 years prior to construction to determine existing conditions and

would be monitored for 10 years post-construction or until desired outcomes

are achieved.

Supporting Information Need: A deep rod-surface elevation table rod

would be installed where hydrologic measurements are taken to establish an

elevation benchmark.

Objective 3: Reduce habitat conversion from swamp to marsh and open water

within the study area.

Performance Measure 3: Habitat and land:water classification

Desired Outcome: Maintaining immediate preconstruction acreage of bald

cypress-tupelo swamp acreage after 10 years.

Monitoring Design: Habitats would be classified using Landsat Thematic

Mapper (TM) scenes and Digital Orthophoto Quarter Quadrangles (DOQs) for

1 pre- and 4 post-project years in the Study Area to assess trends in

conversion between swamp, herbaceous marsh, and open water.

Supporting Information Need: Salinity data would be collected in order to

characterize potential salinity stress associated with low water conditions in

the fall, droughts, and intrusions associated with tropical cyclone events.

Objective 4: Improve fish and wildlife habitat within the study area.

Performance Measure 4: No applicable performance measure.

Desired Outcome: Swamp production and hydroperiod measures would be

used to assess this objective.

Monitoring Design: Fish and wildlife habitat is linked to the performance

measures associated with objectives 1-3, focused on improving habitat.

Therefore, no specific monitoring is proposed for this objective.

3.4.8.5.3 Cost and Duration of Monitoring and Adaptive Management

The costs associated with implementing the monitoring and adaptive management

plan were estimated based on currently available data and information developed

during plan formulation as part of the feasibility study. The costs estimated would

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be refined in PED during the development of the detailed monitoring and adaptive

management plans.

The estimated cost for the monitoring program is $2,970,000, based on October 2010

price levels. In accordance with WRDA 2007 Section 2039, the monitoring costs

presented in the report are for the full allowable 10 year period and represent

conservative and comprehensive costs. Section 2039 guidance does allow for the

monitoring to end prior to the 10-year period if the Secretary determines that the

success criteria have been met. The costs presented in the report are for the full 10

year period but monitoring may end prior to the 10 years. The monitoring plans

and costs were developed by the interagency LCA Adaptive Management Planning

Team in conjunction with stakeholders and have been determined to be a

reasonable plan and estimate for the recommended plan and are what is needed

and necessary to be able to determine project success.

3.4.8.6 Effectiveness of Recommended Plan in Meeting Goals and Objectives

The recommended plan meets all of the project goals and objectives.

Objective 1: Increase hydrologic connectivity between the degraded swamp and

bottomland hardwood habitats within the Study Area and the ARDC by increasing

the exchange of freshwater, sediments, and nutrients over the 50-year period of

analysis. With the addition of cuts and conveyance channels, hydraulics and

hydrology (H&H) modeling has shown that hydrologic connectivity would be

increased within the designated areas of impacts for the subunits determined to be

in the most need of restoration. This connectivity would add to the seasonal flows

needed to maintain healthy swamp habitat and would increase the exchange of

sediments and nutrients between the ARDC and the adjacent interior swamp areas.

Objective 2: Reduce habitat conversion of swamp to open water within the Study

Area over the 50-year period of analysis. With implementation of Alternative 33

(Recommended Plan), added conveyance, reduced impoundment, and

implementation of vegetative plantings- would result in a reduction of habitat

conversion to freshwater marsh for 1,602 acres of degraded cypress-tupelo swamp

within the Study Area. It is also anticipated that the regeneration of native swamp

vegetation would be increased with the implementation of this proposed action,

thereby creating a self-sustaining swamp habitat.

Objective 3: Facilitate natural hydrologic cycles within the Study Area over the 50-

year period of analysis by reducing impoundment in degraded swamp and

bottomland hardwood habitats adjacent to the ARDC to improve tree productivity

and seedling germination. The cuts placed within the existing dredged material

berm, along with the conveyance channels, would allow the swamp habitat adjacent

to the ARDC to drain high-salinity waters introduced by tropical storm events and

allow for seasonal hydrologic flow to occur within the areas of impact. The

increased conveyance observed from seasonal hydrology would produce increased

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sheet flow, resulting in nutrient and sediment input allowing for seedling

germination and establishment as well as a flushing action for the areas of impact

within Alternative 33 (Recommended Plan). The resulting reduction in

impoundment would increase the number of dry days occurring within the areas of

impact, in turn increasing seed germination and establishment and promotion of

natural succession.

Objective 4: Improve fish and wildlife habitat within the Study Area over the 50-

year period of analysis. The implementation of Alternative 33 (Recommended Plan)

would improve the ecosystem by creating a net gain of 679 AAHUs within the areas

of impacts. This benefit quantifies habitat improvements for fish and wildlife that

thrive in cypress-tupelo swamp habitat. The placement of the dredged material

from project activities would also provide new areas of bottomland hardwood

habitat for wildlife refuge during high-water periods. The vegetative plantings on

the placed dredged material and within the degraded swamp also provide habitat

diversity and sustainability within the areas of impact.

3.4.8.7 Effectiveness of Recommended Plan on Meeting Environmental

Operating Principles

Alternative 33 (Recommended Plan) would benefit 1,602 acres of cypress-tupelo

swamp habitat, resulting in a net gain of 679 AAHUs with little to no negative

environmental impacts. This would reverse the trend of conversion from swamp to

freshwater marsh habitat within the areas of impact, while adding habitat

sustainability and diversity. The recommended plan provides significant benefits

and has been agreed upon by the PDT, including Federal and state agencies, as

being the most beneficial plan within the authorized cost for the Study Area.

3.4.8.8 Compensatory Mitigation Measures

Implementation of the recommended plan would result in a net gain in wetland

habitat; therefore, compensatory mitigation, as stipulated in Section 404 of the

Clean Water Act, is not required. In order to offset the loss of habitat resulting

from the placement of dredged material within the areas of impact, 5.0 acres of

vegetative plantings of additional tree species, such as sweet gum and live oaks,

would be implemented on the placed material to create bottomland hardwood

habitat. This habitat could be utilized by some wildlife for available land and food

during high-water periods. The addition of these areas also provides habitat

diversity within the areas of impact. The recommended plan would result in a net

gain in habitat units; therefore, no compensatory mitigation for construction of this

project is required.

3.4.9 Risk and Uncertainty

Identification of all risks and uncertainties involved with development and

implementation of Alternative 33 (Recommended Plan) help to develop risk

management techniques and quantify cost estimate contingencies. The following

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risks and uncertainties are involved with development, selection, and construction

of the recommended plan. Regardless of the associated risks, this project has been

developed to feasibility-level standards. The risks associated with the project would

not impact plan selection or significantly alter the analysis of project benefits and

impacts. All risk items associated with the LCA ARDC Modification Project may be

found in Volume II Appendix L.

Accelerated Project Schedule: As stipulated by WRDA 2007, the six projects

listed under Sec 7006(e)(3) were provided with the conditional construction

authorization pending submittal of a favorable Chief’s Report no later than

December 31, 2010. This conditional authorization created a specific schedule that

all LCA projects are required to follow, which creates additional risk. In order to

achieve feasibility-level of detail, all coordination, plan formulation, and data

gathering need to be conducted within the time constraints of the project, which

includes inflexible items such as public review periods and deadlines.

Modeling Uncertainty: Models, such as the WVA model, allow for the prediction

of environmental benefits over periods of time and a range of conditions; however,

they are highly dependent on input from existing data and the use of best

professional judgment. There are uncertainties inherent to the natural processes

quantified by these models. RSLR was determined to be the variable with the most

uncertainty and, therefore, could pose the greatest impact to the modeling results.

In an effort to quantify these impacts, the WVA was performed for all three levels of

RSLR provided by EC 1165-2-211 (USACE, 2009b). Additionally, RSLR and

accretion estimates were utilized when developing the input variables for the WVA

model.

Cost and Schedule Risks: Cost estimates are a key component for the IWR

Planning Suite analysis and in choosing a plan. Cost contingencies are usually

included in estimates of cost to help minimize these risks. Cost contingencies are

typically determined by a full Cost and Scheduling Risk Analysis (CSRA).

Preliminary cost estimates for the recommended plan were below $40 million;

therefore, a full CSRA is not required for the recommended plan, as stipulated in

the USACE Cost and Scheduling Risk Analysis Guidance (ER 1110-2-1302; USACE,

2008a). However, in an effort to identify the applicable cost and schedule risks

inherent with implementation of the recommended plan, much of the process found

within the USACE guidance was utilized. Once all potential areas of risk were

agreed upon by the evaluation team, a Risk Register was created to help qualify and

quantify the potential impacts of these risks. A Monte Carlo simulation (random

occurrence generator) was run on the registry, which yielded the applicable cost

contingency to use for estimating construction costs for Alternative 33

(Recommended Plan). For this study it was determined that the appropriate

contingency is 59%. This cost contingency was applied to all cost accounts

associated with the project except monitoring costs, which already contain a

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contingency cost. The application of the 59% contingency to the applicable accounts

results in an overall project contingency of 31%. Since all alternatives within the

final array are composed of similar management measures and are located within

areas similar in size and characteristics, it was determined that all risk items

formulated in the CSRA would not vary for each proposed action. More details on

the Cost Risk Analysis are found in Volume II, Appendix L.

Subsidence: Based on guidance provided in EC-1165-2-211, subsidence occurs

within the Study Area at a rate of 7.5 mm/yr. Subsidence plays a role in the

occurrence of RSLR and could increase the impacts of storm surge and salinity

spikes, thereby reducing any potential benefits associated with the proposed action.

Subsidence may limit benefits provided by the proposed action. Biomass accretion

associated with healthy swamp habitat may offset the negative impacts resulting

from subsidence and RSLR.

Sea Level Rise: SLR has the ability to affect the coastal regions of the United

States and Louisiana in varying degrees. The result of these potential impacts may

include losses in project effectiveness, failure to achieve project objectives, and

escalating OMRR&R costs. Specifically, within the Study Area, SLR is predicted to

increase from 1.5 ft (0.46 m) to 3.2 ft (0.97 m) over the 50-year period of analysis but

is not expected to negate project performance or benefits. The risks associated with

RSLR were considered in the formulation of all risk items during the CSRA

performed for this project. The risk items in which RSLR were considered pertinent

include vegetative plantings mortality and inaccuracies in the project scope.

Accretion: Healthy freshwater swamps with an established canopy produce

organic buildup known as biomass accretion. Accretion produces a net increase in

the substrate, effectively raising the vertical elevation of the swamp floor. It is

estimated that with a healthy freshwater swamp habitat, the Study Area could

produce 8 mm/yr of biomass accretion (Bernard Wood, pers comm, 2009). Accretion

could help offset the effects of subsidence and RSLR, thereby reducing negative

impacts and increasing the benefits associated with the proposed action.

Risk of Flooding: According to the H&H modeling, it was determined that all

proposed actions would have an insignificant reduction in the stage on the Amite

River and on the ARDC. The modeling also showed an insignificant increase in

stage height within the adjacent swamp area, near the proposed openings in the

ARDC dredged material berms. It was also observed that, under existing

conditions, the interior swamp areas tended to flood during high stage events. The

proposed plan features would not restrict flow in the ARDC or in the swamps

adjacent to the ARDC; therefore, there would not be an increase in the risk of

flooding within the Study Area. Additionally, increased flood risks would not occur

for any nearby businesses and residences as a result of all proposed actions.

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3.4.10 Implementation Requirements

3.4.10.1 Schedule

This project was authorized for construction by the WRDA of 2007, contingent upon

a signed Chief of Engineers Report no later than December 31, 2010. After a signed

Chief’s Report, this project would be eligible for construction funding. The project

would be considered for inclusion in the President’s budget based on national

priorities, magnitude of the Federal commitment, economic and environmental

feasibility, amount of local public support, willingness of the non-Federal sponsor to

fund its share of the project cost, and the budget constraints that may exist at the

time of funding. Once Congress appropriates Federal construction funds, USACE

and the non-Federal sponsor would enter into a project partnership agreement

(PPA). This PPA would define the Federal and non-Federal responsibilities for

implementing, operating, and maintaining the project. USACE would officially

request the sponsor to acquire the necessary real estate requirements immediately

after signing the PPA. The advertisement of the construction contract would follow

the certification of the real estate. The final acceptance and transfer of the project

to the non-Federal sponsor would follow the delivery of an OMRR&R manual and

as-built drawings. Design considerations were discussed in Section 3.4.8.2. The

estimated schedule for project construction is shown in Table 3-18.

Table 3-18: LCA ARDC Modification Project Implementation Schedule

Milestone Baseline Date

Begin Preconstruction Engineering and Design 2010

Initiation of Monitoring Program 2010

USACE and non-Federal sponsor negotiate PPA 2012

Complete Plans and Specifications 2012

Real Estate Acquisition 2012

Award Contract 2012

Construction Start 2012

Complete Construction- Earthwork 2012

Complete 1st Vegetation Planting 2015

Complete 2nd Vegetation Planting 2018

Turn over Project to Local Sponsor 2018

Complete Monitoring Program 2023

3.4.10.2 Implementation Responsibilities

In addition to cost sharing as described in Section 3.4.8.3, there are a number of

other requirements established by Federal laws and policies that are to be provided

by the non-Federal sponsor. The local cooperation requirements and non-Federal

obligations are specified in Volume II, Section 3.9.2.

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3.4.10.3 Cost Sharing

The State of Louisiana, acting through the CPRA, would be the non-Federal sponsor

for the LCA ARDC Modification Project. Following the feasibility phase, the cost

share for the planning, design and construction of the project would 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. OMRR&R of the project would be a 100% CPRA responsibility. Table 3-19

shows the cost share amounts for the recommended plan.

Table 3-19: Cost Share Amounts for the Recommended Plan

Project Feature Total Cost Non-Federal Federal

% Cost % Cost

Total First Cost of

Construction $8,136,000 a 35 $2,848,000 65 $5,288,000

LERRD Credit $180,000 100 $180,000 0 $0

Monitoring & Adaptive

Management $2,970,000 35 $1,040,000 65 $1,930,000

OMRR&R b $10,000 100 $10,000 0 $0

aTotal first cost of construction is based on the sum of the planning, engineering, and design; construction management (i.e.

supervisions and administration); LERRDs; and monitoring and adaptive management and is based on October 2010 price

levels.

b

*Costs in this table represent first costs not the fully funded cost through the mid-point of construction ($8,540,000)

Average annual cost based on October 2010 price levels.

The State of Louisiana is in full support of the LCA ARDC Modification Project at

the current cost share ratio of 65% Federal, 35% non-Federal, with operations,

maintenance, repair, replacement and rehabilitation being a 100% non-Federal

responsibility, as required in WRDA 2007. Additionally, project monitoring and any

Adaptive Management deemed necessary would be cost shared at 65/35 for the first

ten years of the period of analysis.

3.4.10.4 Environmental Commitments

The USACE, non-Federal sponsor, and all contractors would commit to following all

laws and Executive Orders and to avoid and minimize adverse impacts to the

environment by the following:

Employ necessary best management practices (BMPs) to reduce erosion and

sedimentation during construction. The plans and specifications would

include such BMPs and erosion control measures as necessary. The

contractor would be required to develop a Storm Water Pollution Prevention

Plan that would be coordinated through the LDEQ.

The contractor would be made aware of any practices or measures need to be

compliant with the Endangered Species Act.

The contractor would be made aware of any practices or measures to protect

cultural resources.

The USACE and the non-Federal sponsor agree to maintain coordination

with the USFWS and the LDEQ to ensure compliance with all laws and

executive orders.

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The contractor would be prohibited from dumping oil, fuel, or other

hazardous substances and would require that all appropriate sanitation

measures are followed. The contractor would be to develop a Spill Prevention

Control and Countermeasure plan.

3.5 Public Involvement *

3.5.1 National Environmental Policy Act Scoping

A Notice of Intent (NOI) to prepare an SEIS for the LCA ARDC Modification Project

was published in the Federal Register in December 2008. A scoping meeting for the

project was conducted in February 2009. Additional meetings have occurred with

large landowners, NGOs, and the parishes.

Common themes of the comments included the following:

Weir at French Settlement does not function properly and diverts excessive

flow to ARDC, impairing lower Amite River.

Project should incorporate weir construction at downstream end of ARDC.

ARDC construction has disrupted natural hydrologic regime and damaged

properties.

Endangered/protected species are present in the Study Area and vicinity.

Scope of project should address wildlife and fisheries habitat.

Hydrology and hydraulics modeling should be expansive, incorporate

conditions from other projects, and/or involve stage data collection.

The Draft FS/SEIS was released to the public in May 2010, followed by a 45-day

public review period, which included a public meeting. Public comments were

received during the scoping meeting and Draft FS/SEIS public review. Public

comments have been incorporated into the report throughout the report

development. Comments received and the responses to them are included in

Appendix G of Volume II.

3.5.2 Other Public Comments, Areas of Controversy, Unresolved

Issues

Meetings and discussions with the public; local, state and Federal agencies; and the

LCA ARDC Modification PDT indicate support for the project and did not identify

any areas of controversy or unresolved issues.

3.6 Coordination and Compliance *

3.6.1 U.S. Army Corps of Engineers Principles and Guidelines

This chapter documents the coordination and compliance efforts regarding statutory

authorities including environmental laws, regulations, Executive Orders, policies,

rules, and guidance. Consistency of the recommended plan with other Louisiana

coastal restoration efforts is also described.

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3.6.2 Environmental Coordination and Compliance

Coordination and compliance efforts were conducted regarding statutory

authorities. These include environmental laws, regulations, Executive Orders,

policies, rules, and guidance applicable to this project. Full compliance with

statutory authorities would be accomplished upon review of the integrated FS/SEIS

by appropriate agencies and the public and the signing of the ROD.

The USACE has coordinated with the USFWS, NMFS, and the LDWF per the Fish

and Wildlife Coordination Act (48 Stat. 401, as amended; 16 U.S.C. 661 et seq.). A

final Coordination Act letter report (CAR) has been received and the comments

incorporated into the project plan as appropriate. Accordingly, the USFWS

supports implementation of Alternative 33 provided the following fish and wildlife

recommendations are implemented concurrently with project implementation. The

USACE concurred with the recommendations; discussion of the recommendation is

provided in Volume II.

State certifications for coastal zone consistency and 401 water quality have also

been received.

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4.0 CONVEY ATCHAFALAYA RIVER WATER TO NORTHERN

TERRBONNE MARSHES AND MULTIPURPOSE

OPERATION OF HOUMA NAVIGATION LOCK

4.1 Purpose and Scope*

This is a summary of the FS/SEIS for the LCA ARTM and MOHNL Project (Volume

III). As described in Section 1.4, the LCA ARTM and LCA MOHNL Project

analyses were combined into one FS/SEIS. The joint project is referred to as the

LCA ARTM Project.

The purpose of the proposed LCA ARTM Project is to address critical near-term

needs from the 2004 LCA Report for reversing the current trend of marsh

degradation in the Study Area resulting from subsidence and sea level rise, erosion,

saltwater intrusion, and lack of sediment and nutrient deposition. The project

proposes to accomplish this by utilizing freshwater, sediments, and nutrients from

the Atchafalaya River and the Gulf Intracoastal Waterway (GIWW).

The environmental consequences of the proposed project are evaluated in Volume

III and summarized here. The integrated NEPA documentation and SEIS is a

supplement to the FPEIS for the LCA Report (USACE, 2004b). The ROD for the

FPEIS was signed on November 18, 2005. The FPEIS is incorporated by reference.

4.1.1 Study Area Background*

The LCA ARTM Project, located within the Deltaic Plain in LCA Subprovince 3,

provides for the creation, restoration, and sustainment of freshwater habitats

located in southern Louisiana near the city of Houma and Terrebonne Parish. The

study comprises approximately 1,100 square miles bound to the west by the Lower

Atchafalaya River, to the east by the Bayou Lafourche ridge, and to the north by the

Bayou Black ridge. The southern boundary roughly follows the transition between

saline and brackish marsh types (Sasser et al., 2008). Due to its magnitude, the

LCA ARTM Study Area is divided into three subunit areas labeled as the West -

Bayou Penchant Area, Central - Lake Boudreaux Area, and East - Grand Bayou

Area. Subunits were separated by a combination of natural, physical, and

geographic features. Limits of the subunits were developed by the interagency

PDT. The separation of the Study Area allowed the PDT to evaluate specific needs

relative to each subunit. The Study Area is shown in Figure 4-1.

The ecosystems within the West - Bayou Penchant Area can be characterized as

mostly forested swamps between the GIWW and Bayou Black, floating freshwater

marsh systems throughout the Penchant Basin, and intermediate marsh systems

starting in the vicinity of Lake de Cade. Brackish marsh systems are also within

the subunit, south of the intermediate zone.

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The Central - Lake Boudreaux Area Subunit, measuring approximately 210 square

miles, extends south of the GIWW at Houma, Louisiana, and includes the Houma

Navigation Canal (HNC). The limits of the subunit border the West - Bayou

Penchant Area Subunit along Bayou du Large. The eastern limit of the Central -

Lake Boudreaux Area Subunit consists of Bayou Terrebonne. The land cover within

the Central - Lake Boudreaux Area can be characterized as mostly urban and

agriculture along Bayou Du Large, Bayou Grand Caillou, Bayou Petit Caillou, and

Bayou Terrebonne. Between the bayous, the stratification of ecosystems shifts from

forested swamps in the north to freshwater marsh systems to intermediate marsh

systems. Brackish marshes are found around and south of Lake Boudreaux.

The East - Grand Bayou Area Subunit is located south of Larose, Louisiana, and

measures approximately 185 square miles. The LCA ARTM PDT identified the

northern limits of this study unit as the GIWW, the western limits to be Bayou

Terrebonne, and the eastern limits to be the Bayou Lafourche ridge. Major

freshwater delivery features within the East - Grand Bayou Area include the

GIWW, Bayou Pointe au Chien, Grand Bayou, Bayou Blue, Grand Bayou Blue, and

Cutoff Canal. Other significant features that are present within the Study Area

include St. Louis Canal and portions of the Pointe au Chien Wildlife Management

Area.

4.1.1.1 Study Area Significance

Louisiana’s coastline represents 90% of the wetlands in the contiguous United

States and is currently disappearing at an alarming rate. The Study Area is

declining and imperiled. This unique and scarce habitat has high fish and wildlife

values. The Terrebonne Marshes are one of the largest expanses of critical

freshwater marsh habitat in Louisiana. The Terrebonne Marshes are also a

valuable stopover habitat for migratory birds. With the loss of these marshes, this

valuable stopover habitat for migratory birds is lost as well.

4.1.2 History of Investigation

This study is designed to address general ecosystem restoration problems and

opportunities in the Study Area. These have been documented since 1998 through

numerous comprehensive planning studies. Specifically, this study builds upon the

following comprehensive planning efforts for the Louisiana coastal areas:

Coast 2050 Plan (1999);

LCA Report (2004);

Integrated Ecosystem Restoration and Hurricane Protection: Louisiana’s

Comprehensive Master Plan for a Sustainable Coast (LACPR, 2007); and

Louisiana Coastal Protection and Restoration (LACPR) Technical Report

(USACE, 2009c)

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These comprehensive planning studies are discussed in Volume III and summarized

below. Planning for this study utilizes data from these reports, and alternative

plans were formulated in coordination with these plans.

4.1.3 Prior Reports and Existing Projects

A number of prior water resources development efforts are relevant to the LCA

Program. Restoration feature type and location, engineering design, construction

techniques, and performance metrics from these prior efforts have been assessed

and are being considered throughout the study plan formulation process. Table 4-1

lists these efforts and denotes how each is relevant to the LCA ARTM Project.

Table 4-1: Relevance of Prior Studies, Reports, Programs, and Water

Projects to the ARTM Feasibility Study

Prior Studies, Reports, Programs, and Water

Projects

Relevance to ARTM Ecosystem

Restoration

a

Data Source

Consistency

Hard-Structural

Measures

Soft-Structural

Measures

Future Without

Project

Condition

Comprehensive Planning Studies

Coast 2050 Plan, 1999 X X X

Louisiana’s Comprehensive Master Plan for a

Sustainable Coast, 2007 XX X X X

LACPR Technical Plan, 2009 X X X

LCA Report (2004) X X X X X

Prior Studies, Reports, and Water Projects

GIWW, 1826 and other dates X X

Atchafalaya Basin X X

MR&T, 1928 X X

Mississippi River Gulf Outlet, September 1956 X

Morganza to the Gulf X X X X X

Donaldsonville, LA to the Gulf of Mexico X X X X X

Third Delta X X X X

Cooperative River Basin studies X X X X X

Watershed reports X X X

Measures undertaken pursuant to the authorization

provided under the heading “Operation and

Maintenance” in Title I, Chapter 3 of Division B of

Public Law 109-148, as modified by Section 2304

Title II, Chapter 3 of Public Law 109-234, 2006

X X X

Mississippi and Louisiana Estuarine Areas, 1984 X X

Louisiana Coastal Area Louisiana,

Shore and Barrier Island Erosion, 1984 X X

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Prior Studies, Reports, Programs, and Water

Projects

Relevance to ARTM Ecosystem

Restoration

a

Data Source

Consistency

Hard-Structural

Measures

Soft-Structural

Measures

Future Without

Project

Condition

Mississippi River Delta Study, 1990 X X

Louisiana Coastal Area, Louisiana, Water Supply,

1984 X X

Louisiana Coastal Area, Hurricane Protection, 1989 X X

Louisiana-Texas Intracoastal Waterway, New

Orleans, Louisiana to Corpus Christi, Texas, 1942 X X X

Mississippi River, Baton Rouge to the Gulf of

Mexico, Louisiana, 1945 X X

Barataria Bay, Louisiana, 1958 X X

Hydrologic and Geologic Studies of Coastal

Louisiana, 1973 X X

Mississippi Deltaic Plain Region Ecological

Characterization, 1980 X X

Deep-Draft Access to the Ports of New Orleans and

Baton Rouge, Louisiana, 1981 X X X

Louisiana’s Eroding Coastline: Recommendations

for Protection, 1982 XX X

Proceedings of the Conference on Coastal Erosion

and Wetland Modification in Louisiana: Causes,

Consequences, and Options, 1982

X XX X

Louisiana Barrier Shoreline Feasibility Study, 1996 X X

Mississippi River Sediment, Nutrient and

Freshwater Redistribution Feasibility Study, 2000 XX X

Atchafalaya River and Bayous Chene, Boeuf, and

Black, Louisiana Feasibility Study XX X X X

Old River complex X X X X

Caernarvon Freshwater Diversion X X X X

Davis Pond Freshwater Diversion X X X X X

CWPPRA Projects Constructed or Under

Construction XX X X X

CWPPRA Projects Authorized for Construction X X X X X

Greater New Orleans Hurricane and Storm Damage

Risk Reduction System X X X

Related Laws and Programs

USACE Continuing Authorities Program, 1996 X

CIAP, 2001 & 2005 X X X X

Second Emergency Supplemental Appropriations

Act to Meet the Immediate Needs Arising from the

Consequences of Hurricane Katrina, 2005 (Public

Law 109-062)

X X X

Department of Defense, Emergency Supplemental X X X X

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Prior Studies, Reports, Programs, and Water

Projects

Relevance to ARTM Ecosystem

Restoration

a

Data Source

Consistency

Hard-Structural

Measures

Soft-Structural

Measures

Future Without

Project

Condition

Appropriations to Address Hurricanes in the Gulf of

Mexico, and Pandemic Influenza Act, 2006 (Public

Law 109-148)

Emergency Supplemental Appropriations Act for

Defense, the Global War on Terror, and Hurricane

Recovery, 2006 (Public Law 109-234)

XX X X X

aAdditional studies are included in the FS/SEIS (Volume III).

4.1.3.1 Federal

Several comprehensive planning efforts have significance to the LCA ARTM

Feasibility Study, including the Coast 2050 Plan, Louisiana’s Comprehensive

Master Plan for a Sustainable Coast, and the LACPR technical report. These

comprehensive planning efforts are described below in chronological order.

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 reflects 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, which preceded the LCA Report (2004).

LCA Report, 2004: In 2000, the USACE and State of Louisiana initiated the LCA

Report to address Louisiana’s 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 contribute to the

economy and well being of the nation. The LCA Report 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. The LCA Report and FPEIS

were completed in 2004. Reports produced under the LCA ARTM Study will be

supplements to those documents. The 2004 LCA Report and FPEIS are

incorporated by reference into this document.

In the Fish and Wildlife Coordination Report for the LCA Report FPEIS, the

projects were described as follows (USACE, 2004b):

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Convey Atchafalaya River Water to Northern Terrebonne Marshes includes a

number of features to improve the distribution of freshwater to deteriorated

Terrebonne Basin marshes via the GIWW. Construction of new channels and

enlargement of existing channels would increase seasonal flows of

Atchafalaya River water to central (Lake Boudreaux) and eastern (Grand

Bayou) Terrebonne marshes. All channel alternatives would include a gated

control structure to restrict saltwater intrusion during low river stages. The

project also includes features to increase the supply of Atchafalaya River

within the GIWW include repairing banks along the GIWW, enlarging

constrictions in the GIWW, and possibly diverting additional freshwater from

Bayou Shaffer into Avoca Island Lake provided there are no negative impacts

to Penchant Basin marshes. Those features would increase suspended

sediment supply to Bayou Penchant and other wetlands receiving the

Atchafalaya River water via the GIWW.

Multi-purpose Operation of HNC Lock consists of operating the proposed

Houma Navigation Canal Lock located at the southern end of the HNC, for

multiple purposes, rather than for navigation only. The Corps’ Morganza to

the Gulf Hurricane Protection Study includes construction of the lock, but

does not include the multi-purpose operation of the lock. This restoration

feature would reduce saltwater intrusion, modify water circulation in the

HNC to increase the distribution of Atchafalaya River water within

Terrebonne Basin wetlands, especially within the Lake Boudreaux area

wetlands to the north; the Lake Decade wetlands to the west; and the Grand

Bayou wetlands to the east.

LACPR, 2009: The LACPR technical report includes analysis and concepts for

coastal restoration and Category 5 hurricane risk reduction, exclusive of normal

policy. The USACE submitted a Preliminary Technical Report to Congress in July

2006. A Final Technical Report now under review includes different alignments of

structural measures, such as floodgates, floodwalls, and levees, to compare relative

reduction of risk of flooding and storm surge, including the possibility of structural

measures affecting the LCA ARTM Project. The Final Technical Report also

includes nonstructural measures, such as elevating homes. In addition, the

investigation reviews various wetland restoration measures and highlights the role

of wetlands in coastal risk reduction. A Final Technical Report was sent to USACE

Mississippi Valley Division (MVD) and USACE Headquarters for review December

2008 and currently is undergoing independent external peer review.

Morganza to the Gulf: The Morganza to the Gulf Hurricane Risk Reduction

Project is located in coastal Louisiana approximately 60 miles southwest of New

Orleans and includes portions of Terrebonne and Lafourche parishes. The project

consists of 72 authorized miles of levees and structures; approximately 80% of the

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authorized alignment overlays existing hydrologic barriers. The Morganza to the

Gulf project was authorized to provide 100-year level of hurricane and storm

damage risk reduction based on feasibility reports and Reports of the Chief of

Engineers in 2002 and 2003, prior to development and implementation of postKatrina design criteria.

The authorized hurricane protection plan consisted of approximately 72-miles of

earthen levee, 10 56-foot-wide sector gate structures, three 125-feet-wide floodgates,

13-tidal exchange structures, and a lock complex consisting of a lock in the HNC

measuring 110 feet wide by 800 feet long, an adjoining floodgate measuring 250 feet

wide and a dam closure. The structural features are integrated into the levee

alignment to provide flood protection, drainage, environmental benefit, and

navigational passage.

A Post Authorization Change (PAC) Report is being developed to seek

reauthorization. The PAC Report will evaluate benefits and costs for the authorized

project alternative (post-Katrina 35-year level of risk reduction) and for the postKatrina 100-year alternative. The alternative with the greatest net benefits will be

selected as the recommended plan and then feasibility-level designs and costs will

be completed for that plan.

A Revised Programmatic EIS (RPEIS) will be prepared for concurrent submittal

with the PAC Report. The RPEIS will document changes in existing conditions and

evaluate all direct and indirect environmental impacts of increased levee footprints

resulting from the post-Katrina design criteria. The RPEIS will include sufficient

detail for any constructible features (e.g., HNC Lock Complex) so that no additional

environmental clearances will be required for those features upon signing of the

ROD.

The HNC Lock Complex is a feature of the Morganza to the Gulf of Mexico

Hurricane Protection Project. It consists of a 110-foot by 800-foot lock, an adjacent

250 foot-wide sector gate, and a dam closure that tie into adjacent earthen levees to

reduce the risk of storm surge traveling up the HNC. Vessel traffic will pass

through the sector gate portion of the structure for the majority of conditions.

However, when the sector gates are closed, the lock will be utilized. The sector

gates will be closed to control chloride levels at the Houma water treatment plant

and to reduce risk from storm surge.

The 50% design and specifications on the HNC Lock Complex was complete in July

2008. Design efforts on the lock will continue pending a favorable economic

analysis at the MVD Commander’s review conference, selection of a recommended

plan (establish design elevation), and receipt of additional funds. The USACE is not

authorized to construct the HNC Lock Complex as an independent, free-standing

project or as a separable element of the Morganza to the Gulf project. The

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Morganza to the Gulf Hurricane Protection Project is NOT part of the Southeast

Louisiana Hurricane and Storm Damage Risk Reduction System (HSDRRS).

The local sponsor is moving ahead with plans to build an interim risk reduction

system along the authorized alignment in advance of Morganza to the Gulf. The

general plan is to construct first lift levees to an elevation of 10 feet and install

temporary barge gate structures, all under the regular USACE permit process. The

local sponsor desires to receive Work In Kind (WIK) credit for the interim work.

The local sponsor has completed construction of the first lift for Reach J-1, as

authorized in FY 04 Appropriations Act. The local sponsor is 80% complete in

constructing the first lift for levee Reach H-3 and is 10% complete in constructing

the first lift for Reach H-2. The remainder of the project is in PED.

The Morganza to the Gulf project is included in the LACPR study as Planning Unit

3-a and is part of this comprehensive system to provide higher levels of protection

for the Morganza area.

As of July 2010, the following provides a status of portions of the Morganza to the

Gulf project:

Levee Reach J-1, First Lift, complete (WIK)

Features under construction

Levee Reach H-3, First Lift, 80% complete (WIK)

Levee Reach H-2, First Lift, 10% complete (WIK)

Pointe Aux Chenes Levee, First Lift, 100% Plans and Specifications (P&S)

(WIK)

Features under Design

Levee Reach J-2, First Lift, 95% P&S (WIK)

HNC Lock and Floodgate, 50% P&S complete July 2008

Levee Reach F-1, 25% Design Documentation Report (DDR)

Levee Reach G-1, 35% DDR

Bayou Grand Caillou Floodgate, 35% DDR

Prior studies, reports, and projects: In addition to the comprehensive planning

efforts described above, the studies, reports, and projects listed in Table 4-1 are

relevant to the LCA ARTM Feasibility Study as noted. Applicable laws and

programs are summarized 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.

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CWPPRA, 1990: The CWPPRA of 1990 was the first Federal statutory mandate

for restoration of Louisiana’s coastal wetlands. The CWPPRA Task Force is

composed of five Federal agencies (USEPA, USFWS, USACE, NMFS, and Natural

Resources Conservation Service (NRCS)) and the State of Louisiana. The authority

required preparation of 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. CWPPRA

provides funds annually for coastal restoration planning and the construction of

coastal protection and restoration projects. As of July 2008, 145 active CWPPRA

projects had been approved, 74 had been constructed, 17 were under construction,

and 26 had been de-authorized or transferred to other programs. The CWPPRA

program anticipates receiving $84M in Federal funds for FY 2009.

USACE Continuing Authorities Program, 1996: Section 204 of the WRDA

1992, as amended in WRDA 2007 Section 2037, is a "continuing authority" that

authorizes the Secretary of the Army to plan, design, and implement certain

ecosystem restoration measures, subject to specified cost sharing, cooperation, and

positive Secretarial findings without additional project-specific congressional

authorization. Section 204 as amended authorizes the beneficial use of sediments

in connection with construction, operation, or maintenance dredging of an

authorized Federal water resources project.

CIAP, 2001 and 2005: CIAP originally was authorized by Congress in 2001 in the

OCS Lands Act, as amended (31 U.S.C. 6301-6305). Section 384 of the Energy

Policy Act of 2005 (Public Law 109-58) authorized CIAP funds to be distributed to

OCS oil and gas producing states to mitigate the impacts of OCS oil and gas

activities for FY 2007 through FY 2010. The state liaison for this program in

Louisiana is the CPRA. The CIAP allocations have been used to fund various state

and local coastal activities and projects including: monitoring, assessment, research,

and planning; habitat, water quality, and wetland restoration; coastline erosion

control; and control of invasive nonnative plant and animal species.

Second Emergency Supplemental Appropriations Act to Meet the

Immediate Needs Arising from the Consequences of Hurricane Katrina,

2005 (Public Law 109-062): The Second Emergency Supplemental Appropriations

Act to Meet the Immediate Needs Arising from the Consequences of Hurricane

Katrina, 2005 (Public Law 109-062) was adopted by Congress on September 2, 2005.

This law provided emergency supplemental funding to repair damage to flood risk

management and hurricane shore protection projects.

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Department of Defense, Emergency Supplemental Appropriations to

Address Hurricanes in the Gulf of Mexico, and Pandemic Influenza Act,

2006 (Public Law 109-148): The Department of Defense, Emergency

Supplemental Appropriations to Address Hurricanes in the Gulf of Mexico, and

Pandemic Influenza Act, 2006 (Public Law 109-148), provided funds for the LACPR

efforts.

4.1.3.2 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 CZM 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.

Louisiana Coastal Wetlands Conservation, Restoration and Management

Act, 1989: In 1989, the constitution of the State of Louisiana was amended with

enactment 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,

designated 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. When the CPRA was formed in 2005, it assumed this

responsibility.

Act 6 also created the Wetlands Conservation and Restoration Fund (WCRF), which

dedicates a portion of the state’s revenues from severance taxes on mineral

production (e.g., oil, gas) to finance coastal restoration activities and projects.

Currently, the WCRF provides approximately $25 M 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 risk

management and wetland restoration.

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 CPRA to develop, implement, make reports

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on, and provide oversight for a comprehensive coastal protection master plan and

annual coastal protection plans.

4.1.3.3 Local

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

concerned primarily with preservation. The restoration activities of these

organizations will support the overall goals of the LCA ARTM Project; however,

these efforts are small in scale and will not appreciably influence plan formulation.

4.1.3.4 Existing and Likely Future Water Projects

Several existing and authorized navigation, river flood risk management, hurricane

storm surge risk reduction, coastal restoration, and multipurpose O&M projects are

related to the LCA ARTM Project. These projects are briefly described below.

Navigation Projects

GIWW: The GIWW traces the U.S. coast along the Gulf of Mexico from

Apalachicola Bay near Carrabelle, Florida, to the U.S.-Mexico border at

Brownsville, Texas. The waterway extends approximately 376 miles east and

approximately 690 miles west of the Mississippi River. The GIWW runs

contiguously through the LCA ARTM Study Area from Bayou Lafourche through

Houma and on to Morgan City.

HNC: The HNC is a 36.6-mile navigation channel that begins at the GIWW in

Houma, Louisiana, and extends southward to the Gulf of Mexico. Terrebonne

Parish constructed the canal in 1962 to provide direct access to the nearby resources

of the Gulf of Mexico. The channel was originally constructed with a usable

dimension of 15 ft by 150 ft from the GIWW to mile 0.0 of the HNC and an 18-foot

contour to the Gulf of Mexico. The River and Harbor Act of October 23, 1962,

provided for the maintenance of the HNC by the Federal government. Maintenance

by the United States was initiated on November 27, 1964.

In accordance with Section 5 of the River and Harbor Act, approved March 4, 1915,

authority was granted on August 23, 1973, to increase the HNC project dimensions

to an elevation of -18 ft Mean Low Gulf by 300 ft in bottom width, between mile 0

and the Gulf of Mexico. This enlargement of the HNC was completed in July 1974.

Presently the USACE is undergoing a study to deepen this channel to either -18 ft

or -20 ft North American Vertical Datum (NAVD) 88.

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Atchafalaya River Deep Draft Channel: The project is located in south-central

Louisiana in Assumption, St. Mary, and Terrebonne parishes, near Morgan City,

Louisiana. It includes the Atchafalaya River and adjacent areas south of Morgan

City; Bayous Chene, Boeuf, and Black and adjacent areas between the Atchafalaya

River and Amelia, Louisiana; and Atchafalaya Bay and the Gulf of Mexico, south of

Morgan City. This project provides for a 20-foot-deep by 400-foot-wide navigation

channel.

Lower Atchafalaya Basin Floodway System: The entire Atchafalaya Basin is

located in south-central Louisiana and extends from the confluence of the

Mississippi, Red and Atchafalaya rivers near Simmesport, Louisiana, to the Gulf of

Mexico south of Morgan City. The 833,000-acre Lower Atchafalaya Basin Floodway

is bounded on the north by U.S. 190, on the east and west by the Atchafalaya Basin

protection levees, and extends south to the Gulf of Mexico. The Lower Atchafalaya

Basin Floodway System project has two mutually supporting goals: to preserve the

habitat of the nation’s largest and oldest river-basin swamp and to ensure that the

Lower Atchafalaya Basin can pass a floodwater of 1.5 million cfs as required by the

MR&T Project.

Hurricane Storm Surge Risk Reduction Projects

Morganza to the Gulf of Mexico Risk Reduction Project: In March 2002, a

feasibility report and PEIS entitled Mississippi River & Tributaries - Morganza,

Louisiana to the Gulf of Mexico Hurricane Protection was prepared by the USACE

(2002). The recommended plan proposed a series of flood protection measures and

included the following:

Construction of approximately 72 miles (116 kilometers) of levee south of

Houma

Construction of nine gated structures in various waterways and three

floodgates in the GIWW

Construction of a lock structure and floodgate complex for the HNC

Construction and operation of new and replacement fish and wildlife

structures in selected locations to maintain tidal exchange

The area to be protected by the levee system is a former major delta from a previous

course of the Mississippi River. As in other locations in south Louisiana, urban and

agricultural development has occurred along the banks of the remnant ridges of the

delta. Therefore, conveyance of freshwater via the Mississippi River through these

remnant channels is not practical. However, the proximity of the area to the

Atchafalaya Basin offers other options of freshwater distribution. The GIWW is

linked to the Atchafalaya Basin and conveys water eastward to the area. The HNC

intercepts these flows before they reach the area of need and conveys them

efficiently to the Gulf of Mexico. If authorized, and with the levee system and water

control structures in place, the Atchafalaya River flows could be managed and

distributed across the area. The proposed Morganza to the Gulf levees and water

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control structures would convey Atchafalaya River water eastward and would

support the efforts proposed within the LCA Report, thus helping solve the

saltwater intrusion problem in the Houma area. This project presents a direct

hydraulic relationship with the LCA ARTM Project.

Coastal Restoration Projects

LCA Projects

An LCA Project that could affect the LCA ARTM is the Beneficial Use of

Dredged Material (BUDMAT) Program. A very promising option for

restoring coastal wetlands and reducing land loss is the beneficial use of

dredged material. USACE MVN (Mississippi Valley Division - New Orleans

District) has the largest annual channel O&M program in the nation and

dredges an average of 70 million cubic yards (MCY) of material annually

during maintenance dredging of navigation channels. Not all of this material

is available for beneficial placement in the coastal ecosystem; however, there

is the potential to use up to 30 MCY annually to enhance coastal wetlands

through marsh creation, wetland nourishment, barrier island restoration,

ridge restoration, and other techniques. The 10 year, $100 million LCA

BUDMAT Program will provide the institutional framework to optimize the

use of dredged material resulting from the maintenance of federally

maintained navigational channels to attain the LCA hydrogeomorphic and

ecosystem objectives. The beneficial use of dredged material could affect the

LCA ARTM Study Area directly by beneficially creating/enhancing marsh

habitat within the Study Area boundary.

LCA Small Bayou Lafourche Reintroduction project could supply

freshwater to the eastern portion of the LCA ARTM Study Area. This

restoration feature would reintroduce flow from the Mississippi River into

Bayou Lafourche. The pumped flow would be continuous and would increase

riverine influence in the wetlands between Bayous Lafourche and

Terrebonne, south of the GIWW. Several alternatives are being considered

that would provide year-round flow into the bayou, including gated culverts

and a pump/siphon station at Donaldsonville, and initial engineering and

design has been initiated under CWPPRA. Additional features that would be

required, regardless of the type of diversion structure built, include

modification of existing infrastructure, bank stabilization, dredging, and

channel improvements. The Bayou Lafourche project could have a

synergistic relationship with the LCA ARTM Project. The two projects could

greatly reduce saltwater intrusion in the eastern Terrebonne Marshes.

Moreover, potential measures to improve distribution of Bayou Lafourche

reintroduction waters (e.g., enlargement of Bayou L’Eau Bleu and/or Grand

Bayou) could facilitate efforts to move Atchafalaya waters into areas of

critical need. Given this positive interrelationship, opportunities to maximize

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synergy between these two projects should be fully evaluated in the

feasibility study for the Bayou Lafourche reintroduction.

LCA Maintain Land Bridge between Caillou Lake and Gulf of Mexico

could affect salinity levels in the LCA ARTM Study Area. This restoration

feature would maintain the land bridge between the Gulf of Mexico and

Caillou Lake by placing shore protection in Grand Bayou du Large to

minimize saltwater intrusion. This feature would involve rock armoring or

marsh creation to plug/fill broken marsh areas on the west bank of lower

Grand Bayou du Large, thereby preventing a new channel from breaching the

bayou bank and allowing a new hydrologic connection with Caillou Lake.

Some gulf shore armoring would be needed to protect the area from erosion

on the gulf shoreline. Gulf shoreline armoring might be required where

shoreline retreat and loss of shoreline oyster reefs has allowed increased

water exchange between the gulf and the interior water bodies (between Bay

Junop and Caillou Lake). Some gaps in the barrier between these two water

bodies would be closed to restore historical hydrologic connections. By

reducing marine influences in these interior areas, this feature would allow

increased freshwater influence from Four League Bay to benefit marshes in

the surrounding areas.

CWPPRA has several projects in various stages that could have relationships to

the LCA ARTM Study; some of these projects are described below. Additional

projects are described in detail in Volume III.

Atchafalaya Sediment Delivery (AT-02): The project is located east of the

lower Atchafalaya River navigation channel in the Atchafalaya River Delta,

approximately 19 miles southwest of Morgan City, Louisiana, in St. Mary

Parish. Growth of the lower Atchafalaya Delta has been reduced as a result

of maintenance of the Atchafalaya River navigation channel. Delta

development in the shallow waters of Atchafalaya Bay is dependent on

distributary flows and the diversion of sediments into overbank areas

through crevasse channels. Because of the placement of material dredged

from the navigation channel and sediment accumulation within the channels

that decrease flow efficiency, the open crevasse channels are frequently shortlived. As river flow through a crevasse channel is reduced, the amount of

sediment that can be deposited in the delta is likewise reduced, resulting in

decreased marsh development. The purpose of this project is to promote

natural delta development by reopening two silted-in channels and using

those dredged sediments to create new wetlands. Approximately 720,000

cubic yards of sediment were dredged from Natal Channel and Castille Pass

in 1998. Over 12,000 ft of channel were reopened, and more than 280 acres of

new habitat were created by the strategic placement of the dredged channels’

sediments. By reestablishing water and sediment flow into the eastern part

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of the Atchafalaya Delta, an additional 1,200 acres of new habitat are

expected to be created naturally over the life of the project.

Construction was completed in 1998. A pre- versus post-construction habitat

analysis using aerial photography indicated that, while there was an increase

in land of 78.4 acres, the majority of the habitat created was represented by

forested wetland (50.1 acres), while freshwater marsh and upland barren

habitats accounted for 14 acres of gain each. Although many of the dominant

plant species are present in both created and reference areas, the created

areas contained different plant communities when compared to any time

period in the development of a natural crevasse splay that served as a

reference area for this project. Although the long-term effects on SAV are

unclear, habitat mapping indicated an increase in SAV habitat of 221.5 acres

from 1997 to 1998, but this is very close to the increases that were reported

in the Study Area preconstruction. Although habitat mapping has not been

performed, satellite imagery indicates that there have been significant

increases in emergent acreage from 1998 to 2000. This project is not likely to

have a major impact on the flows or water levels in the LCA ARTM Study

Area.

Avoca Island Diversion and Land Building (TE-49): The project is

located in the Avoca Island area in St. Mary Parish, Louisiana. The Avoca

Island area lost approximately 5,000 acres of marsh between 1932 and 1990.

Natural overbank flooding into the area has been eliminated by

channelization and construction of flood protection levees, thereby preventing

the input of freshwater, sediment, and nutrients. The goal of this project is to

rebuild eroded wetlands in the area through the diversion of freshwater,

sediment, and nutrients. A diversion structure will be installed through the

Avoca levee to allow water from Bayou Shaffer to enter Avoca Lake at a rate

of 1,000 cfs. A natural bayou will be used as the primary outfall channel for

the diversion. Outfall management measures will be evaluated and

incorporated to increase benefits to aquatic habitats in the island system.

The Louisiana Coastal Wetlands Conservation and Restoration Task Force

approved funding for engineering and design at the January 2003 Task Force

meeting. The project work plan for the engineering and design phase was

submitted for program review in May 2003. Engineering data collection,

including site surveys and a geotechnical boring, is ongoing. This project

would directly impact freshwater marsh in the northwest portion of the LCA

ARTM Study Area and could impact hydrology in the area as well.

Floating Marsh Creation Demonstration (LA-05): This project is located

within the fresh and intermediate marshes of the Mandalay Wildlife Refuge

in Terrebonne Basin. Tens of thousands of acres of marsh within the fresh

and intermediate zones of the Barataria and Terrebonne Basins converted to

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open water between 1968 and 1990. Large areas of fresh and intermediate

open water exist in marsh interiors, presenting opportunities for

reestablishment within those basins. These types of open water areas are not

well-suited for typical projects such as sediment diversions, beneficial use of

dredge material, or dedicated dredging because they generally are located

long distances from natural sediment sources, frequently dredged navigation

channels, or other water bodies with bottom substrates containing material

suitable for marsh creation. Additionally, the substrate under these large

areas of fresh and intermediate open water is often fluid organic matter that

would not support the weight of added sediment. The purpose of this

demonstration project is to develop and field test unique and previously

untested technologies for creating floating marsh for potential use in fresh

and intermediate zones.

The Louisiana Coastal Wetlands Conservation and Restoration Task Force

approved funding for this demonstration project at their January 2003

meeting. The goal of this project is to develop methods for restoration of open

areas within deteriorated floating marsh and other freshwater areas where

establishment of maidencane (Panicum hemitomon) marsh is desired. In

addition, the technology being developed is to be transferable to wider

applications across the Louisiana coastal area. The first phase of the project

consisted of two components in which buoyant vegetated mats or artificial

floating systems were developed and tested in a controlled environment

during the first 2 years of the project. Various combinations of plant species,

planting methods, structure materials, and substrates were tested to

determine optimal buoyancy and structure design. In addition, plant

response to environmental effects was evaluated in an effort to identify

methods to accelerate floating marsh mat development. For the second phase

of the project, the AFSs were then deployed into open water areas for field

testing on Mandalay National Wildlife Refuge in 2006. Monitoring of the

AFSs field performance is ongoing. This project is unlikely to affect the

hydrology of the LCA ARTM Study Area.

GIWW Bank Restoration of Critical Areas in Terrebonne (TE-43): The

project is located in the Terrebonne basin, in Terrebonne Parish, Louisiana.

In the past 20 years, as the efficiency of the Lower Atchafalaya River has

decreased, Verrett subbasin flooding and Atchafalaya River flows via the Gulf

Intracoastal Waterway have increased. Deterioration of fresh and

intermediate wetlands, particularly of the floating marshes in the upper

Penchant basin, has been attributed to sustained elevated water levels. In

addition, floating marshes in some areas have become directly exposed to

increased circulation through unnatural connections formed where channel

banks deteriorated. Conversely, losses in the central Terrebonne Parish

marshes have been attributed to the elimination of riverine inflow coupled

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with subsidence and altered hydrology from canal dredging that facilitated

saltwater intrusion. Increased flow of the GIWW and wave pulses from

navigation traffic are causing additional breakup and loss of floating marshes

in unprotected areas. This project is designed to restore critical lengths of

deteriorated channel banks and stabilize/armor selected critical lengths of

deteriorated channel banks with hard shoreline stabilization materials. The

geotechnical soils investigation report is complete. Soils in the area are very

soft and fluid. This project has been completed largely under the CIAP. This

project could impact the LCA ARTM Study Area by reducing the loss rates of

fresh marsh along the GIWW.

Grand Bayou Hydrologic Restoration (TE-10): The project is located in

Lafourche Parish, Louisiana, approximately 5 miles southwest of Cut Off and

south of Larose. The Study Area includes part of the Pointe au Chien

Wildlife Management Area (WMA). St. Louis Canal and the Island Road

Borrow Canal have re-routed water exchange westward via Bayou Pointe au

Chien to the Bayou Jean LaCroix watershed. Because this area has higher

salinities and twice the tidal amplitude of the Grand Bayou watershed into

which the area should drain, swamps and other salt-sensitive Study Area

wetlands have suffered substantial deterioration and loss. Water exchange

to the west through Bayou Pointe au Chien would be halted by installing a

major water control structure in Bayou Pointe au Chien. Exchange with the

Grand Bayou watershed would be restored by installing new water control

structures through the existing levee along the west side of the Grand

Bayou/Grand Bayou Canal. In April 2002, the project was downsized based

on the results of earlier engineering work. Modeling work has been initiated

and is expected to take several years to complete. This project was

deauthorized in January 2009 by the Restoration Task Force and will not be

built under the CWPPRA

In early 2001, the Barataria-Terrebonne National Estuary Program

(BTNEP) and the Greater Lafourche Port Commission fostered a

partnership with other organizations to reestablish a chenier ridge and

associated coastal marsh habitats in southeast Louisiana. This partnership

was born from a desire to further the knowledge and expand the focus of

habitat restoration in coastal Louisiana from purely a vision that supported

marsh restoration to one that encompassed other natural landscape features.

Louisiana’s unparalleled coastal wetland loss problem means dire

consequences for many species of birds. But of equal importance are the

distributary ridges and chenier ridges that are being lost at an alarming rate.

These ridge habitats and associated wetlands are extremely important for

millions of migrating neotropical songbirds that cross the Gulf of Mexico each

spring on their way back to their breeding grounds in the eastern United

States and Canada. The Greater Lafourche Port Commission is in the

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process of reestablishing a maritime forest ridge in the vicinity of Bayous

Cochon and Moreau just north of the port at Fourchon, Louisiana. BTNEP is

serving as a co-lead implementer of this project along with the Greater

Lafourche Port Commission and is helping to coordinate discussions and onthe-ground planning and construction. In addition, BTNEP is providing

funding for this project. This program could benefit the LCA ARTM Study

Area by impacting hydrology and salinities in the area, depending on the

locations chosen for restoration or ridge habitat.

4.2 Need for and Objectives of Action *

Following an extensive literature review and NEPA scoping, the PDT met to

consider all the available information for the purpose of identifying specific

problems and opportunities, a general problem statement, a goal statement, and an

initial list of project specific objectives and constraints.

4.2.1 Public Concerns

Public input was received during several scoping meetings as well as meetings with

various stakeholders. As part of the NEPA scoping and public involvement process,

participants stressed the need for greater influx of both freshwater and sediment to

Terrebonne Parish and stressed the urgency of implementing this project. The top

five themes identified by members of the public follow:

Need for a greater influx of freshwater and sediment to Terrebonne Parish

Use of pipelines to distribute water and sediment

Management of water flowing through the GIWW

Need for freshwater flow into the Terrebonne marshes

Impact to marshes from water increase and velocity

4.2.2 Problems, Needs, and Opportunities*

Study Area Problems & Needs

The natural processes of subsidence, habitat switching, and erosion, combined with

human activities, have caused significant adverse impacts to the Northern

Terrebonne Marshes, including accelerated wetland loss and ecosystem

degradation. In habitat switching, one habitat will convert to another habitat

through succession. In Louisiana, this process is frequently due to changes in

salinity levels or inundation. Examples of habitat switching may be a forested

system converting to a freshwater marsh or a freshwater marsh converting to a

saline marsh. The changes in habitat structure and/or composition result in a loss

of one group of ecosystem services and may result in local rarity of a habitat type.

Wetlands in the Study Area are deteriorating for several reasons: 1) subsidence and

sea level rise, 2) lack of sediment and nutrient deposition, 3) erosion via tidal

exchange, 4) channelization, and 5) saltwater intrusion. These reasons have

resulted in the loss of several thousand acres of solid, vegetated marsh.

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Adequate sediment exists in the Atchafalaya River to benefit marshes in the central

and eastern study areas; however, the existing and potential future sediment

transport capacities of the GIWW or channels and canals in the Study Area

preclude adequate delivery of sediments to achieve project goals and objectives.

In the absence of supplemental freshwater from the Atchafalaya 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

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. Several channels have been dredged that cut through

the natural ridges, increasing both drainage and tidal exchange in the Study Area

and exposing the soil to erosive forces.

The wetland communities within the northwestern portion of Terrebonne Basin are

partially separated from the influence of the Atchafalaya River. The hydrology of

these areas is influenced by a widely variable pattern of Atchafalaya River

backwater effect, rainfall runoff events, and marine processes. Major navigation

channels in the subprovince are the Atchafalaya River, Wax Lake Outlet, HNC,

GIWW, and the Lower Atchafalaya River (south of Morgan City). Each of these

navigation channels introduces and/or compounds marine influences in many of the

interior coastal wetlands and water bodies within the subprovince.

Without action, the freshwater, intermediate, and brackish marshes in the northern

and eastern areas of Terrebonne Basin would continue to deteriorate and disappear

due to the combined effects of subsidence, saltwater intrusion, and a lack of riverine

influence. The flotant marshes within the Penchant Basin, located in northwest

Terrebonne Basin, will continue to deteriorate due to excessive backwater flooding

events from the Atchafalaya River. In the south, the brackish marshes surrounding

Lake Mechant will continue to deteriorate due to saltwater intrusion and a lack of

riverine influence.

General Study Area Opportunities

Opportunities exist to naturalize the distribution of freshwater and deltaic forming

sediments, improve hydrologic distribution of freshwater, improve topographic

diversity and reduce the negative impacts of Gulf storm events.

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 where the limited existing freshwater

supplies are directed through the Terrebonne Marshes and into the Gulf.

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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 marsh-forming sediments

from riverine environments has accelerated the degradation of all marsh

types. Opportunities exist to re-introduce sediments from the Atchafalaya

River and several bayous and to use on-site sediment displaced by Gulf storm

events to create new marsh area.

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.

Specific Problems and Opportunities by Study Area Subunit: Due to the

size of the 1,100-square-mile LCA ARTM Study Area, it was divided into three

subunits, labeled as West - Bayou Penchant Area, Central - Lake Boudreaux Area,

and East - Grand Bayou Area. Subunits have been separated by a combination of

natural, physical, and geographic features, and the PDT developed the limits of the

subunits. The separation of the whole Study Area allowed the PDT to evaluate

specific needs and screen individual measures relative to each subunit. Generally,

all three study subunits are experiencing a similar problem; wetlands are

deteriorating as a result of subsidence, lack of sediment and nutrient deposition,

and saltwater intrusion and erosion.

Although the GIWW has served as a major hydrologic alteration throughout the

entire Study Area, it also serves as a thread that connects all subunits. Therefore,

the GIWW is considered one of the primary opportunities to increase the delivery of

freshwater, nutrients, and sediment to assist with marsh development and land

building and counteracting the effects of saltwater intrusion and land subsidence.

When considering future without project conditions, the assumption was made that

the Morganza to the Gulf Project would be completed by 2025. The operating plan

for the Morganza to the Gulf HNC flood gates calls for closure of the flood gates

whenever necessary to prevent saltwater intrusion up the HNC. Accordingly, for

purposes of future without project hydraulic modeling, the assumption was made

that the HNC flood-gates would be closed for 2 months each year starting in 2025.

Other water control structures associated with the Morganza to the Gulf Project

would only be utilized under tropical storm / hurricane conditions and, therefore,

would not appreciably impact the hydrology of the Study Area under normal

operating conditions. Therefore, these structures were not included in the hydraulic

modeling for the LCA ARTM Project.

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Problems: Within the West - Bayou Penchant Area (

West - Bayou Penchant Area

Figure 4-1), problems include

the following:

Lack of freshwater, sediment, and nutrient delivery

Subsidence and land loss

Hydrologic alterations

Saltwater intrusion

Marsh break up on the GIWW

GIWW constrictions

Opportunities: Within this Study Area, opportunities to implement restoration

measures include creating a diversion from the Atchafalaya River. The goal of the

diversion would be to increase freshwater, sediment, and nutrient supply to the

Study Area, but the results of the diversion may be more heavily relied on in

subunits east of the West - Bayou Penchant Area.

In combination with increasing supply of riverine water into the GIWW, other

methods to improve delivery and distribution of freshwater include enlarging

constrictions within the GIWW and improving eastward conveyance along the

GIWW. As noted in the problems, an observable constriction within this subunit is

in a location where the GIWW flows through a high quality, forested wetland

system located between Bayou Black and Bay Wallace. Opening this constriction

may assist with increasing flow to the Study Area, as well as the other two eastern

Study Areas. There are also many points along the GIWW where canals serve as

diversion points for freshwater, thus affecting the quantity of freshwater conveyed

east of Houma.

Another opportunity to improve eastward conveyance of riverine water and reduce

marsh break up involves methods to stabilize critical lengths of deteriorated

channel banks along the GIWW and Bayou Chene. Bank protection within this

subunit is anticipated to diminish the effects of wave wash from vessels and reduce

breakup. Bank stabilization is also an opportunity to restrict the number of

openings and routes where freshwater supply is escaping to wetlands that are

nutrient and sediment rich. Locations along Bayou Chene near Avoca Island and

areas along the GIWW east of Bay Wallace will likely require measures of

protection. Combined with bank stabilization, nonstructural methods to manage

navigation traffic may be appropriate.

Within the southern portions of the Study Area, opportunities to increase

freshwater delivery and sediment input are available and needed. The options of

implementing additional freshwater diversions in the Lower Penchant Basin may

be necessary to reduce the problem of deteriorating wetlands and land loss in

locations between Lost Lake, Lake Mechant, and Lake de Cade. This area seems to

be most hard hit from land subsidence, saltwater intrusion, and marsh loss. Other

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methods to diminish the influence of saltwater in the Lower Penchant Basin involve

implementing strategic land building to create new ridges to assist with the

redistribution of flow and minimize the influence of saltwater.

Problems: Within the Central - Lake Boudreaux Area (

Central - Lake Boudreaux Area

Figure 4-1), problems

include the following:

Lack of freshwater, sediment, and nutrient delivery

Subsidence and land loss

Hydrologic alterations

Saltwater intrusion

GIWW constrictions

Area infrastructure

Opportunities: Within this subunit, restoration and protection measures aimed at

maintaining the physical integrity of the area primarily include a transition toward

a greater riverine influence to deliver freshwater, sediments, and nutrients to help

promote a healthier marsh system and lower salinity levels. Opportunities to

implement restoration measures include increasing delivery of freshwater to the

study subunit through the GIWW and into the HNC. Through the increased supply

of freshwater, sediments, and nutrients, diversions may be implemented off the

HNC through either gated structures or canals to nearby wetlands. Diversion

locations were evaluated in areas on both the eastern and western side of the HNC.

In combination with increasing freshwater supply into the GIWW, other

opportunities to improve delivery and distribution to the Study Area may include

enlarging constrictions within the GIWW. An observable constriction within this

subunit is within the city of Houma, Louisiana. Opportunities to open constrictions

will be difficult due to the area infrastructure. Opening this constriction may assist

with increasing flow to the immediate subunit through Bayou Petit Caillou and

Bayou Terrebonne. However, widening the constriction will facilitate continued

conveyance to the eastern study subunit.

Another opportunity to improve retention of freshwater and diminish the influence

of saltwater intrusion is to consider management of the proposed HNC Lock

Complex and the proposed Morganza to the Gulf Levee. The design and

management of the planned HNC Lock Complex / Morganza to the Gulf levee may

provide both environmental and flood control benefits. The lock complex and

floodgate can be managed to assist with salt water intrusion and freshwater

distribution. Other methods involve implementing strategic land building south of

Lake Boudreaux to assist with the retention of freshwater and diminish the

influence of saltwater.

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Problems: Within the East - Grand Bayou Area (

East - Grand Bayou Area

Figure 4-1), problems include the

following:

Lack of freshwater, sediment, and nutrient delivery

Subsidence and land loss

Hydrologic alterations

Saltwater intrusion

Area infrastructure

Opportunities: Within this subunit, restoration and protection measures aimed at

maintaining the physical integrity of the area primarily include a transition toward

a greater riverine influence and creating barriers to saltwater intrusion.

Opportunities to implement restoration measures include increasing freshwater,

sediment, and nutrient supply and delivery to the study subunit through increasing

freshwater supply from the Atchafalaya River and/or implementing other diversions

that utilize the Mississippi River as a freshwater source. Additional diversions

from the Mississippi River could either supplement or provide freshwater in lieu of

a diversion from the Atchafalaya River. Diversions were considered from locations

outside the Study Area, which include a diversion from the Mississippi River into

Bayou Lafourche near the city of Donaldsonville, Louisiana, or utilizing the

increased freshwater supply planned through the LCA Davis Pond Diversion

project. Once freshwater supply is increased to the Study Area and delivered to

Grand Bayou Canal, diversions off of Grand Bayou Canal may offer solutions to

increase freshwater, sediment, and nutrient delivery to wetlands located within this

study subunit.

Another opportunity to improve retention of freshwater and diminish the influence

of saltwater intrusion is to analyze the planned construction of the proposed

Morganza to the Gulf Levee. The design of the Morganza to the Gulf levee may

provide both environmental and flood control benefits. However, this levee would

not encapsulate the entire study subunit, and additional methods to minimize

saltwater intrusion and help retain freshwater within the remaining portions of the

study subunit would likely be necessary. Within the southern limits of the Study

Area, other methods to assist with freshwater retention and provide a saltwater

barrier involve implementing strategic ridge development and outfall management

along the boundary line of the Study Area and near the north side of Terrebonne

Bay.

4.2.3 Planning Objectives

For the LCA ARTM Project, the goal is to reduce degradation of the Terrebonne

marshes and facilitate a move toward achieving and sustaining a coastal ecosystem

that can support and protect the environment, economy, and culture of southern

Louisiana and, thus, the nation.

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Specific Project Objectives:

The objective of the LCA ARTM Project is to provide additional freshwater,

nutrients, and fine sediment to the area to facilitate organic sediment deposition,

improve biological productivity, and prevent further deterioration of the marshes.

Specific project objectives include, but are not limited to, the following and are

applicable to all Study Area subunits:

Prevent, reduce, and/or reverse future wetland loss

Achieve and maintain characteristics of sustainable marsh hydrology

Reduce salinity levels in Study Area

Increase sediment and nutrient load to surrounding wetlands

Increase residence time of freshwater

Sustain productive fish and wildlife habitat

4.2.4 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

Ecosystem constraints: Constraints imposed upon the project design by

existing conditions within the Study Area's ecosystem

These categories and their constituent constraints are discussed separately below.

Project Design Constraints: Identified project design constraints for the LCA

ARTM Project include the following:

The LCA ARTM Project must accomplish its goals while avoiding elevating

flood levels at nearby communities.

The LCA ARTM Project must protect vital socioeconomic resources, including

cultures, community, infrastructure, business and industry, and flood

protection.

Some existing infrastructure, such as navigation locks and the constrictions

of the GIWW, could need modification to accommodate flow regimes that

support the objectives of the LCA ARTM Project. Some of these constrictions

and navigation features cannot be modified due to urban development in

Houma, the need to maintain the GIWW for navigation, or exorbitant costs of

constriction removal.

A substantial amount of oil and gas infrastructure exists within the Study

Area. Adverse effects to oil and gas infrastructure would be minimized to the

extent practicable, consistent with the goals of the project.

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The internal arrangement of small access canals would likely need to be

altered to support the goals of the project. This would have to be done in a

manner that would allow reasonable access to all prospective users. Figure

4-2 and Figure 4-3 identify the flow patterns and drainage constrictions in

both the western and eastern subunits.

Figure 4-2: Flows and constrictions in the Western subunit

Figure 4-3: Flows and constrictions in the East subunit

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Ecosystem Constraints: Identified ecosystem constraints for the LCA ARTM

Project include water quality. The introduction of water and sediments should not

result in the violation of established water quality standards in the Study Area.

4.3 Existing and Future Without Project Condition*

This section described the existing and future without project conditions of the

Study Area as they relate to plan formulation and development of alternative

projects. Information regarding the existing condition was obtained from the

Affected Environment section of the FS/SEIS, and information regarding the future

without project condition was obtained from the Environmental Consequences

section of Volume III.

4.3.1 Existing Condition

4.3.1.1 Location

The overall Study Area is located mostly in Terrebonne Parish in southeast

Louisiana at the northern edge of the Gulf of Mexico (Figure 4-1) and encompasses

approximately 1,100 square miles (700,000 acres). A portion of Lafourche Parish

between Bayou Lafourche and Bayou Pointe au Chien is also included in the Study

Area as well as small portions of St. Mary, St. Martin, and Assumption parishes.

The Study Area is approximately 55 miles wide from west to east and averages 20

miles across from the north to south boundaries.

The Study Area lies within the Barataria-Terrebonne Estuary. This estuary

extends from the west bank levees of the Mississippi River (north and east) to the

East Guide Levee of the Atchafalaya River (west) to the Gulf of Mexico (south) and

to the town of Morganza (north). The Barataria Basin covers about 1,551,800 acres,

while the Terrebonne Basin covers an area of about 2,063,500 acres. The Study

Area lies within the southern end of the Terrebonne Basin and contains a complex

of habitat types, including natural levees, lakes, swamps, marshes, and bayous

formed from the sediments of abandoned Mississippi River deltas. Elevations in the

Study Area vary from approximately 10 ft NGVD to 4-5 ft NGVD along bayou ridges

to less than 1 foot NGVD along the southern edge near the Gulf of Mexico.

Due to the magnitude of the Study Area, the entire Study Area was divided into

three subunits West - Bayou Penchant Area, Central - Lake Boudreaux Area, and

East - Grand Bayou Area, which are described in Section 4.1.1 and in the FS/SEIS

(Volume III).

4.3.1.2 Climate

The climate of the Study Area is subtropical marine with long humid summers and

short, moderate winters. The climate is strongly influenced by the water surface of

sounds, bays, lakes, and the Gulf of Mexico and seasonal changes in atmospheric

circulation. Cold, continental air masses produce frontal passages with

temperature drops during fall and winter, and tropical air masses produce warm,

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moist airflow conducive to thunderstorm development during spring and summer

(USACE, 2008c). Average annual rainfall for the area is approximately 65 inches.

The Study Area is also subject to periods of both drought and flood.

Louisiana is susceptible to tropical waves, tropical depressions, tropical storms, and

hurricanes due to its proximity to the Gulf of Mexico. National Oceanic and

Atmospheric Administration (NOAA) Coastal Services Center indicates storm

centers of at least 38 tropical cyclones with a Saffir-Simpson Hurricane Scale of

Category 1 or higher have passed within 50 miles of the Study Area between 1851

and 2008. Hurricane activity in 2004 and 2005 resulted in roughly 12,160 acres of

wetlands being converting to open water within the Terrebonne Basin.

4.3.1.3 Geomorphic and Physiographic Setting

The geology of the Study Area is heavily influenced by the Mississippi River and its

delta plain, which is composed of abandoned and active deltas of the Mississippi

River. Three of four abandoned delta complexes shaped Terrebonne and Lafourche

parishes as sediments were deposited on the Pleistocene Prairie. During the active

delta-building phase, the Mississippi River laid down sediments from 100 to 200 m

thick at each delta (Penland et al., 1988). The most recent sediments were laid

down as part of the abandoned Lafourche Delta.

After delta abandonment occurs, sediments slowly deteriorate as they subside

under own weight. Historically, the cycle of delta growth and destruction took

about 5,000 years (Gosselink and Sasser, 1991); however, delta destruction is taking

place at a much faster rate due to a variety of factors, including human.

Driving factors in landscape changes include sea level rise, geological compaction, a

50% reduction in sediment supply from the Mississippi River since the 1950s, and

hydrologic changes (Turner and Rao, 1990). Geological factors, such as

consolidation of deltaic sediments and active faulting, appear to be the underlying

cause for a majority of land loss in coastal Louisiana (DeLaune et al., 1994).

Hydrocarbon withdrawals may also be a significant factor (White and Morton,

1997). Based on data from Gulf of Mexico gages, regional sea level rise is

approximately 0.75 ft/century, and based on gages at Grand Isle and Eugene Island,

subsidence in the Study Area is approximately 2.35 ft/century.

4.3.1.4 Soils and Water Bottoms

The Study Area is located primarily within Terrebonne Parish, in the south-central

region of the Mississippi River Delta Plain. The land area is approximately 24%

Southern Mississippi Valley alluvium and 76% Gulf Coast Marsh. Loamy soils and

clayey soils that rarely flood make up approximately 9% of the total land area of the

parish. Clayey soils on the lowest parts of the landscape are subject to occasional or

frequent flooding make up about 6% of the land area. The remaining 85% of land in

the parish consists mainly of ponded, frequently flooded, and very frequently

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flooded, mucky and clayey, fluid soils in marshes and swamps. Approximately 7%

of the total survey area meets the soil requirements for prime farmland.

4.3.1.5 Hydrology

Historically, flows within the Study Area were driven by the Atchafalaya River and

Bayou Lafourche. Flows in the Atchafalaya had been increasing from 10% of the

combined Mississippi and Red River flow in the 1850s to 30% before the

construction of the Old River Control Structure. This structure maintains the split

at 30% today. Bayou Lafourche was naturally closing before its connection with the

Mississippi River was closed in the early 1900s. With the closure of Bayou

Lafourche, the inflow of freshwater into the central and eastern portions of the

Study Area was limited to local inflow. The Bayou Black ridge restricted the flow of

water along the northern boundary of the Study Area, as it does today.

Since that time, the Atchafalaya Basin Floodway; GIWW; Atchafalaya River;

Bayous Chene, Boeuf, and Black Navigation Channel; HNC; and Houma area levees

and pump systems, drainage canals, and access canals have altered the hydrology of

the Study Area.

Today, stages in the lower Atchafalaya River force flow northeast through the Avoca

Island Cutoff into the GIWW and Bayou Penchant. Additional flow enters the

GIWW from the Verrett Basin through Bayou Boeuf. Water travels eastward along

the GIWW and through the Penchant Basin. A portion of this water leaves the

Study Area through the Penchant basin along natural and man-made channels.

The remaining flow continues east along the GIWW. The GIWW intersects the

HNC at Houma, and the majority of flow travels down the HNC to the Gulf of

Mexico. The remaining flow continues east along the GIWW. A small amount of

water enters the marshes of the Grand Bayou basin through two channels,

Company Canal and Bayou L’Eau Blue. Finally, the flow exits the Study Area

along the GIWW through the Bayou Lafourche ridge.

Freshwater flow introduction to the Boudreaux basin is limited. The basin is

hydraulically isolated by the Bayou Grand Caillou ridge on the west and the Bayou

Petit Caillou ridge on the east. Bayou Chauvin and forced drainage areas supply

freshwater to the northern Boudreaux basin. Bayou Dulac provides a natural

connection to Bayou Grand Caillou. Boudreaux Canal and Robinson Canal provide

man-made connections to Bayou Petit Caillou. Any remaining freshwater inflow is

provided through local drainage.

The Grand Bayou basin is hydraulically isolated by the Bayou Pointe au Chien

ridge to the west and Bayou Lafourche ridge and back levees to the east as well as

LA Highway 24 to the north along the Bayou Blue ridge. The major sources of

freshwater in this basin include the connection of St. Louis Canal and Bayou L’eau

Blue to the GIWW as well as forced drainage areas and local drainage.

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Bayou Boeuf currently is the outlet for the Verret basin. Backwater effects can slow

drainage through the Bayou Black ridge, thus affecting the duration of high water

levels in the Lake Verret area.

Water levels and salinity levels throughout the Study Area are influenced by tides

in the Gulf of Mexico. Saline waters advance and retreat in channels and marshes

with the tidal cycle. As the land subsides and the marshes disappear, saline water

advances farther north. Salinity and water levels can also vary with seasonal wind

direction. Southern winds push saline water into the marshes during the fall and

winter, and northern winds push water out of the marshes during the remaining

parts of the year.

4.3.1.6 Sedimentation and Erosion

The construction of floodways, levees, pump systems, drainage canals, access

canals, and waterways has altered hydrology and sediment distribution within the

Study Area. Suspended sediments in the Atchafalaya River, Bayou Lafourche, and

Bayou Boeuf water as well as bank line erosion are the sediment sources for the

Study Area.

Suspended sediments are readily distributed through Penchant Basin. The small

amount of sediment that enters Boudreaux Basin is not well distributed. The

Grand Bayou marshes receive small amounts of suspended sediment during spring

flooding on the Atchafalaya River, but the distance from the river and the small

connection to the GIWW limit sediment availability. Much of sediment that enters

the Grand Bayou Basin is efficiently flushed from the basin through Cutoff Canal.

Erosion in the Study Area is the result of wave wash from both natural and

manmade sources.

4.3.1.7 Vegetation Resources

The basic coastal wetland habitats within the Study Area are typically described as

swamp, freshwater marsh, intermediate marsh, brackish marsh, and saline marsh

(Day et al., 1989; Mitch and Gosselink, 2000). With the freshwater marsh category,

flotant emergent and attached emergent are the two types in the Study Area.

Flotant marsh is 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 (Sasser et al., 1994).

Sasser et al. (1994) estimate that about 70% of the marshes in the BaratariaTerrebonne estuary are flotant marsh. The second type in the freshwater marsh

category is attached emergent freshwater marsh, which is attached to the

underlying soil. The species composition for attached emergent marsh contains

predominantly maidencane and coastal arrowhead, along with spikerush,

alligatorweed, common reed, coastal water-hyssop, penny-wort, and saltmeadow

cordgrass (Bahr et al., 1983; Gosselink, 1984; Conner and Day, 1987).

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Intermediate marsh habitat lies between freshwater marsh and brackish marsh

and the species of vegetation do not generally differ significantly from those found

in freshwater marsh although different species may be dominant. According to

Gosselink (1984), saltmeadow cordgrass is the dominant species in intermediate

marsh with other common species including coastal arrowhead, common reed,

coastal water-hyssop, seashore paspalum, spikerush, and Olney's bulrush.

The dominant brackish marsh plant is saltmeadow cordgrass, comprising about

one-half of the plants (Gosselink, 1984; Conner and Day, 1987). By comparison, this

species comprises about one-third of the plants in intermediate marsh (Gosselink,

1984). Other important species for brackish marsh include seashore saltgrass,

camphorweed, and coastal water-hyssop (Conner and Day, 1987).

Salt marsh is dominated by saltmarsh cordgrass, comprising some 62 % of the

plants. Other important species are needlegrass rush, seashore saltgrass, and

saltmeadow cordgrass (Conner and Day, 1987). Saltmeadow cordgrass is prevalent

only at slightly higher elevations along distributary ridges.

Submerged and floating-leafed vegetation are most common in water bodies

associated with forested wetlands and fresh and intermediate marshes. SAV

consists mainly of coontail, hydrilla, elodea, pondweeds, water stargrass, wild

celery, fanwort, and Eurasian milfoil. The floating leafed species include American

lotus, water lettuce, water hyacinth, water spangles, and duckweeds. In brackish

marshes, SAV is most often found in protected areas away from excessive wave

action. Wigeon grass, southern naiad, and Eurasian milfoil are the most common

species in brackish water.

Marsh habitats are influenced strongly by the salinity regime of the surface water.

A zonation of plant species that differ in salinity tolerance exists along the salinity

gradient, with the species diversity of those zones increasing from salt to fresh

environments (Table 4-2).

Table 4-2: Salinity Ranges for the Four Coastal Wetland Types

Wetland

Type Range (ppt) Mean (ppt) Typical Range (ppt)

Fresh 0.1 – 6.7 <3.0 0 – 3

Intermediate 0.4 – 9.9 3.3 2 – 5

Brackish 0.4 – 28.1 8.0 4 – 15

Saline 0.6 – 51.9 16.0 12+

In order to determine existing and likely future conditions in the Study Area and to

facilitate determination of project impacts on area marshes, the USACE MVN

contracted the USGS to conduct habitat and land loss analyses on the Study Area

based on mapping of the area from 1956 to 2008. The project was broken up into 65

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polygons, with habitat classification and land loss analysis conducted on each. The

results of these analyses are presented in Table 4-3 and Figure 4-4. In order to

determine the rate of land loss or land gain within each of the polygons, data from

1985 to 2008 were utilized.

The overall rate of land loss in the Study Area was determined to be 2,597

acres/year (approximately 0.3% per year). However, there is considerable variation

from polygon to polygon in the rate of land loss or land gain. In general, the areas

with the highest rates of land loss have been the intermediate, brackish, and saline

marshes in the southern and eastern sections of the Study Area. The swamp and

freshwater marsh habitats generally exhibited lower rates of land loss and, in some

cases, land gain.

Table 4-3: Habitat Types in the Study Area from 1956 to 2008 (based on

Barras et al., 2008 and Barras, 2009)

Habitat

Category

Swamp Freshwater

marsh

Intermediate

Marsh

Brackish

Marsh

Saline

Marsh

Total

Land

Area

Total

Water ab Area

(acres)

ab

(acres) (acres) (acres) (acres) (acres) (acres)

1956 --- --- --- --- --- 619,822 119,254

1978 39,595 168,652 66,975 100,424 81,905 517,010 223,044

1985 --- --- --- --- --- 613,936 285,211

1988 96,073 204,784 54,532 101,642 87,076 649,064 250,083

1990 --- --- --- --- --- 627,223 271,924

1998 --- --- --- --- --- 582,939 316,208

1999 --- --- --- --- --- 602,428 296,719

2000 93,156 198,516 46,301 79,285 64,406 579,684 319,463

2001 64,765 240,241 51,493 81,996 68,246 597,316 301,831

2002 --- --- --- --- --- 599,453 299,694

2004 64,765 244,023 49,210 79,562 67,294 595,262 303,885

2005 64,759 240,171 49,028 78,120 64,805 585,852 313,295

2006 65,101 213,032 62,591 65,148 86,795 583,483 315,664

2008 --- --- --- --- --- 576,400 322,747

a Data are incomplete in Study Area for 1956 and 1978 imagery. 1985 to 2008 imagery was used in calculation of land loss

trend lines based on USGS recommendation for improving accuracy of projections.

b Variations in calculated land area from year to year occur due to actual land loss and land gain, major storm events, differing

tides/water elevations on the dates imagery was captured, random variation, etc. Trend lines over longer periods of time

provide a more accurate picture of actual land loss trends than comparing individual years.

In coastal Louisiana, 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 (USACE, 2008c).

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WRDA 2007 Section 7006(e)(3) 4-33 October 2010 Figure 4-4: Land gain/loss rates in the Study Area – percent per year based on 1985 to 2008 rates and 1985 acreage (based on Barras et al. 2008 and Barras 2009)

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4.3.1.8 Salinity

Salinity levels throughout the Study Area are influenced by tides in the Gulf of

Mexico. Saline waters advance and retreat in channels and marshes with the tidal

cycle. As the land subsides and the marshes disappear, the limit of the saline water

advances farther north. Salinity levels can also vary with seasonal wind direction.

In the fall and winter, southern winds push saline water into the marshes. During

other parts of the year, northern winds push water out of the marshes, reducing

salinity levels.

Man-made canals within the Study Area provide efficient conduits for salinity to

enter portions of the Study Area. These canals include the HNC, Cutoff Canal,

Robinson Canal, unnamed oil and gas exploration canals, and pipeline canals

4.3.1.9 Essential Fish Habitat

Aquatic and tidally influenced wetland habitats in portions of the Study Area are

designated as essential fish habitat (EFH) for post larval and juvenile life stages of

brown shrimp and white shrimp, red drum, and gulf stone crab. 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 Fishery Conservation and

Management Act by the Gulf of Mexico Fisheries Management Council (GMFMC)

(e.g., mackerels, snappers, groupers) and highly migratory species managed by

NMFS (e.g., billfishes, sharks).

4.3.1.10 Threatened and Endangered Species

Within the Study Area, there are several animal species (some with critical

habitats) under the Federal jurisdiction of the USFWS and/or the NMFS, presently

classified as endangered or threatened. Table 4-4 includes information on federally

listed threatened and endangered species in the Study Area.

Table 4-4: Federally Listed Threatened and Endangered Species in the

Study Area

Species Critical Habitat Status Jurisdiction

Federal State USFWS NMFS

West Indian manatee

(Trichechus manatus) E E X

Brown pelican

(Pelecanus occidentalis) De-listed December 17, 2009.

Piping plover

(Charadrius melodus)

X

(foraging, sheltering,

and roosting habitat

of wintering

populations)

T T X

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Hawksbill sea turtle

(Eretmochelys imbricata) E E X X

Kemp’s Ridley sea turtle

(Lepidochelys kempii) E E X X

Leatherback sea turtle

(Dermochelys coriacea) E E X X

Green sea turtle

(Chelonia mydas) T T X X

Loggerhead sea turtle

(Caretta caretta) T T X X

Pallid sturgeon

(Scaphirhynchus albus) E E X

Gulf sturgeon

(Acipenser oxyrinchus

desotoi)

T T X X

The following information on threatened and endangered species was obtained by

letter from the USFWS dated 21 January 2009.

The federally listed endangered West Indian manatee occasionally enter Lakes

Pontchartrain and Maurepas, and associated coastal waters and streams during the

summer months. Manatees have been reported in the Amite, Blind, Tchefuncte,

and Tickfaw rivers, and in canals within the adjacent coastal marshes of Louisiana.

They have occasionally been observed elsewhere along the Louisiana Gulf Coast.

federally listed as a threatened species, the piping plover, as well as its designated

critical habitat, occur along the Louisiana coast. On July 10, 2001, the USFWS

designated critical habitat for wintering piping plovers (Federal Register Volume

66, No. 132).

The pallid sturgeon is an endangered fish found in both the Mississippi and

Atchafalaya rivers (with known concentrations near the Old River Control

Structure Complex); it possibly is found in the Red River as well.

The Gulf sturgeon, federally listed as a threatened species, is an anadromous fish

that occurs in many rivers, streams, and estuarine waters along the northern Gulf

coast between the Mississippi River and the Suwanee River, Florida. In Louisiana,

the Gulf sturgeon has been reported at Rigolets Pass, rivers and lakes of the Lake

Basin, and adjacent estuarine areas. On March 19, 2003, the USFWS and the

NMFS 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.

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Endangered and threatened sea turtles forage in the nearshore waters, bays, and

sounds of Louisiana.

The LNHP lists 50 species or communities as occurring in Terrebonne and

Lafourche parishes, including federally listed species (Table 4-5).

Table 4-5: LNHP Threatened and Endangered Species in the Study Area

Common Name Scientific Name State Rank

Cooper’s hawk

a

Accipiter cooperii S2B, S3N

Gregg’s amaranth Amaranthus greggii S3

Swamp milkweed Asclepias incarnata S2

Brackish marsh Brackish marsh S3S4

Red wolf Canis rufus SX

Golden canna Canna flaccida S4?

Cypress-knee sedge Carex decomposita S3

Big sandbur Cenchrus myosuroides S1

Dune sandbur Cenchrus tribuloides S2

Floating antler-fern Ceratopteris pteridoides S2

Sand dune spurge Chamaesyce bombensis S1

Snowy plover Charadrius alexandrinus S1B, S2N

Piping plover Charadrius melodus S2N

Wilson’s plover Charadrius wilsonia S1S3B, S3N

Coastal dune grassland Coastal dune grassland S1S2

Coastal dune scrub thicket Coastal dune shrub thicket S1

Coastal live oak-hackberry

forest

Coastal live oak-hackberry forest S1S2

Coastal mangrove-marsh

shrubland

Coastal mangrove-marsh shrubland S3

Hairy comb fern Ctenitis submarginalis S1

Cypress-tupelo swamp Cypress-tupelo swamp S4

Reddish egret Egretta rufescens S2B, S2N

Creeping spike-rush Eleocharis fallax S1?

Canada spikesedge Eleocharis geniculata S1?

Rooted spike-rush Eleocharis radicans S1?

Peregrine falcon Falco peregrinus S2N

Freshwater marsh Freshwater marsh S1S2

Gull-billed tern Gelochelidon nilotica S2B, S2S3N

Bald eagle Haliaeetus leucocephalus S2N, S3B

Caspian tern Hydroprogne cospia S1S2B, S3N

Coast indigo Indigofera miniata S1

Common water-willow Justicia americana S2

Diamondback terrapin Malaclemys terrapin S2

Marine submergent vascular

vegetation

Marine submergent vascular

vegetation

Eastern glass lizard Ophisaurus ventralis S3

Osprey Pandion haliaetus S2B, S3N

Brown pelican Pelecanus occidentalis S2

Coastal ground cherry Physalis angustifolia S1?

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Roseate spoonbill Platalea ajaja S3

Millet beakrush Rhynchospora miliacea S2

Sand rose-gentian Sabatia arenicola S1

Vegetated pioneer emerging

delta

Sagittaria latifolia-Sagittaria

platyphylla-(Colocasia esculenta)

Deltaic Herbaceous Vegetation

S2S3

Salt marsh Salt marsh S3S4

Scaevola Scaevola plumieri SH

Gull bluestem Schizachyrium maritimum S1

Scrub/shrub swamp Scrub/shrub swamp S4S5

Estuarine submergent vascular

vegetation

Submergent vascular vegetation

(estuarine)

S1S2

Manatee Trichechus manatus SZN

Arrow-grass Triglochin striata S1

Sea oats Uniola paniculata S2

Waterbird nesting colony Waterbird nesting colony SNR

a State element ranks: S1 = critically imperiled in Louisiana because of extreme rarity; S2 = imperiled in Louisiana

because of rarity; S3 = rare and local throughout state or found locally in a restricted region; S4 = apparently secure

in Louisiana; S5 = demonstrably secure in Louisiana; SH = of historical occurrence in Louisiana but no recent

records verified within last 20 years; SX = believed to be extirpated from Louisiana; SZ = transient species; B =

breeding occurrence; N = nonbreeding occurrence; NR = No Rank; S? = rank uncertain.

4.3.1.11 Cultural Resources

The Study Area comprises approximately 1,100 square miles, or 700,000 acres, that

includes four primary geologic regions. The full array of 61 project features has a

total temporary right-of-way of approximately 3,467 acres. This represents the area

of direct impact. However, the intent of this project is to deliver freshwater in

quantities such that the broader area of impact has yet to be determined. As such,

the total area of potential effect (APE) cannot be mapped at this time.

There are 290 known archaeological sites within the proposed Study Area. Of

these, 283 are represented within the project geographic information system (GIS)

database by polygon features and seven by points. This dataset was derived from

both the online dataset of the Louisiana Division of Archaeology and sites digitized

manually after a visual examination of the legacy 7.5-minute quad maps at the

Louisiana SHPO. One archaeological site thought to be in the area (16TR80) is not

in the online dataset and was not located on the quad maps. The site files for the

majority of these sites do not list their National Register status.

There are eight locations listed on the National Register that are within the project

boundary. There are an additional six locations within a 1-kilometer radius of the

area. Of these National Register locations, only the Wesley House is located near a

potential project feature, being within 100 m of features CC2 and CD4. A private

cemetery associated with the Wesley House is within the APE of CD4.

4.3.1.12 Recreation

Like much of coastal southeast Louisiana, the eastern and central sections of the

Study Area have experienced substantial coastal erosion, loss of wetlands, and

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increasing salinity levels. Although the Study Area traditionally has provided

excellent saltwater fishing, in recent years, because of the increased salinity levels,

anglers have been able to catch saltwater species much farther inland than in the

past. Due to reductions in fresh and intermediate marshes, cypress trees, and SAV,

waterfowl habitat has become less abundant, and, consequently, duck hunting

opportunities have decreased.

Unlike most of coastal Louisiana, the far western portion of the Study Area, due to

the influence of the Atchafalaya River, has been relatively stable or experiencing

some limited accretion of deltaic lands. Salinity levels are relatively stable in this

area, and freshwater fishing opportunities in the area are excellent. The floating

marshes traditionally have provided quality habitat for waterfowl and waterfowl

hunting.

Recreation areas within the Study Area boundaries include the Mandalay National

Wildlife Refuge, the Pointe au Chien Wildlife Management area, and the Wetlands

Cultural Trail. The most prominent recreational activities within the Study Area

are fishing and waterfowl hunting. Limited consumptive recreation uses include

recreational crabbing, shrimping, and crawfishing. Natural ridges are also utilized

for deer and small game hunting. Nonconsumptive recreational activities attract

far fewer participants and include birdwatching at both Mandalay and Pointe au

Chien, hiking at Mandalay, and camping at Pointe au Chien.

The Study Area is included in Region 3 of the 2003-2008 Louisiana Statewide

Comprehensive Outdoor Recreation Plan (SCORP). Swimming, fishing, boating,

camping, hunting, and hiking in SCORP Region 3 accounted for an estimated 26.3

million activity days per year during the 2003-2008 period of analysis.

4.3.1.13 Socioeconomic Resources – Navigation

Major navigation corridors in the Study Area include the GIWW, Lower Atchafalaya

River, Bayou Chene, Bayou Boeuf, Bayou Black, and the HNC. Navigation

channels are also maintained on Bayou Grand Caillou, Bayou Petit Caillou, and

Bayou Terrebonne. Navigation in the vicinity includes the movement of oil and gas

supply vessels, commercial fishing vessels, pleasure crafts, and other barge traffic.

4.3.1.14 Socioeconomic Resources – Oil, Gas, and Utilities

The petroleum industry in the state accounts for almost 25% of the total state

revenues and employs more than 116,000 people (about 6% of the state’s total

workforce). These workers earn almost 12% of the total wages paid in Louisiana.

Indirect employment levels in support industries make this economic sector more

important than is indicated by the direct employment figures.

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The oil and gas production industry and the numerous associated support

industries are important parts of the socioeconomic landscape of the Study Area.

Oil and gas infrastructure is prevalent throughout the Study Area and vicinity.

4.3.1.15 Socioeconomic Resources – Commercial Fisheries

While Louisiana has long been the nation’s largest shrimp and menhaden producer,

it has also recently become the leading producer of blue crabs and oysters. Total

fish and shellfish landings for ports in the vicinity of the Study Area were 58 million

pounds in 2008. Ports in Terrebonne, Lafourche, and St. Mary parishes landed

approximately 31 million pounds of white and brown shrimp in 2008 with a

dockside value of $41 M, approximately 4.3 million pounds of oyster catch in 2008 at

a value of $11.7 M, and approximately 15.6 million pounds of blue crab with a

dockside value of $11.9 M (NMFS, 2009).

4.3.1.16 Socioeconomic Resources – Oyster Leases

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 M (NMFS pers comm, 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.

Approximately 390,000 acres are currently under lease in Louisiana, compared to

less than 250,000 acres during the mid 1970s and early 1980s (Diagne and Keithly,

1988). Terrebonne and Lafourche parishes currently account for approximately

115,000 acres as compared to 57,000 acres in the 1970s and early 1980s. The leases

have 15-year terms; the locations are leased from the state for $2 per acre per year.

4.3.2 Future Without Project Condition

4.3.2.1 Soils and Water Bottoms

The future without project or No Action Alternative would have no direct impacts

on soils and substrates. Soil erosion and land loss in the Study Area would continue

into the future. Natural and man-made levees would continue to subside, and

marsh soils would not be able to maintain their elevations due to subsidence,

decreased plant productivity, and wave erosion. Net primary productivity within

the Study 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, aesthetics, and

socioeconomic resources. Delta formation would continue at the mouth of the

Atchafalaya River. Water bodies would grow larger, and wave erosion would

accelerate, causing further land loss, thus making coastal communities more

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vulnerable to tropical storms. No large-scale loss of farmland would be expected

from subsidence. The greatest loss of farmland would come from conversion to

development.

4.3.2.2 Hydrology

Building of the Atchafalaya River delta would continue to impact stages on the

Lower Atchafalaya River. As stages increase, the flow passing through the Bayou

Lafourche ridge in the GIWW would increase. Areas hydraulically isolated from the

GIWW would continue to be isolated.

Monthly averaged flows along the GIWW would range from 700 to 28,000 cfs.

These flows would generally decrease from west to east. The largest loss of flow

would continue to be through the HNC, with monthly averaged flows ranging from

2,500 to 7,000 cfs. At times, flow reversals would occur throughout the Study Area.

Flow would enter and leave the Lake Boudreaux basin through Bayou Dulac,

Robinson Canal, and Boudreaux Canal. Bayou Dulac monthly averaged flows

would range between 50 and 400 cfs. Robinson monthly averaged flows would be

fairly steady near 1,500 cfs with higher monthly averaged flows near 1,700 cfs from

March through June. Boudreaux Canal monthly averaged flows would be fairly

steady around 500 cfs with higher monthly averaged flows near 700 cfs from March

through June.

Monthly averaged flows into Grand Bayou would range between 0 and 575 cfs.

Stages within the Study Area would be tidally driven with effects from the

Atchafalaya River. Over the project life, water surface elevations would increase by

at least 0.46 ft due to sea level rise. This increase could be as much as 2.29 ft if the

high rate of sea level rise occurs.

4.3.2.3 Sedimentation and Erosion

Building of the Atchafalaya River delta would continue to impact stages on the

Lower Atchafalaya River. As stages increase, eastward flows along the GIWW

would increase, carrying with them suspended sediments. These sediments would

be distributed through the Study Area according to the flow patterns we see today.

Southernmost portions of the Boudreaux basin would continue to be the only areas

to receive suspended sediments from the GIWW. In the Grand Bayou Basin, a

small portion of suspended sediments that arrive through the GIWW would be

distributed to the marshes to the east of Grand Bayou.

Bank lines of major navigation channels would continue to erode, depositing

sediments in the channels. The need for periodic maintenance dredging would

continue.

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Land building sediments would not enter the Study Area naturally on a large scale.

Federal, state, and local programs may beneficially use dredged materials within

the Study Area. Construction of channels and maintenance of existing channels

would be sources of sediment from within the Study Area. Additionally, sediment

may be brought from sources outside the Study Area.

4.3.2.4 Vegetation Resources

Under the No Action Alternative, there would be no direct impacts to vegetation

resources. Indirect impacts of the No Action Alternative would be the persistence of

existing conditions in the Study Area including saltwater intrusion, erosion, and

subsidence leading to continued fragmentation of marsh habitat and conversion to

open water.

The freshwater marshes in the western portion of the Study Area would likely

continue to receive increasing amounts of freshwater from the Atchafalaya River.

As the river’s delta enlarges, high water would be more likely to escape laterally to

the east and west. The acreage likely to receive the freshwater, nutrients, and

sediment from the Atchafalaya River would increase. The increase in freshwater

would likely encourage more SAV in open water areas. Land loss rates in this area

would likely remain low as subsidence would be counteracted largely by increased

freshwater flows and sediment arriving from the Atchafalaya River and stimulated

marsh growth. Land loss in the Penchant basin has been highest around Jug Lake.

Several CWPPRA projects in the area are being implemented to address this

elevated loss rate; however, it is anticipated that land loss near this location would

continue.

In the central and eastern subareas, wetlands would continue to be lost at an

annual rate of about what has been measured from 1985 to 2008 because of

subsidence, inundation of marsh plants, and subsequent erosion in brackish and

saline marshes. As these marshes disappear, salt water would begin to move

northward more rapidly, further stressing fresh and intermediate marshes. These

marshes would likely not tolerate the increasing salinity well and would probably

not convert to brackish marsh because the soils would be comprised of too much

organic matter. Research by Lessmann et al. (1997) and McKee and Mendelssohn

(1989) indicates these marshes would be very susceptible to the deleterious effects

from the sudden influx of salt water from a tidal surge associated with a hurricane.

For this study, 1985-2008 land loss data for each of the subareas were utilized to

project future conditions. In a few instances, land loss rates were adjusted to

account for anticipated changes due to recently completed or authorized projects or

other conditions that rendered the predicted values inaccurate. The actual rates

used can be found in Figure 4-4. These land loss rates were applied to Study Area

polygons to produce annual acreages lost from each subarea. Using the annual

acreage figure resulted in a linear trend of marsh loss through the 50-year period of

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analysis. Projections started with the acreage from 2008, the latest complete year

of data available during analyses. As can be seen in Figure 4-4, areas of highest

land loss are concentrated in the southeastern portion of the Study Area.

The overall habitat value and acreage of remaining wetlands would decline with the

No Action Alternative. WVA analysis predicted that 102,000 acres or 18% of

remaining vegetated wetlands in the Study Area would be lost over the 50-year

period of analysis. Several of the subareas are predicted to lose all emergent

wetlands before the end of the 50-year period of analysis.

Invasive Species: Under the No Action Alternative, existing conditions would

likely persist. Invasive species would likely continue to pose a threat to the floristic

integrity of the Study Area as landscape disturbance and deterioration is prolonged,

stressing the balance that evolved between Louisiana’s native vegetative

communities and their habitat. Degrading native vegetative communities would

become increasingly vulnerable to infestation and, eventually, be replaced by

invasive species that out-compete native species and aggressively develop dense

monocultural stands.

Some benefit may be realized from establishment of invasive species. For example,

the robust aboveground and belowground production of Cogon grass may provide

substrate stabilization and biomass contributions, or water hyacinth may provide

potential water quality improvement through nutrient uptake and retention.

However, the potential benefits are not expected to outweigh the overall impacts

anticipated from the proliferation of invasive species. Expected major impacts

caused by spread of invasive species are reduced vegetative biodiversity, alteration

of abiotic factors and coastal ecosystem processes, and reduction of wildlife food and

habitat. Existing invasive species found in the Study Area would likely continue to

be found, and new invasive species may become established. Likewise, Federal,

state, and local laws, programs, and regulations aimed at invasive species control

would continue.

4.3.2.5 Salinity

Hydraulic modeling was utilized to project changes in hydrology and associated

changes in water quality in the Study Area over the 50-year period of analysis.

Model results were utilized in the Wetland Value Assessment model to project land

loss impacts. Under future without project conditions, sufficient freshwater,

nutrients, and sediment loads from the Atchafalaya River are expected to continue

to reach the freshwater marshes in the northwestern portion of the West - Bayou

Penchant Area. Modeled salinity values show no change in these areas over the 50-

year period of analysis. Land change projections over the period of analysis show

increases in land area of approximately 5%. However, the intermediate and

brackish marshes in the southeastern Penchant area are expected to continue to

deteriorate due to saltwater intrusion, RSLR, and lack of freshwater, sediment, and

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nutrient delivery. Modeled average annual salinity values show slight increases of

0.1 to 0.4 ppt over the period of analysis. Land change projections over the period of

analysis show decreases in land area of approximately 35%. The fresh,

intermediate, brackish, and saline marshes in the Central - Lake Boudreaux Area

are expected to continue to deteriorate due to saltwater intrusion, RSLR, and lack

of freshwater, sediment, and nutrient delivery. Modeled average annual salinity

values in this region show increases of 0.3 to 1.2 ppt over the period of analysis.

Land change projections over the period of analysis show decreases in land area of

approximately 35%, with several areas converting completely to open water. The

fresh, intermediate, brackish, and saline marshes within the East - Grand Bayou

Area are expected to continue to deteriorate due to saltwater intrusion, RSLR, and

lack of freshwater, sediment, and nutrient delivery. Modeled average annual

salinity values show increases of 0.1 to 1.7 ppt over the period of analysis. Land

change projections over the period of analysis show decreases in land area of

approximately 49%, with several areas converting completely to open water.

4.3.2.6 Essential Fish Habitat

Although previous restoration efforts in the Study Area have helped maintain some

categories of EFH, the cumulative impacts of land loss, conversion of habitats, sea

level change, and increased storm intensity, are expected to lead to a net decrease

in the habitat most supportive of estuarine and marine species. The direct losses of

highly productive forms of EFH would lead to losses of shallow habitat due to the

exposed nature of the shallow open water bottoms that are being formed. Shallow

waters are likely to become deep waters, and salinity gradients would be less

estuarine, with a sharper distinction between saline and freshwater habitat as

coastal residents further attempt to protect self and property with levees, flood

gates, and other water control structures.

It is believed that marsh loss that has been experienced to date has increased this

land/water interface and increased fishery production. As land loss continues, it is

believed that this interface would peak and begin to decline. T his would, in turn,

result in a decline in fishery production. In some areas, continued marsh loss is

already resulting in the reduction of this interface.

With no action, the conversion of categories of EFH, such as inner marsh and marsh

edge, to estuarine water column and mud, sand, or shell substrates is expected to

continue. Over time, the No Action Alternative would result in a substantial

decrease in the quality of EFH in the Study Area, and reduce the area’s ability to

support federally managed species. Analysis of rates of wetland loss in the Study

Area indicated that approximately 18% of the wetlands will be lost by the year

2065.

The future without project condition would indirectly impact species that are linked

in the food chain to directly affected species. Population reductions in directly

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affected species, such as brown shrimp and white shrimp, affect species dependent

on shrimp for food. As marsh, barrier islands, and other EFH are directly lost, less

protection would be available to remaining EFH. These areas would be more

susceptible to storm, wind, and wave erosion. A decrease in species productiveness

would result as populations are stressed by habitat displacement and reduction.

4.3.2.7 Threatened and Endangered Species

The No Action Alternative would have no direct impacts on threatened and

endangered species or their critical habitat in the Study Area. Indirect impacts of

not implementing restoration features would result in the continued degradation

and loss of important and essential fish and wildlife habitats used by many

different fish and wildlife for shelter, nesting, feeding, roosting, cover, nursery, and

other life requirements. The loss and deterioration of transitional wetland habitats

would continue to impact, to some undetermined degree, all listed species that

potentially utilize the Study Area, including West Indian manatee, piping plover,

pallid sturgeon, Gulf sturgeon, green sea turtle, hawksbill sea turtle, Kemp’s Ridley

sea turtle, leatherback sea turtle, and loggerhead sea turtle. Adverse cumulative

impacts on listed species would be offset, to some degree, by the positive impacts of

implementing other Federal, state, local, and private restoration projects.

4.3.2.8 Cultural and Historic Resources

Subsidence and erosion are ongoing throughout the Study Area. In future without

project conditions, site erosion processes and subsidence continue unabated and

may affect cultural and historic resources.

4.3.2.9 Recreation

Recreational resources in the entire region that would most likely be impacted

under the No Action Alternative are those related to loss of wetlands and habitat

diversity as well as substantial salinity changes. In the West region, wetlands and

associated marsh habitat appear generally more stable than in the Central and

East regions due to freshwater and sediment provided by the Atchafalaya River,

which is nearby. However, some portions of the West region, specifically the lower

southeast portions are experiencing wetland loss and fragmentation. Under the No

Action Alternative, in the West region, the floating marsh habitat and intermediate

and brackish marsh habitat would continue to provide freshwater and saltwaterbased recreational opportunities, such as waterfowl hunting and fishing. However,

over time, land and habitat loss and associated changes in salinity levels

encroaching from the southeast could begin to negatively affect both freshwater and

saltwater- based fishing as well as waterfowl hunting.

By taking no action, continued saltwater intrusion, wetland and shoreline erosion

and associated wetland fragmentation and conversion to open water likely would

continue in the Central and East regions with negative impacts on recreation

resources. As marsh habitat decreases, areas for fish spawning decrease and,

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ultimately, the populations and diversity of fish species will diminish, which would

affect recreational fishing opportunities negatively. Similarly, with less freshwater

and intermediate marsh habitat, waterfowl hunting opportunities would likely

decrease. Ridge habitat would also likely continue to decline, reducing

opportunities for deer and other small game hunting.

Long-term impacts specifically in the Central and East regions may include loss of

associated recreational support facilities, such as marinas and bait shops that are

the basis for most recreational use. This would result in a reduction in economic

activity associated with recreational uses.

Cumulative impacts are the impacts on the environment that would result from the

incremental impact of the No Action Alternative from the 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 those supported by various sources including, but not limited to, the

CWPPRA and the USACE. However, the impacts of these other projects do not

extend to the entire 1,100 square mile area that is the Study Area. Despite these

other efforts, continued coastal erosion and increased levels of salinity would likely

occur throughout much of the Study Area.

Localized beneficial impacts may include improved habitat and protection for fish

and wildlife habitat during coastal storms due to the water control structures;

protection of new lands for hunting; and a walking path for hunters and sightseers

on the perimeter of the Pointe Au Chien WMA associated with the USACE

Morganza to the Gulf Hurricane Protection project. The CWPPRA West Lake

Boudreaux Shoreline Protection and Marsh Creation project will provide additional

nursery habitat for fish and improved food supply for waterfowl.

Other recent projects in the area had similar purposes and would similarly benefit

recreation by improving fish and wildlife habitat. The Avoca Island Diversion and

Land Building Project (CWPPRA Project Number TE-49) was approved in 2003 to

divert freshwater, sediment, and nutrients from Bayou Shaffer to rebuild eroded

wetlands of the Avoca Lake area. The Avoca Island Marsh Restoration project

funded through The North American Wetlands Conservation Act was scheduled to

begin in summer 2005 to restore coastal marsh. The GIWW Bankline Restoration

Project was approved for funding through the Natural Resources Conservation

Service in 2003 to protect wetland habitat and protect emerging freshwater floating

marsh.

4.3.2.10 Socioeconomics Resources – Navigation

A majority of Louisiana’s navigable waterways would be adversely impacted

without action as marshes and barrier islands that protect waterborne traffic on

inland waterways continue to erode. As land adjacent to and connecting these

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waterways disappears, waterways currently protected would be exposed to wind,

weather, and waves found in open bays and the Gulf of Mexico. Additionally,

navigation channels that cross open bays may silt in more rapidly or begin to shoal

in less predictable ways. The potential impacts to these waterways and the vessels

that use them include increased maintenance costs (e.g., dredging), the necessity for

higher horsepower vessels to counteract increased currents and wave forces, and

increased risk of groundings, collisions or storm damage to vessels and cargo.

Moreover, shoaling causes the thousands of tows that traverse this area annually to

slow down, thereby increasing both the transit time and cost of transportation. Due

to increased safety concerns, alternate methods of transportation may have to be

taken by hazardous commodities now utilizing the GIWW. These impacts would

have a corresponding effect on cargo rates, which would affect the local and national

economies.

The growth rate estimate for the Louisiana portion of the GIWW is 0.78% annually

(this is the midlevel estimate from a commodity forecast from the Calcasieu Lock

Replacement Study). Average annual growth for activity associated with rig

fabrication and the offshore service industry is 1.67% (this estimate comes from a

forecast prepared for the HNC Deepening Study). Any environmentally negative

impacts to navigation in the Study Area would worsen over time with the No Action

Alternative.

4.3.2.11 Socioeconomics Resources – Oil, Gas, and Utilities

Most of Louisiana’s onshore oil and gas production occurs in the Louisiana coastal

ecosystem. This area is at an elevated risk due to the land loss and ecosystem

degradation. Loss of wetland, marsh, and barrier islands presents a range of

threats to inshore and offshore oil and gas infrastructure. Existing inshore facilities

are not designed to withstand excessive wind and wave actions, which would

become more commonplace as existing marshes are lost or converted into open bays.

In addition, erosion and the subsequent disappearance of barrier islands would

allow gulf type swells from tropical storm events to travel farther inland. The

combination of these factors would increase the risk to inshore facilities. To address

this risk, the oil and gas industry would be faced with the decision to invest in

improvements in order to maintain production/transmission or conversely the

closure and abandonment of infrastructure.

The offshore oil and gas industry in the coastal zone is an important component in

meeting national energy requirements. Coastal land losses have, and will continue

to have, a negative effect on the extensive pipeline network located in coastal areas.

As the open water areas behind the barrier islands increase in size, the tidal

exchange volumes and velocities increase in the tidal passes and channels. This

action can lead to the scouring away of sediments atop buried pipelines, exposing

the pipelines and increasing the risk of failure or damage due to lack of structural

stability, anchor dragging, and boat collisions. Resulting production or

transmission shortfalls may result in disruptions in the availability of crude oil or

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natural gas to a significant part of the Unites States. The impact to these

nationally important resources would be felt in numerous ways depending upon

location (i.e., whether onshore or offshore).

4.3.2.12 Socioeconomics Resources – Commercial Fisheries

Concurrent with projected land loss in the Study Area would be an increase in

saltwater intrusion into some of the upper areas as marshes degrade. This would

result in a shift in the populations of fish and invertebrates, with more salinedominated species replacing freshwater species in some areas. The band of

intermediate salinity necessary for oyster production would likely narrow

significantly, and EFH for many commercial fishery species would likewise decline,

leading to a net loss in fisheries population size and diversity.

Wetland habitat losses would decrease the productivity of Louisiana’s coastal

fisheries. The commercial fishing and seafood industry would likely suffer

significant losses in employment as estuaries that are necessary to produce shrimp,

oysters, and other valuable species erode. Job losses would 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.

4.3.2.13 Socioeconomics Resources – Oyster Leases

The No Action Alternative would result in the persistence of existing conditions,

including the continued conversion of transitional estuarine wetlands to open water

habitats and associated saltwater intrusion. The continued loss of transitional

estuarine wetlands would adversely affect the local detritus-based oyster food web.

Organic detritus, derived mainly from vascular plants, is a major food source for

estuarine consumers, including oysters (Day et al., 1989). Hence, the loss of

wetlands in the Study Area would likely reduce the localized carrying capacity for

oyster leases in the area. As oyster production from leases declines, it would likely

result in lower oyster supply, higher oyster prices, and loss of income and jobs in the

oyster industry.

4.4 Alternatives *

4.4.1 Plan Formulation Rationale

This section of the report presents an overview of the plan formulation process for

the LCA ARTM Project. Specifically, management measures are presented,

screening criteria are discussed and applied, and future work to evaluate and

recommend measures is detailed. From these specific measures, conceptual

alternative plans are developed. During the plan formulation process, the PDT

followed guidance presented in the Planning Guidance Notebook ER 1105-2-100

(USACE, 2000a).

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For this study, the objectives address the project goals to reverse the current trend

of marsh degradation in the Study Area. In addition to the objectives relating to the

restoration of the ecosystem, increasing sediment into the ecosystem and reduction

of land loss are important considerations for developing and evaluating the various

alternatives. Planning constraints relevant to the project include natural resources

limitations, feasibility of restoration techniques, environmental impacts of human

activities in the Study Area, infrastructure that must be avoided or relocated, and

limitations on the characterization and simulation of environmental and coastal

processes that determine the effects of alternative plans. Solutions that address

these objectives and address the planning constraints were incorporated into the

conceptual alternative plans assembled from one or more of the available

management measures for ecosystem restoration of the Terrebonne Marshes.

4.4.2 Management Measures

Management measures were developed to address Study Area problems and to

capitalize upon Study Area opportunities. A management measure is a feature or

an activity that can be implemented at a specific site to address one or more

planning objectives. The PDT evaluated general measures for the Study Area, from

which specific measures were developed. The following measures were considered:

Freshwater Supply and Distribution

Freshwater distribution channel

Gated diversion structure

Groundwater for freshwater

Culverts

Outfall and distribution management

Open constrictions to water transport

Operation of HNC Lock

Canal dredging and placement

Sediment Supply and Distribution for Mechanical Marsh Creation

Dredging and placement of regional sediments

Sediment delivery from distant sources

Construct ridges to create marsh

Restore/Maintain Historic Geomorphic Features

Bank and shoreline protection

Invasive Species Management

Eradication program for nutria

Control of water hyacinth

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Create "No Wake" zones or develop speed restrictions

Navigation Management

Traffic management through scheduling

Reestablish marsh in target areas by planting

Vegetation Management

4.4.2.1 Screening of Management Measures

Initial Screening

The measures presented above were first screened based on their ability to meet the

following four first tier screening criteria:

Achievement of objectives – Measure supports one or all ecosystem planning

objectives.

Synergy with other state/Federal projects – Measure supports other state and

Federal programs and projects aimed at marsh restoration.

O&M requirements – Measure is relatively simple and inexpensive to operate

and maintain.

Efficiency of delivery – Measure has variable timeframes for creating acreage

of new habitat and positively impacting existing marsh; measure includes a

timely ability to create new marsh.

Final Screening

If measures passed the first tier of screening, they were then screened based on

their ability to meet the following five Second Tier Screening Criteria:

Infrastructure impacts – Measure does not negatively impact oil and gas or

municipality infrastructure in the Study Area.

Threatened/ endangered species – Measure does not have a negative impact

on state or federally listed Threatened/ Endangered Species.

Wetland impacts – Measure does not result in net wetland loss.

Flooding – Measure does not have the potential to induce flooding on existing

developed areas.

Navigation – Measure does not have the potential to introduce navigational

hazards or increased O&M costs.

The following measures were eliminated from further consideration in all subunits

based on the screening criteria above:

Groundwater for freshwater

Dredging and placement of regional sediments

Sediment delivery through pipeline infrastructure

Eradication program for nutria

Create “No Wake” zones

Additional information describing the screening process is included in the FS/SEIS

(Volume III).

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4.4.3 Preliminary Alternative Plans

Remaining management measures were grouped into a preliminary list of

strategies to produce a full range of alternative plans as required by NEPA and

USACE regulations. The strategies were designed to be significantly different from

one another and to represent the entire range of solutions from no action to full

restoration in consideration of study goals, objectives, and constraints. Modification

to the operation of the proposed HNC Lock Complex is included in all action

alternatives in accordance with guidance received from the LCA Program

Management Team. This was done because the HNC Lock Operations are integral

to all alternatives developed for LCA ARTM Project in a synergistic and holistic

approach to the problems and opportunities of the Study Area. From these

strategies, alternatives that contained suites of general measures were developed.

Specific measures were generated from the general measures. The strategies are as

follows:

1. No Action Plan (ARTM S1): Alternatives developed under this strategy

will include no measures from this study. This alternative includes operation

of the HNC Lock Complex under the Morganza to the Gulf operations plan.

The assumption was made that the Morganza to the Gulf Project would be

completed by 2025. The operating plan for the Morganza to the Gulf HNC

flood gates calls for closure of the flood gates whenever necessary to prevent

saltwater intrusion up the HNC or during tropical storm / hurricane

conditions. Accordingly, for purposes of future without project hydraulic

modeling, the assumption was made that the HNC flood gates would be

closed to prevent saltwater intrusion for 2 months each year starting in 2025.

During these closure periods, it was assumed that the sluice gates within the

HNC Lock Complex would be open. Other water control structures

associated with the Morganza to the Gulf Project would only be utilized

under tropical storm / hurricane conditions, and, therefore, would not

appreciably impact the hydrology of the Study Area under normal operating

conditions. Therefore, these structures were not included in the hydraulic

modeling for the LCA ARTM Project.

2. Utilize Existing Flow with Management Measures to Maximize

Restoration Efforts (ARTM S2): Utilize existing flow along with

management measures to maximize restoration efforts. Alternatives

developed under this strategy will focus on modifying the interior portions of

the Study Area. They will not actively introduce additional sediment and

nutrient laden freshwater from other sources, but will instead attempt to

redistribute the existing inputs to more efficiently utilize freshwater.

3. Utilize Increased Flow from the Atchafalaya River and Management

Measures to Maximize Restoration Efforts (ARTM S3): Alternatives

developed under this strategy will focus on increasing supply from the

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Atchafalaya River to introduce additional sediment and nutrient laden

freshwater along with modifying existing interior flows.

4. Utilize Increased Flow from Locations East of the Study Area and

Management Measures to Maximize Restoration Efforts (ATRM S4):

Alternatives developed under this strategy will focus on attempting to draw

water from outside the Study Area to the east and modifying existing interior

flows.

5. Utilize Increased Flow from the Atchafalaya River and Locations

East of the Study Area and Management Measures to Maximize

Restoration Efforts (ARTM S5): Alternatives developed under this

strategy will combine ARTM S3 and ARTM S4 thus focusing on maximizing

flow inputs from both the Atchafalaya River and locations east of the Study

Area along with modifying existing interior flows.

Results

The PDT developed eight alternatives composed of different groups of general

measures that addressed the five strategies above. From the suites of remaining

general measures, 94 specific measures were grouped into eight study alternatives.

The interagency PDT then evaluated these alternatives and their specific measures.

Many of the specific measures were developed for CWPPRA projects. As part of the

CWPPRA planning process, the problems and needs of the area were considered.

Thus, many of the measures included in the project have already been evaluated for

their suitability and benefits. After evaluation, 33 measures were eliminated.

Table 4-6 summarizes the retained measures and their associated alternatives.

Table 4-6: Management Measures and Associated Alternatives

Alt IDa Measure Name Description

All

CL1 Central Lock Complex #1 Multi-purpose operation of proposed HNC Lock Complex

2,

3, 6,

8

EC5 East Culvert #5 Bridge construction with Obermeyer gates installed

between the piers

2 - 5, 8

EC2b East Culvert #2 Box culvert

EC3b East Culvert #3 Flap gated box culverts w/variable crest outfall

ED6b East Dredge Channel #6 Dredge a portion of Grand Bayou

EG1b East Spoil Gap #1 Gap in canal spoil bank

EG2b East Spoil Gap #2 Gap in canal spoil bank

EP7 East Plug #7 Boat bay on Cutoff Canal at junction with Point au Chien

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Alt IDa Measure Name Description

EX1b East Removal #1 Rock weir removal

EX2b East Removal #2 Soil plug removal

CC3 Central Culvert #3 Gated control structure

CC5b Central Culvert #5 Aluminum flap-gated culvert

CC6b Central Culvert #6 Aluminum flap-gated culvert

CC7b Central Culvert #7 Aluminum flap-gated culvert

CC8b Central Culvert #8 Aluminum flap-gated culvert

CC9b Central Culvert #9 Aluminum flap-gated culvert

CC10b Central Culvert #10 Aluminum flap-gated culvert

CC11b Central Culvert #11 Aluminum flap-gated culvert

CC12b Central Culvert #12 Aluminum flap-gated culvert

CC13b Central Culvert #13 Box culverts with sluice gates under Hwy 57

CC14b Central Culvert #14 Flap-gates each with a stop log bay

CC15b Central Culvert #15 Timber weir placed at 90 to flow with boat openings

CD1 Central Dredge Channel

#1 Dredge Bayou Provost

CD2 Central Dredge Channel

#2 Dredge part of Bayou Butler

CD6P

b Central Dredge Channel

#6 Dredge new water conveyance channel

CD7P

b Central Dredge Channel

#7 Dredge Bayou Pelton to enlarge it

CP1 Central Plug #1 Soil plug in Robinson Canal

CP2P

b Central Plug #2 Soil plug in canal near Bayou Butler

CS1 Central Diversion

Structure #1 Bayou Butler sluice gated box culverts under Hwy 57

2-5

EC6 East Culvert #6 Flap gated box culverts

EC7 East Culvert #7 Flap gated box culverts

ED2 East Dredge Channel #2 Canal dredging

ED7P

b East Dredge Channel #7 Canal dredging

EM1 East Marsh Berm #1 A linear soil berm placed perpendicular to flow

EM3 East Marsh Berm #3 A linear soil berm placed perpendicular to flow

CC4 Central Culvert #4 Gated control structure

CD3 Central Dredge Channel

#3 Dredge Falgout Canal

CLV1P

b Central Levee #1 New forced drainage levee

CLV2P

b Central Levee #2 New forced drainage levee

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Alt IDa Measure Name Description

CM2 Central Marsh Berm #2 A linear soil berm placed perpendicular to flow

CM3 Central Marsh Berm #3 A linear soil berm placed perpendicular to flow

CM4 Central Marsh Berm #4 A linear soil berm placed perpendicular to flow

CT12b Central Terracing #1 A grid of 10-foot wide berms perpendicular to surge

CT2b Central Terracing #2 A grid of 10-foot wide berms perpendicular to surge

CT3b Central Terracing #3 A grid of 10-foot wide berms perpendicular to surge

CT6b Central Terracing #6 A grid of 10-foot wide berms perpendicular to surge

CT7b Central Terracing #7 A grid of 10-foot wide berms perpendicular to surge

CT8b Central Terracing #8 A grid of 10-foot wide berms perpendicular to surge

WD2 West Dredge Channel #2 Dredge a part of Carencro Bayou and create new canal

WP1 West Plug #1 Soil plug

WW2b West Weir #2 Rock filled sheet pile weir with boat openings

Alt. 2 -

6, 8

ED3b East Dredge Channel #3 Canal dredging

ED5 East Dredge Channel #5 Dredge new canal

Alt. 2 - 6

CD4 Central Dredge Channel

#4

Dredge a new secondary channel along the GIWW4

CC1

at Hwy

24 bridges

Central Culvert #1 Box culvert in CD4 channel under Hwy 24 bridge

CC2 Central Culvert #2 Box culvert in the CD4 channel under Hwy 24 bridge

WD3 West Dredge Channel #3 Dredge a portion of GIWW

Alt. 3, 5, 6

4

WO2 West Shoreline

Protection #2

Riprap the banks of Bayou Chene and Avoca Island Cutoff

around the mouth of Bayou Penchant

WS4 West Diversion Structure

#4 Gated box culverts

Alt. 4 & 5

EP8 East Plug #8 Soil plug in Bayou L’eau Bleu adjacent to Hwy 24 bridge

ES2 East Diversion Structure

#2 Pump station under Hwy 24

a ID – Measures are identified by a unique sequence such as WC1. The first letter describes the subunit location: W = Bayou

Penchant, C = Lake Boudreaux, and E = Grand Bayou. The second and third letters describe the type of measure: C = culvert,

D = dredge, M & MC = marsh creation, X = removal, S = structure, L = lock, G = gap, P = plug, LV = levee, T = terracing, O =

shoreline protection and W = weir. The number provides a unique ID for that particular type of measure in that subunit. In

some cases, measures were redesigned but the ID was retained.

b Measures in bold were proposed as part of a CWPPRA project.

4.4.4 Identification of the Final Array of Alternatives

Based upon the results of the plan formulation analyses and screening, eight

alternatives (designated as No Action and Alternatives 2 through 8) were included

in the Final Array of Alternatives. Alternatives 2 through 8 incorporate various

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combinations of the remaining 61 measures. Modification of the proposed HNC

Lock Complex is included in all action alternatives including the No Action

Alternative. The other 61 measures were incorporated into various alternatives.

The Final Array of Alternatives is described below.

No Action Alternative: This alternative includes no measures from this study.

The future condition will include sea level rise, subsidence, and other projects that

are under construction or are likely to be constructed. This alternative includes

operation of the HNC Lock Complex under the Morganza to the Gulf operations

plan. The assumption was made that the Morganza to the Gulf Project would be

completed by 2025. The operating plan for the Morganza to the Gulf HNC flood

gates calls for closure of the flood gates whenever necessary to prevent saltwater

intrusion up the HNC or during tropical storm / hurricane conditions. Accordingly,

for purposes of future without project hydraulic modeling, the assumption was

made that the HNC flood gates would be closed to prevent saltwater intrusion for 2

months each year starting in 2025. During these closure periods, it was assumed

that the sluice gates within the HNC Lock Complex would be open. Other water

control structures associated with the Morganza to the Gulf Project would only be

utilized under tropical storm / hurricane conditions, and, therefore, would not

appreciably impact the hydrology of the Study Area under normal operating

conditions. Therefore, these structures were not included in the hydraulic modeling

for the LCA ARTM Project.

Alternative 2 – Use Existing Flow and Management Measures: This

alternative would redistribute existing freshwater to benefit Terrebonne marshes

using a variety of measures. To achieve this, GIWW constrictions would be

eliminated. Additionally, the following measures to restrict increase, and control

water are proposed for each of the three subunits. In the West – Bayou Penchant

Area, dredging, a sediment plug, and a weir would be utilized. In the Central –

Lake Boudreaux Area, culverts, levees, dredging, marsh terraces and berms,

sediment plugs, modified operation of the future HNC Lock Complex, as described

in Alternative 7, and a large sluice gated box culvert are proposed. In the East –

Grand Bayou Area, culverts, dredging, gaps in canal spoil banks, marsh berms,

sediment plugs, and removal of a weir and soil plug are proposed.

Alternative 3 – Increase Atchafalaya River Flows and Utilize Management

Measures: This alternative would increase Atchafalaya River inflows and

redistribute existing and increased flows of freshwater. Alternative 3 includes all

the measures in Alternative 2 and two additional. The additional measures are in

the West – Bayou Penchant Area. To increase flows from the Atchafalaya River,

water would be moved from Bayou Shaffer to the Avoca Island Cutoff/Bayou Chene.

This would be accomplished by creating an opening through the Avoca Island levee

and installing a large gated diversion structure (WS4) in the opening. The

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remaining measure (WO2) would place stone along the shore of Bayou Chene and

Avoca Island Cutoff to protect from increased flows.

Alternative 4 – Increase Flow from East of the Study Area and Utilize

Management Measures: This alternative would increase freshwater flows from

east of the Study Area and redistribute existing and increased flows of freshwater.

Alternative 4 includes all but one of the measures in Alternative 2 and has two

additional measures in the East – Grand Bayou Area. In Alternative 2, a new

Highway 24 bridge with Obermeyer gates between the piers (EC5) is proposed to

connect the GIWW to Grand Bayou. In Alternative 4, this measure would be

replaced by a pump station (ES2). The pump station would increase freshwater

delivery to the Grand Bayou watershed but not the other subunits. The second new

measure is a soil plug (EP8) in Bayou L’eau Bleu. Bayou L’eau Bleu connects the

canal receiving the pump station outflow to the GIWW. The pump station is

pumping water from the GIWW; thus, the soil plug would be necessary to prevent

recirculation of water.

Alternative 5 – Increase Flow from the East and from the Atchafalaya

River and Utilize Management Measures: This alternative would increase

flows from the east and west and redistribute existing and increased flows of

freshwater. This alternative is a combination of Alternatives 3 and 4. The only

measure in Alternative 3 not within this alternative is the Highway 24 bridge with

Obermeyer gates (EC5), which would be replaced by a pump station (ES2), as in

Alternative 4.

Alternative 6 – Increase Atchafalaya River Flow and Utilize Management

Measures: This alternative would increase Atchafalaya River inflows and improve

the passage of freshwater through the GIWW while slowing water passage to the

gulf through the HNC. Alternative 6 differs from Alternative 3 because Alternative

6 only includes water management measures along the GIWW. The measures to

increase Atchafalaya River inflows are the same as Alternative 3. A large gated

diversion structure (WS4) would be placed in the new opening created in the Avoca

Island levee. Shoreline protection would be placed (WO2) in Bayou Chene and

Avoca Island Cutoff. To improve freshwater flows through the GIWW to Grand

Bayou, the following measures from Alternative 2 are proposed. In East – Grand

Bayou Area, dredging is proposed to connect Grand Bayou to the GIWW (ED5) and

enlarge Grand Bayou (ED3). Where ED5 goes through Highway 24, a new bridge

with Obermeyer gates between the piers (EC5) is proposed. In Central – Lake

Boudreaux Area, the GIWW would be constricted as it passed under Highway 24.

The Highway 24 bridge columns does not allow for channel enlargement. Therefore,

dredging a new secondary channel with two culverts, one under each Highway 24

bridge, is proposed. Modifying the operation of the HNC Lock Complex, as described

in Alternative 7, is also included in this alternative.

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Alternative 7 – Utilize Existing Flow and Management Measures: This

alternative would slow the movement of freshwater to the Gulf of Mexico and, thus,

put additional freshwater onto northern Terrebonne marshes. The one measure in

this alternative is modified operation of the proposed HNC Lock Complex (CL1).

The HNC Lock Complex is part of the proposed USACE Morganza to the Gulf

project for coastal storm damage reduction. The assumption was made that the

Morganza to the Gulf Project would be completed by 2025. The operating plan for

the Morganza to the Gulf HNC Lock Complex calls for closure of the flood gates

whenever necessary to prevent saltwater intrusion up the HNC or during tropical

storm/hurricane conditions. Accordingly, for purposes of future without project

hydraulic modeling, the assumption was made that the HNC flood gates would be

closed to prevent saltwater intrusion for two months each year starting in 2025.

Alternative7 proposes to keep the flood gates closed year round to hold water back,

thus moving freshwater onto northern marshes. When the flood gates are closed,

boat traffic would travel through the lock chambers. As part of this alternative, an

industry traffic management plan would be developed for vessels exceeding the lock

size that will require the sector gates to be opened. This alternative proposes to

keep the sluice gates located in the lock structure walls open, with the exception of

when tropical events are occurring.

Alternative 8: Utilize Existing Flow and Management Measures to Focus

Freshwater Flows on the Most Critical Areas of the East and Central Study

Sub units: This alternative redistributes existing freshwater to benefit the most

critical areas of the east and central study subunits using a variety of measures.

This alternative represents an increment between Alternative 7 and Alternative 2

and contains many of the features of Alternative 2. In the Central – Lake

Boudreaux Area, culverts, levees, dredging, sediment plugs, modified operation of

the future HNC Lock Complex, and a large sluice gated box culvert are proposed.

In the East – Grand Bayou Area, culverts, dredging, sediment plugs, modified

operation of the future HNC Lock Complex, as described in Alternative 7, and a

large sluice gated box culvert are proposed. In the East – Grand Bayou Area,

culverts, dredging, gaps in canal spoil banks, sediment plugs, and removal of a weir

and soil plug are proposed.

The alternative plans and component measures were evaluated relative to the

project goals and objectives as well as to the objective of NER plan. As a result of

the evaluation, some specific measures were eliminated from the alternatives, but

all eight initial alternatives were carried forward for further analysis.

4.4.5 Environmental Consequences *

An analysis was conducted on the potential environmental consequences of

implementing alternative plans to reverse the trend of degradation in the Northern

Terrebonne Marshes. The analysis compares the No Action Alternative to the

alternatives retained for detailed analysis. The No Action Alternative is considered

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to be the same as the future without project condition and analyzes the future

conditions of the resource over a 50-year period of analysis from 2015 to 2065.

The potential environmental consequences of implementing the No Action

Alternative and Alternatives 2 through 8 were considered for increasing the flow of

freshwater, sediments, and nutrients to the Study Area. A comparison of the direct,

indirect, and cumulative impacts of all alternatives were considered.

No Action Alternative: Due to the large area and variations of habitats and

conditions, without Federal action, soil erosion and land loss in some areas and land

gain in other areas would continue. WVA analysis predicted that overall 102,000

acres of remaining vegetated wetlands in the Study Area would be lost over the 50-

year period of analysis. Natural and man-made levees would continue to subside

and marsh soils would not be able to maintain their elevations due to subsidence,

decreased plant productivity, and wave erosion. 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,

aesthetics, and socioeconomic resources. Air quality would likely decline due to

increased emissions from continued population growth, coupled with the loss of

wetland vegetation that would no longer be available to remove gaseous pollutants.

Invasive species would likely continue to pose a threat as landscape disturbance

and deterioration is prolonged. Expected major impacts caused by spread of

invasive species are reduced vegetative biodiversity, alteration of abiotic factors and

coastal ecosystem processes, and reduction of wildlife food and habitat

Alternative 2: Implementation of Alternative 2 would result in increased

freshwater inputs and associated nutrients in the Study Area due to water control

structures. Flows in the GIWW would increase up to 50% east of Houma and there

would be stage increases of 0.1 to 0.3 ft over most of the Study Area.

Improved distribution of freshwater and nutrients would enhance vegetative

productivity and optimize conditions for maintenance of all vegetative habitats,

benefitting the extensive fish and wildlife resources of the area over much of the

Study Area. Increased freshwater flows would result in decreased salinity levels

throughout much of the Study Area. Construction of project features would result

in conversion to open water of 148 acres of swamp, 343 acres of freshwater marsh,

248 acres of intermediate marsh, and 182 acres of brackish marsh. Alternative 2

would also result in 23 acres of swamp being converted to upland (levee).

Implementation of Alternative 2 would result in the generation of 3,220 AAHUs

over the No Action Alternative by preventing the loss of 9,655 acres of emergent

marsh habitat over the 50-year period of analysis. The emergent marsh referred to

here is mix of primarily brackish and some saline marsh, depending on location

within the Study Area. Improvement of habitat will lead to increased habitat for

wetland dependent wildlife, decreased competition for resources, and localized

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stabilization or improvement in wetland-dependent wildlife populations. This

alternative would have positive synergistic effects on transportation, oil, and gas

infrastructure in combination with other restoration effectors through restoration of

marsh, which indirectly provided wave and storm surge buffering to vulnerable

transportation routes.

Some areas are projected to decline at a faster rate with implementation of

Alternative 2 due to a reduction in freshwater and associated nutrients; the

majority of the impacts in these areas are seen in decreases in emergent marsh

habitat. According to salinity modeling, implementation of Alternative 2 would

negatively impact oyster leases in some areas by causing salinities to move outside

of the ideal range. Navigation on the HNC would be negatively impacted by the

modified operation of the lock complex. Stage increases of up to 0.2 ft could be seen

in the western portions of the Study Area. Stage increases of up to 0.3 ft could be

seen in the central portions of the Study Area. Stage increases of up to 0.1 ft could

be seen in the eastern portions of the Study Area. Stage decreases of up to 0.2 ft

could be seen on the GIWW at certain times of year. Implementation of Alternative

2 would require the relocation of 13 residential structures.

Alternative 3: Cumulative impacts would be similar to Alternative 2.

Implementation of Alternative 3 would create, protect or nourish a total of 10,308

acres of emergent marsh over the 50-year period of analysis. Other cumulative

impacts would generally be similar to Alternative 2

Alternative 4: Cumulative impacts of Alternative 4 on soils and substrate would

be similar to those of Alternative 2. Changes in flow would be similar to Alternative

2 but with increased flows and stages in the Grand Bayou due to the pump station.

Alternative 4 would create, protect or nourish a total of 12,204 acres of emergent

marsh soils in the 50-year period of analysis. Cumulative impacts on sedimentation

and erosion would generally be similar to Alternative 2. Water quality and salinity

impacts would be similar to Alternative 2 although salinity decreases in Grand

Bayou would be greater due to the pump station. Many other cumulative impacts

would generally be similar to Alternative 2.

Alternative 5: Alternative 5 would create, protect or nourish a total of 13,934

acres of marsh habitat. Changes to flow would be similar to Alternative 4 since

both incorporate a pump station. Other cumulative impacts would generally be

similar to Alternative 2.

Alternative 6: Alternative 6 would create, protect, or nourish a total of 7 acres of

marsh habitat. Changes in flow in the GIWW would range from decreases of 5% to

increases of 5%. There would also be stage increase in the Penchant Basin and

Grand Bayou Area of 0.1 ft. Other cumulative effects would generally be similar to

Alternative 2 but to a lesser extent. The relatively large number of AAHUs in

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comparison to the number of acres of emergent marsh loss prevented is due to the

fact that Alternative 6 would generate benefits associated with SAV and marsh

edge (WVA variables V2 and V3) despite very little prevention of marsh loss.

According to salinity modeling, Alternative 6 would cause salinities in several areas

to fall below the ideal range for oysters impacting oyster leases; most of the changes

are minor but two areas are likely to see major changes. Other cumulative impacts

would generally be similar to Alternative 2 but to a lesser degree.

Alternative 7: Alternative 7 would lead to a net loss of 2,651 acres of emergent

marsh soils by conversion to open water over the 50-year period of analysis. Despite

resulting in a net loss of emergent marsh soils, Alternative 7 is still projected to

have a positive impact on marsh habitat in the Study Area through overall

improvement of the remaining marsh. Cumulative impacts on hydrology would

generally include reduced flow in the HNC. According to salinity modeling,

Alternative 7 would cause salinities in several areas to fall below the ideal range for

oysters; however, most of the changes are minor and only one area would likely be

negatively impacted. Other cumulative impacts would generally be similar to

Alternative 2 but to a lesser degree.

Alternative 8: Alternative 8 would create, protect or nourish 989 acres of

emergent habitat from conversion to open water over the 50-year period of analysis.

This would result in a yield of 1,214 AAHUs over the No Action Alternative. This

alternative redistributes existing freshwater within the Study Area to benefit the

eastern and central Terrebonne marshes using a variety of measures in an effort to

focus freshwater distribution to the most critical areas of marsh decline in the

Study Area. This alternative represents an increment between Alternative 7 and

Alternative 2 and contains many of the features of Alternative 2. Cumulative

changes in flow would include impacts similar to Alternative 2 but with no stage

impacts in the western Study Area.

4.4.6 Comparison of Alternative Plans

In order to select a recommended plan, a separate CE/ICA was conducted on the

eight alternatives in the final array using the IWR Planning Suite. The ecosystem

benefits were determined for the alternatives using the WVA methodology.

Inclusion of fisheries access impacts in the calculation of AAHUs may have resulted

in negative AAHUs for all alternatives, despite net gains in wetland acreages.

These measures are designed to correct significant hydrologic alterations on manmade canals which are thought to be significant causes of wetland degradation and

loss and which resulted in artificially increased fisheries access. In addition, other

natural and man-made waterways exist for fisheries access. Therefore, the decision

was made to eliminate this potential impact when calculating benefits associated

with each alternative. Potential modifications to this methodology are being

investigated by USFWS in consultation with NMFS, LDWF, and other interested

natural resource agencies.

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The WVA model is undergoing model certification in accordance with EC 1105-2-

407. The model has undergone external review and the WVA revision

documentation and spreadsheets have been submitted to the ECO-PCX. The ECOPCX 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

this project can be found in Appendix K of Volume III.

Rough cost estimates were developed to conduct the CE/ICA of the various

alternative plans. Items included in the first cost construction estimates are

mobilization, dredging, placement, demobilization, contingency, engineering and

design during construction, supervision and administration, and real estate.

Monitoring as well as O&M are shown as separate amounts on the table. Table 4-7

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 the CE/ICA process. Further details

can be found in the FS/SEIS (Volume III).

Table 4-7: Alternatives Costs and Benefits

Alternative AAHUs Costa

Annualized

(Dollars) Cost

Annualized

Monitoring

Cost b

Annualized b OMRR&R

Total

Annualized

b

Investment

Cost

1

(No Action)

N/A

N/A N/A N/A N/A N/A

2 3,220 $203,047,200 $10,066,504 $396,686 $72,514 $10,535,704

3 3,325 $232,041,000 $11,503,935 $396,686 $75,889 $11,976,509

4 4,258 $253,038,800 $12,544,946 $396,686 $1,656,894 $14,598,526

5 4,719 $294,899,600 $14,620,286 $396,686 $1,660,269 $16,677,241

6 776 $134,199,000 $6,653,206 $396,686 $10,175 $7,060,066

7 243 $42,000 $2,082 $258,513 $0 $260,595

8 1,214 $86,777,600 $4,302,187 $396,686 $48,684 $4,747,557

N/A = not applicable

a Preliminary costs were developed for planning purposes only. Cost estimate is not the fully funded cost. Costs include real

estate and cultural resources.

b Discount rate = 4-3/8%; OMRR&R costs do not include incremental costs associated with the multipurpose operation of the

HNC Lock Complex. These costs have not been determined at this time.

At this point in the analysis, Alternatives 4 and 5 were removed from consideration.

At the TSP meeting during the plan selection process, it was determined

Alternatives 4 and 5 were not sustainable from an efficiency or acceptability

standpoint. These alternatives required a large 4,000 cfs pumping station at the

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confluence of the GIWW and Grand Bayou. The large pump station adversely

impacted the isohalines in the Barataria Basin and would have forced salt water

intrusion up into Bayou Lafourche. The interagency team determined that these

were unacceptable adverse environmental impacts and removed the alternatives

from further consideration and analysis. The effects of the pumping station were

also inconsistent with the USACE EOPs concerning sustainability.

The CE/ICA analysis below shows additional analysis of the Alternatives 2, 3, 7,

and 8 to be cost effective (Table 4-8). Aside from the No Action Alternative,

Alternative 7 exhibited the lowest average annual cost per unit of all alternatives,

$1,072 per AAHU. Alternative 8 exhibited the highest average annual cost per unit

of all alternatives, $3,910 per AAHU. However, as the plans are linear in benefits

and costs, a CE/ICA is conducted on all of the cost-effective alternatives to

determine the Best Buy plans. Best Buy plans provide the greatest increase in

ecosystem benefits for the least increase in cost.

Table 4-8: Summary of WVA Analysis AAHUs, IWR Planning Benefits for

Alternatives in the Final Array.

Alternative AAHU

Total

Annualized

Cost

Costeffective

(Yes / No /

Best Buy) ab

Annualized

Cost Per

Unit

(AAHU)

Incremental

Cost per

AAHU

7 243 $260,595 Best Buy $1,072 $1,072

8 1,214 $4,747,577 Yes $3,910

2 3,220 $10,535,704 Best Buy $3,272 $3,452

3 3,325 $11,976,509 Best Buy $3,601 $13,650

a Preliminary costs were developed for planning purposes only. Cost estimate is not the fully funded cost. Costs

include real estate and cultural resources.

b Discount rate = 4-3/8%

Overall, the CE/ICA process resulted in Alternatives 7, 2, and 3 being designated as

Best Buy plans.

As shown in Table 4-8, Alternative 7 provides 243 AAHUs at an annualized

incremental cost of $260,595. Alternative 2 provides 2,977 additional AAHUs

compared to Alternative 7, at an annualized incremental cost of $10,275,120.

Alternative 3 provides 106 additional AAHUs compared to Alternative 2 at an

annualized incremental cost of $1,440,805. The first Best Buy plan is the most

efficient plan from an incremental cost per AAHU perspective. However, if a higher

level of output (AAHUs) is desired than that provided by the first Best Buy plan,

the second Best Buy plan becomes the most efficient plan for producing additional

output, and so on. The recommended Best Buy Plan is Alternative 2, generating

3,220 WVA AAHUs at a total annualized investment cost of $10,535,704.

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4.4.7 National Ecosystem Restoration Plan

Based on the results of the WVA modeling, the IWR Planning analysis, and the

comparisons to the future without project condition, Alternative 2 was chosen to be

the NER plan. This alternative focuses on increasing the freshwater supply from

the GIWW to the Terrebonne Marshes. Alterative 2 will utilize flow management

measures to achieve sustainable environmental benefits in nationally significant

aquatic ecosystem. Existing freshwater will be more efficiently distributed and

flows will be increased where possible.

The non-Federal sponsor supports the NER plan; therefore, no separate LPP is

identified. While the NER plan is not the environmentally preferable plan, it

reasonably maximizes the environmental benefit.

4.4.8 Environmentally Preferable Alternative

Based on the evaluation conducted as part of this EIS it has been determined that

Alternative 3 is the EPP. This alternative focuses on increasing the fresh water

supply from the GIWW to the Terrebonne Marshes. Existing fresh water will be

distributed more efficiently and flows will be increased where possible.

4.4.9 Plan Selection – Recommended Plan

Comparison of the alternative plans carried over for detailed analysis and the No

Action Alternative identified Alternative 2 as the recommended plan / NER plan.

This alternative meets the study objectives and would result in restoration of some

deltaic processes within the Study Area. Alternative 2 would provide a total of

3,220 AAHUs by reducing wetland losses in the Study Area by 9,655 acres of

existing wetlands. Alternative 2 fits into the framework of Section 902 cost cap

limit of WRDA 1986. Fully funded project cost and 902 limit are shown in Table

4-9. The recommended plan is shown in Figure 4-5. Table 4-10 shows the benefits

and costs for the two components of the combined LCA ARTM Project.

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WRDA 2007 Section 7006(e)(3) 4-63 October 2010 Figure 4-5: LCA ARTM - recommended plan (Alternative 2)

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Table 4-9: Maximum Cost Including Inflation through Construction

Authorized cost in WRDA 2007 Title VII,

Section 7006 (e)(3)(A):

$239,300,000

Cost index useda CWBS Feature Code 6

Fish and Wildlife Facilities

:

EM 1110-2-1304 (Revised 31 Mar 2010)

Cost index ratio:

1Q FY07 to 3Q FY15

1.17

Fully funded project cost estimateb: $280,946,400

(Inflation applied from 10/2006 to 7/2015)

20% of authorized cost: $47,860,000

Monitoring and adaptive managementc $19,209,500 + $1,980,000

= $21,189,500

:

(per WRDA 2007 Section 2039)

Maximum cost limited by Section 902 B: $280,946,400 + $47,860,000 +

$21,189,500

= $349,995,500

Recommended plan cost $305,500,000

a The cost index applied is derived from: EM 1110-2-1304, 31 Mar 10, CWCCIS. b For the purposes of applying the cost index to the WRDA authorized cost, each project was adjusted for inflation

from October 2006 price levels to the midpoint of construction.

c This is the cost of any modifications required by law. This is derived from Section 8.0 of each project’s

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.

Table 4-10: Costs and Benefits for Combined LCA ARTM Project

Alt. 2

(Recommended Plan

/ NER)

ARTM MOHNL Total

AAHUs 2,977 243 3,220

Fully funded project costa $303,900,000 $1,600,000 $305,500,000

Authorized cost in WRDA Title VII,

Section 7006 (e)(3)(A) for LCA ARTM

$221,200,000 $18,100,000 $239,300,000

Maximum cost limited by Section

902

$325,496,000 b$24,500,000 $349,995,500

aFully funded project cost was adjusted for inflation from October 2006 price levels to the midpoint of project

construction.

b Includes inflation and monitoring and adaptive management costs

The non-Federal sponsor supports Alternative 2 Plan; therefore, the LPP is

identified as Alternative 2.

4.4.9.1 Components

The recommended plan is also the NER plan. The recommended plan / NER Plan

(Alternative 2) involves construction of 56 structures and other water management

features and the opportunistic operation of the HNC Lock Complex in an effort to

holistically address the declining health of the Terrebonne Marshes ecosystem.

There are two water diversion structures that are at critical points in the

Terrebonne Marshes. The Central Diversion Structure (CS1), which involves

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constructing six 10-foot by 10-foot gated box culverts on Bayou Butler under

Highway 57, would increase fresh water movement from the HNC to Bayou Grand

Caillou / Lake Boudreaux. The Eastern Culvert #5 (EC5) is composed of a bridge

with five 83-foot spans with two 68.5-foot spans accommodating Highway 24.

Associated with this bridge are five 80-foot Obermeyer gated openings, for a total

flow opening width of 400 feet.

EC5 is intended to convey fresh water from the GIWW to Grand Bayou under

Highway 24. Detailed information about each structure included in the

recommended plan / NER plan is available in Volume III.

The recommended plan / NER Plan meets most planning objectives. The

recommended plan would decrease the rate of decline of the wetlands to ensure

their ability to provide geomorphic and hydrologic form and function for the 50-year

period of analysis. Marsh habitat for essential fish and wildlife species would be

sustained, mimicking as closely as possible conditions that occur naturally in the

area. The alternatives were designed to work with the natural, fluid, soft

environment of coastal Louisiana. This plan fits within the current cost and scope

authorization, has stand-alone utility, and is environmentally beneficial.

Overall, the recommended plan / NER plan would reduce land loss in the Study

Area from 101,570 to 91,915 acres, thus preventing the loss of 9,655 acres of marsh

habitat over the 50-year period of analysis. Alternative 2 would yield 3,220 AAHUs

over the No Action Alternative.

This plan, by increasing the freshwater and nutrient input into a freshwaterdeprived system, would let the ecosystem “self-regulate,” letting natural wetland

processes take over. Per ER 1105-2-100 Section E-30, “The objective of Civil Works

ecosystem restoration is to restore degraded significant ecosystem structure,

function, and dynamic processes to a less degraded, more natural condition.

However, partial restoration may be possible, with significant and valuable

improvement made to degraded ecological resources.” (USACE, 2000a) The

Terrebonne Marshes provide important geomorphic, hydrologic and habitat

functions in the Study Area. Loss of these functions would have impacts beyond the

Study Area.

The significance of the ecosystem outputs plays an important role in ecosystem

restoration evaluation per Section E-37 of ER 1105-2-100. The outputs are

institutionally recognized. This project is listed in the Louisiana State Master Plan

and is designated as a critical near-term feature in the LCA Report. There is public

support in Louisiana for this project, with specific emphasis on beginning

construction as soon as possible.

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The outputs are technically recognized. Examples of technical significance follow:

Scarcity: Louisiana’s coastline represents 90% of the wetlands in the

contiguous United States and is disappearing at an alarming rate. This

unique and scarce habitat has high fish and wildlife values.

Representativeness: The recommended plan would greatly benefit existing

coastal marshes in the Study Area.

Status and trends: The Study Area is declining and imperiled. While the

project cannot stop the natural processes of sea level rise, subsidence, and

storm-caused erosion, the project can greatly slow down the disappearance of

these landforms by decreasing the rate of decline of wetland habitat in the

coastal system.

Connectivity: The Terrebonne Marshes has one of the largest expanses of

critical freshwater marsh habitat in Louisiana. The Terrebonne Marshes are

also a valuable stopover habitat for migratory birds. With the loss of these

marshes, this valuable stopover habitat for migratory birds is lost as well.

Limiting habitat: NMFS has designated all marsh habitats in the Study Area

as EFH for brown shrimp, white shrimp, Gulf stone crab, and red drum.

4.4.9.2 Design, Environmental, and Construction Considerations

Major project considerations:

Continued access of LA Highway 24 would be maintained during

construction.

Construction of all structural measures would be done in accordance with

industry standards.

Construction of the channel conveyance systems would be done in accordance

with industry standards.

Berm construction features would make use of beneficial spoil systems and

would be done in accordance with industry standards.

Any excess spoil from the channel conveyance systems would go into marsh

creation. These marsh creation features would be built to industry

standards.

Construction of features in the vicinity of the twin span bridge conducted as

to not compromise the integrity of the bridges.

4.4.9.3 Real Estate Requirements

The recommended plan / NER plan (Alternative 2) involves construction of 56

structures and other water management features and the opportunistic operation of

the Houma Navigation Lock complex. A total of approximately 2,939.4 acres is

required for this project. The total acreage required for water control structures is

approximately 8.8 acres. Approximately 53.7 acres are necessary for alteration of

canals through placement or removal of plugs and the placement of gaps.

Approximately 1,437.7 acres are necessary for the improvement of channels through

dredging, the use of culverts, and shoreline protection. Approximately 797.6 acres

are required to accommodate marsh restoration efforts. The construction of a weir

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would require approximately 1.4 acres. Approximately 15.3 acres are necessary for

the improvement of two levees. An additional 674.9 acres would be required for a

temporary work area. In addition to the estates acquired to accommodate project

features, approximately 222.3 acres of oyster leases are anticipated to be directly

impacted and, therefore, must be acquired.

4.4.9.4 Operations and Maintenance Considerations

All features for the recommended plan / NER plan were considered for operational

cost and maintenance cost. Items that require painting, periodic inspections, and

debris removal were considered as features that would have annual cost to them

and were priced accordingly. Features that consist of dredging or berm type work

are designated as having no maintenance cost.

Operation of the HNC Lock Complex and flood gate would involve closure of the

flood gate year round. Normal vessel traffic would pass through the lock. A few

times each year, large vessels that would not fit in the lock would need to pass

through the structure. These vessels would schedule openings of the sector gate

portion of the structure. After the vessel passes, the sector gates would again be

closed.

Sluice gates located within the HNC Lock Complex would be open year round with

the exception of storm event conditions. Requirement for modification of the

operational scheme of the sluice gates would be assessed through adaptive

management and monitoring.

All other structures included in the NER plan were assumed to be open for all

conditions during the alternatives analysis. These structures were designed with

adaptive management in mind and have various methods of being closed. Using the

structures to prevent salinity intrusion was another designed purpose. Operational

plans for these structures would be determined during PED.

4.4.9.5 Monitoring Plan and Adaptive Management

4.4.9.5.1 Description of Monitoring Activity and Adaptive Management

A feasibility level monitoring and adaptive management plan has been developed

for the project (Volume III, Appendix I). The monitoring and adaptive management

plan was developed to include a sufficient description of the proposed monitoring

and adaptive management activities to identify the nature of proposed adaptive

management activities and to estimate the costs and duration of the monitoring and

adaptive management plan. The monitoring and adaptive management plan

identifies the restoration goals and objectives identified for the project; outlines

management actions that can be undertaken to achieve the project goals and

objectives; presents a conceptual ecological model that relates management actions

to desired project outcomes; and lists sources of uncertainty that recommend the

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project for adaptive management. Monitoring, assessment, decision making, data

management are also addressed in the monitoring and adaptive management plan.

4.4.9.5.2 Performance Measures for Monitoring

The plan identifies performance measures along with desired outcomes and

monitoring designs in relation to specific project goals and objectives.

Objective 1: Prevent habitat conversion and reduce and/or reverse future wetland

loss

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 excluding storm events (1985 –

2012)

Monitoring Design: Habitats would be classified using Landsat TM scenes

collected in two preconstruction, 5 construction and 10 post-project

construction years and Digital Orthophoto Quadrangles for three

construction and two post-project construction years, as well as any available

field data in the Study Area to assess land:water trends and habitat

distribution.

Monitoring Design: For ground-truthing of Landsat imagery, permanent

vegetation monitoring stations would be established at 24 locations for

assessing Study Area vegetation communities, and sampled annually. These

stations would be monitored 2 years during PED, 5 years during

construction, and 10 years post-construction.

Objective 2: Achieve and maintain characteristics of sustainable marsh hydrology.

Performance Measure 2: Depth, duration and frequency of marsh flooding

Desired Outcome: Maintain marsh hydrology in range of conditions that

support sustainable fresh, intermediate and brackish marsh

Monitoring Design: Marsh hydrology would be assessed at 24 stations

within the Study Area and additional hydrologic stations located in marshes

adjacent to Bayou Copasaw, Minors Canal, Houma Navigational Canal, and

Grand Bayou. The need for additional stations would be determined during

preconstruction engineering and design.

Desired Outcome: Maintain hydrology that matches the predicted salinity,

temperature, discharge and flooding characteristics from modeling of selected

plan at particular points in time

Supporting Information Need: Salinity, temperature, discharge (velocity

and cross-channel profile), conductivity, turbidity, pH, and water surface

elevation

Monitoring Design: The water gauging network (12 stations) that was

established for model development would continue to be monitored during

two years during preconstruction, 5 years during construction and 10 years

post-project construction.

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Objective 3: Reduce salinity levels in Study Area

Performance Measure 3: Pore water and surface salinity

Desired Outcome: Maintain range of variability in salinities at desired

locations that would be identified from modeling output from recommended

plan to maintain baseline vegetation community types.

Monitoring Design: Marsh salinity would be assessed at 24 stations within

the Study Area and additional hydrologic stations located in marshes

adjacent to Bayou Copasaw, Minors Canal, Houma Navigation Canal, and

Grand Bayou, as needed. The need for additional stations would be

determined during preconstruction engineering and design.

Objective 4: Increase sediment and nutrient load to surrounding wetlands.

Performance Measure 4: Elevation and accretion

Desired Outcome: Maintain marsh elevation within tidal frame (relative sea

level rise = 0 cm/yr).

Monitoring Design: Marsh elevation and accretion would be assessed at 24

stations within the Study Area and at additional hydrologic and salinity

stations located in marshes adjacent to Bayou Copasaw, Minors Canal,

Houma Navigation Canal, and Grand Bayou, as needed. The need for

additional stations would be determined during preconstruction engineering

and design.

Supporting Information Need: Total suspended sediment and macro

nutrients

Desired Outcome: Increase sediment and nutrient load

Monitoring Design: Collection of total suspended sediment and nutrients

(total nitrogen, nitrate + nitrite, total phosphorus) would be used to evaluate

change compared to existing conditions using a subset of the water and

salinity gauging network (12 stations) in proximity to Bayou Copasaw,

Minors Canal, Houma Navigation Canal and Grand Bayou.

Objective 5: Sustain productive fish and wildlife habitat.

Performance Measure: Fish population data

Desired Outcome: Sustain current levels of productive fish and wildlife

habitat after project construction

Monitoring Design: Pre- and post-project data collected by LDWF would be

utilized to determine status and trends of fishery populations in the Study

Area. Assessments utilizing this data would be performed as long as data are

made available. Expansion of the current LDWF sampling regime is not

proposed at this time. If it is determined, in coordination with LDWF and

other resource agencies, that additional sampling is needed, it would be

considered during preconstruction engineering and design.

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4.4.9.5.3 Cost and Duration of Monitoring and Adaptive Management

The costs associated with implementing the monitoring and adaptive management

plan were estimated based on currently available data and information developed

during plan formulation as part of the feasibility study. The costs estimated would

be refined in PED during the development of the detailed monitoring and adaptive

management plans.

The current total estimate for implementing the monitoring and adaptive

management programs is $21,302,000 based on October 2010 price levels. In

accordance with WRDA 2007 Section 2039, the monitoring costs presented in the

report are for the full allowable 10 year period and represent conservative and

comprehensive costs. Section 2039 guidance does allow for the monitoring to end

prior to the 10-year period if the Secretary determines that the success criteria have

been met. The costs presented in the report are for the full 10 year period but

monitoring may end prior to the 10 years. The monitoring plans and costs were

developed by the interagency LCA Adaptive Management Planning Team in

conjunction with stakeholders and have been determined to be a reasonable plan

and estimate for the recommended plan and are what is needed and necessary to be

able to determine project success. Adaptive management costs include program

establishment and implementation over 10 years.

4.4.9.6 Effectiveness of Recommended Plan in Meeting Goals and Objectives

The recommended plan / NER plan is an effective alternative at meeting most of the

goals and objectives of the alternatives evaluated. The recommended plan restores

some of the functional deltaic processes that have been impaired resulting in a

degraded condition. The recommended plan fits within the current cost and scope of

the authorization.

4.4.9.7 Effectiveness of Recommended Plan in Meeting Environmental

Operating Principles

The USACE has reaffirmed its commitment to the environment by formalizing a set

of EOPs applicable to all its decision-making and programs. The formulation of all

alternatives considered for implementation meets all of the principles. However, as

a function of the entire LCA program, the only principle not met fully is EOP #1 –

Sustainability. Sustainability is a goal of any USACE project. This project, as a

part of the comprehensive coastal ecosystem restoration project for coastal

Louisiana, is just one part of many pieces that in their entirety, or cumulatively,

lead to a more sustainable end result. Therefore, as a stand-alone project, in the

context of coastal restoration, this project arguably falls short of EOP #1 because it

does not address the entire coast. However, when added to other near-term, longterm, and ongoing efforts, it provides its share of reaching sustainability.

Additional discussion regarding the effectiveness of the recommended plan in

meeting the USACE EOPs is provided in Volume III.

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4.4.9.8 Compensatory Mitigation Measures

The project would provide positive ecosystem benefits. Temporary negative impacts

to the marsh associated with excavation of canals and management structures

would be compensated for by creation of new marsh and by reduction in the rate of

marsh loss. Efforts to avoid and minimize negative impacts to marsh habitat would

be evaluated during PED. No mitigation measures would be needed.

4.4.10 Risk and Uncertainty

Tropical Storm and Hurricane Damages: As with any ecosystem restoration

project in the LCA, there would be risk to features under Alternative 2. The

associated risks with storm damage to features in Alternative 2 were similar to all

other alternatives considered in this study. Likewise, the targeted resources of this

restoration project are vulnerable to storm damage with no action as well with any

of the alternative plans. Implementation of Morganza to the Gulf of Mexico

Hurricane Protection Project would reduce risk of storm damage to some of the

resources and features of Alternative 2, but not eliminate these risks. Storm

damage risks to the LCA ARTM Project are not avoidable in the future but may be

manageable with adaptive management techniques.

Relative Sea Level Rise: Effectiveness of project features would be influenced by

the RSLR within the Study Area. RSLR values were calculated according to the

latest USACE guidance, EC 1165-2-211. This EC provides curves for three different

sea level rise scenarios. The first uses the eustatic sea level rise rate plus the local

subsidence rate, which is determined using observed gage data. This is referred to

as the low RSLR rate. The second and third curves utilize sea level rise projection

curves for intermediate and high sea level rise developed by the Intergovernmental

Panel on Climate Change (IPCC). These values are added to local subsidence rates

to determine the intermediate and high RSLR rates.

For this study all alternatives were analyzed using the low RSLR. Intermediate

RSLR rates were modeled for Alternative 3. This effort showed a reduced

effectiveness for this alternative of 66%. Due to the similarities of alternatives, the

relative reduction in effectiveness of all alternatives would be similar. While the

effectiveness would be reduced, the recommend plan / NER plan would still provide

benefits under the intermediate RSLR scenario. Values for sea level rise and

subsidence are shown in Table 4-11.

At the high RSLR rate, marsh collapse is predicted to begin in 2017, when RSLR

rate reaches 10 mm/yr. This rate represents a threshold believed to initiate rapid

marsh collapse as observed by Nyman et al. (2006). After 10 years, in 2027, the

collapse would be complete and the marsh would convert to open water. None of the

alternatives would prevent marsh collapse at the high RSLR rate.

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Risk to the project due to RSLR cannot be calculated because the three RSLR rates

are based on future scenarios that do not have probabilities assigned to them. Since

the benefits of this project are sensitive to RSLR, the importance of adaptive

management of the project is increased. All structures, with the exception of the

boat bay weir WW2, would be constructed with some method of flow control to allow

for adaptive management. Operating machinery for all structures within this

project would be constructed to an elevation that they are all operable under the

intermediate RSLR rate. This would provide added flexibility to retain benefits

longer under a range of RSLR.

Table 4-11: Sea Level Rise Results for Alternative 2

RSLR Rate RSLR (ft) Net Acres Net AAHU

Low 1.89 10,308 3,325

Intermediate 2.23 1,913 1,126

High 3.73 0 0

Real Estate: Although the LCA ARTM project features may cause slight increases

in water elevations at certain locations periodically, no substantial damage to

private property is anticipated to occur. The majority of the areas anticipated to

experience slight increases in water elevations are marshlands. All existing viable

uses of the marshlands are not expected to be detrimentally affected by the periodic

change in water elevation. All developed areas within the Study Area are protected

by levees and/or ridges. Therefore, the slight and periodic increase in water levels

is not anticipated to impact any developed areas. The LCA ARTM project features

are designed to modify existing artificial flow and drainage patterns in order to

better approximate the patterns that used to naturally occur. The LCA ARTM

project features are not predicted to significantly increase the magnitude or

frequency of inundation of areas that would receive increased freshwater flows.

Any increase in water levels within the Study Area is directly related in increased

water stages in the Atchafalaya River. Therefore, flowage easements are not

necessary within the Study Area.

The benefitted area of the LCA ARTM Project is approximately 1,000,000 acres, the

majority 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 LDNR, 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

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or other form of consent or authorization from the U.S. Army Corps of Engineers,

the Environmental Protection Agency, or the Louisiana Department of 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 USFWS, the NMFS, the USEPA, and the LDEQ.

Combination of Risks: Due to risks arising from storm damages, relative sea

level and anthropogenic modifications to hydrology, there is an underlying

unquantifiable uncertainty to the future viability of the Terrebonne marsh system.

There is a risk that the targeted ecological resources in this study may continue to

decline and possibly become almost non-existent in the Study Area. Alternative 2 is

the first step in the critical near-term to manage these risks in a systematic

approach and would certainly need to be adaptively managed over the project

lifespan.

Implementation of the Houma Navigation Lock Complex: The recommended

plan/ NER plan relies on the operation of the HNC Lock Complex for environmental

purposes after 2025, as do all the alternatives considered with the exception of the

no action plan. The HNC Lock Complex is a feature of the Morganza to the Gulf of

Mexico Hurricane Protection Project. The lock complex ties into adjacent earthen

levees to reduce the risk of hurricane storm surge traveling up the HNC; the 100-

year elevation of the structure is currently estimated to be between 24 and 26 ft

elevation (NAVD 88). The lock complex includes a 110-foot-by-800-foot lock, an

adjacent 250-foot wide sector gate and a dam closure. For added flexibility, there

are 10 sluice gates in the t-wall sections of the lock complex that can be used for

drainage/circulation when the sector gate is closed. Each gate is 5 feet tall by 10

feet wide, with the top of the gate opening at elevation -2.0 ft. For the purposes of

this study, it was assumed that the sluice gates would be open any time the sector

gates were closed, with the exception of storm conditions.

This LCA Report proposes the development of an operational plan for the lock

complex structure authorized under Morganza to the Gulf in order to maximize

potential environmental benefits, both in terms of avoiding saltwater intrusion and

optimizing flow distribution. The proposed action with a constructed lock complex

(which comprises the future without project condition for the LCA Report after

2025) is to operate it in such a way that freshwater from the GIWW “escaping”

down the HNC could be redirected into the surrounding wetlands.

The modified operation of the lock complex, however, may prove to be a challenge

because of the effort involved in opening and closing the floodgates. The lock itself

would be operated only when the floodgates are closed to reduce salinity within the

channel. Once closed, the floodgates would force water down other waterways (such

as Bayou Grand Caillou). Saltwater intrusion would be halted at the gate, and

freshwater flows would increase in other waterways. If the HNC Lock Complex is

not constructed by 2025, the benefits of its operation would be lost and other

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benefits from LCA ARTM from 2025 onward could be altered. Additionally, since

the operations plan for the HNC Lock Complex has not been finalized, the future

without project condition could be modified. This could also alter the benefits after

the lock is constructed.

In order to determine the potential impacts of varying completion schedules and

operational plans for the HNC Lock Complex on the benefits accrued with each LCA

ARTM alternative, separate hydraulic model results and WVA model results would

have to be generated for each new scenario. Given the scale of this undertaking and

the compressed schedule associated with the LCA ARTM Project, additional model

runs to clarify these impacts were not feasible. In lieu of additional model runs, one

method of estimating the impacts on project benefits of the Morganza to the Gulf

Project not being implemented would be to subtract the AAHUs associated with the

modified operation of the lock complex from all of the alternatives that include it as

a measure. Alternative 7 consisted of only one measure, the modified operation of

the lock complex, and resulted in the generation of 243 AAHUs. Therefore, the

assumption could be made that the other action alternatives, all of which included

modified lock operation as a measure, would have their benefits reduced by 243

AAHUs were the lock complex not constructed at all during the 50-year period of

analysis. This is not necessarily an accurate assumption since project features do

not perform completely independently from other project features but rather

interact synergistically or antagonistically in hydraulically complex ways.

Therefore, the modified operation of the lock complex may contribute more or less

than 243 AAHUs to the other action alternatives. However, this methodology

should provide a general idea of the scale of the impact that the removal of the

feature would have on the benefits accrued. Following this logic, Table 4-12 can

serve as a guide to the degree of sensitivity that the project would have to changing

Morganza to the Gulf completion schedules. CE/ICA performed using these

estimated AAHUs revealed that Alternative 2 would still be selected as the NER

plan and recommended plan.

In addition to potential impacts that Morganza to the Gulf could have on the LCA

ARTM Study, features of the LCA ARTM Study may impact Morganza to the Gulf

features. The proposed change in operation of the HNC Lock Complex, in addition

to other features associated with LCA ARTM, could have design implications for

features associated with the Morganza to the Gulf Project. Increased volumes of

water directed into areas that drain through proposed Morganza to the Gulf water

control structures may require adjustments to the designed structure sizes in order

to accommodate more flow. This would require continued coordination between the

two studies to ensure compatibility. In addition, modified operation of the HNC

Lock Complex may result in increased O&M costs for the flood gate and lock. The

degree to which O&M costs would increase remains undetermined at this time. The

increase in O&M costs would be the responsibility of CPRA, the non-Federal

sponsor.

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Table 4-12 : Estimates of Project Habitat Benefits without the HNC Lock

Implementation

Alternative Benefits with Lock

Complex Implementation

in 2025 (AAHUs)

Benefits without Lock

Complex Implementation

(AAHUs)

2 3,220 2,977

3 3,325 3,082

4 4,258 4,015

5 4,719 4,476

6 776 533

7 243 0

8 1,214 971

Project Benefits: Some uncertainty exists with the ability to ensure that the

projected project benefits are attained and maintained in the absence of further

restrictions on land use within the project benefits areas. Further risk assessment

and analysis would be conducted together with identification of approaches that

may be appropriate to manage identified risks. Approaches to be examined may

include the effectiveness of existing regulatory controls and the need for acquisition

of additional real estate interests (with or without surface restrictions).

Uncertainty also exists with respect to ecosystem function and how the ecosystem

components of interest would respond to the restoration project. For example, there

is uncertainty in whether or not increasing the flow of fresh water and nutrients to

area marshes with little associated sediment would result in the predicted level of

benefits. It is believed that increased freshwater would benefit Study Area

marshes, but similar projects that could be used as verification do not currently

exist. In addition, there are associated uncertainties about the best design and

operation for project features. Robust monitoring and adaptive management would

help to ensure project success and identify outcomes that should realistically be

expected for the project.

There is also uncertainty as to the magnitude of benefits that would be accrued

from beneficial use of dredged material. For purposes of impact analysis associated

with dredge features for all alternatives, the assumption was made that the dredge

channel itself and the adjacent disposal site would result in marsh impacts. In

reality, dredged material would be used beneficially to create marsh habitat to the

maximum extent practicable. However, the exact nature of the dredged material

and its utility in marsh creation, the locations of marsh creation sites, and the

acreage of created marsh habitat would not be determined until a later date, during

preconstruction engineering and design. Therefore, the aforementioned

assumptions were necessary in order to complete the impact analysis for project

features. In light of this, the estimates of negative impacts to marsh should be

viewed as maximums as they should be offset at least in part by beneficially using

dredged material during construction. Further environmental analysis and

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documentation, including updates to the Section 404(b)(1) evaluation (see Volume

III, Appendix D), would be prepared during preconstruction engineering and design

to address changes in disposal locations and associated benefits.

Finally, there is uncertainty with regard to fisheries access impacts on project

benefits associated with the Grand Pass weir (WW2), the Robinson Canal plug

(CP1), the Cutoff Canal plug (EP7), and the operation of the HNC Lock Complex

(CL1). Inclusion of fisheries access impacts in the calculation of AAHUs may have

resulted in negative AAHUs for all alternatives, despite net gains in wetland

acreages. These measures are designed to correct significant hydrologic alterations

on man-made canals which are thought to be significant causes of wetland

degradation and loss and which resulted in artificially increased fisheries access. In

addition, other natural and man-made waterways exist for fisheries access.

Therefore, the decision was made to eliminate this potential impact when

calculating benefits associated with each alternative. Potential modifications to

this methodology are being investigated by USFWS in consultation with NMFS,

LDWF, and other interested natural resource agencies.

Future Analysis: In addressing the recommendations of the USFWS for further

analysis and coordination during preconstruction engineering and design (see

Volume III), the following would be undertaken:

Additional hydrologic modeling, benefits analysis, and cost effectiveness

analysis of various sized and designed enlargements of Grand Bayou

Canal/Bayou L'Eau Bleu (measures ED3, ED5, ED6, and ED7) to avoid

unnecessary construction impacts and unnecessary canal-induced saltwater

intrusion impacts, to include efforts to assess project-related effects of

reduced freshwater inflows to the Barataria Basin

Additional hydrologic modeling, benefits analysis, and cost effectiveness

analysis of various sized and designed enlargements of St. Louis Canal

(measure ED2) to avoid unnecessary construction impacts and unnecessary

canal-induced saltwater intrusion impacts

Additional hydrologic modeling, benefits analysis, and cost effectiveness

analysis related to the multipurpose operation of the HNC Lock Complex to

include assessment of the adequacy of the existing model grid, reexamination of model results for unaccounted-for HNC flows, inclusion of the

Falgout Canal structures, review of the predicted Lake Boudreaux salinity

trends, and assessment of alternative sluice gate operations on the HNC Lock

Inspection of proposed work sites for the presence of wading bird nesting

colonies and bald eagles during the nesting season

Sampling and testing of material to be dredged and determination of

locations for beneficial use of dredged material

Development of operation plans for water control structures

Coordination with Louisiana Department of Wildlife and Fisheries

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In addition to the above analyses recommended by USFWS, additional hydrologic

modeling would be conducted on dredge feature WD2 in order to address concerns

from the public regarding saltwater intrusion and bank stability.

These efforts would be coordinated with the USFWS and other interested natural

resource agencies. The results of these additional analyses would be disclosed to

the public and supplemental NEPA documentation would be prepared, as

appropriate.

4.4.11 Implementation Requirements / Adaptive Management

4.4.11.1 Schedule

This project was authorized for construction by the WRDA 2007, contingent upon a

signed and favorable Chief of Engineers Report by December 31, 2010. After the

Chief’s Report is signed, this project would be eligible for construction funding. The

project would be considered for inclusion in the President’s budget based: on

national priorities, magnitude of the Federal commitment, economic and

environmental feasibility, amount of local public support, willingness of the nonFederal sponsor to fund its share of the project cost, and the budget constraints that

may exist at the time of funding. Once Congress appropriates Federal construction

funds, the Corps and the non-Federal sponsor would enter into a PPA. This PPA

would define the Federal and non-Federal responsibilities for implementing,

operating, and maintaining the project.

The USACE would officially request the sponsor to acquire the necessary real estate

immediately after signing the PPA. The advertisement of the construction contract

would follow the certification of the real estate. The final acceptance and transfer of

the project to the non-Federal sponsor would follow the delivery of an O&M manual

and as-built drawings.

At this time, the implementation schedule for the recommended plan / NER plan is

based on Micro-Computer Aided Cost Engineering System, Version 2 (MII) cost

estimation durations. This implementation schedule is tentative and may change to

be accelerated, especially if a larger dredge is used than is currently accounted for

in the cost estimation (Table 4-13).

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Table 4-13: Milestone Schedule

Milestone Schedule

Final report August 2010

Division engineer notice August 2010

Washington level review August 2010

Execute cost-sharing agreement for PED September 2010

State and agency review October 2010

Chief of Engineers Report December 2010

Begin preconstruction engineering and design 2011

ASA and OMB review 2011

ASA report to Congress 2011

Complete design documentation report 2012

Complete plans and specifications 2012

Execute PPA 2012

Complete real estate acquisition 2012

Advertise construction 2012

Construction start 2013

Complete construction 2018

Turnover project to local sponsor 2018

Initiate monitoring and adaptive management During PED

Complete monitoring and adaptive management 2028

Note: ASA = Assistant Secretary of the Army; OMB = Office of Management and Budget

4.4.11.2 Implementation Responsibilities

The Federal government would provide 65% of the first cost of implementing the

recommend plan, including PED, construction, and construction management,

which is estimated to total $285,030,000 based on October 2010 price levels. In

addition to its financial responsibility, the Federal government would:

1. Design and prepare plans and specifications for construction of the

Recommended Plan; and

2. Administer and manage contracts for construction and supervision of the

project after authorization, funding, and execution of a Project Cooperation

Agreement with the CPRA.

4.4.11.3 Cost Sharing

The State of Louisiana, acting through the CPRA, would be the non-Federal sponsor

for the LCA ARTM Project. Following the feasibility phase, the cost share for the

planning, design and construction of the project would be 65% Federal and 35%

non-Federal. The CPRA must provide all LERRDs required for the project.

OMRR&R of the project would be a 100% CPRA responsibility. The cost

apportionment of recommended incremented of construction are presented in Table

4-14.

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Table 4-14: Cost Sharing Split

Project Feature Total Cost

ARTM

Total Cost

MOHNL

Non-Federal Federal

% Cost % Cost

Total first cost of

construction $283,534,000 a $1,496,000 35 $99,760,000 65 $185,270,000

LERRD credit $8,168,000 $0 100 $8,168,000 0 $0

Monitoring and

adaptive

management

$18,776,000 $2,428,000 35 $7,456,000 65 $13,846,000

OMRR&R b $0 $73,000 100 $73,000 0 $0

a Total first cost of construction is based on the sum of the planning, engineering, and design; construction

management (i.e. supervisions and administration); LERRDs; and monitoring and adaptive management and

is based on October 2010 price levels.

b Average annual cost based on October 2010 price levels.

The State of Louisiana is in full support of the LCA ARTM Project at the current

cost share ratio of 65% Federal, 35% non-Federal, with operations, maintenance,

repair, replacement and rehabilitation being a 100% non-Federal responsibility, as

required in WRDA 2007. OMRR&R costs associated with the modified operation of

the HNC Lock Complex have not yet been determined, but would also be the

responsibility of the State of Louisiana. Additionally, project monitoring and any

adaptive management deemed necessary would be cost shared at 65/35 for the first

10 years of the period of analysis.

4.4.11.4 Environmental Commitments

BMPs would be included in construction specifications and they would be employed

during construction activities to minimize environmental effects. Many of these

BMPs 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.

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.

Conduct a search for bald eagle, other raptors, and colonial nesting wading

bird active nests within three-quarter of a mile from proposed disturbance

activities prior to construction. Appropriate protective measures and no-work

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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 BMPs 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.

Implement the Monitoring and Adaptive Management Plan.

Implement the recommendations of the USFWS for further modeling and

analysis of alternatives as detailed in Section 7.2.1 and Appendix B of this

report.

4.5 Public Involvement *

4.5.1 NEPA Scoping

An NOI to prepare an SEIS for the LCA ARTM Project was published in the

Federal Register in December 2008. A scoping meeting was conducted in February

2009 for the project.

Common themes of the comments follow:

Need for a greater influx of freshwater and sediment to Terrebonne Parish

Use of pipelines to distribute water and sediment

Management of water flowing through the GIWW

Need for freshwater flow into the Terrebonne marshes

Impact to marshes from water increase and velocity

The Draft FS/SEIS was released to the public in May 2010, followed by a 45-day

public review period, which included a public meeting. Public comments were

received during the scoping meeting and Draft FS/SEIS public review. Public

comments have been incorporated into the report throughout the report

development. Comments received and the responses to them are included in

Appendix G of Volume III.

4.5.2 Other Public Comments, Areas of Controversy, Unresolved Issues

The recommended plan relies on the operation of the HNC Lock Complex for

environmental purposes after 2025. The HNC Lock Complex is a feature of the

Morganza to Gulf of Mexico Hurricane Protection Project. The LCA ARTM Project

proposes the development of an operational plan for the lock complex structure

authorized under Morganza to the Gulf, in order to maximize potential

environmental benefits, both in terms of avoiding saltwater intrusion and

optimizing flow distribution. The proposed action with a constructed lock complex

(which comprises the future without project condition for the LCA project after

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2025) is to operate it in such a way that freshwater from the GIWW “escaping”

down the HNC could be redirected to surrounding wetlands. Coordinated adaptive

management between LCA ARTM and the Morganza to Gulf Project would be

necessary and is recommended.

However, the modified operation of the HNC Lock Complex may prove to be a

challenge because of the effort involved in opening and closing the floodgates. The

lock itself would be operated only when the floodgates are closed to reduce salinity

within the channel. Once closed, the floodgates would force water down other

waterways (such as Bayou Grand Caillou). Saltwater intrusion is halted at the

gate, and freshwater flows increase in other waterways. If the HNC Lock Complex

is not constructed in 2025, the benefits of its operation would be lost and other

benefits from LCA ARTM from 2025 onward would be altered. The benefits

potentially lost are estimated at 243 AAHUs.

Relative sea level rise rates higher than the historical rate have the potential to

greatly reduce or even eliminate the benefits of this project. Intermediate RSLR

would reduce benefits by 66% and high RSLR would eliminate benefits. While the

intent of EC1165-2-211 on sea level rise was met (USACE, 2009b), at this time it is

impossible to determine the risk of higher relative sea level rise rates. While this

risk exists, the structures in the selected plan were designed with adaptive

management and RSLR in mind. Various operational schemes may help to extend

the benefits under higher RSLR scenarios.

The degree to which Study Area marshes would respond to increased freshwater

inputs associated with project features remains unresolved. Specifically, there is

uncertainty in whether or not increasing the flow of fresh water and nutrients to

area marshes with little associated sediment would result in the predicted level of

prevention of marsh loss. It is believed that increased freshwater would benefit

Study Area marshes, but similar projects that do not utilize sediment inputs that

could be used as verification do not currently exist. Robust monitoring and adaptive

management would help to ensure project success and identify outcomes that

should realistically be expected for the project.

Fisheries access impacts on project benefits remain unresolved for some project

features. Inclusion of fisheries access impacts in the calculation of AAHUs may

have resulted in negative AAHUs for all alternatives, despite net gains in wetland

acreages. Project measures are designed to correct significant hydrologic

alterations on man-made canals which are thought to be significant causes of

wetland degradation and loss and which resulted in artificially increased fisheries

access. In addition, other natural and man-made waterways exist for fisheries

access. Therefore, the decision was made to eliminate this potential impact when

calculating benefits associated with each alternative. Potential modifications to

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this methodology are being investigated by USFWS in consultation with NMFS,

LDWF, and other interested natural resource agencies.

There are also unresolved issues with respect to the best design and operation of

some project features. Further modeling needs to be conducted during

preconstruction engineering and design in order to determine ideal sizes and

operational scenarios of some dredge features and water control structures that

could not be fully analyzed during the planning phase due to time constraints.

Specific details on dredged material disposal acreages and locations also need to be

determined. Dredged material would be utilized for marsh creation to the

maximum extent practicable. Section 7.2.1 above contains details on proposed

analyses.

4.6 Coordination and Compliance *

4.6.1 USACE Principles and Guidelines

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.

4.6.2 Environmental Coordination and Compliance

Coordination and compliance efforts were conducted regarding statutory

authorities. These include environmental laws, regulations, Executive Orders,

policies, rules, and guidance applicable to this project. Full compliance with

statutory authorities would be accomplished upon review of the integrated FS/SEIS

by appropriate agencies and the public and the signing of a ROD.

The USACE has coordinated with the USFWS, NMFS, and the LDWF per the Fish

and Wildlife Coordination Act (48 Stat. 401, as amended; 16 U.S.C. 661 et seq.). A

CAR has been received and the comments incorporated into the project plan as

appropriate. Accordingly, the USFWS supports implementation of the

recommended plan, provided that additional assessment work is continued during

the remaining planning phase and completed during the PED phase, to address

outstanding major issues that could result in substantial improvements and/or

modifications to the selected plan. The USACE concurred with the

recommendations; discussion of the recommendation is provided in Volume III.

State certification for coastal zone consistency has also been received.

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5.0 SMALL DIVERSION AT CONVENT/BLIND RIVER

5.1 Purpose and Scope*

This is a summary of the FS/SEIS for the LCA Small Diversion at Convent/Blind

River Project (Volume IV).

The Blind River headwaters are located in St. James Parish 3 miles north of the

east bank of the Mississippi River at Convent. The Blind River flows north then

east through Ascension and St. John the Baptist parishes emptying into Lake

Maurepas. This study identifies and evaluates management measures and

alternatives to divert Mississippi River waters into Blind River and the Maurepas

Swamp. The purpose of this project is to introduce sediment and nutrients into the

swamp to reverse swamp decline and to prevent the transition of the freshwater

swamp into freshwater marsh and subsequently open water. Reversing this decline

will aid development of a more sustainable wetland ecosystem that will serve to

protect the local environment, economy and culture. This project may also provide

flood damage risk reduction. Alternative diversion locations near Convent,

Louisiana, located at Mississippi River mile 159, were investigated. The objective of

the project is to introduce freshwater, sediment, and nutrients into the southeast

portion of the Maurepas Swamp to improve biological productivity and facilitate

accretion, and prevent further swamp deterioration.

This project would complement but is independent of two other proposed LCA

projects (LCA Small Diversion at Hope Canal and LCA ARDC Canal Modification).

The environmental consequences of the proposed project are evaluated in Volume

IV, Section 5 and summarized here. The integrated NEPA documentation and

SEIS is a supplement to the FPEIS for the LCA Report (USACE, 2004b). The ROD

for the FPEIS was signed on November 18, 2005. The FPEIS is incorporated by

reference.

5.1.1 Study Area Background*

The Study Area includes portions of the Mississippi River Deltaic Plain within

coastal southeast Louisiana in the Lake Pontchartrain Basin (Figure 5-1). The

Study Area is within the Upper Lake Pontchartrain sub-basin. The LCA Small

Diversion at Convent/Blind River is located in LCA Subprovince 1.

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Louisiana parishes in the Study Area include St. James and portions of Ascension.

The benefit area consists of the southeast portions of Maurepas Swamp and Blind

River southwest of Interstate 10 (I-10). Figure 5-2 shows the boundary for the

Study Area and the hydrologic boundaries within the Study Area. These

boundaries define hydrologically distinct areas individually addressed in the plan

formulation process.

5.1.1.1 Study Area Significance

The Maurepas Swamp is one of the largest remaining tracts of coastal freshwater

swamps in Louisiana. It provides a buffer between the open water areas of Lakes

Maurepas and Pontchartrain and developed areas along the I-10 / Airline Highway

corridor. Development along the I-10 / Airline Highway corridor in this area

includes residential, commercial, and industrial land use. Being the largest

contiguous tract of bald cypress-tupelo swamp near the New Orleans metropolitan

area, this area has considerable cultural significance and is used for fishing,

hunting, and other recreational activities.

5.1.2 History of Investigation

General ecosystem restoration problems and opportunities in the Study Area have

been documented since 1998 through numerous comprehensive planning studies.

Specifically, this study builds upon the following comprehensive planning efforts for

the Louisiana coastal areas:

Coast 2050 Plan (1999)

LCA Report (USACE, 2004a)

Integrated Ecosystem Restoration and Hurricane Protection: Louisiana’s

Comprehensive Master Plan for a Sustainable Coast (2007)

LACPR Final Technical Report (USACE, 2009c)

5.1.3 Prior Reports and Existing Projects

A number of prior water resources development efforts are relevant to the LCA

Report. These efforts are listed in Table 5-1 and further described in Volume IV.

Planning for this project utilizes data from these previous reports and studies.

Specifically, alternative plans for this study were formulated based upon the 2004

LCA Report and the project description contained within that report which is

further described in this section. Several existing and authorized navigation, river

flood control, and coastal restoration projects are specifically related to the study.

These projects are also briefly described below.

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Table 5-1: Relevance of Prior Studies, Reports, Programs, and Water

Projects to the LCA Small Diversion at Convent/Blind River, Louisiana

Feasibility Study

Prior Studies, Reports, Programs, and Water

Projects

Relevance to Convent/Blind River

Diversion

Data Source

Consistency

Structural Measures

Non-Structural

Measures

Comprehensive Planning Studies

Future Without

Project Condition

Coast 2050 Report, 1999 X X X X

Louisiana’s Comprehensive Master Plan for a

Sustainable Coast, 2007 XXX X X

LACPR, 2009 X X X X X

LCA Report 2004 X X X X X

Mississippi River Sediment, Nutrient, and Freshwater

Redistribution Study, 2000 XXX X X

Prior Studies, Reports, and Water Projects

LCA Small Diversion at Hope Canal X X

2001 Diversion into Maurepas Swamp X X X X X

2003 Potential Nitrate Removal from a Diversion into

Wetlands XX X

2003 Ecosystem Health of the Maurepas Swamp X X X X

2006 Impacts of Freshwater Diversion on Wildlife and

Fisheries XX X X

2007 Mississippi River Reintroduction into Maurepas

Swamp XXX X X

2007 Evaluation of Potential Impact of Diversion on

Gulf and Pallid Sturgeon XX X

2007 Cultural Resources Survey of River

Reintroduction Corridor XX X

2002 Amite Gapping X X X

2010 Amite Feasibility Study X X X X X

1996 Diversion and Feasibility of Bonnet Carré

Spillway XXX X X

2001 Water Quality Analysis X X X X

2008 Swamp Ecology in a Dynamic Coastal Landscape X X X

2006 Pontchartrain Basin Research Program X X X X

2007 Pontchartrain Basin Research Program X X X X

2002 Hydrologic Modeling to Evaluate MR Diversion

into Maurepas Swamps XX X X

(n.d) Growth and Development of Bald Cypress-Tupelo X X X

1992Effects of Flooding on Bald Cypress X X X

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1972 Effects of Aeration, Water Supply, and Nitrogen

on Tupelo and Bald Cypress XX X

2004 Through Droughts and Hurricanes: Survival and

Productivity of a Coastal Swamp XX X

1995 Interaction of Flooding and Salinity Stress on

Bald Cypress XX X

2005 Comprehensive Habitat Management Plan X X X X

2008 Interim Feasibility Report: Convent/Blind River

Freshwater Diversion XXX X X

Related Laws and Programs

CWPPRA 1990 X X X X

Act 8 of the First Extraordinary Session of 2005 X X X

Louisiana Coastal Zone Management Program, 1980 X X X

CIAP X X X X X

LCA Report, 2004:

This restoration feature involves a small diversion from the Mississippi River

into Blind River through a new control structure. The objective of this

feature is to introduce sediment and nutrients into the southeast portion of

Maurepas Swamp. This feature is intended to operate in conjunction with

the Hope Canal diversion to facilitate organic deposition in the swamp,

improve biological productivity, and prevent further swamp deterioration.

(USACE, 2004a)

In 2000, the USACE and State of Louisiana initiated the LCA

Report to address Louisiana’s severe coastal land loss problem. The LCA Report

used the best available science to develop a plan addressing the most critical coastal

ecological needs. The LCA Small Diversion at Convent/Blind River Project is one of

the elements included in the LCA Report and was described as follows:

Other projects included in the LCA Report that are near the LCA Small Diversion

at Convent/Blind River include the following (USACE, 2004a) :

LCA Small Diversion at Hope Canal: The LCA Small Diversion at Hope

Canal project is located northeast of the Convent/Blind River project. This

project is included in the Louisiana Coastal Area, Louisiana Report of the

Chief of Engineers, dated January 31, 2005, in a list of five priority projects

for implementation approval. The project is being investigated under the

CWPPRA program described above.

The LCA Small Diversion at Hope Canal consists of diverting approximately

0-5,000 cfs from the Mississippi River into the Hope Canal. The objective is

to introduce sediment and nutrients into Maurepas Swamp south of Lake

Maurepas. The introduction of additional freshwater via the diversion would

facilitate organic deposition, improve biological productivity, and prevent

further deterioration of the swamp. The LCA Small Diversion at Hope Canal

has a significant number of project-specific biological, environmental, and

hydrology/hydraulic studies. The hydrodynamic analysis includes an

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Advanced Circulation model with overlap onto the potential LCA Small

Diversion at Convent/Blind River Study Area.

This project will benefit a different portion of the Maurepas Swamp than the

LCA Small Diversion at Convent/Blind River. Both of the projects are

independent but their effects will be additive in restoring the swamp (Figure

5-3).

LCA ARDC Modification Project: This project is located northeast of the

LCA Small Diversion at Convent/Blind River Study Area. This restoration

feature involves the construction of gaps in the existing dredged material

banks of the LCA ARDC Modification Project. The objective of this feature is

to allow floodwaters to introduce additional nutrients and sediment into

western Maurepas Swamp. The exchange of flow would occur during flood

events on the river and from the runoff of localized rainfall events. This

feature would provide nutrients and sediment to facilitate organic deposition

in the swamp, improve biological productivity, and prevent further swamp

deterioration.

The LCA ARDC Modification Project will restore a different portion of the

Maurepas Swamp than the LCA Small Diversion at Convent/Blind River

project (Figure 5-3). The Study Areas for both projects are hydrologically

independent; therefore, any proposed actions would not result in ecosystem

benefits or impacts between the two projects. The LCA ARDC will add to the

restoration benefits of the LCA Small Diversion at Convent/Blind River and

LCA Small Diversion at Hope Canal projects. All projects will aid in

restoring the second largest stand of continuous swamp in Louisiana.

Navigation Projects

Mississippi River, Baton Rouge to the Gulf of Mexico: The Mississippi River,

Baton Rouge to the Gulf of Mexico project currently provides a 45-foot deep draft

channel between Baton Rouge and the Gulf of Mexico. This project includes points

on the river near Convent, Louisiana, investigated for the Blind River Diversion.

MR&T: The MR&T Project is a comprehensive project for flood control on the

Lower Mississippi River below Cape Girardeau, Missouri. The project was

authorized by the Flood Control Act of 1928 in response to the 1927 Lower

Mississippi River flood. The 1927 flood resulted in levee failures and extensive

flooding of populated areas. The four major elements of the MR&T Project are 1)

levees for containing flood flows; 2) floodways for the passage of excess flows past

critical reaches of the Mississippi River; 3) channel improvement and stabilization

to provide an efficient navigation alignment, increase the flood carrying capacity of

the river, and protect the levee system; and 4) tributary basin improvements for

major drainage and for flood control, such as dams and reservoirs, pumping plants

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and auxiliary channels. The MR&T system controls and confines the river system

before it reaches the coastal area.

Figure 5-3: Related LCA projects near the Study Area

Mississippi River Hydrodynamic Study (and other studies): The LCA Report

recommended authorization of a hydrodynamic study of the Mississippi River and

Atchafalaya River covering the reaches of both rivers from the Old River Control

Structure to their mouths. This comprehensive modeling and study effort will

provide estimates of water and sediment resources in the Mississippi River for

future restoration projects and for maintenance of navigation and water supplies.

The USACE and the CPRA have combined the Mississippi River Hydrodynamic

Study with the Mississippi River Delta Management Plan. These studies are

currently in the strategic development and data collection stages and output data

and results are not yet available.

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5.2 Need for and Objectives of Action *

5.2.1 Public Concerns

As a general matter, the public was very supportive on a project to reintroduce

Mississippi River water back into the Maurepas Swamp. As part of our NEPA

scoping and public involvement process, several participants stressed the urgency of

project implementation and deep concern over the deteriorated state of the swamp

and the uncertainty of funding for the project. Some participants raised concerns

regarding the proposed action’s impact on area wildlife and potential impacts on

drainage.

5.2.2 Problems, Needs, and Opportunities*

Study Area Problems & Needs

The MR&T flood control system has isolated the Maurepas Swamp (and Blind

River) from natural, periodic Mississippi River flooding. This has resulted in a

degradation/deterioration process and reduced biological productivity in the swamp

due to lack of freshwater, nutrient, and sediment inputs. The swamp is also

subsiding due to natural causes and possibly due to man-made activities such as oil,

gas, and groundwater withdrawals. The reduced biological productivity combined

with the lack of sediment from the river has reduced soil formation (accretion) to a

rate less than the subsidence. Consequently, the land surface is sinking. Storm

surge and saltwater intrusion have compounded these problems.

Additional ecosystem problems are associated with past construction of logging

trails, drainage channels, pipelines, other utilities, and roads through the swamp.

These features disrupt the water drainage patterns and impact the biological

productivity of the swamp. Short circuiting of the natural drainage patterns has

created ponding (impoundment) in some areas inhibiting bald cypress and tupelo

propagation.

Distributing freshwater through the watershed would help restore natural

hydrologic conditions and allow for increased vegetative growth and nutrient

uptake. Without freshwater reintroduction into the Blind River watershed,

observed conditions of deterioration are expected to continue into the future.

Specifically, the lack of freshwater input into the Blind River results in oxygen

depletion because of low water flow and inadequate mixing. Algae and other

biological growth and decay in the swamp result from agricultural runoff.

Freshwater inputs will increase flow and reduce the excessive biological growth

causing oxygen depletion in Blind River. Reintroduction of Mississippi River water

will also provide nutrients to increase bald cypress and tupelo tree productivity in

the watershed. Without additional nutrients, vegetative growth will continue to be

restricted, reducing soil building processes. Lack of seasonal flushing by the river

can also impact the swamp following storm surge events, which force higher salinity

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water into the swamp. Without seasonal flushing to force higher salinity water out

of the system, vegetation becomes stressed.

Due to subsidence, the lack of substrate accretion, and reduced organic productivity,

the Study Area is at high risk for swamp die-off similar to what is occurring in lakerim areas in western Lake Pontchartrain. The combination of little to no tree regeneration and more frequent incidence of higher than tolerable salinity results in a

higher risk of conversion of swamp to open water. Increasing water depth and yearround wet conditions will convert swamp habitat to marsh and eventually to open

water.

Specific problems identified in the Study Area are:

Tree mortality and decline in the overall health of the swamp

Exposure to increased salinities

Potential impacts to populations of indigenous fish and wildlife species

Hurricane-related damages to the swamp and conversion to open water areas

Study Area Opportunities

Opportunities identified in the 2004 LCA Report and those specific to the LCA

Small Diversion at Convent/Blind River Study Area include the following:

Prevent future cypress swamp degradation and transition currently predicted

to occur.

Restore the deltaic process impaired by levee and dredged material berm

construction.

Enhance Blind River water by increasing freshwater flow.

Protect vital socioeconomic and public resources, such as the growing ecotourism industry resident in the Maurepas Swamp and the Maurepas WMA.

Enhance recreational opportunities in the Maurepas Swamp and Blind River.

5.2.3 Planning Objectives

The project goal is to reverse the trend of degradation in the southeastern portion of

the Maurepas Swamp. This would help to sustain a coastal ecosystem that can

support and protect the environment, economy, and culture of southern Louisiana

and thus contribute to the well being of the nation.

The overall objective of the project is to reverse the trend of deterioration of

southeast Maurepas Swamp and Blind River.

Promote water distribution in the swamp.

Specific Project Objectives

Facilitate swamp building, at a rate greater than swamp loss due to

subsidence and sea level rise.

Establish hydro period fluctuation in the swamp to improve bald cypress and

tupelo productivity and their seeding germination and survival.

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Improve fish and wildlife habitat in the Blind River and swamp.

Specific targets, performance measures, and desired outcomes to determine project

success in meeting the above project objectives have been developed and are

presented in Section 5.4.8.5 of this summary document and the Adaptive

Management and Monitoring appendix of the FS/SEIS (Appendix I, Volume IV).

5.2.4 Planning Constraints

Development and evaluation of restoration alternatives for the proposed project are

constrained by a number of factors. Specific planning constraints identified for

project include the following:

Institutional Constraints

Minimize impact for the ability of the MR&T flood control project to continue

to fulfill its authorized purposes.

Minimize impact for the ability of authorized navigation projects to continue

to fulfill their purpose.

Do not violate limitations imposed by the designation of the Blind River as a

state scenic river by the LDWF.

The project will have to be constructed and operated so it would not conflict

with the Maurepas Swamp WMA.

Technical Constraints

Availability of freshwater, nutrients, and sediments from the Mississippi

River is limited. Annual high water (spring) and low water (summer) river

cycles will affect the hydraulic design of the diversion structure, transmission

channel, and swamp distribution system.

Diversion operation will be constrained by Lake Maurepas tail water

conditions. The Lake Maurepas tailwater is higher than the water level in

Maurepas Swamp.

Environmental Constraints

Do not violate Louisiana water quality standards.

5.3 Existing and Future Without Project Condition *

This section describes the existing and future without project conditions related to

plan formulation. Existing conditions information was obtained from the FS/SEIS

Affected Environment section (in Volume IV) and information regarding the future

without project condition was obtained from the Environmental Consequences

section of the FS/SEIS.

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5.3.1 Existing Condition

5.3.1.1 Location

The Study Area is within the Mississippi Alluvial Plain (Level III) Inland Swamp

(73n) and Southern Holocene Meander Belts (73k) (Level IV) ecoregions (Daigle et

al., 2006). For more information, see the FS/SEIS (Volume IV).

5.3.1.2 Climate

The climate of the Study Area is subtropical marine with long humid summers and

short moderate winters. Long-term, daily precipitation data (1930-present) shows

an average annual rainfall of 60.49 inches (153.65 cm) with a low of 40.48 inches

(102.82 cm) and a high of 93.15 inches (236.60 cm) (NOAA, 2009b). Across years,

rainfall is relatively evenly split between months though the Study Area is subject

to periods of both drought and flood, and the climate rarely seems to truly exhibit

average conditions (NOAA, 2009b; USACE, 2009a).

The Study Area is susceptible to tropical waves, tropical depressions, tropical

storms, and hurricanes. Historical data from 1899 to 2008 indicate that 31

hurricanes and 41 tropical storms made landfall along the Louisiana coastline

during this period (NOAA, 2009b). The 2005 hurricane season brought the most

substantial hurricane damage to the region in recent history, with the arrival of

Hurricanes Katrina and Rita. Hurricane Gustav, while much smaller and less

intense, brought additional damage to the region with landfall on September 1,

2008, that was further exacerbated by subsequent impacts from Hurricane Ike on

September 13, 2008. While there were extensive land losses due to the storms in

parts of coastal Louisiana, negligible wetland losses were detected for the Study

Area as a result of these storms (Wicker, 1980; Barras et al., 1994; Barras et al.,

2003; Morton et al., 2005).

5.3.1.3 Geomorphic and Physiographic Setting

Over long, geologic time scales and across an extended region, coastal processes

have affected and continue to influence the Study Area. Riverine processes,

occurring at smaller spatial scales and over shorter time periods, are the

predominant contemporary forces that shape the geomorphic and physiographic

setting of the Study Area. The co-occurrence of these processes has been further

influenced by human modifications. A description of how these processes define the

geomorphic and physiographic setting is included in the following sections.

Consistent with 40 Code of Federal Regulation (CFR) Parts §§1500.4 (j) and

1502.21, the description of the geomorphic and physiographic setting provided in

the LCA FPEIS (USACE, 2004b) is incorporated by reference.

Formation of the Lake Pontchartrain Basin began approximately 20,000 years ago

in the late Wisconsin glaciations of the Pleistocene Epoch (Penland et al., 2002).

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Climatic warming and the subsequent melting of glaciers caused a rapid rise in sea

level from its lowstand (18,000 years before present) to its highstand (3,000 to 4,000

years before present)—a period known as the Holocene Transgression. As sea level

rose, incised river valleys eroded into and beveled the adjacent Pleistocene uplands.

After sea level reached its highstand, a sequence of events occurred that was critical

to the formation of the basin and the estuarine system present today. Development

of the Pine Island barrier shoreline trend resulted in the creation of Lakes

Pontchartrain and Maurepas. The St. Bernard delta complex built out from the

alluvial valley onto the continental shelf and buried the Pine Island barrier trend.

The Mississippi River abandoned (2,000 years before present) the St. Bernard delta

complex for the Lafourche delta complex and later returned to the Modern delta

complex (1,000 years before present).

The Lake Pontchartrain Basin is divided into three distinct, geomorphic regions:

the Pleistocene Terraces Region to the north of Lake Maurepas, Pontchartrain, and

Borgne; the Mississippi River Deltaic Plain Region to the south of the lakes; and the

Marginal Deltaic Basin Region, which includes the lakes and surrounding wetlands.

The Study Area for the project is within the Maurepas Swamp Area—the

westernmost portion of the Marginal Deltaic Basin.

The first deltaic deposits to enter the area were homogenous prodelta clays. This

was followed by the deposition of interdistributary bay deposits as the Mississippi

River and its distributaries prograded. The deposits were finer sediments (silty clay

and clay) that were transported away from the distributary channel and settled out

of suspension as interdistributary deposits.

Depositional environments within the Study Area include point bar, natural levee,

and inland swamp, in order of decreasing area. Point bars line the Mississippi

River, forming the batture, and were developed through lateral channel migration

of the river, cutbank formation and collapse, followed by the deposition of sand and

silt on the opposite convex bank (Fisk, 1947; Galloway and Hobday, 1983). Floods

historically deposited sand and silt adjacent to the river and formed natural levees

along the Mississippi River that grade toward the inland swamp (Galloway and

Hobday, 1983). The distribution area and, thus, most of the Study Area consists of

inland swamp described as low-lying, very flat, poorly drained areas bounded by

natural levees or low terraces (Saucier, 1994).

5.3.1.4 Soils

Soils include both hydric and nonhydric soils. Hydric soils are characteristic of

wetlands and are predominant. Organic material accumulation in the surficial soil

horizon is evident across most of the Study Area due to slow decomposition under

anaerobic, water saturated conditions. Shaffer et al. (2003) noted atypically low soil

bulk densities for Maurepas Swamp (0.05-0.15 grams/ cubic centimeters [g/cm3]),

which are more typical of freshwater and intermediate marshes (Hatton, 1981).

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Interstitial soil pH was slightly acidic, typical of organic soils with low bulk

densities, and higher bulk densities were found in areas receiving agricultural and

other runoff (Shaffer et al., 2003). Low bulk densities and high organic matter

content likely result from insufficient sediment input since the leveeing of the

Mississippi River.

5.3.1.5 Hydraulics and Hydrology

Lower Mississippi River: 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 levels of the

Lower Mississippi River are directly related and exhibit a seasonal pattern that is

linked to snowmelt runoff and spring rains. High flows and water levels are

characteristic of spring months (March 1-May 31), while low flows and low water

levels are typical from mid-summer to mid-fall (August 16 - November 15). 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. Additionally, strong south and

southeasterly winds can cause rapid rise and northwesterly winds rapid decline in

the river’s stage (USACE, 2000b).

Blind River and Maurepas Swamp: Flows and water levels in the Study Area

differ substantially from historical conditions due to isolation from Mississippi

River floods. Flow directions in general correspond to historical patterns for the

Study Area and vicinity. Drainage features have altered runoff and tidal inflow

rates in Blind River, adjoining channels, and swamps. The hydrologic effect of

these modifications is variable and dependent on location. Most of the contributing

watersheds are hydrologically “flashy” as runoff occurs very quickly after rainfall

events and very little precipitation is lost to evapotranspiration or groundwater

seepage in the contributing watersheds (Day et al., 2004).

A wide range of climate conditions (including tropical depressions, storms and

hurricanes) provides the potential for hydrologic conditions ranging from extreme

flooding to extended drought in the area.

Since the construction of the MR&T levees, Maurepas Swamp and Blind River have

been cut off from periodic overflows from the Mississippi River that brought

freshwater, sediment, and nutrients to the swamp. With minimal soil building and

moderately high subsidence rates, there has been a net lowering of ground surface

elevation.

Based on the strong correlation between lake and swamp water levels, the observed

doubling of flood durations from 1955 to present at Pass Manchac coupled with

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lower swamp than lake elevations suggests that the duration of inundation within

the Study Area has drastically increased over the last 50 years (Thomson et al.,

2002). A limited ability to drain and persistent flooding characterize the existing

hydrology in the swamp, which conflicts with historical drying cycles. Short

circuiting of the natural drainage patterns has created ponding and stagnant

waters in some areas.

Extensive modeling of hydrologic flow patterns in southwest Maurepas Swamp was

conducted in support of CWPPRA Project PO-29, Mississippi River Reintroduction

into Maurepas Swamp (Day et al., 2004; URS, 2007). Analysis examined physical

hydrodynamic and hydrologic characteristics and trends for several factors under

various conditions. Factors included precipitation, stage ranges, velocity, flow,

water budget, tidal propagation, channel over-banking, and swamp circulation in

relation to physical features. The results of these and other related investigations

reveal regional trends applicable to the Study Area, as follows (Lee Wilson &

Associates et al., 2001; Mashriqui et al., 2002; Penland et al., 2002):

Lake Maurepas stage exerts a significant influence (backflow) on water levels

within Blind River and adjoining channels. When the swamp stage is less

than the lake stage, backflow exists.

Propagation of astronomical tides decreases with distance from Lake

Maurepas shoreline; is often absent from smaller channels and the swamp;

and is overwhelmed by meteorological tides.

Meteorological tides related to storm events and winds have a pronounced

affect on stage and flows and exhibit seasonal and daily variability. Storms

and prevailing winds from the southeast in the summer and early fall raise

water levels in the swamp as they push Gulf water into the system.

Continental fronts with prevailing winds from the northeast in the winter

often lower swamp water levels as they push water out of the system toward

the Gulf.

Precipitation and runoff have small influences on Blind River stage and

flows.

Overbank flooding and flow through existing berm gaps from Blind River and

adjoining channels into the swamp is dependent on river stage levels in

relation to river bank and existing berm elevations.

Lake Maurepas: Northeast of the Study Area, Lake Maurepas is a 90 mi2 (233

km2) shallow estuarine water body that receives tidal inflow from Lake

Pontchartrain to the east and freshwater input from tributaries to the north, west,

and southwest. Freshwater input occurs primarily during rainfall runoff through

the Tickfaw and Blind rivers and the ARDC. These rivers have combined average

flows less than 3,400 cfs (Lee Wilson & Associates, 2001). These rivers are prone to

brief high-intensity flood events that contribute the majority of freshwater and

sediment entering Lake Maurepas. Tidal flow passes between Lake Maurepas and

Lake Pontchartrain through Pass Manchac and exhibits diurnal and seasonal

fluctuation.

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The USACE maintains a gauge at Pass Manchac near Ponchatoula, Louisiana,

(Gauge # 85420) that has daily stage data for a period of record from July 1955 to

August 2005. Water levels at this location are representative of the stage in the

east end of Lake Maurepas. Stage analysis was performed for a 30-year period

(January 1, 1975 - December 31, 2004). Since this location is tidally influenced, the

stage readings are for different parts of the tide, ranging from high to low tide.

Subtle trends indicate that, for a given year, the stage for Lake Maurepas is

bimodal; it generally rises in the spring, then falls during summer, rises in the fall,

and again falls to low levels in the winter. Other analyses have detected a similar

trend for the station (Keddy et al., 2007). Limited hourly stage data are available

for part of 2009 (April 27, 2009 -present). Based on this short term data, average

tide heights are 0.4 + 0.2 ft (0.1 + 0.1 m) (mean + standard deviation [SD]).

5.3.1.6 Sedimentation and Erosion

Lower Mississippi River: 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, 2008). 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. The sand to silt

ratio of suspended sediment is typically 20% sand to 80% silt (USGS, 2008).

Mashriqui and Kemp (1996) reported the mean sediment load of the Mississippi

River at Tarbert Landing to be 226 milligram / liter (mg/L), of which about 26% was

sand, with silts and clays each contributing between 30% and 40%.

Blind River and Maurepas Swamp: Several sampling efforts have been recently

conducted to determine sediment loads in Maurepas Swamp. Examining these, the

total suspended solids (TSS) concentrations collected monthly were similar from

April 2000 to June 2001 (mean: 16 mg/L; range: 4 - 101 mg/L) as for April 2002 to

May 2002 (mean: 15 mg/L; range: 1 - 58 mg/L) (Day et al., 2001; Day et al., 2004).

Furthermore, stations located around Lake Maurepas exhibited the highest TSS

concentrations, which was likely due to resuspension of bottom sediments due to

high wave energy.

The Blind River is listed on the 2006 303(d) list of impaired water bodies due to

impairment from excess sediments, extending from its headwaters to its

distribution into Lake Maurepas (LDEQ, 2006). In accordance with EPA mandate,

TMDLs must be developed for sediments and nutrients for Blind River by 2011.

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5.3.1.7 Vegetation Resources

Wetland Vegetation: Wetland habitat descriptions are based on field

observations and are described in accordance with The Natural Communities of

Louisiana (LNHP, 2009). Existing habitat types and respective acreages are based

on the 1988 USGS National Wetlands Research Center (NWRC) map and include

aquatic bed floating vascular, bald cypress-tupelo swamp, bottomland hardwood

forest, freshwater marsh, and scrub-shrub swamp. The map is the most refined

habitat classification for the Study Area with regards to spatial resolution and

community taxonomy. Habitat structure has changed over time; however, bald

cypress-tupelo swamp has remained the predominant habitat type, pre-dating

human disturbance and persisting today.

Aquatic Bed Floating Vascular: The Aquatic Bed Floating Vascular habitat

includes a diverse group of plants that require surface water for optimum growth

and reproduction, preferring continuous or frequent flooding. Aquatic beds are

moved easily by water currents or wind and include species that float freely either

in the water or on its surface (Cowardin et al., 1979). The LNHP (2009)

characterizes aquatic bed floating vascular communities as highly productive

habitat that serves as an important coastal ecosystem component through

supplying oxygen, detrital material, and dissolved organic nutrients to the water

and producing organic matter that is consumed by organisms. Further, these

systems provide valuable habitat for numerous fish and wildlife species. This

habitat type is found along the Blind River and the canals maintained by St. James

Parish. Common species present include water lily, alligator weed, and duckweed.

Depending on the season and rainfall regime, duckweeds can dominate the canals

forming dense mats several inches thick.

Bald Cypress-Tupelo Swamp: Occupying a landscape position slightly higher in

elevation than freshwater marsh but lower in elevation than bottomland hardwood

forests, bald cypress-tupelo swamp habitats are typically located along surface

water channels and in back swamp depressions and swales. This habitat is

inundated or saturated on a nearly permanent basis throughout the growing

season, except periods of extreme drought (Penfound, 1952; Mitsch and Gosselink,

2000). Seasonal fluctuation of water level is typical (LNHP, 2009).

Bald cypress-tupelo swamp is the most prevalent habitat type in the Study Area,

comprising over 90% of the total area. According to a habitat assessment of the

Study Area using the USFWS the WVA Model, bald cypress was the canopy

dominant in a few locations and water tupelo was the predominant species across

sites. Red maple and green ash were prevalent in the midstory in most areas.

Further description of observed community characteristics is presented in the

appendices of Volume VI.

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Bottomland Hardwood Forest: This forest association is found at higher

elevations than surrounding swamp habitats and is inundated less frequently.

Bottomland hardwood forests are generally intolerant of inundation during the

growing season (Putnam et al., 1960; Hodges, 1997). Bottomland hardwood forests

provide habitat for many species of wildlife, such as white-tailed deer, grey

squirrels, raccoons, and numerous bird species.

As elevation increases from the swamp toward the natural levee, species

assemblages transition from flood-tolerant swamp species to less flood-tolerant

bottomland hardwood forest. In the distribution area, these forests have undergone

high mortality of less flood-tolerant species (e.g., green ash) and appear to be

transitioning toward bald cypress-tupelo swamp. Upgradient from the distribution

area, the Romeville and South Bridge Canals transect areas of bottomland

hardwood forest. The batture—the area between the levee and the Mississippi

River—is vegetated by bottomland hardwood forest characterized by pioneer

species, such as black willow. The batture is frequently inundated during the

spring and summer at higher river stages.

Freshwater Marsh: Freshwater marsh is typically located adjacent to

intermediate marshes. Freshwater marshes plant communities are extremely

heterogeneous within and between habitats based largely on the frequency and

duration of flooding, as related to microtopography, which collectively influence

species composition. Other factors regulating species distribution include substrate,

current flow, salinity, competition, and allelopathy. Consequently, freshwater

marshes exhibit the highest species diversity of any marsh type, with as many as 92

plant species reported (LNHP, 2009). Soil organic matter content is highest for

freshwater marsh in relation to other marsh types. Freshwater marsh supports the

highest wildlife populations of any marsh type, providing overwintering habitat for

many migratory waterfowl. Fisheries important to Louisiana’s economy and

ecology depend on freshwater marsh for critical nursery areas, including such

species as flounder, croaker, and juvenile brown and white shrimp (LNHP, 2009).

In the Study Area, freshwater marsh is mainly found in pipeline and powerline

tracts. While some of these areas have ditches, many of the easements are slightly

elevated above the adjacent swamp and are thickly vegetated with grasses and

forbs. These areas are usually saturated to the surface and flooded only during

higher water periods.

Scrub/Shrub Swamp: Scrub/shrub swamp vegetation includes large shrubs and

small trees less than 35 ft in height. This habitat is found in depressional,

semipermanent pools and along slow flowing channels and streams where soils are

flooded for extended periods. Dry periods are infrequent, occurring during summer

months and often associated with droughts. This habitat is found along the Blind

River and area canals. It is also present along the edges of pipeline tracts.

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Ecological Condition: This chapter describes the ecological condition of the

dominate bald cypress-tupelo forests in the Study Area. Studies indicate a trend of

declining health in bald cypress-tupelo forests throughout coastal Louisiana

including the forests of the Study Area (Conner et al., 1981; Barras et al., 1994;

Myers et al., 1995; Chambers et al., 2005). The forests exhibit numerous symptoms

of stress that are regionally apparent in the southwest Maurepas Swamp and are

most evident in more degraded locations.

In forested swamps of the southeastern United States, recorded rates of

aboveground primary productivity range from roughly 200 to 2,000 g per square

meter per year (m2/yr) (Mitsch and Gosselink, 1993; Conner and Day, 1976; Conner

and Buford, 1998). However, over a 5-year study in southwest Maurepas Swamp

Shaffer et al. (2003) observed average aboveground productivity of only 400-700

g/m2/yr, rates typically associated with wetlands that are nearly permanently

flooded, nutrient limited, or exhibit limited water flow (Schlesinger, 1978; Taylor,

1985; Mitsch et al., 1996; Megonigal et al., 1997; Conner and Buford, 1998).

Comparison with the structural characteristics of other bald cypress-tupelo forests

further suggests stressed growing conditions in the Study Area. Field observations

and research by Shaffer et al. (2003) indicate that the forests support atypically low

stem densities and basal areas for the community type. Furthermore, high

mortality rates—approximately 2% or less annually according to Shaffer et al.’s

(2003) estimates—coupled with limited to no regeneration threaten the persistence

of these forests. Throughout coastal Louisiana, increased mortality of less floodtolerant species due to increased flooding is a common trend (Conner et al., 1981;

Shaffer et al., 2003).

Interacting stressors implicated in forest degradation in the Study Area are

increased flood duration, stagnation, salinity, and nutrient limitations and topdown herbivore pressure. Bald cypress and water tupelo are among the most floodtolerant tree species in the southeast (Hook, 1984). However, prolonged, deep

flooding over an extended period may have detrimental effects on growth and

survival (Penfound, 1949; Eggler and Moore, 1961; Harms et al., 1980; Brown, 1981;

Kozlowski, 1984; Conner and Brody, 1989; Dicke and Toliver, 1990; Conner and

Day, 1992; Young et al., 1995). Where water levels fluctuate and pulsed flows

occur, bald cypress-tupelo forests exhibit among the highest productivity rates for

forested ecosystems (Brinson et al., 1981; Brown, 1981; Conner and Day, 1982;

Brinson, 1990; Lugo et al., 1990; Conner, 1994).

Permanent flooding prevents the bald cypress and water tupelo regeneration

because their seeds cannot germinate under water and require a dry period

(Mattoon, 1915; DeMaree, 1932; DuBarry, 1963; DeBell and Naylor, 1972). When

germination does occur, seedlings can only withstand complete submergence over

short intervals, up to 45 days (Souther and Shaffer, 2000), and increased mortality

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occurs when seedlings are inundated for greater than 2 weeks (Brandt and Ewel,

1989). Consequently, water levels low enough and with adequate duration to allow

germination and seedling growth to heights above subsequent flood stages are

required for successful regeneration of bald cypress and tupelo (Conner et al. 1986;

Chambers et al., 2005).

Swamps can survive short-term salinity pulses over several days to weeks (Allen et

al., 1994; Campo, 1996; Conner et al., 1997); however, salt stress due to increases in

background levels and extended exposure during meteorological events (e.g.,

droughts and hurricanes) is a major factor influencing tree productivity and

survival across coastal Louisiana and at all but the most interior sites in Maurepas

Swamp (Pezeshki et al., 1990; Conner and Askew, 1992; Allen, 1992; McLeod et al.,

1996; McCarron et al., 1998; Krauss et al., 1998; Shaffer et al., 2003; Effler et al.,

2007). Together, flooding and salinity have a more detrimental effect on seedling

growth and survival (Conner, 1994; Allen et al., 1996).

Limited nutrients and herbivory are additional stressors impacting Study Area

forest health. Mississippi River floods brought nutrients sediment into the Study

Area. Prevention of these floods has resulted in nutrient, specifically nitrogen,

limitations (Lane et al., 2003; Effler et al., 2007). Herbivory also significantly

influences area forest health. Common defoliators of bald cypress and water tupelo

are bald cypress leafroller (Archips goyerana) and forest tent caterpillar

(Malacosoma disstria), respectively, with other minor pests (Chambers et al., 2005).

Nutria also negatively impact tree species regeneration and are discussed further in

the FS/SEIS (Volume IV)(Meyers et al., 1995).

Based on field observations of forest structure within the Study Area, trends

observed through research in adjacent regions of Maurepas Swamp, and aerial

photography (past and present), a habitat condition map was developed to spatially

classify degraded swamp areas. The classification scheme followed the approach

used by researchers for other areas within Maurepas Swamp. Patches were

discretely defined based on the period of time over which they would transition to

freshwater marsh: 20-30 years to marsh, 30-50 years to marsh, and greater than 50

years to marsh. The areas and their estimated times to convert to marsh are

shown in Figure 5-4.

Upland Vegetation: Based on the USGS National Land Cover Database (2003)

and remote verification, upland areas within the Study Area include lands in

cultivation, pasture, developed, and shrub/scrub cover classes.

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Invasive Species: Chinese tallow, water hyacinth, and hydrilla are invasive plant

species observed in the area. Recently, common salvinia, a floating aquatic fern,

has colonized and established populations and often covering drainage canals

(USACE 2004a; LACPRA, 2008). Alligator weed also grows in the canals and

interior swamp of the Study Area. Chinese tallow and chinaberry are established

on berms along the canals. Invasive plant species that were not observed in the

Study Area but are confirmed within the Lake Maurepas Watershed and, thus, may

be present in the Study Area include parrot feather, wild taro, Brazilian waterweed,

and water lettuce (Kravitz et al., 2005).

Rare, Unique, and Imperiled Vegetation: The LNHP maintains a directory of

over 6,000 occurrences of rare, threatened, or endangered species; unique natural

communities; and other distinctive elements of natural diversity. Across the state,

LNHP has identified 380 ecologically significant sites also included in the database.

The LNHP database was queried for the occurrence of rare, unique, and imperiled

vegetative communities within the Study Area. Of these, the presence of bald

cypress-tupelo swamp was the only recorded occurrence. Additional unique

communities in the Study Area identified by the 1988 NWRC habitat map and field

inventory include bottomland hardwood forest and freshwater marsh.

Bald Cypress-Tupelo Swamp (Rarity Rank S4/G3G5)

Statewide estimates of swamp losses range from 25%-50% of the original

presettlement acreage, and old-growth forests are very rare. Many factors threaten

the persistence and expansion of bald cypress-tupelo swamp. Threats include

development activities; saltwater intrusion, subsidence, and hydrologic alteration;

logging; chemical contamination; and invasive species.

Bottomland Hardwood Forest (Rarity Rank S4/G4G5)

Bottomland hardwood forests are found in all Louisiana river basins. The current

range has been reduced 50%-75% of its original presettlement acreage. Old growth

stands are very rare. Historically, clearing of forests for agricultural production has

been the primary cause of loss. Additional threats include hydrologic alterations;

road construction, utilities, and pipelines; and invasive species.

Freshwater Marsh (Rarity Rank S1S2/G3G4)

The LNHP ranks this community as imperiled because, due to saltwater intrusion,

it has undergone the largest reduction in acreage of any marsh type over the past

20 years. Of the estimated 1 to 2 million acres of freshwater marsh in Louisiana

during presettlement times, only 25-50% of this habitat remains.

5.3.1.8 Threatened and Endangered Species

Within the State of Louisiana, there are 29 animal and three plant species under

the jurisdiction of the USFWS and/or the NMFS that are federally classified as

Federally-Listed Endangered and Threatened Species

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endangered or threatened (Table 5-2). Four animal species and no plant species are

found within the Study Area.

Table 5-2: Threatened and Endangered Species in Study Area

Threatened and Endangered Species Species Status

Threatened Endangered

West Indian manatee (Trichechus manatus) X

American alligator (Alligator mississippiensis) X

Pallid sturgeon (Scaphirhynchus albus) X

Gulf sturgeon (Acipenser oxyrinchus desotoi) X

The pallid sturgeon is an endangered fish found in the Mississippi River (Lee et al.,

1980; Killgore et al., 2007). The species is adapted to large, free-flowing turbid

rivers. Detailed habitat requirements of this fish are not known, but it is believed

to spawn in Louisiana. Occurrence of pallid sturgeon in the Mississippi River near

the diversion site is extremely likely according to Kilgore et al. (2007) and based on

sampling efforts by Kirk et al. (2007) in 2005 and 2006. Presence of subadult and

adult pallid sturgeon is nearly certain within this reach of the Mississippi River;

however, occurrence of juvenile specimens is unconfirmed. Formal consultation on

the pallid sturgeon was conducted and a Biological Opinion was received on

September 23, 2010 from the USFWS. The USFWS determined that the level of

expected take is not likely to result in jeopardy to the pallid sturgeon (Volume IV

Appendix A).

Gulf sturgeon is found in rivers and lakes of the Lake Pontchartrain Basin and

adjacent estuarine areas (USFWS, pers comm, 2009). Based on habitat preferences

and past studies, the presence of Gulf sturgeon is unlikely along the reach of the

Mississippi River where proposed diversion uptake locations are proposed (Ross,

2001).

The West Indian manatee may occasionally enter Lake Pontchartrain, Lake

Maurepas, and the associated coastal waters and marshes of Louisiana (James F.

Boggs, pers comm, 2009). On April 29, 1985, a manatee was sighted in the Blind

River approximately 200 yards south of the I-10 bridge. Additional sightings have

occurred near the Study Area (USFWS, 2009). Manatees are found within local

waterways only during months with warm enough conditions. While rare, the

potential exists for the manatee to be within the Study Area.

While the bald eagle was officially removed from the list of threatened and

endangered species, it has continued protection under the Migratory Bird Treaty

Act (16 U.S.C. 703-712) and the Bald and Golden Eagle Protection Act (16 U.S.C.

668-668c). The LDWF has identified three recorded nesting sites within the Study

Area. Field investigations to determine the exact locations and potential statuses of

these bald eagle nests were performed and resulted in the location of one potentially

active nest.

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The American alligator, a recently recovered species, is still listed as threatened due

to similarity of appearance with other protected species and is provided protection

under the Convention on International Trade in Endangered Species of Wild Fauna

and Flora. At present, Louisiana’s wild alligator population is estimated by LDWF

to be approximately 1.5 million animals, with over 500,000 additional specimens on

alligator farms in the state. Nest densities within the Study Area are medium

(approximately 1 nest per 250 acres) based on survey data from 1996-2000.

The LDWF maintains the LNHP Biological Conservation Database, which includes

over 6,000 occurrences of rare, threatened, and endangered species, unique natural

communities and other distinctive elements of natural diversity, and some 380

ecologically significant sites statewide. Within Ascension and St. James parishes,

LNHP tracks the occurrence of the species and habitats listed in

State-Listed Threatened and Endangered Species

Table 5-3.

Table 5-3: LNHP Rare, Threatened, and Endangered Species and Natural

Communities in Ascension and St. James Parishes (April 2008)

Common Name Scientific Name State Rank

Gulf sturgeon

a

Acipenser oxyrinchus desotoi S1S2

swamp milkweed Asclepias incarnate S2

Bottomland hardwood forest - S4

Cypress swamp - S4

Cypress-tupelo swamp - S4

Bald eagle Haliaeetus leucocephalus S2N, S3B

Four-toed salamander Hemidactylium scutatum S1

Long-tailed weasel Mustela frenata S2S4

Correll’s false dragon-head Physostegia correllii S1

Inflated heelsplitter Potamilus inflatus S1

Eastern spotted skunk Spilogale putorius S1

West Indian manatee Trichechus manatus SZN

Waterbird nesting colony - SNR

a State Ranks: S1 = critically imperiled in Louisiana ;S2 = imperiled in Louisiana ;S3 = rare and local throughout the state;

S4 = apparently secure in Louisiana; B or N may be used as qualifier of numeric ranks and indicating whether the

occurrence is breeding or nonbreeding; R = reported from Louisiana; SZ = transient species in which no specific consistent

area of occurrence is identifiable

5.3.1.9 Cultural and Historic Resources

Recorded archival and historical research was conducted to develop a baseline level

of knowledge for prehistoric and historic period cultural developments and to

identify archaeological and historical sites previously recorded in the Study Area.

Information maintained by the Louisiana Division of Archaeology was consulted to

identify previous cultural resources surveys as well as to obtain site forms for

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previously recorded sites. Detailed results for the background research and cultural

resources inventory conducted are included in Volume IV. Additional cultural

resource surveys are being conducted to verify existing resources and determine

whether previously unknown resources exist, based on geomorphology and

historical sequence of growth and development in the area. These efforts are being

conducted in coordination with SHPO in accordance with Section 106.

5.3.1.10Recreation

The area combines natural and outdoor opportunities with those of the area’s

cultural heritage. Despite the presence of numerous roadways transecting and

surrounding the Study Area, the majority of the area is accessible only by boat due

to the nature of the swamp. The Maurepas Swamp WMA - Eastern and Western

Tracts - encompasses approximately 67,712 acres (27,402 hectare [ha]) that are

managed by the LDWF. The WMA has provisions for camping with tent sites,

trailer sites, and boat ramps; the St. James and Grand Point boat ramps are in the

Study Area. Recreational activities and uses currently permitted in the area year

round include boating, fishing, hunting, sightseeing, and birding. Other

recreational activities permitted seasonally include deer hunting during winter

months with restricted access to the hunting sites. Consideration has been given to

developing walking trails and for reviving the swamp to make it more accessible to

the public for walking and sightseeing. The LDWF is currently involved in the

initial phase of developing WMA-specific management directives to maintain and

enhance the WMA in such a way that will continue to be compatible with its current

uses.

The 2009-2013 Louisiana SCORP provides a statewide inventory of recreation

resources and identifies recreational needs. The majority of the LCA Small

Diversion at Convent/Blind River Study Area fits within the larger SCORP Region

3; the Ascension Parish portion of the Study Ares is within SCORP Region 2. The

activities rated as most important to the residents of Regions 2 and 3 are fishing,

visiting natural places, walking/hiking, and public access to state waters.

5.3.1.11Socioeconomics Resources – Oil, Gas, and Utilities

Data from the LDNR SONRIS indicate that the southeastern Maurepas Swamp had

undergone extensive oil and gas exploration, in the early to mid-twentieth century.

Exploration efforts have occurred primarily to the north and south of the Study

Area, with the north experiencing more concentrated activities. Online data show

only two wells within the Study Area, and they are plugged and abandoned.

Location data for gas transmission and hazardous liquid pipelines, liquefied natural

gas plants, and breakout tanks throughout the United States are compiled by the

U.S. Department of Transportation - Pipeline and Hazardous Materials Safety

Administration. Geospatial data are archived in the National Pipeline Mapping

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System, with the most recent iteration issued January 2004. Locations of pipelines

within the Study Area are provided in Table 5-4.

Table 5-4: Summary of Pipeline Information in Study Area

Company Installation

Date Product

Acadian Pipelines; Cypress Gas Pipeline 16" - 1957

4" - 1976 Natural Gas

Air Products 1992 Hydrogen Gas

Chevron Pipeline

Varies

(earliest is

1965)

Natural Gas, NGL

Propane

Natural Gas

Natural Gas

Natural Gas, NGL, Propane

Gulf South Pipeline Company, LP 1990 Natural Gas

Marathon Pipeline, LLC 1978 Refined Products: Gasoline, Diesel,

Jet Fuel

Petrologistics Olefins, LLC 1980 Ethylene

Williams Gas Pipeline 1971 Natural Gas

Shell Pipeline 1967 Ethylene

5.3.2 Future Without Project Condition

5.3.2.1 Soils

The No Action Alternative would have no direct impacts on soil resources. Existing

conditions would persist, including no net vertical accretion of soil deposition and

continued subsidence over the 50-year period of analysis.

The indirect impacts of the No Action Alternative would be the continued

degradation of soils within the distribution area. Soils within the distribution area

would remain nutrient poor and exhibit atypically low bulk densities for forested

wetlands due to insufficient sediment content. With increased duration of flooding

and impoundment, net primary productivity within the Study Area would continue

to decline, and existing wetland vegetation would continue to diminish. Declines in

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primary productivity would reduce organic matter accretion rates and, thus,

increase subsidence. Increased physiological stress would make plants more

susceptible to further damage by biotic (e.g., herbivory, infection) and abiotic (e.g.,

wind damage) factors. Eventual mortality of woody and herbaceous vegetation and

the accompanying decomposition of belowground biomass would further elevate

subsidence rates and result in a change in habitat from vegetated wetlands to open

water.

Cumulative impacts of the projected loss of soil resources from the Study Area

would be in addition to the loss of soil resources throughout Louisiana. The LCA

Report estimated coastal Louisiana would continue to lose land at a rate of

approximately 6,600 acres per year (2,671 ha/year) over the next 50 years (USACE,

2004a). Wetland soil losses in the Study Area would be offset to some extent by

other Federal, state, local, and private restoration efforts as described in the 2004

LCA Report. Although these projects will help offset losses of soil resources in the

Upper Pontchartrain subbasin, the resulting benefits will be localized and will not

affect processes within the Study Area.

5.3.2.2 Hydraulics and Hydrology

Lower Mississippi River: Under the No Action Alternative for this study, no

direct or indirect impacts on flows and water levels in the Lower Mississippi River

would occur.

Blind River and Maurepas Swamp: Under the No Action Alternative, not

implementing a freshwater diversion into southeastern Maurepas Swamp would

have no direct impacts on flow or water levels within in Blind River and Maurepas

Swamp. Indirect impacts of the No Action Alternative would result in the

persistence of existing conditions, including a limited ability of the swamp to drain

and persistent flooding that conflicts with historical drying cycles in the swamp,

short circuiting of the natural drainage patterns, ponding and stagnant waters in

some areas, and minimal contribution and circulation of nutrients and sediments in

the swamp. Blind River and Maurepas Swamp would continue to deteriorate.

Minimal soil building and moderately high subsidence rates that resulted in a net

lowering of ground surface elevation would continue, and the swamp will continue

to be persistently inundated. The limited ability to drain and the persistent

flooding that exists in the swamp would continue. The No Action Alternative would

allow the existing swamp to function 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 swamp ecosystem. Increases in relative sea level due to continued

subsidence and sea level rise would continue to extend flood duration and elevate

flood stage within Maurepas Swamp, accompanied by impoundment of hypoxic,

nutrient-deficient water.

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Current guidance for incorporating projected sea level rise is established by

Circular No. 1165-2-211. 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 historical rate of RSLR for the Study Area, as discussed in the FS/SEIS (Volume

IV). Based on daily stage data from 1959 to 2009 for the West End at Lake

Pontchartrain Gauge (85625), the estimated historical rate of RSLR for the Study

Area is 0.0302 ft/yr (9.20 mm/yr) with a standard error of 0.65 feet (198.12 mm).

Intermediate and high rates are based on modified NRC curves I and III,

respectively (NRC, 1987), in which the current global mean sea level change is set

at 0.00558 ft/yr (1.7 mm/yr).

Eustatic estimates are added to the historical local subsidence rate (0.0246 ft/yr or

7.50 mm/yr) to calculate the total RSLR for the intermediate and high rate

scenarios. All scenarios were evaluated at 5-year increments over the 50-year

project life (2012-2062). Projected RSLR over the 50-year period of analysis for low,

intermediate, and high scenarios is presented in Table 5-5.

Table 5-5: Projected Relative Sea Level Rise

Year

RSLR (feet)

Low Intermediate High

2012 0 0 0

2017 0.15 0.17 0.24

2022 0.30 0.35 0.51

2027 0.45 0.53 0.78

2032 0.60 0.72 1.08

2037 0.75 0.90 1.39

2042 0.91 1.10 1.72

2047 1.06 1.29 2.06

2052 1.21 1.49 2.42

2057 1.36 1.70 2.80

2062 1.51 1.90 3.19

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Figure 5-5: Projected RSLR over project life

Lake Maurepas: Under the No Action Alternative, no indirect or direct impacts on

flows and water levels in Lake Maurepas would occur. Cumulative impacts would

be the synergistic effect of the No Action Alternative on flow to and water levels in

Lake Maurepas as increased runoff in the watersheds that drain into the lake from

increased future development would likely lead to an increase in water levels in

Lake Maurepas. The LCA Small Diversion at Hope Canal will result in a

significant freshening of the lake and approximately double the turnover rate (Lee

Wilson & Associates et al. 2001).

5.3.2.3 Sedimentation and Erosion

Lower Mississippi River: Under the No Action Alternative, no direct or indirect

impacts on sedimentation and erosion in the Lower Mississippi River would occur.

Blind River and Maurepas Swamp: The No Action Alternative would have no

direct impacts on flow or water levels within Blind River and Maurepas Swamp.

Indirect impacts of the No Action Alternative would result in the persistence of

existing conditions, including a limited ability of the swamp to drain, persistent

flooding that conflict with historical drying cycles in the swamp, short circuiting of

the natural drainage patterns, ponding and stagnant waters in some areas, and

minimal contribution and circulation of nutrients and sediments in the swamp.

Under the No Action Alternative (not implementing a freshwater diversion into the

Study Area in southeast Maurepas Swamp), Blind River and Maurepas Swamp

would continue to deteriorate. Maurepas Swamp and Blind River have been

virtually cut off from periodic overflows from the Mississippi River that brought

freshwater, sediment, and nutrients to the swamp. Minimal soil building and

moderately high subsidence rates that resulted in a net lowering of ground surface

elevation that would continue and the swamp would continue to be persistently

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inundated. The limited ability to drain and the persistent flooding that exists in the

swamp would continue.

The No Action Alternative would allow the existing swamp to function 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 swamp ecosystem.

Increases in relative sea level due to continued subsidence and sea level rise would

continue to extend flood duration and elevate flood stage within Maurepas Swamp,

accompanied by impoundment of hypoxic, nutrient-deficient water.

Cumulative impacts would be the synergistic effect of the No Action Alternative on

flow and water levels with the additive 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 swamp restoration

projects in the vicinity.

5.3.2.4 Vegetation Resources

Wetland Vegetation: The No Action Alternative would have no direct impacts on

coastal vegetation. Indirect impacts of not implementing a freshwater diversion

would result in the persistence of existing conditions. Both man-made and natural

processes would contribute to the continued loss of vegetated wetland habitats,

including loss of bald cypress-tupelo and bottomland hardwood forest resources,

increased saltwater intrusion, increased flood duration and impoundment, and

increased herbivory.

Exceedance of stress thresholds due to permanent inundation for species in existing

plant communities would result in extensive mortality and a change in habitat from

vegetated wetlands to open water under the No Action Alternative. Modeling

efforts run over a 100-year time span for southern Maurepas Swamp support marsh

persistence and swamp-to-marsh conversion (Hoeppner, 2008). However, a

chronosequence of swamp degradation processes nearer Lake Maurepas suggests

that bald cypress-tupelo swamp would change to open water. Based on field

observations, Lee Wilson & Associates et al. (2001) support the following trajectory:

mortality of herbaceous vegetation with limited conversion to more salt-tolerant

species, reduced tree basal area and stem density, followed by mortality and

transition to open water.

Across the Upper Pontchartrain subbasin, the Coast 2050 Report projected loosing

approximately one-half of the existing swamp habitat, including both bald cypresstupelo and bottomland hardwood forests. Projections were based on observed rates

of wetland loss from 1974-1990 by habitat type in each mapping unit (LCWCRTF &

WCRA, 1999). Land cover of the Amite/Blind River Mapping Unit in 1990 included

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tupelo) and 3,440 acres (1,392 ha) of freshwater marsh. Based on observed annual

rates of loss for swamp (0.83 percent per year) and freshwater marsh (0.02% per

year) in this unit, approximately 42% (or 58,338 acres [23,609 ha]) of swamp and 1%

(or 40 acres [16 ha]) of freshwater marsh would be lost over 50 years. Within the

Study Area, these rates of wetland loss would result in the conversion of 9,139 acres

(3,698 ha) of bald cypress-tupelo forest and 697 acres (282 ha) of bottomland

hardwood forest, or a total loss of 9,836 acres (3,980 ha) of swamp to freshwater

marsh and open water for the interval from 2012 to 2062. These conservative

estimates are based upon the assumptions that wetland loss rates are static in time

and loss occurs continuously. Empirical evidence suggests that the rate of RSLR

may increase in the future, as may the frequency of extreme weather events (i.e.,

tropical storms, hurricanes, and droughts) (IPCC, 2007). Consequently, flood

duration, saltwater influx, and wind damage may also increase in the future,

forcing elevated rates of swamp to marsh/open water conversion.

Cumulative impacts would be the synergistic effect of implementing the No Action

Alternative with the additive combination of coastwide wetland loss and

degradation, as well as the benefits and impacts of other state and Federal projects

in the vicinity, as detailed in the FS/SEIS (Volume IV). Dependent on the flow rate

and timing of discharge, the LCA Small Diversion at Hope Canal would likely result

in extensive freshening of Lake Maurepas, especially when operating during latesummer and early fall—low flow periods at which high salinity and saltwater

intrusion present the greatest threat (Lee Wilson & Associates et al., 2001; Day et

al., 2004). Modeling efforts for that project indicate that 40% of water diverted

through Hope Canal will flow westward across Maurepas Swamp into Blind River

and then into Lake Maurepas (Lee Wilson & Associates et al., 2001). Therefore,

inflow from Lake Maurepas into southeastern Maurepas Swamp would likely

exhibit decreased risk of salinity-related vegetation damage. Nonetheless, this

project would not adequately increase sediment and nutrient delivery to the Study

Area necessary to offset RSLR and the indirect negative impacts of increased flood

duration and stage on wetland vegetation resources.

Upland Vegetation: The No Action Alternative would have no direct or indirect

impacts on upland vegetation.

Invasive Species: The No Action Alternative would have no direct impacts on

invasive vegetation resources. The No Action Alternative, not implementing a

diversion into the Study Area, would have minimal to no indirect impacts on

invasive vegetation resources. Several invasive nonindigenous plant species are

established in the Study Area. Based on field observations, these species do not

appear to be displacing native species and dominating communities that are

converting to marsh. Under the No Action Alternative, reduced species diversity

and removal of native vegetation are likely. Such disturbance (i.e., increased water

levels or stochastic event such as storm-related influx of saltwater) may facilitate

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the spread of invasive plant species in the Study Area (Theoharides and Dukes,

2007).

Cumulative impacts would be the synergistic effect of the No Action Alternative on

invasive vegetation with the additive combination of impacts from coastwide native

vegetation losses and degradation on the transport, colonization, establishment, and

spread of invasive plant species, as well as the benefits and impacts of other state

and Federal projects in the vicinity, as detailed in the FS/SEIS (Volume IV).

5.3.2.5 Threatened and Endangered Species

The No Action Alternative would have no direct impacts on listed (endangered or

threatened) species or their critical habitat in the Study Area.

Indirect impacts of not implementing the diversion into the Study Area in

southeastern Maurepas Swamp would result in the continued degradation,

conversion, and eventual loss of important wetland habitats used by threatened and

endangered species for shelter, nesting, feeding, roosting, cover, nursery, and other

life requirements.

Cumulative impacts would be the synergistic effect of implementing the No Action

Alternative with the additive combination of coastwide wildlife habitat losses and

degradation, as well as the benefits and impacts of other state and Federal projects

in the vicinity. Adverse impacts on listed species from not implementing this

project would be offset, to some degree, by the positive cumulative impacts of

implementing other state and Federal projects as detailed in the of the FS/SEIS

(Volume IV).

5.3.2.6 Cultural and Historic Resources

Under the No Action Alternative, no direct or indirect impacts to cultural and

historic resources in Study Area would occur.

5.3.2.7 Recreation

The No Action Alternative would have direct impacts on recreational resources.

The recreational experience of the site is related to the condition of the area’s

natural resources. Continued water quality and marsh degradation would diminish

the wildlife habitat and would adversely impact area recreation.

The existing recreation benefit of the Study Area is estimated by way of the Unit

Day Value (UDV) method, employed in compliance with the USACE Economics

Guidance Memorandum, 09-03. The natural and built resources of the Study Area

are analyzed and assigned points based on five criteria:

Recreation experience

Availability of opportunity

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Carrying capacity

Accessibility

Environmental

In 2009, point values were assigned to the Study Area. The total points allocated to

the Study Area were 29. According to the USACE Memorandum, 29 points equates

to a $6.89 UDV for general fishing and hunting.

The LDWF estimated the average monthly visitation for the Maurepas WMA to be

787 for the July 2007 to June 2008 timeframe. The proposed Study Area comprises

approximately one-half of the total WMA area. Thus, half of 787, or 394 visits, is an

approximate average monthly use for the proposed Study Area. Three hundred and

ninety-four times the $6.89 unit day value yields an estimated total monthly

recreation benefit of $2,700 for the Study Area or approximately $32,400 on an

annual basis.

Despite its recreational benefit value, if nothing is done in the future, this value will

decline. Recreational resources in the Study Area that would most likely be affected

by the No Action Alternative are those related to loss of wetlands/marshes and

habitat diversity. As the Maurepas Swamp continues to degrade, fragment, and

convert to marsh and open water habitat, the local abundance and diversity of fish

and wildlife species that presently utilize the existing Maurepas Swamp habitats

would be expected to decline over time. Mobile fish and wildlife species would

relocate to more suitable wetland habitats; migratory birds would be required to

find more suitable stopover habitats on their trans-Gulf migrations. Hence, fishing

and hunting opportunities would also like decline. Waterfowl populations,

particularly mallards, are presently declining throughout North America.

Consequently, waterfowl hunting opportunities in the Study Area would likely

decline if these waterfowl population trends continue and if suitable waterfowl

wintering habitat continues to degrade, fragment, and decline in the Study Area.

Recreational birdwatching opportunities would also likely diminish as migratory

bird usage of the Maurepas Swamp declines in response to swamp habitat

degradation, fragmentation, and conversion to marsh and open water.

Indirect impacts of the implementation of the No Action Alternative would result

from the continuing swamp degradation, fragmentation, and conversion to

freshwater marsh and subsequently open water. These conditions would be

expected to cause the abundance and diversity of fish and wildlife to decline over

time. Lower-quality fishery spawning, nursery, and foraging habitat would

translate to a decline in sport fishing opportunities in the future. Decreased use of

the Study Area by game species would likewise reduce hunting opportunities.

Thus, implementation of the No Action Alternative would cause the recreational

value of the Study Area to decline.

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Cumulative impacts would be the synergistic effect of implementing the No Action

Alternative 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 as summarized in the FS/SEIS (Volume IV)

In addition, more recent restoration efforts would also cumulatively interact to help

offset losses of recreational resources in the Study Area by preserving and

enhancing the natural habitats, thereby enabling the continuation and even

expansion of existing recreational activities within the Study Area and the region as

a whole.

5.3.2.8 Socioeconomics Resources – Oil, Gas, and Utilities

The No Action Alternative would have no direct impacts on oil, gas, and utilities

pipelines.

Indirect impacts of not implementing a diversion would result in the persistence of

existing conditions, including swamp degradation, increased flood duration, and

elevated stage levels. The effects of land loss and degradation could lead to

increased costs for maintaining and repairing existing infrastructure in the Study

Area.

Cumulative impacts would be the synergistic effect of the No Action Alternative on

oil, gas, and utilities pipelines with the additive combination of similar oil, gas, and

utilities pipeline 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, as detailed in the FS/SEIS (Volume IV). The projected continued

coastwide decline of forested wetlands would contribute to the deterioration of

substrate upon which oil, gas, and utilities (e.g., water pipelines, telephone, electric

transmission wires) are constructed. The loss of storm buffering provided by

wetlands could result in the need for greater expenditures for maintaining and

repairing existing infrastructure (USACE, 2008c). However, these impacts would

be somewhat offset by other state and Federal restoration projects near the Study

Area.

5.4 Alternatives*

This chapter presents the alternative plan formulation process, alternative

evaluation criteria, selected alternatives for detailed analysis, identification of the

recommended plan, and plan implementation and management. This chapter

documents this approach and, ultimately, the plan implementation and

management.

5.4.1 Plan Formulation Rationale

This section presents an overview of the plan formulation process for the study.

Specifically, management measures are presented, screening criteria are discussed,

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and preliminarny and intermediate alternatives plans are presented along with the

screening process to obtain the final array of alternatives. The preliminary

alternatives plans identified through the plan formulation process were first

screened based on the diversion locations, flow rates, and the diversion method.

The remaining alternatives were then evaluated, based on 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 alternatives plan screening:

completeness, effectiveness, efficiency, and acceptability. Additionally, ecosystem

benefits, cost effectiveness, and environmental impacts were considered to ensure

that the recommended plan best meets the project objectives. This chapter also

describes the recommended plan and its implementation requirements.

As part of plan formulation, a VE study was conducted to identify potential

modifications of restoration measures and plan configurations that could improve

the performance and cost effectiveness of the preliminary measures. The VE team

identified three items as key strategies to consider and three other items to be

considered. Since the VE study was conducted very early in the process, the study

team was able to consider all of the VE recommendations throughout the plan

formulation and to incorporate the VE recommendations as plans were developed and

refined. Consistent with the VE study recommendations, plan formulation included

culverts under U.S. 61, conveyance channels designed with shallow side slopes,

modeling of hydrologic connectivity within the swamp, and a thorough analysis of

alternatives sea level rise scenarios. For additional information on the VE study see

Volume IV, Appendix H.

A total of 99 measures and 12 alternatives plus the No Action Alternative were

considered and evaluated.

5.4.2 Management Measures

Management measures were developed to address Study Area problems and Study

Area opportunities. Management measures were derived from a variety of sources,

including prior studies, the NEPA public scoping process, the VE study

recommendations, and the multidisciplinary, interagency PDT. Management

measures identified were organized into structural (features) and nonstructural

measures (activities).

No Action

A future without project condition was used to compare against alternative plans.

Structural Measures (Features)

Water Management Modifications in Maurepas Swamp: Various water

management measures were identified to divert Mississippi River water to

the swamp. This category of management measures included the inflow of

the water from a distribution system, sheet flow across the swamp through

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existing and proposed berm gaps, then release and, if required, control of flow

and final routing to the Blind River. The diversion flow rate would need to be

controlled at the inlets and outlets to the swamp to manage the water depth

and detention time. This is necessary since a fluctuating hydroperiod

characterized by occasional dry periods is critical to seed germination and

sapling survival in swamps.

Distribution System within the Maurepas Swamp: After being

delivered to the fringes of the distribution area, the freshwater would have to

be transported and distributed throughout the swamp to avoid the water

moving through the existing drainage structures and being released into the

Blind River, which would not benefit the swamp. Alternate measures and

approaches were identified, included conveyance channels (canals) and

conveyance conduits. The distribution was a critical component in each

alternative due to the many existing distinct hydrologic units within the

Study Area that are separated by existing channels. These channels have

isolated the hydrology of the individual drainage units; therefore, the

hydroperiod of each unit must be addressed separately.

Separate Distribution System: A measure was developed to keep the

freshwater conveyance separate from the existing drainage systems. The

initial concept was to provide the distribution system, consisting of either

canals or underground conduits, to transport the freshwater to the upstream

ends of sub-basins (hydrologic units), where it would be released. The

freshwater would then flow through the swamp uniformly and slowly drain to

the existing natural and man-made drainage channels. Additional earthwork

would be necessary to rectify man-made disturbances to the terrain and to

direct overland flow to desired routes and locations as discussed under the

section for Water Management in the swamp. Outlet controls might be

required to prevent channelization and to control the hydroperiod in the

swamp.

Transmission (Transfer) System: The transmission or transfer system

included the facilities necessary to transfer the freshwater from the diversion

point and deliver it to the distribution system at the edge of the swamp.

Alternate measures were identified and include a trapezoidal earthen

channel, a trapezoidal concrete-lined channel, underground conduits, and

existing natural and man-made drainage systems. The transfer system

would be designed for the range of flows expected to be diverted to the

swamp, including the maximum flow.

Diversion System: The diversion for the Blind River project would be

located on the east bank of the Mississippi River at a point with available

alignments into the Maurepas Swamp.

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Diversion Point: Seven potential diversion point locations were identified.

In addition to a single diversion point, multiple diversion points were

considered. There are several factors that would be considered in selecting

the diversion point in addition to the cost of transferring the water from the

diversion point to the swamp. The location on the river may affect the way

the diversion receives sediment due to the sediment load variations related to

bends and depth in the Mississippi River. The upstream diversion points

would allow for greater areas of the swamp to be served without additional

pumping

Water Quality Management:

o The swamp has specific restoration needs to promote revitalized

growth, including freshwater, suspended sediment, and nutrients in

the water.

o After it discharges out of the swamp, diverted water can directly

influence the Blind River (through and downstream of the swamp),

existing man-made drainage channels in and adjacent to the swamp,

Lake Maurepas, Lake Pontchartrain, and other water bodies.

Measures would be required to both avoid negative impacts in the

downstream systems, and to improve water quality for restoration

purposes. Measures identified include intake elevation control,

construction of a sedimentation basin to remove coarse sediments,

treatment facilities such as wet detention treatment basins and

wetland treatment to remove nutrients, aeration to add dissolved

oxygen either mechanically or passively, and a salinity barrier in Blind

River to prevent saltwater intrusion into the swamp.

Sediment Management: The existing ground surface in the swamp has

had a net loss of elevation relative to sea level due to ground subsidence

trends and sea level rise. Several measures were identified to introduce

sediment directly into the swamp.

Nonstructural Management Measures (Activities)



o

Water Quality Management:

Extended diversion duration to freshen Blind River. The

anticipated diversion period would be in the spring. During the dry

season, the Blind River becomes stagnant due to lack of local rainfall

and runoff. The diversion period could be extended into the dry

seasons to freshen the Blind River and downstream water courses.

This management measure would require a corresponding measure at

the diversion point, such as pumps, to allow diversion during low water

levels in the Mississippi River.

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o Extended diversion duration to counter salinity intrusion. The

Study Area is subject to high levels of salinity backing up from the

Gulf of Mexico due to storm events. These include extended droughts

and tropical storm surges. Providing capabilities for extended

diversion periods could assist in flushing out the system after the

salinity intrusion events.

Vegetation Management:

o Plant seedlings in targeted areas. This could be a one-time planting or

routine plantings in different areas over the design life of the project.

Measures to assist in bald cypress and tupelo

regeneration and to protect against loss of seedlings and saplings, include the

following:

o Identify areas and control the water levels to mimic the natural wet -

dry cycle.

o Control herbivore grazing of the seedlings with fences or other means.

Recreational Access and Enhancements: The swamp and the existing

WMA is a public recreational area. A diversion would enhance nutrient

assimilation and thereby improve fish and wildlife habitat which would

enhance recreational activities. Opportunities might exist to improve access

and care must be taken to maintain existing uses.

There were a total of 75 management features and 24 management activities

included in the initial screening. As an initial step, the screened list of

management measures was evaluated based on benefits, constraints, and cost

effectiveness. Based on that initial screening, 48 features and 3 activities were

retained for further analysis.

5.4.3 Preliminary Alternative Plans

The retained management measures were grouped into a preliminary array of 12

alternatives and the No Action Alternative for further evaluation to achieve the

overall project goals and objectives. The 12 alternatives were formulated to

consider different options for the diversion point, different diversion methods, the

transmission system, the distribution system, and the benefit area. These 12

alternatives were first evaluated and screened based on the diversion locations, flow

rates, and the diversion method.

Analysis of Diversion Locations: Diversion location was an important factor in

the benefits associated with each alternative. Seven individual diversion locations

and four combinations of dual diversion location measures, for a total of 11, were

initially identified. Preliminary conclusions were that a diversion near Romeville is

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a hydraulically efficient1

Table 5-6

location to provide freshwater, nutrients, and sediments to

the benefit area south of the Blind River; a diversion near the Sunshine Bridge is a

hydraulically efficient location to provide freshwater, nutrients, and sediments to

the benefit area north of the Blind River; and that diversions at both locations could

provide freshwater, nutrients, and sediments to the entire benefit area. Specific

diversion locations considered are described in .

Table 5-6: Diversion Locations Not Carried Forward

Vicinity of Romeville

Belmont Screened out. May impact three historic mounds, least advantageous

hydraulically.

Convent Screened out. Long route; more costly than Romeville without additional

advantage.

Nita Crevasse Screened out. Higher wetland impacts than Romeville with essentially the

same output. This site also has some difficult routing issues through

existing industrial facilities.

Romeville Retained for further analysis

Nucor Screened out. Would seriously interfere with Nucor’s future development

of the property, does not serve the total 35-mile Study Area and for the

area it can serve it is at least as expensive as the Romeville alignment and

does not provide any greater benefit.

Vicinity of Sunshine Bridge

Ancient Domain Screened out. Grain elevator currently is under construction at this

location.

South Bridge Retained for further analysis.

Stein Screened out. Impacts a barge fleeting area and alignment is too narrow.

South of Motiva There are significant HTRW problems associated with the Motiva

Motiva

Refinery

property.

Screened out. Significant HTRW problems are associated with the Motiva

North Bridge

Refinery property.

Screened out. Discharges to Conway Canal, which has insufficient

capacity to receive discharged flows and would be very expensive due to

long transmission channel and need to cross I-10 compared to the South

Bridge alignment.

Note: HTRW = hazardous, toxic, and radioactive waste

Analysis of Diversion Flow Rates: Two separate analyses were conducted to

determine the optimal size for the diversion. The project was authorized by WRDA

2007 as a small diversion with a diversion rate of ranging from 1,000-5,000 cfs. As

part of the planning process, the public expressed interest in higher diversion rates.

Accordingly, diversion rates up to 25,000 cfs were considered as part of the plan

formulation process.

1 The term hydraulically efficient means that the level of the river and the distance between the river and the swamp are

matched so the diversion water can be delivered with a high starting head (upstream on the Mississippi) and minimize

friction loses (shorten the transmission distance) to the swamp so the application water head is as high as possible.

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In the first step to evaluate and screen diversion flow rates, rates of 10,000 and

25,000 cfs were analyzed. The results of this analysis concluded the following:

Flows in excess of 5,000 cfs would be difficult to control without major

modifications to the drainage channels and possible alterations to the Blind

River.

The Mississippi River nutrient loading at these flow rates would exceed the

assimilation capacity of the swamp by factors of 20 to 50. As a result, high

levels of nutrients would pass to the Blind River and Lake Maurepas.

Flow rates higher than the 5,000 cfs currently authorized for this study

would not improve the objectives of the study and may cause additional

problems with soil erosion and nutrient loading downstream of the

distribution area. Higher flows would make it difficult to adjust hydroperiods

as necessary to facilitate tree regeneration.

Based on this analysis, diversions with flow rates greater than 5,000 cfs were

eliminated from further consideration.

As a second step to the evaluation diversion flow rates less than 5,000 cfs were

analyzed. Flow rates less than 5,000 cfs were modeled to determine the

hydroperiod response. Analysis determined a flow range of between 1,500 and

3,000 cfs is needed to meet swamp restoration goals and provide backflow reduction

from Lake Maurepas. The system responds to diversions between 1,500 and 3,000

cfs with the response steepening at 1,500 cfs and then starting to flatten out at

3,000 cfs. The 1,500 cfs flow range is the minimum amount of flow needed to begin

to prevent saline backflow and inundation from Lake Maurepas but has a limited

benefit area. The 3,000 cfs range is the point above which further positive changes

in most areas begin to diminish or stop; thus, alternatives over this range were

removed from consideration. Additional detail regarding the analysis is available in

the FS/SEIS (Volume IV).

Analysis of Diversion Methods: Diversions both by siphons over the Mississippi

River Levee and gated culverts through the Mississippi River Levee were

considered. An analysis of construction costs indicated that siphons are more cost

effective for flow rates below 1,000 cfs and gated culvert systems are more cost

effective for flow rates greater than 1,000 cfs. Accordingly, siphons are used as the

diversion method for flows less than 1,000 cfs and gated culvert systems are used

for flows greater than 1,000 cfs.

Analysis of the diversion location, flow rates, and methods allowed for the screening

of the 12 preliminary alternatives. The remaining alternatives were further refined

to the following eight intermediate alternatives (designated as No Action

Alternative and Alternatives 1 through 6 and 4B). These eight alternatives,

identified for further consideration, were subjected to a more detailed analysis and

screened to determine the final array of alternatives.

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No Action Alternative

Alternative 1 - 1,500 cfs Romeville Diversion (Siphons)

Alternative 2 - 3,000 cfs Romeville Diversion (Gated Culvert System)

Alternative 3 - 1,500 cfs South Bridge Diversion (Siphons)

Alternative 4 - 3,000 cfs South Bridge Diversion (Gated Culvert System)

Alternative 4B - 3,000 cfs Diversion at South Bridge with split flows (Gated

Culvert System)

Alternative 5 - 1,500 cfs diversion split equally between Romeville & South

Bridge (Siphons)

Alternative 6 - 3,000 cfs diversion split equally between Romeville & South

Bridge (Siphons)

An additional analysis of the availability of water from the Mississippi River

indicated that stage conditions could diminish the diversion capacity during certain

months (generally August - November), based on total head differential across the

swamp system. This, in turn, would effectively reduce the total average capacity of

each alternative. For the 1,500 cfs alternatives, this was a concern, since analyses

suggested that 1,500 cfs was at the lower end of capacities capable of providing

hydrologic effects. The 1,500 cfs alternatives were determined not to be reliably

effective in substantially contributing to the planning objectives and addressing

Study Area problems and opportunities (Table 5-7). Accordingly, Alternatives 1, 3,

and 5 (1,500 cfs) were removed from considered.

Table 5-7: Contribution of 1,500 cfs Diversion Alternatives to the

Objectives

Objective Contribution to Objectives

Promote water distribution in the swamp Effective when stages in Lake

Maurepas were lower than in the

swamp. Ineffective in providing

enough freshwater to the swamp when

Lake Maurepas tailwater elevations

were higher than the swamp.

to increase

the area of freshwater inundation for low to average flood

events by 10 to 25% from existing conditions to increase

swamp productivity and wetland assimilation.

Facilitate swamp building, at a rate greater than

swamp loss due to subsidence and sea level rise, by

increasing swamp productivity, as described above and by

increasing sediment input by up to 1,000 g/m2

Ineffective because the amount of flow

would affect a limited benefit area. In

addition, there would be limited

effectiveness when Lake Maurepas

stages are high and not enough water

available when Mississippi River

stages are low.

/yr in order

to decrease the annual subsidence rate 50% to 100% in the

swamp.

Establish hydroperiod fluctuation in the swamp Ineffective because the amount of flow

would affect a limited benefit area. In

addition there would be limited

effectiveness when Lake Maurepas

stages are high and not enough water

available when Mississippi River

stages were low.

to

improve bald cypress and tupelo productivity and their

seeding germination and survival by decreasing flood

duration in the swamp by 10% to 25% for high flood

events, increasing the length of dry periods in the swamp

(no standing water) by 10% to 25%, and by increasing the

number of bald cypress and tupelo saplings per acre by

25% to 50% from existing conditions.

Improve fish and wildlife habitat in the swamp and Effective when stages in Lake

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in Blind River Maurepas were lower than in the

swamp. Ineffective in providing

enough freshwater to the swamp when

Lake Maurepas tailwater elevations

were higher than the swamp.

by increasing the existing WVA habitat

suitability index in the swamp by 10% to 25% 5 years after

project implementation and by a 5% to 10% increase in the

average dissolved oxygen in Blind River from existing

conditions.

Each of the alternatives was also analyzed with respect to features (such as berm

gaps and control structures) that would maximize the flexibility of operations. More

detailed operational analysis was completed for the final array of alternatives

discussed in the Section 5.4.4 and is presented in Volume IV Appendix L2.10.

5.4.4 Identification of the Final Array of Alternatives

Based on the analysis discussed above, the 3,000 cfs diversion was determined to be

optimal to prevent saline backflow and inundation from Lake Maurepas and

achieve the overall goal of reversing the trend of degradation in the swamp. The

following five alternatives were retained for further consideration in the Final

Array:

No Action Alternative: The No Action Alternative (future without project

condition) would lead to the eventual degradation of the swamp. Without

adequate flow of water through the swamp and with issues relating to

subsidence, and RSLR as well as ponding and drainage from pipeline

channels, the hydroperiod of the swamp would not be conducive to the health

and regeneration of several native tree species, including bald cypress and

water tupelo.

Alternative 2 - 3,000 cfs Diversion at Romeville (Gated Culvert System): The

diversion would deliver freshwater, sediment, and nutrients to the swamp at

strategic times during the year. This alternative adds a gated culvert system

and transfer canal along the Romeville alignment, restores and improves the

160 existing berm cuts, adds 30 new 500-foot-wide berm cuts, builds up to six

control structures at strategic locations in the swamp, and adds three new

culverts under U.S. Highway 61.

Alternative 4 - 3,000 cfs Diversion at South Bridge (Gated Culvert System):

The diversion would deliver freshwater, sediment, and nutrients to the

swamp at strategic times during the year. This alternative adds a gated

culvert system and transfer canal along the Cox alignment south of the U.S.

Highway 70 Bridge, restores and improves the 160 existing berm cuts, adds

30 new 500-foot-wide berm cuts, builds up to six control structures at

strategic locations in the swamp, and adds three new culverts under U.S.

HWY 61.

Alternative 4B - 3,000 cfs Diversion at South Bridge with split flows (Gated

Culvert System): The diversion would deliver freshwater, sediment, and

nutrients to the swamp at strategic times during the year. This alternative

adds a gated culvert system and transfer canal along the Cox alignment

south of the U.S. Highway 70 Bridge, restores and improves the 160 existing

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berm cuts, adds 30 new 500-foot wide berm cuts, builds up to six control

structures at strategic locations in the swamp, and adds three new culverts

under U.S. Highway 61. This alternative includes a modification to the

distribution of the diversion provided by Alternative 4 by sending 1,500 cfs to

the south through the St. James Parish Canal in order to achieve a similar

distribution to Alternative 6.

Alternative 6 - Two 1500 cfs Diversions at Romeville and South Bridge

(Siphons): The diversion will deliver freshwater, sediment, and nutrients to

the swamp at strategic times during the year. This alternative adds a gated

culvert system, a transfer canal along the Romeville alignment, and a gated

culvert system and transfer canals along the Cox alignment south of the U.S.

Highway 70 Bridge, restores and improves the 160 existing berm cuts, adds

30 new 500-foot wide berm cuts, builds up to six control structures at

strategic locations in the swamp and adds three new culverts under U.S.

Highway 61.

5.4.5 Environmental Consequences*

An analysis was conducted on the potential environmental consequences of

implementing alternative plans to reverse the trend of degradation in the

southeastern portion of the Maurepas Swamp. The analysis compares the No

Action Alternative to the final array of alternatives retained for detailed analysis.

The No Action Alternative is considered to be the same as the future without project

condition and analyzes the future conditions of the resource over a 50-year period of

analysis from 2012-2062.

A brief summary of that analysis is presented here to evaluate the No Action

Alternative against the alternative proposed in the final array. The full analysis of

all environmental consequences for each alternative is included in Volume IV,

Section 5.

No Action Alternative: Without Federal action, the swamp habitat surrounding

the LCA Small Diversion at Convent/Blind River will continue to degrade. Due to

increased flood duration, stage, and salinity would persist, which would result in

approximately 11,230 acres of forested swamp converting to fresh marsh or open

water. The direct impacts of this action would be the continued impoundment of

swamp water within the Study Area; a reduction in tree canopy, water quality,

hydrologic connectivity; and a transition toward marsh and saline-tolerant

vegetation. Indirect impacts resulting from the continued habitat degradation

would be the eventual decline of wildlife, fishery, and vegetative resources.

Cumulative impacts would be the continual conversion of swamp habitat to

freshwater marsh and open water habitat, along with the additive results of this

habitat degradation when combined with other Federal, state, and local actions.

Some impacts would be reduced by the Small Diversion at Hope Canal, but that

diversion would be insufficient to prevent negative consequences in the Study Area.

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Alternative 2 (Recommended Plan): Implementation of Alternative 2 would

reverse the conversion of swamp habitat to open water and would provide 6,421

average habitat units annually in the Study Area and improve a total of 21,369

acres of bald cypress-tupelo swamp. Both direct and indirect impacts are associated

with this alternative.

Positive direct impacts would include increased freshwater flow into the swamp

when river flows are high as well increased flows out of the swamp when water

levels are low. Increased freshwater will improve water quality within the areas of

impact and reduce salinity levels. Additional sediment delivered with the

freshwater would increase accretion and prevent conversion of swamp to marsh and

open water. Negative direct impacts will include loss of a small area of forested

swamp and agricultural land due to construction. Potential direct impacts to

endangered species would be entrainment of pallid sturgeon in the diversion

structure and displacement of manatees during construction. Cumulative impacts

would be the improvement of swamp habitat, along with the additive results of this

habitat improvement when combined with other Federal, state, and local actions.

Potential cumulative impacts on water quality from this and other restoration

projects nearby will be further addressed during the PED phase through analysis of

data generated by additional piezometers and gauges recently installed in the Study

Area,

Alternative 4: Implementation of Alternative 4 would also reverse the conversion

of swamp habitat to open water and would provide 6,124 average habitat units

annually in the Study Area and improve a total of 21,206 acres of bald cypresstupelo swamp.

Cumulative impacts would be similar to Alternative 2 with potentially more adverse

construction impacts initially due to the South Bridge diversion, which would

displace three houses, additional loss of forested swamp would occur in construction

of the longer South Bridge transmission canal, and there is potential for

underground storage tank issues along the South Bridge diversion. Other

cumulative impacts would be similar to Alternative 2.

Alternative 4B: Implementation of Alternative 4B would reverse the conversion of

swamp habitat to open water and would provide 7,114 average habitat units

annually in the Study Area and improve a total of 21,243 acres of bald cypresstupelo swamp. Other cumulative impacts would be similar to Alternative 2.

Alternative 6: Implementation of Alternative 6 would reverse the conversion of

swamp habitat to open water and would provide 7,103 average habitat units

annually in the Study Area and improve a total of 21,243 acres of bald cypresstupelo swamp. Cumulative impacts would be similar to Alternative 2; however,

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there would be a slightly larger loss of land currently in agricultural production

associated with the two diversion routes. Other cumulative impacts would be

similar to Alternative 2.

The study looked at diversion flows greater than 3,000 cfs and found that benefits to

the swamp were increased only marginally and actually delivered more nutrients to

the swamp in the Study Area than the swamp could assimilate; it is unlikely that

this condition would change with monitoring. However, without structural

modification to the diversion structure, increased flow (greater than 3,000 cfs) could

be achieved during high river stages; depending on how much flow would be

increased, it may become necessary to increase the size of the transmission channel,

and the current design includes enough right-of-way to allow for an increased

transmission channel with reduced freeboard.

5.4.6 Comparison of Alternative Plans

The four alternatives in the final array and the no-action were evaluated and

compared based on benefits, costs, and impacts to significant resources. The first

cost and annual costs for the final four alternatives are shown in Table 5-8.

Alternative 2 is the least expensive with a first cost of about $102 million;

Alternative 6 is the most expensive at over $155.6 million. Alternatives 4 and 4B

are slightly less expensive than Alternative 6 at $152.2 million and $146.9 million,

respectively. A cost summary comparison of the final array of alternatives is

provided in Table 5-8.

Table 5-8: Cost of Final Array Alternatives

Item

Cost (millions of dollars)

Alt. 2

a,b

Alt. 4 Alt. 4B Alt 6

Construction subtotal $73.5 $110.7 $106.8 $111.2

Engineering & design $3.7 $5.5 $5.3 $5.6

Supervision & administration $2.2 $3.3 $3.2 $3.3

Real estate $2.2 $2.2 $2.2 $4.4

Subtotal $81.6 $121.8 $117.5 $124.5

Contingencies @ 25% $20.4 $30.4 $29.4 $31.1

Total Cost $102.0 $152.2 $146.9 $155.6

Annualized first cost $5.06 $7.55 $7.28 $7.72

Annual O&M costs $0.59 $0.59 $0.67 $0.74

Total annual cost $5.65 $8.14 $7.95 $8.46

Life cycle cost $114.0 $164.2 $160.4 $170.6

a Costs for adaptive management are not included in this table.

b Preliminary costs were developed for planning purposes only. Cost estimate is not the fully funded fully

funded cost.

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The WVA model is undergoing model certification in accordance with EC 1105-2-

407. The model has undergone external review, and the WVA revision

documentation and spreadsheets have been submitted to the ECO-PCX. The ECOPCX 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

this project can be found in Appendix K of Volume IV.

Table 5-9 summarizes the results of the WVA analysis and of the IWR Planning

Suite analysis. The WVA model and benefit calculations are described further in

Volume IV and Appendix K. Alternative 6 provided the greatest number of

environmental benefits in terms of AAHUs estimated using the WVA process.

Alternative 2 provided over 90% of the benefits for about 67% of the cost of

Alternative 6. The cost per AAHU was much lower for Alternative 2 than for the

other alternatives, and the incremental cost per habitat unit in going from

Alternative 2 to Alternative 4B and/or Alternative 6 was quite high (Table 5-9).

Alternative 2 would also impact the smallest number of wetland acres.

Accordingly, Alternative 2 is the alternative that reasonably maximizes ecosystem

restoration benefits compared to costs and is designated as the NER plan.

Additional detail on the comparison of alternatives can be found in Volume IV.

Table 5-9: Summary of WVA Analysis AAHUs, IWR Planning Benefits, and

Wetland Impacts for Final Array Alternatives

Alt. 2 Alt. 4B Alt. 6

AAHUs 6,421 7,103 7,114

Cost ($1,000s)a $5,646 $7,954 $8,455

Cost effective Yes Yes No

Best Buy Yes Yes Yes

Cost/HU $879 $1,120 $1,189

Incremental cost/AAHUs ($1000s) $0.88 $3.39 $45.53

Wetland acres impactedb 53 306 287

a Preliminary costs were developed for planning purposes only. Cost estimate is not the fully funded

cost. Costs were annualized using a discount rate of 4 3/8% over a 50-year period

b Wetlands impacted during project construction.

5.4.7 National Ecosystem Restoration Plan

The NER plan reasonably maximizes ecosystem restoration benefits compared to

costs, consistent with the Federal objective. Based on the comparison of

alternatives above, Alternative 2, a 3,000 cfs diversion at Romeville is designated as

the NER plan.

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The non-Federal sponsor supports the NER plan; therefore, no separate LPP is

identified. The NER plan is also identified as the EPP since it maximizes the

environmental benefit.

5.4.8 Plan Selection – Recommended Plan

The NER plan, Alternative 2, a 3,000 cfs diversion at Romeville was also selected as

the recommended plan. Alternative 2 best addressed the screening criteria; would

accomplish the planning objectives and goals; is consistent with the EOPs; and

would contribute to reversing the trend of deterioration in the southeast part of the

Maurepas Swamp by generating 6,421 AAHUs. The recommended plan would

improve a total of 21,369 acres (8,648 ha) of bald cypress-tupelo swamp that are in

deterioration. The recommended plan would improve 3,295 acres (1,333 ha) of bald

cypress-tupelo swamp that would become marsh in 20 to 30 years without project

implementation, 7,934 acres (3,211 ha) of bald cypress-tupelo swamp that would

become marsh in 30 to 50 years without project implementation, and 10,140 acres

(4,104 ha) of bald cypress-tupelo swamp that would become marsh in greater than

50 years without project implementation. The recommended plan is shown in

Figure 5-6.

The selected recommended plan is within the scope and cost of the current

authorization. The fully funded project cost estimate, for the recommended plan is

$123,140,000 (Table 5-10 for details) which is under the cost authorized by WRDA

2007 Table 5-10.

Table 5-10: Recommended Plan Cost

ITEM TOTAL

(Rounded)

LERRDs to be acquired $4,040,000

Facility/utility relocation $14,060,000

Highway modifications/relocations $1,820,000

Railroad modifications/relocations $2,090,000

Subtotal real estate $22,010,000

Construction $77,610,000

PED $7,750,000

Construction management $9,150,000

Subtotal construction $94,510,000

Adaptive management $6,620,000

Subtotal 65/35 cost share $123,140,000

Adjustment for 65/35 Cost Share

Fully funded costa $123,140,000

Annual O&M $462,000

Annual repairs, replacement and renewal $92,000

Annual maintenance dredging $2,200,000

a For the purposes of applying the cost index to the WRDA authorized cost, each

project was adjusted for inflation from the October 2006 price levels through the

projected midpoint of project construction.

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Table 5-11: Maximum Cost Including Inflation through Construction

Authorized cost in WRDA 2007 Title VII,

Section 7006 (e)(3)(A): $88,000,000

Cost index used

EM 1110-2-1304 (Revised 31 Mar 2010)

a CWBS- Features Codes 15 Floodway

Control & Diversion Structure

Cost index ratio

1Q FY07 to 2Q FY14 1.14

Current project cost estimate

(Inflation applied from 10/2006 to 1/2014) $100,729,295 b

20% of authorized cost $17,600,000

Monitoring & adaptive management

(per WRDA 2007 Section 2039)

$6,620,000- $717,000 c = $5,903,000

Maximum cost limited by Section 902 $100,729,295+ $17,600,000+ $5,903,000

= $124,230,000

Recommended plan Cost $123,140,000

Note: Bolded numbers are rounded a The cost index applied to the current estimate is derived from: EM 1110-2-1304, 31 Mar 10, CWCCIS.

b For the purposes of applying the cost index to the WRDA authorized cost, each project was adjusted for inflation from the

October 2006 price levels through the projected midpoint of project construction.

c This is the cost of any modifications required by law. This is derived from the 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.

Significance of Outputs: The recommended plan would restore the southeastern

Maurepas Swamp to ensure its ability to provide hydrologic and habitat form and

function for the 50-year period of analysis. Hydroperiods, water quality, and interior

marsh habitat for fish and wildlife species would be restored, mimicking as closely

as possible the conditions that occurred naturally in the area. The alternatives

were designed to work with the natural, fluid, soft environment of coastal

Louisiana. Without this project, southeastern Maurepas Swamp will continue to

deteriorate, with eventual conversion to open water; the bald cypress-tupelo habitat

characteristic of the swamp would be lost.

The Maurepas Swamp is a significant ecosystem within the Pontchartrain Basin in

southern Louisiana. The ecosystem outputs from the Maurepas Swamp play an

important role in the overall health of the southern Louisiana ecosystem. The

outputs are institutionally recognized. The Study Area is almost wholly located

within the Maurepas WMA, and the Blind River is a state-designated Scenic River.

This project is listed in the Louisiana State Master Plan and is designated as a

critical near-term feature in the LCA Report (USACE, 2004a). There is public

support in Louisiana for this project, with specific emphasis on beginning

construction as soon as possible. The area is utilized for boating, fishing, hunting,

and bird watching. Commercial and recreational fishing are culturally significant

to many south Louisiana residents.

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Figure 5-6 : LCA Small Diversion at Convent/Blind River Recommended Plan (Alternative 2)

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The recommended plan outputs are also technically recognized:

Scarcity: Louisiana’s coastline represents 90% of the wetlands in the

contiguous United States and is disappearing at an alarming rate. This

unique and scarce habitat has high fish and wildlife values.

Representativeness: The project footprint is uninhabited. The recommended

plan would restore the hydrologic and habitat of the swamp.

Status and trends: The Study Area is declining and imperiled. While the

project cannot stop the natural processes of sea level rise, subsidence, and

storm caused erosion, the project can greatly slow down the disappearance of

these landforms and supported habitats by increasing the amount of

freshwater, nutrients, and sediment in the swamp system.

Connectivity: The Maurepas Swamp serves as a buffer between open water

areas of Lake Maurepas and Lake Pontchartrain and developed areas along

I-10 / Airline Highway, and it is one of the largest continuous tracts of bald

cypress-tupelo on the coast, supporting fish and wildlife habitats. The

swamp is also a valuable stopover habitat for migratory birds.

Limiting habitat: Much of the southeastern Maurepas Swamp is considered

important habitat for nesting bald eagles and other migratory birds. The

swamp provides necessary habitat for a variety of small mammals including

deer, alligators, and fish species.

5.4.8.1 Components

Alternative 2 has six major components:

Diversion Structure:

Three 10-foot by 10-foot multi-cell cast-in-place reinforced concrete box

culverts under the east levee and LA 44

The diversion culvert facility would divert freshwater from

the Mississippi River, transfer it under the east levee through a box culvert, and

discharge it into the transmission canal. The primary hydraulic elements of the

diversion culvert facility are as follows:

Three 10-foot by 10-foot cast iron sluice gates with motor operators on the

culvert inlets

Trash racks near the culvert inlet

Inlet canal across the batture from the Mississippi River to the culvert inlet

Erosion protection would be provided as needed at locations with higher flow

velocities and turbulence, such as at the Mississippi River bank, in the inlet canal

entrance, at the box culvert entrance, and at the culvert outlet.

Transmission Canal: The transmission canal would transfer diverted water

approximately 3 miles from the diversion culvert facility to an existing drainage

channel at the perimeter of the swamp. The transmission canal would be designed

with a 25% factor of safety for the flow rate to avoid overtopping the berms. The

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canal would be an earthen trapezoidal channel section, with a 155-foot wide bottom,

4:1 (horizontal:vertical) side slopes, and a depth of approximately 12 ft, including a

2-foot freeboard. The top width would be approximately 250 ft. The hydraulic

grade line would be above natural ground for most of the route. Therefore,

embankments or berms with 12-foot wide tops would be constructed on both sides of

the canal.

The transmission canal alignment crosses the Canadian National Railroad (CN RR)

and LA 3125, a local highway. Both crossings would consist of eight 12-foot by 8-

foot reinforced concrete box culverts across the full right-of-way.

Control Structures: The project would use the existing drainage channels at the

perimeter of the swamp to distribute the diverted flow throughout and into the

swamp. The hydraulic grade line, or water surface elevation, would need to be

raised above the existing levels and controlled to force the diverted water out of the

drainage channels into the swamp. Control structures would be installed at key

locations in the existing channels to perform this function. During PED, other

options on control structures would be considered. Final design of the control

structure should be coordinated with natural resource agencies to ensure the design

considers aspects of fish and wildlife conservation. Selection of the control

structures would have no effect on the ranking of alternatives or the level of benefit

derived from the project.

Berm Gaps: When the existing drainage channels were excavated in the swamp,

the material was cast to the side of the channel forming spoil banks. The sizes of

the spoil banks vary, with the top elevations ranging from elevation 4 to elevation

12 (NAVD 88). The spoil banks block flow circulation into and out of the swamp,

resulting in stagnant areas and poor water circulation in the hydrologic units. In

the current configuration, the spoil banks would continue to prevent the diverted

water from easily entering and flowing through the swamp. New 500-foot-wide

berm gaps would be excavated in the spoil banks to the elevation of the adjacent

swamp natural ground elevations. The spoil would be disposed of behind the

existing spoil banks and placed up to elevation 6 (NAVD 88) to provide additional

refuge areas for wildlife during flood events in the swamp.

Cross Culverts at the Highway 61 Corridor: The hydrodynamic modeling of

the swamp indicated that the Kansas City Southern Railroad (KCS RR) and the

U.S. Highway 61 embankments disrupt the natural flow and circulation of water

through the swamp. As a result, hydrologic units east and west of the KCS

RR/Highway 61 corridor having stagnant water, poor drainage, and lack of sources

of freshwater input. Culvert crossings would be added under the KCS RR and U.S.

Highway 61 at four locations. Each installation would consist of three 3-foot by 4-

foot reinforced concrete box culverts. Earthen channels (large ditches) would be

excavated across the 500-foot space between the KCS RR and U.S. Highway 61 to

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interconnect the drainage capacity at the railroad with the new culverts at U.S.

Highway 61.

Instrumentation: Instrumentation would be required to monitor and control the

diversion flow rate and the water surface elevations in the diversion, transmission,

and distribution system in the swamp. Real-time data would be required from the

system components to allow the operator to control and adjust the system flow rates

from the diversion structure. Satellite communication would be provided at each

control structure to communicate to the control building. Typically, flow rates and

water levels would be measured and the feedback data would be used to adjust gate

positions to control the desired parameters at the diversion culvert and the control

structures. Additional instrumentation may be required as part of monitoring and

adaptive management.

5.4.8.2 Design, Environmental, and Construction Considerations

The purpose of the project is to divert freshwater into the Maurepas Swamp to

freshen the swamp, provide nutrients and sediment, and counter potential backflow

of water from Lake Maurepas containing elevated levels of salinity. The hydraulic,

hydrodynamic, and environmental analyses of the swamp indicated that reintroducing freshwater from the Mississippi River back into the swamp and

correcting the internal drainage and circulation problems could revitalize the

swamp. The hydraulic and the hydrodynamic analyses identified means to divert

the freshwater from the Mississippi River, deliver it to the swamp, and distribute it

within the swamp to accomplish the environmental goals. The hydrodynamic

analysis identified specific actions necessary to improve the distribution and

circulation of the water into and within the swamp.

The major project components are primarily hydraulic conveyance and control

structures designed to divert freshwater from the Mississippi River, transfer it to

the Maurepas Swamp, and distribute and direct the diverted water into and

through the swamp. Typically, the hydraulic designs were established through

iterative processes that included the hydraulic needs, the hydraulic grade line of the

overall system, component sizes, and costs. In some cases, alternative management

measures were evaluated, such as diversion culverts versus diversion siphons and

sluice gates versus crest gates at the control structures.

The project would be constructed in two very different settings - upland areas where

normal construction techniques apply and the swamp where special techniques and

approaches would be required. Construction considerations include existing site

conditions, access, construction techniques, temporary construction facilities,

detours for transportation facilities, construction sequences, dewatering and surface

water control, storm water pollution prevention plans, and balancing earthwork

volumes. All of which would impact the design and the cost estimates of the

components. Based on HTRW research in the study area the potential to encounter

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HTRW is low in most of the study area, nevertheless if any solid or hazardous

wastes, or soils and/or groundwater contaminate with hazardous constituents are

encountered during the project LDEQ will be notified.

5.4.8.3 Real Estate Requirements

Real estate requirements for this alternative would include both temporary and

permanent construction. Permanent real estate requirements exist for the

following:

Transmission channel - The channel would run from the Mississippi River

to the St. James Parish drainage canal. A 400-foot-wide (122 m) easement

that is 15,500 ft (4,724 m) long would be required; total area of the easement

would be approximately 145 aces (59 ha).

Diversion structure - The diversion structure would be co-located in the

easement for the flood-control levee and would require a dual-use easement.

Control structures and berm gap - The control structures and berm gap

would require the use of Louisiana state land in the WMA. Surveys and

construction agreements would be required from the LDWF, but no easement

costs are anticipated.

The project would require three temporary real estate easements: construction

detours for LA 44, the CN RR, and LA 3125. A temporary real estate requirement

would exist for the 100-foot (30 m) temporary offset detour for LA 44, the CN RR,

and LA 3125. The area for the temporary easements during construction of crossing

culverts and bridges is estimated at 10 acres (4 ha).

Other areas of consideration include:

Dual use easement for the diversion structure at the levee where the

diversion would be co-located in the easement for the flood control levee.

Use of Louisiana state land in the WMA for the control structures and berm

gap construction.

Permits to construct the bridges and culvert on state highway right-of-way.

5.4.8.4 Operation and Maintenance Considerations

O&M considerations have to be addressed on the diversion structures, transmission

canal, berm gaps, control structures, and U.S. Highway 61 cross-culverts.

Transmission Canal:

Operations - The transmission canal would be self-operating with

monitoring of flow and stage transmitted to the control building for

processing. An automatic diversion gate closure would be initiated if the

freeboard in the channel is less than 1.0. The sediment level in the channel

would be periodically monitored, and the canal crossing would be inspected at

annual intervals.

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Maintenance - The transmission channel right-of-way would be mowed and

maintained, and the sediment deposited in the channel would be monitored

and removed by dredging annually. Any erosion of internal or external slopes

would be repaired as required.

Diversion Structure:

Operations - An operator would set the flow rate into the swamp and Blind

River. The gates would be automatically controlled to maintain the flow

based on river stage and downstream water surface conditions.

Maintenance - Maintenance would include the computerized control and

monitoring system, the diversion gates and inspection and cleaning of the

inlet trash grates. General maintenance of the control building and

landscaping would also be required. All dredging maintenance activities

would be coordinated with state and Federal agencies.

Control Structures:

Operations - The gates on the controls structures would be positioned to

provide flow through the swamp as required for flow, sediment, and nutrient

distribution. The gates would be lowered in the anticipation of heavy rain

events. Due to the slow drainage time for the channels, the gates would be

lowered 24 hours in advance of rain events greater than 1 inch.

Maintenance - The control structures would have hydraulically operated

gates with electric motors on the hydraulic pumps and generators providing

power to the motors. General maintenance of pumps, motors, and generators

would be required. The units would be inspected and maintained monthly.

Berm Gaps:

Operations - The berm gaps would have no operating features.

Maintenance - The gaps would need to be inspected twice each year, and

debris cleared from the gaps as required. Should the gaps silt in, there may

need to be limited dredging that would be accomplished when the drainage

channel dredging is accomplished.

U.S. Highway 61 Cross Culverts:

Operations - The culverts would have no operating features.

Maintenance - Culverts would be submerged and would need to be desilted

on an annual basis to assure that flow openings are maintained.

5.4.8.5 Monitoring Plan and Adaptive Management

5.4.8.5.1 Description of Monitoring Activity and Adaptive Management

A feasibility level monitoring and adaptive management plan has been developed

for the project (Volume IV, Appendix I). The monitoring and adaptive management

plan was developed to include a sufficient description of the proposed monitoring

and adaptive management activities to identify the nature of proposed adaptive

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management activities and to estimate the costs and duration of the monitoring and

adaptive management plan. The monitoring and adaptive management plan

identifies the restoration goals and objectives identified for the project; outlines

management actions that can be undertaken to achieve the project goals and

objectives; presents a conceptual ecological model that relates management actions

to desired project outcomes; and lists sources of uncertainty that recommend the

project for adaptive management. Monitoring, assessment, decision making, data

management are also addressed in the monitoring and adaptive management plan.

5.4.8.5.2 Performance Measures for Monitoring

The plan identifies performance measures along with desired outcomes and

monitoring designs in relation to specific project goals and objectives.

Objective 1- Promote water distribution in the southeast portion of Maurepas

Swamp to move stagnant water out of the system

Performance Measure: Area of swamp inundated with diverted water

during operational events.

Desired Outcome: Increase from pre-project conditions area of swamp

inundated for low flow to high flow events. Specific targets are:

Increase the area of freshwater inundation for low to average flood

events by 10% to 25%

Increase swamp productivity as measured by a 5% to 10% annual

increase in the diameter at breast height (dbh) of bald cypress and

tupelo

Decrease average total nitrogen in Blind River by 10% to 25%

Decrease average total phosphorous in Blind River by 10% to 25%

Increase average dissolved oxygen in Blind River by 5% to 10%

Monitoring Design: Synoptic hydrologic surveys, using salinity,

temperature, dissolved oxygen, conductivity, turbidity, pH, and velocity as

tracers, would be conducted during selected low flow and high flow

operational events to track distribution of freshwater.

Objective 2 - Facilitate swamp building, at a rate greater than swamp loss due to

subsidence and sea level rise, by increasing sediment input and swamp production

to maintain or increase elevation in the swamp.

Performance Measure 2a: Sediment accretion and elevation

Desired Outcome: Accretion rate equals or exceeds subsidence rate after 5

years. The specific target is to increase sediment input by up to 1,000

g/m2

Monitoring Design: Sediment erosion tables would serve as an elevation

benchmark and marker horizons or sediment traps would be used to assess

accretion.

/yr.

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Supporting Information Need: TSS would be collected to help understand

how sediment contributions through the diversion may enhance swamp

productivity and land building.

Performance Measure 2b: Swamp production and extent

Desired Outcome: Increase in basal area increment of bald cypress and

tupelo in the swamp from existing conditions, that is, existing conditions

defined from preconstruction measurements from Coastwide Reference

Monitoring System (CRMS)-Wetlands stations and Southeastern Louisiana

University historical monitoring

Monitoring Design: Diameter at breast height and overstory tree cover

would be measured to estimate production.

Performance Measure 2c: Annual sediment discharge

Desired Outcome: Deliver 86,480 million tons of sediment through the

Convent/Blind River diversion each year.

Monitoring Design: Hourly turbidity recorders would be deployed in the

outfall channel and at hydrologic sites and correlated to TSS to investigate

this measure.

Objective 3 - Establish hydroperiod fluctuation in the swamp to improve bald

cypress and tupelo productivity and their seed germination and survival, by

increasing the length of dry periods in the swamp.

Performance Measure 3a: Depth, duration, and frequency of flooding in

the swamp

Desired Outcome: A statistically significant decrease from pre-project

condition average flood durations (existing conditions defined from

preconstruction measurements from CRMS stations). The project would be

operated to facilitate dry periods. These dry periods should be targeted every

year if possible.

Desired Outcome: Maintain dry periods (moist soils) in the swamp for a

minimum 7 to 35 days during summer and early fall for seed germination,

and maintain water levels below seedling height to promote seedling

survival.

Monitoring Design: Hourly hydrologic recorders would be deployed to

investigate this measure.

Performance Measure 3b: Number of bald cypress and tupelo saplings

Desired Outcome: 25% increase in the number of bald cypress and tupelo

saplings per acre from pre-project conditions 5 years after project

implementation and 50%increase after 10 years. Performance of this measure

is dependent on achieving extended dry periods in the swamp. In addition

the following outcomes are desired:

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Decreased flood duration in the swamp by 10% to 25% for high flood

events

Increasing the length of dry periods in the swamp (no standing water)

by 10% to 25%

Increase the number of bald cypress and tupelo saplings per acre by

25% to 50%.

Monitoring Design: Understory vegetation (herbaceous, seedling and

sapling) would be measured to assess regeneration and changes in cover

classes.

Objective 4 - Improve fish and wildlife habitat in the swamp and in Blind River

Performance Measure: No applicable performance measure

Desired Outcome: Swamp production, hydroperiod, and water quality

measures would be used to assess this objective.

Monitoring Design: Fish and wildlife habitat is linked to the performance

measures associated with Objectives 1-3, focused on improving habitat.

Therefore, no specific monitoring is proposed for this objective.

Risk Endpoint: Water quality impairment in Blind River and Lake

Maurepas

Desired Outcome: Do not create or contribute to nitrate loading in Blind

River that would result in a Louisiana 303 (d) listing. If listed, a TMDL

assessment would be considered in coordination with LDEQ.

Monitoring Design: Nutrient sampling would be designed in coordination

with LDEQ, if needed.

5.4.8.5.3 Costs for Implementation of Monitoring and Adaptive Management

The costs associated with implementing the monitoring and adaptive management

plan were estimated based on currently available data and information developed

during plan formulation as part of the feasibility study. The costs estimated would

be refined in PED during the development of the detailed monitoring and adaptive

management plans.

The current total estimate for implementing the monitoring and adaptive

management programs is $6,620,000, based on October 2010 price levels. In

accordance with WRDA 2007 Section 2039, the monitoring costs presented in the

report are for the full allowable 10 year period and represent conservative and

comprehensive costs. Section 2039 guidance does allow for the monitoring to end

prior to the 10-year period if the Secretary determines that the success criteria have

been met. The costs presented in the report are for the full 10 year period but

monitoring may end prior to the 10 years. The monitoring plans and costs were

developed by the interagency LCA Adaptive Management Planning Team in

conjunction with stakeholders and have been determined to be a reasonable plan

and estimate for the recommended plan and are what is needed and necessary to be

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able to determine project success. Adaptive management costs include program

establishment and implementation over 10 years.

5.4.8.6 Effectiveness of Recommended Plan in Meeting Goals and Objectives

The recommended plan would meet the overall and the specific project objectives as

identified in Section 5.2. The diversion would bring nutrients, sediment, and water

to the swamp to increase productivity and accretion. The construction of new gaps

in berms, maintenance of existing gaps in the berms, and strategically placed

control structures in the major conveyance channels, along with the diversion,

would promote water distribution to increase productivity and accretion. The

operational flexibility provided in the recommended plan would allow establishment

of hydroperiod fluctuations in the swamp to improve seedling germination and

survival. Nutrient assimilation in the swamp from water diverted from the

Mississippi River would improve water quality and, thereby, the fish and wildlife

habitat in the swamp and in Blind River. These activities would reverse the trend

of deterioration of Maurepas Swamp and Blind River.

5.4.8.7 Effectiveness of Recommended Plan in Meeting Environmental

Operating Principles

The recommended plan is effective in meeting the EOPs. The recommended plan is

environmentally sustainable as it minimizes operational activities to the extent

possible while maintaining operational flexibility to restore a viable natural system.

The recommended plan was developed to reverse deterioration of the swamp and

Blind River by utilizing the natural swamp building and assimilation processes

balanced with appropriate management activities while minimizing environmental

consequences. The improvement of bald cypress-tupelo swamp provided by the

recommended plan would mitigate for the minimal unavoidable wetland impacts

resulting from project implementation. Monitoring and adaptive management of

this project would provide knowledge on how to effectively implement small

diversion projects to maintain and protect valuable swamp ecosystems. In addition,

the recommended plan was developed with the inclusion of important stakeholder

input.

5.4.8.8 Compensatory Mitigation Measures

Compensatory mitigation is not needed for this project. Wetland impacts were

avoided and minimized to the extent possible in the preliminary design of the

recommended plan. The recommended plan would impact 53 acres (21 ha) of

wetlands with construction of the diversion canal. The improvement of 21,369 acres

(8,648 ha) of bald cypress-tupelo swamp would compensate for the wetland impacts

resulting from construction.

5.4.9 Risk and Uncertainty

Hydrologic Uncertainties: The hydraulic and hydrologic modeling results

presented in the analysis have been developed with the best available information

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on historical hydrology, existing topography, sea level rise, subsidence, and

accretion; however, each of these factors, alone or in combination, is subject to

uncertainties. These hydrologic uncertainties would be reduced as additional data

are collected and additional modeling is conducted during future study design

phases. The potential uncertainties are discussed below:

Topography: All modeling has been completed using best available topographic

and bathymetric data in combination with available engineering plans to define

channel cross-sections, roadway culverts, and surface storage areas. The available

topographic data coupled with field reconnaissance provided sound definition of

major hydrologic and hydraulic features for use in the development models.

Future hydrology: The period of record used for extended analysis covered the

period from 1989 through 2004. During this period, it appears that extended dry

conditions that would support cypress germination and sapling survival occurred

only every 5 to 6 years. Analysis of this data set demonstrates that careful flow

management within the system can facilitate periodic hydrologic conditions that

would support tree regrowth, but favorable ecological factors would also need to be

present for this desired outcome. A more robust date set would further strengthen

this analysis and better determine the frequency at which conditions in the future

may support growth.

Relative Sea Level Rise: The basis for estimating RSLR and associated impacts

to the project are based on multiple components.

Eustatic sea level rise: USACE estimates for 50-year eustatic sea level rise

(without the relative impacts of subsidence or accretion) range from 0.28 to

2.00 ft. This is a very broad range, as it coincides generally with the

magnitude of normal water level fluctuations in the swamp. Future conditions

for this project used the intermediate eustatic sea level rise estimate of 0.67 ft.

Subsidence: Subsidence rates used in this project, per USACE guidance,

were 7.5 mm/yr. This corresponds to 1.23 ft over a 50-year period. This is

based on the measured local increase in sea level over 50 years (9.20 mm/yr)

minus the global eustatic rate of sea level rise (1.7 mm/yr). Coupled with the

intermediate value of eustatic sea level rise, this yields a RSLR of 1.90 ft over a

50-year period. The 50-year RSLR estimates including subsidence range from

1.51 ft at the low estimate to 3.23 ft at the high end. Subsidence estimates in

the Maurepas Swamp have been estimated to range from 4 to 20 mm/yr based

on projects and limited research available for the region. The variation in

predicted subsidence rates in the area must be evaluated when considering the

effects of RSLR.

Accretion: Estimates of future accretion rates are not included in the

projections of future RSLR. The LCA ARDC Modification Project identified a

range of 5 to 25 mm/yr of accretion, with an intermediate estimate of 12

mm/year. The intermediate rate of 12 mm/yr translates into 1.97 ft over 50

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years, which would roughly offset the RSLR of 1.90 ft (eustatic sea level rise

plus subsidence).

Combined Effects: The cumulative 50-year effects of uncertainty with

respect to eustatic sea level rise, subsidence, and accretion are as follows, using

combinations of extreme values:

Highest Estimated Relative Sea Level Rise:

o Maximum Eustatic Rise + Maximum Subsidence - Minimum Accretion

o 2.00 ft + 3.28 ft - 0.82 ft = 4.46 ft

Lowest Estimated Relative Sea Level Rise:

o Minimum Eustatic Rise + Minimum Subsidence - Maximum Accretion

o 0.28 ft + 0.66 ft - 4.1 ft = -3.16 ft

The total range, then, of cumulative effects of land and sea changes is

approximately 7.62 ft, which represents a large range of potential future

conditions, especially considering that the range spans almost equally in

opposing directions. The use of intermediate values for all factors produces an

estimated RSLR is -0.07 ft, representing a condition in which accretion

effectively offsets the combined effects of subsidence and eustatic sea level rise

and the project would be sustainable for the 50-year project life.

Using intermediate values from available regional estimates of each contributing

factor (eustatic sea level rise, subsidence, and accretion) suggest that RSLR over

50 years would not produce the adverse hydrologic impacts to project

performance that were analyzed. Analysis results developed for Alternative 2

are presented in this report and utilized RSLR for three projections: low,

medium and high. The rates of sea level rise and the rate of accretion relative to

the existing elevation of the swamp is depicted for reference in Figure 5-7 and

Figure 5-8. A review of these graphs indicates that with project accretion would

keep up with RSLR under low and intermediate forecasts.

The sea level rise scenarios that were evaluated are considered to be

conservative since they account for eustatic rise and subsidence, but not for

accretion. Uncertainty associated with RSLR can be reduced with the collection

and incorporation of additional information during subsequent project phases to

better define local subsidence and probable accretion rates. In addition,

adaptive management strategies should continue to be incorporated into the

planned project in order to minimize potential impacts of relative sea and land

elevations in the future. As additional information becomes available,

consideration of future conditions would continue to be refined during project

design and to facilitate adaptive management after construction.

In the analyses performed, the use of intermediate values for eustatic sea level

rise, subsidence, and accretion produces an estimated RSLR representing a

condition in which accretion effectively offsets the combined effects of subsidence

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and eustatic sea level rise. This suggests that that RSLR would not produce

adverse hydrologic impacts in project performance.

Figure 5-7: Accretion and sea level rise forecasts

Figure 5-8: Accretion minus sea level rise for the recommended plan

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WVA Results for Sea Level Rise Scenarios

USACE guidance requires project performance to be assessed using three sea

level change scenarios; a low estimate, an intermediate estimate, and a high

estimate. Using the RSLR rate of 9.20 mm/yr (a historical rate representative of

the Study Area based on the West End at Lake Pontchartrain gage-85625), a

starting year of 2012, and a 50-year project life, the low RSLR rate is 1.51 ft for

the year 2062. The low RSLR rate of 9.20 mm/yr includes both eustatic sea level

rise and subsidence. Estimates of the intermediate and high RSLR rates were

determined from NRC curves I and III.

The diversion of water from the Mississippi River at Romeville for the low sea

level rise scenario would be a reduction in the average water depth relative to

the existing condition in the Blind River and Maurepas Swamp for 20 years and

30 years. For the intermediate sea level rise scenario, there would be a

reduction in the average water depth relative to the existing condition for 20

years. For the high sea level rise scenario, there would be no reduction in the

average water depth relative to the existing condition. As sea level rises, water

depth can be expected to increase accordingly throughout the swamp. Because

in-swamp management is a feature of all alternatives, there are considerable

WVA benefits in the first 20 years as a result of those features, and the

difference in AAHUs between alternatives is minimized.

The benefits of the recommended plan (Alternative 2) in terms of AAHUs for

low, intermediate, and high sea level rise estimates indicate 6,741, 6,421, and

5,459 AAHUs, respectively (see FS/SEIS Appendix K, Volume IV). A comparison

of these values indicates that the low sea level rise AAHU value is 5% greater

than the intermediate sea level rise AAHU value and the high sea level rise

AAHU value is 15% less than the intermediate sea level rise AAHU value.

The WVA does not show a distinction (or change in suitability indices) between

habitat classes and between future with project and future without project for

basal area because most of the Study Area is considered to be within the optimal

range for basal area to support wildlife habitat. Because of these factors,

alternative evaluations have placed an emphasis on stand structure and water

regime. The Study Area is semi-permanently flooded and future with project

modeling projections indicate that the flooding regime within most of the Study

Area would return to pre-project conditions by target year 20 as a result of

RSLR. However, hydrologic flow would be improved and would provide

additional benefits by increasing forest stand vigor, accretion, water quality, and

back flow prevention.

Monitoring for adaptive management, including water levels, salinity, and

accretion rates, would provide data to better identify/quantify influence areas

and how water, sediments, and nutrients move through the system and within

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each hydrologic unit. These data as well additional topographic data in the

swamp can be incorporated into the hydrologic models in support of adaptive

management activities and modification of the diversion operation plan.

Hydraulics and Flood Levels: During the FS phase of the LCA Small Diversion

at Convent / Blind River Project, the hydraulic modeling was confined to the Study

Area. During the PED phase the hydraulic modeling would be expanded to include

several additional refinements to the results reported for the project for the

feasibility phase. The areas where additional modeling would be conducted include

downstream hydraulic benefits, effects of nutrients on downstream systems, water

surface elevation control mechanisms as part of the operations system, optimization

of flow through the berm gaps for both flooding and drainage of the swamp. The

results of these additional investigations would be disclosed to the public. The

additional work to refine the hydraulics during PED would optimize the selected

plan, but the ability to optimize the current plan would not make any of the

previously considered alternatives more cost effective.

The level of hydraulics performed for the feasibility phase of the project leaves low

levels of uncertainty that the existing plan is viable and would achieve the

objectives and stated benefits of the project. The primary purpose of additional

modeling would be to assist with better definition of the operations plan for the

timing and control of diversions and for the adaptive management plan for inswamp modifications to improve vegetation productivity. The key point is that the

Maurepas Swamp is a natural system and would be allowed to evolve naturally. As

the ecological evolution of the swamp is monitored the project would have the

flexibility to adapt to that evolution. The hydraulic modeling was adjusted over a

wide range that indicates that the project can operate within those ranges and

achieve the objectives and stated benefits. So while there are some hydraulic

uncertainties, they can be accommodated within the operations plan of the system

once it is optimized.

During PED there would be additional emphasis on how the operations system

would work with the diversion optimization to control the amount of additional

water surface level increase that would correspond to any adverse flooding effects.

During the FS the hydraulic calculations showed that the diversion flows presented

no adverse impacts to water surfaces that were not already present due to rainfall

and extreme tidal events. The entire area is subject to extreme tropical tidal surge

events that far exceed the levels expected by the diversion of 3,000 cfs. There would

be a need to coordinate the stopping of the diversion flows with high tidal and

rainfall events so that the current level of flooding is not increased.

Environmental Uncertainties: Environmental uncertainties include the amount

of water, sediment, and nutrients needed to reverse swamp degradation, the affect

of existing conditions on swamp degradation, and the level of future salinity

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impacts to the swamp. Less impoundment and greater throughput of water and an

increase in hydroperiod fluctuation are needed to reverse swamp degradation, but

the optimal target hydroperiod to maximize swamp productivity, accretion, nutrient

assimilation, seed germination and sapling survival is unknown. Available

information has been summarized regarding how swamps respond to a diversion or

other applications of water, sediment, and nutrients but the specific needs and the

optimal target hydroperiod to reverse the degradation of this swamp would be

determined through project operations and adaptive management. These

environmental uncertainties can, to some extent, be reduced in the future through

adaptive management practices.

Water quality within the swamp and downstream of the swamp would likely change

with diversion flow over time (refer to Volume IV, Appendix L). The expectation is

that water quality would improve in the swamp and the Blind River as freshwater,

nutrients, and sediments from the Mississippi River are delivered to the Study Area

by the project. The feasibility phase modeling of water flow and water quality used

the best available data, however limited, to simulate existing conditions and

estimate future change in water quality. While some uncertainty of change in

water quality exists, water quality monitoring stations installed within the swamp

and along Blind River as part of the feasibility phase will result in more substantial

water quality and salinity data that will be used to refine water quality modeling

during the PED phase. Additionally, as data and further analysis on other projects

in the Maurepas Swamp, such as Hope Canal, are available, the cumulative effects

of all projects on water quality would be examined more fully. These additional

data, analysis, and refined modeling results would be disclosed to the public prior to

construction and a supplemental NEPA document would be prepared as

appropriate.

Construction and Economic Uncertainties: Construction and engineering

design uncertainties include diversion flow control as a function of variability in the

Mississippi River, amount of sedimentation in the transmission canal, the type and

amount of contaminants in the diverted water, the level of erosion control needed,

structural and geotechnical issues related to berm improvement and placement of

water control structures, high groundwater during construction, the need for special

construction equipment and construction techniques in and near the swamp, and

maintenance needs. These uncertainties would be addressed in final design.

Uncertainties that will be considered during actual construction phase include

identification/location of and avoidance of nesting bird colonies and bald eagle nests.

Coordination with the appropriate regulating agencies will minimize disruption to

area avifauna. Construction will also be subject to obtaining all necessary permits

to work in the area and construction timing will consider migration and nesting

seasons. Economic (cost) uncertainties include embankment quantities, geotechnical

results (incomplete), detailed designs for control structures, pricing (including

localized effects), price trends, and inflation. These uncertainties are accounted for

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through conservative design and cost estimating, including contingencies coupled

with a 25% project scope contingency. These construction and economic

uncertainties can, to some extent, be reduced in the future through additional data

collection and analysis and through adaptive management practices.

Because the project relies upon the St. James Parish drainage system to convey

freshwater from the Mississippi River to the swamp, the potential impacts of the

project on flooding were analyzed. The results of this analysis determined that the

inclusion of the gaps as a project feature would allow flow to pass through the

drainage system and into the swamp with no increased risk of flooding. There are

no inhabited structures near the project influence area, and no flooding impacts are

anticipated.

5.4.10 Implementation Requirements

5.4.10.1Schedule

The schedule presents the steps and milestones required to complete the feasibility

report, obtain project approvals, authorization of construction, final design, and

construction (Table 5-12). The recommended plan /NER plan can be implemented

with existing authorities. Following completion of a report of the Chief of Engineers

with a favorable recommendation for the project (provided that the Chief completes

his report before December 31, 2010), the project would be eligible for construction

funding. The project would be considered for inclusion in the President’s budget

based on: national priorities, magnitude of the Federal commitment, economic and

environmental feasibility, level of local support, willingness of the non-Federal

sponsor to find its share of the project cost and the budget constraints that may

exist at the time of funding. Once Congress appropriates Federal construction

funds, the USACE and the non-Federal sponsor would enter into a PPA. This PPA

would define the Federal and non-Federal responsibilities for implementing,

operating, and maintaining the project. Project construction would begin following

the certification of the real estate requirements. After construction, the final

acceptance and transfer of the project to the non-Federal sponsor would follow the

delivery of an O&M manual and as-built drawings.

Table 5-12: Milestone Schedule

Milestone Schedule

Final report

a

August 2010

Division engineer notice August 2010

Washington level review August 2010

Execute cost-sharing agreement for PED September 2010

State and agency review October 2010

Chief of Engineers Report December 2010

Begin preconstruction engineering and design 2010

ASA and OMB review 2011

ASA report to Congress 2011

Complete design documentation report 2011

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Complete plans and specifications 2011

Execute PPA 2011

Complete real estate acquisition 2011

Advertise construction 2012

Construction start 2012

Complete construction 2015

Turnover project to local sponsor 2015

Initiate monitoring and adaptive management During PED

Complete monitoring and adaptive management 2025

a This schedule is currently the best estimate for achieving project milestones but is subject to the administrations

review and budget process.

5.4.10.2 Implementation Responsibilities

In addition to cost sharing as described below, there are a number of other

requirements established by Federal laws and policies that are to be provided by

the non-Federal sponsor. The local cooperation requirements and non-Federal

obligations are specified in the FS/SEIS (Volume IV).

5.4.10.3Cost Sharing

The State of Louisiana, acting through the CPRA, would be the non-Federal sponsor

for the LCA Small Diversion at Convent/Blind River Project. Following the

feasibility phase, the cost share for the planning, design and construction of the

project would be 65% Federal and 35% non-Federal. The CPRA must provide all

LERRDs required for the project. OMRR&R of the project would be a 100% CPRA

responsibility. Table 5-13 shows the cost share amounts for the recommended plan.

Table 5-13: Cost Sharing

Project Feature Total Cost Non-Federal Federal

% Cost % Cost

Total First Cost of

Construction $116,791,000 a 35 $40,877,000 65 $75,914,000

LERRD Credit $3,920,000 100 $3,920,000 0 $0

Monitoring & Adaptive

Management $6,620,000 35 $2,317,000 65 $4,303,000

OMRR&R b,c $2,754,000 100 $2,754,000 0 $0

a Total first cost of construction is based on the sum of the PED; construction management (i.e. supervisions and

administration); LERRDs; and monitoring and adaptive management and is based on October 2010 price levels.

b Average annual cost based on October 2010 price levels.

c

*Costs in this table represent first costs not the fully funded cost through the mid-point of construction ( $123,140,000)

Includes annual O&M as well as annual dredging.

O&M activities would include (but are not limited to) starting and stopping the

diversion(s), routine equipment and instrument maintenance, corrective equipment

and instrument maintenance, and gap and culvert cleaning. The annual estimated

cost for O&M activities is $462,000.

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Annual maintenance dredging or desilting is anticipated to remove sediments

deposited in the Transmission Canal during operation of the diversion system. The

Mississippi River carries a significant suspended solids load. It is expected that the

flow diverted into the diversion operation would have the same characteristics and

would cause a reduction in Transmission Canal volume due to sediment

accumulation. The annual cost for dredging is $2,200,000. Periodically, major

project components may have to be repaired, rehabilitated, or replaced. The annual

cost for repair, rehabilitation, and replacement is $92,000. The total annual cost for

OMRR&R is $2,754,000.

5.4.10.4Environmental Commitments

A summary of the environmental and related commitments made during the

planning process and incorporated into the proposed project plan is as follows.

Mitigation measures are proposed to reduce or avoid impacts that would otherwise

occur as a result of the implementation of the preferred alternative. Construction

contractors or management authorities would implement these commitments.

Some commitments, such as monitoring, would continue beyond completion of

construction of facilities.

Throughout the planning process for the proposed project, efforts have been made to

avoid impacts where practicable. If avoidance was not possible, then mitigation

measures have been developed to reduce the level of impact. The recommended

plan would impact 53 acres (21 ha) of wetlands with construction of the Romeville

diversion canal. The wetlands that would be impacted are not part of Maurepas

Swamp, which, would be improved. The improvement of 21,369 acres (8,648 ha) of

bald cypress-tupelo swamp that are in various stages of deterioration would

mitigate for the wetland impacts resulting from construction of the Romeville

diversion canal.

Other management practices would be employed during construction activities to

minimize environmental effects and would be included in construction

specifications. Many of these measures are required in order to comply with

Federal, State, or local laws and regulations, regardless of whether they are

specifically identified in this document. 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 for the proposed project would be documented to track

the completion of the environmental commitments.

Environmental commitments:

Ensure that construction contractors limit ground disturbance to the smallest

feasible areas.

Use accepted erosion control measures during construction.

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To minimize disturbance to bald eagles and other raptors, nest searches

would be conducted up to three-quarters of a mile of proposed activities prior

to construction to avoid active nests. Appropriate protective measures would

be implemented to avoid or minimize nest disturbance if active nests are

found.

Contact pipeline and gas well companies prior to construction activities to

identify and avoid existing hazards.

Construction contractors would use and implement measures contained in

erosion control guidelines and BMPs to control soil erosion from construction

areas.

Construction contractors would 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.

Formal consultation was conducted on the pallid sturgeon in compliance with ESA

of 1973. A Biological Opinion (Volume IV; Appendix A) was received on September

23, 2010 from the USFWS outlining the following Reasonable and Prudent

Measures and Terms and Conditions:

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 small diversion at Convent/Blind River.

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.

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.

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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/protocols/PallidSturgeonHandlingProtocol2008B.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 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.

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5.5 Public Involvement*

5.5.1 NEPA Scoping

An NOI to prepare an SEIS for the LCA Small Diversion at Convent/Blind River

was published in the Federal Register in December 2008. A scoping meeting was

conducted in February 2009 for the project. Two additional public group meetings

were conducted with groups associated with recreational use of the Study Area.

Common themes of the comments included the following:

Support for the project

A need for urgency

Concerns about the management of hydrology

Concerns about potential impacts to wildlife and endangered species

Some requests for further hydrological studies

The Draft FS/SEIS was released to the public in May 2010, followed by a 45-day

public review period, which included a public meeting. Public comments were

received during the scoping meeting and Draft FS/SEIS public review. Public

comments have been incorporated into the report throughout the report

development. Comments received and the responses to them are included in

Appendix G of Volume IV.

5.5.2 Other Public Comments, Areas of Controversy, Unresolved Issues

Meetings and discussions with the public; local, state, and Federal agencies; and the

PDT indicate support for the project and did not identify any areas of controversy or

unresolved issues.

5.6 Coordination and Compliance *

5.6.1 USACE Principles and Guidelines

Planning for this feasibility study has been conducted in accordance with the ER

1105-2-100 and the P&G. This report is a summary of the integrated FS and SEIS

conducted for this project. Policy reviews have been conducted to ensure compliance

with applicable USACE policies.

5.6.2 Environmental Coordination and Compliance

Coordination and compliance efforts were conducted regarding statutory

authorities. These include environmental laws, regulations, Executive Orders,

policies, rules, and guidance applicable to this project. Full compliance with

statutory authorities would be accomplished upon review of the integrated FS/SEIS

by appropriate agencies and the public and the signing of a ROD.

The USACE has coordinated with the USFWS, NMFS, and the LDWF per the Fish

and Wildlife Coordination Act (48 Stat. 401, as amended; 16 U.S.C. 661 et seq.). A

final CAR has been received and the comments incorporated into the project plan as

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appropriate. Accordingly, the USFWS supports implementation of Alternative 2, a

3,000 cfs diversion at Romeville, provided the following fish and wildlife

recommendations are implemented concurrently with project implementation.

The USACE concurred with the recommendations; discussion of the

recommendation is provided in Volume IV.

Formal consultation on the pallid sturgeon was conducted and a Biological Opinion

was received on September 23, 2010 from the USFWS. The USFWS determined

that the level of expected take is not likely to result in jeopardy to the pallid

sturgeon. The Reasonable and Prudent Measures and Terms and Conditions as

outlined by the Biological Opinion will be followed (Volume IV -Appendix A).

State certifications for coastal zone consistency and 401 water quality have also

been received.

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6.0 TERREBONNE BASIN BARRIER SHORELINE

RESTORATION

6.1 Purpose and Scope*

This is a summary of the FS/SEIS for the LCA TBBSR Project (Volume V).

The LCA TBBSR Project was proposed to reverse the disappearance of the Isles

Dernieres and Timbalier Islands by enlarging the existing barrier islands (width

and height) and reducing the number of breaches. The Isles Dernieres islands and

Timbalier islands are barrier islands that separate Terrebonne and Timbalier Bay

from the Gulf of Mexico and have undergone significant reductions in size due to a

number of natural processes and human actions, including lack of sediment, storminduced erosion and breaching, subsidence, sea level rise, and hydrologic

modifications, such as navigation and oil and gas canals. Loss of island landmass

and associated habitat has impacted wildlife and fisheries resources, left fragile

marshes in the Terrebonne Basin more vulnerable to the high energy marine

coastal processes, increased the potential for storm surge in interior areas, and left

oil and gas infrastructure more vulnerable.

This project would complement but is independent of executed and planned

CWPPRA and CIAP projects in the Study Area.

The environmental consequences of the proposed project are evaluated in Volume V,

Section 5 and summarized here. The integrated NEPA documentation and SEIS is

a supplement to the FPEIS for the LCA Report (USACE, 2004b). The ROD for the

FPEIS was signed on November 18, 2005. The FPEIS is incorporated by reference.

6.1.1 Study Area Background*

The LCA TBBSR Study Area, located in LCA Subprovince 3, provides for the

restoration of the Timbalier and Isles Dernieres barrier islands located in

Terrebonne Parish and Lafourche Parish, Louisiana. The Study Area is located in

the 3rd Congressional District and is shown in Figure 6-1.

The Isles Dernieres have been and continue to be an important commercial and

recreational resource for Louisiana and the nation for more than 150 years. The

islands support habitats that are critical to the State’s commercial fishing industry.

Furthermore, the mineral-rich subsurface below Terrebonne Bay, Lake Pelto, and

Timbalier Bay has supported a high concentration of oil and gas wells. The Isles

Dernieres are the location of five CWPPRA projects. These projects include Raccoon

Island (TE-29), Whiskey Island (TE-27), Trinity Island (TE-24), East Island (TE20), and New Cut (TE-37).

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The Timbalier Islands support onshore and offshore oil and gas development and

production. Oil and gas production facilities are prevalent along East Timbalier

Island, while only a few scattered facilities are present along Timbalier Island. Oil

and gas canals are present on both islands (USACE, 2004c). The Timbalier Islands

are the location of four CWPPRA projects. These projects include Timbalier Island

Planting Demonstration (TE-18), East Timbalier Island Sediment Restoration

Phase 1 (TE-25) and Phase 2 (TE-30), and Timbalier Island Dune and Marsh

Creation (TE-40).

6.1.1.1 Study Area Significance

The Isles Dernieres and Timbalier Islands have been acknowledged as important in

many ways by different entities. Restoration of the Terrebonne Basin barrier

islands is included as a component of Louisiana’s Comprehensive Master Plan for a

Sustainable Coast. The CWPPRA Program previously constructed two projects on

Whiskey Island. Raccoon, Whiskey, Trinity, East, and Timbalier Islands have been

designated as critical habitat for wintering populations of endangered piping

plovers. During the February 2009 NEPA scoping meeting for this report,

numerous public responses were received that expressed the importance of the

barrier islands and a need for urgency in their restoration. The Isles Dernieres and

Timbalier Islands were designated by the National Audubon Society as Important

Bird Areas.

A 2003 study by Stone et al. evaluated the impact of the barrier islands on storm

surge and wave energy along the Isles Dernieres and Timbalier Islands. Modeling

in that study showed significant increases of wave height and storm surge levels in

the period from 1950 to 1990 were attributed to a 24% loss of barrier island and

marsh landmass. Increased storm surge and wave height resulted in the

inundation of an additional 80,000 acres of landmass. Following Hurricanes

Katrina and Rita, there is critical interest in the results of the storm surge study.

The presence of the islands is incorporated into the current Federal Emergency

Management Agency Base Flood Elevations for structure elevations and heights.

6.1.2 History of Investigation

This study addresses general barrier island and estuarine ecosystem restoration

problems and opportunities in the Study Area. Numerous regional and site-specific

investigations of erosion and shoreline loss have been conducted along the

Terrebonne Basin barrier islands. Five of the most comprehensive studies

conducted are:

Coast 2050 Plan (LCWCRTF and WCRA, 1999);

LCA Report (USACE, 2004a);

LACPR Technical Plan (USACE, 2009c);

Integrated Ecosystem Restoration and Hurricane Protection: Louisiana’s

Comprehensive Master Plan for a Sustainable Coast (LACPRA, 2007); and

CWPPRA Barrier Shoreline Feasibility Study (TBS and M&N, 2007).

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6.1.3 Prior Reports and Existing Projects

A number of prior water resources development efforts are relevant to the LCA

TBBSR Study. Information from these prior efforts has been assessed and

considered throughout the project plan formulation process. Table 6-1 lists these

efforts and denotes how each is relevant to the LCA TBBSR Study.

Table 6-1: Relevance of Prior Studies, Reports, Programs, and Water

Projects to the LCA TBBSR Feasibility Study

Prior Studies, Reports, Programs, and Water

Projects

Relevance to Terrebonne Basin

Barrier Shoreline Restoration Data Source Consistency

a

Hard-Structural

Measures

b

Soft-Structural

Measures

c

Future Without

Project Condition

d

Comprehensive Planning Studies

Coast 2050 Plan, 1999 X X X X

LCA, Louisiana Ecosystem Restoration Study,

2004 XX X X X

Louisiana’s Comprehensive Master Plan for a

Sustainable Coast, 2010 XX X X X

LACPR Technical Plan, 2009 X X X

Ecosystem Restoration and Hurricane Protection

in Louisiana (CPRA), 2007 XX X X X

Barrier Island Plan, Evaluation and

Recommendation of the Barrier Shoreline

Feasibility Study, T. Baker Smith, 1997

XX X X X

Prior Studies, Reports and Water Projects

CWPPRA TE-18, Timbalier Island Planting

Demonstration, NRCS, Completed 1996 XX X X

CWPPRA TE-20, Isles Dernieres Restoration of

East Island, EPA, Completed 1999 XX X X X

CWPPRA TE-24, Isles Dernieres Restoration of

Trinity Island, EPA, Completed 1999 XX X X X

CWPPRA TE-25, East Timbalier Island Sediment

Restoration, Phase 1, NMFS, Completed 2000 XX X X X

CWPPRA TE-30, East Timbalier Island Sediment

Restoration, Phase 2, NMFS, Completed 2000 XX X X X

CWPPRA TE-27, Whiskey Island Restoration,

EPA, Completed 2000 XX X X

CWPPRA TE-29, Raccoon Island Breakwater

Demonstration, NRCS, Completed 1997 XX X

CWPPRA TE-37, New Cut Dune and Marsh

Restoration, EPA, Completed 2007 XX X X X

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Prior Studies, Reports, Programs, and Water

Projects

Relevance to Terrebonne Basin

Barrier Shoreline Restoration Data Source Consistency

a

Hard-Structural

Measures

b

Soft-Structural

Measures

c

Future Without

Project Condition

d

CWPPRA TE-40, Timbalier Island Dune and

Marsh Creation, EPA, Completed 2004 XX X X X

CWPPRA TE-47, Ship Shoal - Whiskey West

Flank Restoration, EPA, Currently in

Engineering & Design

XX X X X

CWPPRA TE-48, Raccoon Island Shoreline

Protection / Marsh Creation, NRCS, Under

Construction

XX X X X

CWPPRA TE-50, Whiskey Island Back-Barrier

Marsh Creation, EPA, Construction Funds

Awarded

XX X X X

CWPPRA TE-52, West Belle Pass Barrier

Headland Restoration, NMFS/COE, Currently in

Engineering & Design

XX X

CWPPRA TE-53, Enhancement of Barrier Island

Vegetation Demonstration, EPA, X X

CIAP Nomination - Raccoon Island Breakwaters X X

CIAP Nomination - East Timbalier Island

Sediment Restoration X X

CIAP Nomination - Ship Shoal: Whiskey West

Flank Restoration XX X X X

CIAP Nomination - Beach and Back Barrier

Marsh Restoration, East and Trinity Islands X X

CIAP Nomination - Wine Island Restoration X X

CIAP Nomination - East Island Beach, Dune &

Marsh Restoration X X

CIAP Nomination - East Timbalier Island

(Eastern Section) Restoration X X

CIAP Nomination - East Timbalier Island

Restoration X X

USACE Navigation Projects - Houma Navigation

Canal XX X

Beneficial Use of Dredged Material (BUDMAT) X X

Scoping Study to Evaluate Deepening of Houma

Navigation Channel at Cat Island Pass,

Louisiana, USACE, 2008

XX X

Environmental Assessment - Issuance of NonCompetitive Leases for the use of Outer

Continental Shelf Sand Resources from Ship

Shoal, Offshore Central Louisiana for Coastal and

Barrier Island Nourishment and Hurricane Levee

Construction, MMS, Draft - 2004

XX X

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Prior Studies, Reports, Programs, and Water

Projects

Relevance to Terrebonne Basin

Barrier Shoreline Restoration Data Source Consistency

a

Hard-Structural

Measures

b

Soft-Structural

Measures

c

Future Without

Project Condition

d

Laws and Programs

CWPPRA, 1990 X X X X X

USACE Continuing Authorities Program, 1996 X

CIAP, 2001 & 2005 X X X X X

Second Emergency Supplemental Appropriations

Act to Meet the Immediate Needs Arising from

the Consequences of Hurricane Katrina, 2005

(Public Law 109-062)

X X X

Department of Defense, Emergency Supplemental

Appropriations to Address Hurricanes in the Gulf

of Mexico, and Pandemic Influenza Act, 2006

(Public Law 109-148)

XX X X

Louisiana Coastal Wetlands Conservation,

Restoration and Management Act, 1989 X

Act 8 of the First Extraordinary Session of 2005

(CPRA) X X

a Relevance of TBBSR data sources to data sources of prior projects b Consistency of TBBSR measures with prior projects c Relevance of TBBSR hard-structural measures including breakwaters, revetments, groins, terminal groins, barges/ships,

sand fencing, sheet pile, pass closures, and canal plugs, to hard-structural measures of prior projects d Relevance of TBBSR soft-structural measures including dune/beach restoration, marsh creation, beach nourishment,

subtidal sediment placement, beach closure, vegetation planting, oyster reefs, spit creation, and canal backfilling to softstructural measures of prior projects

6.1.3.1 Federal

Several comprehensive planning efforts have significance to the LCA TBBSR

Feasibility Study; additional information about those comprehensive planning

efforts is included in the FS/SEIS (Volume V). The LCA Report (USACE, 2004a)

information describing this project is summarized here.

LCA Report, 2004: In 2000, the USACE and State of Louisiana initiated the LCA

Report to address Louisiana’s severe coastal land loss problem. In 2004, the LCA

Report was completed and it identified various projects across the coastal area of

Louisiana to address the most critical needs. This project was formulated to

address this description and scope. The report described the LCA TBBSR Project as

follows:

This feature originally considered restoration elements for all the major

reaches of the Terrebonne barrier-shoreline chain. However, for inclusion in

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the near-term plan some consideration to the most critically needed elements

of the chain. This restoration feature provides for the restoration of the

Timbalier and Isles Dernieres barrier island chains. This would simulate

historical conditions by reducing the current number of breaches, enlarging

(width and dune crest) of the Isles Dernieres (East Island, Trinity Island, and

Whiskey Island), Timbalier Island, and East Timbalier Island.

Related Laws and Programs

CWPPRA, 1990: The enactment of CWPPRA in 1990 marked the first Federal

statutory mandate for restoration of Louisiana’s coastal wetlands. In FY 2009,

CWPPRA received approximately $90 million of Federal funding for the planning

and construction of coastal protection and restoration projects (Gay Browning, pers

comm, 2009).

The following projects located within the Study Area have either been constructed,

are in the engineering and design phase, or are awaiting Phase I/II Authorization

(Table 6-2; Figure 6-2):

Table 6-2: CWPPRA Projects in Study Area

Project Name Status Date

TE-18: Timbalier Island Planting Demonstration Completed 7/1996

TE-20: Isles Dernieres Restoration East Island Completed 6/1999

TE-24: Isles Dernieres Restoration Trinity Island Completed 6/1999

TE-25: East Timbalier Island Sediment Restoration, Phase 1 Completed 1/2000

TE-27: Whiskey Island Restoration Completed 6/2000

TE-29: Raccoon Island Breakwater Demonstration Completed 7/1997

TE-30: East Timbalier Island Sediment Restoration, Phase 2 Completed 1/2000

TE-37: New Cut Dune and Marsh Restoration Completed 7/2007

TE-40: Timbalier Island Dune and Marsh Creation Completed 12/2004

TE-50: Whiskey Island Back Barrier Marsh Creation Completed 7/2009

TE-48: Raccoon Island Shoreline Protection/ Marsh Creation -

Phase A

Completed 9/2005

TE-47: Ship Shoal: Whiskey West Flank Restoration Engineering &

design

TE-52: West Belle Pass Barrier Headland Restoration Beginning

engineering and

design

TE-53: Enhancement of Barrier Island Vegetation

Demonstration Waiting phase

CIAP, 2001: CIAP is a grant program authorized by Congress in 2001 to provide

assistance to states in mitigating impacts from OCS oil and gas production. The

Minerals Management Service (MMS) oversees and administers this grant program.

Nominated CIAP projects within the Study Area are identified in Figure 6-3.

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Raccoon Island Breakwaters

East Timbalier Island Sediment Restoration

Wine Island Restoration

Ship Shoal: Whiskey Island West Flank Restoration

Beach and Back Barrier Marsh Restoration, East and Trinity Islands

East Island Beach Dune & Marsh Restoration

East Timbalier Island (Eastern Section) Restoration

East Timbalier Island Restoration

USACE Navigation Projects: There are a number of federally maintained

waterways near the LCA TBBSR Study Area. The most important of these in terms

of potential direct and indirect impacts on the Terrebonne Basin barrier islands is

the HNC. This canal originates in Houma, Louisiana, descends south, and enters

the Gulf of Mexico between East Island and Timbalier Island in Cat Island Pass.

The HNC currently undergoes maintenance dredging in the inland portions every 8

years; the bay portions every 2 years; and the bar channel section every 2 years. A

HNC Deepening Re-evaluation Study is being conducted in response to requests

from the Terrebonne Port Commission to deepen the HNC from -18 to 20 ft

NAVD88.

BUDMAT Program: The USACE MVN has the largest annual channel O&M

program within the USACE, with an average of 64.0 MCY of material dredged

annually. Currently, approximately 24% of the material dredged under USACE

MVN’s O&M program is used beneficially within the Federal standards. The

Federal standard refers to the least costly alternative identified by the USACE that

is consistent with sound engineering practices and meets all of the Federal

environmental standards established by Section 404 of the Clean Water Act of 1972

and Section 103 of the Marine Protection, Research, and Sanctuaries Act of 1972, as

amended. Application of the Federal standard constitutes the base disposal plan for

a navigation project. Funds from the BUDMAT Program would be used for disposal

activities associated with separate, cost-shared, individual ecosystem restoration

beneficial use projects that are above and beyond the disposal activities that are

covered under the USACE O&M maintenance dredging Federal standard.

There are two waterways that are of major significance to the LCA TBBSR Project

that serve as potential sources of beneficially used material. The first is the HNC.

The second is Bayou Lafourche, which is at the far eastern periphery of the Study

Area, approximately 3 miles from East Timbalier Island

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Figure 6-2: Location of authorized CWPPRA projects in Planning Unit 3a

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WRDA 2007 Section 7006(e)(3) 6-10 October 2010Figure 6-3: Location of proposed CIAP projects (LDNR, 2009c)

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Sand Sources: In a 1991 report, Suter, et al. identified and described many of the

previously surveyed and/or utilized nearshore sediment areas in the southeast

portion of Coastal Louisiana. Though these potential borrow areas line the

immediate gulf- and bay-sides of the Terrebonne Basin barrier islands, only the

gulf-side areas are being considered for this study. The State now strongly

discourages bayside sediment dredging because of the potential for the borrow areas

to adversely affect the barrier islands ability to migrate. Furthermore, borrow

areas could potentially serve as sediment sinks in a sediment-starved system.

In April, 2004, the U.S. Department of the Interior, MMS published an

Environmental Assessment titled Issuance of Non-Competitive Leases for the Use of

Outer Continental Shelf Sand Resources from Ship Shoal, Offshore Central

Louisiana for Coastal and barrier Island Nourishment and hurricane levee

Construction (2004). The assessment analyzed the proposed dredging of

approximately 14 MCY of sand for coastal and barrier island restoration and flood

levee construction from within two areas: Ship Shoal OCS area Blocks 87, 88, 89,

94, and 95 and South Pelto OCS area Blocks 12, 13, 14, 18, and 19. These blocks

are located approximately 10 miles south of the Terrebonne Basin barrier islands.

Other Federal Programs: Other Federal and state coastal restoration efforts

over the years have resulted in the construction of state projects, Federal projects,

and state vegetative plantings (LDNR, 2003). One of the more significant

contributions to the restoration of coastal wetlands has been a result of the North

American Wetlands Conservation Act, administered by the USFWS. The 1999 and

2001 biennial North American Wetlands Conservation Act report presented to

Congress cites 30,558 acres of restoration and 40,348 acres where ecosystem

function has been improved in coastal Louisiana wetlands.

6.1.3.2 State

Louisiana’s Comprehensive Master Plan for a Sustainable Coast, 2010: The

Louisiana Legislature, through Act 8 of the First Extraordinary Session of the 2005

Louisiana Legislature, established the CPRA to develop, implement, make reports

on, and provide oversight for a comprehensive coastal protection master plan and

annual coastal protection plans. Several measures proposed in the Master Plan

were incorporated into the initial array for this study.

6.2 Need for and Objectives of Action *

6.2.1 Public Concerns

Public input was received during several scoping meetings as well as meetings with

various stakeholders. The public has expressed support for restoration of the

islands, with specific emphasis on beginning construction as soon as possible.

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6.2.2 Problems, Needs, and Opportunities*

Study Area Problems and Needs

The overarching problem in the Study Area is a lack of sustainability of the coastal

ecosystem, primarily due to coastal land loss. Natural processes and human

actions, such as the construction of oil field canals and the containment of

waterways, have threatened the long-term viability of the Study Area. These

processes and activities have caused significant adverse impacts to the Terrebonne

Basin barrier island shoreline, resulting in extensive barrier island habitat loss and

ecosystem degradation (USACE, 2004a).

Specific problems in the LCA TBBSR Study Area include the following:

Land loss due to erosion threatens the geomorphic and hydrologic barrier

systems

Longshore sediments are significantly reduced, limiting the ecosystem’s

ability to be self-sustaining

Loss of barrier islands/headlands ecosystem habitat

Freshwater wetlands are impacted by increased salinity

The following sections discuss general ecosystem problems identified in the Study

Area.

Retreating and Eroding Barrier Islands: The barrier islands in the Study Area

are the remains of an abandoned Mississippi River Delta; their degradation is the

result of the anthropogenic activities and natural deltaic processes. Barrier islands

act as a buffer to reduce the effects of ocean waves and currents on associated

estuaries and wetlands. Louisiana's barrier islands are eroding at a rate of up to 20

m/yr, and according to recent USGS estimates, several of these islands will

disappear by the end of the century (LACPR, 2009). The disappearance of the

barrier islands exposes coastal wetlands to the full force and effects of wave action,

saltwater intrusion, storm surge, and tidal currents, accelerating wetlands

deterioration.

Lack of Sediment: The islands currently exist in a sediment-starved environment

typical of the erosional barrier arc stage of the deltaic cycle. The lack of sediment is

also attributed to the islands being cut off from potential sediment sources of the

Mississippi River by flood protection levees and other navigation projects, such as

the Belle Pass jetties to the east of the Study Area.

Encroachment of Marine Forces: The soil along natural ridges and barrier

islands is susceptible to wind-induced erosion. Storm events can directly and

indirectly contribute to coastal land loss through a variety of ways: erosion from

increased wave energies, removal and/or scouring of vegetation from storm surges,

and saltwater intrusion into estuaries and interior wetlands carried by storm

surges. These destructive processes can result in the loss and degradation of large

areas of coastal habitats in a relatively short period of time (days and weeks versus

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years). When these soils are eroded away, organic marsh soils are directly exposed

to open water wave attack. Tropical storm events and natural tidal processes are

other natural causes of shoreline erosion.

Saltwater Intrusion: Saltwater intrusion results from changes in the salinity

gradient, which results in habitat changes or loss. Salinity levels exist along a

gradient, which declines as the saltwater moves inland from the Gulf of Mexico. A

distinct zonation of plant communities, or vegetative habitat types, differing in

salinity tolerance exists along that gradient, with the species diversity of those

zones increasing from salt to fresh environments. Changes to the salinity gradient

are caused by a number of factors, including the construction of levees, man-made

channels and canals, and degraded barrier islands. Tropical storm events can

introduce saltwater into fresher areas, damaging large amounts of habitat in a

short period of time.

Subsidence: Vertical accretion in the majority of the Study Area is insufficient to

offset subsidence, decreasing land elevations. Based on NOAA’s current mean sea

level (MSL) trend at Grand Isle, Louisiana of 9.24 mm/yr and global MSL rise of 1.7

mm/yr (USACE, 2009b), the subsidence rate in the LCA TBBSR Study Area is

estimated at 7.54 mm/yr (http://tidesandcurrents.noaa.gov).

Eustatic Seal Level Change: Eustatic sea level change is the global change of the

oceanic water level. According to IPCC (2007), the global MSL rose at an average

rate of about 1.7 mm/yr during the twentieth century. Recent climate research has

documented global warming during the twentieth century and has predicted either

continued or accelerated global warming for the twenty-first century and possibly

beyond (IPCC, 2007).

Relative Seal Level Change: Relative sea level change is the term applied to the

effects of the combination of eustatic sea level change and the change in land

elevation. According to NOAA, the relative mean sea level trend at Grand Isle, LA

is 9.24 mm/yr with a 95% confidence interval of +/- 0.59 mm/yr

(http://tidesandcurrents.noaa.gov). Using the USACE (2009b) projections of future

changes in mean sea level, the estimated relative sea level changes in the LCA

TBBSR Study Area between 2006 and 2062 are 517 mm, 644 mm, and 1058 mm, for

the low/historical, intermediate, and high rates, respectively.

Critical needs in the Study Area include the following:

Restore and/or preserve critical and essential geomorphic structures (beach,

dune, ridge, and marsh) of the Terrebonne Basin barrier system.

Reduce and/or prevent future land loss, habitat loss, and fragmentation of the

land features.

Protect vital local, regional, and national socio-economic resources.

Protect the back barrier estuarine environments from the high energy marine

processes and associated salinities of the Gulf of Mexico.

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Near-term restoration should be synergistic with future restoration by

maintaining or restoring the integrity of Louisiana’s coastline, upon which all

future coastal restoration is dependent.

Design and operate restoration features that support the development of

large-scale, long-range comprehensive coastal restoration.

The sustainability of the coastal ecosystems is threatened by the inability of the

barrier islands to maintain geomorphologic functionality. The Isles Dernieres and

Timbalier barrier islands are expected to be impacted by multiple tropical weather

events over the next several decades. Each storm poses the risk of breaching the

existing islands. As a result, these barrier islands will continue to degrade and

migrate landward as an increasingly fragmented chain of smaller barrier islands.

The fragmentation of the barrier islands will progressively increase the risk of a

single storm event causing widespread fundamental changes in the hydrodynamics

and ecological function of the interior bay system.

Complete opening of the bays to the unabated effects of storms will increase the

volume of open water and fetch within these bays, decreasing their ecologic value.

Ecologic changes will occur, and storm surges will increase, requiring greater levels

of flood risk reduction infrastructure in populated areas. As the islands continue to

fragment and migrate northward which allows intrusion of the Gulf of Mexico,

restoration will become progressively more expensive and difficult to implement.

The effects of increased wave and storm energy will increase stress on, and

contribute to a reduction in the vigor and aerial extent of, the remaining wetlands

that now serve as a buffer affording protection against storms to the developed

areas located north of the Study Area (USACE, 2008b).

Study Area Opportunities

Opportunities for ecosystem restoration include the following:

Increase longevity of the barrier island geomorphic function.

Improve habitat value of the barrier islands.

Increase sediment into the long-shore transport process.

Restore diversity of the barrier island habitats.

Many of the above opportunities can be utilized in combination with planned or

existing projects to produce synergistic effects while minimizing disruptions to the

surrounding ecosystem and economy.

6.2.3 Planning Objectives

The LCA TBBSR study objectives are a localized and project-specific delineation of

the LCA objectives. Based on the function of these barrier islands and problems

identified for the Terrebonne islands during this study, the following planning

objectives were developed to assist the development and evaluation of alternative

plans.

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Provide an expanded footprint of minimized barrier island section to provide

the geomorphic form and ecologic function of the Terrebonne Basin barrier

islands, reducing volume loss within the LCA TBBSR Study Area below the

historical average (1880 through 2005).

Restore and improve various barrier island habitats that provide essential

habitats for fish, migratory birds, and other terrestrial and aquatic species,

mimicking, as closely as possible, conditions that would occur naturally in the

area for the 50-year period of analysis.

Increase sediment input to supplement long-shore sediment transport

processes along the Gulf shoreline by mechanically introducing compatible

sediment and increasing the ability of the restored area to continue to

function and provide habitat for the 50-year period of analysis with minimum

continuing intervention.

6.2.4 Planning Constraints

Planning constraints relevant to the project include natural resources limitations,

such as lack of suitable sediments for restoration; environmental impacts of human

activities in the Study Area; infrastructure and cultural resources that must be

avoided or relocated; and limitations in the characterization and simulation of

environmental processes that determine the effects of alternatives plans. Barrier

shoreline systems are dynamic. Each hurricane and winter season will impact the

shoreline to varying degrees. Breaches created during a hurricane are often healed

through the natural sand transport processes. However, lack of sediment in the

Terrebonne barrier system has limited the natural ability of these breaches to close.

Throughout the study, the team’s analyses attempted to incorporate data related to

these changes. However, the dynamic nature of the shoreline makes it more

difficult to accurately simulate and predict the affects of the various alternatives.

6.3 Existing and Future Without Project Conditions*

This section described the existing and future without project conditions of the

Study Area as they relate to plan formulation and development of alternative

projects. Information regarding the existing condition was obtained from the

“Affected Environment” section of the FS/SEIS and information regarding the

future without project condition was obtained from the “Environmental

Consequences” Section of Volume V.

6.3.1 Existing Condition

6.3.1.1 Location

Extending from Caillou Bay east to Cat Island Pass, the Isles Dernieres is a barrier

island chain approximately 22 miles long. Isles Dernieres chain includes Raccoon

Island, Whiskey Island, Trinity Island, East Island, and Wine Island. Those islands

are bordered to the north by Bay Blanc, Bay Round, Caillou Bay, and Terrebonne

Bay, and to the south by the Gulf of Mexico. The islands range from approximately

0.1 to 1.2 miles wide and are generally composed of a thin sand cap over a thick

mud platform. Elevations are generally low and the islands are frequently

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overwashed (USACE, 2004c). The remnant of Wine Island is located in Wine Island

Pass, about midway between East and Timbalier Islands.

The Timbalier islands include Timbalier Island and East Timbalier Island. The two

islands are on the western edge of the Lafourche barrier shoreline and are located

about 60 miles southwest of New Orleans, Louisiana. They are located east of the

Isles Dernieres. This barrier island shoreline is approximately 20 miles long and

bordered to the north by Terrebonne and Timbalier Bay and by Raccoon Pass to the

east and Cat Island Pass to the west. The islands range from 0.1 to 0.6 miles wide

and have low elevations.

Ship Shoal is the largest and easternmost of a series of sand shoals on the inner

continental shelf of Louisiana and contains approximately 1.6 billion cubic yards of

fine sand (Stone et al., 2009). The elongated shoal lies parallel to the coast

approximately 8 to 12 miles (12 to 19 km) south of the Isles Dernieres and

measures approximately 31 miles (50 km) in an east-west direction (Khalil et al.,

2007). The potential borrow areas identified within the shoal include Ship Shoal

MMS Lease Blocks 87, 88, 89, 94, and 95 and South Pelto Blocks 12, 13, 14, 18, and

19.

6.3.1.2 Climate

The climate of coastal Louisiana is one that is significantly influenced by the Gulf of

Mexico water and wind systems. Louisiana is susceptible to tropical waves, tropical

depressions, tropical storms, and hurricanes due to its proximity to the Gulf of

Mexico. Historical data from 1899 to 2007 indicate that 30 hurricanes and 41

tropical storms have made landfall along the Louisiana coastline (National Weather

Service, and National Hurricane Center).

6.3.1.3 Geomorphic and Physiographic Setting

The most prominent physiographic features are the numerous narrow beaches and

their associated dunes, overwash fans, spits, tidal inlets, marshes, and bays.

Elevations range from a maximum of approximately 5 ft NAVD88 on the highest

dunes to near 0 ft NAVD88 in the back barrier marshes. All of the island segments

are retreating. Much of the erosion and transport of material takes place during

storms (frontal passages and tropical storms / hurricanes). Estimated erosion rates

are provided in Table 6-3 (Barras, 2009; USACE, 2004c).

Table 6-3: Summary of Acreage and Erosion Rates

Island Acreage

in 2008

Short-term

Erosion Rate

(ft/yr)

Long-term

Erosion Rate

(ft/yr) a

Raccoon Island

b

121 -60.5 -27.4

Whiskey Island 509 -86.0 -56.0

Trinity Island 630 -62.5 -38.4

East Island 300 -38.6 -17.0

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Wine Island 12 N/A N/A

Timbalier Island 1,112 -96.4c -23.5

East Timbalier Island

c

242 -36.3 -61.2

a Short-term erosion rates are based on the period from 1988 to 2002.

b Long-term erosion rates are based on the period from 1887 to 2002.

c

N/A = data not available

Average erosion rates for Western and Eastern sections of Timbalier Islands.

Subsidence:

Vertical accretion in the majority of the Study Area is insufficient to offset

subsidence, decreasing land elevations. Based on NOAA’s current MSL trend at

Grand Isle, Louisiana, of 9.24 mm/yr and global MSL rise of 1.7 mm/yr (USACE,

2009a), the subsidence rate in the LCA TBBSR Study Area is estimated at 7.54

mm/yr (http://tidesandcurrents.noaa.gov).

6.3.1.4 Soils

Isles Dernieres soils have been identified as Felicity and Scatlake soil units (USDA,

2005). Felicity soil is a level to gently sloping, somewhat poorly drained soil, which

is formed in the sandy beach rim/dune complex along the Gulf of Mexico shoreline.

The soil is frequently flooded and subject to scouring and deposition by storm surge

and sediment. The surface layer of Felicity soil is typically grayish brown, loamy

fine sand that extends to a depth of approximately 9 inches. The underlying

material, dark gray loamy sand is typically measured to a depth of approximately

60 inches (USDA, 2005).

The soils of Timbalier and East Timbalier Islands are similar to those found on Isles

Dernieres in that they are composed primarily of fine-grained, poorly developed

sands. The Felicity soils are classified as poorly drained, rapidly permeable, saline

sands in the beaches, dunes, and overwash regions, while the Scatlake soils are

mucky clays that are primarily located in the saline marshes (USDC, 1998). The

nearshore features of Timbalier and East Timbalier Islands are flat compacted

sand, with minor sandbar features in 6-8 ft of offshore water (USEPA, 2002).

6.3.1.5 Water Bottoms

Previous studies provide data that use geophysical and geotechnical methods to

assess geologic resource areas for offshore sand sources and provide the geospatial

extent of potential sediment sources for back-barrier and marsh restoration using

numerous core borings.

Ship Shoal is the largest sand source in the Terrebonne Basin and testing has

shown sediment to be similar in quality to the native beaches and dunes of the Isles

Dernieres and Timbalier islands (LDNR, 2005a; USEPA 2003a and 2003b).

Sediments found in Ship Shoal vary based on stratigraphic position. Sediments in

the shoal are composed of very well-sorted quartz sand, finer-grained sand, and

poorly sorted finer-grained sand mixed with layers of silt and clay (Penland et al.,

1988 from Stone et al., 2004).

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Suggested areas of sediment removal were offshore lease blocks Ship Shoal 88,

Pelto 12, and Pelto 13. Volumes, not considering the presence of infrastructure

within these blocks, were estimated at 74 MCY, 58 MCY, and 44 MCY, respectively.

In association with MMS, recent studies have been conducted to establish a buffer

zone around oil infrastructure and other magnetic anomalies within the Ship Shoal

sand resource areas to ensure quality of borrow sediments and safety of dredging

operations (Michel, 2004; Nairn et al., 2004).

In South Pelto, Blocks 12 and 13, analyses identified primarily clean sand (D50

grain size 0.15 to 0.2 mm) with less than 5% silt over an area of about 10.4 square

miles. The combined volume of three closely spaced potential borrows amounted to

approximately 28.3 MCY (Khalil et al., 2007; Finkl et al., 2005).

6.3.1.6 Coastal Processes and Hydrology

The Terrebonne Basin wetland system is exposed to several hydrological influences.

The eastern portions of the basin are hydrologically isolated from the influence of

the major sediment rich waters of the Atchafalaya and Mississippi Rivers. The

same is true for the northwestern portions, both above and below the GIWW, where

the hydrology influence comes mainly from a widely variable pattern of Atchafalaya

River backwater effect, rainfall runoff events, and marine processes. Conversely,

the southwestern portion of the basin receives nourishment from the Atchafalaya

River and has some of the lowest land loss rates in the state (USACE, 2004a).

The present LCA TBBSR Study Area still maintains most of the features of typical

natural estuaries. Even though the changes in hydrology, salinity, and marsh

extent have been severe, there is still a fresh to salt gradient, flow across many

marshes, and an active fish and shellfish nursery—important aspects of estuarine

function and integrity.

The average tidal range near the barrier islands is on the order of 1 ft with a

fortnightly maximum range of 1 to 2 ft. Frontal passages can increase the normal

tidal range up to 2 ft, and storm surges associated with tropical storms and

hurricanes can reach magnitudes several times the normally encountered range.

Hurricane storm surge will typically be on the order of 3 to 4 ft once every 10 years

and 7 ft once every 20 years (USEPA, 1997). For additional information about

hydraulics and hydrology, please see Volume V.

Eustatic Sea Level Change: According to IPCC (2007), the global MSL rose at an

average rate of about 1.7 mm/yr during the twentieth century. Recent climate

research has documented global warming during the twentieth century and has

predicted either continued or accelerated global warming for the twenty-first

century and possibly beyond (IPCC, 2007).

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Relative Sea Level Change: The RSLR rates in the Study Area are among the

highest rate along the contiguous United States. Subsidence and rising sea level

are also largely responsible for shoreline erosion and the transgressive nature of

most of the barrier islands in Louisiana (USACE, 2004c).

Tidal Inlets and Tidal Prism Dynamics: Barrier island development along the

Louisiana coast is a product of river avulsion and the subsequent reworking of

distributary headlands (Penland et al., 1988). The size and number of tidal inlets

along the barrier coast are controlled, in part, by the volume of water (tidal prism)

moving into and out of back-barrier bays. The historical evolution of these tidal

inlets is a product of changes in extent and configuration of the back-barrier bays.

Generally, tidal exchange between back-barrier bays and the Gulf of Mexico has

increased along the Deltaic Plain since at least the 1880s due to widespread

conversion of wetlands and salt marsh to open water areas.

Tidal prism dynamics and the pattern of tidal exchange dictate the occurrence and

geometry of tidal inlets along the various barrier chains. Tidal inlets along the

Timbalier Islands have highly variable geometries due to the segmented nature of

the barrier system. Much of the tidal exchange between the back-barriers of Caillou

Bay, Terrebonne Bay, and Timbalier Bay and that of the Gulf of Mexico occurs

through broad shallow channels where the transgressive barriers have undergone

extensive erosion. However, there are several relatively deep passes 20 to 33 ft

deep that are maintained by strong tidal currents on the order of 3.3 ft/second (s).

Estuarine Circulation:

Tidal currents in Louisiana are relatively small due to the small tidal amplitude. In

the absence of wind, density effects, and barometric pressure gradients, these

currents reach magnitudes of approximately 0.3 to 0.5 ft/s. More critical than tides,

in terms of circulation and mixing, are wind and barometric pressure. Wind can

induce circulation in the form of set-up and set-down, seiche, and wind-waves.

Similarly, the presence of front-like weather during the winter and storms during

hurricane season enhances these processes by producing dynamic wind conditions.

Wind and barometric pressure-induced circulation is critical and dominant in back

bays, enclosed bays, lakes, marshes, and sub-tidal areas. These processes are

characterized by extreme water-level fluctuations and are responsible for a

significant amount of the erosion taking place along the Louisiana coast.

6.3.1.7 Sedimentation and Erosion

Longshore Sediment Transport

Longshore sediment transport is the movement of sediment parallel to the shore.

This process is a result of breaking and shoaling waves suspending sand from the

bottom and the displacement of the sediment down-drift by the longshore current.

Overall net longshore sediment transport along the Isle Dernieres is directed

westward at an approximate rate of 45,000 cubic yards per year (CY/yr) and overall

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net longshore sediment transport along the Timbalier islands is directed westward

at an approximate rate of 15,000 cubic yard CY/yr.

Isles Dernieres Reach: Sediment transport along the Isles Dernieres is complex

given its fragmented nature (Georgiou et al., 2005). Overall, sediment moves in a

westerly direction along the Isles Dernieres reach, although local bidirectional

transport occurs on Trinity and Whiskey Islands. Sediment movement around

Whiskey Pass is largely nonexistent. Waves propagating through the pass break

along the marsh shoreline in Lake Pelto (Stone and Zhang, 2001). This process

indicates that sand is transported predominantly onshore through the pass, thereby

minimizing sediment bypassing that down drift Whiskey Island. Although net

transport rates are variable, net westward transport of approximately 78,000 CY/yr

has been derived numerically (Stone and Zhang, 2001).

Timbalier Reach: According to Georgiou et al. (2005), net sediment movement

along the Timbalier Islands is to the west, and the rate increases from east to west.

Sub-scale transport trends are evident on both islands. However, the sand transport

system along the island has been greatly diminished due to the extent of coastal

structures in the area. The potential for transferring sand from the Caminada

Moreau headland to East Timbalier Island is minimal, given the large width of

Raccoon Pass and the net landward transport of sand to its flood tidal delta

(Georgiou et al., 2005). Kulp et al. (2002) have documented extensive growth of this

flood tidal delta suggests that little sand bypasses the inlet. Rather, the sand is

worked onshore into Timbalier Bay. Bypassing of sand across Little Pass Timbalier

is also minimal. Waves propagate through this inlet prior to breaking inside

Timbalier Bay. Further, the jetties at Belle Pass on the western end of the

Caminada Headland interrupt the natural flow of sediment, thus reducing the

volume transported drown drift (CEC and SJB, 2008).

Similarly, net transport is westward along Timbalier Island with a net increase in

rate along the eastern flank of the barrier island to approximately 65,000 CY/yr

(Georgiou et al., 2005). Conversely, the rate decreases to the western end of the

island. This pattern suggests that sand eroded from the eastern flank is

transported to the west where it is deposited along the west flank of the barrier and

in Cat Island Pass (Georgiou et al., 2005).

Cross-Shore Sediment Transport

Cross-shore sediment transport is the movement of sediment in a direction

perpendicular to the shoreline. Cross-shore movement of sediment includes the

sand that is eroded from the beach and transported offshore during storms as well

as the sand moved onshore by the process of overwash or during poststorm recovery

by fair-weather waves. At the same time, storm waves breaking over low barriers

wash sand into back-barrier marshes. This process provides a mechanism for the

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barrier islands to migrate landward and to reestablish sand platforms that are

colonized by marsh vegetation.

6.3.1.8 Vegetation Resources

Barrier shorelines and associated back marsh areas are dynamic areas with

considerable spatial and temporal variation in plant species distribution.

Vegetation is one of the most important factors in trapping and retaining sediments

in the barrier shoreline system. The zones or communities of barrier island

vegetation and the extent of their diversity are related to elevation, degree of

exposure to salt spray, and storm events that cause overwash.

Vegetation contributes to the stability of barrier islands. Plant colonies trap and

retain suspended sediment (those essential for platform accretion and dune

formation) and protect those newly deposited material from erosion. Vegetation

also contributes to soil structure, nutrients, and trophic-level food supply through

their decomposition and subsequent accumulation of organic matter (detrital

material). In addition to the structural and nourishment benefits, vegetation also

provides habitat function and serves as an indirect indicator of wildlife and fisheries

species vigor and condition (USDA, 2005).

Salt marsh communities (those that are common and fundamental to barrier

islands) are characterized by some degree of tidal inundation, saline substrates,

waterlogged soils, and salt-tolerant vegetation. These communities develop in the

lee of the barrier islands, providing lateral support to the beach and essential

nursery grounds for finfish and shellfish (USEPA, 1997a).

Rare, Unique, and Imperiled Vegetative Communities: The Louisiana

Natural Heritage Program describes imperiled vegetative communities occurring in

the Study Area, including coastal mangrove thicket, coastal dune grassland, and

coastal dune shrub thicket. These communities are nestled within the broader

vegetative habitats and are important in that they contribute to the extensive

diversity of the coastal ecosystem, enhance its productivity, and are essential to the

stability of the bionetwork.

6.3.1.9 Salinity

Barrier islands restrict water exchange with estuaries behind them, provide storm

surge protection to wetlands and human infrastructure, and modify currents and

salinity within the bay system. According to the Louisiana Gulf Shoreline

Restoration Report Louisiana Coastal Area 2004 Study, a comprehensive model

that can evaluate the spatial and temporal links that barrier islands have with the

interior bays and coastal marshes is unavailable. The study showed that the

barrier islands influence the hydrodynamics of the mixing zone but the hydraulic

conveyance of the embayment and the marsh are probably more important. The

more open water and conveyance channels in the marshes, the greater the

penetration of tidal energy into the marsh and the farther the mixing zone of fresh

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and saltwater will move into the marsh. Swenson (2000) found that coastal

salinities in the central and eastern portions of coastal Louisiana were inversely

proportional to Mississippi River discharge, with a range of 10 to 20 ppt but with a

fairly wide distribution.

Barrier islands are critical in maintaining salinity gradients, which are vital for

proper functioning of the associated estuarine systems (Knotts, et al., 2006).

Without these islands, the estuaries deteriorate and higher salinity Gulf of Mexico

waters invade the lower salinity interior wetlands and the estuarine gradient

between them would collapse and its productivity would be destroyed (Penland et

al., 2003).

6.3.1.10 Essential Fish Habitat

Fishery resources in the Study Area include marine and estuarine finfish and

shellfish. By a letter dated February 11, 2009, the NMFS indicated that the barrier

island habitat is designated as EFH. These island habitats and associated nearshore water bodies in the Study Area support fish and crustacean assemblages

distinctly different from mainland marshes. Examples of economically important

marine fishery species in the Study Area include striped mullet (Mugil cephalus),

white mullet, Atlantic croaker (Micropogonias undulates), spot, Gulf menhaden,

Florida pompano, spotted seatrout, sand seatrout, southern flounder, black drum,

and blue crab (Williams, 1998 as cited in pers comm NMFS, February 11, 2009).

Some of these species serve as prey for other federally managed fish species, such as

mackerels, snappers, groupers, billfishes, and sharks.

Barrier islands provide three primary zones of habitats for shellfish and finfish.

These zones of habitats include the surf zone beach; back island low-energy zones

that are either sand flats or marsh; and intra-island ponds, lagoons, and meanders

(Britton and Morton, 1989). The offshore borrow site at Ship Shoal and the

nearshore borrow sites support white and brown shrimp and spotted seatrout

fisheries. These species are major components of the Ship Shoal ecosystem

(http://www.GulfofMexico.mms.gov/homepg/regulate/environ/ongoing_studies/gm/G

M-92-42-109.html).

Aquatic and tidally influenced habitats within the Study Area are designated as

EFH for various life stages for shrimp, red drum (Sciaenops ocellatus), reef fish, and

stone crab managed by the GMFMC.

6.3.1.11 Threatened and Endangered Species

Within the State of Louisiana, there are 28 animal and 3 plant species (some with

critical habitats) under the jurisdiction of the USFWS and/or NMFS, presently

classified as threatened or endangered (Table 6-4). The USFWS and NMFS share

jurisdictional responsibility for sea turtles and the Gulf sturgeon. Of the animals

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and plants under USFWS and/or NMFS jurisdiction, no plant species and only 15

animal species are potentially within the Study Area (including borrow areas).

Table 6-4: Threatened and Endangered Species in Study Area

Species Critical Habitat Status Jurisdiction

Federal State USFWS NMFS

West Indian manatee

(Trichechus manatus) E E X

Sperm whale

(Physeter macrocephalus) E X

Sei whale

(Balaenoptera borealis) E X

Humpback whale

(Megaptera novaeangliae) E X

Finback whale

(Balaenoptera physalus) E X

Blue whale

(Balaenoptera musculus) E X

Piping plover

(Charadrius melodus)

X

(foraging, sheltering,

and roosting habitat

of wintering

populations)

T T X

Hawksbill sea turtle

(Eretmochelys imbricata) E E X X

Kemp’s Ridley sea turtle

(Lepidochelys kempii) E E X X

Leatherback sea turtle

(Dermochelys coriacea) E E X X

Green sea turtle

(Chelonia mydas) T T X X

Loggerhead sea turtle

(Caretta caretta) T T X X

American alligator

(Alligator

mississippiensis)

T X

Pallid sturgeon

(Scaphirhynchus albus) E E X

Gulf sturgeon

(Acipenser oxyrinchus

desotoi)

T T X X

Threatened and endangered species outside of the Study Area would not likely be

affected by the proposed action. There are no known threatened or endangered

floral species near the proposed action. The brown pelican typically frequents the

Louisiana coast and may forage in coastal estuarine waters of the Study Area.

Piping plovers may winter in or near the Study Area, frequenting outer beaches and

occasionally foraging on mudflats within the Study Area. Much of the Study Area is

designated as critical habitat for the piping plover. Formal consultation on the

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piping plover was conducted and a Biological Opinion was received on September

23, 2010 from the USFWS. The USFWS determined that the level of expected take

is not likely to result in jeopardy to the piping plover (Volume V Appendix A).

The West Indian manatee has been reported in the Barataria-Terrebonne estuary

during the summer months and may be a rare visitor in the Study Area.

Threatened and endangered sea turtles typically frequent the Louisiana coast as

they forage in estuarine waters.

Five endangered whale species might be present in offshore Louisiana waters.

During aerial surveys conducted May 1980-April 1981 in the region south of Marsh

Island, Louisiana, there was only one sighting of endangered whales (Fritts et al.,

1983). The final programmatic biological assessment (BA) for the LCA Ecosystem

Restoration Study indicates a low potential for impacting cetaceans with proposed

restoration measures, which includes the present study, across the entire coastal

Louisiana area (USACE, 2004b). A total of 28 cetaceans have been reported in the

Gulf of Mexico waters (Davis et al., 2002; http://www.fws.gov). Of these, five

Mysticeti (i.e., baleen whales including the blue whale [Balaneoptera musculus],

finback whale [Balaenoptera physalus] and sei [Balaenoptera borealis]; and

Odontoceiti [i.e., toothed whales including the humpback [Megaptera novaeangliae])

and sperm whale [Physeter macrocephalus]) have been reported in the Gulf of

Mexico and all are listed as endangered species. Strandings of whales have

occurred throughout the Gulf coast. However, the infrequent historical sightings

and strandings in the Study Area of these endangered cetaceans suggest that most

of these species are rare, accidental, or uncommon. All whales are principally

marine deepwater species and would not likely be impacted by the proposed action.

There are three species of turtle (hawksbill, Kemp's Ridley, and leatherback)

classified as endangered and two species of turtles (green and loggerhead) classified

as threatened that may occur in the Study Area. Green and hawksbill sea turtles

are more tropical in their distribution and rarely seen in the north central Gulf.

The remaining species have been sighted in Louisiana coastal waters.

6.3.1.12 Cultural Resources

Barrier Islands

R. Christopher Goodwin and Associates, Inc., performed a cultural resource

assessment of six APEs within the Study Area in December 2009 (Nowak et al.,

2010). The APEs investigated included the footprint of the design plans for each of

the individual islands composing the Dernieres and Timbalier barrier islands. The

cultural resource assessment reviewed the geomorphology, prehistory, history and

archaeology of the Isles Dernieres and Timbalier Islands to ascertain the

probability for the presence of significant cultural resources (i.e., those

archaeological sites and historic properties possessing the qualities of significance

and integrity defined by the National Register of Historic Places Criteria for

Evaluation [36 CFR 60.4(a-d)]).

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The review and correlation of the geomorphology of the Study Area with the

regional prehistory and archaeological record of this part of south Louisiana

indicate a low probability for significant prehistoric archaeological sites or

prehistoric watercraft within the barrier island APEs. Additionally, any prehistoric

archaeological remains that exist within these areas likely will consist of reworked

and/or redeposited accumulations of cultural materials lacking integrity and having

little research value (36 CFR 60.4[d]).

Consideration of the geomorphology and history of the Study Area also suggests

that there is a low probability for significant historic archaeological sites or

standing structures since no historic occupations were noted on terre firme within

the Study Area. However, various probabilities for the discovery of historic

shipwrecks exist within the barrier island APEs, as summarized below.

Raccoon Island: Within the Raccoon Island APE, a high probability for historic

shipwrecks is indicated near Raccoon Point, while a moderate probability for such

resources is present to the east of this area. A low probability for historic

shipwrecks is indicated along the entire Gulf Coast of the island since waters south

of the shoreline within the APE were subaerially exposed until the mid-twentieth

century.

Whiskey Island: The potential for historic shipwrecks within the Whiskey Island

APE generally is similar to Raccoon Island. Although no reported historic

shipwrecks are recorded within this area, and while ships traveling to and from the

village on Isle Dernieres probably did not pass within the Whiskey Island APE,

Confederate blockade runners probably did pass behind this reach of Isle Dernieres.

As a result, the northwestern portion of the Whiskey Island APE has a moderate

probability for historic shipwrecks. Areas within the APE south and west of this

region were subaerially exposed until the mid-twentieth century; thus, they should

be considered to have low potential for historic shipwrecks.

Trinity and East Islands: Trinity and East Island APE was largely subaerially

exposed until the mid-twentieth century. Coastal Environments, Inc., recently

studied a portion of the East Island APE, and no significant cultural resources were

identified during that study (Kelley et al., 2009). The Trinity and East Island APE

is considered to have low probability for historic shipwrecks.

Wine Island: Modern Wine Island is a relatively recent landform. The area it

occupies was open water prior to and during the nineteenth and early twentieth

centuries. Ships entering or exiting Lake Pelto would have passed close to this

area. One reported shipwreck, the schooner Lizzie Haas, foundered in a gale near

Wine Island during 1902. Considering the position of modern Wine Island near the

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eastern entrance to Lake Pelto, there is a moderate probability for historic

shipwrecks within the Wine Island APE.

Timbalier Island: Three ships are reported to have been lost in the immediate

vicinity of Timbalier Island. These include the side-wheel steamer Merchant, the

schooner Thistle, and the bark Gerhardus (Birchett and Pearson 1998:21-24; Clune

and Wheeler 1991; Goodwin & Associates, 2010). These ships were lost during

1842, 1877, and 1897, respectively. Coastal Environments, Inc., recently

investigated a portion of the Timbalier Island APE (Kelley et al., 2009). No

significant cultural resources were identified during that study. As a result, only

the areas immediately adjacent to but outside of the footprint of the aforementioned

Coastal Environments, Inc., investigation can be considered to have a moderate

potential for historic shipwrecks.

East Timbalier Island: East Timbalier Island is a relatively recent landform.

The area it occupies was open water prior to and during the nineteenth and early

twentieth centuries. No shipwrecks have been reported within the East Timbalier

Island APE. However, ships sailed through the area now occupied by this island

throughout the historic period and could have foundered within the APE.

Normally, there would be a moderate probability for historic shipwrecks within

such an area. However, review of oil and gas field data from the LDNR SONRIS

system indicates that extensive disturbance has occurred within the East Timbalier

Island APE. As a result, a low to moderate probability exists for historic

shipwrecks within the East Timbalier Island APE.

In addition, R. Christopher Goodwin and Associates, Inc., considered the Whiskey

Pass Silver King Association statue of the Madonna on Trinity Island and

determined that the statue does not possess significance of associations with

important historic patterns or events, for associations with important personages,

for its qualities of design or construction, or for its potential to yield important

information, as required under the National Register Criteria for Evaluation (36

CFR 60 [a-d]).

Section 106 consultation was initiated with the Advisory Council on Historic

Preservation, SHPO, and federally recognized Indian tribes in May 2009, and the

results of the cultural resource assessment have been coordinated with the SHPO

officer. In consultation with the Advisory Council on Historic Preservation, SHPO,

Indian tribes, representatives of local governments, and other consulting parties,

the USACE developed a Programmatic Agreement among the USACE, CPRA,

SHPO, and Advisory Council on Historic Preservation, pursuant to 36 CFR §

800.14(b)(1), executed July 29, 2010. The programmatic agreement establishes the

procedures for consultation, identification of historic properties, assessment and

resolution of adverse effects, and is included in Appendix F of Volume V. The

execution and implementation of the programmatic agreement fulfills USACE

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obligations under Section 106 of the National Historic Preservation Act of 1966, as

amended.

Borrow Areas

Five sediment sources have been identified for use as borrow for either beach and

dune restoration or marsh creation and restoration. The five source locations have

been investigated to determine if any historic properties exist within the APE; the

results are summarized below. The locations of potential sites, possibly

representing historic shipwrecks or prehistoric sites, will be avoided, and the

USACE MVN will continue consultation with the SHPO and Federally recognized

Indian tribes, providing documentation of a “no historic properties affected” finding

for the recommended plan .

Whiskey Island TE-50 Area 3: Whiskey Island TE-50 Area 3 is located

approximately 3 miles south of Trinity Island in state waters. Submerged cultural

resource investigations of Subarea 3a revealed several areas where magnetic

anomalies were detected. Of the 247 magnetic anomalies identified, only 24 were

considered to be potentially significant cultural resources and recommended for

avoidance by Archaeological Resources, Inc. (TBS and M&N, 2007).

New Cut TE-37 Area 4: The New Cut TE-37 Area 4 is an existing active borrow

area in state waters previously utilized by LDNR. Seismic and magnetometer

surveys have been conducted throughout this borrow area. Avoidance area

locations were developed based on these surveys.

Raccoon Island TE-48 Area 5: The Raccoon Island TE-48 Area 5 is located

approximately 4 to 6 miles south of Raccoon Island in Federal waters. A submerged

cultural resources investigation was conducted at this location in 2008. Review of

the geology, prehistory, and history of the borrow area indicate that there is low

potential for the discovery of both submerged prehistoric cultural resources and for

the discovery of submerged historic cultural resources, such as shipwrecks. The

magnetometer data indicated one pipeline, one anomaly cluster that may represent

a pipeline, and three anomaly clusters that may represent significant submerged

cultural resources. No potentially significant side-scan sonar contacts were

identified. R. Christopher Goodwin and Associates, Inc., recommended avoidance of

the abovementioned anomalies (Goodwin, 2008).

South Pelto Area 6: South Pelto Area 6, which includes MMS South Pelto Lease

Blocks 12 and 13, is located in Federal waters of the Gulf of Mexico approximately

9.5 miles south of Isle Dernieres. A submerged cultural resources investigation was

conducted in 2003. Numerous sonar targets and magnetometer anomalies were

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recorded. Based on these findings, 10 avoidance areas were proposed within the

borrow area (C & C 2003b).

Ship Shoal Area 7: Ship Shoal Area 7, which includes MMS Lease Blocks 87, 88,

89, 94, and 95, is located in Federal waters of the Gulf of Mexico approximately 10

miles south of Whiskey Island. All of these lease blocks are identified by the MMS

as high probability areas relative to prehistoric archaeological site potential and

Blocks 88, 89, and 94 are identified as high probability blocks relative to historic

shipwreck potential. Ship Shoal deposits have the potential for containing cultural

resources dating to the Middle Archaic period (circa 7,000 to 5,000 years before

present) (C & C, 2003a). Evidence suggests that Ship Shoal deposits have been

churned, reworked, and extensively burrowed over the past several thousand years

such that any cultural remains contained in them have been disturbed and will not

be in situ (Penland et al., 1985). Substantial geophysical surveys were conducted

within the borrow area as part of a separate coastal restoration effort (C & C,

2003a). Based on these surveys, two areas were recommended for avoidance

because of potentially significant cultural resources.

6.3.1.13 Recreation

The 2009 - 2013 Louisiana SCORP inventoried over 104,000 acres of recreational

facilities for SCORP Region 3, which includes Terrebonne Parish (2009). Public

lands in the Terrebonne Basin include one USFWS National Wildlife Refuge, the

Mandalay National Wildlife Refuge. The Terrebonne Barrier Island Refuge

includes portions of Raccoon, Whiskey, and Trinity islands.

Major recreational activities occurring in the coastal area, specifically in and around

barrier islands, include sport fin-fishing (the most popular); waterfowl, recreational

shrimping; boating; swimming; sailing; picnicking; camping; hunting; bird

watching; and observing wildlife. The barrier islands of the Terrebonne Basin are

also a resting area for migratory neo-tropical songbirds and waterfowl. Many of

these birds are passing through coastal Louisiana on their way to nesting areas

northward.

6.3.1.14 Socioeconomic Resources – Navigation

Within the Terrebonne Basin, there is one federally maintained navigation feature

that is important to barrier island morphology, restoration, and maintenance. This

canal, the HNC, serves as a navigation route connecting the Gulf of Mexico with the

interior of the central coast of Louisiana, providing direct access to the maritime

and offshore support interests. Navigation channels introduce and/or compound

marine influences in many of the interior wetlands and water bodies within the

coastal zone (USACE, 2004a). The HNC has direct influence on the Terrebonne

Basin barrier shoreline as its mouth is situated in Cat Island Pass at the western

end of Timbalier Island.

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The thousands of miles of navigation channels and oil and gas canals in coastal

Louisiana have played a major role in the loss of wetlands and barrier islands

(USACE, 2004a). These losses can be attributed to the direct conversion of marsh

to open water, as well as by the indirect impacts associated with altered hydrology

and saltwater intrusion. Navigation channels that cross open bays may silt in more

rapidly or begin to shoal in less predictable ways. Without barrier island

restoration, the islands and marshes that protect waterborne traffic will continue to

erode and adversely impact vital navigable waterways. As the adjacent and

connecting protective marsh and barrier island landscapes disappear, the wind and

wave energy from nearby open bays and the Gulf of Mexico will have increased

adverse effects on these navigable waterways (USACE, 2004a).

6.3.1.15 Socioeconomic Resources – Oil, Gas, and Utilities

Louisiana’s production of crude oil has declined by about 30% since 1980, although

production in the Louisiana offshore OCS has increased steadily since 1990 and

now exceeds the onshore production rate (MMS, 1999). Louisiana provides over

27% of the total oil produced in the United States.

Natural gas has been the second largest source of energy for the U.S. since 1988.

Louisiana currently provides over 26% of the total natural gas produced in the

United States

All of the oil and gas produced along Louisiana’s coast and wetlands comes from a

highly interdependent network of core and supporting industries. Port Fourchon is

the geographic and economic hub of this core. There are hundreds of offshore

drilling rigs in the Gulf of Mexico. The Study Area is traversed by numerous oil and

gas pipelines of various sizes, many within the footprints of the plan alternatives

and in their immediate vicinity.

The lines represent both a substantial investment and a substantial level of risk for

the area. The pipelines are increasingly at risk from a combination of coastal

erosion and local navigation. The erosion of wetland areas uncovers pipelines that

had been buried in the marsh for protection. As land is converted to open water, the

pipelines remain under water and unprotected from maritime traffic.

6.3.1.16 Socioeconomic Resources – Commercial Fisheries

Louisiana produced about 52.8 million pounds of blue crabs, totaling $31.8 million

in dockside revenue, and accounting for 36% of the nation’s total production for

2006 (LDWF, 2008). One of the most important species harvested in the Louisiana

waters is the Gulf menhaden. The 2006 Louisiana menhaden fisheries landings

were the largest in the nation (746 million pounds), landing twice as much as the

next closest state (LDWF, 2008). Located just north of the Study Area, the port at

Dulac-Chauvin, Louisiana reported commercial fisheries landings in 2007 at 23.5

million pounds with a dockside value of $35.5 million (NMFS, 2008).

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6.3.1.17 Socioeconomic Resources – Oyster Leases

Terrebonne and Lafourche parishes play an important role in Louisiana’s oyster

industry, accounting for more than 25% of the state’s total oyster leases. Within 6

km of the Study Area, there are approximately 100 oyster leases. These leases are

most plentiful to the north of the Isles Dernieres reach, in the northern portions of

Caillou Bay and Lake Pelto. Though there are many leases in the Isles Dernieres

vicinity, few leases are located near the Timbalier Island Reach. Nearby seed

grounds are managed by the LDWF to produce a ready supply of seed oysters that

can be planted on private leases for later harvest. However, increasing coastal land

loss is reducing the amount of marsh that provides shelter to reefs, and saltwater

intrusion is exacerbating disease and predation.

6.3.2 Future Without Project Condition

The future without project conditions are the same as conditions under the No

Action Alternative. Therefore, the No Action Alternative scenario was the basis for

comparison of the alternatives in plan formulation.

6.3.2.1 Land loss

Raccoon Island: The average short-term shoreline change between 1988 and 2002

was -60.5 ft/yr with a range of -144.5 to -8.6 ft/yr (USACE, 2004c). Since 1978,

Raccoon Island rapidly decreased in area. If no action is taken to restore Raccoon

Island, the following significant environmental resources that have institutional,

public, and technical importance will be lost.

Westernmost end of the Isles Dernieres Barrier Island Refuge

Second largest nesting colony of brown pelicans in Louisiana (USEPA, 1993)

Largest species diversity of aquatic birds of any single island in Louisiana

and perhaps North America (USEPA, 1993)

Critical habitat for piping plover

188 acres of EFH and highly productive marsh

51 acres of supratidal habitat utilized by the brown pelican as a rookery and

by migrating birds as resting areas

Storm surge protection for western Terrebonne Parish

Whiskey Island: The average short-term shoreline change rate was -86.0 ft

between 1988 and 2002 with a range of -139.4 to -48.4 ft/yr (USACE, 2004c). If no

action is taken to restore Whiskey Island, significant environmental resources will

be lost:

443 acres of EFH

Critical habitat for piping plover

377 acres of supratidal habitat

Storm surge protection for Terrebonne Parish

Protection of oil and gas infrastructure

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Trinity Island: The average long-term shoreline change rate between 1956 and

1988 developed from the atlas of shoreline changes on Louisiana was -39.7 ft/yr

(William et al., 1992). If no action is taken to restore Trinity Island, the following

environmental resources will be lost:

311 acres of EFH

Critical habitat for piping plover

232 acres of supratidal habitat

Storm surge protection for western Terrebonne Parish

Protection of oil and gas infrastructure

East Island: The average long-term shoreline change rate between 1956 and 1988

developed from the atlas of shoreline changes on Louisiana was -39.7 ft/yr (William

et al., 1992). If no action is taken to restore East Island, significant environmental

resources will be lost:

71 acres of EFH

Critical habitat for piping plover

178 acres of supratidal habitat

Storm surge protection for western Terrebonne Parish

Protection of oil and gas infrastructure

Wine Island: The average long-term shoreline change rate between 1956 and 1988

developed from the atlas of shoreline changes on Louisiana was -21.6 ft/yr (William

et al., 1992). If no action is taken to restore Wine Island, significant environmental

resources will be lost:

6 acres of EFH

Critical habitat for piping plover

5 acres of supratidal habitat utilized by the brown pelican and numerous

other shorebirds

Storm surge protection for western Terrebonne Parish

Protection of oil and gas infrastructure

Timbalier Island: The average long-term shoreline change rate between 1956 and

1988 developed from the atlas of shoreline changes on Louisiana was -32.5 ft/yr

(William et al., 1992). If no action is taken to restore Timbalier Island, the

following significant environmental resources will be lost:

374 acres of EFH

Critical habitat for piping plover

549 acres of supratidal habitat

Storm surge protection for eastern Terrebonne and Lafourche parishes

Protection of oil and gas infrastructure

East Timbalier Island: The average long-term shoreline change rate between

1956 and 1988 developed from the atlas of shoreline changes on Louisiana was -21.4

ft/yr (William et al., 1992). If no action is taken to restore East Timbalier Island,

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significant environmental resources will be lost that have institutional, public, and

technical importance.

173 acres of EFH

Critical habitat for piping plover

129 acres of supratidal habitat

Storm surge protection for western Lafourche Parish

Protection of oil and gas infrastructure

6.3.2.2 Soils

The No Action Alternative would have no direct impacts on soil resources. Existing

conditions would persist.

Indirect impacts would result in the soil resources at the Terrebonne Basin barrier

shoreline to likely be converted into shallow open water bottoms.

Cumulative impacts include continuing erosion and loss of coastal landforms. The

LCA Report estimated coastal Louisiana would continue to lose land at a rate of

approximately 6,600 acres per year over the next 50 years (USACE, 2004a). Land

loss along Terrebonne Basin Barrier Shoreline would likely continue at rates

similar to present resulting in the projected loss of 3,220 acres of barrier island soils

by 2062.

6.3.2.3 Water Bottoms

The No Action Alternative would have no direct impacts on water bottoms and/or

benthic resources.

Within the period of analysis, the No Action Alternative would result in the

conversion of approximately 3,220 acres of existing Terrebonne Basin barrier island

beach, dune and marsh habitats to water bottoms.

Cumulative impacts to water bottoms would be the synergistic effect of the NoAction Alternative of converting 3,220 acres of existing Terrebonne Basin barrier

island habitats to water bottoms, along with the additive combination of

approximately 10% of Louisiana’s remaining coastal wetlands being converted to

water bottoms at a rate of 6,600 acres per year over the next 50 years, resulting in

an additional net loss of 328,000 acres by 2050 (Barras et al. 2003).

6.3.2.4 Coastal Processes and Hydrology

Not implementing proposed restoration of the Terrebonne Basin barrier shoreline

would have no direct impacts on coastal processes, flows or water levels.

The primary indirect impacts of not implementing the proposed Terrebonne Basin

barrier shoreline restoration measures would be associated with changes in coastal

processes. Both natural and human-induced changes to coastal processes of water

flows and levels would continue. The natural and human-induced hydrological

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modifications to coastal processes that have influenced flows and water levels

throughout the Louisiana coastal barrier systems is well documented (USACE,

2004a). Natural subsidence, barrier shoreline erosion due to waves and storms,

construction of oil and gas exploration canals, construction and maintenance

(dredge and fill activities) of navigation channels, as well as mineral extraction

would continue to contribute to alteration of the natural coastal processes and flow

and water levels within the Terrebonne barrier system. These and other influences

have resulted and will continue to result in the Terrebonne barrier islands moving,

changing shape and decreasing in size over time (Williams et al. 1992).

Construction of navigation channels, as well as natural coalescence of tidal passes,

will continue to influence coastal processes and the Terrebonne barrier systems.

If the natural and human-induced changes to coastal process responsible for

continued land loss continue in the Study Area, the Terrebonne Basin barrier island

system would likely continue to be lost at rates similar to present resulting in the

projected loss over all seven of the Terrebonne barrier islands of about 3,220 acres

by 2062.

6.3.2.5 Sedimentation and Erosion

The No Action Alternative would have no direct impacts on sedimentation and

erosion. Without any action, approximately 3,220 acres of existing barrier sediment

resources from the seven island Terrebonne Basin barrier system (East Timbalier,

Timbalier, Trinity, East Island, Wine, Whiskey and Raccoon Island) would likely

continue to erode similar to historic erosion rates and eventually convert into

shallow open water bottoms..

The No Action Alternative would have indirect impacts on sedimentation and

erosion in which sediment quality would be affected. Sediment quality is important

due to the role that sediments play in supporting community productivity. The

productivity of green plants, algae, and bacteria build the foundation of food webs

upon which higher aquatic organisms depend. Sediments provide essential habitats

for epibenthic (live on sediments) and infaunal (live in sediments) invertebrates and

demersal fish, which represent important food sources for amphibians, reptiles, fish,

birds, and mammals. In addition, many fish and amphibian species utilize

sediments at stages in their life cycles for the purposes of spawning, incubation,

refuge, and over-wintering (LDEQ, 2005). As smaller sediments are deposited

rather than larger heavier sediments (such as sand and course silt), erosion rates

would increase, causing the barrier islands to deteriorate much quicker.

The No Action Alternative would have cumulative impacts on sedimentation and

erosion in which sediment quality, quantity, and sediment source would be affected.

Erosion rates would increase to the point that the barrier habitats would erode and

sedimentation would decrease, forcing these critical habitats to no longer exist.

Sediment quality would be altered in size and the availability of sediments that are

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needed for healthy marsh, beach, and dune habitats. When all intertidal habitats

along the barrier islands disappear, the remaining habitat types will increase in

erosion and disappear as well. Storm surge will then reach farther inland with the

absence of these barrier islands, resulting in an increase in erosion along inland

marshes.

6.3.2.6 Vegetation Resources

Without implementation of proposed coastal barrier system restoration, the

Terrebonne Basin barrier shoreline would continue to degrade, fragment and

eventually convert to primarily marine-influenced open water

Indirect impacts would include a decline in wetland vegetation as well as net

primary productivity inland of the Study Area. 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. Other indirect adverse impacts

that would result from the loss of important and essential vegetated habitats used

by fish and wildlife are the loss of shelter, nesting, feeding, roosting, cover, nursery,

and other life requirements for fish and wildlife; loss of productivity; loss of

transitional habitat between estuarine and marine environments; and increased

inter- and intra-specific competition between resident and migratory fish and

wildlife species for decreasing wetland resources. This would also reduce the

availability of important stopover habitats used by migrating neotropical birds.

Cumulative impacts would include a loss of vegetation resources as well as

productivity of the Study Area.

6.3.2.7 Salinity

The No Action Alternative would have no direct impact on salinity. Existing

conditions would continue to deteriorate, allowing higher salinity from Gulf of

Mexico waters to invade the lower salinity interior wetlands and the estuarine

gradient.

Indirect effects would be an increase in salinity over time that would collapse the

estuarine gradient, and its productivity would be destroyed (Penland et al., 2003).

A change in tidal prism would result in increased land loss and conversion of the

estuarine system to a more marine system. Vegetation species would be dominated

by a more salt-tolerant species, and freshwater aquatic species would be forced to

move inland.

The cumulative impacts would result in a dramatic increase in salinities as the

islands deteriorate causing salinity ranges equivalent to the open waters of the Gulf

of Mexico.

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6.3.2.8 Essential Fish Habitat

The No Action Alternative would have no direct impacts on EFH.

With the data currently available, it has been determined that under the existing

conditions, 1,560 acres of back barrier marsh, a more productive category of EFH

would be converted to water bottoms, a less productive category. This loss would

continue to adversely impact essential spawning, nursery, nesting, and foraging

habitats for commercially and recreationally important species of finfish and

shellfish, as well as other aquatic organisms.

The cumulative impacts of barrier island loss, conversion of existing EFH, sea level

change, increased storm intensity, and other natural perturbations are expected to

lead to a decrease in the diversity of EFH most supportive of estuarine and marine

species. Over time, the no action alternative would result in a substantial decrease

in the quality of EFH in the Study Area and reduce the area’s ability to support

federally managed species.

6.3.2.9 Threatened and Endangered Species

The No Action Alternative would have no direct impacts on listed (endangered or

threatened) species or their critical habitat in the Study Area.

Indirect impacts of not implementing the barrier island restoration features would

result in the continued degradation and loss of critical habitat (such as the Gulf

shoreline) for piping plover and other listed threatened or endangered species that

utilize the Study Area, including Gulf sturgeon, green sea turtle, hawksbill sea

turtle, Kemp’s Ridley sea turtle, leatherback sea turtle, loggerhead sea turtle,

brown pelican, and the West Indian manatee.

Listed species or their critical habitat would be impacted by continued coastal land

loss and deterioration of critical coastal habitats. It is anticipated to impact all

threatened and endangered species, which utilize coastal Louisiana. In particular,

the brown pelican, bald eagle, piping plover, and all sea turtles would most likely be

impacted to the greatest extent, as these species utilize the rapidly deteriorating

barrier systems.

6.3.2.10 Cultural Resources

The No Action Alternative, not implementing coastal barrier system restoration,

would have no direct impacts on historic or cultural resources.

As the barrier islands and inland marshes erode or subside, cultural resources

existing on them could be exposed to elements or inundated, putting them at a

greater risk of damage or destruction. Resources could also be adversely impacted

over time by an increased risk of storm damage as barrier islands and marshes

continue to degrade.

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Cumulative impacts on cultural resources would include continued adverse effects

as historical and archaeological sites are exposed to these forces.

6.3.2.11 Recreation

Recreational resources in the Louisiana coastal zone that would be most affected in

the future without project conditions are those related to loss of wetlands/marshes

and habitat diversity.

Indirect impacts of no action include the loss of recreational activities associated

with the coastal and inland marshes. As existing barrier islands are lost and

freshwater wetland/marsh areas convert to saltwater marsh and then to open

water, the recreational opportunities would change accordingly. Another major

impact of barrier island and land loss is the possible loss of facilities and

infrastructure that support or are supported by recreational activities.

Cumulative impacts result in the recreation needs identified by the SCORP for the

Study Area becoming greater. Land loss, particularly the potential loss of barrier

islands and conversion of marsh to open water, may be the largest impact to

recreation resources. Over time, conversion of marsh to open water may result in a

decline of estuarine-dependent recreation. Access to marsh recreation opportunities

may be impacted by predicted land loss.

6.3.2.12 Socioeconomic Resources – Navigation

The No Action Alternative would have no direct impacts on navigation.

Indirect impacts would result in the persistence of existing conditions, including

continued wetland loss and degradation of the barrier islands and coastal wetlands

north of the Study Area. This continued wetland loss may affect navigability and

maintenance of federally maintained waterways, including the HNC, Bayou Grand

Caillou, and Bayou Terrebonne.

There would be cumulative impacts of the No Action Alternative on navigation, as

this will change access, cost, and maintenance of federally maintained waterways

that pass near or within the Study Area.

6.3.2.13 Socioeconomic Resources – Oil, Gas, and Utilities

The No Action Alternative would have no direct impacts on oil, gas or mineral

resources.

Indirect impacts of not implementing the barrier island restoration would result in

the continued deterioration of existing conditions and increased costs for

maintaining and repairing existing infrastructure, reduced level of oil and gas

infrastructure development and relocation of some existing oil and gas assets.

Continued degradation would expose buried pipelines, thereby increasing the risk of

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failure or damage due to lack of structural stability, anchor dragging, and boat

collisions.

Cumulative impacts to oil and gas infrastructure would include higher operations

cost and upgrading wells, platforms, and other equipment to withstand open water

areas due to the loss of barrier islands.

6.3.2.14 Socioeconomic Resources – Commercial Fisheries:

The No Action Alternative would have no direct impacts on commercial fisheries.

Existing conditions would persist.

Wetland habitat losses would contribute to the overall decrease in productivity of

these fisheries throughout the coastal Louisiana area. The seafood industry would

likely suffer significant losses in employment as estuaries that are necessary to

produce shrimp, oysters, and other valuable species continue to erode. Job losses

would likely occur in the areas reliant on fishing, harvesting, processing, and

shipping of the seafood catch.

The cumulative impacts include significant losses in employment in the seafood

industry as natural resources, which are necessary to produce shrimp, oysters, and

other valuable species (mainly estuaries), begin to erode. Job losses would occur in

the areas of fishing, harvesting, processing, and shipping of seafood catch.

6.3.2.15 Socioeconomic Resources – Oyster Leases

The No Action Alternative would have no direct impacts on oyster leases. Existing

conditions would persist.

The loss of wetlands in the Study Area would likely alter the detritus-based food

web of the oyster, thereby reducing the localized carrying capacity for oyster leases

in the area. Oysters depend on estuarine wetlands for protection and food when

they are juveniles.

Cumulative impacts would be eventual loss of barrier habitats, which in turn,

would result in increased salinity conditions making these areas unsuitable for the

viable culture of oysters.

6.4 Alternatives *

6.4.1 Plan Formulation Rationale

The LCA TBBSR Project is an extension of previous planning efforts including the

CWPPRA program, the Coast 2050: Toward a Sustainable Coastal Louisiana

Report, and the 2004 LCA Report (USACE, 2004a). Alternative plan formulation

was performed in a two-stage process: (1) the available ecosystem restoration

measures were evaluated for capability to meet project objectives and (2) alternative

plans were formulated from the selected restoration measures. The plan

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formulation process included a number of detailed evaluations of potential scales

and combinations of restoration measures and an iterative refinement process for

alternative development.

6.4.2 Management Measures

Management measures were developed to address Study Area problems and to

capitalize upon Study Area opportunities. The PDT evaluated hard-structural

management measures and soft-structural management measures.

Hard-Structural Measures

Breakwaters

Revetments

Terminal groins

Groins

Sand fencing

Sunken barges/ships

Floating barges/ships

Sheet pile

Pass closures

Canal plugs

Soft-Structural Measures

Dune restoration

Marsh creation

Beach restoration

Subtidal sediment placement

Addition of sediment into near-shore environment to supplement littoral drift

Breach closure

Small marsh island construction on bayside for bird habitat

Vegetation planting

Herbivore control

Bio-engineered oyster reefs

Spit creation (threatened and endangered species habitat)

Backfilling canals

6.4.2.1 Screening of Management Measures

Initial Screening

Qualitative screening of 31 measures (19 hard-structural and 12 soft-structural)

proposed in the initial array resulted in the elimination of 15 measures and the

retention of 16 measures to be carried forward for more detailed evaluation in the

second level of screening. Measures were eliminated following an analysis of past

project performance, reviews of technical literature, technical evaluation among the

PDT, and scientific judgment.

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Second Screening

The second-level screening effort built on the initial screening process, with

emphasis on the combinations of measures that could be used to meet the specific

objectives of the project. Combinations of management measures are referred to as

“island strategies.” This screening process was undertaken during a three-day field

trip to the islands. Results of the previous screenings were reviewed in situ, along

with observations of the conditions of past CWPPRA projects. Based on these

discussions, it was determined that a combination of beach, dune, and marsh

restoration measures would be required to meet the primary objective of restoring

the geomorphologic form and ecologic function of the barrier islands. This

combination was designated as the primary island strategy.

Sand fences, vegetative planting, herbivory control, segmented breakwaters,

terminal groins, and continuous revetments remained in the evaluation based on

their potential to provide supplemental benefits to the beach/dune/marsh island

strategy proposed above.

Final Screening

The PDT had concluded that the island strategies must include a beach, dune, and

marsh component in order to achieve the objectives of the project. Therefore, the

final screening effort evaluated the use of supplementary measures, including sand

fences, vegetative planning, herbivory control, breakwaters, terminal groins, and

continuous revetments (for Wine Island Only).

Raccoon Island: The PDT evaluated the potential effectiveness of an additional

series of breakwaters and a terminal groin on the western end of the existing

breakwater field using a series of models. The Steady State Spectral Wave

(STWAVE) model was used to transform wave data from offshore locations to the

surf zone. This information was used in the Generalized Model for Simulating

Shoreline Change (GENESIS) to evaluate the impact of the structures on shoreline

erosion. The coupled STWAVE/GENESIS model was calibrated for Raccoon Island

for a period preceding the initial construction of the breakwaters and for the period

following breakwater construction.

Based on the results of the two simulations, both series of structures are expected to

reduce shoreline erosion rates on the island. Furthermore, a preliminary costbenefit analysis shows that the island strategy would be more cost effective (i.e.,

have a lower cost/acre) if it includes a terminal groin or additional breakwaters.

The measures that were carried forward for Raccoon Island include segmented

breakwaters, a terminal groin at the west end of the island (to retard sand loss into

Caillou Bay), dune restoration, marsh creation, beach restoration, sand fencing,

vegetative plantings, and herbivory control.

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Whiskey Island: In conjunction with the GENESIS modeling effort used to assess

the breakwaters and terminal groin on Raccoon Island, the effectiveness of

segmented breakwaters placed off Whiskey Island was evaluated (Appendix L

Annex, Volume V). The modeling results indicated that the rate of shoreline erosion

would be reduced by the structures. However, a preliminary cost-benefit analysis

indicated that the additional benefits provided by the breakwaters could not be

justified by the additional costs associated with their construction. Since the

breakwaters considerably increased the cost/acre, they were eliminated as a

possible measure for Whiskey Island. Terminal groins were also eliminated

because they could cutoff sediment supply to Raccoon Island.

The measures that were carried forward for Whiskey Island include dune

restoration, marsh creation, beach restoration, sand fencing, vegetative plantings,

and herbivory control.

Trinity/East Islands: The PDT concluded that the combination of beach, dune,

and marsh restoration was the best mechanism for protecting most of Trinity/East

Islands, but again emphasized shifting the template gulfward. The team stressed

the importance of marsh creation behind the newly restored Trinity/East Islands, to

buffer the north side of the island from wind-driven waves moving across

Terrebonne Bay from the north and northeast and help anchor the beach/dune

system by providing a marsh platform to hold overwash sand and retain it in the

island profile.

The measures that were carried forward for Trinity and East Islands include dune

restoration, marsh creation, beach restoration, sand fencing, and vegetative

planting. Based on the results of the modeling efforts for Whiskey Island, it was

inferred that segmented breakwaters would not be cost effective on Trinity or East

Island; therefore, they were eliminated from further consideration. Terminal groins

were also eliminated because they could cutoff sediment supply to Whiskey and

Raccoon Islands.

Wine Island: Historically, Wine Island was the easternmost of the Isles Dernieres.

It was approximately 3 miles in length and located across the mouth of the present

Wine Island/Cat Island Pass (Penland, et al., 2005). By the mid-twentieth century

the island had migrated north and slowly disappeared. What is now called Wine

Island is a rock-stabilized dredge material disposal site, associated with the HNC

(Channel). The island is no longer contained within the revetment. Its area has

been reduced, and its footprint has migrated north such that about one-third of it

presently lies outside the ring of rocks.

The team investigated two courses of action regarding Wine Island. The first

involves restoring the island within the boulder revetment through beneficial use of

sediment dredged from the HNC. The second would be a much more ambitious

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project, involving development of a restoration template anchored at the present

island location and extending to the adjacent shoal, referred to locally as the

Monkey Bar, to create a larger island. The measures that were carried forward for

Wine Island include repair of the existing continuous revetment, dune restoration,

marsh creation, beach restoration, sand fencing, vegetative plantings, and herbivory

control.

Timbalier Island: The measures that were carried forward for Timbalier Island

include dune restoration, marsh creation, beach restoration, sand fencing,

vegetative plantings, and herbivory control. Based on the results of the modeling

efforts for Whiskey Island, it was inferred that segmented breakwaters would not

be cost effective on Timbalier Island; therefore, they were eliminated from further

consideration.

During field visits to Timbalier Island, the PDT observed evidence of sediment

accumulation at the western end of the island. Therefore, it was determined that a

terminal groin would not be needed on the island.

East Timbalier Island: East Timbalier Island is the site of an oil and gas

production and processing facility. Much of the island was in imminent danger of

disappearing when its two CWPPRA projects were implemented. The proposed

island restoration template includes the presently submerged eastern half of the

island. The PDT investigated previous attempts to stabilize East Timbalier Island.

Several series of boulder revetments were place on the shoreline in the past. The

gulfside rocks are now several hundred feet offshore, and the rock placed along the

north shoreline is apparently buried within the island. Due to the lack of

effectiveness of the hard structures that have been implemented for past CWPPRA

projects, the PDT determined that breakwaters would not an effective measure for

East Timbalier and, thus, eliminated them from future consideration.

The measures that were carried forward for East Timbalier Island include dune

restoration, marsh creation, beach restoration, sand fencing, vegetative plantings,

and herbivory control.

Results

Table 6-5 summarizes the island strategies that were carried forward for each

island. These island strategies will be combined and paired with various

combinations of borrow areas to form alternatives.

Table 6-5: Summary of Potential Island Strategies

Description of

Island Strategy

a

Raccoon Whiskey Trinity East Wine Timbalier East

Timbalier

Beach / dune /

marsh Yes b Yes Yes Yes Yes Yes Yes

Beach / dune / Yes No No No No No No

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marsh w/

segmented

breakwaters

Beach / dune /

marsh w/ terminal

groin

b

Yes bNo No No No No No

Marsh creation w/

continuous

revetment

No c

No No No Yes No No

a “Yes” indicates the island strategy was carried forward; “No” indicates the island strategy was screened out.

b Combination includes sand fencing, vegetation planting, and herbivory control.

c Combination includes vegetation planting and herbivory control.

6.4.2.2 Screening/Evaluation of Borrow Areas

Since the LCA TBBSR Project would require a sediment source to accomplish some

of the measures evaluated, borrow areas were also screened and evaluated during

the planning process. Khalil et al. (2010) mapped numerous potential sediment

borrow areas along the Louisiana Gulf coast, from South Pass west to Sabine Pass.

Six large-volume areas were delineated off the Terrebonne Basin Barrier Islands.

Three of these are on the OCS, and three are in state waters, closer to shore. The

latter included a group of five small borrow areas associated with a Timbalier

Island project, three north of the island, in the bay, and two to the south. The PDT

used a combination of physical, geographic, and socioeconomic characteristics to

evaluate these borrow areas. Results of the final screening effort are summarized

in Table 6-6 and Figure 6-4.

Resulting Borrow Areas

The initially proposed source of borrow sand for beach and dune restoration was

Ship Shoal, an elongate sand body in the Gulf, located 20 to more than 40 miles

west of Belle Pass and 4 to 10 miles south of the Isles Dernieres. Ship Shoal is the

nearest, accessible sand source that contains a sufficient quantity of sand of

appropriate quality to match the native sand found on the islands and achieve the

project goals. Borrow Areas 6 and 7 are located on Ship Shoal.

The proposed sources of borrow sediments for marsh creation and restoration have

also been identified. Nearshore resources seaward of the depth of closure will be

utilized to provide mixed sediments consisting of fine sand, silts, and clays

compatible with the existing island framework. The two marsh sediment borrow

areas are the Raccoon Island TE-48 Borrow Area 5 and the overburden stratum on

Subarea 3a of the Whiskey Island TE-50 Borrow Area 3.

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WRDA 2007 Section 7006(e)(3) 6-43 October 2010 Table 6-6: Final Level Borrow Area Screening Cultural Resources Chirp, magnetic, and side scan sonar surveys (Ocean Surveys, 2006) Vibracore & magnetic surveys Remote sensing side scan & mag surveys (Goodwin, 2008) Seismic, sonar, and mag surveys (USEPA, 2003b) Seismic, sonar, and mag surveys (USEPA, 2003a); Echosounder and vibracore surveys & sediment sampling analysis (STE, 2004) Seismic, sonar, and mag surveys (USEPA, 2003a)

a Available volume based upon personal communication (Khalil, , A2009)b Excludes a volume of 1MCY estimated for Raccoon Island TE-48 Projectc

Available

Volume

(MCY)

Excludes a volume of 7MCY estimated for Caminada Headland Restoration Project

7.974.72

2.52.4

a

21.3

b

17.3

c

47.5

Sediment

Composition

20% sand; 30-

49.7% silt;

27.4-68.7% clay

80% sand

-

16.5-24.6%

above #200

sieve

< 5% silt< 5% silt< 5% silt

Thickness of

Sediment

Source (ft)

3.5–17.4

2.5–14

6

10–2013–2010–19

8–12

Applicability

Marsh

Beach/dune

Beach/dune

Marsh

Beach/dune

Beach/dune

Beach/dune

Sediment Type

Mixed, silt, clay

(overburden)

SandSand

Mixed sand, silt,

clay

SandSandSand

Location

Whiskey IslandTE-50 Area 2(subarea 3a)New Cut TE-37AreaRaccoon IslandTE-48South PeltoBlocks 12 & 13Ship Shoal Block88Ship ShoalBlocks 84, 85,98, & 99

ID

34567

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6.4.3 Preliminary Alternative Plans

An alternative is defined as a combination of island strategies and borrow areas.

The feature configurations that were carried forward from the third level of

screening include the following:

Raccoon Island: Beach/Dune/Marsh

Raccoon Island: Beach/Dune/Marsh w/ Segmented Breakwaters

Raccoon Island: Beach/Dune/Marsh w/ Terminal Groin

Whiskey Island: Beach/Dune/Marsh

Trinity Island: Beach/Dune/Marsh

East Island: Beach/Dune/Marsh

Wine Island: Marsh Creation w/Continuous Revetments

Timbalier Island: Beach/Dune/Marsh

East Island: Beach/Dune/Marsh

These island strategies were selected because they would be consistent with the

USACE EOPs, present the fewest constraints, and (are) synergistic with other

existing and authorized projects on the islands.

The borrow areas that were carried forward from the third level of screening include

the following:

Whiskey Island TE-50 - Area 3a (marsh material)

New Cut TE-37 (beach/dune material)

Raccoon Island TE-48 (marsh material)

South Pelto (beach/dune material)

Ship Shoal (beach/dune material)

The borrow areas were selected because they were outside the depth of closure of

the alternative cross sections, had adequate capacity of compatible material, and

had no cultural resource impediments.

Five restoration plans, denoted as Plans A through E, were developed as the next

step of plan formulation. The five restoration plans included the No Action

Alternative, a minimum design plan, and scalar variations of the minimum design.

No Action Plan (Plan A) - Future Without Project

Plan A represents the No Action plan; that is, no sediment is imported to

restore the islands components (i.e., beach, dune, and marsh) and no

restoration actions would be taken. The No Action plan is synonymous with

future without project conditions. This plan as identified as Alternative 1 in

subsequent sections.

Minimum Design Plan (Plan B)

The restoration template for Plan B provides for the minimal geomorphologic

form and ecologic function on each island and retains this form and function

after being subjected to a number of design storms.

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o Geomorphologic Form and Ecologic Function: The barrier islands are

typically low lying and composed of three physical features, the beach, dune,

and back barrier marsh. They act as a buffer to reduce the full force and

effects of wave action, saltwater intrusion, storm surge, and tidal currents on

associated estuaries and wetlands. To increase the longevity of the island’s

geomorphologic form and provide this buffer involves reinforcing the

shoreline through beach and dune restoration. In addition, it includes

providing a marsh platform to capture overwash sediments during episodic

events, sediment that would otherwise be carried into back bay areas to form

shoals or be lost into deeper waters. The marsh also serves as a roll over

platform as the islands migrate landward. Restoration of ecologic function of

the barrier islands includes vegetating both the restored dunes and back

barrier marsh platforms with native plants to provide wetland habitat for a

diverse number of plant and animal species and to help retain sediment.

Basic geomorphologic form and ecologic function were defined through

analysis of historic planforms and elevations and storm erosion modeling

such that the restored island retains this form and function after being

subjected to selected design storms. The design storms that were used in

template development included a hypothetical 50-year storm as well as the

varying intensities, durations, and approach paths of Hurricanes Katrina and

Rita, which occurred in 2005, and Hurricanes Gustav and Ike, which occurred

in 2008. SBEACH, a widely accepted cross-shore sediment transport model,

was utilized for predicting storm-induced beach and dune erosion. The

model’s use is considered standard practice both in the United States and

internationally as evidenced by the many documented applications in

professional journals and conference proceedings. The assumptions utilized

in the modeling program along with verification of use of the model are

presented in the Annex of Appendix L, Volume V. The minimum design plan

consists of a beach/dune component and a marsh component.

Beach and Dune Component: Based on historical natural

beach and dune elevations, and SBEACH simulations that were

performed on an array of various restoration plans to examine

storm-induced beach and dune erosion, the following design

criteria for Plan B were derived:

Gulf-side beach width: 250 ft

Beach elevation: 3.8 ft NAVD88

Dune width: 100 ft

Dune elevation: 6.0 ft NAVD88

Bay side beach width: 100 ft

Marsh Component: Based on the poststorm observations from

the recent historic storms, there is ample evidence that the back

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barrier marsh width needs to be approximately 1,000 ft to

capture overwash sediments during episodic events.

Examination of aerial photographs of the Texas coast, made

following Hurricane Ike, shows areas of overwash extending

from 800 to 1,300 ft inland (Ewing et al., 2009). An extensive

study of overwash on the Caminada-Moreau Headland by

Ritchie and Penland found that, for much of the low shoreline,

overwash penetrated from 700 to more than 1,000 ft beyond the

beach (Ritchie and Penland, 1989). Therefore, 1,000 ft was

defined as the design criteria for the minimized restoration

template for the marsh platform width.

Based on similar Louisiana barrier island restoration

plans, the average healthy marsh elevation, defined as

the target elevation for the marsh platform, is typically

within +/- 0.1 ft of Mean High Water (MHW). MHW for

the Study Area is approximately 1.6 ft NAVD88 and was

defined as the design criteria for the minimized design

plan for the marsh platform elevation.

Design Plan Scalars (Plans C through E)

Plans C through E are scalars of Plan B that incorporate incremental

increases in the scales of beach, dune and marsh planforms and elevations to

provide plan formulators the ability to determine the optimal increment for

restoration of the geomorphologic form and ecologic function of these islands.

Plan C provides for the minimal geomorphologic form and ecologic function

on each island along with 5 years of advanced fill. Plan D provides for the

minimal geomorphologic form and ecologic function on each island along with

10 years of advanced fill. Plan E provides for the minimal geomorphologic

form and ecologic function on each island along with 25 years of advanced fill.

The IWR Planning Suite was used to determine the most cost effective combination

of island scales and alternatives. This process assisted planners in identifying the

plans which are best financial investments.

The WVA model is undergoing model certification in accordance with EC 1105-2-

407. The model has undergone external review, and the WVA revision

documentation and spreadsheets have been submitted to the ECO-PCX. The ECOPCX 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

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specific project. The specific comments and responses for the WVA as it relates to

this project can be found in Appendix K of Volume V.

6.4.4 Identification of the Intermediate Array of Alternatives

Of the 243,750 plans that were generated by the IWR Planning Suite, 10 were

carried forward for additional analysis. Five of the plans were selected because

they were the five most cost effective Best Buy plans. Best Buy Plan #5 was

selected as the cutoff point because the incremental increase in output between Best

Buy Plan #5 and #6 was relatively small compared to the incremental increase in

cost required for the additional output. All other Best Buy and cost effective plans

were eliminated. The remaining plans in the intermediate array were multi-island

combinations that provided additional benefits that were worthy of consideration

and, thus, were carried forward for further analysis.

The rationale for advancing these multi-island alternatives is based on a systemwide approach of restoring as many of the islands within the Terrebonne Basin

barrier system as possible. Based upon the results of the plan formulation analyses

and screening, 10 alternatives were included in the intermediate array of

Alternatives. The intermediate array is shown in Table 6-7.

Table 6-7: Intermediate Array of Alternatives

No. Name Description

1 No Action (Plan A) This alternative does not include any restoration.

2 Timbalier (Plan E) Restoration of Timbalier Island to its minimal geomorphologic

form and ecologic function along with 25 years of advanced fill

3

Whiskey (Plan C) /

Timbalier (Plan E)

Restoration of Whiskey Island to its minimal geomorphologic form

and ecologic function along with 5 years of advanced fill combined

with restoration of Timbalier Island to its minimal geomorphologic

form and ecologic function along with 25 years of advanced fill

4

Whiskey (Plan C) /

Trinity (Plan C) /

Timbalier (Plan E)

Restoration of Whiskey and Trinity Islands to their minimal

geomorphologic form and ecologic function along with 5 years of

advanced fill combined with restoration of Timbalier Island to its

minimal geomorphologic form and ecologic function along with 25

years of advanced fill

5 Raccoon with TG

(Plan E) /

Whiskey (Plan C) /

Trinity (Plan C) /

Timbalier (Plan E)

Restoration of Whiskey and Trinity Islands to their minimal

geomorphologic form and ecologic function along with 5 years of

advanced fill combined with restoration of Raccoon and Timbalier

Islands to their minimal geomorphologic form and ecologic

function along with 25 years of advanced fill and construction of a

terminal groin on the western end of Raccoon Island

6 Raccoon (Plan B) /

Whiskey (Plan B) /

Trinity (Plan B)

Restoration of Raccoon, Whiskey, and Trinity islands, all to their

minimal geomorphologic form and ecologic function

7 Raccoon with BW

(Plan B) /

Whiskey (Plan B) /

Trinity (Plan B)

Restoration of Raccoon, Whiskey, and Trinity Islands, all to their

minimal geomorphologic form and ecologic function, along with

construction of 8 additional breakwaters on the western end of

Raccoon Island.

8 Raccoon with TG (Plan Restoration of Raccoon, Whiskey, and Trinity islands, all to their

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B) / Whiskey (Plan B) /

Trinity (Plan B)

minimal geomorphologic form and ecologic function, along with

construction of a terminal groin on the western end of Raccoon

Island

9 Raccoon (Plan B) /

Whiskey (Plan B) /

Timbalier (Plan B)

Restoration of Raccoon, Whiskey, and Timbalier islands, all to

their minimal geomorphologic form and ecologic function

10 Raccoon (Plan B) /

Trinity (Plan B) / East

(Plan B) / Whisky (Plan

B) / Timbalier (Plan B) /

East Timbalier (Plan B)

/ Wine (Plan B)

Restoration of Raccoon, Whiskey, Trinity, East, Wine, Timbalier,

and East Timbalier Islands, all to their minimal geomorphologic

form and ecologic function

After identification of the intermediate array of alternatives, the alternatives were

compared based on benefits, costs, and environmental consequences. The results of

the WVA analysis, measured in AAHUs, were compared to cost data to provide a

measure of effectiveness of a proposed alternative in terms of annualized cost per

AAHU gain. The HUs resulting from the future without and future with project

scenarios are annualized (averaged over the project life) to determine AAHUs. The

difference in AAHUs between the two scenarios represents the net benefits

attributable to the project in terms of habitat quality and quantity.

Alternative 5 (Raccoon with Terminal Groin Plan E, Whiskey Plan C, Trinity Plan

C, and Timbalier Plan E, was identified as the NER plan. The NER Plan would add

3,283 acres of habitat to the existing island footprints, increasing the total size of

the islands to 5,840 acres. However, the NER plan cannot be constructed within

the WRDA 2007 authorization. In order to identify a plan that could be constructed

within the authorization, additional analyses were conducted. Trinity Plan C and

Whiskey Plan C can be constructed within the WRDA authorization and were added

to the intermediate array.

From the intermediate array, Alternatives 6, 7, 8, and 10 were not cost effective

and, therefore, not carried forward for further analysis. Alternative 9 was also

removed from further analysis because the cost per AAHU was significantly (14%)

higher than Alternative 2 and it fell above the efficient frontier curve. Alternative

11, Whiskey Island was chosen for further analysis due to a number of qualitative

benefits such as a rare mangrove habitat and pelican habitat located on the island.

The resulting final array included five alternatives: Alternatives 2, 3, 4, 5, and 11.

6.4.5 Environmental Consequences *

The potential environmental consequences of implementing the No Action

Alternative and Alternatives 2, 3, 4, 5, and 11 were considered for restoration of the

Terrebonne Basin Barrier Shoreline. A comparison of the direct, indirect, and

cumulative impacts of all alternatives were considered.

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The No Action Alternative is considered to be the same as the future without project

condition and analyzes the future conditions of the resource over a 50-year period of

analysis (2012-2062). The analysis compares the No Action Alternative to five

alternatives carried over from the final array for detailed analysis.

No Action Alternative: Without Federal action, the barrier island habitat within

the Terrebonne Basin will continue to be subjected to the factors and processes that

are contributing to the loss of the Timbalier and Isles Dernieres barrier islands.

These processes will result in continued degradation of barrier beach, dune and

marsh within the Study Area; a reduction in marsh and dune, vegetation,

hydrologic connectivity; and a transition toward open water habitat.

Land loss along the Terrebonne Basin barrier shoreline would likely continue at

current rates, resulting in the projected loss of 3,220 acres of existing Terrebonne

Basin barrier island beach, dune, and intertidal wildlife habitats to marinedominated open water bottom habitat over the 50-year period of analysis.

Continuing erosion would allow higher salinity from Gulf of Mexico waters to

invade the lower salinity interior wetlands and the estuarine gradient. Changes in

the tidal prism would result in increased land loss and conversion of the estuarine

system to a more marine system. Storm surge will then reach further inland with

the absence of these barrier islands resulting in an increase in erosion along inland

marshes.

The ongoing conversion of existing fragmented emergent wetlands to shallow open

water would have indirect adverse impacts on coastal vegetation, fish and wildlife

resources, EFH, threatened and endangered species, recreation, and aesthetic and

socioeconomic resources. Continued fragmentation and deterioration of barrier

island habitat quality, conversion of marsh and barrier habitats to open water, and

the dwindling availability of suitable barrier and marsh habitats for use by wildlife

are expected to result in a general decline of wildlife populations throughout the

Study Area.

Habitat change will modify recreation opportunities (i.e., fresh to marine) and may

impact facilities that specialize in services to particular types of recreation (i.e., loss

of freshwater opportunities). Another major impact of barrier island and land loss

in general is the possible loss of facilities (through submergence) and infrastructure

that support or are supported by recreational activities.

Alternative 5: Compared to the No Action Alternative, implementation of

Alternative 5 would initially restore a total of 5,840 acres on Raccoon, Whiskey,

Trinity, and Timbalier Islands including a total of 472 acres of dune, 4,320 acres of

supratidal (beach), and 1,048 acres of intertidal (marsh) wildlife habitats for use by

various wildlife species.

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Initial construction would remove a total of 55,787,481 CY of borrow material from

a total of 2,498 acres of water bottoms in the offshore borrow areas. Renourishment

would remove a total of 23,639,786 CY from a total of 1,222 acres of water bottoms

in offshore borrow areas. Initial construction would cover a total of 3,283 acres of

water bottoms and existing fragmented barrier habitats. Renourishment would

directly cover 71 acres at TY30 on Raccoon Island, 474 acres at TY20 and 349 acres

at TY40 on Whiskey Island; 537 acres on Trinity Island at TY 25; and 202 acres on

Timbalier Island at TY30. Construction of the terminal groin on Raccoon Island

would result in 2 acres of these existing shallow water bottoms to be permanently

unavailable for use by wildlife.

Restoration of four barrier islands, combined with interior marsh creation and

restoration measures, would widen the islands sufficiently to prevent breach

formation, thereby reducing formation of additional tidal passes, as well as closing

existing breaches and over wash areas. An undetermined reduction in tidal prism

would also result. These different restoration measures would act together to

retard saltwater intrusion into more northern portions of the Terrebonne Basin.

Generally, Alternative 5 would have cumulative, positive impacts on fish and

wildlife resources, channel maintenance, and recreation.

Direct impacts would include temporary disruption of hydrologic connectivity

between the wetland creation and nourishment sites, bays, and Gulf of Mexico;

temporary and/or minor impacts to water quality, if any; and negligible effects on

salinity levels. Short term and minor water quality impacts primarily during

construction e.g., increased turbidity, decreased dissolved oxygen associated with

placement of dredged material. Alternative 5 would probably not adversely impact

brown pelican or piping plover or piping plover critical habitat; no other threatened

or endangered species or their critical habitat would be impacted.

Alternative 11: Impacts resulting from the implementation of Alternative 11 are

similar to impacts from Alternative 5 except that Alternative 5 would restore only

Whiskey Island and improve a total of 1,272 acres. This alternative would restore

65 acres of dune, 830 acres of supratidal (beach), and 377 acres of intertidal (marsh)

habitat at initial construction. Initial construction would remove a total of

10,340,701 CY of sediments from a total of 535 acres of borrow site water bottoms.

Renourishment would remove a total of 16,599,548 CY of borrow material from a

total of 859 acres at Ship Shoal - 7; with 9,413,143 CY removed from 487 acres at

TY20 and 7,186,405 CY from 372 acres at TY40. Initial construction would cover

approximately 469 acres of water bottoms and fragmented barrier habitats.

Renourishment with borrow material from Ship Shoal - 7 would directly impact a

total of 474 acres and 349 acres of water bottoms and fragmented barrier habitats

at TY20 and TY40, respectively.

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Generally, Alternative 11 would have cumulative, positive impacts on fish and

wildlife resources, channel maintenance, and recreation in the area; however, those

impacts are on a smaller scale since only one island would be restored. Indirect

impacts would include an improvement in wildlife and aquatic habitat, the

regeneration of marsh and dune vegetation, and increased nutrient and sediment

transport.

The restoration of Whiskey Island, which is the island located closest to the

mainland marsh, will provide some storm surge protection for the interior marshes

to the north and west, which will decrease erosion rates. Alternative 11 would

protect, create, and nourish transitional estuarine wetlands. These transitional

estuarine wetlands would provide important and essential fish and wildlife habitats

that would contribute to restoring the base of organisms used for recreational

activities such as fishing and camping. The implementation of Alternative 11 would

also increase sediment availability to Raccoon Island because the long shore

sediment movement is westward.

Direct impacts would include temporary disruption of hydrologic connectivity

between the wetland creation and nourishment sites, bays, and Gulf of Mexico;

temporary and/or minor impacts to water quality, if any; and negligible effects on

salinity levels. Short term and minor water quality impacts would occur primarily

during construction e.g., increased turbidity, decreased dissolved oxygen associated

with placement of dredged material. Alternative 11 would probably not adversely

impact brown pelican or piping plover or piping plover critical habitat; no other

threatened or endangered species or their critical habitat would be impacted.

Alternative 2: Impacts resulting from the implementation of Alternative 2 would

be similar to those described for Alternative 5, except 2,630 acres would be restored

on Timbalier Island with 215 acres of dune, 2,346 acres of supratidal, and 69 acres

of intertidal wildlife habitat.

Direct impacts of implementing Alternative 2 would be similar to those described

for Alternative 11. Initial construction would remove a total of 25,214,803 CY of

sediments from a total of 1,375 acres of borrow site water bottoms. Renourishment

at TY30 would remove a total of 531,329 CY of borrow material from, 26 acres at

South Pelto - 6 borrow site. Initial construction would cover approximately 1,675

acres of existing water bottoms and fragmented barrier habitats. Renourishment at

TY30, with borrow material from South Pelto - 6, would directly impact a total of

202 acres of water bottoms and fragmented barrier habitats.

Alternative 3: Impacts resulting from the implementation of Alternative 3 would

be similar to those described for Alternative 5 except 3,902 acres would be restored

on Whiskey and Timbalier Islands with 280 acres of dune, 3,176 acres of supratidal,

and 446 acres of intertidal habitat during initial construction.

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Direct impacts of implementing Alternative 3 would be similar to those described

for Alternative 11. Initial construction would remove a total of 35,381,587 CY of

borrow material from a total of 1,535 acres of water bottoms in the offshore borrow

areas. Renourishment would remove a total of 17,130,877 CY from a total of 885

acres of water bottoms in offshore borrow areas. Initial construction would cover a

total of 2,144 acres of water bottoms and existing fragmented barrier habitats.

Renourishment would directly cover 474 acres at TY 20 and 349 acres at TY30 on

Whiskey Island and 202 acres on Timbalier Island at TY40.

Alternative 4: Impacts resulting from the implementation of Alternative 4 would

be similar to those described for Alternative 5 except 5,051 acres would be restored

on Whiskey, Trinity, and Timbalier Islands with 409 acres of dune, 3,632 acres of

supratidal, and 1,010 acres of intertidal habitat during initial construction.

Initial construction would remove a total of 44,544,496 CY of borrow material from

a total of 1,998 acres of water bottoms in the offshore borrow areas including 803

acres at Ship Shoal - 7; 613 acres at the South Pelto - 6; 39 acres at Raccoon Island -

5; 147 acres at New Cut - 4; and 396 acres at Whiskey Area - 3. Renourishment

would remove a total of 21,440,567 CY from a total of 1,108 acres of water bottoms

in offshore borrow areas including 26 acres at South Pelto - 6 and 1,082 acres at

Ship Shoal - 7. Initial construction would cover a total of 2,729 acres of water

bottoms and existing fragmented barrier habitats. Renourishment would directly

cover 474 acres at TY 20 and 349 acres at TY40 on Whiskey Island; 537 acres on

Trinity Island at TY 25; and 202 acres on Timbalier Island at TY30.

6.4.6 Comparison of Alternative Plans

In order to determine the recommended plan, a separate CE/ICA was conducted on

the 5 alternatives in the final array using the IWR Planning Suite. The cost of each

alternative was refined to more accurately reflect the borrow area configuration

used by the island combination. Additionally, the benefits for ecosystem function

were refined for the final alternatives using the WVA methodology. Alternatives

costs and benefits are included in Table 6-8 and Table 6-9.

6.4.7 National Ecosystem Restoration Plan

Alternative 5 (Raccoon with Terminal Groin Plan E, Whiskey Plan ,Trinity Plan C,

and Timbalier Plan E) was selected as the NER plan because it is a Best Buy plan

that fulfills the planning objectives of this project. The NER plan would restore the

geomorphologic form and ecologic function of the four islands in the Terrebonne

Basin barrier system. Immediately after construction (TY1), the NER plan would

add 3,283 acres of habitat (dune, intertidal, and supratidal) to the existing island

footprints of Raccoon, Whiskey, Trinity, and Timbalier Islands, increasing the total

size of the islands to 5,840 acres.

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WRDA 2007 Section 7006(e)(3) 6-54 October 2010 Table 6-8: CE/ICA for Intermediate Array of Alternatives Total Annualized Investment$0 $8,710,000 $12,640,000 $16,820,000 $20,830,000 $9,040,000 $9,280,000 $9,190,000 $10,160,000 $22,420,000 $4,070,000 $4,160,000

a Preliminary costs were developed for planning purposes only. Cost estimate is not the fully funded cost.b

Annualized

Cost

Alternatives 11 and 12 were added in the final analysis to determine the project recommended plan.

$0

$8,370,000

$12,300,000$16,480,000$20,470,000

$8,700,000$8,910,000$8,820,000$9,820,000

$22,080,000

$3,730,000$3,820,000

Annualized

Monitoring Cost

$0

$260,000$260,000$260,000$260,000$260,000$260,000$260,000$260,000$260,000$260,000$260,000

Annualized

OMRR&R

$0

$80,000$80,000$80,000

$110,000

$80,000

$110,000$110,000

$80,000$80,000$80,000$80,000

Cost

$0

a

$170,000,000$247,000,000$329,000,000$408,000,000$177,000,000$182,000,000$180,000,000$199,000,000$439,000,000

$73,000,000

$74,800,000

Alternatives

123456789

10

1112

bb

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0

$195,000$133,000$212,000$185,000

N/AN/AN/A

$1,530,000

N/A

$202,000$613,000

a Maximum number of islands constructible with cleared sediment sources

b System-wide Barrier Island Restoration

c

Annualized

Cost/HU

Alternative s11 and 12 were added in the final analysis to determine the project recommended plan.

0

$10,000$10,120$10,280$10,100$11,510$11,490$11,470$11,420$12,170$10,738$10,749

Best Buy

YesYes

Yes

aaaa

***

b

***

CostEffective

YesYesYesYesYes

NoNoNo

Yes

No

YesYes

Cost

($1,000)

0

$170,000$247,000

$329,000$408,000$177,000$182,000$180,000

$199,000

$439,000

$76,600$81,500

AAHUs

0

871

1,2501,6372,063

785808801890

1,842

379387

Alternatives

123456789

10

11

12

cc

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This would result in the restoration and creation of approximately 472 acres of

dune, 4,320 acres of supratidal habitat, and 1,048 acres of intertidal habitat. The

initial construction of the NER plan would generate 2,063 AAHUs.

The creation of dune, supratidal, and intertidal habitats would provide essential

habitats for fish, migratory birds, and other terrestrial and aquatic species. The

project would also increase sediment input to supplement longshore sediment

transport processes along the Gulf shoreline by mechanically introducing

compatible sediment and increasing the ability of the restored area to continue to

function and provide habitat with minimum continuing intervention. Sediment

placed on Trinity Island would eventually be transported to Whiskey Island and

Raccoon Island as the sediment moves westward through the system. Raccoon

Island would also receive sediment directly from Whiskey.

The NER plan was also selected because it would protect existing critical habitat on

Raccoon and Whiskey Islands. Raccoon Plan E and Whiskey Plan C were designed

to avoid approximately 58 and 286 acres of existing mangroves on the islands,

respectively. This was done in order to minimize potential adverse the ecologic

impacts during construction. These two islands are also considered to be valuable

wildlife habitats (Isles Dernieres Barrier Islands Wildlife Refuge) and the LDWF is

reestablishing a pelican rookery on Whiskey Island; consequently, maintaining

adequate areas of healthy beach, dune, and marsh is particularly important.

Raccoon, Whiskey, Trinity, and Timbalier are also a critical habitat for endangered

species including the piping plover and are a valuable stopover habitat for

migratory birds.

In addition to protecting and maintaining precious ecological benefits, the NER plan

would complement existing CWPPRA projects on the island. For example, Whiskey

Plan C was designed to complement TE-50, which is an existing CWPPRA project

that was constructed in 2009. TE-50 created approximately 316 acres of intertidal

back-barrier marsh between the two existing mangrove stands. Restoration of the

beach and dune gulfward of TE-50 would complement the existing CWPPRA

investment.

Raccoon Plan E was designed to complement two separate CWPPRA projects, TE-29

and TE-48. The TE-29 project, which was completed in July 1997, included the

construction of eight segmented breakwaters along the eastern end of the island.

The TE-48 project consists of two phases. Phase A, which included the construction

of eight additional segmented breakwaters and a terminal groin, was completed in

September of 2005. The terminal groin, which was constructed on the eastern end

of the island, was intended to prevent longshore currents from scouring

accumulated sediment behind the breakwater field. Phase B, which is currently in

the preconstruction phase, would include the construction of a 53-acre marsh along

the backside of the island. The resilience of Raccoon Island Plan E is partially due

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to the existing breakwaters from both CWPPRA projects. The NER plan would help

protected the marsh that would be constructed as part of TE-48.

The existing mangrove stands and CWPPRA projects on Raccoon and Whiskey

Island can be avoided without undermining the project proposed action because

they are the only areas of sufficient elevation to complement the design template

and to contribute to the geomorphologic form and ecologic function of the islands.

Avoidance of other pockets of existing habitat could potentially undermine the

project by providing “weak spots” in the template. These areas could be more

susceptible to breaching and could accelerate erosion. Therefore, the remaining 124

acres of habitat on Raccoon Island and 201 acres on Whiskey Island would be

covered with fill material during construction of the template (i.e. at TY1). Existing

habitat on Trinity and Timbalier Islands cannot be avoided without undermining

jeopardizing the proposed project. Therefore, the entire footprints of both islands

(564 acres on Trinity and 955 acres on Timbalier) would be covered with fill

material, but these areas would be restored through the vegetative planting efforts

immediately following construction.

The preliminary cost estimates that were used when evaluating the intermediate

array were refined for the NER plan using the MII to develop a baseline project cost

for initial restoration. Based on these refinements, the resulting fully funded cost of

the NER was determined to be $689,000,000 without renourishment. The nonFederal sponsor fully supports Alternative 5 as the NER plan under the current

authorization. The fully funded cost is provided in Table 6-10.

Table 6-10: Fully Funded NER Plan Cost Summary

Project Element Fully Funded Total

Lands and damages $751,000

Fish and wildlife

(Adaptive Management Plan) $5,820,000

Breakwaters and seawalls $2,494,000

Beach replenishment $619,000,000

PED $30,000,000

Construction management $31,000,000

NER initial restoration

fully funded costs $689,000,000 a

a

For the purposes of applying the cost index to the WRDA authorized cost, each project was

adjusted for inflation from the October 2006 price levels through the projected midpoint of project

construction.

Renourishment costs, including the mobilization/demobilization events and the cost

of dredging the sediment, were later added to the fully funded costs to determine

the ultimate cost of the NER. Based on a total renourishment cost of approximately

$557,000,000, the fully funded cost for the NER with renourishment is

approximately $1,246,000,000.

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The non-Federal sponsor supports the NER plan; therefore, no separate LPP is

identified. The NER plan is also identified as the EPP since it maximizes the

environmental benefit.

6.4.7.1 Renourishment

The initial plan formulation process focused on the identification of the alternative

which provided the best performance in the absence of future enhancements. Based

on initial construction costs and benefits, Alternative 5 was determined to be a Best

Buy and was identified as the NER plan. However, none of the alternatives

considered met the evaluation criteria of acceptability per ER 1105-2-100. More

specifically, none of the alternatives were found to provide a sustainable

environment and, subsequently, would not be capable of maintaining the project

objectives. Consequently, O&M in the form of renourishment was added to each of

the islands found in the intermediate array.

The PDT optimized the renourishment quantity and sequencing by determining the

minimum amount needed to maintain the geomorphic form and ecologic function of

the islands throughout the 50-year period of analysis. Only dune and supratidal

(beach) renourishment were included; intertidal (marsh) areas would receive no

additional sediment after construction. The amounts of sediment needed for

renourishment are described in terms of the original plans (Plans A through D)

used for analyses (see explanation of plans in Section 6.4.3) as shown in Table 6-11.

For example, Raccoon Island would be constructed to the Plan E template in TY1

and at TY30 the dune and supratidal (beach) area would be renourished with an

amount of sediment equivalent to Plan B.

Table 6-11: Renourishment Sequencing and Quantities

Island Plan Renourishment Year Renourishment Plan

Raccoon Plan E w/TG TY30 Restore Plan B

Whiskey Plan Ca TY20 Add Plan C

TY40 Add Plan B

Trinity Plan C TY25 Add Plan C

Timbalier Plan E TY30 Restore Plan B

a Whiskey Island would require two renourishment episodes with one occurring in TY20 and one

occurring in TY40

When compared to all other alternatives in the intermediate array with

renourishment, Alternative 5 with renourishment is still a Best Buy per the

CE/ICA. However, when each island with renourishment is incrementally analyzed

individually and in all possible combinations, other alternative combinations not

previously identified in the intermediate array provided cost effective solutions.

The identified NER plan falls within the uncertainty band of cost effective plans,

but not on the cost effective frontier. The major difference between the results of

the analysis of the intermediate array versus the analysis of the individual

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combination of islands is the effect of discounting the future costs of the

renourishment cycles. This results in alternatives with costs in the outlying years

appearing to be more cost effective than those alternatives with greater initial

construction costs. However, greater potential for, and certainty of, benefits is

attained in the initial construction. As a result, Alternative 5 remains the NER

plan.

6.4.7.2 Components

Whiskey Island Plan C proposes a dune height of +6.4 ft NAVD 88 with a dune

crown width of 100 ft. The dune elevation takes into account that there would be

approximately 0.4 ft of vertical adjustments (ESLR, subsidence, and compaction)

occurring during the first six months after construction. At the end of the sixmonth period, the dune should reach the design elevation of +6.0 ft NAVD 88. The

slopes of the beach and dune are set 60:1 and 30:1 (horizontal to vertical),

respectively. The marsh fill is proposed on the landward side of the dune at an

elevation of +2.4 ft NAVD 88. Although the design elevation for the marsh is +1.6 ft

NAVD 88, the marsh would be constructed at a higher elevation to account for

initial vertical adjustments. Immediately after construction (TY1), the Whiskey

Island Plan would add 469 acres of habitat (dune, intertidal, and supratidal) to the

existing island footprint, increasing the size of the island to 1,272 acres. Figure 6-5

shows Whiskey Island Plan C.

Trinity Plan C proposes a dune height of +6.4 ft NAVD 88 with a dune crown width

of 100 ft. The slopes of the beach and dune are set 60:1 and 30:1 (horizontal to

vertical), respectively. The marsh fill is proposed on the landward side of the dune

at an elevation of +2.5 ft NAVD 88, which is slightly higher than the dune elevation

at Whiskey. Due to the existing topography of Trinity Island, the required marsh

fill thickness is greater and, thus, results in a higher compaction rate. As with

Whiskey Island, the dune and marsh elevations account for vertical adjustments

occurring after the first six months of construction. Immediately after construction

(TY1), the Trinity Plan C would add 585 acres of habitat (dune, intertidal, and

supratidal) to the existing 564-acre island footprint, increasing the size of the island

to 1,149 acres. This includes 129 acres of dune, 456 acres of supratidal, and 564

acres of intertidal habitat. Figure 6-6 shows Trinity Island Plan C.

Raccoon Plan E proposes a dune height of +7.7 ft NAVD 88 with a dune crown

width of 100 ft. The dune elevation is considerably higher than that of Trinity and

Whiskey because the plan is design to withstand 25 years of additional back ground

erosion rather than just 5 years. Furthermore, the thickness of the 25-year plan

(Plan E) results in a higher compaction rate. The slopes of the beach and dune are

set 60:1 and 30:1 (horizontal to vertical), respectively. The marsh fill is proposed on

the landward side of the dune at an elevation of +3.7 ft NAVD 88. As with the dune

elevation, the marsh elevation is higher than that of Whiskey and Trinity because it

is designed withstand a longer duration of background erosion. Immediately after

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construction (TY1), the Raccoon Plan E would add 554 acres of habitat (dune,

intertidal, and supratidal) to the existing 235-acre island footprint, increasing the

size of the island to 789 acres. This includes 63 acres of dune, 688 acres of

supratidal, and 38 acres of intertidal habitat. Figure 6-7 shows Raccoon Island

Plan E.

For Raccoon Island, a terminal groin would also be constructed as part of the

restoration. The terminal groin would be approximately 1,200 ft long and 75 ft wide

and will be installed at the western terminus of the template to prevent sediment

migration out of the Isle Dernieres system.

Timbalier Plan E proposes a dune height of +7.1 ft NAVD 88 with a dune crown

width of 100 ft. The slopes of the beach and dune are set 60:1 and 30:1 (horizontal

to vertical), respectively. The marsh fill is proposed on the landward side of the

dune at an elevation of +3.2 ft NAVD 88. As with Raccoon Island Plan E, the

elevations of the plan are larger than that of Trinity and Whiskey because it is

designed to withstand a longer period of background erosion. Furthermore, the

larger plans are thicker and thus exhibit higher compaction rates. Immediately

after construction (TY1), the Timbalier Plan E would add 1675 acres of habitat

(dune, intertidal, and supratidal) to the existing 955-acre island footprint,

increasing the size of the island to 2,630 acres. This includes 215 acres of dune,

2346 acres of supratidal, and 69 acres of intertidal habitat. An access canal for an

active oil and gas facility was incorporated into the design of the template for

Timbalier Island. Figure 6-8 shows Timbalier Island Plan E.

Sustainability: The LCA TBBSR Study was identified in the LCA 2004 report as

a restoration feature that could be implemented in the near-term that addresses the

most critical needs of the Louisiana coastline. As indicated in the LCA 2004 report,

the design and operation of the LCA TBBSR Study feature would maintain the

opportunity for, and support the development of large-scale, long range

comprehensive coastal restoration. The Study is synergistic with future restoration

by maintaining or restoring the integrity of the estuaries’ coastline, upon which all

future restoration is dependent. The NER plan would work in concert with other

LCA projects such as BUDMAT, CWPPRA, and CIAP projects, in addition to other

current and future projects developed under the Louisiana Coastal Comprehensive

Plan, to improve the sustainability of the Terrebonne Basin barrier shoreline.

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WRDA 2007 Section 7006(e)(3) 6-61 October 2010 Figure 6-5: Whiskey Island Plan C

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WRDA 2007 Section 7006(e)(3) 6-62 October 2010 Figure 6-6: Trinity Island Plan C

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WRDA 2007 Section 7006(e)(3) 6-63 October 2010 Figure 6-7: Raccoon Island Plan E with Terminal Groim

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WRDA 2007 Section 7006(e)(3) 6-64 October 2010 Figure 6-8: Timbalier Island Plan E

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As a result of the LCA TBBSR Study, there is a substantial improvement in terms

of resource sustainability within the Study Area provided by the NER plan

compared to the future without project conditions. While much of the constructed

acreage created under the NER plan would decrease by the end of the period of

analysis, the net effect of the plan would be to prevent the loss of Raccoon, Whiskey,

Trinity, and Timbalier Islands. If no actions are taken, the remaining habitat acres

on Raccoon Island (239) and Whiskey Island (820 acres) are expected to disappear

by TY40 and TY31, respectively (i.e. all dune, supratidal, and intertidal habitat

would be gone). This includes the existing critical mangrove habitat and the backbarrier marsh created by CWPPRA project TE-48 on Raccoon and TE-50 on

Whiskey. The remaining habitat on Trinity Island (673 acres) would disappear by

TY40 and only 2 acres of intertidal habitat would remain on Timbalier at TY50.

The majority of this loss would be prevented with implementation of the NER plan.

The plan also meets the major restoration objectives of restoring the geomorphic

form and ecologic function of the barrier islands and of restoring and improving

essential habitats for fish, migratory birds, and other terrestrial and aquatic species

for the 50-year period of analysis. The restoration of the four islands would alter

the tidal prism, thereby reducing the formation of any additional tidal passes as

well as closing or narrowing existing passes and breaches, protecting and

preserving the interior marsh habitats which would quickly erode without the

protection of the sand shoreline.

6.4.7.3 Design, Environmental, and Construction Considerations

Project construction would require the hydraulic placement of beach and marsh fill

within the Study area. Inclement weather, especially tropical storms, may impact

the construction schedule. High seas may impact offshore dredging. Waves and

winds from storm events may also move debris, cultural resources, and pipelines on

the gulf floor. If during dredging, cultural resources are inadvertently discovered,

there could be impacts to the schedule and cost of the project. Additionally, dredge

availability may impact the schedule and cost of the project. The project could

potentially impact threatened and endangered species as well as species of special

interest. Therefore, all construction-related activities would be coordinated with

the USFWS as well as LDWF. During the PED process both the mechanics /

methodologies and phasing of fill placement would be analyzed and modified with

the goal to eliminate or minimize adverse impacts. The project team includes

ecologists and wildlife biologists who, in concert with agency scientists, would

endeavor to ensure the maintenance of habitat diversity and the stability of a

diverse assemblage of species. The primary metrics for this should be species

diversity and habitat area, to be evaluated during the monitoring and adaptive

management process. Specific measures to protect the endangered species

occurring in the area are detailed in Volume V.

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Project construction would require the hydraulic placement of beach and marsh fill

within the Study Area. Inclement weather, especially tropical storms, may impact

the construction schedule. High seas may impact offshore dredging. Waves and

winds from storm events may also move debris, cultural resources, and pipelines on

the gulf floor. If during dredging, cultural resources are inadvertently discovered,

there could be impacts to the schedule and cost of the project. Additionally, dredge

availability may impact the schedule and cost of the project. The project could

potentially impact threatened and endangered species as well as species of special

interest. Therefore, all construction-related activities would be coordinated with

the USFWS as well as LDWF. More details regarding the protection of threatened

and endangered species during construction is included in Volume V.

Beach and Dune Fill: It is anticipated that the contractor would use either a

hydraulic cutterhead dredge or a hopper dredge plant to excavate sand from the

cleared sand borrow areas. The sand would then be pumped through a series of

booster pumps or from the hopper discharge through a booster pump to the

beach/dune fill template via a submerged sediment pipeline. During construction

the contractor would be directed to maintain dedicated equipment

loading/unloading areas, staging areas, and access corridors to minimize the

impacts to the island. Existing mangrove habitats and prior restoration project

areas shall be avoided by construction equipment and construction-related

activities. Once on the beach, the sediment pipeline would run parallel to the

shoreline. Front-end loaders that are equipped with grapple arms would be utilized

in the placement and relocation of the sediment pipeline. In order to minimize the

impact on piping plover, the beach would be constructed in sections to allow the

birds to move to areas that are not currently under construction. The sand would

be worked on the beach by bulldozers to meet the specified template grades, slopes

and widths.

Back-Barrier Marsh Fill: The contractor would use a hydraulic cutterhead

dredge and booster pump(s) to excavate sediment from the cleared offshore marsh

borrow area(s) and directly transport it via a submerged sediment pipeline to the

marsh platform. Sediment used to construct the marsh containment dikes would be

dredged from existing material inside the marsh creation area rather than from

offshore borrow areas. These operations would be done in a manner that would

minimize turbidity. Discharge and dewatering from the marsh fill shall typically be

directed towards the Gulf of Mexico including orienting discharge pipes such that

the hydraulic flow moves in a gulfward direction and locating dewatering structures

on the gulf side of the Study Area.

Construction Access Considerations: The required land based equipment

including but not limited to graders, loaders, dozers, and marsh buggy backhoes

would be transported from the mainland to the islands via barge(s). The contractor

would excavate access channels from either the Gulf of Mexico or the back bays to

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the islands utilizing barge mounted clamshell dredges with temporary sidecast

disposal. Exact access to the beach/dune and marsh fill templates would be

determined and coordinated during the Planning, Engineering and Design phase

and would include the necessary easements. The contractor would be required to

submit a construction access plan which shall contain provisions for the restoration

of any damaged habitats.

Miscellaneous equipment to be stored on the beach may include sediment pipeline,

graders, loaders, dozers, marsh buggy backhoes, weirs, grade stakes, light towers,

fuel tanks with containment, welding machine, and temporary shanty for personnel.

Further, the contractor would locate a quarters barge in an appropriate sheltered

staging area to house the land based personnel and office facilities.

6.4.7.4 Real Estate Requirements

Raccoon Island: Raccoon Island is owned by the State of Louisiana and is valued

highly by LDWF because it is the largest pelican rookery in Louisiana, critical

habitat for piping plover, and it is frequented by other threatened and endangered

species. The island has a footprint which contains approximately 235 acres. Fill for

the dune/beach and marsh components would be placed directly into water bottoms

water bottoms owned by the State of Louisiana as well as the upland areas owned

by the State. The island is owned by the State of Louisiana and is under the

jurisdiction of the Louisiana Department of Wildlife & Fisheries for Isles Dernieres

Barrier Island Refuge; therefore, easements are not needed for this island, only a

Grant of Particular Use.

Whiskey Island: Whiskey Island is an uninhabited island off the coast of

Terrebonne Parish. Access to the Island is only by boat. The island has a narrow

beach area on the Gulf front and broken marsh on the landside. Fill for the

dune/beach and marsh components would be placed directly into water bottoms

owned by the State of Louisiana as well as the upland areas owned by the State.

The island is owned by the State of Louisiana and is under the jurisdiction of the

Louisiana Department of Wildlife & Fisheries for Isles Dernieres Barrier Island

Refuge; therefore, easements are not needed for this island, only a Grant of

Particular Use.

Trinity Island: Trinity Island has a footprint which contains approximately 887

acres. What had been two islands for decades, and rejoined only recently, appears

to be successfully maintaining itself. Fill for the dune/beach and marsh components

would be placed directly into water bottoms owned by the State of Louisiana as well

as the upland areas owned by the State and a private entity. The majority of the

island is owned by the State of Louisiana. However, a small portion of the island,

approximately 30 acres, is privately owned by what appears to be one landowner. A

Standard Perpetual Beach Nourishment Easement would be acquired over these 30

acres of private property.

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Timbalier Island: Timbalier Island has a footprint which contains approximately

1,087 acres. Existing canals are apparently routinely used to service isolated

petroleum production facilities and wells, based on evidence of recent dredging.

Active gas production is present on the northern side of the island. Fill for the

dune/beach and marsh components would be placed directly into water bottoms

owned by the State of Louisiana as well as the upland areas owned by the State and

private entities. The majority of the island is owned by the State of Louisiana.

However, one end of the island has some private ownership which is estimated to be

approximately 80 acres. The ownership of this land is heavily disputed; however,

preliminary data indicates that each of the 11 estimated tracts contain multiple

owners. A Standard Perpetual Beach Nourishment Easement would be acquired

over these 80 acres of private property.

Timbalier Island hosts three oil and gas wells that are operated by Hilcorp Energy

Co. Based on recent conversations with Hilcorp, two of the three wells on Timbalier

are in the process of being plugged and abandoned and therefore will not require

access. The third well, SL 301 #101 is active and was recently refurbished by

Hilcorp. There is also a tank battery immediately east of the well that is still in

operation. Therefore, an access canal was incorporated into the design of the

template to facilitate barge travel from the bayward side of the island to the well

and tank battery. The canal is approximately 100 ft wide by 2,000 ft long.

A second access canal will be provided at the western end of the island to facilitate

access to an active platform. The platform, which is operated by Phoenix

Exploration, serves as a junction point for the Tennessee Pipeline. The access

canal is approximately 100 ft wide by 550 ft long.

6.4.7.5 Operations and Maintenance Considerations

O&M considerations for the LCA TBBSR Project include renourishment for the

NER plan and maintenance of a terminal groin.

Currently, renourishment for each island included in the NER plan is included on

Table 6-11. No additional marsh material would be added to any of the islands.

O&M for the terminal groin were evaluated based on a 20-year design life. The

structure may require repairs in that 20-year period to address structural

settlement based on the O&M of breakwaters currently located at Raccoon Island.

O&M costs are included in project cost projections. After 20 years, the structures

function would not have the same effectiveness due to sea level change, subsidence,

and barrier island migration. At that point, the structure would require

modification and rebuilding, which would not qualify as O&M.

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6.4.7.6 Monitoring Plan and Adaptive Management

6.4.7.6.1 Description of Monitoring Activity and Adaptive Management

A feasibility level monitoring and adaptive management plan has been developed

for the project (Volume V, Appendix I). The monitoring and adaptive management

plan was developed to include a sufficient description of the proposed monitoring

and adaptive management activities to identify the nature of proposed adaptive

management activities and to estimate the costs and duration of the monitoring and

adaptive management plan. The monitoring and adaptive management plan

identifies the restoration goals and objectives identified for the project; outlines

management actions that can be undertaken to achieve the project goals and

objectives; presents a conceptual ecological model that relates management actions

to desired project outcomes; and lists sources of uncertainty that recommend the

project for adaptive management. Monitoring, assessment, decision making, data

management are also addressed in the monitoring and adaptive management plan.

6.4.7.6.2 Performance Measures for Monitoring

The plan identifies performance measures along with desired outcomes and

monitoring designs in relation to specific project goals and objectives.

Objective 1: Restore the barrier structures to ensure their ability to provide

geomorphic and hydrologic form and function for the 50 year period of analysis.

Performance Measure: Areal extent

Desired Outcome: Reduce land loss within the TBBS Study Area below the

Historic average (1880’s - 2005)

Desired Outcome: Maintain an areal extent that matches the predicted

aerial extent of the associated design template at a particular point in time

Monitoring Design: Aerial photography and LiDAR surveys would be used

to assess the island’s dimensions over time

Performance Measure: Island volume

Desired Outcome: Reduce volume loss within the TBBS Study Area below

the historic average (1880’s - 2005)

Desired Outcome: Maintain an island volume that matches the predicted

island volume of the associated design template at a particular point in time

Monitoring Design: LiDAR and bathymetric surveys would be used to

assess the island’s volumes over time

Objective 2: Restore and improve various barrier island habitats that provide

essential habitats for fish, migratory birds, and other terrestrial and aquatic

species, mimicking, as closely as possible, conditions which occur naturally in the

area.

Performance Measure: Habitat composition

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Desired Outcome: Provide a distribution of acreage between habitat types

that matches the predicted acreages of the associated design template at a

particular point in time

Monitoring Design: Habitats would be classified using aerial photography

to assess trends in conversion of beach and marsh to open water

Objective 3: Increase sediment input to supplement long-shore sediment transport

processes along the gulf shoreline by mechanically introducing compatible

sediment, and increasing the ability of the restored area to continue to function and

provide habitat with minimum continuing intervention.

Performance Measure: Island elevation changes

Desired Outcome: maintain elevation and bathymetric profiles that match

the predicted profiles of the associated design template at a particular point

in time

Monitoring Design: Bathymetric and topographic surveys would be used to

determine the cross shore profile and volumes of the barrier islands in order

to characterize the changes that are occurring in the sediment budget,

barrier platform stability, and inlet response over time

Supporting Information Need: Geotechnical and sediment properties

would be identified using push cores and grab samples to better understand

sediment transport processes

Risk Endpoint: Erosion rates

Desired Outcome: Avoid inducing or increasing down drift erosion through

the use of hard structures. The benefits and/or impacts of hard structures on

sediment transport can be assessed by comparing the actual longshore

erosion rate measured along the beaches to the predicted erosion rates of the

associated design template at a particular point in time. Because impacts can

occur at a distance from the structure(s), monitoring should cover the entire

chain.

Monitoring Design: LiDAR and bathymetric surveys would be used to

determine downdrift erosion

Supporting Information Need: Potential scouring around hard structures

would be assessed using field reconnaissance

Risk Endpoint: Sediment capture and hypoxia

Desired Outcome: Understand sediment pathways, evolution of the side

slopes and environment (hypoxia) of borrow pits after dredging and over a

period of time

Monitoring Design: Close-spaced grid-pattern bathymetric survey followed

by sampling of bottom sediments. The bathymetric survey would be

appended to any such survey undertaken in the vicinity.

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6.4.7.6.3 Costs for Implementation of Monitoring and Adaptive Management

Programs

The costs associated with implementing the monitoring and adaptive management

plan were estimated based on currently available data and information developed

during plan formulation as part of the feasibility study. The costs estimated would

be refined in PED during the development of the detailed monitoring and adaptive

management plans.

The current total estimate for implementing the monitoring and adaptive

management programs is $9,960,000, based on October 2010 price levels. In

accordance with WRDA 2007 Section 2039, the monitoring costs presented in the

report are for the full allowable 10 year period and represent conservative and

comprehensive costs. Section 2039 guidance does allow for the monitoring to end

prior to the 10-year period if the Secretary determines that the success criteria have

been met. The costs presented in the report are for the full 10 year period but

monitoring may end prior to the 10 years. The monitoring plans and costs were

developed by the interagency LCA Adaptive Management Planning Team in

conjunction with stakeholders and have been determined to be a reasonable plan

and estimate for the recommended plan and are what is needed and necessary to be

able to determine project success. Adaptive management costs include program

establishment and implementation over 10 years.

6.4.7.7 Effectiveness in Meeting Goals and Objectives

The barrier island restoration components of the NER plan would achieve the

planning objectives by maximizing the barrier islands ability to provide geomorphic

and hydrologic form and ecological function over the 50 year period of analysis as

well as improve critical barrier island habitats for fish, migratory birds, and other

terrestrial and aquatic species. Sediment would be entered into the system to

supplement longshore sediment transport processes along the gulf shoreline by

mechanically introducing compatible sediment, and increasing the ability of the

restored area to continue to function and provide habitat with minimal continuing

intervention.

The NER plan is the plan that best meets the goal of the 2004 LCA Plan to address

critical near-term needs for shoreline restoration for Terrebonne Basin through

simulating historical conditions by enlarging the barrier islands (width and dune

crest) and reducing the current number of breaches to ensure the continuing

geomorphic and hydrologic form and function of the barrier islands. The selection of

the NER plan was based on a thorough review of existing scientific and engineering

reports, as well as geospatial, survey, and geotechnical data which reaffirmed that

the findings of the FPEIS remain valid.

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6.4.7.8 Effectiveness in Meeting Environmental Operating Principles

The NER plan is also the plan that best meets the USACE Principles and

Guidelines 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.

6.4.8 Recommended Component of Construction

The NER plan cannot be constructed within the current WRDA 2007 authorization.

Therefore, Whiskey Island Plan C, an implementable increment of the NER plan, is

recommended as the recommended component of construction. The USACE will

seek additional funding to fully construct the NER plan. In order to identify the

recommended component of construction from the NER plan, the PDT performed

additional cost refinements on each island in the NER plan using the MCACES,

MII. Refinements increased the costs of the islands, leaving Trinity Island Plan C

and Whiskey Island Plan C as the only island plans that could be constructed

within the current amount of the WRDA 2007 authorization. Previous CE/ICA

analysis revealed that both islands plans, when analyzed separately, were cost

effective. The plans also proved to be cost effective when compared against the

intermediate array. This analysis did not include renourishment. Consequently, a

separate screening process was conducted on the two islands to select the most

appropriate island as the recommended component of construction.

Although Whiskey Island Plan C provides slightly fewer AAHUs than Trinity

Island Plan C (379 AAHUs versus 387 AAHUs in the original plan without

renourishment), it was selected as the recommended component of construction due

to a number of qualitative benefits provided by the plan. Whiskey Plan C was

designed to avoid approximately 286 acres of existing mangroves on the island in

order to minimize the ecologic impact during construction. Since the island is

considered a valuable wildlife habitat (Isles Dernieres Barrier Islands Wildlife

Refuge) and the LDWF is reestablishing a pelican rookery on the island,

maintaining adequate areas of healthy beach, dune, and marsh is particularly

important. The island is also a critical habitat for endangered species, including the

piping plover, and is a valuable stopover habitat for migratory birds. The island

with the proposed restoration is shown in Figure 6-5.

Whiskey Island Plan C was designed to complement an existing CWPPRA project,

TE-50, which was constructed in 2009. TE-50 created approximately 316 acres of

intertidal back-barrier marsh between the two existing mangrove stands.

Restoration of the beach and dune Gulf-ward of TE-50 would help to sustain the

existing project. Raccoon Island, which also contains a rare mangrove habitat and

is an important rookery, would benefit from increased sediment deposition as the

long-shore sediment transport moves some of the sediment from Whiskey Island

westward to Raccoon Island.

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Whiskey Island is expected to disappear considerably sooner than the other islands

in the Isles Dernieres and Timbalier Island chains. The island currently lacks dune

habitat. If no action is taken on the island, supratidal and intertidal habitats are

expected to disappear by TY17 and TY31, respectively (compared to TY33 and TY40

for Trinity Island). Due to the rapidly approaching year of disappearance of the

remaining two habitat types, Whiskey Island warrants immediate restoration.

Whiskey Island is also the closest of the seven barrier islands to the critical marsh

habitat located in the southern most portion of Terrebonne Parish. If the island

were to disappear, the marsh habitat on the mainland would be susceptible to the

direct impacts of tropical storms and hurricanes. Immediately after construction

(TY1), the recommended component of construction would add 469 acres of habitat

(dune, intertidal, and supratidal) to the existing island footprint, increasing the size

of the island to 1,272 acres.

The total project cost of Whiskey Plan C is approximately $119,000,000. The nonFederal sponsor fully supports Whiskey Island Plan C as the recommended

component of construction under the current authorization. Table 6-12 shows the

fully funded cost for the recommended component of construction of this project.

Table 6-12 Fully Funded Recommended Component of Construction Cost

Summary

Project Element Fully Funded Total

Lands and damages

a

$67,000

Fish and wildlife

(Adaptive Management Plan) $5,820,000

Beach replenishment $103,000,000

PED $5,040,000

Construction management $5,160,000

Fully funded project costb $119,000,000

a Includes contingency; does not include renourishment b For the purposes of applying the cost index to the WRDA authorized cost, each project was

adjusted for inflation from the October 2006 price levels through the projected midpoint of

project construction.

Table 6-13 includes information about the fully funded project costs compared to the

original WRDA authorized cost and the escalated costs.

Table 6-13: Maximum Cost including Inflation through Construction

Authorized cost in WRDA 2007 Title VII,

Section 7006 (e)(3)(A): $124,600,000

Cost index used

EM 1110-2-1304 (Revised 31 Mar 2010)

a

CWBS Feature Code 17 - Beach Replenishment

Cost index ratio

1Q FY05 to 1Q FY10 1.22

Fully funded project cost estimateb $151,860,000

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(Inflation applied from 10/2004 to 10/2010)

20% of authorized cost: $24,920,000

Monitoring and adaptive managementc

(per WRDA 2007 Section 2039)

: $5,821,200 - $967,000

= $4,854,200

Maximum cost limited by Section 902 B:

$151,860,000 + $24,920,000 + $4,106,600

= $180,886,600

$180,900,000

Recommended Component of Construction cost

without renourishment $119,000,000 d

Note: All bolded numbers have been rounded. a The cost index applied to the current estimate through PED is derived from: EM 1110-2-1304, 30 Mar 10, .CWCCIS) b For the purposes of applying the cost index to the WRDA authorized cost, each project was adjusted for inflation from the

October 2004 price levels identified in the 2004 LCA Report, where the original project budget estimates were developed.

c Line 2 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.

d Renourishment is considered an O&M cost and, thus, is not included in the maximum cost limited by Section 902 B.

6.4.8.1 Renourishment

The PDT evaluated renourishment of the recommended component of construction

concurrently with the NER renourishment analysis. Based on the optimized

intervals that the PDT established, Whiskey Island would undergo two

renourishment events. The first event in TY 20 would involve the addition of

sediment to the dune and supratidal habitat equivalent to Plan C. The second

event would occur in TY40 and would include sediment added to the dune and

supratidal habitat in an amount equivalent to Plan B. The effects of the

renourishment on habitat acreages over time are shown in Table 6-14.

Table 6-14: Acerages for Whiskey Island Renourishment

Island Habitat

Type

Habitat Acres

TY0 TY1 TY5 TY10 TY20 TY21 TY30 TY40 TY41 TY50

Whiskey

Island

Dune 0 65 61 57 0 65 57 0 57 0

Supratidal

(Beach)

377 830 328 223 84 496 223 84 387 164

Intertidal

(Marsh)

443 377 808 828 847 834 717 472 461 363

Total 820 1,272 1,197 1,108 931 1,395 997 556 905 527

A WVA analysis for the recommended component of construction with

renourishment yielded a net benefit of 678 AAHUs when compared to the future

without project. For the recommended component of construction without

renourishment, a net benefit of 379 AAHUs would be created compared to the

future without project.

6.4.8.2 Components

Whiskey Island Plan C is a component of the NER plan. Whiskey Plan C proposes a

dune height of +6.4 ft NAVD 88 with a dune crown width of 100 ft. At the end of

the six-month period, the dune should reach the design elevation of 6 ft NAVD 88.

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The slopes of the beach and dune are set 60:1 and 30:1 (horizontal to vertical),

respectively.

The marsh fill is proposed on the landward side of the dune at an elevation of +2.4

ft NAVD 88 with the final elevation after the initial vertical adjustment matching

the design elevation of 1.6 ft NAVD 88. Immediately after construction in TY1,

approximately 65 acres of dunes, 830 acres of supratidal (beach), and 377 acres of

intertidal (marsh) habitat would be added to the island (see Table 6-14).

The recommended component of construction would utilize beach/dune material

from the Ship Shoal borrow area and marsh material from Whiskey 3a borrow area.

Fill quantities for the dune/beach and marsh components of Whiskey Plan C are 8.3

million and 0.6 million CY for initial construction. For the dune area, the material

would be pumped from the dredge to the beach. The material would then be worked

on the beach by bulldozers and front-end loaders. For the marsh area, the material

would be pumped from the offshore borrow site. Containment dikes would be

constructed around the perimeter. Sediment for the containment dikes would be

dredged from existing material inside the marsh creation area. Approximately

18,075 ft of sand fencing would be installed. The sand fences would promote

deposition of windblown sand, create dune features, reduce trampling of existing

dunes by beach visitors, and protect vegetative plantings. Vegetative plantings

would include a variety of native species. The recommended planting density is no

greater than 8-foot centers.

The island would require two renourishment events in order to maintain

geomorphic form and ecologic function throughout the 50-year period of analysis.

The first renourishment in TY20 would require the addition of 8.3 MCY of sediment

to the dune and supratidal areas. In TY40, the second renourishment event would

require the addition of 6.4 MCY of material to the dune and supratidal habitat. No

material would be added to the intertidal (marsh) areas.

Sustainability: The LCA TBBSR Project was identified in the 2004 LCA Report as

a restoration feature that could be implemented in the near term that addresses the

most critical needs of the Louisiana coastline. As indicated in the 2004 LCA Report,

the design and operation of the LCA TBBSR feature would maintain the

opportunity for, and support the development of large-scale, long-range

comprehensive coastal restoration. The project is synergistic with future

restoration by maintaining or restoring the integrity of the estuaries’ coastline,

upon which all future restoration is dependent. The recommended component of

construction would work in concert with other projects to improve the sustainability

of the Terrebonne Basin barrier shoreline.

The recommended component of construction would prevent the loss of Whiskey

Island. If no actions are taken, the existing 820-acre island is expected to disappear

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by 2042. This includes the existing critical mangrove habitat and the back-barrier

marsh created by CWPPRA Project TE-50. These objectives of restoring the

geomorphic form and ecologic function of the barrier islands and of restoring and

improving EFHs for fish, migratory birds, and other terrestrial and aquatic species

for the 50-year period analysis.

The restoration of the Whiskey Island would alter the tidal prism, thereby reducing

the formation of any additional tidal passes as well as closing or narrowing existing

passes and breaches, protecting and preserving the interior marsh habitats, which

would quickly erode without the protection of the sand shoreline.

6.4.8.3 Design, Environmental, and Construction Considerations

Project design, environmental, and construction considerations would be the same

for the NER plan and the recommended component of construction except the

recommended component of construction includes only one island. These

considerations are included in Section 6.4.7.3 of this report.

6.4.8.4 Real Estate Requirements

Land Acquisition: Whiskey Island is within the Isles Dernieres Barrier Island

Refuge under the jurisdiction of the LDWF. Based on information provided by the

State Land Office, the construction of the recommended component of construction

would completely occur within properties of the State. Therefore, no acquisition

costs are expected.

CPRA would be required to enter into a "Grant of Particular Use agreement" with

the LDWF prior to construction. Subject to project approval and funding, the

acquisition process would begin after a PPA is signed.

Pipelines: Several oil and gas pipelines are present throughout the Study Area.

Pipeline crossings occur within the island footprints, between the islands, and near

the islands. These pipelines are used to transport crude oil and natural gas from

wells to facilities scattered throughout the Terrebonne Basin. However,

construction of the project is not expected to impact any of these pipelines.

Furthermore, fill placement on the pipelines would provide an extra barrier of

protection.

6.4.8.5 Operations and Maintenance Considerations

O&M considerations for the LCA TBBSR Project include renourishment for the

recommended component of construction.

The timing and size of renourishment of sediment in the dune and supratidal

habitats to maintain the geomorphic and ecologic objectives of the project is

described in Section 6.4.8.1 for the recommended component of construction.

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6.4.8.6 Monitoring Plan and Adaptive Management

6.4.8.6.1 Description of Monitoring Activity and Adaptive Management

Development and implementation of the monitoring and adaptive management plan

for the project would be the same for the NER plan and the recommended

component of construction. The development of that plan is detailed in Section

6.4.7.6.1 of this report.

6.4.8.6.2 Performance Measures for Monitoring

Performance measures for monitoring would be the same for the NER plan and

recommended component of construction. The performance measures for the NER

plan are included in Section 6.4.7.2 of this report.

6.4.8.6.3 Costs for Implementation of Monitoring and Adaptive Management

Programs

The costs associated with implementing the monitoring and adaptive management

plan were estimated based on currently available data and information developed

during plan formulation as part of the feasibility study. The costs estimated would

be refined in PED during the development of the detailed monitoring and adaptive

management plans.

The current total estimate for implementing the monitoring and adaptive

management programs is $5,820,000, based on October 2010 price levels. In

accordance with WRDA 2007 Section 2039, the monitoring costs presented in the

report are for the full allowable 10 year period and represent conservative and

comprehensive costs. Section 2039 guidance does allow for the monitoring to end

prior to the 10-year period if the Secretary determines that the success criteria have

been met. The costs presented in the report are for the full 10 year period but

monitoring may end prior to the 10 years. The monitoring plans and costs were

developed by the interagency LCA Adaptive Management Planning Team in

conjunction with stakeholders and have been determined to be a reasonable plan

and estimate for the recommended plan and are what is needed and necessary to be

able to determine project success. Adaptive management costs include program

establishment and implementation over 10 years.

6.4.8.7 Effectiveness in Meeting Goals and Objectives

The barrier island restoration components of the recommended component of

construction would achieve the planning objectives by maximizing the barrier

islands ability to provide geomorphic and hydrologic form and ecological function

over the 50-year period of analysis as well as improve critical barrier island habitats

for fish, migratory birds, and other terrestrial and aquatic species. Sediment would

be added to the system to supplement long-shore sediment transport processes

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along the Gulf shoreline by mechanically introducing compatible sediment and

increasing the ability of the restored area to continue to function and provide

habitat with minimum continuing intervention.

The recommended component of construction meets the goal of the 2004 LCA Study

to address critical near-term needs for shoreline restoration for Terrebonne Basin

through simulating historical conditions by enlarging the barrier islands (width and

dune crest) and reducing the current number of breaches to ensure the continuing

geomorphic and hydrologic form and function of the barrier islands. The selection of

the recommended component of construction was based on a thorough review of

existing scientific and engineering reports as well as geospatial, survey, and

geotechnical data that reaffirmed that the findings of the LCA Report PEIS remain

valid. Additional discussion of how the recommended component of construction

addresses the project goals and objectives is included in Section 3 of Volume V.

6.4.8.8 Effectiveness in Meeting Environmental Operating Principles

The recommended component of construction is also the plan that best meets the

USACE P&G of completeness, effectiveness, efficiency, and acceptability as well as

the USACE EOPs of environmental sustainability, interdependence, balance and

synergy, accountability, knowledge, respect, and assessing and mitigating

cumulative impacts. A detailed discussion of how the recommended component of

construction addresses the USACE P&G as well as the USACE EOPs is included in

Section 3 of Volume V.

6.4.8.9 Compensatory Mitigation Measures

No compensatory mitigation is required for this project. As an ecosystem

restoration project, the alternatives were designed to avoid environmental impacts.

Any incidental temporary impacts that might be incurred during construction

would be more than offset by the net habitat value created by the recommended

component of construction.

6.4.9 Risk and Uncertainty

Simulation Uncertainties: Risks and uncertainties related to the formulation,

selection, and implementation of the project plan have been considered in this

study. Uncertainties in the analysis of the alternatives are associated with the

precision of the information on coastal erosion process and the methods used to

assess performance of alternatives. In order to analyze the alternatives at an

appropriate level of detail and reliability for selection of the preferred plan, a

number of simplifying assumptions and approaches were used to evaluate the

restoration feature performance for the alternatives. These uncertainties,

assumptions, and limitations on reliability of the analyses are provided in the

Engineering Appendix of Volume V.

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Weather-related Risks: Risks associated with the project alternatives are

primarily related to the possibility of extreme weather events during the project

period of performance. If a powerful tropical weather system passes over the Study

Area early in the project life, the overall performance and benefits of the restoration

features may be greatly reduced, or even eliminated, by such an event. Smaller

scale storm events have been incorporated into estimates of coastal processes, such

as shoreline retreat, for evaluation of the alternatives. The assumptions are based

on near-term and long-term historical observations of the frequency of repeat events

that are considered likely to occur during the project life.

Relative Sea-Level Rise Uncertainties: According to EC-1165-2-211, RSLR

must be considered in every USACE coastal activity. Low (historical), intermediate,

and high sea level rise rates were calculated for the Study Area. The low RSLR rate

was determined using historical data collected at Grand Isle, Louisiana

(http://tidesandcurrents.noaa.gov). Analysis of the data revealed an MSL trend of

9.24 mm/year, which is equivalent to a change of 0.030 ft/yr. This estimated MSL

trend combines the global MSL rise and a subsidence rate of 0.24 ft/yr. Subsidence

was calculated by subtracting the local MSL rise rate from the regional MSL rate.

The future sea level change values for the low rate were then determined by

extrapolating the historical linear trend into the future.

The eustatic sea level rise rates for the intermediate and high rates were

determined using the modified NRC Curves I and III, respectively. RSLR rates

were then calculated by summing the eustatic rates and the subsidence rate of 0.24

ft/yr.

During plan formulation, the PDT determined that the intermediate RSLR rate

would be the most appropriate rate to utilize in the initial development, evaluation,

and screening of the project alternatives. Consequently, habitat acres, AAHUs, and

erosion rates discussed in the preceding sections of the report are based on this rate.

However, to meet the requirements of EC 1165-2-211, the PDT concurrently

conducted an evaluation of the alternatives utilizing the high and low RSLR rates.

Each of the plans in the intermediate array was subjected to low and high RSLR

rates to determine a new set of habitat acres for each target year.

Should the RSLR coincide with the low rates as calculated per EC 1165-2-211,

output would be slightly greater than anticipated. However, should the RSLR equal

the high sea level rise trend, the project would produce approximately 11% fewer

acres than anticipated without renourishment. Additional information about the

possible impacts of RSLR on the project is included in Volume V.

Cost Estimate Uncertainties: In compliance with ER 1110-2-1302 Civil Works

Cost Engineering, dated September 15, 2008, formal risk analyses studies were

conducted for the development of contingency on the total project cost for the initial

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restorations of the NER and recommended component of construction exclusive of

the O&M construction activities. The purpose of these risk analyses studies were to

establish project contingencies by identifying and measuring the cost and schedule

impact of project uncertainties with respect to the estimated project cost for the

initial restoration of the NER plan and recommended component of construction.

A more detailed discussion of the cost estimate uncertainties and the escalations

used is included in Volume V. Further details of the Risk Analyses are presented in

Volume V, Appendix L Annex L-5.

6.4.10 Implementation Requirements

6.4.10.1 Schedule

Design Schedule: On a project following the full normal authorization process,

the PED phase begins when the Major Subordinate Command Commander issues

the public notice for the feasibility report and PED funds are allocated to the

district. The anticipated start date for PED is November 2010. PED generally

requires a period of up to 2 years, depending on the complexity of the project, and

ends with completion of the plans and specifications for the first construction

contract or as otherwise defined in the PED cost-sharing agreement. Engineering

functions shall be prepared to begin an intensive effort immediately upon

notification that PED funds are available. For the LCA TBBSR, it is estimated this

phase would last approximately 15 months. Time should be saved because the

alternatives analysis, fill template designs, and borrow area identification were

completed as part of the engineering feasibility study. Surveys, volume

calculations, and cost estimate would have to be updated at the design level prior to

completing final plans and specifications.

Construction Schedule: The construction schedule for the initial restoration of

the NER plan and recommended component of construction consists of project

mobilization / demobilization and construction access, beach/dune and marsh fill

placement, and borrow area pipeline relocation for both the NER plan and the

recommended component of construction. The NER plan was divided into two

separate construction contracts. The NER plan Contract No.1 consists of the initial

restoration of Whiskey Island, Trinity Island, and Raccoon Island with terminal

groin. The NER plan Contract No. 2 consists of initial restoration of Timbalier

Island. The islands were divided between the contracts on the basis of common

borrow area allocations and construction duration.

Construction of NER plan Contracts No.1 and No. 2 should begin concurrently. The

anticipated start date of construction for the NER plan or the recommended

component of construction is June of 2012. The estimated timeline for construction

of the NER plan and recommended component of construction are summarized

below and described in detail in Volume V, Appendix L.

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The following assumptions were made in developing the construction schedules:

Single dredge plant would be utilized per contract

NER plan Contracts No.1 and No.2 would commence construction

simultaneously

Construction access for each subsequent island would be constructed

concurrent with the previous island's fill placement

Marsh fill containment dikes would be constructed concurrent with

beach/dune fill placement

Construction of the terminal groin would be done concurrent with fill

placement.



NER plan restoration construction schedule Contract No. 1:

Project Mobilization: 56 days

Whiskey Island Beach/Dune Construction: 325 days

Borrow Area Pipeline Relocation: 94 days

Trinity Island Beach/Dune Construction: 168 days

Borrow Area Pipeline Relocation: 63 days

Trinity Island Marsh Construction: 193 days

Borrow Area Pipeline Relocation: 60 days

Whiskey Island Marsh Construction: 23 days

Borrow Area Pipeline Relocation: 61 days

Raccoon Island Beach/Dune: 204 days

Raccoon Island Marsh & Terminal Groin Construction: 109 days

Borrow Area Pipeline Relocation: 56 days

Raccoon Island Marsh Construction: 48 days

Demobilization: 35 days

Total construction time for initial restoration of the NER plan, Contract No. 1 is

49.2 months.

NER Plan Restoration Construction Schedule Contract No. 2:

Project Mobilization: 71 days

Timbalier Island Beach/Dune Construction: 474 days

Timbalier Island Marsh Construction: 130 days

Borrow Area Pipeline Relocation: 112 days

Timbalier Island Marsh Construction: 237 days

Borrow Area Pipeline Relocation: 81 days

Timbalier Island Marsh Construction: 61 days

Demobilization: 52 days

Total construction time for initial restoration of the NER Plan Contract No. 2 is

40.1 months. Contract No. 2 will run concurrently with Contract No. 1.

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Initial Restoration Construction Schedule for the Recommended Component of

Construction:

Project Mobilization: 56 days

Whiskey Island Beach/Dune Construction: 325 days

Borrow Area Pipeline Relocation: 65 days

Whiskey Island Marsh Construction: 23 days

Demobilization: 37 days

Total construction time for the initial restoration of the recommended component of

construction is 16.6 months. Vegetative plantings and sand fencing will be

scheduled following fill activities in accordance with Volume V, Appendix L.

6.4.10.2 Implementation Responsibilities

Preconstruction Engineering and Design: Detailed design of the Terrebonne

Basin Barrier Shoreline Restoration Project would be the responsibility of the

USACE. All detailed design would be in accordance with USACE’s regulations and

standards.

Construction and LERRDs: Activities within the construction phase would be in

accordance with the USACE’s regulations and standards. Crediting for work

performed by CPRA would be subject to project authorization and adherence to

USACE design standards and regulations. LERRDs would be the responsibility of

CPRA.

Operations and Maintenance: All future O&M for the restoration project would

be accomplished by the non-Federal sponsor at 100% non-Federal cost. O&M of

structures would be required. The non-Federal sponsor would repair and/or replace

the sand fencing and vegetation required. Renourishment of the islands is part of

the non-Federal sponsor’s O&M responsibilities. Additionally, the non-Federal

sponsor would monitor the Study Area and enforce the easement restrictions.

6.4.10.3 Cost Sharing

The State of Louisiana, acting through the CPRA, would be the non-Federal sponsor

for the LCA Terrebonne Basin Barrier Shoreline project. Following the feasibility

phase, the cost share for the planning, design and construction of the project would

be 65% Federal and 35% non-Federal. The CPRA must provide all LERRDs

required for the project. OMRR&R of the project would be a 100% CPRA

responsibility. The cost apportionment of the NER plan and the recommended

component of construction are presented in Table 6-15 and Table 6-16.

The State of Louisiana is in full support of the LCA Terrebonne Basin Barrier

Shoreline Restoration project at the current cost share ratio of 65% Federal, 35%

non-Federal, with operations, maintenance, repair, replacement and rehabilitation

being a 100% non-Federal responsibility, as required in WRDA 2007. Additionally,

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project monitoring and any adaptive management deemed necessary would be cost

shared at 50/50 for the first 10 years of the project life.

Table 6-15: LCA TBBSR Project Cost Sharing for NER Plan

Project Feature Total Cost Non-Federal Federal

% Cost %Cost

Total first cost

of construction $646,931,000 a 35 $226,426,000 65 $420,505,000

LERRD credit $692,000 100 $692,000 0 $0

Monitoring and

adaptive

management

$9,960,000 35 $3,486,000 65 $6,474,000

OMRR&Rb,c $11,300,000 100 $11,300,000 0 $0

aTotal first cost of construction is based on the sum of the planning, engineering, and design; construction management

(i.e. supervision and administration); LERRDs; and monitoring and adaptive management and is based on October 2010

price levels.

bAverage annual cost based on October 2010 price levels

c Includes multiple renourishment events

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Table 6-16: LCA TBBSR Project Cost Sharing for Recommended

Component of Construction

Project Feature Total Cost Non-Federal Federal

% Cost %Cost

Total first cost

of construction $113,434,000 1 35 $39,702,000 65 $73,732,000

LERRD credit $65,000 100 $65,000 0 $0

Monitoring and

adaptive

management

$5,820,000 35 $2,037,000 65 $3,783,000

OMRR&R2,3 $4,970,000 100 $4,970,000 0 $0

1Total first cost of construction is based on the sum of the planning, engineering, and design; construction management (i.e.

supervision and administration); LERRDs; and monitoring and adaptive management and is based on October 2010 price

levels.

2Average annual cost based on October 2010 price levels

3 Includes multiple renourishment events

6.4.10.4 Environmental Commitments

The USACE, its non-Federal sponsor (CPRA), and contractors commit to avoiding,

minimizing, or mitigating for adverse effects during construction activities. A

detailed list of the specific environmental commitments in included in Section 3 of

Volume V.

REASONABLE AND PRUDENT MEASURES

The Service believes the following reasonable and prudent measures (RPMs) are

necessary and appropriate to minimize take on non-breeding piping plovers

during implementation of the proposed TBBSR project within the action area.

1. A baseline piping plover survey shall be conducted within the migrating

and wintering season immediately prior to initial construction within the

action area. As part of that survey, the project footprint should be

delineated using a global position system (GPS) unit and appropriately

marked/flagged for future survey reference and data collection.

2. A survey of the intertidal benthic prey species community shall be

conducted within the migrating and wintering season immediately prior to

initial construction, at the same time as the plover distribution surveys, in

order to establish a baseline of benthic prey species diversity and

abundance.

3. Piping plover monitoring surveys shall be conducted during the

migrating and wintering seasons throughout initial project construction

and three consecutive years following completion of initial construction.

4. To confirm re-establishment of suitable foraging habitat for migrating

and wintering plovers, monitoring surveys of the intertidal benthic prey

species community shall be conducted each year following completion of

initial construction for three consecutive years, preferably at the same

time as the bird surveys.

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5. The Service shall be notified in writing at least 3 months prior to a

renourishment event for each island. If renourishment events are

conducted during the migrating and wintering season, piping plover

monitoring surveys shall be conducted for the duration of construction

activities following the survey schedule outlined in Appendix B.

6. A comprehensive report describing the actions taken to implement the

RPMs and terms and conditions associated with this incidental take

statement (including data sheets from surveys conducted) shall be

submitted to the Service by June 1 of the year following completion of all

required surveys.

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.

Monitoring Requirements

1. Requirements for piping plover surveys

a) A survey schedule (with dates) is listed in Appendix B and the

recommendation is for at least 3 survey dates per month; this schedule

should be followed as closely as possible. If conditions require a deviation

from the recommended survey schedule, such information should be

carefully documented, including an explanation why any deviation from

the recommended schedule was deemed necessary. The Service recognizes

that given the remoteness of the project area and the potential for

inclement weather conditions during the plover wintering season, three

survey dates per month may be difficult to achieve in Louisiana.

Therefore, the Service will require a minimum of two survey dates per

month.

b) Piping plover identification, especially when in non-breeding

plumage, can be difficult. Qualified professionals with shorebird/habitat

survey experience must conduct the required survey work. Piping plover

monitors must be capable of detecting and recording locations of roosting

and foraging plovers, and documenting observations in legible, complete

field notes. Aptitude for monitoring includes keen powers of observation,

familiarity with avian biology and behavior, experience observing birds or

other wildlife for sustained periods, tolerance for adverse weather,

experience in data collection and management, and patience.

c) Binoculars, a GPS unit, a 10-60x spotting scope with a tripod,

and the Service datasheet (Appendix B) must be used to conduct the

surveys.

d) Negative (i.e., no plovers seen) and positive survey data shall be

recorded and reported.

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e) Piping plover locations shall be recorded with a GPS unit set to

record in decimal degrees in universal transverse Mercator (UTM) North

American Datum 1983 (NAD83).

f) Habitat, landscape, and substrate features used by piping

plovers when seen shall be recorded. Such features are outlined on the

Service data sheet in Appendix B.

g) Behavior of piping plovers (e.g., foraging, roosting, preening,

bathing, flying, aggression, walking) shall be documented on the Service

data sheet in Appendix B.

h) Color-bands seen on piping plovers shall also be carefully

documented, and should also be reported according to the information

found at the following websites. Information regarding color-band

observations can be found at:

http://www.fishwild.vt.edu/piping_plover/Protocols_final_draft.pdf,

http://www.waterbirds.umn.edu/Piping_Plovers/piping2.htm, and

http://www.fws.gov/northeast/pipingplover/pdf/BahamasBandReporting20

10.pdf.

2. Requirements for surveying benthic prey species

a) A qualified professional with sediment/macroinvertebrate

sampling experience must conduct the required benthic prey species

surveys.

b) A baseline macroinvertebrate survey will be conducted at the

same time of the initial piping plover survey during the

migrating/wintering season immediately prior to construction. Additional

surveys will be conducted during the migrating/wintering season each

year postconstruction for three consecutive years to determine benthic

prey species recovery. Such surveys shall be conducted at the same time

as the plover surveys.

c) Sampling will be conducted using a basic before and after

control and impact design method. Sampling will be coordinated with

piping plover foraging observations based on low tide surveys.

d) In addition to recording benthic species abundance and

diversity, a qualitative measure of sediment characteristics (sand, shell,

mud) will also be recorded.

e) A detailed sampling methodology shall be developed in

coordination with the Service and LDWF prior to initiating surveys.

Reporting Requirements

1. Incorporate all data collected into an appropriate database; preferably

one for piping plovers and one for benthic prey species.

2. Annual update reports shall be provided to the Service and LDWF by

June 30 of each calendar year once construction begins. Annual update

reports should include data sheets, maps, a copy of the database, and the

progress and initial findings of piping plover and benthic community

surveys, as well as any problematic issues that may hinder future survey

efforts.

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3. If the Corps foresees any problematic issues that would require a

change in the recommended survey schedule due to work conditions or

project delays, the Corps should immediately notify the Service so that we

can resolve/correct any such issues.

4. A final comprehensive report should be provided to the Service and

LDWF by June 30 following the third year of surveys. That final report

should include an analysis of all data results from the piping plover and

benthic community surveys.

5. At least six months prior to mobilization, the Corps should notify the

Service in writing prior to each proposed renourishment event. That

notification should include whether there are any changes in the proposed

amount of renourishment per island.

Upon locating a dead or injured piping plover 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 piping plover to

ensure effective treatment or disposition and in handling dead specimens to

preserve biological materials in the best possible state for later analysis.

6.5 Public Involvement *

6.5.1 NEPA Scoping

A NOI to prepare a SEIS for the LCA TBBSR Project was published in the Federal

Register in December 2008. A scoping meeting was conducted in February 2009 for

the project. Two additional public group meetings were conducted with groups

associated with recreational use of the Study Area.

Common themes of the comments included the following:

Need for urgency of project implementation

Stress the need to protect the barrier islands in the Study Area

Using Ship Shoal sand and/or rock material in the restoration efforts

Need to include Wine Island in the restoration effort

Narrow passages to lower water velocity

Concerns about saltwater intrusion

The Draft FS/SEIS was released to the public in June 2010, followed by a 45-day

public review period, which included a public meeting. Public comments were

received during the scoping meeting and Draft FS/SEIS public review. Public

comments have been incorporated into the report throughout the report

development. Comments received and the responses to them are included in

Appendix G of Volume V.

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6.5.2 Other Public Comments, Areas of Controversy, Unresolved Issues

An area of controversy that exists is the effectiveness of hardened structures, most

notably, rock breakwaters and revetments, in achieving the project goals. Hard

structures that have been used in the past on East Timbalier Island and Raccoon

Island have had mixed results. The construction of jetties at Belle Pass and the

seawall-groin systems along East Timbalier have been linked to the present erosion

problems on East Timbalier, whereas, the segmented rock breakwaters on Raccoon

have had positive results to date.

A concurrent resolution, sponsored by Representative Gordon Dove of Terrebonne

Parish, was passed during the 2006 Regular Session of the Louisiana Legislature

which prompted the U.S. Congress to ensure that any USACE projects designed to

restore the barrier islands protecting Terrebonne and Timbalier bays utilize

hardened material to redefine and narrow Whiskey Pass, Wine Island Pass, and

Cat Island Pass. During the public scoping meeting held in March 2009,

Terrebonne Parish President Mr. Michel Claudet and other members of the public

stressed that rocks should be given proper consideration in light of the positive

benefits demonstrated at Raccoon Island. The LDWF have also been very

supportive of the use of hard structures on Raccoon and Whiskey islands. Both of

these islands are owned and managed by LDWF.

The project team evaluated the use of segmented breakwaters on Whiskey Island

and segmented breakwaters and a terminal groin on Raccoon Island using the

GENESIS Model. Model results indicated that the breakwaters reduced erosion on

Whiskey Island and Raccoon Island by 5.62 ft/yr and 0.80 ft/yr, respectively.

However, further analysis revealed that barrier island restoration using dredged

material was a more cost effective method of maximizing habitat created over the

50-year period of analysis. The GENESIS model indicated that the terminal groin

on Raccoon Island would result in accretion of sand on the western end of Raccoon

Island and would yield cost effective net benefits over 50-year period of analysis.

The impacts of the Deepwater Horizon oil spill on coastal Louisiana are uncertain.

The impacts of the oil spill as well as the various emergency actions taken to

address oil spill impacts could potentially impact USACE water resources projects

and studies within the Louisiana coastal area. 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.

6.6 Coordination and Compliance *

6.6.1 USACE Principles and Guidelines

The coordination and compliance efforts for this project regarding statutory

authorities, including environmental laws, regulations, Executive Orders, policies,

rules, and guidance are documented in Volume V. Consistency of the recommended

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component of construction and other Louisiana coastal restoration efforts is also

addressed.

6.6.2 Environmental Coordination and Compliance

Coordination and compliance efforts were conducted regarding statutory

authorities. These include environmental laws, regulations, Executive Orders,

policies, rules, and guidance applicable to this project. Full compliance with

statutory authorities would be accomplished upon review of the integrated FS/SEIS

by appropriate agencies and the public and the signing of a ROD.

The USACE has coordinated with the USFWS, NMFS, and the LDWF per the Fish

and Wildlife Coordination Act (48 Stat. 401, as amended; 16 U.S.C. 661 et seq.). A

CAR has been received and the comments incorporated into the project plan as

appropriate. Accordingly, the USFWS supports implementation of the

recommended plan, provided that additional assessment work is continued during

the remaining planning phase and completed during the PED phase, to address

outstanding major issues that could result in substantial improvements and/or

modifications to the selected plan. The USACE concurred with the

recommendations; discussion of the recommendation is provided in Volume V.

Formal consultation on the piping plover was conducted and a Biological Opinion

was received on September 23, 2010 from the USFWS. The USFWS determined

that the level of expected take is not likely to result in jeopardy to the piping plover.

The Reasonable and Prudent Measures and Terms and Conditions as outlined by

the Biological Opinion will be followed (Volume V - Appendix A).

State certifications for coastal zone consistency and 401 water quality have also

been received.

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7.0 MEDIUM DIVERSION AT WHITE DITCH

7.1 Purpose and Scope*

This is a summary of the FS/SEIS for the LCA MDWD Project (Volume VI).

The LCA MDWD was proposed to reverse the current decline of wetlands in the

Breton Sound Area and to prevent the transition of the marsh and open water and

intermediate marsh into brackish marsh. Reversing this decline will help to

develop more sustainable ecosystems, which can serve to protect the local

environment, economy, and culture. The feasibility study of the LCA MDWD

evaluates a medium-sized (5 to 15,000 cfs) diversion structure from the Mississippi

River and into the Breton Sound area. The goal of this diversion was to reintroduce

Mississippi River water into the Breton Sound Area. Reintroduction of the

Mississippi River water would bring freshwater, sediments, and nutrients to the

Study Area. Alternative locations and sizes of the diversion were investigated.

This project would complement but is independent of another proposed LCA project

in the area. The Caernarvon Diversion is located north of the White Ditch

Diversion area but does not affect the same area.

The environmental consequences of the proposed project are evaluated in Volume

VI, Section 5 and summarized here. The integrated NEPA documentation and

SEIS is a supplement to the FPEIS, LCA Report (USACE, 2004b). The ROD for the

FPEIS was signed on November 18, 2005. The FPEIS is incorporated by reference.

7.1.1 Study Area Background*

The LCA MDWD 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 (see Figure 7-1). The area is currently isolated from

the effects of the Caernarvon Freshwater Diversion, located at the northern end of

the Breton Sound basin.

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Two discreet project locations 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 Study 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 diversion structure would be located 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 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. This minimizes the infrastructure that would be affected

by construction of a diversion structure. Channel construction, subsidence,

saltwater intrusion, and storm-related damages have all significantly altered the

natural environment, causing extensive losses of wetland habitats.

7.1.1.1 Study Area Significance

Numerous scientific analyses and evaluations of the LCA MDWD Study Area have

documented its significant ecological resources. Louisiana contains one of the

largest expanses of coastal wetlands in the contiguous United States, and accounts

for 90% of the total coastal marsh loss occurring in the nation. The LCA MDWD

Study Area contains an extraordinary diversity of habitats that range from narrow

natural levee 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 Study Area among the nation’s most productive and important

natural assets. In human terms, these coastal wetlands have been a center for

culturally diverse social development.

The area is important for commercial harvest of alligator eggs and approximately

70% of all waterfowl that migrate through the United States use the Mississippi

and Central flyways, which are located directly over (within) the LCA MDWD Study

Area. With over 5 million birds wintering in Louisiana, the Louisiana coastal

wetlands are a crucial habitat to these birds as well as to neotropical 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 LCA MDWD Study Area, specifically, are significant

on a national level.

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7.1.2 History of Investigation

This study addresses ecosystem restoration problems and opportunities in the LCA

MDWD Study Area. These have been documented since 1998 through numerous

comprehensive planning studies. Specifically, this study builds upon the following

comprehensive planning efforts for the LCA, which are further discussed in the

FS/SEIS (Volume VI):

Coast 2050 Plan (LCWCRTF and WCRA, 1999)

LCA Report (USACE, 2004a)

LACPR Final Technical Report (USACE, 2009c)

Integrated Ecosystem Restoration and Hurricane Protection: Louisiana’s

Comprehensive Master Plan for a Sustainable Coast (LACPRA, 2007)

7.1.3 Prior Reports and Existing Projects

A number of prior water resources development efforts have been identified as

relevant to the LCA MDWD Study. The relevance of these reports will be

determined as the study progresses and will be accurately reflected in Table 7-1.

Additional reports and information about referenced reports are included in the

FS/SEIS (Volume VI).

Table 7-1: Relevance of Prior Studies, Reports, Programs, and Water

Projects to the

Prior Studies, Reports, Programs, and Water

Projects

LCA MDWD Feasibility Study

Relevance to Medium

Diversion at White Ditch

Data Source

Consistency

Structural

Measurements

Non-Structural

Measures

Future Without

Project

Condition

MR&T, 1928 X X X

New Orleans to Venice, Louisiana Hurricane

Protection, 1962 XXX

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

Louisiana’s Eroding Coastline: Recommendations

for Protection, EPA 1982 XXXX 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 X X

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(Draft)

Louisiana Coastal Wetlands Conservation,

Restoration and Management Act, Act 6 1989 X X X

CWPPRA, 1990 X X X X X

White’s Ditch Diversion Siphon - Outfall

Management Plan Feasibility Report (1992) X XX X

An Environmental- Economic Blueprint for

Restoring the Louisianan Coastal Zone: The State

Plan for the Wetlands Conservation and

Restoration Authority, 1994

XXXX X

A White Paper- The State of Louisiana’s 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 Louisiana’s New Map: Addressing Land

Loss in Coastal Louisiana, 2006 X X

Louisiana’s Comprehensive Master Plan for a

Sustainable Coast, 2007 XXXX X

LACPR, 2009 X X X X X

Bonnet Carré Spillway X X X X

CWPPRA Projects Constructed or Authorized for

Design XXXX X

HSDRRS XXXX

Various Environmental Assessments Prepared by

the USACE XXXX X

7.1.3.1 Federal

Several comprehensive planning efforts have significance to the LCA MDWD

Feasibility Study and additional information about those comprehensive planning

efforts references in this report are more fully described in the FS/SEIS (Volume

VI).

LCA Report, 2004: In 2000, the USACE and State of Louisiana initiated the LCA

Report to address Louisiana’s severe coastal land loss problem. In 2004, the LCA

Report was completed, and it identified various projects across the coastal area of

Louisiana to address the most critical needs. This project was formulated to

address this description and scope. The report described the LCA MDWD Project as

follows:

Medium Diversion at Whites Ditch, located at White’s Ditch downstream of

the Caernarvon diversion structure, would implement a medium diversion

into central River aux Chene area through the construction and operation of

a new water control structure. The objective of this project is to provide

additional freshwater, nutrients, and fine sediments to the area between the

Mississippi River and River aux Chene ridge which is currently isolated from

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the beneficial effects of the Caernarvon freshwater diversion. The

introduction of additional freshwater would facilitate organic sediment

deposition, improve biological productivity, and prevent further deterioration

of the marshes.

Other projects included in the LCA Report that are near the LCA MDWD Project

include the following (USACE, 2004a):

The Caernarvon Diversion, constructed in 1992 near the Breton Sound

marshes, has been operated to manage salinities in the central Breton Sound

estuary through the introduction of freshwater at rates ranging between

1,000 and 8,000 cfs. This restoration project would seek a post-authorization

change to the original project purpose to include wetland creation and

restoration via increasing freshwater introduction rates, up to perhaps 5,000

cfs on average, to provide greater wetland-building function. The

introduction of additional freshwater would facilitate organic and sediment

deposition, improve biological productivity, and prevent further deterioration

of the marshes.

Federal Laws and Programs

CWPPRA, 1990: The CWPPRA of 1990 was the first Federal statutory mandate

for restoration of Louisiana’s coastal wetlands. The CWPPRA Task Force is

composed of five Federal agencies (USEPA, USFWS, USACE, NMFS, and NRCS)

and the State of Louisiana. The Task Force is required to prepare an annual

Project Priority List. CWPPRA provides funds annually for coastal restoration

planning and the construction of coastal protection and restoration projects.

7.1.3.2 State/Parish

Coastal resource management in Louisiana formally evolved once Louisiana

adopted and began participating in the Federal CZM program in 1978. Shortly

thereafter, the State developed a CZM 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.

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 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 statesponsored coastal restoration projects.

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Act 6 also created the WCRF, which dedicates a portion of the state’s revenues from

severance taxes on mineral production (e.g., oil, 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 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.

7.1.3.3 Local

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 Lake Pontchartrain Basin Foundation and the Coalition to Restore Coastal

Louisiana are both active and prominent NGOs that have taken an interest in the

development of the LCA MDWD Study. 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 Study

Area.

Related Water Projects

Several existing and authorized navigation, river flood control, hurricane storm

surge risk reduction, and coastal restoration projects are related to the LCA MDWD

Feasibility Study. These projects are briefly described below. These projects are

listed below in Table 7-2 and are more fully described in the FS/SEIS (Volume VI).

Table 7-2: Additional Water Related Projects

Project Name

Coastal

Restoration

Project

River Flood

Control

Project

Hurricane Storm

Surge Risk

Reduction

Projects

Bonnet Carré Freshwater Diversion X

Davis Pond Freshwater Diversion X

Caernarvon Freshwater Diversion and

Outfall Management X

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Bertrandville Siphon X

Naomi Siphon and Outfall Management X

White Ditch Resurrection and Outfall

Management X

West Pointe à la Hache Siphon and Outfall

Management X

Bohemia Mississippi River Reintroduction X

Bayou Lamoque Freshwater Diversion X

Delta Building Diversion North of Fort St.

Philip X

Benney’s Bay Sediment Diversion X

West Bay Diversion X

Myrtle Grove Diversion X

Bonnet Carré Freshwater Diversion X

Davis Pond Freshwater Diversion X

Caernarvon Freshwater Diversion and

Outfall Management X

MR&T, 1928 X

Bonnet Carré Spillway, 1931 X

Greater New Orleans Hurricane and Storm

Damage Risk Reduction System X

7.2 Need for and Objectives of Action *

7.2.1 Public Concerns

A number of public concerns have been identified for the project. 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, workshops and public meetings. The public concerns

that are related to the establishment of planning objectives and planning

constraints are as follows:

Potential negative effects from the diversion on oyster habitats

Potential negative effects from the diversion on alligator egg collecting

Potential negative effects 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, which converts existing estuarine

habitats into purely freshwater and intermediate types

Making the 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 LCA Myrtle Grove Diversion

that could be located directly across from the White Ditch diversion location

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It should be noted that through numerous stakeholder meetings and discussions,

there is also broad-based support for a project of this magnitude.

7.2.2 Problems, Needs, and Opportunities*

Study Area problems and opportunities were drawn from prior comprehensive

planning studies, 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.

Following an extensive literature review and NEPA scoping, the PDT met to

consider all the available information for the purpose of identifying specific

problems and opportunities, a general problem statement, a goal statement and an

initial list of project specific objectives and constraints.

Study Area Problems and Needs

The fundamental problem in the Study Area is the disconnection of the estuary

from the freshwater, sediment, and nutrient inputs of the Mississippi River by

construction of the MR&T flood control system. 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 LCA MDWD

Study Area over the past century. Various human activities have resulted in a

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. The

threat of increasing RSLR is compounding these problems.

Wetlands in the Study 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.

These activities have resulted in the loss of several thousand acres of solid,

vegetated marsh. It is expected that the Study 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.

In the absence of supplemental freshwater and sediment from flooding of the

Mississippi River, subsidence, sea level rise, wave erosion, and saltwater intrusion

will continue to be problems. Restoration of this area is 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.

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Historically, floodwater from the river would overtop the natural river banks then

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 as 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 Study Area. This event caused the development of

the Bayou Garelle tributary channel.

The present-day hydrology of the Study 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 freshwater 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:

The Mississippi River can no longer overflow its banks into the Study Area

due to the MR&T 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 have increased

drainage and tidal exchange and exposed the soil to erosive forces.

Study Area Opportunities

Opportunities exist to reconnect the Mississippi River to the estuary, 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 where the limited existing freshwater

supplies are directed toward River aux Chenes and into the Gulf. These

canals also allow for the direct influx of saltwater from the exterior bays of

the Breton Sound Basin. Opportunities exist to improve the internal

distribution of freshwater to restore and improve the sustainability of

freshwater marsh habitats.

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Sediment Supply and Distribution: The lack of sediments from the

Mississippi River has accelerated the degradation of all marsh types.

Opportunities exist to reintroduce sediments from the river and use on-site

sediments displaced by Gulf storm events to create new marsh area.

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 dredged materials.

Sustainability: As marsh degradation has accelerated, seasonal Gulf events

have a magnified impact on the remaining marsh areas. Opportunities exist

through freshwater 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.

7.2.3 Planning Objectives

The overall objective of the LCA MDWD 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 to the area between the Mississippi River and the River aux Chenes

ridges. This will contribute to 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 wellbeing of the nation.

Additionally, planning objectives identified in the 2004 LCA Report serve as a

foundation for developing specific project objectives. Two tiers of tactical planning

objectives, including hydrogeomorphic and ecosystem, were established.

Specifically, they include the following:

Establish dynamic salinity gradients that reflect natural cycles of freshwater

availability and marine forcing.

Increase sediment input from sources outside estuarine basins and manage

existing sediment resources within estuarine basins, to sustain and

rejuvenate existing wetlands and rebuild marsh substrate.

Maintain or establish natural landscape features and hydrologic processes

that are critical to sustainable ecosystem structure and function.

Sustain productive and diverse fish and wildlife habitats.

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Reduce nutrient delivery to the Continental shelf by routing Mississippi

River waters through estuarine basins while minimizing potential adverse

effects.

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.

Specific Project Objectives

Restore adequate freshwater and nutrient inputs into the Study Area such

that sustainable areas of freshwater, intermediate, brackish and saline

marsh are present and existing areas of marsh acres are maintained.

Restore sediment inputs into the Study Area equivalent to an average of

approximately 1,300,000 CY of sediment per year.

7.2.4 Planning Constraints

Planning constraints generally include the legal and policy constraints that are

applicable to all Federal water resources planning efforts and additional projectspecific constraints. The implementation and operation of the project will be

constrained by the following categories of constraints:

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.

Ecosystem constraints: Constraints imposed upon the project design by

existing conditions within the Study Area’s ecosystem

These categories and their constituent constraints are discussed separately below.

Project Design Constraints:

The current authorization in WRDA 2007 identifies a 5,000-15,000 cfs

diversion. 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: Measures must accomplish their goals while

avoiding and/or minimizing 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.

General Infrastructure: A state highway and several local roads as well as a

few residences are found in the Study Area. Numerous oil and gas pipelines

exist 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.

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Potential impacts such as induced shoaling or increased O&M of the

authorized Mississippi River Navigation Project should be avoided.

Ecosystem Constraints:

It may be likely that the restoration of marsh habitats will 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: At this time, it is not known if pallid sturgeons, a federallylisted species, are in the lower river near the LCA MDWD Study Area.

Monitoring will need to be done to determine its presence; 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 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 H&H 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 Study Area and River aux Chenes, as well as

navigation access, while achieving project objectives for marsh restoration.

7.3 Existing and Future Without Project Condition *

This section described the existing and future without project conditions of the

Study Area as they relate to plan formulation and development of alternative

projects. Information regarding the existing condition was obtained from the

“Affected Environment” section of the FS/SEIS and information regarding the

future without project condition was obtained from the “Environmental

Consequences” Section of Volume II.

7.3.1 Existing Conditions

Elevations range from sea level along the Gulf Coast, to approximately +15 ft above

sea level along levee ridges. The Study Area is located within the Mississippi River

Deltaic Plain. The Mississippi River is the primary influence on geomorphic

processes in the delta region.

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7.3.1.1 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.

7.3.1.2 Climate

The climate is subtropical marine with long, humid summers and short, moderate

winters. It is strongly influenced by the water surface of many sounds, bays, lakes

and the Gulf of Mexico. During the fall and winter, cold continental air masses

produce frontal passages with temperature drops. During the spring and summer,

tropical air masses produce a warm, moist airflow conducive to thunderstorm

development (LACPRA, 2008).

Periods of drought, flood, tropical waves, tropical depressions, tropical storms, and

hurricanes occur. 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.

Average annual temperature in the area is 67 degrees Fahrenheit (° F), with

monthly temperatures varying from the mid-90s °F in July and August, to the mid30s °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 IPCC (2007) predicts continued or accelerated global

warming for the twenty-first century and possibly beyond, which will cause a

continued or accelerated rise in global mean sea level.

7.3.1.3 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

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abandoned, reworked, and submerged by marine waters (transgressive deposition).

The Plaquemines-Balize Complex is in the latter phase of the cycle.

7.3.1.4 Soils

The U.S. Department of Agriculture, Soil Conservation Services noted that there

are several different soils mapped in the Study Area. These are Commerce,

Sharkey, Clovelly, Lafitte, and Gentilly (SCS, 1992). 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, semifluid, 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, classified as prime

farmland soils, were rarely flooded and adequately drained, while the Gentilly,

Clovelly, and Lafitte soil series are classified as hydric soils.

7.3.1.5 Hydraulics and Hydrology

The LCA MDWD Study 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, 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 stream courses within the

estuary are the Oak River (also known as River aux Chenes) and Bayou Terre 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 Lery, 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 1-May 31), while low flows and low water levels are typical from midsummer 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, 2000b). Astronomical tides

have been observed as far upstream as the head of ship navigation in Baton Rouge,

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Louisiana. Strong south and southeasterly winds can cause rapid rise and

northwesterly winds rapid decline in the river’s stage (USACE, 2000b). Seasonally,

tides tend to be highest in late summer through mid fall (August-November) and

lowest in the winter and early spring (December-March). 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.

7.3.1.6 Sedimentation and Erosion

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 Study Area to maintain a

balance of emergent wetland and shallow water.

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; USGS, 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 LCA MDWD Study Area is subsiding at a rate of

approximately 0.50 ft per century. Just beyond the project boundary toward Head

of Passes, the rate increases to 1.0-4.0 ft per century.

7.3.1.7 Vegetation Resources

Vegetation in coastal Louisiana is inextricably linked to coastal hydrology. Two of

the major mechanisms of vegetation change in the region, which includes the Study

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 Study Area over the past 50 years. A more detailed

discussion of the relationship between regional hydrology and vegetation regimes in

the region is provided in the FPEIS for the LCA Ecosystem Restoration Study

(USACE, 2004b).

The Study Area includes riparian vegetation, wetland vegetation, upland

vegetation, and SAV. Riparian vegetation includes bottomland hardwood forest.

Bottomland hardwood forest is publicly important because of the high priority that

the public places on its aesthetic, recreational, and commercial value. Bottomland

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hardwood forest 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.

Various herbaceous wetland habitats are included in the Study Area. Intermediate

marsh (2-8 ppt salinity) habitat lies between freshwater marsh and brackish marsh

and the species of vegetation are not much different from freshwater marsh;

however, the dominance of the species is different. Approximately 18,771 acres of

intermediate marsh are present in the Study Area. Brackish marsh (4-18 ppt

salinity) habitat lies between intermediate marsh and saline marsh. Approximately

9,338 acres of brackish marsh are present in the Study Area. The saline marsh (8-

29 ppt salinity) community typically has the lowest plant species diversity of any

marsh type. Approximately 13,274 acres of saline marsh are present in the Study

Area.

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.

Little to no up-to-date field information is available on the current composition and

extent of SAV in the White Ditch Study Area. For purposes of the WVA analysis,

existing 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 WVA assessments

completed for the Monsecour Siphon Project in 2009, the Bertrandville Siphon

Project in 2008, and the White Ditch Siphon Project in 2004 (Appendix B, Volume

VI).

7.3.1.8 Salinity

For the White Ditch WVA assessment, baseline salinity values for the Study Area

were determined using 2008-2009 data from Coastal Reference Monitoring stations

located within or near the Study 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 ppt; the mean baseline was calculated as

4.0 ppt. Baseline salinity for brackish and saline marsh was representative of the

mean annual salinity recorded in 2008-2009. Baseline values of 6.6 ppt for the

brackish marsh zone were determined using station data that ranged from 5.0 to

9.9 ppt. A baseline value of 13.0 ppt 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.

7.3.1.9 Essential Fish Habitat

Aquatic and tidally influenced wetland habitats in portions of the LCA 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 GMFMC. Table 7-3 lists life stages and

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subcategories of EFH for these species that could benefit from or be 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 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 7-3, 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, groupers) and highly migratory species

managed by NMFS (e.g., billfishes, sharks)(NOAA, 2009).

Table 7-3: 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

Gulf of Mexico <5 m west from Mobile

Bay; all estuaries SAV,

sand/shell/soft/hard bottom, emergent

marsh

Adults Marine/

estuarine

Gulf of Mexico 1-46 m west from Mobile

Bay; all estuaries SAV, pelagic,

sand/shell/soft/hard bottom, emergent

marsh

Lane

snapper

Larvae Estuarine/

marine

4-132 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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7.3.1.10 Threatened and Endangered Species

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 LCA MDWD

Study Area, federally listed species include the pallid sturgeon, Gulf sturgeon, West

Indian manatee, piping plover, green sea turtle, Kemp’s Ridley sea turtle, and

loggerhead sea turtle. Table 7-4 includes information on the federally listed species

in the Study Area.

Known to occur near the study area and directly affected by diversion structures,

the pallid sturgeon is an endangered fish found in the Mississippi River (Lee et al.,

1980; Killgore et al., 2007). The species is adapted to large, free-flowing turbid

rivers. Detailed habitat requirements of this fish are not known, but it is believed to

spawn in Louisiana. Occurrence of pallid sturgeon in the Mississippi River near the

diversion site is extremely likely according to Kilgore et al. (2007) and based on

sampling efforts by Kirk et al. (2007) in 2005 and 2006. Presence of subadult and

adult pallid sturgeon is nearly certain within this reach of the Mississippi River;

however, occurrence of juvenile specimens is unconfirmed. Formal consultation on

the pallid sturgeon was conducted and a Biological Opinion was received on

September 23, 2010 from the USFWS. The USFWS determined that the level of

expected take is not likely to result in jeopardy to the pallid sturgeon (Volume VI

Appendix A).

Table 7-4: Federally Listed Threatened and Endangered Species in the

Study Area

Species Critical Habitat Status Jurisdiction

Federal State USFWS NMFS

West Indian manatee

(Trichechus manatus) E E X

Piping plover

(Charadrius melodus) T T X

Hawksbill sea turtle

(Eretmochelys imbricata) E E X X

Kemp’s Ridley sea turtle

(Lepidochelys kempii) E E X X

Leatherback sea turtle

(Dermochelys coriacea) E E X X

Green sea turtle

(Chelonia mydas) T T X X

Loggerhead sea turtle

(Caretta caretta) T T X X

Pallid sturgeon

(Scaphirhynchus albus) E E X

Gulf sturgeon

(Acipenser oxyrinchus

desotoi)

T T X X

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7.3.1.11 Cultural 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 Study 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 Study Area

and will not be affected by the White Ditch Diversion.

7.3.1.12 Recreation

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. Nonconsumptive recreational activities appear to be

minimal and include wildlife observation.

7.3.1.13 Socioeconomic Resources – Navigation

The Study Area has not been used extensively for shallow water navigation, and

there is no deep water navigation possible in the marsh area. There are man-made

canals once used by oil companies, but commercial use of these canals is limited;

they are now used mostly for recreational purposes.

7.3.1.14 Socioeconomic Resources – Oil, Gas, and Utilities

The LCA MDWD Study Area contains some pipelines that cross LA Highway 39.

There are utility service lines that traverse the length of LA Highway 39 servicing

the communities located south of the proposed diversion structure. There are no oil

refineries or rigs located within the diversion area.

7.3.1.15 Socioeconomic Resources – Commercial Fisheries

The LCA MDWD Study Area contains fishing, shellfish, and aquatic resources

within the Freshwater Diversion vicinity.

7.3.1.16 Socioeconomic Resources – Oyster Leases

Areas east of the Mississippi River and the Barataria Basin dominate oyster

production in Louisiana. St. Bernard and Plaquemines parishes encompass

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virtually all oyster producing areas east of the river. From 1988 through 1997,

these two parishes accounted for approximately 50% of the oysters landed in

Louisiana and approximately 47% of landings from private leases in Louisiana.

Monitoring data from the existing Caernarvon Diversion Structure has shown that

production of both oysters and menhaden have increased.

7.3.2 Future Without Project Condition

7.3.2.1 Soils

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 Study Area would not be able to maintain their elevations due to subsidence,

decreased plant productivity, wave erosion, and RSLR. Net primary productivity

within the Study 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, and

aesthetic and socioeconomic resources. In the future, if no actions are taken to

restore and protect marsh habitat within the Study 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.

Cumulative impacts under the No Action Alternative include continuing erosion

and loss of marsh soils. Water bodies would grow larger, and wave erosion would

accelerate causing further land loss, thus making remaining marshlands in the

Study 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.

7.3.2.2 Hydraulics and Hydrology

The No Action Alternative would have no direct impacts on flow or water levels

within the surrounding marsh or historical distributaries, such as River aux

Chenes.

Indirect impacts of the No Action Alternative, not implementing the diversion,

would result in the persistence of existing conditions. Consequences would include

increased degradation of the existing marsh from saltwater intrusion due to shortcircuited hydrologic processes present in the basin, as well as the continued lack of

sediments, nutrients, and freshwater in the River aux Chenes and the Mississippi

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River. 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 salt water, 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 EC 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 historical rate of RSLR for the Study Area. Sea level rise

is shown in Figure 7-2.

Estimated Sea Level Rise for White's Ditch IAW EC-1165-2-211

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

2000 2010 2020 2030 2040 2050 2060 2070

Year

Estimated Sea Level Rise (feet)

Low curve (historic) Intermediate curve High curve

Figure 7-2: Sea level rise rates for the White Ditch Study Area

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

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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 LCA MDWD

Study Area, albeit to an unknown extent, and could impact the flow patterns in and

near the Study Area, but would not likely affect water levels in the Study Area.

The proposed CWPPRA project for the rehabilitation and expansion of the existing

siphon at White Ditch could have impacts on the Study 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.

7.3.2.3 Sedimentation and Erosion

The No Action Alternative 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

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 Study Area to maintain a balance of emergent

wetland and shallow water.

Indirect impacts of the No Action Alternative are the persistence of existing

conditions. 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.

7.3.2.4 Vegetation Resources

For direct impacts under the No Action Alternative, no BLH would be cleared or

filled by construction activities. No opportunities for beneficial use of dredged

material for construction features would occur. Existing bottomland hardwood

forest 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 SAV would occur. Baseline

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SAV coverage was estimated at approximately 15% of open water areas near the

proposed construction footprint (25% in the overall Study 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.

Indirect impacts include the continued erosion of marsh soils and continued

fragmentation and conversion of bottomland hardwood forest 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 bottomland hardwood forest species in the Study Area

would experience continued subsidence, sea level rise, and salinity increases. The

bottomland hardwood forest 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 coastwide bottomland hardwood forest loss and degradation, as well as the benefits and

impacts of other local, state, Federal, and private projects summarized in the

FS/SEIS (Volume VI). 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 result in a

selected plan having features that create and restore bottomland hardwood forest

ridges from the secondary use of channel dredging to redirect water flows. The

USACE MVN has issued some Section 10 and 404 permits for maintenance

dredging canals northeast of the LCA MDWD Project. Some dredged material

placement areas from this dredging would likely reforest with bottomland hardwood

forest 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 freshwater marsh in areas adjacent to the LCA MDWD

Study Area. However, such wetland conversion would probably have little effect on

the species composition of the wetlands in the Study Area other than a slight shift

toward less salt-tolerant species. The introduction of nutrients would likely

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increase the productivity of the nearby marshes, but any potential effects on

productivity within the LCA MDWD Study 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/SEIS. 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. LCA

CFDM could result in a conversion of some intermediate marsh to freshwater

marsh in areas adjacent to the LCA MDWD Study Area. The Duffy study (1997)

showed that SAV abundance (Eurasian water milfoil 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 LCA MDWD Study Area are unknown at this time.

7.3.2.5 Salinity

Under the No Action Alternative, no direct impacts to salinity levels of the

Mississippi River or the LCA MDWD Study 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 LCA MDWD Study 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.

7.3.2.6 Essential Fish Habitat

The No Action Alternative 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 continued conversion of categories of EFH, such as estuarine marsh and SAV, to

marine water column and mud, sand, or shell substrates. 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 Study

Area would reduce the area’s ability to support all fishery 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

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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.

7.3.2.7 Threatened and Endangered Species

The No Action Alternative would have no direct impacts on listed species or their

critical habitat in the Study Area.

The loss and deterioration of transitional wetland habitats over time could continue

to indirectly affect, to an undetermined degree, all listed species that may

potentially utilize the Breton Sound Basin including Gulf sturgeon, green sea turtle,

hawksbill sea turtle, Kemp’s Ridley sea turtle, leatherback sea turtle, loggerhead

sea turtle, brown pelican, piping plover, and the West Indian manatee.

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

Study 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.

7.3.2.8 Cultural Resources

Under the No Action Alternative, no archeological sites would be directly impacted

by construction activities. Indirect impacts are that all archaeological sites within

the Study Area would continue to be affected by erosion and subsidence.

Archaeological sites in southeast Louisiana are all subjected to the same cumulative

impacts, including natural forces, subsidence, and erosion from natural wave action,

storm surge, and wakes created by motorboats. Eventually, most sites would

disappear from the archaeological record unless protected.

7.3.2.9 Recreation

Recreational resources in the region that would most likely be directly affected

under the No Action Alternative are those related to loss of wetlands and habitat

diversity. Lower quality fishery 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 wetlanddependent wildlife would likely decrease as these species relocate to find more

suitable transitional wetland habitats. 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.

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Long-term potential indirect impacts may include loss of associated recreational

support facilities, such as marinas and bait shops that are the basis for most

recreational use. This would result in a reduction in economic activity associated

with recreation uses.

Cumulative effects of the Caernarvon Diversion on recreational resources in the

LCA MDWD Study Area are expected to be minimal. The effects on recreational

resources are 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 Study Area, as described in the direct and indirect impact sections.

7.3.2.10 Socioeconomic Resources – Navigation

There would be no direct or indirect impacts on navigation in the Study Area and

vicinity if the proposed diversion were not constructed. 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.

7.3.2.11 Socioeconomic Resources – Oil, Gas, and Utilities

There would be no direct or indirect impacts on oil, gas, and utilities in the Study

Area and vicinity if the proposed diversion were not constructed. 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 Greater New Orleans

Area HSDRRS, and existing and in-progress elements of the LCA Program,

including development of freshwater diversion projects. Under the No Action

Alternative, direct cumulative impacts remain no greater than the sum of those

impacts indicated individually for each project component of the aforementioned

programs.

7.3.2.12 Socioeconomic Resources – Commercial Fisheries

There would be no direct impacts on natural resources and commercial fisheries

within the Study Area and vicinity if the proposed diversion were not constructed.

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 Study 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-freshwater areas. Over

the 50-year planning horizon, EFH for many commercial fishery species would

likewise decline, leading to a net loss in fisheries population size and diversity.

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The commercial fishing and seafood industry could suffer losses in employment as

estuaries that are 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.

7.3.2.13 Socioeconomic Resources – Oyster Leases

There would be no direct impacts to oyster leases in the Study Area and vicinity if

the proposed diversion were not constructed. Under no action, 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 Study Area would continue. 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 Study Area could degrade if salinity shifts above the optimal

level. 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.

Without the contribution of the LCA MDWD, continued wetland habitat losses

would incrementally decrease the productivity of Louisiana's coastal fisheries,

including oyster beds. The commercial fishing and seafood industry could suffer

losses in employment as estuaries that are 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.

7.4 Alternatives *

This chapter presents the alternative plan formulation process, alternative

evaluation criteria, selected alternatives for detailed analysis, and plan

implementation and management.

7.4.1 Plan Formulation Rationale

This section provides an overview of the plan formulation process for the LCA

MDWD. A total of 22 general measures and 5 alternatives plus the No Action

Alternative were considered and evaluated.

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7.4.2 Management Measures

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 PDT.

Based on a review and analysis of prior studies, initial site visits, and input

received through the scoping process, the following initial list of general

management measures was developed.

Freshwater Supply

F1 - Uncontrolled Diversion (MR&T Levee Removal): 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.

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. 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 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 LCA MDWD Study Area. The flow would be driven only by the

difference in hydrostatic pressure between the river side and the Study Area

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without any need for pumping. To achieve a minimum diversion of 5,000 cfs,

several large siphons could be required.

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 flow rate.

Hydraulic Distribution (H)

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 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 be 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.

Sediment Supply and Distribution (S)

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:

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

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sensitive marsh habitats. These include concrete pumps on floating

platforms and conveyor belts.

S3 - Importation and Placement of Regional Sediments: 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 LCA MDWD reach of the Mississippi River. It is possible

to make use of channel maintenance material for beneficial use as well as

long-range transport of suitable sediments from USACE MVD ecosystem

projects 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.

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.

Protection (Existing Marshes) (P)

P1 - Barrier Islands: A series of smaller constructed barrier islands on the

south-east edge of the Study Area would serve to disrupt storm surge and

damage to project features.

P2 - Rock Dikes: Areas of existing high quality marsh could be made more

resilient to seasonal Gulf events by construction of rock shoreline protection.

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.

P4 - Construct Terraces: Terraces could be constructed in open water

habitats to help trap sediments that move through the area.

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.

There were a total of 24 management measures included in the initial screening.

As an initial step, the screened list of management measures was evaluated based

on benefits, constraints, and relative costs. Based on that initial screening of the

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management measures, 10 management measures were retained for further

analysis. The retained management measures were then grouped into a

preliminary array of five alternatives and the No Action Alternative for further

evaluation to achieve the overall study goals and objectives. The five alternatives

were formulated to consider five different options for the diversion flow rate and five

options for location.

7.4.3 Preliminary Alternative Plans

The preliminary array of five alternatives was evaluated for benefits, constraints,

and relative costs. All of the action alternatives have freshwater diversions as the

base option with measures added as more data become available in later stages of

the feasibility. Based on discussions with the non-Federal sponsor and PDT review

of goals and objectives, the following conceptual alternatives have been defined:

Conceptual White Ditch (CWD) 1: No Action.

CWD2: 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.

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,

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.

CWD4: 45,000 cfs Freshwater Diversion. This alternative involves construction

of a structure capable of diverting up to 45,000 cfs. Additionally, measures from the

hydraulic distribution (H), sediment supply & distribution (S) and protection and

sustainability will be refined to improve beneficial distribution of freshwater and

sediments to create and restore marsh habitat and improve its sustainability.

CWD5: 75,000 cfs Freshwater Diversion. This alternative involves construction

of a structure capable of diverting up 75,000 cfs. Additionally, 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.

CWD6: 100,000 cfs Freshwater Diversion. This alternative involves

construction of a structure capable of diverting up to 100,000 cfs. Measures from

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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 as described in the original project

objectives, 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 LCA Diversion Project

at Myrtle Grove on the opposite bank of the Mississippi River completed hydraulic

modeling evaluation of the same range of diversions (45,000, 75,000, and 100,000)

and identified significant issues with impacts to the MR&T and back levees, a

situation very similar to the LCA MDWD Study Area. Table 7-5 lists the

alternatives eliminated from further consideration and why.

Table 7-5: Conceptual Alternatives Screened from Further Consideration

Alternative Symbol Justification for Elimination

from Further Consideration

45,000 cfs

freshwater

diversion

CWD4

Significant impacts were identified at Myrtle Grove in evaluating

the 45,000 cfs diversion option. Sustained water levels in excess

of 3 feet were identified. Similar water levels could be expected

within the LCA MDWD Study Area. 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 LCA Myrtle Grove in

evaluating the 75,000 cfs diversion option. Sustained water

levels in excess of 3 feet were identified. Other impacts are the

same as those identified for the 45,000 cfs diversion.

100,000 cfs

freshwater

diversion

CWD6

Significant impacts were identified at LCA Myrtle Grove in

evaluating the 100,000 cfs diversion option. Sustained water

levels in excess of 3.5 feet were identified. Other impacts are the

same as those identified for the 45,000 cfs diversion

7.4.3.1 Location for Diversion

The various conceptual alternatives are 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 sizes ranging from 5,000

to 35,000 cfs. The remaining nondiversion measures 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

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maximize marsh creation. 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 LCA MDWD 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 ft to 2,700 ft.

Location 2: Location 2 is at the existing siphons at White Ditch. There are no

residences in the potential construction footprint. Several small recreational

buildings and an electrical substation are 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 ft. It is considered a

good location for sediment.

Location 3: Location 3 is just north of Phoenix, Louisiana. No known structures

are 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 ft north on the MR&T

levee. The White Ditch VE team identified this area as a good location to intake

sediment because it is on a point bar. It is centrally located within the LCA MDWD

Study Area and could yield benefits to the north and south.

Location 4: Location 4 is in the central portion of the LCA MDWD 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 ft. 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.

Location 5: Location 5 is in the central portion of the LCA MDWD 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 ft to 2,900 ft.

This area was recommended for consideration in the VE Study. It was identified as

a good location to intake sediment and deliver environmental benefits to the

southern end of the Study Area.

The five potential locations for diversion structures are shown in Figure 7-3. A

screening process was used to determine which of the locations were most suitable

for further evaluation. Criteria evaluated include the following:

Back levee cost: Several locations would need to cross residential areas with

back levees. The cost of crossing two levees would be high.

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Lack of beneficial sediment: Certain locations have high sediment load along

the Mississippi River and would be ideal for capturing river sediments.

Hydrology and hydraulics: The northwest to southeast flow of water to the

Gulf indicates that a diversion located toward the lower downstream end of

the project sites would be less effective at distributing the requisite

freshwater, sediment, and nutrients (See Volume VI, Appendix L for

additional discussion).

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.

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.

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 ft. Locations 2 and 3 also have

the advantage of being centrally located and directly adjacent to much of the most

degraded marsh within the Study Area.

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), hydraulic modeling indicated that it would require 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 new

conveyance channels, provides the opportunity to design the channels to more

efficiently to distribute flows of freshwater, nutrients, and sediments. At this point,

Locations 2 and 3 were retained for additional analysis.

After the screening of the larger-sized diversion, the PDT decided that for a full

array of alternatives to be evaluated a diversion larger than the 2004 LCA Report

description would be required. Since the original concepts for an alternative over

the 2004 15,000 cfs project (45,000 - 100,000 cfs) proved unacceptable for reasons

shown in Table 7-5, the PDT developed and discussed a 30,000 cfs diversion because

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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.

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As the PDT progressed through their hydrology and hydraulics assessment, they

developed a minimum operating condition for all of the structures such that the

structures could operate at design flows at any time during a typical year with a

minimum of 1-foot head differential on the Mississippi River, which is an average

low stage. The structure design for the 15,000 cfs diversion (ten 15-foot by 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 Locations 2 and 3.

The remaining conceptual alternatives 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 follow:

No Action (Future without Project Conditions): 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.

White Ditch (WD) 2: Location 2 - 5,000 cfs structure with features 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.

WD 3: Location 2 - 10,000 cfs structure with features 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.

WD 4: Location 2 - 15,000 cfs structure with features 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.

WD 5: Location 2 - 35,000 cfs structure with features 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.

WD 6: Location 3 - 5,000 cfs structure with features from the hydraulic distribution

(H), sediment supply & distribution (S), and protection and sustainability (P) will be

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refined to improve beneficial distribution of freshwater and sediments to create and

restore marsh habitat and improve its sustainability.

WD 7: Location 3 - 10,000 cfs structure with features 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.

WD 8: Location 3 - 15,000 cfs structure with features 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.

WD 9: Location 3 - 35,000 cfs structure with features 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.

7.4.4 Identification of the Final Array of Alternatives

After an initial cost analysis was completed on the preliminary array of

alternatives, it was determined that all of the alternatives at Location 2 were not

cost effective while the 5,000; 10,000; and 15,000 cfs diversions at Location 3 were

cost effective. The 35,000 cfs diversion was considered a Best Buy. Consequently,

the final array of alternatives included the 5,000; 10,000; and 15,000 cfs diversion at

Location 3 for a detailed analysis.

7.4.5 Environmental Consequences *

An analysis was conducted on the potential environmental consequences of

implementing alternative plans for the LCA MDWD. The analysis compares the No

Action Alternative to the alternatives retained for detailed analysis. The No Action

Alternative is considered to be the same as the future without project condition and

analyzes the future conditions of the resource over a 50-year period of analysis from

2015 to 2065.

The operational scenario used in the evaluation of all alternatives 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 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 LCA MDWD Study Area are more likely to be

reduced or minimized if flows are limited in duration and are timed to avoid

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sensitive periods in the annual life cycles of marsh vegetation and associated

aquatic organisms.

No Action Alternative (Future without Project Conditions): Under the No

Action Alternative, as erosion continued, there would be a continued loss of marsh

soils. Water bodies would grow larger, and wave erosion would accelerate, causing

further land loss, thus making remaining marshlands in the Study Area and the

larger Breton Sound Basin more vulnerable to tropical storms. The No Action

Alternative would result in the existing marsh continuing to degrade due to

minimal circulation of water, nutrients, and sediment. Subsidence and sea level

rise would exacerbate the degradation. Under the current rate of loss, it is

predicted that most of the marsh will be lost in 50 years.

Alternative 1 - 5,000 cfs Max Diversion: Construction of the 5,000 cfs maximum

diversion would directly impact marsh. This excavated material would be placed on

organic marsh soils and aquatic substrates to create marsh in locations adjacent to

the outfall channels. This is summarized in Table 7-6 Indirect beneficial impacts of

implementing the 5,000 cfs max diversion would include the expected decrease in

rate of loss of existing marsh acreage. Table 7-7 summarizes wetland loss/creation.

Indirect impacts to hydrology would be the inundation of lands while the structure

is being operated. 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 historical deltaic processes.

Alternative 2 - 10,000 cfs Max Diversion: Construction of the 10,000 cfs

maximum diversion would directly impact marsh. This excavated material would

be placed on organic marsh soils and aquatic substrates to create marsh in locations

adjacent to the outfall channels. This is summarized in Table 7-6. Indirect

beneficial impacts of implementing the 10,000 cfs max diversion would include the

expected maintenance of existing marsh acreage. Table 7-7 summarizes wetland

loss/creation. Indirect impacts to hydrology would be the inundation of lands while

the structure is being operated. 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 historical deltaic processes.

Alternative 3 - 15,000 cfs Max Diversion: Construction of the 15,000 cfs

maximum diversion would directly impact marsh. This excavated material would

be placed on organic marsh soils and aquatic substrates to create marsh in locations

adjacent to the outfall channels. This is summarized in Table 7-6. Indirect

beneficial impacts of implementing the 15,000 cfs max diversion would include the

expected creation of small amounts of new marsh. It is believed that it would be a

sufficient amount to slightly exceed the current rate of marsh loss. Table 7-7

summarizes wetland loss/creation. Indirect impacts to hydrology would be the

inundation of lands while the structure is being operated. However, with this

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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 historical deltaic processes.

Alternative 4 - 35,000 cfs Max Diversion: Construction of the 35,000 cfs

maximum diversion would directly impact marsh. This excavated material would

be placed on organic marsh soils and aquatic substrates to create marsh in locations

adjacent to the outfall channels. This is summarized in Table 7-6. Indirect

beneficial impacts of implementing the 35,000 cfs max diversion would include the

expected creation of large amounts of new marsh. It is believed that it would be a

sufficient amount to exceed the current rate of marsh loss and have the potential for

restoring the marsh back to its historical acreage. Table 7-7 summarizes wetland

loss/creation. Indirect impacts to hydrology would be the inundation of lands while

the structure is being operated. 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 historical deltaic processes.

Alternative 4 has the greatest potential for creating new marsh habitat, managing

risk and uncertainty, and providing adaptive management opportunities.

Table 7-6: Benefits Summary (in AAHUs)

Outfall Management

Features

a

Alt. 1 Alt. 2 Alt. 3 Alt. 4

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 (in AAHUs)

Marsh Type

Alt. 1 Alt. 2 Alt. 3 Alt. 4

Freshwater/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

a The WVAs were updated during the review process. Updated AAHUs and acres are included in Volume VI,

Appendix B. There was no significant change in these values.

Table 7-7: Acerage Summary

Alternative

a

WVA AAHU’s

March/April Open +

1,000 cfs Maintenance Flow

Year 0 = 2015

Gross/Net Acres

March/April Open +

1,000 cfs Maintenance Flow

Year 0 = 2015

No Net Loss Acres = 39,587

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1: Location 3 - 5,000 cfs 5,197 35,638 / -3,949

2: Location 3 - 10,000 cfs 5,936 40,419 / 562

3: Location 3 - 15,000 cfs 7,742 45,046 / 5,459

4: Location 3 - 35,000 cfs 13,355 59,902 / 20,315

a The WVA assessment was updated during the review process. The updated AAHUs and acres affected can be found in

Volume VI, Appendix B. There was no significant change in these values as a result of the update.

7.4.6 Comparison of Alternative Plans

The four alternatives in the final array were compared based on benefits, costs, and

impacts. The first cost and annual costs for the final four alternatives are noted in

Table 7-8.

Table 7-8: Incremental Cost/ Cost Effectiveness Step

Item

Cost

Alt. 1

(5,000 cfs)

Alt. 2

(10,000 cfs)

Alt. 3

(15,000 cfs)

Alt 4

(35,000 cfs)

Total costa $152,900,000 $174,200,000 $241,700,000 $329,300,000

Annualized first cost $7,580,348 b $8,636,342 $11,982,801 $16,325,760

Annual OMRR&R

costs $781,804 $871,463 $1,131,044 $1,467,836

Total annualized cost $8,362,152 $9,507,805 $13,113,845 $17,793,596

a Includes real estate; discount rate 4 3/8%

b Preliminary cost estimates were developed for planning purposes and are not fully funded costs.

Table 7-9 shows that Alternatives 1, 2, 3, and 4 are cost effective. Aside from the

No Action Alternative, Alternative 4 exhibits the lowest cost per unit of all

alternatives at $1,311 per AAHU. Alternative 3 exhibited the highest cost per unit

at $1,694 per AAHU.

The WVA model is undergoing model certification in accordance with EC 1105-2-

407. The model has undergone external review, and the WVA revision

documentation and spreadsheets have been submitted to the ECO-PCX. The ECOPCX 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

this project can be found in Appendix K of Volume VI.

Table 7-9: Summary of WVA Analysis AAHUs and IWR Planning Benefits

for Final Alternative Array

Alt. 1 Alt. 2 Alt. 3 Alt. 4

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AAHUs 5,197 5,936 7,742 13,355

Total Annualized Costa $8,362,152 $9,507,805 $13,113,845 $17,793,596

Cost effective Yes Yes Yes Yes

Best Buy Yes

Cost/HU $1,609 $1,602 $1,694 $1,332

Incremental Cost/HU $1,609 $1,550 $1,997 $834

a Preliminary cost estimates were developed for planning purposes and are not fully funded costs.

The alternatives were also evaluated on the acres of area that would benefit from

the project. Acres of benefit include ridge and marsh creation as well as channel

enlargement and are shown per alternative in Table 7-10.

Table 7-10: Direct Footprint Acreage Impacts

Alternative No.

Ridge

Creation

(Acres)

Marsh

Creation

(Acres)

Channel

Enlargement

(Acres)

1: Loc 3 - 5,000 cfs Diversion 32 139 153

2: Loc 3 - 10,000 cfs Diversion 32 176 167

3: Loc 3 - 15,000 cfs Diversion 32 235 182

4: Loc 3 - 35,000 cfs Diversion 31 385 223

7.4.7 National Ecosystem Restoration Plan

The NER plan reasonably maximizes ecosystem restoration benefits compared to

costs, considering the cost effectiveness and incremental cost of implementing other

restoration options. Alterative 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-foot-by15-foot box culverts. 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.

The non-Federal sponsor supports the NER plan; therefore, no separate LPP is

identified. The NER plan is also identified as the EPP since it maximizes the

environmental benefit.

7.4.8 Plan Selection – Recommended Plan

The USACE, through the interagency team selects Alternative 4 as the

recommended plan as this plan best meets the screening criteria; would accomplish

the planning objectives and goals; would be consistent with the USACE EOPs; and

would best satisfy the intent of WRDA 2007 for a medium diversion at White Ditch.

This plan would generate 13,355 AAHUs and result in restoration of deltaic

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processes within the Study Area. In cooperation with the USFWS, NOAA, and the

State of Louisiana, the USACE has planned and would design a project that serves

the needs of the nation. The recommended plan is also the NER plan, Alternative 4,

and the plan cost exceeds the authorization for this project. The recommended plan

/ NER has been determined to reasonably maximize ecosystem restoration benefits

compared to costs, consistent with the Federal objective. Due to the nature of the

diversion and the analyses completed, a separable element of the NER plan could

not be identified.

The recommended plan would have 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 (May-February).

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 chosen pulse regime would minimize adverse effects to natural

socioeconomic resources and mimic a natural hydrologic regime. The March-April

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 March-April timeframe,

flows would be based on conditions. 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 doesn’t 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

result in freshening of the Breton Sound Basin to a comparable degree. The

performance obtained by coupling a 35,000 cfs structure with the March-April pulse

regime made the recommended plan unique among the alternatives considered. It

can attain project objectives while minimizing adverse impacts to natural and

manmade resources. The duration of the diversion operation determines the size of

the effect on salinity regimes, not the flow rate 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. A small diversion

would run for longer periods of time to deliver similar amounts of sediment. Longer

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runs would disturb desirable estuarine salinity gradients and create conditions

unfavorable to vital natural socioeconomic resources while also creating favorable

conditions for nuisance invasive plant species. There is also a limit on how big a

diversion can be which is dictated by the conditions of the Study 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 (2015-2065). 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. In summary, the recommended plan has the potential to reverse the

decline of marsh habitats occurring now and in the future within the Study Area

and provides sustainability in the face of uncertainty surrounding relative sea level

rise.

In order to proceed to the next phases of the proposed project, including 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

amending language from House/Senate subcommittees that adjusts the project as

authorized in WRDA 2007 to account for the increase in the construction cost

estimate. Table 7-11 shows the fully funded project cost. Figure 7-4 shows the

recommended plan.

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Table 7-11: Maximum Cost Including Inflation Throuh Construction

Authorized cost in WRDA 2007 Title VII,

Section 7006 (e)(3)(A):

$86,100,000

Cost index useda CWBS Feature Code 15

Floodway Control & Diversion

Structure

:

EM 1110-2-1304 (Revised 31 Mar 2010)

Cost index ratio:

1Q FY07 to 3Q FY14

1.15

Fully funded project cost estimateb: $99,015,000

(Inflation applied from 10/2006 to 4/2014)

20% of authorized cost: $17,220,000

Monitoring and adaptive managementc $11,143,400 - $692,000

= $10,451,400

:

(per WRDA 2007 Section 2039)

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

a The cost index applied is derived from: EM 1110-2-1304, 31 Mar 10, CWCCIS. b For the purposes of applying the cost index to the WRDA authorized cost, each project was adjusted

for inflation from October 2006 price levels to the midpoint of construction.

c 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.

7.4.8.1 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 ten box

culverts each sized 15-foot by 15-foot 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. This project 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.

7.4.8.2 Design, Environmental, and Construction Considerations

The recommended plan is also the NER plan, Alternative 4, and the plan cost

exceeds the authorization for this project. The USACE District Commander

recommends seeking additional authorization in order to construct the

recommended plan / NER plan.

Other major project considerations follow:

Ensure that stability of the Mississippi River Levee would not be

compromised during construction.

Continued access of LA Highway 39, a major evacuation route, would be

maintained during construction.

Structure construction would be done in accordance with industry standards.

Construction of the channel conveyance systems would be done in accordance

with industry standards.

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Ridge restoration features would make use of beneficial spoil from the

channel conveyance systems and would be done in accordance with industry

standards.

Any excess spoil from the channel conveyance systems, beyond the ridge

restoration features, would go into marsh creation. These marsh creation

features would be built to industry standards.

7.4.8.3 Real Estate Requirements

There is a total of 1,161.2 acres required for this project. The diversion structure

would 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

detailed discussion of the real estate requirements is included in Volume VI,

Appendix J.

Although the White Ditch diversion would increase the frequency of inundation in

the interior marshes during the March-April pulse, the project would not interfere

with economically viable uses of the property. Therefore, flowage easements are not

necessary within the Study 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.). More detailed discussion

regarding real estate issues may be found in Volume VI, Appendix J, and Real

Estate Plan.

7.4.8.4 Operation and Maintenance Considerations

For purposes of analysis, it was assumed that the diversion would operate at

maximum capacity during March-April with a 1,000 cfs maintenance flow for the

remainder of the year.

Operations for the diversion would be determined and modified based on Adaptive

Management. The operation of this structure would 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 undesired impacts to the

Mississippi River, such as induced shoaling.

With the proposed diversion, there would be needs for channel maintenance

dredging and sluice gate maintenance. It is estimated that there would need to be

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channel dredging every 10 years on the proposed channel enhancement features. It

is also assumed that there would be annual maintenance and lubrication needs

provided to the sluice gates. Information about the costs for OMRR&R is included

in Table 7-12. More detailed information on the O&M of the proposed diversion can

be found in the engineering appendix of the FS/SEIS (Volume VI).

Table 7-12: OMRR&R Annualization for Recommended Plan

Annualized

Operations -

Culvert

Operations

& Gate

Maintenance

Channel

Maintenance

Dredging

Present

Value

Riprap

Replacement

Present

Value

Structural

Rehabilitation

Present Value

Annualized

Cost of

Present

Value

Components

Total

Annualized

OMRR&R

Alt. 4: Location

3 - 35,000 cfs

Box

a

$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

a Preliminary costs were developed for planning purposes only. Cost estimate is not the fully funded cost.

7.4.8.5 Monitoring Plan and Adaptive Management Plan

7.4.8.5.1 Description of Monitoring Activity and Adaptive Management

A feasibility level monitoring and adaptive management plan has been developed

for the project (Volume VI, Appendix I). The monitoring and adaptive management

plan was developed to include a sufficient description of the proposed monitoring

and adaptive management activities to identify the nature of proposed adaptive

management activities and to estimate the costs and duration of the monitoring and

adaptive management plan. The monitoring and adaptive management plan

identifies the restoration goals and objectives identified for the project; outlines

management actions that can be undertaken to achieve the project goals and

objectives; presents a conceptual ecological model that relates management actions

to desired project outcomes; and lists sources of uncertainty that recommend the

project for adaptive management. Monitoring, assessment, decision making, data

management are also addressed in the monitoring and adaptive management plan.

7.4.8.5.2 Performance Measures for Monitoring

The plan identifies performance measures along with desired outcomes and

monitoring designs in relation to specific project goals and objectives.

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 (1985 - 2012).

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Desired Outcome: Maintain and/or increase acreage of marsh habitats

from pre-construction estimates (41,206 acres).

Monitoring Design: Habitats would be classified using Landsat TM scenes

collected in 3 pre- and 10 post-project years and DOQs for 1 pre- and 2 postproject 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

would be assessed by increasing the number of LDWF finfish and shellfish

sampling sites in the White Ditch Study Area.

Objective 2: Restore adequate freshwater and nutrient inputs into the Study 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 would be

established for assessing Study Area vegetation communities. These stations

would be sampled 3 years prior to project completion to assess pre-project

conditions and 10 years post-construction.

Supporting Information Need: Salinity and hydroperiod would be

assessed by establishing nine hydrologic sites in project and reference areas.

Risk Endpoint: Nutrient loading

Desired Outcome: Nutrient introductions do not contribute to reduced

biomass of belowground plant material when compared to preconstruction

estimates.

Monitoring Design: Belowground biomass would be sampled quarterly at

the nine vegetation sites. These stations would 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 would 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 pre-project conditions

and sampled for 10 years post-construction.

Desired Outcome: Nutrient introductions do not contribute to expansion of

floating aquatic vegetation (water hyacinth) in Study Area when compared to

pre-construction estimates.

Monitoring Design: The distribution of water hyacinth throughout the

Study Area would be tracked by visual assessment of water hyacinth cover

from overflights during summer.

Objective 3: Restore sediment inputs into the Study Area equivalent to an average

of approximately 1,328,580 CY of sediment per year.

Performance Measure: Annual sediment discharge

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Desired Outcome: Deliver 1.328M CY (equivalent to 1.422M tons) of

sediment through the White Ditch diversion each year.

Monitoring Design: Hourly turbidity recorder would be deployed in the

outfall channel and at nine hydrologic sites and correlated to TSS to

investigate this measure. The sites would be measured for 3 years prior to

project completion to assess pre-project conditions and sampled for 10 years

post-construction.

Performance Measures: Accretion and subsidence

Desired Outcome: Maintain marsh elevation within tidal frame (RSLR = 0

cm/yr).

Monitoring Design: SET/feldspar stations would be sampled at nine

hydrologic sites for assessing Study 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.

7.4.8.5.3 Costs for Implementation of Monitoring and Adaptive Management

Programs

The costs associated with implementing the monitoring and adaptive management

plan were estimated based on currently available data and information developed

during plan formulation as part of the feasibility study. The costs estimated would

be refined in PED during the development of the detailed monitoring and adaptive

management plans.

The current total estimate for implementing the monitoring and adaptive

management programs is $11,143,000 based on October 2010 price levels. In

accordance with WRDA 2007 Section 2039, the monitoring costs presented in the

report are for the full allowable 10 year period and represent conservative and

comprehensive costs. Section 2039 guidance does allow for the monitoring to end

prior to the 10-year period if the Secretary determines that the success criteria have

been met. The costs presented in the report are for the full 10 year period but

monitoring may end prior to the 10 years. The monitoring plans and costs were

developed by the interagency LCA Adaptive Management Planning Team in

conjunction with stakeholders and have been determined to be a reasonable plan

and estimate for the recommended plan and are what is needed and necessary to be

able to determine project success. Adaptive management costs include program

establishment and implementation over 10 years.

7.4.8.6 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:

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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 (2015-2065), 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. 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 RSLR.

The recommended plan is capable of achieving no net loss of marsh acres

accounting for the intermediate RSLR 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 plan's location (USGS gages

data), the recommended plan would provide adequate supplies of both to

maintain current areas of marsh. The pulsed operation of the recommended

plan would 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.

7.4.8.7 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 USACE EOPs.

7.4.8.8 Compensatory Mitigation Measures

The project would provide positive ecosystem benefits to the Study Area.

Temporary negative marsh impacts associated with excavation of outfall canals and

management structures would be compensated for by creation of new marsh of

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better quality as a result of the reintroduction of freshwater, nutrients, and

sediments into the Study Area. No mitigation measures are needed.

7.4.9 Risk and Uncertainty

Risk and uncertainty would be discussed as they relate to the ability of the proposed

system to meet the project objectives. Risk is defined as the reliability of an

estimated value. Uncertainty is a measure of imprecision of knowledge of

parameters and functions used to describe aspects of a project plan, such as the

hydrologic, environmental, and engineering design, operational performance and

maintenance needs, as well as construction and economics.

Induced Shoaling: 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.

The current operating plan for the LCA MDWD 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 would be the largest man-made diverted flow for wetland building on the

Lower Mississippi River, but the 1- to 2-month duration would be a modifying

factor. The diversion should be approximately 5% or less of the main channel flow

for most years. Although some deposition in the downstream channel could 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 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 LCA MDWD are required to better address the amount of deposition expected.

Specific sediment transport studies to better address the amount of deposition

expected would be conducted during PED. If induced shoaling that adversely

affected navigation were to occur as a direct result of the LCA MDWD Project, the

cost for dredging or other operations and maintenance activities would be borne by

the non-Federal cost share sponsor.

EDRC-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 Study Area. Several sites were initially considered for the proposed

diversion; however, equivalent data for each site was not available. Ideally, data

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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 Tarbert’s 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 Study 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 sites 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 indicate 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 LCA 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 Study 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 sediment loads for the Study Area. The risk of encountering

lower sediment loads than what were used in the ERDC-SAND2 calculation is

minimal. In fact, it is likely that the site would encounter heavier sediment loads

than those 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 Volume VI, Appendix L.

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

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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. However, it should be noted, 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 year-round open diversion would be critical.

Real Estate: Although the White Ditch diversion would increase the frequency of

inundation in the interior marshes during the March-April 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 MR&T project. The LCA MDWD is formulated to mimic

these natural, land-building flood events by reintroducing freshwater, sediment,

and nutrients to the marshes in the Study 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 Study Area and could lead to a net gain in marsh acres.

Economically viable uses of the private property in the Study 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

would improve fish and wildlife values in the benefited area. No existing viable

uses of the marshlands are expected to be detrimentally affected by the periodic

change in water elevation. Therefore, flowage easements are not necessary within

the Study Area.

The benefited area of the LCA MDWD 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 (e.g., oil/gas surface exploration,

excavation and fill activities) are currently regulated by the LDNR, 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 and 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 USACE, the USEPA, or the LDNR.”

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

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regulated by the USFWS, the NMFS, the USEPA, and the LDEQ. More detailed

information regarding real estate is in Volume VI, Appendix J, Real Estate Plan.

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 location. When

comparing the ERDC-Sand2 Model inputs to data that have been collected within

the Study 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 Study Area than

represented by the Belle Chasse Data. Using the Belle Chasse Data, it is expected

that the recommended plan would deliver approximately 16,600 ton of sediment per

day into the Study Area during the March-April Pulse. Using the USGS sediment

loads and the same pulse operation, approximately 17,900 tons of sediment per day

could enter the Study 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 would 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 would enhance the amount of sediment available in the

area of the diversion as the back-current would 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 would be evaluated

further during the PED phase.

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 LCA

MDWD. 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 would need to occur not only with White Ditch but in a systemic

fashion. Joint operation of the proposed LCA MDWD 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 LCA MDWD, flow from Caernarvon would have to be closely

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controlled. This would mean a change to the current operational plan. It would be

crucial that future modeling during PED for LCA MDWD Project and during the FS

for the LCA Modification to Caernarvon investigate joint operation. The

Modification to Caernarvon Project would need to consider and account for the

proposed LCA MDWD Project during its analysis. Additionally the existing and

proposed operational plans for both LCA MDWD 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

Re-authorization: The chosen recommended plan for this project exceeds the cost

authorization presented in the 2004 LCA Report and the maximum project cost

authorized in section 7006(e)(3) of the WRDA 2007. The USACE 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.

Water Quality: In preparation of the Water Quality sections, the best available

data was used to develop the existing conditions analysis. Based on the analysis,

best professional judgment was used to define the predicted impacts. During PED,

more data will be collected in the project area and analyzed. If these results reveal

conditions that are significantly different than that described within this report,

then a new NEPA document may be prepared as appropriate. Appendix I details the

Water Quality monitoring that would occur pre and post project implementation.

Since the primary objective of the project is marsh creation and restoration of

natural deltaic processes, the results of water quality monitoring will not

necessarily influence the operational regime of the structure.

Fisheries: In preparation of the Fisheries sections, the best available data was

used to develop the existing conditions analysis. Based on the analysis, best

professional judgment was used to define the predicted impacts. During PED, an

aquatic model will be used to further analyze the predicted effects of the project on

fisheries resources, including commercial species such as oysters. If impacts are

significantly different that those described within this document, then a NEPA

document may be prepared as appropriate. Although fisheries resources were not

considered in the objectives of the project, these populations may be monitored

before and after project completion. Since the primary objective of the project is

marsh creation and restoration of natural deltaic processes, the results of fisheries

monitoring will not necessarily influence the operational regime of the structure.

During PED, there could be a modification of the design to accommodate fish

passage

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7.4.10 Implementation Requirements

There are various requirements for the non-Federal sponsor established by Federal

laws and policies. The non-Federal sponsor (CPRA) supports the LCA MDWD

Project. A list of all non-Federal sponsor requirements is included in the LCA

MDWD FS/SEIS (Volume VI).

7.4.10.1 Schedule

The recommended plan is also the NER plan, Alternative 4, and the plan cost

exceeds the authorization for this project. The USACE District Commander

recommends seeking additional authorization in order to construct the

recommended plan / NER plan. The need for additional authorization could affect

the schedule and delay the project construction. The schedule shown here assumes

that the additional authorization could be obtained resulting in a 1-year delay in

construction. This project was authorized for construction by the WRDA 2007,

contingent upon a signed and favorable Chief of Engineers’ Report by December 31,

2010. After the Chief’s report is signed and additional authorization is obtained,

this project would be eligible for construction funding. The project would be

considered for inclusion in the President’s budget based: on national priorities,

magnitude of the Federal commitment, economic and environmental feasibility,

amount of local public support, willingness of the non-Federal sponsor to fund its

share of the project cost, and the budget constraints that may exist at the time of

funding. Once Congress appropriates Federal construction funds, the USACE and

the non-Federal sponsor would enter into a PPA. This PPA would define the

Federal and non-Federal responsibilities for implementing, operating and

maintaining the project.

The USACE would officially request the sponsor to acquire the necessary real estate

immediately after signing the PPA. The advertisement of the construction contract

would follow the certification of the real estate. The final acceptance and transfer of

the project to the non-Federal sponsor would follow the delivery of an O&M manual

and as-built drawings. The schedule is shown in Table 7-13.

Table 7-13 : LCA MDWD Implementation 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 December 2010

Begin Preconstruction Engineering and

Design 2010

ASA and OMB Review 2011

ASA Report to Congress 2011

Execute PPA 2011

Receive Reauthorization from WRDA 2011 2011

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Milestones Schedule

Request Construction Funding per

Reauthorization 2011

Complete Design Documentation Report 2012

Complete Plans and Specifications 2012

Complete Real Estate Acquisition 2012

Advertise Construction 2013

Start Construction 2013

Complete Construction 2016

Turnover Project to Local Sponsor 2016

Initiate Monitoring and Adaptive

Management During PED

Complete Monitoring and Adaptive

Management 2026

7.4.10.2 Implementation Responsibilities

The Federal sponsor for this project is the USACE and the non-Federal sponsor is

the State of Louisiana, represented by the CPRA. 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. In addition to its financial responsibility, the Federal Government

would design and prepare plans and specifications for construction of the

recommended plan and administer and manage contracts for construction and

supervision of the project after authorization, funding, and execution of a Project

Cooperation Agreement with the CPRA.

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 O&M costs are anticipated to be minimal over the 50-year period of analysis at

an average annual cost of $1,467,836. The State of Louisiana also would be

required to provide certain local cooperation items based on Federal law and

policies. The full list of items of local cooperation can be found in the FS/SEIS

(Volume VI).

7.4.10.3 Cost Sharing

Ecosystem restoration projects require that the non-Federal share of the first cost of

the project or the separable element be 35%. Non-Federal sponsors would provide

100% of any LERRDs. The value of LERRDs would be included in the non-Federal

35% share. No Federal funds may be used to meet the non-Federal sponsor’s

obligations. Also, WIK provided by the non-Federal sponsor would be negotiated for

the both the Design Partnership Agreement and PPAs and in accordance with

current law. Where the LERRDs exceed the non-Federal sponsor’s 35% share, the

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sponsor would be reimbursed for the value of the LERRDs that exceed the 35% nonFederal share. The non-Federal sponsor is also responsible for 100% of the costs for

OMRR&R of project features. The cost share amounts for the Federal and nonFederal partner are shown in Table 7-14.

Table 7-14: Cost Sharing

Project Feature Total Cost Non-Federal Federal

% Cost % Cost

Total first cost of

construction $365,201,000 1 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&R 2 $1,468,000 100 $1,468,000 0 $0

1Total first cost of construction is based on the sum of the PED; construction management (i.e. supervisions and

administration); LERRDs; and monitoring and adaptive management and is based on October 2010 price levels.

2Average annual cost based on October 2010 price levels.

7.4.10.4 Environmental Commitments

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.

BMPs would be included in construction specifications, and they would be employed

during construction activities to minimize environmental effects. Many of these

BMPs 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 would be performed during the PED

phase. The cost and schedule for this would be incorporated into the project

management plan being developed by the USACE for the PED phase. At this time,

a scope of work 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.

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Formal consultation was conducted on the pallid sturgeon in compliance with ESA

of 1973. A Biological Opinion (Volume IV; Appendix A) was received on September

23, 2010 from the USFWS outlining the following Reasonable and Prudent

Measures and Terms and Conditions:

Formal consultation was conducted on the pallid sturgeon in compliance with ESA

of 1973. A Biological Opinion (Volume IV; Appendix A) was received on September

23, 2010 from the USFWS outlining the following Reasonable and Prudent

Measures and Terms and Conditions:

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.

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.

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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/protocols/PallidSturgeonHandlingProtocol2008B.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 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.

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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.

7.5 Public Involvement *

7.5.1 NEPA Scoping

An NOI to prepare an SEIS for the LCA MDWD was published in the Federal

Register in December 2008. A scoping meeting was conducted in February 2009 for

the project. Additional public meetings were conducted with recreational users,

local landowners, land managers, and the parish.

Common themes of the comments included the following:

Need for introducing more sediment into the Study Area

Comments indicated that the storm surge was the root cause of the problems

in this area

Suggestion to convert the project to a sediment diversion as opposed to a

freshwater diversion

Concern about EFH and the water bodies that provide nursery and foraging

habitats for fish and wildlife

Concern about the erosion effects from the water

Concern about impacts to oyster beds and other marine fisheries

The history of other projects like Caernarvon and the effects that have had

The Draft FS/SEIS was released to the public in May 2010, followed by a 45-day

public review period, which included a public meeting. Public comments were

received during the scoping meeting and Draft FS/SEIS public review. Public

comments have been incorporated into the report throughout the report

development. Comments received and the responses to them are included in

Appendix G of Volume VI.

7.5.2 Other Public Comments, Areas of Controversy, 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 have been 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:

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Coordinating joint operation of the LCA MDWD and Caernarvon Diversion

Potential negative impacts to oysters from over-freshening of the basin

Converting the estuary to fresh/intermediate marsh

Creating flotant marsh that is not anchored and provides no surge protection

Direct sediment delivery with dredging from the river

Impacts to pallid sturgeon

Creating access and/or land use problems for private landowners

Determining best location to capture sediment

RSLR

Induced shoaling effects and other effects to the navigation/shipping industry

Need to seek additional authorization of project

Fishery modeling and habitat change model are currently under development

The impacts of the Deepwater Horizon oil spill

7.6 Coordination and Compliance *

7.6.1 USACE Principles and Guidelines

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.

Planning for this feasibility study has been conducted in accordance with the ER

1105-2-100 guidance. This report is an integrated FS/SEIS. Policy reviews have

been conducted to ensure compliance with applicable USACE policies.

7.6.2 Environmental Coordination and Compliance

Coordination and compliance efforts were conducted regarding statutory

authorities. These include environmental laws, regulations, Executive Orders,

policies, rules, and guidance applicable to this project. Full compliance with

statutory authorities would be accomplished upon review of the integrated FS/SEIS

by appropriate agencies and the public and the signing of a ROD.

The USACE has coordinated with the USFWS, NMFS, and the LDWF per the Fish

and Wildlife Coordination Act (48 Stat. 401, as amended; 16 U.S.C. 661 et seq.). A

CAR has been received and the comments incorporated into the project plan as

appropriate. Accordingly, the USFWS supports implementation of the

recommended plan, provided that additional assessment work is continued during

the remaining planning phase and completed during the PED phase, to address

outstanding major issues that could result in substantial improvements and/or

modifications to the selected plan. The USACE concurred with the

recommendations; discussion of the recommendation is provided in Volume VI.

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Formal consultation on the pallid sturgeon was conducted and a Biological Opinion

was received on September 23, 2010 from the USFWS. The USFWS determined

that the level of expected take is not likely to result in jeopardy to the pallid

sturgeon. The Reasonable and Prudent Measures and Terms and Conditions as

outlined by the Biological Opinion will be followed (Volume VI -Appendix A).

State certification for coastal zone consistency has also been received.

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8.0 CONCLUSIONS AND RECOMMENDATIONS

The USACE District Commander has considered all significant aspects of the

studies included in this report, including the environmental, social, and economic

effects; the engineering feasibility; and the comments received from other resource

agencies, the non-Federal sponsor, and the public, and has determined that the

recommended plans presented in this report are in the overall public interest and a

justified expenditure of Federal funds.

The recommended plans have been determined to best meet the goals and objectives

of the 2004 LCA Report (USACE, 2004a) and to address critical near-term

restoration needs through the reintroduction of riverine influence, removing

hydrologic impediments , and restoring the geomorphic form and function to barrier

islands. Since the 2005 signing of the LCA Chief of Engineers’ Report significant

changes have occurred. The significant impacts of the 2005 hurricane season

further deteriorated the Louisiana coastal landscape and emphasized the critical

need for restoration of ecosystem form and function. The extensive response to the

impact of those storms has also resulted in a massive demand of materials and

resources, producing dramatic escalation in the costs for implementing projects of

all types.

The authorization of the LCA Plan in the WRDA 2007 recognized the impact of the

2005 storm season. The WRDA authorization directed that appropriate

consideration be given to those impacts in making a final determination on the

project recommendations presented in the 2004 LCA Report. The planning teams

for each of the projects presented in this report have fully considered the critical

needs of the coastal system, the changing coastal conditions, and the changes in

implementation cost. Evaluations and comparisons have been made in

consideration of the objectives and needs identified in 2004 and any additional

objective and needs that exist currently.

The 2004 LCA Report identified the critical near-term projects as necessary to

maintain the long-term potential for comprehensive restoration of the coastal

Louisiana ecosystem. In doing so, the plan presented a suite of projects that were

components of comprehensive plans evaluated to be effective and efficient. The

LCA Report projects were those that could address the critical near-term needs to

stabilize and/or restore ecosystem form and function. The project recommendations

presented in this report address those original objectives as well as the expanded

needs identified through the current analysis. Although the estimated costs and

extent of the projects have increased to a greater degree than generally expected,

the recommended projects remain consistent with the originally presented and

authorized purposes and objectives. The recommendations represent the most

environmentally appropriate, effective, and efficient actions for ensuring the

maintenance of a fully functioning Louisiana coastal ecosystem.

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The following recommendations are being made regarding the projects authorized

in Section 7006 (e)(3)(A) of WRDA 2007 and include additional authorization to

more effectively achieve Federal NER objectives within these Study Areas. Error!

Reference source not found. summarizes the benefits, costs, and authorizations

for the selected Recommended Plan and NER projects included in this study.

Table 8.1 LCA Section 7006(e)(3) Projects

Recommended Plan Cost and Benefit Summary

(October 2010 Price Level)

* Implementation of the recommended plan to fully address the restoration needs of the study area identified

in this report requires additional authorization by Congress by raising the total project cost.

** Alternative 11 describes Whiskey Island which is an increment of the recommended plan Alternative 5.

8.1 Amite River Diversion Canal Modification

The LCA ARDC NER Plan, Alternative 39, would address all of the subunits

currently in critical need of restoration (such as NE-2 and SE-2 which have already

begun converting to marsh, and SE-1, which is expected to need restoration in the

next 20 years). The NER would improve habitat function by 1,602 AAHUs, which

includes improvement to 3,881 acres of swamp habitat and creating 9.9 acres of

upland habitat.

Project Alternative Total First Cost Average Annual

Habitat Units

Amite River

Diversion Canal

Modification

Alt. 33 $8,136,000 679

Convey Atchafalaya

River Water to

Northern Terrebonne

Marshes

Alt. 2 $283,534,000 3,220

Houma Navigation

Control Lock Alt. 2 $1,496,000 243

Small Diversion at

Convent/Blind River Alt. 2 $116,791,000 6,421

Terrebonne Basin

Barrier Shoreline

Restoration

Alt. 5* $646,931,000 2,063

(Alt. 11)** ($113,434,000) (379)

Medium Diversion at

White Ditch Alt. 4* $365,201,000 13,355

Total $1,422,089,000 25,981

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For the LCA ARDC Modification Project, Alternative 33 is recommended for

construction as the recommended plan. Alternative 33 includes the creation of

three gaps and conveyance channels through the dredged material berm of the

ARDC. These gaps would improve connectivity, which would greatly increase the

movement of freshwater, sediments, and nutrients to and from the bald cypresstupelo swamp. Alternative 33 would improve habitat function by 679 AAHUs. The

benefits include improvements to approximately 1,602 acres of existing freshwater

swamp and creating an additional 5.0 acres of upland habitat from dredged

material placement.

The fully funded cost of the LCA ARDC NER plan, Alternative 39, exceeds the

authorized cost for this project. The recommended plan is an implementable

increment of the NER plan, meets the LCA and project objectives, has been

determined to be cost effective, is within the cost and scope of the WRDA

authorization, has stand-alone utility, and is justified based on ecosystem

restoration benefits. The State of Louisiana, acting as the non-Federal sponsor,

supports Alternative 33 as the recommended plan; however, they believe the project

warrants additional congressional authorization to increase funding and allow the

implementation of the NER plan (Alternative 39) to fully address the Maurepas

Swamp’s ecosystem needs identified in this report.

The project total first cost, based on October 2010 price levels, is estimated at

$8,136,000, and this project would be cost shared by the non-Federal sponsor, the

State of Louisiana, at 35% non-Federal and 65% Federal. Additionally, the nonFederal sponsor would be 100% responsible for the OMRR&R for the 50-year period

of analysis of the project.

8.2 Convey Atchafalaya River Water to Northern Terrebonne

Marshes and Multipurpose Operation of the Houma

Navigation Lock

For the LCA ARTM and LCA MOHNL Project, referred to collectively as the LCA

ARTM Project, Alternative 2 is recommended for construction as the recommended

plan. Alternative 2 utilizes flow management measures to maximize benefits of

existing freshwater flows. Flow management measures would focus on eliminating

GIWW constrictions and constructing flow management features in the interior

portions of the Study Area. Alternative 2 also includes the multipurpose operation

of the proposed HNC Lock Complex, once constructed, in an effort to direct water

into surrounding wetlands rather than shunting flow down the HNC into the Gulf

of Mexico. Additional freshwater would not be introduced from other sources.

Instead, this alternative would attempt to redistribute the existing inputs to more

efficiently utilize freshwater.

Alternative 2 would improve habitat function by approximately 3,220 AAHUs. The

LCA ARTM project provides approximately 2,977 AAHUs and the HNC operation

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provides 243 AAHUs of that total. Those benefits include the reduction of wetland

loss by approximately 9,655 acres of existing wetlands over the 50-year period of

analysis. Alternative 2 is also the NER plan, is within the WRDA authorized cost

for this project, and is justified based on ecosystem restoration benefits. The State

of Louisiana, acting as the non-Federal sponsor, supports the implementation of the

recommended plan / NER plan.

The project total first cost, based on October 2010 price levels, is estimated at

$285,030,000. The estimated LCA ARTM project first cost is $283,534,000, and the

estimated LCA MOHNL project cost is $1,496,000. This project would be cost

shared by the non-Federal sponsor, the State of Louisiana, at 35% non-Federal and

65% Federal. Additionally, the non-Federal sponsor would be 100% responsible for

the OMRR&R for the 50-year period of analysis of the project.

8.3 Small Diversion at Convent/Blind River

For the LCA Small Diversion at Convent/Blind River, Alternative 2 is recommended

for construction as the recommended plan. Alternative 2 includes a 3,000 cfs

capacity gated box culvert diversion and delivery channel to be constructed in the

vicinity of Romeville, Louisiana. The diversion would deliver freshwater, sediment,

and nutrients to the swamp at strategic times during the year and improve habitat

function by 6,421 AAHUs over a total of 21,369 acres of bald cypress-tupelo swamp

that are in various stages of deterioration.

The recommended plan is also the project NER and has been determined to

reasonably maximize ecosystem restoration benefits compared to costs, consistent

with the ecosystem restoration objectives. The State of Louisiana, acting as the

non-Federal sponsor, supports the implementation of the recommended plan / NER

plan.

The project total first cost, based on October 2010 price levels, is estimated at

$116,791,000, and this project would be cost shared by the non-Federal sponsor, the

State of Louisiana, at 35% non-Federal and 65% Federal. Additionally, the nonFederal sponsor would be 100% responsible for the OMRR&R for the 50-year period

of analysis of the project.

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8.4 Terrebonne Basin Barrier Shoreline Restoration

For the LCA TBBSR Project, Alternative 5 was identified as the NER plan.

Alternative 5 includes four islands: Raccoon Island with terminal groin Plan E;

Whiskey Island Plan C; Trinity Island Plan C; and Timbalier Island Plan E.

Immediately after construction, the NER plan would add 3,283 acres of habitat

(dune, intertidal, and supratidal) to the existing island footprints of Raccoon,

Whiskey, Trinity, and Timbalier Islands, increasing the total size of the islands to

5,840 acres and improving habitat function by 2,063 AAHUs The project would

ensure the geomorphic and hydrologic form and ecological function of the majority

of the estuary over a 50-year period. Beach renourishment events would be needed

at staggered intervals for the different islands over the 50-year period of analysis to

maintain the benefits. The cost of these events would be considered OMRR&R and

would be the responsibility of the non-Federal sponsor.

The fully funded cost of the NER plan exceeds the authorization for this project.

While additional authority is needed to raise the total project cost to allow

implementation of the entire NER plan, the reporting officers recommend that the

Whiskey Island component (Alternative 11) of the NER plan be implemented under

the existing authority provided in Section 7006(e)(3) of WRDA 2007. The Whiskey

Island component includes renourishment every 20 years to maintain the

constructed features. The Whiskey Island component is an implementable

increment of the NER plan, meets the LCA Program objectives, and is within the

cost and scope of the current WRDA authorization. The State of Louisiana, acting

as the non-Federal sponsor, supports immediate implementation of the Whiskey

Island component.

Whiskey Island Plan C, would generate habitat function of 379 AAHUs by adding

469 acres of habitat (dune, intertidal, and supratidal) to the existing island

footprint, increasing the size of the island to 1,272 acres. The project would

support the geomorphic and hydrologic form and ecological function of the adjacent

estuary over a 50-year period as well as improve critical barrier island habitats for

fish, migratory birds, and other terrestrial and aquatic species. To sustain the

project benefits, two renourishment events would be required; the cost of these

events would be considered OMRR&R and would be the responsibility of the nonFederal sponsor. The State of Louisiana, acting as the non-Federal sponsor,

supports Whiskey Island Plan C as the first component of construction of the NER

plan; however, they believe the project warrants additional congressional

authorization to increase funding and allow the implementation of the NER plan

(Alternative 5) to fully address the barrier island needs identified in this report.

The total first cost, based on October 2010 price levels, of the first component on

construction of the recommended plan is estimated at $113,434,000 and the

estimated total first cost of the entire recommended plan is $646,931,000. The

project would be cost shared by the non-Federal sponsor, the State of Louisiana, at

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35% non-Federal and 65% Federal. Additionally, the non-Federal sponsor would be

100% responsible for the OMRR&R for the 50-year period of analysis of the project.

8.5 Medium Diversion at White Ditch

For the LCA MDWD Project, Alternative 4 is recommended as the Recommended

Plan. Alternative 4 includes a 35,000 cfs capacity gated box culvert diversion and

delivery channel to be constructed in the vicinity of Phoenix, Louisiana. The project

would deliver freshwater, sediment, and nutrients and improve habitat function by

13,355 AAHUs and achieve no-net-loss of marsh acreages during the period of

analysis (2015-2065). 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. Restoration of freshwater,

nutrient, and sediment inputs to the Study Area would result in the creation and

nourishment of a variety of marsh types within the study area.

The recommended plan is also the NER plan, Alternative 4, and the plan cost

exceeds the authorization for this project. The recommended plan / NER plan has

been determined to reasonably maximize ecosystem restoration benefits compared

to costs, consistent with the Federal objective. Due to the nature of the diversion

and the analyses completed, an implementable increment of the NER plan could not

be identified. The USACE District Commander recommends seeking additional

authorization in order to construct the recommended plan / NER plan. The State of

Louisiana, acting as the non-Federal sponsor, supports the implementation of the

Recommended Plan / NER plan.

The project total first cost, based on October 2010 price levels, is estimated at

$365,201,000, and this project would be cost shared by the non-Federal sponsor, the

State of Louisiana, at 35% non-Federal and 65% Federal. Additionally, the nonFederal sponsor would be 100% responsible for the OMRR&R for the 50-year period

of analysis of the project.

8.6 Financial Requirements

It is expected that the CPRA will have the capacity to provide the required local

cooperation for the projects. The project schedules and cost estimates 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 each project, including the value of LERRD and pre-construction engineering

and design costs construction features.

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

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Management Services determines in writing that funds it provides to the nonFederal 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 Small Diversion at Blind River 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.

8.7 Views of Non-Federal Sponsor

CPRA, the non-Federal sponsor, has expressed the desire for implementing the LCA

projects presented in this summary and sponsoring the project construction in

accordance with the items of local cooperation that are set forth in the

recommendations chapter of each report (Volumes II through VI).

The State of Louisiana fully supports the LCA 7006(e)(3) projects. The state

recognizes that the USACE's 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 USACE 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.

8.8 Area of Controversy and Unresolved Issues

Current Events: The impacts of the Deepwater Horizon oil spill on coastal

Louisiana are uncertain at this time. 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. Potential impacts could include factors such as

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WRDA 2007 Section 7006(e)(3) 8-8 October 2010

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.).

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Attachment A

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Suter, J. R., Penland, S., and Ramsey, K. E. 1991. “Nearshore Sand Resources of

the Mississippi River Delta Plain: Marsh Island to Sandy Point.” Coastal

Geology Technical Report No. 8. Louisiana Geological Survey.

Taylor, J.R. 1985. Community structure and primary productivity of forested

wetlands in Western Kentucky. Ph.D. thesis, University of Louisville,

Louisville, KY.

T. Baker Smith and Moffatt & Nichol (TBS and M&N). 2007. Whiskey Island Back

Barrier Marsh Creation (TE-50) 95% Design Report, Appendix B, OSI’s

Hydrographic, Geophysical, and Geotechnical Survey Program.

Theoharides, K.A., Dukes, J.S. 2007. Plant invasion across space and time: factors

affecting nonindigenous species success during four stages of invasion. New

Phytologist 176: 256-273.

Thomson, D.M., G.P. Shaffer, and J.A. McCorquodale. 2002. A potential

interaction between sea level rise and global warming: implications for

coastal stability on the Mississippi River deltaic plain. Global Plan 32: 49-

59.

Tidwell, M. 2007. Bayou Farewell: The Rich Life and Tragic Death of Louisiana’s

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Cajun Coast.

Turner, R.E. 1990. Landscape development and coastal wetland losses in the

Northern Gulf of Mexico. American Zoologist 30(1): 89-105.

Turner, R.E. and V.S. Rao. 1990. Relationships between wetland fragmentation

and recent hydrologic changes in a deltaic coast. Estuaries 13:272-281.

URS Corporation and Evans-Graves Engineers. 2007. Mississippi River

reintroduction into Maurepas Swamp. Project PO-29. Vol. I-VII. Final Report

for Louisiana Department of Natural Resources and U.S. EPA.

U.S. Army Corps of Engineers (USACE). 2000a. “Planning Guidance Notebook.”

ER 1105-2-100. Washington D.C. April, 2000.

------. 2000b. Mississippi River Sediment, Nutrient, and Freshwater Redistribution

Study, Draft Report and Environmental Resources Document.

------. 2002. Mississippi River & Tributaries - Morganza, Louisiana to the Gulf of

Mexico Hurricane Protection Feasibility Study and Programmatic

Environmental Impact Statement. New Orleans, LA.

------. 2004a. “Louisiana Coastal Area (LCA) Ecosystem Restoration Study.”

Volume 1: LCA Study - Main Report. November, 2004.

------. 2004b. “Louisiana Coastal Area (LCA) Ecosystem Restoration Study.”

Volume 2: Programmatic Environmental Impact Assessment. November,

2004.

------. 2004c. “Louisiana Coastal Area (LCA) Ecosystem Restoration Study.”

Volume 4: LCA Study - Main Report Appendices. November, 2004.

------. 2007. Waterbourne Commerce of the United States, Calendar Year 2005.

Part 5- National Summaries. Alexandria, VA: Institute for Water Resources,

U.S. Army Corps of Engineers. Internet URL:

http://iwr.usace.army.mil/ndc/wcsc/pdf/wcusnatl105.pdf.

------. 2008a. “Civil Works Cost Engineering.” ER 1110-2-1302. Washington, D.C.

------. 2008b. Unpublished. “Project Management Plan. Terrebonne Basin Barrier

Shoreline restoration Feasibility Study. Conditionally Authorized Project -

Louisiana Coastal Area Ecosystem Restoration Project”. Draft Report. New

Orleans, Louisiana.

------. 2008c. USACE Louisiana Coastal Protection and Restoration (LACPR): Draft

Technical Report. New Orleans, LA

------. 2009a. Comprehensive Plan and Integrated Programmatic Environmental

Impact Statement, Mississippi Coastal Improvements Program (MsCIP)

Hancock, Harrison, and Jackson Counties, Mississippi. Mobile, AL.

------. 2009b. “Water Resources Policies and Authorities Incorporating Sea-Level

Change Considerations in Civil Works Programs.” EC 1165-2-211.

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Appendices Volume I - Summary

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Washington, D.C.

------. 2009c. Louisiana Coastal Protection and Restoration (LACPR): Final

Technical Report. New Orleans, LA

U.S. Census Bureau. 2007. Annual Estimates of the Population for Counties: April

1, 2000 to July 1, 2006. (Coastal parish total was calculated based on the sum

of the populations of 20 coastal parishes). Internet URL:

http://www.census.gov.

U.S. Department of Agriculture (USDA). 2005. “Final Project Plan and

Environmental Assessment, Raccoon Island Shoreline Protection/Marsh

Creation Project TE-48”, Terrebonne Parish, Louisiana. Alexandria,

Louisiana.

U.S. Department of Agriculture, Soil Conservation Service (USDA SCS). 1992.

Project No. BS-4. Feasibility Report, White’s Ditch Diversion Siphon Outfall

Management Plan, completed for Louisiana Department of Natural

Resources - Coastal Restoration Division.

U.S. Department of Commerce (USDC). 1998. Environmental Assessment of East

Timbalier Island Restoration Projects. CWPPRA Projects XTE-67 and XTE45/67B. Lafourche Parish, Louisiana. Prepared by Gotech Inc., Baton Rouge,

Louisiana.

U.S. Department of the Interior, Minerals Management Service (MMS). 2004.

Environmental Assessment - Issuance of Non-Competitive Leases for the Use

of Outer Continental Shelf Sand Resources from Ship Shoal, Offshore

Central Louisiana for Coastal and barrier Island Nourishment and hurricane

levee Construction. April 2004.

U.S. Environmental Protection Agency (USEPA). 1997. “Environmental

Assessment for Isles Dernieres Barrier Island Restoration and Coastal

Wetland Creation (TE-20/TE-24): Finding Of No Significant Impacts”.

Terrebonne Parish, Louisiana.

------. 2002. “Environmental Assessment for Timbalier Island Dune and Marsh

Creation Project (TE-40/XTE-45a), Finding of No Significant Impact”.

Terrebonne Parish, Louisiana.

------. 2003a. High Resolution Geophysical and Archaeological Survey of Portions of

Blocks 87, 88, 89, 94, and 95 Ship Shoal Area. Whiskey Island West Flank

Restoration Project Using Ship Shoal Sediment Coastal Terrebonne Parish,

Louisiana. Prepared by C&C Technologies, December 2003.

------. 2003b. High Resolution Geophysical and Archaeological Survey of the South

Pelto Area Block 13 Vicinity of Ship Shoal. New Cut Dune/Marsh Restoration

Project Using Ship Shoal Sediment Coastal Terrebonne Parish, Louisiana.

Prepared by C&C Technologies, December 2003.

U.S. Fish and Wildlife Service (USFWS). 2002. Wetland Value Assessment

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Methodology: Barrier Island Community Model.

------. 2009a. In cooperation with Louisiana Sea Grant Program: Louisiana

Manatee Sightings from 1929 through 1996.

U.S. Geological Survey (USGS). 2003. 100+ years of land change for southeast

coastal Louisiana. National Wetlands Research Center. USGS National

Land Cover Database, Map ID: USGS-NWRC 2003-02-0373.

------. 2008. National Water Information System: Web Interface.

http://waterdata.usgs.gov/la/nwis/current/?type=flow. Retrieved historical

data for Mississippi River

URS Corporation and Evans-Graves Engineers. 2007. Mississippi River

reintroduction into Maurepas Swamp. Project PO-29. Vol. I-VII. Final

Report for Louisiana Department of Natural Resources and U.S. EPA.

White, W.A. and R.A. Morton. 1997. Wetland losses related to fault movement and

hydrocarbon production, southeastern Texas coast. Journal of Coastal

Research. 13:1305-1320.

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.

Williams, J. S., Penland, S., Sallenger, A. H. 1992. “Louisiana Barrier Island

Erosion Study, Atlas of Shoreline Changes in Louisiana from 1853 to 1989.”

U.S. Geological Survey and Louisiana Geological Survey.

Young, P.J., B.D. Keeland, and R.R. Sharitz. 1995. Growth response of baldcypress

[Taxodium distichum (L.) Rich] to an altered hydrologic regime. American

Midland Naturalist 133: 206-212.

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Appendix B

Glossary

Acceptability Adequate to satisfy a need, requirement, or standard. One of the

USACE 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.

Alternative Plan A set of one or more management measures within a

subprovince functioning together to address one or more

objectives.

Amplitude The maximum absolute value of a periodically varying quantity.

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 without- and future with-project

scenarios are annualized, averaged over the project life, to

determine Average Annual Habitat Units (AAHUs).

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

(BLH)

Low-lying forested wetlands found along streams and rivers.

Brackish Marsh Intertidal plant community typically found in the area of the

estuary where salinity ranges between 4 to 15 parts per

thousand.

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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 which pertain to

regulating impacts to 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.

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 feasibilitylevel report to be recommended for authorization of potential

future project construction by Congress.

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.

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.

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Deltaic Cycle The repeating pattern of delta development, progression, and

abandonment. As sediments are deposited at the mouth of the

distributary channels, the delta progresses seaward. The main

channel then switches to a new course with a shorter reach to

the depositional basin. Abandoned delta lobes decrease in

elevation due to continued subsidence and sediment compaction,

resulting in retreat of the shoreline. Abandoned lobes may be

partially or wholly covered by new lobes during later deltaic

cycles.

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.

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.

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 Impacts.”

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.

Diurnal Relating to or occurring in a 24-hour period; daily.

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.

Dune A habitat occurring at elevations greater than 5.0 feet North

American Vertical Datum (NAVD88), which includes foredune,

dune, and rear dune. While dunes may occur at lower

elevations, lower-elevation dunes are likely to overwash more

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frequently and have plant communities which differ from

“typical” dune species (USFWS, 2002).

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 an 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 requirements for a project.

Egress A path or opening for going out; an exit.

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.

Enhance To augment or increase/heighten the existing state of an area.

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.

Estuarine Related to an estuary.

Estuary A semi-enclosed body of water with freshwater input and a

connection to the sea where freshwater and salt water mix.

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

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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 cost-effectiveness

analysis.

Feature A constructible increment of an alternative plan.

Final Array The final grouping of the most effective coast wide plans from

which a final recommendation can be made.

Freshwater Marsh Intertidal herbaceous plant community typically found in that

area of the estuary with salinity ranging from 0 to 3 parts per

thousand.

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.

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 (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 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

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difference in AAHUs between the two scenarios represents the

net benefit attributable to the project in terms of habitat

quantity and quality.

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.

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.

Intermediate Marsh Intertidal herbaceous plant community typically found in that

area of the estuary with salinity ranging from 2 to 5 parts per

thousand.

Intertidal Alternately flooded and exposed by tides. This habitat is defined

as existing between 0.0 feet and 1.9 feet NAVD 88 and can

encompass intertidal marsh, mudflats, beach, and other

habitats occurring in that elevation range (USFWS, 2002).

Invertebrates Animals without backbones, including shrimp, crabs, oysters,

and worms.

Larvae The stage in some animal’s 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

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flood.

Loamy Soil composed of a mixture of sand, clay, silt, and organic

matter.

Locally Preferred

Plan (LPP)

Alternative plan preferred by local sponsor if other than the

Recommended Plan.

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.

National Ecosystem

Restoration (NER)

USACE standard for cost-effectiveness based on ecosystem, not

economic, benefits.

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.

Organic Composed of or derived from living things.

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.

Planning Scale Planning term that reflects the degree to which environmental

processes would be restored or reestablished, and the resulting

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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 projected rate of loss of function is “Reduce.” The

lowest possible scale was no further action above and beyond

existing projects and programs.

Post-larval Stage in an animal’s lifecycle after metamorphosis from the

larval stage, but not yet full grown.

Potable Water Water that is fit to drink.

ppt Parts per thousand. The salinity of ocean water is

approximately 35 parts per thousand.

Primary

Consolidation/Secon

dary 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 NEPA document.

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)

An 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.

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.

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

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Appendices Volume I - Summary

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problem/need. If so, then a “Feasibility Report” is prepared,

which details the solution and its impacts further.

Relative Sea Level

Change

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 an 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.

Saline Marsh Intertidal herbaceous plant community typically found in that

area of the estuary with salinity ranging from 12 to 32 parts per

thousand.

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

Environmental Impact Statement.

Sea level Long-term average position of the sea surface.

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.

Social Relating to human society and its modes of organization.

Socioeconomic Involving both social and economic factors.

Stabilize To fix the level or fluctuation of; to make stable.

State Historic

Preservation Office

(SHPO)

The part of the Louisiana Department of Culture, Recreation,

and Tourism that oversees consultation and compliance with

Section 106 of the National Historic Preservation Act for

Federally funded, permitted, or approved projects.

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.

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Appendices Volume I - Summary

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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 Earth’s surface

with little or no horizontal motion.

Supratidal Habitat occurring between 2.0 feet and 4.9 feet NAVD 88 and

typically encompasses swale. Habitat may also include low

elevation dune and beach (USFWS, 2002).

Sustain To support and provide with nourishment to keep in existence;

maintain.

Terrestrial Habitat The land area or environment where an organism lives; as

distinct from water or air habitats.

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.

Upland A general term for non-wetland elevated land above low areas

along streams or between hills.

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.

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Appendices Volume I - Summary

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Appendix C

Acronyms

AAHU Average Annual Habitat Unit

Alt. Alternative

APE Area of Potential Effect

AR&T Amite River and Tributaries

ARDC Amite River Diversion Canal

ARTM Convey Atchafalaya to Northern Terrebonne Marshes

ASA Assistant Secretary of the Army

BMP Best Management Practices

BO Bank Openings

BTNEP Barataria-Terrebonne National Estuary Program

BUDMAT Beneficial Use of Dredge Material

CAR Coordination Act Letter Report

CC Conveyance Channel

CD Channel Dredging

CE/ICA Cost Effectiveness and Incremental Cost Analysis

CFDM Caernarvon Freshwater Diversion Modification

CFR Code of Federal Regulations

cfs Cubic Feet per Second

CIAP Coastal Impact Assistance Program

cm Centimeters

CN RR Canadian National Railroad

Coast 2050

Plan

Coast 2050 Plan: Toward a Sustainable Coastal Louisiana

(1999)

CPRA Coastal Protection and Restoration Authority (State of

Louisiana)

CRMS Coast-wide Reference Monitoring System

CSRA Cost and Scheduling Risk Agreement

CWCCIS Civil Works Construction Cost Index System

CWD Conceptual White Ditch

CWPPRA Coastal Wetland Planning, Protection Restoration Act

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CY Cubic Yard

CZM Coastal Zone Management Act of 1972

DDR Design Documentation Report

DOQ Digital Orthophoto Quadrangles

EC Engineering Circular

ECO-PCX National Ecosystem Planning Center of Expertise

EFH Essential Fish Habitat

EOP Environmental Operating Principle

EPP Environmentally Preferable Plan

ER Engineering Regulation

°F Degrees Fahrenheit

ft Feet

FPEIS Final Programmatic Environmental Impact Statement

FS Feasibility Study

FWP Future With Project

FY Fiscal Year

g Grams

GIWW Gulf Intracoastal Waterway

GMFMC Gulf of Mexico Fishery Management Council

H Hydraulic Distribution

ha Hectare

H&H Hydraulics and hydrology

HC Habitat Creation via Placement of Dredge Material

HNC Houma Navigation Canal

HSDRRS Hurricane and Storm Damage Risk Reduction System

HTRW Hazardous, toxic, and radioactive waste

HU Habitat Unit

I-10 Interstate 10

IPCC Intergovernmental Panel on Climate Change

IWR Institute for Water Resources Planning

KCSRR Kansas City Southern Railroad

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Appendices Volume I - Summary

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km Kilometer

L Liter

LA Louisiana

LACPR Louisiana Coastal Protection and Restoration

LCA Louisiana Coastal Area

LCA Report Louisiana Coastal Area (Ecosystem Restoration Study, 2004)

LDEQ Louisiana Department of Environmental Quality

LDNR Louisiana Department of Natural Resources

LDWF Louisiana Department of Wildlife and Fisheries

LERRD Land, Easements, Rights-Of-Way, Relocation, and Disposal

Areas

LNHP Louisiana Natural Heritage Program

LPP Locally Preferred Plan

m Meters

MCACES Micro-Computer Aided Cost Engineering System

MCY Million Cubic Yards

MDWD Medium Diversion at White Ditch

mg Milligram

MHW Mean High Water

mi Mile

MII Micro-Computer Aided Cost Engineering System, Version 2

mm Millimeter

MMS Minerals Management Service

MOHNL Multipurpose Operation of the Houma Navigation Lock

MR&T Mississippi River and Tributaries

MSL Mean Sea Level

MVD USACE Mississippi Valley Division

MVN USACE New Orleans District

NAVD North American Vertical Datum

NEPA National Environmental Policy Act

NER National Ecosystem Restoration

NGO Non-governmental organization

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NGVD National Geodetic Vertical Datum

NMFS National Marine Fisheries Service

NOAA National Oceanic and Atmospheric Administration

NOI Notice of Intent

NRC National Resource Council

NRCS Natural Resources Conservation Service

NWRC National Wetland Research Center

O&M Operation and Maintenance

OCS Outer Continental Shelf

OMB Office of Management and Budget

OMRR&R Operating, Maintaining, Repairing, Replacing, and

Rehabilitating

P Protection and Sustainability

PAC Post Authorization Change

P&G Principles and Guidelines

PDT Project Delivery Team

PED Planning, Engineering, and Design

PEIS Programmatic Environmental Impact Statement

PPA Project Partnership Agreement

ppt Parts per Thousand

ROD Record of Decision

RPEIS Revised Programmatic Environmental Impact Statement

RSLR Relative Sea Level Rise

S Sediment Supp Distribution

s Second

SAV Submerged Aquatic Vegetation

SCORP Statewide Comprehensive Outdoor Recreation Plan

SD Standard Deviation

SEIS Supplemental Environmental Impact Statement

SHPO State Historic Preservation Office

SLR Sea Level Rise

SONRIS Strategic Online Natural Resources Information System

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TBBSR Terrebonne Basin Barrier Shoreline Restoration

TM Thematic Mapper

TMDL Total Maximum Daily Load

TSP Tentatively Selected Plan

TSS Total Suspended Solids

UDV Unit Day Value

U.S. United States

U.S.C. United States Code

USACE United States Army Corps of Engineers

USEPA United States Environmental Protection Agency

USFWS United States Fish and Wildlife Service

USGS United States Geological Survey

VE Value Engineering

VP Non-structural Vegetative Planting

WCRA Wetland Conservation and Restoration Authority

WCRF Wetland Conservation and Restoration Fund

WD White Ditch

WIK Work-In-Kind

WMA Wildlife Management Area

WRDA Water Resources Development Act

WVA Wetland Value Assessment

yr Year

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