MISSISSIPPI RIVER GULF OUTLET (MRGO) 

ECOSYSTEM RESTORATION PLAN 

FINAL FEASIBILITY REPORT 

SUPPLEMENTAL REPORT OF THE CHIEF OF ENGINEERS 

IN RESPONSE TO THE WATER RESOURCES DEVELOPMENT ACT OF 2007

U.S. Army Corps of Engineers 

New Orleans District 

7400 Leake Avenue 

New Orleans, Louisiana 70118

June 2012

Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report Contents 

i June 2012 

Contents 

Page 

S REPORT SUMMARY: MISSISSIPPI RIVER GULF OUTLET (MRGO) ECOSYSTEM 

RESTORATION PLAN ................................................................................................................................ S-1

S.1 STUDY INTRODUCTION AND INFORMATION ........................................................................... S-1

S.2 STUDY AND PROJECT AUTHORITY ............................................................................................ S-3

S.3 STUDY AND PROJECT AUTHORITY ............................................................................................ S-3

S.4 STUDY PURPOSE AND SCOPE .................................................................................................... S-5

S.4.1 Project Location / Congressional District ........................................................................ S-6

S.4.2 Prior Studies, Reports and Existing Water Projects ...................................................... S-6

S.4.3 Federal Interest ................................................................................................................ S-6

S.4.4 Key Planning Assumptions ............................................................................................. S-9

S.5 STUDY OBJECTIVES ................................................................................................................... S-11

S.5.1 Problems and Opportunities ......................................................................................... S-11

S.5.2 Planning Objectives ....................................................................................................... S-12

S.5.3 Planning Constraints ..................................................................................................... S-15

S.6 PLAN FORMULATION RATIONALE ............................................................................................ S-15

S.7 MANAGEMENT MEASURES AND ALTERNATIVE PLANS....................................................... S-15

S.8 MINIMUM PLANNING INCREMENT ............................................................................................. S-16

S.8.1 Cypress and Coastal Ridge Habitat ............................................................................. S-16

S.8.2 Recommendations for MRGO Channel ....................................................................... S-17

S.8.3 Violet, Louisiana Freshwater Diversion ........................................................................ S-17

S.9 FINAL ARRAY OF ALTERNATIVES ............................................................................................ S-18

S.10 COMPARISON OF ALTERNATIVES ........................................................................................... S-20

S.11 SYSTEMS / WATERSHED CONTEXT ......................................................................................... S-22

S.12 FEDERALLY IDENTIFIED PLAN .................................................................................................. S-24

S.13 EXPECTED PROJECT PERFORMANCE ................................................................................... S-26

S.13.1 Project Costs .................................................................................................................. S-26

1 INTRODUCTION AND BACKGROUND ................................................................................................... 1-1

1.1 STUDY PURPOSE AND SCOPE .................................................................................................... 1-1

1.2 STUDY AND PROJECT AUTHORITY ............................................................................................ 1-1

1.3 STUDY AREA .................................................................................................................................... 1-4

1.4 MRGO NAVIGATION CHANNEL .................................................................................................... 1-6

1.4.1 Authorization, Deauthorization, and Channel Closure ................................................... 1-6

1.5 MRGO ENVIRONMENTAL IMPACTS ............................................................................................ 1-6

1.6 PRIOR STUDIES, REPORTS, AND EXISTING WATER PROJECTS ......................................... 1-9

1.7 ENVIRONMENTAL OPERATING PRINCIPLES .......................................................................... 1-15

1.8 ENVIRONMENTAL PLANNING GUIDING PRINCIPLES ............................................................ 1-16

1.9 ROADMAP FOR RESTORING ECOSYSTEM RESILIENCY AND SUSTAINIBILITY .............. 1-17

2 PLAN FORMULATION ................................................................................................................................ 2-1

2.1 KEY PLANNING ASSUMPTIONS ................................................................................................... 2-3

2.2 EXISTING CONDITIONS ................................................................................................................. 2-4

2.2.1 Coastal System Processes .............................................................................................. 2-4

2.2.2 Geomorphic and Physiographic Setting .......................................................................... 2-6

2.2.3 Hydrology .......................................................................................................................... 2-8

2.2.4 Coastal Vegetation Resources ...................................................................................... 2-14
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2.2.4.1 Land Cover ............................................................................................... 2-14

2.2.4.2 Habitat Types ........................................................................................... 2-15

2.2.4.3 Invasive Species ...................................................................................... 2-16

2.2.4.4 Rare, Unique and Imperiled Vegetative Communities .......................... 2-16

2.2.5 Wildlife Resources .......................................................................................................... 2-20

2.2.6 Aquatic and Fishery Resources ..................................................................................... 2-20

2.2.7 Essential Fish Habitat ..................................................................................................... 2-22

2.2.8 Threatened and Endangered Species .......................................................................... 2-22

2.2.9 Recreational Resources ................................................................................................. 2-23

2.2.10 Historic and Cultural Resources .................................................................................... 2-24

2.2.11 Aesthetics ........................................................................................................................ 2-25

2.2.12 Hazardous, Toxic, and Radioactive Materials .............................................................. 2-26

2.2.13 Socioeconomic and Human Resources ........................................................................ 2-27

2.2.14 Tropical Storms ............................................................................................................... 2-28

2.3 FUTURE WITHOUT PROJECT CONDITION ............................................................................... 2-29

2.3.1 Other Restoration Efforts................................................................................................ 2-29

2.3.2 Coastal Land Loss .......................................................................................................... 2-30

2.3.3 Environmental Consequences of Coastal Land Loss .................................................. 2-31

2.3.4 Socioeconomic Consequences of Coastal Land Loss ................................................. 2-32

2.3.5 Future Hydrology ............................................................................................................ 2-33

2.3.5.1 Future Salinity Conditions ....................................................................... 2-34

2.3.6 Future Water Quality ...................................................................................................... 2-34

2.3.7 Future Soils ..................................................................................................................... 2-35

2.3.8 Future Barrier Island Resources .................................................................................... 2-35

2.3.9 Future Coastal Vegetation Resources .......................................................................... 2-35

2.3.10 Future Wildlife Resources .............................................................................................. 2-35

2.3.11 Future Aquatic and Fisheries Resources ...................................................................... 2-36

2.3.12 Future Storm Surge and Wave Conditions ................................................................... 2-36

2.3.13 Relative Sea Level Rise Scenarios ............................................................................... 2-37

2.4 PROBLEMS AND OPPORTUNITIES ............................................................................................ 2-38

2.4.1 Study Area Problems ..................................................................................................... 2-38

2.4.2 Study Area Opportunities ............................................................................................... 2-45

2.4.3 Identification of Management Measures ....................................................................... 2-47

2.4.4 Descriptions of Measures by Type ................................................................................ 2-47

2.4.4.1 Risk and Uncertainty Associated with Restoration Measure Types ..... 2-53

2.4.5 Planning Subunits ........................................................................................................... 2-57

2.5 STUDY GOALS, CONSTRAINTS, AND OBJECTIVES ............................................................... 2-63

2.5.1 Goals ............................................................................................................................... 2-63

2.5.2 Constraints ...................................................................................................................... 2-63

2.5.3 Challenges Associated with Limited Resources ........................................................... 2-64

2.5.3.1 Sediment Replenishment and Borrow Source Suitability ...................... 2-64

2.5.3.2 Potential Borrow Sources ........................................................................ 2-64

2.5.4 Environmental Planning Guiding Principles .................................................................. 2-67

2.5.5 Risk-Informed Planning Framework .............................................................................. 2-69

2.5.6 Value Engineering .......................................................................................................... 2-69

2.5.7 Trade-Off Analysis .......................................................................................................... 2-71
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2.5.8 Objectives Found to be Unattainable ............................................................................ 2-73

2.5.8.1 Restoration to pre-Mississippi River and Tributaries (1928) 

Conditions ................................................................................................ 2-73

2.5.8.2 Restoration to pre-MRGO (1958) Conditions......................................... 2-73

2.5.8.3 Maintain Existing Wetland Acreage in the Entire Study Area ............... 2-74

2.5.9 Study Objectives and Metrics ........................................................................................ 2-74

2.6 IDENTIFICATION AND SCREENING OF MANAGEMENT MEASURES .................................. 2-83

2.6.1 Initial Formulation and Screening Process .................................................................... 2-86

2.6.1.1 Freshwater Diversions Initial Screening ................................................. 2-87

2.6.1.2 Hydrologic Restoration Initial Screening Results ................................... 2-92

2.6.1.3 Marsh and Swamp Restoration Measures Initial Screening Results .... 2-94

2.6.1.4 Shoreline Protection Measures Initial Screening Results ...................... 2-97

2.6.1.5 Ridge Restoration Measures Initial Screening Results ....................... 2-100

2.6.1.6 Vegetative Planting Measures Initial Screening Results ..................... 2-102

2.6.1.7 Barrier Island Restoration Measures Initial Screening Results ........... 2-103

2.6.1.8 SAV Demonstration Projects Initial Screening Results ....................... 2-104

2.6.1.9 Artificial Oyster Reef Measures Initial Screening Results ................... 2-104

2.6.2 Summary of Initial Screening Results ......................................................................... 2-105

2.7 ALTERNATIVE PLAN FORMULATION ...................................................................................... 2-105

2.7.1 Preliminary Evaluation of Measures ............................................................................ 2-106

2.7.2 Cost Effectiveness/Incremental Cost Analysis ........................................................... 2-111

2.7.2.1 Minimum Planning Increment ............................................................... 2-112

2.7.3 Selection of the Final Array of Alternatives ................................................................. 2-125

2.7.4 Final Array of Alternatives ............................................................................................ 2-134

2.8 EVALUATION OF ALTERNATIVE PLANS ................................................................................. 2-143

2.8.1 Risks and Uncertainties................................................................................................ 2-144

2.8.2 Assessment of Sustainability for Relative Sea Level Rise Scenarios ....................... 2-148

2.8.3 Comparison of Impacts to Significant Resources ....................................................... 2-150

2.9 COMPARISON OF ALTERNATIVE PLANS ............................................................................... 2-158

2.9.1 Completeness, Effectiveness, Efficiency and Acceptability ....................................... 2-158

2.9.2 Comparison to Recommendations in LCA, LACPR, and the 2007 State Master 

Plan ............................................................................................................................... 2-160

2.10 IDENTIFICATION OF THE FEDERALLY IDENTIFIED PLAN ................................................... 2-166

2.11 DESCRIPTION OF THE FEDERALLY IDENTIFIED PLAN ....................................................... 2-167

2.12 BORROW SITES .......................................................................................................................... 2-167

2.13 IMPLEMENTATION APPROACH ................................................................................................ 2-168

3 SUMMARY OF COORDINATION, PUBLIC VIEWS AND COMMENTS ............................................... 3-1

3.1 COLLABORATIVE PLANNING........................................................................................................ 3-1

3.2 PROJECT DELIVERY TEAM (PDT) ................................................................................................ 3-1

3.3 INTERAGENCY TEAM PARTICIPATION ....................................................................................... 3-1

3.3.1.1 Interagency Team Tasks ........................................................................... 3-1

3.4 NEPA COOPERATING AGENCIES ................................................................................................ 3-2

3.5 AGENCY COORDINATION ............................................................................................................. 3-2

3.6 PUBLIC INVOLVEMENT ACTIVITIES TO DATE ........................................................................... 3-2

3.7 STUDY WEBSITE ............................................................................................................................. 3-2

3.8 STAKEHOLDER VISITS ................................................................................................................... 3-2
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3.9 NATIONAL ENVIRONMENTAL POLICY ACT SCOPING ............................................................. 3-3

3.10 STAKEHOLDER FORUMS .............................................................................................................. 3-3

3.11 NEW ORLEANS DISTRICT QUARTERLY NGO MEETINGS...................................................... 3-4

3.12 SMALL GROUP MEETINGS ............................................................................................................ 3-4

3.13 DRAFT REPORT .............................................................................................................................. 3-6

3.14 US FISH AND WILDLIFE SERVICE RECOMMENDATIONS ....................................................... 3-7

4 FEDERALLY IDENTIFIED PLAN ............................................................................................................... 4-1

4.1 FEDERALLY IDENTIFIED PLAN (FIP) ........................................................................................... 4-1

4.2 RECOMMENDATIONS .................................................................................................................... 4-2

4.2.1 Monitoring and Adaptive Management ........................................................................... 4-6

4.3 PROJECT COST ............................................................................................................................... 4-8

4.3.1 Cost and Schedule Risk Analysis .................................................................................... 4-8

4.3.2 Federally Identified Plan Costs ........................................................................................ 4-9

4.4 COST SHARING AND AGENCY RESPONSIBILITIES ............................................................... 4-11

4.5 OPERATION AND MAINTENANCE .............................................................................................. 4-15

4.6 INSTITUTIONAL REQUIREMENTS .............................................................................................. 4-16

4.7 MRGO ECOSYSTEM RESTORATION PLAN: VIEWS OF THE STATE OF LOUISIANA ....... 4-16

4.8 VIOLET, LOUISIANA FRESHWATER DIVERSION PROJECT, VIEWS OF THE STATE 

OF MISSISSIPPI AND THE STATE OF LOUISIANA ................................................................... 4-17

4.9 REAL ESTATE ................................................................................................................................ 4-20

4.9.1 Estates ............................................................................................................................ 4-20

4.9.2 Navigation Servitude ...................................................................................................... 4-20

4.9.3 Fee (Standard Estate) .................................................................................................... 4-20

4.9.4 Project Partnership ......................................................................................................... 4-20

4.9.5 Real Estate Cost Estimates ........................................................................................... 4-21

4.9.6 Public Law (PL) 91-646 Relocations ............................................................................. 4-21

4.9.7 Relocation of Facilities .................................................................................................... 4-21

4.9.8 Acquisition Schedules .................................................................................................... 4-21

4.9.9 Landowner Concerns ..................................................................................................... 4-22

4.10 FEDERALLY IDENTIFIED PLAN SUMMARY .............................................................................. 4-22

5 LIST OF PREPARERS ................................................................................................................................ 5-1

6 LITERATURE CITED ................................................................................................................................... 6-1

7 ACRONYMS AND ABBREVIATIONS ....................................................................................................... 7-1

8 GLOSSARY .................................................................................................................................................. 8-1

Appendixes:

A Environmental Appendix 

B Engineering Appendix 

C Real Estate Plan
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report Contents 

v June 2012 

Figure Page 

Figure S-1 Study Area .............................................................................................................................................. S-8

Figure S-2 Chatry Line ........................................................................................................................................... S-13

Figure S-3. System-Wide Problems and Potential Management Measures ...................................................... S-14

Figure S-4. Systems Context ................................................................................................................................. S-23

Figure S-5. Alternative C, Federally Identified Plan .............................................................................................. S-27

Figure S-6. Alternative C, Federally Identified Plan – Perspective View ............................................................. S-28

Figure 1-1. Study Area ............................................................................................................................................. 1-5

Figure 1-2. Completed MRGO Rock Closure Structure ......................................................................................... 1-6

Figure 1-3. Salinity Impacts of the MRGO ............................................................................................................ 1-11

Figure 2-1. Planning Process ................................................................................................................................... 2-2

Figure 2-2. Sedimentation Process ......................................................................................................................... 2-7

Figure 2-3. Average Salinity 1959-1961 (in parts per thousand) ......................................................................... 2-11

Figure 2-4. Annual Average Salinity 1990-2008 (in parts per thousand) ............................................................ 2-12

Figure 2-5. Post-MRGO Closure Annual Average Salinity (in parts per thousand) ............................................ 2-13

Figure 2-6. Habitat Diversity Degradation ............................................................................................................ 2-18

Figure 2-7. Pre-Altered Habitat and Biodiversity ................................................................................................... 2-19

Figure 2-8. Projected Future Land Loss 2050. ..................................................................................................... 2-31

Figure 2-9. System-Wide Problems and Potential Management Measures ....................................................... 2-39

Figure 2-10. Conceptual Ecological Model ........................................................................................................... 2-40

Figure 2-11. Fragmented Marsh Separating Lake Borgne from the MRGO. ..................................................... 2-41

Figure 2-12. Potential Pathways of Change among Habitats and the Associated Driving Forces .................... 2-42

Figure 2-13. Aerial view of Breton Island (2009) ................................................................................................... 2-43

Figure 2-14. Study Area Potential Management Measures ................................................................................. 2-46

Figure 2-15. Caernarvon Freshwater Diversion ................................................................................................... 2-48

Figure 2-16. Dredge Material Placement for Marsh Restoration ......................................................................... 2-49

Figure 2-17. Dredge Piping Sediment from the Mississippi River to Restore Marsh ......................................... 2-50

Figure 2-18. Example of Onshore Placement of Rock for Shoreline Protection ................................................. 2-51
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Figure Page 

Figure 2-19. Example of Offshore Placement of Rock for Shoreline Protection ................................................. 2-51

Figure 2-20. Study Area Subunit ........................................................................................................................... 2-58

Figure 2-21. Areas Affected by the MRGO and Lake Borgne Ecosystem Subunits .......................................... 2-61

Figure 2-22. Salinity Target Line Identified by Chatry et al. 1983 ........................................................................ 2-79

Figure 2-23. Critical Landscape Features for Storm Surge Damage Risk Reduction ........................................ 2-81

Figure 2-24. Multiple Lines of Defense Strategy (Source: Lopez 2006).............................................................. 2-82

Figure 2-25. Freshwater Diversion Location Constraints ..................................................................................... 2-88

Figure 2-26. Preliminary Features Evaluated ..................................................................................................... 2-105

Figure 2-27. Actual and Predicted Acreage for Subunit 17 ................................................................................ 2-107

Figure 2-28. Sub-Area Best Buys ........................................................................................................................ 2-121

Figure 2-29. Geographic Subareas ..................................................................................................................... 2-122

Figure 2-30. Incremental Costs and Outputs ...................................................................................................... 2-133

Figure 2-31. Lower Ninth Ward Bienvenue Triangle Recreation Feature ......................................................... 2-137

Figure 2-32. Shell Beach Recreation Feature .................................................................................................... 2-138

Figure 2-33. Recreation Features Overview ....................................................................................................... 2-139

Figure 2-34. Alternative B..................................................................................................................................... 2-163

Figure 2-35. Alternative C .................................................................................................................................... 2-164

Figure 2-36. Alternative D .................................................................................................................................... 2-165

Figure 2-37 Borrow Sites for Federally Identified Plan ....................................................................................... 2-173

Figure 2-38 Implementation Sequence for Federally Identified Plan ................................................................ 2-174

Figure 2-39 Construction Sequence for Federally Identified Plan ..................................................................... 2-175

Figure 2-40. Restoration and Dredged Material Quantities ............................................................................... 2-176

Figure 2-41. Federally Identified Plan and Actions by Others ............................................................................ 2-177

Figure 2-42. Federally Identified Plan and LACPR Recommendations ............................................................ 2-178

Figure 4-1. Federally Identified Plan ........................................................................................................................ 4-6

Figure 4-2. State of Louisiana Letter ..................................................................................................................... 4-18

Figure 4-3. State of Mississippi Letter ................................................................................................................... 4-19
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Table Page

Table S-1. Key Assumptions ................................................................................................................................. S-10

Table S-2. System-Wide Study Area Problems and Opportunities ..................................................................... S-12

Table S-3. Final Array of Alternatives .................................................................................................................... S-19

Table S-4. Comparison of the Alternative Plans and Plan Objectives ................................................................ S-20

Table S-5. Project First Costs (October 2011 Price Levels) ................................................................................ S-26

Table 1-1. Direct and Indirect Habitat Impacts of the MRGO Navigation Channel............................................... 1-8

Table 1-2. Prior Studies, Reports, Programs, Projects, and Laws ...................................................................... 1-12

Table 2-1. Key Assumptions .................................................................................................................................... 2-3

Table 2-2. Louisiana Scenic Streams and Rivers in the Study Area ................................................................... 2-26

Table 2-3. Relative Sea Level Rise Projections Over the Period of Analysis ..................................................... 2-37

Table 2-4. System-Wide Study Area Problems and Opportunities ..................................................................... 2-45

Table 2-5. Subunits by Geographic Area and Their Relevance to the MRGO Ecosystem Restoration 

Plan .................................................................................................................................................... 2-59

Table 2-6.Problems in Initial Feature Subunits ..................................................................................................... 2-62

Table 2-7. Cost Comparison of Dredging and Piping Material from Different Borrow Sources ......................... 2-67

(October 2010 Price Levels) .................................................................................................................................. 2-67

Table 2-8. Goals, Objectives, Metrics, and Measures .......................................................................................... 2-76

Table 2-9. Monthly Salinity Targets at the Chatry Line......................................................................................... 2-78

Table 2-10. Habitat Targets ................................................................................................................................... 2-79

Table 2-11. Steps 3 and 4: Freshwater Diversion Measures ............................................................................... 2-89

Table 2-12. Steps 3 and 4: Hydrologic Restoration Measures ............................................................................ 2-92

Table 2-13. Steps 3 and 4: Marsh and Swamp Restoration Measures .............................................................. 2-95

Table 2-14. Steps 3 and 4: Shoreline Protection Measures ................................................................................ 2-97

Table 2-15. Steps 3 and 4: Ridge Restoration Measures .................................................................................. 2-101

Table 2-16. Steps 3 and 4: Vegetative Planting Measures ................................................................................ 2-102

Table 2-17. Steps 3 and 4: Barrier Island Measures .......................................................................................... 2-104

Table 2-18. Steps 3 and 4: SAV Measures ........................................................................................................ 2-104

Table 2-19. Steps 3 and 4: Oyster Reef Measures ............................................................................................ 2-104

Table 2-20. Measures Retained for Plan Formulation........................................................................................ 2-109

Table 2-21. Best Buy Plans ................................................................................................................................. 2-124

Table 2-22. Best Buy Plan Descriptions .............................................................................................................. 2-124

Table 2-23. Best Buy Plan Significance .............................................................................................................. 2-128
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Table Page

Table 2-24. Final Array of Alternatives ................................................................................................................ 2-134

Table 2-25 Restoration Features Included in the Final Array ............................................................................ 2-140

Table 2-26. Relative Sustainability of Features .................................................................................................. 2-147

Table 2-27. Sustainability under Relative Sea Level Rise by Feature. ............................................................. 2-149

Table 2-28. Evaluation of Potential Impacts to Significant Resources by Alternative over the Period of 

Analysis............................................................................................................................................ 2-151

Table 2-29. Comparison of the Alternative Plans and Plan Objectives ............................................................. 2-158

Table 2-30. Comparison of Completeness, Effectiveness, Efficiency, and Acceptability ................................. 2-159

Table 2-31. Robustness of Features in FIP under All Relative Sea Level Rise Scenarios* ............................ 2-170

Table 3-1. Small Group Meetings ............................................................................................................................ 3-5

Table 4-1. Implementation Table ............................................................................................................................. 4-3

Table 4-2. Adaptive Management Threshold and Trigger Matrix .......................................................................... 4-7

Table 4-3 Summary of MAMP Costs for the MRGO Ecosystem Restoration Project ......................................... 4-7

(October 2011 Price Levels) .................................................................................................................................... 4-7

Table 4-4. Project First Costs for FIP (In October 2011 $1,000) .......................................................................... 4-9

Table 4-5. Project First s for Tier 1 (In October 2011 $1,000) ............................................................................. 4-10

Table 4-6. Project First Costs for Tier 2 (In October 2011 $1,000) ...................................................................... 4-10

Table 4-7. Project First Costs for Tier 3B (In October 2011 $1,000)................................................................... 4-10

Table 4-8. Incremental Cost Schedule – Tentatively Selected Plan (October 2011 Price Levels, 

$1,000‘s) ............................................................................................................................................ 4-11

Table 4-9. OMRR&R Costs by Tier (October 2011 Price Levels) .................................................................... 4-16
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 

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S REPORT SUMMARY: MISSISSIPPI RIVER GULF OUTLET 

(MRGO) ECOSYSTEM RESTORATION PLAN 

S.1 STUDY INTRODUCTION AND INFORMATION 

Approximately 3,000 years ago the Mississippi River followed a different course than it does 

today as it drained water from the interior of the continent to the Gulf of Mexico. Geologists call 

this ancient river pathway the St. Bernard Delta. While on this course, the river created a vast 

complex of coastal wetlands east of New Orleans that remain between the city and the gulf 

today. Tidal salt marshes in this one part of Louisiana‘s coast alone surpass the total acreage of 

salt marsh found along the entire east coast of the United States. 

The area‘s rare and sensitive coastal habitats are home to thousands of resident and migratory 

waterfowl, numerous fresh water, estuarine and marine fish species, as well as many reptiles 

and mammals. Cypress swamps are generally found close to the river in the fresher portions of 

the estuary. Coastal ridges that were formed by the ancient tributaries of the Mississippi River 

support oak trees and other woody vegetation offering refuge habitat to the estuary‘s nonaquatic inhabitants. The outer barrier islands protecting the estuary form a unique wild 

landscape along the Louisiana coast. These sand islands harbor submerged seagrasses that 

provide food and shelter for fish, marine turtles, and diving birds. In addition, the island beaches 

provide important spawning habitat for gulf fishes. President Roosevelt visited Breton Island at 

the southern end of the Chandeleur Island chain. Out of concern for nesting shore birds on the 

island the President designated it as the Nation‘s second National Wildlife Refuge in 1904. 

New Orleans is world renowned for its rich culinary tradition. A large part of this tradition stems 

from the bounty that fishermen catch and haul from the area‘s wetlands and waterways. The 

marshlands east of the river are recognized by the state‘s wildlife and fisheries commission as 

the ―backbone of the oyster industry.‖ Blue crabs, both jumbo hard crabs and soft shell crabs, 

are a delicacy shipped far and wide to tables in some of the Nation‘s best restaurants. With the 

downturn in oyster and crab harvests in the Chesapeake Bay region, supplies from Louisiana 

estuaries have increased in notoriety and economic importance. 

Sportsmen from the New Orleans area and beyond depend on area marshes for recreational 

pursuits. Charter trips for fishing in the Biloxi Marsh, a large wetland complex located between 

Chandeleur Sound and Lake Borgne, are commonplace. Many fly fishermen and other salt 

water fishermen travel to this area that has been nicknamed ―the land of the giants‖ because of 

the large schools of red drum that populate the wetlands, bayous and bays in the system. From 

a waterfowl perspective, the wetlands near New Orleans has been described as a location of 

―extreme importance‖ and ―by far the one of the most important areas in southeast Louisiana.‖ 

From a historical perspective, the wetlands east and southeast of New Orleans have played an 

important role for our Nation and the world. In 1815 the British army approached the American 

forces at New Orleans by marching up the banks of Bayou Bienvenue after disembarking from 

their ships in Lake Borgne. Those same soldiers made their retreat along the bayou after the 

American victory at the Battle of New Orleans. During a later war, the waterways and wetlands 

of the area served as a testing ground for Andrew Higgins‘ beach landing craft. The specialized 

shallow draft vessels were designed and manufactured in New Orleans. The boats were key 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report Summary 

S-2 June 2012 

equipment needed to land Allied forces on the beaches of Normandy. General Eisenhower later 

credited Mr. Higgins and his boats with helping to win World War II. 

After the war, America‘s soldiers returned home and the Nation turned its focus to economic 

development. The Port of New Orleans, a key maritime center for the country, viewed the 

wetlands east of the city and along the Gulf Intracoastal Waterway as prime areas for industrial 

and maritime expansion. Plans were devised to expand the port to accommodate more 

international trade and better secure naval defense forces. This vision led to the creation of a 

Tidewater Development Association that promoted the concept of a seaway canal for ships. The 

port commission, the development association and the Louisiana Congressional delegation 

worked to have the Corps of Engineers create navigation plans for a new canal linking the port 

to the Gulf of Mexico. The purpose of the canal was to eliminate the need for vessels to make 

the difficult and dangerous trip from the Gulf of Mexico up and down the Mississippi River to the 

riverside wharfs in New Orleans. After ship channel studies were completed, Congress provided 

funds in 1956 for the Corps of Engineers to construct the Mississippi River Gulf Outlet. 

The Mississippi River Gulf-Outlet (MRGO or ―Mister Go‖) was a 76-mile manmade navigation 

channel built to provide a shortcut from the inner harbor area of the Port of New Orleans to the 

Gulf of Mexico. Constructed in 1950s-1960s, the MRGO navigation channel directly removed 

wetland habitat and influenced ecosystem changes. The channel allowed the intrusion of 

saltwater into the vast wetland complex bordering the City of New Orleans and surrounding 

coastal communities east of the Mississippi River. The dredging and filling during the 

construction of MRGO destroyed thousands of acres of wetlands, interrupted the local 

circulation patterns of natural waterways that transected the channel, and breached an 

important hydrologic boundary when the channel was cut through the ridge at Bayou La Loutre. 

After the MRGO was completed, significant habitat shifts occurred as the area converted to a 

higher salinity system as a result of saltwater intrusion from the gulf into the estuary. Operation 

of the MRGO resulted in high rates of shoreline erosion from ship wakes, further destroying 

wetlands and threatening the integrity of the Lake Borgne shoreline and adjacent communities, 

infrastructure, and cultural resources. Erosion of the MRGO channel banks and the daily influx 

of saltwater in the tides facilitated the transition of the estuary toward a more saline system. 

Prior to construction of the MRGO, tidal movement into Lake Borgne was dominated by flow 

from Mississippi Sound. The tidal flow from Breton Sound was reduced as it moved northwest 

across the marshes and wetlands toward Lake Borgne. Following construction of the MRGO the 

circulation pattern reversed, with the dominant tidal flow into Lake Borgne coming from the 

Breton Sound area via the MRGO. Before channel construction, habitats were aligned along 

salinity gradients and reflected a varied landscape and interspersed watercourses. 

Public controversy surrounding the channel arose even before its construction and spanned 

over five decades before the landfall of Hurricane Katrina in 2005. After the storm, the Corps of 

Engineers responded to Congressional direction and developed a channel closure plan. In 

2009, the ship channel was closed with a large rock structure at the site of a prominent coastal 

ridge (Bayou La Loutre) that had been severed during channel construction. As a result of the 

closure, ship traffic no longer transits the channel and environmental conditions are improving 

with salinity falling throughout the estuary. Although positive, these environmental benefits will 

not replace the habitats lost in the area. 
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In the Water Resources Development Act (WRDA) 2007, Congress requested an ecosystem 

restoration plan for the areas affected by the MRGO channel and a plan to restore natural 

features that reduce storm surge damages. This report tells how the United States Army Corps 

of Engineers (USACE), along with an interagency team and local stakeholders, developed a 

plan to restore one of the most unique and productive ecosystems in the world. 

S.2 STUDY AND PROJECT AUTHORITY 

The study is authorized by WRDA of 2007 Section 7013 to develop a plan that would: 

 physically modify the MRGO and restore the areas affected by the navigation channel; 

 restore natural features of the ecosystem that will reduce or prevent damage from storm 

surge; 

 prevent the intrusion of saltwater into the waterway; 

 integrate the recommendations of the Louisiana Coastal Area Report and the Louisiana 

Coastal Protection and Restoration Technical Report; and

 consider the use of native vegetation and diversions of fresh water to restore the Lake 

Borgne ecosystem. 

The plan is conditionally authorized for construction, pending the determination by the Assistant 

Secretary of the Army (Civil Works) (ASA(CW)) that the project is cost-effective, environmentally 

acceptable, and technically feasible. This conditional authorization also assumes that a viable 

sponsor(s) will be identified as required by Section 221 of Public Law 91-611, Flood Control Act 

of 1970, as amended and by Section 103 of the WRDA 1986, as amended. 

Additionally, the MRGO Ecosystem study initiated study of the Violet, Louisiana Freshwater 

Diversion project, as authorized by Section 3083 of WRDA 2007, for the design and 

implementation of a freshwater diversion at or near Violet, Louisiana for purposes of reducing 

salinity in the western Mississippi Sound, enhancing oyster production, and promoting the 

sustainability of coastal wetlands. The report recommends that the feasibility-level study 

regarding the Violet, Louisiana Freshwater Diversion be continued under the authority of 

Section 3083 of WRDA 2007, together with those elements of the MRGO Ecosystem 

Restoration project for which success requires the implementation of the Violet, Louisiana 

Freshwater Diversion Canal. 

S.3 STUDY AND PROJECT AUTHORITY 

MRGO ECOSYSTEM RESTORATION PLAN: VIEWS OF THE STATE OF LOUISIANA: 

The study is 100% Federally funded. After extensive discussions with the State of Louisiana, a 

non-Federal sponsor has not been identified for implementation of the MRGO Ecosystem 

Restoration Plan authorized by Section 7013 of WRDA 2007. 

The State of Louisiana has been involved in the development of the MRGO ecosystem 

restoration plan. The plan has been formulated to be consistent with Louisiana's 

Comprehensive Master Plan for a Sustainable Coast (Master Plan). For example, the 2007 

State Master Plan specifically recommended restoration of wetlands and swamps in the Central 

Wetlands and Golden Triangle areas, which is included in the FIP. The Master Plan was 
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Final Feasibility Report Summary 

S-4 June 2012 

developed with intensive public input and was unanimously adopted by the Louisiana 

Legislature. 

In a letter dated August 12, 2010, the State of Louisiana expressed ―its continuing support of the 

Mississippi River Gulf Outlet Ecosystem Restoration Project‖ and declared ―full support for the 

Mississippi River Gulf Outlet Ecosystem Restoration Program" (See Figure 4-2). However, this 

letter also expresses the State of Louisiana‘s view that the Mississippi River-Gulf Outlet 

Ecosystem Restoration Project should be undertaken at full Federal expense and that the state 

should have no financial obligations with respect to the Mississippi River Gulf Outlet Ecosystem 

Restoration Project. 

Implementation of the ecosystem restoration plan would require identification of a non-Federal 

sponsor and execution of a binding cost sharing agreement. As of the date of this report, 

USACE has not received a letter of intent from the State of Louisiana to serve as the nonFederal sponsor to cost share in implementation of the ecosystem restoration plan. The USACE 

will continue to coordinate with the State of Louisiana in the development and implementation of 

the restoration plan. 

VIOLET, LOUISIANA FRESHWATER DIVERSION PROJECT, VIEWS OF THE STATE OF 

LOUISIANA AND THE STATE OF MISSISSIPPI 

Section 3083 of WRDA 2007, citing the Corps of Engineers feasibility study entitled ―Mississippi and 

Louisiana Estuarine Areas: Freshwater Diversion to Lake Pontchartrain Basin and Mississippi 

Sound‖ dated 1984, authorizes the Corps of Engineers to design and implement a project for the 

diversion of freshwater at or near Violet, Louisiana for the purposes of reducing salinity in the western 

Mississippi Sound, enhancing oyster production and promoting the sustainability of coastal wetlands. 

Section 3083 identifies the State of Louisiana and the State of Mississippi as non-Federal sponsors 

for the non-Federal 25% share of the design and implementation of the Violet, Louisiana Freshwater 

Diversion project. 

The State of Mississippi, along with the State of Louisiana, has been actively involved in the 

development of the Violet, Louisiana Freshwater Diversion project. The final recommendations for 

the plan addressed in this report include a recommendation for additional analysis, design and 

implementation of the Violet Freshwater Diversion as authorized by WRDA 2007 Section 3083.. In a 

letter dated September 20, 2010 the Mississippi Department of Marine Resources (MDMR) declared 

its full support for the Violet, Louisiana Freshwater Diversion project (See Figure 4-3) and its 

understanding of its non-Federal cost sharing obligation. The State of Mississippi‘s letter also states 

its desire that the USACE, to the fullest extent possible, seek full Federal funding for the project. .

USACE has not received a letter of intent from the State of Louisiana regarding the Violet project; 

however, since this report recommends further study and analysis, such a letter of intent is not 

required at this time.. 

Before the Violet, Louisiana Freshwater Diversion project can be implemented, the USACE will 

require a letter of intent to serve as the non-Federal sponsor and a self-certification of the nonFederal sponsor's financial capability from both the State of Mississippi and the State of 

Louisiana, including a clear statement of each State‘s willingness and ability to provide its 

required cost share and other items of local cooperation for the project, as described in this 

report. Prior to the commencement of construction by USACE, Federal law requires that both 
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S-5 June 2012 

States execute a binding written agreement wherein they agree to provide all of the non-Federal 

obligations for the construction, operation, maintenance, repair, rehabilitation and replacement 

of the Violet, Louisiana Freshwater Diversion project. USACE will continue to coordinate with 

the State of Mississippi and the State of Louisiana in the development and implementation of 

the Violet, Louisiana Freshwater Diversion project. 

S.4 STUDY PURPOSE AND SCOPE 

The MRGO was authorized as a 36-foot-deep, 500-foot-bottom-width waterway (38 feet deep, 

600 feet wide at the Gulf of Mexico entrance) extending from the Inner Harbor Navigation Canal 

(IHNC) to the 38-foot depth contour in the Gulf of Mexico. Construction of the channel began in 

1958 and the channel was completed in 1968. 

In August 2005, Hurricane Katrina caused shoaling in the MRGO channel limiting its depth to 22 

feet, and thus restricted deep-draft vessel access. Rather than continue funding operation and 

maintenance of the channel, in June 2006, the Congress requested a plan for deauthorization of 

the MRGO (see Public Law 109-234). 

The USACE submitted an interim report in December 2006 highlighting a plan to close the 

MRGO from the Gulf Intracoastal Waterway (GIWW) to the Gulf of Mexico. In January 2008, the 

Chief of Engineers signed a report recommending deauthorization of the channel, construction 

of a closure structure across the channel at Bayou La Loutre, and development of a 

supplemental report to provide an ecosystem restoration plan for the areas affected by the 

MRGO. On June 5, 2008, the Assistant Secretary of the Army (Civil Works) (ASA(CW)) 

forwarded the Final MRGO Deep-Draft De-authorization Report to Congress, officially 

deauthorizing the MRGO federal navigation project from the GIWW to the Gulf of Mexico. 

The MRGO Deep Draft De-authorization Report recommendations resulted in the construction 

of a rock closure structure across the MRGO near the Bayou La Loutre ridge in St. Bernard 

Parish, Louisiana, which was completed on July 9, 2009. 

The Mississippi River Gulf Outlet (MRGO) Ecosystem Restoration Plan Feasibility Study is 

being developed as a supplement to the June 2008 MRGO Deep-Draft De-Authorization Report 

and is intended to fully meet the requirements of the Water Resources Development Act 

(WRDA) of 2007 Section 7013. This feasibility study will result in a Report of the Chief of 

Engineers describing the federally identified plan for MRGO Ecosystem Restoration and 

recommending construction of features for early implementation contingent upon the 

identification of a non-Federal sponsor. The Plan will address systematic ecosystem restoration 

and protection of the Lake Borgne ecosystem and areas affected by the MRGO navigation 

channel, and will include considerations of measures to reduce or prevent damage from storm 

surge. The study integrates the findings of ongoing comprehensive restoration planning efforts 

in the study area, including the Louisiana Coastal Protection and Restoration (LACPR) Final 

Technical Report, the Louisiana Coastal Area (LCA) Program, and Louisiana‘s Comprehensive 

Master Plan for a Sustainable Coast. 

The cumulative effects of human and natural activities in the Louisiana coastal area have 

severely degraded the deltaic processes and shifted the coastal area to a net land loss 

condition. Many studies have been conducted to identify the major contributing factors (e.g., 
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Boesch et al. 1994; Turner 1997; Penland et al. 2000), and many studies agree that land loss 

and the degradation of the coastal ecosystem are the result of both natural and human induced 

factors, producing conditions where wetland vegetation can no longer survive and land is lost. 

Establishing the relative contribution of natural and human-induced factors is difficult. In many 

cases, the changes in hydrologic and ecologic processes manifest gradually over decades and 

in large areas, while other effects occur over single days and impact relatively localized areas. 

The study purpose is to develop alternative plans to restore natural features and processes in 

the Lake Borgne ecosystem and areas affected by the former navigation channel. Construction 

recommendations will be developed to restore historic habitat types and natural ecological 

processes in concert with other large-scale comprehensive ecosystem restoration plans. 

S.4.1 Project Location / Congressional District 

The study area (Figure S-1) includes portions of the Mississippi River Deltaic Plain in coastal 

southeast Louisiana and parts of coastal southwest Mississippi. It encompasses approximately 

3.84 million acres (6,023 square miles) of land and open water. 

The study area is located in Louisiana Congressional Districts 1, 2, and 3; and Mississippi 

Congressional District 4. 

S.4.2 Prior Studies, Reports and Existing Water Projects 

Information related to the study area has been accumulated over more than five decades. This 

study builds upon existing studies, reports and plans. For example, study area problems and 

opportunities have been documented in numerous prior studies. Where conditions have 

changed or new information has become available, additional analyses have been performed to 

develop an ecosystem restoration plan based on sound science and engineering. 

S.4.3 Federal Interest 

For ecosystem restoration projects, alternatives are evaluated using contributions to National 

Ecosystem Restoration (NER). The basis of this contribution is cost effectiveness and 

incremental cost analyses of the possible restoration alternatives and significance of ecosystem 

outputs (benefits) that accrue in the planning area and the nation. 

By law and current and past Administration policy, ecosystem restoration, navigation and flood 

damage reduction are the primary missions of the Corps of Engineers. The need to reduce the 

loss of Louisiana coastal wetlands has been recognized by the current and past Administrations 

and Congress. The Coastal Wetlands Planning, Protection and Restoration Act program 

(CWPPRA or ―Breaux Act‖) provides targeted funds through 2019 to be used for planning and 

implementing projects that create, protect, restore and enhance wetlands in coastal Louisiana. 

The Coastal Impact Assistance Program (CIAP) was authorized by Section 384 of the Energy 

Policy Act of 2005, to assist coastal producing states and their political subdivisions in mitigating 

the impacts from Outer Continental Shelf (OCS) oil and gas production. Louisiana is one of the 

six coastal states selected to receive funds under this appropriation to implement this program. 

On November 8, 2007, Congress passed the Water Resources Development Act of 2007, 

authorizing the MRGO Ecosystem Restoration Plan. 
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In October 2009, President Obama formed the Louisiana-Mississippi Gulf Coast Ecosystem 

Restoration Working Group, co-led by the White House Council on Environmental Quality (CEQ) and 

the Office of Management and Budget (OMB) and comprising senior-level officials from the National 

Oceanic and Atmospheric Administration (NOAA), the U.S. Environmental Protection Agency (EPA), 

and the Departments of the Army (USACE), Homeland Security, the Interior, and Transportation. The 

Working Group has developed a Roadmap for Restoring Ecosystem Resiliency and Sustainability in 

the Louisiana and Mississippi Coast. One of the findings of this roadmap is that ―bold and decisive 

action is needed now to curtail the rate of wetland loss and barrier island erosion in the area and to 

restore some of these lost features and ecosystem services.‖ 

The Administration has repeatedly demonstrated a commitment to coastal restoration in 

Louisiana. President Barack Obama made the following statement during his 2009 visit to the 

Gulf Coast: 

“We've already seen 220 miles worth of levees and flood walls repaired, and we are 

working to strengthen the wetlands and barrier islands that are the first line of defense for 

the Gulf Coast. This isn't just critical to this region's physical protection, it's critical to our 

environment, it's critical to our economy.” - President Barack Obama, October 15, 2009 

During this visit, the Council on Environmental Quality visited the Bienvenue Triangle in the 

Central Wetlands. Restoration of this area is a key component of the study. 

The nation derives significant benefits from the coastal Louisiana ecosystem: protection for the 

production and transport infrastructure for about 30 percent of the nation‘s oil and gas supply; 

the Nation‘s second largest commercial fishery; and navigation and port facilities which together 

support America‘s number one port complex by tonnage. 
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Figure S-1 Study Area
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Final Feasibility Report Summary 

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The plan would restore rare and unique habitat, including coastal ridge, cypress swamp, and 

fresh marsh. These habitat types are institutionally and technically significant due to relative 

scarcity and importance. The study area includes environmental resources that are protected by 

the Endangered Species Act of 1973; Fish and Wildlife Conservation Act of 1980; Fish and 

Wildlife Coordination Act of 1958, as amended; Migratory Bird Conservation Act; Migratory Bird 

Treaty Act; and Executive Order 13186 Migratory Bird Habitat Protection. 

The USFWS, in a letter dated October 31, 2008, formally requested that significant fish and 

wildlife resources be fully considered and addressed in this study, including: seabirds, 

shorebirds, wading birds, migratory and resident waterfowl, and estuarine-dependant fishes and 

shellfishes. 

Coastal Louisiana‘s wetlands support neotropical and other migratory avian species such as 

rails, gallinules, shorebirds, wading birds, and numerous songbirds, as well as many different 

furbearers, rabbits, deer, and alligators. Louisiana coastal wetlands provide neotropical 

migratory birds essential stopover habitat on their annual migration route. The coastal wetlands 

in the study area provide important and essential fish and wildlife habitats, used for shelter, 

nesting, feeding, roosting, cover, nursery, and other life requirements. 

Emergent wetlands and shallow open water areas in the study area provide important habitat 

and Essential Fish Habitat (EFH). By letter dated October 27, 2008, the National Marine 

Fisheries Service (NMFS) indicated water bodies and wetlands in the study area provide 

nursery and foraging habitats supportive of a variety of economically important marine fishery 

species. Some of these species also serve as prey for other fish species managed under the 

Magnuson-Stevens Act by the Gulf of Mexico Fishery Management Council and highly 

migratory species managed by NMFS. 

Wetlands of national interest that would benefit from the implementation of the FIP include those 

found in the Bayou Sauvage National Wildlife Refuge and the Pearl River and Biloxi Wildlife 

Management Areas. 

S.4.4 Key Planning Assumptions 

In formulating and evaluating alternatives, certain assumptions or simplifications were required. 

Table S-1 provides a brief summary of the major assumptions and the scientific basis or 

rationale behind each assumption. 
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Table S-1. Key Assumptions

Assumption Rationale for the Assumption

Study Area

The MsCIP (Mississippi Coastal Improvements 

Program) and other planning efforts led by the 

USACE Mobile District will address vegetated 

habitat ecosystem restoration needs in the 

portions of the study area located in Mississippi. 

Except for diversions of freshwater, the MRGO 

ecosystem restoration study will not formulate 

measures for the purpose of ecosystem 

restoration in Mississippi.

The MsCIP Comprehensive Plan addressed 

ecosystem restoration needs in the Bay St. Louis 

and western Mississippi Sound areas, such as 

barrier island and submerged aquatic vegetation 

restoration. To avoid redundancy and ensure 

consistency with that plan, the MRGO ecosystem 

restoration plan will not re-evaluate those 

authorized measures.

Plan Objectives

It is not a study objective or restoration target to 

restore the study area to a pre-MRGO 

hydrologic condition.

This condition cannot be achieved within the study 

constraints due to authorized navigation and risk 

reduction protection projects and other landscape 

changes.

The primary purpose of the plan is ecosystem 

restoration. Hurricane and storm damage risk 

reduction through the protection and restoration 

of natural features contributes to the need for 

the plan and is an authorized goal of the study. 

The reduction of damages will not be monetarily 

quantified. This portion of the study authority will 

be achieved through the restoration of habitat in 

areas identified as critical landscape features for 

storm surge reduction in scientific literature.

The WRDA implementation guidance dated 28 

April 2009 says, ―Alternative plans shall be 

formulated for the purpose of ecosystem 

restoration inclusive of the requirements set forth in 

Section 7013 of WRDA 2007.‖ Ecosystem 

restoration studies do not require the quantification 

of economic benefits. Benefits of coastal landscape 

features with respect to hurricane and storm 

damage risk reduction are difficult to empirically 

quantify due to the complex interaction of dynamic

variables.

Future Without Project Conditions

Restoration of the Lake Maurepas swamps is 

assumed to be part of the future without project 

conditions.

Swamp restoration in these areas is addressed

through several authorized LCA and CWPPRA 

diversion projects.

Period of Analysis

For comparison of alternatives, the total period 

of analysis is from 2011 to 2065.

The period of analysis includes implementation 

plus 50 years. The implementation phase is 2012 

to 2015 (begins with the first PED year; concludes 

with first construction completion year). The 50-

year period begins with the first year of operation 

(first year when benefits would be realized) and is 

2015 to 2065. Consideration beyond the period of 

analysis is given to environmental factors. 
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Table S-1. Key Assumptions

Assumption Rationale for the Assumption

Relationship to Violet, Louisiana Freshwater Diversion Authority

Section 3083 of WRDA 2007 authorizes the 

design and implementation of a diversion at or 

near Violet, Louisiana, which is located within 

the MRGO Ecosystem Restoration Plan study 

area. A freshwater diversion project at or near 

the Violet Canal will be analyzed as a 

component of the MRGO Ecosystem 

Restoration Plan. 

This study has identified that a freshwater diversion 

at or near Violet may be a key driver in the 

sustainability of the restoration of areas affected by 

the MRGO and the Lake Borgne ecosystem. 

Feasibility level investigations of the project 

authorized in WRDA 2007 Section 3083, will be 

included in this study, consistent with the 

Implementation Guidance for Section 7013 WRDA 

2007 dated 28 April 2009.

Minimum Restoration Target

The minimum restoration targets were 

developed to include direct and indirect habitat 

impacts of the former navigation channel by 

habitat type. Impacts include construction, 

operation, and maintenance of the MRGO 

through 2008. 

These targets were set to produce a plan that 

meets the requirements of the study authority and 

USACE requirements for completeness, 

effectiveness, efficiency, and acceptability. 

Measures

Maintenance will be performed on all plan

features. 

Periodic maintenance actions will be developed to 

sustain benefits over the period of analysis.

Marsh restoration areas will include vegetative 

plantings but marsh nourishment areas will not.

Marsh nourishment is performed using a thin layer 

of sediment slurry over existing marsh so it is 

assumed that the existing marsh vegetation will 

survive.

S.5 STUDY OBJECTIVES 

S.5.1 Problems and Opportunities 

Study area problems and opportunities have been documented in numerous prior studies. 

Systemic problems were identified for the entire study area. The study area was divided into 

subunits, and each subunit was examined to determine specific problems and opportunities for 

these smaller areas. The overarching environmental 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 and operation of the MRGO, contributed to 

degradation in the Lake Borgne ecosystem, and threaten the long-term viability of the study 

area. 

Table S-2 identifies study area problems and ecosystem restoration opportunities to address 

each problem (see also Figure S-3). 
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Table S-2. System-Wide Study Area Problems and Opportunities 

Problems Opportunities

Decreased Freshwater, 

Sediment, and Nutrient 

Inputs

Increase sediment, freshwater, and nutrient inputs Increase organic 

deposition.

Modification of Natural 

Hydrology

Restore altered tidal circulation patterns and improve water quality.

Saltwater Intrusion Prevent saltwater intrusion.

Wetland Loss Create wetlands, nourish, and prevent the continued loss of wetlands. 

Ridge Habitat Degradation 

and Destruction

Restore ridge habitat.

Bank/Shoreline Erosion Prevent bank and shoreline erosion.

Habitat Changes and Loss Restore habitat types such as swamps, ridges, submerged aquatic 

vegetation, oyster reefs, and barrier islands.

Invasive Species Eliminate or reduce invasive species.

Herbivory Prevent herbivory.

Retreating and Eroding 

Barrier Islands

Restore barrier islands.

Human Development 

Susceptible to Storm Surge

Reduce or prevent storm surge damage through restoration of natural 

ecosystem features.

S.5.2 Planning Objectives 

Planning objectives were developed to address systemic ecosystem problems and the 

Congressional mandate of the study authority. Construction and maintenance of the MRGO 

caused wetland loss and environmental damage in the study area. The study objectives were 

developed to address the habitat impacts of the former navigation channel to restore study area 

biodiversity and ecosystem function. The storm surge risk reduction component of the study 

authority was addressed by including restoration of critical landscape features in the objectives. 

While storm models show benefits from additional marsh, island, and landbridge habitat in some 

areas, the effects of allowing existing features to degrade in these areas are even more 

pronounced (USACE 2009). 

The objectives for the MRGO Ecosystem Restoration Plan follow: 

1. Restore historic salinity conditions in the study area to re-establish and maintain historic habitat 

types; optimize ecosystem services; and decrease stress to vegetation as measured by the 

monthly salinity targets in the Biloxi Marsh (as identified by Chatry et al. 1983) each month of the 

year, for at least four years out of every ten year period (see Figure S-2). 

2. Restore native habitat acreages impacted by the MRGO and their ecosystem functions. 

a. Increase the year round spatial coverage of cypress swamp habitat in the Central Wetlands 

by at least 9,500 acres by 2065. 

b. Increase the year round spatial coverage of fresh/intermediate marsh in the Central 

Wetlands, Golden Triangle, MRGO, and South Lake Borgne by at least 6,800 acres by 2065. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report Summary 

S-13 June 2012 

c. Increase the year round spatial coverage of brackish marsh in Bayou Terre aux Boeufs, the 

Biloxi Marsh, and the East Orleans Landbridge by approximately 18,100 acres by 2065. 

d. Increase the year round spatial coverage of vegetated wetlands in areas adjacent to the 

channel lost to increased tides and salinity by at least 3,900 acres by 2065. 

e. Increase the year round spatial coverage of ridge habitat along Bayou La Loutre by 2065. 

3. Increase the year round spatial coverage of critical landscape features that provide hurricane and 

storm damage risk reduction in the study area (i.e. areas located in the Biloxi Marshes, the East 

Orleans Landbridge, and forested habitats). 

4. Increase awareness and understanding of the significance of resources in the study area through 

increased recreational and educational opportunities. 

Figure S-2 Chatry Line 
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Figure S-3. System-Wide Problems and Potential Management Measures 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

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S.5.3 Planning Constraints 

Planning constraints are restrictions that limit the extent of the planning process. For this study, 

the planning constraints are: 

 Avoid or minimize negative impacts to threatened and endangered species to the 

extent practicable. 

 Avoid or minimize impacts to critical habitat to the extent practicable. 

 Do not diminish the level of protection provided by authorized flood risk reduction 

projects and hurricane storm damage risk reduction projects. 

 Avoid actions that negatively affect the ability of authorized navigation projects to 

continue to fulfill their purpose to the extent practicable. 

 Minimize impacts to commercial fisheries (such as oysters). 

 Avoid or minimize contributions to low dissolved oxygen concentrations or conditions 

that could result in detrimental algal blooms. 

S.6 PLAN FORMULATION RATIONALE 

Alternative plans are formulated across a range of potential scales to demonstrate the relative 

effectiveness of various approaches at varying scales. Alternatives are formulated recognizing 

study area problems and opportunities, as well as study goals, objectives and constraints with 

consideration of the four Principles and Guidelines (P&G) criteria: completeness, effectiveness, 

efficiency, and acceptability. 

S.7 MANAGEMENT MEASURES AND ALTERNATIVE PLANS 

A management measure is a feature (a structural element that requires construction or 

assembly on-site) or an activity (a nonstructural action) that can be combined with other 

management measures to form alternative plans. Management measures were developed to 

address study area problems and to capitalize upon study area opportunities. Management 

measures were derived from a variety of sources including prior studies, the National 

Environmental Policy Act (NEPA) public scoping process, and the multidisciplinary, interagency 

Project Delivery Team (PDT). Approximately 300 initial structural management measures 

considered can be grouped into the following categories (non-structural measures, such as 

invasive species control, were integrated into structural measures and were not considered 

independently): 

 Freshwater diversions 

 Hydrologic restoration (e.g. plugs, fill, weirs, sills, gaps) 

 Marsh creation, marsh nourishment, and swamp creation or restoration 

 Shore protection 

 Ridge restoration 

 Restoration/creation of forested habitat 

 Vegetative Planting 
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 Barrier island restoration 

 Submerged aquatic vegetation (SAV) restoration 

 Oyster reef restoration 

S.8 MINIMUM PLANNING INCREMENT 

Several measures were considered necessary components of a plan that addressed the study 

authority, considered the significance of ecosystem outputs, and met the goals and objectives 

for the study. A minimum planning increment was included in the plan formulation process to 

produce alternatives that would address the study authority and consider significance of 

outputs, completeness, effectiveness, and acceptability, prior to the evaluation of efficiency 

through cost-effectiveness/incremental cost (CE/ICA) analysis. 

S.8.1 Cypress and Coastal Ridge Habitat 

In an abstract evaluation, cypress and coastal ridge restoration measures are not as costeffective as other types of measures. These restoration measures require more sediment and 

more time to achieve benefits than marsh restoration, and therefore have much higher costs 

compared to benefits. Restoration of cypress and ridge habitat was considered necessary to 

fulfill the requirements of the study authority to ―restore the areas affected by the navigation 

channel,‖ as documented in Habitat Impacts of the Construction of the MRGO and Louisiana 

Coastal Area Ecosystem Restoration Study (USACE 1999, 2004). 

 The former navigation channel was cut through the Central Wetlands and the Bayou La 

Loutre ridge, directly impacting these areas. 

 The Central Wetlands is the only area in the immediate vicinity of the MRGO that could 

support cypress swamp, a scarce habitat rich in biodiversity. Other locations are outside 

of the project area (Caernarvon) or far removed from the channel (LaBranche and 

Maurepas). 

 The only remaining natural ridge in the immediate vicinity of the MRGO is the Bayou La 

Loutre ridge. This habitat is technically significant because of its scarcity, biodiversity, 

and function as a limiting habitat on which species of concern depend (Conner and Day 

1988, Twedt and Portwood 1997, Barrow et al. 2000, USGS 2006, Barrow et al. 2006). 

 Cypress swamp habitat is increasingly scarce and provides unique habitat and 

ecological functions, contributing to the technical significance of these resources 

(Lowery 1974, Conner and Toliver 1990, Messina and Conner 1998, Martin et al. 2002). 

 The restoration of cypress swamp in the Central Wetlands is widely supported by the 

adjacent communities, NGOs, state and local government, and resource agencies, 

demonstrating its public significance (University of Wisconsin-Madison 2008 and 2009, 

SLFPA-E 2009, Day et al. 2006). 

 The ecosystem services provided by these habitat types (e.g. avian and mammalian 

habitat) cannot be provided by other habitat types in the study area (Messina and 

Conner 1998, Barrow et al. 2000, USGS 2006, Barrow et al. 2006). 
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The restoration of these habitats was integral to the development of a complete, effective, 

efficient, and acceptable plan. By definition, the most effective and efficient plan would fully 

achieve the target objective. Therefore, IWR-PLAN formulation was developed to produce plans 

that include features to achieve these objectives. As the ridge habitat does not have a specified 

acreage amount, two scales of ridge restoration were developed, and the smaller feature 

closest to the channel was selected for inclusion in the minimum planning increment. 

S.8.2 Recommendations for MRGO Channel 

Similarly, the inclusion of some features in the MRGO is required to address the LCA NearTerm Project described in Section 7006 (c)(1)(A) of WRDA 2007 and the portion of the 7013 

authority requiring ―a plan to physically modify the Mississippi River-Gulf Outlet‖, despite the 

relative cost-effectiveness of these features. 

Bank reclamation and stabilization along the MRGO is important to prevent the further 

confluence of the MRGO and Lake Borgne and to maintain the MRGO/Lake Borgne 

Landbridge. A plan that did not include features in the MRGO would likely be unacceptable to 

the public and did not appear to meet the Congressional intent of the study. Stabilization of the 

MRGO banks would preserve estuarine wetlands and important structural features of the lake 

and marsh landscape. The MRGO features would prevent future land loss and restore degraded 

wetlands; stabilize and restore the endangered, critical Lake Borgne rim geomorphic structure; 

and protect vital socioeconomic resources, such as communities located adjacent to the MRGO. 

Bank stabilization in the MRGO was identified as a critical near-term need in the LCA report. 

The implementation guidance for the MRGO Ecosystem Restoration Plan states that the 

Section 7006 project ―shall be held in abeyance until the tentatively selected plan for ecosystem 

restoration, authorized by Section 7013 of WRDA 2007, is identified.‖ The implementation 

guidance also states that the feasibility report and EIS for Section 7013 of WRDA 2007 will 

include recommendations regarding the Section 7006 project. 

Although the MRGO features were determined to be less cost-effective than other restoration 

features considered, it was determined that the most cost-effective MRGO features should be 

included in the recommendations for this study. The inclusion of the most cost effective MRGO 

features in the recommendations for the study serves to ―integrate the recommendations of the 

report with the program authorized under section 7003‖ as noted in the study authority. 

S.8.3 Violet, Louisiana Freshwater Diversion 

Alternatives that did not include a freshwater diversion were considered in the initial 

development of alternatives. These alternatives were ultimately eliminated from further study as 

inconsistent with the study goals and objectives. 

Restoration of historic salinity is technically significant because the man-made separation of the 

Mississippi River from the wetlands has decreased biodiversity and increased the scarcity of 

native marsh habitats. These effects were exacerbated by the construction of the MRGO and 

the resultant saltwater intrusion (USACE 1999). A freshwater diversion would restore this 

connection and increase marsh productivity and vertical accretion (DeLaune et al. 2003). 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report Summary 

S-18 June 2012 

A freshwater diversion could fully restore historic salinity conditions and increase freshwater and 

nutrients to nourish existing and restored wetlands in the study area. WRDA 2007 Section 3083 

authorizes the achievement of the benefits described in Mississippi and Louisiana Estuarine 

Areas Freshwater Diversion to Lake Pontchartrain and Mississippi Sound Feasibility Study (also 

known as the Bonnet Carrè study) through the design and implementation of a freshwater 

diversion at or near Violet, LA. However, additional study is needed to improve decisions about 

where, when, and how to divert Mississippi River flows in a systems context. The ongoing 

Mississippi River Hydrodynamic and Delta Management Study will evaluate ecosystem 

restoration alternatives in concert with dynamic flood risk management and navigation; 

multipurpose management scenarios of the river; and dynamic conditions in a comprehensive 

systems context. The information gained from this study will improve decision-making for the 

Violet, Louisiana Freshwater Diversion. Therefore, the final recommendations for the MRGO 

Ecosystem Restoration Plan include additional analysis of the Violet, Louisiana Freshwater 

Diversion under the WRDA 2007 Section 3083 authority. 

S.9 FINAL ARRAY OF ALTERNATIVES 

The Corps‘ Institute for Water Resources (IWR) has developed procedures and software to 

assist in conducting CE/ICA analysis. IWR-PLAN Decision Support Software was used to assist 

in performing CE/ICA. IWR-PLAN software generated 6,721 plan combinations. Including the 

No Action plan (Plan A), there were 285 cost-effective plans and 19 ―Best Buy‖ plans ranging in 

costs up to $6.5 Billion (October 2009 Price Levels). The most efficient plans are called Best 

Buys. They provide the greatest increase in output at the lowest average cost. Best Buys have 

the lowest incremental costs per unit of output. A summary of the costs and benefits associated 

with the plans generated in IWR-PLAN is provided in Table 2-10 of this Feasibility Report. 

Three Best Buy plans generated using IWR-PLAN software, along with the No Action plan, were 

selected for the final array. Best Buy plans #2, #7, and #10 (Plans B, C, and D, respectively) 

were chosen based on cost effective increments, contribution to addressing the study authority, 

and achieving planning objectives. These plans represent a wide range of costs and outputs. 

Plan B includes 10,287 acres of brackish marsh restoration and nourishment on the East 

Orleans Landbridge and the Bayou Terre aux Boeufs area. 9,343 acres of intermediate marsh in 

South Lake Borgne and along the MRGO would be restored as part of Plan B. Cypress swamp 

restoration and nourishment in the Central Wetlands (10,318 acres) are included in Plan B. 

Coastal ridge habitat restoration along Bayou La Loutre is also a component of Plan B (54 

acres). Along the MRGO, Plan B includes approximately 32.5 miles of bank protection and 548 

acres of marsh restoration. Plan B does not include any shoreline protection features along 

Lakes Borgne or Pontchartrain, oyster reef restoration, or restoration features in the Biloxi 

Marsh. Further analysis of the Violet, Louisiana Freshwater Diversion under WRDA 2007 

Section 3083 is also included in Plan B. 

Plan C includes all of the measures in Plan B and adds 22,224 acres of brackish marsh 

restoration and nourishment on the East Orleans Landbridge, Bayou Terre aux Boeufs, 

Hopedale and the Biloxi Marsh. Plan C also includes the restoration and nourishment of 3,281 

acres of imperiled fresh marsh in the Central Wetlands and 280 acres of intermediate marsh at 

the confluence of the MRGO and GIWW. Restoration of globally scare oyster reef habitat is 

proposed for 5.8 miles of the Biloxi Marsh shoreline between Point Eloi and the mouth of Bayou 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report Summary 

S-19 June 2012 

La Loutre as part of Plan C. Approximately 41 miles of shoreline protection features included in 

Plan C fill in the gaps between existing and planned projects, creating a complete plan for the 

protection of the East Orleans Landbridge and the Lake Borgne shoreline. 

Plan D incorporates all of the measures in Plan C and adds 12.8 miles of shoreline protection in 

the Biloxi Marsh and an SAV restoration measure in Lake Pontchartrain. 

Plan B was chosen for further consideration because it was the least costly Best Buy Plan. Plan 

B does not achieve all of the goals and objectives of the study, but includes some restoration 

measures for all of the targeted habitat types. Plan B would restore or protect 9,518 acres of 

fresh and intermediate marsh, 10,253 acres of brackish marsh, and 10,431 acres of cypress 

swamp. Plan B does not meet the target acre objectives for brackish marsh. Additionally, 10,456 

acres of brackish marsh would be converted to another habitat type that would not be restored 

elsewhere in the study area. Therefore, it did not meet the objective to add to the total amount 

of each habitat type in the study area. Plan B has no features in the Biloxi Marsh and only 

includes two features on the East Orleans Landbridge: therefore, Plan B does not fully address 

the objective to restore and protect critical landscape features for storm surge reduction. 

Plan C is the first Best Buy Plan that meets all of the objectives, including reasonably 

maximizing restoration and protection of the Biloxi Marsh and East Orleans Landbridge. Plan C 

was selected for further evaluation in the final array of alternatives because it appeared to be a 

complete plan for the Lake Borgne ecosystem and the areas affected by the MRGO. 

Plan D includes additional restoration measures in the Biloxi Marsh and East Orleans 

Landbridge. Because of these additions, Plan D improves upon Plan C by further protecting 

these critical landscape features, and better meets the storm surge objective. Plan D was 

included for further evaluation because it was the first Best Buy after Plan C to include more 

measures to protect both of these features. Table S-3 provides a summary of each plan. 

Table S-3. Final Array of Alternatives 

Plan

Estimated

Construction Cost1

Measure 

AAHUs2

Plan

AAHUs3 Acres Restored4

A $0 0 0 0

5

B $1.7 B ($67 M annual) 6,008 13,608 30,250

C $2.9 B ($124 M annual) 10,324 17,575658,861

D $3.1 B ($130 M annual) 10,399 17,116 59,823

Notes: 1. Based on preliminary costs in October 2009 Price Levels. Does not include real estate, OMRR&R, or adaptive 

management costs. 

2. The AAHUs presented in this column are the total AAHUs of all measures in the plan added together and does not 

consider interactions between restoration features, except for areas influenced by the freshwater diversion. The influence of 

the authorized Violet, Louisiana Freshwater Diversion was considered in the calculation of all benefits in this table. 

3. The AAHUs in this column are for the entire plan, and does consider synergies. 

4. The acres in this column are the total acres restored, nourished, and protected by the plan. 

5. The table shows only the costs and benefits associated with this plan. Therefore, all values are zero for the no-action plan. 

6. This number is reflective of the initial WVAs that were performed for the project in the plan formulation phase. WVAs were 

revised for the FIP based on a revised WVA methodology. In this final plan analysis, the Violet, Louisiana Freshwater 

Diversion was assumed operational in 2027. The total AAHUs for Plan C considering synergies is now 37,980 because the 

revised methodology considers the value of existing habitat, significantly increasing total benefits. 

The historic rate of sea level rise was selected for primary display of ecological benefits in this table because this rate is 

supported by data.
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report Summary 

S-20 June 2012 

S.10 COMPARISON OF ALTERNATIVES 

Alternative plans were compared against each other, with emphasis on the outputs and effects 

(beneficial and adverse) with respect to study goals and objectives and NER benefits and costs. 

Table S-4 provides a summary of how each alternative plan meets the study objectives. 

Plans A and B were not selected because they do not fully achieve all of the study objectives 

and would not comply with the Congressional mandate in WRDA 2007, Section 7013. Plan C is 

the FIP because it was determined to be the lowest cost plan that fully achieves all of the 

planning objectives and provides a complete plan to restore the Lake Borgne ecosystem. Key 

features and processes would be restored by Plan C. Plan C provides significantly greater 

benefits at a relatively small increase in average costs, and therefore better meets the 

effectiveness criteria than Plan B. Plan D would provide more benefits to the ecosystem than 

Plan C; however, in this evaluation, the additional benefits do not justify the increased cost. Plan 

D is a cost effective means of achieving the objectives of the study, but due to increased 

incremental costs compared to Plan C, it is not the most efficient plan. 

Table S-4. Comparison of the Alternative Plans and Plan Objectives 

Objective Plan A Plan B Plan C Plan D

1. Salinity Target No Yes Yes Yes

2. Cypress 

(Minimum 9,500 acres) No Yes Yes Yes

3. Fresh/Intermediate 

(Minimum 6,800 acres) No Yes Yes Yes

4. Brackish 

(Minimum 18,100 acres) No No Yes Yes

5. Various Marsh types lost from 

increased tides and salinity(Minimum 

3,900 acres)

No No Yes Yes

7. Ridge Habitat No Yes Yes Yes

8. Landscape Features for

Surge Reduction a No Yes 5,100 acres

Yes

20,234 acres

Yes

21,165 acres

a Landscape features for surge reduction include acres restored, nourished or protected on the East 

Orleans Landbridge and the Biloxi Marsh. 

Risks and Uncertainty 

There are significant risks and uncertainties associated with all of the plans. The greatest risks 

to restoration are damage from tropical storms, increased sea level rise, and climate change. A 

single storm event could destroy restored wetlands, significantly reducing or eliminating 

benefits. Increased sea level rise would convert emergent wetlands to shallow open water, and 

shallow open water to deeper water habitat. This conversion would reduce the effectiveness of 

restoration plans. Extreme changes in climate could result in conditions that cannot support the 

types of habitat restored, reducing the effectiveness of the restoration plan. 

Large uncertainties affect future conditions in the study area, including: climate change; sea 

level rise rates; subsidence rates; timing of tropical storm events; changes in frequency and 

intensity of tropical storm events; and/or changes in drought conditions. All of these factors 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report Summary 

S-21 June 2012 

could contribute to accelerated degradation in the study area, changing forecast conditions and 

diminishing the effectiveness of restoration plans. 

Some features of the plan are more susceptible to these risks and uncertainties. Management 

measures were assessed for each of the following four sustainability factors: 

1. Elevation – Features at higher elevations are more sustainable under relative sea level 

rise, e.g. ridges, than features at marsh elevation. 

2. Freshwater influence – Features that are influenced by rivers or river diversions have a 

sustainable source of freshwater and sediment to nourish them and aid in accretion. 

3. Wave energy – Features that are protected from wave energy (e.g. interior marsh) are 

more sustainable than features subjected to high wave energy. 

4. Natural features – Features that are natural, living features of the ecosystem such as 

marsh are more sustainable than hard structures such as rock that subside more quickly 

and cannot sustain themselves and therefore require more O&M. 

The most sustainable features are the freshwater diversion, cypress swamp restoration, and 

ridge habitat restoration. Shoreline protection features are less sustainable than other features, 

but are considered critical to address systemic erosion. These features protect the marsh from 

wave energy, and increase the sustainability of the marsh by allowing natural vegetative 

shoreline stabilization to occur. 

The timing and availability of financial resources is a major uncertainty that must be considered. 

If the plan is not implemented in the near future, the problems in the study area will continue to 

degrade conditions. The impact of the uncertainties associated with the future condition of the 

study area could increase restoration costs, decrease restoration benefits, or both. These 

uncertainties are increased because a non-Federal sponsor has not been identified. 

The FIP has a phased implementation schedule to reduce risk. With phased implementation, 

costs are expended periodically, rather than all at once, which reduces risk to the monetary 

investment. Phased implementation also provides the opportunity to adjust project design and 

construction from lessons learned from projects built in the earlier phases. 

The selection of the FIP represents a tradeoff of environmental benefits and monetary costs. 

Plan B is the least costly alternative in the final array. However, Plan B only partially addresses 

the study objectives. Additional restoration features requiring additional costs are needed to 

meet the study objectives. Plan D is a more effective plan than Plan C, because it better 

addresses study area problems and opportunities. However, the additional benefits provided by 

Plan D do not justify the additional cost. 

The adaptive management plan for the FIP addresses the potential impacts of increased sea 

level rise rates. The implementation plan provides opportunities for adaptive management 

through phased construction. 

The long-term impacts of the Deepwater Horizon oil spill on coastal Louisiana are uncertain at 

this time. This spill has impacted USACE water resources projects and studies in the Louisiana 

coastal area. Potential impacts to this study include factors such as changes to existing or 

baseline conditions, as well as changes to Future Without Project (FWOP) and Future With 

Project (FWP) conditions. The USACE will continue to monitor and closely coordinate with other 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report Summary 

S-22 June 2012 

Federal and state resource agencies and local sponsors in determining how to best address 

potential problems associated with the oil spill that may adversely impact projects and studies. 

This may include revisions to proposed actions as well as supplemental environmental analysis 

and documentation for specific projects and studies. 

S.11 SYSTEMS / WATERSHED CONTEXT 

The overarching principle adopted for this study (based on the LACPR technical report) is that 

sustaining the integrity of the estuarine environments in coastal Louisiana, including various 

landscape features that make up those environments, is critical to the ecological health, social 

and economic welfare of the region. 

System-wide problems and opportunities were used to identify and define more geographically 

specific problems and opportunities throughout the study area. The alternative plans were 

formulated to address systemic problems in the ecosystem, as well as specific problems in each 

subunit. The FIP includes multiple types of management measures to address factors 

contributing to ecosystem degradation. Public and agency coordination undertaken for the study 

has assisted in the development of a system based plan that complements other private, local 

state and federal restoration activities in the study area. 

The systems-based planning approach for the study supports the strategic approach described 

in the Louisiana-Mississippi Gulf Coast Ecosystem Restoration Working Group Roadmap for 

Restoring Ecosystem Resiliency and Sustainability. Specifically, the planning process 

recognizes the following key points of the strategic approach: 

 Enhancing essential coastal processes and the ecological services they provide. 

 Incorporating a multiple lines of defense strategy. 

 Safeguarding the region‘s rich cultural history and economic resources. 

 Addressing the potential impacts of accelerated sea level rise and subsidence as a 

strategy to protect communities, infrastructure, and to restore ecosystems and the 

services they provide. 

Representatives of Federal and State agencies were members of the Project Delivery Team 

(PDT). Agencies are also involved through the NEPA process, with some agencies serving as 

official cooperating agencies and others with official coordination and consultation roles. 

Cooperating Agencies (as defined under 40 CFR 1501.6) include: U.S. Department of the 

Interior – U.S. Fish and Wildlife Service (USFWS); U.S. Department of Commerce – National 

Oceanic and Atmospheric Administration – National Marine Fisheries Service (NMFS); U.S. 

Department of Agriculture – Natural Resources Conservation Service (NRCS); U.S. 

Environmental Protection Agency (EPA) and the Bureau of Ocean Energy Management, 

Regulation and Enforcement (BOE), formerly Minerals Management Service (MMS). Other 

participating agencies include the Louisiana Department of Environmental Quality (LDEQ), 

Louisiana Department of Wildlife and Fisheries (LDWF), the Louisiana Department of Natural 

Resources (LDNR), and the Mississippi Department of Marine Resources (MDMR). 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report Summary 

S-23 June 2012 

Figure S-4. Systems Context 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report Summary 

S-24 June 2012 

S.12 FEDERALLY IDENTIFIED PLAN 

Plan C was chosen as the FIP because it is the lowest cost alternative that meets all of the 

study objectives and provides a complete plan to restore the Lake Borgne ecosystem. The 

National Ecosystem Restoration account is best achieved by Plan C, because it meets all of the 

study objectives, reasonably maximizes benefits for the associated costs, includes key 

restoration features to restore and sustain the form and function of the Lake Borgne ecosystem, 

and fully addresses the Congressional mandate of WRDA 2007 Section 7013. 

Plan C is a complete plan for the Lake Borgne ecosystem because it protects and restores the 

portions of the Lake Borgne ecosystem that are not addressed by existing and authorized 

restoration projects. Existing and authorized shoreline protection projects along the shores of 

Lake Borgne do not comprehensively address erosion in the lake. Plan C would provide 

protection in the areas in between existing and authorized projects to stabilize the entire shore 

of Lake Borgne. Marsh restoration features included in Plan C would work synergistically with 

existing and authorized projects to restore the structure of the Lake Borgne ecosystem. 

The restoration of historic salinity conditions is a key system driver. The Violet, Louisiana 

Freshwater Diversion, as authorized for design and implementation in WRDA 2007 Section 

3083, would fully restore salinity conditions, mimic natural processes, and enhance the 

sustainability of the system through the input of freshwater, nutrients and sediment. Full 

restoration of historic habitat types in the area is dependent upon salinity conditions. Plan C 

addresses salinity impacts of the MRGO by recommending further analysis of the Violet, 

Louisiana Freshwater Diversion under WRDA 2007 Section 3083. 

Plan C is illustrated in Figures S-5 and S-6.

Approximately 11,222 acres of the restoration and protection features would be located in the 

East Orleans Landbridge/Pearl River area and approximately 9,012 acres of restoration would 

be located in the Biloxi Marsh, which have been determined to be critical landscape features 

with respect to storm surge. Additionally, the cypress swamp and ridge restoration features 

would include forested habitats, having some storm surge damage risk reduction benefits. 

The plan would restore technically significant habitat, such as 3,281 acres of imperiled fresh 

marsh in the Central Wetlands, 10,318 acres of ecologically important cypress forest, and 54 

acres of rare coastal ridge habitat. The plan would restore and nourish 12,797 acres of brackish 

marsh in the Hopedale and Bayou Terre aux Boeufs area south of the channel. In the Golden 

Triangle area, 4,317 acres of intermediate marsh would be restored on the Lake Borgne side of 

the IHNC Surge Barrier and 280 acres of significant urban marsh would be restored on the 

GIWW/MRGO side of the barrier. 

Implementation 

Following the identification of the FIP, a construction sequence was developed. Assumptions 

factoring into construction sequence include production rates for building rock projects, dredge 

equipment availability, land loss rates, alternating dredging cycles in the lobes of Lake Borgne. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report Summary 

S-25 June 2012 

The timing and availability of financial resources for implementation is a major uncertainty that 

must be considered given current Federal budgetary constraints. If the plan is not implemented 

in the near future, conditions will continue to degrade. The impact of the uncertainties 

associated with the future condition of the study area could increase restoration costs, decrease 

restoration benefits, or both. The uncertainties associated with implementation are increased 

because a non-Federal sponsor has not been identified. 

Funding assumptions, as detailed in the Engineering Appendix, were required for planning 

purposes and to develop costs and benefits for the plan. Construction sequencing assumed 

optimal funding appropriations and an aggressive schedule to complete implementation as soon 

as realistically possible. Given the considerable need for the plan, Federal interest, significance 

of resources, and the conditional authorization for implementation, an aggressive 

implementation sequence was considered appropriate. However, current budgetary conditions 

and the lack of a non-Federal sponsor make it very likely that reality will differ from these 

optimal assumptions. Risk and uncertainties related to implementation have been assessed in 

the Cost Risk Analysis, as detailed in the Engineering Appendix. However, due to uncertainties 

associated with the timing and availability of funding for the plan, only features that are 

sustainable without the implementation of any other feature are recommended for construction 

at this time. 

Tiered Implementation Sequence 

Recommendations are divided into tiers by the level of uncertainty regarding conditions for ecological 

success and long-term sustainability including the need for additional study. 

 Tier 1 includes features that have been developed to a feasibility level of detail and are 

not dependent on a freshwater diversion. Tier 1 features are recommended for 

construction through the WRDA 2007 Section 7013 authority upon the identification of a 

non-Federal sponsor. 

 Tier 2 includes features with feasibility level detail that are dependent upon salinity 

conditions but may be sustainable without the implementation of a freshwater diversion. 

If future conditions and further analysis indicate that favorable conditions for ecological 

success and long term sustainability exist (as defined in the adaptive management 

plan1), then these projects may be constructed. Tier 2 features would be constructed 

through the WRDA 2007 Section 7013 authority upon the identification of a non-Federal 

sponsor. 

 Tier 3A includes further study of the Violet, Louisiana Freshwater Diversion under the 

WRDA 2007 Section 3083 authority. The non-Federal cost-share responsibilities for the 

Violet, Louisiana Freshwater Diversion would be consistent with the 75 percent/25 

percent Federal/non-Federal cost share identified in Section 3083 of WRDA 2007, 

together with such other items of cost-share responsibilities as may be identified in the 

Feasibility Report for the project, as approved by the decision of the Chief of Engineers. 

Presently, as identified in the 1984 Chief‘s Report for Mississippi and Louisiana 

Estuarine Areas Freshwater Diversion to Lake Pontchartrain and Mississippi Sound 

Feasibility Study, the 25 percent non-Federal share of the cost of the design and 

implementation of the Violet, Louisiana Freshwater Diversion project is allocated 80 

percent to the State of Louisiana and 20 percent to the State of Mississippi. It is not 

anticipated that this allocation will change as a result of completing the feasibility study 

 

1

 Average annual salinity: fresh marsh: <1.1 parts per thousand (ppt); intermediate marsh: <4.1 ppt; brackish marsh: <8.3 ppt, and swamp <4.0. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report Summary 

S-26 June 2012 

for the project; however, if it does, the change in allocation will be addressed in the 

study, as approved by the decision of the Chief of Engineers.

 Tier 3B includes any features that are dependent on freshwater diversion, and features 

in Tier 2 that future conditions and further analyses indicate are not sustainable. 

Subsequent to the completion of Tier 3A, Tier 3B features would be constructed through 

the WRDA 2007 Section 7013 authority upon the identification of a non-Federal sponsor. 

S.13 EXPECTED PROJECT PERFORMANCE 

The implementation of the plan would improve the health of marsh vegetation through structural 

restoration projects. Healthier vegetation is more resilient and would improve air, water, and soil 

quality. The implementation of Plan C would produce a healthier, more sustainable Lake Borgne 

ecosystem and address the impacts of the MRGO. 

S.13.1 Project Costs 

The Engineering Appendix provides the detailed preliminary design costs for all measures and the 

summary cost estimates for the final array of alternatives considered in detail - Alternatives B, C, and D. 

These cost analyses are deemed adequate for making a federal interest determination. Further, these 

estimates allow for the use of the CE/ICA optimization comparison and selection of a federally identified 

plan in accordance with Corps Ecosystem Restoration policy. The Mii cost estimate and narrative 

summary is provided in the Engineering Appendix. This appendix also provides the scheduled 

construction costs for the FIP. 

Based on October 2011 Price Levels, the Project First Cost of the FIP is estimated at $2.9 

billion. The Project First Cost of Tiers 1 and 2 is estimated at $1.3 billion and $325 million, 

respectively. The Project First Cost of the Monitoring and Adaptive Management Plan (MAMP) 

is $190 million, including costs for potential adaptive management actions. The Project First 

Cost of the MAMP for Tiers 1 and 2 are $104 million and $46 million, respectively. The 

operation, maintenance, repair, replacement, and rehabilitation (OMRR&R) costs for the FIP is 

$427 million. The OMRR&R costs for plan features in Tiers 1 and 2 are estimated at $210 and 

$18 million, respectively. 

Table S-5. Project First Costs (October 2011 Price Levels)

Ecosystem Restoration Recreation Features Total

Project First Costs ($FY 2011) $2,879,704,000 $4,443,000 $2,884,147,000
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report Summary 

S-27 June 2012 

Figure S-5. Alternative C, Federally Identified Plan 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report Summary 

S-28 June 2012 

Figure S-6. Alternative C, Federally Identified Plan – Perspective View 
1-1 June 2012 

1 INTRODUCTION AND BACKGROUND 

1.1 STUDY PURPOSE AND SCOPE

The Mississippi River Gulf Outlet (MRGO) Ecosystem Restoration Plan Feasibility Study is a 

supplement to the June 2008 MRGO Deep-Draft De-Authorization Report. It is intended to fully 

meet the requirements of the Water Resources Development Act (WRDA) of 2007 Section 7013 

(Public Law [PL] 110-114). This feasibility study will result in a Report of the Chief of Engineers 

containing a recommended MRGO Ecosystem Restoration Plan. The plan has been 

conditionally authorized for construction by WRDA 2007 Section 7013. The Plan will address 

systematic ecosystem restoration and protection of the Lake Borgne ecosystem and areas 

affected by the MRGO navigation channel, and will include considerations of measures to 

reduce or prevent damage from storm surge. The study will integrate the findings of ongoing 

comprehensive restoration planning efforts for the study area, including the Louisiana Coastal 

Protection and Restoration (LACPR) Final Technical Report, the Louisiana Coastal Area (LCA) 

Program, and Louisiana‘s 2007 Comprehensive Master Plan for a Sustainable Coast. 

The study purpose is to develop alternative plans to restore natural features and processes in 

the Lake Borgne ecosystem and areas affected by the former navigation channel. Construction 

recommendations will be developed in concert with large-scale comprehensive ecosystem 

restoration plans for the region. As noted in the Louisiana-Mississippi Gulf Coast Ecosystem 

Restoration Working Group Roadmap for Restoring Ecosystem Resiliency and Sustainability, 

the MRGO Ecosystem Restoration Plan will not necessarily provide comprehensive ecosystem 

restoration for the entire study area. 

If the Assistant Secretary of the Army, Civil Works (ASA [CW]) determines that the 

recommendations of the MRGO Ecosystem Restoration Plan are cost-effective, environmentally 

acceptable, and technically feasible, no further Congressional authorization is needed. 

However, the execution of the implementation phase is subject to additional funding 

appropriations. Cost sharing is consistent with section 103(c) of WRDA 1986 (33 U.S.C. 

2213(c)). 

1.2 STUDY AND PROJECT AUTHORITY 

In 2006, after Hurricane Katrina, Congress provided $75,000,000 for operation and 

maintenance of the MRGO channel (as authorized at that time) in the Department of Defense 

Emergency Supplemental Appropriations to Address Hurricanes in the Gulf of Mexico and 

Pandemic Influenza Act, 2006 (PL 109-148). 

In 2006, the Congress directed the Secretary of the Army, acting through the Chief of 

Engineers, to develop a plan for deauthorization of deep-draft navigation on the MRGO in the 

Emergency Supplemental Appropriations Act for Defense, the Global War on Terror, and 

Hurricane Recovery, 2006 (PL 109-234). PL 109-234 also modified PL 109-148, to clarify that 

the $75,000,000 provided in PL 109-148 was to be used for ―the repair, construction or provision 

of measures or structures necessary to protect, restore or increase wetlands, to prevent 

saltwater intrusion or storm surge.‖
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 1: Introduction and Background 

1-2 June 2012 

The requirements for the deauthorization plan in PL 109-234 were addressed in the MRGO 

Deep-Draft De-Authorization Study that was submitted to the Congress on June 5, 2008, by 

providing a comprehensive plan, at full Federal expense, to deauthorize deep draft navigation 

on the MRGO from the Gulf of Mexico to the Gulf Intracoastal Waterway (GIWW). At the time 

that report was undergoing State and Agency review, WRDA 2007 became law, expanding the 

scope of the MRGO Deep Draft De-authorization Study to include ecosystem restoration. The 

MRGO Deep Draft De-authorization Study preliminarily addresses the requirements of WRDA 

2007; however, in order to continue processing the MRGO Deep Draft De-authorization Study, 

U.S. Army Corps of Engineers (USACE) leadership decided to develop a supplemental report to 

completely address the requirements of WRDA 2007. 

WRDA 2007 Section 7013, the authority for this study, is provided below: 

SEC. 7013. MISSISSIPPI RIVER-GULF OUTLET. 

(a) DEAUTHORIZATION.- 

(3) CLOSURE AND RESTORATION PLAN.- 

(A) IN GENERAL.-Not later than 180 days after the date of enactment of this Act, 

the Secretary shall submit to the Committee on Environment and Public Works of 

the Senate and the Committee on Transportation and Infrastructure of the House 

of Representatives a final report on the deauthorization of the Mississippi RiverGulf outlet, as described under the heading ''INVESTIGATIONS'' under chapter 3 

of title II of the Emergency Supplemental Appropriations Act for Defense, the 

Global War on Terror, and Hurricane Recovery, 2006 (120 Stat. 453). 

(B) INCLUSIONS.-At a minimum, the report under subparagraph (A) shall 

include- 

(i) a plan to physically modify the Mississippi River-Gulf Outlet and restore the 

areas affected by the navigation channel; 

(ii) a plan to restore natural features of the ecosystem that will reduce or prevent 

damage from storm surge; 

(iii) a plan to prevent the intrusion of saltwater into the waterway; 

(iv) efforts to integrate the recommendations of the report with the program 

authorized under section 7003 and the analysis and design authorized by title I of 

the Energy and Water Development Appropriations Act, 2006 (119 Stat. 2247); 

and 

(v) consideration of- 

(I) use of native vegetation; and 

(II) diversions of fresh water to restore the Lake Borgne ecosystem. 

(4) CONSTRUCTION.-The Secretary shall carry out a plan to close the 

Mississippi River-Gulf Outlet and restore and protect the ecosystem substantially 

in accordance with the plan required under paragraph (3), if the Secretary 

determines that the project is cost-effective, environmentally acceptable, and 

technically feasible. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 1: Introduction and Background 

1-3 June 2012 

Section 7003 of WRDA 2007, which is referenced in Section 7013(a)(3)(B)(iv) above, refers to 

the LCA Program. Title I of the Energy and Water Development Appropriations Act, 2006 (119 

Stat. 2247) refers to the LACPR Final Technical Report. Both are described in Section 1.5. The 

MRGO LCA Near-Term Project described in WRDA 2007 Section 7006 (c)(1)(A) is also 

addressed in this study. 

WRDA 2007 Section 7012 (b) states that the activities described in Section 7013 will be carried 

out consistent with the cost-share requirements in PL 109-234. Therefore, the MRGO 

Ecosystem Restoration Plan Feasibility Study is being conducted at full federal expense. A 

portion of the $75 million appropriated in PL 109-148 is being used to fund the study. 

The study is 100% Federally funded. After extensive discussions with the State of Louisiana, a 

non-Federal sponsor has not been identified for implementation of the MRGO Ecosystem 

Restoration Plan authorized by Section 7013 of WRDA 2007. 

In accordance with Section 221 of Public Law 91-611, Flood Control Act of 1970, as amended 

(42 U.S.C. 1962d-5), and Section 103 of the WRDA 1986, as (33 USC 2213(c)), implementation 

of the MRGO Ecosystem Restoration Plan (Tiers 1, 2 and 3B) requires a non-Federal sponsor 

responsible for providing 35 percent of the costs assigned to ecosystem restoration; providing 

the lands, easements, rights-of-way, and dredged or excavated material disposal areas required 

for the plan, and performing all necessary relocations (LERRDs); and paying 100 percent of the 

costs of operation, maintenance, repair, rehabilitation, and replacement (OMRR&R). 

Implementation of recreation features requires a 50 percent non-Federal cost share. The value 

of LERRDs provided by the non-Federal sponsor would be credited toward the non-Federal 

share of the costs of implementing elements of the plan. 

The State of Louisiana disagrees with USACE over the cost-share requirements for 

implementation of the MRGO Ecosystem Restoration features of the plan (Tiers 1, 2 and 3B) 

and has expressed its unwillingness to participate in plan implementation unless it is undertaken 

at full (100%) federal cost. The USACE will continue to coordinate with the State of Louisiana to 

finalize the ecosystem restoration plan and to identify a non-Federal sponsor to cost share in 

implementation of the plan. 

The State of Mississippi, along with the State of Louisiana, has been actively involved in the 

development of the Violet, Louisiana Freshwater Diversion project preliminarily addressed in 

this report (Tier 3A). The non-Federal cost-share responsibilities for the Violet, Louisiana 

Freshwater Diversion would be consistent with the 75 percent/25 percent Federal/non-Federal 

cost share identified in Section 3083 of WRDA 2007, together with such other items of costshare responsibilities as may be identified in the Feasibility Report for the project, as approved 

by the decision of the Chief of Engineers. Presently, as identified in the 1984 Chief‘s Report for

Mississippi and Louisiana Estuarine Areas Freshwater Diversion to Lake Pontchartrain and 

Mississippi Sound Feasibility Study, the 25 percent non-Federal share of the cost of the design 

and implementation of the Violet, Louisiana Freshwater Diversion project is allocated 80 percent 

to the State of Louisiana and 20 percent to the State of Mississippi. It is not anticipated that this 

allocation will change as a result of completing the feasibility study for the project; however, if it 

does, the change in allocation will be addressed in the study, as approved by the decision of the 

Chief of Engineers.
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 1: Introduction and Background 

1-4 June 2012 

In a letter dated September 20, 2010 the Mississippi Department of Marine Resources (MDMR) 

declared its full support for the Violet, Louisiana Freshwater Diversion project and its 

understanding of its non-Federal cost sharing obligation. The State of Mississippi‘s letter also 

states its desire that the USACE, to the fullest extent possible, seek full Federal funding for the 

project. A letter of intent has not been received from the State of Louisiana regarding the Violet, 

Louisiana Freshwater Diversion project (Tier 3A); however, since this report recommends 

further study of that project under the authority of Section 3083 of WRDA 2007, such a letter of 

intent will not be required until such time as that study nears completion and decision by the 

Chief of Engineers. 

1.3 STUDY AREA 

The study area (Figure 1-1) includes portions of the Mississippi River Deltaic Plain in coastal 

southeast Louisiana and parts of coastal southwest Mississippi. It encompasses approximately 

3.86 million acres (6,023 square miles) of land and open water. 

In Mississippi, the study area includes the Western Mississippi Sound, its bordering wetlands, 

and Cat Island. The Lake Borgne ecosystem and areas that may have been affected by the 

construction, operation, and maintenance of the MRGO navigation channel are included in the 

study area. The MRGO channel may have affected salinity as far northwest as Lake Maurepas. 

To the east, the MRGO channel was dredged through open water between Breton and Grand 

Gossier Islands (segments of the lower Chandeleur Island chain). The MRGO channel affected 

portions of the Lake Borgne ecosystem to the north and potentially altered hydrology to the west 

as far as the Bayou Terre aux Boeufs ridge. 

Louisiana parishes in the study area include Ascension, Jefferson, Livingston, Orleans, 

Plaquemines, St. Bernard, St. Charles, St. James, St. John the Baptist, St. Tammany and 

Tangipahoa. Mississippi counties in the study area include Hancock and Harrison. 

Lake Borgne is hydrologically linked to Lake Pontchartrain through tidal passes at The Rigolets, 

Chef Menteur Pass, and the Inner Harbor Navigation Canal (IHNC). The Lake Borgne 

ecosystem is influenced by the Pearl River to the north and is hydrologically connected to areas 

located as far south as Bayou Terre aux Boeufs. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 1: Introduction and Background 

1-5 June 2012 

Figure 1-1. Study Area
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 1: Introduction and Background 

1-6 June 2012 

1.4 MRGO NAVIGATION CHANNEL 

1.4.1 Authorization, Deauthorization, and Channel Closure 

Congress authorized the MRGO in 1956 as a Federal navigation channel to provide a short 

route between the Port of New Orleans and the Gulf of Mexico. The MRGO was authorized as a 

36-foot-deep, 500-foot-bottom-width waterway (38 feet deep, 600 feet wide at the Gulf of 

Mexico entrance) extending from the IHNC to the 38-foot depth contour in the Gulf of Mexico. 

Channel construction began in 1958 and the channel was completed in 1968. 

In August 2005, Hurricane Katrina shoaled the MRGO channel limiting its depth to 22 feet and 

restricting deep-draft vessel access. Rather than continue funding operation and maintenance, 

in June 2006, Congress requested a plan to deauthorize of the MRGO (see PL 109-234). 

The USACE submitted an interim report in December 2006 highlighting a plan to close the 

MRGO from the GIWW to the Gulf of Mexico. In January 2008, the Chief of Engineers signed a 

report recommending deauthorization of the channel, construction of a closure structure across 

the channel at Bayou La Loutre, and development of a supplemental report to provide an 

ecosystem restoration plan for the areas affected by the MRGO. On June 5, 2008, the 

ASA(CW) forwarded the Final MRGO Deep-Draft De-authorization Report to Congress, 

deauthorizing the MRGO federal navigation project from the GIWW to the Gulf of Mexico. 

Construction of a rock closure structure across the MRGO near the Bayou La Loutre ridge in St. 

Bernard Parish, Louisiana, was completed on July 9, 2009. 

Figure 1-2. Completed MRGO Rock Closure Structure 

1.5 MRGO ENVIRONMENTAL IMPACTS 

The cumulative effects of human and natural activities in the coastal area have severely 

degraded the Mississippi River‘s deltaic processes and shifted the Louisiana coastal area to a 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 1: Introduction and Background 

1-7 June 2012 

net land loss condition. Many studies have been conducted to identify the major contributing 

factors (e.g., Boesch et al. 1994; Turner 1997; Penland et al. 2000), and many studies agree 

that land loss and the degradation of the coastal ecosystem are the result of both natural and 

human induced factors, producing conditions where wetland vegetation can no longer survive 

and wetlands are lost. Establishing the relative contribution of natural and human-induced 

factors is difficult. In many cases, the changes in hydrologic and ecologic processes manifest 

gradually over decades and in large areas, while other effects occur over single days and 

impact relatively localized areas. 

Construction and operation of the MRGO contributed to wetland loss and damages to estuarine 

habitats in Louisiana from the outer tidal marshes in Breton Sound to the cypress forests and 

fresh mashes in the western reaches of the Lake Borgne basin. Loss of marsh and cypress 

swamp habitats has resulted in the decline of important ecological habitat as well as natural 

surge and wave buffers. Indirect and cumulative impacts associated with saltwater intrusion 

attributable to the MRGO occurred throughout the Lake Pontchartrain Basin. Due to the 

hydrologic connectivity of the system, the MRGO contributed to habitat changes and loss from 

Lake Maurepas to the north, Bayou Terre aux Bouefs to the west, Mississippi Sound to the east, 

and the outer reaches of Breton and Chandeleur Sounds to the south. 

The direct and indirect habitat impacts of the construction and operation of the MRGO between 

1956 and 1990 were estimated in Habitat Impacts of the Construction of the MRGO (USACE 

1999). MRGO channel construction, including the dredging of the canal and placement of 

dredged spoil, resulted in the conversion of 19,400 acres of wetlands and 4,750 acres of 

shallow open water to deep open water or spoil. 

Other contributing factors of land loss, such as subsidence, complicate the calculation of MRGO 

indirect impacts. The methodology for estimating indirect impacts utilized habitat data from the 

Louisiana Department of Natural Resources (LDNR) for 1956 and 1990 (USACE 1999). 

Increased land loss due to the MRGO was estimated by calculating a baseline loss by mapping 

unit, which included all land loss factors (such as subsidence and sea level rise) as well as the 

MRGO, and then estimating what percentage of the baseline loss was caused by the navigation 

channel to develop a ―without MRGO‖ loss rate. The percentages were developed based on the 

condition of the area prior to channel construction, proximity to the direct effects of the channel, 

and the significance of saltwater intrusion to each area. This loss rate was applied to the acres 

present in 1956; and the resulting 1990 acres were compared to calculate the possible 

increased loss. Additional losses due to erosion along the MRGO between 1990 and 2008 were 

calculated by U.S. Geological Survey team members. The methodology used in the 1999 report 

was re-assessed and validated. The ―without MRGO‖ loss rates are estimates based on a 

professional assessment of various contributing factors. 

There are no new tools available to provide a more accurate picture of what the landscape 

would look like if the channel had never been built. These estimates, and the methodology used 

to develop them, were verified as the best available quantification of MRGO impacts. Table 1-1 

summarizes the direct and indirect impacts by habitat type. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 1: Introduction and Background 

1-8 June 2012 

Table 1-1. Direct and Indirect Habitat Impacts of the MRGO Navigation Channel 

Impacts from 1956 to 1990 as Documented

in Habitat Impacts of the Construction of the MRGO*

Habitat Type

Direct Impacts

(acres lost)

Indirect Impacts

(acres lost or converted)

Cypress swamp 1,510 8,000

Fresh/intermediate marsh 3,370 3,350

Brackish marsh 10,310 19,170

Saline marsh 4,210 N/A

Shallow open water converted to deep water or 

disposal

4,750 N/A

Additional marsh lost adjacent to the channel** 460 3,400

Total Impacts 24,610 Acres Lost 33,920 Acres Lost

or Converted

*Direct impacts are due to construction and erosion. Indirect impacts are due to salinity or hydrological changes 

from the MRGO. Habitat shifts were estimated using 1956-1990 habitat composition data from LDNR. 

**Direct impacts due to additional erosion between 1990 and 2008. Indirect impacts due to increased tides and 

salinity. 

Does not include deeper water aquatic habitat effects due to salinity increases or Lake Maurepas area to be 

restored by LCA projects. 

Other studies have attributed additional impacts to the MRGO. The Mister Go Must Go report 

estimates the total impact of the MRGO is 618,000 acres (Day et al. 2006). This estimate 

includes 488,400 acres of Lakes Pontchartrain and Borgne affected by salinity shifts. This also 

includes 64,000 acres of Lake Pontchartrain that exhibited seasonal hypoxic/anoxic conditions 

due to its hydrologic connection with the MRGO channel. The report cites Habitat Impacts of the 

Construction of the MRGO as the source for other impact figures (Day et al. 2006). 

Initial monitoring data indicate that the channel closure at Bayou La Loutre has significantly 

decreased salinity upstream of the closure (USGS 2009). Results of sampling conducted near 

the mouth of the IHNC in Lake Pontchartrain prior to and after closure in summer 2009 indicate 

a substantial reduction in differences between surface and bottom salinity and dissolved oxygen 

levels (personal communication, Dr. Michael A. Poirrier, UNO). Low dissolved oxygen (DO) 

levels (<4.0 milligrams per liter [mg/L]) have not been observed in Lake Pontchartrain since the 

construction of the closure. Water quality monitoring has been conducted in and around the 

channel following the construction of the closure, and areas of low DO have been occasionally 

observed in the MRGO southeast of the closure. Based on preliminary data, these occurrences 

appear to be seasonal and temporary. Because there is limited water quality data from the 

MRGO prior to the construction of the closure, it is unclear what, if any, impacts to DO in the 

channel are related to the closure. The closure at Bayou La Loutre and other authorized 

projects are anticipated to continue to address the impacts of the former navigation channel in 

Lakes Pontchartrain and Borgne with respect to hypoxia and salinity changes. Therefore, these 

acreages are not included in impact quantifications used to formulate restoration plans. 

Prior to construction of the MRGO, typical tidal flow within the Breton Sound area was reduced 

as it moved across the marsh inward toward Lake Borgne (USACE 2004). The MRGO was 

dredged through the Bayou La Loutre ridge, which provided a basin boundary limiting the flow of 

saline water from the Breton Sound area into Lake Borgne (Rounsefell 1964). Habitat changes 

in the study area are primarily related to saltwater intrusion, although other factors such as 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 1: Introduction and Background 

1-9 June 2012 

logging and the construction of impoundments contributed to these changes. The salinity 

changes based on pre- and post-channel water quality monitoring are documented in ―Salinity 

Changes in Pontchartrain Basin Estuary, Louisiana, Resulting from Mississippi River-Gulf Outlet 

Partial Closure with Width Reduction, Final Report‖ (Tate et al. 2002) (Figure 1-3). 

This study is a component of the larger coastal restoration efforts that will be required to ensure 

the resilience and sustainability of the coast. This study is specifically focused on restoration of 

historic habitat types in the areas affected by the MRGO channel and the Lake Borgne 

Ecosystem. Restoration objectives were developed using the quantities in Table 1-1 to achieve 

the overarching goals of the study and address the study authority. As discussed in detail in 

Section 2, it is not feasible to restore the study area to a historic state. Rather, this study intends 

to develop a plan to restore historic habitat types, processes, and conditions to the extent 

practicable to address systemic problems in the area. 

1.6 PRIOR STUDIES, REPORTS, AND EXISTING WATER PROJECTS

Information related to the MRGO study area has been accumulated over five decades. Planning 

for this study builds upon existing studies and plans. For example, study area problems and 

opportunities have been documented in numerous prior studies. Where conditions have 

changed or new information has become available, additional analyses have been performed to 

develop an ecosystem restoration plan based on sound science and engineering. The following 

comprehensive planning efforts for the Mississippi and Louisiana coastal areas provided a 

foundation for the development of the MRGO Ecosystem Restoration Plan. 

Coast 2050 (1998–1999). This conceptual restoration plan for the Louisiana coast incorporated 

public and scientific input through the Coastal Wetlands Planning, Protection and Restoration 

Act (CWPPRA) and other programs. The plan reflected a growing recognition that a more 

comprehensive approach to restoring coastal wetlands was needed. This plan informed the 

MRGO Ecosystem Plan Feasibility Study. 

Louisiana Coastal Area (LCA) Program (2000–present). The 2004 LCA feasibility study built 

on the Coast 2050 strategies, incorporating the best available science and technology, to 

develop a plan addressing the most critical coastal ecological needs. WRDA 2007 Section 

7006(c) authorized the construction and further study of specific projects in accordance with the 

January 2005 LCA Chief‘s Report. This plan proposed to construct rock breakwaters along the 

entire north bank of the MRGO and along important segments of the southern shoreline of Lake 

Borgne as a critical near-term need. In accordance with the implementation guidance for this 

study, the feasibility report and NEPA compliance document developed for the plan for 

ecosystem restoration authorized by Section 7013 will include recommendations regarding the 

project for MRGO environmental restoration referenced in Section 7006(c)(1)(A) of WRDA 

2007. Data from the LCA report was used in the MRGO study, and alternative plans were 

evaluated for consistency with the LCA plan. 

Louisiana Coastal Protection and Restoration (LACPR) Technical Report (2005–present). 

The LACPR report includes a coastwide analysis and design of a multiple lines of defense 

approach to ―Category 5‖ hurricane damage risk reduction. The report includes structural 

measures (e.g. levees), nonstructural measures (e.g. elevating homes) and coastal restoration 

measures (e.g. marsh creation). Data and restoration measures from the LACPR report were 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 1: Introduction and Background 

1-10 June 2012 

incorporated in the MRGO Ecosystem Restoration Plan Feasibility Study. Alternative plans 

developed for the MRGO study were evaluated for consistency with LACPR. 

Mississippi Coastal Improvements Program (MsCIP) Comprehensive Plan (2005–

present). Concurrent with LACPR, Congress authorized the MsCIP study to address hurricane 

and storm damage reduction and coastal restoration in coastal Mississippi. In January 2010, the 

Final MsCIP Report was transmitted to Congress. This plan provided data and potential 

restoration measures included in the MRGO study. Alternative plans developed for the MRGO 

study were evaluated for consistency with MsCIP. 

Integrated Ecosystem Restoration and Hurricane Protection: Louisiana’s Comprehensive 

Master Plan for a Sustainable Coast (2007 State Master Plan) (2005–present). The 

Louisiana Legislature, through Act 8 of the First Extraordinary Session of the 2005 Louisiana 

Legislature, established the Coastal Protection and Restoration Authority (CPRA) to develop, 

implement, make reports on, and provide oversight for a comprehensive coastal protection 

master plan and annual coastal protection plans. The MRGO Ecosystem Restoration Plan 

incorporated data and proposed restoration measures from the Master Plan. Consistency with 

the 2007 State Master Plan was evaluated as part of the planning process. 

In addition to the comprehensive planning efforts described above, Table 1-2 lists other prior 

Federal and state efforts and notes how each is relevant to the MRGO study. 

Non-governmental organizations 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 preservation 

focused and did not appreciably influence plan formulation.
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 1: Introduction and Background 

1-11 June 2012 

Figure 1-3. Salinity Impacts of the MRGO
1-12 June 2012 

Table 1-2. Prior Studies, Reports, Programs, Projects, and Laws

Topic Prior Reports, Studies, Programs, Projects, and Laws

Data

Consistency

Measures 

included in the 

Initial Array

Future Without 

Project

Former MRGO Navigation Channel and

Projects in the Vicinity of Lake Borgne

Final Environmental Impact Statement (FEIS) for the Mississippi River-Gulf Outlet (MRGO), Louisiana, and Lake Borgne –

Wetland Creation and Shoreline Protection Project, 2009 X X X X

Integrated Final Report to Congress and Legislative Environmental Impact Statement for the MRGO Deep-Draft Deauthorization Study, 2008 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 PL 109-148, as modified by Section 2304 Title II, Chapter 3 of PL 109-234, 2006 X X X

Ecological Review, Lake Borgne and MRGO Shoreline Protection, 2005 X X X X

MRGO Reevaluation Study, 2005 X

MRGO North Bank Foreshore Protection Evaluation, 1996 X X X

MRGO St. Bernard Parish, Louisiana, Reconnaissance Report, 1988 X

MRGO, Michoud Canal, Louisiana Project, 1968 X X X

Mississippi River Outlets, Venice, Louisiana, 1968 X X

Mississippi River Gulf Outlet, September 1956 X

Bayous La Loutre, St. Malo and Yscloskey, 1945 X X

LACPR Louisiana Coastal Protection and Restoration (LACPR) Final Technical Report, 2009 X X X

LA Master 

Plan Louisiana‘s Comprehensive Master Plan for a Sustainable Coast, 2007 X X X

MS Portion of 

the Study 

Area

Mississippi Coastal Improvements Program (MsCIP) Comprehensive Plan Report, 2009 X X X

MsCIP Interim Report Near-Term Projects, 2006 X X X

Coastal Wetlands Protection Act (Mississippi Code Section 49-27-1, 49-27-71), 2003 X

Wetlands Protection Act (Mississippi Code Section 49-27-5), 1992 X

Mississippi Sound and Adjacent Areas: Dredged Material Disposal Study, Feasibility Report, 1984 X

CIAP

Coastal Impact Assistance Program (CIAP) X X X

CIAP Projects Authorized for Construction or Under Construction X X X
Table 1-2 Prior Studies, Reports, Programs, Projects, and Laws 

1-13 June 2012 

Table 1-2. Prior Studies, Reports, Programs, Projects, and Laws

Topic Prior Reports, Studies, Programs, Projects, and Laws

Data

Consistency

Measures 

included in the 

Initial Array

Future Without 

Project

Louisiana 

Coastal Area 

(LCA)

LCA Near Term Projects Authorized in WRDA 2007:

1. Mississippi River Gulf Outlet (MRGO) environmental restoration features

2. Small diversion at Hope Canal (1,000 – 5,000 cfs)

3. Small diversion at Convent/Blind River (1,000 – 5,000 cfs)

4. Increase Amite River Diversion Canal influence by gapping banks

5. Medium diversion at White Ditch (5,001 – 15,000 cfs)

6. Modification of Caernarvon diversion

X X X

CWPPRA

The Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) Program X X X X

CWPPRA Projects with Approved Grants X X X

CWPPRA Violet Freshwater Distribution (Deauthorized September 11, 2006) X

CWPPRA Bayou Lamoque Diversion X X X

CWPPRA White Ditch Siphon X

CWPPRA Goose Point/Pointe Platte Marsh Creation X X

CWPPRA Fritchie Marsh Restoration X X

CWPPRA Lake Borgne Shoreline at Shell Beach and Bayou Dupre X X X

Violet

Diversion Violet, LA, (WRDA 2007) X X X

Bonnet

Carré

Bonnet Carré Diversion X X

Bonnet Carré Spillway X X

Gulf 

Intracoastal 

Waterway

Draft Environmental Assessment Maintenance Dredging and Disposal of Dredged Material Mississippi and Louisiana 

Portions of the Gulf Intracoastal Waterway Federally Authorized Navigation Project Hancock, Harrison and Jackson 

Counties, Mississippi and Coastal Louisiana, 2008

X X X

Gulf Intracoastal Waterway (GIWW), 1826 and other dates X X

Caernarvon Caernarvon Freshwater Diversion X X X

IHNC Lock Inner Harbor Navigation Canal Lock Replacement Project, 1956 X X X

MR&T Mississippi River and Tributaries (MR&T), 1928 X X
Table 1-2 Prior Studies, Reports, Programs, Projects, and Laws 

1-14 June 2012 

Table 1-2. Prior Studies, Reports, Programs, Projects, and Laws

Topic Prior Reports, Studies, Programs, Projects, and Laws

Data

Consistency

Measures 

included in the 

Initial Array

Future Without 

Project

Risk 

Reduction 

System

Greater New Orleans Hurricane and Storm Damage Risk Reduction System (HSDRRS)

X X X

Inner Harbor Navigation Canal (IHNC) Surge Barrier X X X

Individual Environmental Report #11, Improved Protection on the Inner Harbor Navigation Canal, Orleans and St. Bernard 

Parishes, Louisiana, 2008 X X X

Investigation of the Performance of the New Orleans Flood Protection Systems in Hurricane Katrina on August 29, 2005, 

Final Report, 2006 X X

Performance Evaluation of the New Orleans and Southeast Louisiana Hurricane Protection System, Draft Final Report of 

the Interagency Performance Evaluation Task Force (IPET), USACE, 2006 X X

Southeast Louisiana Urban Flood Control Project (SELA), 1996 X X X

Lake Pontchartrain and Vicinity, Louisiana, Hurricane Protection Project, 1965 X X X

Public Laws

Second Emergency Supplemental Appropriations Act to Meet the Immediate Needs Arising from the Consequences of 

Hurricane Katrina, 2005 (PL 109-062) X X X

Department of Defense, Emergency Supplemental Appropriations to Address Hurricanes in the Gulf of Mexico, and 

Pandemic Influenza Act, 2006 (PL 109-148) (Authorization for LACPR) X X X

Emergency Supplemental Appropriations Act for Defense, the Global War on Terror, and Hurricane Recovery, 2006 (PL

109-234) X X X

Other

Coast 2050 Report, 1999 X X

Other Environmental Assessments and Environmental Impact Statements X X X
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 1: Introduction and Background 

1-15 June 2012 

1.7 ENVIRONMENTAL OPERATING PRINCIPLES 

In 2002, the USACE reaffirmed its long-standing commitment to environmental conservation by 

formalizing a set of Environmental Operating Principles applicable to decision-making in all 

programs. The principles are consistent with NEPA; the Department of the Army‘s 

Environmental Strategy with its four pillars of prevention, compliance, restoration, and 

conservation; other environmental statutes and WRDA that govern USACE activities. The 

Environmental Operating Principles inform the plan formulation process and are integrated into 

all proposed program and project management processes. 

The Environmental Operating Principles are as follows: 

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. 

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 winwin solutions to the nation‘s problems that also protect and enhance the 

environment. 

Ecosystem sustainability and diversity have been integrated into the goals and objectives for the 

study and have guided the plan development, evaluation and selection processes. Target acres 

by habitat type, a salinity regime, and restoration of critical landscape features have been used 

as metrics for incorporating sustainability and habitat diversity into plan formulation. Sections 

2.5 through 2.10 detail the plan formulation, evaluation and selection processes, including 

discussions of the significance of a healthy, sustainable, and diverse ecosystem. 

Generally, consequences of restoration measures evaluated in this study are beneficial to both 

the natural and human environments. For example, improving aquatic habitat can have a 
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Final Feasibility Report 1: Introduction and Background 

1-16 June 2012 

positive impact to commercial fishing interests. In some instances, beneficial effects in the 

natural environment can result in adverse impacts to the human environment, and vice versa. In 

cases where an environmental benefit may have adverse effects to another environmental or 

human resource, the beneficial and adverse consequences have been carefully considered in 

the plan formulation process. 

Decisions and recommendations that may result from this study would be compliant with all 

applicable laws, regulations and policies. The potential adverse and beneficial impacts of any 

proposed actions would be evaluated with particular attention to the continued viability of the 

ecosystem and potential impacts to the health, safety and welfare of the public. 

This study has undertaken a proactive public involvement campaign, including an interactive 

website, technical workshops, regular stakeholder visits, focus group meetings, and targeted 

stakeholder forums. Active and responsive public involvement has informed the development of 

solutions to the problems this study seeks to address, and has facilitated the sharing and 

distribution of data and knowledge. The relationships that the study team has developed with 

non-governmental organizations (NGOs), local officials, community and special interest groups, 

the academic community and agency partners are intended to facilitate the consensus-building 

process. The public coordination for this study is discussed in Section 3.0. 

1.8 ENVIRONMENTAL PLANNING GUIDING PRINCIPLES 

Several of the guiding principles established in the LACPR Technical Report, Coastal 

Restoration Appendix applicable to this study area were adopted. The overarching principle 

adopted from the LACPR technical report is that sustaining the integrity of the estuarine 

environments in coastal Louisiana, including various landscape features that make up those 

environments is critical to the ecological health, social and economic welfare of the region. 

Model analysis conducted for the LACPR of storm surge levels and wave magnitudes 

demonstrate the value of coastal features to lowering storm risks (USACE 2009). While the 

models show benefits from additional marsh, island and landbridge habitat, the effects of 

allowing existing features to degrade are even more pronounced. 

Guiding principles include: 

 Relatively intact estuarine ecosystems are a key attribute in coastal Louisiana, and 

alternatives should seek to enhance the resilience and self-sustainability of the 

estuarine environments, including protection of existing high-quality estuaries. 

 Restoration of key processes and dynamics are critical to the long-term health of the 

ecosystem. 

 Riverine diversions must be carefully sited to maximize sediment retention within the 

coastal ecosystem and avoid sediment loss to the Gulf because of reduced 

Mississippi River sediment loads. Therefore, measures and alternatives must seek to 

maximize the combined benefits of diversions that seek to restore natural processes 

with mechanical marsh creation measures. 

 Additional sources of sediments should be sought where feasible; recognizing that 

such measures should not contribute to ecosystem degradation in the source area. 
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Final Feasibility Report 1: Introduction and Background 

1-17 June 2012 

 Measures should be combined synergistically to maximize possible cumulative 

benefits. Thus, the position of features within the landscape has a direct influence on 

the potential benefits derived. 

 Capacity to assess and quantify benefits and impacts from various measure 

combinations may be limited due to the state-of-the-science, uncertainty with future 

development, relative sea level rise and other factors. Flexibility is required in project 

design and implementation to permit adaptive management as conditions change 

and more is learned. 

 A concerted monitoring and adaptive management program should be a component 

of the restoration plan. 

1.9 ROADMAP FOR RESTORING ECOSYSTEM RESILIENCY AND 

SUSTAINIBILITY 

In October 2009, President Obama formed the Louisiana-Mississippi Gulf Coast Ecosystem 

Restoration Working Group, co-led by the White House Council on Environmental Quality 

(CEQ) and the Office of Management and Budget (OMB) and comprising senior-level officials 

from the National Oceanic and Atmospheric Administration (NOAA), the U.S. Environmental 

Protection Agency (EPA), and the Departments of the Army (USACE), Homeland Security, the 

Interior, and Transportation. The Working Group has developed a Roadmap for Restoring 

Ecosystem Resiliency and Sustainability in the Louisiana and Mississippi Coast. One of the 

findings of this roadmap is that ―bold and decisive action is needed now to curtail the rate of 

wetland loss and barrier island erosion in the area and to restore some of these lost features 

and ecosystem services.‖ 

The systems-based planning approach for this study is in accordance with the strategic 

approach described in the Louisiana-Mississippi Gulf Coast Ecosystem Restoration Working 

Group Roadmap for Restoring Ecosystem Resiliency and Sustainability. Specifically, the 

planning process was cognizant of the following key points of the strategic approach: 

 Enhancing essential coastal processes and the ecological services they provide. 

 Incorporating a multiple lines of defense strategy. 

 Safeguarding the region‘s rich cultural history and economic resources. 

 Addressing the potential impacts of accelerated sea level rise and subsidence as a 

strategy to protect communities, infrastructure, and to restore ecosystems and the 

services they provide. 
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2 PLAN FORMULATION 

The guidance for conducting Civil Works planning studies (ER 1105-2-100) requires the 

systematic formulation of alternative plans that contribute to the Federal objective. To ensure 

that sound decisions are made, the plan formulation process requires a systematic and 

repeatable approach. The Economic and Environmental Principles and Guidelines for Water 

and Related Land Implementation Studies (Principles and Guidelines) describe the USACE 

study process and requirements. 

Step 1 – Identify Problems and Opportunities. The first phase of the planning process 

defines study area problems and opportunities, as well as study goals, objectives, and 

constraints. Because this is an ecosystem restoration study, problems and opportunities are 

developed to address the Federal objective of National Ecosystem Restoration (NER). Goals, 

objectives, and constraints are developed to help solve the problems and achieve the 

opportunities within the confines of legislative authority, policies, and other restrictions. 

Step 2 – Inventory and Forecast Conditions. The second planning step consists of 

inventorying and forecasting study area resources. This inventory step accounts for the level or 

amount of a particular resource that currently exists within the study area, i.e., identification of 

existing conditions. This step also involves forecasting to predict what changes will occur to 

resources throughout the 50-year period of analysis, assuming no actions are taken to address 

the problems in the study area. Comparison of the existing and forecast conditions of the study 

area measures the problems resulting from the change in resources over time. Study area 

problems are quantified based on this predicted change in resources. This second step also 

results in the delineation of opportunities that fully or partially address the study area problems. 

An opportunity is a resource, action, or policy that, if acted upon, may alter the conditions 

related to an identified problem. 

Step 3 – Formulate Alternatives. The third step is to generate alternative solutions. Alternative 

plans are formulated across a range of potential scales to demonstrate the relative effectiveness 

of various approaches at varying scales. Alternatives are formulated in consideration of study 

area problems and opportunities, as well as study goals, objectives and constraints with 

consideration of four criteria: completeness, effectiveness, efficiency, and acceptability. 

1. Completeness is the extent to which a given alternative plan provides and accounts for 

all necessary investments or other actions to ensure the realization of the planned 

effects. 

2. Effectiveness is the extent to which an alternative plan alleviates the specified problems 

and achieves the specified opportunities. 

3. Efficiency is the extent to which an alternative plan is the most cost-effective means of 

alleviating the specified problems and realizing the specified opportunities, consistent 

with protecting the nation‘s environment. 

4. Acceptability is the workability and viability of the alternative plan with respect to 

acceptance by state and local entities and the public and compatibility with existing laws, 

regulations, and public policies. 
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Final Feasibility Report 2: Plan Formulation 

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Step 4 – Evaluate Alternatives. In the fourth step, alternative plans are evaluated for their 

potential results to address the specific study problems, needs, and objectives. The measure of 

output is expressed by the difference in amount or effect of a resource between the ―No-Action 

Alternative‖ conditions and those predicted to occur with each ―Action Alternative‖ in place. This 

difference is referred to as the benefits of the action alternative. This evaluation focuses on 

ecosystem benefits, which are measured in metrics that reflect the area, productivity, and value 

of restored or conserved habitats. 

Step 5 – Compare Alternatives. The planning process continues with the fifth step, 

comparison of alternative plans to each other utilizing the benefit outputs and costs of the 

alternatives. A relationship between costs and varying levels of ecosystem restoration outputs 

across a full range of scales is compared. 

Step 6 – Select a Plan. The sixth and final step in the process is selection of the plan that best 

meets the study objectives and the four criteria in the Principles and Guidelines: completeness, 

effectiveness, efficiency, and acceptability. Using the six-step planning process, the 

recommended plan is identified. 

The USACE Planning Manual (IWR Report 96-R-21) describes planning as a dynamic and 

iterative process, in which steps are repeated and may occur out of order. For instance, the 

identification of existing and future conditions contributes to the understanding of system-wide 

problems and opportunities. During every point in the process, previous steps may be revised 

and subsequent steps may be anticipated. This planning approach allows the process to 

progress based on the best information available at any given time. 

Figure 2-1. Planning Process 
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2.1 KEY PLANNING ASSUMPTIONS 

In formulating and evaluating alternatives, certain assumptions and/or simplifications were 

required. Table 2-1 provides a brief summary of the major assumptions and the scientific basis 

or rationale behind each assumption. Additional assumptions specific to plan formulation and 

evaluation are described in sections 2.6, 2.7, and 2.8, as well as the Environmental Impact 

Statement (EIS) and Engineering Appendix for this study. 

Table 2-1. Key Assumptions

Assumption Rationale for the Assumption

Study Area

The MsCIP effort and other planning efforts 

led by the USACE Mobile District will address 

vegetated habitat ecosystem restoration 

needs in the portions of the study area located 

in Mississippi. Except for diversions of 

freshwater, the MRGO ecosystem restoration 

study will not formulate measures for the 

purpose of ecosystem restoration in 

Mississippi.

The MsCIP Comprehensive Plan addressed 

ecosystem restoration needs in the Bay St. Louis 

and western Mississippi Sound areas, such as 

barrier island and submerged aquatic vegetation 

restoration. To avoid redundancy and ensure 

consistency with that plan, the MRGO ecosystem 

restoration plan will not re-evaluate those measures.

Plan Objectives

It is not a study objective or restoration target 

to restore the study area to a pre-MRGO 

hydrologic condition.

This condition cannot be achieved within the study 

constraints due to authorized navigation and risk 

reduction protection projects and other landscape 

changes.

The primary purpose of the plan is ecosystem 

restoration. Hurricane and storm damage risk 

reduction through the protection and 

restoration of natural features contributes to 

the need for the plan and is an authorized goal 

of the study. The reduction of damages will not 

be monetarily quantified. This portion of the 

study authority will be achieved through the 

restoration of habitat in areas identified as 

critical landscape features for storm surge 

reduction in scientific literature.

The WRDA implementation guidance dated 28 April 

2009 says, ―Alternative plans shall be formulated for 

the purpose of ecosystem restoration inclusive of 

the requirements set forth in Section 7013 of WRDA 

2007. Ecosystem restoration studies do not require 

the quantification of economic benefits. Benefits of 

coastal landscape features with respect to storm 

damage risk reduction are difficult to empirically 

quantify due to the complex interaction of dynamic 

variables.

Future Without Project Conditions

Restoration of the Lake Maurepas swamps is 

assumed to be part of the future without 

project conditions.

Swamp restoration in these areas is addressed 

through several authorized LCA/CWPPRA diversion 

projects.

Period of Analysis

For comparison of alternatives, the total period 

of analysis is from 2012 to 2065.

The period of analysis includes implementation plus 

50 years. The implementation phase is 2012 to 

2015 (begins with the first PED year; concludes with 

first construction completion year). The 50-year 

period begins with the first year of operation (first 

year when benefits would be realized) and is 2015 

to 2065. Consideration beyond the period of 

analysis is given to environmental factors. 
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Table 2-1. Key Assumptions

Assumption Rationale for the Assumption

Relationship to Violet, Louisiana Freshwater Diversion Authority

Section 3083 of WRDA 2007 authorizes the 

design and implementation of a diversion at or 

near Violet, Louisiana, which is located within 

the MRGO Ecosystem Restoration Plan study 

area. A freshwater diversion project at or near 

the Violet Canal will be analyzed as a 

component of the MRGO Ecosystem 

Restoration Plan. 

This study has identified that a freshwater diversion 

at or near Violet may be a key driver in the 

sustainability of the restoration of areas affected by 

the MRGO and the Lake Borgne ecosystem. 

Feasibility level investigations of the project 

authorized in WRDA 2007 Section 3083, will be 

included in this study, consistent with the 

Implementation Guidance for Section 7013 WRDA 

2007 dated 28 April 2009.

Minimum Restoration Target

The minimum restoration targets were 

developed to include direct and indirect habitat 

impacts of the former navigation channel by 

habitat type. Impacts include construction, 

operation, and maintenance of the MRGO 

through 2008. 

These targets were set to produce a plan that meets 

the requirements of the study authority and USACE 

requirements for completeness, effectiveness, 

efficiency, and acceptability. 

Measures

Maintenance will be performed on all plan 

features.

Periodic maintenance actions will be developed to 

sustain benefits over the period of analysis.

Marsh restoration areas will include vegetative 

plantings but marsh nourishment areas will 

not.

Marsh nourishment is performed using a thin layer 

of sediment slurry over existing marsh so it is 

assumed that the existing marsh vegetation will 

survive.

2.2 EXISTING CONDITIONS 

The long-term impacts of the Deepwater Horizon oil spill on coastal Louisiana are uncertain at 

this time. This spill may impact USACE water resources projects and studies within the 

Louisiana coastal area. Potential impacts include factors such as changes to existing or 

baseline conditions, as well as changes to Future Without Project (FWOP) and Future With 

Project (FWP) conditions. The USACE will continue to monitor and closely coordinate with other 

Federal and state resource agencies and local sponsors in determining how to best address 

potential problems associated with the oil spill that may adversely impact projects and studies. 

This may include revisions to proposed actions as well as supplemental environmental analysis 

and documentation for specific projects and studies. 

2.2.1 Coastal System Processes 

An estuary and its immediate catchment form a complex system of ecological, physical, 

chemical and social processes, which interact in a highly involved and, at times, dynamic 

fashion. The following sections summarize the key processes involved in this ecosystem. These 

are discussed in detail in the 2004 LCA report and Section 3.5 of the EIS. 
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2-5 June 2012 

The Deltaic Processes 

The Mississippi River Deltaic Plain and its associated wetlands and barrier shorelines are the 

product of the accumulation of sediments deposited by the river and its distributaries during the 

past 7,000 years. Regular shifts in the river‘s course have resulted in four ancestral and two 

active delta lobes, which accumulated as overlapping, stacked sequences of unconsolidated 

sands and muds. As each delta lobe was abandoned by the river, its main source of sediment, 

the deltas experienced erosion and degradation due to compaction of loose sediment, rise in 

relative sea level, and storms. Marine coastal processes eroded and reworked the seaward 

margins of the deltas forming sandy headlands and barrier beaches. As erosion and 

degradation continued, segmented low-relief barrier headlands formed and eventually were 

separated from the mainland by shallow bays and lagoons forming barrier islands (USACE 

2009). 

Marine Processes 

Water fluxes in the coastal marshes are driven by the water-level differences across the 

estuary. These change over the long term, seasonally, and daily. Long-term rises in sea level 

have been documented by many investigators, and recently average about 0.04 to 0.08 inch (1 

to 2 millimeters) per year, but are projected to increase due to climate change (Titus and 

Richman 2001). These marine processes serve to redistribute sediments and nutrients, as well 

as regulate salinity levels and fluxes in the estuaries. 

Fluvial Processes 

The Mississippi River discharges into the Gulf of Mexico. Most of the Mississippi River waters 

are carried westward along the coast, freshening the Gulf waters that move in and out of the 

Barataria and Terrebonne estuaries, rather than reaching estuaries in the study area (USACE

2009). Some water is discharged through Baptiste Collette, Cubit‘s Gap and Pass a Loutre. This 

plume can influence the study area especially Breton Sound. The Mississippi River is leveed for 

most of its length so sediment no longer reaches many of the Louisiana marshes. The Pearl 

River discharges into the Lake Borgne ecosystem via The Rigolets. Other smaller rivers in the 

Pontchartrain watershed contribute additional water and sediments from local watersheds. 

Chemical Processes 

Elements and compounds can enter tidal wetlands by tidal exchange, precipitation, upland 

runoff, and groundwater flow. Once in the wetlands, they may be deposited on water bottoms, 

adsorbed to particles, or adhered in the tissues of rapidly growing vascular plants. 

Biological Processes 

Coastal fringe marshes provide habitat for a variety of vertebrate animals including fish, birds, 

mammals, and reptiles. Teal (1986) stated that one of the most important functions of salt 

marshes is to provide habitat for migrant and resident bird populations. Some wildlife species 

inhabiting tidal marshes are important game animals, valuable furbearers, and provide 
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2-6 June 2012 

recreational opportunities for hunters, birdwatchers, nature enthusiasts, and wildlife 

photographers (USACE 2009). 

The majority of wildlife species that utilize the wetlands have neither commercial nor 

recreational value, but simply are ecologically important members of the ecosystem. For 

example, the rice rat and other small mammals play a key role in marsh trophic cycles, 

providing food for several species of avian and mammalian predators. Many of the vertebrates 

that use the marsh ecosystem are highly mobile and serve as a transfer mechanism for 

nutrients and energy to adjacent terrestrial or aquatic ecosystems. Some of the larger 

vertebrates, including the muskrat and nutria, consume copious amounts of plants and, at high 

densities, may have significant impacts on marsh vegetation structure (USACE 2009). 

Tidal marshes provide forage, spawning sites, predation refuge, and nursery habitat for resident 

and nonresident fishes and macrocrustaceans. These organisms use tidal marshes or adjacent 

subtidal shallows either year round or during a portion of their life history. These organisms are 

consumed by nektonic and avian predators and represent an important link in estuarine trophic 

dynamics (USACE 2009). 

2.2.2 Geomorphic and Physiographic Setting 

Louisiana 

The study area lies within the Mississippi Delta Region, which is comprised of three geomorphic 

regions. Pleistocene Terrace Region is the area north of Lakes Maurepas, Pontchartrain and 

Borgne; The Marginal Deltaic Basin is comprised of estuarine marshes and forested wetlands 

around Lakes Pontchartrain and Maurepas. Maurepas Swamp includes some of the largest 

remaining tracts of forested wetlands in the Lower Mississippi River Valley. The Marginal Deltaic 

Basin region lies within the coastal zone of Louisiana, and is influenced by wetland loss, 

subsidence, saltwater intrusion and shoreline erosion. The Mississippi River Deltaic Region lies 

south and east of Lakes Maurepas and Pontchartrain. The salinity gradient within this region 

decreases from east (salt water of the Gulf) to west (fresher waters in the coastal plain) through 

the Pontchartrain Basin. 

The eastern Louisiana coast consists of a deltaic system with fronting barrier islands built by the 

Mississippi River. High, firm land is rare in coastal Louisiana. Elevations of the wetlands are 

barely above mean gulf level and at best the soils are soft and poorly consolidated. Within the 

Deltaic Plain, finger-like patterns of narrow alluvial ridges, which reach out toward the gulf, are 

higher and firmer. These natural levees, formed by overbank processes, occur along active and 

abandoned Mississippi River distributaries (Coast 2050). The natural and man-made ridges 

form the skeletal framework to which the coastal wetlands are attached. They form hydrologic 

basin boundaries, and are more resistant to erosion than the wetlands. 

Separating the wetlands from the open Gulf is the Chandeleur Island chain. The islands occur in 

an arc fringing an abandoned delta lobe (Morgan and Larimore 1957; Penland and Boyd 1981). 
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Figure 2-2. Sedimentation Process 
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Mississippi 

The western boundary of the state consists of broad expanses of emergent tidal marsh and 

riverine swamps. The mainland of Mississippi is bordered on the south by Mississippi Sound, a 

shallow body of water that separates the coast from Cat Island, a barrier island that lies 

approximately 6 miles offshore. 

The geomorphology of Cat Island is more closely related to the geomorphology of the Louisiana 

islands. The geologic evolution of Cat Island was also influenced by the extension of the St. 

Bernard subdelta 4,000 to 2,000 years ago (Roberts 1997). Cat Island is the only barrier island 

in the Mississippi Barrier Island Chain with a significant fringing coastal marsh habitat. 

2.2.3 Hydrology 

A detailed discussion of study area hydrology is included in the EIS and Engineering Appendix. 

Hydrologic Basins 

The study area includes the Pontchartrain Basin and the southernmost portion of the Pearl 

River Basin. The Lake Pontchartrain Basin consists of Lake Maurepas, Lake Pontchartrain, 

Lake Borgne, the Biloxi Marshes, Chandeleur Sound, and associated marshlands and 

waterways. Lakes Maurepas and Pontchartrain are hydrologically connected by Pass Manchac, 

separated only by landbridges of cypress swamp and fresh/intermediate marsh. Lake Borgne is 

hydrologically connected to Lake Pontchartrain through Chef Menteur Pass and The Rigolets. 

The Pontchartrain Basin has several freshwater tributaries. These are the most important factor 

affecting salinity in Lake Pontchartrain. The annual freshwater flow into Lake Pontchartrain 

averages about 3,800 cubic feet per second (cfs). The Pearl River discharges a mean annual 

flow of about 10,000 cfs into The Rigolets, and is the largest recurring natural freshwater 

influence in the basin. Lake Borgne is connected to the Mississippi River Gulf Outlet by several 

bayous, principally Bayous Bienvenue, Dupre, Yscloskey, and La Loutre. Prior to the 

construction of levees, seasonal flooding of the Mississippi River provided freshwater inputs into 

the study area estuaries. 

The Pearl River Basin covers an area of about 7,800 square miles from the headwaters of the 

Pearl River in east-central Mississippi to western Mississippi Sound. From its headwaters, the 

Pearl River flows southwesterly, forming the boundary between Louisiana and Mississippi in the 

southern part of the basin, and discharging into Lake Borgne near The Rigolets. Near the coast, 

the river becomes estuarine, bounded by salt marsh and affected by tidal influence. The Pearl 

River is about 490 miles long and divides into the Pearl River and the West Pearl River about 50 

miles above the mouth. Significant tributaries include the Yockanookany and Strong Rivers. 

Tides 

Tides in the study area are diurnal, with mean ranges of 0.3 foot (Lake Maurepas) to 0.5 foot 

(Lake Pontchartrain) to 1.4 feet (Chandeleur Sound). Mean water levels are affected by winds, 

freshwater runoff, and seasonal trends in the Gulf of Mexico. Sustained winds can raise or lower 
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peak astronomical tide levels by several feet for short periods. Currents and circulation are 

controlled by tides, winds, freshwater discharges, and gulf currents (Tate, et al. 2002). 

Hydrodynamics 

There are three Federal navigation channels that modified hydrologic conditions in the study 

area: the IHNC, the GIWW, and the MRGO navigation channel. The vast network of canals, 

pipelines, and production facilities that service the oil and gas industry have also altered natural 

hydrology in the study area. Dredged material spoil banks, which are higher than the natural 

marsh surface and the many smaller canals dredged for oil and gas exploration, alter the flow of 

water through area wetlands. Hydrodynamic alteration changes important hydrogeomorphic, 

biogeochemical, and ecological processes, including chemical transformations, sediment 

transport, vegetation health, and organism migration. 

A hydrologic study across areas of the MRGO channel was conducted from 1959 – 1961 to 

evaluate the major hydrologic parameters, including circulation and salinity, prior to opening the 

MRGO to marine traffic in 1963 (Rounsefell 1964). These data indicated that the Bayou La 

Loutre ridge provided a basin boundary that limited the flow of saline water from the Breton 

Sound area into Lake Borgne and nearby wetlands. An analysis of typical tidal flow across the 

region indicates that since construction of the MRGO, circulation patterns have been altered 

along its length in areas from Breton Sound north to Lake Pontchartrain. The MRGO acted as a 

direct passage for tidal exchange, allowing a more direct flow of higher-density saline water 

inland. 

Dredging performed for construction of the MRGO channel to an approximate depth of 36 feet 

resulted in the generation of an abundance of spoil for placement. The spoil was deposited in a 

continuous strip along the channel‘s southwestern limits. This deposition interrupted the local 

circulation patterns of natural waterways that transected the length of the channel, such as 

Bayou Bienvenue, Bayou Dupre, and Bayou La Loutre. 

Salinity 

The USACE – Engineer Research and Development Center‘s (ERDC) Coastal and Hydraulics 

Laboratory ran a numerical model investigation entitled Salinity Changes in Pontchartrain Basin 

Estuary, Louisiana, Resulting from Mississippi River-Gulf Outlet Partial Closure Plans. In the 

Historical Salinity section of the report data for five stations throughout the basin were analyzed. 

The mean pre- and post-MRGO salinity information is from 1951 to 1963 and 1963 to 1977, 

respectively. These data indicate that the salinity increased at all five stations throughout the 

year after the MRGO was opened. 

A hypoxic/anoxic zone in Lake Pontchartrain was first described by Poirrier (1978). Its existence 

was verified by extensive water quality sampling done by DEQ in 1980 and 1982 (Schurtz and 

St. Pé 1984). This zone appeared to be caused primarily because the MRGO carries bottom 

water in excess of 20 parts per thousand (ppt), which enters the IHNC and then Lake 

Pontchartrain during the flood tide cycle (Georgiou and McCorquodale 2002). This saline water 

sinks to the bottom where it moves with the bottom lake currents and can cover at least 1/6 of 

the lake‘s bottom (Schurtz and St. Pé 1984). This stratified water inhibits both mixing and 
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oxygenation, generally leading to hypoxic (low oxygen) or anoxic (no oxygen) conditions near 

the lake bottom. This hypoxic/anoxic zone seems to appear most often in the spring and 

summer (Abadie and Poirrier 2001). 

Initial monitoring data indicate that the closure at Bayou La Loutre has contributed to decreased 

salinity upstream of the closure (USGS 2009). Results of sampling conducted near the mouth of 

the IHNC in Lake Pontchartrain prior to and after closure in summer 2009 indicate a substantial 

reduction in differences between surface and bottom salinity and dissolved oxygen levels 

(personal communication, Dr. Michael A. Poirrier, UNO). Detrimental DO levels (<4.0 mg/L) 

have not been observed in Lake Pontchartrain since the construction of closure. 

The influx of rivers creates a salinity gradient within Mississippi Sound (Priddy et al. 1955). Both 

east-west and north-south gradients occur in the Sound in addition to vertical gradients. 

Generally, positive salinity gradients exist from the mainland seaward and vertically, surface to 

bottom (GMFMC 1998). Surface salinity is influenced by the discharge of freshwater from large 

rivers and is reduced during periods of higher flow in late spring and early summer (Thompson 

et al. 1999). Temperature follows expected salinity trends (USACE 2008b).
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Figure 2-3. Average Salinity 1959-1961 (in parts per thousand) 
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Figure 2-4. Annual Average Salinity 1990-2008 (in parts per thousand) 
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Figure 2-5. Post-MRGO Closure Annual Average Salinity (in parts per thousand)
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2.2.4 Coastal Vegetation Resources 

Nearshore marine and estuarine habitats, including wetlands, are the nursery grounds for the 

marine food chain in the Gulf of Mexico. As this habitat erodes or changes, it depletes the 

species that form the base of the food chain throughout the Gulf of Mexico. Failure to address 

the loss of this habitat in the Gulf region threatens the long-term health of the entire ecosystem 

and human culture. 

Coastal vegetation resources are institutionally significant because of the Coastal Barrier 

Resources Act of 1982; Coastal Zone Management Act of 1972; Emergency Wetlands 

Resources Act of 1986; Estuary Protection Act of 1968; Fish and Wildlife Conservation Act of 

1980; the Fish and Wildlife Coordination Act of 1958, as amended; Migratory Bird Conservation 

Act; Migratory Bird Treaty Act; Endangered Species Act of 1973 (ESA); Magnuson Fishery 

Conservation and Management Act 1990; National Environmental Policy Act (NEPA) of 1969; 

the North American Wetlands Conservation Act; the Water Resources Development Acts of 

1976, 1986, 1990, and 1992; Executive Order 13186 Migratory Bird Habitat Protection; and 

Executive Order 13547 Stewardship of the Ocean, Our Coasts, and the Great Lakes. 

Coastal vegetation resources are technically significant because they are a critical element of 

coastal habitats. In addition, coastal vegetation resources serve as the basis of productivity, 

contribute to ecosystem diversity, provide various habitat types for fish and wildlife, and are an 

indicator of the health of coastal habitats. 

Coastal vegetation resources are publicly significant because of the high priority that the public 

places on their aesthetic, recreational, and commercial value. Overall, plant communities 

provide protection against substrate erosion and contribute food and physical structure for 

cover, nesting, and nursery habitat for wildlife and fisheries. Continued degradation and loss of 

existing wetland areas, in concert with truncation of replenishing processes, will accelerate 

decline in the interdependent processes of plant production and vertical maintenance necessary 

for a stable ecosystem. 

2.2.4.1 Land Cover 

The vegetation classification descriptions within the study area are covered in detail in the EIS 

for this study. Acreages of the various vegetation classifications are provided below. 

 Wetland Vegetation – 826,668 total acres 

 Palustrine Forested Wetland = 354,226 acres 

 Palustrine Scrub/shrub Wetland = 39,448 acres 

 Estuarine Scrub/Shrub Wetland = 2,050 acres 

 Estuarine Emergent Wetland = 430,944 acres 

 Mixed Forest – 344 acres 

 Deciduous Forest – 416 acres 

 Evergreen Forest – 69,254 acres 

 Developed, High Intensity – 19,916 acres 
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 Developed, Medium Intensity – 32,248 acres 

 Developed, Low Intensity – 96,174 acres 

 Developed, Open Space – 18,498 acres 

 Open Water – 1,969,152 acres 

2.2.4.2 Habitat Types 

Common and scientific names of plants and animals in the study area mentioned throughout 

this report and appendices are also presented as an appendix in the EIS. 

Since the source of salinity in coastal Louisiana and Mississippi is the Gulf of Mexico, salinity 

levels exist along a gradient, which declines as the saltwater moves inland and mixes with 

freshwater sources. A zonation of plant species that differ in salinity tolerance exists along that 

gradient. 

The basic coastal wetland habitats within the study area are typically described as Swamp 

(Forested Wetlands), Fresh, Intermediate, Brackish and Saline Marsh (Day, et al. 1989) (Mitch 

and Gosselink 2000). These habitats are strongly influenced by the salinity regime of the 

surface water. 

Historically, the habitats were maintained by freshwater introduced through the Mississippi River 

and other natural water sources. The construction of levees limits the flow of freshwater into the 

marsh, and the construction of canals allows additional saltwater into the estuary. These and 

other changes have resulted in the shift of higher salinity habitats inland. 

Swamp (0–3 ppt salinity) 

Forested coastal wetlands in the study area are dominated by bald cypress and water tupelo, 

which are the remnants of extensive logging of virgin forest more than 70 years ago. The 

Louisiana swamps generally lack a mature canopy as was present in colonial forests and have 

lower productivity where isolated from riverine influences (Shaffer et al 2003). 

Fresh Marsh (0–3 ppt salinity) 

Fresh marsh has the highest plant diversity of all the coastal habitat types including as many as 

93 species. Floating aquatic and submerged plants are common and are significant for 

waterfowl. Soils may be highly organic and prone to settlement. Many species of duck and 

waterfowl use coastal Louisiana and Mississippi as overwintering grounds for foraging of 

diverse invertebrates, plant roots, and tubers. 

Intermediate Marsh (2–8 ppt salinity) 

Intermediate marsh has lower species diversity than fresh marsh, but may have higher 

productivity. This habitat provides important nurseries for brown shrimp, white shrimp, blue crab, 

and Gulf menhaden or pogy. Soils may be very poor due to very high organic content. 

Submerged aquatic vegetation within lakes and bays are vital to secondary productivity. 
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Brackish Marsh (4–18 ppt salinity) 

Brackish marsh has the lowest plant diversity, but may be the most productive type of marsh. 

The dominant species is marshhay grass. Oysters are exceptionally significant due to filtration, 

biomass, reef building, and commercial harvest and other fish found in reef communities. 

Salt Marsh and Barrier Islands (8–29 ppt salinity) 

Salt Marsh and barrier islands have high overall species diversity due to plants and animals. 

Bird rookeries are an important use of these habitat types. Nesting for sea turtles occurs on 

some islands. Some islands in the study area also have true seagrasses on their bay side 

lagoons and provide habitat for the endangered West Indian manatee during migration. 

2.2.4.3 Invasive Species 

Invasive plant species often increase and spread rapidly because the new habitat into which 

they are introduced is often free of insects and diseases that are natural controls in their native 

habitats. In coastal Louisiana, 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 2009). 

Invasive species are a major cause of the extinction of native species (second only to habitat 

loss). Muskrat, once trapped for their valuable fur throughout coastal Louisiana, have been 

crowded out by South American nutria. In summer 2000, masses of Australian spotted jellyfish 

along the Louisiana coast threatened to disrupt the gulf shrimp industry. 

2.2.4.4 Rare, Unique and Imperiled Vegetative Communities 

The following unique communities, nestled within the broader vegetative habitats, are important 

in that they contribute to the extensive diversity of the coastal ecosystem, and are essential to 

the stability of the bionetwork. 

Marine Submergent Vascular Vegetation Communities 

Also known as seagrass beds, marine submergent vascular vegetation communities occur in 

shallow, relatively clear offshore marine systems with unconsolidated substrate. The primary 

community species listed are turtle grass, manatee grass, and shoal grass. 

Estuarine Submergent Vascular Vegetation Communities 

Composed primarily of water celery, widgeon grass, southern naiad and horned pondweed, 

these brackish communities grow in sand/mud bottom substrates in shallow, protected waters 

with low turbidity. Activities that cause long-term increases in turbidity in the waters surrounding 

the beds are a serious threat to their viability. 
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Coastal Mangrove Thicket 

Dominated by black mangrove, this estuarine community has several important ecological 

functions - the extensive root systems stabilize shorelines and reduce erosion, provide cover 

and food, improve surrounding water quality by filtering nutrients and suspended sediments, 

and provide nesting areas for colonial water birds. 

Coastal Dune Grassland 

Also known as maritime grasslands, coastal dune grassland occurs on beach dunes, relatively 

elevated backshore areas above intertidal beaches on barrier islands, and mainland shores. 

Marshhay cordgrass is usually the dominant species, but saltgrass, seashore paspalum, beach 

panicgrass, seacoast bluestem, and broomsedges are common associates. 

Live Oak Forest 

Live oak forests occur principally in southeastern Louisiana on natural levees, ridges, or 

frontlands, and on islands within marshes and swamps in the coastal zone. Live oak dominates 

the stand, but water oak, American elm, sugarberry, red maple, and green ash are usually 

prominent community members. There are only a small number of populations known to exist 

and they are vulnerable to extirpation (local extinction). 

Coastal Live Oak-Hackberry Forest (Coastal Ridge) 

Also known as chenier maritime forest, this natural community formed on abandoned beach 

ridges primarily in southwest Louisiana, although abandoned beach ridges and stream levees in 

the southeast are also locally known as cheniers. Live oak and hackberry are the dominant 

canopy species, and other common species are red maple, sweet gum, water oak, green ash, 

and American elm. 

Fresh Marsh 

Although the fresh marshes, as previously described, compose a large amount of the entire 

coastal marsh acreage, the Louisiana Natural Heritage Program ranks this community as 

imperiled because it has undergone the largest reduction in acreage of any of the marsh types 

over the past 20 years due to saltwater intrusion.
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Figure 2-6. Habitat Diversity Degradation 

 
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Figure 2-7. Pre-Altered Habitat and Biodiversity 
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2.2.5 Wildlife Resources 

Section 3.15 of the associated EIS for this study provides a detailed discussion of wildlife 

resources in the study area. 

The significance of wildlife resources is demonstrated by the multitude of legislative acts that 

exist to manage and conserve the resource. Pivotal among these are the National 

Environmental Policy Act of 1969; the Coastal Zone Management Act; the Estuary Protection 

Act; the Fish and Wildlife Coordination Act of 1958, as amended; the Migratory Bird 

Conservation Act of 1929, as amended; the Migratory Bird Treaty Act of 1918; the Endangered 

Species Act of 1973 (ESA), as amended; the Fish and Wildlife Conservation Act of 1980; the 

North American Wetlands Conservation Act; Executive Order 13186 Migratory Bird Habitat 

Protection; and the Marine Mammal Protection Act. Wildlife resources are critical elements of 

the coastal barrier ecosystem and important indicators of the health of coastal habitats. Wildlife 

resources are also important recreational and commercial resources as well and are regarded 

highly by the public for their aesthetic, recreational, and commercial value. 

The USFWS, in a letter dated October 31, 2008, formally requested that significant fish and 

wildlife resources be fully considered and addressed in this study, including: seabirds, 

shorebirds, wading birds, migratory and resident waterfowl, and estuarine-dependant fishes and 

shellfishes. 

Coastal Louisiana‘s wetlands support neotropical and other migratory avian species such as 

rails, gallinules, shorebirds, wading birds, and numerous songbirds, as well as many different 

furbearers, rabbits, deer, and alligators. Louisiana coastal wetlands provide neotropical 

migratory birds essential stopover habitat on their annual migration route. The coastal wetlands 

in the study area provide important and essential fish and wildlife habitats, used for shelter, 

nesting, feeding, roosting, cover, nursery, and other life requirements. 

2.2.6 Aquatic and Fishery Resources 

Section 3.16 of the associated EIS for this study provides a detailed discussion of aquatic and 

fisheries resources in the study area.

Fishery resources, including both finfish and shellfish, are institutionally, ecologically, and 

publicly important. They are institutionally important because of the Fish and Wildlife 

Coordination Act of 1958, as amended; Endangered Species Act of 1973; Magnuson-Stevens 

Fishery Conservation and Management Act of 1976, as amended (Magnuson-Stevens Act); 

Magnuson-Stevens Act Reauthorization of 2006; Coastal Zone Management Act; and Estuary 

Protection Act. They are ecologically important because they occupy various trophic levels in 

the aquatic environment. They are publicly important because of the high priority placed on their 

aesthetic, recreational, and commercial value. 

Emergent wetlands and shallow open water areas in the study area provide important habitat 

and Essential Fish Habitat (EFH). The area historically and currently provides valuable habitat 
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for recreational and commercial fishing, oyster culture, and nursery areas for a wide variety of 

finfish and shellfish (Rounsefell 1964; Penland et al. 2002). 

By letter dated October 27, 2008, the National Marine Fisheries Service (NMFS) indicated 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 and 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 Gulf of Mexico Fishery Management Council (e.g., mackerels, 

snappers, and groupers) and highly migratory species managed by NMFS (e.g. billfishes and 

sharks). 

Mississippi Sound Estuary 

The Mississippi Sound estuary provides prime habitat for various lifestages of red snapper, 

tuna, redfish, Spanish and king mackerel, grouper, speckled trout, jack crevalle, cobia, 

amberjack, marlin, and various species of sharks. Mississippi Sound‘s productivity is ideal for 

sport fishermen, commercial fishing, and local recreational use (USACE 2008b). 

The total value of commercial fisheries landings in Mississippi amounted to $43.6 million in 2008 

(NMFS 2010). The recreational fishing industry, which includes saltwater and freshwater fishing, 

is also a significant economic contributor to the state. 

Louisiana Estuaries 

Louisiana‘s coastal estuaries are the most productive in the nation. Louisiana has historically 

been an important contributor to the nation‘s domestic fish and shellfish production, and one of 

the primary contributors to the nation‘s food supply for protein. Landings in 2008 for commercial 

fisheries in coastal Louisiana, estimated at 918 million pounds, were the largest for any state in 

the contiguous U.S. and second only to Alaska (NMFS 2009). These landings represent over 11

percent of the total landings in the U.S., with a value of approximately $272.9 million. 

Fisheries are discussed in detail in the EIS. Fish were sampled in the MRGO area from 1959 to 

1961 (El-Sayed 1961). Estuarine marine species dominated the fish communities with spot, 

Atlantic croaker, anchovy, and seatrout ranked among the top ten species in every area 

sampled. Nine freshwater species disappeared after the construction of the channel (Fontenot 

and Rogillo, 1970). More recent data shows that as the salinity levels increased in the areas 

immediately adjacent to the MRGO channel, more marine species began to appear in sampling 

trawls (LDWF 2000). Blue crab and brown and white shrimp are harvested in the study area. 

Oysters 

Adult oysters can tolerate salinity from 0 to 42 ppt, but the optimal salinity range is 5-15 ppt 

(EOBRT 2007). Oysters grow faster in areas with fluctuating salinity within their normal ranges, 

compared to constant salinity (Pierce and Conover 1954). In Louisiana, a total of 12.8 million 

pounds of oyster were harvested in 2008, with a dockside value of $38.8 million (NMFS 2009). 

The extent of oyster reefs in Mississippi is estimated at 10,000 to 12,000 acres, of which over 
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half is located in the western Mississippi Sound south of Pass Christian. In 2008, 2.8 million 

pounds of oyster were harvested in Mississippi, with a value of $6.9 million (NMFS 2009). 

2.2.7 Essential Fish Habitat 

Section 3.18 of the associated EIS for this study provides a detailed discussion of essential fish 

habitat (EFH) in the study area. 

Aquatic and tidally influenced wetland habitats within portions of the study area are designated 

as EFH for shrimp, red drum, reef fish, and stone crab, as listed in the Fisheries Management 

Plan and managed by the Gulf of Mexico Fishery Management Council (GMFMC). The 1996 

amendments to the Magnuson-Stevens Fishery Conservation and Management Act of 1996 

(MSA) set forth a mandate for the National Marine Fisheries Service (NMFS) of the National 

Oceanic and Atmospheric Administration (NOAA), regional Fishery Management Council 

(FMC), and other Federal agencies to identify and protect EFH of economically important 

marine and estuarine fisheries including critical habitat needed for various life stages. The public 

places a high value on seafood and recreational and commercial opportunities provided by 

EFH. Specific categories of EFH include all estuarine waters and substrates (mud, sand, shell, 

rock, and associated biological communities), subtidal vegetation (sea grasses and algae), and 

adjacent intertidal vegetation (marshes and mangroves). 

By letter dated October 27, 2008, NMFS identified EFH resources in the study area as including 

estuarine emergent wetlands; submerged aquatic vegetation/seagrass beds; mud, sand and 

shell substrates; and estuarine and marine water column. Habitats in portions of the study area 

are designated as EFH for pink, brown and white shrimp; red drum; Gulf stone crab; lane 

snapper; dog snapper; dwarf sand perch; king mackerel; Spanish mackerel; cobia; bonnethead 

shark; and Atlantic sharpnose shark. 

2.2.8 Threatened and Endangered Species 

Section 3.19 of the associated EIS for this study provides a detailed discussion of threatened 

and endangered species that occur in the study area. 

This resource is institutionally significant because of the Endangered Species Act of 1973, as 

amended, and the Marine Mammal Protection Act of 1972. Threatened and endangered species 

are technically significant because the status of such species provides an indication of the 

overall health of an ecosystem. These species are publicly significant because of the desire of 

the public to protect them and their habitats. 

Within the State of Louisiana there are thirty animal and three plant species (some with critical 

habitats) under the jurisdiction of the USFWS and/or the NMFS, presently classified as 

threatened or endangered. The USFWS and the NMFS share jurisdictional responsibility for sea 

turtles and the Gulf sturgeon. Of the animals and plants under USFWS and/or NMFS 

jurisdiction, nine animal species and no plant species are potentially found within the project 

area. Although some of these species may be occasionally found in the project area, those 

species that may be potentially impacted by the proposed action are described below. 
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 One federally listed endangered avian species, the piping plover, may occur in the 

study area. Piping plovers winter on barrier islands along the Gulf coast, including 

Louisiana. Portions of the Mississippi Sound shore, the Mississippi River Delta, and 

Breton Island and Chandeleur Island chain are critical habitat for piping plovers. 

 The West Indian manatee, a federally listed endangered marine mammal, may 

occasionally enter Lakes Pontchartrain and Maurepas, and associated coastal 

waters and marshes of Louisiana. The West Indian manatee is also found in the 

Mississippi Sound and St. Louis Bay. 

 The pallid sturgeon is a federally listed endangered nonanadromous fish species 

inhabiting the Missouri and Mississippi Rivers from Montana to Louisiana. 

 Gulf sturgeon, a federally listed threatened anadromous fish, occur in rivers and 

lakes of the Lake Pontchartrain basin. Portions of the Pearl and Bogue Chitto Rivers, 

Lake Pontchartrain east of the Causeway Bridge, Little Lake, The Rigolets, Lake St. 

Catherine, and Lake Borgne were designated as critical habitat for the Gulf sturgeon 

on March 19, 2003 (Federal Register Volume 68, No. 53). 

 Five federally listed sea turtle species may occur in the study area: the Kemp‘s 

Ridley sea turtle (endangered), Atlantic green sea turtle (threatened), hawksbill sea 

turtle (endangered), loggerhead sea turtle (threatened and under review), and 

leatherback sea turtle (endangered). 

State Rare, Threatened and Endangered Species 

The Louisiana Natural Heritage Program lists thirty-one species as occurring in the study area 

not including federally listed species (LNHP 2009). These include: Cooper's Hawk, River Grass, 

Big Brown Bat, Southern Umbrella-sedge, Southwest Bedstraw, Bald Eagle, small flower 

hemicarpha, Malaclemys terrapin, Diamondback Terrapin, Glossy Ibis, Paddlefish, Clasping-leaf 

Pondweed, Ornate Chorus Frog, Sand Rose-gentian, Saw Palmetto, Dune Sandbur, Sand 

Dune Spurge, Snowy Plover, Reddish Egret, Creeping Spike-rush, Gull-billed Tern, American 

Oystercatcher, Gulf Halophila, Caspian Tern, Brown Pelican, coastal ground cherry, Roseate 

Spoonbill, Eared Greenbrier, Turtle-grass, and Sea Oats. 

The Mississippi Natural Heritage Program lists five species as occurring in the Mississippi study 

area (MNHP 2009). These species include: marsh eryngo, coast sedge, naked-stemmed panic 

grass, harper's yellow-eyed grass, and Drummond's yellow-eyed grass. 

2.2.9 Recreational Resources 

Section 3.23 of the associated EIS for this study provides a detailed discussion of recreational 

resources in the study area. 

Recreational resources are institutionally significant because of the Federal Water Project 

Recreation Act of 1965, as amended, and the Land and Water Conservation Fund Act of 1965, 

as amended. Recreational resources are technically significant because of the high economic 

value of recreational activities and their contribution to local, state, and national economies. 

Recreational resources are publicly significant because of the high value that the public places 
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on fishing, hunting, and boating, as measured by the large number of fishing and hunting 

licenses sold in Louisiana, and the large per-capita number of recreational boat registrations in 

Louisiana. 

Louisiana Recreational Resources 

State and Federal recreation areas in the Louisiana portion of the study area include: Bayou 

Sauvage National Wildlife Reserve, Biloxi Wildlife Management Area, Breton National Wildlife 

Reserve, Fort Pike State Historic Site, and the Pearl River Wildlife Management Area. Other 

recreational features are provided by parishes and historic communities that attract visitors to a 

variety of heritage and cultural festivals, historical sites, parks offering opportunities for active 

and passive recreation that include tennis courts, soccer and softball fields, swimming pools, 

and golf courses. 

Funds from the Land and Water Conservation Fund have supported 164 different recreational 

projects in the Louisiana portion of the study area since 1964. Land and Water Conservation 

Fund projects in the study area have provided numerous boat ramps and other facilities that 

enhance opportunities for recreation (LWCF 2008). Recreation areas in the study area include 

15 miles of trails for hiking and biking, 38 boat ramps, four fishing piers, one classroom space, 

two visitor centers, and two picnic shelters. These recreation areas provide opportunities for 

hunting, hiking, biking, boating, bird watching, fishing and crabbing, crawfishing, shrimping, 

education, camping, picnicking, and playing. 

Mississippi Recreational Resources 

Buccaneer State Park is located in the study area in Hancock County. Due to damage from 

Hurricane Katrina, it has been closed since 2005. 

The 2 miles of the western tip of Cat Island are within the boundaries of the Gulf Islands 

National Seashore under the jurisdiction of the National Park Service. The island is only 

accessible by private boat. Recreational opportunities include beaches, hiking, and overnight 

camping. 

2.2.10 Historic and Cultural Resources 

Section 3.22 of the associated EIS for this study provides a detailed discussion of cultural 

resources in the study area. 

Historic and cultural resources are institutionally significant because of the National Historic 

Preservation Act (NHPA), as amended (16 U.S.C. 470 et seq.), and NEPA. Historic and cultural 

resources are technically significant to the fields of anthropology, archeology, architecture, and 

other disciplines. Historic and cultural resources are publically significant because of the desire 

of the public to protect them for future generations. 
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Louisiana 

High probability areas for archaeological sites are the ridges adjacent to Bayou La Loutre and 

Bayou Terre aux Boeufs. One site situated along Bayou La Loutre is listed on the National 

Register of Historic Places (NRHP). Other areas with the possibility of encountering important 

cultural resources are the off-shore borrow areas, especially in and around Lake Borgne. The 

potential exists for finding boats and ships that took part in the 1814-1815 Battle of New Orleans 

in Lake Borgne. Archaeological sites are very common along the shorelines of Lakes Maurepas, 

Pontchartrain and Borgne. Archaeological sites are also common along the rivers and bayous 

draining into these lakes, especially along the lower reaches of these streams. 

Historic plantations are very common along the main channel of the Mississippi River. These 

are often represented by the remains of sugar mills and plantation related grave yards. 

Important vernacular house types are also situated along the Mississippi River and along the 

upper reaches of Mississippi River distributaries. 

Mississippi 

Site types range from shell middens along streams and on beaches, historic forts and 

settlements and shipwrecks. Previous investigations in the area include Lauro 1995, Smith et. al 

2007, and U.S. Army Corps of Engineers 1995.

2.2.11 Aesthetics 

Section 3.24 of the associated EIS for this study provides a detailed discussion of aesthetic 

resources in the study area. 

Aesthetic resources are institutionally significant because of the Louisiana Scenic Rivers Act 

Acts of 1988 and NEPA. Aesthetic resources are publically significant because of the desire of 

the public to protect viewsheds. 

The visual complexity surrounding the study area‘s marshes, bayous, wetlands, ridges and 

levees provide a pleasing aesthetic. View points that provide some visual interest are based on 

the interplay of lines, forms, colors and textures found in water, vegetation and changes in 

elevation from the water‘s edge to dry land. Public significance is based on expressed public 

perceptions and professional analysis of the study area. 

Louisiana Scenic Rivers and Streams 

The Louisiana Natural and Scenic River System is one of the nation‘s largest, oldest, most 

diverse and unique state river protection initiatives (LSU Agricultural Center 2009). 

The LDWF administers the Louisiana Natural and Scenic Rivers system established in 1970 for 

the purpose of preserving, developing, reclaiming and enhancing the wilderness qualities, 

scenic beauties and ecological regime of designated free-flowing water bodies. 

There are 21 designated scenic streams or bayous located within the study area (Table 2-2). All 

of these streams are used for recreational activities such as boating, fishing, and canoeing. 
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Table 2-2. Louisiana Scenic Streams and Rivers in the Study Area 

Scenic Stream/River Location

Bayou Dupre The Lake Borgne Canal to Terre Beau Bayou

Lake Borgne Canal The Forty Arpent Canal to Bayou Dupre

Bashman Bayou Origin to Bayou Dupre

Terre Beau Bayou Bayou Dupre to the New Canal

Pirogue Bayou Bayou Dupre to the New Canal

Bayou Bienvenue Bayou Viuere to Lake Borgne

Bayou Chaperon Origin to end

Bayou Cane Fontainbleau State Park to Lake Pontchartrain

Bayou Chinchuba West Causeway approach to Lake Pontchartrain

Bayou Dupre Lake Borgne/Violet Canal to Terre Beau Bayou

Bayou LaBranche Good Hope to Lake Pontchartrain

Bayou Lacombe Talisheek to Lake Pontchartrain

Bayou St. John Origin to Lake Pontchartrain

Bayou Trepagnier Origin to Bayou La Branche

Blind River Origin to Lake Maurepas

Tchefuncte River Origin to Lake Pontchartrain

Pushepatapa Creek East/West Fork to Cross Creek

Tangipahoa River State line to Lake Pontchartrain

Terre Beau Bayou Bayou Dupre to New Canal

Tickfaw River State line to Springville

West Pearl River Wilson/Bradley Slough to East/West mouth

2.2.12 Hazardous, Toxic, and Radioactive Materials 

The Phase I Environmental Site Assessment for this study provides detailed information 

regarding the presence of hazardous, toxic, and radioactive materials in the study area and is 

presented as an appendix in the associated EIS. 

During review of historic records the presence of a former World War II training facility known as 

the Shell Beach, Anti-Aircraft Training Center located on the southern shoreline of the eastern 

half of Lake Borgne was identified. Based on review of historic documents and information 

obtained from personnel interviews, ammunition was shot from both large and small caliber 

weapons at targets that were towed above Lake Borgne. 

Magnetic surveys of the shoreline protection area between Doulluts Canal and Jahncke‘s Ditch 

were conducted by USACE Baltimore District, Munitions and Explosives of Concern dredging 

experts. These surveys did not identify the presence of Munitions and Explosives of Concern in 

the dredged material deposited within an existing shoreline protection project. The Munitions 

and Explosives of Concern dredging experts reported a low probability of encountering 

Munitions and Explosives of Concern in the study area. The Munitions and Explosives of 

Concern dredging experts also recommended that borrow area sediments are monitored during 

the project for Munitions and Explosives of Concern. 
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Should at anytime during the project Hazardous, Toxic, and Radioactive Waste (HTRW) 

concerns arise, the USACE New Orleans District would take immediate actions to investigate 

the concerns. Should an HTRW issue be determined and the development of a response action 

required, USACE New Orleans District would coordinate with the appropriate Federal and state 

authorities to implement an approved response action. 

2.2.13 Socioeconomic and Human Resources 

Section 3.20 of the associated EIS for this study includes detailed socioeconomic information for 

existing and historic conditions in the study area. 

Socioeconomic and human resources are institutionally significant because of the National 

Environmental Policy Act of 1969; the Estuary Protection Act; the Clean Water Act; the River 

and Harbors Acts; the Watershed Protection and Flood Protection Act; and the Water 

Resources Development Acts. Of particular relevance is the degree to which the proposed 

action affects public health, safety, and economic well-being; and the quality of the human 

environment. This resource is technically significant because the social and economic welfare of 

the nation may be positively or adversely impacted by the proposed action. This resource is 

publicly significant because of the public‘s concern for health, welfare, and economic and social 

well-being from water resources projects. 

Population 

Population in the study area is spread among portions of eleven Louisiana parishes, including 

Ascension, Jefferson, Livingston, Orleans, Plaquemines, St. Bernard, St. Charles, St. James, 

St. John the Baptist, St. Tammany, and Tangipahoa. The eastern boundary of the study area 

includes portions of Hancock and Harrison Counties in Mississippi that do not include any 

permanent resident population. The total population of the eleven Louisiana Parishes was 

1,382,975 persons in 2007 (City Data 2008). The study area itself, however, is smaller than the 

multi-parish area and encompasses only portions of this population. Orleans and St. Bernard 

Parishes are wholly included in the study area and had populations of 484,674 and 67,229, 

respectively, in 2000. July 2007 estimated post-storm populations were significantly lower. 

Business and Industrial Activity 

Business and industrial activity for the study area is well-represented by the commercial/ 

tourism industries of Orleans Parish and the agriculture/fishing industries of the remaining 

parishes. The large presence of oil and gas industries in southern Louisiana also impact 

business activity in the study area. 

Public Facilities and Services 

The study area contains the normal array of public facilities and services normally associated 

with a major metropolitan area. These include but are not limited to hospitals, medical facilities, 

schools, government offices/buildings, public wharves, parks, recreation areas, and public 

transportation. 
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Transportation 

The transportation infrastructure of the study area includes major roadways and navigable 

waterways. Interstate 10 passes through the Greater New Orleans area and connects Louisiana 

with Texas and Mississippi along the southern corridor. Interstate 55 is its north/south 

counterpart, beginning in LaPlace, Louisiana, and ending in Chicago, Illinois. Major waterways 

include the Mississippi River and the GIWW. The GIWW is a navigable inland waterway running 

approximately 1,050 miles from Carrabelle, Florida, to Brownsville, Texas. 

Risk Reduction Infrastructure 

When completed in 2011, the 350-mile Hurricane and Storm Damage Risk Reduction System 

(HSDRRS) will consist of levees, floodwalls, gates and pumps providing 100-year level 

protection to a five-parish area. This system represents a $14.5 billion Federal investment in risk 

reduction in the area (Greater New Orleans Hurricane and Storm Damage Risk Reduction 

System Facts and Figures, December 2009). One of the major HSDRRS projects within the 

study area is the IHNC Surge Barrier. The IHNC Surge Barrier at Lake Borgne is a 1.8-mile-long 

barrier, the largest of its kind in the world, and includes three navigation gates and a barrier wall 

that will stand 24–26 feet above the water line. 

Community and Regional Growth 

Historically, most of the activities that have driven regional and community growth have 

centered on oil and gas production, tourism, port operations, fishing, and hunting. Development 

of the area‘s energy resources during the 1950s and 1960s was instrumental in the expansion 

of industrial growth in surrounding communities. More recently, saltwater sport fishing has 

become an important stimulus to local and regional economies. In the last 40 years this activity 

has increased in popularity due to the advancements in affordable and reliable power sources 

for small boats and the advent of fiberglass boat hulls. Recreational fishing has a substantial 

economic impact on the coastal Louisiana economy. 

Community and regional growth have benefitted from the construction of an extensive network 

of levees along the Mississippi River for flood protection, and maintenance dredging of the river 

sufficient to accommodate deep-draft navigation and waterborne commerce. Numerous lesser 

flood control, hurricane protection, and navigation projects have also been developed in 

response to public officials seeking support for continued desirable community and regional 

growth. 

2.2.14 Tropical Storms 

Tropical 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 years). 
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2.3 FUTURE WITHOUT PROJECT CONDITION 

The No-Action Alternative is an analysis of the Future without Project (FWOP) Conditions for the 

period of analysis. Chapter 4 of the EIS, Environmental Consequences, describes the potential 

direct, indirect, and cumulative impacts of the No-Action Alternative for the MRGO Ecosystem 

Restoration Study in detail. 

The No-Action Alternative would have no direct beneficial or adverse impacts. Most of the 

indirect and cumulative impacts resulting from the No-Action Alternative are related to coastal 

land loss, which is expected to continue into the future without action. 

Without action, the key systemic problems in the study area would persist over the period of 

analysis (2011 to 2065). 

 Land loss: 131,100 acres of emergent wetlands are projected to be converted to open 

water (USGS 2010). 

 Bank/shoreline erosion: Erosion would continue to threaten the littoral structure of the 

ecosystem and the integrity of critical landscape features. 

 Habitat change and loss: Wetland losses, saltwater intrusion, and further modification 

of natural hydrology would result in an increasingly homogenous system. Rare and 

unique habitat would become increasingly scarce. 

 Modification of natural hydrology: Land loss would result in the convergence of open 

water areas into larger waterbodies, further altering the study area hydrology. 

 Decreased freshwater, sediment, and nutrient inputs: Authorized freshwater 

diversions in the study area would not fully address the need for additional freshwater, 

sediments, and nutrients in the study area to nourish emergent vegetation and 

counteract subsidence and sea level rise. 

 Saltwater intrusion: The channel closures at Bayou La Loutre and the IHNC are 

projected to decrease saltwater intrusion into the IHNC and Lake Pontchartrain via the 

former navigation channel. However, land loss and shoreline erosion would continue to 

allow more saline waters into the study area estuaries. 

 Retreating and eroding barrier islands: The entire Chandeleur Island chain is 

projected to convert to subsurface shoals within the period of analysis. 

 Ridge habitat degradation and destruction: The Bayou La Loutre ridge would 

continue to subside to marsh elevation. 

 Invasive species and herbivory: Without action, invasive vegetation will continue to 

out-compete native species. Nutria would continue to destroy emergent wetlands. 

 Increasing susceptibility of coastal communities to storm surge: As emergent 

vegetation along the marsh edge continues to degrade and erode, interior marshes and 

human development will become increasingly exposed to the open waters of the Gulf of 

Mexico. 

2.3.1 Other Restoration Efforts 

Wetland losses in the Louisiana study area would be offset to some extent by other Federal, 

state, local, and private restoration efforts, which were predicted by the LCA study to create, 

restore and/or protect approximately 64,410 net acres in the study area (LCA Subprovince 1). 
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These numbers are based on a 20-year project life for CWPPRA projects and 50-year project 

life for all others evaluated. 

In addition, more recent restoration efforts would also cumulatively interact to help offset losses 

of soil resources in the study area, including the following: 

 CWPPRA PO-30 Lake Borgne Shoreline Protection project. 

 The MRGO 2006 Lake Borgne Shoreline Protection, (Doullut‘s Canal to Jahncke‘s 

Ditch), St. Bernard Parish, LA (06-C-0210) project. 

 The MRGO 2007 North Bank Foreshore Dike Construction and Repairs, Mile 44.4 to 

Mile 39.9 (Non-Continuous), St. Bernard Parish, LA (07-C-0089) project. 

WRDA 2007 authorizes the LCA Plan near-term restoration features, including construction and 

additional investigations. Implementation of the LCA program WRDA 2007 passed would 

provide positive cumulative impacts in reducing the loss of wetlands throughout the study area. 

Other ongoing restoration projects include the Parish Coastal Wetlands Restoration Program 

(―Christmas Tree Program‖), State of Louisiana projects, CIAP projects, civil works mitigation 

projects, regulatory permit mitigation projects, LDNR/NRCS/Soil and Water Conservation 

Committee Vegetation Planting Program, and private restoration efforts. 

2.3.2 Coastal Land Loss 

Land loss in the study area is expected to continue over the 50-year period of analysis. Without 

action, coastal vegetated resources would continue to decline, including bankline erosion and 

sloughing of the shoreline, and continued fragmentation and conversion of existing brackish and 

saline marsh to shallow open water habitats. Both human induced impacts and natural 

processes would contribute to the continued loss of vegetated habitats, including: continued 

shoreline erosion and subsidence, increased saltwater intrusion, increased water velocities, and 

increased herbivory. 

The LCA Study (USACE 2004) estimated coastal Louisiana would continue to lose land at a 

rate of approximately 6,600 acres per year over the next 50 years. It is estimated that an 

additional net loss of 328,000 acres may occur by 2050, which is almost 10 percent of 

Louisiana‘s remaining coastal wetlands. 

Wetland acreage data (1985 through 2006) was obtained from the USGS for the study area. 

FWOP wetland acreages were determined via a linear trendline through those data. Where 

applicable, annual net acreage benefits associated with pre-existing or soon to be constructed 

restoration projects were added to the base subunit FWOP acreages to obtain revised FWOP 

subunit acreages. 

With no action, 131,100 acres of emergent wetlands in the Louisiana portion of the study area 

are predicted to be lost over the period of analysis (USGS 2010). Overall, the majority of direct 

land loss is expected to occur from interior wetlands. However, substantial wetland losses are 

also predicted to occur due to shoreline erosion. If the landbridges are breached, existing 
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vegetated wetlands along these critical landbridges would be converted to open water; and 

those wetlands remaining in the area would be exposed to greater hydrologic forcing factors 

(tidal flow and wave action). 

 Figure 2-8. Projected Future Land Loss 2050. 

Source: Louisiana Coastal Protection and Restoration Authority 

2.3.3 Environmental Consequences of Coastal Land Loss 

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 loss would also reduce the 

availability of important stopover habitats used by migrating neotropical birds.

The loss and deterioration of transitional wetland habitats would continue to impact all federally 

threatened and/or endangered listed 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, piping plover, and the West Indian manatee. 

Cultural Resources 

Erosion and land loss would continue to adversely affect existing cultural resources in the study 

area. The loss of land within the study area threatens the existence and integrity of these sites. 

Recreation and Aesthetics 
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Recreational areas may be affected both positively and negatively by the various projects that 

would be implemented without the MRGO ecosystem projects. Generally, projects that improve 

access to recreation areas or increase the diversity of species in an area would be beneficial to 

recreation. Projects that impede access to open waters or limit birding, hunting or fishing areas 

would be detrimental to recreation. 

The borrow pits that would be created to supply material for structural projects may benefit 

recreational fishing by providing additional public access to fishing, additional ponds for 

freshwater fishing or for fish hatcheries, and additional habitat for waterfowl. If the borrow pits 

are large and in areas where there never was a recreational area, the borrow pits may provide 

entirely new recreation opportunities. 

Marsh creation projects would benefit recreation by providing additional land for birding and 

hunting, but may be detrimental for recreational boating as open waters are removed. Shoreline 

restoration projects would reduce risk for recreational areas and would generally benefit 

recreation by providing increased areas for bird nesting. Shoreline erosion reduction projects 

cause silt and sediment to accumulate along shorelines, which facilitates access to the water 

providing a benefit for recreational fishing. 

Subsistence bankline erosion and sloughing of the shoreline and conversion of existing 

fragmented wetlands to open water habitats would persist, possibly resulting in degraded 

viewscapes for those traveling the study area‘s designated scenic streams. 

2.3.4 Socioeconomic Consequences of Coastal Land Loss 

The continued coast wide decline of emergent wetlands would contribute to the deterioration of 

substrate upon which infrastructure features (e.g., levees; oil, gas and water pipelines, 

telephone and electric transmission wires) are constructed. The effects of land loss and 

degradation would increase potential infrastructure damage and associated adverse 

environmental impacts (e.g. pipeline leaks). Continued land loss would increase the cost of 

maintaining and repairing existing infrastructure. These increased costs would likely be passed 

on to consumers. An increase in the cost of oil and natural gas infrastructure in Louisiana would 

likely increase prices for these commodities nationally. 

While hydrodynamic models show some benefits from additional marsh, island, and landbridge 

habitat, the effects of allowing existing features to degrade in these areas are even more 

pronounced (USACE 2009). Hurricane storm damage risk reduction systems cannot fully 

depend on coastal landscape features because of the vulnerability of these features to single 

storm events. However, the FWOP condition could pose a hazard to the efficacy of the $14.45 

billion Federal investment in risk reduction systems, because the buffer between the structural 

system components and open water would continue to deteriorate. 

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. The 

resultant decline in oyster production in and near the study area would likely result in a local 

reduction of oysters, which could lead to higher local oyster prices as leases farther from ports 

would be relied upon to maintain harvests. There could be similar impacts to nearby state oyster 
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seed grounds in Lake Borgne. This impact could reduce the local availability of seed oysters 

used to sustain the local oyster lease productivity. Because Louisiana and Western Mississippi 

Sound produce between 60 to 65 percent of the nation‘s oysters, these adverse impacts would 

affect oyster availability and prices across the country. 

Continued land loss in the study area would gradually change the estuarine system to a 

saltwater system. This change could have adverse impacts to estuarine fisheries, as study area 

wetlands provide nursery and foraging habitats for a variety of economically important marine 

species. Negative impacts to the productivity of fisheries in the study area would affect the 

availability and cost of seafood nationally. 

Continued degradation and loss of emergent wetlands in the study area would contribute to 

increased sedimentation and maintenance of the GIWW navigation channel. As the wetlands in 

the Golden Triangle fragment and convert to open water, the protection afforded to the GIWW 

from Lake Borgne wind-driven waves would be reduced. Some vessels utilizing the GIWW, 

especially barge traffic, would be subjected to more open water conditions as the landbridge 

continues to erode, thereby exposing this waterway directly to Lake Borgne. The integrity of the 

GIWW as an inland, protected waterway is paramount to its function for navigation and 

commerce. Costs to maintain this protection would likely increase if the landbridge breached. 

2.3.5 Future Hydrology 

Programs such as CWPPRA, CIAP, and LCA as well as ongoing hurricane protection projects 

would have indirect impacts on hydrology in the study area. The gates on the GIWW and Bayou 

Bienvenue would alter flow patterns in and near the western end of the study area. Construction 

of the storm surge barrier structure included dredging an access channel on the Lake Borgne 

side of the floodwall (USACE, 2008). The access channel connects the MRGO with the GIWW 

across the Golden Triangle, but will be closed after construction. The net effect has been 

determined to be negligible. The gates across Bayou Bienvenue and the GIWW would remain 

open, except when a storm surge is present or anticipated. 

Construction of the storm surge barrier structure would alter the flow path of tidal propagation 

into the Central Wetlands area through the Bayou Bienvenue Control Structure. Prior to the 

construction of the surge barrier, tidal flow in and out of the Bayou Bienvenue Control Structure 

came from multiple directions (i.e. from across the MRGO as well as from north and from south 

in the MRGO). With this barrier in place, the tidal flow no longer comes from the south in the 

MRGO. Likewise the completed MRGO closure structure at the La Loutre Ridge has altered 

tidal flow paths to the Bayou Dupre Control Structure. The tidal connection with Breton Sound 

via the MRGO has been severed. 

Cumulative Impacts 

Cumulative impacts would be the synergistic effect of no action on hydrology with the additive 

combination of similar wetland degradation and wetland loss impacts to hydrology and 

hydraulics throughout coastal Louisiana, as well as the benefits and impacts to other state and 

Federal projects in the vicinity as detailed in the EIS. 
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2.3.5.1 Future Salinity Conditions 

Hydrodynamic modeling was conducted for this study to determine historic, baseline, and future 

conditions in the study area. This effort is described in detail in Annex 1 of the Engineering 

Appendix for the study. 

FWOP conditions are examined based on the final disposition of future diversions. FWOP 

scenarios include the baseline conditions at Violet Siphon, Caernarvon, and Bonnet Carré 

Spillway leakage and openings. Planned diversions at Maurepas Swamp (Convent/Blind River, 

Hope Canal/Maurepas Swamp River Reintroduction), Caernarvon operation modifications, and 

the Central Wetlands Wastewater Treatment Program are included in the FWOP conditions. 

Planned diversions from the lower Mississippi River located below the Caernarvon Diversion 

were not included in the hydrodynamic model. The Bertrandville Siphon, Bohemia Mississippi 

River Reintroduction, Delta Building Diversion (North of Ft. St. Phillip), White Ditch, Bayou 

LaMoque and the Benney‘s Bay Diversion were deemed to be sufficiently removed from the 

Lake Borgne ecosystem to preclude significant influence on salinity conditions in the area. 

Additionally, there is little available information as to the proposed operational schemes for 

these diversions. The inflow due to existing cuts, overflows and diversions in the Mississippi 

River reach from Baptiste Collette to Bohemia was approximated as 12% of the River flow. 

The freshwater diversion for the Violet Siphon was modeled as 100 cfs, which is assumed to be 

the average. Historic data were used in the model to include Bonnet Carré Spillway openings 

with a maximum flow of 240,000 cfs. The combined diversions into the Maurepas swamp area 

(Convent/Blind River Diversion, Hope Canal/Maurepas Swamp River Reintroduction) have a 

potential capacity of 4,500 cfs in the FWOP scenario. The Central Wetlands Wastewater 

Treatment Program flow totaled approximately 30 cfs. 

Input flows for the Caernarvon diversion were increased by roughly 25 percent, which is 

consistent with the projected modifications to operations. The increase is calculated by 

increasing the actual flows for 2007 and 2008, in which the structure was operated to pulse 

large flows, by 25 percent. The resulting flows were then smoothed so as to eliminate rapid 

changes that might induce numerical instabilities in the model. 

The hydrodynamic model results indicate that the planned diversions reduce salinity in the study 

area. However, the salinity reductions do not restore pre-MRGO conditions in the Lake Borgne 

ecosystem. Additional freshwater is needed to achieve the salinity targets developed for this 

study, as described in Section 2.5.6. 

2.3.6 Future Water Quality 

The FWOP includes direct adverse and beneficial impacts on water quality from the 

implementation of freshwater diversions or other programs, such as CWPPRA, CIAP, and LCA, 

within the study area. These diversions could have both adverse and beneficial impacts to water 

quality, as discussed in detail in the EIS. Current water quality conditions would likely persist 

and coastal wetlands could continue to be affected by natural and man-made factors that have 

both beneficial and adverse effects on water quality. The continual loss of emergent wetland 
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plants under existing conditions, some of which absorb and transform pollutants in the air and 

water, could reduce the amount of pollution absorbed/transformed, which would likely have 

direct adverse effects on water quality. 

2.3.7 Future Soils 

The ongoing conversion of wetlands to shallow open water under existing conditions would 

continue in the FWOP. The projected loss of wetlands in the study area is 131,091 acres over 

the 50-year period of analysis; this would include the loss of wetland soil types over this area. 

The Clovelly muck and Lafitte muck soil types would primarily be lost, with some loss of Fausse 

clay soils. Net primary productivity within the study area would continue to decline and existing 

wetland vegetation would continue to diminish. 

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 and Mississippi. The LCA Study 

(USACE, 2004) estimated coastal Louisiana would continue to lose land at a rate of 

approximately 6,600 acres per year over the next 50 years. It is estimated that an additional net 

loss of 328,000 acres may occur by 2050, which is almost 10 percent of Louisiana‘s remaining 

coastal wetlands. However, these wetland soil losses would be offset to some extent by 

restoration projects implemented through other programs. 

2.3.8 Future Barrier Island Resources 

Chandeleur and Breton Islands would continue to deteriorate without the implementation of a 

restoration program. It is projected that by 2014, Breton Island would have no remaining 

subaerial acreage and the entire Chandeleur Island chain (that includes Breton Island) would be 

completely eroded. Without the Chandeleur and Breton Barrier Islands, important gradients and 

ecotones would not exist in landward bays and wetlands, resulting in decreases in estuarine 

habitat complexity followed by decreases in species diversity and biomass (Hester et al., 2005). 

2.3.9 Future Coastal Vegetation Resources 

Marsh habitat would continue to be restored through other restoration projects and programs, 

such as the Coastal Wetlands Planning, Protection and Reservation Act (CWPPRA), the 

Coastal Impact Assistance Program (CIAP), and the Louisiana Coastal Area (LCA), but not at a 

magnitude to completely restore natural processes and features vital to the long-term success 

of the watershed. Without action, the coastal vegetation resources of the project area would 

continue to decline through bankline erosion, sloughing of the shoreline, and continued 

fragmentation and conversion of existing brackish and saline marsh to shallow open water 

habitats. Continuing adverse impacts to coastal vegetation would result from both human 

activities and natural processes including continued shoreline erosion and subsidence, 

increased saltwater intrusion, increased water velocities, and increased herbivory. 

2.3.10 Future Wildlife Resources 

Without an extensive ecosystem restoration plan, marsh habitat in the study area would 

continue to be restored through other restoration projects and programs, such as those 
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authorized for construction through CWPPRA, CIAP, and LCA; these projects would indirectly 

and cumulatively benefit wildlife, but not on a large enough scale to completely restore natural 

processes and features vital to the long-term success of the watershed. 

Habitat quality would decline as wetlands continue to deteriorate and fragment, specifically in 

the critical landbridges within the study area. As interior wetlands convert to open water, there 

would be an expected loss of species richness. The continued degradation and loss of wetland 

habitat would also likely result in a localized decrease in wildlife use of the area. In general, for 

most amphibians, reptiles, birds, and mammals, the fresh, intermediate, and brackish wetlands 

are required or preferred to open water habitats (Chabreck, 1988). 

2.3.11 Future Aquatic and Fisheries Resources 

The persistence of existing conditions, such as wetland fragmentation and emergent wetland 

loss, as well as, shoreline and bank line erosion contributing to the continued degradation of 

aquatic habitat would continue in the FWOP. Over time, this would result in a substantial 

decrease of habitat needed for support the life stages of numerous fish species, therefore 

reducing the area‘s ability to adequately support fishery resources. Distribution and abundance 

of aquatic organisms would likely decrease, indirectly impacting species linked in the food web 

to directly affected species. Reduction in emergent wetlands would result in shifts of 

predator/prey relationships, decline in fish productivity, and reduced recreational fishing 

opportunities. 

Continued restoration of emergent marsh and shoreline habitat, authorized through programs 

such as CWPPRA, CIAP, and LCA, as detailed in chapter 2, would benefit aquatic and fishery 

resources; however, these programs would not be as beneficial on a large scale as the MRGO 

Restoration program, which would restore natural processes and features vital to long-term 

success of aquatic and fisheries resources. 

2.3.12 Future Storm Surge and Wave Conditions 

Water levels are expected to be similar or greater than existing conditions in the future. Because 

of the uncertainty and wide ranges inherent in sea level rise projections, the MsCIP and the 

LACPR efforts used scenarios to evaluate the effects of different relative sea level rise rates 

(eustatic sea level rise combined with subsidence) over a 50-year planning period. The relative 

sea level rise values used for the MsCIP scenarios were 0 feet, 2 feet, and 3.4 feet (USACE

2008b). The relative sea level rise values used for the LACPR scenarios were 1.3 feet and 2.6 

feet, and deltaic rates of 1.9 feet and 3.2 feet (USACE 2009). Because a variety of factors affect 

the height of storm surge, at this stage of scientific knowledge it is difficult to quantify the effect 

of wetland loss in the study area on storm surge. 

The IHNC Surge Barrier will alter flow patterns in and near the middle end of the study area 

(Lake Borgne and eastern Lake Pontchartrain). For construction of this structure, an access 

channel was dredged on the Lake Borgne side of the floodwall (USACE 2008c). Modeling 

indicates that the net effect will be negligible. The gates across Bayou Bienvenue and the 

GIWW would remain open, except when storm surge is anticipated. This configuration would 

prevent salt-water intrusion into the Central Wetlands in storm situations, while not impeding 
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tidal flows under normal circumstances. The concrete surge barrier across the MRGO channel 

south of Bayou Bienvenue will stop tidal flow on the channel, but the closure structure at Bayou 

La Loutre has a greater impact on non-storm flows in the MRGO. Nevertheless, the water flows 

near the sector gates are anticipated to be greater than preconstruction conditions. Additionally, 

modeling scenarios indicate that the Chalmette Loop Levee would raise the water levels by up 

to 0.1 foot (0.03 meter), with marshes experiencing up to 7 hours of additional wetted period per 

day (USACE 2008c).

2.3.13 Relative Sea Level Rise Scenarios 

Recent climate research by the Intergovernmental Panel on Climate Change (IPCC) predicts 

continued or accelerated global warming for the 21st Century and possibly beyond, which will 

cause a continued or accelerated rise in global mean sea level. Subsidence of the deltaic 

sediments which characterize the study area is an ongoing process that will continue to 

contribute to relative sea level rise. Marsh accretion is a mechanism which allows marshes to 

keep pace with relative sea level rise through organic and inorganic sediment accumulation. 

Coastal marshes may accrete at a rate that keeps pace with a slow rate of sea level rise; 

however, as the rate of sea level rise increases, coastal mashes cannot maintain their elevation, 

and they submerge and are transformed to open water. Some Louisiana marshes are able to 

survive current sea-level rise conditions; increased sea-level rise may approach or cross this 

critical threshold (USGS website).Engineering Circular No. 1165-2-211 dated July 1, 2009, 

provides USACE guidance for incorporating the direct and indirect physical effects of projected 

future relative sea level rise in managing, planning, engineering, designing, constructing, 

operating, and maintaining USACE projects. The National Research Council‘s 1987 report 

Responding to Changes in Sea Level: Engineering Implications recommends a multiple 

scenario approach to deal with key uncertainties for which no reliable or credible probabilities 

can be obtained. In the context of USACE planning, multiple scenarios address uncertainty and 

help to develop better risk-informed alternatives. The final array of alternatives were evaluated 

using ―low,‖ ―intermediate,‖ and ―high‖ rates of future relative sea level rise for both ―with‖ and 

―without‖ project conditions as shown in Table 2-3. 

Table 2-3. Relative Sea Level Rise Projections Over the Period of Analysis 

Scenario Based On RSLR 

Low Historic rates 1.8 feet 0.55 meters

Medium NRC Curve I 2.2 feet 0.69 meters

High NRC Curve III 3.7 feet 1.12 meters

The ―high‖ rate exceeds the upper bounds of IPCC estimates from both 2001 and 2007 to 

accommodate for the potential rapid loss of ice from Antarctica and Greenland. 

Wetland Acreage Predictions under Increased SLR Rates 

For the medium and high scenarios, the future wetland loss rates were increased to simulate effects 

of increased wetland submergence. Using predicted future water levels (based on the Shell Beach 

gage) under medium and high sea-level rise scenarios, those water levels were converted into 

relative sea level rise (RSLR) rates, assuming that those water levels incorporate both subsidence 
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and sea level rise effects. By subtracting the average accretion value of 7.4 mm/yr (an average of 

accretion measurements obtained throughout the project area), from the year 2011 baseline RSLR 

rate of 10.24 mm/yr, a net baseline submergence rate of 2.84 mm/yr was calculated. Likewise, the 

7.4 mm/yr average accretion value was subtracted from predicted future submergence rates under 

both the medium and high SLR scenarios. To calculate future wetland loss rates under increased 

SLR scenarios, the baseline wetland loss rate, in acres lost per year, was multiplied by the year X 

submergence rate ratio (i.e., Submergence Rate Year X/Submergence Rate Year 2011). 

Based on research conducted at the Madison Bay wetland loss hotspot in the Terrebonne Basin, it 

appears that when submergence reaches a certain critical threshold, plant productivity decreases 

rapidly and the marsh undergoes a rapid loss or collapse, when there is there inadequate sediment 

accretion to counter submergence. According to (Nyman et al. 2006), that threshold is 10 mm/yr. 

Under the high SLR scenario, this submergence threshold is reached in year 2023. It was assumed 

that once that threshold was reached, the marsh would undergo rapid collapse and be totally 

converted to open water in 10 years. Consequently, under the high SLR scenario, marshes not 

receiving additional sediment would totally disappear by year 2033. 

2.4 PROBLEMS AND OPPORTUNITIES 

The first step in the planning process is the identification of problems and opportunities. 

Problems are undesirable conditions that the study will attempt to improve. Opportunities are 

desirable conditions that could be achieved in the future. Study area problems and opportunities 

were drawn from prior comprehensive planning studies and from public input and inter-agency 

information exchange. 

System-wide problems and opportunities were used to identify and define more geographically 

specific problems and opportunities throughout the study area. Through the NEPA public 

scoping process, the study team solicited input on problems and opportunities from members of 

the public, government resource agencies, and other stakeholders. A discussion of general 

study area problems and opportunities follows. The study area was divided into subunits and 

problems were documented on a subunit basis. Section 2.6, Evaluation of Management 

Measures, describes how study area opportunities were developed into management measures 

for each subunit. 

2.4.1 Study Area Problems 

The main water resource problems identified in the study area are as follows: 

• Land loss

• Bank/shoreline erosion;

• Habitat change and loss;

• Modification of natural hydrology;

• Decreased freshwater, sediment, 

and nutrient inputs;

• Saltwater intrusion;

• Retreating and eroding barrier islands

• Ridge habitat degradation and 

destruction

• Invasive species;

• Herbivory; and

• Increasing susceptibility of coastal 

communities to storm surge.
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Figure 2-9. System-Wide Problems and Potential Management Measures 
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A conceptual ecological model was developed to illustrate the stressors and drivers of the system. 

 Figure 2-10. Conceptual Ecological Model 
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Coastal Land Loss 

As previously described in the sections on existing and FWOP conditions, 

perhaps the most serious and complex problem in the study area is land loss. 

Land loss is a critical problem not only because of ecosystem degradation but also because of 

its role in increasing susceptibility of coastal communities to storm surge. Relative sea level rise, 

tropical storms, shoreline erosion, modification of natural hydrology, and other factors contribute 

to land loss in the study area. Coastal ecosystem sustainability is threatened by the inability of 

many wetlands to maintain their surface elevation. Alterations which allow marsh soils to be 

excessively waterlogged cause soil chemical changes stressing even the most resilient marsh 

plants. Plant stress can lead to mortality. Once plants die, roots no longer provide structure and 

integrity to hold marsh soils, and land loss results. 

Bank/Shoreline Erosion 

Tropical storms and wind driven waves cause erosion. Navigation channels 

subject inland areas to more dramatic tidal forces and wave action, increasing 

erosion. Rims of firmer soil around lakes, bays, and natural ridges along 

waterways are susceptible to wind-induced erosion. When these firmer soils are eroded away, 

organic marsh soils are directly exposed to open water wave attack. 

Figure 2-11. Fragmented Marsh Separating Lake Borgne from the MRGO. 

Fort Proctor (bottom left), an historic pre- Civil War era fort was originally constructed on land but is now 

surrounded by Lake Borgne. 
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Habitat Change and Loss 

Habitat diversity is important for a healthy ecosystem. Erosion, storm surge 

inundation, and salinity changes from decreased freshwater inputs or saltwater 

intrusion can cause habitat changes and habitat loss (Figure 2-12). In some 

areas (such as the Central Wetlands), loss of habitats with high friction factors, such as swamp 

forests, can lead to higher storm surge risk. 

Figure 2-12. Potential Pathways of Change among Habitats and the Associated Driving Forces 

(Source: CLEAR) 

Modification of Natural Hydrology 

Construction of levees, oil and gas canals and navigation channels has altered 

natural hydrology, affecting freshwater, sediment, and nutrient transport. 

Dredged material spoil banks block the movement of sediment re-suspended 

during storms. Hurricanes play a major role in sediment transport and sustaining 

land elevations in coastal wetlands (Reed et al. 1997). Hurricanes can also result in massive 

land loss. Channels and canals promote saltwater intrusion and increase tidal processes that 

impact the marsh by accelerating erosion. Canals impede sheetflow and cause ponding of water 

on the marsh. Because of the presence of dredged material banks, partially impounded areas 

experience fewer but longer periods of flooding and reduced water exchange when compared to 

unimpounded marshes (USACE 2004). This impoundment results in increased waterlogging 

and frequently in plant death. 

Hypoxic/anoxic conditions (―dead zones‖) occur in Lake Pontchartrain and the Gulf of Mexico. 

These conditions are caused primarily by excess nitrogen in combination with stratification of 

more saline waters. Due to the control of the Mississippi River, nutrients pass though the study 

area and into the northern gulf, rather than into adjacent wetlands, which would absorb these 

nutrients. 
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Decreased Freshwater, Sediment and Nutrient Inputs 

The construction of levees along the Mississippi River and its distributaries has eliminated the 

periodic floods that provided vital freshwater, sediment and nutrients to the 

study area. These flood control measures have seriously altered 

hydrogeomorphic, biogeochemical, and ecological processes. Without inputs of 

freshwater, sediment and nutrients, coastal land loss is accelerated and natural 

subsidence is exacerbated. 

Saltwater Intrusion 

Saltwater intrusion changes salinity gradients in estuaries, resulting in habitat 

shifts. 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, channels and canals, and drainage systems. Tropical storms can 

introduce saltwater into fresher areas, damaging large amounts of habitat in a short period of 

time. 

Retreating and Eroding Barrier Islands 

The barrier islands in the Louisiana portion of the study area are the remains of 

an abandoned Mississippi River Delta lobe; and their degradation is the result of 

the natural deltaic processes. The formation of Cat Island in Mississippi was also 

influenced by this abandoned delta, and it is distinct from other Mississippi 

barrier islands (Schmid 2001). Barrier islands act as buffers 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 66 feet per year. According to recent 

U.S. Geological Survey (USGS) 

estimates, several islands will disappear 

by the end of the century (USACE 2009). 

Although Cat Island has lost 39% of the 

land area it had in 1848, it is the most 

stable of the Mississippi barrier islands. 

Interior elevations and the orientation of 

Cat Island prevent breaching and 

overwash by storm waves except along 

spits of the eastern shore (Morton 2007). 

Figure 2-13. Aerial view of Breton Island (2009) 
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Ridge Habitat Degradation and Destruction 

Natural levees are ridges formed from sediments delivered over the banks of 

rivers and bayous during floods. These ridges assist in defining a watershed and 

in maintaining its natural hydrology. Ridges sustain upland shrubs and trees, 

providing unique habitat for certain plant and animal species, such as birds and mammals. 

Intact ridges prevent intrusion of saltwater into fresher marsh. Natural factors such as 

subsidence have contributed to the loss of the ridges. The construction of the MRGO directly 

affected the Bayou La Loutre ridge by cutting the channel through the ridge. 

Invasive Species 

The aggressive spread of invasive species decreases native plant communities, 

rapidly altering ecosystem function. For instance, Chinese tallowtree (Triadica 

sebifera, formerly Sapium sebiferum), an invasive species found in the study area, 

can establish self-replacing monocultures that provide less value to the foraging of migrating 

avian species. Disturbed ecosystems are more vulnerable to invasive species than stable 

ecosystems: therefore, invasive species are a severe threat to biodiversity and ecological 

function in the study area. 

In the study area, water hyacinth (Eichhornia crassipes), alligator weed (Alternanthera 

philoxeroides), and hydrilla (Hydrilla verticilata), common salvinia (Salvinia minima), giant 

salvinia (Salvinia molesta), and variable-leaf milfoil (Myriophyllum heterophylum) are invasive 

aquatic vegetative species, displacing native aquatics and degrading water and habitat quality 

(USACE 2009). Chinese tallowtree and sea-side cedar (Tamarix gallica) interrupt natural 

succession of native prairie, scrub-shrub and woody species because of their tolerance to 

flooding and salt stress (USACE 2009). Cogongrass (Imperata cylindrica) is a fast-growing 

perennial grass that is infesting Gulf coast wetlands, savannas, and forests (USACE 2009).

Herbivory 

During the 1930s, nutria (Myocastor coypus) were accidentally released into the 

coastal wetlands. Their population has rapidly expanded and their grazing and 

foraging for plant roots have been a major contributor to wetland losses (USACE 

2009). Although native, rather than an introduced species, muskrat eat-outs may also result in 

significant local impacts to area marshes. Eat-outs may recover under some conditions, tropical 

storm impacts on an eat-out area may overnight convert such an area to permanent open water 

conditions (USGS 2000). 

Increasing Susceptibility of Coastal Communities to Storm Surge 

The levees and floodgates that allowed increased development in coastal areas 

also contribute to subsidence and wetland loss. Continued land loss and 

ecosystem degradation cause developed areas to become more susceptible to 

storm surge, threatening communities and valuable infrastructure. 
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2.4.2 Study Area Opportunities 

For each of the problems described in the previous section opportunities to improve future 

conditions were identified. Table 2-4 shows the linkages between study area problems and 

ecosystem restoration opportunities. 

Table 2-4. System-Wide Study Area Problems and Opportunities 

Problems Opportunities

Decreased Freshwater, 

Sediment, and Nutrient 

Inputs

Increase sediment, freshwater, and nutrient inputs Increase organic 

deposition.

Modification of Natural 

Hydrology

Restore altered tidal circulation patterns and improve water quality.

Saltwater Intrusion Prevent saltwater intrusion.

Wetland Loss Create wetlands, nourish, and prevent the continued loss of wetlands. 

Ridge Habitat Degradation 

and Destruction

Restore ridge habitat.

Bank/Shoreline Erosion Prevent bank and shoreline erosion.

Habitat Changes and Loss Restore habitat types such as swamps, ridges, submerged aquatic 

vegetation, oyster reefs, and barrier islands.

Invasive Species Eliminate or reduce invasive species.

Herbivory Prevent herbivory.

Retreating and Eroding 

Barrier Islands

Restore barrier islands.

Human Development 

Susceptible to Storm Surge

Reduce or prevent storm surge damage through restoration of natural 

ecosystem features.
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Figure 2-14. Study Area Potential Management Measures 
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2.4.3 Identification of Management Measures 

A management measure is a feature (a structural element that requires construction or 

assembly on-site) or an activity (a nonstructural action) that can be combined with other 

management measures to form alternative plans. Management measures were developed to 

address study area problems and to capitalize upon study area opportunities. Management 

measures were derived from a variety of sources including prior studies, the NEPA public 

scoping process, and the multidisciplinary, interagency PDT. The structural management 

measures considered can be grouped into the following categories: 

 Freshwater diversions 

 Hydrologic restoration (e.g. plugs, fill, weirs, sills) 

 Vegetative plantings 

 Marsh restoration, marsh nourishment, and swamp restoration 

 Shore protection 

 Ridge restoration 

 Restoration of forested habitat 

 Barrier island restoration 

 Submerged aquatic vegetation (SAV) restoration 

 Oyster reef restoration 

WRDA 2007 Section 7013 states that the study should undertake ―efforts to integrate the 

recommendations of the report with the program authorized under section 7003 [LCA] and the 

analysis and design authorized by title I of the Energy and Water Development Appropriations 

Act, 2006 (119 Stat. 2247) [LACPR]‖. Therefore, restoration features located in the study area 

proposed in LCA and LACPR were included in the initial evaluation of management measures. 

In addition, the following nonstructural measures were considered: invasive species control; 

herbivory control; and buy-outs of developed areas for ecosystem restoration purposes. 

Invasive species control and herbivory control measures will be further considered in 

conjunction with structural measures as detailed designs and implementation plans are 

developed. Buy-outs of developed areas were not deemed necessary for the plan because of 

the large extent of non-developed areas available for restoration purposes. 

2.4.4 Descriptions of Measures by Type 

The section describes the types of measures that were identified to address study area 

problems and opportunities. The specific measures considered and the initial screening process 

as applied to each group of management measures is described in Section 2.6.2. 
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Freshwater Diversions 

Freshwater diversion features could address the following study area problems: 

decreased freshwater, sediment, and nutrient inputs; modification of natural 

hydrology; saltwater intrusion; habitat changes and loss; wetland loss; and human development 

susceptible to storm surge. Diverting freshwater from the Mississippi River into the study area 

could nourish existing marshes to increase their productivity and build wetlands, maintain and 

restore salinity gradients, and reintroduce and distribute sediment and nutrients throughout the 

ecosystem. The benefits that diversions produce increase over time and continue as long as the 

diversion is operated and maintained. In addition, diversion operations can be adaptively 

managed to respond to environmental changes and optimize benefits. Figure 2-15 shows the 

Mississippi River Diversion at Caernarvon. 

Hydrologic Restoration 

Measures 

Hydrologic restoration measures could 

address the following study area 

problems: modification of natural 

hydrology; saltwater intrusion; and 

habitat changes and loss; and human 

development susceptible to storm 

surge. Hydrologic restoration can be 

achieved through backfilling, plugging, 

or creating gaps in the banks of canals 

and channels. The construction of 

water control structures, such as weirs 

and sills, can also restore natural 

hydrology. Several channels and canals 

within the Louisiana portion of the study 

area were identified during the scoping 

process for potential backfilling, 

plugging, installing water control structures (such as weirs and sills), or bank gapping. Bank 

gapping can be used to help restore natural hydrology and provide nutrients and sediment to 

facilitate organic deposition, improve biological productivity, and prevent further habitat 

deterioration (USACE 2004). Weirs and sills provide partial closure and aid sedimentation and 

salinity control. Backfilling can serve the dual purpose of water control and land building 

(depending upon the depth of fill). Plugging can be accomplished with lateral fill or full closure 

structures. Plugging methods are primarily water control structures and do not provide the land 

creation benefits of backfilling. Plugging, however, is usually a substantially less expensive 

option than backfilling. 

Vegetative Planting 

Vegetative planting features could address the following study area problems: habitat 

changes and loss; wetland loss; herbivory, invasive species; and human development 

susceptible to storm surge. One way to address habitat loss is through planting appropriate 

Figure 2-15. Caernarvon Freshwater Diversion
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native species in areas that already have the necessary elevation to maintain a particular 

habitat. of restore and rebuild wetlands. Vegetated habitat will provide the following benefits: 

combat subsidence; reduce breaching and erosion; reduce wave fetch from open water areas; 

and allow for more vertical accumulation of vegetation. 

Marsh Restoration and Marsh Nourishment 

Marsh restoration and nourishment features could address the following 

study area problems: habitat changes and loss; wetland loss; herbivory, 

invasive species; and human development susceptible to storm surge. One way to address 

marsh loss is through the placement of dredged material to restore and rebuild wetlands. Marsh 

restoration involves the placement of dredged material in shallow open water areas and 

extensively broken marsh to raise the area to marsh elevation. Following compaction and 

dewatering, the area is planted with marsh vegetation. Retention dikes, deflection dikes, and/or 

closures may be used to contain material within the restoration area. Dredged material is 

allowed to overflow to nourish and consolidate existing marsh vegetation within the restoration 

area. 

Marsh nourishment refers to the placement of a thin layer of dredged material into broken 

marsh. The placement of this material facilitates the recruitment and consolidation of marsh 

vegetation after dewatering. Unlike marsh restoration features, no plantings are associated with 

marsh nourishment features. 

Newly restored or nourished marsh will provide the following benefits: add new sediment and 

nutrients to the system; combat subsidence; reduce breaching and erosion; reduce wave fetch 

from open water areas from previously broken marsh; and allow for more vertical accumulation 

of vegetation. 

Figure 2-16. Dredge Material Placement for Marsh Restoration 
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Swamp Restoration and Swamp Nourishment 

Swamp restoration and nourishment features could address the following 

study area problems: habitat changes and loss; wetland loss; herbivory, 

invasive species; and human development susceptible to storm surge. In 

addition to marsh restoration, there were additional suggestions to restore cypress swamp 

habitat in the study area. Swamp would be restored through the placement of dredged material, 

similar to marsh restoration features described above. Swamp restoration features would have a 

higher elevation than marsh restoration features to support cypress trees. 

Swamp nourishment is proposed for areas that are currently at marsh elevation, and consists of 

placing a thin layer of dredged material to nourish the area, raise elevation, and encourage the 

recruitment of cypress-tupelo community species. 

Figure 2-17. Dredge Piping Sediment from the Mississippi River to Restore Marsh 

Shoreline Protection 

Shoreline protection features could address the following study area problems: 

habitat changes and loss; wetland loss; and human development susceptible to 

storm surge. The prevention of shoreline erosion is essential to addressing the larger problem of 

coastal land loss. High water, wave action, wind induced currents, tidal flow, channel 

bathymetry, and tidal circulation can contribute to shoreline erosion. 
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Shoreline protection includes the placement of materials, such as sand, shell, or rock on-shore 

or off-shore. Construction methods included the establishment of artificial reefs and breakwaters 

off-shore as well as the placement of rock or sand on-shore. These measures dissipate wave 

energy and prevent shoreline erosion and land loss. 

Figure 2-18. Example of Onshore Placement of Rock for Shoreline Protection 

Figure 2-19. Example of Offshore Placement of Rock for Shoreline Protection 
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Ridge Restoration 

Ridge restoration features could address the following study area problems: habitat 

changes and loss; wetland loss; herbivory, invasive species; human development 

susceptible to storm surge; and ridge habitat degradation and destruction. Historically, ridges 

were formed as natural levees of major and minor distributary channels that diverge from larger 

distributaries as they trend toward the outer coast. Deposits of mostly linear dredged material 

along the coast may also be considered ridges if they mimic natural levees. Natural ridges in the 

study area include the Bayou La Loutre ridge and the Bayou Terre aux Boeufs ridge. Several 

reaches of the Bayou La Loutre and Bayou Terre aux Boeufs ridges were proposed for 

restoration as part of the initial array of measures considered. Ridge restoration would consist of 

the placement of dredged material to a height suitable for upland habitat. Various footprints 

were evaluated for several reaches of these historic ridges. 

Restoration of Forested Habitat 

Restoration of forested habitat could address the following study area 

problems: habitat changes and loss; wetland loss; herbivory, invasive 

species; human development susceptible to storm surge; and ridge habitat 

degradation and destruction. Measures to restore forested habitat include planting woody 

vegetation. Vegetative planting measures were developed as standalone measures on existing 

spoil banks and in conjunction with other measures such as ridge restoration and swamp 

restoration. These measures may contribute to storm surge risk reduction. 

Forests are an important resource in the study area and provide important habitat for resident 

and migratory birds. Wetland and upland forested habitat historically found in the study area has 

decreased. During public scoping meetings, measures to restore forest habitat were suggested. 

Barrier Island Restoration 

Barrier island restoration could address the following study area 

problems: retreating and eroding barrier islands; habitat changes and 

loss; and wetland loss. Barrier island restoration was considered for all 

barrier islands in the study area. These measures may contribute to storm surge risk reduction 

and salinity control. Barrier Islands in the study area consist of the Chandeleur Chain (including 

Chandeleur Island and Breton Island) and Cat Island (located between the Mississippi Sound 

and the Chandeleur Sound). Restoration of these islands was proposed as part of the initial 

array of measures considered. 

Through LACPR and MsCIP, the contribution of surge reduction provided by the barrier islands, 

in their historic, existing, and altered states, has been subject to sensitivity analyses. The 

reports indicate that some surge reduction is realized by the barrier islands. Additional benefits 

were also predicted by creating longer and higher islands. It can only be speculated as to how 

much actual damage reduction the barrier islands provide, but the disappearance of the barrier 

islands provides the means for a dramatically increased wave climate, along the coasts of 

Mississippi and Louisiana. 
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Submerged Aquatic Vegetation (SAV) Pilot Projects 

Submerged Aquatic Vegetation (SAV) restoration could address the habitat changes 

and loss problem in the study area. SAV beds improve water quality and provide 

other ecosystem function benefits such as increased habitat availability for critical fisheries 

resources. Worldwide, SAV coverage has been declining. For example, in 1969, an estimated 

20,000 acres of SAV were documented in Mississippi Sound and coastal bays. As of 1998, only 

2,000 acres were documented (Moncrieff et. al. 1998). 

Submerged aquatic vegetation is an important component of the Lake Pontchartrain ecosystem. 

Presently, there are few areas where SAV is present, most of which are along the northshore 

(Cho and Poirrier 2005). Salinity level and water clarity have been determined to be two of the 

main factors that affect SAV in the Lake (Cho and Poirrier 2005). 

During public scoping meetings, pilot projects to investigate various methods of SAV planting in 

the Mississippi Sound and in Lake Pontchartrain were suggested. SAV restoration measures 

are presented as pilot projects because of uncertainties surrounding the re-establishment of 

SAV beds. For example, it is unknown if efforts to create habitat conditions that are suitable for 

SAV are sufficient for restoration or if more targeted approaches, such as planting, would also 

be necessary to re-establish SAV beds. 

Oyster Reef Restoration 

Oyster reef restoration features could address the following study area problems: 

habitat changes and loss; wetland loss; and human development susceptible to storm 

surge. The establishment of oyster reefs in the Biloxi Marshes was suggested during 

public scoping meetings. Generally, oyster communities are a part of the Lake Borgne 

ecosystem and some reef designs could dissipate wave energy and thus prevent shoreline 

erosion or land loss and contribute to storm surge risk reduction. 

Oyster reefs were considered both for oyster production and shoreline protection purposes. 

Three alternative designs for oyster reefs were evaluated as shoreline protection measures, i.e., 

a bio-engineered reef, using crushed stone, or incorporating a berm for oysters in addition to a 

traditional rock shoreline protection measure. These measures demonstrate the opportunity to 

incorporate benefits for oysters into shoreline protection designs. 

2.4.4.1 Risk and Uncertainty Associated with Restoration Measure Types 

All restoration measure types are subject to the general risks and uncertainties discussed in 

Section 2.5.4. Risk is considered to be the product of the likelihood of project failure and the 

consequences of that failure. Uncertainty is the lack of surety inherent in any future-oriented 

planning effort and is the result of incomplete and inadequate information about future 

conditions. The following section discusses specific risks for each restoration measure type. 

Freshwater Diversion

The diversion of significant quantities of river water typically leads to unintended consequences, 

such as sedimentation and shoaling in the main river downstream of the diversion and 
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sedimentation in interior distribution channels after the flow is diverted. The likelihood of 

shoaling and sedimentation is moderate. The consequences of shoaling and sedimentation are 

higher maintenance costs, which would decrease the cost effectiveness of the measure. 

Specific risks and uncertainties associated with relative sea level rise in the formulation of 

freshwater diversion plans include a loss of benefits, changes in assumed conditions, and 

inadequate structure design. The consequences of inadequate structure design could be 

significant. To limit the likelihood of plan failure, increased relative sea level rise is incorporated 

into the design of freshwater diversion structures. 

The SAND2 (Sediment and Nutrient Diversion) method uses sediment and nutrient inputs to 

predict accretion rates in areas affected by freshwater diversions. Ideally, sediment loads in the 

river at proposed diversion sites would be used in these calculations. Due to data limitations, the 

known data from the Tarbert's Landing was used in the analysis of these features. There is 

some uncertainty associated with not using site-specific data for the analysis. However the risk 

is minimal because the data being used came from a nearby station and the sites that were 

evaluated appear to occur in areas of higher sediment concentration in the Mississippi River. 

SAND2 uses the average water depth of the project area along with the sediment load 

introduced into the area from the river to project future acres of marsh restored and nourished. 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. 

The implementation of other authorized and planned freshwater diversions is uncertain. 

Freshwater diversion alternative plans will consider the potential impacts of other freshwater 

diversion, while being formulated to produce benefits independent of other diversions. It is very 

likely that the assumptions made in this study regarding other authorized and planned 

freshwater diversion projects will be inaccurate. However, by developing freshwater diversion 

alternatives that produce benefits independent of other plans, the consequences of this risk are 

decreased. 

Uncertainties associated with river water constituents that may have unintended consequences 

include: increased total suspended sediments, turbidity, and organic/nutrient enrichment of the 

water column; disturbance and release of possible contaminants; decrease in water 

temperatures; and the possible release of oxygen depleting substances (organic or anaerobic 

sediments) as well as possibly decreasing dissolved oxygen (DO) levels. These impacts would 

be minimized to the extent practicable through the implementation of stormwater pollution 

prevention plans (SWPPPs), the ITM protocols, and other applicable best management 

practices (BMPs). The likelihood that river water constituents may have unintended effects is 

moderate. However, the consequences of these effects are likely to be temporary and localized 

in nature, and therefore are unlikely to significantly affect overall project success. 

Hydrologic Restoration Measures

Restoration of hydrologic function can result in unexpected changes to circulation, salinity and 

water quality. Relative sea level rise could result in changes in assumed conditions, which could 
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decrease the benefit of hydrologic restoration measures. The likelihood of failure associated 

with these risks is low, if sufficient analyses are conducted using accurate information. 

Marsh Restoration and Marsh Nourishment 

Marsh restoration and nourishment measures are susceptible to tropical storms, wind-driven 

erosion, the effects of increased relative sea level rise, saltwater intrusion, herbivory, invasive 

species, and lack of freshwater and nutrients. These problems contribute to the need for 

restoration, while posing the greatest risks to their success. Marsh restoration measures in 

interior areas are less susceptible to these risks than areas exposed to open water. However, 

without the restoration and protection of areas adjacent to open water, interior marshes will 

become increasingly exposed to these forces as the exterior marsh degrades. 

It is very likely that one or more of these risk factors will affect project performance, with a 

moderate risk of project failure. The consequences of these risks can be complete or partial 

project failure and loss of investment. However, the consequences of failure must be considered 

on an individual project basis and include an analysis of the consequences of no action. The 

effects of these risks were minimized by incorporating lessons learned from previously 

constructed projects in the formulation of alternatives and incorporating these risk factors into 

the calculation of benefits. 

Swamp Restoration and Swamp Nourishment 

Saltwater intrusion and unsuitable water levels are the greatest risks associated with cypress 

swamp restoration. Therefore, these features were only planned for areas where salinity and 

water levels can be controlled to some extent (inside the levee system). The location of cypress 

swamp features inside of the levees significantly reduces the likelihood of failure. 

 Invasive species and herbivory are also a threat to cypress swamp restoration. Chinese tallow 

trees could out-compete native species and herbivory could destroy juvenile and newly 

established trees. Implementation methods for these features would incorporate controls to 

prevent loss of benefits from invasive species and herbivory. 

Shoreline Protection 

Subsidence, sea level rise, wave action, inaccurate or incomplete data, and design failures are 

the primary risks associated with shoreline protection features. Subsidence and wave energy 

are unavoidable, and therefore must be carefully considered in the design of alternative 

measures to avoid unacceptable consequences. Inaccurate or insufficient survey data or human 

error could result in design failures, reducing the effectiveness of these features. Appropriate 

maintenance and repair of these features contribute to project success. The likelihood that one 

or more of these factors will affect project performance is moderate. The consequences of 

failure could result in a significant or total loss of benefits. 
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Ridge Restoration 

Lack of technical knowledge is a risk associated with ridge restoration features. Very few 

coastal ridge restoration projects have been constructed, and there is limited data to contribute 

to the successful design and implementation of these features. The lack of knowledge could 

jeopardize project success, and the consequences of failure could result in a significant or total 

loss of benefits. 

In addition to the technical challenges of coastal ridge restoration, other factors threaten the 

success of these projects. Tropical storms, subsidence, sea level rise, saltwater intrusion, and 

invasive species are risks that can jeopardize the success of ridge restoration measures. The 

likelihood of failure due to these factors is moderate. The consequences of failure would be a 

partial or total loss of benefit. However, the consequences of failure must be considered on an 

individual project basis and include an analysis of the consequences of no action. 

Restoration of Forested Habitat 

Invasive species and herbivory are risks associated with forested habitat restoration. Chinese 

tallow trees could out-compete native species and herbivory can destroy juvenile and newly 

established trees. Implementation methods for these features would incorporate controls to 

prevent loss of benefits from invasive species and herbivory to reduce risk. 

Barrier Island Restoration 

The primary risk associated with barrier island restoration is significant loss of benefits due to 

erosion and tropical storm events. Because these measures are exposed to the open Gulf, 

losses to wave energy can be significant. These risks are unavoidable and are inherent to the 

changeable nature of these geographic features. The consequences of these risks can be 

complete project failure and loss of investment. Additionally, the opportunity cost of investing in 

a higher-risk restoration measure when a lower-risk measure could have been implemented 

must also be considered. However, the consequences of project failure must be balanced with a 

consideration of the consequences of no restoration. 

Submerged Aquatic Vegetation (SAV) Pilot Projects 

Lack of technical knowledge is a limiting factor for SAV features. Very few SAV restoration 

projects have been constructed, and there is limited data to contribute to the successful design 

and implementation. SAV are also fragile components of the ecosystem that are very 

susceptible to storm events. Given these limitations, the likelihood of failure is moderate to high. 

The consequences of failure are a partial or total loss of benefit and investment. The opportunity 

cost of investing in a higher-risk restoration measure when a lower-risk measure could have 

been implemented must be considered with the consequences of no action. 

Oyster Reef Restoration 

There is limited data on oyster reef restoration success as a means of shoreline stabilization 

and erosion prevention. The lack of data on oyster reef development for structural purposes is a 
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risk to the successful design and implementation of these features. Climate change, saltwater 

intrusion, and over-freshening also present a risk to the successful implementation of oyster reef 

restoration. If habitat conditions are not conducive to the propagation of oysters, the measures 

would be ineffective. It is moderately likely that these risks will result in project failure, and the 

consequences would be a partial or total loss of benefit and investment. 

2.4.5 Planning Subunits 

For planning purposes, the study area has been divided into subunits as shown in Table 2-5 

and Figure 2-20. Subunits classified as fastlands (agricultural, developed, and upland areas that 

do not have direct and significant impacts on coastal waters) do not function as part of the 

estuarine Lake Borgne ecosystem. These fastland areas are not targeted for ecosystem 

restoration in this study (LOSR 2002). 

Table 2-5 also describes the relevance of each subunit to the MRGO study and how problems 

and opportunities were addressed in each subunit. Problems are further described in Table 2-6 

for those subunits in which initial plan features were developed. 

The initial determination whether restoration features should be developed in a subunit were 

based on the study authority. The study authority indicates that the plan would ―physically 

modify the Mississippi River-Gulf Outlet and restore the areas affected by the navigation 

channel‖. Therefore, if a subunit was adjacent to the MRGO or considered potentially affected 

by the construction, operation, or maintenance of the channel, problems and opportunities were 

identified in those subunits. 

The study authority also mandates the development of ―a plan to restore natural features of the 

ecosystem that will reduce or prevent damage from storm surge‖. To address this portion of the 

authority, if a subunit was identified as a critical landscape feature in LACPR and was located in 

either the areas potentially affected by the MRGO or the Lake Borgne ecosystem, management 

measures were developed in those subunits. 

The study area was interpreted to include the greater Lake Borgne ecosystem, because the 

authority also states that the plan should include: ―consideration of...diversions of fresh water to 

restore the Lake Borgne ecosystem‖. This interpretation is consistent with the study 

Implementation Guidance dated 28 April 2009. The Lake Borgne ecosystem was defined as 

areas hydrologically connected to Lake Borgne. Table 2-5 describes the relevance of each 

geographic subunit to the MRGO Ecosystem Restoration Plan. 
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Figure 2-20. Study Area Subunit
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Table 2-5. Subunits by Geographic Area and Their Relevance to the MRGO Ecosystem Restoration Plan

(ID) Subunit Name Relevance of Subunit to MRGO Plan

Lake Maurepas and North Lake Pontchartrain

(16) East Lake Maurepas Identified as a critical landscape feature for storm surge risk 

reduction in LACPR. Measures were initially developed to 

address ecosystem restoration problems but were screened out 

because initial investigations indicated that the benefits of these 

features were minimal based on historic shoreline erosion and 

land loss rates. Habitat changed from cypress swamp to 

intermediate marsh on the Eastern Lake Maurepas Landbridge 

can be attributed to increased salinity caused by the MRGO.

However, because these areas have relatively low land loss 

rates, the benefits of restoration in this area are comparatively 

low.

(50) West Lake Maurepas Landbridge

(48) Tchefuncte River Mouth 

Tate et al. 2002 indicates that the MRGO contributed to salinity 

increases as far west as Pass Manchac. Therefore, the MRGO 

may have contributed to increased salinity in areas 

hydrologically linked to Lake Maurepas. MRGO effects related 

to saltwater intrusion are partially addressed by the MRGO 

closures and are anticipated to be fully addressed by other 

authorized projects (Convent/Blind, Amite and Hope 

Canal/Maurepas Swamp freshwater reintroductions).

(47) Tangipahoa River Mouth

(49) Tickfaw River Mouth

(28) Lake Maurepas

(02) Amite River 

(08) Blind River 

(20) Hope Canal 

(09) Bonnet Carré

(25) LaBranche Wetlands

(33) Northshore Marshes

(29) Lake Pontchartrain

Lake Pontchartrain was affected by saltwater intrusion caused 

by the MRGO. Salinity effects are being addressed by the 

MRGO closures. Because it is an open water body, any 

problems, opportunities, or measures in the lake are linked to 

the nearest subunit. For example, Submerged Aquatic 

Vegetation Restoration in Lake Pontchartrain is linked to the 

(05) Bayou Sauvage subunit.

East Orleans Landbridge and South Lake Borgne

(36a) Pearl River Mouth – LA Subunits 36a, 17, and 05 are part of the Lake Borgne 

Ecosystem and are recognized as critical landscape features in 

LACPR. Subunit 40 was directly and indirectly impacted by the 

MRGO. Subunit 26 was indirectly affected by the MRGO. 

Because it is an open water body, any problems, opportunities, 

or measures in the lake are linked to the nearest subunit. The 

spatial integrity of the MRGO/Lake Borgne Landbridge was 

compromised by the construction of the channel. The 

maintenance of the form of the lake rim is needed to restore the 

estuary. Measures were developed to address subunit 

problems and opportunities.

(17) East Orleans Landbridge

(05) Bayou Sauvage

(26) Lake Borgne

(40) S. Lake Borgne

Central Wetlands

(13) Central Wetlands

Subunit 13 was directly and indirectly impacted by the MRGO. 

The channel was cut through the eastern portion of the subunit. 

Measures were developed to address subunit problems and 

opportunities.

IHNC/GIWW
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Table 2-5. Subunits by Geographic Area and Their Relevance to the MRGO Ecosystem Restoration Plan

(ID) Subunit Name Relevance of Subunit to MRGO Plan

(22) IHNC/GIWW

More saline water entered these navigation channels via the 

MRGO. These areas are being considered as potential borrow 

sites.

MRGO 

(32) MRGO Spoil Bank Subunit 32 was directly affected by the dredging and placement 

of material during the construction of the channel.

(31) MRGO Offshore MRGO effects addressed by deauthorization of channel, natural 

shoaling.

Biloxi Marsh

(07) Biloxi Marshes Interior Subunits 07 and 18 were directly and indirectly impacted by the 

MRGO. Subunit 06 is adjacent to the Lake Borgne ecosystem 

and the offshore portion of the MRGO was dredged in the 

vicinity. Measures were developed to address subunit problems 

and opportunities.

(06) Biloxi Marshes Exterior

(18) Eloi Bay

Barrier Islands

(14) Chandeleur Islands Subunits 14 and 15 are adjacent to the Lake Borgne ecosystem 

and the offshore portion of the MRGO was dredged in the 

vicinity. Potential borrow sites. An offshore portion of the MRGO 

was dredged in subunit 10. Impacts of MRGO are addressed by 

deauthorization of channel and natural shoaling.

(15) Chandeleur/Breton Sound

(10) Breton/Grand Gossier Islands

Florissant

(19) Florissant

Subunit 19 was indirectly impacted by the MRGO through the 

placement of spoil material and hydrologic changes. Measures 

were developed to address subunit problems and opportunities.

Terre aux Boeufs, Hopedale

(21) Hopedale Subunits 21 and 23 were indirectly impacted by the MRGO 

through the placement of spoil material and hydrologic changes.

Measures were developed to address subunit problems and 

opportunities.

(23) Jean Louis Robin

Mississippi Sound

(04) Bay St. Louis Part of the Lake Borgne ecosystem. Problems and 

opportunities addressed by MsCIP. (36b) Pearl River Mouth (Mississippi)

(51) Western Mississippi Sound Part of the Lake Borgne ecosystem. Problems and 

opportunities addressed by MsCIP. Potential borrow area.

Caernarvon

(11) Caernarvon North

(38) River aux Chenes Insufficient nexus to Lake Borgne ecosystem or MRGO.

(12) Caernarvon South

River Delta

(01) American Bay Insufficient nexus to Lake Borgne ecosystem or MRGO.

(39) River Delta
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Figure 2-21 illustrates the subunits that were affected by the MRGO and subunits in the Lake Borgne ecosystem. 

Figure 2-21. Areas Affected by the MRGO and Lake Borgne Ecosystem Subunits 
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Table 2-6.Problems in Initial Feature Subunits 

Problems

Decreased Freshwater, Sediment and Nutrient InputsHydrologic ModificationSaltwater IntrusionWetland LossRidge Habitat Degradation and DestructionBank and Shoreline ErosionHabitat Change and Land LossInvasive Species and HerbivoryRetreating and Eroding Barrier Islands

Lake Maurepas and North Lake Pontchartrain

(16) East and (50) Lake Maurepas 

Landbridge X X X X X X X

East Orleans Landbridge

(36a) Pearl River Mouth – LA, (17) East 

Orleans Landbridge, and (05) Bayou 

Sauvage

X X X X X X X

South Lake Borgne

(40) South Lake Borgne X X X X X X X X

Central Wetlands

(13) Central Wetlands X X X X X X

Biloxi Marsh

(07) Biloxi Marshes Interior and (18) Eloi 

Bay X X X X X X X X

(06) Biloxi Marshes Exterior X X X X X X X

Barrier Islands

(10) Breton/Grand Gossier Islands X X X

(14) Chandeleur Islands X X X

Florissant

(19) Florissant X X X X X X X X

Terre aux Boeufs, Hopedale

(23) Jean Louis Robin X X X X X

(21) Hopedale X X X X X X X X

The problem of the susceptibility of coastal communities to storm surge does not appear in the 

table because development in the study area generally occurs in the subunits classified as 

fastlands. The problems of invasive species and herbivory are combined in the table because 

both of those problems generally occur in the same subunits. 
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2.5 STUDY GOALS, CONSTRAINTS, AND OBJECTIVES 

Study goals, objectives, and constraints were developed to comply with the study authority and 

to respond to study area problems and opportunities. 

The planning team develops objectives and constraints based on those problems and 

opportunities. An objective is a statement of what an alternative plan should try to 

achieve, while a constraint is basically a restriction that the alternative plan should avoid. 

Objectives, as well as constraints, are written statements that should generally include 

the following four types of information: effect (the verb that expresses the intent to bring 

about an objective and not to violate a constraint); subject (what is to be changed for the 

better through meeting the objective or not changed through avoiding a constraint); 

location (often the study area, which defines where the objective is to be achieved); and 

timing and duration (often the study period of analysis, which define when and how long 

the objective is to be achieved or the constraint to be avoided). Developing specific, 

flexible, measurable, realistic, attainable, and acceptable objectives and constraints is 

critical to the success of the entire planning process. Objectives and constraints are used 

to guide information gathering, to help identify solutions and formulate alternative plans, 

to identify which plan effects will be evaluated, to compare the relative effectiveness of 

alternative plans, to assist in plan selection, and ultimately, in gauging the success of the 

plan implemented (ER 1105-2-100, E-3.a). 

2.5.1 Goals 

The overarching goals of the MRGO Ecosystem Restoration Plan are as follows: 

1. Restore the Lake Borgne ecosystem and the areas affected by the MRGO navigation 

channel. 

2. Restore natural ecosystem features that reduce or prevent storm surge. 

3. Achieve ecosystem sustainability to the greatest degree possible. 

2.5.2 Constraints 

Planning constraints include legal and policy constraints that are applicable to all Federal water 

resources planning efforts, as well as study-specific constraints. 

 Avoid or minimize negative impacts to threatened and endangered species to the 

extent practicable. 

 Avoid or minimize impacts to critical habitat to the extent practicable. 

 Do not diminish the level of protection provided by authorized flood risk reduction 

projects and hurricane storm damage risk reduction projects. 

 Avoid actions that negatively affect the ability of authorized navigation projects to 

continue to fulfill their purpose to the extent practicable. 

 Minimize impacts to commercial fisheries (such as oysters). 
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 Avoid or minimize contributions to low dissolved oxygen concentrations or conditions 

that could result in detrimental algal blooms. 

2.5.3 Challenges Associated with Limited Resources 

2.5.3.1 Sediment Replenishment and Borrow Source Suitability 

The majority of the study area is situated within the abandoned St. Bernard Delta of the 

Mississippi River. Active sedimentation related to delta growth ceased in this area over 1000 

years ago. Since delta abandonment, the processes of erosion and relative subsidence have 

dominated the landscape resulting in land loss and habitat switching. More recently, the 

construction of levees along the Mississippi River has eliminated the periodic floods that 

provided freshwater, sediment and nutrients to the study area. In addition, upstream reservoirs, 

changes in agricultural practices and land uses, and bank stabilization measures have reduced 

average sediment loads in the lower Mississippi River by approximately 67 percent since the 

1950s (Kesel 1988). Sediments in the Mississippi River that could be used to build land in 

critical areas are lost from the system once the River reaches the Gulf of Mexico. 

The surface and shallow subsurface of the study area is composed mainly of organic clay and 

clay. Coarser sediments are confined mainly to the Mississippi River and the Chandeleur 

Islands chain. As land areas erode, much of the material is oxidized or transported away via 

suspension. The remaining sediment is distributed throughout the marshes, bays, and lakes. 

Detailed investigations to quantify the distribution of eroded and transported sediments over this 

extensive study area have not been conducted to date. However, there are no significant land 

areas being formed within the study area from deposition of eroded marsh sediments indicating 

a net loss of material from the system. 

The USACE has developed a conceptual sediment study to determine the amount of sediment 

available for restoration efforts throughout coastal Louisiana. The purpose of this initial effort is 

to document what is known about present-day sediment transport processes and pathways, 

coastal and nearshore volume changes, and sources and sinks of sediment for the Louisiana 

coast. In the study area, the primary focus areas include the Mississippi River, Chandeleur 

Sound, portions of Breton Sound, and the Mississippi River birdsfoot delta. 

In addition to the Louisiana conceptual sediment study, USACE completed an initial study and 

comprehensive database of measured suspended solids in the lower Mississippi River (Thorne 

et al. 2008). This report indicates that the average annual load over the period 1963 to 2005 at 

one representative site on the lower river was approximately 150 million tons, varying between a 

minimum of 70 million tons and a maximum of 230 million tons. Further study of sediment loads 

in the lower Mississippi River is needed due to variation between sampling frequency and 

methods at various sites. 

2.5.3.2 Potential Borrow Sources 

Potential borrow sources for swamp and marsh restoration features include the Mississippi 

River, the IHNC/GIWW, the MRGO, Lake Pontchartrain, Lake Lery, Lake Borgne, Breton 

Sound, and offshore sources including the MRGO offshore dredged material disposal site 

(ODMDS). Barges could be used to bring material from other locations in the region; however, 
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the cost of transporting material by barge generally costs about twice as much as pumping 

material via pipeline from a nearby source. Other sources of material from outside of the study 

area were not considered a practicable option due to the costs associated with obtaining, 

transporting, and stockpiling the needed volume of material. 

Lake Borgne 

Lake Borgne is a viable borrow source for most of the areas evaluated for restoration in this 

study. Lake Borgne is designated critical habitat for Gulf sturgeon, and therefore no actions should 

be undertaken that may adversely impact this resource. Lake Borgne includes some sandy bottoms 

that are the preferred foraging habitat for this species. These areas were surveyed and excluded 

from consideration as potential borrow sources. 

Lake Pontchartrain 

Lake Pontchartrain is a viable borrow source for features located on the East Orleans 

Landbridge. Like Lake Borgne, the portion of Lake Pontchartrain closest to these features is 

designated critical habitat for Gulf sturgeon. However, the sandy bottoms of Lake Pontchartrain were 

identified as preferred foraging habitat for this species. Therefore this borrow source was not 

considered further as other sources that are not preferred foraging habitat were identified closer to 

proposed restoration features. 

MRGO Channel 

Public preference for filling in the channel and restoring the area to historic conditions is documented 

in the Scoping Report for this study and numerous other public documents: 

 The Final Environmental Impact Statement (EIS) for the Mississippi River-Gulf Outlet 

(MRGO), Louisiana, and Lake Borgne – Wetland Creation and Shoreline Protection Project, 

a USACE document, states that ―use of the MRGO channel as a borrow source was 

considered to be contrary to the Congressional intent, as described in House Report No. 109-

359, that funds provided in P.L. 109-148 for authorized operation and maintenance activities 

along the MRGO not be used to conduct any dredging of the MRGO channel.‖ This 

reasoning may have limited applicability to the MRGO ecosystem restoration plan. 

 Louisiana House Concurrent Resolution 34 (2005) to ―suspend any current appropriations or 

authorizations for expenditure of funds to dredge the Mississippi River Gulf Outlet, to direct 

the United States Army Corps of Engineers not to engage in any dredging activities on the 

Mississippi River Gulf Outlet, and to begin the necessary process to return the waterway to 

wetlands marsh status as close as possible to what it was prior to establishment of the canal.‖

 ―MRGO Must Go A Guide for the Army Corps Congressionally-Directed Closure of the 

Mississippi River Gulf Outlet‖ (Endorsed by LSU, Coalition to Restore Coastal Louisiana, 

Lake Pontchartrain Basin Foundation, Environmental Defense Fund, Gulf Restoration 

Network, National Wildlife Federation, Louisiana Wildlife Federation, American Rivers, and 

St. Bernard Parish). 
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Dredging the MRGO to obtain borrow material for wetland restoration is a potentially unacceptable 

alternative. However, because Lake Borgne (the closest available borrow source) is critical habitat for 

Gulf sturgeon, all viable alternatives must be investigated to avoid and minimize potential impacts to 

critical habitat to the extent practicable. 

The MRGO was analyzed as a borrow option for marsh restoration features. Using the channel could 

supply <10% of the identified 150+ million cubic yards of sediment need for the entire FIP. Dredging 

the channel would provide some cost savings (estimated at ~$20 million in October 2010 Price 

Levels) over the Lake Borgne option. As illustrated above, MRGO dredging for borrow is a publicly 

sensitive issue that was adamantly opposed in some scoping comments. 

Since Lake Borgne dredging raises issues because it is designated critical habitat for the threatened 

Gulf sturgeon, a trade off analysis has been conducted. Due to the public acceptability factor, the 

lake is the preferred choice while recognizing some higher costs and environmental impacts. 

Consultation with NMFS has resulted in a plan that minimizes impacts to critical habitat. 

Analyses were conducted for using the MRGO as a potential borrow source between the closures at 

Bayou Bienvenue (IHNC Surge Barrier) and Bayou La Loutre. Assuming dredging to -40' by 500' with 

a 1' over-depth, approximately 15.5 million cubic yards of material would be available for use in 

restoration projects. 

The practicability and acceptability of the use of the MRGO must also be considered. ―An alternative 

is practicable if it is available and capable of being done after taking into consideration cost, existing 

technology, and logistics in light of overall project purposes‖ (40 CFR 230.10 emphasis added). One 

purpose of the study is to restore areas affected by the MRGO. The area that was dredged to create 

the channel is the most directly affected area. 

Degrading the MRGO spoil banks south of the Chalmette Loop Levee to marsh elevation was 

considered as a restoration feature that would also provide material. This alternative was rejected 

because the spoil bank provides more storm surge protection than it would as marsh. 

Mississippi River 

The cost per unit associated with moving sediments from the river to restoration areas is 

significantly higher than using sediments from the nearest source. All things being equal, using 

river sediment for a restoration area with an average pumping distance of 20,000 feet (3.8 

miles) would cost approximately 25 to 30 percent more than using material from Lake Borgne. 

Dredging costs are positively correlated to distance: the cost of transporting material via pipeline 

for an average distance of 50,000 feet is about twice as much for an average distance of 20,000 

feet. Because dredging at depths greater than 70 feet necessitates costly modifications to 

dredging equipment, it is not always feasible to dredge the nearest location on the river. It is 

possible to load dredged river sediment onto barges and transport it to a restoration site. 

However, this process costs considerably more than dredging and distributing via pipeline. 

Other factors influencing the feasibility of using Mississippi River sediment include 

considerations for laying pipe across levees, land, and roads rather than water, and potential 

impacts to navigation. Table 2-7 provides a rough cost comparison of dredging from Lake 

Borgne and the Mississippi River. 
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Table 2-7. Cost Comparison of Dredging and Piping Material from Different Borrow Sources

(October 2010 Price Levels)

Average Pumping Distance Unit Cost of Dredging and Transporting via Pipeline

Source: Lake Borgne Source: Mississippi River

20,000 lf $4.50 $5.75

30,000 lf $5.80 $6.75

40,000 lf $7.25 $10.00

50,000 lf $9.75 $10.25

60,000 lf $11.00 $15.00

Notes: Very rough comparison of costs based on recent projects. Estimates for 5 million cubic 

yards of material per cubic yard. Assumes the same project from different sediment borrow

sources with all other factors being equal. 

Lake Lery 

Lake Lery is a viable borrow source for features in the vicinity of Bayou Terre aux Boeufs. 

However, a number of other restoration plans currently under development are considering 

Lake Lery, and it is uncertain if it will be available for use in the implementation of this plan. 

GIWW/Michoud Canal 

Features in the Central Wetlands could utilize sediment from the adjacent GIWW channel 

between miles 66 and 60. The channel would be dredged to its authorized depth to provide 

material for restoration features. The Michoud Canal is another potential source of sediment for 

use in this vicinity. 

MRGO Offshore Dredged Material Disposal Site (ODMDS) 

The MRGO ODMDS is located off of Breton Island and was used as a disposal site for material 

dredged for the MRGO navigation channel. This location would be considered as a borrow 

source for barrier island restoration. This site is not a practicable site for inland marsh and 

swamp restoration features, because it is located between 30 miles to 70 miles away from these 

features. 

Sand Deposits at Chandeleur and Breton Islands 

There are sand deposits at the northern end of Chandeleur Island and the southern end of 

Breton Island that could provide a source of material for barrier island restoration. These 

deposits were described in a report by Coastal Planning and Engineering, Inc. and the 

Pontchartrain Institute for Environmental Sciences. Mining at these sites would have minimal 

impact with regard to littoral sediment transport because these sands are at the terminus of the 

littoral system and there are no downdrift features that would be impacted. 

2.5.4 Environmental Planning Guiding Principles 

Several of the guiding principles established in the LACPR Technical Report, Coastal 

Restoration Appendix that were applicable to this study area were adopted. The overarching 

principle of the guiding principles is that sustaining the integrity of the estuarine environments in 
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coastal Louisiana, including various landscape features that make up those environments is 

critical to the ecological health, social and economic welfare of the region. Model analysis 

conducted for the LACPR of storm surge levels and wave magnitudes demonstrate the value of 

coastal features to lowering storm risks (USACE 2009). While the models show benefits from 

additional marsh, island and landbridge habitat, the effects of allowing existing features to 

degrade are even more pronounced. These guiding principles are consistent with the strategic 

approach developed by the Louisiana-Mississippi Gulf Coast Ecosystem Restoration Working 

Group‘s Roadmap for Restoring Ecosystem Resiliency and Sustainability. 

Guiding principles include: 

 Relatively intact estuarine ecosystems are a key attribute in coastal Louisiana, and 

alternatives should seek to enhance the resilience and self-sustainability of the 

estuarine environments, including protection of existing high-quality estuaries. 

 Restoration of key processes and dynamics are critical to the long-term health of the 

ecosystem. 

 Freshwater diversions must be carefully sited to maximize sediment retention within 

the coastal ecosystem and avoid sediment loss to the Gulf because of reduced 

Mississippi River sediment loads. Therefore, measures and alternatives must seek to 

maximize the combined benefits of diversions that seek to restore natural processes 

with mechanical marsh creation measures. 

 Additional sources of sediments should be sought where feasible; recognizing that 

such measures should not contribute to ecosystem degradation in the source area. 

 Measures should be combined synergistically to maximize possible cumulative 

benefits. Thus, the position of features within the landscape has a direct influence on 

the potential benefits derived. 

 Capacity to assess and quantify benefits and impacts from various measure 

combinations may be limited due to the state-of-the-science, uncertainty with future 

development, relative sea level rise and other factors. Flexibility is required in project 

design and implementation to permit adaptive management as conditions change 

and more is learned. 

 A concerted monitoring and adaptive management program should be a component 

of the restoration plan. 

These principles support the goals and objectives developed for the study, particularly in terms 

of sustainability, geographic integrity, and restoration in a systems context. The development of 

alternative plans was influenced by these principles by seeking to maximize the combined 

benefits of features. Compliance with these principles was used in the evaluation, comparison, 

and selection of plans. 
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2.5.5 Risk-Informed Planning Framework 

There are numerous risks and uncertainties associated with ecosystem restoration that must be 

considered in the planning process. Sources of risk and uncertainties fall into two general 

categories: errors in analysis and the variability of natural, social, and economic situations. 

Future conditions are inherently uncertain. The forecast of future conditions is limited by existing 

science and technology. Future conditions described in this study are based on an analysis of 

historic trends and the best available information. Some variation between forecast conditions 

and reality is certain. The degree to which these variations would affect planning decisions 

made in this study can be limited by recognizing risks and uncertainties in the decision-making 

process. 

Large uncertainties affect future conditions in the study area, including: climate change; sea 

level rise rates; subsidence rates; timing of tropical storm events; changes in frequency and 

intensity of tropical storm events; and/or changes in drought conditions. All of these factors 

could contribute to the acceleration of degradation of the study area, changing forecast 

conditions and the effectiveness of restoration plans. 

There are also significant economic and social uncertainties that could affect planning for this 

study. The timing and availability of financial resources for implementation is a major uncertainty 

that must be considered. 

Therefore, planning for this study will address the risks and uncertainties associated with all 

alternatives throughout the study process. The MRGO Ecosystem Restoration Plan Feasibility 

Study will be conducted within a risk-informed framework, aware of the challenges that risks and 

uncertainties present to the development, evaluation, and implementation of alternatives. 

2.5.6 Value Engineering 

In January 2009, Value Management Strategies, Inc. conducted a Value Engineering (VE) 

workshop with the PDT on the MRGO Ecosystem Restoration Study. The workshop was 

conducted at the Draft Feasibility Scoping Meeting Report/Preliminary Draft EIS phase, an early 

stage of plan formulation. The purpose of the VE study was to help the USACE better formulate 

plans to carry forward into the next phase of development. The VE team documented their 

findings in a March 2009 VE Study Report. This section evaluates the primary suggestions 

developed by the VE Team and how those suggestions were incorporated into the plan 

formulation process. 

Project Development Process/Plan Formulation 

The VE Team was concerned that the alternative measures were too expansive and 

unsustainable. The team recommended that additional reduced scope alternative strategies be 

developed. Three specific recommended measures were: 

 Develop alternative strategies based on limited resources; stabilize East Orleans 

Landbridge and Lake Borgne shorelines and contiguous marsh areas only. 
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 Develop a long term sustainable project alternative based on sediment capture. 

A phased implementation plan was developed considering land loss rates and the importance of 

measures to overall ecosystem form and function. Based on these factors, shoreline protection 

features, and features with the highest land loss rates are proposed to be constructed first. 

The challenges associated with limited resources are not treated as absolute planning 

constraints, but are strongly taken into consideration. All of the plans in the final array would 

require phased implementation and large amounts of sediment. 

Sediment Provisions 

Land creation and ridge restoration measures would require an enormous quantity of sediment. 

In addition, new land will continue to be lost due to subsidence and relative sea level rise. 

Therefore, the VE Team recommended long-term land creation strategies, such as: 

 A Mississippi River sediment delivery system using permanent trunk sediment 

pipelines; sediment traps via sill dams or over-dredging; and adding dredged 

material to diversions from the Mississippi River. 

 Investigation of various sediment sources, such as: 

 Mine only from mid-depth water bottoms; 

 Dredge the MRGO channel; 

 Dredge the original MRGO spoils in Black Bay and Breton Sound; 

 Use MRGO south spoil bank to fill in the MRGO channel; 

 Dredge sediment from Lake Pontchartrain and transfer to marsh creation areas; 

 Trap sediment near the mouth of the Mississippi River; and 

 For nearshore sources, consider continuous re-dredging of perimeter inverted 

breakwaters or develop specified borrow locations (e.g., Lake Borgne) with identified 

mitigation measures. 

At this point in the plan formulation process, feasibility level measures are being evaluated, not 

the specific methods of implementing those measures. However, all of the alternative sediment 

sources were considered and are discussed in Section 2.5.3.1. 

Shoreline Protection 

The VE team suggested inverted breakwaters as a method of shoreline protection. The concept 

of inverted breakwaters is to excavate near-shore trenches parallel to marsh area open 

shorelines for two main purposes: 1) to slow the water and reduce erosion rates and 2) to drop 

sediment close to the shore as a partial source of marsh creation and maintenance material. 

The New Orleans District has previously tested this concept near Grand Isle and the results 

were not favorable. Also, the use of inverted breakwaters would not reduce transportation and 

dredging costs, since many shoreline locations are removed from interior marsh creation and 
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nourishment sites. Therefore, at this time rock placement is considered the most effective 

means of foreshore protection. Similar to the inverted breakwater concept, offshore placement 

of rock structures may also benefit marsh by capturing sediments behind the shoreline 

protection feature. 

Habitat Restoration 

The VE team made the following habitat restoration recommendations: 

 Consider utilizing wave attenuation devices to reduce (non-storm or hurricane) wave 

energy for the purpose of improving vegetation success. 

 Consider temporary attenuation devices to reduce wind velocities to protect 

vegetation installations, providing a better environment for initial establishment and 

expediting the natural restoration processes. 

 Utilize the proposed cypress swamp restoration area to biofilter stormwater and 

treated wastewater effluent, in lieu of dumping directly into Lake Borgne or the 

Mississippi River, to improve water quality and to add nutrients to the biotic system. 

 Expand the submerged aquatic vegetation (SAV) pilot program to include 

consideration of SAV restoration in the marsh areas as well as the lakes. 

 Consider soil bioengineering measures for the ridge restoration. 

The VE team‘s habitat restoration recommendations would be taken into consideration in the 

detailed design of the federally identified plan. 

2.5.7 Trade-Off Analysis 

Decision-making for this study requires choices to be made from alternative options. These 

choices often entail trade-offs; choosing more of one thing simultaneously means choosing less 

of something else. Generally, stakeholders agree that restoration is needed in the study area. 

However, there are varying opinions among stakeholders as to where restoration should be 

sited, what restoration efforts are most important, and how it will be achieved. Planning for this 

study requires the evaluation of trade-offs and the consideration of competing interests. 

In the screening process, it was determined which component measures would be retained, and 

which components would be eliminated from further consideration. Criteria were established to 

screen measures as described in Section 2.6. This step in the study process was a large-scale 

trade-off analysis. For example, it was determined that the area to the west of Bayou Terre aux 

Boeufs was not significantly affected by the MRGO. This area was identified as a good location 

for restoration: the marsh was significantly degraded by Hurricane Katrina, it is located adjacent 

to development, and restoration would have synergy with the Caernarvon Freshwater Diversion. 

However, recommending restoration in this area under this plan could potentially result in less 

restoration in areas that were more directly affected by the navigation channel. Therefore, 

Caernarvon area restoration was removed from consideration in favor of restoration in areas 

directly affected by the navigation channel. 
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The location of borrow sites is also a significant trade-off that was considered in the formulation 

of alternatives. Ideally, the restoration features would utilize sediments from outside of the area 

to increase the net amount of sediment in the system. Transporting materials via barge, truck, or 

rail is significantly more costly than transporting materials via pipeline from within the system. 

The Mississippi River was identified as the best source for material for restoration features in 

the study area. The sediment is transported from upstream, and therefore represents a net 

increase of sediment in the system. The material is also silty-sand, which is more stackable than 

the material available from area lake bottoms. 

Despite the identification of the Mississippi River as the ideal source of material for restoration 

projects, only two features in the FIP would utilize these materials. All things being equal, using 

river sediment for a restoration area with an average pumping distance of 20,000 feet (3.8 

miles) would cost approximately 25 to 30 percent more than using material from Lake Borgne. 

However, all of the proposed marsh and swamp restoration features are significantly farther 

away from point bar deposits of river sediment than the nearest borrow source. Because 

dredging at depths greater than 70 feet necessitates costly modifications to dredging 

equipment, it is not feasible to dredge the nearest location on the river. It is possible to load 

dredged river sediment onto barges and transport it to a restoration site. However, this process 

costs at least twice as much as dredging and distributing via pipeline. Other factors influencing 

the feasibility of using Mississippi River sediment include considerations for laying pipe across 

levees and land, rather than water, and potential impacts to navigation. 

Lake Borgne water bottoms were determined to be the most cost-effective and feasible borrow 

source for construction of the majority of restoration features requiring sediment. However, the 

water bottoms of Lake Borgne are critical habitat for the endangered gulf sturgeon. To limit 

potential impacts to critical habitat, areas determined to have shell or hard bottoms were 

removed from consideration as borrow sites. Lake Pontchartrain is the closest site for a few 

marsh restoration features. However, the portion of Lake Pontchartrain in the study area is also 

designated critical habitat for gulf sturgeon. Due to the sandy composition of Lake Pontchartrain 

bottoms in the vicinity, these areas are considered prime habitat, and were removed from 

consideration. The location of borrow sites in Lake Borgne is the result of a significant trade-off. 

Some impacts to gulf sturgeon critical habitat are an unavoidable trade-off of achieving the 

benefits of the proposed action in a manner that is not cost-prohibitive. Continued coordination 

with NMFS and other stakeholders to avoid and minimize these impacts will be conducted in the 

design and implementation of these features. 

There are also several trade-offs associated with the plan selection process. The alternative 

plans selected for the final array represent scales of trade-offs. The no-action alternative does 

not have any associated construction costs, but the disbenefits of no action to the ecosystem, 

region, and nation involve different kinds of costs. The results of no action are not an acceptable 

trade-off for the monetary savings, as evidenced by the Congressional mandate associated with 

the study. However, once it has been determined that no action is not an acceptable alternative 

for implementation, the action alternative selected for recommendations must balance costs and 

benefits. 

Specific, measurable study objectives were developed to evaluate plans. The extent to which 

these plans achieved the identified objectives was used to determine which plan would be 
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chosen for tentative recommendation. This evaluation is discussed in Section 2.7.3. Ultimately, 

the first Best Buy Plan that achieved all of the objectives and reasonably maximized benefits for 

the least cost was recommended as the FIP. 

2.5.8 Objectives Found to be Unattainable 

Developing realistic and attainable objectives is critical to the success of the entire planning 

process. The following objectives were found to be unrealistic and unattainable based on the 

constraints and challenges discussed in the previous sections: 

 Restore the ecosystem to pre-Mississippi River and Tributaries (1928) conditions. 

 Restore the ecosystem to pre-MRGO (1958) conditions. 

 Maintain existing wetland acreage in the entire study area. 

The following paragraphs describe the reasons for not pursuing the above restoration 

approaches. 

2.5.8.1 Restoration to pre-Mississippi River and Tributaries (1928) Conditions 

Reversing the alteration of the marsh landscape since 1928 would require removing levees and 

other hydrologic constraints, backfilling in the extensive network of artificial channels, and letting 

the unconstrained physical processes re-create the wetlands, ridges and other features over 

time. Even if these measures were implemented, it is unlikely that the system would return to 

1928 form. The findings of the LCA and LACPR studies, however, suggest that complete 

restoration to a historic level is not feasible or cost-effective. 

1. The physical processes that formed the marsh are quite different than those operating 

now. For example, sediment loads in the Mississippi River and other tributaries are 

much lower now than in recent history and relative sea level rise is greater and projected 

to increase with global climate change. 

2. There are significant human constraints that limit the ability to restore natural processes. 

These include land development, flood risk reduction projects, and the presence of 

public infrastructure and travel corridors (including navigation channels and canals) 

within the study area. 

3. The economic investment in restoration is usually directed towards achieving restoration 

goals within a quick timeframe. Conversely, recovery through the restoration of key 

natural processes may require decades or even centuries to fully realize benefits at 

significant costs. This may also mean trade-offs between created/restored landscape 

features that increase or accelerate system sustainability versus the significant 

implementation required for unconstrained ―natural‖ evolution. 

2.5.8.2 Restoration to pre-MRGO (1958) Conditions 

Full restoration to pre-MRGO conditions would require infilling the entire MRGO channel, 

restoring all land lost in the study area between 1958 and the present (wetlands, natural ridges, 
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Final Feasibility Report 2: Plan Formulation 

2-74 June 2012 

and barrier islands), planting the area with vegetation types present prior to the construction of 

the MRGO, and eradication of invasive species that have appeared since 1958. Restoration to 

pre-MRGO conditions was eliminated from further consideration due to: 1) the inefficiency 

involved with backfilling the MRGO channel and 2) the length of time required for 

implementation. For example: 

1. It is estimated that it would require approximately 250–350 million cubic yards of 

dredged material to fill the channel from mile 60 to mile 25 at a cost of about $2.8 billion 

based on October 2006 price levels, and could take from 15 to 44 years to completely fill 

the channel (USACE 2008a). Backfilling the channel would replace the land lost from the 

direct impacts of construction and prevent saltwater intrusion into the channel. Backfilling 

the entire channel is not seen as an efficient measure, because the resources required 

could be used in other ways to produce greater benefits in less time. 

2. Human constraints, such as the Lake Pontchartrain and Vicinity project, limit the ability 

to restore natural processes. Land use practices and other related factors throughout the 

entire Mississippi River drainage area may also effectively constrain opportunities. 

2.5.8.3 Maintain Existing Wetland Acreage in the Entire Study Area 

Both the LCA and LACPR reports set out to develop plans for maintaining the existing acres of 

wetlands across the coast. In the case of LCA, the purpose was for ecosystem function, and in 

the case of LACPR, for storm surge risk reduction. In the MRGO study area, the LACPR Final 

Technical Report indicates that preserving the quantity and configuration of existing wetlands in 

the study area is important for sustaining current levels of storm risk reduction. In peer review of 

the LCA and LACPR reports, however, the National Research Council of the National 

Academies expressed doubts about the feasibility of sustaining wetlands into the future. The 

2006 NRC publication Drawing Louisiana’s New Map: Addressing Land Loss in Coastal 

Louisiana states the following: 

Full restoration of past Louisiana wetland cover and function will not be possible. The 

natural and anthropogenic processes contributing to net land loss in coastal Louisiana 

are significant and pervasive, and they have been operating for decades. Achieving no 

net loss is not a feasible objective because the social, political, and economic 

impediments are extensive; the sediment supply is limited; and the affected area is large. 

Louisiana’s coastal restoration plans must acknowledge these limitations prominently and 

adjust goals and public expectations accordingly. 

2.5.9 Study Objectives and Metrics 

Study objectives were developed as specific targets to guide the development of measures and 

gauge the extent that plans meet the overarching study goals. Metrics are used to measure how 

plans meet those specific targets. Study objectives include targets for salinity, habitat diversity, 

and landscape features critical to storm surge risk reduction. Salinity targets are based on 

ecosystem health and oyster production. Habitat targets are based on the direct and indirect 

habitat impacts of the MRGO navigation channel as described in Section 1.4. Critical landscape 

targets for storm surge risk reduction are based on features identified in the LACPR Final 

Technical Report. Table 2-8 identifies the study goals and objectives, the portion of the study 
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authority related to those objectives, problems and opportunities associated with the objectives, 

the management measure types identified to address specific objectives, and metrics for 

evaluation of alternatives.
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Table 2-8. Goals, Objectives, Metrics, and Measures

WRDA 2007 

Authority

Goal(s) Objective Problem Management 

Measures

Metric

- Sec. 7013 a(3)B(i)

- Sec. 7013 a(3)B(ii) 

- Sec. 7013 a(3)B(iii)

- Sec. 7013 a(3)B(iv)

- Sec. 7013 a(3)B(v)(II) 

- Sec. 3083 (a) and (b) 

to be studied under 

Sec. 7013 as per 

WRDA 2007 

implementation 

guidance

1. Achieve 

ecosystem 

sustainability to 

the greatest 

degree possible. 

2. Restore 

habitat in the 

Lake Borgne 

ecosystem and 

the areas 

affected by the 

MRGO 

navigation 

channel. 

1. Restore historic salinity conditions in 

the study area to re-establish and 

maintain historic habitat types; optimize 

ecosystem services; and decrease stress 

to vegetation as measured by the 

monthly salinity targets in the Biloxi 

Marsh (as identified by Chatry et al. 

1983) each month of the year, for at least 

four years out of every ten year period.

- Land loss

- Habitat change 

and loss

- Modification of 

natural 

hydrology

- Decreased 

freshwater, 

sediment,

and nutrient 

inputs

- Saltwater 

intrusion

Freshwater 

Diversion, 

Hydrologic 

Modification

Percentage of years 

target can be met over 

the period of analysis.

- Sec. 7013 a(3)B(i)

- Sec. 7013 a(3)B(ii)

- Sec. 7013 a(3)B(iv)

- Sec. 7013 a(3)B(v)(I)

1. Achieve 

ecosystem 

sustainability to 

the greatest 

degree possible. 

2. Restore 

habitat in the 

Lake Borgne 

ecosystem and 

the areas 

affected by the 

MRGO 

navigation 

channel.

3. Restore 

2. Restore native habitat acreages 

impacted by the MRGO and their 

ecosystem functions.

- Land loss

- Habitat change 

and loss

- Invasive 

species

- Increasing 

susceptibility of 

coastal 

communities to 

storm surge

Swamp Restoration 

and Nourishment 

Marsh Restoration 

and Nourishment, 

Shoreline 

Protection, 

Freshwater 

Diversion, 

Ridge Restoration, 

SAV Restoration, 

Oyster Reef 

Restoration, Buyouts, Vegetative 

Plantings, Invasive 

Species control, 

Herbivory control, 

Barrier Island 

Restoration.

1. Number of Acres 

restored or nourished

2. Number of Net Acres 

at the end of the period 

of analysis

a. Increase the year round spatial 

coverage of cypress swamp habitat in 

the Central Wetlands by at least 9,500 

acres by 2065.

b. Increase the year round spatial 

coverage of fresh/intermediate marsh in 

the Central Wetlands, Golden Triangle, 

MRGO, and South Lake Borgne by at 

least 6,800 acres by 2065.

c. Increase the year round spatial 

coverage of brackish marsh in Bayou 

Terre aux Boeufs, the Biloxi Marsh, and 

the East Orleans Landbridge by 

approximately 18,100 acres by 2065.

d. Increase the year round spatial 
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Table 2-8. Goals, Objectives, Metrics, and Measures

WRDA 2007 

Authority

Goal(s) Objective Problem Management 

Measures

Metric

natural features 

of the 

ecosystem that 

will reduce or 

prevent damage 

from storm 

surge.

coverage of vegetated wetlands in areas 

adjacent to the channel lost to increased 

tides and salinity by at least 3,900 acres 

by 2065.

e. Increase the year round spatial 

coverage of ridge habitat along Bayou La 

Loutre by 2065.

- Sec. 7013 a(3)B(i)

- Sec. 7013 a(3)B(ii)

- Sec. 7013 a(3)B(iv)

- Sec. 7013 a(3)B(v)(I)

3. Restore 

natural features 

of the 

ecosystem that 

will reduce or 

prevent damage 

from storm 

surge.

3. Increase the year round spatial 

coverage of critical landscape features 

that provide hurricane and storm damage 

risk reduction in the study area (i.e. areas 

located in the Biloxi Marshes, the East 

Orleans Landbridge, and forested 

habitats).

Marsh Restoration 

and Nourishment, 

Shoreline 

Protection, Ridge 

Restoration, 

Freshwater 

Diversion, Oyster 

Reef Restoration, 

Vegetative 

Plantings, Invasive 

Species control, 

Herbivory control,

In critical landscape 

areas and forested 

habitat: 

1. Number of AAHUs in 

critical areas

2. Number of Critical 

Acres restored or 

nourished

3. Number of Net 

Critical Acres at the end 

of the period of analysis 

- Sec. 7013 a(3)B(i) 2. Restore 

habitat in the 

Lake Borgne 

ecosystem and 

the areas 

affected by the 

MRGO 

navigation 

channel.

4. Increase awareness and 

understanding of the significance of 

resources in the study area through 

increased recreational and educational 

opportunities.

- Land loss

- Habitat change 

and loss

- Modification of 

natural 

hydrology 

- Increasing 

susceptibility of 

coastal 

communities to 

storm surge

Recreation and 

education 

enhancements to 

ecosystem 

restoration features.

1. Number of 

restoration features 

including recreation 

components.
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Objective 1 – Salinity Targets 

The first objective is to Restore historic salinity conditions in the study area to re-establish and 

maintain historic habitat types; optimize ecosystem services; and decrease stress to vegetation 

as measured by the monthly salinity targets in the Biloxi Marsh (as identified by Chatry et al. 

1983) each month of the year, for at least four years out of every ten year period. 

The Salinity Working Group for the MRGO Ecosystem Restoration Plan confirmed the validity of 

the salinity targets presented in the Mississippi and Louisiana Estuarine Areas Freshwater 

Diversion from Lake Pontchartrain Basin to Mississippi Sound Feasibility Study (also referred to 

as the Bonnet Carré study) for ecosystem restoration (USACE 1984). The salinity targets are 

based on mean monthly averages and are graphically presented in Figure 2-22 and Table 2-9. 

The salinity targets were originally developed and adopted by an ad hoc group consisting of 

representatives from USACE, LDWF, NMFS, St. Bernard Parish, LDNR and the Mississippi 

Bureau of Marine Resources for the 1984 report to enhance fish and wildlife resources in the 

Pontchartrain basin and re-establish a desirable salinity regime in the historic oyster reefs on 

the seaward fringe of the Biloxi Marsh (USACE 1984). The group determined that salinity should 

mimic historical conditions when the Mississippi River over-flowed its banks in the early part of 

the year. The targets were developed using ten years of data (1971-1981) from Louisiana‘s 

most productive oyster seed grounds. Oysters are an important commercial species but are also 

the best indicator species to determine the optimum salinity range for the Louisiana commercial 

fishery (LPBF 2006b). Oysters directly contribute to the larger ecosystem by filtering water and 

providing reef surface for other organisms. The Salinity Working Group noted that a target line 

and frequency need to be established in order to design a freshwater diversion, but that 

adaptive management should also be a component of freshwater reintroduction plans. 

Therefore, the metric for achieving this study objective is whether salinity falls within the optimal 

range each month, at least forty percent of the time, as described in Chatry et al. 1983. The 

Chatry targets are a way to measure the restoration of historic salinity regimes. 

Table 2-9. Monthly Salinity Targets at the Chatry Line

Month Mean Optimal 

Salinity

Standard Deviation

January 16.4 1.04

February 14.4 0.79

March 11.6 1.02

April 8.0 1.27

May 7.0 0.92

June 12.5 0.80

July 12.7 0.57

August 15.7 0.80

September 17.0 1.06

October 16.8 0.87

November 16.1 0.82

December 15.7 0.52
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Figure 2-22. Salinity Target Line Identified by Chatry et al. 1983 

Objective 2 – Habitat Targets 

The target acres for each habitat type were developed using the direct and indirect habitat 

impacts of the construction and operation of the MRGO between 1956 and 2008 as described in 

Section 1.4. The numbers of acres presented in these objectives are considered the minimum 

restoration targets to address the study authority (Table 2-10). 

Table 2-10. Habitat Targets 

Habitat Type Direct Loss Indirect Loss Indirect Gain Net Target

Fresh / Intermediate -3,400 -3,400 -6,800 6,800

Brackish -10,300 -19,200 11,400 -18,100 18,100

Saline -4,200 19,200 +15,000 0

Cypress -1,500 -8,000 -9,500 9,500

Shallows -4,800 4,800* 0+* 0

Additional** -500 -3,400 -3,900 3,900

Total -24,700 -34,000 -23,300 38,300

*Shallow water increases are difficult to quantify. Increases of this habitat type offset losses, and 

net gain is likely due to marsh loss. 

**Additional marsh includes areas adjacent to the channel lost due to increased salinity and tides. 

Although the impacts of the MRGO to the habitat of the Bayou La Loutre Ridge are not 

quantified, the channel made a 500 foot cut through the ridge, destroying upland habitat and a 
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2-80 June 2012 

natural salinity barrier. To address this effect of the construction of the MRGO channel, the 

study evaluated measures to improve and increase ridge habitat. 

The MRGO was dredged at an existing tidal inlet between Grand Gossier and Breton Islands, 

and may have interrupted sediment transport to Breton Island. To address this potential effect of 

the construction of the MRGO channel, the study evaluated measures to improve and increase 

barrier island habitat. 

Objective 3 – Critical Landscape Features for Storm Damage Risk Reduction 

Features that have been identified as critical landscape features for providing hurricane and 

storm damage risk reduction in the study area include: 

 The Biloxi Marsh, the East Orleans Landbridge and the Lake Maurepas Landbridge. 

 Forested habitats within the Lake Borgne ecosystem. 

All of these geographic locations were affected by increased salinity attributable to the MRGO, 

although it is noted in the planning assumptions for this study that the restoration of the Lake 

Maurepas area would be achieved through authorized LCA and CWPPRA projects. Portions of 

the channel were excavated through the Biloxi Marsh, and habitats in this area were affected by 

erosion along the channel and increased salinity due to saltwater intrusion from the channel. 

The affects of the MRGO channel on the East Orleans Landbridge are related to saltwater 

intrusion. Tate et al. 2002 notes that pre- and post-channel water quality monitoring and 

analysis indicate that salinity in the vicinity of Chef Menteur Pass increased by 2.3 ppt. 

Therefore, restoration in these areas is connected to portions of the study authority related to 

the restoration of habitats affected by the MRGO and areas that will reduce or prevent damage 

from storm surge. 

The connection between these features and storm surge is based on the geographic structure 

of the estuary. The Biloxi Marsh separates Lake Borgne from the Chandeleur Sound and the 

Gulf of Mexico. If the Biloxi Marsh did not exist, Lake Borgne would merge with Chandeleur 

Sound, and the ―speed bump‖ the marsh creates for storm surge would be removed. Similarly, if 

the East Orleans Landbridge disappeared, Lakes Pontchartrain and Borgne would merge to 

form one large lake and there would be no natural barrier to storm surge between these two 

bodies of water. The affect would be compounded if both landscape features were to disappear. 

These landscape features are technically recognized as significant in terms of scarcity and 

connectivity. The continuing disappearance of wetland barriers in the study area is well 

documented (Morgan and Larrimore 1957, Penland and Boyd 1981, Day and Templet 1989, 

Kesel, 1989, Gagliano 1998, USACE 2004, LPBF, 2006a, Lopez 2006, USGS 2007). Burkett et 

al. 2002 describes the importance of these areas and forested habitat as a barrier contributing 

to the reduction of flooding levels in the Greater New Orleans area. Restoration of the Biloxi 

Marsh and the East Orleans Landbridge is identified as measures that can ―potentially reduce 

the loss of life and property due to flooding‖ (Burkett et al. 2002). 

A sensitivity analysis was performed for the LACPR Technical Report to assess the impact of 

barrier island and marsh features on storm surge and wave energy. Hydrodynamic modeling 
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evaluated future scenarios for degraded and restored coastal conditions. The model was 

adjusted to account for changes to bathymetry and frictional resistance associated with the 

presence or absence of various landscape features. 

The findings of the LACPR analysis indicate that the effect of coastal features on storm surge 

and wave energy depends on a variety of factors, including the physical characteristics of the 

storm, coastal geomorphic setting, and the track of a storm when it makes landfall. The 

complex, dynamic nature of the interaction of various factors precludes the application of 

constant attenuation rates, i.e. it cannot be stated that a given acreage of marsh will produce a 

given amount of surge reduction. 

While the models show benefits from additional marsh, island, and landbridge habitat in some 

areas, the effects of allowing existing features to degrade in these areas are even more 

pronounced (USACE 2009). Therefore, the MRGO Ecosystem Restoration Plan will address the 

storm damage risk reduction objective by evaluating alternatives to sustain the integrity of the 

study area, particularly areas identified as critical landscape features. The Maurepas 

Landbridge, the Pontchartrain Landbridge (East Orleans Landbridge), and the Biloxi Marshes 

were identified in the LACPR Technical Report as critical landscape features having significant 

effects on surge, based on model results. Forested habitats were also considered to have 

different frictional coefficients in the LACPR hydrodynamic modeling, and therefore some 

benefit with regard to hurricane storm damage risk reduction. 

Figure 2-23. Critical Landscape Features for Storm Surge Damage Risk Reduction 
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The Multiple Lines of Defense strategy incorporates coastal ecosystem restoration as a ―first 

line of defense‖ in comprehensive hurricane storm damage risk reduction plans (Lopez 2006). In 

the Multiple Lines of Defense strategy, natural landscape features complement engineered 

structures, such as levees, to decrease hurricane storm damage risk. However, hurricane storm 

damage risk reduction systems cannot rely significantly on coastal landscape features because 

of the vulnerability of these features to single storm events. 

The MRGO Ecosystem Restoration study did not undertake an analysis to assign monetary 

benefits in terms of storm damage risk reduction to restoration features. The monetary benefits 

of coastal landscape features with respect to storm damage risk reduction are difficult to 

empirically quantify due to the complex interaction of dynamic variables. However, the general 

effect of coastal marshes on storm surge is well documented (USGS 1994, Walmsley et al. 

2009, Howes et al. 2010, Shepard et al. 2011) 

The extent to which plans achieve the storm surge damage objective was measured by 

comparing the extent of restoration proposed for identified critical landscape features. 

Restoration of forested habitat was also considered in the evaluation of this objective. 

Figure 2-24. Multiple Lines of Defense Strategy (Source: Lopez 2006) 

EO 11990 recognizes the impact of wetlands to flood and storm hazards, demonstrating the 

institutional significance of these areas. The East Orleans Landbridge and Biloxi Marsh are also 

significant in terms of the function of the estuary, because they act as geomorphic barriers to 

saltwater intrusion from the Gulf of Mexico. The significance of these resources is recognized by the 

Estuary Protection Act. 

The Biloxi Marsh and East Orleans Landbridge are critical landscape features that contribute to the 

maintenance of significant resources and storm surge reduction. Therefore, restoration in these 

areas was considered to contribute to the achievement of both the habitat and storm surge risk 

reduction objectives. 

Objective 4 – Increase awareness and understanding of the significance of resources in the 

study area through increased recreational and educational opportunities. 

The landscape and habitat impacts of the construction and operation of the MRGO since 1956 have 

changed recreational opportunities in the study area. This objective was developed to increase 
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2-83 June 2012 

opportunities for citizens to enjoy and understand the significance of the resources this study seeks 

to restore. 

Louisiana is known as ―Sportsman's Paradise‖ as a tribute to the wildlife and the hunting, trapping 

and fishing resources of the state. This nickname demonstrates the public significance of the 

recreational value of the study area‘s unique natural resources. The five species of fish most landed 

in recreation fishing activities in Louisiana are red drum, black drum, speckled sea trout, Atlantic 

croaker, and sand sea trout (Pattillo et al. 1997). These species rely on transitional habitat between 

estuarine and marine environments for nursery, foraging, spawning, and other life requirements that 

would be restored and protected through the implementation of this plan. 

Involving the public in the restoration activities and increasing awareness of the problems and 

opportunities in the study area could contribute to the acceptability and overall success of the plan. 

Providing the public with increased opportunities to interact with the ecosystem and learn about 

environmental principles, processes and native habitat in general could create a sense of public 

ownership in the restoration plan. Citizens that are more aware of the impacts of human activities to 

the natural environment would be more likely to support actions that restore, protect, and sustain 

these significant resources. 

2.6 IDENTIFICATION AND SCREENING OF MANAGEMENT 

MEASURES 

Several hundred conceptual features were initially considered. These features came from previous 

plans and reports, as well as the public scoping process. The following provides a list of conceptual 

features initially considered for inclusion in this study. 

Levees, Floodgates, and other Risk 

Reduction Features 

 Construct five floodgates at Seabrook, the 

GIWW, MRGO near Bayou Bienvenue, 

Bayou Dupre, and MRGO near Verret 

 New levee connecting the five floodgates on 

the GIWW and MRGO to levees on the SW 

shore of MRGO to +17 feet 

 Raise levee that is parallel to the SW 

shoreline of MRGO to +17.5 feet and other 

levees in St. Bernard Parish to +20 feet. 

 Construct new levee at +17.5 feet 

connecting the levees in St. Bernard Parish to 

levees on the Mississippi River. 

 Continue construction of 40 Arpent Levee 

through Verret. 

 Raise Mississippi River Levees. 

 Construct new river floodgate at Bohemia. 

 Sector gates at Seabrook, GIWW, MRGO 

and leaky levee at MRGO to GIWW gates. 

 Raise and armor existing MRGO levees. 

 A new levee on the eastern shore of MRGO 

or barriers across Lake Borgne. 

 Storm breakwaters from Golden Triangle to 

Bayou St. Malo. 

 A levee from approximately Verret to the 

GIWW protecting the land in the Golden 

Triangle. 

 No gate constructed across the 

MRGO/GIWW at Paris Road. 
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Freshwater Diversion 

 Freshwater diversion at or near Violet 

 Introduction of freshwater into the system 

at the existing Violet Canal 

 Bayou Bienvenue Diversion 

 Bayou LaLoutre Diversion 

 Bayou Terre aux Boeufs Diversion 

 American/California Bay Diversion 

 Bohemia Mississippi River Reintroduction 

 Diversion N. of Fort St. Phillip 

 Fort Jackson Sediment Diversion 

 Grand Bay Diversion 

 Bayou Lamoque Diversion 

 White Ditch Diversion 

 Benney‘s Bay Diversion 

 Adaptive Management through 

Maintenance of Existing Crevasses and 

Construction of New Crevasses 

 Diversion at Hope Canal 

 Diversion at Blind River or Convent/Blind 

 Caernarvon Diversion Modification 

 Bonnet Carrè Freshwater / Sediment 

Introduction or Opportunistic use of 

Bonnet Carrè Spillway 

 La Branche Diversion 

 Violet Spillway 

 Effluent from Waste Water Treatment 

Plant 

Hydrologic Modification and Restoration 

 Fill MRGO 

 Fill Hopedale 

 Fill Florissant 

 Fill Back Dike Canal 

 Identify sustainable methods to benefit 

Bayou St. John water quality 

 South Slough Hydrologic Restoration 

 Lock Replacement 

 Total closure of Alabama Bayou at MRGO 

 Remove Old Grand Prairie Levee. 

 Dredge and maintain Baptiste Collette 

Bayou. 

 Construct new channel from Baptiste 

Collette Bayou to Gulfport Ship Channel 

 Do not construct closures at Rigolets and 

Chef Pass 

 Constriction of Bayou Dupre at Lake 

Borgne 

 A sill at Seabrook 

 Water control structures on MRGO 

 Biloxi Marsh water control structures 

 Channel severance or constriction on 

MRGO in four or more additional locations 

 Allow natural infill of the south reach of 

MRGO channel 

 Sediment Delivery by Pipeline at Central 

Wetlands 

 Sediment Pipeline at Golden Triangle 

 Bayou La Loutre Water Control Features 

 Create Channel (Bayou Restoration) 

 Constrict opening between Lake Borgne 

and MRGO 

 MRGO sill 
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Marsh Restoration 

 Biloxi Marsh marsh restoration

 Restoration and maintenance of the 

narrow land between Lake Borgne 

and the MRGO 

 Ensure that the MRGO remains 

isolated from Lake Borgne 

 Central Wetlands marsh restoration 

 Golden Triangle marsh restoration 

 Lake Borgne marsh restoration 

 New Orleans East Landbridge marsh 

restoration 

 Breton Landbridge marsh restoration 

 South Lake Borgne marsh restoration 

 Caernarvon area marsh restoration 

 Grand Bay Marsh Restoration 

 La Branche Wetlands Marsh 

Restoration 

 Fort St. Phillip Marsh Restoration 

 St. Tammany Marsh Restoration 

 Jefferson Parish fringe marsh buffer 

 Small Marsh Restoration at Outfall 

Canals 

 Bayou Terre aux Boeufs Marsh 

Restoration 

 North Lake Lery Marsh Restoration 

 Marsh Restoration South of Lake Lery 

Swamp Restoration 

 Central Wetlands cypress 

restoration

 Florissant cypress restoration

 Hopedale cypress restoration

Shoreline Protection 

 New bank line stabilization on the entire 

shore of Lake Borgne 

 Breakwaters in Lake Borgne 

 Breakwaters to protect Chandeleur Islands. 

 Armor eroding shorelines on the north bank 

of MRGO and on Lake Borgne. 

 Armor MRGO banks to stop erosion. 

 Armor both sides of the La Loutre Ridge 

bank 

 Shoreline protection in the Biloxi Marsh 

 Biloxi Marsh northeastern outlying islands 

bank armament 

 Jetties in the offshore segments of the 

channel in Breton and Chandeleur Sounds 

 Foreshore protection segments along the 

portion of the Chalmette Loop Levee 

fronting the MRGO 

 Foreshore protection in various locations 

on the north bank of the channel fronting 

wetlands areas 

 Shore protection from Golden Triangle to 

Bayou St. Malo. 

 Restoration/rehabilitation of bank lines 

along MRGO

 La Branche Wetlands shoreline protection 

 Sink Ships for Breakwater/Oyster Reef 

 Lake Maurepas shoreline protection 

 St. Tammany shoreline protection 

 Lake Lery shoreline protection 

Ridge Restoration 

 Restore La Loutre Ridge to +8 feet 

 Rebuild La Loutre Landbridge 
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 Restore Bayou La Loutre Ridge east of the 

MRGO to Christmas Camp Lake 

 Bayou Terre aux Boeuf ridge restoration 

Vegetative Planting 

 Plant MRGO spoil banks with trees 

 Plant trees in front of levees 

Barrier Island Restoration 

 Restore Breton and Chandeleur Island 

Chain 

 Biloxi Marsh northeastern outlying islands 

marsh restoration 

 Cat Island restoration 

SAV Restoration 

 SAV restoration in the study area

Oyster Reef Restoration 

 Oyster reef restoration in the Biloxi Marsh

Recreation Features 

 USACE provide a boat launch immediately 

south of the proposed closure structure on 

the right descending bank of the MRGO 

 Bienvenue Triangle recreation feature 

 Violet Diversion recreation feature 

 Shell Beach monument recreation 

improvements 

 Bayou St. John recreation improvemen

2.6.1 Initial Formulation and Screening Process 

The following section provides a summary of the initial formulation and screening of measures. 

Step 1 –Proposed measures that did not serve the primary purpose of ecosystem restoration 

(e.g., levees, floodwalls) were eliminated as not in compliance with the goals and objectives of 

the study. Recreation features were deferred for development in conjunction with the selected 

plan. 

Step 2 – Conceptual measures were defined spatially and input into a Geographic Information 

System (GIS) database. In some cases, several specific proposed marsh, swamp, or ridge 

restoration measures in the same area were combined into one larger measure, while other 

larger, more conceptual measures were segmented into smaller geographic components. 

Step 3 – Once measures were geographically defined, they were screened based on their 

spatial effects by determining if they met one of two of the following criteria: 1) the measure 

addressed restoration of the Lake Borgne Ecosystem, 2) the measure addressed a MRGO 

ecosystem effect. Measures that did not meet one of these two criteria were eliminated from 

further consideration. 

Step 4 – The remaining measures were then screened based on additional criteria specific to 

the type of measure as described in the following sections. During this portion of the screening 

process, measures were only compared to like measures, for example, marsh restoration 

measures were only compared to other marsh restoration measures. 

The following sections describe the initial screening by measure type. 
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Final Feasibility Report 2: Plan Formulation 

2-87 June 2012 

2.6.1.1 Freshwater Diversions Initial Screening 

The MRGO study authority calls for considering the diversion of freshwater from the Mississippi 

River for restoring the Lake Borgne ecosystem. Delivering river water to the Lake Borgne area 

could be achieved at a number of different locations along the east bank of the Mississippi 

River. Several alternative locations and sizes for freshwater diversions had been proposed in 

previous reports such as LCA and LACPR, which were incorporated into the initial measures to 

be evaluated as part of this study. Twenty-two freshwater diversion sites along the east bank of 

the Mississippi River between Convent in St. James Parish and Baptiste Collette Bayou in 

Plaquemines Parish were evaluated. This set of initial sites for evaluation was developed from 

existing reports, public input, and interagency collaboration. If sites had previously specified 

sizes, specific multiple sizes at these sites were considered. If previous studies had not 

identified discharge rates for a site, consideration of the size of the diversion was deferred. 

Freshwater diversion measures were initially screened from further consideration based upon 

two criteria. If diversion measures and sites were determined to have an influence area lying 

entirely outside the Lake Borgne ecosystem or outside of the areas potentially affected by the 

MRGO, they were screened from further evaluation as detailed below. 

Ten potential sites on the river‘s east bank below Caernarvon were identified in the initial 

planning phase. It was determined that these areas were outside of the Lake Borgne 

ecosystem. Therefore, potential diversion locations on the river below the existing Caernarvon 

Diversion were removed from further consideration. This initial screening reduced the original 43 

measures to a total of 23 conceptual measures at 12 sites (see Table 12-11). 

The location of a freshwater diversion is constrained by existing development, infrastructure, 

and river conditions as illustrated in Figure 2-25. A freshwater diversion at Bonnet Carrè was the 

selected plan in the 1984 Mississippi and Louisiana Estuarine Areas Feasibility Study 

Freshwater Diversion to Lake Pontchartrain and Mississippi Sound Feasibility Study (USACE 

1984). The State of Louisiana has expressed opposition to a large diversion of freshwater into 

Lake Pontchartrain due to water quality concerns. A re-evaluation of this study was performed in 

1996, and a Finding of No Significant Impact (FONSI) for an Environmental Assessment 

evaluating water quality impacts to Lake Pontchartrain was signed in July 1996. In an official 

reply, the State of Louisiana in July 1996, declined to participate further in the project. WRDA 

2007 Section 3083 authorizes the achievement of the benefits described in Mississippi and 

Louisiana Estuarine Areas Freshwater Diversion to Lake Pontchartrain and Mississippi Sound 

Feasibility Study through the design and implementation of a freshwater diversion at or near 

Violet, LA. Modification to the Bonnet Carrè is still an authorized project and could be 

considered as part of that effort. Because it would be inefficient to build a new structure at a 

location where an existing structure could be modified to achieve the same benefits, a new 

structure at or near the Bonnet Carrè Spillway was removed from further consideration, 

including a new diversion in the vicinity of the La Branche Wetlands. 
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Final Feasibility Report 2: Plan Formulation 

2-88 June 2012 

Figure 2-25. Freshwater Diversion Location Constraints 

A freshwater diversion could not be located between the La Branche Wetlands and the Inner 

Harbor Navigation Canal without impacting existing suburban and urban development in 

Orleans and Jefferson Parishes. Developing a plan to locate a diversion in a densely developed 

community without open land corridors between the river and estuary would require substantial 

relocation of homes, businesses, and public infrastructure. There are no existing open land 

corridors between the river and lake in either Jefferson Parish or Orleans Parish. Therefore, no 

locations in Jefferson Parish or in Orleans Parish were evaluated. 

There are four open land corridors in St. Bernard Parish between the communities of Chalmette 

and Poydras where freshwater could be diverted from the Mississippi River for distribution in the 

Lake Borgne ecosystem. 

South of Poydras, there are opportunities to divert river water in the vicinity of Bayou Terre aux 

Boeufs and at the existing Caernarvon Diversion. The Bayou Terre aux Boeufs ridge in St. 

Bernard Parish forms a hydrologic barrier that would inhibit the movement of freshwater to the 

areas targeted for restoration in the MRGO study. Bayou Terre aux Boeufs flows through the 

communities of St. Bernard, Toca, Kenilworth and Verret. A freshwater diversion at this location 

was proposed in LACPR to benefit the marshes located between the MRGO and Bayou Terre 

aux Boeufs. As noted in LACPR, the construction of a freshwater diversion at this location would 

require construction of a leveed conveyance channel approximately 7.16 miles in length to 

influence the area between Bayou Terre aux Boeufs and the MRGO. To distribute freshwater to 
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Final Feasibility Report 2: Plan Formulation 

2-89 June 2012 

this area would require widening and deepening the existing bayou, and adjacent residential, 

commercial, and industrial development would be impacted. Additional channels would be 

needed outside of the Chalmette Loop Levee to influence the greater Lake Borgne ecosystem. 

Because the Mississippi River is farther away from Lake Borgne in this location, it would be less 

efficient to distribute freshwater through Bayou Terre aux Boeufs than at a location where the 

river is closer to the lake. A freshwater diversion at Bayou Terre aux Boeufs would not provide 

freshwater to the Central Wetlands, Golden Triangle, and northern Lake Borgne/MRGO 

Landbridge, and therefore would not achieve the goals and objectives of this study. Due to 

concerns regarding efficiency, constructability, and potential impacts to development, diversion 

alternatives at Bayou Terre aux Boeufs were removed from further consideration. 

Two existing LCA Caernarvon Diversion projects were being developed to maximize benefits at 

the Caernarvon Diversion, and the area targeted for restoration in the MRGO Ecosystem 

Restoration Study would be more efficiently served by a freshwater diversion that would not be 

impeded by the Bayou Terre aux Boeufs ridge and the MRGO spoil bank. This assessment 

reduced the number of potential diversion sites to four locations in the vicinity of Violet, LA in St. 

Bernard Parish. 

Restoration of a freshwater system in the Central Wetlands may be needed to restore the 

swamp habitat affected by the MRGO, and sustain the restored marsh. To accomplish this 

restoration, a freshwater diversion is needed to establish the optimal salinity regime for the 

estuary. A river diversion at or near the existing Violet Canal was determined to be the best 

location to achieve the goals and objectives of the study. The MRGO was excavated through 

the eastern portion of the Central Wetlands and increased salinity in the area through salt water 

intrusion. The habitat of the Central Wetlands changed from a cypress swamp and 

fresh/intermediate marsh system to an entirely brackish system. Although salinity levels have 

decreased in the area due to the closure of the MRGO, a freshwater diversion may be needed 

to establish and maintain optimal salinity. In these preliminary analyses, a freshwater diversion 

located in the vicinity of Violet, LA was determined to be the most effective way to restore the 

Central Wetlands and the salinity regime in the estuary. 

Table 2-11. Steps 3 and 4: Freshwater Diversion Measures

Measure Name

Addresses 

Restoration 

of Lake 

Borgne 

Ecosystem

Addresses a 

MRGO 

Ecosystem 

Effect

Other Criteria

American Bay Diversion No No

California Bay Diversion No No

Bohemia Mississippi River Reintroduction No No

Delta Building Diversion N. of Fort St. Phillip No No

Fort Jackson Sediment Diversion No No

Grand Bay Diversion R1 and R2 No No
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Final Feasibility Report 2: Plan Formulation 

2-90 June 2012 

Table 2-11. Steps 3 and 4: Freshwater Diversion Measures

Measure Name

Addresses 

Restoration 

of Lake 

Borgne 

Ecosystem

Addresses a 

MRGO 

Ecosystem 

Effect

Other Criteria

Bayou Lamoque Diversion R1, R2, R3, R4, 

and R5 No No

White Ditch Diversion R3 and R5 No No

Benney‘s Bay Diversion R3 and R4 No No

Adaptive Management through 

Maintenance of Existing Crevasses and 

Construction of New Crevasses

No No

Freshwater Diversion in the Vicinity of 

Violet Yes Yes

Diversion at Hope Canal R1, R2, R3, R4, 

and R5 Yes Yes Addressed by LCA authorized project.

Diversion at Blind River R1, R2, R3, R4, and 

R5 Yes Yes Addressed by LCA authorized project.

Diversion Convent/Blind River R1, R2, R3, 

R4, and R5 Yes Yes Addressed by LCA authorized project.

Bayou Bienvenue Diversion R1 and R2 Yes Yes

Concerns associated with 

constructability and impacts to 

existing infrastructure.

Bayou La Loutre Diversion R1 and R2 Yes Yes

Concerns regarding efficiency, 

constructability, potential impacts to 

development, and the potential to 

influence the targeted areas.

Caernarvon Diversion Modification R1 and 

R2 Maybe Maybe

Target influence area for MRGO 

Ecosystem Restoration could be 

served more efficiently from another 

location due to the hydrologic barriers 

formed by the bayou Terre aux 

Boeufs and MRGO spoil banks. Also 

addressed in the two authorized 

Caernarvon Diversion modification 

projects.

Bonnet Carrè Freshwater / Sediment 

Introduction or Opportunistic use of Bonnet 

Carrè Spillway

Yes Yes

Project is already authorized and can 

be implemented by Congress; 

however WRDA 2007 Section 3083 

mandates the achievement of the 

benefits of this diversion at or near 

Violet, LA. Modification to the Bonnet 

Carrè could be considered as part of 

that effort.

La Branche Diversion R1 and R2 Yes Yes

The benefits of a diversion at this 

location could be achieved at Bonnet 

Carrè for considerably less cost.
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Final Feasibility Report 2: Plan Formulation 

2-91 June 2012 

Table 2-11. Steps 3 and 4: Freshwater Diversion Measures

Measure Name

Addresses 

Restoration 

of Lake 

Borgne 

Ecosystem

Addresses a 

MRGO 

Ecosystem 

Effect

Other Criteria

Bayou Terre aux Boeufs Diversion R1 and 

R2 Yes Yes

Target influence area for MRGO 

Ecosystem Restoration could be 

served more efficiently from another 

location due to the hydrologic barriers 

formed by the bayou Terre aux

Boeufs and MRGO spoil banks.

Violet Spillway Yes Yes

An uncontrolled diversion was ruled 

out because of the need to control 

flows at different times of the year in 

order to meet salinity targets, support 

cypress growth, avoid flooding, 

adaptively manage, etc.

Effluent from Waste Water Treatment Plant Yes Yes

Addressed by CIAP project. Flow 

capability insufficient to meet the 

objectives.

Note: Bold text indicates the measure was carried forward for further consideration.

Alternatives that did not include a freshwater diversion were considered in the initial 

development of alternatives. These alternatives were ultimately eliminated from further study as 

inconsistent with the study goals and objectives and the ―Guiding Principles‖. A small freshwater 

diversion would not mimic periodic overbank flooding of the Mississippi River, a key process of 

the estuary that preliminary analyses indicate is needed to re-establish historic salinity 

gradients, habitat types, and increase self-sustainability in the system. 

The forecast future without project salinity conditions suggest that salinity in the study area 

would be reduced by the closures on the MRGO and other authorized projects. However, 

additional inputs of freshwater may be necessary to fully restore the historic salinity regime.The 

restoration and maintenance of a cypress swamp and fresh/intermediate marsh in the Central 

Wetlands may require the introduction of freshwater into this area. Additionally, to restore the 

MRGO/Lake Borgne Landbridge to a condition favorable for the propagation of intermediate 

marsh species, the area may require further salinity reductions beyond the forecast future 

without project conditions. 

The ―Guiding Principles‖ reinforce the inclusion of a freshwater diversion for this study. The 

freshwater diversion proposed as part of the MRGO Ecosystem Restoration Plan would assist 

with realizing the following guiding principles: 

 Restore key processes and dynamics in the estuary; 

 Enhance the resilience and self-sustainability of the estuary; 
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Final Feasibility Report 2: Plan Formulation 

2-92 June 2012 

 Maximize the combined benefits of freshwater diversions that seek to restore natural 

processes with mechanical marsh creation measures; and 

 Combine measures synergistically to maximize possible cumulative benefits. 

2.6.1.2 Hydrologic Restoration Initial Screening Results 

Initially, 24 channel/canal backfilling measures were considered. After screening, six of the 

original fill measures were carried forward for further study. In addition, those associated with 

the distribution of freshwater from diversions were considered to be part of the diversion 

measure rather than a stand-alone measure. Some other proposed backfill areas were deemed 

impractical because of the cost of installing multiple retaining structures in a relatively small 

geographic area. Other canal backfilling features were screened out to maintain vessel access 

following the MRGO closure at Bayou La Loutre. The remaining six backfilling features were 

located within the footprint of the former navigation channel (see Table 2-12).

Initially, 26 water control measures were considered. After screening, no measures were carried 

forward. It was determined that water control measures would be examined in conjunction with 

individual marsh/swamp restoration features and freshwater diversions, rather than as standalone measures (see Table 2-12).

Table 2-12. Steps 3 and 4: Hydrologic Restoration Measures

Measure Name

Addresses 

Restoration of 

Lake Borgne 

Ecosystem

Addresses a 

MRGO 

Ecosystem 

Effect

Other Criteria

Florissant Fill and Plant with Trees No No

Hopedale Fill and Plant with Trees No No

Alabama Bayou Closure No No

Identify sustainable methods to benefit 

Bayou St. John water quality, habitat 

management, recreational access, and 

educational opportunities

No No

South Slough Hydrologic Restoration 1-3 No No

Lock Replacement No No

Multiple Closures in MRGO 1-3 No No

Fill parallel canal to Marsh Elevation

(Back Canal Bienvenue to Dupre) No No

Fill parallel canal to Marsh Elevation

(Back Canal Between Dupre and Verret 

Levee)

Yes Yes

Interferes with freshwater 

distribution. The benefits of 

creating marsh habitat in this 

location are less than the impacts 

to fisheries and access.
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2-93 June 2012 

Table 2-12. Steps 3 and 4: Hydrologic Restoration Measures

Measure Name

Addresses 

Restoration of 

Lake Borgne 

Ecosystem

Addresses a 

MRGO 

Ecosystem 

Effect

Other Criteria

Fill parallel canal to Marsh Elevation

(Back Canal Between HPL at Verret to 

Yscloskey)

Yes Yes

Interferes with freshwater 

distribution. The benefits of 

creating marsh habitat in this 

location are less than the impacts 

to fisheries and access.

Fill parallel canal to Marsh Elevation

(Back Canal Between Bayous Yscloskey 

and La Loutre)

Yes Yes

Interferes with freshwater 

distribution. The benefits of 

creating marsh habitat in this 

location are less than the impacts 

to fisheries and access. Access 

over pipelines is an issue.

Fill parallel canal to Marsh Elevation

(Back Canal Between Bayous Yscloskey 

and La Loutre) Yes Yes

Interferes with freshwater 

distribution. The benefits of 

creating marsh habitat in this 

location are less than the impacts 

to fisheries and access.

Fill in MRGO to Bay Bottom 

(Between barrier islands to Mile 27)

Yes Yes

Interferes with freshwater 

distribution. The benefits of 

creating marsh habitat in this 

location are less than the impacts 

to fisheries and access. NOTE: 

Approx 1360' of canal, in vicinity of 

MRGO mile 41.6, is filled in and 

does not require any further fill.

Fill parallel canal to Marsh Elevation 

(Bayou La Loutre to terminus) Yes Yes Natural fill occurring; no land created.

Fill in MRGO to Marsh Elevation (GIWW to 

Bienvenue) Reach 1 Yes Yes Impractical: Three containment 

structures would be required in 

addition to IHNC surge barrier in 

distance of approx. 7000'.

Fill in MRGO to Marsh Elevation (GIWW to 

Bienvenue) Reach 2 Yes Yes

Fill parallel canal to Marsh Elevation

(Bayou Bienvenue to Bayou Dupre inside 

levee)

Yes Yes Already filled in by previous MRGO 

O&M dredge disposal.

Fill parallel canal to Marsh Elevation 

(Bayou Dupre to Levee at Verret inside 

levee)

Yes Yes Already filled in by previous MRGO 

O&M dredge disposal.

Florissant Historic - Re-grade from ridge to 

marsh at edge of MRGO Yes Yes

Degrading spoil banks not seen as 

desirable because upland scrubshrub provides habitat for migrating 

birds.

Hopedale Historic - Re-grade ridge to 

marsh at edge of MRGO Yes Yes

Degrading spoil banks not seen as 

desirable because upland scrubshrub provides habitat for migrating 

birds.
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2-94 June 2012 

Table 2-12. Steps 3 and 4: Hydrologic Restoration Measures

Measure Name

Addresses 

Restoration of 

Lake Borgne 

Ecosystem

Addresses a 

MRGO 

Ecosystem 

Effect

Other Criteria

Sediment Delivery by Pipeline at Central 

Wetlands Yes Yes Deferred as dependent on other diversion measures.

Sediment Delivery by Pipeline at Golden 

Triangle Yes Yes Deferred as dependent on other diversion measures.

MRGO Sill (Water Control Structure 2-5 Deferred as dependent on other 

diversion measures.

Bayou La Loutre Water Control Features 

1-6

Yes Yes Deferred as dependent on other 

diversion measures.

Create Channel (Bayou Restoration) 1-3

Yes Yes Concerns about increasing 

saltwater intrusion and tidal scour.

Constrict opening between Lake Borgne 

and MRGO Yes Yes

Addressed by shore protection 

measures along south shore of 

Lake Borgne and north bank of 

MRGO.

MRGO Sill (Water Control Structure - 1) Yes Yes Channel filling in naturally.

Fill in MRGO to Marsh Elevation - A 

(Bienvenue to Dupre) Yes Yes

Fill in MRGO to Marsh Elevation - C 

(Dupre to end of Levee Reach) Yes Yes

Fill In MRGO to Marsh Elevation - I 

(Bayou LaLoutre to Lake Athanasio) Yes Yes

Fill in MRGO to Marsh Elevation - G 

(Bayou Yscloskey to Bayou Doulluts) Yes Yes

Fill in MRGO to Marsh Elevation - F

(End of Leveed Reach to Bayou 

Yscloskey)

Yes Yes

Fill in MRGO to Marsh Elevation - H

(Bayou Doulluts to Bayou LaLoutre) Yes Yes

Note: Bold text indicates the measure was carried forward for further consideration.

2.6.1.3 Marsh and Swamp Restoration Measures Initial Screening Results 

Initially, approximately 42 marsh restoration and five swamp restoration areas were identified in 

Louisiana. For discussion of potential marsh restoration sites in Mississippi, see MsCIP. The 

sites in Louisiana were screened to remove areas that were not affected by the MRGO or were 

outside of the Lake Borgne ecosystem (see Table 2-13). After initial screening, 19 areas were 

identified for further refinement of marsh restoration and nourishment measures. Three areas in 

the Central Wetlands were retained for further study and refinement of swamp restoration and 

nourishment measures. 
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2-95 June 2012 

Table 2-13. Steps 3 and 4: Marsh and Swamp Restoration Measures

Measure Name

Addresses 

Restoration of 

Lake Borgne 

Ecosystem

Addresses 

a MRGO 

Ecosystem 

Effect

Other Criteria

Maintain Breton Landbridge - North Yes Yes

Adverse impact to hydrology in 

terms of freshwater.

Bayou Terre aux Boeufs Marsh Creation - B Yes Yes

Caernarvon Area Marsh Creation - South No No

Maintain and Restore Biloxi Landbridge and 

Barrier Reefs North B No No

Maintain and Restore Biloxi Landbridge and 

Barrier Reefs South A No No

Maintain and Restore Biloxi Landbridge and 

Barrier Reefs South B No No

Maintain critical marsh shoreline and ridges 

of East Orleans Landbridge - B-C Yes Yes

Maintain critical marsh shoreline and ridges of 

East Orleans Landbridge – D Yes Yes

Screened out as unnecessary due 

to existing dredge material 

disposal.

Maintain critical marsh shoreline and ridges 

of East Orleans Landbridge - A Yes Yes

Maintain critical marsh shoreline and ridges 

of East Orleans Landbridge - E Yes No

Maintain critical marsh shoreline and ridges 

of East Orleans Landbridge - F Yes No

Maintain and Restore Biloxi Landbridge and 

Barrier Reefs North A Yes No

Marsh is intact and has not 

changed significantly since 1956.

Bayou Terre aux Boeufs Marsh Creation - A No No

Golden Triangle Marsh Creation - East Yes Yes

Maintain Lake Borgne Landbridge including 

Landbridge Shoreline Protection Yes Yes

Maintain and Restore Biloxi Landbridge and 

Barrier Reefs South C Yes Maybe

Biloxi Marshes - Marsh Creation Interior - C Yes Maybe

Marsh is intact and has not 

changed significantly since 1956.

Bayou Terre aux Boeufs Marsh Creation - C No No

Maintain Breton Landbridge - South No No

Caernarvon Area Marsh Creation - North No No

Central Wetlands Swamp Creation - B Yes Yes

Central Wetlands Swamp Creation - A Yes Yes

Central Wetlands Swamp Creation - C Yes Yes

Golden Triangle Marsh Creation - East Yes Yes
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2-96 June 2012 

Table 2-13. Steps 3 and 4: Marsh and Swamp Restoration Measures

Measure Name

Addresses 

Restoration of 

Lake Borgne 

Ecosystem

Addresses 

a MRGO 

Ecosystem 

Effect

Other Criteria

Biloxi Marshes - Marsh Creation Interior - B No No

Biloxi Marshes - Marsh Creation Interior - A No No

Biloxi Marshes - Marsh Creation Interior - D Yes Maybe

Biloxi Marshes - Marsh Creation Interior - E Yes Maybe

Marsh is intact and has not 

changed significantly since 1956.

Biloxi Marshes Marsh Creation and Shoreline 

Protection – A Yes No

Marsh is intact and has not 

changed significantly since 1956.

Eloi Bay Marsh Creation/Nourishment

Yes Yes

Marsh is intact and has not 

changed significantly since 1956.

North Lake Lery Marsh Creation No No

Biloxi Marsh Marsh Nourishment Yes Yes

Biloxi Marshes Marsh Creation and Shoreline 

Protection - B

Yes No

Marsh is intact and has not 

changed significantly since 1956.

Skiff Lake Marsh Creation

Yes Maybe

Marsh is intact and has not 

changed significantly since 1956.

Morgan Harbor Marsh Creation

Yes Yes

Removed from consideration due 

to concerns regarding impacts to 

oyster reefs and seed grounds.

Breton Marsh Creation - A (See Note 2)

Yes Yes

Marsh is intact and has not 

changed significantly since 1956.

Breton Marsh Creation - C (See Note 2)

Yes Yes

Marsh is intact and has not 

changed significantly since 1956.

Florissant Swamp Restoration

Yes Yes

Area not historically cypress; 

conditions not suitable for the 

development of a sustainable 

cypress swamp.

Hopedale Swamp restoration

Yes Yes

Area not historically cypress; 

conditions not suitable for the 

development of a sustainable 

cypress swamp.

Hopedale Marsh Restoration Yes Yes

Florissant Marsh Restoration Yes Yes

Biloxi Marshes Marsh Creation - Lake 

Athanasio. Yes Yes

Marsh is intact and has not 

changed significantly since 1956.

Marsh Creation South of Lake Lery No No

Marsh Creation east of Lake Calebass Yes Yes Removed from consideration due 

to concerns regarding impacts to Marsh Creation near St. Helena Bay Yes Yes
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

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Table 2-13. Steps 3 and 4: Marsh and Swamp Restoration Measures

Measure Name

Addresses 

Restoration of 

Lake Borgne 

Ecosystem

Addresses 

a MRGO 

Ecosystem 

Effect

Other Criteria

Marsh Creation West of Lake Jean Louis Robin Yes Yes oyster reefs and seed grounds.

Marsh Creation West of Lake Calebass Yes Yes

Note: Bold text indicates the measure was carried forward for further consideration.

2.6.1.4 Shoreline Protection Measures Initial Screening Results 

Initially, 58 shoreline protection measures were considered. Various shore protection alignments 

were initially screened to eliminate those deemed to be outside the Lake Borgne ecosystem or 

outside areas potentially affected by the MRGO. Breakwaters were screened out in Lake 

Borgne and Biloxi Marshes because they are less effective than foreshore protection. After 

screening, 26 shoreline protection measures were carried forward for further study (see Table 

2-14). 

Table 2-14. Steps 3 and 4: Shoreline Protection Measures

Measure Name

Addresses 

Restoration of 

Lake Borgne 

Ecosystem

Addresses 

a MRGO 

Ecosystem 

Effect

Other Criteria

Maintain Shoreline East Orleans 

Landbridge – C Yes No

Biloxi Marshes Shoreline Protection –

A No No

Would only protect a small area at a high 

cost due to water depth and geographic 

constraints.

Biloxi Marshes Shore Protection 

Interior A Yes No

Off-shore protection deemed less 

effective than near shore protection for 

erosion prevention.

Biloxi Marshes Shore Protection 

Interior C No No

Biloxi Marshes Shore Protection -

South C Yes No

Biloxi Marshes Shore Protection 

Interior B Yes No

Off-shore protection deemed less 

effective than near shore protection for 

erosion prevention.

Biloxi Marshes Shore Protection -

South A Yes No

Would only protect a small area at a high 

cost due to water depth and geographic 

constraints.

Skiff Lake Shoreline Protection No No

Would only protect a small area at a high 

cost due to water depth and geographic 

constraints.
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2-98 June 2012 

Table 2-14. Steps 3 and 4: Shoreline Protection Measures

Measure Name

Addresses 

Restoration of 

Lake Borgne 

Ecosystem

Addresses 

a MRGO 

Ecosystem 

Effect

Other Criteria

Maintain Lake Borgne Shoreline - B Yes No

State will build with surplus funds. Part of 

FWOP.

Maintain Shoreline East Orleans 

Landbridge – A Yes No

Lake Borgne Shoreline Protection - B Yes No

State will build with surplus funds. Part of 

FWOP.

Shoreline Protection (Potential 

Creation of SAV Habitat) Yes No

MRGO North Bank (MRGO Mile 23.2-

20.8) O&M Yes Yes

Removed as inefficient. Does not protect 

any land, could prevent natural filling in 

the channel.

Maintain Shoreline East Orleans 

Landbridge – B Yes No

Lake Borgne Shoreline Protection - A Yes No

State will build with surplus funds. Part of 

FWOP.

Biloxi Marshes Shore Protection -

South B No No

Biloxi Marshes Shore Protection -

North A Yes No

Maurepas Shoreline Protection - East Yes No

Marsh is intact and has not changed 

significantly since 1956.

Lake Borgne Shoreline Protection 

– C Yes No

MRGO North Bank (MRGO Mile 

33.8-32.6) O&M Yes Yes

Morgan Harbor Shoreline 

Protection Yes No

MRGO Shoreline Protection - H 

O&M Yes Yes

MRGO Shoreline Protection - G Yes Yes

Maurepas Shoreline Protection –

West Yes Maybe

Removed due to low benefit numbers 

from initial WVA and high cost.

Eloi Bay Shoreline Protection Yes No

Oyster Reef Development in Biloxi 

Marshes C (Foreshore Dike with 35 ' 

Berm for Reef) Yes Maybe Reefs in area already in good condition.

Biloxi Marshes Shore Protection -

North B

No No
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Final Feasibility Report 2: Plan Formulation 

2-99 June 2012 

Table 2-14. Steps 3 and 4: Shoreline Protection Measures

Measure Name

Addresses 

Restoration of 

Lake Borgne 

Ecosystem

Addresses 

a MRGO 

Ecosystem 

Effect

Other Criteria

MRGO Shoreline Protection - C 

O&M Yes Yes

MRGO Shoreline Protection - D 

O&M Yes Yes

MRGO South Bank (MRGO Mile 59-

47) O&M Yes Yes

Screened out because WVA assigned 

very few benefits.

Golden Triangle Shoreline Protection Yes Yes Covered by CIAP project.

MRGO Shoreline Protection - F 

O&M Yes Yes

Bayou Dupre/Lake Borgne Shoreline 

Protection Yes Yes

Covered by USACE project.

West of Shell Beach Shoreline 

Protection Yes Yes Covered by USACE project.

Biloxi Marshes Shoreline Protection –

B Yes No

Would only protect a small area at a high 

cost due to water depth and geographic 

constraints.

MRGO Shoreline Protection - B Yes Yes

Maintain Lake Borgne Shoreline –

A Yes No

MRGO Shoreline Protection - E Yes Yes

MRGO South Bank (MRGO Mile 

23.2-20.8) O&M Yes Yes

Removed as inefficient. Does not protect 

any land, could prevent natural filling in 

the channel.

MRGO South Bank (MRGO Mile 

37.3-36.5) O&M Yes Yes

Existing Articulated Concrete Mattress in 

good condition.

MRGO South Bank (MRGO Mile 

38.9-38.5) O&M Yes Yes

Existing Articulated Concrete Mattress in 

good condition.

MRGO South Bank (MRGO Mile 60-

59) O&M Yes Yes

Screened out because WVA assigned 

very few benefits.

Jean Louis Robin Shoreline 

Protection Yes Yes

West Lake Lery Shoreline Protection No No

South Lake Lery Shoreline 

Restoration No No

MRGO Shoreline Protection - A Yes Yes

In authorized part of the GIWW channel, 

O&M covered.
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Table 2-14. Steps 3 and 4: Shoreline Protection Measures

Measure Name

Addresses 

Restoration of 

Lake Borgne 

Ecosystem

Addresses 

a MRGO 

Ecosystem 

Effect

Other Criteria

Oyster Reef Development in Biloxi 

Marshes A (Via Crushed Stone) Yes Maybe

Not as effective for shoreline protection 

purpose as measure #98 - Oyster Reef 

Development in Biloxi Marshes C 

(Foreshore Dike with 35' Berm for Reef)

Breakwaters along Lake Borgne 

Shoreline Yes No

Not as cost effective as nearshore 

shoreline protection measures

Oyster Reef Development in Biloxi

Marshes B (Bio-Engineered Reef) Yes Maybe

Not as effective for shoreline protection 

purpose as measure #98 - Oyster Reef 

Development in Biloxi Marshes C 

(Foreshore Dike with 35' Berm for Reef)

Biloxi Marshes Shoreline Protection -

Offshore Artificial Reef No No

Not as cost effective as nearshore 

shoreline protection measures

LaBranche Wetlands Shoreline 

Protection No No

Sink Ships for Breakwater/Artificial 

Reef

No No

Lake Maurepas Shoreline Protection 

– A

No No

Lake Maurepas Shoreline Protection 

– B

No No

St. Tammany Shoreline Protection No No

Bay Boudreau Shoreline Protection Yes No

Duplicative with #98 Shoreline Protection

Note: Bold text indicates the measure was carried forward for further consideration.

2.6.1.5 Ridge Restoration Measures Initial Screening Results 

Initially, 55 ridge restoration measures were considered. The 55 measures were developed by 

combining five different sized ridges (historic, 50 ft, 100 ft, 150 ft, and 200 ft footprints) at 11 

locations. After screening, only two ridge restoration locations on the Bayou La Loutre Ridge 

were carried forward for further study (see Table 2-15). 

Ridge restoration consists of stacking sediment to a height conducive to the propagation of 

upland habitat. In areas where natural ridges are above marsh elevation and currently support 

upland habitat, ridge restoration would bury existing vegetation and replace it with vegetation 

considered to have greater habitat value. It was determined that the benefits derived from the 

higher habitat value would not justify the costs associated with raising the elevation and planting 

these features. 
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Similarly, in areas where the ridges have subsided to marsh elevation, ridge restoration would 

result in adverse impacts to marsh that must be considered in the calculation of benefits. The 

Bayou Terre aux Boeufs Ridge was removed from further consideration because it was 

determined that the negative impacts to existing upland and marsh habitats were greater than 

the ecosystem benefits of ridge restoration in this location. 

Portions of the south side of the Bayou La Loutre Ridge were identified that were above marsh 

elevation but did not have existing upland vegetation: these sections were retained for further 

evaluation. Ridge restoration designs were developed that minimized impacts to adjacent 

wetlands while providing suitable crown widths and slopes for establishing ridge species. 

Table 2-15. Steps 3 and 4: Ridge Restoration Measures

Measure Name

Addresses 

Restoration of 

Lake Borgne 

Ecosystem

Addresses 

a MRGO 

Ecosystem 

Effect

Other Criteria

Bayou La Loutre Ridge 

Restoration East - South Bank A 

200ft Yes Yes

Bayou La Loutre Ridge Restoration 

East - South Bank A 50ft Yes Yes

Crown width and slope not suitable for 

establishing oak ridge species.

Bayou La Loutre Ridge Restoration 

East - South Bank A 100ft Yes Yes

Crown width and slope not suitable for 

establishing oak ridge species.

Bayou La Loutre Ridge Restoration 

East - South Bank A 150ft Yes Yes

Crown width and slope not suitable for 

establishing oak ridge species.

Bayou La Loutre Ridge Restoration 

East - South Bank A historic width Yes Yes

Removed due to potential negative impacts 

to existing vegetation and marsh.

Bayou La Loutre Ridge Restoration 

East - South Bank B 50ft, 100 ft, 

150 ft, 200 ft, and historic width Yes Yes

Removed due to potential negative impacts 

to existing vegetation and marsh.

Bayou La Loutre Ridge Restoration 

East - North Bank A: 50ft., 100 ft., 

150 ft., 200ft., and historic width Yes Yes

Removed due to potential negative impacts 

to existing vegetation and marsh.

Bayou La Loutre Ridge Restoration 

East - North Bank B: 50ft., 100 ft., 

150 ft., 200ft., and historic width Yes Yes

Removed due to potential negative impacts 

to existing vegetation and marsh.

Bayou La Loutre Ridge Restoration 

West - North Bank A: 50ft., 100 ft., 

150 ft., 200ft., and historic width Yes Yes

Removed due to potential negative impacts 

to existing vegetation and marsh.

Bayou La Loutre Ridge Restoration 

West - South Bank A: 50ft., 100 ft., 

150 ft., 200ft., and historic width Yes Yes

Removed due to potential negative impacts 

to existing vegetation and marsh.

Bayou Terre aux Boeufs West 

Ridge Restoration A: 50ft., 100 ft., 

150 ft., 200ft., and historic width Yes Yes

Removed due to potential negative impacts 

to existing vegetation and marsh.
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2-102 June 2012 

Table 2-15. Steps 3 and 4: Ridge Restoration Measures

Measure Name

Addresses 

Restoration of 

Lake Borgne 

Ecosystem

Addresses 

a MRGO 

Ecosystem 

Effect

Other Criteria

Bayou Terre aux Boeufs West 

Ridge Restoration B: 50ft., 100 ft., 

150 ft., 200ft., and historic width Maybe Maybe

Removed due to potential negative impacts 

to existing vegetation and marsh.

Bayou Terre aux Boeufs West 

Ridge Restoration C: 50ft., 100 ft., 

150 ft., 200ft., and historic width Maybe Maybe

Removed due to potential negative impacts 

to existing vegetation and marsh.

Bayou Terre aux Boeufs East 

Ridge Restoration A: 50ft., 100 ft., 

150 ft., 200ft., and historic width Maybe Maybe

Removed due to potential negative impacts 

to existing vegetation and marsh.

Bayou Terre aux Boeufs East 

Ridge Restoration B: 50ft., 100 ft., 

150 ft., 200ft., and historic width Maybe Maybe

Removed due to potential negative impacts 

to existing vegetation and marsh.

Note: Bold text indicates the measure was carried forward for further consideration.

2.6.1.6 Vegetative Planting Measures Initial Screening Results 

Initially, 11 stand-alone vegetative planting measures were considered, which involved planting 

trees on the banks of the MRGO navigation channel. All of these measures were screened out 

(see Table 2-16). Measures to plant trees on the north bank of the MRGO were screened out 

because tree planting in that location is inconsistent with both the existing and historic marsh 

habitat. Measures to plant trees in front of the levee were screened out because they could 

potentially affect the structural integrity of the levee. Measures to plant trees on the spoil bank 

were screened out because the spoil banks are already well vegetated. 

Additional vegetative planting measures are being carried forward as integral components of 

other measures such as marsh, swamp, and ridge restoration. 

Table 2-16. Steps 3 and 4: Vegetative Planting Measures

Measure Name

Addresses

Restoration of 

Lake Borgne 

Ecosystem

Addresses 

a MRGO 

Ecosystem 

Effect

Other Criteria

Plant Trees in Front of Levee (Mile 

59 - 47) Yes Yes

Would violate maintenance criteria for 

levees.

Plant Trees on Spoil Bank – A Yes Yes

Disposal areas are already well vegetated 

and will likely develop into mature stands that 

could serve basically the same function as 

Plant Trees on Spoil Bank – C Yes Yes

Plant Trees on Spoil Bank – D Yes Yes
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Final Feasibility Report 2: Plan Formulation 

2-103 June 2012 

Table 2-16. Steps 3 and 4: Vegetative Planting Measures

Measure Name

Addresses

Restoration of 

Lake Borgne 

Ecosystem

Addresses 

a MRGO 

Ecosystem 

Effect

Other Criteria

Plant Trees on Spoil Bank – E Yes Yes more desirable tree species.

Plant Trees on Spoil Bank – B Yes Yes

Plant Trees on Spoil Bank – F Yes Yes

Vegetative Planting Trees North 

Bank of MRGO – A

No No

Vegetative Planting Trees North 

Bank of MRGO – B

No No

Vegetative Planting Trees North 

Bank of MRGO – C

No No

Vegetative Planting Trees North 

Bank of MRGO – D

No No

Note: Bold text indicates the measure was carried forward for further consideration.

2.6.1.7 Barrier Island Restoration Measures Initial Screening Results 

Initially, three barrier island restoration measures were considered. After screening, two barrier 

island restoration measures were carried forward for further study and several variations of 

these alternatives were developed (see Table 2-17). Cat Island was eliminated from further 

study because it is part of MsCIP. The MRGO channel was dredged between Breton and Grand 

Gossier Islands in the Chandeleur Islands Chain, and some scientists contend that the former 

navigation channel disrupted sediment transport to Breton Island. However, the impact to the 

islands from the MRGO, if any, is difficult to quantify with any degree of certainty because the 

erosion and migration patterns in place since the late 1800s were still operating in 2005, with no 

obvious change after construction of the MRGO (Britsch 2009). Barrier islands were not 

identified as critical landscape features with respect to storm surge risk reduction in the LACPR 

ADCIRC analyses (USACE 2009). Barrier island restoration was ultimately eliminated for 

implementation under this authority because of the insufficient nexus to MRGO effects, the Lake 

Borgne ecosystem, or storm surge damage risk reduction. Restoration of the barrier islands 

would not directly benefit the area targeted for restoration under this authority. Alternative 

barrier island restoration measures on the Chandeleur Island chain require further study to 

determine how to maximize benefits while minimizing risks to project performance. Further 

study of alternative barrier island restoration techniques should be conducted to protect and 

restore this significant coastal habitat. 
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Final Feasibility Report 2: Plan Formulation 

2-104 June 2012 

Table 2-17. Steps 3 and 4: Barrier Island Measures

Measure Name

Addresses 

Restoration of 

Lake Borgne 

Ecosystem

Addresses 

a MRGO 

Ecosystem 

Effect

Other Criteria

Cat Island Restoration Study Yes No

Would violate maintenance criteria for 

levees.

Chandeleur Islands (Not Breton & 

Grand Gossier) No No

Breton and Grand Gossier Island 

Restoration

No Maybe

No documented MRGO effect to the islands; 

channel between the islands is addressed 

under "Channel Filling Measures"

2.6.1.8 SAV Demonstration Projects Initial Screening Results 

Initially, two SAV demonstration projects were considered — one in Louisiana and one in 

Mississippi. The Louisiana SAV project was replaced with a breakwater/shoreline protection 

measure to allow expansion of established SAV on Lake Pontchartrain. The Mississippi project 

was screened out because it is recommended by the MsCIP report (see Table 2-18). 

Table 2-18. Steps 3 and 4: SAV Measures

Measure Name

Addresses 

Restoration of 

Lake Borgne 

Ecosystem

Addresses 

a MRGO 

Ecosystem 

Effect

Other Criteria

Mississippi SAV DEMO No No

Louisiana SAV DEMO

Yes Maybe

Replaced with breakwater to provide calming 

to allow expansion of established SAV on 

south shore of Lake Pontchartrain.

2.6.1.9 Artificial Oyster Reef Measures Initial Screening Results 

Initially, one artificial oyster reef measure was considered. This artificial oyster reef measure is 

not being carried forward to the final array of alternatives because the area identified is already 

in acceptable condition regarding oysters; however, various oyster reef designs were evaluated 

under shoreline protection (see Table 2-19). 

Table 2-19. Steps 3 and 4: Oyster Reef Measures

Measure Name

Addresses 

Restoration of 

Lake Borgne 

Ecosystem

Addresses 

a MRGO 

Ecosystem 

Effect

Other Criteria

Oyster Reef Development in the 

Biloxi Marsh Maybe Maybe

Area identified already in acceptable 

condition regarding oysters, oyster reef 

designs evaluated as shoreline protection 

measures.
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Figure 2-26. Preliminary Features Evaluated 

2.6.2 Summary of Initial Screening Results 

Screening the measures proposed in the initial array resulted in the elimination of 240 measures 

and the retention of 59 measures to be carried forward for refinement and detailed evaluation. 

The measures that were carried forward for further evaluation were further refined to produce 

more detailed designs, cost estimates, and quantification of outputs. 

2.7 ALTERNATIVE PLAN FORMULATION 

Alternative plans are combinations of management measures that collectively meet study goals 

and objectives within the defined study constraints. Alternative plans and their component 

management measures were assessed relative to the Federal objective of National Ecosystem 

Restoration (NER). 
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Final Feasibility Report 2: Plan Formulation 

2-106 June 2012 

A GIS database was utilized to catalogue study information including individual management 

measures, existing and authorized water projects, and study area existing conditions. The GIS 

enables the visual display and manipulation of information across the large study area. 

Additionally, the system allows the building and testing of various alternative combinations of 

management measures during the course of plan formulation. Thus, GIS serves as a decision 

support tool. 

2.7.1 Preliminary Evaluation of Measures 

Measures are compared against one another and assembled into alternative plans using 

performance outputs (benefits) and costs. 

Outputs (Benefits) 

Environmental outputs were measured using the Wetland Value Assessment (WVA) 

methodology (certified for this use by the USACE Ecosystem Planning Center of Expertise). The 

WVA quantifies changes in fish and wildlife habitat quality and quantity that are expected to 

result from a proposed wetland restoration project. The results of the WVA, measured in 

Average Annual Habitat Units (AAHUs), can be combined with cost data to provide a measure 

of the effectiveness of a proposed project in terms of annualized cost per AAHU gained. In 

addition, the WVA methodology provides an estimate of the number of acres benefited or 

enhanced by the project and the net acres of habitat protected/restored. The results of the 

WVAs (in AAHUs) were compared with annual costs in IWR-PLAN to develop alternative plans. 

The WVA model was used to determine the most effective measures for each habitat type 

identified for restoration in the study planning objectives. The WVA methodology uses different 

models for each habitat type, which facilitates the comparison of restoration measures by type. 

The WVA model does not assign different values to different types of habitat. An AAHU of 

brackish marsh has the same benefit as an AAHU of ridge habitat in the WVA model, although 

coastal ridge habitat is extremely scarce and brackish marsh is relatively abundant. Therefore, 

other important considerations, such as habitat type scarcity, contribution to overall ecosystem 

function, whether a measure addresses a direct effect of the MRGO, and contribution to 

restoration of critical landscape features were evaluated qualitatively for alternative plan 

combinations developed by IWR-PLAN. 

WVA requires estimates of FWP and FWOP marsh acreages. Wetland acreage data (1985 through 

2006) was obtained from the USGS for each of the study area subunits. FWOP subunit wetland 

acreages were determined via a linear trendline through those data (Figure 2-27). Where applicable, 

annual net acreage benefits associated with pre-existing or soon to be constructed restoration 

projects were added to the base subunit FWOP acreages to obtain revised FWOP subunit acreages. 

The SAND2 method was used to predict accretion rates in areas benefitted by freshwater diversions. 

This model is an Engineering Research and Development Center (ERDC) revision of the SAND1 

(Boustany-ERDC spreadsheet model) used in the Louisiana Coastal Protection and Restoration 

Final Technical Report (LACPR). The WVA model used this engineering input to assess benefits. 
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Final Feasibility Report 2: Plan Formulation 

2-107 June 2012 

Given the great uncertainties regarding future subsidence rate changes, sea-level rise changes, and 

many other factors that might affect future wetland loss rates over the project life, there is 

considerable uncertainty regarding the accuracy of the predicted river diversion benefits. However, 

the SAND2 model provides an objective means for comparing alternative measures and plans. 

Utilizing the predicted FWOP wetland acreage as a basis, the SAND2 model calculates FWP 

benefits (in acres) via the accretion of suspended sediments (land building) together with the effects 

of nitrogen additions. The nitrogen benefits (in acres) are calculated as the grams of nitrogen 

required to produce a wetland acre multiplied by the grams of introduced nitrogen (less nitrogen lost 

to denitrification), which equals wetland acres restored/supported via introduced nitrogen. 

Figure 2-27. Actual and Predicted Acreage for Subunit 17. 

Sustainability 

The benefits analysis utilized for the MRGO Ecosystem Restoration Plan considers 

sustainability inherently. Because the WVA methodology utilizes historic land loss rates in the 

calculation of benefits, areas that have historically been more susceptible to risks such as 

tropical storms, subsidence, and sea level rise, will have fewer AAHUs than areas that have not 

been as susceptible to these factors. The SAND2 methodology accounts for the greater 

sustainability of features nourished by the freshwater diversion by assigning more AHHUs to 

features in the diversion influence area. Additionally, the WVA methodology assigns greater 

benefits to features that include natural vertical accretion than protection features like shoreline 

protection that require maintenance. 

15,000

17,000

19,000

21,000

23,000

25,000

27,000

29,000

31,000

19801990200020102020203020402050206020702080

Subunit 17 Acreage

Actual data

Predicted acres
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 2: Plan Formulation 

2-108 June 2012 

The initial WVA analysis was conducted for each feature individually and did not consider 

synergies with other restoration projects proposed as part of this plan. The initial WVAs did 

consider existing, authorized and planned projects that were included in the FWOP condition. 

The Violet, Louisiana Freshwater Diversion was assumed to be operational in 2015 in the 

analysis. 

Costs 

Preliminary costs were developed for measures remaining after initial screening. Material 

quantities were developed for each measure based on assumptions about existing land 

elevations, required containment dikes and interior weirs, access channels, borrow sources and 

shoreline protection sections. Further information on these assumptions can be found in the 

Engineering Appendix. 

The preliminary cost estimates for the MRGO Ecosystem Restoration Plan Feasibility Study 

were prepared based on readily available New Orleans District data and quantities provided by 

Waterways Section, Civil Branch. The estimated costs were based upon an analysis of each 

line item evaluating quantity, production rate, and time, together with the appropriate equipment, 

labor, and material costs or the costs were based on in-house knowledge and experience by 

New Orleans District cost engineers who estimated similar projects. Cost Estimates were 

developed using historical data, CEDEP, and Mii estimating software. 

The project consists of various combinations of marsh restoration, marsh nourishment, ridge 

restoration, swamp nourishment and shoreline protection. The marsh restoration, marsh 

nourishment, and swamp nourishment were constructed using typical dredge and fill techniques 

from nearby borrow sources such as interior bays, Lake Borgne, Lake Lery, Breton Sound, and 

the Mississippi River. It is anticipated that cutterhead pipeline dredges would excavate the 

native material and pump it to the project sites. The largest dredge that could do the work was 

typically chosen given the large quantities and long pump distances. Dredge size was limited by 

the available depth in the access route and the proposed borrow areas (24-inch to 30-inch 

dredge sizes assumed). Nourishment and restoration areas included earthen retention dikes, 

weirs, and earth and sheetpile closure structures as required. Given the remote locations of the 

projects, all work is assumed to be marine based. All materials for the shoreline protection 

alternatives will be delivered by barge. All features were estimated based on standard 

construction methods all of which are common to the New Orleans District and South Louisiana. 

The estimates assumed access was available to proposed areas unless otherwise stated. 

Following preliminary planning, further investigations were made to verify accessibility 

assumptions. Each measure cost was developed independently and assumed equipment 

availability is not an issue. Contingencies of 20 to 30 percent were added to all cost estimates 

based on the level of uncertainty to produce conservative worst-case scenario costs for 

planning purposes while detailed engineering information was collected and analyzed. E&D of 

4% and S&A of 6% were also added to each estimate. The initial costs developed for planning 

purposes reflected only construction costs and did not include real estate, OMRR&R, or 

adaptive management. Some costs changed when site specific geotechnical and survey data 
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Final Feasibility Report 2: Plan Formulation 

2-109 June 2012 

were applied. The cost-effectiveness of features was re-evaluated when detailed information 

became available. Costs were developed with October 2009 price levels using a four percent 

discount rate and 0.04655 amortization factor. The detailed cost-estimates did not significantly 

alter the cost-effectiveness of any plan feature. 

Table 2-20 provides the costs and benefits generated for the formulation and analysis of plans. 

Table 2-20. Measures Retained for Plan Formulation

Geographic Area Measure Label Total AAHU Annual Cost*

E. Orleans Landbridge 010a 147 1,318,785

E. Orleans Landbridge 010b 578 7,610,542

E. Orleans Landbridge 011 156 648,743

E. Orleans Landbridge 007 89 1,889,288

E. Orleans Landbridge 009 500 2,385,457

E. Orleans Landbridge 005sp 74 758,201

E. Orleans Landbridge 006sp 77 958,944

E. Orleans Landbridge 007sp 188 3,012,971

E. Orleans Landbridge 090 15 330,464

S. Lake Borgne 028 84 1,236,516

S. Lake Borgne 014 832 5,911,103

S. Lake Borgne 015a 551 2,348,644

S. Lake Borgne 008sp 128 1,979,597

S. Lake Borgne 015c 569 1,965,753

S. Lake Borgne 030sp 7 130,898

S. Lake Borgne Fill in MRGO1

1,932 159,995,564

MRGO Channel 099 0.01 143,223

MRGO Channel 100 0.02 813,422

MRGO Channel 024 22 1,400,723

MRGO Channel 021 20 340,306

MRGO Channel 022 20 326,590

MRGO Channel 025 7 175,561

MRGO Channel 027 32 1,770,019

MRGO Channel 026 40 2,736,228

MRGO Channel 087 5 316,098

MRGO Channel 104 3 104,483

Central Wetlands 025a 271 6,207,018

Central Wetlands 025b 134 3,283,973

Central Wetlands 026a 158 5,020,967

Central Wetlands 026b 303 2,856,953

Central Wetlands 026c 136 1,446,291

Central Wetlands 026d 33 1,350,766

Central Wetlands 026e 196 14,406,107

Central Wetlands 027a 369 7,055,378

Central Wetlands 027b 384 8,860,530

Biloxi 081 373 5,873,225

Biloxi 042 73 6,446,604

Biloxi 020 159 4,796,356
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2-110 June 2012 

Table 2-20. Measures Retained for Plan Formulation

Geographic Area Measure Label Total AAHU Annual Cost*

Biloxi 010sp2

100 1,397,042

Biloxi 011sp2

91 566,508

Biloxi 013sp2

179 2,639,700

Biloxi 014sp 142 4,414,464

Biloxi 98asp 66 2,171,273

Biloxi 98bsp 120 4,863,397

Biloxi 111sp 58 1,901,045

Biloxi 017sp 31 1,239,152

Biloxi 107sp 35 1,223,905

Biloxi 029asp3

137 2,084,680

Biloxi 110 130 4,994,804

Bayou La Loutre Ridge 133a 8 865,399

Bayou La Loutre Ridge 133a + 133b 14 1,510,834

Terre aux Boeufs 002a 358 2,266,837

Terre aux Boeufs 002b 823 9,815,257

Terre aux Boeufs 002c 552 5,087,244

Terre aux Boeufs 245 1,545 4,829,628

Terre aux Boeufs 2434

425 1,354,619

Terre aux Boeufs 2444

984 4,217,112

Terre aux Boeufs 2414

1,051 5,186,676

Terre aux Boeufs 2424

972 2,066,854

Florissant 191 12 1,576,410

Hopedale 190 186 2,054,465

Jetty Realignment 029bsp + 0285

232 3,392,549

Notes:

* October 2009 

1

Exclusive of other MRGO measures.

2

Subsequently removed from consideration as the State of Louisiana is planning to build these 

features with surplus funds.

3 Due to survey findings that water depths are infeasible for traditional foreshore protection, measure 

was changed to oyster reef restoration.

4

Subsequently removed due to impacts to oyster reefs and seed grounds.

5 Due to survey findings, this measure was removed from further consideration.

Relative Sea Level Rise Considerations 

Potential increases in RSLR, as noted in the future without project conditions, could impact the costs 

and benefits developed for these features. These potential impacts and associated OMRR&R and/or 

adaptive management actions were assessed for all of the features retained for plan formulation. 

OMRR&R actions were calculated as part of the project costs. Additional adaptive management 

measures associated with increased RSLR scenarios were also incorporated into the project costs. 

The first O&M event for brackish marsh was determined by the calendar year of predicted marsh 

collapse used in the WVA. Marsh collapse is when the observed condition of a defined area loses a 
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Final Feasibility Report 2: Plan Formulation 

2-111 June 2012 

significant amount of marsh through erosion or inundation resulting in a  ̳collapse‘ where the 

remaining marsh is lost at an accelerated rate. For the MRGO Ecosystem Restoration study under 

the medium RSLR condition, the predicted marsh collapse in brackish marsh habitat occurs in 

calendar year 2058 (or target year 44). For OMRR&R, target year 39 (calendar year 2053) is used to 

precede the predicted marsh collapse event in target year 44 for brackish marsh. 

The amount of marsh lost that would need to be replaced during an O&M event was calculated by 

taking the difference of the peak amount of marsh created and or nourished and the amount of 

marsh left in a particular target year. For brackish marsh habitat, the target year 39 is used. For 

swamp habitat, target year 35 is used. 

The 50 year land loss totals for the MRGO restoration project were calculated by USFWS using the 

three levels of RSLR. The total amount of land remaining for any single project feature at the end of 

50 years for the low RSLR is no less than 83%. The total amount of land remaining for any single 

project feature at the end of 50 years for the medium RSLR is no less than 69%. OMRR&R and 

adaptive management measures would address risks and uncertainties. 

Under the high sea level rise rate, all wetland restoration features lose significant amounts of 

land, and all shoreline protection features would require significant adaptive management 

actions. The diminished output under the high RSLR scenario necessitates a systematic 

approach to assess and respond to the high RSLR. Sea level rise rates will be monitored in the 

pre-construction, construction, and post construction phases. Data will be evaluated at key 

decision points. An assessment of relative sea level rise trends would be made prior to 

partnership agreements, PED, construction award and any cost shared Adaptive Management 

actions. If at any time data indicate that the high level of RSLR is occurring, additional Federal 

investments in the plan would be re-assessed. 

2.7.2 Cost Effectiveness/Incremental Cost Analysis 

Cost effectiveness/Incremental Cost Analysis (CE/ICA) are two distinct analyses that must be 

conducted to evaluate the effects of alternative plans. First, it must be shown through cost 

effectiveness analysis that an alternative restoration plan‘s output cannot be produced more 

cost effectively by another alternative. ―Cost effective‖ means that, for a given level of nonmonetary output, no other plan costs less, and no other plan yields more output for less money. 

Subsequently, through incremental cost analysis, a variety of implementable alternatives and 

various-sized alternatives are evaluated to arrive at a ―best‖ level of output within the limits of 

both the sponsor‘s and the Corps‘ capabilities. 

The subset of cost effective plans are examined sequentially (by increasing scale and increment 

of output) to ascertain which plans are most efficient in the production of environmental benefits. 

Those most efficient plans are called ―Best Buys‖. They provide the greatest increase in output 

at the lowest average cost. ―Best Buys‖ have the lowest incremental costs per unit of output. In 

most analyses, there will be a series of Best Buy plans, in which the relationship between the 

quantity of outputs and the unit cost is evident. As the scale of Best Buy plans increases (in 

terms of output produced), average costs per unit of output and incremental costs per unit of 
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Final Feasibility Report 2: Plan Formulation 

2-112 June 2012 

output will increase as well. Usually, the incremental analysis by itself will not point to the 

selection of any single plan. The results of the incremental analysis must be synthesized with 

other decision-making criteria (for example, significance of outputs, completeness, 

effectiveness, acceptability, risk and uncertainty, reasonableness of costs) to support the 

selection and recommendation of a particular plan. The Corps‘ Institute for Water Resources 

(IWR) has developed procedures and software to assist in conducting CE/ICA. IWR-PLAN Decision 

Support Software was used to assist in performing CE/ICA for this study.

2.7.2.1 Minimum Planning Increment 

Despite the use of AAHUs to describe the benefits for all habitat types, all AAHUs are not 

equivalent. The comparison of AAHU values across habitat types should be addressed 

qualitatively when planning in a systems-based context, because diverse habitats are needed to 

restore the function of the system as a whole. Additionally, ER 1105-2-100 notes that the 

concept of significance of outputs plays an especially important role in ecosystem restoration 

planning. Several measures were considered necessary components of a plan that addressed 

the study authority, considered the significance of ecosystem outputs, and adhered to the 

Guiding Principles developed for the study. A minimum planning increment was included in the 

plan formulation process to produce alternatives that would address the study authority and 

consider significance of outputs, completeness, effectiveness, and acceptability, prior to the 

evaluation of efficiency through CE/ICA analysis. 

Cypress and Coastal Ridge Habitat 

In an abstract evaluation of cost per AAHU, cypress and coastal ridge restoration measures are 

not as cost-effective as other types of measures. These restoration measures require more 

sediment and more time to achieve benefits than marsh restoration, and therefore have much 

higher costs compared to benefits. For example, if an existing site is at mean sea level, marsh 

restoration requires fill to be placed at a settled elevation of approximately 1.5 ft.; cypress 

swamp requires +2.0 ft; and ridge requires +8.0 ft. Therefore, swamp requires 33% more fill 

than marsh, and ridge requires 433% more fill than marsh, given the same site conditions. In 

addition, marsh restoration will be fully vegetated in a few years, whereas cypress and ridge 

require decades to mature. 

Restoration of cypress and ridge habitat was considered necessary to fulfill the requirements of 

the study authority to ―restore the areas affected by the navigation channel,‖ as documented in 

Habitat Impacts of the Construction of the MRGO and Louisiana Coastal Area Ecosystem 

Restoration Study (USACE 1999, 2004). 

 The former navigation channel was cut through the Central Wetlands and the Bayou La 

Loutre ridge, directly impacting these areas. 

 The Central Wetlands is the only area in the immediate vicinity of the MRGO that could 

support cypress swamp, a scarce habitat rich in biodiversity. Other locations are outside 

of the project area (Caernarvon) or far removed from the channel (LaBranche and 

Maurepas). 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 2: Plan Formulation 

2-113 June 2012 

 The only remaining natural ridge in the immediate vicinity of the MRGO is the Bayou La 

Loutre ridge. This habitat is technically significant because of its scarcity, biodiversity, 

and function as a limiting habitat on which species of concern depend (Conner and Day 

1988, Twedt and Portwood 1997, Barrow et al. 2000, USGS 2006, Barrow et al. 2006). 

 Cypress swamp habitat is increasingly scarce and provides unique habitat and 

ecological functions, contributing to the technical significance of these resources 

(Lowery 1974, Conner and Toliver 1990, Messina and Conner 1998, Martin et al. 2002). 

 The restoration of cypress swamp in the Central Wetlands is widely supported by the 

adjacent communities, NGOs, state and local government, and resource agencies, 

demonstrating its public significance (University of Wisconsin-Madison 2008 and 2009, 

SLFPA-E 2009, Day et al. 2006). 

 The ecosystem services provided by these habitat types (e.g. avian and mammalian 

habitat) cannot be provided by other habitat types in the study area (Messina and 

Conner 1998, Barrow et al. 2000, USGS 2006, Barrow et al. 2006). 

Cypress swamps and coastal ridge, once common habitats in the study area, are now 

increasingly scarce. In the immediate vicinity of the MRGO, 99% of cypress habitat has been 

converted to brackish marsh or open water since 1956 (USGS 2009). These habitats are 

technically significant because of their contribution to biodiversity; importance to species of 

concern; and contribution to the geographic form of the ecosystem. Cypress swamps provide 

critical nesting habitat for the bald eagle, the emblem of the United States. Fortunately, 

significant conservation actions have resulted in the removal of the bald eagle from the federally 

threatened species list. However, the national bird is protected by the Bald and Golden Eagle 

Protection Act of 1940, demonstrating the institutional significance of this species and its 

habitat. The institutional and public value of cypress swamps was recognized by the Louisiana 

government in 2005, when the findings of a technical task force that the state should ―place 

priority on conserving, restoring, and managing coastal wetland forests...to ensure that their 

functions and ecosystem services will be available to present and future citizens of Louisiana 

and the United States‖ were adopted (Chambers et al. 2005). Coastal forest habitats provide 

critical rookeries for seventeen species of wading birds that are known to regularly occur in 

Louisiana. Louisiana is believed to have the largest population of wading birds in the United 

States due to the biodiversity provided by its unique ecosystems (Fontenot and DeMay 2008) 

Millions of migratory birds depend upon Louisiana‘s coastal forests as wintering and stopover 

habitat (NWF 2011). The prothonotary warbler is one example of a species associated with 

cypress-tupelo stands that is listed as a Tier 1 priority species by Partners in Flight because of 

the dramatic loss of this habitat nationwide (Partners in Flight 2006). The cypress-tupelo forests 

of Louisiana are vital for the long-term survival of this, and many other, songbird species that 

use Louisiana‘s coastal wetland forests for breeding and/or wintering habitat (Lowery, 1974). 

The coastal forests of the study area are included as ―Important Bird Areas‖ designated by the 

Audubon Society as critical breeding, wintering, and stopover habitat for birds of conservation 

concern (Audubon 2011). The Important Bird Areas Program relies heavily on volunteer efforts, 

and citizen participation in state-wide data collection efforts such as Christmas Bird Counts, 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 2: Plan Formulation 

2-114 June 2012 

Breeding Bird Surveys, and the Louisiana Winter Bird Atlas demonstrates the public significance 

of these species and their habitat. 

The restoration of these habitats was integral to the development of a complete, effective, 

efficient, and acceptable plan. By definition, the most effective and efficient plan would fully 

achieve the target objective. Therefore, IWR-PLAN formulation was developed to produce plans 

that include features to achieve these objectives. As the ridge habitat does not have a specified 

acreage amount, two scales of ridge restoration were developed, and the smaller feature 

closest to the channel was selected for inclusion in the minimum planning increment. Abstractly, 

any amount of ridge habitat would satisfy the objective. However, a smaller ridge restoration 

project would be less sustainable than the two scales of ridge restoration developed. The first 

increment of ridge that is included in the minimum planning increment starts at the restored 

hydrologic barrier created by the MRGO rock closure and extends to an existing canal. While 

this increment does not fully restore the ecological, hydrologic, surge reduction, and geographic 

functions of the historic Bayou La Loutre ridge, the feature was developed between two logical 

termini to produce a plan component with independent utility. 

The addition of these features in a minimum planning increment provides 10,318 acres of 

cypress swamp restoration and 54 acres of ridge restoration, at a cost of approximately $845 

million (October 2011 Price Levels). 

Recommendations for MRGO Channel 

Similarly, the inclusion of some features in the MRGO is required to address the LCA NearTerm Project described in Section 7006 (c)(1)(A) and the portion of the 7013 authority requiring 

―a plan to physically modify the Mississippi River-Gulf Outlet‖, despite the relative costeffectiveness of these features. 

Bank reclamation and stabilization along the MRGO is important to prevent the further 

confluence of the MRGO and Lake Borgne and to maintain the MRGO/Lake Borgne 

Landbridge. A plan that did not include features in the MRGO would likely be unacceptable to 

the public and did not appear to meet the Congressional intent of the study. Stabilization of the 

MRGO banks would preserve estuarine wetlands and important structural features of the lake 

and marsh landscape. The MRGO features would prevent future land loss and restore 

previously degraded wetlands; stabilize and restore the endangered, critical Lake Borgne rim 

geomorphic structure; and protect vital socioeconomic resources, such as communities located 

adjacent to the MRGO. 

The Lake Borgne estuarine complex is deteriorating and recent analysis indicates that the rate 

of wetland loss in the area is accelerating. Rapid action is required to protect the integrity of the 

southern Lake Borgne shoreline and to prevent continued erosion of the MRGO channel banks. 

Without action, critical landscape components that make up the Lake Borgne estuary would be 

lost and future efforts to restore other parts of the ecosystem would be much more difficult and 

expensive if not impossible. 

The following previous studies have described the need for bank stabilization along the MRGO: 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 2: Plan Formulation

2-115 June 2012 

 EA #47, MRGO Foreshore Protection 

(1985); MRGO St. Bernard Parish, 

Louisiana, Reconnaissance Report 

(1988) 

 EA #72, MRGO Breton Sound Jetty 

Repairs (1988) 

 EA #152, MRGO St. Bernard Parish, LA, 

Bank Stabilization, Miles 50.5 to 55.0 

(1991) 

 EA #162, Mississippi River – Gulf Outlet, 

St. Bernard and Plaquemines Parishes, 

LA – Marsh Enhancement/Creation and 

Berm Construction (1992) 

 EA #244, MRGO Back Dike (CWPPRA), 

Disposal Area Marsh Protection, Back 

Dike (1996) 

 EA #247, MRGO St. Bernard Parish, LA, 

Bank Stabilization Miles 55.0 to 56.1 

(1996); MRGO North Bank Foreshore 

Protection Evaluation (1996) 

 EA #255, MRGO, LA, Wetland Creation, 

Miles 15.0 to 23.0, St. Bernard and 

Plaquemines Parish, LA (1997) 

 EA #269, MRGO, LA, South of Lake 

Borgne Additional Disposal Areas, St. 

Bernard Parish, LA (1998) 

 EA #274, MRGO, Additional Disposal 

Areas, Hopedale Marshes (1998) 

 Coast 2050: Toward a Sustainable 

Coastal Louisiana (1998) 

 EA #288, MRGO Mile 43 to Mile 41 North 

Bank Stabilization, St. Bernard Parish, 

LA (1999) 

 EA #269-B, MRGO, South of Lake 

Borgne Additional Disposal Areas plus 

Deflection Dike and Floatation Channels, 

St. Bernard Parish, LA (2000) 

 EA #277, MRGO, LA, Shell Beach 

Disposal Areas, St. Bernard Parish, LA 

(2001) 

 MRGO Reevaluation Study (2002) 

 EA #349, MRGO, Miles 32-27, Additional 

Disposal Areas – Hopedale Marshes, St. 

Bernard Parish, LA (2002) 

 EA #355, MRGO Mile 27.0 to 0 (2003) 

 EA #361, MRGO, LA, Test Installation of 

Articulated Concrete Mattressing, Miles 

39.0 to 38.0 (2003) 

 Lake Borgne and MRGO Shoreline 

Protection between Doulluts Canal and 

Lena Lagoon (CWPPRA 2003) 

 EA #354, MRGO, Additional Disposal 

Area Designation Miles 66.0 to 49.0, St. 

Bernard Parish, LA (2004) 

 EA #402Lake Borgne – MRGO, 

Shoreline Protection Project, St. Bernard 

Parish, LA (2004) 

 EA #403 MRGO, Hopper Dredging Miles 

27.0 To 66.0 (2004) 

 EA #411, MRGO, Installation of 

Articulated Concrete Mattressing, Miles 

37.4 to 36.5, St. Bernard Parish, 

Louisiana (2004) 

 Ecological Review, Lake Borgne and 

MRGO Shoreline Protection (2005) 

 LCA (2005) 

 Louisiana Coastal Impact Assistance 

Program (2006) 

 Environmental Assessment for the Lake 

Borgne Shoreline Protection Project 

(2006) 

 LACPR (2006) 

 Integrated Ecosystem Restoration and 

Hurricane Protection: Louisiana‘s 

Comprehensive Master Plan for a 

Sustainable Coast (2007) 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 2: Plan Formulation

2-116 June 2012 

Bank stabilization in the MRGO was identified as a critical near-term need in the LCA report. 

The implementation guidance for the MRGO Ecosystem Restoration Plan states that the 

Section 7006 project ―shall be held in abeyance until the tentatively selected plan for ecosystem 

restoration, authorized by Section 7013 of WRDA 2007, is identified.‖ The implementation 

guidance also states that the feasibility report and EIS for Section 7013 of WRDA 2007 will 

include recommendations regarding the Section 7006 project. 

Shoreline protection features on the south shore of the MRGO were determined to have limited 

ecosystem restoration benefits because the areas protected are levees or spoil banks. 

Maintenance of shoreline protection features adjacent to levees will be conducted as needed as 

part of levee maintenance. Channel back-filling measures were determined to be among the 

least cost effective features evaluated in the plan, due to the depth of the MRGO and the 

amount of sediment required. Maintenance of existing shoreline protection features and channel 

narrowing features on the north shore of the channel produced more habitat benefits and were 

more cost effective than other features proposed in the MRGO. However, when compared to 

features in other areas, the MRGO features were less cost-effective. 

Although the MRGO features were determined to be less cost-effective than other restoration 

features considered, it was determined that the most cost-effective MRGO features should be 

included in the recommendations for this study. The inclusion of the most cost effective MRGO 

features in the recommendations for the study serves to ―integrate the recommendations of the 

report with the program authorized under section 7003‖ as noted in the study authority. 

Maintaining existing bank stabilization features along the north shore of the MRGO are the 

lowest cost features evaluated for this study. Maintenance of these features has ceased since 

the deauthorization of the channel. At this time, these features will not be maintained unless a 

non-federal sponsor is identified and funds are appropriated for implementation of these 

features. These features are less cost effective than other shoreline protection features because 

of the way WVA benefits are calculated. Because there are existing bank stabilization features 

in these locations, the projected erosion and land loss is less than in areas where there is no 

existing shoreline protection. Benefits are calculated by comparing the future without project 

condition to the future with project condition; therefore, maintenance of existing structures 

produces fewer benefits than construction of new features, despite the increased costs. Existing 

shoreline protection features in the MRGO are anticipated to become submerged within the 

period of analysis if they are not maintained. A first maintenance event for the existing foreshore 

protection in the MRGO was added to all of the alternatives in the final array to maintain the 

existing bankline and prevent land loss along the MRGO/Lake Borgne Landbridge. Any 

subsequent OMRR&R would be the non-Federal sponsor‘s responsibility. In addition, new 

shoreline protection is proposed for the area south of Bayou La Loutre in the vicinity of the 

closure structure and three channel narrowing features are proposed as part of the final array of 

alternatives. 

Protection and restoration of the south Lake Borgne/MRGO landbridge is technically and 

institutionally significant because these wetlands are specifically targeted for protection and 

restoration in WRDA 2007 Section 7006 and 7013 and the documents cited above. These 

features are also publicly significant as demonstrated by significant public comment to restore 

the area to a pre-construction condition; the actions and publications of the MRGO Must Go 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 2: Plan Formulation 

2-117 June 2012 

Coalition; and Louisiana House Concurrent Resolution 34 (2005) to ―...direct the United States 

Army Corps of Engineers not to engage in any dredging activities on the Mississippi River Gulf 

Outlet, and to begin the necessary process to return the waterway to wetlands marsh status as 

close as possible to what it was prior to establishment of the canal.‖

The most cost-effective measures for the MRGO were included in all plans in the final array. 

These seven measures provide 26.5 miles of shoreline protection and restore and protect 1,171 

acres of intermediate marsh at a cost of approximately $120 million (October 2011 Price 

Levels). An additional increment provides 6 miles of shoreline protection using vinyl sheetpile 

wall for bank reclamation and containment for fill to restore and protect 360 acres of 

intermediate marsh at a cost of approximately $53 million (October 2011 Price Levels). 

Violet, Louisiana Freshwater Diversion 

Alternatives that did not include a freshwater diversion were considered in the initial 

development of alternatives. These alternatives were ultimately eliminated from further study as 

inconsistent with the study goals and objectives and the ―Guiding Principles‖. A small freshwater 

diversion would not mimic periodic overbank flooding of the Mississippi River, a key process of 

the estuary that preliminary analyses indicate is needed to fully re-establish historic salinity 

gradients, habitat types, and increase self-sustainability in the system. 

The Violet, Louisiana Freshwater Diversion is technically significant because the man-made 

separation of the Mississippi River from the wetlands has decreased biodiversity and increased 

the scarcity of native marsh habitats. These effects were exacerbated by the construction of the 

MRGO and the resultant saltwater intrusion (USACE 1999). A freshwater diversion would 

restore this connection and increase marsh productivity and vertical accretion (DeLaune et al. 

2003). 

The Violet, Louisiana Freshwater Diversion is institutionally significant because it is included in 

federal, state and local plans (Louisiana Master Plan, CIAP, and CWPPRA). The public 

significance of the diversion is demonstrated by support from regional NGOs (LPBF 2006b, Day 

et al. 2006, Lopez et al. 2010).

Violet, Louisiana Freshwater Diversion Recommendations 

The restoration of historic salinity conditions is a key system driver. The Violet, Louisiana 

Freshwater Diversion, as authorized for design and implementation in WRDA 2007 Section 

3083, would fully restore salinity conditions, mimic natural processes, and enhance the 

sustainability of the system through the input of freshwater, nutrients and sediment. Full 

restoration of historic habitat types in the area is dependent upon salinity conditions. 

Additional study is needed to improve decisions about where, when, and how to divert Mississippi 

River flows in a systems context. The ongoing Mississippi River Hydrodynamic and Delta 

Management Study will evaluate ecosystem restoration alternatives in concert with dynamic flood risk 

management and navigation; multipurpose management scenarios of the river; and dynamic 

conditions in a comprehensive systems context. The information gained from this study will improve 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 2: Plan Formulation 

2-118 June 2012 

decision-making for the Violet, Louisiana Freshwater Diversion. Therefore, the final 

recommendations for the MRGO Ecosystem Restoration Plan include additional analysis, design and 

implementation of the Violet, Louisiana Freshwater Diversion as authorized by WRDA 2007 Section 

3083. 

Summary of Minimum Planning Increment 

The following measures were included as a minimum increment for further plan formulation. 

 10,318 acres of cypress swamp restoration and 54 acres of ridge restoration at a cost of 

approximately $845 million (October 2011 Price Levels). 

 Seven MRGO measures that provide 18 miles of shoreline protection and restore and 

protect 764 acres of intermediate marsh at a cost of approximately $120 million (October 

2011 Price Levels). An additional increment provides 6 miles of shoreline protection using 

vinyl sheetpile wall for bank reclamation and containment for fill to restore and protect 360 

acres of intermediate marsh at a cost of approximately $53 million (October 2011 Price 

Levels). 

 The Violet, Louisiana Freshwater Diversion to restore and maintain the salinity regime of the 

estuary, mimic natural historic processes, and increase the sustainability of the area. 

These measures are considered critical for the formulation of a plan that addresses the study 

authority and achieves the goals and objectives. These features are the basis for the formulation of a 

complete, effective, efficient, and acceptable plan through the CE/ICA process. 

IWR-PLAN Steps 

The Corps‘ Institute for Water Resources (IWR) has developed procedures and software to 

assist in conducting CE/ICA. IWR-PLAN Decision Support Software was used to assist in 

performing CE/ICA. Given the computational limitations of the IWR-PLAN software, the over 50 

individual measures could not be run in IWR-PLAN simultaneously (all measures are 

combinable). Therefore, separate runs were made in each major geographic area to limit the 

number of possible combinations. 

Some scale of restoration in these geographic areas was considered necessary to address the 

study authority to ―restore the areas affected by the navigation channel‖ and ―restore natural 

features of the ecosystem that will reduce or prevent damage from storm surge.‖

The Biloxi Marsh geographic area consists of Subunits 07 - Biloxi Marshes Interior, and 18 - Eloi 

Bay. These subunits compose a unique geomorphologic feature that has been identified as a 

critical landscape feature for storm surge damage risk reduction and is technically significant, in 

terms of scarcity and connectivity, as a geologic barrier for storm surge reduction (USGS 1994, 

USACE 2009, Walmsley et al. 2009, Howes et al. 2010, Shepard et al. 2011). The Biloxi Marsh 

also supports oyster reef habitat, which is arguably the most imperiled marine habitat on earth 

(Beck et al. 2011). This area is institutionally significant because it is protected by significant 

legislation promoting the conservation of the nation‘s wetlands and estuaries in general, and the 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 2: Plan Formulation 

2-119 June 2012 

significance of the Gulf of Mexico ecosystem as recognized by President Obama‘s

administration in particular (EPA et al. 2011). This area is publically significant because of its 

recreational value and importance as an area that can ―potentially reduce the loss of life and 

property due to flooding‖ (Burkett et al. 2002). The primary problems in this area are the lack of 

freshwater and sediment, and wind driven shoreline erosion. Unlike other subunits, this area 

has relatively low subsidence rates due to its unique geomorphology. The Bayou La Loutre 

Ridge is located in the Biloxi Marsh subarea; however, because it was determined that some 

scale of ridge needed to be included in the plan, these restoration features were evaluated in 

IWR-PLAN separately. 

The East Orleans/South Lake Borgne geographic area is composed of Subunits 36a - Pearl 

River Mouth – LA, 17 - East Orleans Landbridge, 05 - Bayou Sauvage, 40 - South Lake Borgne 

and 26 - Lake Borgne. Subunits 36a, 17, and 05 form the East Orleans Landbridge area. This 

area is recognized as a critical landscape feature with respect to storm surge damage risk 

reduction (USGS 1994, USACE 2009, Walmsley et al. 2009, Howes et al. 2010, Shepard et al. 

2011). Subunit 40 - South Lake Borgne covers the MRGO/Lake Borgne Landbridge, the strip of 

marsh separating the MRGO from the lake. The spatial integrity of the MRGO/Lake Borgne 

Landbridge was compromised by the construction of the channel. South Lake Borgne is 

considered a critical landscape feature to protect the form and function of the estuary, which is 

recognized as an institutionally significant resource by President Obama‘s administration. These 

subunits were grouped together because the areas are contiguous and create a structural 

framework for the estuary. This landscape feature is publically important because of its role in 

the potential reduction loss of life and property due to flooding and recreational value. There are 

numerous state, local, and NGO plans for restoration that demonstrate this significance (LPBF 

2006, Lopez 2006, Day et al. 2006, Lopez et al. 2010). Because these areas are important to 

the overall integrity of the estuary, IWR-PLAN was used to facilitate the development of the 

most cost-effective combination of measures for all components of the area. 

The Terre aux Boeufs/Hopedale geographic area is composed of Subunits 23 - Jean Louis 

Robin, and 21 - Hopedale. These subunits are south of the MRGO and have been primarily 

affected by the channel through the placement of spoil material and hydrologic changes. Bayou 

Terre aux Boeufs forms the boundary of Subunit 23, and is considered to be the southeast 

boundary of the hydrologic impacts of the channel. This area is technically significant because it 

contributes to the spatial integrity of the ecosystem (USGS 1994, USACE 2009, Walmsley et al. 

2009, Howes et al. 2010, Shepard et al. 2011). This area also supports imperiled oyster reef 

habitat (Beck et al. 2011). The significant legislation protecting estuarine and wetland resources, 

President Obama‘s and previous Presidential administration‘s commitments to this ecosystem 

demonstrate it is an institutionally important resource. The area‘s public importance is 

recognized by its inclusion in several Federal, state, and local restoration plans. 

The Central Wetlands (Subunit 13) is isolated from the rest of the study area by levees and 

floodgates, and was considered a separate geographic area for this reason. Additionally, the 

Central Wetlands presents a unique set of problems and opportunities because of its proximity 

to the Mississippi River and the containment provided by the levees. Similarly, Florissant 

(Subunit 19) is isolated from other portions of the study area, and was evaluated separately. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 2: Plan Formulation 

2-120 June 2012 

The restoration of the Central Wetlands is important to achieve the goals and objectives of this 

study because of the magnitude of the effects of the channel in this area and the significant 

resources it historically supported. The channel was excavated and spoil material was placed 

on the northeastern border of this subunit. Saltwater intrusion resulted in the mortality of the 

remaining cypress forest and fresh marsh in the area. Fresh marsh is ranked as imperiled by 

the Louisiana Natural Heritage Program because it has undergone the largest reduction in 

acreage of any of the marsh types in the state over the past 20 years due to saltwater intrusion, 

demonstrating its technical, institutional and public significance (LDWF 2011).

The following describes the steps that were taken to identify the most cost efficient plans. 

Step 1 –CE/ICA were run in IWR-PLAN for each of the following geographic areas: 

1. Biloxi Marsh (3 marsh areas; 10 shoreline segments) 

2. MRGO Channel (8 narrowing/shoreline features) 

3. East Orleans/South Lake Borgne (9 marsh areas; 4 shoreline segments; SAV 

measure) 

4. Terre aux Boeufs/Hopedale (5 marsh areas and 1 shoreline protection feature) 

Step 2 – The incremental cost box graphs (incremental cost per unit vs. output) for the above 

areas were evaluated and a subset of Best Buy plans for each geographic area were selected 

to run as scales in a combined IWR run. Scales were selected as follows: 

 Minimum scales – Selected Best Buy plans containing at least two or more measures. 

The Best Buy plan containing only one measure was not selected as a scale because it 

would not produce a complete, effective, or acceptable plan for a geographic area. 

 Intermediate scales – Selected one or more Best Buy plans based on cost effective 

increments, i.e. where high outputs could be gained for minimal additional cost. 

 Maximum scales – To develop the full cost effectiveness curve, always selected the 

largest Best Buy Plan, i.e. the plan that contained all measures in that group. 

Step 3 – Repeated the CE/ICA using scales of alternatives as described below: 

 Biloxi Marsh – 4 scales selected based on Steps 1 and 2. 

 MRGO Channel – 5 scales based on Steps 1 and 2; in addition, backfilling in the MRGO 

channel between Bayou Bienvenue and Bayou La Loutre was added as a scale for a 

total of 6 scales. MRGO 1-7 was included in the minimum planning increment. 

 East Orleans/South Lake Borgne – 5 scales based on Steps 1 and 2. 

 Terre aux Boeufs/Hopedale – 3 scales based on Steps 1 and 2. 

 Ridge – Partial ridge vs. full ridge – 2 scales. The partial ridge was included in the 

minimum planning increment. 
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Final Feasibility Report 2: Plan Formulation 

2-121 June 2012 

 Florissant – 1 scale. 

 Central Wetlands – Swamp only vs. swamp plus marsh – 2 scales. 

Figure 2-28. Sub-Area Best Buys
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Final Feasibility Report 2: Plan Formulation 

2-122 June 2012 

Figure 2-29. Geographic Subareas
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 2: Plan Formulation

2-123 June 2012 

All solutions were combinable. In Step 3 of the CE/ICA each plan was required to contain at 

least one scale of ridge, and one scale of Central Wetlands. 

As noted previously, one limitation of the WVA model is that all habitat types are considered to 

have equal value. In an abstract evaluation of cost per AAHU, the restoration measures 

proposed for the Central Wetlands and the Bayou La Loutre ridge were not as effective as many 

of the measures. However, the inclusion of some restoration measure in these areas, as well as 

the MRGO channel, is considered necessary to fulfill the requirements of the study authority. 

 The former navigation channel was cut through the Central Wetlands and the Bayou La 

Loutre ridge, directly impacting these areas. 

 The Central Wetlands is the only area in the immediate vicinity of the MRGO that could 

support cypress swamp habitat. 

 The Bayou La Loutre ridge is the only natural ridge in the immediate vicinity of the 

MRGO. 

 Cypress swamp and coastal ridge habitat are increasingly scarce and provide unique 

habitat and ecological functions. 

 The restoration of cypress swamp in the Central Wetlands is widely supported by the 

adjacent communities, NGOs, state and local government, and resource agencies. 

The inclusion of some scale of restoration in these areas was integral to development of the 

plan. This constraint was added to the IWR-PLAN formulation process to ensure production of a 

wide range of alternatives meeting the study objectives. 

IWR-PLAN Results 

IWR-PLAN software generated 6,721 plan combinations. Including the No Action plan, there 

were 285 cost-effective plans and 19 Best Buy plans ranging in costs up to $6.5 billion (October 

2009 Price Levels). A summary of the costs and benefits associated with the plans generated in 

IWR-PLAN is provided in Table 2-21. 

The Best Buy plans that were generated in IWR-PLAN addressed the study goals and 

objectives of the study in varying degrees. The plans included for further consideration should 

be selected from the Best Buy plans, as all of these plans maximize restoration benefits for the 

associated costs. These plans are summarized in Table 2-22. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 2: Plan Formulation 

2-124 June 2012 

Table 2-21. Best Buy Plans 

Plan# Output 

(HU) Annual Cost Average Cost($/HU)

Incremental 

Cost ($)

Incremental 

Output 

(AAHU)

Incremental 

Cost per 

Output

1 0.00 0.00

2 6,132 65,660,087 10,708 65,660,087 6,132 10,708

3 7,693 82,617,053 10,739 16,956,966 1,561 10,863

4 8,569 93,263,525 10,884 10,646,472 876 12,154

5 9,173 101,670,185 11,084 8,406,660 604 13,918

6 9,862 112,267,790 11,384 10,597,605 689 15,381

7 10,262 118,496,874 11,547 6,229,084 400 15,573

8 10,302 119,163,770 11,567 666,896 40 16,672

9 10,406 121,383,522 11,665 2,219,752 104 21,344

10 10,591 125,718,961 11,870 4,335,439 185 23,435

11 10,601 125,999,005 11,886 280,044 10 28,004

12 11,342 151,603,401 13,367 25,604,396 741 34,554

13 11,374 153,373,420 13,485 1,770,019 32 55,313

14 11,401 155,090,241 13,603 1,716,821 27 63,586

15 11,441 157,826,469 13,795 2,736,228 40 68,406

16 13,224 310,652,025 23,492 152,825,556 1,783 85,713

17 13,297 317,098,629 23,847 6,446,604 73 88,310

18 13,303 317,744,064 23,885 645,435 6 107,573

19 13,315 319,320,474 23,982 1,576,410 12 131,368

Note: Costs are October 2009 Price Levels 

Table 2-22. Best Buy Plan Descriptions

Best Buy Description

1 No action.

2 Central Wetlands: Cypress measures CC1-CC6 and Violet, Louisiana Freshwater Diversion

South Lake Borgne: LM1-3

East Orleans Landbridge: EM1 and 2

MRGO: MRGO 1-7

Biloxi Marsh: BR1

Bayou Terre aux Boeufs: TM1-2, JS1 (later determined to be infeasible due to water depths)

3 BB2 plus TM7, TM8, HM1

4 BB3 plus EM3 and 4, ES1 and 2

5 BB4 plus CM1-5

6 BB5 plus BM1, BS1, BS2

7 BB6 plus LM4, ES3, LS1

8 BB7 plus MRGO1-2 (later included in all action plans)

9 BB8 plus EM5, EV1

10 BB9 plus BS3

11 BB10 plus MRGO3-4 (later included in all action plans)

12 BB11 plus additional shoreline protection in Biloxi Marsh

13 BB12 plus MRGO5 (later included in all action plans)

14 BB13 plus MRGO6-7 (later included in all action plans)

15 BB14 plus MRGO8 (later included in Plans C and D)

16 BB15 plus backfilling MRGO to marsh elevation from Bayou Bienvenue to Bayou La Loutre

17 BB16 plus additional shoreline protection in the Biloxi Marsh

18 BB17 plus additional ridge restoration
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Table 2-22. Best Buy Plan Descriptions

Best Buy Description

19 BB18 plus Florissant

2.7.3 Selection of the Final Array of Alternatives 

In the cost effectiveness/incremental cost analysis described in the previous section, measures 

were combined into alternatives and evaluated based solely on costs and outputs. In order to 

select a final array of alternatives from the 19 Best Buy plans, the following additional 

considerations were synthesized into the decision making process: 

 Environmental Planning Guiding Principles 

 Significance of Outputs 

 Risk and Uncertainty 

 Four Planning Criteria (completeness, efficiency, effectiveness, acceptability,) 

The following sections describe how these principles and criteria were used to select plans to 

carry forward into the final array of alternatives for further analysis. 

Environmental Planning Guiding Principles 

All plans address the plan formulation guiding principles. The differences between the plans are 

a matter of scale. Consequently, the degree to which each plan follows the guiding principles is 

generally also a matter of scale. 

Principle 1 - Relatively intact estuarine ecosystems are a key attribute in coastal Louisiana, 

and alternatives should seek to enhance the resilience and self-sustainability of the estuarine 

environments, including protection of existing high-quality estuaries. 

Because all of the plans include the Violet, Louisiana Freshwater Diversion, all plans enhance 

the resilience and self-sustainability of the estuary. However, the plans vary in their ability to 

protect, maintain and restore the form of the ecosystem. Plans that do not provide extensive 

protection and restoration on the East Orleans Landbridge, Biloxi Marsh, and the MRGO/Lake 

Borgne Landbridge (Plans #2 to #5) may not contain all of the features needed to maintain and 

restore the form and function of the estuary, an institutionally significant resource recognized by 

the Estuary Protection Act. The need to protect existing high quality estuaries is better 

addressed by Plans #6 to #19, which include increasing scales of restoration and protection in 

these areas. Plans #16 to #19 include backfilling portions of the MRGO channel, and better 

address the need for an intact system and restoration to historic conditions. 

Principle 2 - Restoration of key processes and dynamics are critical to the long-term health of 

the ecosystem. 

The Violet, Louisiana Freshwater Diversion restores a key process of the estuary and is a 

component of every plan. However, the plans vary in the extent they restore biodiversity and 

promote accretion through sediment placement, vegetative planting, and shoreline protection. 
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2-126 June 2012 

Plans #2 to #11 provide incremental scales of marsh restoration and shoreline protection 

features that would promote accretion and restore biodiversity. Plans #12 to #15 do not increase 

marsh restoration, although additional shoreline protection features would help protect existing 

vegetation. Plans #16 to #19 incrementally increase the amount of marsh restored, with Plan 

#19 providing the greatest amount of restoration. 

Principle 3 - Measures and alternatives must seek to maximize the combined benefits of 

diversions that seek to restore natural processes with mechanical marsh creation measures. 

All plans seek to maximize the combined benefits of diversions. However, plans that include the 

most restoration features in the area benefitted by the diversion (Plans #7 to #19) better 

address the goal of combining the benefits of diversions with mechanical marsh creation 

measures. Plan #7 is the first plan to include all of the proposed marsh restoration features in 

the immediate influence area of the diversion (Central Wetlands, Golden Triangle, MRGO/Lake 

Borgne Landbridge, and areas adjacent to Lake Borgne and Mississippi Sound) with the 

exception of backfilling portions of the MRGO channel. Plans #16 to #19 would maximize the 

amount of marsh benefitted by the diversion by including these measures. 

Principle 4 - Additional sources of sediments should be sought where feasible; recognizing 

that such measures should not contribute to ecosystem degradation in the source area. 

All of the plans require significant amounts of sediments to restore and nourish sedimentdeprived marsh. Alternative sediment sources were considered and are discussed in Section 

2.5.3.2. The smaller plans better address this principle because the potential for environmental 

damage from obtaining and/or transporting borrow material is on a smaller scale than the larger 

plans. However, the potential adverse environmental impacts associated with obtaining and 

transporting borrow material must be considered in context with the long-term benefits 

associated with these actions. 

Principle 5 - Measures should be combined synergistically to maximize possible cumulative 

benefits. Thus, the position of features within the landscape has a direct influence on the 

potential benefits derived. 

Plans #2 to #5 work synergistically over the areas that they include, but do not include any 

features in the Biloxi Marsh. Therefore, they do not address restoration in a critical landscape 

feature necessary to maintain the form and function of the overall ecosystem. These plans do 

not capitalize on existing and planned foreshore protection measures. Plan #6 does not include 

measures ES3 and LM1, which are key pieces in a comprehensive shoreline protection plan for 

Lake Borgne. Plan #7 is a cohesive plan that reasonably maximizes cumulative benefits. Plans 

#8 to #19 continue to incrementally increase the potential for cumulative benefits; however, the 

incremental benefits associated with Plans #8 to #15 are minor. Plan #16, which is the first plan 

to include backfilling portions of the MRGO, maximizes the potential for synergistic benefits. 

Principle 6 - Flexibility is required in project design and implementation to permit adaptive 

management as conditions change and more is learned. 

All of the 19 Best Buy plans include plans for the Violet, Louisiana Freshwater Diversion, which 

offers the greatest opportunity for continued adaptive management. 
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2-127 June 2012 

Principle 7 - A concerted monitoring and adaptive management program should be a 

component of the restoration plan. 

All of the plans would include a concerted monitoring and adaptive management plan. 

Significance of Outputs 

All of the action plans would protect and restore significant resources. The institutional 

significance of these resources is demonstrated by the Coastal Barrier Resources Act of 1982; 

Coastal Zone Management Act of 1972; Emergency Wetlands Resources Act of 1986; Estuary 

Protection Act of 1968; Fish and Wildlife Conservation Act of 1980; the Fish and Wildlife 

Coordination Act of 1958, as amended; Migratory Bird Conservation Act; Migratory Bird Treaty 

Act (MBTA); Endangered Species Act of 1973; Magnuson-Stevens Fishery Conservation and 

Management Act of 1976, as amended; Bald and Golden Eagle Protection Act of 1940; NEPA 

of 1969; the North American Wetlands Conservation Act; the Water Resources Development 

Acts of 1976, 1986, 1990, 1992, and 2007; Clean Water Act; EO 11990 Protection of Wetlands; 

and EO 13186 Migratory Bird Habitat Protection. The Obama administration‘s commitment to 

the restoration of the study area, as evidenced by the creation of the Louisiana-Mississippi Gulf 

Coast Ecosystem Restoration Working Group, and the area‘s designation as an ecosystem of 

national importance in Clean Water: A Foundation of Healthy Communities and a Healthy 

Environment further exemplifies the institutional significance of the ecosystem (EPA et al. 2011). 

The resources of the area are also technically significant because of the uniqueness of the 

ecosystem, scarcity of the habitats that comprise the system, species richness and biodiversity 

produced by the system, and the area‘s importance to species of concern. Louisiana is losing 

land at an alarming rate between 20 and 50 square miles a year (USGS 1995, USGS 2011). 

Approximately 1,900 square miles of coastal habitat was lost between 1932 and 2010 (USGS 

2011). The vegetative communities that would be restored by any of the action plans provide 

protection against substrate erosion and contribute food and structure for cover, nesting, and 

nursery habitat for wildlife and fish. Continued degradation and loss of existing areas, along with 

truncation of replenishing processes, will accelerate decline in the interdependent processes of 

plant production and vertical maintenance necessary for a stable ecosystem. 

Coastal habitats are publicly significant because of the high priority that the public places on 

their aesthetic, ecological, recreational, and cultural value. The involvement of national, state, 

and local NGOs in restoration efforts demonstrates the public significance of these resources. 

The National Audubon Society, the Nature Conservancy, National Wildlife Federation and 

Ducks Unlimited are examples of national organizations actively involved in area restoration. 

Several regional and local NGOs are concerned with the restoration of the study area, including: 

the America's Wetland Foundation, Louisiana Environmental Action Network and Parishes 

Against Coastal Erosion. The MRGO Must Go Coalition was founded in 2006 ―to ensure that the 

wetlands affected by the MRGO are carefully restored in a timely manner‖ (MRGO Must Go 

2011). The Coalition includes 17 local and national environmental, social justice, and community 

organizations including: American Rivers, Citizens Against the Widening of the Industrial Canal, 

Coalition to Restore Coastal Louisiana, Environmental Defense Fund, Global Green, Gulf 

Restoration Network, Holy Cross Neighborhood Association, Lake Pontchartrain Basin 
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2-128 June 2012 

Foundation, Levees.org, Louisiana Environmental Action Network, Louisiana Wildlife 

Federation, Lower Mississippi Riverkeeper, Lower Ninth Ward Center for Sustainable 

Engagement and Development, MQVN Community Development Corporation, National 

Audubon Society, National Wildlife Federation, and the Sierra Club - Delta Chapter. 

The entire ecosystem has global, national, state, and local significance, and every part 

contributes to the unique services and functions of the whole. However, some components of 

the ecosystem have particular significance with respect to scarcity, biodiversity, connectivity, 

ecosystem structure, recreation, and culture that demonstrates their distinct technical, 

institutional and public significance. The Best Buy plans were evaluated for the extent to which 

they contributed to the restoration and conservation of these significant resources to determine 

which plans should be considered in further detail. 

Table 2-23. Best Buy Plan Significance

Best 

Buy

Description Contribution to Significant Resources

1 No action. None

2 Central Wetlands: Cypress measures CC1-

CC6 and Violet, Louisiana Freshwater 

Diversion

South Lake Borgne: LM1-3

East Orleans Landbridge: EM1 and 2

MRGO: MRGO 1-7

Biloxi Marsh: BR1

Bayou Terre aux Boeufs: TM1-2,

Restoration of a key natural process by the Violet, 

Louisiana Freshwater Diversion.

Restoration of scarce cypress swamp habitat.

Some restoration in South Lake Borgne and 

MRGO, significant for ecosystem structure.

Some restoration of the East Orleans Landbridge 

critical landscape feature.

Restoration of rare coastal ridge habitat.

3 BB2 plus TM7, TM8, HM1 Additional restoration of brackish habitat adjacent to 

communities outside the HSDRRS.

4 BB3 plus EM3 and 4, ES1 and 2 Additional restoration on the East Orleans 

Landbridge critical landscape feature.

5 BB4 plus CM1-5 Restoration of scarce fresh marsh.

6 BB5 plus BM1, BS1, BS2 Biloxi Marsh critical landscape feature restoration.

Restoration of globally imperiled oyster habitat.

7 BB6 plus LM4, ES3, LS1, MRGO8 Restoration of a publically significant urban area.

ES3 and LS1 complete the protection of the Lake 

Borgne Shoreline.

Additional protection of the East Orleans Landbridge 

critical landscape feature.

Additional South Lake Borgne protection, which is 

significant to the maintenance of estuary structure.

9* BB8 plus EM5, EV1 Additional marsh restoration in the East Orleans 

Landbridge critical landscape feature.

10 BB9 plus BS3 Additional protection of the Biloxi Marsh critical 

landscape feature.

12* BB11 plus additional shoreline protection in 

Biloxi Marsh (014, 111, 98a, 107, 110, 017, 

98b)

Additional protection of the Biloxi Marsh critical 

landscape feature.

16* BB15 plus backfilling MRGO to marsh elevation 

from Bayou Bienvenue to Bayou La Loutre

Addition of a publicly significant feature addressing 

the direct impacts of the channel.
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Final Feasibility Report 2: Plan Formulation 

2-129 June 2012 

Table 2-23. Best Buy Plan Significance

Best 

Buy

Description Contribution to Significant Resources

17 BB16 plus additional shoreline protection in the 

Biloxi Marsh (020, 042)

Additional protection of the Biloxi Marsh critical 

landscape feature.

18 BB17 plus additional ridge restoration (133b) Additional restoration of rare coastal ridge habitat.

19 BB18 plus Florissant (191) Additional brackish marsh restoration.

*BB 8, 11, 13, 14, and 15 added MRGO features that are part of the minimum planning increment.

Risk and Uncertainty 

In general, the larger the plan, the higher the uncertainty of producing expected outputs. Plans 

increase in size from Plan #1 (no action) to Plan #19 (largest plan). Conversely, the smaller the 

plan, the higher the residual risks in terms of ecosystem degradation and potential resulting 

storm surge increases in the future. 

As described in Risk and Uncertainty Associated with Restoration Measure Types section, risk 

and uncertainty vary by measure type. Except for the No Action alternative, all Best Buy plans 

include a freshwater diversion, forested swamp restoration, and forested ridge restoration, so 

the risks and uncertainties associated with those features are the same for all plans. Risks and 

uncertainties associated with individual plans vary based on the amount and location of marsh 

restoration/nourishment and shoreline protection, which is discussed in the following section 

along with the application of the four planning criteria.

Rationale for Selection of the Final Array 

In addition to the No Action Plan (Plan #1), three action plans (Plans #2, #7, and #10) were 

selected for the final array of alternatives. 

Plan #2 was selected for further consideration for the following reasons: 

 Plan #2 is the least costly Best Buy Plan. 

 Plan #2 has the least amount of marsh restoration and nourishment and therefore has 

the least uncertainty associated with obtaining sufficient quantities of borrow material. 

 Plan #2 contains the least amount of rock protection. Hard structures, such as rock 

protection, are less acceptable to some stakeholders than natural features. Shoreline 

protection measures are not self-sustaining and have risk of failure under the higher 

relative sea level rise scenarios. 

Plan #2 does not achieve all of the goals of the study, but it includes some restoration measures 

for all of the targeted habitat types. Plan #2 would restore or protect 9,518 acres of fresh and 

intermediate marsh, 10,253 acres of brackish marsh, and 10,431 acres of cypress swamp. Plan 

#2 does not meet the target acre objectives for brackish marsh. Plan #2 has no features in the 

Biloxi Marsh and includes only one feature on the East Orleans Landbridge; therefore, Plan #2 

does not fully address the objective to restore and protect critical landscape features and 

significant residual risks associated with not restoring critical landscape features. 
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Plan #7 was selected for further consideration for the following reasons: 

 Plan #7 is the least costly Best Buy Plan that meets all of the objectives, including 

reasonably maximizing restoration and protection of the Biloxi Marsh and East Orleans 

Landbridge. 

 Plan #7 is the least costly Best Buy plan to include Feature LS1, which is a key Lake 

Borgne restoration component. Feature LS1 would work synergistically with the Bayou 

Dupre and West of Shell Beach shoreline protection features currently under 

construction, and Feature LM2 to restore and protect the Proctor Point area. 

 Plan #7 is a complete plan for the Lake Borgne ecosystem and the areas affected by the 

MRGO. For example, Plan #7 addresses the gaps left by existing and authorized 

restoration projects. Plan #7 includes the necessary shoreline protection and marsh 

restoration features to form a complete plan for the ecosystem. 

Plan #10 was selected for further consideration for the following reasons: 

 Plan #10 improves upon Plan #7 by further protecting critical landscape features, and 

better meets the storm surge objectives. It contains additional shoreline protection in the 

Biloxi Marsh and additional marsh restoration in the East Orleans Landbridge both of 

which are critical landscape features. 

 Plan #10 is the least costly Best Buy plan to include a Submerged Aquatic Vegetation 

(SAV) project. SAV restoration measures are presented as pilot projects because of 

uncertainties surrounding the re-establishment of SAV beds. 

The remainder of the Best Buy plans were not selected because they were either not significantly 

different from one of the selected plans or the benefits did not justify the significant additional costs. 

Plans #3 to #6 were not selected because all of the measures in Plans #3 to #6 are contained in #7, 

which was selected for the final array. Plans #3 to #5 do not contain features BM1, BS1, and BS2, 

and therefore do not meet the objective to restore and protect the Biloxi Marsh. The institutional, 

technical, and public significance of the Biloxi Marsh is demonstrated by the recognition that this 

landscape feature reduces risk associated with storm surge (USGS 1994, Burkett et al. 2002, 

USACE 2009, Walmsley et al. 2009, Howes et al. 2010, Shepard et al. 2011). The Biloxi Marsh was 

directly affected by the MRGO channel, and restoration in this area would contribute to the 

satisfaction of section a(3)B(i) of the study authority to ―restore areas affected by the navigation 

channel‖. Maintaining the Biloxi Marsh contributes to the structural integrity of the system by 

separating Lake Borgne from the higher salinity waters of Chandeleur Sound. If this barrier were 

removed, the resulting saltwater intrusion would destroy one of the most productive estuaries in the 

nation. Restoration in this area is consistent with LACPR and the 2007 State Master Plan, 

demonstrating the public significance of restoration in this area. 

Feature BS1 is a critical component for the comprehensive protection of the Lake Borgne shoreline. 

This area has the highest erosion rates in Lake Borgne and is the only remaining piece of the 

southeast shore of Lake Borgne that is not protected by existing or planned projects. Feature BM1 

would provide marsh nourishment along the Lake Borgne shoreline, contributing to the maintenance 
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Final Feasibility Report 2: Plan Formulation 

2-131 June 2012 

of the boundary between Lake Borgne and Chandeleur Sound. The only oyster reef restoration 

feature proposed as a plan component is BS2. Feature BS2 is an important component of the plan 

because it restores globally and nationally rare oyster habitat that were affected by the saltwater 

intrusion from the channel (Beck et al. 2011). The feature prevents erosion of Biloxi Marsh, 

contributing to the structural integrity of the system and multiple lines of defense through protection of 

a critical landscape feature. Additionally, the institutional, technical, and public significance of this 

feature is further demonstrated by the inclusion of an adjacent oyster restoration project in the 

Deepwater Horizon Oil Spill Draft Phase I Early Restoration Plan and Environmental Assessment 

(Deepwater Horizon Natural Resource Trustees 2012). Additionally, a considerable number of 

comments were received on the Draft MRGO Ecosystem Restoration Plan suggesting that the plan 

should contain more oyster reef restoration, demonstrating public significance. All of these features 

are consistent with the environmental planning guiding principles adopted for this study by 

maximizing benefits and sustainability through synergy with existing and planned adjacent projects. 

Because the protection of this critical landscape feature would require actions by others, these 

features contribute to the completeness of alternative plans. 

Plan #6 includes restoration features in the Biloxi Marsh and more features that protect the East 

Orleans Landbridge; however, Plan #6 does not include LM4, ES3, and LS1. LM4 would provide 

restoration in the area forming the boundary between the portion of the MRGO/GIWW channel still 

authorized and the de-authorized portion of the channel. This feature would provide a buffer in front 

of the NASA Michoud Facility and its levees, as well as restoration adjacent to HSDRRS, contributing 

to multiple lines of defense. Ecologically, the marsh is located immediately across the GIWW from 

the hot-water canal a winter refuge for numerous estuarine fish species. Publicly, this marsh is 

significant as it provides a short-run recreational fishing spot for boat launches in Chalmette and New 

Orleans. The institutional significance of this feature is demonstrated by the commitment of President 

Obama‘s administration to the restoration of urban water resources (EPA et al. 2011). Restoration in 

this area is consistent with LCA, LACPR, and the 2007 State Master Plan, further demonstrating 

public significance of this restoration project. 

 ES3 and LS1 complete the protection of the Lake Borgne shoreline. Feature ES3 provides 

additional protection of the East Orleans Landbridge, which is institutionally, technically, and 

publically significant because this landscape feature reduces risk associated with storm surge 

(USGS 1994, Burkett et al. 2002, USACE 2009, Walmsley et al. 2009, Howes et al. 2010, 

Shepard et al. 2011). Feature LS1 provides protection for South Lake Borgne, which is 

significant to the maintenance of estuary structure by preventing the further confluence of the 

MRGO and Lake Borgne. The spatial integrity of the MRGO/Lake Borgne Landbridge was 

compromised by the construction of the channel, and restoration in this area would contribute to 

the satisfaction of section a(3)B(i) of the study authority to ―restore areas affected by the 

navigation channel‖. South Lake Borgne is considered a critical geomorphic feature to protect 

the form and function of the estuary, which is recognized as an institutionally significant 

resource by President Obama‘s administration (EPA et al. 2011). 

Plans #8 and #9 were not selected because all of the measures contained in Plans #8 and #9 

are also contained in Plan #10, which was selected for the final array. Plan #8 includes more 
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Final Feasibility Report 2: Plan Formulation 

2-132 June 2012 

shoreline protection features in the MRGO. Plan #9 includes the additional features in Plan #8 

as well as additional features in the East Orleans Landbridge. 

Plans #11 to #19 were not selected because although they would provide additional benefits, 

they are the most expensive plans providing diminishing returns at increasing financial risk and 

uncertainty. Plan #11 adds additional protection features along the MRGO/Lake Borgne 

Landbridge. The incremental cost difference between Plans #10 and #11 is relatively small. 

However the incremental cost per unit of output is relatively low. 

Plan #12 includes the features in Plan #11 and increases the amount of shoreline protection 

and marsh restoration in the Biloxi Marsh at a relatively low incremental cost. However, it was 

determined that Plan #10 met the storm surge objective, and that Plan #12 would not be carried 

forward, although it may better meet this objective. Potential risks and uncertainties regarding 

extensive foreshore protection in the Biloxi Marsh were raised by some Federal partner 

agencies, and were an additional consideration in the decision to not carry this alternative 

forward. 

The incremental costs associated with Plans #13 to #15 were not considered reasonable for the 

relatively minor amount of associated costs. Plans #16 to #19 provide a substantial increase in 

benefits (by filling in large portions of the MRGO channel), but the total estimated construction 

costs are considered too great for the associated ecosystem outputs. 

The incremental costs associated with Plans #13 to #15 were not considered reasonable for the 

relatively minor amount of associated benefits. Plans #16 to #19 provide a substantial increase 

in benefits (by filling in large portions of the MRGO channel), but the total estimated construction 

costs are considered too great for the associated ecosystem outputs. 

As illustrated in the IWR output graph, the final array selection is supported by the position of 

the plans on the efficient frontier. Best Buy 2 was selected because it was the least expensive 

action plan. The plans between Best Buy 2 and Best Buy 7 continue to increase benefits at 

relatively minor increases in incremental costs (illustrated by the gentle slope between the two 

points). Best Buy 7 appears on the efficient frontier at the point where the incremental cost of 

benefits becomes more significant (illustrated by the steep slope between the point for Best Buy 

7 and the other plans). 
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Final Feasibility Report 2: Plan Formulation 

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Figure 2-30. Incremental Costs and Outputs 

Measures Not Included in the Final Array 

The following measures were not included in the final array because they are the least cost 

effective and/or they have high risk and uncertainty: 

 Marsh restoration and shoreline protection on the Breton Sound side of Biloxi marshes 

north of Morgan Harbor – These measures would be exposed to high wave action and 

would not perform well under higher levels of sea level rise. 

 Backfilling in the MRGO channel - These plans have the highest uncertainty associated 

with obtaining sufficient quantities of borrow material. 

 Large ridge restoration measure - Lack of technical knowledge is a risk associated with 

ridge restoration features. Very few coastal ridge restoration projects have been 

constructed, and there is limited data to contribute to the successful design and 

implementation of these features. The lack of knowledge could jeopardize project 

success, and the consequences of failure could result in a significant or total loss of 

benefits. By including the smaller ridge restoration measure in the final array, these risks 

are reduced without eliminating all of the benefits of this unique habitat type. 

 Florissant marsh restoration – This measure is not cost effective and would contribute 

little to the overall plan. 
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2-134 June 2012 

Sensitivity Analyses 

Sensitivity analyses were conducted to evaluate how the results would have been different if all 

of the Best Buys for each subarea were included in the Combined Run instead of a subset. 

Based on incremental cost vs. output, as well as the unique benefits of the the plans in the final 

array, the same plans would have been selected from among the more complete set of Best 

Buy Plans generated though the sensitivity analysis. 

Additional sensitivity analyses were conducted to evaluate how the results would have been different 

if IWR-PLAN was ran by habitat type rather than by subarea. The results of this sensitivity analysis 

confirm the selection of the final array, even if the CE/ICA analysis had been conducted differently. 

2.7.4 Final Array of Alternatives 

Three action plans are included in the final array of alternatives. Best Buy plans #2, #7, and #10 

(Plans B, C, and D, respectively) were chosen based on the analysis described in the previous 

section. WVAs were conducted for all of the plans in the final array considering the interaction 

between plan elements, the authorized Violet, Louisiana Freshwater Diversion, and projects in 

the FWOP. 

These three plans provide a wide range of costs and outputs (see Table 2-24). 

Table 2-24. Final Array of Alternatives 

Plan

Estimated

Construction Cost1

Measure 

AAHUs2

Plan

AAHUs3

Acres 

Restored4

A $0 0 0 0

5

B $1.7 B ($67 M annual) 6,008 13,608 30,250

C $2.9 B ($124 M annual) 10,324 17,575658,861

D $3.1 B ($130 M annual) 10,399 17,116 59,823

Notes: 

1. Based on preliminary costs in October 2009 Price Levels. Does not include real estate, OMRR&R, or adaptive 

management costs. 

2. The AAHUs presented in this column are the total AAHUs of all measures in the plan added together and does 

not consider interactions between restoration features, except for areas influenced by the freshwater diversion. 3. 

The AAHUs in this column are based on the Wetland Value Assessments (WVAs) for the entire plan, and does 

consider synergies. All benefits in this table consider the effects of the authorized Violet, Louisiana Freshwater 

Diversion. 

4. The acres in this column are the total acres restored, nourished, and protected by the plan. 

5. The table shows only the costs and benefits associated with this plan. Therefore, all values are zero for the 

no-action plan. 

6. This number is reflective of the initial WVAs that were performed for the project in the plan formulation phase. 

WVAs were revised for the FIP based on a revised WVA methodology. In this final plan analysis, the Violet, 

Louisiana Freshwater Diversion was assumed operational in 2027. The total AAHUs for Plan C considering 

synergies is now 37,980 because the revised methodology considers the value of existing habitat , significantly 

increasing total benefits . 

The historic rate of sea level rise was selected for primary display of ecological benefits in this table because this 

rate is supported by data. 
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2-135 June 2012 

No Action 

The No-Action Alternative is required by the National Environmental Policy Act of 1969 and 

represents the future without project condition to which alternatives considered in detail are 

compared. The No-Action Alternative assumes there will be no ecosystem restoration measures 

constructed within the study area beyond existing and presently authorized projects. 

The study area would continue to be subjected to natural and human land-loss factors such as 

tropical storms, subsidence, erosion, sea level rise, oil and gas exploration, and saltwater 

intrusion. Wetland loss would continue at the same or accelerated rates. Critical landscape 

features would continue to erode and degrade, potentially increasing storm surge damages. 

Large uncertainties surround land loss rates including climate change; sea level rise rates; 

subsidence rates; changes in frequency and intensity of tropical storm events; and/or changes 

in drought conditions. All of these factors could contribute to the acceleration of degradation. 

Continued wetland fragmentation and the eventual conversion to shallow open water habitat 

would have negative consequences on a variety of important resources. 

Summary of Recreation Features 

The Recreation Development Plan recommends recreational features for the MRGO Ecosystem 

Restoration project in concurrence with facilities that are approved in ER 1105-2-100 for ecosystem 

restoration projects. When implementation funds are appropriated, a non-Federal sponsor, yet to be 

identified, would participate in a cost-sharing agreement for construction of the recreation plan. 

Accordingly, the non-Federal share will be 50 percent of the recreation development costs. NonFederal sponsors are responsible for 100 percent of lands, easements, rights-of-way, utility or public 

facility relocations, and dredged or excavated material disposal areas (LERRD), and operation, 

maintenance, repair, rehabilitation, and replacement (OMRR&R). The value of LERRD is credited to 

the 50 percent share. For a more detailed discussion of the recreation features, drawings, and 

benefit-cost ratios presented below, see Appendix W. 

The recommended recreational features are ancillary to the ecosystem restoration project, work 

harmoniously with the measures of the restoration project and are proposed on fee title lands for 

cost-sharing. Recreation features recommended were first identified through USACE meetings with 

community groups and non-governmental organizations (NGOs). Additionally, this report refers to the 

Louisiana Department of Culture, Recreation and Tourism‘s Statewide Outdoor Recreation Plan 

(SCORP), which presents findings from focus group meetings regarding locally preferred outdoor 

recreation activities. A third source, University of Wisconsin (UW), prepared a recreation needs report 

for St. Bernard and part of Orleans Parishes. All three of these resources are used in identifying the 

recommended recreation features, including development of the benefits of each recreation 

development. Both sites offer American Disability Act (ADA) accessible features, including parking, 

bathrooms, access to boardwalks, ramps, and picnic shelters. 
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Lower Ninth Ward Bienvenue Triangle Recreation Feature 

Existing Condition – The site of the proposed recreation feature is located in Orleans Parish‘s 

Bienvenue Triangle. Located at the terminus of Caffin Avenue, the site currently offers a viewing 

platform overlooking the marsh. The platform is used by the neighborhood, tourists and schools both 

recreationally and as an educational tool. Martin Luther King Elementary School located on Caffin 

Avenue and North Claiborne Avenue currently uses the platform for teaching about environmental 

principles, processes and general education concerning marshland, habitat, and wildlife.

Proposed Improvement – The entrance of the proposed recreation development would offer 

interpretive signage detailing the history of the Bienvenue Triangle, its various functions to the 

community, the wetlands‘ restoration mission, the project development process, educational 

programming, and sustainable design elements. Opportunities for increasing the recreational and 

environmental education experience include development of a nature boardwalk through the marsh 

with interpretive signs describing viewsheds, plants, processes, and wildlife within the area. The 

features would be constructed before wetland restoration begins to afford viewing opportunities of the 

restoration process. Also, the local sponsor could develop wetland research pilot sites that schools 

could use to develop test sites of certain types of marsh grasses and other research projects. 

Information from a UW report revealed the need at this site for children‘s programs; such as some 

discussion about plants and animals living in the bayou and wetland preservation efforts. Signage 

explaining the proposed project would educate children about wetland restoration and ways to 

counter man-made and natural environmental degradation. A multi-use, nature boardwalk would 

provide access to the restored wetland while a bird watching boardwalk would provide access for 

viewing wildlife in a very secluded structure. An enlarged land-based viewing platform and 

shelter/classroom in the swamp would also provide space for larger groups visiting the site. 

Constraints to development include the Alabama Great Southern Railroad and local sponsor real 

estate acquisition. Discussion regarding crossing the railroad must be finalized. Currently, the railroad 

is crossed to gain access to the existing platform. An at-grade, ADA compliant crossing is proposed, 

such as is available at other crossings to recreational features in the city of New Orleans. Finally, the 

local sponsor must obtain real estate fee title for recreation development lands. The land between 

Florida Avenue and the railroad track is owned by the Sewerage and Water Board (City of New 

Orleans), the railroad is owned by Alabama Great Southern Railroad (aka Southern Norfolk), the 

levee is owned by the New Orleans Levee Board, and the swamp by less than five owners. 
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The recommended design selection is based upon maximizing net benefits. Two designs, Option A 

and B, are based upon input from community groups in the Lower 9th ward. Both Option A and B are 

evaluated in terms of benefits and costs and the resulting ratio is the basis for selection. Option A 

maximizes net benefits, has a BCR, 1.05, and is recommended for implementation. It consists of a 

100 lf (linear feet) of platform, 995 lf of boardwalk into the swamp, 4 picnic shelters, interpretive 

signage, bathrooms, parking, solar lighting and vegetative plantings. 

 

Figure 2-31. Lower Ninth Ward Bienvenue Triangle Recreation Feature 

Shell Beach Recreation Feature 

Currently, the shoreline of Shell Beach, located in St. Bernard Parish at the end of Yscloskey Road 

where it meets the MRGO, is often used by fisherman. Fishermen are confronted with a rocky, 

jagged shoreline and snakes in the area. The shoreline is used extensively on the weekends by 

many in the area. Additionally, a memorial is located at this location which lists the names of those 

who lost their lives as a result of Hurricane Katrina. The recreational plan will attempt to incorporate 

the memorial in a way that is both respectful and functional. 
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Opportunities for recreational development feature include a boardwalk into the MRGO for fishing 

and wildlife viewing and to gain access to other spots along the shore including picnic tables and 

shelters. Two designs, Option A and B, are based upon input from the Coastal Zone Administration 

of St. Bernard Parish. Both Option A and B are evaluated in terms of benefits and costs. Shell Beach 

Option B maximizes net benefits, has a BCR of 1.80 and is recommended as part of the plan. 

The recommended plan for Shell Beach consists of a 343 lf of boardwalk into the MRGO, 805 lf of 

shoreline boardwalk to 5 picnic shelters (2 handicap accessible), interpretive signage, bathrooms, 

parking, solar lighting and vegetative plantings. Option B is the recommended plan for Shell Beach. 

Figure 2-32. Shell Beach Recreation Feature 
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Final Feasibility Report 2: Plan Formulation 

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Figure 2-33. Recreation Features Overview 

Summary of Features Included in the Final Array 

The following table provides a brief description of each feature and indicates which plans in the 

final array include these features. 
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Final Feasibility Report 2: Plan Formulation 

2-140 June 2012 

Table 2-25 Restoration Features Included in the Final Array

Area Measure Description Plan 

B

Plan 

C

Plan 

D

Biloxi Marsh

BM1 8,000 acres of marsh nourishment along the south shore of Lake 

Borgne. 11 million cubic yards of material would be obtained from 

South Lake Borgne Borrow Cycle 6.

Y Y

BS1 Approximately 50,637 linear feet (9.5 miles) of shoreline protection 

along the southeast shore of Lake Borgne. This feature begins at 

the northern terminus of the Biloxi Marsh Shoreline Protection 

Project (PO-72) south of Point aux Marchettes and extends north 

to Malheureax Point.

Y Y

BS2 Approximately 30,750 linear feet (5.8 miles) of artificial oyster reef 

development on the Chandeleur Sound side of the Biloxi Marsh 

between Eloi Point and the mouth of Bayou La Loutre.

Y Y

BS3 67,623 linear feet (12.8 miles) of shoreline protection extending

from the south shore of Treasure Bay, around Point Paulina and 

Point Lydia to the north side of the mouth of Bayou La Loutre.

Y

BR1 Approximately 54.1 acres of ridge restoration on the south bank of 

Bayou La Loutre. 400,000 cubic yards of silty sand material to be 

obtained from the Mississippi River between river miles 83R and 

85R.

Y Y Y

MRGO

MRGO1 3,850 feet (0.75 miles) of new foreshore protection between 

MRGO miles 56.6 and 57.4. This stone protection feature is 

embedded within the limits of MRGO7.

Y Y Y

MRGO2 Repair and maintenance of approximately 21,630 linear feet (4.1 

miles) of foreshore protection between Mile 44.5 and 40 of the 

MRGO.

Y Y Y

MRGO3 Repair and maintenance of existing approximately 26,650 linear 

feet (5 miles) of foreshore protection between approximately Mile 

56 to 51 of the MRGO.

Y Y Y

MRGO4 Repair and maintenance of approximately 11,770 linear feet (2.2 

miles) of existing retention dike MRGO Miles 36.6 to 37.1 and 

MRGO Miles 33.9 to 32.9.

Y Y Y

MRGO5 202 acres of marsh would be restored behind 13,685 linear feet of 

vinyl sheet pile wall to establish the shoreline. 3 million cubic yards 

of material would be obtained from South Lake Borgne Borrow 

Cycle 4.

Y Y Y

MRGO6 8,132 linear feet (1.5 miles) of new, non-continuous foreshore 

protection between MRGO miles 36.0 and 34.4, immediately east 

of the existing stone closure of the MRGO. MRGO6 ties into an 

existing foreshore dike immediately downstream.

Y Y Y

MRGO7 110 acres of marsh restoration adjacent to approximately 9,170 

linear feet of bankline reclamation, consisting of 9,700 linear feet of 

vinyl sheet pile wall. 1.65 million cubic yards of material would be 

obtained from North Lake Borgne borrow cycle 5.

Y Y Y
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MRGO

MRGO8 236 acres of marsh restoration adjacent to approximately 17,785 

linear feet of bank reclamation constructed using vinyl sheet pile 

wall. 3.5 million cubic yards of material would be obtained from 

South Lake Borgne Cycle 4.. Approximately 14,225 linear feet (2.6 

miles) of new foreshore protection would also be included between 

approximate channel miles 51.0 and 48.3.

Y Y

SHELL 

BEACH

Recreation Feature - 343 lf of boardwalk into the MRGO, 805 lf of 

shoreline boardwalk to 5 picnic shelters (two handicap accessible), 

interpretive signage, bathrooms, parking, solar lighting and 

vegetative plantings.

Y Y Y

Central Wetlands

CC1 1,020 acres of cypress swamp restoration and 935 acres of 

cypress swamp nourishment in the area north of the existing Violet 

Canal along the Forty Arpent levee. 6 million cubic yards of borrow 

material to be obtained from North Lake Borgne Borrow Cycle 9.

Y Y Y

CC2 250 acres of cypress swamp restoration and 250 acres of swamp 

nourishment to the northeast of CC1. 1.7 million cubic yards of 

borrow material to be obtained from North Lake Borgne Borrow 

Cycle 9.

Y Y Y

CC3 370 acres of cypress swamp restoration and 790 acres of swamp 

nourishment along the Forty Arpent Levee south of Paris Road. 

Approximately 3.7 million cubic yards of material to be obtained 

from North Lake Borgne Borrow Cycle 9.

Y Y Y

CC4-A 400 acres of cypress restoration in the Bienvenue Triangle. 

Approximately 2.6 million cubic yards of silty sand material to be 

obtained from the Mississippi River between river miles 84.45R 

and 83R.

Y Y Y

Central Wetlands

CC4-B 1,065 acres of cypress swamp restoration in the open water areas 

adjacent to the Forty Arpent Levee north of Paris Road. 7.8 million 

cubic yards of borrow material to be obtained from North Lake 

Borgne Borrow Cycle 9.

Y Y Y

CC5 1,120 acres of swamp restoration and 1,550 acres of swamp 

nourishment south of the Violet Canal along the Forty Arpent 

Levee and the Chalmette Loop Levee. 7.8 million cubic yards of 

borrow material to be obtained from North Lake Borgne Borrow 

Cycle 10.

Y Y Y

CC6 2,568 acres of swamp nourishment in the southwest corner of the 

Central Wetlands. 5.2 million cubic yards of borrow material would 

be obtained from North Lake Borgne Borrow Cycle 10.

Y Y Y

CM1 1,240 acres of marsh nourishment south of Paris Road between 

cypress restoration feature CC3 and the Chalmette Loop Levee. 

Approximately 1.5 million cubic yards of material would be obtained 

from GIWW/MRGO Reach 1 starting at mile 66, as well as the 

turning basin at mile 65.5 and the Michoud Canal project that ties 

into MRGO/GIWW at mile 60.

Y Y

CM2 795 acres of marsh restoration and 190 acres of marsh 

nourishment north of Paris Road. Approximately 4.72 million cubic 

yards of material would be obtained from North Lake Borgne 

Borrow Cycle 2.

Y Y

CM3 300 acres of marsh restoration and 215 acres of marsh 

nourishment in the area north of Bayou Dupre and south of MRGO. Y Y
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1.6 million cubic yards of borrow material would be obtained from 

North Lake Borgne Borrow Cycle 7.

CM4 97.5 acres of marsh restoration and 128.5 acres of marsh

nourishment south of Bayou Dupre. 600,000 cubic yards of 

dredged material would be obtained from North Lake Borgne 

Borrow Cycle 7.

Y Y

CM5 245 acres of marsh restoration and 70 acres of marsh nourishment 

in the area north of Bayou Bienvenue and Paris Road. 1million 

cubic yards of material would be obtained from GIWW/MRGO 

Reach 1 starting at mile 66, as well as the turning basin at mile 

65.5 and the Michoud Canal project that ties into MRGO/GIWW at 

mile 60.

Y Y

BAYOU 

REC 

Recreation Feature 100 linear feet of platform, 995 linear feet of 

boardwalk into the swamp, 4 picnic shelters, interpretive signage, 

bathrooms, parking, solar lighting and vegetative plantings in the 

Bienvenue Triangle. 

Y Y Y

East Orleans

EM1 1,175 acres of marsh restoration and nourishment of 2,830 acres 

of surrounding marsh in the area bounded by the Lake 

Pontchartrain shoreline, Chef Menteur Pass, and the levee. 

Approximately 8.1 million cubic yards of material would be obtained 

from North Lake Borgne Borrow Cycle 5.

Y Y Y

EM2 1,095 acres of marsh nourishment on Hog Island, located between 

the west and east mouth of the West Pearl River. Approximately 

1.3 million cubic yards of dredged material would be obtained from 

Northeast Lake Borgne Borrow Cycle 8.

Y Y Y

EM3 861 acres of marsh restoration and 180 acres of adjacent marsh 

nourishment bounded by Highway 433, Little Lagoon, Salt Bayou 

and Highway 90. 4.1 million cubic yards of dredged material would 

be obtained from Northeast Lake Borgne Borrow Cycle 8.

Y Y

EM4 2,625 acres of marsh restoration and 1,455 acres of adjacent 

marsh nourishment in the area bounded by Salt Bayou to the 

north, the West Pearl River to the east, the Rigolets to the south 

and Highway 80 to the north. 9.2 million cubic yards of material 

would be obtained from North east Lake Borgne Borrow Cycle 8.

Y Y

EM5 704 acres of brackish marsh restoration in the area on the south 

side of the Rigolets from Sawmill Pass to Counterfeit Pass. 2.6 

million cubic yards of dredged material would be obtained from 

Lake Borgne Borrow Area 8.

Y

ES1 20,530 linear feet (3.8 miles) of shoreline protection from the south 

shore of Lake Pontchartrain to the terminus of the existing Bayou 

Chevee shoreline protection feature.

Y Y

ES2 30,750 (5.8 miles) linear feet of shoreline protection in Lake 

Pontchartrain between Chef Menteur Pass and The Rigolets. Y Y

ES3 69,900 linear feet (13.2 miles) of foreshore protection along Lake 

Borgne between Alligator Point and The Rigolets. Y Y

EV1 Three Submerged Aquatic Vegetation (SAV) protection structures 

5,000 linear feet in length, consisting of five 750 feet low level rock 

weirs spaced 100 feet apart. This feature is located along the south 

shore of Lake Pontchartrain from near the former mouth of Turtle 

Bayou to the railroad bridge. 

Y
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South Lake Borgne

LS1 45,000 linear feet (8.5 miles) of shoreline protection beginning at 

the terminus of the Bayou Dupre supplemental shoreline project, 

extending around Proctor Point to the West of Shell Beach 

supplemental funding shoreline protection.

Y Y Y

LM1 3,253 acres of marsh restoration from open water and nourishment 

of 1,064 adjacent acres in the Golden Triangle, south of the IHNC 

Surge Barrier. Approximately 14.3 million cubic yards of borrow to 

be obtained from North Lake Borgne Borrow Cycle 1.

Y Y Y

LM2 225 acres of marsh restoration and 2,628 acres of marsh 

nourishment in the area between Proctor Point and the MRGO. 

Approximately 4.45 million cubic yards of borrow material to be 

obtained from North Lake Borgne Borrow Cycle 1.

Y Y Y

LM3 911 acres of marsh creation and 950 acres of marsh nourishment 

in South Lake Borgne north of Lena Lagoon in the area bounded 

by the lake, Bayou St. Malo, MRGO, and Doulets Canal. 

Approximately 6.4 million cubic yards of borrow to be obtained from 

South Lake Borgne Borrow Cycle 6.

Y Y

LM4 225.5 acres of marsh restoration and nourishment of 54.8 adjacent 

acres of marsh in the portion of the Golden Triangle bordered by 

the GIWW, the IHNC Surge Barrier, and the MRGO. Approximately 

1.16 million cubic yards of borrow material would be obtained from 

North Lake Borgne Borrow Cycle 1.

Y Y

Terre aux Boeufs

TM1 798 acres of marsh restoration and 223 acres of marsh 

nourishment, requiring approximately 3.8 million cubic yards of 

material to be obtained from South Lake Borgne Borrow Cycle 4.

Y Y Y

TM2 770 acres of marsh restoration and 2,734 acres of marsh 

nourishment in the vicinity of Lake Ameda. Approximately 8.8 

million cubic yards of borrow material would be obtained from 

South Lake Borgne Borrow Cycle 4.

Y Y Y

TM7 2,255 acres of brackish marsh restoration and up to 3,338 acres 

of adjacent marsh nourishment on the east side of Bayou Terre 

aux Boeufs. 11.5 million cubic yards of material would be obtained 

from Lake Lery if available, but it is currently assumed that 

material will be obtained from Lake Borgne Borrow Area 2.

Y Y

TM8 1,511 acres of marsh restoration on the east side of Bayou Terre 

aux Boeufs in the vicinity of Delacroix. 9.7 million cubic yards of 

material will be obtained from South Lake Borgne Borrow Cycle 8.

Y Y

Hopedale

HM1 757 acres of marsh restoration and the nourishment of 973 acres 

of adjacent marsh, located in the Hopedale area bordered by 

MRGO to the northeast. 4.5 million cubic yards of dredged material 

would be obtained from South Lake Borgne Borrow Cycle 4.

Y Y

2.8 EVALUATION OF ALTERNATIVE PLANS 

The evaluation of effects, or comparison of the with-project and without-project conditions for 

each alternative, is a requirement of NEPA and ER-1105-2-100. The evaluation was conducted 

by assessing or measuring the differences between each with- and without-project condition 

and by appraising those differences. Evaluation consists of four general tasks described below: 
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Final Feasibility Report 2: Plan Formulation 

2-144 June 2012 

 Forecast the most likely with-project condition expected under each alternative plan, 

 Compare each with-project condition to the without-project condition and document 

the differences between the two, 

 Characterize the beneficial and adverse effects by magnitude, location, timing and 

duration, and 

 Identify the plans that will be further considered in the planning process, based on a 

comparison of the adverse and beneficial effects and the evaluation criteria. 

Plans were evaluated based on the following criteria: all relevant resources, outputs and plan 

effects; contributions to the Federal objective (NER), the study goals and objectives, compliance 

with environmental protection requirements, the Planning Guidance Notebook‘s four evaluation 

criteria (completeness, effectiveness, efficiency and acceptability) and other criteria deemed 

significant by participating stakeholders. 

Ecosystem restoration alternatives must be evaluated based on CE/ICA and significance of 

ecosystem outputs. Display of the environmental quality account is required for this study using 

a minimum of two categories of effects: costs and ecosystem restoration outputs. 

2.8.1 Risks and Uncertainties 

Risk is the product of the likelihood of failure and its consequences. Uncertainty describes any 

situation lacking absolute surety. There are significant risks and uncertainties associated with all 

ecosystem restoration plans. The adaptive management plan will address specific risks and 

uncertainties associated with the implementation of the selected plan, and potential changes to 

the plan to respond to and minimize the potential effects of these unknown variables that could 

affect plan performance and/or costs. The following section describes major sources of risk and 

uncertainty and how they could impact each plan in the final array. 

Tropical Storms 

Tropical storm events can directly and indirectly contribute to coastal land loss through erosion 

from increased wave energies, removal and/or scouring of vegetation from storm surge, and 

saltwater intrusion into estuaries and interior wetlands. Wetland loss and degradation of large 

areas can occur in a short period of time from storms. All of the plans in the final array (and the 

associated costs and benefits) are at some risk from storm damage. The extent of potential 

damage is dependent upon several unknown variables, including: the track and intensity of the 

storm, the development stage of the project, changes in future conditions in the study area, and 

variability of project performance from forecast conditions due to other factors. 

Sediment-rich areas impacted by storms are able to re-vegetate naturally if they are not 

disturbed by additional storms (Barras 2009). Therefore, the proposed placement of dredged 

material could promote the natural recovery of areas affected by storms. The nutrients and 

suspended solids associated with freshwater diversions would also assist in minimizing the 

adverse effects of storms to restored marsh. 
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Brackish and saline marsh communities appear to be more resilient to shearing than fresh and 

intermediate communities (Barras 2009). The majority of fresh and intermediate marsh areas 

proposed for restoration in the FIP are located in the Central Wetlands, where storm damage 

risk is reduced by the Chalmette Loop Levee. Intermediate marsh restoration proposed along 

the Lake Borgne/MRGO Landbridge would remain susceptible to storm surge and shearing. 

However, these areas would be more resilient than the existing marsh due to the anticipated 

benefits of proposed shoreline protection, dredged material placement, vegetative planting, and 

nourishment from the proposed freshwater diversion. Although these areas could be 

significantly damaged by a storm event, the proposed action would decrease the extent of 

damage and increase the likelihood that these areas could recover naturally compared to 

existing and future without project conditions. 

The brackish features in the Terre aux Boeufs and Hopedale areas are located in interior areas 

that are less susceptible to scouring and removal of vegetation than areas directly adjacent to 

large open water areas. The anticipated benefits of restoration in these areas could be 

significantly reduced by a storm, particularly if marsh vegetation was not well established. Some 

of the sediment placed in these areas could be lost in a storm event. However, because there is 

a buffer between these features and large open water areas, it is less likely that the benefits of 

restoration features in this area would be lost entirely. 

Depending on the track and intensity of the storm, the proposed ridge feature at Bayou La 

Loutre could reduce potential storm damage to adjacent areas, including features LM3 and 

BM1. The ridge feature would be more resilient when fully vegetated than during construction. 

However, if the ridge feature was damaged during construction, it is likely that sediment would 

be dispersed throughout the adjacent marsh areas, benefitting those areas while reducing or 

eliminating the benefit to the proposed ridge. 

The predicted benefits of Features EM1, EM2, EM3, and EM4 are at risk of scouring and 

shearing from storms. Depending on the track and intensity of a storm, the benefits in these 

areas could be significantly reduced. However, without restoration, the destruction of these 

areas could increase storm damage risk in the study area. 

The benefits of shoreline protection features could be reduced by a storm through the 

displacement of rocks and damage to the structures. Repair of storm damage to these features 

would increase the anticipated costs to maintain the anticipated erosion reduction benefits, 

reducing the cost-effectiveness of these features. 

Increased Sea Level Rise 

Increased sea level rise could convert emergent wetlands to shallow open water, and shallow 

open water to deeper water habitat, reducing or eliminating the effectiveness of restoration 

plans. Proposed restoration features adjacent to open water are more susceptible to the effects 

of increased sea level rise than more interior areas. Risks associated with increased sea level 

rise are discussed separately in the following section. 
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Climate Change 

Extreme changes in climate could result in conditions that cannot support the types of habitat 

restored, reducing the effectiveness of the restoration plan. Extreme climate change could 

essentially eliminate the benefits of vegetative plantings, if the change resulted in fatality. The 

adaptive management plan includes provisions for monitoring climate change and triggers for 

adjusting plan implementation to these potential changes. 

Errors in Analysis 

Future conditions are inherently uncertain. The forecast of future conditions is limited by existing 

science and technology. Future conditions described in this study are based on an analysis of 

historic trends and the best available information. Some variation between forecast conditions 

and reality is certain. Restoration features were developed in a risk-aware framework to 

minimize the degree to which these variations would affect planning decisions. However, errors 

in analysis or discrepancies between forecast and actual conditions could affect the 

effectiveness of plans. 

All of the models used in this study are abstract mathematical representations of reality. Models 

simulate complex systems by simplifying real processes into expressions of their most basic 

variables. These tools assist with finding optimal solutions to problems, testing hypothetical 

situations, and forecasting future conditions based on observed data. No model can account for 

all relevant variables in a system. The interpretation of model outputs must consider the 

limitations, strengths, weaknesses and assumptions inherent in model inputs and framework. 

Inaccurate assumptions or input errors could change benefits predicted by models used in this 

study. The potential for significant changes due to errors has been reduced through technical 

review, sensitivity analyses, and quality assurance procedures. However, there is inherent risk 

in reducing complex natural systems into the results of mathematic expressions driven by the 

simplified interaction of key variables. 

Salinity 

Salinity is a specific source of potential analytical variability because salinity in the study area is 

changing. For instance, salinity in the MRGO in the vicinity of the Central Wetlands was reduced 

to approximately 4 to 7ppt following the closure of the MRGO. Coastwide Reference Monitoring 

Stations indicate that Central Wetlands salinity is lower than 4ppt and is continuing to decline. 

Contributing factors include the closure of MRGO, the closure of Bayou Dupre during the 

construction of the Chalmette Loop Levee, the construction of the IHNC Surge Barrier, and the 

concurrent operation of the existing Violet Siphon. If salinity is different from predicted 

conditions, it may not be possible to support the habitat type planned for that area. 

Implementation

The timing and availability of financial resources for implementation is a major uncertainty that 

must be considered. If the plan is not implemented in the near future, the problems in the study 

area will continue to degrade conditions. The impact of the uncertainties associated with the 
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2-147 June 2012 

future condition of the study area could increase restoration costs, decrease restoration 

benefits, or both. The uncertainties associated with implementation are increased because a 

non-Federal sponsor has not been identified. 

All plans in the final array of alternatives require phased implementation, which can reduce risk. 

With phased implementation, costs are expended periodically, rather than all at once, which 

reduces risk to the monetary investment. Phased implementation also provides the opportunity 

to adjust project design and develop lessons learned from projects built in the initial phase. 

The relative risk of each plan is based on the differences in consequences. Because it has the 

lowest benefits and costs, Plan A involves no action, and therefore the risk to the ecosystem is 

greatest under this scenario. The risk associated with Plan B is less than Plan A, because some 

key restoration features, would be implemented. Plan B reduces the risk to some critical 

landscape features, but does not provide as much restoration and protection as Plan C. The risk 

to ecosystem form and function is less with Plan C than Plans A and B, because it includes 

more actions to protect and restore key geographic components of the ecosystem. Plan D 

provides the most restoration features of all of the plans evaluated in the final array, and further 

decreases the risk to ecosystem form and function. Table 2-26 evaluates the susceptibility of 

plan features to risks. 

Table 2-26. Relative Sustainability of Features 

Measure

Relative Susceptibility to Risk

Tropical 

Storms

Climate 

Change

Increased 

RSLR

Analytical 

Variability Implementation Overall Risk

EM2 High Moderate High Moderate Moderate Moderate-High

EM3 Moderate Moderate High Moderate Moderate Moderate

EM4 Moderate Moderate High Moderate Moderate Moderate

EM1 Moderate Moderate High Moderate Moderate Moderate

EM5 High Moderate High Moderate Moderate Moderate-High

ES1 High Low High Low Low Moderate

ES2 High Low High Low Low Moderate

ES3 High Low High Low Low Moderate

EV1 High Low High Low Low Moderate

MRGO1 High Low High Low Low Moderate

MRGO2 High Low High Low Low Moderate

MRGO3 High Low High Low Low Moderate

MRGO4 High Low High Low Low Moderate

MRGO5 High Moderate High Moderate Moderate Moderate-High

MRGO6 High Low High Low Low Moderate

MRGO7 High Moderate High Moderate Moderate Moderate-High

MRGO8 High Moderate High Moderate Moderate Moderate-High

LM1 High Moderate High Moderate Moderate Moderate-High
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Table 2-26. Relative Sustainability of Features 

Measure

Relative Susceptibility to Risk

Tropical 

Storms

Climate 

Change

Increased 

RSLR

Analytical 

Variability Implementation Overall Risk

LM2 High Moderate High Moderate High Moderate-High

LM3 High Moderate High Moderate Moderate Moderate-High

LM4 Low Moderate High Moderate Low Moderate

LS1 High Low High Low Low Moderate

CC1 –CC6 Low Moderate Moderate Moderate Moderate Moderate

CM1-CM5 Moderate Moderate Moderate Moderate Moderate Moderate

TM1 High Moderate High Moderate Moderate Moderate-High

TM2 High Moderate High Moderate Moderate Moderate-High

TM7 High Moderate High Moderate Moderate Moderate-High

TM8 High Moderate High Moderate Moderate Moderate-High

HM1 High Moderate High Moderate Moderate Moderate-High

BR1 High High Low High Moderate High

BS1 High Low High Low Low Moderate

BS2 High Moderate High Moderate Low Moderate-High

BS3 High Low High Low Low Moderate

BM1 High Moderate High Moderate Moderate Moderate-High

2.8.2 Assessment of Sustainability for Relative Sea Level Rise 

Scenarios 

Features contained within the final array of alternatives were assessed on a Yes/No scale for each of 

the following four sustainability factors: 

1. Elevation – Features at higher elevations are more sustainable under relative sea level 

rise, e.g. ridges, than features at marsh elevation. (Y = features that are higher than 

marsh elevation; N = features that are at marsh elevation) 

2. Freshwater influence – Features that are influenced by rivers or river diversions have a 

sustainable source of freshwater and sediment to nourish them and aid in accretion. (Y = 

features nourished by freshwater; N = features not nourished by fresh water) 

3. Wave energy – Features that are protected from wave energy (e.g. interior marsh) are 

more sustainable than features subjected to high wave energy. (Y = features protected 

from high wave energy; N = features not protected from high wave energy) 

4. Natural features – Features that are natural, living features of the ecosystem such as 

marsh are more sustainable than hard structures such as rock that subside more quickly 

and cannot sustain themselves and therefore require more O&M. (Y = natural features; 

N = hard features) 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 2: Plan Formulation 

2-149 June 2012 

After each feature or groups of features was assessed for each sustainability factor, the feature was 

assigned numerical and qualitative scores as follows: 

 Sustainability factors were convert to points: Yes (Y) = 1 point. No (N) = 0 points. 

If a feature included more than one component and received a Yes score for one 

component and a No score for the other component, it received a half point. 

 Points were then totaled and converted into a qualitative score as follows: 0 = 

Poor; 1 = Fair; 2 = Good; 3 = Very Good; 4 = Excellent. 

Table 2-27. Sustainability under Relative Sea Level Rise by Feature.

Area ID Plans

Sustainability Factors

Score Elev. FW Influ. Wave 

Energy

Natural 

feature

East Orleans 

Landbridge

EM2 B, C (FIP), D N Y N Y 2 Good

EM3 C (FIP), D N Y Y Y 3 Very Good

EM4 C (FIP), D N Y N Y 2 Good

EM1 B, C (FIP), D N N N Y 1 Fair

EM5 D N N N Y 1 Fair

ES1 C (FIP), D N N N N 0 Poor

ES2 C (FIP), D N N N N 0 Poor

ES3 C (FIP), D N N N N 0 Poor

EV1 D N N N N 0 Poor

MRGO

MRGO1 B, C (FIP), D N N N N 0 Poor

MRGO2 B, C (FIP), D N N N N 0 Poor

MRGO3 B, C (FIP), D N N N N 0 Poor

MRGO4 B, C (FIP), D N N N N 0 Poor

MRGO5 B, C (FIP), D N Y N Y/N 1.5 Fair/Good

MRGO6 B, C (FIP), D N N N N 0 Poor

MRGO7 B, C (FIP), D N Y N Y/N 1.5 Fair/Good

MRGO8 C (FIP), D N Y N Y/N 1.5 Fair/Good

South 

Lake 

Borgne

LM1 B, C (FIP), D N Y N Y 2 Good

LM2 B, C (FIP), D N Y N Y 2 Good

LM3 B, C (FIP), D N Y N Y 2 Good

LM4 C (FIP), D N Y Y Y 3 Very Good

LS1 C (FIP), D N N N N 0 Poor

Central Wetlands

CC1 –

CC6

B, C (FIP), D Y Y Y Y 4 Excellent

CM1-

CM5

C (FIP), D N Y Y Y 3 Very Good

Terre aux 

Boeufs

TM1 B, C (FIP), D N N Y Y 2 Good

TM2 B, C (FIP), D N N Y Y 2 Good

TM7 C (FIP), D N N Y Y 2 Good

TM8 C (FIP), D N N Y Y 2 Good

HM1 C (FIP), D N N Y Y 2 Good

Biloxi 

Marsh

BR1 B, C (FIP), D Y Y Y Y 4 Excellent

BS1 C (FIP), D N N N N 0 Poor

BS2 C (FIP), D N N N N 0 Poor

BS3 D N N N N 0 Poor

BM1 C (FIP), D N Y N Y 2 Good
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 2: Plan Formulation 

2-150 June 2012 

If the sustainability scores are averaged, Plans B, C, and D are all in the range of Fair to Good 

sustainability (1-2). All plans include the most sustainable types of features, i.e. the cypress swamp 

and ridge habitat. The smallest plan, Plan B is marginally more sustainable simply because it 

includes the least number of features. For Plans C and D, sustainability decreases marginally as less 

sustainable features, such as shoreline protection, are added. 

Relative Sea Level Rise Scenario Analysis Conclusions 

Under the medium scenario, the cost-effectiveness of all of the action plans would decrease. To 

achieve the level of benefits projected for the historic rate under the medium scenario, additional 

lifts and maintenance of restoration features beyond predicted OMRR&R actions may be 

required. The alternative to increased maintenance would be significantly reduced benefits. 

Under the low and medium sea level rise scenarios, it does not appear that land/water ratios 

would be altered to the extent that habitat-switching would occur in the restored areas. Adaptive 

management actions could mitigate potential switching under these sea level rise scenarios. 

The diminished output of the alternative plans under the high sea-level rise scenario requires 

serious consideration. The recommendations for this study include an assessment of sea level 

rise rates and appropriate responses. 

2.8.3 Comparison of Impacts to Significant Resources 

Table 2-28 provides a comparative summary evaluation of the potential adverse and beneficial 

impacts to significant resources for the pans included in the final array of alternatives.
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Final Feasibility Report 2: Plan Formulation 

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Table 2-28. Evaluation of Potential Impacts to Significant Resources by Alternative over the Period of Analysis

Significant 

Resources

Plan A

No Action

Plan B Plan C Plan D

HYDROLOGY AND 

HYDRAULICS

No direct impacts. Indirect and 

cumulative impacts include: altered 

flow patterns, paths of tidal 

propagation, and loss of tidal 

connection. Some reduction in 

salinity is anticipated due to other 

authorized freshwater diversion 

projects.

Wave modeling conducted for 

this study indicates that 

impacts from dredging Lake 

Borgne would be negligible.

Impacts would be similar to 

Plan B.

Impacts would be similar to 

Plan B.

WATER QUALITY

Current water quality conditions 

would persist; low DO levels and 

bacterial pollution would persist; 

continues loss wetlands reduce 

ability to filter and absorb 

pollutants.

The protection, restoration and 

nourishment of 30,020 acres of 

marsh and swamp would 

benefit water quality in terms of 

increased DO, reduced 

turbidity, and filtration and 

trapping of pollutants once 

construction completed.

The protection, restoration 

and nourishment of 57,452

acres of marsh and swamp 

would benefit water quality 

as described for Plan B. The 

area potentially benefitted by 

Plan C is greater than Plan 

B.

The protection, restoration 

and nourishment of 58,409

acres of marsh and swamp 

would benefit water quality 

as described for Plan B. 

The area potentially 

benefitted by Plan D is 

slightly greater than Plan 

C.

NAVIGABLE 

WATERWAYS

Current conditions would persist.

Other projects such as other fresh 

water diversions; MRGO closure; 

sector gates on the Gulf 

Intracoastal Waterway and Bayou 

Bienvenue; and construction of the 

storm surge barrier may affect 

current navigable waterways.

Mississippi River navigation 

would not be impacted.

Navigation in the GIWW 

minimally impacted by the 

diversion flow current. 

Impacts would be similar to 

Alternative B.

Impacts would be similar to 

Alternative B.

SOILS

Continued loss of sediments due to 

shoreline erosion and wetland 

loss.

No prime farmland soils would 

be adversely impacted.

Impacts would be similar to 

Alternative B.

Impacts would be similar to 

Alternative B.
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

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Table 2-28. Evaluation of Potential Impacts to Significant Resources by Alternative over the Period of Analysis

Significant 

Resources

Plan A

No Action

Plan B Plan C Plan D

AIR QUALITY

St. Bernard, St Tammany, Orleans, 

and Plaquemines Parish are in 

attainment for all pollutants. Air 

quality trends would have no direct 

beneficial or adverse impacts.

Emissions increases from 

construction are not expected 

to cause or contribute to a 

violation of Federal or state 

ambient air quality standards.

Impacts would be similar to 

Plan B.

Impacts would be similar to 

Plan B.

NOISE No impacts anticipated from FWOP 

condition

No significant impacts 

anticipated; potential temporary 

and local impacts to 

communities near the diversion 

site during construction. Some 

temporary disturbance to 

wildlife during construction of 

other features.

Impacts would be similar to 

Plan B.

Impacts would be similar to 

Plan B.

HTRW

No potential impacts because there 

are no associated construction 

activities.

An HTRW Phase I in the study 

area was performed on the 

study area, and identified a low 

probability of encountering 

contaminants of concern.

Potential impacts would be 

similar to Plan B.

Potential impacts would be 

similar to Plan B.

COASTAL 

VEGETATIVE 

RESOURCES

Loss of 131,091 acres by 2065.

The protection, restoration and 

nourishment of 30,020 acres of 

marsh and swamp would 

benefit coastal vegetation 

resources. Losses would be 

significantly less in areas 

benefitted by the plan; 

however, in areas outside of 

project areas land loss are 

likely to continue at current or 

increased rates.

Beneficial impacts would be 

greater than Plan B, due to 

27,452 acres of additional 

restoration.

Beneficial impacts would 

be greater than Plan C, 

due to 937 acres of 

additional restoration.
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 2: Plan Formulation 

2-153 June 2012 

Table 2-28. Evaluation of Potential Impacts to Significant Resources by Alternative over the Period of Analysis

Significant 

Resources

Plan A

No Action

Plan B Plan C Plan D

WILDLIFE 

RESOURCES

Continued decline in quality of 

wildlife habitat adversely impacts 

wetland dependent wildlife 

populations.

Significantly beneficial impacts 

vital to neotropical migratory 

birds; colonial nesting birds, 

waterfowl and mammals.

Beneficial impacts would be 

similar to Plan B; although 

the scope of benefits is 

greater due to 27,452 acres 

of additional restoration.

Plan D would benefit 937 

more acres of potential 

wildlife habitat than Plan C. 

AQUATIC AND 

FISHERY 

RESOURCES

Wetland fragmentation, emergent 

wetland loss, shoreline and bank 

line erosion would result in loss of 

critical EFH, reducing the area‘s 

ability to adequately support 

federally managed species.

Preliminary analyses indicate 

no significant adverse impacts 

to fishery species. Wetlands 

restoration and protection 

would benefit fisheries.

Potential impacts similar to 

Plan B. Potential benefits are 

greater than Plan B due to 

additional 27,452 acres of 

restoration.

Potential impacts similar to 

Plan B. Potential benefits 

are slightly greater than 

Plan C, due to an 

additional 937 acres of 

restoration.

COMMERCIAL 

FISHERIES

Declined expected as habitat loss 

and degradation from erosion due 

to salinity changes leads to 

overfishing of the resource.

Restoreed marsh is anticipated 

to increase productivity.

Similar to Plan B, although 

greater beneficial impacts 

due to 27,452 acres of 

additional wetland habitat 

restoration. Additional 

beneficial impacts to oyster 

fisheries anticipated with the 

inclusion of an artificial oyster 

reef in the Biloxi Marsh.

Similar to Plan C; slightly 

greater potential impacts 

due to 937 acres of 

additional restoration.

PLANKTON 

RESOURCES

No Action would have an additive 

impact due to increasing salinity 

and a transition to more marinedominated community.

No substantial affect on 

plankton abundance or 

distribution.

Similar to Plan B. Similar to Plan B.

WATER BOTTOMS 

AND BENTHIC 

RESOURCES

Persistence of existing conditions, 

including existing emergent 

wetlands converted to water 

bottoms no longer available for use 

by benthic species assemblages 

typically using this habitat.

Excavation of 87 million cubic 

yards of material, from a total of 

9,036 acres of water bottom.

Excavation of 152 million 

cubic yards of material from 

a total of 15,724 acres of 

water bottom.

Impacts would be similar to 

Plan C, although borrow 

material would increase by 

2.3 million cubic yards.
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 2: Plan Formulation 

2-154 June 2012 

Table 2-28. Evaluation of Potential Impacts to Significant Resources by Alternative over the Period of Analysis

Significant 

Resources

Plan A

No Action

Plan B Plan C Plan D

ESSENTIAL FISH 

HABITAT

Wetland fragmentation and 

emergent wetland loss contributing 

to the continued degradation of 

EFH for species utilizing this habitat 

such as; larvae and juvenile brown 

shrimp, juvenile white shrimp, all 

life stages of red drum, and juvenile 

dog snapper.

30,020 acres of marsh and 

swamp restoration would 

create a more continuous 

emergent transitional wetland

and would benefit EFH.

57,452 acres of marsh and 

swamp restoration would 

create a more continuous 

emergent transitional wetland 

would benefit EFH.

Preliminary analyses same 

as Plan B.

59,409 acres of marsh and 

swamp restoration would 

create a more continuous 

emergent transitional 

wetland would benefit 

EFH. Preliminary analyses 

same as Plan B.

THREATENED 

AND 

ENDANGERED 

SPECIES

Loss of coastal wetland habitat 

resulting from the continued 

transition of wetland habitats and 

barrier island habitats to shallow 

open water habitats.

Approximately 87 million cubic 

yards of material to be 

borrowed from Gulf sturgeon 

critical habitat. Preferred habitat 

was excluded from potential 

borrow sites to minimize 

potential adverse impacts.

Potential impacts are greater 

than Plan B due to 

approximately 65 million 

cubic yards of additional 

borrow material to be 

obtained from Gulf sturgeon 

critical habitat. Approximately 

44 miles of foreshore 

protection in critical habitat.

Potential impacts are 

greater than Plan C 

approximately 2.3 million 

cubic yards of additional 

borrow material and 3 

miles of SAV protection in 

Gulf sturgeon critical 

habitat.

SOCIOECONOMIC 

RESOURCES -

Population

The No Action Alternative would 

have no direct, indirect, or 

cumulative impacts on human 

populations.

The plan is not anticipated to 

have any direct, indirect, or 

cumulative effects on nearby 

populations.

Impacts would be similar to 

Plan B.

Impacts would be similar to 

Plan B.

SOCIOECONOMIC 

RESOURCES –

Community 

Cohesion

The No Action Alternative would 

have no impact on community 

cohesion

The construction of the 

diversion would create a new 

canal in an agricultural field 

between two communities 

potentially impacting 

community cohesion.

Impacts similar to Plan B. Impacts similar to Plan B.
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

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Table 2-28. Evaluation of Potential Impacts to Significant Resources by Alternative over the Period of Analysis

Significant 

Resources

Plan A

No Action

Plan B Plan C Plan D

SOCIOECONOMIC 

RESOURCES –

Employment and 

Income

The No Action Alternative would 

result in continued wetland loss 

and localized impacts on 

employment and income.

Plan B would work 

synergistically with other 

projects to help support coast 

wide wetland-dependent 

employment.

Plan C have greater 

beneficial synergistic effects 

than Plan B due to the 

27,452 acres of additional 

wetland habitat restoration.

Impacts would be similar to 

Plan C.

SOCIOECONOMIC 

RESOURCES -

Infrastructure

The decline wetlands would 

contribute to the deterioration of 

substrate upon which infrastructure 

features are constructed.

Plan B would restore or protect 

30,020 acres in the study area, 

which would assist with 

protection of existing 

infrastructure.

Plan C would provide greater 

beneficial impacts through 

the restoration of 27,452

acres more than Plan B.

Impacts would be slightly 

greater than Plan C, 

because 937 additional 

acres would be restored.

SOCIOECONOMIC 

RESOURCES –

Oil, Gas and Utilities 

Pipelines

The No Action Alternative could 

expose buried pipelines thereby 

increasing the risk of failure or 

damage due to lack of structural 

stability, anchor dragging, and boat 

collisions.

The restoration proposed for 

Plan B would prevent the 

increase in maintenance and 

relocation costs for pipelines in 

and around the project areas.

Plan C would provide more 

complete protection for oil 

and gas infrastructure than 

Plan B, and would produce 

more beneficial impacts 

through the restoration of 

27,452 additional acres.

Impacts would be slightly 

greater than Plan C, 

because 937 additional 

acres would be restored.

SOCIOECONOMIC 

RESOURCES –

Commercial 

Fisheries

Continued conversion of existing 

wetlands to open water habitats, 

continued bankline erosion and 

sloughing of the shoreline. Sharp 

declines are predicted in fisheries 

productivity under the No-Action 

Alternative.

Plan B would increase 

important fisheries habitat.

Overall, the industry would be 

more stable in the study area 

due to a long-term increase in 

the quality of fisheries habitat.

Plan C would provide greater 

beneficial impacts to fisheries 

habitat than plan B, by 

providing an additional

28,452 acres of marsh 

benefits.

Impacts would be similar to 

Plan C.

SOCIOECONOMIC 

RESOURCES –

Recreation

There are no recreational benefits 

of Plan A,

The net value of incidental 

recreational benefits 

associated with Plan B is 

estimated to be increase by 

$1,751,000 or $78,374 of 

annualized benefits compared 

to Plan A.

The net value of incidental 

recreational benefits 

associated with Plan C is 

estimated to be increase by 

$3,956,000 or $177,070 of 

annualized benefits 

compared to Plan A.

The net value of incidental 

recreational benefits 

associated with Plan D is 

estimated to be increase 

by $3,956,000 or $177,070 

of annualized benefits 

compared to Plan A.
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

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2-156 June 2012 

Table 2-28. Evaluation of Potential Impacts to Significant Resources by Alternative over the Period of Analysis

Significant 

Resources

Plan A

No Action

Plan B Plan C Plan D

SOCIOECONOMIC 

RESOURCES –

Oyster Leases

The loss of wetlands in the project 

area would likely alter the detritusbased food web of the oyster 

thereby reducing the localized 

carrying capacity for oyster leases 

in the area.

Increases to productivity are 

anticipated in the Biloxi Marsh.

Impacts would be similar to 

Plan B.

Impacts would be similar to 

Plan B.

SOCIOECONOMIC 

RESOURCES –

Flood Control and 

Hurricane 

Protection Levees

The No Action Alternative would 

have no direct impacts on flood 

control or hurricane protection 

levees. Indirect impacts would 

result in the continued degradation 

of the landbridge separating Lake 

Borgne from the MRGO channel, 

the conversion of existing wetlands 

to open water habitats, and the 

continued bankline erosion and 

sloughing of the shoreline.

Plan B would protect and 

restore marsh outside of the 

levees, which would help 

protect the levees, allowing 

current level of risk reduction in 

the project areas to be 

maintained.

Benefits would be greater 

than Plan B, by providing an 

additional 28,452 acres of 

marsh benefits

Impacts slightly greater 

than Plan C, by providing 

additional marsh benefits.

SOCIOECONOMIC 

RESOURCES –

Navigation

As Louisiana‘s coastal wetlands 

continue to fragment and convert to 

open water, the protection 

wetlands provide to inland 

waterways from wind-driven waves 

would be reduced.

Plan B would work with other 

projects to protect adjacent 

waterways, such as the GIWW, 

from waves propagated 

through the lake, thus providing 

a safer route for inland waterborne traffic.

Impacts would be similar to 

Plan B.

Impacts would be similar to 

Plan B.

ENVIRONMENTAL

JUSTICE

With continued wetland loss, loss 

of valuable property increased 

flooding risk of homes and 

businesses, impacts would affect 

all population groups. 

Communities are located on 

either side of the agricultural 

field where the proposed 

diversion would be located. 

Potential impacts would be 

the same as Plan B.

Potential impacts would be 

the same as Plan B.
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

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2-157 June 2012 

Table 2-28. Evaluation of Potential Impacts to Significant Resources by Alternative over the Period of Analysis

Significant 

Resources

Plan A

No Action

Plan B Plan C Plan D

HISTORIC AND 

CULTURAL 

RESOURCES

Continued erosion of cultural sites 

is expected.

Deposition of dredged material 

could increase the rate of 

subsidence and the 

disappearance of important 

sites from the archaeological 

record. National Register 

eligible sites would be avoided 

or adverse effects will have to 

be mitigated. A programmatic 

agreement with the SHPO and 

ACHP is being pursued for this 

study.

Plan C includes 27,452 acres 

of restoration activities more 

than Plan B, and therefore 

greater potential impacts.

Plan D includes 937 acres 

of restoration activities 

more than Plan C, and 

therefore greater potential 

impacts.

RECREATION 

RESOURCES

Continued wetland loss and 

conversion of existing wetlands to 

open water habitats resulting in 

decreased structural complexity 

and habitat diversity of recreational 

fish caught and game species 

hunted.

Restoration would likely 

improve recreational fishing 

and wildlife hunting 

opportunities.

For wetland measures, 

beneficial impacts are to a 

greater extent due to 

additional 27,452 acres of 

restoration. 

Impacts are similar to Plan 

C, with slightly greater 

beneficial impacts due to 

an additional 937 acres of 

restoration.

AESTHETICS

(Scenic Rivers)

Continued habitat deterioration, 

land loss, and conversion to open 

water reducing scenic qualities of 

area.

The plan would benefit marsh 

and swamp in the vicinity of the 

scenic streams restoring their 

viewscape to its original habitat 

types.

Impacts similar to Plan B. Impacts similar to Plan B.
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2-158 June 2012 

2.9 COMPARISON OF ALTERNATIVE PLANS 

Alternative plans were compared against each other, with emphasis on benefits and impacts, 

with respect to study goals and objectives and NER objectives. Table 2-29 provides a summary 

of how each alternative plan meets the study objectives. 

Table 2-29. Comparison of the Alternative Plans and Plan Objectives 

Objective Plan A Plan B Plan C Plan D

1. Salinity Target No Yes Yes Yes

2. Cypress 

(Minimum 9,500 acres) No Yes Yes Yes

3. Fresh/Intermediate 

(Minimum 6,800 acres) No Yes Yes Yes

4. Brackish 

(Minimum 18,100 acres) No No Yes Yes

5. Additional marsh types lost through 

erosion

(Minimum 3,900 acres)

No No Yes Yes

7. Ridge Habitat No Yes Yes Yes

8. Landscape Features for

Surge Reductiona No Yes Yes Yes

a

 Landscape features for surge reduction include acres restored, nourished or protected on the 

East Orleans Landbridge and the Biloxi Marsh. 

2.9.1 Completeness, Effectiveness, Efficiency and 

Acceptability 

Acceptability is the extent to which the alternative plans are acceptable in terms of applicable 

law, regulations and public policies. ―An ecosystem restoration plan should be acceptable to 

state and Federal resource agencies, and local government. There should be evidence of broad 

based public consensus and support for the plan.‖ (ER 1105-02-100). 

Completeness is the extent to which an alternative plan provides and accounts for all necessary 

investments or other actions to ensure the realization of the planning objectives. It is an 

indication of the degree that the outputs of the plan are dependent upon the actions of others. 

Plans that require substantial activity by others in order to achieve their objectives are not likely 

to be complete. ―The plan must provide and account for all necessary investments or other 

actions needed to ensure the realization of the planned restoration outputs...Real estate, O&M, 

monitoring, and sponsorship factors must be considered.‖ (ER 1105-02-100). 

Effectiveness is the extent to which an alternative plan contributes to achieving the planning 

objectives. ―An ecosystem restoration plan must make a significant contribution to addressing 

the specified restoration problems or opportunities (i.e., restore important ecosystem structure 

or function to some meaningful degree.‖ (ER 1105-02-100). 
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2-159 June 2012 

Efficiency is the extent to which an alternative plan is the most cost effective means of achieving 

the objectives. ―An ecosystem restoration plan must represent a cost-effective means of 

addressing the restoration problem or opportunity. It must be determined that the plan‘s 

restoration outputs cannot be produced more cost-effectively by another agency or institution.‖

(ER 1105-02-100). 

Table 2-30 compares the final array in terms of completeness, effectiveness, efficiency and 

acceptability.

Table 2-30. Comparison of Completeness, Effectiveness, Efficiency, and Acceptability

Completeness Effectiveness Efficiency Acceptability

Plan A No No No No

Plan B No No No No

Plan C Yes Yes Yes Yes

Plan D Yes Yes Yes Yes

Plan A (No-Action Alternative) 

Plan A is the least acceptable plan in terms of public law and regulation, in that it violates the 

mandate of the Congress in WRDA 2007, Section 7013. It does not meet the acceptability 

criterion because it is not consistent with public policy, as evidenced by CWPPRA, LCA, 

LACPR, the 2007 State Master Plan, the Louisiana-Mississippi Gulf Coast Ecosystem 

Restoration Working Group‘s Roadmap for Restoring Ecosystem Resiliency and Sustainability, 

and other restoration initiatives.

The no-action alternative does not meet the completeness criterion because it does not provide 

any means to realize the planning objectives of this feasibility study. 

Plan A does not meet the effectiveness criterion because it does not achieve any of the 

planning objectives. 

Plan A is the least efficient alternative because it is estimated to result in a net economic loss to 

the nation. Plan A would not produce any benefits but would result in increased costs to protect 

infrastructure in the study area. 

Plan B 

Plan B is more acceptable than Plan A, but it does not fully address this criterion. Plan B does 

not meet the acceptability criterion because it does not include elements that would protect and 

restore the Biloxi Marsh, a critical landscape feature for storm surge risk reduction. Restoration 

in this area has been identified as important in previous restoration studies. 

Plan B does not meet the completeness criterion because it would require actions by others to 

realize the planning objectives; i.e. restoration of brackish habitat and the Biloxi Marsh. 

The effectiveness criterion is not fully addressed by Plan B because it does not achieve the 

brackish marsh objective. The restoration features included in Plan B would contribute to 

restoring ecosystem structure and function. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 2: Plan Formulation 

2-160 June 2012 

Plan B is an efficient plan. However, it does not achieve all of the planning objectives, and 

therefore is not the most efficient means of achieving the objectives. 

Plan C 

Plan C is acceptable in terms of public law and regulation, in that it provides a plan for 

ecosystem restoration in areas affected by the navigation channel, consistent with WRDA 2007, 

Section 7013. Plan C also addresses previously documented public policy as evidenced by 

CWPPRA, LCA, LACPR, the 2007 State Master Plan, the Louisiana-Mississippi Gulf Coast 

Ecosystem Restoration Working Group‘s Roadmap for Restoring Ecosystem Resiliency and 

Sustainability, and other restoration initiatives.

All actions required to achieve the planning objectives are accounted for in Plan C, and it is not 

significantly dependent on the actions of others. Plan C is a complete plan that would enhance 

the overall goals of coastal restoration by complementing other restoration efforts. 

Plan C meets the effectiveness criterion because it achieves all of the planning objectives and 

would significantly contribute to restoring ecosystem structure and function. Plan C is a 

complete plan for the Lake Borgne ecosystem and the areas affected by the MRGO. The 

restoration features included in Plan C work with existing and authorized projects to restore and 

protect the Lake Borgne ecosystem. 

Plan C is the most efficient means of achieving the objectives because it is the least-cost Best 

Buy plan that meets all of the study objectives. 

Plan D 

Plan D is slightly more acceptable than Plan C, because it includes more restoration features 

desired by the public. Plan D does not violate public laws and regulations. 

Plan D is a complete plan that is not significantly dependent on the actions of others, and would 

enhance the overall goals of ecosystem restoration. 

Plan D is slightly more effective than Plan C because it includes more features that would 

contribute to restoring ecosystem structure and function. 

Plan D is a cost effective means of achieving the objectives of the study, but due to increased 

incremental costs compared to Plan C, it is not the most efficient. 

2.9.2 Comparison to Recommendations in LCA, LACPR, and 

the 2007 State Master Plan 

WRDA 2007 Section 7013(B)(iv) states that the MRGO Ecosystem Restoration Plan 

recommendations should include efforts to integrate with LCA and the analysis and design in 

LACPR. The authorization for LACPR was directed to be consistent with the 2007 Louisiana 

State Master Plan. The final array of alternatives was compared to these plans to determine 

consistency with other restoration efforts. Consistency with these plans also contributes to the 
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Final Feasibility Report 2: Plan Formulation 

2-161 June 2012 

completeness and acceptability of the plan. Additionally, the public significance of the resources 

protected and restored by the plan is demonstrated by consistency with other plans. 

Introduction of Sediment into the Central Wetlands (LCA, LACPR and 2007 State Master 

Plan): Plan B includes 10,431 acres of swamp restoration in the Central Wetlands. Plans C and 

D also include 3,281 acres of marsh restoration in the Central Wetlands. The placement of 

dredged material is one component of the restoration strategy for the area. 

Introduction of Sediment into the Golden Triangle (LCA, LACPR, and 2007 State Master 

Plan): Plan B includes 4,017 acres of restoration in the Golden Triangle. Plans C and D include 

the restoration of over 4,469 acres of marsh in the Golden Triangle. 

Opportunistic use of Bonnet Carré Spillway (LCA and LACPR): The State of Louisiana is 

historically opposed to large freshwater diversions at this location. A small diversion at Bonnet 

Carré would not meet the salinity objective for this study. Any size diversion at this location 

would be less effective than closer locations to sustain salinity conditions and restoration in the 

project area. Cypress and fresh marsh restoration in the Central Wetlands would not receive 

direct inputs from Bonnet Carré, and could not be as effectively adaptively managed. Therefore, 

this location was removed from further study under this effort. A freshwater diversion at Bonnet 

Carré is still authorized and may be re-assessed in future studies.

Marsh Restoration on East Orleans Landbridge (LCA and LACPR): Plan B includes 5,100 

acres of restoration and protection in the East Orleans Landbridge and the Pearl River areas. 

Plan C includes over 11,222 acres of marsh restoration and shoreline protection in this area. 

Plan D includes 11,926 acres of restoration and protection in the vicinity. 

Mississippi River Gulf Outlet (MRGO) Environmental Restoration Features (LCA and 

LACPR): Shoreline protection features in the MRGO were originally not included in Plan B and 

C. The incremental cost of these features exceeded the ecological benefits. All shoreline 

protection features on the south shore of the channel were removed from further consideration, 

as these features did not provide any ecological benefits because they are located on the levee 

side of the MRGO. Additionally, maintenance of shoreline protection features adjacent to levees 

would be conducted as needed as part of levee maintenance. Several options for shoreline 

protection on the north shore were evaluated and included in the minimum planning increment. 

Breton Sound Marsh Restoration (LACPR and 2007 State Master Plan): Plan B includes 

5,153 acres of restoration in the marsh adjacent to Breton Sound. Plans C and D include 12,252 

acres of restoration in the marsh adjacent to Breton Sound. 

Biloxi Marsh Restoration and Protection (LACPR and 2007 State Master Plan): Plan B 

does not include any restoration features in the Biloxi Marsh. Plan C includes 8,000 acres of 

marsh restoration and approximately 24 miles of shoreline protection in the Biloxi Marsh. Plan C 

includes approximately 7 more miles of shoreline protection in the Biloxi Marsh than Plan C. The 

areas targeted for restoration in Plans C and D differ from those proposed in LACPR.
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Bayou La Loutre Ridge Restoration (LACPR and 2007 State Master Plan): 54 acres of ridge 

restoration along Bayou La Loutre are included in all of the action plans. However, ridge 

restoration to the extent proposed in LACPR and 2007 State Master Plan was not cost-effective. 

Maintain MRGO – Lake Borgne Landbridge (2007 State Master Plan): Plan B includes 2,945 

acres of marsh restoration on Proctor Point and 2,816 acres or marsh restoration on the Lake 

Borgne / MRGO Landbridge. Plans C and D also include these features and approximately 9 

miles of shoreline protection along Proctor Point. 

Mississippi River Diversion at Violet (2007 State Master Plan): All of the action alternatives 

are consistent with this recommendation. 

Bayou Bienvenue Diversion (LACPR): This diversion was developed to target land-building in 

the marshes on the East Orleans Landbridge in LACPR. Flows examined in LACPR ranged 

from an average flow of 5,000 cfs in a low flow year to 175,000 cfs pulse in a high flow year. 

Planning for the Violet, Louisiana Freshwater Diversion for this study is consistent with this 

feature. 

Lake Borgne and East Orleans Landbridge Shoreline Protection (LACPR): Plan B does not 

include any shoreline protection features in Lake Borgne or the East Orleans Landbridge. Plans 

C and D include approximately 33 miles of Lake Borgne shoreline protection and approximately 

10 miles of Lake Pontchartrain shoreline protection along the East Orleans Landbridge. 

Rehabilitate Violet Siphon and Post-Authorization Change for the IHNC to divert 

Freshwater into the Central Wetlands (LCA): Preliminary analyses indicate a rehabilitation of 

the Violet Siphon and/or diversion from the IHNC would not meet the salinity objectives in the 

Biloxi Marsh and Western Mississippi Sound established for the study. The Violet, Louisiana 

Freshwater Diversion as authorized in WRDA 2007 Section 3083 is anticipated to restore 

cypress in the Central Wetlands as well as establish an optimal salinity regime.

Plans C and D are consistent with the recommendations made in the LCA and LACPR Reports. 

Plan D is the most consistent because it includes restores more acres than Plans B and C. Plan 

B is the least consistent, as it does not include features in the Biloxi Marsh or shoreline 

protection features in Lake Borgne and the East Orleans Landbridge. 
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Figure 2-34. Alternative B 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

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Figure 2-35. Alternative C 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

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Figure 2-36. Alternative D 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

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2.10 IDENTIFICATION OF THE FEDERALLY IDENTIFIED PLAN 

Plan C is the Federally Identified Plan (FIP) and NER plan as determined by all of the evaluation 

criteria discussed in Section 2.8. Selecting the NER plan requires careful consideration of 

planning goals, objectives, and constraints. The NER plan reasonably maximizes environmental 

benefits considering cost effectiveness and incremental cost analyses, significance of outputs, 

completeness, efficiency, effectiveness and acceptability. Section 7013 of WRDA 2007 requires 

the MRGO Ecosystem Restoration features of the plan to be cost effective, environmentally 

acceptable, and technically feasible determined by the Secretary of the Army for Civil Works. 

Plan C is the FIP and NER plan for this study because it is the lowest cost alternative that meets 

all of the study objectives and provides a complete plan to restore the structure and function of 

the Lake Borgne ecosystem. Other plans were evaluated that provide additional benefits, but 

the increases in costs were not considered reasonable given the relative outputs. Plan C is costeffective, and maximizes the opportunities to achieve the objectives of the study for the least 

cost. The incremental costs associated with Plan C are considered reasonable for the 

significance of the outputs achieved. 

Plan C protects and restores the portions of the Lake Borgne ecosystem that are not addressed 

by existing and authorized restoration projects. Existing and authorized shoreline protection 

projects along the shores of Lake Borgne do not comprehensively address erosion in the lake. 

Plan C would provide protection in the areas between existing and authorized projects to 

stabilize the entire shore of Lake Borgne. Marsh restoration features included in Plan C would 

work synergistically with existing and authorized projects to restore the structure of the Lake 

Borgne ecosystem. 

Although it is not feasible to restore the area to a historic condition, the FIP would restore and 

significantly improve the areas affected by the navigation channel. Plan C would restore and 

protect approximately 57,472 acres of habitat in the study area, including 14,123 acres of fresh 

and intermediate marsh; 32,511 acres of brackish marsh; 10,430 acres of cypress swamp; 466 

acres of saline marsh; and 54 acres of ridge habitat. Plan C provides 71 miles of shoreline 

protection in Lake Borgne, along the MRGO, and in the Biloxi Marsh, including 5.8 miles of 

oyster reef restoration in the Biloxi Marsh. 

Implementing the FIP is anticipated to restore significant ecosystem function, structure, and 

processes through a comprehensive systems-based approach. The FIP would restore unique 

habitat in a nationally significant watershed. The FIP has significant costs, and would represent 

a continuing national commitment to the restoration of one of the Nation‘s most productive 

estuaries. There is no construction cost associated with the No Action Alternative; however, the 

loss of unique habitat and natural resources that would result from this alternative would 

represent unacceptable costs to the Nation. 

The FIP would restore rare and unique habitat, including coastal ridge, cypress swamp, and 

fresh marsh. These habitat types are institutionally and technically significant due to relative 

scarcity and importance. Wetlands of national interest, including those found in the Bayou 
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Sauvage National Wildlife Refuge and the Pearl River and Biloxi Wildlife Management Areas, 

would be restored by the FIP. 

Current and past Administrations have repeatedly demonstrated a commitment to Louisiana 

coastal restoration. President Barack Obama made the following statement during his 2009 visit 

to the Gulf Coast: 

“We've already seen 220 miles worth of levees and flood walls repaired, and we are 

working to strengthen the wetlands and barrier islands that are the first line of defense 

for the Gulf Coast. This isn't just critical to this region's physical protection, it's critical to 

our environment, it's critical to our economy.” 

- President Barack Obama, October 15, 2009 

The nation derives significant benefits from the coastal Louisiana ecosystem: protection for the 

production and transport infrastructure for about 30 percent of the nation‘s oil and gas supply; 

the Nation‘s second largest commercial fishery; and navigation and port facilities which together 

support America‘s number one port complex by tonnage. 

2.11 DESCRIPTION OF THE FEDERALLY IDENTIFIED PLAN 

Plan C would restore and protect 57,472 acres of habitat, including 10,318 acres of cypress 

swamp, 14,123 acres of fresh and intermediate marsh, 32,511 acres of brackish marsh, 466 

acres of saline marsh, and 54 acres of ridge habitat. Plan C includes 71 miles of shoreline 

protection (including 5.8 miles of artificial oyster reef). 

Approximately 11,222 acres of the restoration and protection features would be located in the 

East Orleans Landbridge/Pearl River area and approximately 9,012 acres of restoration features 

would be located in the Biloxi Marsh area, which have been determined to be critical landscape 

features with respect to storm surge. Additionally, the cypress swamp and ridge restoration 

feature would include forested habitat, which has been demonstrated as having some storm 

surge damage risk reduction benefits. 

Salinity is a key ecosystem driver. Additional study of the Violet, Louisiana Freshwater 

Diversion, as authorized for design and construction in WRDA 2007 Section 3083, is 

recommended. This project may be a means of restoring river flooding processes that would 

enhance system sustainability through freshwater, nutrients and sediment inputs. 

2.12 BORROW SITES 

The implementation of the FIP would require a significant amount of sediment. Figure 2-37 illustrates 

the proposed borrow site for each feature included in the FIP. 

Borrow sites would be located a minimum of 3,000 feet from the Lake Borgne shoreline to minimize 

potential impacts to hydraulic conditions (e.g., wave climate), and to avoid existing oyster leases to 

the extent practicable. Borrow material would be excavated with a hydraulic dredge and transported 

via pipeline to wetland creation and nourishment sites. Designated borrow areas are estimated larger 

than needed for each feature to ensure that adequate material is available in the event that 
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environmental or cultural resources are discovered during PED that require avoidance. Borrow areas 

would be designed to minimize hypoxic (lack of dissolved oxygen) formation. 

A phased implementation plan is proposed to remove borrow material from Lake Borgne. Borrow 

would be removed from the lake gradually over 10 implementation cycles that would allow no more 

than 2.5 percent of the lake bottom to be impacted during any given implementation cycle. The 

borrow plan limits dredging to one lobe of Lake Borgne per implementation cycle, therefore isolating 

increased turbidity to one lobe of the lake. As a new implementation cycle is being initiated, the 

borrow areas disturbed in the previous cycle for that lobe would have recovered sufficiently to support 

foraging and to allow benthic species to recover between implementation cycles. 

In consultation with NMFS, two years of water quality monitoring are included in the plan. Three test 

borrow pits would be constructed in implementation cycle 1. Pit 1 would be constructed to 15 feet 

deep below the water surface, Pit 2 would be constructed to the proposed depth of 20 feet deep 

below the water surface, and Pit 3 would be constructed to approximately 25 feet deep below the 

water surface. After the borrow pits are constructed, monthly water quality monitoring would be used 

to determine if hypoxia formation was occurring within the borrow pits. When monitoring is complete, 

the remaining borrow pits would be adjusted to ensure that hypoxia formation would not result within 

the remaining borrow pits. The design of the borrow pits and water quality monitoring is proposed to 

ensure that impacts to the water quality of Lake Borgne would be temporary and localized. In 

addition, USACE will collect data describing Gulf sturgeon movements within the Lower 

Pontchartrain Sub-basin and recovery rates of Gulf sturgeon prey species in response to recolonization of muddy-sand substrate that would assist in future assessments of impacts to Gulf 

sturgeon prey items. 

2.13 IMPLEMENTATION APPROACH 

Three areas of uncertainty were identified as most likely to affect ecological success and 

sustainability: salinity, implementation, and increased RSLR. Based on these factors, features 

were divided into tiers. 

 Tier 1 includes features that have been developed to a feasibility level of detail and are 

not dependent on a freshwater diversion. Tier 1 features are recommended for 

construction through the WRDA 2007 Section 7013 authority upon the identification of a 

non-Federal sponsor. 

 Tier 2 includes features with feasibility level detail that are dependent upon salinity 

conditions but may be sustainable without the implementation of a freshwater diversion. 

If future conditions and further analysis indicate that favorable conditions for ecological 

success and long term sustainability exist (as defined in the adaptive management 

plan2), then these projects may be constructed. Tier 2 features would be constructed 

through the WRDA 2007 Section 7013 authority upon the identification of a non-Federal 

sponsor. 

 Tier 3A includes further study of the Violet, Louisiana Freshwater Diversion under the 

WRDA 2007 Section 3083 authority. The non-Federal cost-share responsibilities for the 

Violet, Louisiana Freshwater Diversion would be consistent with the 75 percent/25 

 

2

 Average annual salinity: fresh marsh: <1.1 parts per thousand (ppt); intermediate marsh: <4.1 ppt; brackish marsh: <8.3 ppt, and swamp <4.0. 
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percent Federal/non-Federal cost share identified in Section 3083 of WRDA 2007, 

together with such other items of cost-share responsibilities as may be identified in the 

Feasibility Report for the project, as approved by the decision of the Chief of Engineers. 

Presently, as identified in the 1984 Chief‘s Report for Mississippi and Louisiana 

Estuarine Areas Freshwater Diversion to Lake Pontchartrain and Mississippi Sound 

Feasibility Study, the 25 percent non-Federal share of the cost of the design and 

implementation of the Violet, Louisiana Freshwater Diversion project is allocated 80 

percent to the State of Louisiana and 20 percent to the State of Mississippi. It is not 

anticipated that this allocation will change as a result of completing the feasibility study 

for the project; however, if it does, the change in allocation will be addressed in the 

study, as approved by the decision of the Chief of Engineers.

 Tier 3B includes any features that are dependent on freshwater diversion, and features 

in Tier 2 that future conditions and further analyses indicate are not sustainable. 

Subsequent to the completion of Tier 3A, Tier 3B features would be constructed through 

the Section 7013 authority upon the identification of a non-Federal sponsor. 

Salinity 

Salinity is a specific source of potential analytical variability because salinity in the study area is 

changing. For instance, salinity in the MRGO in the vicinity of the Central Wetlands was reduced 

to approximately 4 to 7ppt following the closure of the MRGO. Coastwide Reference Monitoring 

Stations indicate that Central Wetlands salinity is lower than 4ppt and is continuing to decline. 

Contributing factors include the closure of MRGO, the closure of Bayou Dupre during the 

construction of the Chalmette Loop Levee, the construction of the IHNC Surge Barrier, and the 

concurrent operation of the existing Violet Siphon. FWOP scenarios include the baseline 

conditions at Violet Siphon, Caernarvon, and Bonnet Carré Spillway leakage and openings. 

Planned diversions at Maurepas Swamp (Convent/Blind River, Hope Canal/Maurepas Swamp 

River Reintroduction), Caernarvon operation modifications, and the Central Wetlands 

Wastewater Treatment Program are also included in the FWOP conditions. 

Salinity is changing in the study area. Current conditions in the Central Wetlands are optimum 

for intermediate marsh species and the FWOP scenario predicts that conditions will be 

favorable for fresh marsh species and cypress swamp in the future. However, because 

conditions are variable and assumptions may not be accurate, all features that are dependent 

upon salinity conditions or freshwater diversions to be sustainable are not included in Tier 1. 

Implementation

Following the identification of the FIP, a construction sequence was developed. Assumptions 

factoring into the construction sequence include production rates for building rock projects, 

dredge equipment availability, land loss rates, and the limitation of alternating dredging cycles in 

the lobes of Lake Borgne. 

The timing and availability of financial resources for implementation is a major uncertainty that 

must be considered given current Federal budgetary constraints. If the plan is not implemented 

in the near future, conditions will continue to degrade. The impact of the uncertainties 

associated with the future condition of the study area could increase restoration costs, decrease 
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restoration benefits, or both. The uncertainties associated with implementation are increased 

because a non-Federal sponsor has not been identified. 

Funding assumptions, as detailed in the Engineering Appendix, were required for planning 

purposes and to develop costs and benefits for the plan. Construction sequencing assumed 

optimal funding appropriations and an aggressive schedule to complete implementation as soon 

as realistically possible. Given the considerable need for the plan, Federal interest, significance 

of resources, and the conditional authorization for implementation, an aggressive 

implementation sequence was considered appropriate. The implementation of the HSDDRS 

demonstrates National interest in study area resources and the magnitude of what can be 

achieved when stakeholders are united in purpose. However, current budgetary conditions and 

the lack of a non-Federal sponsor make it very likely that reality will differ from these optimal 

assumptions. Risk and uncertainties related to implementation have been assessed in the Cost 

Risk Analysis, as detailed in the Engineering Appendix. However, due to uncertainties 

associated with the timing and availability of funding for the plan, only features that are 

sustainable without the implementation of any other feature are recommended for construction 

at this time. 

Increased Relative Sea Level Rise 

A detailed WVA analysis of the three relative sea level rise scenarios was performed for the FIP. 

Table 2-31 below shows the net acres projected under each of the three relative sea level rise 

scenarios based on feature locations. 

Table 2-31. Robustness of Features in FIP under All Relative Sea Level Rise Scenarios* 

LOW RSLR MEDIUM RSLR HIGH RSLR

Features AAHU

Net 

Acres AAHU

Net 

Acres AAHU

Net 

Acres

Biloxi Marsh (BM1, BS1-2) 1,685 1,819 1,948 602 401 0

Bayou La Loutre Ridge (BR1) 33 19 34 55 49 55

Central Wetlands Marsh (CM1-5) 5,275 2,593 9,289 5,668 8,934 0

Central Wetlands Swamp (CC1-6) 4,600 6,387 4,843 9,577 5,584 11,332

East Orleans Landbridge (EM1, ES 1-3) 2,110 1,568 1,612 581 718 0

Lower Pearl River (EM2-4) 419 3,379 505 1,303 121 0

Lake Borgne (LM1-4, LS1) 18,112 7,965 18,034 11,940 10,021 0

Hopedale (HM1) 176 736 192 286 70 0

Terre Aux Bouefs (TM1-2, 7-8) 1,595 5,123 1,678 2,008 519 0

TOTAL 33,839 29,353 37,980 31,930 26,322 11,387

* All benefits in this table include the influence of the authorized Violet, Louisiana Freshwater Diversion.

Although it may seem counterintuitive that some AHHUs and net acres for some features 

increase as relative sea level rise increases, the reason is that the WVA calculation subtracts 

existing and future without project marsh acres from project footprints. As relative sea level rise 

increases, future marsh acres decrease. For example, the ridge produces 55 net acres. Under 
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the historic (low) rate of sea level rise, the ridge would replace 36 acres of marsh that is 

anticipated to continue to exist in the future; therefore the net acres are 19. In the medium and 

high sea level rise scenarios, no marsh acres are anticipated to exist in the FWOP condition, 

therefore, 55 net acres are produced. 

Under the medium scenario, the cost-effectiveness of all of the action plans would decrease. 

The medium scenario requires more OMRR&R actions than the historic rate of sea level rise. 

The alternative to increased maintenance would be significantly reduced benefits. The plan 

includes OMRR&R and adaptive management measures that are anticipated to maintain 

predicted benefits under the low and medium sea level rise scenarios. 

The diminished output of the FIP under the high RSLR scenario necessitates a systematic 

approach to assess and respond to the high level of sea level rise scenario. Sea level rise rates 

will be monitored in the pre-construction, construction, and post construction phases. Data will 

be evaluated at key decision points. An assessment of relative sea level rise trends would be 

made prior to partnership agreements, PED, construction award and any cost shared Adaptive 

Management actions. If at any time data indicate that the high level of RSLR is occurring , 

additional Federal investments in the plan would be re-assessed. 

Priority of Features for Tier 1 

The first features proposed for implementation in Tier 1 are LS1, MRGO1, and MRGO6 

because these areas are critical for ecosystem structure (maintaining the MRGO landbridge), 

subject to high rates of erosion, in close proximity to the MRGO, and are currently unprotected. 

The next features proposed for construction are located in areas that have been identified as 

critical landscape features, including BS1, BS2, ES1, ES2, ES3, BR1, EM2, EM3, and EM4. 

These geographic areas are significant structural elements to maintain ecosystem function and 

reduce storm surge damage risk. The shoreline protection features fill in gaps between existing 

and planned projects to provide a complete plan to address erosion along Lake Borgne and the 

East Orleans Landbridge. Most of the features in the second priority phase are in areas of 

relatively low land loss rates, and are therefore more sustainable. Feature BR1 is considered 

one of the most sustainable features under the high RSLR scenario because of its elevation. 

Features HM1, TM1, TM2, TM7, and TM8 are the next features proposed for implementation 

because they are located in interior areas that are less susceptible to sea level rise. In the last 

phase of Tier 1, the one-time repair of existing shoreline protection projects MRGO2, MRGO3, 

MRGO4, and the Shell Beach recreation feature associated with MRGO2 are proposed for 

implementation. These features are the lowest priority within Tier 1 because they currently have 

some protection. 

Priority of Features for Tier 2 

In Tier 2, features inside the HSDRRS are prioritized for construction. These features are 

considered to be more likely to exhibit favorable conditions for ecological success and 

sustainability because of their location behind existing infrastructure that provides protection 

from storms and saltwater intrusion. These features include CC4-A, CC4 (Sites 2, 3, 4), CM2, 

CM5 , LM4 and the Bienvenue Triangle recreation feature associated with CC4-A. The features 

in the Central Wetlands included in Tier 2 are located north of Paris Road and therefore have 
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more barriers to saltwater intrusion than features south of Paris Road. Feature CC4-A is 

considered the highest priority in this tier because of high public interest, proximity to the City of 

New Orleans, and its educational value. 

Priority of Features for Tier 3 

Further study of the Violet, Louisiana Freshwater Diversion as authorized by WRDA 2007 

Section 3083 is designated as Tier 3A because it is the highest priority for Tier 3, as all of the 

features in Tier 3B are dependent upon the implementation of a freshwater diversion for salinity 

or to ensure long-term sustainability. Implementation priority of these features would be 

determined following additional analysis. 
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 Figure 2-37 Borrow Sites for Federally Identified Plan 
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Figure 2-38 Implementation Sequence for Federally Identified Plan 
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Figure 2-39 Construction Sequence for Federally Identified Plan 
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Figure 2-40. Restoration and Dredged Material Quantities
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Figure 2-41. Federally Identified Plan and Actions by Others 
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Figure 2-42. Federally Identified Plan and LACPR Recommendations 
3-1 June 2012 

3 SUMMARY OF COORDINATION, PUBLIC VIEWS AND 

COMMENTS 

3.1 COLLABORATIVE PLANNING

In accordance with EC 1105-2-409 (Planning in a Collaborative Environment) representatives of 

Federal and State agencies have been invited to be members of the Project Delivery Team 

(PDT) and the Interagency Team. Federal and State agencies are also involved through the 

NEPA process, with some agencies serving as official cooperating agencies and other agencies 

with official coordination and consultation roles. 

3.2 PROJECT DELIVERY TEAM (PDT) 

The PDT is a multi-disciplinary, multi-agency team responsible for the successful development 

and execution of all aspects of the study. The PDT is led by the USACE (New Orleans District) 

Senior Planner. USACE team members include Functional Team Leads (New Orleans and 

Mobile Districts) and USACE District Support Teams and Regional Integration Teams in 

Vicksburg, Atlanta, and Washington, D.C. The PDT also includes the Interagency Team, 

internal and external review teams, and Federal and State agency representatives. The PDT 

facilitates the interagency collaboration and coordination necessary for study execution. NEPA 

coordination with Federal and State agencies will occur through the PDT. Agency team 

members will provide guidance and recommendations throughout the planning process to 

assure the successful delivery of a quality product. The PDT will expand as necessary to 

include all necessary expertise for study execution. Some agency PDT members may also 

serve on the Interagency Team or as NEPA cooperating agencies. 

3.3 INTERAGENCY TEAM PARTICIPATION 

The Interagency Team is part of the PDT and is composed of resource agency representatives. 

The Interagency Team performs planning and technical assessments consistent with their 

agency responsibilities and expertise. The USACE (New Orleans District) Environmental 

Manager leads the Interagency Team. The Interagency Team is involved at all stages of the 

planning process, and will assist with the development, evaluation, and analysis of project 

alternatives. The Interagency Team will participate in the public information/involvement 

program, exchange study information, provide recommendations, and assist in the resolution of 

any interagency issues that may surface in the study process. Membership on the Interagency 

Team includes participants from both Louisiana and Mississippi State and Federal agencies as 

well as USACE members from New Orleans District, Mobile District and ERDC. The State of 

Mississippi‘s participation has been limited to the Violet, Louisiana Freshwater Diversion. 

3.3.1.1 Interagency Team Tasks 

The Interagency Team was assigned several responsibilities including the formulation of coastal 

restoration measures and alternatives; identification of screening criteria for evaluating the 

restoration plan; and quantification of the environmental impacts and benefits of those plans. 
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3-2 June 2012 

3.4 NEPA COOPERATING AGENCIES 

Cooperating Agencies (as defined under 40 CFR 1501.6) include: USFWS, NMFS, NRCS, EPA, 

and BOE (formerly MMS). Other participating agencies include LDEQ, LDWF, LDEQ, and 

MDMR. 

3.5 AGENCY COORDINATION 

Preparation of this restoration plan and environmental impact statement is coordinated with 

appropriate Congressional, Federal, state and local interests as well as environmental groups 

and other interested parties. 

A project kick-off meeting was held on October 8, 2008, to present the study authority, purpose, 

goals and objectives. Federal, state and local agencies from Mississippi as well as Louisiana 

participated in the discussions. 

Agencies were invited by email on August 27, 2008, and letter dated October 23, 2008, to 

participate in the study as cooperating agencies and provide a team member for the PDT as 

well as the Interagency Team. Informal agency coordination meetings will be held throughout 

the study to discuss issues and clarify information. 

3.6 PUBLIC INVOLVEMENT ACTIVITIES TO DATE 

3.7 STUDY WEBSITE 

The MRGO website, http://mrgo.gov, is dedicated to the many aspects of the MRGO, including 

the Ecosystem Restoration Feasibility Study. In addition to general information about the 

MRGO, it includes an interactive map, fact sheets, presentations, past documents, posters from 

public meetings, handouts from public meetings, as well as a calendar of events. 

This site was used to announce the NEPA scoping meetings as well as a record of the materials 

used and distributed at the meetings. In addition, the public was also able to use a comment 

button on the left navigation pane to submit comment relevant to scoping. 

The site is updated as new products and reports are released. 

3.8 STAKEHOLDER VISITS 

The success of USACE planning efforts depends, to a great extent, on establishing partnerships 

with stakeholders. Introducing the study is the first step in establishing partnerships and this 

effort is a key component. 

Members of the PDT made appointments with key stakeholders, which included public officials, 

members of non-governmental organizations, Federal partners, and landowners, to introduce 

the study through a series of short office visits conducted in advance of the launch of full-scale 

planning efforts. 
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3.9 NATIONAL ENVIRONMENTAL POLICY ACT SCOPING 

Scoping is a critical component of the overall public involvement program to solicit input from 

affected Federal, state, and local agencies, Indian Tribes, and interested stakeholders. The 

NEPA scoping process is designed to provide an early and open means of determining the 

scope of issues (problems, needs, and opportunities) to be identified and addressed in the Draft 

Environmental Impact Statement (DEIS). Scoping is the process used to: a) identify the affected 

public and agency concerns; b) facilitate an efficient DEIS preparation process; c) define the 

issues and alternatives that will be examined in detail in the DEIS; and d) save time in the 

overall process by helping to ensure that relevant issues are adequately addressed. Scoping is 

a process, not an event or a meeting; it continues throughout the EIS (draft and final) process 

and may involve meetings, telephone conversations, and/or written comments. 

A Notice of Intent to prepare a DEIS for the Mississippi River – Gulf Outlet (MRGO) Ecosystem 

Restoration Plan Study, Louisiana, was published on October 2, 2008, in the Federal Register

(Vol. 73, No. 192). 

A project kick-off meeting was held on October 8, 2008, and public scoping meetings were held 

on November 3 and 6, 2008. 

The scoping comment period began with the filing of the Notice of Intent and continues through 

release of the DEIS for public comment. Higher participation was received in Chalmette, LA with 

approximately 79 stakeholders attending. A total of 322 comments were received during the 

comment period; 257 comments were expressed at the scoping meetings and 65 written (letter, 

fax and email) and verbal comments were received during the comment period. 

The scoping comments were documented in a Scoping Report that describes the public‘s 

concerns about the restoration effort and strategies for restoration efforts. The Scoping Report 

is posted on the study website. All restoration strategies suggested during the scoping process 

were included in the initial array of alternatives. The Scoping Report is available under separate 

cover and is incorporated by reference in the associated EIS for this study. 

There were several reoccurring themes in the NEPA scoping comments. Five themes 

accounted for 52 percent of the comments received: 

 Use sediment diversions and placement for wetland restoration. 

 Restore the ecosystem to pre-disturbance/historical condition. 50 percent of these 

comments specifically mention cypress trees or forests. 

 Restoring the first line of hurricane defense for public safety is a priority. 

 Restore hydrology. 

 Implement/incorporate existing plans. 

3.10 STAKEHOLDER FORUMS 

USACE Central Wetlands Forum 

Over fifty participants attended an open public forum on Central Wetlands restoration projects 

and concepts at the New Orleans District Assembly Room on April 2, 2009. Attendees included 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 3: Summary of Coordination, Public Views and Comments 

3-4 June 2012 

non-governmental organizations, community members, local elected officials, academics, state 

and Federal agency representatives and USACE representatives. The purpose of the forum 

was to share information and identify data gaps, discuss the physical requirements for 

restoration; develop common restoration goals; discuss implementation alternatives; and 

determine what restoration measures should be evaluated as part of the MRGO Ecosystem 

Restoration Plan. Presentations were made by the MRGO Ecosystem Restoration Plan PDT, 

the New Orleans Sewerage and Waterboard, LSU School of Landscape Architecture, and the 

Environmental Defense Fund. 

USACE Recreation Forum 

A recreation forum was held at the USACE New Orleans District on September 28, 2009, to 

gather information in order to estimate the impact of the various restoration measures on the 

recreational activities of the study area, including fishing, boating, hunting, park or refuge 

access and usage, area-wide recreational access and usage. Invitations were sent to NGOs, 

various public agencies and private citizens involved in recreation (charterboat operators, 

hunting and fishing clubs, boat ramp operators, marinas, etc). 

USACE/Lake Pontchartrain Basin Foundation Ridge Restoration Workshop 

In partnership with the Lake Pontchartrain Basin Foundation, the USACE co-sponsored a 

coastal ridge restoration workshop on October 26, 2009. The purpose of the interdisciplinary 

workshop was to advance the understanding of these coastal restoration features. Issues 

addressed included: identifying measurable benefits of these features; practical development of 

design goals; construction techniques; ridge vegetation; and the high probability of cultural 

resource issues. Ridge restoration opportunities for the MRGO Ecosystem Restoration Plan 

were discussed at this workshop. Participants included members of the academic community, 

non-governmental organizations, engineers, planners, landscape architects, and other 

stakeholders. 

St. Bernard Parish Central Wetlands Workshop 

The St. Bernard Parish Government hosted a Central Wetlands Workshop on January 6, 2010. 

Members of the MRGO Ecosystem Restoration PDT participated in the workshop, as well as the 

District Commander, HPO Commander, and Deputy District Engineer for Project Management. 

Restoration priorities were identified and alternative implementation strategies were discussed 

at this workshop. 

3.11 NEW ORLEANS DISTRICT QUARTERLY NGO MEETINGS 

Quarterly meetings are held at the New Orleans District to update NGOs on the status of 

various projects in the area. Representatives of the team attend these meetings to answer 

questions regarding the study. 

3.12 SMALL GROUP MEETINGS 

The team regularly meets with several government and NGOs to provide study updates. The 

team also attends regular meetings of groups such as the St. Bernard Parish Coastal Zone 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 3: Summary of Coordination, Public Views and Comments 

3-5 June 2012 

Advisory Committee to discuss the study. Additionally, the team attends other meetings in the 

study area to be available to discuss the study. To date, the team has participated in the 

following meetings: 

Table 3-1. Small Group Meetings

Date Organization Topic

11-Feb-09 Lake Pontchartrain Basin Foundation Board MRGO Closure Construction and MRGO Ecosystem 

Restoration Feasibility Study

11-Mar-09 USACE IER 8-10 public meeting

18-Mar-09 State of Louisiana Violet, Louisiana Freshwater Diversion

23-Mar-09 Lake Pontchartrain Basin Foundation MRGO Ecosystem Restoration Feasibility Study Public

Involvement

25-Mar-09 St. Bernard Parish Coastal Zone Advisory Committee Monthly Meeting

20-May-09 Various NGOs Update on MRGO Ecosystem Restoration Study

21-May-09 Southeast Louisiana Flood Protection Authority - East Update on MRGO Channel Closure and Ecosystem 

Restoration Study

10-Jun-09 National Wildlife Federation Great Waters Summit Field Trip to Lower 9th Ward and 

Bayou Bienvenue

2-Jul-09 Environmental Defense Fund Central Wetlands Restoration Planning

6-Jul-09 State of Louisiana Violet, Louisiana Freshwater Diversion

8-Jul-09 New Orleans Sewer and Water Board Central Wetlands Wastewater Assimilation CIAP 

Project and Central Wetlands Restoration Planning

16-Jul-09 LCA Science Board MRGO Ecosystem Restoration Study

23-Jul-09 State of Louisiana

Lake Borgne Shoreline Protection Project PreApplication Meeting with MVN Regulatory Office

24-Jul-09 University of New Orleans MRGO Barrier Islands Meeting

29-Jul-09 St. Bernard Parish Coastal Zone Advisory Committee

6-Aug-09 Southeast Louisiana Flood Protection Authority - East Use of I-10 Twin Span bridge rubble for shoreline 

protection on the East Orleans Landbridge

7-Aug-09 Lake Pontchartrain Basin Foundation Update on MRGO Ecosystem Restoration Study

11-Aug-09 MRGO Must GO Coalition St. Bernard Community Forum on MRGO Ecosystem 

Restoration

15-Aug-09 Environmental Defense Fund Rebuilding the Bayou: Visions of Restoration in the 

Central Wetlands 

27-Aug-09 Delacroix Area Landowners Study alternatives and Right of Entry

4-Sep-09 US Fish and Wildlife Service Ecosystem modeling

8-Sep-09 Biloxi Marsh Lands Corporation Study alternatives and Right of Entry

15-Sep-09 National Wildlife Federation Sea Level Rise Considerations

28-Sep-09 Federal Resource Agencies Ecosystem modeling

30-Sep-09 St. Bernard Parish Coastal Zone Advisory Committee Monthly Meeting

15-Oct-09 Council on Environmental Quality Wetlands event at Central Wetlands associated with 

President Obama's visit 

27-Oct-09 St. Bernard Parish Government and Environmental 

Defense Fund Central Wetlands Restoration Plans

28-Oct-09 St. Bernard Parish Coastal Zone Advisory Committee Monthly Meeting

28-Oct-09 USACE IER 11 - Pontchartrain Seabrook Gate public meeting

29-Oct-09 USACE Industrial Canal Corridor public meeting

30-Oct-09 St. Bernard Parish Coastal Zone Advisory Committee CWPPRA Project Development and MRGO Study 

Coordination

13-Nov-09 St. Bernard Parish Coastal Zone Advisory Committee CWPPRA Project Development and MRGO Study 

Coordination

23-Nov-09 US Fish and Wildlife Service MRGO - Bayou Sauvage land access meeting

1-Dec-09 Governor's Advisory Commission on Coastal 

Activities Meeting

Commission meeting on coastal protection and 

restoration including brief on MRGO Ecosystem 

Restoration 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 3: Summary of Coordination, Public Views and Comments 

3-6 June 2012 

Table 3-1. Small Group Meetings

Date Organization Topic

2-Dec-09 The Nature Conservancy Tour of Central Wetlands

3-Dec-09 The Nature Conservancy Partnering meeting; covered oyster reef restoration in 

MRGO study area

4-Dec-09 Mister Go Must Go Coalition MRGO Ecosystem Restoration Study information 

exchange meeting

21-Dec-09 Mississippi Department of Marine Resources MRGO Study Update and Violet, Louisiana Freshwater 

Diversion Evaluation Status

21-Dec-09 City of New Orleans - Mayor‘s Office of 

Environmental Affairs Coastal Planning Meeting

6-Jan-10 St. Bernard Parish Government Central Wetlands Workshop

14-Jan-10 LCA Science Board Science Board Meeting

21-Jan-10 Southeast Louisiana Flood Protection Authority - East Board meeting - presentation on coastal restoration 

studies including MRGO Ecosystem Plan

1-Feb-10 St. Bernard Parish Coastal Zone Advisory Committee Special Meeting on Request to Open Bypass Channel 

Around the MRGO Closure Structure

8-Feb-10 State of Louisiana State restoration plan public meeting

10-Feb-10 Mississippi Department of Marine Resources Violet, Louisiana Freshwater Diversion and MRGO 

Restoration Plan

11-Feb-10 St. Bernard Parish Government Coordination with Parish Leaders on Violet, Louisiana 

Freshwater Diversion Neighborhood Focus Meeting

12-Feb-10 National Wildlife Federation IHNC surge barrier and MRGO wetlands site visit

22-Feb-10 US Fish and Wildlife Service USFWS - MRGO - Bayou Sauvage NWR Access 

Permit

22-Feb-10 USACE MRGO - Violet, Louisiana Freshwater Diversion 

neighborhood focus meeting

24-Feb-10 St. Bernard Parish Coastal Zone Advisory Committee Monthly meeting

23-Feb-10 USACE Coastal Restoration Town Hall Meeting

24-Feb-10 USACE Coastal Restoration Town Hall Meeting

25-Feb-10 USACE Coastal Restoration Town Hall Meeting

12-Mar-10 Tulane University and Lake Borgne Levee District IHNC Surge Barrier and MRGO Wetlands Tour

22-Feb-10 Lake Catherine Civic Association East Orleans Landbridge Features of MRGO 

Ecosystem Restoration Plan 

29-Mar-10 City of New Orleans - Mayor‘s Office of 

Environmental Affairs Orleans Parish Coastal Advisory Group

3.13 DRAFT REPORT 

The Draft Feasibility Report and EIS were released to the public following a Notice of Availability 

(NOA) that was published in the Federal Register on December 17, 2010. This notice provided 

a description of the proposed action including the project features, a point of contact to obtain 

more information regarding the DEIS, and a means of commenting on the DEIS and MRGO 

Ecosystem Restoration Plan Feasibility Report. 

Following the NOA, the USACE held three Public Meetings as an opportunity for the public, 

resources agencies, and elected officials to participate in the NEPA planning process, to provide 

input regarding the proposed restoration features, and to provide comments on the DEIS. Public 

hearings were held on January 20, 2011 in Chalmette, LA, on January 25, 2011 in Waveland, 

MS, and on February 8, 2011 in New Orleans, LA. 

The formal comment period began with the filing of the NOA on December 17, 2010 and was 

extended by the USACE twice due to special requests to provide additional time to comment, 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 3: Summary of Coordination, Public Views and Comments 

3-7 June 2012 

coupled with an overwhelming response. The final date for the acceptance of comments was 

established as March 5, 2011, resulting in an overall 78-day comment period. 

Verbal comments received at each of the Public Hearings were made part of the Public Hearing 

transcript and were included within the comment database. During the comment period, over 

31,400 individual commenters provided written comments (via email, letter, and fax) and/or 

verbal comments on one recurring subject matter alone – Support of Plan Elements. The large 

comment response was primarily attributed to approximately 31,270 individual commenters 

associated with 4 non-government organizations that submitted multiple form letters, with each 

set being identical in content. These form letters represented 99.5 percent of the comments 

received on the most common recurring comment theme. Individuals associated with one 

organization alone submitted 10,325 identical representing 33 percent of the total comments 

received on this specific subject matter. 

As comments were received, each was read and entered into a database. Names, 

organizations, addresses, and emails were all entered. Comments were initially identified under 

―major topics‖ and then by ―recurring themes‖ to gain an understanding of key issues. Major 

topics included the diversion; sediment; additional plan features; and funding; just to name a 

few. Since each commenter generally commented on more than one issue, the comments were 

categorized among the 64 recurring themes or similar issues. All comments were reviewed to 

determine significance of each comment regardless of the recurrence of the comment. 

Appendix Y of the FEIS presents summarizes the comments received during the comment 

period and the responses to comments for recurring comment themes. 

3.14 US FISH AND WILDLIFE SERVICE RECOMMENDATIONS 

The TSP will benefit the fish and wildlife resources of the MRGO Ecosystem Restoration area by 

providing freshwater, nutrients, and sediments, and restoring ridge, swamp and marsh habitats in the 

study area thus facilitating increasing organic production, increasing biological productivity, increasing 

habitat diversity, and reducing wetland loss. Approximately 37,980 Average Annual Habitat Units 

(AAHUs) and 31,930 net acres of fresh/intermediate, brackish, and saline marsh, swamp and ridge 

habitats would benefit by the proposed project at the end of the project life given an intermediate sea 

level rise scenario. The Service supports implementation of the TSP and respectfully request the 

following fish and wildlife recommendations be implemented concurrently with project construction: 

1. Regarding the barrier island component of the MRGO Ecosystem Restoration; the Service 

recommends, with support from NMFS and LDWF, the selection of a barrier island 

component be a part of the TSP. The Service feels the design and evaluation of the barrier 

island alternatives was sufficient to warrant selection, though further engineering would be 

required prior to construction. Breton Island is a National Wildlife Refuge, managed by the 

Service and is of National importance. Recent scientific investigations (Lavoie, D, ed., 2009; 

Thomson et al., 2009) demonstrate the long-term impacts to this important refuge as a result 

of the MRGO channel. Therefore, the Service recommends amelioration of the areal loss of 

Breton Island due to the construction and maintenance of the MRGO channel should be 

appropriately addressed in the TSP. The Corps should contact the Service regarding a 

compatibility determination, Wilderness Act provisions and special use permits that may be 

necessary to conduct activities on Breton NWR. The Corps is encouraged to establish and 

continue coordination with the Service until construction of any project feature is complete 
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Final Feasibility Report 3: Summary of Coordination, Public Views and Comments 

3-8 June 2012 

and prior to any subsequent maintenance. Points of contacts for the Service are: Kenneth 

Litzenberger, Project Leader for the Service‘s Southeast National Wildlife Refuges and Neil 

Lalonde (985) 882-2000, Refuge Manager for the Breton Island NWR. 

USACE Response. The USACE recognizes the importance of the barrier island chain and the need 

for restoration; however, we believe that additional study is warranted before a sustainable 

restoration plan can be recommended for construction. Given the uncertainties of conditions at this 

time due to the oil spill and recovery efforts, USACE would seek additional authority for further study 

before recommending a viable restoration plan. The Corps will continue to coordinate with the 

Service throughout the study process. 

2. The Corps should contact the Service regarding a compatibility determination, and special 

use permits that may be necessary to conduct activities on Bayou Sauvage NWR. The Corps 

should establish and continue coordination with the Service until construction of any project 

feature is complete and prior to any subsequent maintenance. Points of contacts for the 

Service are: Kenneth Litzenberger, Project Leader for the Service‘s Southeast National 

Wildlife Refuges and Neil Lalonde (985) 882-2000, Refuge Manager for the Breton Island 

NWR. 

USACE Response. The Corps will continue to coordinate with the Service throughout the study 

process. 

3. The final recommendations for the MRGO Ecosystem Restoration Plan include additional 

analysis, design and implementation of the Violet Freshwater Diversion as authorized by 

WRDA 2007 Section 3083. This means the Violet Diversion will be funded and constructed 

under a different authorization than the authorization for the MRGO Ecosystem Restoration 

Plan. The Service recommends any additional study, design, and implementation include the 

Service and other resource agency involvement. In addition if the diversion location or other 

aspects of the diversion change significantly from what was analyzed in the MRGO 

Ecosystem Restoration Plan, the Service recommends the Sediment and Nutrient Diversion 

model (SAND2) and Wetland Value Assessment benefits analysis be revised to reflect the 

changes. 

USACE Response. Concur. The Service and other resource agencies would be included in any 

additional study, design and implementation of the Violet, Louisiana Freshwater Diversion. 

4. The Service recommends the operational plans for the Violet Diversion be evaluated to 

include more flexibility of flow (flows between 1000cfs and 7000cfs) to achieve optimal habitat 

conditions favorable to nearby intermediate marsh and to bald cypress germination, growth, 

and reproduction by controlling depth and duration of inundation and salinity levels. As the 

operational plan for the Violet Diversion is further developed, future hydrological and fisheries 

(i.e., CASM) modeling, and updated habitat assessments (i.e., Wetland Value Assessments) 

should be conducted. 

USACE Response. The USACE plans to adaptively manage the freshwater flows from the diversion 

to promote a sustainable swamp habitat and fresh/intermediate marsh in the Central Wetlands. 

Additional hydrologic modeling and aquatic modeling would be conducted during additional studies of 

the diversion. The diversion would be operated in coordination with other diversions planned in the 

watershed to achieve the goals and objectives of the study. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 3: Summary of Coordination, Public Views and Comments 

3-9 June 2012 

5. The Service recommends, with support from NMFS and LDWF, the diversion operational 

plan be developed in a way to avoid or minimize adverse impacts to marine fisheries and 

Essential Fish Habitat (EFH) while maximizing freshwater and nutrient input to the extent 

practicable to meet habitat objectives. 

USACE Response. Concur. 

6. The Service and LDWF recommend salinity meters be placed in appropriate locations to 

assist in determining when target salinities are met. 

USACE Response. Seven hourly recorders will be deployed to measure salinity, temperature, water 

level and turbidity at three sites located along the MRGO / Lake Borgne Landbridge, three sites in the 

Biloxi Marsh, and one site located in the western Mississippi Sound.

7. The Service recommends the diversion be adaptively managed to enhance surrounding 

wetlands, that habitat switching (as a result of re-introduced river water) is allowed to occur in 

a manner that is not detrimental or destructive to the ecological processes, and that the 

diversion allows for draw down periods sufficient for cypress regeneration and cypress 

growth. 

USACE Response. The diversion would be adaptively managed to achieve the study goals and 

objectives and minimize adverse effects to the extent practicable. 

8. The Service recommends, with support from LDWF, a comprehensive examination of the 

river and all existing and proposed diversions to coordinate their operation and ensure that 

their operation will maximize their restoration capabilities. The ongoing Mississippi River 

Hydrodynamic and Delta Management Study could be utilized to address this issue. 

USACE Response. USACE supports the need for a comprehensive plan to coordinate the water 

needs of the basin. The Mississippi River Hydrodynamic and Delta Management Study is anticipated 

to address those needs with full participation by natural resource agencies. 

9. The Service recommends, with support from NMFS and LDWF, establishment of a 

committee similar to review the operation and monitoring and adaptive management results 

of the Violet, Louisiana Freshwater Diversion and when necessary, provide 

recommendations regarding any future operational and maintenance changes. The Service 

and other natural resource agencies are amenable to participate on this committee. 

USACE Response. Concur. An adaptive management planning team, including members from 

other natural resource agencies would be established for recommending project and program 

adaptive management actions. 

10. The large quantity of borrow material proposed to be taken from Lake Borgne, which is 

designated Gulf sturgeon critical habitat, for the TSP may have an adverse effect to fisheries, 

EFH, and the threatened Gulf sturgeon by: 1) alteration in water bottom substrate habitat: 2) 

direct removal of benthos from a large area which may (at least temporarily) reduce food 

availability for fishery organisms; 3) other sessile resources, such as oysters could be 

affected; and 4) by continually moving the dredge, the resuspended sediments will take 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 3: Summary of Coordination, Public Views and Comments 

3-10 June 2012 

longer to settle and could prolong the periods of high turbidity associated with dredging 

operations. The Service recommends, with support from NMFS and LDWF, careful 

consideration be given to the affects of taking all borrow, including monitoring for benthos and 

water quality, from Lake Borgne and consideration should be give to obtaining borrow from 

other ―outside‖ sources, such as the Mississippi River, and adjacent bays, and offshore 

areas. Over the project life, search for borrow from outside sources should continue as 

alternative sources may become economically feasible or as new advances in technology 

become available. 

USACE Response. Concur. Additional analyses on borrow areas has been conducted and the 

borrow plan modified, in coordination with NMFS, to minimize adverse impacts to fisheries, EFH, and 

the threatened Gulf sturgeon including additional borrow sources. The corps will continue to consider 

sources outside of Lake Borgne throughout the study process.

11. The NMFS is responsible for consultations regarding impacts to the Gulf sturgeon and its 

critical habitat for the MRGO Ecosystem Restoration project. Therefore, please contact Dr. 

Stephania Bolden (727/824-5312) in St. Petersburg, Florida, for information concerning that 

species and its critical habitat. Should the proposed project directly or indirectly affect the Gulf 

sturgeon or its critical habitat in Louisiana, further consultation with that office will be 

necessary.

USACE Response. the NMFS has been a member of the habitat evaluation team throughout the 

planning process. The Corps will continue to coordinate with both NMFS offices.

12. The Service, with support from NMFS and LDWF, recommends the Lake Borgne borrow 

plan should initially specify monitoring three different depths of borrow sites for a 

minimum of two-years post dredging and prior to continued excavation. The Service 

recommends monitoring of water quality parameters are included in the MAMP in order 

to assess if anoxic or hypoxic conditions occur. If anoxia is a problem at 10 feet below 

the existing sediment surface with a +/- 5 foot tolerance, then the borrow sites will have 

to be dug shallower and other borrow source options explored to minimize impacts to 

estuarine water bottoms and EFH. The Service, NMFS, and LDWF recommend a 

summary of the Monitoring and Adaptive Management Plan for borrow be included in the 

Feasibility Study or Environmental Impact Statement. The Service, NMFS, and LDWF 

also recommend that all borrow sites be at least 1,000 feet from the shoreline to help 

avoid increasing shoreline erosion via increased wave height. 

USACE Response. All borrow sites would be excavated at a minimum of 3,000 feet from the 

Lake Borgne shoreline. Three test sites would be dredged and monitored to determine the 

maximum depth of future borrow pits. If anoxia is a problem at 15 feet below water surface, then 

the borrow sites would be dug shallower and other borrow source options would be explored. 

This is part of the adaptive management plan. A brief summary of this test pit monitoring plan is 

included in the borrow section of the EIS. 

13. The proposed borrow areas in Lake Borgne do include private leases as well as public oyster 

seed grounds. LDWF manages the public seed grounds and should be consulted before final 

borrow locations are determined. 

USACE Response. Concur. Borrow sites would be excavated at a minimum of 3,000 feet from the 

Lake Borgne shoreline. LDWF is an active member of the habitat evaluation team. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 3: Summary of Coordination, Public Views and Comments 

3-11 June 2012 

14. The Service recommends that all shoreline protection features include one fish dip every 

1,000 feet (ft) constructed to a 25 ft bottom width to the pre-project elevation. On a case by 

case basis the 1,000 ft distance can be adjusted, in consultation with NMFS, to incorporate 

existing water exchange points. 

USACE Response. Concur. During the detail design phase for each feature, USACE would closely 

coordinate with USFWS and NMFS before implementation of these measures. 

15. The Service and NMFS recommends the retention dikes constructed for swamp and marsh 

creation and nourishment areas be gapped and degraded within three years of use if they 

have not naturally degraded on their own. Please coordinate gapping and degrading efforts 

with the Service and NMFS. 

USACE Response. Concur. The dike features would be mechanically breached or degraded within 

three years of construction, if natural degradation has not sufficiently removed the earthen material. 

16. The Service and LDWF recommend a buffer of at least 500 feet be placed around existing 

hard bottom and oyster leases to minimize impacts to those resources. 

USACE Response. Non-concur. Designated borrow areas are estimated larger than needed for 

each feature to ensure that adequate material is available in the event that environmental or cultural 

resources are discovered during construction that require avoidance. Hard bottom areas would be 

avoided because they are considered preferred habitat for the Gulf sturgeon. Borrow sites would be 

located a minimum of 3,000 feet from the Lake Borgne shoreline to avoid existing oyster leases to 

the maximum extent practicable. However, in the southern lobe proposed borrow sites do overlap 

existing oyster leases and these oyster leases would be impacted by dredging acitivity. 

17. The Monitoring and Adaptive Management Plan, as it is further developed, should be 

provided to the Service, NMFS, and LDWF for continued review, comment, and input. 

USACE Response. Concur. 

18. If a proposed project feature is changed significantly or is not implemented within one year of 

the Endangered Species Act consultation letter, we recommend that the Corps reinitiate 

coordination with the Service and NMFS to ensure that the proposed project would not 

adversely affect any Federally listed threatened or endangered species or their critical habitat. 

USACE Response. Concur. 

19. The proposed Violet Freshwater Diversion structure off the Mississippi River has the 

potential to entrain pallid sturgeon, that effect should be addressed in the diversions 

future planning studies. Should the proposed project directly or indirectly affect the pallid 

sturgeon or its habitat, further consultation with this office will be necessary. 

USACE Response. Concur. The Corps would coordinate with the Service during the future planning 

studies of the diversion. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 3: Summary of Coordination, Public Views and Comments 

3-12 June 2012 

20. Avoid adverse impacts to nesting bald eagles, gulls, terns, and/or black skimmers, wading 

birds, and brown pelicans through the careful design of project features and timing of 

construction. A qualified biologist should inspect the proposed work area for the presence of 

undocumented nesting colonies and bald eagles during the nesting season (i.e., September 

15 through March 31 for brown pelican, September 1 through February 15 for wading bird 

nesting colonies, September 16 through April 1 for colonies containing nesting gulls, terns, 

and/or black skimmers, and October through mid-May for bald eagles). 

 To minimize disturbance to colonies containing nesting wading birds (i.e., herons, 

egrets, night-herons, ibis, and roseate spoonbills), anhingas, and/or cormorants, all 

activity occurring within 1,000 feet of a rookery should be restricted to the non-nesting 

period (i.e., September 1 through February 15, exact dates may vary within this 

window depending on species present). 

 For colonies containing nesting brown pelicans, all activity occurring within 2,000 feet 

of a rookery should be restricted to the non-nesting period (i.e., September 15 through 

March 31). Nesting periods vary considerably among Louisiana‘s brown pelican 

colonies so it is possible that this activity window could be altered based upon the 

dynamics of the individual colony. 

 For colonies containing nesting gulls, terns, and/or black skimmers, all activity 

occurring within 650 feet of a rookery should be restricted to the non-nesting period 

(i.e., September 16 through April 1, exact dates may vary within this window 

depending on species present). 

 If a bald eagle nest is discovered within or adjacent to the proposed project area, then 

an evaluation must be performed to determine whether the project is likely to disturb 

nesting bald eagles. That evaluation may be conducted on-line at: 

http://www.fws.gov/southeast/es/baldeagle. Following completion of the evaluation, 

that website will provide a determination of whether additional consultation is 

necessary and those results should be forwarded to this office. 

USACE Response. Concur. 

21. Land clearing associated with project features should be conducted during the fall or winter to 

minimize impacts to nesting migratory birds, when practicable. 

USACE Response. The USACE will to the extent practicable implement land clearing activities 

during the fall and winter. When this is not feasible, the USACE would coordinate with the USFWS 

and conducted surveys for nesting colonies and bald eagles prior to initiating work activities. 

22. Further detailed planning of project features (e.g., Design Documentation Report, 

Engineering Documentation Report, Plans and Specifications, or other similar 

documents) should be coordinated with the Service and other State and Federal natural 

resource agencies, and shall be provided an opportunity to review and submit 

recommendations on all work addressed in those reports. 

USACE Response. Concur 

23. A report documenting the status of implementation, maintenance, and adaptive management 

measures should be prepared every three years by the managing agency and provided to 

the Corps, the Service, NMFS, U.S. Environmental Protection Agency (EPA), Louisiana 

Department of Natural Resources (LDNR), Office of Coastal Protection and Restoration 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 3: Summary of Coordination, Public Views and Comments 

3-13 June 2012 

(OCPR), and LDWF. That report should also describe future management activities, and 

identify any proposed changes to the existing management plan.

USACE Response. Concur. The adaptive management team would be the responsible party for 

preparation of this report. 

24. The Service recommends minimizing impacts to marsh from marsh buggy activities. Options 

to achieve that minimization include limiting the repetitive use of a route or to build temporary 

boardwalks over marsh where feasible and then backfilling the boardwalk area if needed. In 

areas with large marsh creation features that have minimal access routes, such as the inner 

Terre Aux Bouef marsh features, the Service recommends that work begin at the farthest 

location and proceed to the outer edges of the site to minimize the amount of damage. 

USACE Response. Concur. USACE plans to utilize boardwalks over existing marsh to reduce 

marsh impacts and backfill impacted marsh when the boardwalks are removed. USACE would 

restore the farthest location of Bayou Terre aux Boeufs and work to the outer edges to minimize 

adverse impacts to existing and newly restored marsh. Marsh buggies would be required to avoid 

repetitive use of the same tracts to reduce marsh impacts. Any impacts to existing marsh would be 

backfilled to the extent practicable.

25. The Service recommends the CASM model should be updated to incorporate conditions from 

the oil spill in the adaptive management plan. This model should also use the corrected 

assumptions. 

USACE Response. Funding and time constraints limit the ability to re-run any models at this stage. 

An update of the CASM model could potentially take place during PED phase. 

26. Due to the significant acreage of marsh that will be accessed for swamp and marsh 

creation/nourishment, the Service request the Corps quantify the estimated acreage of 

flotation and construction access canal impacts to shallow open water habitat. 

USACE Response. Concur. Additional analyses on flotation access and construction access will be 

conducted during the detailed planning, engineering and design phase following approval of the 

recommended plan. 
4-1 June 2012 

4 FEDERALLY IDENTIFIED PLAN 

4.1 FEDERALLY IDENTIFIED PLAN (FIP) 

As the District Engineer, I have considered the environmental, social, and economic effects, the 

engineering feasibility, and the comments received from other resource agencies and the public 

during the MRGO Ecosystem Restoration Study effort and plan formulation. Based upon the 

sum of this information, I am recommending for implementation the MRGO Ecosystem 

Restoration Plan that includes the highest priority actions from among those considered during 

plan formulation. I am convinced that the MRGO Ecosystem Restoration Plan would restore 

areas affected by the MRGO, begin to reverse the current trend of degradation of Louisiana‘s 

coastal ecosystem, support Nationally significant resources, provide a sustainable and diverse 

array of fish and wildlife habit, provide infrastructure protection, and make progress towards a 

more sustainable ecosystem. 

The plan I am recommending includes features recommended for construction (contingent upon 

the identification of a non-Federal sponsor), features that may be constructed if conditions for 

ecological success and long term sustainability exist, features recommended for additional 

study, and a Monitoring and Adaptive Management Plan (MAMP). These recommendations are 

subject to modifications at the discretion of the Commander, HQUSACE. 

Plan C is the FIP and NER plan for this study because it is the lowest cost alternative that meets 

all of the study objectives and provides a complete plan to restore the structure and function of 

the Lake Borgne ecosystem as described in sections 2.8 and 2.9. Other plans were evaluated 

that provide additional benefits, but the increases in costs were not considered reasonable 

given the relative outputs. Plan C is cost-effective, and maximizes the opportunities to achieve 

the objectives of the study for the least cost. The incremental costs associated with Plan C are 

considered reasonable for the significance of the outputs achieved. 

The components of the FIP would produce 37,980 Annual Average Habitat Units (AAHUs) and 

restore and protect approximately 57,472 acres of habitat. The plan includes the following: 

 A freshwater diversion at or near Violet, Louisiana; 

 14,123 acres of fresh and intermediate marsh; 

 32,511 acres of brackish marsh; 

 10,318 acres of cypress swamp; 

 466 acres of saline marsh; 

 54 acres of Bayou La Loutre ridge habitat; 

 71 miles of shoreline protection in Lake Borgne, along the MRGO, and in the Biloxi 

Marsh, including 5.8 miles of oyster reef restoration in the Biloxi Marsh; 

 2 recreation features. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-2 June 2012 

Based on October 2011 Price Levels, the Project First Cost of the FIP is estimated at $2.9 

billion. The total cost of the Monitoring and Adaptive Management Plan is $190 million, including 

costs for potential adaptive management actions. The operation, maintenance, repair, 

replacement, and rehabilitation (OMRR&R) costs for plan features are estimated at $427 million. 

4.2 RECOMMENDATIONS 

Recommendations are divided into tiers by the level of uncertainty regarding conditions for ecological 

success and long-term sustainability including the need for additional study. 

 Tier 1 includes features that have been developed to a feasibility level of detail and are 

not dependent on a freshwater diversion. Tier 1 features are recommended for 

construction through the WRDA 2007 Section 7013 authority upon the identification of a 

non-Federal sponsor. 

 Tier 2 includes features with feasibility level detail that are dependent upon salinity 

conditions but may be sustainable without the implementation of a freshwater diversion. 

If future conditions and further analysis indicate that favorable conditions for ecological 

success and long term sustainability exist (as defined in the adaptive management 

plan3), then these projects may be constructed. Tier 2 features would be constructed 

through the WRDA 2007 Section 7013 authority upon the identification of a non-Federal 

sponsor. 

 Tier 3A includes further study of the Violet, Louisiana Freshwater Diversion under the 

WRDA 2007 Section 3083 authority. The non-Federal cost-share responsibilities for the 

Violet, Louisiana Freshwater Diversion would be consistent with the 75 percent/25 

percent Federal/non-Federal cost share identified in Section 3083 of WRDA 2007, 

together with such other items of cost-share responsibilities as may be identified in the 

Feasibility Report for the project, as approved by the decision of the Chief of Engineers. 

Presently, as identified in the 1984 Chief‘s Report for Mississippi and Louisiana 

Estuarine Areas Freshwater Diversion to Lake Pontchartrain and Mississippi Sound 

Feasibility Study, the 25 percent non-Federal share of the cost of the design and 

implementation of the Violet, Louisiana Freshwater Diversion project is allocated 80 

percent to the State of Louisiana and 20 percent to the State of Mississippi. It is not 

anticipated that this allocation will change as a result of completing the feasibility study 

for the project; however, if it does, the change in allocation will be addressed in the 

study, as approved by the decision of the Chief of Engineers.

 Tier 3B includes any features that are dependent on freshwater diversion, and features 

in Tier 2 that future conditions and further analyses indicate are not sustainable. 

Subsequent to the completion of Tier 3A, Tier 3B features would be constructed through 

the WRDA 2007 Section 7013 authority upon the identification of a non-Federal sponsor. 

Table 4-1 provides the FIP feature descriptions by tier and Figure 4-1 depicts the FIP. 

 

3

 Average annual salinity: fresh marsh: <1.1 parts per thousand (ppt); intermediate marsh: <4.1 ppt; brackish marsh: <8.3 ppt, and swamp <4.0. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-3 June 2012 

Table 4-1. Implementation Table1

Measure Description

TIER 1 RECOMMENDED FOR CONSTRUCTION

(CONTINGENT UPON IDENTIFICATION OF NON-FEDERAL SPONSOR)

Total Investment Cost: $1,308,000,000

Total Average Annual Costs: $54,591,000

Total MAMP Costs: $104,131,000

Total OMRR&R Costs: $209,503,000

Average Annual OMRR&R Costs: $3,141,000

Total Benefits: 2,414 AAHUs

October 2011 Price Levels

LS1 45,000 linear feet (8.5 miles) of shoreline protection beginning at the terminus of the Bayou 

Dupre supplemental shoreline project, extending around Proctor Point to the West of Shell 

Beach supplemental funding shoreline protection.

MRGO1 3,850 feet (0.75 miles) of new foreshore protection between MRGO miles 56.6 and 57.4. This 

stone protection feature is embedded within the limits of MRGO7.

MRGO6 8,132 linear feet (1.5 miles) of new, non-continuous foreshore protection between MRGO miles 

36.0 and 34.4, immediately east of the existing stone closure of the MRGO. MRGO6 ties into an 

existing foreshore dike immediately downstream. 

BS1 Approximately 50,637 linear feet (9.5 miles) of protection along the southeast shore of Lake 

Borgne from the Biloxi Marsh Shoreline Protection Project (PO-72) south of Point aux 

Marchettes extending north to Malheureax Point.

BS2 Approximately 30,750 linear feet (5.8 miles) of artificial oyster reef development between Eloi 

Point and the mouth of Bayou La Loutre.

ES1 20,530 linear feet (3.8 miles) of shoreline protection from the south shore of Lake Pontchartrain 

to the existing Bayou Chevee shoreline protection feature.

ES2 30,750 (5.8 miles) linear feet of shoreline protection in Lake Pontchartrain between Chef 

Menteur Pass and The Rigolets.

ES3 69,900 linear feet (13.2 miles) of foreshore protection along Lake Borgne between Alligator 

Point and The Rigolets.

BR1 Approximately 54.1 acres of ridge restoration on the south bank of Bayou La Loutre. 400,000 

cubic yards of silty sand material would be required.

EM2 1,095 acres of marsh nourishment on Hog Island, located between the west and east mouth of 

the West Pearl River using 1.3 million cubic yards of dredged material.

EM3 861 acres of marsh restoration and 180 acres nourishment bounded by Highway 433, Little 

Lagoon, Salt Bayou and Highway 90 using 4.1 million cubic yards of material.

EM4 2,625 acres of marsh restoration and 1,455 acres of nourishment bounded by Salt Bayou, the 

West Pearl River, the Rigolets, and Highway 80. Approximately 9.2 million cubic yards of 

material would be required.

HM1 757 acres of marsh restoration and nourishment of 973 located in the Hopedale area using 4.5 

million cubic yards of dredged material.

TM1 798 acres of marsh restoration and 223 acres of marsh nourishment south of Bayou La Loutre 

in the Terre aux Boeufs area using 3.8 million cubic yards of material.

TM2 770 acres of marsh restoration and 3,396 acres of marsh nourishment in the vicinity of Lake 

Ameda. Approximately 8.8 million cubic yards of material would be required.

TM7 2,255 acres of marsh restoration and 2,144 acres of adjacent marsh nourishment to the east of 

Bayou Terre aux Boeufs using 12.4 million cubic yards of material.
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-4 June 2012 

Table 4-1. Implementation Table1

Measure Description

TM8 1,511 acres of marsh restoration on the east side of Bayou Terre aux Boeufs in the vicinity of 

Delacroix. 9.7 million cubic yards of material would be required.

MRGO2 One time repair of approximately 21,630 linear feet (4.1 miles) of existing foreshore protection 

between Mile 44.5 and 40 of the MRGO.

MRGO3 One time repair of approximately 26,650 linear feet (5 miles) of existing foreshore protection 

between approximately Mile 56 to 51 of the MRGO.

MRGO4 One time repair of approximately 11,770 linear feet (2.2 miles) of existing retention dike

between MRGO Miles 36.6 to 37.1 and MRGO Miles 33.9 to 32.9.

SHELL 

BEACH

Recreation feature to be constructed following repair of MRGO2. 343 lf of boardwalk into the 

MRGO, 805 lf of shoreline boardwalk, 5 picnic shelters (two handicap accessible), interpretive 

signage, bathrooms, parking, solar lighting and plantings.

TIER 2 RECOMMENDED FOR CONSTRUCTION IF CONDITIONS FAVORABLE FOR ECOLOGICAL 

SUCCESS AND SUSTAINIBILITY ARE DOCUMENTED

Total Investment Cost: $390,232,700

Total Average Annual Costs: 15.531,700

Total MAMP Costs: $45,701,000

Total OMRR&R Costs: $18,318,000

Average Annual OMRR&R Costs: $251,700

Total Benefits: 5,694 AAHUs

October 2011 Price Levels

CC4-A 400 acres of cypress restoration in the Bienvenue Triangle. Approximately 2.6 million cubic 

yards of material to be obtained from Mississippi River.

CC4 (Sites 

2,3,4)

1,065 acres of cypress swamp restoration in the open water areas adjacent to the Forty Arpent 

Levee north of Paris Road using 7.8 million cubic yards of material.

CM2 795 acres of marsh restoration and 190 acres of marsh nourishment north of Paris Road using 

approximately 4.7 million cubic yards of material.

CM5 245 acres of marsh restoration and 70 acres of nourishment in the area north of Bayou 

Bienvenue and Paris Road using 1million cubic yards of material.

LM4 225.5 acres of marsh restoration and nourishment of 54.8 acres in the portion of the Golden 

Triangle bordered by the GIWW, the IHNC Surge Barrier, and the MRGO. Approximately 1.2 

million cubic yards of material are required. 

BAYOU

REC

Recreation feature associated with CC4-A. 100 linear feet of platform, 995 linear feet of 

boardwalk into the swamp, 4 picnic shelters, interpretive signage, bathrooms, parking, solar 

lighting and vegetative plantings in the Bienvenue Triangle.

TIER 3 RECOMMENDED FOR FURTHER STUDY

Estimated Total Investment Costs for Tier 3B: $1,194,150,000

Estimated Total MAMP Costs for Tier 3B: $36,561,000

Estimated Total OMRR&R Costs for Tier 3B: $198,806,000

Estimated Average Annual OMRR&R Costs: $2,618,000

Estimated Total Benefits for Tier 3B: 29,872 AAHUs

Estimated costs do not include construction of the Violet, Louisiana Freshwater Diversion.

October 2011 Price Levels

Tier 3A
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-5 June 2012 

Table 4-1. Implementation Table1

Measure Description

VIOLET The Violet, Louisiana Freshwater Diversion as authorized in WRDA 2007 Section 3083. A 

freshwater diversion would enhance and sustain the benefits of the FIP. Additional study would 

be carried out under WRDA 2007 Section 3083 and subject to the cost-share provisions in that 

authority.

Tier 3B

EM1 1,175 acres of marsh restoration and 2,830 acres nourishment bounded by Lake Pontchartrain, 

Chef Menteur, and the levee using 8.1 million cubic yards of material.

LM1 3,253 acres of marsh restoration and nourishment of 1,064 acres in the Golden Triangle, south 

of the IHNC Surge Barrier using 14.3 million cubic yards of material.

LM2 225 acres of marsh restoration and 2,628 acres of marsh nourishment in the area between 

Proctor Point and the MRGO using 4.5 million cubic yards of material.

LM3 911 acres of marsh restoration and 950 acres nourishment in South Lake Borgne north of Lena 

Lagoon in the area bounded by the lake, Bayou St. Malo, MRGO, and Doulets Canal using 6.4 

million cubic yards of material.

BM1 8,000 acres of marsh nourishment along the south shore of Lake Borgne using 11 million cubic 

yards of material.

MRGO5 202 acres of marsh restoration using 3.0 million cubic yards of material located behind 13,685 

linear feet (2.5 miles) of vinyl sheet pile wall to establish the shoreline.

MRGO7 110 acres of marsh restoration using 1.65 million cubic yards of material adjacent to 9,700 

linear feet (1.8 miles) of vinyl sheet pile wall. 

MRGO8 236 acres of marsh restoration using 3.5 million cubic yards of material adjacent to 17,785 

linear feet (3.3 miles) of vinyl sheet pile wall and 14,225 linear feet (2.6 miles) of new foreshore 

protection between approximate channel miles 51.0 and 48.3.

CM1 1,240 acres of marsh nourishment south of Paris Road between cypress restoration feature 

CC3 and the Chalmette Loop Levee using 1.5 million cubic yards of material.

CM3 300 acres of marsh restoration and 215 acres of marsh nourishment north of Bayou Dupre and 

south of MRGO using 1.6 million cubic yards of borrow material.

CM4 97.5 acres of marsh restoration and 128.5 acres of marsh nourishment south of Bayou Dupre 

using 600,000 cubic yards of dredged material.

CC1 1,020 acres of swamp restoration and 935 acres nourishment north of the existing Violet Canal 

along the Forty Arpent levee using 6.0 million cubic yards of material.

CC2 250 acres of cypress swamp restoration and 250 acres of swamp nourishment to the northeast 

of CC1 using 1.7 million cubic yards of material.

CC3 370 acres of swamp restoration and 790 acres nourishment along the Forty Arpent Levee south 

of Paris Road using 3.7 million cubic yards of material.

CC5 1,120 acres of swamp restoration and 1,550 acres nourishment south of the Violet Canal along 

the Forty Arpent Levee and the Chalmette Loop Levee. 7.8 million cubic yards of borrow 

material would be required.

CC6 2,568 acres of swamp nourishment in the Central Wetlands southwest corner. 5.2 million cubic 

yards of borrow material would be required.

Note 1. Measures are listed in order of priority for Tiers 1 and 2 as described in detail in Section 2.13.
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-6 June 2012 

Figure 4-1. Federally Identified Plan 

4.2.1 Monitoring and Adaptive Management 

The Monitoring and Adaptive Management Plan (MAMP) for the study describes a systematic 

approach to reduce and address some of the uncertainties associated with the study. The 

MAMP for this study has developed decision criteria, also referred to as AM ecological success 

criteria, to determine if and when AM opportunities should be implemented. These criteria are 

described in Table 4-2 and are based on the monitoring of indicators. Indicators are applicable 

to all tiers. 

Cost estimates have been developed for the MAMP and are presented in Table 4-3. For cost 

estimating purposes, the maximum cost-shared period of monitoring was assumed for all features. 

Some projects, such as marsh restoration, may require less than ten years of post-construction 

monitoring to determine ecological success. Once ecological success has been established, 

monitoring would cease. Other features, such as ridge restoration and cypress swamp restoration, 

may require longer monitoring periods to determine ecological success. The need for additional 

monitoring would be assessed at the end of the cost-shared period, and any additional monitoring 

would be a 100% non-Federal responsibility. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-7 June 2012 

Table 4-2. Adaptive Management Threshold and Trigger Matrix 

Indicator Threshold Ecological Success 

Criteria

Response Options 

Salinity Threshold set by 

Snedden and Steyer, 

in review- Figure 4

Trigger set if marsh 

types change 2 classes 

(fresh to brackish) 

across years or if 

swamp/fresh meet 

salinity threshold

Alter freshwater input. Potential options 

include: bank gapping, salinity barriers, 

diversion operation, or freshwater 

management through other projects in 

the area potentially including Borgne 

Barrier, Bonne Carre Spillway, Small 

Diversion at Convent Blind River, 

Maurepas Swamp Diversion

Plant Mortality 

– emergent 

marsh and 

(plantings)

Threshold set by 

marsh collapse expert 

panel; (plantings –

70% survival at year 

1)-Table 3

Trigger set at low range 

of marsh collapse 

thresholds

Control salinity and or inundation. 

Potential methods include nourishment to 

enhance elevation, diversion operation 

or other method of altering freshwater 

input into the system, and managed 

habitat switching (replant with vegetation 

type suitable for observed conditions- i.e. 

replant previous brackish marsh area with 

saline marsh species types)

Land/Water 

Ratio

Threshold set by 

WVA

Trigger set if land lost 

episodic (marsh 

dieback) 

Enhance elevation

Elevation Threshold set by high 

inundation depth

Trigger set when 

elevation by marsh type 

less than reference

Enhance elevation

Oyster 

Recruitment

Threshold set on 

sufficient oyster reef 

development to 

protect identified 

marsh

Presence/absence of 

oyster settlement at 2-3 

years

Seed with juveniles/stock adults

Water Quality TBD by NMFS 

consultation in PED

TBD by NMFS 

consultation in PED

Evaluate options for increasing 

freshwater input and hydrologic 

restoration measures such as bank 

gapping and salinity barriers

Table 4-3 Summary of MAMP Costs for the MRGO Ecosystem Restoration Project 

(October 2011 Price Levels)

Category Tier 1 Tier 2 Tier 3B Project Total for 

MAMP

Set-up and Implementation of the MAMP for the Project

Monitoring 

Planning and 

Management

$510,349 $231,977 $185,581 $927,907 

Data Collection $11,478,487 $3,586,244 $2,868,995 $17,933,727 

Database 

Management

$487,733 $221,697 $177,357 $886,787 

AM Planning 

Program Set-up

$1,052,700 $478,500 $382,800 $1,914,000 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-8 June 2012 

Table 4-3 Summary of MAMP Costs for the MRGO Ecosystem Restoration Project 

(October 2011 Price Levels)

Category Tier 1 Tier 2 Tier 3B Project Total for 

MAMP

Management of 

AM Program

$438,625 $199,375 $159,500 $797,500 

Assessment $412,308 $187,413 $149,930 $749,650 

Decision Making $271,948 $123,613 $98,890 $494,450 

Stakeholder 

Program Set-up

$437,604 $199,375 $159,500 $796,479 

Stakeholder 

Involvement 

During 

Construction

$175,450 $79,750 $63,800 $319,000 

Stakeholder 

Involvement Post 

Construction

$175,450 $79,750 $63,800 $319,000

Potential AM Actions

Potential AM 

Action-Wetland 

Nourishment

$86,935,475 $39,516,125 $31,612,900 $158,064,500 

Potential AM 

Action- Cultural 

Data Recovery

$1,754,500 $797,500 $638,000 $3,190,000 

TOTAL $104,130,628 $45,701,318 $36,561,054 $186,393,000 

Cost Share 

Federal-65% $67,684,908 $29,705,856 $23,764,685 $121,155,450

Non-Federal35% $36,445,720 $15,995,461 $12,796,369 $65,237,550 

4.3 PROJECT COST 

4.3.1 Cost and Schedule Risk Analysis 

A formal risk analysis study was performed to develop contingency for the total project cost. The risk 

analysis was performed to determine a true contingency cost required for cost estimating based on 

the risk items associated with the project. The contingencies are determined by qualifying and 

quantifying all potential cost risks and producing a frequency spectrum and probability range for 

applied risk costs. The cost contingency is within the 80-percent confidence interval determined by 

this statistical analysis. The potential cost risks identified indicate how to avoid unforeseen escalation 

of project costs and may be used as a valuable tool in all phases of project study, design, and 

construction planning and estimation. 

Within the risk analysis, it was noted that the project scope for this effort is fairly confident in design 

and quantities. Primary factors contributing to cost and schedule risk include: revisions to the borrow 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-9 June 2012 

plan/borrow availability (due to the uncertainties associated with final pit depths resulting from water 

quality analyses, unidentified cultural resources and pipelines, and borrow availability for adaptive 

management); uncertainties associated with freshwater diversion implementation; uncertainties 

related to funding stream; hydraulic cutterhead dredge availability; and fuel cost variation. 

The quantitative impacts of risk factors on project plans are analyzed using professional judgment, 

empirical data, and analytical techniques. Risk factor impacts are quantified using probability 

distributions (density functions). The probabilistic distribution functions are used to describe the 

characteristic population (tendencies) of the risk factor inputs. The following elements were 

addressed in the risk factor quantification process: maximum possible value; minimum possible 

value; most likely value (the statistical mode), if applicable; nature of the probability density function 

used to approximate risk factor uncertainty; mathematical correlations between risk factors; and 

affected cost estimate and schedule elements. 

It was recognized that the various features carry differing degrees of risk as related to cost, schedule, 

design complexity, and design progress. A risk register was developed that records risk concerns 

and potential impacts to the current cost and schedule estimates. The risk register supports 

decisions related to event likelihood, impact, and the resulting risk levels for each risk event used to 

develop cost and schedule contingencies. 

The cost contingency is calculated as the difference between the 80-percent confidence interval cost 

forecast and the base cost estimate. Each option-specific contingency is then allocated based on the 

dollar-weighted relative risk of each feature. Standard deviation is used as the feature-specific 

measure of risk for contingency allocation purposes. A larger portion of the cost contingency is 

allocated to features with relatively higher estimated cost uncertainty using this approach. 

For schedule contingency analysis, the option schedule contingency is calculated as the difference 

between the 80-percent confidence interval option duration forecast and the base schedule duration. 

These contingencies are used to calculate the time value of monetary impacts of project delays that 

are included in the presentation of total cost contingency. The resulting time value of money, or 

added risk escalation, is then added into the contingency amount to reflect the USACE standard for 

presenting the ―total project cost‖ for the fully funded project amount. 

4.3.2 Federally Identified Plan Costs 

Table 4-4 provides the Project First Costs (Constant Dollar Costs at the current price level) for the FIP. 

These scheduled costs follow the construction implementation schedule provided in the Engineering 

Appendix for this study. 

Table 4-4. Project First Costs for FIP (In October 2011 $1,000)

Cost Category Cost Contingency Total Federal 

Responsibility

Non-Federal 

Responsibility

Lands And Damages $75,888 $23,172 $99,060 $99,060

Relocations $0 $0 $0

Fish & Wildlife 

Facilities (Plantings) $109,532 $26,945 $136,477 $88,710 $47,766 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-10 June 2012 

Table 4-4. Project First Costs for FIP (In October 2011 $1,000)

Fish & Wildlife 

Facilities Adaptive 

Management

$90,754 $53,998 $144,752 $94,088 $50,663 

Recreation Facilities $3,566 $877 $4,443 $2,221 $2,221 

Beach 

Replenishment $1,783,352 $438,705 $2,222,056 $1,543,396 $678,659 

Planning, 

Engineering & Design

(PED)

$78,675 $19,354 $98,030 $63,719 $34,310 

PED Adaptive 

Management $22,063 $13,128 $35,191 $22,874 $12,316 

Construction 

Management $107,894 $26,542 $134,435 $87,382 $47,052 

Construction 

Management 

(Adaptive 

Management)

$6,083 $3,620 $9,703 $6,306 $3,396 

Baseline Total Cost: $2,277,807 $606,340 $2,884,147 $1,908,700 $975,446 

Table 4-5. Project First s for Tier 1 (In October 2011 $1,000)

Cost Category Total Federal 

Responsibility

Non-Federal 

Responsibility

Ecosystem Restoration 

Construction $1,147,768 $ 746,049 $ 401,719

MAMP $104,131 $67,685 $36,446

Recreation Facilities $2,786 $1,393 $1,393

TOTAL $1,254,685 $815,127 $439,558 

Table 4-6. Project First Costs for Tier 2 (In October 2011 $1,000)

Cost Category Total Federal 

Responsibility

Non-Federal 

Responsibility

Ecosystem Restoration 

Construction 

$322,823 $193,694 $112,988

MAMP $45,701 $29,706 $15,995

Recreation Facilities $2,006 $1,003 $1,003

TOTAL $370,530 $224,403 $129,986

Table 4-7. Project First Costs for Tier 3B (In October 2011 $1,000)

Cost Category Total Federal 

Responsibility

Non-Federal 

Responsibility

Ecosystem Restoration 

Construction 

$1,076,597 $699,788 $376,809

MAMP $36,561 $23,765 $12,796

Recreation Facilities $0 $0 $0

TOTAL $1,113,157 $723,553 $389,605 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-11 June 2012 

Table 4-8.

Incremental Cost Schedule – Tentatively Selected Plan (October 2011 Price Levels, $1,000‘s)

Item FY14 FY15 FY16 FY17 FY18 FY19 FY20 FY21 Sub-Totals

01 Real 

Estate $8,255 $8,255 $8,255 $8,255 $8,255 $8,255 $8,255 $8,255 $66,040 

06 Fish /

Wildlife $19,849 $2,225 $0 $0 $19,748 $9,465 $5,170 $8,657 $65,114 

06 Fish

/Wildlife /

AM $0 $0 $0 $0 $0 $0 $0 $0 $0 

14 

Recreation 

Fac $1,861 $0 $0 $0 $2,583 $0 $0 $0 $4,444 

17 Beach 

Rep $278,553 $183,965 $16,159 $76,104 $414,537 $133,614 $173,399 $180,430 $1,456,761 

30 PED $12,197 $8,412 $965 $3,511 $18,544 $4,596 $7,062 $9,196 $64,483 

31 PED AM

31 S&A $17,743 $11,418 $1,287 $5,025 $21,840 $6,704 $10,513 $11,121 $85,651 

31 S&A 

AM

Annual 

Total $338,458 $214,275 $26,666 $92,895 $485,507 $162,634 $204,399 $217,659 $1,742,493 

Item FY22 FY23 FY24 FY25 AM Total

01 Real 

Estate $8,255 $8,255 $8,255 $8,255 $99,060

06 

Fish/Wildli

fe $26,018 $0 $17,506 $27,838 $136,476

06 

Fish/Wildli

fe/AM $0 $0 $0 $0 $144,752 $144,752

14 

Recreation 

Fac $0 $0 $0 $0 $4,444

17 Beach 

Rep $151,044 $18,088 $287,597 $308,567 $2,222,057

30 PED $7,050 $942 $12,155 $13,399 $98,029

31 PED AM $35,191 $35,191

31 S&A $10,057 $1,302 $17,881 $19,543 $134,434

31 S&A 

AM $9,703 $9,703

Annual 

Total $241,650 $215,015 $238,480 $110,601 $189,646 $2,884,146

4.4 COST SHARING AND AGENCY RESPONSIBILITIES 

I further recommend Federal and Non-Federal Sponsor responsibilities and cost sharing 

requirements as set forth in the following paragraphs. 

Ecosystem Restoration Plan, Tiers 1, 2 and 3B: Before the ecosystem restoration plan for Tiers 

1, 2 and 3B can be implemented, a non-Federal sponsor would need to be identified and a cost 

sharing agreement executed in accordance with the cost-sharing provisions outlined below. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-12 June 2012 

Despite extensive discussions with the State of Louisiana, a non-Federal sponsor has not been 

identified for the MRGO Ecosystem Restoration plan. The non-Federal share will bear 35 

percent of the costs of implementing the ecosystem restoration plan and 50 percent of 

recreation facilities. The non-Federal sponsor is responsible for providing all lands, easements, 

rights-of-way, utility or public facility relocations, and dredged or excavated material disposal 

areas and performance of all relocations required for the project (LERRDs), and 100 percent of 

the costs of operation, maintenance, repair, rehabilitation, and replacement (OMRR&R). The 

value of LERRDs will be credited toward the non-Federal cost share. 

Mississippi River-Gulf Outlet Ecosystem Restoration project: 

Federal implementation of the recommended project for Tier 1, Tier 2 and Tier 3B would be 

subject to the non-Federal sponsor agreeing to comply with applicable Federal laws and 

policies, including but not limited to: 

Provide 35 percent of total ecosystem restoration costs as further specified below: 

a. Provide 35 percent of total ecosystem restoration costs as further specified below: 

1. Provide the non-Federal share of design costs allocated by the Government to ecosystem 

restoration in accordance with the terms of a design agreement entered into prior to 

commencement of design work for the ecosystem restoration features; 

2. Provide, during the first year of construction, any additional funds necessary to pay the full 

non-Federal share of design costs allocated by the Government to ecosystem restoration; 

3. Provide all lands, easements, and rights-of-way, including those required for relocations, 

the borrowing of material, and the disposal of dredged or excavated material; perform or 

ensure the performance of all relocations; and construct all improvements required on 

lands, easements, and rights-of-way to enable the disposal of dredged or excavated 

material all as determined by the Government to be required or to be necessary for the 

construction, operation, and maintenance of the ecosystem restoration features; 

4. Provide, during construction, any additional funds necessary to make its total contribution 

for ecosystem restoration equal to 35 percent of total ecosystem restoration costs; 

b. Provide 50 percent of total recreation costs as further specified below: 

1. Provide the non-Federal share of design costs allocated by the Government to recreation 

in accordance with the terms of a design agreement entered into prior to commencement 

of design work for the recreation features; 

2. Provide, during the first year of construction, any additional funds necessary to pay the full 

non-Federal share of design costs allocated by the Government to recreation; 

3. Provide all lands, easements, and rights-of-way, including those required for relocations, 

the borrowing of material, and the disposal of dredged or excavated material; perform or 

ensure the performance of all relocations; and construct all improvements required on 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-13 June 2012 

lands, easements, and rights-of-way to enable the disposal of dredged or excavated 

material all as determined by the Government to be required or to be necessary for the 

construction, operation, and maintenance of the recreation features; 

4. Provide, during construction, any additional funds necessary to make its total contribution 

for recreation equal to 50 percent of total recreation costs; 

c. Provide, during construction, 100 percent of the total recreation costs that exceed an amount 

equal to 10 percent of the Federal share of total ecosystem restoration costs; 

d. Provide the non-Federal share of that portion of the costs of mitigation and data recovery 

activities associated with historic preservation, that are in excess of 1 percent of the total amount 

authorized to be appropriated for the project; 

e. Not use funds provided by a Federal agency under any other Federal program, to satisfy, in 

whole or in part, the non-Federal share of the cost of the project unless the Federal agency that 

provides the funds determines that the funds are authorized to be used to carry out the project; 

f. Prevent obstructions or encroachments on the project (including prescribing and enforcing 

regulations to prevent such obstructions or encroachments) such as any new developments on 

project lands, easements, and rights-of-way or the addition of facilities which might reduce the 

outputs produced by the ecosystem restoration features, hinder operation and maintenance of 

the project, or interfere with the project‘s proper function; 

g. Not use project or lands, easements, and rights-of-way required for the project as a wetlands 

bank or mitigation credit for any other project; 

h. Keep the recreation features, and access roads, parking areas, and other associated public use 

facilities, open and available to all on equal terms; 

i. Comply with all applicable provisions of the Uniform Relocation Assistance and Real Property 

Acquisition Policies Act of 1970, Public Law 91-646, as amended (42 U.S.C. 4601-4655), and the 

Uniform Regulations contained in 49 CFR Part 24, in acquiring lands, easements, and rights-ofway required for construction, operation, and maintenance of the project, including those 

necessary for relocations, the borrowing of materials, or the disposal of dredged or excavated 

material; and inform all affected persons of applicable benefits, policies, and procedures in 

connection with said Act; 

j. For so long as the project remains authorized, operate, maintain, repair, rehabilitate, and replace 

the project, or functional portions of the project, including any mitigation features, at no cost to the 

Federal Government, in a manner compatible with the project‘s authorized purposes and in 

accordance with applicable Federal and State laws and regulations and any specific directions 

prescribed by the Federal Government; 

k. Give the Federal Government a right to enter, at reasonable times and in a reasonable manner, 

upon property that the non-Federal sponsor owns or controls for access to the project for the 

purpose of completing, inspecting, operating, maintaining, repairing, rehabilitating, or replacing 

the project; 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-14 June 2012 

l. Hold and save the United States free from all damages arising from the construction, operation, 

maintenance, repair, rehabilitation, and replacement of the project and any betterments, except 

for damages due to the fault or negligence of the United States or its contractors; 

m. Keep and maintain books, records, documents, or other evidence pertaining to costs and 

expenses incurred pursuant to the project, for a minimum of 3 years after completion of the 

accounting for which such books, records, documents, or other evidence are required, to the 

extent and in such detail as will properly reflect total project costs, and in accordance with the 

standards for financial management systems set forth in the Uniform Administrative 

Requirements for Grants and Cooperative Agreements to State and Local Governments at 32 

Code of Federal Regulations (CFR) Section 33.20; 

n. Comply with Section 221 of Public Law 91-611, Flood Control Act of 1970, as amended (42 

U.S.C. 1962d-5), and Section 103 of the Water Resources Development Act of 1986, Public 

Law 99-662, as amended (33 U.S.C. 2213), which provides that the Secretary of the Army shall 

not commence the construction of any water resources project or separable element thereof, 

until the non-Federal sponsor has entered into a written agreement to furnish its required 

cooperation for the project or separable element; 

o. Comply with all applicable Federal and State laws and regulations, including, but not limited to: 

Section 601 of the Civil Rights Act of 1964, Public Law 88-352 (42 U.S.C. 2000d) and 

Department of Defense Directive 5500.11 issued pursuant thereto; Army Regulation 600-7, 

entitled "Nondiscrimination on the Basis of Handicap in Programs and Activities Assisted or 

Conducted by the Department of the Army‖; and all applicable Federal labor standards 

requirements including, but not limited to, 40 U.S.C. 3141- 3148 and 40 U.S.C. 3701 – 3708 

(revising, codifying and enacting without substantial change the provisions of the Davis-Bacon 

Act (formerly 40 U.S.C. 276a et seq.), the Contract Work Hours and Safety Standards Act 

(formerly 40 U.S.C. 327 et seq.), and the Copeland Anti-Kickback Act (formerly 40 U.S.C. 276c 

et seq.); 

p. Perform, or ensure performance of, any investigations for hazardous substances that are 

determined necessary to identify the existence and extent of any hazardous substances 

regulated under the Comprehensive Environmental Response, Compensation, and Liabil-ity Act 

(CERCLA), Public Law 96-510, as amended (42 U.S.C. 9601-9675), that may exist in, on, or 

under lands, easements, or rights-of-way that the Federal Government determines to be 

required for construction, operation, and maintenance of the project. However, for lands that the 

Federal Government determines to be subject to the navigation servitude, only the Federal 

Government shall perform such investigations unless the Federal Government provides the nonFederal sponsor with prior specific written direction, in which case the non-Federal sponsor shall 

perform such investigations in accordance with such written direction;

q. Assume, as between the Federal Government and the non-Federal sponsor, complete financial 

responsibility for all necessary cleanup and response costs of any hazardous substances 

regulated under CERCLA that are located in, on, or under lands, easements, or rights-of-way 

that the Federal Government determines to be required for construction, operation, and 

maintenance of the project; 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-15 June 2012 

r. Agree, as between the Federal Government and the non-Federal sponsor, that the non-Federal 

sponsor shall be considered the operator of the project for the purpose of CERCLA liability, and 

to the maximum extent practicable, operate, maintain, repair, rehabilitate, and replace the project 

in a manner that will not cause liability to arise under CERCLA. 

Violet, Louisiana Freshwater Diversion Project: 

 The non-Federal cost-share responsibilities for the Violet, Louisiana Freshwater Diversion 

would be consistent with the 75 percent/25 percent Federal/non-Federal cost share identified in 

Section 3083 of WRDA 2007, together with such other items of cost-share responsibilities as 

may be identified in the Feasibility Report for the project, as approved by the decision of the 

Chief of Engineers. Presently, as identified in the 1984 Chief‘s Report for Mississippi and 

Louisiana Estuarine Areas Freshwater Diversion to Lake Pontchartrain and Mississippi Sound 

Feasibility Study, the 25 percent non-Federal share of the cost of the design and 

implementation of the Violet, Louisiana Freshwater Diversion project is allocated 80 percent to 

the State of Louisiana and 20 percent to the State of Mississippi. It is not anticipated that this 

allocation will change as a result of completing the feasibility study for the project; however, if it 

does, the change in allocation will be addressed in the study, as approved by the decision of the 

Chief of Engineers.

4.5 OPERATION AND MAINTENANCE 

The OMRR&R for this plan shall be a non-Federal sponsor responsibility. OMRR&R includes renourishment and invasive species control for marsh and swamp features. The first event for 

brackish marsh was determined by the calendar year of predicted marsh collapse in the WVA. 

Marsh collapse is when the observed condition of a defined area loses a significant amount of 

marsh through erosion or inundation resulting in a  ̳collapse‘ where the remaining marsh is lost 

at an accelerated rate. The predicted marsh collapse in brackish marsh habitat occurs in 

calendar year 2058 (or target year 44) for this study under the medium RSLR condition. Target 

year 39 (calendar year 2053) is used for OMRR&R to precede the predicted marsh collapse 

event in target year 44 for brackish marsh. 

The amount of marsh lost that would need to be replaced during an O&M event was calculated 

by taking the difference of the peak amount of marsh created and or nourished and the amount 

of marsh left in a particular target year. For brackish marsh habitat, the target year 39 is used. 

For swamp habitat, target year 35 is used. 

For shoreline protection features, a maintenance event is assumed to be needed in year 5 as 

the majority of the settlement occurs fairly quickly after construction. Additional maintenance 

events would occur at 10 year intervals after the first maintenance event. Since the initial 

construction for existing features MRGO 2, MRGO 3 and MRGO 4 is a maintenance event, the 

initial lift at year 5 would not be needed. These would be maintained at 10 year intervals after 

the initial event. Table 4-10 summarizes OMRR&R costs by tier. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-16 June 2012 

Table 4-9.

OMRR&R Costs by Tier (October 2011 Price Levels)

Marsh and Swamp 

Re-nourishment

Invasive Species 

Control

Shoreline 

Protection Total

Tier 1 $136,582,000 $5,671,000 $67,250,000 $209,503,000

Tier 2 $17,352,000 $966,000 $0 $18,318,000

Tier 3B $194,686,000 $4,120,000 $4,062,500 $198,806,000

FIP TOTAL $426,627,000

4.6 INSTITUTIONAL REQUIREMENTS 

The WRDA of 1986 comprehensively reestablished and redefined the Federal interest in water 

resources development and, in recognition of the limitations on Federal financial resources, 

instituted requirements for proportionately greater non-Federal cost-sharing in USACE projects. 

4.7 MRGO ECOSYSTEM RESTORATION PLAN: VIEWS OF THE STATE 

OF LOUISIANA 

The State of Louisiana has been involved in the development of the ecosystem restoration plan. 

The plan has been formulated to be consistent with Louisiana's Comprehensive Master Plan for 

a Sustainable Coast (Master Plan). For example, the 2007 State Master Plan specifically 

recommended restoration of wetlands and swamps in the Central Wetlands and Golden 

Triangle areas, which is included in the FIP. The Master Plan was developed with intensive 

public input and was unanimously adopted by the Louisiana Legislature. 

In a letter dated August 12, 2010, the State of Louisiana expressed ―its continuing support of the 

Mississippi River Gulf Outlet Ecosystem Restoration Project‖ and declared ―full support for the 

Mississippi River Gulf Outlet Ecosystem Restoration Program" (See Figure 4-2). It states that 

―the State of Louisiana and the Coastal Protection and Restoration Authority wholeheartedly 

endorse this and other Corps' hurricane protection and ecosystem restoration efforts...‖

However, this letter also expresses the State of Louisiana‘s view that the Mississippi River Gulf 

Outlet Ecosystem Restoration Project should be undertaken at full Federal expense and that the 

state should have no financial obligations with respect to the Mississippi River Gulf Outlet 

Ecosystem Restoration Project. 

Implementation of the ecosystem restoration plan would require identification of a non-Federal 

sponsor and execution of a cost sharing agreement. As of the date of this report, USACE has 

not received a letter of intent from the State of Louisiana to serve as the non-Federal sponsor to 

cost share in implementation of the ecosystem restoration plan. The USACE will continue to 

coordinate with the State of Louisiana in the development and implementation of the restoration 

plan. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-17 June 2012 

4.8 VIOLET, LOUISIANA FRESHWATER DIVERSION PROJECT, 

VIEWS OF THE STATE OF MISSISSIPPI AND THE STATE OF 

LOUISIANA 

Section 3083 of WRDA 2007, citing the Corps of Engineers feasibility study entitled ―Mississippi and 

Louisiana Estuarine Areas: Freshwater Diversion to Lake Pontchartrain Basin and Mississippi 

Sound‖ dated 1984, authorizes the Corps of Engineers to design and implement a project for the 

diversion of freshwater at or near Violet, Louisiana for the purposes of reducing salinity in the western 

Mississippi Sound, enhancing oyster production and promoting the sustainability of coastal wetlands. 

Section 3083 identifies the State of Louisiana and the State of Mississippi as non-Federal sponsors 

for the non-Federal 25% share of the design and implementation of the Violet, Louisiana Freshwater 

Diversion project. Although Section 3083 does not expressly allocate the increment of the nonFederal 25 percent cost share attributable to each sponsor, the cited 1984 Feasibility Study and 

subsequent Report of the Chief of Engineers dated May 1986, stipulates that each State will be 

responsible for the recreational features built within its respective jurisdiction and that the State of 

Louisiana shall bear 80 percent of the Non-Federal Sponsor‘s 25 percent cost share and that the 

remaining 20 percent of the non-Federal 25 percent cost share shall be borne by the State of 

Mississippi. 

The State of Mississippi, along with the State of Louisiana, has been actively involved in the 

development of the Violet, Louisiana Freshwater Diversion project. The final recommendations for 

the plan addressed in this report include a recommendation for additional analysis, design and 

implementation of the Violet, Louisiana Freshwater Diversion as authorized by WRDA 2007 Section 

3083. This is consistent with MSCIP and the State of Mississippi's desire to freshen the Mississippi 

Sound and sustain oyster production. 

In a letter dated September 20, 2010 the Mississippi Department of Marine Resources (MDMR) 

declared its full support for the Freshwater, Louisiana Diversion project (See Figure 4-3) and its 

understanding of its non-Federal cost sharing obligation. The State of Mississippi‘s letter also states 

its desire that the USACE, to the fullest extent possible, seek full Federal funding for the project. .

Before the Violet, Louisiana Freshwater Diversion can be implemented, the USACE will require a 

letter of intent to serve as the non-Federal sponsor and a self-certification of the non-Federal 

sponsor's financial capability from both the State of Mississippi and the State of Louisiana, including a 

clear statement of each State‘s willingness and ability to provide its required cost share and other 

items of local cooperation for the project, as described in this report. Prior to the commencement of 

construction by USACE, Federal law requires that both States execute a binding written agreement 

wherein they agree to provide all of the non-Federal obligations for the construction, operation, 

maintenance, repair, rehabilitation and replacement of the Violet, Louisiana Freshwater Diversion 

project. USACE will continue to coordinate with the State of Mississippi and the State of Louisiana in 

the development and implementation of the Violet, Louisiana Freshwater Diversion project. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-18 June 2012 

Figure 4-2. State of Louisiana Letter 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-19 June 2012 

Figure 4-3. State of Mississippi Letter 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-20 June 2012 

4.9 REAL ESTATE 

4.9.1 Estates 

It is Corps of Engineers policy to acquire fee simple title for ecosystem restoration projects. Two 

reasons for such requirement is to reduce the risk that incompatible uses on project land will 

occur after project construction, and to ensure that ownership rights vested in the project are 

clear and enforceable. It should be noted that this is a planning document and the necessary 

estates are subject to change dependent upon project needs; in the event that the project would 

require the acquisition of an estate that is not proposed herein, a revised real estate plan will be 

prepared. It is the opinion of the project delivery team that the estates proposed herein provide 

sufficient rights to the Government to construct the project and also protect the interests of the 

Government. 

4.9.2 Navigation Servitude 

The Navigation Servitude will not be asserted for ecosystem restoration projects and therefore 

will not apply. 

4.9.3 Fee (Standard Estate) 

It is recommended that for Ecosystem Restoration projects that in order to protect project 

benefits, Fee (including mineral rights) be acquired from the private landowners. 

“The fee simple title (described in Schedule A), is subject, however, to existing easements for 

public roads and highways, public utilities, railroads and pipelines.” 

It is assumed that all borrow material will be obtained from sites owned by the State or the 

Federal government. Therefore, only a Grant of Particular Use may need to be obtained for 

borrow areas. 

4.9.4 Project Partnership 

After extensive discussions with the State of Louisiana, a non-Federal sponsor has not been 

identified for implementation of the MRGO Ecosystem Restoration Plan authorized by Section 7013 

of WRDA 2007 (Tiers 1, 2 and 3B). For design and implementation of the Violet, Louisiana 

Freshwater Diversion project, Section 3083 of WRDA 2007 identifies the State of Louisiana and the 

State of Mississippi as a joint non-Federal sponsors. The obligations of the non-Federal sponsor for 

both projects includes a requirement that the sponsor provide all real estate interests required for 

each project implemented under the plan, i.e., all lands, easements, rights of way, relocations, and 

any other interests, including suitable borrow and dredged or excavated material disposal areas, and 

performing all necessary relocations (LERRDs). The non-Federal cost-share responsibilities for the 

Violet, Louisiana Freshwater Diversion would be consistent with the 75 percent/25 percent 

Federal/non-Federal cost share identified in Section 3083 of WRDA 2007, together with such other 

items of cost-share responsibilities as may be identified in the Feasibility Report for the project, as 

approved by the decision of the Chief of Engineers. Presently, as identified in the 1984 Chief‘s Report 

for Mississippi and Louisiana Estuarine Areas Freshwater Diversion to Lake Pontchartrain and 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-21 June 2012 

Mississippi Sound Feasibility Study, the 25 percent non-Federal share of the cost of the design and 

implementation of the Violet, Louisiana Freshwater Diversion project is allocated 80 percent to the 

State of Louisiana and 20 percent to the State of Mississippi. It is not anticipated that this allocation 

will change as a result of completing the feasibility study for the project; however, if it does, the 

change in allocation will be addressed in the study, as approved by the decision of the Chief of 

Engineers.

In accordance with Section 103(c)(4) of WRDA 1986, development of the recreation facilities 

proposed as part of the FIP would be cost-shared 50 percent Federal and 50 percent nonFederal. The non-Federal sponsor is responsible for providing any separable lands required for 

public access, health, and safety, with crediting for the value of those lands toward the 

sponsor's 50 percent share for the recreation facilities. Operation, maintenance, replacement, 

repair and rehabilitation (OMRR&R) costs are the responsibility of the non-Federal sponsor. 

4.9.5 Real Estate Cost Estimates 

Acquisition Costs: The total Real Estate costs for the FIP are $99,060,000 (October 2011 Price 

Levels). The gross appraisal for LERRDs is on file and is being reviewed at the Division level. 

Refer to Exhibit B in the Real Estate Plan for the charts of accounts estimate. 

Based on preliminary research, it is assumed that approximately 1900 private ownerships are 

impacted by the FIP and will require the acquisition of new right of way. Also in the project area 

are lands owned by U.S. Fish and Wildlife Services: the Bayou Sauvage National Wildlife 

Refuge. Any areas owned by the State of Louisiana will require a Special Use Permit to be 

obtained. 

4.9.6 Public Law (PL) 91-646 Relocations 

All acquisition of private property for this project will be done in accordance with the provisions 

of Public Law 91-646, as amended. It is anticipated at this time that the project will not displace 

any persons, businesses or farms. 

4.9.7 Relocation of Facilities 

Due to the nature of the work to be done, it is assumed that there will not be any facility/utility 

relocations. Any existing oil and gas well sites will be avoided by the project footprint. 

4.9.8 Acquisition Schedules 

Following is an estimated acquisition schedule for the entire plan: 

Task Task Duration 

Obtain all title information 3 years

Obtain all mapping information 3 years

Obtain all appraisals 3 years

Negotiate and issue all rights-of-entry 8 years

Condemnation 3 years

 Activities would be done concurrently. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-22 June 2012 

4.9.9 Landowner Concerns 

During public scoping meetings, most landowners were in favor of the project given the direct 

benefits it would provide to the ecosystem; however, the public has not yet had the opportunity 

to provide comments in regards to fee acquisition instead of the originally proposed nonstandard estates. It is our opinion that most landowners will not be in favor of selling fee 

interests. We expect that many acquisitions will be accomplished through condemnation. 

4.10 FEDERALLY IDENTIFIED PLAN SUMMARY 

The federally identified plan would restore and protect approximately 57,472 acres of habitat in the 

study area, including 14,123 acres of fresh and intermediate marsh; 32,511 acres of brackish marsh; 

10,318 acres of cypress swamp; 466 acres of saline marsh; and 54 acres of ridge habitat. The 

federally identified plan also identifies 71 miles of shoreline protection including 5.8 miles of oyster 

reef restoration. The federally identified plan is the National Ecosystem Restoration Plan. 

Based on 2012 price levels, the Project First Cost of the FIP is estimated at $2.9 billion (October 

2011 Price Levels). The Project First of Tiers 1 and 2 is estimated at $1.3 billion and $325 

million, respectively (October 2011 Price Levels). The Project First Cost of the Monitoring and 

Adaptive Management Plan (MAMP) is $190 million, including costs for potential adaptive 

management actions (October 2011 Price Levels). The Project First Cost of the MAMP for Tiers 

1 and 2 are $104 million and $46 million, respectively (October 2011 Price Levels). The 

operation, maintenance, repair, replacement, and rehabilitation (OMRR&R) costs for the FIP is 

$427 million (October 2011 Price Levels). The OMRR&R costs for plan features in Tiers 1 and 2 

are estimated at $210 and $18 million, respectively (October 2011 Price Levels). 

Recommendations are divided into tiers by the level of uncertainty regarding conditions for ecological 

success and long-term sustainability, including the need for additional study. 

 Tier 1 includes features that have been developed to a feasibility level of detail and are 

not dependent on a freshwater diversion. Tier 1 features are recommended for 

construction through the WRDA 2007 Section 7013 authority upon the identification of a 

non-Federal sponsor. 

 Tier 2 includes features with feasibility level detail that are dependent upon salinity 

conditions but may be sustainable without the implementation of a freshwater diversion. 

If future conditions and further analysis indicate that favorable conditions for ecological 

success and long term sustainability exist (as defined in the adaptive management plan), 

then these projects may be constructed. Tier 2 features would be constructed through 

the WRDA 2007 Section 7013 authority upon the identification of a non-Federal sponsor. 

 Tier 3A includes further study of the Violet, Louisiana Freshwater Diversion under the 

WRDA 2007 Section 3083 authority. The non-Federal cost-share responsibilities for the 

Violet, Louisiana Freshwater Diversion would be consistent with the 75 percent/25 

percent Federal/non-Federal cost share identified in Section 3083 of WRDA 2007, 

together with such other items of cost-share responsibilities as may be identified in the 

Feasibility Report for the project, as approved by the decision of the Chief of Engineers. 

Presently, as identified in the 1984 Chief‘s Report for Mississippi and Louisiana 

Estuarine Areas Freshwater Diversion to Lake Pontchartrain and Mississippi Sound 

Feasibility Study, the 25 percent non-Federal share of the cost of the design and 

implementation of the Violet, Louisiana Freshwater Diversion project is allocated 80 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 4: Federally Identified Plan 

4-23 June 2012 

percent to the State of Louisiana and 20 percent to the State of Mississippi. It is not 

anticipated that this allocation will change as a result of completing the feasibility study 

for the project; however, if it does, the change in allocation will be addressed in the 

study, as approved by the decision of the Chief of Engineers 

 Tier 3B includes any features that are dependent on freshwater diversion, and features 

in Tier 2 that future conditions and further analyses indicate are not sustainable. 

Subsequent to the completion of Tier 3A, Tier 3B features would be constructed through 

the WRDA 2007 Section 7013 authority upon the identification of a non-Federal sponsor. 

5-1 June 2012 

5 LIST OF PREPARERS 

Name Job Description/Experience/

Education/Registration

Subject Matter

Britsch, Del Geologist/27 years/Ph.D./Reg.Prof.Geol. Geology,Sediment 

Sources,Subsidence, Land Loss

Broussard, Darrel Project Manager/20 years/B.S. Physics, MBA Sr. Project Manager

Broussard, Richard Lead Civil Engineer/Technical Manager (MVN)/ 33 years/ 

BSCE, University of New Orleans/ EI in LA

Dredging for navigation, flood 

control, coastal restoration and 

foreshore protection

Boyce, Mayely Assistant District Council (MVN)/3 years/J.D/M.E.M., Duke 

University

Legal Review

Carson, Joshua Environmental Scientist (PBS&J) 3 years/ B.S. in Biology, 

Baldwin-Wallace College

Project Manager

Chaisson, Angela Senior Project Manager/Senior NEPA Specialist (URS), 

26 years/B.S., Wildlife Resources, West Virginia 

University/Certified Wildlife Biologist, The Wildlife Society

Independent Technical Review of 

EIS Sections

Conner, J.V. Senior Ecologist (URS) 45 years/Ph.D. Tulane University Wildlife, Noise

Darville, Jennifer Technical Editor and Writer/MVN 10 years/M.A. English, 

University of New Orleans

Technical Writer/Editor/Document 

Administration

Deloach, Pamela Project Engineer/26 years/B.S. Civil Engineering –

University of Alabama

Engineering Team Leader

DeMarcay, Gary Archaeologist (MVN) 24 years/MA

Anthropology, Texas A&M University

Cultural Resources

Esmail, Muna Senior Environmental Engineer (URS) / 11 years / B.S. 

Civil Engineering, Tulane University

Air Quality

Feldmeier, Paula

Goh, Yong Sr. Project Scientist/environmental specialist 24 years, Soil 

Scientist, soil morphologist, Louisiana State University.

Soils 

Lanford, Caroline Lead Planner / 11 years/ M.U.R.P University

of New Orleans/American Institute of

Certified Planners (AICP)

Plan Formulation, Project 

Management Support

LeBlanc, Jim Sr. Environmental Scientist/ 31 years /B.S. Marine 

Science, Nicholls State University

Coastal Vegetation Resources; 

Plankton Resources

Marler, Bradley Senior Project Scientist, 22 years, M.S. Wildlife 

Ecology/Fisheries Management – Mississippi State 

University

Barrier Islands, URS Internal 

Technical Review

Martinez, Jonathan Environmental Planner (URS)/9 years

B.S. Forestry and Ecosystem Management – Louisiana 

State University

Environmental Lead / Water Quality 

and Scenic Streams

Mccaffrey, Kelly Landscape Architect (MVN)/9 years/ B.L.A.Landscape 

Architecture – Mississippi State University

Aesthetics/Visual Resources

Miller, Gregory Senior Planner (MVN) /22 years/ B.S. in Marine Science 

and International Business from The University of 

Alabama, and M.A. in Marine Affairs from the University of 

Rhode Island.

Plan Formulation, Project 

Management, Public Involvement

Muller, Brandon Wildlife Biologist (URS)/6 years

B.S. Wildlife and Fisheries Management –

Louisiana State University

Aquatic/Fisheries Resources, 

Commercial Fisheries, Oyster 

Resources, Water Bottoms and 

Benthic Resources, and Essential 

Fish Habitat
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 6: List of Preparers 

5-2 June 2012 

Name Job Description/Experience/

Education/Registration

Subject Matter

Napolitano, Matthew Economist, 17 years/ BS Economics, University of 

Pennsylvania, MBA Tulane University

Economics

Parker, Thomas Environmental Resource Specialist (MVN) 2 Years/ B.A. 

Biology, University of Colorado at Denver

Endangered Species and Biological 

Assessment

Perez, Andrew Outdoor Recreation Planner, 11 years/ M.U.R.P. –

University of North Carolina

Recreation Specialist

Qualls, Ying Environmental Scientist / 20 years / B.A. City & Regional 

Planning / University of Louisiana Lafayette

Barrier Reef Resources

Reidenauer, Jeffrey Senior Project Manager/Senior NEPA Specialist (URS), 

24 years/Ph.D. and M.S., Biological Oceanography, 

Florida State University, B.S., Marine Biology, Fairleigh 

Dickenson University/Certified Senior Ecologist, Ecological 

Society of America/Professional Wetland Scientist, Society 

of Wetland Scientists

Independent Technical Review of 

EIS Sections

Richardson, Jerica Archaeologist (MVN) 13 years/BA

Anthropology, Mississippi State University

Environmental Justice

Stiles, Sandra Chief, Ecological Planning and Restoration Section/ MVD 

RTS Environmental Compliance /26 years/B.S. Animal 

Science at Oklahoma State University

Environmental Manager/Biologist

Spalding, Elizabeth Senior Staff Scientist II (PBSJ)/11 years experience in 

Louisiana coastal ecosystem assessment and restoration/ 

M.S. Biology–University of New Orleans and B.S. degrees 

in Biology and Business – Indiana University

Estuarine Ecology: Flora and 

Fauna 

Taylor, Ron Hydraulics Engineer, 9 years/B.S. Civil Engineering 

University of New Orleans PE-LA

Functional Team Leader

Engineering; Hydraulic Engineering

Whalen, Dan Economist/36 years/BS Economics University of New 

Orleans

Economics

Winer, Harley Coastal/Hydraulic/Civil engineer (PBSJ)/21 yrs/ Ph.D. 

U of Florida/ PE- LA, MS, AL, FL

Hydraulic Engineering
6-1 June 2012 

6 LITERATURE CITED 

Abadie, S.W. and M.A. Poirrier. 2001b. Rangia Clams as an Indicator of Hypoxia in Lake 

Pontchartrain. In: S. Penland, A. Beall and J. Waters (Editors) Environmental Atlas of the 

Pontchartrain Basin. Lake Pontchartrain Basin Foundation. p166 

Barrow, W.C., Chien, C.C., Hamilton, R.B., Ouchley, K. and Spengler, T.J. 2000. Disruption and 

restoration of en route habitat, a case study: The Chenier Plain. In Stopover Ecology of 

Nearctic-Neotropical Landbird Migrants: Habitat Relations and Conservation Implications 

(F.R. Moore, ed.), pp. 71–87. Studies in Avian Biology No. 20. Cooper Ornithological 

Society, Camarillo, CA. 

Barrow, W.C. Jr., P. Chadwick, B. Couvillion, T. Doyle, S. Faulkner, C. Jeske, T. Michot, L. 

Randall, C. Wells, and S. Wilson 2007. Cheniere Forest as Stopover Habitat for Migrant 

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Applicable USACE Engineering Regulations

Publication 

Number Title Publication Date

ER 1-1-11 Progress, Schedules, and Network Analysis Systems 15 Jun 95

ER 1-2-2

Water Resources Policies and Authorities Substantive 

Congressional Contacts 01 Jul 91

ER 5-1-9 Assignment and Transfer of Project Responsibilities 15 Mar 96

ER 5-1-11 USACE Business Process 01 Nov 06

ER 11-1-321 Army Programs Value Engineering 28 Feb 05

ER 11-2-101 Army Programs – Civil Works Activities CH 1-24 01 Aug 64

ER 25-1-98 Publications in the Federal Register 10 May 96

ER 200-1-4

Environmental Compliance Policies-Formerly Utilized Sites 

Remedial Action Program (FUSRAP) – Site Designation, 

Remediation Scope, and Recovering Costs

30 Aug 03

ER 200-1-5

Policy for Implementation and Integrated Application of USACE 

Environmental Operating Principles and Doctrine 30 Oct 03

ER 200-2-2 Procedures for Implementing NEPA 04 Mar 88

ER 200-2-3 Environmental Compliance Policies 30 Oct 96

ER 360-1-1 Public Affairs 1 Apr 91

ER 415-1-11 Biddability, Constructabilty, Operability, and Environmental 

Review 1 Sept 94

ER 1105-2-100

Amendment 1, 

Appendix G 

Amendment 2, 

Appendix F

Amendment 1, 

Appendix D

Planning Guidance Notebook

22 Apr 00

30 June 04

31 Jan 07

30 June 04

ER 1110-1-12

Change 1 Quality Management 21 July 0630 Sept 06

ER 1110-1-263 Chemical Data Quality Management for Hazardous, Toxic, 

Radioactive Waste Remedial Activities 30 Apr 98

ER 1110-1-300 Cost Engineering Policy and General Requirements 26 Mar 93

ER 1110-1-8156 Policies, Guidance, and Requirements for Geospatial Data and 

Systems 30 Sept 05

ER 1110-1859 Engineering and Design, DrChecks 10 May 2001

ER 1110-2-401

Operation, Maintenance, Repair, Replacement, and 

Rehabilitation Manual for Projects and Separable Elements 

Managed by Project Sponsors

30 Sept 94

ER 1110-2-1150 Engineering and Design for Civil Works Projects 31 Aug 99

ER 1110-2-1302 Civil Works Cost Engineering 31 Mar 94
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 7: Literature Cited 

6-8 June 2012 

Applicable USACE Engineering Regulations

Publication 

Number Title Publication Date

ER 1110-2-1403 Studies by Coastal, Hydraulic and Hydrologic Facilities and 

Others 1 Jan 98

ER 1110-2-1496 Coastal Field Data Collection 30 Apr 90

ER 1110-2-1407 Hydraulic Design for Coastal Shore Protection Projects 30 Nov 97

ER 1110-2-1450 Hydrologic Frequency Estimates 31 Aug 94

ER 1110-2-1451 Acquisition of lands Downstream from Spillways for Hydrologic 

Safety Purposes 10 Aug 78

ER 1110-2-1460 Hydrologic Engineering Management 7 July 89

EM 1110-2-6056 Standards and Procedures for Referencing Project 

Elevation Grades to Nationwide Vertical Datums (Draft) 31 Dec 10

ER 1110-2-8153 Technical Project Sedimentation Investigations 30 Sept 95

ER 1110-2-8154 Water Quality and Environmental Management for Corps Civil 

Works Projects 31 May 1995

ER 1110-2-8160 Policies for Referencing Project Elevation Grades 01 Mar 09

ER 1165-2-27 Establishment of Wetlands Areas in Connection with Dredging 18 Aug 89

ER 1165-2-132 Hazardous, Toxic, and Radioactive Waste (HTRW) Guidance 

for Civil Works Projects 26 June 92

EC 1165-2-206

Delegation of Review, Approval, and Signature Authority for 

Project Cooperation Agreements for Specifically Authorized 

Projects

30 Jan 04

ER 1165-2-501 Civil Works Ecosystem Restoration Policy 30 Sept 99

EC 1165-2-211 Incorporating Sea-Level Change Considerations in Civil 

Works Programs 1 July 09

MSC Regulations DIVR 415-2-3, Alterations to Federally Constructed 

Floodwater Retaining Works 2 Mar 98

MSC Regulations DIVR 1100-1-4031 Policy on River Diversions 23 Mar 11
7-1 June 2012 

7 ACRONYMS AND ABBREVIATIONS 

AAHU Average Annual Habitat Unit 

ADCIRC ADvanced CIRCulation (wind and wave modeling system) 

ASA(CW) Assistant Secretary of the Army for Civil Works 

ATR Agency Technical Review 

CE/ICA Cost Effectiveness/Incremental Cost Analysis 

CIAP Coastal Impact Assistance Program 

CPRA Coastal Protection and Restoration Authority (State of Louisiana) 

CWPPRA Coastal Wetlands Planning, Protection, and Restoration Act 

DEIS Draft Environmental Impact Statement 

EA Environmental Assessment 

EFH Essential Fish Habitat 

EIS Environmental Impact Statement 

FIP Federally Identified Plan 

FONSI Finding of No Significant Impact 

FWOP Future Without Project 

FWP Future With Project 

GIS Geographic Information System 

GIWW Gulf Intracoastal Waterway 

HSDRRS Hurricane and Storm Damage Risk Reduction System 

HTRW Hazardous, Toxic, and Radioactive Waste 

IPET Interagency Performance Evaluation Taskforce 

IHNC Inner Harbor Navigation Canal 

IWR Institute of Water Resources 

LACPR Louisiana Coastal Protection and Restoration 

LCA 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 

MDEQ Mississippi Department of Environmental Quality 

MDMR Mississippi Department of Marine Resources 

MRGO Mississippi River Gulf Outlet 

MR&T Mississippi River and Tributaries 

MsCIP Mississippi Coastal Improvements Program 

MVD USACE Mississippi Valley Division 

MVN USACE New Orleans District 

NAVD North American Vertical Datum 

NEPA National Environmental Policy Act 

NER National Ecosystem Restoration 

NMFS National Marine Fisheries Service 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 8: Acronyms and Abbreviations 

7-2 June 2012 

NOAA National Oceanic and Atmospheric Administration 

NRCS Natural Resources Conservation Service 

O&M Operation and Maintenance 

OMRR&R Operation and Maintenance, Repair, Replacement and Rehabilitation 

PED Preconstruction Engineering and Design 

PDT Project Delivery Team 

SAD USACE South Atlantic Division 

SAM USACE Mobile District 

SAV Submerged Aquatic Vegetation 

SSDS Social Science Data and Software 

USACE U.S. Army Corps of Engineers 

USEPA U.S. Environmental Protection Agency 

USFWS U.S. Fish and Wildlife Service 

USGS U.S. Geological Survey 

WCRF Wetlands Conservation and Restoration Fund 

WRDA Water Resources Development Act 

WVA Wetland Value Assessment 
8-1 June 2012 

8 GLOSSARY 

Alternatives or alternative plans. Combinations of management measures that collectively 

meet study goals and objectives within the defined study constraints. 

Constraint. A limitation or restriction on plans. Planning constraints may not be absolute 

restrictions but rather something to minimize or avoid. 

Damage. This term from the Congressional language is interpreted to mean damage to real 

property. 

Eustatic sea level rise. Change in global average sea level brought about by an increase in the 

volume of the world ocean [Intergovernmental Panel of Climate Change (IPCC) 2007b]. See 

also relative sea level rise. 

IWR-PLAN. A decision support software program that assists with plan formulation by 

combining user-defined solutions to planning problems and calculating the effects of each 

combination, or ―plan.‖ The program can assist with plan comparison by conducting cost 

effectiveness and incremental cost analyses, identifying the plans which are best financial 

investments and displaying the effects of each on a range of decision variables. 

Locally Preferred Plan. A plan requested by the non-Federal sponsor that deviates from the 

National Ecosystem Restoration Plan. 

Management measures. A feature (a structural element that requires construction or assembly 

on-site) or an activity (a nonstructural action) that can be combined with other management 

measures to form alternative plans. 

Marsh creation. A type of management measure that creates marsh in open water and 

nourishes the surrounding existing marsh. Marsh creation will include vegetative plantings. See 

also marsh nourishment. 

Marsh nourishment. A type of management measure that nourishes existing marsh and 

decreases the depth of nearby open water. See also marsh creation. 

National Ecosystem Restoration (NER) Plan. For ecosystem restoration projects, a plan that 

reasonably maximizes ecosystem restoration benefits compared to costs, consistent with the 

Federal objective. The selected plan must be shown to be cost effective and justified to achieve 

the desired level of output. 

Natural features. This term from the Congressional language is interpreted to mean those 

features that serve a primarily ecosystem restoration purpose rather than features that primarily 

serve another purpose such as levees or floodwalls. 

Opportunities. Desirable conditions to be achieved. 
Mississippi River Gulf Outlet Ecosystem Restoration Plan 

Final Feasibility Report 9: Glossary 

8-2 June 2012 

Period of analysis. The time horizon for which project benefits, deferred construction costs, 

and operation, maintenance, repair, rehabilitation, and replacement costs are analyzed. For this 

study, the period of analysis is from 2011 to 2065. 

Problems. Undesirable conditions to be solved. 

Reduce or prevent damage from storm surge. This phrase from the Congressional language 

is interpreted as ―hurricane and storm damage risk reduction‖ as used in LACPR. This 

interpretation is consistent with LACPR, e.g. we cannot prevent, we can only reduce risk, and 

hurricane and storm damage risk results from factors in addition to storm surge including but not 

limited to waves. 

Relative sea level rise. Sea level rise measured by a tide gauge with respect to the land upon 

which it is situated. Relative sea level rise occurs where there is a local change in the level of 

the ocean relative to the land, which might be due to ocean rise and/or land level subsidence. 

See also eustatic sea level rise. 

Risk. A measure of the probability and severity of undesirable consequences (including, but not 

limited to, loss of life, threat to public safety, environmental and economic damages). 

Uncertainty. Uncertainty is the result of imperfect knowledge concerning the present or future 

state of a system, event, situation, or (sub) population under consideration. There are two types 

of uncertainty: aleatory and epistemic. Aleatory uncertainty is the uncertainty attributed to 

inherent variation which is understood as variability over time and/or space. Epistemic 

uncertainty is the uncertainty attributed to our lack of knowledge about the system (e.g., what 

value to use for an input to a model or what model to use). Uncertainty can lead to lack of 

confidence in predictions, inferences, or conclusions. 

Wetland Value Assessment (WVA). A quantitative habitat-based assessment methodology 

used to determine wetland benefits of restoration measures. The WVA quantifies changes in 

fish and wildlife habitat quality and quantity that are expected to result from a proposed wetland 

restoration project. The results of the WVA, measured in Average Annual Habitat Units 

(AAHUs), can be combined with cost data to provide a measure of the effectiveness of a 

proposed project in terms of annualized cost per AAHU gained. In addition, the WVA 

methodology provides an estimate of the number of acres benefited or enhanced by the project 

and the net acres of habitat protected/restored.