MISSISSIPPI RIVER GULF OUTLET (MRGO)

ECOSYSTEM RESTORATION PLAN

FINAL

ENVIRONMENTAL IMPACT STATEMENT

U.S. Army Corps of Engineers

Mississippi Valley Division

New Orleans District

7400 Leake Avenue

New Orleans, Louisiana 70118

June 2012
Table of Contents 

FEIS MRGO Ecosystem

Restoration Plan i June 2012

FINAL

ENVIRONMENTAL IMPACT STATEMENT

MISSISSIPPI RIVER GULF OUTLET (MRGO)

ECOSYSTEM RESTORATION STUDY

LOUISIANA AND MISSISSIPPI

TABLE OF CONTENTS

CHAPTER 1: INTRODUCTION ............................................................................................. 1-1

1.1 INTRODUCTION .................................................................................................. 1-1

1.2 STUDY AUTHORITY AND STUDY SPONSOR ............................................... 1-2

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

1.4 PURPOSE AND NEED FOR ACTION ................................................................ 1-7

1.4.1 MRGO Navigation Channel ............................................................................. 1-11

1.4.1.1 MRGO Impacts .................................................................................... 1-13

1.4.2 Land Loss ......................................................................................................... 1-16

1.4.3 Bank/Shoreline Erosion .................................................................................... 1-19

1.4.4 Habitat Change and Loss .................................................................................. 1-20

1.4.5 Modification of Natural Hydrology ................................................................. 1-20

1.4.6 Lake Borgne Ecosystem ................................................................................... 1-21

1.4.7 Retreating and Eroding Barrier Islands ............................................................ 1-22

1.4.8 Ridge Habitat Degradation and Destruction..................................................... 1-22

1.4.9 Invasive Species ............................................................................................... 1-22

1.4.10 Herbivory ......................................................................................................... 1-23

1.4.11 Increasing Susceptibility to Storm Surge ......................................................... 1-23

1.5 RESTORATION GOALS .................................................................................... 1-23

1.6 STUDY OBJECTIVES ......................................................................................... 1-24

1.7 HABITAT EVALUATION TEAM ..................................................................... 1-31

1.7.1 Tasks................................................................................................................. 1-32

1.7.2 Guiding Principles ............................................................................................ 1-32

1.7.3 Approach .......................................................................................................... 1-33

1.8 NATIONAL ENVIRONMENTAL POLICY ACT ............................................ 1-33

1.8.1 Environmental Assessments and Environmental Impact Statements ............... 1-33

1.8.2 NEPA Scoping ................................................................................................. 1-36

1.8.3 Cooperating Agencies ...................................................................................... 1-38

1.8.4 Compliance with Laws and Executive Orders ................................................. 1-38

1.8.5 Current and Authorized Restoration Projects ................................................... 1-40

CHAPTER 2: ALTERNATIVE FORMULATION ................................................................ 2-1

2.1 INTRODUCTION .................................................................................................. 2-1

2.2 CONCEPTUAL ECOLOGICAL MODEL .......................................................... 2-3

2.2.1 Overview ............................................................................................................ 2-3

2.2.2 Coastal System Processes ................................................................................... 2-3

2.2.3 Important Issues in the Development of Alternatives ........................................ 2-5

2.2.3.1 Natural Hydrologic Process Degradation (Hydrologic Barriers, 

Connectivity) ......................................................................................... 2-7

2.2.3.2 Ridge Habitat Degradation (Hydrologic Barriers) ............................... 2-7

2.2.3.3 Barrier Island Degradation .................................................................. 2-7
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2.2.3.4 Storm Surge ........................................................................................... 2-8

2.2.3.5 Herbivory .............................................................................................. 2-8

2.2.3.6 Invasive Species ..................................................................................... 2-8

2.2.3.7 Drought ................................................................................................. 2-9

2.2.3.8 Habitat Change ..................................................................................... 2-9

2.2.3.9 Lake Pontchartrain Dead Zone Expansion ........................................... 2-9

2.2.3.10 Reduced Freshwater, Nutrient, Sediment Input .................................... 2-9

2.2.3.11 Wetland Losses (Land Loss Rate) ....................................................... 2-10

2.2.3.12 Saltwater Intrusion (Salinity) .............................................................. 2-10

2.2.3.13 Shoreline Erosion (Land Loss Rate) ................................................... 2-10

2.2.3.14 Subsidence ........................................................................................... 2-11

2.3 IDENTIFICATION OF MANAGEMENT MEASURES AND INITIAL 

SCREENING PROCESS ..................................................................................... 2-11

2.3.1 Description of Measures by Type .................................................................... 2-12

2.3.1.1 Freshwater Diversion .......................................................................... 2-12

2.3.1.2 Hydrologic Restoration ....................................................................... 2-13

2.3.1.3 Marsh Restoration and Marsh Nourishment ....................................... 2-13

2.3.1.4 Swamp Restoration and Nourishment ................................................. 2-14

2.3.1.5 Shoreline Protection ............................................................................ 2-14

2.3.1.6 Ridge Restoration ................................................................................ 2-14

2.3.1.7 Restoration/Creation of Forested Habitat .......................................... 2-15

2.3.1.8 Barrier Island Restoration .................................................................. 2-15

2.3.1.9 Submerged Aquatic Vegetation (SAV) Restoration ............................. 2-15

2.3.1.10 Oyster Reef Restoration ...................................................................... 2-16

2.3.1.11 Vegetative Planting ............................................................................. 2-16

2.3.2 Initial Formulation and Screening Process .................................................. 2-16

2.3.2.1 Freshwater Diversion / Initial Screening Process .............................. 2-17

2.3.2.2 Hydrologic Restoration Initial Screening Results ............................... 2-22

2.3.2.3 Marsh and Swamp Restoration Initial Screening Results ................... 2-24

2.3.2.4 Shoreline Protection Initial Screening Results.................................... 2-26

2.3.2.5 Ridge Restoration Initial Screening Results ........................................ 2-29

2.3.2.6 Vegetative Planting Initial Screening Results ..................................... 2-31

2.3.2.7 Barrier Island Restoration Initial Screening Results .......................... 2-32

2.3.2.8 SAV Demonstration Project Initial Screening Results ........................ 2-32

2.3.2.9 Artificial Oyster Reef Initial Screening Results .................................. 2-33

2.3.3 Summary of Initial Screening Results .............................................................. 2-33

2.3.4 Measures Requiring Additional Study ............................................................. 2-33

2.3.4.1 Recommendations for Additonal Studies ............................................. 2-33

2.3.4.2 Barrier Island Restoration .................................................................. 2-34

2.3.4.3 Sediment Study .................................................................................... 2-34

2.3.4.4 Fisheries Modeling Study .................................................................... 2-35

2.3.4.5 Recreation Components ...................................................................... 2-36

2.3.5 Measures Considered But Eliminated .............................................................. 2-36

2.4 ALTERNATIVE PLAN FORMULATION ....................................................... 2-36

2.4.1 Preliminary Evaluation of Measures ................................................................ 2-37

2.4.1.1 Outputs (Benefits) ................................................................................ 2-37

2.4.1.2 Sustainability ....................................................................................... 2-49

2.4.1.3 Costs .................................................................................................... 2-50

2.4.1.4 Relative Sea Level Rise Considerations .............................................. 2-52

2.5 COST EFFECTIVENESS/INCREMENTAL COST ANALYSIS ................... 2-54

2.5.1 Institute for Water Resources (IWR) Plan Steps .............................................. 2-54
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2.5.2 Institute for Water Resources (IWR) Plan Results ........................................... 2-58

2.5.3 Selection of the Final Array of Alternatives ..................................................... 2-59

2.5.3.1 Violet, Louisiana Freshwater Diversion ............................................ 2-65

2.5.3.2 Recreational Components ................................................................... 2-66

2.6 DESCRIPTION OF ALTERNATIVES CONSIDERED .................................. 2-71

2.6.1 Alternative A - No Action Plan (FWOP Condition) ........................................ 2-71

2.6.2 Action Alternatives........................................................................................... 2-75

2.6.2.1 Violet, Louisiana Freshwater Diversion ............................................. 2-75

2.6.2.2 Alternative B - MRGO Restoration Plan 2 .......................................... 2-87

2.6.2.3 Alternative C - MRGO Restoration Plan 7 ......................................... 2-87

2.6.2.4 Alternative D - MRGO Restoration Plan 10 ....................................... 2-87

2.7 EVALUATION OF ALTERNATIVE PLANS................................................... 2-92

2.7.1 Risks and Uncertainties .................................................................................... 2-94

2.7.2 Assessment of Sustainability for Relative Sea Level Rise Scenarios .............. 2-98

2.8 COMPARISON OF ALTERNATIVE PLANS ................................................ 2-100

2.9 IDENTIFICATION OF THE TENATIVELY SELECTED PLAN ............... 2-101

2.9.1 Description of the Tentatively Selected Plan ................................................. 2-103

2.9.1.1 Marsh Restoration ............................................................................. 2-104

2.9.1.2 Marsh Nourishment ........................................................................... 2-105

2.9.1.3 Swamp Restoration ............................................................................ 2-106

2.9.1.4 Swamp Nourishment .......................................................................... 2-107

2.9.1.5 Shoreline Protection .......................................................................... 2-108

2.9.1.6 Ridge Restoration .............................................................................. 2-111

2.9.1.7 Access Corridors ............................................................................... 2-112

2.9.1.8 Flotation Access Channels ................................................................ 2-113

2.9.1.9 Implementation Approach ................................................................. 2-113

2.9.1.10 Borrow Sites ...................................................................................... 2-122

2.10 ADAPTIVE MANAGEMENT .......................................................................... 2-127

2.11 ENVIRONMENTAL COMMITMENTS ......................................................... 2-128

2.12 MODEL DEVELOPMENT AND UNCERTAINTIES ................................... 2-130

2.12.1 Predicting Future Conditions.......................................................................... 2-130

2.12.2 UNO Mass Balance Model Uncertainties ...................................................... 2-132

2.12.3 Sediment and Nutrient Diversion (SAND2) Model Uncertainties ................. 2-134

2.12.4 Wetland Value Assessment Model Uncertainties .......................................... 2-135

2.12.5 Land Change Uncertainties ............................................................................ 2-139

2.12.6 Comprehensive Aquatic Ecosystem Model (CASM) Uncertainties .............. 2-139

2.12.7 Oil Spill Uncertainties .................................................................................... 2-141

2.12.8 Engineering Level of Design .......................................................................... 2-144

2.13 RESEARCH AND TECHNOLOGY DEVELOPMENT NEEDS .................. 2-145

CHAPTER 3: AFFECTED ENVIRONMENT ........................................................................ 3-1

3.1 INTRODUCTION .................................................................................................. 3-1

3.2 SIGNIFICANT RESOURCES .............................................................................. 3-2

3.3 STUDY AREA ......................................................................................................... 3-3

3.4 GEOMORPHIC AND PHYSIOGRAPHIC SETTING ...................................... 3-4

3.5 COASTAL SYSTEM PROCESSES ..................................................................... 3-8

3.5.1 The Deltaic Processes ......................................................................................... 3-8

3.5.2 Mud Stream ........................................................................................................ 3-8

3.5.3 Marine Processes ................................................................................................ 3-9

3.5.4 Fluvial Processes ................................................................................................ 3-9

3.5.5 Chemical Processes .......................................................................................... 3-10

3.5.6 Biological Processes ......................................................................................... 3-10
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3.6 HYDROLOGY – HYDRAULICS ....................................................................... 3-12

3.6.1 Historic and Existing Conditions ..................................................................... 3-12

3.7 WATER QUALITY .............................................................................................. 3-14

3.7.1 Historic and Existing Conditions ..................................................................... 3-14

3.7.1.1 Mississippi River Existing Water Quality ........................................... 3-17

3.7.1.2 Central Wetlands Area Existing Water Quality .................................. 3-19

3.7.1.3 Mississippi River Gulf Outlet (MRGO) Existing Water Quality ......... 3-21

3.7.1.4 Lake Borgne Wetlands Area Existing Water Quality .......................... 3-22

3.7.1.5 Lake Borgne Existing Water Quality................................................... 3-23

3.7.1.6 Biloxi Marsh Existing Water Quality .................................................. 3-24

3.7.1.7 Mississippi Territorial Waters Existing Water Quality ....................... 3-25

3.7.2 Altered Hydrology ............................................................................................ 3-28

3.7.2.1 MRGO Salinity .................................................................................... 3-29

3.7.2.2 Lake Pontchartrain Salinity ................................................................ 3-33

3.7.2.3 Lake Maurepas Salinity ....................................................................... 3-35

3.7.2.4 Mississippi Territorial Waters Salinity ............................................... 3-36

3.7.2.5 Lake Pontchartrain Hypoxic/Anoxic Zone .......................................... 3-39

3.8 NAVIGABLE WATERWAYS ............................................................................ 3-40

3.8.1 Historic and Existing Conditions ..................................................................... 3-40

3.9 SOILS AND SEDIMENTS................................................................................... 3-42

3.9.1 Historic and Existing Conditions ..................................................................... 3-42

3.9.2 Prime and Unique Farmlands ........................................................................... 3-49

3.9.3 Sediments ......................................................................................................... 3-49

3.10 AIR QUALITY ..................................................................................................... 3-51

3.10.1 Historic and Existing Conditions ..................................................................... 3-51

3.11 NOISE .................................................................................................................... 3-54

3.11.1 Historic and Existing Conditions ..................................................................... 3-54

3.12 HAZARDOUS, TOXIC, AND RADIOACTIVE WASTE ................................ 3-55

3.12.1 Historic and Existing Conditions ..................................................................... 3-55

3.13 BARRIER ISLAND RESOURCES ..................................................................... 3-56

3.13.1 Historic and Existing Conditions ..................................................................... 3-56

3.13.2 Shoreline Changes: History and Storm Impacts ............................................... 3-60

3.13.3 Tidal Inlets ........................................................................................................ 3-61

3.13.4 Spits 3-62

3.13.5 Barrier Shoals ................................................................................................... 3-62

3.13.6 Back-Barrier Platform, Habitat and Submerged Aquatic Vegetation .............. 3-63

3.13.6.1 Plant Communities .............................................................................. 3-63

3.13.6.2 Wildlife and Habitat Associations ....................................................... 3-63

3.13.6.3 Submerged Aquatic Vegetation ........................................................... 3-64

3.13.7 Sediment Dynamics .......................................................................................... 3-64

3.14 COASTAL VEGETATION RESOURCES ........................................................ 3-65

3.14.1 Land Cover ....................................................................................................... 3-66

3.14.2 Wetland Vegetation .......................................................................................... 3-66

3.14.3 Plant Community Types ................................................................................... 3-69

3.14.3.1 Swamp (0-3 ppt Salinity) – 180,279 Acres .......................................... 3-69

3.14.3.2 Freshwater Marsh (0-3 ppt Salinity) – 78,720 Acres .......................... 3-70

3.14.3.3 Intermediate Marsh (2-8 ppt Salinity) – 185,272 Acres ...................... 3-70

3.14.3.4 Brackish Marsh (4-18 ppt Salinity) – 197,223 Acres .......................... 3-71

3.14.3.5 Salt Marsh and Barrier Islands (8-29 ppt Salinity) – 231,345 Acres . 3-71

3.14.4 Invasive Species ............................................................................................... 3-72

3.14.5 Rare, Unique and Imperiled Vegetative Communities ..................................... 3-76
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3.14.5.1 Marine Submerged Aquatic Vegetation Communities ........................ 3-76

3.14.5.2 Estuarine Submerged Aquatic Vegetation Communities ..................... 3-77

3.14.5.3 Coastal Mangrove Thicket .................................................................. 3-77

3.14.5.4 Coastal Dune Grassland ..................................................................... 3-77

3.14.5.5 Live Oak Forest ................................................................................... 3-78

3.14.5.6 Coastal Live Oak-Hackberry Forest ................................................... 3-78

3.15 WILDLIFE RESOURCES ................................................................................... 3-78

3.15.1 Historic and Existing Conditions ................................................................... 3-78

3.16 AQUATIC AND FISHERY RESOURCES ........................................................ 3-83

3.16.1 Historic and Existing Conditions ..................................................................... 3-83

3.16.1.1 Mississippi Territorial Waters............................................................. 3-83

3.16.1.2 Louisiana Estuaries ............................................................................. 3-84

3.16.2 Commercial Fisheries ....................................................................................... 3-85

3.16.3 Oyster Resources .............................................................................................. 3-87

3.16.4 Water Bottoms and Benthic Resources ............................................................ 3-89

3.17 PLANKTON RESOURCES ................................................................................ 3-91

3.17.1 Historic and Existing Conditions ..................................................................... 3-91

3.18 ESSENTIAL FISH HABITAT ............................................................................ 3-92

3.18.1 Historic and Existing Conditions ..................................................................... 3-92

3.19 THREATENED AND ENDANGERED SPECIES ............................................ 3-98

3.19.1 Historic and Existing Conditions ..................................................................... 3-98

3.20 SOCIOECONOMIC AND HUMAN ENVIRONMENT ................................. 3-103

3.20.1 Historic and Existing Conditions ................................................................... 3-103

3.20.2 Population ....................................................................................................... 3-103

3.20.3 Community Cohesion ..................................................................................... 3-105

3.20.4 Employment and Income................................................................................ 3-106

3.20.5 Infrastructure .................................................................................................. 3-106

3.20.6 Oil, Gas and Utility ........................................................................................ 3-106

3.20.7 Flood Control and Protection Levees ............................................................. 3-108

3.21 ENVIRONMENTAL JUSTICE ........................................................................ 3-110

3.21.1 Historic Conditions ........................................................................................ 3-111

3.21.2 Existing Conditions ........................................................................................ 3-111

3.22 HISTORIC AND CULTURAL RESOURCES ................................................ 3-113

3.22.1 Louisiana ........................................................................................................ 3-113

3.22.2 Mississippi ...................................................................................................... 3-114

3.23 RECREATIONAL RESOURCES .................................................................... 3-115

3.23.1 Historic Conditions ........................................................................................ 3-115

3.23.2 Louisiana Recreational Resources .................................................................. 3-115

3.23.2.1 Recreational Resource Facilities in the Project Area ....................... 3-118

3.23.3 Mississippi Recreational Resources ............................................................... 3-119

3.24 AESTHETICS ..................................................................................................... 3-121

3.24.1 Historic and Existing Conditions ................................................................... 3-121

3.24.1.1 East Orleans Landbridge .................................................................. 3-121

3.24.1.2 Central Wetlands ............................................................................... 3-122

3.24.1.3 Pearl River Mouth – LA .................................................................... 3-123

3.24.1.4 Pearl River Mouth – MS .................................................................... 3-124

3.24.1.5 Biloxi Marshes Exterior .................................................................... 3-124

3.24.1.6 Biloxi Marshes Interior ..................................................................... 3-124

3.24.1.7 Eloi Bay ............................................................................................. 3-124

3.24.1.8 Hopedale ........................................................................................... 3-125

3.24.1.9 IHNC/GIWW ..................................................................................... 3-125
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3.24.1.10 Terre aux Boeufs ............................................................................... 3-125

3.24.1.11 Lake Borgne ...................................................................................... 3-126

3.24.1.12 South Lake Borgne ............................................................................ 3-127

3.24.1.13 MRGO Dredge Material Bank .......................................................... 3-127

3.24.1.14 Western Mississippi Sound ................................................................ 3-127

3.24.2 Scenic Streams ............................................................................................... 3-128

3.24.2.1 Historic and Existing Conditions ...................................................... 3-128

3.25 FLOODPLAINS .................................................................................................. 3-131

3.25.1 Historic and Existing Conditions ................................................................... 3-131

CHAPTER 4: ENVIRONMENTAL CONSEQUENCES ....................................................... 4-1

4.1 INTRODUCTION .................................................................................................. 4-1

4.2 TENTATIVELY SELECTED PLAN SUMMARY ............................................. 4-2

4.3 ENVIRONMENTAL CONSEQUENCES SUMMARY TABLE ....................... 4-3

4.4 HYDROLOGY – HYDRAULICS ....................................................................... 4-12

4.4.1 Alternative A - No Action Plan ........................................................................ 4-12

4.4.2 Alternative B - MRGO Restoration Plan 2....................................................... 4-14

4.4.3 Alternative C - MRGO Restoration Plan 7....................................................... 4-15

4.4.4 Alternative D - MRGO Restoration Plan 10 .................................................... 4-16

4.5 WATER QUALITY .............................................................................................. 4-16

4.5.1 Alternative A - No Action Plan ........................................................................ 4-16

4.5.2 Alternative B - MRGO Restoration Plan 2....................................................... 4-21

4.5.3 Alternative C - MRGO Restoration Plan 7....................................................... 4-27

4.5.4 Alternative D - MRGO Restoration Plan 10 .................................................... 4-29

4.6 NAVIGABLE WATERWAYS ............................................................................ 4-31

4.6.1 Alternative A - No Action Plan ........................................................................ 4-31

4.6.2 Alternative B - MRGO Restoration Plan 2....................................................... 4-32

4.6.3 Alternative C - MRGO Restoration Plan 7....................................................... 4-33

4.6.4 Alternative D - MRGO Restoration Plan 10 .................................................... 4-34

4.7 SOILS ..................................................................................................................... 4-34

4.7.1 Alternative A - No Action Plan ........................................................................ 4-34

4.7.2 Alternative B - MRGO Restoration Plan 2....................................................... 4-35

4.7.3 Alternative C - MRGO Restoration Plan 7....................................................... 4-37

4.7.4 Alternative D - MRGO Restoration Plan 10 .................................................... 4-37

4.8 SEDIMENTS ......................................................................................................... 4-38

4.8.1 Alternative A - No Action Plan ........................................................................ 4-38

4.8.2 Alternative B - MRGO Restoration Plan 2....................................................... 4-38

4.8.3 Alternative C - MRGO Restoration Plan 7....................................................... 4-39

4.8.4 Alternative D - MRGO Restoration Plan 10 .................................................... 4-40

4.9 AIR QUALITY ..................................................................................................... 4-40

4.9.1 Alternative A - No Action Plan ........................................................................ 4-40

4.9.2 Alternative B - MRGO Restoration Plan 2....................................................... 4-41

4.9.3 Alternative C - MRGO Restoration Plan 7....................................................... 4-44

4.9.4 Alternative D - MRGO Restoration Plan 10 .................................................... 4-46

4.10 NOISE .................................................................................................................... 4-47

4.10.1 Alternative A - No Action Plan ........................................................................ 4-47

4.10.2 Alternative B - MRGO Restoration Plan 2....................................................... 4-47

4.10.3 Alternative C - MRGO Restoration Plan 7....................................................... 4-49

4.10.4 Alternative D - MRGO Restoration Plan 10 .................................................... 4-49

4.11 HAZARDOUS, TOXIC, AND RADIOACTIVE WASTE ................................ 4-50

4.11.1 Alternative A - No Action Plan ........................................................................ 4-52

4.11.2 Alternative B - MRGO Restoration Plan 2....................................................... 4-52
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4.11.3 Alternative C - MRGO Restoration Plan 7....................................................... 4-53

4.11.4 Alternative D - MRGO Restoration Plan 10 .................................................... 4-53

4.12 BARRIER ISLAND RESOURCES ..................................................................... 4-53

4.12.1 Alternative A - No Action Plan ........................................................................ 4-54

4.13 COASTAL VEGETATION RESOURCES ........................................................ 4-54

4.13.1 Alternative A - No Action Plan ........................................................................ 4-54

4.13.2 Alternative B - MRGO Restoration Plan 2....................................................... 4-55

4.13.3 Alternative C - MRGO Restoration Plan 7....................................................... 4-59

4.13.4 Alternative D - MRGO Restoration Plan 10 .................................................... 4-60

4.14 WILDLIFE RESOURCES ................................................................................... 4-61

4.14.1 Alternative A - No Action Plan ........................................................................ 4-61

4.14.2 Alternative B - MRGO Restoration Plan 2....................................................... 4-62

4.14.3 Alternative C - MRGO Restoration Plan 7....................................................... 4-63

4.14.4 Alternative D - MRGO Restoration Plan 10 .................................................... 4-64

4.15 AQUATIC AND FISHERY RESOURCES ........................................................ 4-64

4.15.1 Alternative A - No Action Plan ........................................................................ 4-65

4.15.2 Alternative B - MRGO Restoration Plan 2....................................................... 4-67

4.15.3 Alternative C - MRGO Restoration Plan 7....................................................... 4-70

4.15.4 Alternative D - MRGO Restoration Plan 10 .................................................... 4-71

4.16 COMMERCIAL FISHERIES ............................................................................. 4-72

4.16.1 Alternative A - No Action Plan ........................................................................ 4-72

4.16.2 Alternative B - MRGO Restoration Plan 2....................................................... 4-74

4.16.3 Alternative C - MRGO Restoration Plan 7....................................................... 4-76

4.16.4 Alternative D - MRGO Restoration Plan 10 .................................................... 4-76

4.17 OYSTER RESOURCES ....................................................................................... 4-77

4.17.1 Alternative A - No Action Plan ........................................................................ 4-77

4.17.2 Alternative B - MRGO Restoration Plan 2....................................................... 4-78

4.17.3 Alternative C - MRGO Restoration Plan 7....................................................... 4-82

4.17.4 Alternative D - MRGO Restoration Plan 10 .................................................... 4-82

4.18 WATER BOTTOMS AND BENTHIC RESOURCES ...................................... 4-83

4.18.1 Alternative A - No Action Plan ........................................................................ 4-83

4.18.2 Alternative B - MRGO Restoration Plan 2....................................................... 4-84

4.18.3 Alternative C - MRGO Restoration Plan 7....................................................... 4-87

4.18.4 Alternative D - MRGO Restoration Plan 10 .................................................... 4-88

4.19 PLANKTON RESOURCES ................................................................................ 4-88

4.19.1 Alternative A - No Action Plan ........................................................................ 4-88

4.19.2 Alternative B - MRGO Restoration Plan 2....................................................... 4-89

4.19.3 Alternative C - MRGO Restoration Plan 7....................................................... 4-90

4.19.4 Alternative D - MRGO Restoration Plan 10 .................................................... 4-91

4.20 ESSENTIAL FISH HABITAT ............................................................................ 4-92

4.20.1 Alternative A - No Action Plan ........................................................................ 4-92

4.20.2 Alternative B - MRGO Restoration Plan 2....................................................... 4-94

4.20.3 Alternative C - MRGO Restoration Plan 7....................................................... 4-97

4.20.4 Alternative D - MRGO Restoration Plan 10 .................................................... 4-98

4.21 THREATENED AND ENDANGERED SPECIES ............................................ 4-98

4.21.1 Alternative A - No Action Plan ........................................................................ 4-98

4.21.2 Alternative B - MRGO Restoration Plan 2..................................................... 4-100

4.21.3 Alternative C - MRGO Restoration Plan 7..................................................... 4-107

4.21.4 Alternative D - MRGO Restoration Plan 10 .................................................. 4-108

4.22 SOCIOECONOMIC AND HUMAN ENVIRONMENT ................................. 4-109

4.22.1 Population ....................................................................................................... 4-109
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4.22.1.1 Alternative A - No Action Plan .......................................................... 4-109

4.22.1.2 Alternative B - MRGO Restoration Plan 2 ........................................ 4-110

4.22.1.3 Alternative C - MRGO Restoration Plan 7 ....................................... 4-111

4.22.1.4 Alternative D - MRGO Restoration Plan 10 ..................................... 4-111

4.22.2 Community Cohesion ..................................................................................... 4-111

4.22.2.1 Alternative A - No Action Plan .......................................................... 4-111

4.22.2.2 Alternative B - MRGO Restoration Plan 2 ........................................ 4-111

4.22.2.3 Alternative C MRGO Restoration Plan 7 .......................................... 4-112

4.22.2.4 Alternative D MRGO Restoration Plan 10 ........................................ 4-112

4.22.3 Infrastructure .................................................................................................. 4-112

4.22.3.1 Alternative A - No Action Plan .......................................................... 4-112

4.22.3.2 Alternative B - MRGO Restoration Plan 2 ........................................ 4-113

4.22.3.3 Alternative C - MRGO Restoration Plan 7 ....................................... 4-114

4.22.3.4 Alternative D - MRGO Restoration Plan 10 ..................................... 4-114

4.22.4 Employment and Income................................................................................ 4-114

4.22.4.1 Alternative A - No Action Plan .......................................................... 4-114

4.22.4.2 Alternative B - MRGO Restoration Plan 2 ........................................ 4-115

4.22.4.3 Alternative C - MRGO Restoration Plan 7 ....................................... 4-115

4.22.4.4 Alternative D - MRGO Restoration Plan 10 ..................................... 4-116

4.22.5 Oil, Gas And Utilities ..................................................................................... 4-116

4.22.5.1 Alternative A - No Action Plan .......................................................... 4-116

4.22.5.2 Alternative B - MRGO Restoration Plan 2 ........................................ 4-116

4.22.5.3 Alternative C - MRGO Restoration Plan 7 ....................................... 4-117

4.22.5.4 Alternative D - MRGO Restoration Plan 10 ..................................... 4-117

4.22.6 Flood Control And Protection Levees ............................................................ 4-117

4.22.6.1 Alternative A - No Action Plan .......................................................... 4-117

4.22.6.2 Alternative B - MRGO Restoration Plan 2 ........................................ 4-118

4.22.6.3 Alternative C - MRGO Restoration Plan 7 ....................................... 4-119

4.22.6.4 Alternative D - MRGO Restoration Plan 10 ..................................... 4-119

4.23 ENVIRONMENTAL JUSTICE ........................................................................ 4-119

4.23.1 Alternative A - No Action Plan ...................................................................... 4-119

4.23.2 Alternative B - MRGO Restoration Plan 2..................................................... 4-120

4.23.3 Alternative C - MRGO Restoration Plan 7..................................................... 4-121

4.23.4 Alternative D - MRGO Restoration Plan 10 .................................................. 4-122

4.24 HISTORIC AND CULTURAL RESOURCES ................................................ 4-123

4.24.1 Alternative A - No Action Plan ...................................................................... 4-123

4.24.2 Alternative B - MRGO Restoration Plan 2..................................................... 4-123

4.24.3 Alternative C - MRGO Restoration Plan 7..................................................... 4-124

4.24.4 Alternative D - MRGO Restoration Plan 10 .................................................. 4-125

4.25 RECREATIONAL RESOURCES .................................................................... 4-126

4.25.1 Alternative A - No Action Plan ...................................................................... 4-126

4.25.2 Alternative B - MRGO Restoration Plan 2..................................................... 4-128

4.25.3 Alternative C - MRGO Restoration Plan 7..................................................... 4-132

4.25.4 Alternative D - MRGO Restoration Plan 10 .................................................. 4-132

4.26 AESTHETICS ..................................................................................................... 4-133

4.26.1 Alternative A - No Action Plan ...................................................................... 4-133

4.26.2 Alternative B - MRGO Restoration Plan 2..................................................... 4-134

4.26.3 Alternative C - MRGO Restoration Plan 7..................................................... 4-135

4.26.4 Alternative D - MRGO Restoration Plan 10 .................................................. 4-136

4.26.5 Scenic Streams ............................................................................................... 4-137

4.26.5.1 Alternative A - No Action Plan .......................................................... 4-137
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FEIS MRGO Ecosystem

Restoration Plan ix June 2012

4.26.5.2 Alternative B - MRGO Restoration Plan 2 ........................................ 4-138

4.26.5.3 Alternative C - MRGO Restoration Plan 7 ....................................... 4-140

4.26.5.4 Alternative D - MRGO Restoration Plan 11 ..................................... 4-141

4.27 FLOODPLAINS .................................................................................................. 4-142

4.27.1 Alternative A - No Action Plan ...................................................................... 4-142

4.27.2 Alternative B – MRGO Restoration Plan 2 .................................................... 4-142

4.27.3 Alternative C – MRGO Restoration Plan 7 .................................................... 4-143

4.27.4 Alternative D – MRGO Restoration Plan 10 .................................................. 4-144

4.28 ANY ADVERSE ENVIRONMENTAL IMPACTS WHICH CANNOT BE 

AVOIDED SHOULD THE TENTATIVELY SELECTED PLAN BE 

IMPLEMENTED ................................................................................................ 4-144

4.29 ANY IRREVERSIBLE AND IRRETRIEVABLE COMMITMENTS OF 

RESOURCES INVOLVED IN THE IMPLEMENTATION OF THE 

TENTATIVELY SELECTED PLAN ............................................................... 4-145

4.30 RELATIONSHIP BETWEEN LOCAL SHORT-TERM USES OF MAN’S 

ENVIRONMENT AND THE MAINTENANCE AND ENHANCEMENT OF 

LONG-TERM PRODUCTIVITY ..................................................................... 4-146

CHAPTER 5: PUBLIC INVOLVEMENT............................................................................... 5-1

5.1 GENERAL ............................................................................................................... 5-1

5.2 AGENCY COORDINATION ................................................................................ 5-1

5.3 PUBLIC INVOLVEMENT ACTIVITIES TO DATE ........................................ 5-2

5.3.1 Study Website .................................................................................................... 5-2

5.3.2 Scoping ............................................................................................................... 5-3

5.3.3 Summary of Major Scoping Issues .................................................................... 5-3

5.3.3.1 Use Sediment Diversions for Wetland Restoration ............................... 5-3

5.3.3.2 Restore the Ecosystem to Pre-Disturbance/Historical Condition ......... 5-3

5.3.3.3 Restoring the First Line of Hurricane Defense for Public Safety is a 

Priority .................................................................................................. 5-4

5.3.3.4 Focus on Restoring Flow of Water (Hydrology) ................................... 5-4

5.3.3.5 Implement/Incorporate Existing Plans .................................................. 5-4

5.3.4 Environmental Justice Public Outreach Efforts ................................................. 5-5

5.3.5 Public Meeting ................................................................................................... 5-5

5.4 STAKEHOLDER FORUM ................................................................................... 5-6

5.4.1 USACE Central Wetlands Forum ...................................................................... 5-6

5.4.2 USACE Recreation Forums ............................................................................... 5-6

5.4.3 USACE/Lake Pontchartrain Basin Foundation Ridge Restoration Workshop... 5-7

5.4.4 St. Bernard Parish Central Wetlands Workshop ................................................ 5-7

5.5 U.S. FISH AND WILDLIFE COORDINATION ................................................. 5-7

5.6 DRAFT ENVIRONMENTAL IMPACT STATEMENT .................................... 5-7

5.6.1 DEIS Public Hearings ........................................................................................ 5-8

5.6.2 DEIS Public/Agency Comment and Response................................................... 5-8

5.6.3 Final Environmental Impact Statement .............................................................. 5-9

5.6.4 Record Of Decision ............................................................................................ 5-9

CHAPTER 6: ENVIRONMENTAL REQUIREMENTS ....................................................... 6-1

6.1 CLEAN AIR ACT – AIR QUALITY DETERMINATION ................................ 6-1

6.2 CLEAN WATER ACT – SECTION 401 WATER QUALITY .......................... 6-1

6.3 CLEAN WATER ACT – SECTION 404(B)(1) .................................................... 6-3

6.4 COASTAL ZONE MANAGEMENT ACT OF 1972 ........................................... 6-3

6.5 FARMLAND PROTECTION POLICY ACT ..................................................... 6-3

6.6 FISH AND WILDLIFE COORDINATION ACT OF 1958 ................................ 6-4

6.6.1 Service Positions and Recommendations ........................................................... 6-4
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FEIS MRGO Ecosystem

Restoration Plan x June 2012

6.7 ENDANGERED SPECIES ACT OF 1973 ......................................................... 6-12

6.8 LOUISIANA STATE RARE, THREATENED AND ENDANGERED SPECIES, 

AND NATURAL COMMUNITIES COORDINATION ................................... 6-13

6.9 MAGNUSON-STEVENS FISHERY CONSERVATION AND MANAGEMENT 

ACT OF 1996 AND THE MAGNUSON-STEVENS ACT 

REAUTHORIZATION OF 2006 (ESSENTIAL FISH HABITAT) ................. 6-13

6.9.1 NOAA/NMFS .................................................................................................. 6-14

6.10 MIGRATORY BIRD TREATY ACT AND MIGRATORY BIRD 

CONSERVATION ACT ...................................................................................... 6-15

6.11 NATIONAL HISTORIC PRESERVATION ACT OF 1966 ............................ 6-16

6.12 RESOURCE CONSERVATON AND RECOVERY ACT (RCRA) AS 

AMENDED BY THE HAZARDOUS AND SOLID WASTE AMENDMENTS 

(HSWA) OF 1984 .................................................................................................. 6-16

6.13 EXECUTIVE ORDER 11988, FLOOD PLAIN MANAGEMENT .................. 6-17

6.14 EXECUTIVE ORDER 11514, PROTECTION OF ENVIRONMENT ........... 6-17

6.15 EXECUTIVE ORDER 11990, PROTECTION OF WETLANDS ................... 6-17

6.16 EXECUTIVE ORDER 13186, MIGRATORY BIRD HABITAT PROTECTION6-17

6.17 EXECUTIVE ORDER 12898, ENVIRONMENTAL JUSTICE ...................... 6-18

6.18 EXECUTIVE ORDER 13112, INVASIVE SPECIES ....................................... 6-19

6.19 WILD AND SCENIC RIVER ACT OF 1968 ..................................................... 6-19

6.20 MARINE MAMMAL PROTECTION ACT OF 1972 ...................................... 6-19

CHAPTER 7: CONCLUSIONS AND RECOMMENDATIONS .......................................... 7-1

7.1 AREAS OF CONTROVERSY AND UNRESOLVED ISSUES ......................... 7-1

7.1.1 Proposed Violet, Louisiana Freshwater Diversion ............................................. 7-1

7.1.2 Deepwater Horizon Oil Spill .............................................................................. 7-2

7.2 CONCLUSIONS ..................................................................................................... 7-3

7.3 RECOMMENDATIONS ........................................................................................ 7-4

CHAPTER 8: DISTRIBUTION LIST AND OTHER ............................................................. 8-1

8.1 DISTRIBUTION LIST ........................................................................................... 8-1

8.2 LIST OF PREPARERS .......................................................................................... 8-1

8.3 LITERATURE CITED .......................................................................................... 8-4

8.4 GLOSSARY .......................................................................................................... 8-19

8.5 ACRONYMS, ABBREVIATONS AND SYMBOLS ......................................... 8-30

8.6 INDEX.................................................................................................................... 8-37

TABLES

Table 1-1: Subunits by Geographic Area and Their Relevance to the MRGO Ecosystem 

Restoration Plan ........................................................................................................ 1-8

Table 1-2: Problems in Initial Feature Subunits ........................................................................ 1-10

Table 1-3: Direct and Indirect Habitat Impacts of the MRGO .................................................. 1-14

Table 1-4: Pre- and Post-MRGO Salinity (ppt) ......................................................................... 1-16

Table 1-5: Land Loss Rates ....................................................................................................... 1-18

Table 1-6: Goals, Objectives, Metrics and Measures ................................................................. 1-26

Table 1-7: Monthly Salinity Targets ......................................................................................... 1-28

Table 1-8: Habitat Targets (in area) .......................................................................................... 1-29

Table 1-9: Scoping Comment Themes by Percentage of Occurrence ....................................... 1-37

Table 1-10: Compliance with Environmental Laws, Regulations and Executive Orders ......... 1-38

Table 2-1: Effects of MRGO and Selected Ecosystem Restoration Measures on Selected Issues 

and Drivers in the MRGO Study Area ...................................................................... 2-6

Table 2-2: Steps 3 and 4: Freshwater Diversion Measures ....................................................... 2-17
Table of Contents 

FEIS MRGO Ecosystem

Restoration Plan xi June 2012

Table 2-3: Steps 3 and 4: Hydrologic Restoration Measures .................................................... 2-22

Table 2-4: Steps 3 and 4: Marsh and Swamp Restoration Measures ........................................ 2-25

Table 2-5: Steps 3 and 4: Shoreline Protection Measures ......................................................... 2-27

Table 2-6: Steps 3 and 4: Ridge Restoration Measures ............................................................. 2-29

Table 2-7: Steps 3 and 4: Vegetative Planting Measures .......................................................... 2-31

Table 2-8: Steps 3 and 4: Barrier Island Measures ..................................................................... 2-32

Table 2-9: Steps 3 and 4: SAV Measures .................................................................................. 2-32

Table 2-10: Steps 3 and 4: Oyster Reef Measures..................................................................... 2-33

Table 2-11: Summary of Barrier Island Restoration Alternative Benefits and Costs ............... 2-34

Table 2-12: Sustainability Under Relative Sea Level Rise by Feature ..................................... 2-48

Table 2-13: Robustness of Features in Tentatively Selected Plan Under all Relative Sea Level 

Rise Scenarios ......................................................................................................... 2-49

Table 2-14: Measures Retained for Plan Formulation ............................................................... 2-51

Table 2-15: Best Buy Plan Descriptions.................................................................................... 2-58

Table 2-16: Best Buy Plans ....................................................................................................... 2-58

Table 2-17: Final Array of Alternatives ..................................................................................... 2-61

Table 2-18: Restoration Features Included in the Final Array ................................................... 2-61

Table 2-19: Base and Predicted FWOP Salinity Range for Lake Borgne Ecosystem ............... 2-75

Table 2-20: Diversion Scenarios: Percent of Time Salinity Targets are Met ............................ 2-78

Table 2-21: Alternative Violet, Louisiana Freshwater Diversion Location Comparison .......... 2-81

Table 2-22: Final Array of WVA Results ................................................................................. 2-93

Table 2-23: Relative Sustainability of Features ........................................................................ 2-97

Table 2-24: Sustainability under Relative Sea Level Rise by Feature ...................................... 2-99

Table 2-25: Comparison of Alternatives to Study Objectives ................................................. 2-101

Table 2-26: Robustness of Features in TSP under all Relative Sea Level Rise Scenarios* .... 2-115

Table 2-27: Adaptive Management Threshold and Trigger Matrix ........................................ 2-117

Table 2-28: Implementation Table1

 ......................................................................................... 2-118

Table 2-29: Relative Sea Level Rise Projections Over the Period of Analysis ....................... 2-128

Table 2-30: Wetland Value Assessment Sensitivity Levels .................................................... 2-137

Table 3-1: Significant Resource and Institutional Recognition ................................................... 3-2

Table 3-2: 2008 Louisiana Water Quality – 303(d) List ........................................................... 3-14

Table 3-3: Summary of Use Support Categories ....................................................................... 3-15

Table 3-4: Mississippi River Group General Summary Statistics from 1990-2010 .................. 3-17

Table 3-5: Central Wetlands Area Group General Summary Statistics from 1990-2010 ......... 3-20

Table 3-6: MRGO Group General Summary Statistics from 1990-2010 .................................. 3-21

Table 3-7: LBWA Group General Summary Statistics from 1990-2010 .................................. 3-22

Table 3-8: Lake Borgne Group General Summary Statistics from 1990-2010 ......................... 3-23

Table 3-9: Biloxi Marsh Group General Summary Statistics from 1990-2010 ......................... 3-24

Table 3-10: Mississippi Coastal Area Water Quality Indicators ............................................... 3-26

Table 3-11: 2008 Mississippi Water Quality Assessment – 303(d) List ................................... 3-28

Table 3-12: Mean Salinity Data from Stations Affected by MRGO ......................................... 3-30

Table 3-13: MRGO Influence on Salinity Regime .................................................................... 3-32

Table 3-14: MRGO Closure Influence on Salinity Regime ...................................................... 3-33

Table 3-15: Salinity for Pre- and Post-MRGO Salinity (ppt) .................................................... 3-35

Table 3-16: Existing Salinity in St. Louis Bay .......................................................................... 3-36

Table 3-17: Existing Salinity in Biloxi Bay .............................................................................. 3-37

Table 3-18: Existing Salinity in Pascagoula Bay ...................................................................... 3-38

Table 3-19: Dominant Soil Series of the Study Area ................................................................ 3-43

Table 3-20: National Ambient Air Quality Standards for the Seven Criteria Pollutants .......... 3-52

Table 3-21: Invasive Species Occurring in Coastal Vegetation ................................................ 3-73

Table 3-22: Estimated Annual Number of Wetland Acres Damaged by Nutria ....................... 3-74
Table of Contents 

FEIS MRGO Ecosystem

Restoration Plan xii June 2012

Table 3-23: Status, Functions of Interest, Trends, and Projections through 2050 for Avifauna, 

Furbearers, Game Mammals, and Reptiles within the Project Area (LCWCRTF & 

WCRA, 1999) ......................................................................................................... 3-81

Table 3-24: Annual Landing Statistics for all Fisheries Species Combined for the State of 

Louisiana, 2005 – 2008 ........................................................................................... 3-86

Table 3-25: Dollar Value of Representative Game and Commercial Fisheries Species Occurring 

in Louisiana and Mississippi Territorial Waters ..................................................... 3-86

Table 3-26: Life Stages of Federally Managed Species and EFH Present in the Project Area . 3-92

Table 3-27: Representative Categories of EFH Known to Occur Within the Gulf of Mexico 

Region (Louisiana and Mississippi Territorial Waters) .......................................... 3-93

Table 3-28: Threatened and Endangered Species ...................................................................... 3-99

Table 3-29: 2008 Estimated Population – Post Katrina .......................................................... 3-104

Table 3-30: July 2009 Census Populations of Cities and Towns near the Project Area ......... 3-105

Table 3-31: Tenure by Year Householder Moved into Unit for Owner-Occupied Housing Units 

(%) ........................................................................................................................ 3-105

Table 3-32: MRGO Utility Crossings and Owners ................................................................. 3-107

Table 3-33: FY 2008 Boater Registrations, Fishing / Hunting Licenses ................................. 3-116

Table 3-34: LWCF Expenditures in Study Area for Recreational Resources ......................... 3-119

Table 3-35: State and Federal Recreation Areas ..................................................................... 3-120

Table 4-1: Evaluation of Potential Impacts to Significant Resources by Alternative ................. 4-4

Table 4-2: Total (Worst Case) Air Emissions (tons/year) from Alternative B Construction 

Activities Pollutant Total (tons/year) ...................................................................... 4-42

Table 4-3: Total (Worst Case) Air Emissions (tons/year) from Alternative C Construction 

Activities Pollutant Total (tons/year) ...................................................................... 4-45

Table 5-1: MRGO DEIS Public Hearing Summary .................................................................... 5-8

Table 6-1: Relevant Federal Statutory Authorities and Executive Orders .................................. 6-2

Table 6-2: Relevant State Statutory Authorities .......................................................................... 6-3

FIGURES

Figure S-1: Alternative C, Tentatively Selected Plan .............................................................. ES-11

Figure 1-1: Study Area - Ponchartrain Basin and Western Mississippi Sound ........................... 1-4

Figure 1-2: MRGO Planning Subunits ........................................................................................ 1-6

Figure 1-3: MRGO Navigation Channel ................................................................................... 1-11

Figure 1-4: MRGO Closure Structure at Bayou La Loutre ....................................................... 1-12

Figure 1-5: Construction of MRGO Channel (1959) ................................................................ 1-13

Figure 1-6: Salinity Impacts of the MRGO ............................................................................... 1-17

Figure 1-7: Average Shoreline Retreat Rates ............................................................................ 1-19

Figure 1-8: Potential Pathways of Change among Habitats and the Associated Driving Forces1-20

Figure 1-9: Aerial View of Breton Island (2009) ...................................................................... 1-22

Figure 1-10: Salinity Line (Chatry Line) Depicted Across Biloxi Marsh ................................. 1-25

Figure 1-11: Salinity Target ...................................................................................................... 1-25

Figure 2-1: Initial Restoration Measures Considered ................................................................ 2-12

Figure 2-2: Freshwater Diversion Location Constraints ........................................................... 2-20

Figure 2-3: Actual and Predicted Acreage for Subunit 17 ........................................................ 2-39

Figure 2-4: Marsh Restoration Net Benefits.............................................................................. 2-44

Figure 2-5: Marsh Nourishment Net Benefits ........................................................................... 2-45

Figure 2-6: Shoreline Protection Net Benefits .......................................................................... 2-46

Figure 2-7: Alternative Diversion Locations ............................................................................. 2-66

Figure 2-8: Bienvenue Triangle Overlook Recreational Feature – Option A............................ 2-68

Figure 2-9: Violet, Louisiana Freshwater Diversion Recreational Feature – Option B ............ 2-70
Table of Contents 

FEIS MRGO Ecosystem

Restoration Plan xiii June 2012

Figure 2-10: Shell Beach Recreational Feature – Option B ...................................................... 2-71

Figure 2-11: IHNC Surge Barrier .............................................................................................. 2-72

Figure 2-12: Alternative Locations for the Violet, Louisiana Freshwater Diversion Considered in 

Initial Analysis ........................................................................................................ 2-81

Figure 2-13: Alternative Location 1 .......................................................................................... 2-82

Figure 2-14: Alternative Location 2 .......................................................................................... 2-83

Figure 2-15: Alternative Location 3 .......................................................................................... 2-84

Figure 2-16: Alternative Location 4 .......................................................................................... 2-85

Figure 2-17: Alternative Location 1 for the Violet Freshwater Diversion ................................ 2-88

Figure 2-18: Alternative B – MRGO Restoration Plan 2 .......................................................... 2-89

Figure 2-19: Alternative C – MRGO Restoration Plan 7 .......................................................... 2-90

Figure 2-20: Alternative D – MRGO Restoration Plan 10 ........................................................ 2-91

Figure 2-21: Oyster Reef Alternative - Loose Oyster Shells ................................................... 2-109

Figure 2-22: Oyster Reef Alternative - Interlocking, Triangular Welded Steel Structures ..... 2-110

Figure 2-23: Oyster Reef Alternative - Interlocking Concrete Rings...................................... 2-111

Figure 2-24: MRGO Tentatively Selected Plan Implementation Timetable ........................... 2-121

Figure 2-25: Borrow Sites for Tentatively Selected Plan ........................................................ 2-123

Figure 3-1: MRGO Closure Structure at Bayou La Loutre Completed July, 2009 ..................... 3-1

Figure 3-2: Study Area – Pontchartrain Basin and Western Mississippi Sound ......................... 3-4

Figure 3-3: Mississippi Deltaic Region (Coast 2050) ................................................................. 3-5

Figure 3-4: Marginal Deltaic Basin ............................................................................................. 3-6

Figure 3-5: Mississippi River Deltaic Region ............................................................................. 3-7

Figure 3-6: Site Location Map – Gulf Coast Water Quality Monitoring .................................. 3-27

Figure 3-7: Primary Area Station Locations.............................................................................. 3-31

Figure 3-8: Site Location Map – St. Louis Bay and Associated Waterways ............................ 3-37

Figure 3-9: Site Location Map – Back Bay of Biloxi ................................................................ 3-38

Figure 3-10: Site Location Map – Pascagoula, Escatawpa, West Pascagoula Rivers ............... 3-39

Figure 3-11: Distribution of Hydric Soils in Study Area – Pontchartrain Basin and Western 

Mississippi Sound ................................................................................................... 3-44

Figure 3-12: Chandeleur Islands, Breton Island, and Breton Sound ......................................... 3-57

Figure 3-13: Shoreline Configuration and Bathymetry for the 1920s ....................................... 3-58

Figure 3-14: Shoreline Configuration and Bathymetry for 2005 .............................................. 3-59

Figure 3-15: Land Cover in Study Area .................................................................................... 3-67

Figure 3-16: Vegetation Types .................................................................................................. 3-68

Figure 3-17: Nutria Damage in Louisiana Marsh (Louisiana Department of Wildlife and 

Fisheries) ................................................................................................................. 3-74

Figure 3-18: Location of Oyster Reefs and Seeding Grounds within the Louisiana Portion of the 

Project Area (Outlines in Purple) ............................................................................ 3-88

Figure 3-19: Location of Oyster Reefs and Seeding Grounds within the Mississippi Territorial 

Waters ..................................................................................................................... 3-89

Figure 3-20: Utility Crossings in and near the Project Area ................................................... 3-107

Figure 3-21: Pipelines and Oil and Gas Wells in Lake Borgne and Vicinity .......................... 3-108

Figure 3-22: Flood Protection Features near the Project Area ................................................ 3-109

Figure 3-23: Bayou Sauvage near Highway 90 ....................................................................... 3-121

Figure 3-24: Bayou Sauvage near Highway 90 ....................................................................... 3-122

Figure 3-25: Central Wetlands from I-510 .............................................................................. 3-123

Figure 3-26: Central Wetlands from I-510 .............................................................................. 3-123

Figure 3-27: Terre aux Boeufs near LA 624 ........................................................................... 3-126

Figure 3-28: Terre aux Boeufs near LA 624 ........................................................................... 3-126

Figure 3-29: Scenic Streams and Central Wetlands Area ....................................................... 3-130
Table of Contents 

FEIS MRGO Ecosystem

Restoration Plan xiv June 2012

Figure 4-1: Distribution of Soil Types and Farmland (Prime and Non-Prime) in the Vicinity of 

the Proposed Violet, Louisiana Freshwater Diversion Channel ............................. 4-36

APPENDICES

APPENDIX A SCOPING REPORT

APPENDIX B USFWS COORDINATION / FWCAR

APPENDIX C NMFS COORDINATION

APPENDIX D CULTURAL RESOURCES COORDINATION

APPENDIX E 404(b)(1) DRAFT

APPENDIX F COASTAL ZONE CONSISTENCY (DRAFT)

APPENDIX G TREATENED AND ENDANGERED SPECIES CONSULTATION

APPENDIX H CONCEPTUAL ECOLOGICAL MODEL REPORT

APPENDIX I AQUATICS MODEL REPORT (CASM)

APPENDIX J BARRIER ISLAND MODEL REPORT (SBEACH)

APPENDIX K DISTRIBUTION LIST

APPENDIX L H&H MODEL REPORT

APPENDIX M WETLAND VALUE ASSESSMENT AND OPERATIONS SCHEME

APPENDIX N SALINITY WORKING GROUP REPORT

APPENDIX O MEASURES AND ALTERNATIVES SCREENING TABLES

APPENDIX P AIR QUALITY IMPACTS

APPENDIX Q PHASE I ESA / HTRW REPORT

APPENDIX R PRIME AND UNIQUE FARMLANDS / NRCS FORMS

APPENDIX S WATER QUALITY

APPENDIX T ADAPTIVE MANAGEMENT PLAN

APPENDIX U ENGINEERING DESIGN FOOTPRINTS / MEASURES

APPENDIX V HABITAT IMPACTS OF CONSTRUCTION OF THE MRGO

APPENDIX W RECREATION PLAN DEVELOPMENT

APPENDIX X SCENIC STREAMS

APPENDIX Y PUBLIC HEARING RECORD AND DEIS COMMENT SUMMARY

APPENDIX Z PLANTING PLAN
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-1 June 2012

EXECUTIVE SUMMARY

S.1 INTRODUCTION

This Final Environmental Impact Statement (FEIS) for the Mississippi River Gulf Outlet 

(hereafter MRGO) Ecosystem Restoration Plan Feasibility Report was prepared by the 

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

District (CEMVN). It includes input from Federal, as well as Louisiana and Mississippi

state agencies.

The National Environmental Policy Act (NEPA) of 1969 (Public Law 91-190) requires 

all Federal agencies to address environmental consequences of major Federal actions on 

the natural and human environment. Compliance guidance for NEPA is contained in 

Title 40 of the Code of Federal Regulations (CFR), Parts 1500 through 1508, and in the 

USACE regulations 33 CFR 230 and 325, Environmental Quality and Procedures for 

Implementing NEPA. The primary intent of NEPA is to ensure that environmental 

information is made available to officials and citizens regarding major Federal actions.

This FEIS was prepared as an update to the Draft EIS (December 2010) that was 

conducted to assess the viable alternatives identified as part of the MRGO Ecosystem 

Restoration Plan Feasibility Report. The feasibility report will accompany this FEIS; the 

reports are companion documents. Plans were evaluated based on their ability to meet 

the study goals and objectives, compliance with environmental laws, contributions to the 

Federal objective of National Ecosystem Restoration (NER), and meeting the evaluation 

criteria of completeness, effectiveness, efficiency and acceptability. 

Through evaluation and impact assessment, the feasibility report and FEIS will identify 

the tentatively selected plan that is the NER plan. Selecting the NER plan required

careful consideration of planning goals, objectives, and constraints. The NER plan 

reasonably maximizes environmental benefits while passing tests of cost effectiveness 

and incremental cost analyses, significance of outputs and their ability to meet the 

evaluation criteria. The Water Resources Development Act of 2007 (WRDA 2007) 

requires the plan to be cost effective, environmentally acceptable, and technically feasible 

in order to be carried out by the Secretary of the Army. 

S.2 PURPOSE AND NEED FOR ACTION

The purpose of this study was to develop a comprehensive ecosystem restoration plan to 

restore the Lake Borgne ecosystem and the areas affected by the MRGO navigation 

channel as required by Section 7013 of WRDA 2007. The period of analysis is from 

implementation and extends 50 years into the future from the estimated first year of 

construction, 2015 to 2065. 
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-2 June 2012

The main water resource problems identified in the study area include: 

• 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. 

The natural flow and drainage patterns have been impacted by a complex levee system 

throughout the area, drainage channels, pipelines and other utilities, roadways, and most 

importantly navigation channels. Channels and other canals serve as a conduit for tidal 

flow and saltwater intrusion, subjecting the sensitive marsh to the erosive forces of wind 

and wave action.

S.3 STUDY AUTHORITY AND STUDY SPONSOR

The study is authorized by the Water Resources Development Act 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; 

• integrates the recommendations of the Louisiana Coastal Area (LCA) Report and 

the Louisiana Coastal Protection and Restoration (LACPR) Technical Report; 

• consider the use of native vegetation and diversions of freshwater to restore the 

Lake Borgne ecosystem.

The WRDA 2007 Section 7013 features of the MRGO plan in Tiers 1 and 2, as described 

in the 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, are 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 cost 

sharing sponsor(s) will be identified as required by 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), The Tier 3 feature, consisting of the Violet, Louisiana Freshwater Diversion 

project, as authorized by Section 3083 of WRDA 2007 (Tier 3A), as well as certain 
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-3 June 2012

MRGO Ecosystem Restoration features authorized by Section 7013 of WRDA 2007 (but 

which are dependent upon the implementation of a freshwater diversion at or in the 

vicinity of Violet (Tier3B)), are recommended in the report for additional feasibility 

study and analysis. 

The Section 7013 MRGO ecosystem restoration study is 100% Federally funded. Despite 

lengthy discussions with the State of Louisiana, the Government has been unable to 

identify a non-Federal sonsor for design and implementation of the Section 7013 Section 

3083 of WRDA 2007 conditionally authorizes the the Violet, Louisiana Freshwater 

Diversion project and identifies the State of Mississippi and the State of Louisiana as the 

non-Federal sponsors for that project. Both states have been actively participating on the 

planning team. . USACE will continue, pursuant to Section 3083 of WRDA 2007, to 

coordinate with the State of Louisiana and the State of Mississippi during the further 

feasibility study for the Violet, Louisiana Freshwater Diversion project and with the State 

of Louisiana regarding those Section 7013 elements of the MRGO Ecosystem 

Restoration project that are determined by USACE to be dependent upon the design and 

implementation of the Violet diversion. 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) requires the 

execution of a binding written agreement by the State of Louisiana and the State of 

Mississippi in order for the United States to commence construction. 

S.4 STUDY AREA

The study area includes portions of the Mississippi River Deltaic Plain within coastal 

southeast Louisiana and parts of southwest Mississippi encompassing approximately 3.84 

million acres (over 6,000 square miles). 

In Louisiana, the study area includes the Pontchartrain Basin, which is comprised of the 

Upper, Middle, and Lower sub-basins. The Upper Pontchartrain sub-basin includes Lake 

Maurepas and its adjacent wetlands and swamps. Lake Maurepas receives its freshwater 

influences from the Amite and Tickfaw Rivers, Bayou Manchac, and other smaller rivers. 

The Middle Pontchartrain sub-basin is comprised of Lake Pontchartrain, its adjacent 

cities and towns, and surrounding wetlands. Lake Pontchartrain is affected by freshwater 

inflows from Pass Manchac, North Pass, and the Tangipahoa, Tchefuncte, and Bogue 

Falaya Rivers, some bayous, and the Bonnet Carré Spillway. The Lower Pontchartrain 

sub-basin includes Lake Borgne, the deauthorized MRGO, the Mississippi River, 

Chandeleur and Breton Sounds, portions of the Gulf of Mexico, and the surrounding 

wetlands, barrier islands, and communities. Lake Borgne is hydrologically linked to 

Lake Pontchartrain through tidal passes at the Rigolets, Chef Menteur Pass, and the 

manmade Inner Harbor Navigation Canal (IHNC). The Lake Borgne ecosystem is also 

influenced by the Pearl River to the north and receives hydrologic interchange from areas 

located as far west as Bayou Terre aux Boeufs Ridge, which is located between the 

MRGO and the Mississippi River. Major navigation channels include the Mississippi 

River, IHNC, and the Gulf Intracoastal Waterway (GIWW). 
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-4 June 2012

In Mississippi, the study area includes the Western Mississippi Sound, its bordering 

wetlands, and Cat Island. 

S.5 PUBLIC INVOLVEMENT

The USACE invites full public participation in the NEPA process and promotes open 

communication for better decision-making. A scoping comment period began with the 

filing of the Notice of Intent (NOI) and continued through release of the Draft EIS 

(DEIS). Public scoping meetings were held on November 3, 2008, in Chalmette, LA and 

November 6, 2008, in Waveland, MS. Public meetings were held February 23, 2010 and 

April 20, 2010, in New Orleans, LA, to study alternatives for a freshwater diversion 

proposed in the vicinity of Violet, LA, and receive comments from the public. Agencies 

were invited by email on August 27, 2008, and by letter dated October 23, 2008, to 

participate in the study as cooperating agencies and provide a team member for the 

Project Delivery Team (PDT) as well as the Habitat Evaluation Team (HET). 

The DEIS was released to the public following a Notice of Availability (NOA) that was 

published in the Federal Register on December 17, 2010. A NOA letter was mailed to 

the USACE New Orleans District stakeholder and NEPA mailing lists 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 companion MRGO Ecosystem Restoration Plan 

Feasibility Report. 

Following the NOA, the USACE held three Public Hearings as an opportunity for the 

public, resource 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, coupled with an overwhelming response. The final date for the acceptance of 

comments was established on March 5, 2011, resulting in an overall 78-day comment

period. 

During the comment period, over 31,400 commenters provided written and/or verbal 

comments on one subject matter alone – Support of Plan Elements. The large comment 

response was primarily attributed to approximately 31,270 individual commenter’s 

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. 
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-5 June 2012

S.6 AREAS OF CONTROVERSY AND UNRESOLVED 

ISSUES

Construction and operation of the MRGO, in synergistic combination with other natural 

and man-made factors, has caused direct, indirect and cumulative land loss, shoreline 

erosion, saltwater intrusion, habitat modification, and impacts to wildlife and fisheries 

resources throughout the project area. Determining the extent to which the MRGO 

contributed to these impacts and what, if any, actions would be necessary to remediate any 

such impacts remains a controversial issue.

The communities surrounding the MRGO include minority and/or low-income to nonminority and non-low income populations. The location of the proposed Violet, 

Louisiana Freshwater Diversion would be constructed in an open field that sits between 

two subdivisions that are predominately minority and/or low-income populations. 

Construction efforts such as noise, dust, traffic delays, etc., would temporarily impact 

those in the immediate project vicinity as well as other groups that work or live in the 

surrounding area. While many of the residents support marsh creation and restoration in 

the project area, some were opposed to the location of the proposed diversion location. 

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

uncertain at this time (May 2012). The impacts of the oil spill could potentially impact 

USACE water resources projects and studies within the Louisiana coastal area, including 

the MRGO Ecosystem Restoration project. Potential impacts could include factors such 

as changes to existing, future-without, and future-with-project conditions, as well as 

increased project costs and implementation delays. The USACE will continue to monitor 

and closely coordinate with other Federal and state resource agencies and local sponsors 

in determining how to best address any potential problems associated with the oil spill 

that may adversely impact projects and studies. Supplemental planning and 

environmental documentation may be required as information becomes available. 

S.7 RESTORATION GOALS

Restoring natural processes, such as reconnecting the floodplain with the Mississippi 

River system’s hydrologic cycles, is the key to restoring the ecosystem and improving 

productivity. Restoring some degree of these natural processes holds the best promise for 

significant improvements to the Deltaic processes in the lower Mississippi River system. 

Priority was given to restoration measures that contributed to restoring natural processes. 

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. 
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-6 June 2012

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 special 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 

Bouefs, 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. 

S.8 MANAGEMENT MEASURES AND ALTERNATIVES

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 measurers to form alternative plans. Measures were developed to address 

study area problems and to capitalize on study area opportunities. Management measures 

were derived from a variety of sources including prior studies, the NEPA public scoping 

process, and the multidisciplinary, interagency Project Delivery Team (PDT), and other 

private, local government, and landowner groups. Approximately 300 initial structural 

management measures considered can be grouped into the following categories: (nonstructural 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 restoration, marsh nourishment, and swamp restoration

• Shoreline protection 

• Ridge restoration 

• Restoration/creation of forested habitat

• Barrier island restoration

• Submerged aquatic vegetation (SAV) restoration 

• Oyster reef restoration

• Vegetative planting
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-7 June 2012

Alternatives were formulated to maximize environmental benefits, minimize 

environmental impacts and costs. A Cost Effectiveness/Incremental Cost Analysis 

(CE/ICA) was conducted to evaluate the benefits of alternative plans as related to cost 

and identify the plans that provide the greatest benefits with the least amount of 

incremental cost. The subset of cost effective plans were examined sequentially (by 

increasing scale and increment of output) to determine which plans were more efficient 

and achieved the greatest benefits. These plans are called “Best Buy Plans.” The Corps’ 

Institute for Water Resources (IWR)-PLAN Decision Support Software was used to 

generate 6,721 plan combinations. Including the no action plan (alternative A), there 

were 285 cost-effective plans and 19 Best Buy plans. Three Best Buy plans were 

selected as the final array of alternatives. Best Buy plans #2, #7, and #10 (alternatives B, 

C, and D, respectively) were chosen based on cost effective increments based on their 

contribution to addressing the study authority and achieving the planning objectives. 

These three plans provide a wide range of costs and outputs. 

Best Buy Plan #2 (alternative B) was chosen for further consideration because it was the 

least costly Best Buy Plan. Alternative B does not achieve all of the goals of the study, 

but it does include some restoration measures for all of the targeted habitat types. 

Alternative B would restore or protect 19,630 acres of marsh and 10,318 acres of cypress 

swamp. Alternative 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 by 

compensating for any habitat switching. Alternative B has no features in the Biloxi 

Marsh and only includes two features on the East Orleans Landbridge; therefore, 

alternative B does not fully address the objective to restore and protect critical landscape 

features for storm surge reduction. 

Best Buy Plan #7 (alternative 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. Therefore, alternative 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. 

Best Buy Plan #8 (alternative D) includes additional marsh creation features and 

additional shoreline protection in the Biloxi Marsh and East Orleans Landbridge. 

Alternative D improves upon alternative C by further protecting these critical landscape 

features, and better meets the storm surge objective. Alternative D was included for 

further evaluation because it was the first Best Buy Plan after alternative C to include 

more measures to protect both of these areas. 

S.9 COMPARISON OF IMPACTS 

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

impacts with respect to study goals and objectives and NER objectives. A brief summary 

of the benefits and impacts associated with each alternative is discussed below. 
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-8 June 2012

Alternative A. The no action alternative is required by the NEPA and represents the 

future without project (FWOP) condition to compare to the final array of alternatives. 

The no action alternative considers restoration programs that would continue into the 

future and are currently authorized under the Coastal Wetlands Planning, Protection and 

Restoration Act (CWPPRA), Coastal Impact Assistance Program (CIAP), the LCA

Ecosystem Restoration Study, and other programs. 

Alternative B. Alternative B would restore approximately 54 acres of ridge habitat 

along Bayou La Loutre in the Biloxi Marsh area, provide 122 acres of shoreline 

protection, restore 10,318 acres of cypress swamp habitat in the Central Wetlands, and 

restore 19,630 acres of wetlands in the Lower Pontchartrain sub-basin. The Violet, 

Louisiana Freshwater Diversion, pulsing 7,000 cubic feet per second (cfs) from April to 

May would influence approximately 115,078 acres. The diversion channel would result 

in the loss of 302 acres of prime/unique farmland and 227 acres of wetland. Restoration 

of the Bayou La Loutre Ridge would result in permanent impacts to 54 acres of brackish 

marsh. 

Alternative C. Alternative C would restore approximately 54 acres of ridge habitat in 

the Biloxi Marsh area, provide 1,937 acres of shoreline protection, restore 10,318 acres of 

cypress swamp habitat in the Central Wetlands, and restore 44,188 acres of wetlands in 

the lower Pontchartrain sub-basin. The Violet Freshwater Diversion, pulsing 7,000 cfs 

from April to May would influence approximately 115,078 acres. The diversion channel 

would result in the loss of 302 acres of prime/unique farmland and 227 acres of wetland. 

Restoration of the Bayou La Loutre Ridge would result in permanent impacts to 54 acres 

of brackish marsh. 

Alternative D. Alternative D would restore approximately 54 acres of ridge habitat in 

the Biloxi Marsh area, provide 2,494 acres of shoreline protection, restore 10,318 acres of 

cypress swamp habitat in the Central Wetlands, and restore 44,892acres of wetlands in 

the lower Pontchartrain sub-basin. The Violet, Louisiana Freshwater Diversion, pulsing 

7,000 cfs from April to May would influence approximately 115,078 acres. The 

diversion channel would result in the loss of 302 acres of prime/unique farmland and 227 

acres of wetland. Restoration of the Bayou La Loutre Ridge would result in permanent 

impacts to 54 acres of brackish marsh. 

Impacts by alternative and resource are described in table S-1. 

S.10 TENTATIVELY SELECTED PLAN

Alternative C (Figure S-1) was chosen as the tentatively selected plan based on 

preliminary analysis 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 

tentatively selected plan (TSP) is referenced as the federally identified plan (FIP) in the 

Feasibility Report. The National Ecosystem Restoration account is best achieved by 
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-9 June 2012

alternative 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. 

Alternative 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. 

Alternative 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 alternative 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. Alternative C addresses some of the salinity impacts of the MRGO by 

recommending further analysis of the Violet Freshwater Diversion.

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 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. 

Tiered Implementation Sequence

Plan recommendations include features recommended for construction (contingent upon 

the identification of a non-Federal sponsor), features recommended for contingent 

authorization subject to a decision document showing that necessary conditions have 

been met, features recommended for additional study, and a Monitoring and Adaptive 

Management Plan.
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-10 June 2012

• 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 (in red on Figure S1). 

• 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. 

• 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. 

Assumptions factoring into the implementation sequence include elements such as 

production rates for building rock projects and issues like dredge equipment availability 

for use in marsh creation. Other implementation sequencing factors include 

considerations such as land loss rates (areas with higher land loss rates are proposed for 

construction first), required construction work order, and the limitation of alternating 

dredging cycles in the lobes of Lake Borgne. Shore protection work in an area subject to 

wave erosion would be constructed before creating a restored marsh in the same area to 

address the driving erosive factor first to improve the sustainability of restored marshes. 

Shoreline protection, marsh restoration and nourishment, and ridge restoration features 

are recommended for construction, contingent upon the identification of a non-Federal 

sponsor. There is significant institutional knowledge regarding the construction of 

shoreline protection and marsh restoration features, and therefore further investigation of 

these features is not required. These features have been developed to a feasibility level of 

design, are critical to the stabilization and restoration of the study area, and are proposed 

to be constructed first. 

Because salinity conditions in the area are changing, many features are delayed until further 

analysis can confirm that necessary conditions have been met. If data indicate that conditions 

prohibit the successful implementation of features in Tier 2, they will be deferred until longterm data indicate that they can be sustainably built.

The Violet, Louisiana Freshwater Diversion requires additional study to develop the feature to 

a feasibility level of detail, and is therefore recommended for further analysis. Plan features 

that require a freshwater diversion to be sustainable are recommended for further analysis in 

conjunction with the Violet Freshwater Diversion.
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-11 June 2012

Figure S-1: Alternative C, Tentatively Selected Plan
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-12 June 2012

Table S-1: Evaluation of Potential Impacts to Significant Resources by Alternative

Environmental 

Resources

Alternatives

Alternative A

No Action Alternative B Alternative C Alternative D

HYDROLOGY AND 

HYDRAULICS (H&H)

No direct impacts. Indirect and cumulative 

impacts include altered flow patterns, altered 

paths of tidal propagation, and loss of tidal 

connection. Slight reduction in salinity due 

to other projects. Continued loss of 

wetlands is expected due to lack of hydraulic 

connectivity and sediment source, as well 

salinity levels. 

Flow velocities would be negligibly 

increased as a result of 1,000 cubic feet 

per second (cfs) background flow and 

would not impede fish passage. 

Increased flow velocity and local eddies 

expected at point of discharge during 

7,000 cfs discharge. Flow velocity 

rapidly decreases when discharged into 

the MRGO. 

No change in diversion flow 

regime so impacts would be 

similar to alternative B.

No change in diversion flow 

regime so impacts would be similar 

to alternative B.

WATER QUALITY

Current water quality conditions would 

persist; dissolved oxygen (DO) levels and 

bacterial concentration would persist; 

continued loss of wetlands reduces ability to 

filter and absorb pollutants. 

Create 7,444 acres and nourish 12,186

acres marsh; create 4,225 acres and 

nourish 6,093 acres swamp; benefit 

water quality in terms of increased DO, 

reduced turbidity, and filtration and 

trapping of pollutants once construction 

completed.

Create 17,352 acres and nourish 

26,836 acres marsh; create 4,225

acres and nourish 6,093 acres 

swamp; benefit water quality in 

terms of increased DO, reduced 

turbidity, and filtration and 

trapping of pollutants once 

construction completed.

Create 18,056 acres and nourish 

26,836 acres marsh; create 4,225

acres and nourish 6,093 acres 

swamp; benefit water quality in 

terms of increased DO, reduced 

turbidity, and filtration and 

trapping of pollutants once 

construction completed.

WATER QUALITY

(salinity)

Potential reduction of 2-3 parts per thousand 

(ppt) in salinity based on the proposed 

construction of several diversion projects in 

the study area.

A maximum salinity change of -1.0 to -

1.4 ppt in Lake Borgne from May to 

December based on proposed diversion 

of 1,000 cfs and peak diversion flow of 

7,000 cfs. Salinity in the Mississippi 

Territorial Waters are predicted to be 

reduced by -0.6 to -0.9 ppt under 

combined influence of Violet, Louisiana

Freshwater Diversion and the 4,500 cfs 

of the combined Maurepas Swamp area 

diversions.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

NAVIGABLE 

WATERWAYS

Current conditions would persist. Other 

projects such as other freshwater 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 

may be affected by current from 

diversion flow. Velocities at Bayou 

Bienvenue and Bayou Dupre control 

structures would not affect navigation. 

Impact to navigation in Central 

Wetlands area from increased velocities 

or gate closures.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B. 
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-13 June 2012

Table S-1: Evaluation of Potential Impacts to Significant Resources by Alternative

Environmental 

Resources

Alternatives

Alternative A

No Action Alternative B Alternative C Alternative D

SOILS Continued loss of sediments due to shoreline 

erosion and wetland loss.

Diversion channel (Alternative 1 

location) would impact approx. 442 

acres of soils designated as prime 

farmland. 

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

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 

alternative B.

Impacts would be similar to 

alternative B.

NOISE No impacts anticipated from FWOP 

condition

No significant impacts anticipated; 

potential temporary impacts to 

communities near the diversion; may be 

temporary and local disturbance of 

some wildlife. 

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

HAZARDOUS, TOXIC, 

AND RADIOACTIVE 

WASTE (HTRW) 

No potential impacts due to any associated 

construction activities. 

An HTRW Phase I was performed for 

the study area, and identified a low 

probability of encountering 

contaminants of concern.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

BARRIER ISLAND 

RESOURCES 

The Chandeleur Islands would continue to 

erode: it is estimated that by 2014, Breton 

Island would be subaerial and the entire 

island chain completely eroded. 

No impacts from this alternative. 

Preliminary modeling efforts for the 

barrier islands indicate additional study 

is warranted. Additionally, modeling 

parameters that involve the impacts of 

the oil spill have to be considered and 

the future is uncertain based on the 

magnitude of the spill and the constantly 

changing efforts to alleviate the 

immediate environmental impacts.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-14 June 2012

Table S-1: Evaluation of Potential Impacts to Significant Resources by Alternative

Environmental 

Resources

Alternatives

Alternative A

No Action Alternative B Alternative C Alternative D

COASTAL 

VEGETATION

RESOURCES 

Loss of 131,091 acres by 2065. 

Restoration plan includes 54 acres 

ridge; create 4,225 acres, nourish 6,093

acres swamp; create 7,444 acres, 

nourish 12,186 acres marsh; Diversion 

channel (Alternative 1 location) would 

adversely impact 227 acres of existing 

wetlands. While the project area will 

see an increase in wetland acreage, the 

system as a whole could continue to 

encounter some vegetative losses.

Restoration plan includes 54 acres 

ridge; create 4,225 acres, nourish 

6,093 acres swamp; create 17,352

acres, nourish 26,836 acres marsh; 

Diversion channel would 

adversely impact 227 acres of 

existing wetlands. While the 

project area will see an increase in 

wetland acreage, the system as a 

whole could continue to encounter 

some vegetative losses.

Restoration plan includes 54 acres 

ridge; create 4,225 acres, nourish 

6,093 acres swamp; create 18,056 

acres, nourish 26,836 acres marsh; 

Diversion would adversely impact 

227 acres of existing wetlands. 

While the project area will see an 

increase in wetland acreage, the 

system as a whole could continue 

to encounter some vegetative 

losses.

WILDLIFE 

RESOURCES 

Continued decline in quality of wildlife 

habitat adversely impacts wetland dependent 

wildlife populations.

Restoration plan would provide 54 acres 

ridge; 19,630 acres of new marsh; 

10,318 acres swamp habitat and protect 

35,367 linear feet of shoreline vital to 

neotropical migratory birds; colonial 

nesting birds, waterfowl and mammals. 

Restoration plan would provide 54

acres ridge; 44,188 acres of new 

marsh; 10,318 acres swamp 

habitat and protect 314,944 linear 

feet of shoreline vital to 

neotropical migratory birds; 

colonial nesting birds, waterfowl 

and mammals. 

Restoration plan would provide 54

acres ridge; 44,892 acres of new 

marsh; 10,318 acres swamp habitat 

and protect 410,567 linear feet of 

shoreline vital to neotropical 

migratory birds; colonial nesting 

birds, waterfowl and mammals. 

AQUATIC AND 

FISHERY RESOURCES

Wetland fragmentation, emergent wetland 

loss, shoreline and bank line erosion result 

in substantial decrease of critical essential 

fish habitat (EFH) needed for important fish 

life cycles, reducing the area’s ability to 

adequately support Federally managed 

species.

Convert 7,444 acres of shallow open 

water and nourish 12,186 acres of marsh 

to create a more continuous emergent 

transitional wetland and 35,367 linear 

feet of shoreline protection. Based on 

preliminary aquatic impact analysis,

results show no significant impacts to 

fishery species including Atlantic 

croaker, red drum (juveniles and adults), 

spotted sea trout (juveniles and adults), 

stripped mullet, sheepshead, Gulf 

menhaden, and bay anchovy. However, 

the potential for localized impacts to 

some species in areas closest to the 

Violet, Louisiana Freshwater Diversion 

could occur, as well as potential 

increases further away.

Creation of approximately 17,356

acres of marsh, 314,944 linear feet 

of shoreline protection, nourish 

26,836 acres of existing marsh 

habitat. Based on preliminary 

aquatic impact analysis, results 

show no significant impacts to 

fishery species including Atlantic 

croaker, red drum (juveniles and 

adults), spotted sea trout 

(juveniles and adults), stripped 

mullet, sheepshead, Gulf 

menhaden, and bay anchovy. 

However, the potential for 

localized impacts to some species 

in areas closest to the Violet, 

LouisianaFreshwater Diversion 

could occur, as well as potential 

increases further away.

Similar to that of alternative C, 

with the following exceptions, 

additional 95,623 linear feet of 

shoreline protection, 704 acres of 

additional marsh created. Based on 

preliminary aquatic impact 

analysis, results show no 

significant impacts to fishery 

species including Atlantic croaker, 

red drum (juveniles and adults), 

spotted sea trout (juveniles and 

adults), stripped mullet, 

sheepshead, Gulf menhaden, and 

bay anchovy. However, the 

potential for localized impacts to 

some species in areas closest to the 

Violet, Louisiana Freshwater 

Diversion could occur, as well as 

potential increases further away.
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-15 June 2012

Table S-1: Evaluation of Potential Impacts to Significant Resources by Alternative

Environmental 

Resources

Alternatives

Alternative A

No Action Alternative B Alternative C Alternative D

COMMERCIAL 

FISHERIES 

Decline expected as habitat loss and 

degradation from erosion due to salinity 

changes lead to overfishing of the resource.

Convert 7,444 acres of shallow open 

water and nourish 12,186 acres of marsh 

to create a more continuous emergent 

transitional wetland and 35,367 linear 

feet of shoreline protection. Based on 

preliminary aquatic impact analysis,

results show slight increase in net 

productivity for juvenile white shrimp 

and brown shrimp within Lake Borgne. 

Restoration of approximately 

17,356 acres of marsh, 314,944

linear feet of shoreline protection, 

nourish 26,836 acres of existing 

marsh habitat. Based on 

preliminary aquatic impact 

analysis, results show slight 

increase in net productivity for 

juvenile white shrimp and brown 

shrimp within Lake Borgne. 

Similar to alternative C, additional 

95,623 linear feet of shoreline

protection, 704 acres of additional

marsh created. Based on 

preliminary aquatic impact 

analysis, results show slight 

increase in net productivity for 

juvenile white shrimp and brown 

shrimp within Lake Borgne. 

OYSTER RESOURCES 

Loss of wetlands in the project area would 

likely alter the detritus-based food web of 

the oyster, thereby reducing the localized 

carrying capacity for oyster leases in the 

area.

Would borrow 87 million cubic yards

(mcy) of borrow in Lake Borgne. 

Convert 7,444 acres of shallow open 

water and nourish 12,186 acres of marsh 

to create a more continuous emergent 

transitional wetland and 35,367 linear 

feet of shoreline protection. Based on 

preliminary aquatic impact analysis,

results show slight decreases to oysters 

and spat through Lake Borgne and the 

Inner Biloxi Marsh. 

Restoration of approximately 

17,352 acres of marsh, 314,944

linear feet of shoreline protection, 

nourish 26,836 acres of existing 

marsh habitat using 152 mcy of 

borrow. Based on preliminary 

aquatic impact analysis, results 

show slight decreases to oysters 

and spat through Lake Borgne and 

the Inner Biloxi Marsh.

Similar to that of alternative C, 

additional 95,623 linear feet of 

shoreline and 704 acres or marsh 

created using an additional 2.3 mcy

of borrow. Based on preliminary 

aquatic impact analysis, results 

show slight decreases to oysters 

and spat through Lake Borgne and 

the Inner Biloxi Marsh.

PLANKTON 

RESOURCES 

No Action would have an additive impact 

due to increasing salinity and a transition to 

more marine-dominated community.

Minor changes in salinity (-0.6 to -1.4 

ppt) in Lake Borgne and the Biloxi 

Marsh would not have a substantial 

effect on plankton abundance or 

distribution.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative 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 mcy of material, to 

depths of ten feet with a maximum 

depth of twelve feet, from a total of 

9,036 acres of water bottom. Based on 

preliminary aquatic impact analysis,

results show slight increase in annual 

net productivity for benthic species in 

East Lake Pontchartrain and Lake 

Borgne. 

Excavation of 152 mcy of 

material, to depths of ten feet with 

a maximum depth of twelve feet, 

from a total of 15,724 acres of 

water bottom. Based on 

preliminary aquatic impact 

analysis, results show slight 

increase in annual net productivity 

for benthic species in East Lake 

Pontchartrain and Lake Borgne. 

Excavation of 154.3 mcy of 

material, to depths of ten feet with 

a maximum depth of twelve feet, 

from a total of 15,724 acres of 

water bottom. Based on 

preliminary aquatic impact 

analysis, results show slight 

increase in annual net productivity 

for benthic species in East Lake 

Pontchartrain and Lake Borgne. 
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-16 June 2012

Table S-1: Evaluation of Potential Impacts to Significant Resources by Alternative

Environmental 

Resources

Alternatives

Alternative A

No Action Alternative B Alternative C Alternative 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. 

Convert 7,444 acres of shallow open 

water and nourish 12,186 acres of marsh 

to create a more contiguous emergent 

transitional wetland. Based on 

preliminary aquatic impact analysis,

results show slight decrease in net 

productivity for juvenile red drum, 

white shrimp, and brown shrimp within 

Lake Borgne. Construction of retention 

dikes and reverse tidal flows could 

reduce utilization of Central Wetlands 

by certain species.

Restoration of approximately 

17,352 acres of marsh, 314,944 

linear feet of shoreline protection, 

nourish 26,836 acres of existing 

marsh habitat. Based on 

preliminary aquatic impact 

analysis, results same as 

alternative B. Construction of 

retention dikes and reverse tidal 

flows could reduce utilization of 

Central Wetlands by certain 

species.

Similar to that of alternative C, 

with the following exceptions, 

additional 95,623 linear feet of 

shoreline protection, and 704 acres 

of additional marsh created. Based 

on preliminary aquatic impact 

analysis, results same as alternative 

B. Construction of retention dikes 

and reverse tidal flows could 

reduce utilization of Central 

Wetlands by certain species.

THREATENED AND 

ENDANGERED (T&E) 

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 mcy borrow 

materials, 122 acres impacts from 

shoreline protection from Gulf sturgeon 

critical habitat. 

Approximately 152 mcy borrow 

material, 1,937acre impacts from 

shoreline protection from Gulf 

sturgeon critical habitat.

Approximately 154.3 mcy borrow 

material 2,494 acre impacts from 

shoreline protection from Gulf 

sturgeon critical habitat. 

SOCIO-ECONOMIC 

RESOURCES - 

Population

The no action alternative, would have no 

direct, indirect, or cumulative impacts on 

human populations. 

There are no direct impacts to human 

populations within the project area. 

Hence, this alternative would not be 

expected to have any cumulative effects

on nearby populations.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

SOCIO-ECONOMIC 

RESOURCES – 

Community Cohesion

The no action alternative would have no 

impact on community cohesion

The construction of the diversion would 

create a new canal temporarily 

impacting traffic and thus affecting flow 

linkage between the two subdivisions 

and connected community residents.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

SOCIO-ECONOMIC 

RESOURCES – 

Employment and Income

The no action alternative would result in 

continued wetland loss and localized 

impacts on employment and income. 

Alternative B would work 

synergistically with other projects and 

programs to support coast wide 

wetland-dependent employment.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

SOCIO-ECONOMIC 

RESOURCES - 

Infrastructure 

The decline wetlands would contribute to 

the deterioration of substrate upon which 

infrastructure features are constructed.

Alternative B would restore or protect 

30,002 acres in the project area, which 

would assist with protection of existing 

infrastructure.

Alternative C would provide 

greater beneficial impacts through 

the restoration of 24,558 acres 

more than alternative B.

Impacts would be slightly greater 

than alternative C, because 704 

additional acres would be restored.
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-17 June 2012

Table S-1: Evaluation of Potential Impacts to Significant Resources by Alternative

Environmental 

Resources

Alternatives

Alternative A

No Action Alternative B Alternative C Alternative D

SOCIO-ECONOMIC 

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 alternative 

B would prevent the increase in 

maintenance and relocation costs for 

pipelines in and around the project area.

Alternative C would provide more 

complete protection for oil and 

gas infrastructure than alternative 

B, and would produce more 

beneficial impacts through the 

restoration of 24,558 additional 

acres.

Impacts would be slightly greater 

than alternative C, because 704 

additional acres would be restored.

SOCIO-ECONOMIC 

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.

Alternative B would provide important 

fisheries habitat. Overall, the industry 

would be more stable near the project 

area due to a long-term increase in the 

quality of fisheries habitat.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

SOCIO-ECONOMIC 

RESOURCES – Oyster 

Leases

The loss of wetlands in the project area 

would likely alter the detritus-based food 

web of the oyster thereby reducing the 

localized carrying capacity for oyster leases 

in the area. 

Creation, protection and nourishment of 

emergent wetlands in the project area in 

conjunction with other actions proposed 

and implemented in the vicinity would 

not affect the productivity of planktonic 

resources upon which oysters feed.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

SOCIO-ECONOMIC 

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. 

Alternative 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 area to be maintained.

Benefits would be greater than 

alternative B, by providing an 

additional 24,558 acres of marsh 

benefits.

Impacts slightly greater than 

alternative C, by providing 704 

acres of additional marsh benefits.

SOCIO-ECONOMIC 

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.

Alternative 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 

alternative B.

Impacts would be similar to 

alternative B.
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-18 June 2012

Table S-1: Evaluation of Potential Impacts to Significant Resources by Alternative

Environmental 

Resources

Alternatives

Alternative A

No Action Alternative B Alternative C Alternative D

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 areas where the proposed 

diversion would be located (Alternative 

1 location). Concerns raised at public

meetings include: a perceived potential 

for induced flooding, disapproval of the 

location, a perceived lack of benefits to 

St. Bernard Parish, and community 

cohesion.

Potential impacts would be the 

same as alternative B.

Potential impacts would be the 

same as alternative B.

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 either have 

to be avoided or adverse effects would 

have to be mitigated. 

Alternative C includes 24,558 

additional acres of restoration 

activities, and therefore greater 

potential impacts.

Alternative D includes 704

additional acres of restoration 

activities, 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 should improve recreational 

fishing and wildlife hunting 

opportunities. Freshwater diversion 

could improve duck hunting. 

Freshening from diversion may push 

some recreational fishing further into 

more saline waters within the project 

area. Based on preliminary aquatic 

impact analysis, results show decrease 

in net productivity for spotted sea trout 

in the Inner Biloxi Marsh but a slight 

increase in net productivity for juvenile 

white shrimp and brown shrimp within 

Lake Borgne

Similar effect as alternative B for 

diversion feature, for wetland 

measures, impacts are to a greater 

extent. 

Effects to resource similar to 

alternative C. 
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-19 June 2012

Table S-1: Evaluation of Potential Impacts to Significant Resources by Alternative

Environmental 

Resources

Alternatives

Alternative A

No Action Alternative B Alternative C Alternative D

AESTHETICS

(Scenic Rivers)

Continued habitat deterioration, land loss, 

and conversion to open water reducing 

scenic qualities of area.

Temporary impacts from the 

Restoration Plan could include a 

reduction in access, reduced water 

quality, and possible sedimentation. 

However, the overall project would 

create and nourish 4,317 acres of marsh 

and 7,693 acres of swamp in the vicinity 

of the scenic streams restoring their 

viewscape to its original habitat types. 

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

FLOODPLAINS

A large portion of the project area is coastal 

marsh habitat, which would continue to 

degrade and increase the flood risk to 

developed portions of the floodplain.

Approximately 529 acres within the 500 

and/or 100-year floodplain would be 

converted to floodway as part of the 

construction of the diversion channel

(Alternative 1 location). Guide levees 

and control structures would eliminate 

the flood risk to communities or 

development in the adjacent floodplain.

Impacts would be similar to 

alternative B. 

Impacts would be similar to 

alternative B.
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-20 June 2012

S.11 CONCLUSIONS

The tentatively selected plan (alternative C) would restore 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 in the Central Wetlands; 466 

acres of saline marsh; and 54 acres of ridge habitat along Bayou La Loutre. Alternative 

C includes approximately 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. Alternative C also includes two recreation features and an adaptively 

managed freshwater diversion near Violet, Louisiana. These acreage values are based on 

WVA results, which take into account marsh creation behind the shoreline protection 

features.

Approximately 10,221 acres of the restoration and protection features would be located in 

the East Orleans Landbridge/Pearl River area and approximately 9,861 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 features include forested habitats, having some 

storm surge damage risk reduction benefits. 

The Violet, Louisiana Freshwater Diversion is an important component of the plan to 

restore historic salinity conditions and provide freshwater and nutrients to nourish 

existing and restored wetlands in the study area. 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, design and implementation of the Violet, Louisiana Freshwater 

Diversion as authorized by WRDA 2007 Section 3083. 

The anticipated outputs of the tentatively selected plan would help address the current 

trend of degradation of the Lake Borgne ecosystem, support Nationally significant 

resources, provide a sustainable and diverse array of fish and wildlife habitats, provide 

infrastructure protection, and make progress towards a more sustainable ecosystem. 

S.12 RECOMMENDATIONS

The District Commander has considered all the significant aspects of this study including 

the environmental, social, and economic effects, the engineering feasibility, and comments 

received from resource agencies, the non-Federal sponsors, and the public and has 

determined that the tentatively selected plan is in the overall public interest and a justified 

expenditure of Federal funds. As a comprehensive approach to protect, stabilize, and 
Executive Summary 

FEIS MRGO Ecosystem

Restoration Plan ES-21 June 2012

augment the landbridge between Lake Borgne and the MRGO, the District Commander 

recommends the construction of rock dikes for shoreline protection along the south bank 

of Lake Borgne in the reaches referenced as Bayou Bienvenue, Bayou Dupre, and West of 

Shell Beach. The District Commander also recommends the construction of marsh 

creation projects in the Golden Triangle and Shell Beach area.

The total cost for the project is $2.9 billion inclusive of associated investigation, 

environmental, engineering and design, construction, supervision and administration, and 

contingency costs. The operations, maintenance, repair, replacement and rehabilitation 

(OMRR&R) of this project shall be the responsibility of the a non-Federal sponsor. 
Chapter 1 Introduction 

FEIS MRGO Ecosystem

Restoration Plan 1-1 June 2012

CHAPTER 1: INTRODUCTION 

1.1 INTRODUCTION

This Final Environmental Impact Statement (FEIS) for the Mississippi River Gulf Outlet 

(hereafter MRGO) Ecosystem Restoration Plan Feasibility Report was prepared by the 

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

District (CEMVN). It includes input from Federal, as well as Louisiana and Mississippi

state agencies. This National Environmental Policy Act (NEPA) of 1969 document tiers 

off the Louisiana Coastal Area (LCA), Final Programmatic Environmental Impact 

Statement (FPEIS), Record of Decision (ROD), signed January 31, 2005. 

This FEIS was prepared to assess of the viable alternatives identified as part of the 

MRGO Ecosystem Restoration Plan Feasibility Report. The feasibility report will 

accompany this FEIS, the reports are companion documents. Plans are evaluated based 

on the ability to meet the study goals and objectives, compliance with environmental laws 

and regulations, contributions to the Federal objective of National Ecosystem Restoration 

(NER), and meeting the four evaluation criteria of completeness, effectiveness, 

efficiency, and acceptability. 

Through evaluation and impact assessment, the feasibility report and FEIS identify the 

tentatively selected plan that is the NER plan as determined by the four evaluation criteria

noted above. Selecting the NER plan requires careful consideration of planning goals, 

objectives, and constraints. The NER plan reasonably maximizes environmental benefits 

while passing tests of cost effectiveness and incremental cost analyses, significance of 

outputs and ability to meet the evaluation criteria. The Water Resources Development 

Act of 2007 (WRDA 2007) requires the plan to be cost effective, environmentally 

acceptable, and technically feasible in order to be carried out by the Secretary of the 

Army. 

Louisiana’s coastal plain contains the largest expanse of coastal wetlands in the 

contiguous United States and accounts for 90 percent of the total coastal marsh loss as 

occurring in the Nation (USACE, 2004). Louisiana coastal land loss has been ongoing 

since the early 1900s with commensurate harmful effects on the ecosystem and future 

adverse impacts to the regional economy and the Nation. The USACE, the State of 

Louisiana, and others, under the laws passed by Congress and as administered by the 

President of the United States, have been working to combat coastal land loss, not only 

because of the role coastal environment plays in storm protection, but also because of its

contribution to the health of the natural environment, the regional and national economy, 

and the culture of South Louisiana. 

The coastal wetlands, built by Mississippi River deltaic processes, contain diverse 

habitats that range from narrow natural levee and beach ridges to expanses of forested 

swamps and freshwater, intermediate, brackish, and saline marshes. Taken as a whole, 
Chapter 1 Introduction 

FEIS MRGO Ecosystem

Restoration Plan 1-2 June 2012

the unique habitats, with their hydrological connections to each other, upland areas, the 

Gulf of Mexico, and migratory routes of birds, fish, and other species, combine to place 

the coastal wetlands of Louisiana among the Nation’s most productive and important 

natural assets. 

Coastal wetlands are unsurpassed in their contribution and importance to the ecosystem 

of the Louisiana and Mississippi gulf coast region. The wetlands are an irreplaceable 

natural resource that provides many benefits to local communities as well as the Nation. 

From a biological perspective, the wetlands provide habitat and food that sustains the 

biodiversity in the region from the smallest to largest scales. Beginning with a single 

blade of Spartina that provides habitat and food for microbes and snails to complex 

wetland landscapes that are home to crabs, shrimp, and fish and the birds and mammals 

that feed on them, Louisiana’s wetlands are a vital National resource. From a 

socioeconomic perspective, the wetlands define a way of life for the commercial and 

recreational fishermen in the region. Additionally, the wetlands stabilize shorelines and 

provide a buffer for the coastal communities from storm waves and surge. 

1.2 STUDY AUTHORITY AND STUDY SPONSOR

The study is authorized by Section 7013 of the WRDA 2007 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 storm surge 

damage;

• prevent saltwater intrusion into the waterway; 

• integrate the recommendations of the LCA Report and the Louisiana Coastal 

Protection and Restoration (LACPR) Technical Report; and

• consider the use of native vegetation and diversions of freshwater to restore the 

Lake Borgne ecosystem.

The WRDA 2007 Section 7013 features of the MRGO plan in Tiers 1 and 2, as described 

in the Mississippi River-Gulf Outlent (MRGO) Ecosystem Restoration Plan Final 

Feasibility Report, Supplemental Report of the Chief of Engineers In Response To The 

Water Resources Development Act Of 2007, are 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 cost 

sharing sponsor(s) will be identified as required by 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), The Tier 3 feature, consisting of the Violet, Louisiana Freshwater Diversion 

project, as authorized by Section 3083 of WRDA 2007 (Tier 3A), as well as certain 
Chapter 1 Introduction 

FEIS MRGO Ecosystem

Restoration Plan 1-3 June 2012

MRGO Ecosystem Restoration features authorized by Section 7013 of WRDA 2007 (but 

which are dependent upon the implementation of a freshwater diversion at or in the 

vicinity of Violet (Tier3B)), are recommended in the report for additional feasibility 

study and analysis. 

The Section 7013 MRGO ecosystem restoration study is 100% Federally funded. Despite 

lengthy discussions with the State of Louisiana, the Government has been unable to 

identify a non-Federal sonsor for design and implementation of the Section 7013 Section 

3083 of WRDA 2007 conditionally authorizes the the Violet, Louisiana Freshwater 

Diversion project and identifies the State of Mississippi and the State of Louisiana as the 

non-Federal sponsors for that project. Both states have been actively participating on the 

planning team. . USACE will continue, pursuant to Section 3083 of WRDA 2007, to 

coordinate with the State of Louisiana and the State of Mississippi during the further 

feasibility study for the Violet, Louisiana Freshwater Diversion project and with the State 

of Louisiana regarding those Section 7013 elements of the MRGO Ecosystem 

Restoration project that are determined by USACE to be dependent upon the design and 

implementation of the Violet diversion. 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) requires the 

execution of a binding written agreement by the State of Louisiana and the State of 

Mississippi in order for the United States to commence construction. 

1.3 STUDY AREA

The study area includes portions of the Mississippi River deltaic plain in southeast 

Louisiana and parts of the southwest Mississippi coast (figure 1-1). It encompasses

approximately 3.84 million acres (over 6,000 square miles). 

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 Gosier 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 include portions of Hancock and Harrison. 
Chapter 1 Introduction 

 

FEIS MRGO Ecosystem

Restoration Plan 1-4 June 2012

Figure 1-1: Study Area - Ponchartrain Basin and Western Mississippi Sound
Chapter 1 Introduction 

FEIS MRGO Ecosystem

Restoration Plan 1-5 June 2012

In Louisiana, the study area includes the Pontchartrain Basin. The Upper Pontchartrain 

sub-basin includes Lake Maurepas and its adjacent wetlands and swamps. Lake 

Maurepas receives its freshwater influences from the Amite and Tickfaw Rivers, Bayou 

Manchac, and other smaller rivers. 

The Middle Pontchartrain sub-basin is comprised of Lake Pontchartrain, its adjacent 

cities and towns, and surrounding wetlands. Lake Pontchartrain is affected by freshwater 

inflows from Pass Manchac, North Pass, and the Tangipahoa, Tchefuncte, and Bogue 

Falaya Rivers, some bayous, and the Bonnet Carré Spillway. 

The Lower Pontchartrain sub-basin includes Lake Borgne, the MRGO, the Mississippi 

River, Chandeleur and Breton Sounds, portions of the Gulf of Mexico, and the 

surrounding wetlands, barrier islands, and communities. Lake Borgne is hydrologically 

linked to Lake Pontchartrain through tidal passes at the Rigolets, Chef Menteur Pass, and 

the manmade 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. 

Major navigation channels include the Mississippi River, IHNC, the Gulf Intracoastal 

Waterway (GIWW), and a portion of the MRGO that remains authorized. 

For planning and evaluation purposes, the study area, which encompasses the 

Pontchartrain Basin and Western Mississippi Sound, was divided into 52 planning 

subunits, as illustrated in figure 1-2. 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 (LOSR, 2002). 

These fastland areas are not targeted for ecosystem restoration in this study and were not 

included in table 1-1. 

The restoration measures considered in this study are located in the eastern portion, or 

Lower Pontchartrain sub-basin, of the overall study area. Due to the absence of project 

related construction features in large portions of the study area, the study area was 

reduced in order to facilitate ease of discussion of existing conditions and potential 

impacts within chapter 3 and chapter 4, respectively. The “smaller” study area that was 

focused on for discussion in this EIS includes the East Orleans Landbridge, Lake Borgne 

and associated marsh, the Biloxi Marsh, and Bayou Terre aux Boeufs Marsh and is herein 

referenced as the project area. This area includes subunits 5 through 7, 10 through 15, 17 

through 19, 21 through 23, 26, 27, 32, 36a, 38, and 40 as shown on figure 1-2. These 39 

subunits were focused on since each has at least one restoration feature located within it. 
Chapter 1 Introduction 

 

FEIS MRGO Ecosystem

Restoration Plan 1-6 June 2012

Figure 1-2: MRGO Planning Subunits
Chapter 1 Introduction

FEIS MRGO Ecosystem

Restoration Plan 1-7 June 2012

1.4 PURPOSE AND NEED FOR ACTION

The MRGO Ecosystem Restoration Plan Feasibility Report and Final Environmental 

Impact Statement (FEIS) were developed as a supplement to the June 2008 MRGO DeepDraft De-Authorization Report and is intended to fully meet the requirements of Section 

7013 of the WRDA 2007. The feasibility report will result in a Report of the Chief of 

Engineers, describing the tentatively selected plan for MRGO Ecosystem Restoration and 

recommending construction of features for early implementation contingent upon the 

identification of a non-Federal sponsor, which has been conditionally authorized for 

construction by Section 7013 of the WRDA 2007. The plan addresses systematic 

ecosystem restoration and protection of the Lake Borgne ecosystem and areas affected by 

the MRGO navigation channel, and includes considerations of measures to reduce or 

prevent damage from storm surge. The study integrates the findings of ongoing 

comprehensive restoration planning efforts for the study area, including the LACPR Final 

Technical Report, the LCA Program, and Louisiana’s 2007 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., 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 humaninduced 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. The period of analysis covers implementation and extends 50 years 

into the future. It begins in the first year of construction in 2015 and extends to 2065. 

The main water resource problems identified in the study area and the impacts associated 

with the construction and maintenance of the MRGO navigation channel include: 

• Wetlands 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 to storm 

surge. 
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Table 1-1 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 1-2 for subunits where initial plan features were developed.

The initial determination whether restoration features should be developed in a subunit 

were based on the study authority. The authority indicates that the plan would 

“physically modify the MRGO and restore the areas affected by the navigation channel”. 

Problems and opportunities were identified in subunits adjacent to the MRGO and in 

subunits potentially affected by MRGO construction, operation, or maintenance. 

The study authority 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 1-1: 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 Manchac Landbridge 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 East Manchac Landbridge can be 

attributed to increased salinity caused by the MRGO. However, 

because these areas have relatively low land loss rates, the

benefits of wetland creation and nourishment in this area are 

comparatively low.

(50) West Manchac 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
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Restoration Plan 1-9 June 2012

Table 1-1: Subunits by Geographic Area and Their Relevance to the MRGO 

Ecosystem Restoration Plan 

(ID) Subunit Name Relevance of Subunit to MRGO Plan

(29) Lake Pontchartrain

Lake Pontchartrain was affected by saltwater intrusion caused 

by the MRGO. Salinity affects 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 (SAV) 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. 

Measures were developed to address subunit problems and 

opportunities. 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

(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 affects addressed by de-authorization of channel and 

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 de-authorization 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.
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Table 1-1: Subunits by Geographic Area and Their Relevance to the MRGO 

Ecosystem Restoration Plan 

(ID) Subunit Name Relevance of Subunit to MRGO Plan

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 Mississippi Coastal Improvements Program 

(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

Table 1-2: Problems in Initial Feature Subunits

Problems

Decreased Freshwater, 

Sediment and Nutrient 

Inputs

Hydrologic 

Modification

Saltwater Intrusion

Wetland Loss

Ridge Habitat 

Degradation and 

Destruction

Bank and Shoreline 

Erosion

Habitat Change and 

Land Loss

Invasive Species and 

Herbivory

Retreating and Eroding 

Barrier Islands

Lake Maurepas and North Lake Pontchartrain

(16) East and (50) West Manchac 

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
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Table 1-2: Problems in Initial Feature Subunits

Problems

Decreased Freshwater, 

Sediment and Nutrient 

Inputs

Hydrologic 

Modification

Saltwater Intrusion

Wetland Loss

Ridge Habitat 

Degradation and 

Destruction

Bank and Shoreline 

Erosion

Habitat Change and 

Land Loss

Invasive Species and 

Herbivory

Retreating and Eroding 

Barrier Islands

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

1.4.1 MRGO Navigation Channel

Congress authorized the MRGO in 1956 as a Federal navigation channel to provide a 

shorter route between the Port of New Orleans and the Gulf of Mexico (figure 1-3). It 

was authorized as a 36-foot deep, 500-foot bottom width waterway (38-foot deep, 600-

foot wide at the Gulf of Mexico entrance) extending from the IHNC Lock to the 38-foot 

depth contour in the Gulf of Mexico. Construction began in 1958 and was completed in 

1968. 

Figure 1-3: MRGO Navigation Channel
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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, Congress requested a 

plan for de-authorization of the MRGO (Public Law 109-234). 

In 2006, Congress directed the Secretary of the Army, acting through the Chief of 

Engineers, to develop a plan for de-authorization of deep-draft navigation on the MRGO 

in the Emergency Supplemental Appropriations Act for Defense, the Global War on 

Terror, and Hurricane Recovery, 2006 (Public Law 109-234). Public Law 109-234 also 

modified Public Law 109-148, to clarify that the $75,000,000 provided in Public Law 

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.” 

In January 2008, the Chief of Engineers signed a report recommending de-authorization 

of a portion 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 MRGO was 

officially de-authorized from the confluence with the GIWW to the Gulf of Mexico as a 

Federal navigation channel. A rock closure structure was constructed across the MRGO 

near the Bayou La Loutre Ridge in St. Bernard Parish, Louisiana (figure 1-4) in 2009. 

Figure 1-4: MRGO Closure Structure at Bayou La Loutre 
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1.4.1.1 MRGO Impacts

The cumulative effects of human and natural coastal activities have severely degraded the 

Mississippi River’s deltaic processes and shifted the coastal area from a dynamic balance 

between land gain and land loss to one of net land loss. 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 (figure 

1-5). 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. 

Figure 1-5: Construction of MRGO Channel (1959) 

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) (appendix V). MRGO channel construction, the dredging of the 

channel and placement of dredged material, resulted in the conversion of 19,400 acres of 
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Restoration Plan 1-14 June 2012

wetlands and 4,750 acres of shallow open water to deep open water or dredge material 

banks. 

Other contributing factors of land loss, such as subsidence, sea level rise, and human 

alterations complicate the calculation of indirect impacts from the MRGO. 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 Department of the Interior – 

United States Geological Survey (USGS) 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 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. A summary of the direct and indirect impacts by habitat type resulting 

from the construction of the MRGO is presented in table 1-3. 

Table 1-3: Direct and Indirect Habitat Impacts of the MRGO

Habitat Type

Impacts from 1956 to 1990a

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 impacts between 1990 to 2008

Additional marsh lost adjacent to the channel 460 b 3,400

Total Impacts 24,610 33,920 

NOTES: a Direct impacts are due to construction and erosion. Indirect impacts are due to salinity or hydrological changes from the MRGO (Habitat 

Impacts of the Construction of the MRGO, USACE, 1999). Habitat shifts were estimated using 1956 – 1990 habitat composition data from 

LDNR. b

Does not include deeper water aquatic habitat effects due to salinity increases or Lake Maurepas area to be restored by LCA 

projects.

Direct impacts due to additional erosion between 1990 and 2008. Indirect impacts due to increased tides and salinity.
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Restoration Plan 1-15 June 2012

It is important to note that 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). The PDT recognizes that the MRGO, as well as other contributing 

factors affected the salinity levels in Lake Pontchartrain and Lake Borgne; however, the 

team considered these concerns and determined they are being addressed by the LCA 

feasibility studies, MRGO closure structure, and the Lake Borgne storm surge barrier. 

This includes 488,400 acres of Lakes Pontchartrain and Borgne affected by salinity shifts 

and 64,000 acres of Lake Pontchartrain that exhibited seasonal hypoxic/anoxic conditions 

(low oxygen/no oxygen) due to its hydrologic connection with the MRGO channel. 

Initial monitoring data indicate that the channel closure at Bayou La Loutre has decreased 

salinity upstream of the closure (USGS, 2009). The closure at Bayou La Loutre and 

authorized LCA projects are anticipated to continue to address the hypoxia and salinity 

impacts of the MRGO in Lakes Pontchartrain and Borgne. 

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 

major tidal channels at the Chandeleur Islands are located north of Hewes Point and south 

of Breton Island. Measurements and modeling conducted in the 1970s demonstrate that 

these two tidal channels were responsible for the majority of tidal flow into and out of 

Chandeleur and Breton Sounds (Hart and Murray, 1978). The MRGO was dredged 

through the Bayou La Loutre Ridge cutting a basin boundary that limited the flow of 

saline water from the Breton Sound area into Lake Borgne (Rounsefell, 1964). 

Following construction of the MRGO, strong tidal current flow occurred through the 

MRGO, creating a major conduit for tidal exchange for portions of the Lake 

Pontchartrain Basin. In a study analyzing the typical tidal flow following construction of 

the MRGO, it was determined that circulation patterns were altered along the lower 

southeastern length of the channel and across areas between Breton Sound and Lake 

Borgne (Wicker et al., 1982). 

The habitat changes in the study area are primarily related to saltwater intrusion, although 

other factors such as 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). The data indicated that the salinity is lowest in the late 

spring and highest in the summer and fall. This is reflective of the seasonal variations in 

the freshwater inflows from the rivers and streams into the basin. The salinity in Lake 

Borgne generally ranged from 2 to 15 parts per thousand (ppt) and is influenced greatly 

by the Pearl River and inflows from the Rigolets and Chef Pass. Higher salinity water 

from the MRGO entered Lake Borgne through breaks in the marshes between the two 

water bodies (Tate, 2002). 

A comparison of data collected pre- and post-construction of the MRGO indicate that the 

most notable increase in monthly average salinity occurred after 1963 (Tate, 2002). 

Mean monthly salinity increased for all months for the period after 1963. This increase 
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Restoration Plan 1-16 June 2012

coincides with the partial completion of the MRGO in 1963, which provided a major 

access for saltwater to enter Lakes Pontchartrain and Borgne. Table 1-4 lists mean 

monthly pre- and post-MRGO salinity for the period 1951 to 1963 and 1963 to 1977. 

Table 1-4: Pre- and Post-MRGO Salinity (ppt)

Month

Pass Manchac North Shore Little Woods Chef Pass Alluvia City

Pre- Post- Pre- Post- Pre- Post- Pre- Post- Pre- PostJanuary 1.1 1.5 3.0 4.0 3.9 5.0 3.8 5.7 6.8 9.8

February 1.0 1.5 2.5 3.0 3.0 6.5 .9 4.8 6.4 9.7

March 1.0 1.2 1.9 2.6 2.3 4.4 2.2 4.3 6.3 10.4

April 0.8 1.3 1.9 2.6 2.4 4.0 2.2 4.0 7.0 10.0

May 1.0 1.1 2.4 2.7 2.2 3.9 2.6 4.0 9.5 10.2

June 1.0 1.5 3.6 3.0 2.2 3.8 3.3 4.2 9.0 12.3

July 1.0 1.6 3.0 4.6 2.1 4.4 3.2 6.3 7.9 16.0

August 1.2 1.7 4.6 5.6 2.5 4.8 4.8 7.5 8.6 16.1

September 1.7 2.0 5.4 7.5 4.5 6.2 6.0 8.5 8.2 12.9

October 1.8 2.2 4.7 7.3 4.9 6.8 5.2 8.4 7.6 13.8

November 1.8 2.1 4.6 6.7 4.8 6.8 5.2 8.0 8.0 13.1

December 1.2 1.8 4.5 5.4 4.7 6.2 4.2 7.0 8.0 12.5

Monthly summaries of salinity for pre- and post-MRGO construction indicate that 

salinity has increased on the average (figure 1-6) by the following:

• 0.4 ppt Pass Manchac near Ponchatoula 

• 1.1 ppt North Shore, Lake Pontchartrain 

• 1.9 ppt Little Woods, Lake Pontchartrain 

• 2.3 ppt Chef Menteur Pass near Lake Borgne

• 4.5 ppt Shell Beach near Bayou La Loutre

1.4.2 Land Loss

Land loss is a concern 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. It is difficult to single out a specific 

cause for land loss, which is believed to result from complex interactions between natural 

and human activities on the landscape. 

The construction, operation and maintenance of the MRGO caused the loss of 

approximately 24,610 acres and indirectly to an additional loss of 33,920 acres. 

Approximately 63,178 acres of land is estimated to have been lost in the study area from 

1985 through 2010 (Wetland Value Assessment, appendix M). Approximately 131,091 

acres are projected to be lost between 2010 and 2065 (appendix M) within the study 

area. 
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Restoration Plan 1-17 June 2012

Figure 1-6: Salinity Impacts of the MRGO
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Table 1-5 represents the acres lost or gained over the life of the project based on land 

loss rates per planning subunit. The highlighted subunits (7, 13, 17, 18, 21, 23, 32, 36 

and 40) are the ones chosen in which to implement measures. Note that subunits 15, 20, 

48, and 49 are gaining acreage in the future without project (FWOP). 

Table 1-5: Land Loss Rates

Planning 

Subunit

FWOP Total Acres 

Lost/Gained by 

Year 2065

FWP Total Acres 

Lost/Gained by 

Year 2065

1 -9,926 -9,926

2 -37 -37

5 -4,483 -4,483

6 -16,806 -16,806

7 -12,922 391

8 -403 -403

9 -496 -496

10 -2,284 -2,284

11 -8,758 -8,758

12 -5,265 -5,265

13 -4,467 49*

14 -2,984 -2,984

15 277 277

16 -328 -328

17 -5,460 162

18 -6,765 98

19 -348 -348

20 476 476

21 -588 -62

22 -626 -626

23 -12,448 1,512

25 -515 -515

26 0 0

27 -2,989 -2,989

28 -34 -34

29 -542 -542

31 -9 -9

32 -1,576 33

33 -1,471 -1,471

36 -3,750 480

38 -3,888 -3,888

39 -5,667 -5,667

40 -6,439 1,202

47 -522 -522

48 670 670

49 415 415

50 -255 -255

*Subunit 13, Central Wetlands, is separated into swamp and marsh; 49 acres 

gained was derived by combining the two habitat totals which are marsh = 

185 and swamp = -136.
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1.4.3 Bank/Shoreline Erosion

Natural causes of erosion include tropical storm events and natural tidal processes. 

Navigation channels serve as direct routes subjecting inland areas to tidal forces and 

wave action thereby increasing erosion. The firmer soils of lakes, bays, and natural 

ridges along waterways are susceptible to wind-induced erosion. When these firmer soils 

erode away, organic marsh soils are directly exposed to open water wave attack.

Emergent wetlands located adjacent to the MRGO are impacted by wave action from 

vessels and wind resulting in erosion rates between 27 and 38 feet per year (USACE, 

2004). The Lake Borgne shoreline continues to erode due to wind, waves and tidal surge, 

at a rate of 7 feet to 15 feet per year (Barras, 2006). Interior wetlands are subsiding at a 

rate of 0.50 feet per century because of natural deltaic processes. Figure 1-7 shows the 

average shoreline retreat rates around Lake Borgne. Shoreline retreat rates average from 

9 feet per year at Alligator Point to 7 feet per year at the Golden Triangle to 27 feet per 

year along the north shoreline of the Biloxi Marsh (UNO, 2001). 

Saucier (1963) calculated the Lake Pontchartrain shoreline retreat by 1-mile stretches of 

shoreline and determined that the southwestern shoreline was retreating at an average rate 

of 8.8 feet per year compared to 3.6 feet per year on the north shore and 5.6 feet per year 

on the south shore. Saucier (1963) attributed the shoreline movement to subsidence, the 

lack of sediment input, increasing fetch, and sea level rise. 

Figure 1-7: Average Shoreline Retreat Rates
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1.4.4 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 has resulted 

in habitat changes and loss (figure 1-8). In some areas, loss of habitats with high friction 

factors, such as swamp forests, has led to higher storm surge risk. As presented in table 

1-3, approximately 4,750 acres of shallow water has converted to deep water habitat. 

The Central Wetlands area once supported a healthy productive swamp habitat. Much of 

the cypress swamp has deteriorated and converted to brackish marsh due to saltwater 

intrusion attributed to the MRGO. 

(Source: CLEAR)

Figure 1-8: Potential Pathways of Change among Habitats and the Associated 

Driving Forces 

1.4.5 Modification of Natural Hydrology

Mississippi River Levees 

Seasonal flooding that provided sediments and nutrients critical to the healthy wetland 

productivity has been eliminated by the addition of an extensive levee system on top of 

the natural levee system. The levee system extends for approximately 310 miles from the 

Old River Control Structure to Venice, Louisiana. Sediment carried by the Mississippi 

River is now discharged off the coast, depriving wetlands of this vital resource. 

Hydrologic alterations resulting from levees, canals, and other physical alterations are the 

predominant stressors on the ecosystem. 

Levee building along the Mississippi River at New Orleans began around 1727 and 

extended to Baton Rouge by 1812. Levees increased the height of the flood crest on the 

Mississippi River, which resulted in floodwaters discharging through breaches or 

crevasses. The crevasse events were sporadic, allowing Mississippi River water to enter 

Lake Pontchartrain on the average once every four years between 1849 and 1892 (Sikora, 
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Restoration Plan 1-21 June 2012

1985). In 1931, the Bonnet Carré Spillway was completed, enabling the USACE to 

control the Mississippi River discharge and protect the City of New Orleans from 

flooding. 

Because of the levee system, sediment no longer nourishes coastal barrier shorelines, 

which are starved for sediment and eroding. To exacerbate the situation, there is a 

measurable decline in the sediment load from the rest of the drainage basin delivered by 

the Mississippi River in the last 50 years (Coast, 2050). 

Canals 

The oil industry created a vast network of canals, pipelines, and production facilities 

stretching from the Gulf of Mexico inland to freshwater habitats, resulting in saltwater 

intrusion, particularly during droughts and storm events. A majority of the canal 

dredging occurred between 1950 and 1980. The excavated material from dredging canals

was side-cast on adjacent marsh, resulting in altered water flow across wetland habitats. 

Hydrologic alterations affect important hydro-geomorphic, biogeochemical, and 

ecological processes, including chemical transformations, sediment transport, vegetation 

health, and organism migration. Dredge material piled along the banks increased the 

period of marsh inundation causing water logging and plant mortality. More importantly, 

dredge material piled along the banks blocks movement of resuspended sediments from 

storm events, which play a major role in sustaining marsh height (Reed et al., 1997). 

Canal dredging not only switched land to water, but also indirectly changed the processes 

essential to a healthy marsh.

1.4.6 Lake Borgne Ecosystem

The majority of the MRGO is located within the Lake Borgne ecosystem. As previously 

indicated, the MRGO altered natural hydrology and contributed to saltwater intrusion, 

which in turn caused habitat change and loss. Other factors contributing to ecosystem 

degradation include levees and canals, sea level rise, and subsidence. 

Historically, seasonal flooding of the Mississippi River created natural levees, which 

influenced the direction of the river and provided sediments and nutrients to wetlands 

behind the levees. As the natural levees increased in height and size, the location and 

course of distributaries, river meanders, and river channels changed over a geologic scale 

of time. Construction of flood protection levees on top of existing natural levees within 

the watershed of the Mississippi River permanently disrupted this natural process. 

Navigation channels and canals dredged for oil and gas exploration and extraction have 

altered the hydrology of the coastal area. North-south channels and canals have brought 

saltwater into fresh marshes where the salinity and sulfides killed the vegetation. 

Saltwater intrusion, caused by channel deepening, endangers the potable water supply of 

much of the New Orleans metro-area. Canals result in increases in tidal processes that 

increase erosion of marsh habitat. East-west canals impede sheet-flow, pond water on the 

marsh, stress the marsh, and result in wetland loss. 
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FEIS MRGO Ecosystem

Restoration Plan 1-22 June 2012

1.4.7 Retreating and Eroding Barrier Islands

Barrier islands act as a buffer to reduce the effects of ocean waves and currents on 

associated estuaries and wetlands. Louisiana barrier islands are the remains of an 

abandoned Mississippi River Delta; and their degradation is the result of natural deltaic 

processes. The formation of Cat Island in Mississippi was also influenced by this 

abandoned delta, and is distinct from other Mississippi barrier islands (Schmid, 2001). 

Louisiana's barrier islands are eroding at a rate of up to 65 feet per year and, according to 

recent USGS estimates, several will disappear by the end of the century (LACPR, 2008). 

Figure 1-9 depicts an aerial view of Breton Island that was taken in 2009. Although Cat 

Island has lost 39 percent of the land area it had in 1848, it is the most stable of the 

Mississippi barrier islands.

Figure 1-9: Aerial View of Breton Island (2009) 

1.4.8 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. Intact ridges reduce intrusion of saltwater into fresher 

marsh areas. Natural factors, such as subsidence, have contributed to the destruction of 

the ridges. The construction of the MRGO directly affected the Bayou La Loutre Ridge 

by cutting the channel through the ridge. This resulted in a direct link between the Gulf 

of Mexico and the interior estuaries. Construction of the MRGO channel directly 

impacted 24,610 acres and indirectly impacted 33,920 acres, as well as contributing to the 

salinity patterns in Lake Pontchartrain and Lake Borgne. 

1.4.9 Invasive Species

The aggressive spread of invasive species decreases native plant communities, rapidly 

altering ecosystem function. Disturbed ecosystems are more vulnerable to invasive 
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FEIS MRGO Ecosystem

Restoration Plan 1-23 June 2012

species than stable ecosystems; therefore, invasive species are a severe threat to 

biodiversity and ecological function in the study area. The MRGO dredge material banks 

are largely comprised of the invasive Chinese tallowtree (Triadica sebifera, formerly

Sapium sebiferum), an invasive species found in the study area that provides less value to 

the foraging of migrating avian species. 

1.4.10 Herbivory

During the 1930s, nutria (Myocastor coypus) were released into the coastal wetlands. 

The population has rapidly expanded and their grazing and foraging for plant roots has 

been a major contributor to wetland losses (LACPR, 2008). Additionally, native muskrat 

eat-outs may also result in significant local impacts to area marshes. Although 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). 

1.4.11 Increasing Susceptibility to Storm Surge 

The water control structures (levees, floodgates, etc.) that protect the developed 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, thus 

threatening communities and valuable infrastructure.

1.5 RESTORATION GOALS

Restoring natural processes, such as reconnecting the floodplain with the Mississippi

River system’s hydrologic cycles, is the key to restoring the ecosystem damaged by the 

construction and operation of the MRGO. Restoring some degree of these natural 

processes holds the best promise for significant improvements to the deltaic processes in 

the lower Mississippi River system. Priority was given to restoration measures that 

contribute to restoring natural processes.

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. 

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 special coverage of fresh/intermediate marsh in the 

Central Wetlands, Golden Triangle, MRGO, and South Lake Borgne by at 

least 6,800 acres by 2065. 
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FEIS MRGO Ecosystem

Restoration Plan 1-24 June 2012

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

Bouefs, 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. 

1.6 STUDY OBJECTIVES

Study objectives were developed as specific targets to guide the development of measures 

and gauge the extent the plans meet the overarching study goals. Metrics were used to 

measure how the alternative plans meet the specific targets. Study objectives include 

targets for salinity, habitat diversity, and landscape features critical to storm surge risk 

reduction. Salinity targets were based on ecosystem health and oyster production. 

Habitat targets were based on direct and indirect habitat impacts of the MRGO navigation 

channel as described in section 1.3.1. Critical landscape targets for storm surge risk 

reduction were based on features identified in the LACPR Final Technical Report 

(LACPR, 2008). Table 1-6 identifies the study goals and objectives, the portion of the 

study 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.

Objective 1 – Salinity Targets

The first objective is to restore historic salinity conditions in the study area to re-establish 

and maintain historic habitat type; 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, as depicted on figure 1-10. On April 20, 2009, 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 purposes (USACE, 1984). The salinity 

targets are based on mean monthly averages and are graphically presented in figure 1-11

and table 1-7. 
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FEIS MRGO Ecosystem

Restoration Plan 1-25 June 2012

Figure 1-10: Salinity Line (Chatry Line) Depicted Across Biloxi Marsh

Figure 1-11: Salinity Target

Salinity (ppt)

Month

Biloxi Marsh Salinity Targets

Range Limits

Optimum Limits

Target
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FEIS MRGO Ecosystem

Restoration Plan 1-26 June 2012

Table 1-6: Goals, Objectives, Metrics and Measures

WRDA 2007 

Authority Goal(s) Objective Problem Opportunity 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 

natural features 

of the ecosystem 

that will reduce 

or prevent 

damage from 

storm surge.

2. Restore native habitat acreages 

impacted by the MRGO 

- 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, Buy-outs, 

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 

coverage of vegetated wetlands in 

areas adjacent to the channel lost to 

increased tides and salinity by at least 

3,900 acres by 2065.
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FEIS MRGO Ecosystem

Restoration Plan 1-27 June 2012

Table 1-6: Goals, Objectives, Metrics and Measures

WRDA 2007 

Authority Goal(s) Objective Problem Opportunity Metric

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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FEIS MRGO Ecosystem

Restoration Plan 1-28 June 2012

Table 1-7: Monthly Salinity Targets

Month

Chatry 

Target

Chatry Optimum

Limits

Chatry Range 

Limits

Low High Lowest Highest

January 16.4 15.5 17.5 15.0 19.0

February 14.4 13.5 15.0 11.0 17.0

March 11.6 10.5 12.5 7.5 15.0

April 8.0 7.0 9.5 2.0 13.0

May 7.0 6.0 8.0 4.5 11.5

June 12.5 12.0 13.5 9.0 16.0

July 12.7 12.5 13.0 10.5 15.0

August 15.7 15.0 16.5 13.0 17.5

September 17.0 16.0 18.0 15.0 24.0

October 16.8 16.0 18.0 13.0 18.5

November 16.1 15.0 17.0 11.5 18.5

December 15.7 15.5 16.5 13.0 17.0

The salinity targets were originally developed and adopted by an ad hoc group consisting 

of representatives from USACE, Louisiana Department of Wildlife and Fisheries 

(LDWF), U.S. Department of Commerce – National Oceanic and Atmospheric 

Administration - National Marine Fisheries Service (NMFS), St. Bernard Parish, LDNR 

and the Mississippi Department of Marine Resources (MDMR) 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 ad hoc group determined that salinity should mimic historical 

conditions when the Mississippi River over-topped 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 

considered the best indicator species to determine the optimum salinity range for the 

overall commercial fishery in Louisiana (LPBF, 2006b). Oysters also directly contribute 

to the larger ecosystem by filtering water and providing reef surface for other organisms 

to grow. 

The Salinity Working Group for the MRGO study 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.

Objective 2 – Habitat Targets 

The target acres for each habitat type were developed using the direct and indirect habitat 

impacts from the construction and operation of the MRGO between 1956 and 2008. The 

number of acres, presented in these objectives are considered the minimum restoration 

target to address the study authority (table 1-8). 

 NOTE: Salinity targets were estimated to the nearest 0.5 ppt using the graphical display in Chatry et at. (1983)
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FEIS MRGO Ecosystem

Restoration Plan 1-29 June 2012

Table 1-8: Habitat Targets (in area)

Habitat Type

Direct 

Loss

Indirect 

Loss

Indirect 

Gain Net Target

Fresh /

Intermediate marsh -3,400 -3,400 -6,800 6,800

Brackish marsh -10,300 -19,200 11,400 -18,100 18,100

Saline marsh -4,200 19,200 +15,000 0 

Cypress swamp -1,500 -8,000 -9,500 9,500

Shallows -4,800 4,800* 0+* 0 

Additional marsh** -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 on the habitat of the Bayou La Loutre Ridge are not 

quantified, the channel made a 500-foot cut through the ridge, destroying ridge habitat 

and a natural salinity barrier. To address the MRGO construction impacts to this habitat, 

the study will evaluate 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: 

• Areas located in the Biloxi Marshes, 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 effects 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. 
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FEIS MRGO Ecosystem

Restoration Plan 1-30 June 2012

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 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., X acres of marsh will produce 

Y feet 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 (LACPR, 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 provide some benefit with regard to 

hurricane storm damage risk reduction. 
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FEIS MRGO Ecosystem

Restoration Plan 1-31 June 2012

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 opportunities for citizens to enjoy and understand the significance of the resources 

this study seeks to restore. 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. 

1.7 HABITAT EVALUATION TEAM 

A Habitat Evaluation Team (HET) was established to assist in the plan formulation and 

evaluation process, as well as provide input and data for preparation of the DEIS. 

Membership on the HET includes participants from Louisiana, Mississippi and Federal 

agencies, as well as USACE members from the New Orleans and Mobile Districts, and 

the Engineer Research and Development Center (ERDC) as listed below:

• USACE, New Orleans District

• USACE, Mobile District

• USACE, Engineer Research and Development Center, Environmental Laboratory, 

Vicksburg, MS 

• U.S. Fish and Wildlife Service, Louisiana

• U.S. Fish and Wildlife Service, Mississippi 

• U.S. Environmental Protection Agency 

• National Marine Fisheries Service, Louisiana

• National Marine Fisheries Service, Mississippi

• Natural Resources Conservation Service 

• United States Geological Survey

• Bureau of Ocean Energy Management, Regulation and Enforcement 

• Louisiana Department of Wildlife and Fisheries

• Office of Coastal Protection and Restoration, Louisiana 

• Louisiana Department of Natural Resources

• Louisiana Department of Environmental Quality 

• Mississippi Department of Marine Resources

• Mississippi Department of Environmental Quality

Additional members that participated in the Salinity Working Group include: 

• Louisiana State University, Louisiana

• University of New Orleans, Louisiana 
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FEIS MRGO Ecosystem

Restoration Plan 1-32 June 2012

• University of Southern Mississippi, Mississippi

1.7.1 Tasks

The HET actively participated throughout the study process, providing input in the 

formulation of coastal restoration measures and alternatives, identifying screening criteria 

for evaluating the restoration plan, and quantifying the environmental impacts and 

benefits of those plans. 

1.7.2 Guiding Principles

The team adopted several of the guiding principles established the draft LACPR 

Technical Report, Coastal Restoration Appendix that were applicable to this study area. 

The overarching principle adopted 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 and 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 surge risks 

(USACE, 2009). While the models show benefits from additional marsh, barrier 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 of Mexico 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. 
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Restoration Plan 1-33 June 2012

1.7.3 Approach

A number of studies and reports on Louisiana’s coastal ecosystem and water resources 

development in the study area have been prepared. These previous studies established an 

extensive database for the LCA Study, which in turn served as a significant starting point 

for the LACPR State’s Master Planning Process and this restoration plan. Historical 

trends and existing conditions were identified to provide insight into future conditions, 

help isolate the problems, and identify the most critical areas for restoration.

1.8 NATIONAL ENVIRONMENTAL POLICY ACT

The NEPA of 1969 (Public Law 91-190) requires all Federal agencies to address 

environmental consequences of major Federal actions on the natural and human 

environment. Compliance guidance for NEPA is contained in Title 40 of the Code of 

Federal Regulations (CFR), Parts 1500 through 1508, and in the USACE regulations 33 

CFR 230 and 325, Environmental Quality and Procedures for Implementing NEPA. The 

primary intent of NEPA is to ensure that environmental information is made available to 

public officials and citizens regarding major actions taken by Federal agencies, and to 

identify and consider concerns and issues from the public. 

This FEIS analyzes and documents the potential beneficial and adverse environmental 

impacts of implementing the tentatively selected plan. As established by the Council on 

Environmental Quality (CEQ). This report incorporates by reference other 

environmental documents covering coastal restoration in Louisiana. 

This FEIS is tiering off the LCA, FPEIS and ROD signed January 31, 2005. 

This FEIS adopts, in their entirety or identified portions thereof, previous NEPA 

documents. All NEPA documents related to the project and study area are listed in 

section 1.8.1. Vital documents and/or portions being adopted include: 

• Coast 2050: Toward a Sustainable Coastal Louisiana

• LCA Ecosystem Restoration Study 

• MRGO Deep-Draft De-Authorization Project. 

1.8.1 Environmental Assessments and Environmental Impact 

Statements

Many Environmental Assessments (EA) and EISs have been prepared to evaluate 

potential impacts of project-specific proposed actions within the study area. 

• EIS, entitled “Lake Pontchartrain, LA and Vicinity Hurricane Protection Project 

Riprap shore protection with openings at Bayous Bienvenue and Dupre,” 1973 

and 1974. 
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FEIS MRGO Ecosystem

Restoration Plan 1-34 June 2012

• EIS, entitled “Lake Borgne Vicinity MRGO Bayous La Loutre, St. Malo, and 

Dupre”, ROD signed March 1976. 

• EA #15, entitled “Transfer of Land Along Mississippi River – Gulf Outlet 

Jourdan Road Terminal to Inner Harbor Navigation Channel,” with a Finding of 

No Significant Impact (FONSI) signed on December 15, 1980. 

• EA #38, entitled “MRGO, Foreshore Protection Test Section,” with a FONSI 

signed on August 15, 1983. 

• EA #47, entitled “MRGO Foreshore Protection,” with a FONSI signed on January 

23, 1985. 

• EA #54, entitled “South Bank Mississippi River – Gulf Outlet – Borrow Site,” 

with a FONSI signed on April 1, 1986. 

• EA #72, entitled “MRGO Breton Sound Jetty Repairs,” with a FONSI signed on 

May 26, 1988. 

• EIS, entitled “Mississippi River – Gulf Outlet Ocean Dredged Material Final 

EIS,” ROD signed May 1989. 

• EA #143, entitled “Mississippi River – Gulf Outlet – New Canal, Remedial 

Dredging,” with a FONSI signed on September 11, 1991. 

• EA #152, entitled “MRGO St. Bernard Parish, LA, Bank Stabilization, Miles 50.5 

to 55.0,” with a FONSI signed on November 21, 1991. 

• EA #154, entitled “Mississippi River – Gulf Outlet – Major Rehabilitation of the 

South Jetty in Breton Sound,” with a FONSI signed on December 23, 1991. 

NOTE: no EA available, this is date of Memorandum to discontinue work. 

• EA #162, entitled “Mississippi River – Gulf Outlet, St. Bernard and Plaquemines 

Parishes, LA – Marsh Enhancement/Creation and Berm Construction,” with a 

subsequent FONSI signed on July 10, 1992. 

• EA #244, entitled “MRGO Back Dike (CWPPRA), Disposal Area Marsh 

Protection, Back Dike,” with a FONSI signed on July 30, 1996. 

• EA #247, entitled “MRGO St. Bernard Parish, LA, Bank Stabilization Miles 55.0 

to 56.1,” with a FONSI signed on September 24, 1996. 

• EA #255, entitled “MRGO, LA, Wetland Creation, Miles 15.0 to 23.0, St. 

Bernard and Plaquemines Parish, LA,” with a FONSI signed on February 12, 

1997. 

• EA #269, entitled “MRGO, LA, South of Lake Borgne Additional Disposal 

Areas, St. Bernard Parish, LA,” with a FONSI signed on March 24, 1998. 

• EA #269-B, entitled “MRGO, South of Lake Borgne Additional Disposal Areas 

plus Deflection Dike and Floatation Channels, St. Bernard Parish, LA,” with a 

FONSI signed on June, 2000. 

• EA #269-C, entitled “MRGO, LA, Construction of Flotation Channels Miles 51.0 

to 48.0, St. Bernard Parish, LA,” with a FONSI signed on October 2, 2001. 

• EA #274, entitled “MRGO, Additional Disposal Areas, Hopedale Marshes,” with 

a FONSI signed on July 10, 1998. 

• EA #277, entitled “MRGO, LA, Shell Beach Disposal Areas, St. Bernard Parish, 

LA,” with a FONSI signed on September 6, 2001. 

• EA #277-A, entitled “MRGO, LA, Construction of Flotation Channels Miles 49.0 

to 38.0, St. Bernard Parish, LA,” with a FONSI signed on October 2, 2001. 
Chapter 1 Introduction

FEIS MRGO Ecosystem

Restoration Plan 1-35 June 2012

• EA #288, entitled “MRGO Mile 43 to Mile 41 North Bank Stabilization, St. 

Bernard Parish, LA,” with a FONSI signed on November 8, 1999. 

• EA #349, entitled “MRGO, Miles 32-27, Additional Disposal Areas – Hopedale 

Marshes, St. Bernard Parish, LA,” with a FONSI signed on August 15, 2002. 

• EA #354, entitled “MRGO, Additional Disposal Area Designation Miles 66.0 to 

49.0, St. Bernard Parish, LA,” with a FONSI signed February 9, 2004. 

• EA #355, entitled “MRGO Mile 27.0 to 0,” with a FONSI signed on June 30, 

2003. 

• EA #361, entitled “MRGO, LA, Test Installation of Articulated Concrete 

Mattressing, Miles 39.0 to38.0,” with a FONSI signed on January 29, 2003. 

• EA #402, entitled “Lake Borgne – MRGO, Shoreline Protection Project, St. 

Bernard Parish, LA,” FONSI signed on December 16, 2004. 

• EA #403, entitled “MRGO, Hopper Dredging Miles 27.0 To 66.0,” FONSI signed 

on March 22, 2004. 

• EA #411, entitled “MRGO, Installation of Articulated Concrete Mattressing, 

Miles 37.4 to 36.5, St. Bernard Parish, Louisiana,” FONSI signed on October 19, 

2004. 

• PEIS #03-01, entitled “Programmatic Environmental Impact Statement for the 

Louisiana Coastal Area (LCA), Louisiana – Ecosystem Restoration Study,” ROD

signed January 31, 2006. 

• EA #468, entitled “Mississippi River – Gulf Outlet Reuse of MRGO Jetty Rock 

St. Bernard Parish, Louisiana,” FONSI signed on July 21, 2008. 

• LEIS #07-04, entitled “Integrated Final Report to Congress and Legislative 

Environmental Impact Statement for the Mississippi River – Gulf Outlet DeepDraft De-authorization Study,” ROD signed June 5, 2008. 

• FEIS #06-12, entitled “Environmental Impact Statement (EIS) for the Mississippi 

River-Gulf Outlet (MRGO), Louisiana, and Lake Borgne – Wetland Creation and 

Shoreline Protection Project,” transmitted to EPA June 2009. A ROD was signed 

March 18, 2010. 

NEPA documents currently under development within the study area include: 

• PDEIS #09-01, entitled “West Shore – Lake Pontchartrain, Louisiana, Hurricane 

and Storm Damage Risk Reduction,” 2009. 

• 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. 

• PDEIS #07-02, entitled “NOV Hurricane Protection Project: Incorporation of 

Non-Federal Levees from Oakville to St. Jude, Plaquemines Parish Louisiana,” 

Notice of Intent (NOI) filed February 26, 2007. 
Chapter 1 Introduction

FEIS MRGO Ecosystem

Restoration Plan 1-36 June 2012

1.8.2 NEPA Scoping

Scoping is a critical component of the overall public involvement program to solicit input 

from affected Federal, state, and local agencies, Indian Tribes, and interested 

stakeholders. The NEPA scoping process is designed to provide an early and open means 

of determining the scope of issues (problems, needs, and opportunities) to be identified 

and addressed in the DEIS. Scoping is the process used to: a) identify the affected public 

and agency concerns; b) facilitate an efficient EIS preparation process; c) define the 

issues and alternatives that will be examined in detail in the EIS; and d) save time in the 

overall process by helping to ensure that relevant issues are adequately addressed. 

Scoping is a process, not an event or a meeting; it continues throughout the EIS (draft and 

final) process and may involve meetings, telephone conversations, and/or written 

comments. 

A Notice of Intent (NOI) to prepare a DEIS for the 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 two public scoping 

meetings were organized and hosted in accordance with NEPA on November 3, 2008, 

and November 6, 2008. Public meeting announcements were published on October 30, 

2008, and November 1, 2008, in the Times-Picayune; October 31, 2008, in the St. 

Bernard Voice; November 1, 2008, in the Baton Rouge Advocate; November 2, 2008, in 

the Biloxi Gulfport Sun Herald; and November 5, 2008, in the Bay St. Louis Sea Coast 

Echo. The public notice was mailed to the stakeholder and NEPA mailing lists for the 

CEMVN and Mobile District on October 17, 2008, (appendix A). Scoping meeting 

notices were also placed on the MRGO website and the St. Bernard Parish website.

The scoping comment period began with the filing of the NOI and continues through 

release of the DEIS for public comment. Public scoping meetings were held on 

November 3, 2008, in Chalmette, Louisiana, and November 6, 2008, in Waveland, 

Mississippi. Greater participation was received in Chalmette, Louisiana, 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. 

Comments were evaluated for recurring themes to gain an understanding of the key 

issues to address in the DEIS. Eighteen recurring themes were identified. See table 1-9 

for a full listing of recurring themes and their percentage of occurrence. The highlighted 

area represents the top 10 recurring themes, which account for 80 percent of the 

comments. All comments were reviewed by the PDT to determine the significance of 

each comment, regardless of the recurrence of the comment.
Chapter 1 Introduction

FEIS MRGO Ecosystem

Restoration Plan 1-37 June 2012

Of the total of 322 comments received, 19 were off topic and not considered a part of this 

analysis. Two additional types of comments that did not fall into themes are identified, 

but not included, in the overall theme analysis. There are 16 instances in which the entire 

comment appears to be relevant, but does not fall easily into the identified themes. 

Another group of 15 comments addressed the USACE or the meeting process. Analysis 

of the comments shows these types of comments to be 40 percent positive and 26 percent 

negative with the remaining 34 percent neutral. 

The scoping comments were documented in a Scoping Report and describe the public’s 

concerns about the restoration effort and strategies for restoration efforts. See appendix 

A for the Scoping Report. Public involvement is discussed further in chapter 5. 

Registered scoping meeting participants, as well as those providing written or verbal 

comments, were advised of the availability of the Scoping Report on the study website at 

http://www.mrgo.gov. 

Table 1-9: Scoping Comment Themes by Percentage of Occurrence

Ranking Theme

Number of 

Comments

Percent 

Occurrence

1. Sediment diversions are needed to help restore marshes/wetlands. 51 13.5% 

2. Restore the ecosystem to pre-disturbance/historical conditions. 43 11.3% 

3. Restoring the first line of hurricane defense for public safety is a priority. 40 10.6% 

4. Focus on restoring flow of water (hydrology). 33 8.7% 

5. Implement/incorporate existing plans. 30 7.9% 

6. Restoration project needs to be started as soon as possible (ASAP) 26 6.9% 

7. Restore barrier islands (Chandeleur). 23 6.1% 

8. Socio-economic impacts need to be considered. 21 5.5% 

9. Address saltwater intrusion, but maintain brackish water in areas 

(Caernarvon, Bayou Bienvenue). 20 5.3% 

10. Restore ridge areas along levees that are under threat of being destroyed. 17 4.5% 

11. Dredging should be considered as a method to restore natural areas. 15 4.0% 

12. Stabilize and preserve existing land that is under threat of loss or 

conversion to open water. 13 3.4% 

13. Repair/restore Violet Siphon. 10 2.6% 

14. Structural methods/controls to close MRGO. 10 2.6% 

15. Rebuild levees and walls in the region (Verret to Yscloskey). 9 2.4% 

16. Use resources as efficiently as possible to get the MRGO project 

completed. 8 2.1% 

17. Use jetty rock for shoreline protection. 7 1.8% 

18. Opportunities for mitigation need to be identified. 3 0.8% 

Total: 379 100%

NOTE: Green highlighted rows represent the top ten themes. The number of occurrences totals 379 because a given comment can be associated 

with more than one theme. The percentages are based on dividing the number of occurrences of a given theme by the total number of occurrences 

and multiplying by 100.
Chapter 1 Introduction

FEIS MRGO Ecosystem

Restoration Plan 1-38 June 2012

1.8.3 Cooperating Agencies

Cooperating Agencies (as defined under 40 CFR 1501.6) include: Department of the 

Interior – U.S. Fish and Wildlife Service (USFWS); NMFS; Department of Agriculture – 

Natural Resources Conservation Service (NRCS); U.S. Environmental Protection Agency 

(EPA) and the Bureau of Ocean Energy Management, Regulations and Enforcement. 

Other participating agencies include the Louisiana Department of Environmental Quality 

(LDEQ), the LDWF, the LDNR, and the Mississippi Department of Marine Resources 

(MDMR). 

1.8.4 Compliance with Laws and Executive Orders

Coordination and evaluation of required compliance with specific laws, executive orders, 

and other policies for the various alternatives will be achieved, in part, through the 

coordination of this document with appropriate agencies and the public. Table 1-10

summarizes the level of compliance with those statutes, orders, and policies. Disclosures 

and findings required by these laws and orders are contained in chapter 6 of this DEIS.

Table 1-10: Compliance with Environmental Laws, Regulations and Executive Orders

Law, Regulation or 

Policy Status Comments Full Compliance Expected

Clean Air Act of 1970 Coordination 

complete

An air quality analysis was conducted. 

The tentatively selected plan would not 

significantly impact air quality. The 

study area would remain in attainment. 

LDEQ correspondence dated January 11, 

2011.

Full compliance after review of 

FEIS by EPA and upon signing of 

the Record of Decision (ROD)

(appendix P) 

Clean Water Act of 1977 Coordination 

complete

The final 404(b)(1) evaluation is 

complete. Water quality certification has 

been met and the placement of fill 

material will not violate water quality 

standards. LDEQ correspondence dated 

February 02, 2012. National Pollutant 

Discharge Elimination System (NPDES) 

non-point source permit will be required 

and obtained before construction 

commences.

Consistency determination received 

from LDEQ and upon signing of the 

ROD (appendix E; appendix S) 

National Environmental 

Policy Act of 1969

Coordination 

on-going

The DEIS has been coordinated with 

Federal/State Agencies. The EPA rated 

the DEIS document as EC-2. The FEIS 

addresses EPA comments. 

Full compliance upon coordination 

of the FEIS, remaining public 

involvement activities completed, 

and upon signing of the ROD

Fish and Wildlife 

Coordination Act of 1958

Coordination 

complete

USFWS and U.S. Department of the 

Interior (DOI) are active team 

participants and have provided input on 

fish and wildlife resources in the project 

area. A final Fish and Wildlife 

Coordination Act Report (FWCAR) was

completed in March 13, 2012. NIMFS 

issued A Biological Opinion (BO) on 

May 3, 2012.

Full compliance upon signing of the 

ROD (appendix B) 
Chapter 1 Introduction

FEIS MRGO Ecosystem

Restoration Plan 1-39 June 2012

Table 1-10: Compliance with Environmental Laws, Regulations and Executive Orders

Law, Regulation or 

Policy Status Comments Full Compliance Expected

Endangered Species Act 

of 1973

Coordination 

complete 

A final BA has been submitted to NMFS 

and USFWS as part of the formal and 

informal consultation with NMFS and 

USFWS, respectively. USFWS issued a 

letter of concurrence February 8, 2012 

stating project is not likely to adversely 

affect the West Indian Manatee or piping 

plover. NMFS and USFWS reviewed 

the final BA and issued a BO on May 3, 

2012.

Full compliance upon signing of the 

ROD (appendix G)

Magnuson-Stevens 

Fishery Conservation and 

Management Act of 1976

Coordination 

complete

An Essential Fish Habitat (EFH) 

assessment is incorporated in the FEIS in 

section 4.18 and within the final 

FWCAR. Letter received from NMFS 

March 28, 2012

Full compliance upon signing of the 

ROD (appendix B; appendix C) 

Coastal Zone 

Management Act of 1972

Coordination 

complete

The tentatively selected plan is 

consistent with the State of Louisiana’s 

Coastal Resources Program per LDNR 

correspondence dated February 8, 2010.

Full compliance upon signing of the 

ROD (appendix F) 

Coastal Barrier Resources 

Act and Coastal Barrier 

Improvement Act

Not 

applicable

There are no designated coastal barrier 

resources in the study area that would be 

affected by this project. These acts do 

not apply.

Not applicable

Marine Mammal 

Protection Act

Coordination 

complete

A final BA has been submitted to NMFS 

and USFWS as part of the formal and 

informal consultation with NMFS and 

USFWS, respectively. West Indian 

manatee are not likely to be adversely 

affected per USFWS concurrence in 

letter dated Fubruary 8, 2012. Best 

Management Practices for the bullnose 

dolphin would be implemented per 

consultation with NOAA. NMFS and 

USFWS reviewed the final BA and 

issued a BO on May 3, 2012.

Full compliance upon signing of the 

ROD (appendix G)

Marine Protection, 

Research and Sanctuaries 

Act

Coordination 

complete

Disposal of dredge material must comply 

with the Act. 

Full compliance upon signing of the 

ROD

Estuary Protection Act of 

1968

Coordination 

complete

Estuaries would be benefited by this 

project.

Full compliance upon signing of the 

ROD

Anadromous Fish 

Conservation Act

Coordination 

complete

Anadromous fish species would not be 

affected. The project has been 

coordinated with NMFS.

Full compliance after NMFS review 

of the FEIS and upon signing of the 

ROD

Migratory Bird Treaty 

Act and Migratory Bird 

Conservation Act

Coordination 

complete

Migratory birds would benefit by this 

project. A final FWCAR was completed 

March 13, 2012. 

Full compliance upon USFWS 

submittal of FWCAR and upon 

signing of the ROD

(appendix B) 

Wild and Scenic River 

Act of 1968

Coordination 

complete

Coordination with the LDWF Scenic 

Streams Coordinator is on-going. A final 

Scenic River Use Permit would be 

complete in May 2012. USACE to 

submit final permit application. Further 

coordination would be deferred pending 

additional review of the Violet, 

Louisiana Freshwater Diversion.

Full compliance upon signing of the 

ROD (appendix X)
Chapter 1 Introduction

FEIS MRGO Ecosystem

Restoration Plan 1-40 June 2012

Table 1-10: Compliance with Environmental Laws, Regulations and Executive Orders

Law, Regulation or 

Policy Status Comments Full Compliance Expected

Federal Water Project 

Recreation Act

Coordination 

complete

The principles of this Act (PL 89-72) 

have been fulfilled.

Full compliance upon signing of the 

ROD

Submerged Lands Act of 

1953

Coordination 

complete

Coordination with LDNR and LDWF 

has been ongoing.

Full compliance after LDNR and 

LDWF review of the FEIS and upon 

signing of the ROD

Rivers and Harbors Act 

of 1899

Coordination 

complete

The proposed work would not obstruct 

navigable waters of the United States.

Full compliance upon signing of the 

ROD

National Historic 

Preservation Act of 1966 

Coordination 

complete

A Programmatic Agreement has been 

agreed upon and signed between the 

State Historic Preservation Office 

(SHPO), the Advisory Council on 

Historic Preservation (ACHP) and two 

Federally recognized tribes. 

Full compliance upon signing of the 

ROD (appendix D)

Resource conservation 

and Recovery Act 

(RCRA), Comprehensive 

Environmental Response, 

Compensation, and 

Liability Act (CERCLA), 

Toxic Substances Control 

Act of 1976

Coordination 

complete

A Phase 1 hazardous, toxic, or 

radioactive waste (HTRW) assessment 

was performed February 1, 2010 to 

identify sites of concern in the project 

area and vicinity. 

Full compliance upon signing of the 

ROD (appendix Q) 

Farmland Protection 

Policy Act of 1981

Coordination 

complete

Portions of the proposed Violet, 

Louisiana Freshwater Diversion would 

impact prime farmlands. A Farmland 

Conversion Impact Rating worksheet, 

Form AD-1006 has been completed by 

NRCS per correspondence dated January 

12, 2011.

Full compliance upon signing of the 

ROD (appendix R). 

Executive Order (EO)

11988 Floodplain 

Management

Coordination 

complete

Portions of the proposed Violet, 

Louisiana Freshwater Diversion 

(Alternative 1 location) would be located 

in the 100-year and 500-year floodplain. 

The assessment for the diversion is 

programmatic and further study is 

required.

Full compliance after St. Bernard 

Parish Floodplain Administrator 

review of the FEIS and upon 

signing of the ROD 

EO 11990 Protection of 

Wetlands

Coordination 

complete

Design plans for restoration features 

would minimize the loss and/or 

degradation of wetlands. 

Full compliance upon signing of the 

ROD

EO 12898 Environmental 

Justice

Coordination 

complete

Minority or low-income com-munities 

are not disproportionally affected by the 

project. 

Full compliance upon signing of the 

ROD

EO 13089 Coral Reef 

Protection

Not 

applicable

This project would not adversely impact 

coral reefs or coral reef resources. Not applicable

EO 13112 Invasive 

Species

Coordination 

complete

Project is not expected to lead to 

propagation of invasive species.

Full compliance upon signing of the 

ROD

SOURCE: USACE.

1.8.5 Current and Authorized Restoration Projects

The MRGO Ecosystem Restoration Feasibility Report, table 1-2 lists the existing water 

resources projects and their potential application to this study. 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-1 June 2012

CHAPTER 2: ALTERNATIVE FORMULATION

2.1 INTRODUCTION

The “Economic and Environmental Principles for Water and Related Land Resources 

Implementation Studies” and the “Economic and Environmental Guidelines for Water 

and Related Land Resources Implementation Studies”, generally known as the Principles 

and Guidelines (P&G) provides guidance for conducting Civil Works planning studies. 

Ecosystem restoration is one of the primary missions of the U.S. Army Corps of 

Engineers (USACE) Civil Works program. The objective is to contribute to the National 

Ecosystem Restoration (NER), which is increased in the net quantity and/or quality of 

desired ecosystem resources. Measurement of NER is based on changes in ecological 

resource quality, as a function of improvement in habitat quality and/or quantity, and is 

expressed in physical units such as average annual habitat units (AAHU) or acres. 

Restoration plans are formulated and evaluated in terms of their contribution to 

improvement in ecosystem value expressed in a unit measure that is non-monetary.

The Federal planning procedures follow a six-step process structured to approach a 

problem in a rational framework for decision-making. The MRGO Ecosystem 

Restoration Plan Feasibility Report that accompanies this National Environmental Policy 

Act of 1969 (NEPA) document provides more detail and in-depth discussion on the 

planning process for this study and the plan formulation (Note that throughout this 

document the term “MRGO” refers to the former Mississippi River Gulf Outlet 

navigation channel). This FEIS contains a summary of the plan formulation process and 

alternative development and focuses on a description of the development of reasonable 

alternatives to achieving ecosystem restoration. In addition, it describes those 

alternatives considered, but dropped for various reasons. Described below are the 

USACE’s six planning steps and their applicability to the NEPA process:

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 the 

inventory and forecast of resources within the study area. 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 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-2 June 2012

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 problems in the study area. 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. 

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 habitats that are restored or conserved. 

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 tentatively selected plan is identified.

In developing the alternative restoration plans from which the tentatively selected plan 

was chosen, 299 measures were screened and evaluated through a coordinated 

interagency process. The restoration measures were evaluated according to planning 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-3 June 2012

goals, objectives, and performance metrics in which 59 measures were carried forward 

for detailed evaluation. The remaining measures were further evaluated and refined 

during the development of detailed designs, cost estimates, and quantification of 

ecological benefits utilizing Wetland Value Assessment methodology. Four final 

alternatives, which are comprised of a combination of individual measures, resulted from 

the evaluation process, each of which builds upon the other: 

• Alternative A, No Action Plan or future without project (FWOP) 

• Alternative B, MRGO Restoration Plan 2 – small restoration plan

• Alternative C, MRGO Restoration Plan 7 – medium restoration plan

• Alternative D, MRGO Restoration Plan 10 – large restoration plan

2.2 CONCEPTUAL ECOLOGICAL MODEL

2.2.1 Overview

Given the complexity of factors that drive the functioning of the ecosystem within the 

project area, the Engineer Research Development Center (ERDC) Environmental 

Laboratory (EL) assisted the habitat evaluation team (HET) in development of a 

conceptual ecological model (CEM) for the study. The CEM was developed to guide 

plan formulation and the assessment of restoration plans for the MRGO. ERDC EL 

investigators and the HET developed metrics and predictive models for the MRGO 

Restoration Study. 

The development of this CEM utilized other well-documented CEM frameworks 

developed for this system formulated under the Louisiana Coastal Area (LCA) 

Ecosystem Restoration Study and Louisiana Coastal Protection and Restoration 

(LACPR). As presented in chapter 1, the MRGO navigation channel directly impacted 

an estimated 24,610 acres of wetlands and influenced saltwater intrusion with subsequent 

secondary and tertiary impacts. Nonetheless, it is noteworthy to point out that the study 

area is largely degradational even in the absence of the MRGO (see figure 1-1). Within 

the study area a number of restoration measures have been proposed through Coastal 

Wetlands Planning, Protection, and Restoration Act (CWPPRA), Coastal Impact 

Assistance Program (CIAP) and other programs, some of which are targeted to achieving 

restoration objectives specific to MRGO impacts. 

Details of the CEM are provided in appendix H. Below is a description of the major 

processes considered in the model. 

2.2.2 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 dynamic fashion. 

The distribution and abundance of wetland habitats in the deltaic plain has been, and 

continues to be, in constant flux. The changing conditions are a function of the differing 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-4 June 2012

salinity gradients that occur during the land building and degradation phases as well as 

the myriad of other key processes that influence wetland and estuarine conditions. These 

processes include the Deltaic Processes; Marine Processes; Fluvial Processes; Chemical 

Processes; and Biological Processes as briefly described below. These processes are 

described in detail in chapter 3. 

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 mud. 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 lowrelief 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 inches 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 other 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 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-5 June 2012

water bottoms, absorbed 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 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, marine and freshwater organisms,

and avian predators and represent an important link in estuarine trophic dynamics 

(USACE, 2009). 

The key landscape features in the study area are described in chapter 3. 

2.2.3 Important Issues in the Development of Alternatives

The HET identified specific issues (or drivers) that contributed to the conditions of the 

study area. Each of the following issues includes important processes, drivers or 

components identified as critical to the MRGO Ecosystem Restoration Plan Feasibility 

Report. Effects on each of these components by MRGO (before and after closure 

structure) and also by proposed measures have been compared (table 2-1). The purpose 

of the table is to support the team in determining which components (issues) have been or 

continue to be affected by MRGO, to what extent each proposed restoration measure may 

influence all components of concern within the study area whether or not affected by 

MRGO and which measures would address those issues specifically affected by MRGO. 

Elements in this table form the basis for the CEM.
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Table 2-1: Effects of MRGO and Selected Ecosystem Restoration Measures on Selected Issues and Drivers in the MRGO Study 

Area Measure 

Issue 

/ Driver

MRGO

Before 

Closure

FWOP+ 

MRGO 

Closure 1

FWOP+ 

Additional 

Measures 2 

River 

Diversions 3

Hydrologic 

Restoration 4 

Marsh 

Restoration 

Shoreline 

Protection

Ridge 

Restoration 5

Forest 

Habitat/ 

Restoration

Barrier 

Islands

Restoration

SAV 

Restoration

Oyster Reef

Restoration

Swamp

Restoration

Reduced 

Freshwater, 

Nutrients, 

Sediment Input

NA NA D↓ I↓ D↓ D↓ I↓ NA NA NA NA NA NA NA NA

Wetland Losses D↑ I↑ D↑ I↑ D↑ I↑ I↓ I↓ D↓ D↓ I↓ D↓ D↓ I↓ I↓ I↓ D↓

Saltwater Intrusion D↑ I↓ D↓ I↓ D↓ D↓ I↓ I↓ NA I↓ NA D↓ NA NA I↓

Essential Fish 

Habitat (EFH)

Degradation

D↑ I↑ D ↑I↓ D↑ I↓ I↓ D↓ I↓ D↓ D↓ I↓ NA D↓ D↓ D↓ D↓

Natural 

Hydrologic 

Process 

Degradation

D↑ D D 6 D↓ 6 D↓ I↓ NI I↓ NA D↓ NI NI I↓

Ridge Habitat 

Degradation D↑ D↓ D↑ I↑ NA I↓ I↓ NI D↓ NA I↓ NI NI I↓

Barrier Islands 

Degradation I↑ I↓ NA NA NA NA NI NA NA D↓ I↓ NI NA

Shoreline Erosion I↑ I↑ I↑ I↓ I↓ I↓ D↓ D↓ I↓ NA I↓ I↓ I↓ I↓

Subsidence NA NA NA I↓ I↓ I↓ NA I↑ NA NA NI NI I↓

Sea Level Rise NA NA NA NA NA NA NA NA NA NA NA NA NA

Storm Surge NA NA NA I↓ I↓ D↓ NA D↓ D↓ D↓ I↓ NA D↓

Marine Habitat 

Degradation D↑ I↑ I↓ D↓ I↓ D↓I↓ D↓ I↓ D↓ I↓ I↑ D↓ I↓ D↓ I↓ D↓ D↓ D↓ D↓ I↓

Freshwater Habitat 

Degradation D↑ I↑ I↓ D↓ I↓ D↓ D↓ D↓ I↓ I↓ I↓ I↓ D↓ NA D↓

Lake Pontchartrain

Dead Zone 

Expansion

D↑ I↑ D↓ I↓ D↓ I↓ I↓ I↓ NI NI NI NI NI NA NA NI

NA = Not Applicable or measure not proposed for selected Issue/Driver

Key to Cell Codes

↑ Increases rate or amount (not “good” or “bad”)

NI = Little to No Impact of Measure on Issue/Driver ↓ Decreases rate or amount (not “good” or “bad”)

D = Direct impact of Measure on Issue/Driver NOTE:

I = Indirect impact of Measure on Issue/Driver

Uncertainty, Predictability, and Strength of impact are not indicated in 

this table

Table 2-1 Footnotes: 1

MRGO before closure

2

FWOP+ MRGO Closure

3

FWOP+ Additional Measures

4

River Diversion Measure Category includes large measures such as Violet, Louisiana Freshwater Diversion. 5

Shoreline Protection refers to Marsh, Lake and Channel shorelines only.

6

. 

Closure of MRGO will not restore natural hydrologic functions and may result in a hypoxic zone within the closed, unfilled MRGO due to anticipated reduction in current velocity
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2.2.3.1 Natural Hydrologic Process Degradation (Hydrologic 

Barriers, Connectivity)

Construction of levees, oil and gas canals, and navigation channels has altered natural 

hydrology, affecting freshwater, sediment, and nutrient transport. Dredged material 

banks block the movement of sediment re-suspended during storms, which play a major 

role in sustaining land elevations (Reed et al., 1997). Channels and canals promote 

saltwater intrusion and increase tidal processes that impact the marsh by accelerating 

erosion. East-west canals impede sheetflow and cause ponding of water on the marsh. 

Canals and channels allow freshwater inputs to discharge quickly from wetlands to be 

rapidly replaced by Gulf of Mexico waters.

Dredged material banks partially impounding wetlands suffer fewer, but longer periods of 

flooding as well as reduced water exchange when compared to un-impounded marshes 

(USACE, 2004). Impoundment results in increased waterlogging and frequently, in plant 

death. 

2.2.3.2 Ridge Habitat Degradation (Hydrologic Barriers)

Ridges are natural levees 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. 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. 

2.2.3.3 Barrier Island Degradation

The barrier islands in the Louisiana portion of the study area are the remains of 

abandoned Mississippi River Delta lobes 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’s distinct from other Mississippi barrier islands (Schmid, 2001). 

Barrier islands act as a buffer to reduce the effects of ocean waves and currents on 

associated estuaries and wetlands. Louisiana's barrier islands are eroding at a rate of up 

to 66 feet per year. According to recent U.S. Geological Survey (USGS) estimates, 

several islands will disappear by the end of the century (LACPR, 2008). Although Cat 

Island has lost 39 percent 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). The disappearance of the barrier islands exposes coastal wetlands to the full force 

and effects of wave action, saltwater intrusion, storm surge, and tidal currents, 

accelerating wetland deterioration.
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2.2.3.4 Storm Surge

Coastal storms, particularly tropical cyclone events, also exert a stochastic, but severe 

influence on the study area. Data obtained from the National Oceanic and Atmospheric 

Administration (NOAA) Coastal Services Center indicate that the storm centers of at 

least 16 tropical cyclones with a Saffir-Simpson Hurricane Scale of Category 2 or higher 

have passed within 50 miles of the study area during the interval 1851 to 2008, and at 

least 52 such tropical cyclones have passed within 100 miles of the study area during the 

same interval. The most recent tropical cyclones to affect the study area were Hurricanes 

Katrina and Rita, which occurred in August 2005 and September 2005, respectively, and 

Hurricanes Gustav and Ike, which occurred in September 2008. 

Wetlands already weakened by extreme weather conditions may be more vulnerable to 

damage from subsequent storm events as plant communities become stressed beyond 

their ability to recover or shift toward communities with more tolerant species. 

Hurricanes impact coastal vegetation communities with saltwater intrusion and flooding 

from storm surges. Hurricanes also cause immediate physical damage to emergent 

wetlands as increased wave action and currents cause tearing or uprooting of the live mat 

and substrate loss, and high winds sheer limbs and fell trees in wooded areas. Storms 

deposit smothering mats of wrack (debris), and detritus over large areas, causing 

temporary or permanent shifts in plant community composition. The erosion and 

breaching of emergent lands also deteriorates its buffering function that protects lowenergy hydrologic regimes where aquatic vegetative communities may thrive. 

2.2.3.5 Herbivory

During the 1930s, nutria (Myocastor coypus) were accidentally released into the coastal 

wetlands. Since then, their population has rapidly expanded and their grazing and 

foraging for plant roots have been a major contributor to wetland losses. Although 

native, muskrat eat-outs may also result in significant local impacts to area marshes. 

Although eat-outs may recover under some conditions, tropical storm impacts on an eatout area may quickly convert such an area to permanent open water conditions (USGS, 

2000). 

2.2.3.6 Invasive Species

Invasive plant species increase and spread rapidly because the new habitat into which 

they are introduced is free of insects and disease that are natural controls in their native 

habitats. The aggressive spread of invasive species decreases stands of native plants in 

many areas, rapidly altering ecosystem function. Different ecosystem types vary in the 

species that pose problems and the degree to which they are currently impacted or 

threatened by invasive species (USGS, 2000). Disturbed ecosystems are more vulnerable 

to invasive species than stable ecosystems. Invasive aquatic species interfere with 

drainage and flood control, and impede navigation and recreation activities (Westbrooks, 

1998). 
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Restoration Plan 2-9 June 2012

2.2.3.7 Drought

Prolonged periods of drought can also impact coastal vegetation. In 2000, coinciding 

with the drought period, damage or dieback was reported in areas of unprecedented size 

in the Terrebonne and Barataria saline marshes. Areas sustaining the worst damage 

during this “brown marsh” phenomenon suffered complete dieback of above and 

belowground plant material and conversion to unvegetated mud flats (Linscombe et al., 

2001). In addition (Visser et al., 2002), in comparing 1997 and 2000 vegetation survey 

data, found that salinity increases across all marsh types occurred. The response of 

estuarine plant communities to the hydrologic changes brought about by the 1999 to 2000 

drought may provide a preview of changes in estuarine plant communities as global sealevel change causes marine intrusion into estuaries to increase (Visser et al., 2002). More 

recently, a severe nine-month drought following the 2005 Hurricanes Katrina and Rita 

allowed for prolonged inundation of gulf-strength surge waters and its deep infiltration 

into marsh soils. One year post-storm, soil salinity levels in many coastal areas remained 

significantly increased (Jerry Daigle, USDA NRCS; Steyer et al., in prep.).

2.2.3.8 Habitat Change

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 switching and loss of habitat. In some areas, loss of habitats with high friction 

factors, such as swamp forests, can lead to higher storm surge risk.

2.2.3.9 Lake Pontchartrain Dead Zone Expansion

Hypoxic/anoxic conditions (“dead zones”) have occurred in Lake Pontchartrain and the 

Gulf of Mexico in the past. 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. As a result of the 

MRGO closure structure and the Inner Harbor Navigation Canal (IHNC) Lake Borgne 

barrier structure, there are indications of a reduction of the hypoxic/anoxic zone in Lake 

Pontchartrain. Results of sampling conducted near the mouth of the IHNC in Lake 

Pontchartrain prior to and after the MRGO closure in summer 2009 indicate a substantial 

reduction in differences between surface and bottom salinity and dissolved oxygen (DO)

levels (Dr. Michael A. Poirrier, UNO). Low DO levels (<4.0 milligrams per liter [mg/l]) 

have not been observed in Lake Pontchartrain since the construction of the MRGO 

closure. 

2.2.3.10 Reduced Freshwater, Nutrient, Sediment Input

The construction of levees along the Mississippi River and its distributaries has virtually 

eliminated the periodic floods that provided vital freshwater, sediment and nutrients to 

the study area. These flood control measures have seriously altered hydrogeomorphic, 
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Restoration Plan 2-10 June 2012

biogeochemical, and ecological processes. Without inputs of freshwater, sediment, and 

nutrients, coastal land loss is accelerated and natural subsidence is exacerbated. 

2.2.3.11 Wetland Losses (Land Loss Rate)

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 to storm surge. Relative sea level rise (RSLR), tropical 

storms, shoreline erosion, modification of natural hydrology, and other factors contribute 

to land loss in the study area. The sustainability of the coastal ecosystems is threatened 

by the inability of many wetlands to maintain their surface elevation. Any alterations 

which allow marsh soils to be excessively saturated cause soil chemical changes that 

even the most resilient marsh plants cannot survive. Once plants die, roots no longer 

provide structure and integrity to marsh soils, and land loss results. 

2.2.3.12 Saltwater Intrusion (Salinity)

Saltwater intrusion changes the salinity gradient, which results in habitat changes. 

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 storm events can introduce saltwater 

into fresher areas, damaging large amounts of habitat in a short period. 

In addition to impacts on vegetation, increased salinity levels have negatively impacted 

the Louisiana oyster (Crassostrea virginica) fishery and its industry by shrinking the area 

within the seeding grounds that serve as ideal oyster habitat (Chatry et al., 1983). Chatry 

et al., (1983) developed an optimum salinity regime for oysters (table 1-5) by studying 

salinity, spatfall, and seed oyster production data from a 10-year time period. Meeting 

this established salinity regime at least 40 percent of the time was a goal of this study. 

For the purposes of this study, the results of the hydrology and hydraulics (H&H) model 

would be used to define discharge rates at the Violet, Louisiana Freshwater Diversion 

necessary to meet the salinity targets in the Biloxi Marsh/Lake Borgne regions. The 

results are expressed by a range with consideration of the model uncertainties. The 

model does not provide detail flow diagrams, residual velocity fields or detailed 

constituent gradient information. Details of the modeling are contained in the H&H 

model report that is included in appendix L. 

2.2.3.13 Shoreline Erosion (Land Loss Rate)

Tropical storm events and natural tidal processes are natural causes of erosion. 

Navigation channels subject inland areas to more dramatic tidal forces and wave action, 

thus increasing erosion. Rims of firmer soil around lakes, bays, and natural ridges along 
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Restoration Plan 2-11 June 2012

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.

2.2.3.14 Subsidence

The water control structures that allowed coastal areas to be developed also contribute to 

subsidence and wetland loss. Continued land loss and ecosystem degradation cause 

developed areas to become more susceptible to storm surge, thus threatening 

communities and valuable infrastructure. 

2.3 IDENTIFICATION OF MANAGEMENT MEASURES 

AND INITIAL SCREENING PROCESS

Several hundred conceptual features were initially considered. These features came from 

previous plans and reports, as well as the NEPA public scoping process. Section 2.6 of 

the feasibility report provides a list of conceptual features initially considered for 

inclusion in this study.

Ten types of management measures were identified to address the issues that were 

described in section 2.2.3 above and capitalize on ecological benefits. Management 

measures were considered by the Project Delivery Team (PDT) and the HET based upon 

the input received from the NEPA public scoping process, coordination with other 

resource management agencies, private, local governmental, or landowner groups, as well 

as information and scientific data from prior studies. Descriptions of the types of 

structural management measures are briefly described below and portrayed in figure 2-1. 

These structural management measures include: 

• Freshwater diversions 

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

• Marsh restoration, marsh nourishment, and swamp restoration 

• Shoreline protection 

• Ridge restoration 

• Restoration/creation of forested habitat 

• Barrier island restoration

• Submerged aquatic vegetation (SAV) restoration 

• Oyster reef restoration 

• Vegetative planting

In addition to the structural measures identified, nonstructural measures considered

include invasive species control; herbivory control; and buy-outs of developed areas for 

ecosystem restoration purposes. Invasive species and herbivory control measures would 

be considered further as management measures necessary to sustain structural measures. 

Buy-outs of developed areas were not deemed necessary for the MRGO ecosystem 
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restoration plan because of the large extent of non-developed areas available for 

restoration purposes located within the Lower Pontchartrain sub-basin. 

Figure 2-1: Initial Restoration Measures Considered

2.3.1 Description of Measures by Type

Below are descriptions of the types of management measures considered. Within each of 

these management measures, multiple specific measures (taking into account specific 

locations, quantities, size, etc.) were developed and screened. 

2.3.1.1 Freshwater Diversion

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 Pontchartrain basin 

would 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 from diversions can increase over time 
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Restoration Plan 2-13 June 2012

and continue as long as the diversion is adaptively operated and maintained to respond to 

environmental conditions. 

2.3.1.2 Hydrologic Restoration

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 in the Louisiana portion of the study area were 

considered for backfilling, plugging, installing water control structures (such as weirs and 

sills), or bank gapping. Backfilling measures serve the dual purpose of controlling water 

flow and building land (depending upon the depth of fill). Measures to plug the channels 

or canals can be accomplished with lateral fill or full closure structures that would aid in 

salinity control, restore the natural hydrology, increase sedimentation and eventually 

build marsh. Measures such as weirs and sills provide partial closure and aid in 

sedimentation and salinity control. Bank gapping measures allow water to flow freely 

and restore natural hydrology, provide valuable nutrients and sediment facilitating 

organic deposition, improve biological productivity, and inhibit further habitat 

deterioration. 

2.3.1.3 Marsh Restoration and Marsh Nourishment

Land loss from 1985 through 2010 in the study area is estimated to be approximately 

63,178 acres. Approximately 131,091 acres is projected to be lost between 2010 and 

2065 (Wetland Value Assessment in appendix M). 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 dredge material for 

marsh building to restore lost marsh or nourishment of existing marsh. Marsh restoration 

involves the placement of dredge material in shallow open water areas and extensively 

broken marsh to raise the area to marsh elevation. Following compaction and 

dewatering, the area would be planted with marsh vegetation according to the salinity 

gradient. Retention dikes, deflection dikes, and/or closures may be used to contain 

material within the restoration area. During marsh restoration, dredged material would be 

allowed to overflow into existing marsh within the restoration area to sustain the marsh. 

Marsh nourishment refers to the placement of a thin layer of dredged material on 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 would 

add new sediment and nutrients to the system; combat subsidence; reduce breaching and 

erosion; reduce wave fetch; and allow for increased vertical accumulation of vegetation. 
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Restoration Plan 2-14 June 2012

2.3.1.4 Swamp Restoration and 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. To restore habitats affected by the MRGO, 

measures for cypress swamp restoration and nourishment were developed. Restoration of 

swamp habitat would be accomplished in the same manner as the marsh restoration 

described previously, however, it would be restored to a higher dewatered and settled 

elevation than marsh restoration features to support cypress habitat.

Swamp nourishment is proposed for existing swamp habitat that are currently at marsh 

elevation, and consists of placing a thin layer of dredge material to nourish the area, raise 

elevation, and encourage the recruitment of cypress-tupelo community species. In the 

areas of swamp nourishment, the elevations would be raised to a level conducive to 

cypress-tupleo growth, and these species would simply be allowed to volunteer due to the 

presence of suitable habitat, no plantings would occur in the nourishment areas. 

2.3.1.5 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. 

Shoreline protection is considered critical for the prevention of shoreline erosion and 

addressing the larger problem of land loss by dissipating wave energy. High waters, 

wave action, wind induced currents, tidal flow, channel bathymetry, and residual tidal 

circulation contributes to shoreline erosion. 

Shoreline protection includes the placement of materials, such as sand, shell, rock, or 

construction debris on-shore or off-shore. Potential construction methods include the 

establishment of artificial reefs, such as oyster reefs, and breakwaters off-shore as well as 

the placement of rock or sand on-shore. Protection measures are generally placed parallel 

to the shoreline and are designed to harden the shoreline and dampen wave energy. 

2.3.1.6 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, 

natural ridges formed as smaller distributaries diverged from larger distributaries as they 

flowed toward the coast. Bayou La Loutre and Terre aux Boeufs are natural ridges 

remaining in the study area that have degraded over time due to both natural and human 

induced events. The breach in the Bayou La Loutre Ridge resulting from the 

construction of the MRGO was recently restored by the construction of a rock barrier. 

Additional restoration measures proposed for ridges include the placement of dredge 

material to reestablish historical ridge heights to sustaining ridge habitat. Ridge 

restoration measures include a planting plan. 
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2.3.1.7 Restoration/Creation 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 on the confined disposal sites along the MRGO or in combination 

with other measures such as swamp restoration were considered. Forested habitat is an 

important resource and unique habitat in the study area and provide important habitat for 

resident and migratory birds. Forested habitat has a higher friction factor providing 

increased protection to developed inland areas by reducing storm surge risk. Forested 

habitat historically existed in the study area but has declined over time due to tropical 

storms, salinity intrusion and development. During public scoping meetings, measures to 

restore or create forest habitat were suggested.

2.3.1.8 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 proposed as a measure to reduce storm surge and provide critical habitat 

for threatened piping plovers, migratory waterfowl, and other aquatic and wildlife 

species. Through Louisiana Coastal Protection and Restoration (LACPR) and 

Mississippi Coastal Improvements Program (MsCIP), the contribution of surge reduction 

provided by the barrier islands, in their historic, existing, and altered states, has been 

subject to sensitivity analyses that 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 and changes in circulation patterns along the coasts 

of Mississippi and Louisiana. 

2.3.1.9 Submerged Aquatic Vegetation (SAV) Restoration

Submerged Aquatic Vegetation (SAV) restoration could address the habitat changes and 

loss problem in the study area. SAV beds provide ecosystem function benefits such as 

important habitat for critical fisheries and improved water quality. 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). 

During public scoping meetings, the re-establishment of SAV in the Mississippi Sound 

and Lake Pontchartrain were recommended. The sustainability of SAV is uncertain; 

therefore, pilot projects are recommended to determine the potential for re-establishing 

SAV beds in the Pontchartrain basin. 
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Restoration Plan 2-16 June 2012

2.3.1.10 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. 

During the NEPA scoping meetings, it was suggested that artificial oyster reefs should be 

established in the Biloxi Marshes. Artificial oyster reefs were considered for oyster 

production and shoreline protection. Three alternative designs for artificial 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. Artificial oyster reefs as shoreline protection offers an 

opportunity to incorporate shoreline protection benefits as well as benefits for oysters. 

2.3.1.11 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 native species in areas that already have the necessary elevation to maintain a 

particular habitat to 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. 

2.3.2 Initial Formulation and Screening Process

The screening of specific measures within each type of management measure was an 

iterative process consisting of multiple steps to arrive at a suite of measures to formulate 

alternative plans. The initial formulation and screening process involved comparing 

measures to the study purpose and need, goals, and objectives as described below: 

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. 
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Restoration Plan 2-17 June 2012

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. Section 2.6.1 of 

the feasibility report further details the initial formulation and screening process for the 

individual measures. Appendix O contains screening tables with individual measures. 

2.3.2.1 Freshwater Diversion / Initial Screening Process

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. 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. Freshwater 

diversion measures were initially screened from further consideration based upon two 

criteria established by the planning team. Diversion measures and sites determined to 

have an influence area lying entirely outside the Lake Borgne ecosystem or outside of the 

areas potentially affected by the MRGO 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 (table 2-2). 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.

 

Table 2-2: 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

Bayou Lamoque Diversion R1, R2, 

R3, R4, and R5 No No

White Ditch Diversion R3 and R5 No No
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-18 June 2012

Table 2-2: Steps 3 and 4: Freshwater Diversion Measures

Measure Name

Addresses 

Restoration of 

Lake Borgne 

Ecosystem

Addresses a 

MRGO 

Ecosystem 

Effect Other Criteria

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 indicates the 

desire of Congress to achieve the benefits 

of this diversion at another location. 

Acceptability is a concern due to 

opposition to a large diversion of 

freshwater into Lake Pontchartrain.

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.

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.
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-19 June 2012

Table 2-2: Steps 3 and 4: Freshwater Diversion Measures

Measure Name

Addresses 

Restoration of 

Lake Borgne 

Ecosystem

Addresses a 

MRGO 

Ecosystem 

Effect Other Criteria

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.

The team determined that feasibility studies and engineering and design efforts are 

currently underway in the LCA and CWPPRA programs for freshwater diversions to 

address the Upper Pontchartrain Basin/Lake Maurepas swamps portion of the study area. 

Therefore, new river diversions or modifications to existing structures in that vicinity 

were removed from further consideration. The application of this criterion reduced the 

number of potential sites to eight locations between the Bonnet Carrè Spillway and the 

existing Caernarvon Freshwater Diversion. 

The location of a freshwater diversion is constrained by existing development, 

infrastructure, and river conditions. 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 Feasibility Study 

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 Carré 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. This reduced the 

number of potential freshwater diversion sites to six. 

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. 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-20 June 2012

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 (figure 2-2). 

Figure 2-2: Freshwater Diversion Location Constraints

South of Poydras, there are opportunities to divert river water in the vicinity of Bayou 

Terre aux Bouefs and at the existing Caernarvon Diversion. The Bayou Terre aux Bouefs 

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 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, 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-21 June 2012

constructability, and potential impacts to development, diversion alternatives at Bayou 

Terre aux Bouefs 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 Bouefs Ridge and the MRGO spoil 

bank. This assessment reduced the number of potential diversion sites to four locations in 

the vicinity of Violet, Louisiana 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, Louisiana 

was determined to be the most effective way to restore the Central Wetlands and the 

salinity regime in the estuary. 

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 selfsustainability 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; 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-22 June 2012

• Enhance the resilience and self-sustainability of the estuary; 

• 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. 

2.3.2.2 Hydrologic Restoration Initial Screening Results

Channel/Canal Filling

Initially, 24 channel/canal backfilling measures were considered. After screening, 6 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 

6 backfilling features were located within the footprint of the former navigation channel. 

See table 2-3. 

Water Control Measures

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 stand-alone measures. See table 2-3. 

Table 2-3: 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

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
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-23 June 2012

Table 2-3: 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 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.

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.
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-24 June 2012

Table 2-3: Steps 3 and 4: Hydrologic Restoration Measures

Measure Name

Addresses 

Restoration 

of Lake 

Borgne 

Ecosystem

Addresses a 

MRGO 

Ecosystem 

Effect Other Criteria

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.

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 La Loutre 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 La Loutre) Yes Yes

NOTE: Bold text indicates the measure was carried forward for further consideration.

2.3.2.3 Marsh and Swamp Restoration Initial Screening Results

Initially, approximately 42 marsh restoration and five swamp restoration areas were 

identified in Louisiana. For discussion of potential marsh restoration/creation 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. 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 (table 2-4). 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-25 June 2012

Table 2-4: 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

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.
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-26 June 2012

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

Measure Name

Addresses 

Restoration 

of Lake 

Borgne 

Ecosystem

Addresses 

a MRGO 

Ecosystem

Effect Other Criteria

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 Marsh’ 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 oyster 

reefs and seed grounds. Marsh Creation near St. Helena Bay Yes Yes

Marsh Creation West of Lake Jean Louis Robin Yes Yes

Marsh Creation West of Lake Calebass Yes Yes

NOTE: Bold text indicates the measure was carried forward for further consideration.

2.3.2.4 Shoreline Protection 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 (table 2-5). 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-27 June 2012

Table 2-5: 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.

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
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-28 June 2012

Table 2-5: 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 - 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

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.

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)
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-29 June 2012

Table 2-5: Steps 3 and 4: Shoreline Protection Measures

Measure Name

Addresses 

Restoration 

of Lake 

Borgne 

Ecosystem

Addresses 

a MRGO 

Ecosystem 

Effect Other Criteria

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.

2.3.2.5 Ridge Restoration Initial Screening Results

Initially, 55 ridge restoration measures were considered. The 55 measures were 

developed by combining five different sized ridges (historic, 50-foot, 100-foot, 150-foot, 

and 200-foot footprints) at 11 locations. After screening, only two ridge restoration 

locations on the Bayou La Loutre Ridge were carried forward for further study (table 2-

6). 

Table 2-6: 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 

200 ft.

Yes Yes

Bayou La Loutre Ridge Restoration 

East - South Bank A 50 ft. Yes Yes Crown width and slope not suitable for establishing oak ridge species.

Bayou La Loutre Ridge Restoration 

East - South Bank A 100 ft. Yes Yes Crown width and slope not suitable for establishing oak ridge species.

Bayou La Loutre Ridge Restoration 

East - South Bank A 150 ft. Yes Yes Crown width and slope not suitable for establishing oak ridge species.
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FEIS MRGO Ecosystem

Restoration Plan 2-30 June 2012

Table 2-6: 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 historic width Yes Yes Removed due to potential negative impacts to existing vegetation and marsh.

Bayou La Loutre Ridge Restoration 

East - South Bank B 50 ft., 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: 50 ft., 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 B: 50 ft., 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 

West - North Bank A: 50 ft., 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 

West - South Bank A: 50 ft., 100 ft., 

150 ft., 200 ft., and historic width

Yes Yes Removed due to potential negative impacts to 

existing vegetation and marsh.

Bayou Terre aux Boeufs West Ridge 

Restoration A: 50 ft., 100 ft., 150 ft., 

200 ft., and historic width

Yes Yes Removed due to potential negative impacts to 

existing vegetation and marsh.

Bayou Terre aux Boeufs West Ridge 

Restoration B: 50 ft., 100 ft., 150 ft., 

200 ft., and historic width 

Maybe Maybe Removed due to potential negative impacts to 

existing vegetation and marsh.

Bayou Terre aux Boeufs West Ridge 

Restoration C: 50 ft., 100 ft., 150 ft., 

200 ft., and historic width

Maybe Maybe Removed due to potential negative impacts to 

existing vegetation and marsh.

Bayou Terre aux Boeufs East Ridge 

Restoration A: 50 ft., 100 ft., 150 ft., 

200 ft., and historic width

Maybe Maybe Removed due to potential negative impacts to 

existing vegetation and marsh.

Bayou Terre aux Boeufs East Ridge 

Restoration B: 50 ft., 100 ft., 150 ft., 

200 ft., 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.

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. 

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 
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FEIS MRGO Ecosystem

Restoration Plan 2-31 June 2012

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 for these areas that 

minimized impacts to adjacent wetlands while providing suitable crown widths and 

slopes for establishing of oak ridge species. 

2.3.2.6 Vegetative Planting Initial Screening Results 

Initially, 11 standalone vegetative planting measures were considered, which involved 

planting trees on the banks of the MRGO navigation channel. All of these measures were 

screened out. 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

(table 2-7). 

Additional vegetative planting measures are being carried forward as integral components 

of other measures such as marsh, swamp, and ridge restoration. 

Table 2-7: 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 

more desirable tree species.

Plant Trees on Spoil Bank - C Yes Yes

Plant Trees on Spoil Bank - D Yes Yes

Plant Trees on Spoil Bank - E Yes Yes

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.
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2.3.2.7 Barrier Island Restoration 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. 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 1800’s 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 (table 2-8). 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. 

Table 2-8: 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"

2.3.2.8 SAV Demonstration Project 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 south shore of Lake 

Pontchartrain. The Mississippi SAV project was screened out because it has already been 

recommended by the MsCIP report (table 2-9). 

Table 2-9: Steps 3 and 4: SAV Measures
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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.

2.3.2.9 Artificial Oyster Reef Initial Screening Results

Initially, one artificial oyster reef measure was considered (table 2-10). 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.

Table 2-10: 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.

2.3.3 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, Wetland Value Assessment methodology. 

2.3.4 Measures Requiring Additional Study

2.3.4.1 Recommendations for Additonal Studies

Restoring historic salinity conditions and providing freshwater and nutrients to nourish 

existing and restored wetlands in the study area is an important component of the plan. 

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 related to 
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FEIS MRGO Ecosystem

Restoration Plan 2-34 June 2012

a Freshwater Diversion. Therefore, the final recommendations for the MRGO Ecosystem 

Restoration Plan include additional analysis, design and implementation of a Freshwater 

Diversion at or near Violet as authorized by WRDA 2007 Section 3083. 

2.3.4.2 Barrier Island Restoration

The former MRGO navigation channel was dredged through an existing tidal inlet 

between Grand Gosier Island and Breton Island to allow ships from the Gulf of Mexico 

to enter Breton Sound and onward to the Port of New Orleans. Construction and 

maintenance of the channel is believed to have interrupted sediment transport in the 

lower Chandeleur Islands limiting long-shore movement of sand from Grand Gosier 

Island to Breton Island. Dredged material from the MRGO was beneficially deposited on 

and near Breton Island between 1993 and 2005 during channel maintenance events to 

restore island habitat. 

The MRGO Ecosystem Restoration Plan Feasibility Study – Chandeleur and Breton 

Islands, May 2010 (SBEACH Model Report) found in appendix J evaluated measures to 

improve and increase barrier island habitat on the Chandeleur Island Chain. Further 

study of alternative barrier island restoration techniques should be conducted to protect 

and restore this significant coastal habitat. 

The type of benefits provided by reconstructing either the Chandeleur Islands or Breton 

Island alternatives can be considered identical as they provide similar habitat (supratidal, 

gulf intertidal, bay intertidal, and subtidal) along barrier island shorelines that are 

geographically close. Table 2-11 summarizes the benefits and cost of the various barrier 

island restoration alternatives.

Table 2-11: Summary of Barrier Island Restoration Alternative Benefits and 

Costs

Alternative Fill Volume (cy)

Cost 

Estimate

Net Benefits 

(AAHUs)

Cost per AAHU 

($/AAHU)

Chandeleur Island 8,720,000 $119,568,000 1,464 $81,672

Breton Island Alt. 1 20,040,000 $178,486,000 195 $915,313

Breton Island Alt. 2 9,657,000 $88,450,000 49 $1,807,435

Breton Island Alt. 3 7,255,000 $61,038,000 67 $908,645

Breton Island Alt. 4 9,382,000 $100,279,000 70 $1,428,307

Breton Island Alt. 5 12,321,000 $83,631,000 0 -

AAHU = Average Annual Habitat Unit

2.3.4.3 Sediment Study

Due to uncertainties associated with sustaining Louisiana’s coast through sediment 

placement, a sediment-needs budget and sources inventory should be developed. Further 

study of sediment loads in the lower Mississippi River is needed due to variation between 

sampling frequency and methods at various sites. The LCA Mississippi River 

Hydrodynamic Study is anticipated to increase available data and understanding about the 

sediment loads in the river. A comprehensive inventory of available borrow sources, 
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FEIS MRGO Ecosystem

Restoration Plan 2-35 June 2012

their volumes, and any constraints associated with their use would facilitate the 

identification of available sediment for projects throughout the area.

2.3.4.4 Fisheries Modeling Study

A Comprehensive Aquatic Systems Model (CASM) modeling study (appendix I) was 

undertaken to evaluate the potential ecological and food web implications of diverting 

Mississippi River water across the Central Wetlands area into Lake Borgne and aquatic 

systems associated the MRGO. The CASM is a bioenergetics-based ecosystem model 

that simulates the daily production dynamics of modeled populations of aquatic plants 

and animals. The principal modeling objective was to assess the potential effects of 

alterations in salinity and other water quality parameters that would result from the 

proposed Violet, Louisiana Freshwater Diversion on selected populations of valued 

ecological resources in the MRGO ecosystem. The CASM was run on the diversion flow 

regime which was a component of all the action alternatives and therefore, did not 

influence the selection of the tentatively selected plan. 

The CASM MRGO modeling study focused on key species of ecological, recreational, 

and commercial value including oysters, brown shrimp, white shrimp, blue crab, red 

drum, spotted sea trout, striped mullet, Gulf menhaden, bay anchovy, sheepshead, and 

Atlantic croaker. Gulf sturgeon was additionally included because of its endangered 

species status. To address different habitat requirements (e.g., salinity, depth,) juvenile 

(or immature) and adult stages were modeled as separate populations for oysters (i.e., 

spat), blue crab, brown shrimp, white shrimp, red drum, and spotted sea trout. The CASM 

MRGO also included zooplankton and zoobenthos as separate generalized consumer 

populations because of their importance as food resources in the model food web. 

Broadly defined populations of phytoplankton and periphyton (i.e., diatoms, green algae, 

bluegreen algae) were modeled as key primary producers in the CASM MRGO. The 

modeled food web also included four representative submerged aquatic plants. The 

resulting composition of primary producers and consumers defines a food web structure 

relevant to the MRGO ecosystem. 

The CASM MRGO simulates the daily biomass of the modeled populations for 55-years 

for 23 selected inshore and offshore locations in the MRGO ecosystem. The CASM 

model domain includes approximately the southern half of Lake Pontchartrain, Lake 

Borgne, the Biloxi Marsh and extends eastward past Bay St. Louis and Biloxi, MS, and 

southwards past the Chandeleur Islands into the Gulf of Mexico. The 23 locations 

represent a subset of the larger domain defined by the University of New Orleans (UNO) 

H&H model. The UNO model was developed to characterize changes in salinity 

throughout this lager region projected for several MRGO future without-project and withproject conditions (i.e., freshwater diversions). 

Despite the assumptions and limitations inherent in developing a complex aquatic 

systems model for MRGO ecosystem, the resulting CASM application appears as a 

useful approach for assessing the ecological impacts of freshwater diversions. The 

combination of environmental input data, food web structure, and literature-based 
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Restoration Plan 2-36 June 2012

bioenergetics parameters proved capable of usefully describing production dynamics of 

the selected aquatic populations of producers and consumers. 

The CASM MRGO has been used to assess the outcomes of proposed without- and withproject alternatives in relation to ecosystem restoration actions proposed near Violet, 

Louisiana. The incremental effects have been calculated in evaluating the proposed 

freshwater diversion. The preliminary results of the CASM study are addressed in 

chapter 4. Section 2.12.6 describes the additional CASM modeling work recommended 

for the project. 

2.3.4.5 Recreation Components

Public comments have indicated that recreational improvements should be considered as 

a part of this plan. Real estate issues and the need for a local sponsor responsible for a 

part of the construction costs (50 percent) and maintenance and operation (100 percent) 

prevent full development of recreational features for inclusion in this plan. However, it is 

the recommendation of this study that recreation features be considered in the design and 

implementation phase of the plan. Three sites were identified as potential locations for 

recreational improvements associated with the restoration features for the tentatively 

selected plan (alternative C) (appendix W).

2.3.5 Measures Considered But Eliminated

Measures that were eliminated because they were considered the least cost effective 

include: 

• Marsh restoration and shoreline protection on the bayside of Biloxi marshes north 

of Morgan Harbor 

• Filling in the MRGO 

• Large ridge restoration measure

• Florissant marsh restoration

2.4 ALTERNATIVE PLAN FORMULATION

Alternatives were formulated to maximize environmental benefits, avoid and minimize 

environmental impacts, and minimize the cost associated with the disposition of the deauthorized project. Plans were formulated in consideration of four criteria: 

completeness, effectiveness, efficiency, and acceptability. Alternative plans are 

combinations of the management measures that were carried forward after screening as 

described in section 2.3. Alternative plans and their component management measures 

were assessed relative to the objective of the NER. 

The study utilized a geographic information system (GIS) database to catalogue study 

information including individual management measures, existing and authorized water 

projects, and existing conditions. The GIS enabled the team to visually display and 
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FEIS MRGO Ecosystem

Restoration Plan 2-37 June 2012

manipulate information across the large study area. Additionally, the system allowed the 

team to build and test various alternative combinations of management measures during 

the course of plan formulation. Thus, the GIS is utilized as a decision support tool. 

2.4.1 Preliminary Evaluation of Measures

The measures that passed through initial screening were compared against one another 

and assembled into alternative plans using performance outputs (benefits) and costs. 

2.4.1.1 Outputs (Benefits) 

Environmental outputs were measured using the Sediment and Nutrient Diversion Model 

(SAND2) and the Wetland Value Assessment (WVA) methodology. The SAND2 

utilized outputs from the hydrologic model to determine the ecological benefits from the 

freshwater diversion. The outputs from the SAND2 were utilized to conduct the wetland 

value assessments. 

The WVA methodology is similar to the Department of the Interior - U.S. Fish and 

Wildlife Service’s (USFWS’s) habitat evaluation program (HEP), in that habitat quality 

and quantity are measured for baseline conditions and predicted for FWOP and future 

with project (FWP) conditions. Separate habitat assessment models were used, including 

the Barrier Island, the Bayou La Loutre Ridge, the Fresh/Intermediate Marsh, the 

Brackish Marsh, and the Saline Marsh Community Models. Instead of the species-based 

approach of HEP, each model utilizes an assemblage of variables considered important to 

the suitability of a given habitat type for supporting a diversity of fish and wildlife 

species. As with HEP, these models allow a numeric comparison of each future 

condition and provide a combined quantitative and qualitative estimate of project-related 

impacts to fish and wildlife resources.

The WVA models operate under the assumption that optimal conditions for fish and 

wildlife habitat within a given coastal wetland type can be characterized, and that existing 

or predicted conditions can be compared to that optimum to provide an index of habitat 

quality. Habitat quality is estimated and expressed through the use of a mathematical 

model developed specifically for each habitat type. Each model consists of: 1) a list of 

variables that are considered important in characterizing fish and wildlife habitat; 2) a 

Suitability Index graph for each variable, which defines the assumed relationship between 

habitat quality (Suitability Indices) and different variable values; and 3) a mathematical 

formula that combines the Suitability Indices for each variable into a single value for 

wetland habitat quality, termed the Habitat Suitability Index (HSI).

The WVA models assess the suitability of each habitat type for providing resting, 

foraging, breeding, and nursery habitat to a diverse assemblage of fish and wildlife 

species. This standardized, multi-species, habitat-based methodology facilitates the 

assessment of project-induced impacts on fish and wildlife resources. The 

fresh/intermediate, brackish, and saline marsh WVA model consists of six variables: 1) 

percent of wetland covered by emergent vegetation; 2) percent open water dominated by 
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FEIS MRGO Ecosystem

Restoration Plan 2-38 June 2012

submerged aquatic vegetation; 3) degree of marsh edge and interspersion; 4) percent of 

open water less than or equal to 1.5 feet deep; 5) salinity; and 6) aquatic organism access. 

The swamp model consists of six variables: 1) stand structure, 2) stand maturity, 3) 

hydrology, 4) size of contiguous forested area, 5) suitability and traversability of 

surrounding land use, and 6) disturbance. The ridge model consists of three variables: 1) 

percent canopy cover, 2) percent midstory cover, and 3) woody species diversity. The 

barrier island WVA model consists of seven variables: 1) percent of the total subaerial 

area that is classified as dune habitat; 2) percent of the total subaerial area that is 

classified as supratidal habitat; 3) percent of the total subaerial area that is classified as 

intertidal; 4) percent vegetative cover of dune, supratidal, and intertidal habitats; 5) 

percent vegetative cover by woody species; 6) degree of marsh edge and interspersion; 

and 7) beach/surf zone features. 

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 AAHUs, were 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 

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, the USACE’s Institute for 

Water Resources (IWR) windows-based decision support software 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.

The HET agreed that use of the WVA methodology would be most appropriate 

considering the tight feasibility report schedule. The models and methods utilized to 

determine future acreages are presented below and in more detail in appendix M. 

The sections below provide descriptions of the results of the SAND2 and WVA for the 

FWOP and various wetland restoration measures. 

FWOP Wetland Acreage Projections

Wetland acreage data (1985 through 2006) was obtained from the USGS for each of the 

study area planning subunits. FWOP subunit wetland acreages were determined via a 

linear trendline through those data (figure 2-3). Where applicable, annual net acreage 
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Restoration Plan 2-39 June 2012

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. 

Figure 2-3: Actual and Predicted Acreage for Subunit 17

Predicting Wetland Benefits of Mississippi River Diversions - General

An assessment of wetland benefits associated with proposed Mississippi River diversion 

measures was undertaken. The SAND2 model was used. This model is an ERDC 

revision of the SAND1 (Boustany-ERDC spreadsheet model) used in the LACPR Final 

Technical Report. The SAND2 version differs from the SAND1 model by incorporating 

an improved method for determined nutrient benefits, and it includes the ability to 

capture diversion synergies with proposed marsh restoration measures constructed within 

the diversion benefit area. 

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 

period of analysis, there is considerable uncertainty regarding the accuracy of the 

predicted river diversion benefits. However, the SAND2 models do provide an objective 

means for comparing alternative measures and plans. 

Although the period of analysis is 50 years, all environmental assessments were 

conducted for a 100-year period to assess the wetland acreage trajectories at and beyond 

the period of analysis. 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 

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
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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) 

= wetland acres created/supported via introduced nitrogen. Inputs required for estimating 

the nutrient benefits are: 

1. Mississippi River Discharge 

All diversion benefit assessments utilized 25 years of Tarbert’s Landing discharge 

data (1983-2007) repeated 4 times to create a 100-year input. 

2. Diversion Discharge 

The Violet, Louisiana Freshwater Diversion was assumed to operate year-round at 

1,000 cubic feet per second (cfs), except during the months of April and May, when 

it would operate at 7,000 cfs. 

 

3. Nutrient Concentrations 

Monthly USGS Belle Chase nitrogen concentration data (1976 through 2007) are 

used to calculate nitrogen additions to diversion receiving areas. 

4. Plant Productivity Rate 

Monthly above-ground emergent vegetation productivity values, by marsh type, are 

selectable with the model. Productivity values according to the FWOP marsh type 

were chosen.

5. Emergent Vegetation Percent Nitrogen

Percent nitrogen of emergent vegetation biomass (Chabreck, 1972) is incorporated 

into the model, and selectable by habitat type. Percent nitrogen based on FWOP 

habitat type was used. 

6. Denitrification Rate

A literature reported value of 21g/m2

/yr was used (Delaune and Jugsujinda, 2003; 

Bond, 2006; and Day et al., 2004). Denitrification was assumed to reduce the 

amount of introduced nitrogen available for uptake by emergent wetland 

vegetation. 

Land building benefits under the SAND2 model were estimated utilizing a Belle Chase 

sediment rating curve, together with the assumed diversion discharge, to compute the 

volume of introduced sediment. The model’s sediment retention module then applied all 

or a portion of the introduced suspended sediment toward accretion of new wetland acres. 

The sediment retention module uses the size and dimensions of the receiving area, and 

diversion discharge, to calculate velocities within the receiving area. Whenever receiving 

area velocities drop below the thresholds required keeping any one of the three sediment 

types (fine sand, silts, and clay) in suspension, the model calculates deposition of that 

sediment type. However, land building is not solely based on the accretion of introduced 

mineral sediments. The model automatically includes sufficient organic material to 

achieve the average surface soil bulk density of the selected habitat type (which was 

always selected as that of the FWOP condition). In addition to using the surface soil bulk 
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density by habitat type, the model also uses depth of fill, and bulk density compaction 

with depth change rate to calculate a depth-averaged soil bulk density 

The previously defined study area subunits were utilized as the diversion receiving areas. 

Required inputs to calculate acres of diversion-related land-building include; width, 

acreage, and average water depth, and roughness height of bottom sediments. 

1. Mississippi River Sediment Concentrations 

A sediment rating curve using (1991-2004) surface suspended sediment 

concentration values at Belle Chase relative to Tarbert’s Landing discharges 

(Snedden et al., 2007) was incorporated into the model to calculate suspended 

sediment concentrations at a given river discharge. Belle Chase sediment size 

fractions were also used (fine sand, silt, clay). Percent flocs (larger and heavier 

sediment particles) were estimated based on the FWOP salinity regime. Higher 

percent flocs are assumed in higher salinity receiving areas, and lower percent flocs 

are assumed in lower salinity receiving areas.

2. Diversion Discharge 

The Violet, Louisiana Freshwater Diversion was assumed to operate year-round at 

1,000 cfs, except during the months of April and May, when it would operate at 

7,000 cfs. 

3. Receiving Area length

Using ArcMap, the receiving area length was measured as the length of the primary 

diversion flow pathway through the receiving area. 

4. Receiving Area Width 

This was calculated by dividing the receiving area length into area of the receiving 

area (i.e., subunit area). 

5. Average Depth 

This was obtained through any available data source. If no data source was 

available, average depth was estimated based on field observations and professional 

judgment. 

6. Roughness Height of Water Bottoms 

Based on Smith, 2007 and Soulsby, 1983, a roughness height for mud of 0.0006562 

feet was used for all model runs. 

 

7. Wetland Soil Bulk Density 

Based on values reported in the published literature, average surface bulk density 

values are selectable within the model. Surface bulk density values were selected 

according to the FWOP habitat type. The model computes a depth-averaged bulk 

density using surface bulk density, depth of fill, and bulk density change with depth 

inputs. 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-42 June 2012

8. Maximum Tidal Velocity

Maximum tidal velocities are required in the model’s sediment retention module. 

Lacking velocity data for all evaluated diversion receiving areas, velocities were

estimated to be 1.5 feet per second (fps) in receiving areas close to the Gulf of 

Mexico, and 1.0 fps in middle and upper basin diversion receiving areas.

The application of the SAND2 model to the Violet, Louisiana Freshwater Diversion was 

atypical because sediment and nutrient retention and losses within the immediate Central 

Wetlands receiving area, the deep MRGO, and Lake Borgne, would reduce diversion 

benefits to the more distant influence areas such as the Inner Biloxi marshes and the East 

Orleans Landbridge. Consequently, benefits were determined separately for the Central 

Wetlands, South Lake Borgne marshes, Inner Biloxi Marshes, and East Orleans 

Landbridge study area subunits. To assist in this effort, UNO scientists utilized a simple 

hydrologic model to provide estimates of diverted water, nutrients, and sediments that 

would be delivered to and retained within each of the receiving areas at the 1,000 cfs and 

7,000 cfs diversion discharges. The reported water, nitrogen, and sediment distribution 

values used in the SAND2 model were derived with the inclusion of a proposed closure 

across the Lake Borgne shoreline opening to the MRGO, across the MRGO from Bayou 

Dupre. Additionally, UNO’s work indicated that all sands would be deposited within the 

Central Wetlands, and that only fine sediments would travel further. Therefore, sand 

retention values were manually set to 0.0 in all receiving areas, except for the Central 

Wetlands model run. 

Use of the SAND2 model also required input of FWOP and FWP wetland loss rates, plus 

initial marsh and water acreages of the receiving area. FWOP TY0 (Target Year 0)

acreages (year 2014) were determined via application of a linear trend-line as described 

above. The SAND2 model was developed to allow input of up to three different FWOP 

and three FWP loss rates. Because CWPPRA projects have a 20-year project life, 

implementation of CWPPRA projects may cause FWOP subunit loss rates to change 

several times. If several CWPPRA projects occur within a subunit, they may result in 

more than three FWOP loss rate changes over the 100-year SAND2 analysis period. In 

such cases, a weighted average was utilized to combine two similar loss rate periods. In 

many cases, FWP marsh restoration and marsh nourishment measures also resulted in 

more than three loss rate changes. In such cases, a weighted average was utilized to 

combine two similar loss rate periods. 

Predicting Wetland Benefits of the Mississippi River Diversion at Violet

The evaluated Violet, Louisiana Freshwater Diversion was assumed to operate yearround at 1,000 cfs, except during the months of April and May, when it would operate at 

7,000 cfs. During the 7,000 cfs pulsing flow, it was determined that the Central Wetlands 

would only receive 1,000 cfs and the remaining 6,000 cfs would flow directly toward the 

MRGO and into Lake Borgne. The UNO report determined that the maximum sediment 

deposition (at 1,000 cfs) was 30 percent of the total introduced sediment and the 

maximum nitrogen uptake was 50 percent of the total introduced nitrogen. Therefore, 

input nutrient load in the SAND2 model run for the Central Wetlands was reduced by 50 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-43 June 2012

percent and sediment retention within the area was manually set to 30 percent of the total 

introduced suspended sediment load. 

According to the UNO report, the South Lake Borgne marshes would receive a maximum 

61 percent of the total river water inputs, a maximum 50.6 percent of the suspended 

sediment, and a maximum 46.4 percent of the introduced nitrogen. Therefore, the 

SAND2 model diversion inputs to this area were reduced to 61 percent of the total. 

Because the percent suspended sediment input was less than the percent water input, the 

sediment input was manually reduced to 83 percent of introduced water’s sediment load 

(50.6 of the total sediment/61 of the total diversion discharge = 83 percent) Similarly, 

the nitrogen load was reduced to 76 percent (46.4 percent total nitrogen delivered/61 

percent of the total water delivered).

The East Orleans Landbridge marshes were estimated to receive a maximum of 9 percent 

of the total diverted discharge, a maximum of 7.5 percent of the total nitrogen, and a 

maximum of 8.1 percent of the total suspended sediment load. For this area, the SAND2 

model nitrogen input was reduced to 83.3 percent (7.5 percent of the total nitrogen/9 

percent of the total diversion input), and the suspended sediment input was reduced to 90 

percent (8.1 percent of the sediment/9 percent of the introduced water). 

Although the UNO report indicated that the Inner Biloxi marshes would receive 34 

percent of the total diversion flows, that estimate was reduced to 30 percent since 70 

percent of the diversion flows were designated as going elsewhere (61 percent to the 

South Lake Borgne + Golden Triangle, and 9 percent to the East Orleans Landbridge). 

Because the UNO report indicated that the maximum sediment delivery would be 30.4 

percent of the total, and the maximum nitrogen delivery would be 28.2 percent of the 

total, the SAND2 sediment inputs for the Inner Biloxi marshes were adjusted to 101 

percent (30.4 percent of sediment/30 percent of the water), and 94 percent of the nitrogen 

(28.2 percent of introduced nitrogen/30 percent of the introduced water). 

Whenever FWP marsh restoration measures were proposed within a diversion receiving 

area, the acres of created marsh were entered into the SAND2 model as FWP created 

acres so that the diversion model would predict benefits both the existing and created 

marshes. In those cases, the SAND2 model would report the benefits of both the 

diversion and affected marsh restoration measures. 

In some subunits, FWP shoreline protection measures were proposed within a diversion 

receiving area. Diversion operations were assumed not to change shoreline loss 

processes or rates. 

Predicting Wetland Benefits of Marsh Restoration Projects

A mathematical model or formula was developed to calculate net marsh restoration 

project benefits (net acres = future-with project acres minus FWOP acres). Formula 

inputs include: created acres, year constructed, loss rate (acre/year), subsidence, and 

FWP year benefits loss rate reverts. 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-44 June 2012

Figure 2-4 depicts marsh restoration net benefits, FWOP acres, and FWP acres in 

relation to time. Acres are added to existing marsh acres in the FWP. The loss rate for 

the FWOP acres and the created acres will be added together for the FWP acres. After 

the FWOP acres reach zero, remaining acres will be lost at the loss rate for the created 

acres.

Figure 2-4: Marsh Restoration Net Benefits

Predicting Wetland Benefits of Marsh Nourishment Projects

A mathematical model or formula was developed to calculate net marsh nourishment 

project benefits (net acres = future-with project acres minus FWOP acres). Formula 

inputs include: total acres nourished, construction year, net annual benefit (acre/year), 

FWOP zero (the year when the FWOP marsh acreage has reached zero), subsidence, and

FWP year benefits loss rate reverts. 

Figure 2-5 depicts marsh nourishment net benefits, FWOP acres, and FWP acres in 

relation to time. The marsh nourishment project affects the area causing the land loss rate 

to be reduced by a factor of two. The net benefits are additive until the FWOP acreage 

reaches zero. 

Marsh Creation

-1000

0

1000

2000

3000

4000

5000

6000

2000 2020 2040 2060 2080 2100 2120 2140 2160 2180 2200

Year

Acres

-200

0

200

400

600

800

1000

Net Benefit Acres

FWOP

FWP

FWOP w/med SLR

FWP w/med SLR

benefits

benefits w/ med SLR
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-45 June 2012

Figure 2-5: Marsh Nourishment Net Benefits

Predicting Wetland Benefits of Shoreline Protection Projects

A mathematical model or formula was developed to calculate net shoreline protection 

project benefits (net acres = future-with project acres minus FWOP acres). Formula 

inputs include: number of years benefitted, total acres, year constructed, max acreage 

benefitted, FWOP loss rate, FWP loss rate, and FWOP zero. 

Figure 2-6 depicts shoreline protection net benefits, FWOP acres, and FWP acres in 

relation to time. Net benefits will accrue for the set length of time referred to as “years 

benefitted”. Benefits will level out and then decrease at the FWOP land loss rate once 

the FWOP project acreage reaches zero. Sea level rise is not considered in the shoreline 

protection models because it is assumed that the project is maintained as needed for 25 

years.

Marsh Nourishment

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

1980 2000 2020 2040 2060 2080 2100 2120 2140 2160 2180 2200

Year

Acres

0.00

100.00

200.00

300.00

400.00

500.00

600.00

700.00

Net Benefit Acres

FWOP

FWP

FWOP w/med SLR

FWP w/ med SLR

Benefits

Benefits w/med SLR
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-46 June 2012

Figure 2-6: Shoreline Protection Net Benefits

Wetland Acreage Predictions Under Increased Sea Level Rise (SLR) Rates

For the medium and high scenarios, the future wetland loss rates were increased to 

simulate effects of increased wetland submergence. Using USACE-predicted future 

water levels (based on the Shell Beach gage) under medium and high SLR scenarios, 

those water levels were converted into RSLR rates, assuming that those water levels 

incorporate both subsidence and sea level rise effects. By subtracting the average 

accretion value of 0.3 inches per year (in/yr) (an average of accretion measurements 

obtained throughout the project area), from the year 2011 baseline RSLR rate of 0.4 in/yr, 

a net baseline submergence rate of 0.11 in/yr was calculated. Likewise, the 0.3 in/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 0.39 in/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 

0

200

400

600

800

1000

1200

1400

1600

1980 2000 2020 2040 2060 2080 2100

DATE

ACRES

FWOP FWP Net Benefits
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-47 June 2012

water in 10 years. Consequently, under the high SLR scenario, marshes not receiving 

additional sediment would totally disappear by year 2033. 

Collapse thresholds were not applied to the wetlands receiving increased input of 

suspended sediment from the proposed Violet, Louisiana Freshwater Diversion (i.e., the 

Central Wetlands, the south Lake Borgne marshes, East Orleans Landbridge, and the 

inner Biloxi marshes). For those areas, FWP acreages were determined using the 

SAND2 model benefits with high wetland loss rates due to accelerating submergence. 

Assessment of Feature Sustainability under Relative Sea Level Rise 

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 (Elev.) – Features at higher elevations are more sustainable under 

RSLR, 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 (FW Influ.) – 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 operations and 

maintenance (O&M). (Y = natural features; N = hard features) 

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 2-12 summarizes the sustainability of each restoration feature under RSLR. 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-48 June 2012

Table 2-12: Sustainability Under Relative Sea Level Rise by Feature

Area Measure Alternatives

Sustainability Factors

Elev. Score

FW 

Influ.

Wave 

Energy

Natural 

feature

Biloxi 

Marsh

BR1 B, C, D Y Y Y Y 4 Excellent

BS1 C, D N N N N 0 Poor

BS2 C, D N N N N 0 Poor

BS3 D N N N N 0 Poor

BM1 C, D N Y N Y 2 Good

MRGO MRGO1 B, C, D N N N N 0 Poor

MRGO2 B, C, D N N N N 0 Poor

MRGO3 B, C, D N N N N 0 Poor

MRGO4 B, C, D N N N N 0 Poor

MRGO5 B, C, D N Y N Y/N 1.5 Fair/Good

MRGO6 B, C, D N N N N 0 Poor

MRGO7 B, C, D N Y N Y/N 1.5 Fair/Good

Central 

Wetlands

CC1 - CC6 B, C, D Y Y Y Y 4 Excellent

CM1- CM5 C, D N Y Y Y 3 Very Good

East Orleans 

Landbridge

EM1 B, C, D N N N Y 1 Fair

EM2 B, C, D N Y N Y 2 Good

EM3 C, D N Y Y Y 3 Very Good

EM4 C, D N Y N Y 2 Good

EM5 D N N N Y 1 Fair

ES1 C, D N N N N 0 Poor

ES2 C, D N N N N 0 Poor

ES3 C, D N N N N 0 Poor

EV1 D N N N N 0 Poor

South Lake 

Borgne

LM1 B, C, D N Y N Y 2 Good

LM2 B, C, D N Y N Y 2 Good

LM3 B, C, D N Y N Y 2 Good

LM4 C, D N Y Y Y 3 Very Good

LS1 C, D N N N N 0 Poor

Terre aux 

Boeufs 

TM1 B, C, D N N Y Y 2 Good

TM2 B, C, D N N Y Y 2 Good

TM7 C, D N N Y Y 2 Good

TM8 C, D N N Y Y 2 Good

Hopedale HM1 C, D N N Y Y 2 Good

If the sustainability scores are averaged, alternatives B, C, and D are all in the range of 

Fair to Good sustainability. All alternatives include the most sustainable types of features, 

i.e., the cypress swamp and ridge habitat. The smallest plan, alternative B is marginally 

more sustainable simply because it includes the least number of features. For alternatives

C and D, sustainability decreases marginally as less sustainable features, such as 

shoreline protection, are added. 

Since alternatives B, C, and D cannot be substantially differentiated based on relative sea 

level rise, a detailed WVA analysis of the three RSLR scenarios was only performed on 

the tentatively selected plan (alternative C). Table 2-13 below shows the net acres 

projected under each of the three RSLR scenarios based on feature locations. 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-49 June 2012

Table 2-13: Robustness of Features in Tentatively Selected Plan Under 

all Relative Sea Level Rise Scenarios

Feature Location

Net Acres Robust 

Under all 

Scenarios?

Low 

RSLR

Medium 

RSLR

High 

RSLR

Lower Pearl River 1,056 905 0 No

East Orleans Landbridge 819 642 0 No

MRGO Channel 95 75 0 No

South Lake Borgne 6,326 5,031 0 No

Central Wetlands Swamp 3,793 4,914 7,340 Yes

Central Wetlands Marsh 6,478 4,785 0 No

Terre aux Boeufs 2,937 2,165 0 No

Hopedale 244 181 0 No

Bayou La Loutre Ridge 14 25 48 Yes

Biloxi Marsh 2,809 2,220 0 No

Biloxi Marsh Outer Shoreline 49 48 0 No

Although it may seem counterintuitive that the net acres for ridge and swamp increase as 

RSLR increases, the reason is that the WVA calculation subtracts existing and future 

marsh acres from the ridge and swamp footprints. As RSLR increases, the marsh acres 

decrease; therefore, the ridge and swamp net acres increase. Another difference is in the 

marsh and swamp WVA calculations. The marsh WVAs take into account changing 

water to land ratios over time, while the swamp WVA procedures simply multiply quality 

by total project area. In general, ridge and swamp are more sustainable than marsh 

because they have a higher elevation and would be less affected by RSLR. In general, the 

most sustainable features will be those will higher elevations; features being nourished by 

diversions; and the diversion itself. 

2.4.1.2 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. 

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 Freshwater Diversion was assumed to be operational in 

2015 in the analysis. 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-50 June 2012

2.4.1.3 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 appendix U. 

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 percent and S&A of 6 percent 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 were applied. The cost-effectiveness of 

features was re-evaluated when detailed information became available. Costs were 

developed with October 2011 price levels using a four percent discount rate and 0.04655 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-51 June 2012

amortization factor. The detailed cost-estimates did not significantly alter the costeffectiveness of any plan feature.

Table 2-14 provides the costs and benefits generated for the formulation and analysis of 

plans. 

Table 2-14: 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 MRGO 1,932 1 159,995,564

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

Biloxi 010sp 100 2 1,397,042

Biloxi 011sp 91 2 566,508
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-52 June 2012

Table 2-14: Measures Retained for Plan Formulation

Geographic Area Measure Label Total AAHU Annual Cost

Biloxi 013sp 179 2 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 029asp 137 3 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 243 425 4 1,354,619

Terre aux Boeufs 244 984 4 4,217,112

Terre aux Boeufs 241 1,051 4 5,186,676

Terre aux Boeufs 242 972 4 2,066,854

Florissant 191 12 1,576,410

Hopedale 190 186 2,054,465

Jetty Realignment 029bsp + 028 232 5 3,392,549

Notes:

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.

2.4.1.4 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 for shoreline protection 

features were calculated as part of the project costs. Additional adaptive management 

measures associated with increased RSLR scenarios were also incorporated into the 

project costs for shoreline protection features. 

For marsh restoration features, a ratio of 64 percent land to 36 percent water was used as 

a threshold for when re-nourishment would be required. The land/water ratio is based on 

the total amount of land remaining in any feature at the end of a period of analysis. 

The land/water ratio is based on standard practices used in Louisiana coastal wetlands 

restoration. The WVA methodology for coastal marsh community models outlines six 

variables used in determining project benefits. Of the six WVA variables, Variable V3, 

marsh edge and interspersion, addresses habitat values as a ratio of land to water 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-53 June 2012

expressed as a marsh class. Variable V3 was used to determine the threshold for marsh 

restoration adaptive management actions associated with increased relative sea level rise.

Variable V3 takes into account the relative juxtaposition of marsh and open water for a 

given marsh to open water ratio, and is measured by comparing the project area to sample 

illustrations depicting different degrees of interspersion. Interspersion is especially 

important when considering the value of an area as foraging and nursery habitat. Certain 

interspersion classes can be indicative of marsh degradation, a factor taken into 

consideration in assigning suitability indices to the various interspersion classes. 

A relatively high degree of interspersion in the form of tidal channels and small ponds 

(Class 1) is assumed to be optimal; tidal channels and small ponds offer interspersion, yet 

are not indicative of active marsh deterioration. Numerous small marsh ponds (Class 2) 

offer a high degree of interspersion, but can be indicative of the onset of marsh break-up 

and deterioration, and are therefore assigned a lower SI of 0.6. Large ponds (Class 3) and 

open water areas with little surrounding marsh (Class 4) offer lower interspersion values 

and usually indicate advanced stages of marsh loss. Also grouped within Class 3 are 

areas of “carpet” marsh which contain no or relatively insignificant tidal channels, creeks, 

trenasses, ponds, or other features of interspersion but may still provide habitat for 

aquatic organisms during tidal flooding. Class 5 is characterized by very small marsh 

islands (i.e., less than 5 percent emergent marsh) or areas made up entirely of open water. 

Habitat of this type provides little to no marsh edge and its function as nursery habitat for 

marine organisms or foraging habitat for avian predators has been significantly reduced. 

Although habitats represented by this classification are predominantly unvegetated open 

water areas, they still provide habitat for many fish and shellfish species and provide 

loafing areas for waterfowl and other waterbirds. Also grouped within Class 5 are areas 

characterized as solid land with no interspersion features and little to no vegetation. 

Newly created marsh with no ponds, creeks, or other tidal features would fall within this 

class.

The descriptions provided in the WVA methodology use aerial photographs of 

representative sites to guide the visual assessment of the quality or state of any particular 

wetland habitat. The representative photo used to assess the land to water ratio as a 

percentage for OMRR&R and adaptive management estimates is Interspersion Class 2. 

A ratio was developed from the photo and the result was a ratio of 64 percent land to 36 

percent water.

The 50 year land loss totals for the MRGO restoration project were calculated by USFWS 

using the three levels of RSLR. Total numbers under the low and medium RSLR rates 

shows there are no instances where OMRR&R would be required for marsh restoration 

and nourishment areas when using the land to water ratio of 64 percent to 36 percent. 

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 percent. 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 

percent. OMRR&R and adaptive management measures would address risks and 

uncertainties.
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-54 June 2012

Under the high sea level rise rate, all wetland restoration features lose significant amounts 

of land below the 64 percent threshold, and all shoreline protection features would 

require significant adaptive management actions. Because it has been determined that the 

submergence threshold is reached in year 2023 under the high RSLR rate, it was 

determined that land/water ratios should be monitored to determine if the high RSLR 

scenario is occurring. Implications of RSLR at the high rate to infrastructure in coastal 

areas throughout the nation would be significant. If land/water ratios trends indicate the 

high RSLR rate is occurring, Federal investment in construction would cease and the 

OMRR&R plan would require significant changes to maintain project benefits. 

2.5 COST EFFECTIVENESS/INCREMENTAL COST 

ANALYSIS

A Cost Effectiveness/Incremental Cost Analysis (CE/ICA) was conducted to evaluate the 

benefits of alternative plans as related to cost and identify the plans that provide the 

greatest benefits with the least amount of incremental cost. “Cost effective” refers to the 

plan that costs less and yields more output for less money than the other alternatives. 

Subsequently, through incremental cost analysis, a variety of alternatives are evaluated to 

arrive at a “best” level of output within the limits of both the sponsor’s and the USACE’s

capabilities. 

The subset of cost effective plans were examined sequentially (by increasing scale and 

increment of output) to determine which plans were more efficient and achieved the 

greatest benefits. These plans are called “Best Buys.” “Best Buy” plans provide the 

greatest increase in output at the lowest average cost and have the lowest incremental 

costs per unit of output. 

In most analyses, there are multiple Best Buy plans. As the outputs produced increase in 

the Best Buy plans, the average costs per unit of output and incremental costs per unit of 

output increase as well. As a result, the incremental analysis does not point to the 

selection of any single plan. The results must be considered with other decision-making 

criteria such as significance of outputs, acceptability, completeness, effectiveness, risk 

and uncertainty, and reasonableness of costs to support the selection and recommendation 

of a particular plan. 

2.5.1 Institute for Water Resources (IWR) Plan Steps

The USACE’s Institute for Water Resources (IWR) has developed procedures and 

software for conducting CE/ICA. IWR-PLAN Decision Support Software was used in 

performing the CE/ICA. As a result of the computational limitations of the IWR-PLAN

software, over 50 individual measures could not be run in the IWR-PLAN at the same 

time (combining all measures). Therefore, separate runs in each major geographic area 

were made to reduce the number of possible combinations and meet the limitations of the 

IWR-PLAN software. 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-55 June 2012

Some scale of restoration in each of these geographic areas was considered necessary to 

address the portions of 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 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 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-56 June 2012

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, the Florissant area (Subunit 19) is isolated from other portions of the 

study area, and was therefore evaluated separately.

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. The resulting 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 – Four separate CE/ICA runs were made for each of the following geographic 

areas:

• Biloxi Marsh (three marsh areas; ten shoreline segments) 

• MRGO (eight narrowing/shoreline features)

• East Orleans/South Lake Borgne (nine marsh areas; four shoreline segments; 

SAV measure) 

• Terre aux Boeufs/Hopedale (five 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 that contained at least two measures, 

i.e. plans with only one measure were not selected. 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-57 June 2012

• Intermediate scales – Selected one or more plans based on cost effective 

increments, i.e. where large amount of outputs could be gained for minimal 

additional cost. 

• Maximum scales – In order to develop the full cost effectiveness curve, the 

largest Best Buy Plan was always selected, i.e. plan that contained all measures in 

that group. 

Step 3 - Repeated the CE/ICA using scales of alternatives as described below:

• Biloxi Marsh – four scales selected based on Steps 1 and 2.

• MRGO – five 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 six scales.

• East Orleans/South Lake Borgne – five scales based on Steps 1 and 2. 

• Terre aux Boeufs/Hopedale – three scales based on Steps 1 and 2. 

• Ridge – Partial ridge vs. full ridge – two scales.

• Florissant – one scale.

• Central Wetlands – Swamp only vs. swamp plus marsh – two scales.

All solutions were combinable. In Step 3 of the CE/ICA, each plan was formulated 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 remnant Bayou La 

Loutre Ridge were not as effective as many of the measures in other areas. However, the 

inclusion of some restoration measure in these areas is considered necessary to fulfill the 

requirements of the study authority. 

• The former MRGO navigation channel was constructed 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 only natural ridge in the immediate vicinity of the MRGO is the Bayou La 

Loutre Ridge. 

• 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, non-governmental organizations (NGOs), state and 

local government, and resource agencies. 

The inclusion of some scale of restoration in these areas was integral to the development 

of the plan. This constraint was added to the IWR-PLAN formulation process to ensure 

the program produced a wide range of alternatives that met the study objectives. 

 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-58 June 2012

2.5.2 Institute for Water Resources (IWR) Plan Results

IWR-PLAN generated 6,721 plan combinations. Including the no action alternative (Plan 

#1), there were 285 cost-effective plans and 19 Best Buy plans with costs up to $6.5 

billion. Table 2-15 lists the descriptions of each of the Best Buy plans. A summary of 

the costs and benefits associated with the plans generated in IWR is provided in table 2-

16. 

Table 2-15: Best Buy Plan Descriptions

Best 

Buy Description

1 No action.

2 Central Wetlands: Cypress measures CC1-CC6 and Violet Diversion

South Lake Borgne: LM1-3 

East Orleans Landbridge: EM1 and 2

MRGO: MRGO 1-7 

Biloxi Marsh: BR1

Bayou Terre aux Bouefs: 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

19 BB18 plus Florissant

Table 2-16: Best Buy Plans

Plan 

#

Output 

(HU*) Annual Cost

Average 

Cost 

($/HU)

Incremental 

Cost ($)

Incremental 

Output (HU)

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
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-59 June 2012

Table 2-16: Best Buy Plans

Plan 

#

Output 

(HU*) Annual Cost

Average 

Cost 

($/HU)

Incremental 

Cost ($)

Incremental 

Output (HU)

Incremental 

Cost per 

Output

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

*Habitat Unit

The Best Buy plans that were generated in IWR-PLAN addressed the goals and 

objectives of the study in varying degrees. The PDT determined that 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. 

2.5.3 Selection of the Final Array of Alternatives 

See Section 2.7.3 of the feasibility report for a detailed description of the selection of the 

final array of alternatives. In addition to the No Action Plan (plan #1), three Best Buy 

plans were selected for the final array. Best Buy plans #2, #7, and #10 (alternative B, C, 

and D, respectively) were chosen based on cost effective increments, i.e. where large 

amount of outputs could be gained for minimal additional cost. These plans also 

represent a wide range of costs and outputs. A brief description of Best Buy Plans #2 

through #19 follows. 

Best Buy Plan #2 (alternative B) was selected for further consideration because it was the 

least costly Best Buy Plan. Alternative B does not achieve all of the goals of the study, 

but it does include some restoration measures for all of the targeted habitat types. 

Alternative B would restore or protect 9,518 acres of fresh and intermediate marsh, 

10,253 acres of brackish marsh, 10,431 acres of cypress swamp, and 257 acres of saline 

marsh. Alternative B does not meet the target acre objectives for brackish marsh. 

Additionally, 11,424 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 by 

compensating for any habitat switching. Alternative B did not contain any features in the 

Biloxi Marsh and only includes one feature on the East Orleans Landbridge; therefore, 

alternative B does not fully address the objective to restore and protect critical landscape 

features for storm surge reduction. 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-60 June 2012

Best Buy Plans #3 to #5 also do not meet the objectives for brackish habitat, habitat 

switching objectives, or contribute substantially to the restoration and protection of the 

East Orleans Landbridge and the Biloxi Marsh. Therefore, these plans were not 

considered further. 

Best Buy Plan #6 includes restoration features in the Biloxi Marsh and more features that 

protect the East Orleans Landbridge. Plan #6 does not meet the target for increasing 

brackish marsh. 

Best Buy Plan #7 (alternative 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. Therefore, alternative C was selected for further evaluation in the 

final array of alternatives because it is a complete plan for the Lake Borgne ecosystem 

and the areas affected by the MRGO. Alternative C was the first 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. Alternative C addresses the gaps left by existing and authorized 

restoration projects. Alternative C includes the necessary shoreline protection and marsh 

restoration features to form a complete plan for the ecosystem.

Best Buy Plan #8 includes more shoreline protection features in the MRGO. 

Best Buy #9 includes the additional features in Best Buy #8 as well as additional features 

in the East Orleans Landbridge. 

Best Buy #10 (alternative D) includes the features in Plans #8 and #9, and also adds 

additional shoreline protection in the Biloxi Marsh. Because of these additions, 

alternative D improves upon alternative C by further protecting these critical landscape 

features, and better meets the storm surge objective. Alternative D was included for 

further evaluation because it was the first Best Buy after alternative C to include more 

measures to protect both of these critical landscape features.

Best Buy Plan #11 adds additional protection features along the MRGO/Lake Borgne 

Landbridge. The incremental cost difference between Best Buy Plans #10 and #11 is 

relatively small. However the incremental cost per unit of output is relatively low. 

Best Buy 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 alternative D 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 Federal cooperating partner agencies, and were an 

additional consideration in the decision to not carry this alternative forward.

The incremental costs associated with Best Buy Plans #13 to #15 were not considered 

reasonable for the relatively minor amount of associated benefits. Plan #16 provides a 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-61 June 2012

substantial increase in benefits, but the total estimated construction costs for plan #16 

were considered too great for the associated ecosystem outputs. Best Buy Plans #17 to 

#19 were considered too costly for the incremental benefits provided. 

Table 2-17 summarizes the Final Array of Alternatives estimated construction costs, 

AAHUs, and acres restored.

Table 2-17: Final Array of Alternatives

Plan

Estimated 

Construction Cost

Measure

AAHUs 1 

Plan 

AAHUs 2 

Acres

3 Restored

A

4 

$0 0 0 0

B

5

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

C $2.9 B ($124 M annual) 10,324 17,575 58,861 6

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

NOTES: 

1. Based on preliminary costs. 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 whereas 

influenced by the freshwater diversion. The influence of the authorized Violet Freshwater 

Diversion was considered in the calculation of all benefits in this table.

3. The AAHUs in this column are based on the Wetland Value Assessments (WVAs) 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 Tentatively Selected Plan based on a revised WVA 

methodology. In this final plan analysis, the Violet Freshwater Diversion was assumed operational 

in 2027. The total AAHUs for Plan C considering synergies is now 33,839 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.

Table 2-18 below provides a summary of measures contained within each alternative 

plan. 

Table 2-18: 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 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-62 June 2012

Table 2-18: Restoration Features Included in the Final Array

Area Measure Description

Plan 

B

Plan 

C

Plan 

D

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 

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 40Arpent 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 

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 

Y Y Y 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-63 June 2012

Table 2-18: Restoration Features Included in the Final Array

Area Measure Description

Plan 

B

Plan 

C

Plan 

D

Borrow Cycle 9.

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. 1.6 million cubic 

yards of borrow material would be obtained from North Lake Borgne 

Borrow Cycle 7.

Y Y 

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. 1 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 

VIOLET 7,000 cfs capacity freshwater diversion from the Mississippi River to 

the MRGO in the vicinity of Meraux. Y Y Y 

VIOLET 

REC

Recreation Feature - 6,500 linear feet of guide levee multi-use path, 

4,500 linear feet of path at the base of the levee, 15 picnic shelters, 

interpretive signage, bathrooms, parking, solar lighting and vegetative 

plantings along the Violet Freshwater Diversion.

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. 

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 in the area bounded by Highway 433, Little Lagoon, Salt 

Bayou and Highway 90. Approximately 4.1 million cubic yards of 

dredged material would be obtained from Northeast Lake Borgne 

Y Y 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-64 June 2012

Table 2-18: Restoration Features Included in the Final Array

Area Measure Description

Plan 

B

Plan 

C

Plan 

D

Borrow Cycle 8.

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. Approximately 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 

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 Doulluts 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 Y Y
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FEIS MRGO Ecosystem

Restoration Plan 2-65 June 2012

Table 2-18: Restoration Features Included in the Final Array

Area Measure Description

Plan 

B

Plan 

C

Plan 

D

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.

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 

2.5.3.1 Violet, Louisiana Freshwater Diversion

All of the action plans include the design and implementation of the Violet, Louisiana 

Freshwater Diversion as authorized in WRDA 2007 Section 3083, as an important feature 

to increase the sustainability of the plan. The forecasted FWOP salinity conditions 

suggest that salinity in the study area would be reduced by the closure of the MRGO and 

other authorized projects. However, additional inputs of freshwater may be necessary to 

fully restore the historic salinity regime. The MRGO was excavated through the eastern 

portion of the Central Wetlands, which resulted in saltwater intrusion and increased 

salinity in the area. The habitat of the Central Wetlands changed from a cypress swamp 

and fresh/intermediate marsh system to an entirely brackish system. In order to restore 

the habitat type adversely affected by the former navigation channel, a freshwater system 

must be established in the Central Wetlands area.

The preliminary yearly operational scheme of the Violet, Louisiana Freshwater Diversion 

to benefit cypress swamp and marsh restoration as part of the MRGO Ecosystem 

Restoration Plan Feasibility Report is based on the required hydroperiod and depth 

constraints of bald cypress (Taxodium distichum) phenology and seasonal water levels 

based on the Mississippi River stage. Because of the specific requirements of bald 

cypress, it was used as an indicator of conditions conductive to swamp tupelo (Nyssa 

aquatica) and other constituents of forested wetland. In addition, maiden cane (Panicum 

hemitomon) and bull tongue (Sagittaria lancifolia) are dominant species of 

fresh/intermediate marsh and marsh-hay cordgrass (Spartina patens) of brackish marsh. 

These species are often used as indicators of ecosystem health and restoration success 

(see Operations Scheme in appendix M).

Four potential locations for a freshwater diversion were evaluated to convey water from 

the Mississippi River to the Lake Borgne ecosystem. Figure 2-7 displays the four 

potential diversion locations. Additional information regarding the evaluation of the 

proposed locations for the Violet, Louisiana Freshwater Diversion is included in section 

2.6.2. 
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Restoration Plan 2-66 June 2012

Figure 2-7: Alternative Diversion Locations 

2.5.3.2 Recreational Components

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 costsharing agreement for construction of the recreation plan. Accordingly, the non-Federal 

share will be 50 percent of the recreation development costs. Non-Federal 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. All of the recreation features recommended were first 

identified through USACE meetings with community groups and non-governmental 

organizations (NGOs) from St. Bernard and Orleans Parishes. Additionally, appendix W 

refers to the Louisiana Department of Culture, Recreation and Tourism’s Statewide 

Comprehensive Outdoor Recreation Plan (SCORP), which presents findings from focus 

group meetings regarding locally preferred outdoor recreation activities. A third source, 
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FEIS MRGO Ecosystem

Restoration Plan 2-67 June 2012

the University of Wisconsin, prepared a recreation needs report for St. Bernard Parish

and part of Orleans Parish. All three of these resources are used in identifying the 

recommended recreation features, including development of the benefits of each 

recreation development. All three sites offer American’s with Disabilities Act (ADA) 

accessible features, including parking lots, bathrooms, access to boardwalks, ramps, and 

picnic shelters. 

Bienvenue Triangle Recreation Feature

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 students about environmental principles, processes and a general 

education concerning marshland, habitat, and wildlife. 

Existing Condition

The entrance of the proposed recreation features would offer interpretive signage 

detailing the history of the Bienvenue Triangle including 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. This recreation feature would be constructed 

before wetland restoration begins to afford viewing opportunities of the stages of cypress 

swamp creation. Also, the local sponsor could develop wetland research pilot sites 

adjacent to the boardwalk which schools could use to develop test sites of certain types of 

marsh grasses and other research projects related to wetland restoration. Information 

from the University of Wisconsin report revealed the need for children’s programs; such 

as some discussion about plants and animals living in the bayou and wetland preservation 

efforts. Signage explaining the proposed marsh creation 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. 

Proposed Improvement 

Constraints to development include the Alabama Great Southern Railroad (a.k.a. Norfolk 

Southern Railroad) and local sponsor real estate acquisition. Discussion regarding 

pedestrian access 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 
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FEIS MRGO Ecosystem

Restoration Plan 2-68 June 2012

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 City of New Orleans Sewerage and Water Board, the railroad is owned by Norfolk 

Southern Railroad, the levee is owned by the New Orleans Levee Board, and the swamp 

is owned by less than five owners.

The recommended design for the Bienvenue Triangle recreation feature is Option A, and 

is shown in figure 2-8; its selection is based upon the benefit-to-cost ratio (BCR). Two 

designs, Option A and B, were developed based upon input from community groups in 

the Lower 9th

 

 Ward. Both Option A and B were evaluated in terms of benefits and costs 

and the resulting ratio was the basis for selection. Option A has the higher BCR, 1.14, 

and is one of three recommended recreation features for the MRGO Ecosystem 

Restoration project. 

Figure 2-8: Bienvenue Triangle Overlook Recreational Feature – Option A

The recommended plan for the Bienvenue Triangle consists of a 100 linear feet of 

platform, 995 linear feet of boardwalk into the swamp, four picnic shelters, interpretive 

signage, bathrooms, parking, solar lighting and vegetative plantings. Option A is the 

recommended plan for the Bienvenue Triangle.
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FEIS MRGO Ecosystem

Restoration Plan 2-69 June 2012

Violet, Louisiana Freshwater Diversion Recreation Feature

Currently, the site is used as agricultural land and offers no recreational opportunity. 

Existing Condition

Recreational features are proposed to compliment and use the Violet Freshwater 

Diversion, a conveyance of water to nearby swamp and marsh land, as an activity 

resource. Recreation features at the proposed Violet, Louisiana Freshwater Diversion site 

in St. Bernard Parish include multi-use paths, open space, picnic tables and shelters, 

interpretive signage in a park setting with landscaping, trees and lighting. The multi-use 

path would be located along the top of the guide levees and meander off the levee to 

areas with picnic tables and interpretive signage. The trail could also connect to the 

adjacent park at the old Archbishop Hannan site and lead to other bike paths in the area. 

A parking lot would also be provided on-site. Interpretive signage would provide a 

description of the diversion’s function for restoring freshwater to the Central Wetlands 

and the general purpose of the ecosystem project surrounding the MRGO. 

Proposed Improvement 

The recommended design for the Violet Diversion recreation feature is Option B and 

shown in figure 2-9; its selection was based upon the BCR. Two designs, Option A and 

B, were evaluated and Violet, Louisiana Freshwater Diversion, Option B has the higher 

BCR, 5.62 and is the second of three recommended recreation features for the MRGO 

Ecosystem Restoration project. 

The recommended plan for the Violet, Louisiana Freshwater Diversion recreation feature 

consists of 6,500 linear feet of guide levee multi-use path, 4,500 linear feet of path at the 

base of the levee, 15 picnic shelters (including three handicap accessible), interpretive 

signage, bathrooms, parking, solar lighting and vegetative plantings. Option B is the 

recommended plan for the Violet, Louisiana Freshwater Diversion. 

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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FEIS MRGO Ecosystem

Restoration Plan 2-70 June 2012

Figure 2-9: Violet, Louisiana Freshwater Diversion Recreational Feature – Option 

B 

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, were based upon 

input from the Coastal Zone Administration of St. Bernard Parish. Both Option A and B 

were evaluated in terms of benefits and costs and the resulting ratio is the basis for 

selection. Shell Beach Option B has the higher BCR, 2.02 and is the third and final 

recommended recreation feature for the MRGO Ecosystem Restoration project. 

The recommended recreation feature for Shell Beach is Option B that consists of 343 

linear feet of boardwalk into the MRGO, 805 linear feet of shoreline boardwalk to five

picnic shelters (two handicap accessible), interpretive signage, bathrooms, parking, solar 

lighting and vegetative plantings. Option B is the recommended plan for Shell Beach and 

is presented in figure 2-10. 
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FEIS MRGO Ecosystem

Restoration Plan 2-71 June 2012

Figure 2-10: Shell Beach Recreational Feature – Option B

2.6 DESCRIPTION OF ALTERNATIVES CONSIDERED

2.6.1 Alternative A - No Action Plan (FWOP Condition) 

The no action alternative is required by the NEPA and represents the FWOP condition by

which alternatives considered in detail are compared. The no action alternative considers 

restoration programs that would continue into the future, and that in the absence of this 

restoration plan, would continue to be proposed and implemented under CWPPRA, 

CIAP, LCA, and other programs. 

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 throughout the study area 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 of the study area. Continued 

wetland fragmentation and the eventual conversion to shallow open water habitat would 
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FEIS MRGO Ecosystem

Restoration Plan 2-72 June 2012

have negative consequences on a variety of important environmental resources in the 

study area. 

As a result of the devastating effect of Hurricane Katrina which made landfall in 2005, 

several important hurricane protection projects are under construction in the study area 

that are expected to have significant impacts on the future conditions of the area without 

implementation of this restoration study. 

An important project in the area includes the IHNC sector gate for flood control and 

navigation. A surge barrier, similar to a floodwall but much larger, would be constructed 

near the confluence of the GIWW and the MRGO, generally running north-south from a 

point just east of Michoud Canal on the north bank of the GIWW and just south of the 

existing Bayou Bienvenue flood control structure (figure 2-11). Navigation gates would 

be constructed where the barrier crosses the GIWW and Bayou Bienvenue to reduce the 

risk of storm surge coming from Lake Borgne and/or the Gulf of Mexico. 

Another navigation gate would be constructed near Seabrook, where the IHNC meets 

Lake Pontchartrain, to block storm surge from entering the IHNC from the lake. 

Figure 2-11: IHNC Surge Barrier

As described in chapter 1, the MRGO closure structure was constructed and completed 

in July 2009. These projects individually and cumulatively are anticipated to change the 

future environmental conditions of the basin regardless of whether a restoration plan is 

implemented or not. Important among the anticipated changes is the reduction in salinity 

levels in the area as demonstrated by the hydrologic modeling discussed in more detail in 

chapter 3. More in-depth discussions of the impacts are described further in chapter 4

for the applicable resources affected.
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FEIS MRGO Ecosystem

Restoration Plan 2-73 June 2012

Hurricanes Katrina and Rita resulted in a total marsh loss of over one third of the total 

wetland losses predicted by the Coast 2050 Report (LCWCRTF and WCRA, 1999). 

Within the Lake Borgne and MRGO area, approximately 663 acres of wetlands were 

converted to open water (Barras, 2006). This loss rate exceeded the average background 

loss rate of approximately 144 acres per year from 1988 to 2004 (Morton et al., 2005). In 

the northern and eastern shorelines of Lake Borgne, new water bodies formed and 

existing water bodies expanded (USGS, 2006). 

In the FWOP conditions, wetland losses would be offset to some extent by other Federal, 

state, local, and private restoration efforts. Under Section 7006 of the WRDA 2007, the 

LCA program has authority for feasibility-level reports of six near-term critical 

restoration features. The projects that are considered a part of the FWOP conditions for 

this study include: 

• Medium Diversion at White Ditch – The draft recommended plan includes 

diverting up to 35,000 cfs of freshwater from the Mississippi River left 

descending bank at river mile 60.0 into the Breton Sound basin as well as restore 

thirty-one acres of ridge and terrace habitat and restore 385 acres of marsh. The 

diversion influence area is approximately 98,000 acres. 

• Amite River Diversion and Canal Modification; 500 cfs freshwater diversion. 

This project is currently in the feasibility phase with a final report expected in 

December 2010. This project would construct gaps in the existing banks of the 

Amite River Diversion Canal to allow floodwaters to introduce additional 

nutrients and sediment into western Maurepas Swamp. The exchange of flow 

would occur during flood events on the river and from the runoff of localized 

rainfall events. Nutrients and sediment would be provided to facilitate organic 

deposition in the swamp, improve biological productivity, and prevent further 

swamp deterioration. This project is designed to complement two other LCA 

projects: the Hope Canal Diversion and Convent/Blind River Diversion, and one 

proposed Coastal Impact Assistance Program project, Hydrologic Restoration in 

Swamps West of Lake Maurepas.

• Hope Canal freshwater diversion; 1,000 cfs freshwater diversion. This 

restoration feature involves a small diversion from the Mississippi River through 

a new control structure at Hope Canal. The objective is to introduce sediment and 

nutrients into Maurepas Swamp south of Lake Maurepas. The introduction of 

additional freshwater via the diversion would facilitate organic deposition, 

improve biological productivity, and prevent further deterioration of the swamp. 

Work for this feature has been initiated in engineering and design and NEPA 

compliance under CWPPRA. 

• Blind/Convent River Diversion; 3,000 cfs freshwater diversion. This project is 

currently in the feasibility phase with a final report expected in December 2010. 

The project would involve construction of a small siphon(s) over the Mississippi 

River levee or construction of a concrete multi-barrel box culvert(s) in the 

Mississippi River in the vicinity of Convent. Freshwater from the Mississippi 

River would flow into a conveyance channel and eventually distributed through a 

network of small conveyance ditches in the project area.
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FEIS MRGO Ecosystem

Restoration Plan 2-74 June 2012

Other restoration projects occurring in the study area that would have an effect on FWOP 

conditions include: 

• CWPPRA PO-29 River Reintroduction into Maurepas Swamp. 

• CWPPRA PO-30 Lake Borgne Shoreline Protection project has been completed. 

• CWPPRA PO-32 Lake Borgne and MRGO Shoreline Protection project. This 

project was authorized in April 2003. Phase I design was complete in 2005 and 

phase II design was complete in 2007. Construction of the Lake Borgne portion 

has been completed and the MRGO portion has been proposed for 

deauthorization. Anticipated net acres benefited are 266 acres.

• CWPPRA PO-34 Alligator Bend Marsh Restoration and Shoreline Protection. 

This project is currently in planning and design. Construction is anticipated to 

start in October 2011 and end in September 2012. Anticipated net acres benefited 

would be 127 acres. 

• CWPPRA PO-36 (EB) Orleans Landbridge shoreline protection and marsh 

restoration. The goal of the project is to protect approximately 1,400 acres. 

• Lake Borgne and MRGO Shoreline Protection and accretion behind shoreline 

protection structures – Area 1 Doulluts Canal to Jahncke’s Ditch. Construction 

would commence in 2010 and protect approximately 3.8 acres/year and restore 

approximately 17 acres by 2030. 

• Lake Borgne and MRGO Shoreline Protection - Area 3 Doulluts Canal to Lena’s 

Lagoon. Construction would commence in 2010 and is anticipated to stop land 

loss and restore approximately 8.2 acres per year.

• USACE 3rd and 4th

• CIAP, The Rigolets Shoreline Protection and Marsh Restoration – Grand Coin 

Pocket, tier 2. Anticipated net acres benefited would be 100 acres. 

 Supplemental Funds - Lake Borgne Shoreline Protection and 

Marsh Restoration Project. This restoration project would create and nourish 

marsh in the Golden Triangle and Shell Beach area and protect shoreline in the 

Shell Beach area. Anticipated net acres benefited would be approximately 29 

acres per year.

• CIAP, Lake Pontchartrain Shoreline Protection and Marsh Restoration – Irish 

Bayou to Chef Menteur Pass, tier 2. Anticipated net acres benefited would be 46 

acres.

• CIAP, Fritchie Marsh Stormwater Diversion.

• State shoreline protection project along the Interior Biloxi Marsh funded with 

Federal surplus funds. 

• WRDA 2007 - The Violet, Louisiana Freshwater Diversion Project – Project to 

construct a freshwater diversion to meet or maximize the ability to meet the 

benefits identified in the Bonnet Carré Feasibility Study and Report prepared in 

1984. The Violet WRDA 2007 project is pending the findings of this study. 

• The New Orleans Sewerage and Water Board, in collaboration with St. Bernard 

Parish, has developed preliminary engineering alternatives for the use of treated 

wastewater for wetlands enhancement in the Central Wetlands as part of the CIAP 

program. The wastewater tertiary treatment plans that have been developed for 

Orleans and St. Bernard Parishes are seen as critical components to restore the 

area. The distribution of treated wastewater is needed to supplement the Violet, 
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FEIS MRGO Ecosystem

Restoration Plan 2-75 June 2012

Louisiana Freshwater Diversion, particularly in the northern portion of the 

subunit. If the funds appropriated under the CIAP program are insufficient to 

complete the necessary work to maximize the use of treated wastewater for 

wetlands enhancement in the Central Wetlands, these actions should be 

considered for inclusion as part of this plan, due to the sensitivity of the MRGO 

Ecosystem Restoration Plan to the implementation of these actions.

As a result of the LCA diversion projects in the Upper Pontchartrain sub-basin and the 

Hurricane and Storm Damage Risk Reduction System (HSDRRS) storm barriers, the 

salinity regime in the Lower Pontchartrain sub-basin is anticipated to change from 

baseline conditions. Table 2-19 demonstrates the projected FWOP salinity range based 

on the H&H modeling results discussed further in chapter 3 as well as the H&H 

Modeling Report included in appendix L. 

Table 2-19: Base and Predicted FWOP Salinity Range for Lake Borgne Ecosystem

BOX

1 

(Lake Borgne)

2 

(Lake Borgne)

13

(Interior Biloxi 

Marsh)

14 

(W. MS Sound)

73

(Interior Biloxi 

Marsh)

74

(Interior Biloxi 

Marsh)

Base FWOP Base FWOP Base FWOP Base FWOP Base FWOP Base FWOP

January 4-6 3-5 5-8 5-7 8-10 7-11 14-21 13-19 7-11 7-10 13-19 11-16

February 2-4 1-3 4-7 4-6 5-8 5-8 12-1 8 10-15 5-8 5-7 11-17 9-13

March 2-3 1-3 3-5 3-5 5-8 5-7 11-17 10-15 4-7 4-6 10-15 8-12

April 2-4 2-3 3-5 3-4 6-9 5-8 13-19 11-17 5-8 4-7 11-16 7-11

May 3-6 3-5 3-5 3-4 8-10 7-10 15-22 13-19 6-9 5-8 11-17 8-11

June 4-7 3-6 3-6 3-5 9-14 8-12 16-24 14-21 7-10 6-9 12-18 8-12

July 5-8 4-7 4-6 3-5 10-14 8-12 17-24 15-22 7-11 6-9 13-18 9-14

August 6-10 5-8 4-7 4-6 11-16 10-14 18-26 16-24 8-13 7-11 14-21 12-17

September 7-10 6-9 5-8 4-7 11-17 10-15 18-26 17-25 9-13 8-12 15-22 13-19

October 7-11 6-10 5-9 5-7 12-18 11-17 19-27 18-25 10-14 9-13 17-24 15-21

November 7-11 6-10 6-9 5-8 12-18 11-16 19-27 17-25 10-14 9-13 17-24 15-21

December 6-9 5-8 6-9 5-8 10-15 10-14 17-25 16-23 9-13 8-12 16-23 14-20

The Box numbers correspond to the numbers assigned to the boxes in the H&H model 

and represent specific areas within the Lower Pontchartrain sub-basin. For instance, Box 

2 refers to the Lake Borgne area; box 14 represents the West Mississippi Sound, box 73 

is the Interior Biloxi Marsh. As is demonstrated in the table, salinity levels are projected 

to change in the Lake Borgne area by only 1 part per thousand (ppt) to 2 ppt on average. 

2.6.2 Action Alternatives

2.6.2.1 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 Principals”. A 

small freshwater diversion would not mimic periodic overbank flooding of the 
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FEIS MRGO Ecosystem

Restoration Plan 2-76 June 2012

Mississippi River, a key process of the estuary that must be restored to re-establish 

historic salinity gradients, habitat types, and increase self-sustainability in the system. 

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 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. 

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. However, 

hydrodynamic modeling conducted for the study indicates that the salinity regime can be 

achieved at all four of the locations in the vicinity of Violet. All locations are therefore 

identical with respect to benefits.

Additionally, significant reliance on the implementation of other authorized projects is 

inconsistent with the risk-aware planning framework for this study. Sensitivity analyses 

indicate that without the implementation of other planned freshwater diversions, 

specifically the Convent/Blind River and Hope Canal/Maurepas Swamp River 

Reintroduction projects, only partial restoration of the salinity regime can be 

accomplished without the implementation of freshwater reintroduction as part of this plan 

or under the WRDA 2007 Section 3083 authority. 

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; 

• 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. 
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Restoration Plan 2-77 June 2012

Four sites on the east bank in St. Bernard Parish were evaluated as potential diversion 

locations. These sites are located between the Inner Harbor Navigation Canal and the 

community of Poydras. Generally open land corridors between the river and the Forty 

Arpent Levee were identified. Other locations in the area were not considered because of 

existing residential development (i.e. the Lower 9th

Four alternative locations for a freshwater diversion located at or near the existing Violet 

Canal were evaluated to convey water from the Mississippi River to the Lake Borgne 

ecosystem. The diversion sites in the Violet vicinity considered are: 

 Ward, Arabi, Chalmette, etc.), 

existing industrial development (Domino Sugar, Port of St. Bernard, refineries, etc.), and 

cultural resources (Chalmette National Historic Battlefield and Cemetery). 

• Alternative Location 1 – Located at approximate Mississippi River Mile 86 in St. 

Bernard Parish on an open parcel of land called the Sinclaire Tract in the 

community of Meraux. 

• Alternative Location 2 – Located at approximate Mississippi River Mile 85 in St. 

Bernard Parish on an open parcel of land between the communities of Meraux and 

Violet.

• Alternative Location 3 – Located at approximate Mississippi River Mile 84 in St. 

Bernard Parish at the existing Violet Canal.

• Alternative Location 4 – Located at approximate Mississippi River Mile 82 in St. 

Bernard Parish on an open parcel of land between the communities of Violet and 

Poydras.

The Violet, Louisiana Freshwater Diversion is proposed to extend from the Mississippi 

River and Tributaries (MRT) Levee at the river to the Forty Arpent levee via a controlled 

conveyance channel. A gated structure would be built at the river to allow flow through 

the MRT levee into a conveyance channel leading to a structure at the Forty Arpent 

Canal. The proposed river diversion channel would flow out through the Central

Wetlands to an outfall structure in the Chalmette Loop Levee and discharge through a 

structure into the MRGO. Openings to adjacent channels in the Central Wetlands would 

provide the freshwater and nutrients required to maintain the restored cypress swamp. If 

needed, a structure at the Back Dike Canal would maintain shallow draft navigation in 

the Central Wetlands above and below the new diversion channel. The diversion design 

includes a closure structure on Lake Borgne at Dupre Cut. The structure would be open 

to shallow draft navigation and would function to better conduct the freshwater via the 

MRGO. Freshwater would filter through adjacent marsh channels to the greater Lake 

Borgne ecosystem. 

Violet, Louisiana Freshwater Diversion Flow Analysis

The Salinity Working Group for the MRGO study noted that a target line and frequency 

need to be established to design a freshwater diversion, but that adaptive management 

should also be a component of freshwater reintroduction plans. Therefore, the metric for 

achieving the salinity regime objective is whether salinity falls within the optimal range 

each month, at least forty percent of the years in a decade, as described in Chatry et al. 

1983. The Chatry targets are a way to measure the restoration of historic salinity regimes. 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-78 June 2012

Hydrodynamic modeling evaluated a variety of discharge scenarios between 1,000 and 

30,000 cfs. A variety of diversion alternatives between 5,000 and 10,000 cfs were found 

to be effective in meeting this goal. At 5,000 cfs, the target is met in the range of 32 

percent to 36 percent. At 7,000 cfs alternatives range between 32 percent and 48 percent. 

At 10,000 cfs the range in meeting the Chatry targets is from 38 percent to over 50 

percent. 

Assuming that the Maurepas Swamp diversions are operated to maintain salinities below 

1 ppt, the 1,000/7,000 cfs proposed Violet, Louisiana Diversion meets the Chatry target 

32 percent of the time. 

With a constriction at Dupre Cut, the 1,000/7,000 cfs diversion lowers salinity to meet 

the target 37 percent. 

When the Convent / Blind diversion is increased to a constant 3,000 cfs or the proposed 

Violet Diversion is increased to flow 7,000 cfs year round, the Chatry target is met 43 

percent of the time. 

Table 2-20: Diversion Scenarios: Percent of Time Salinity Targets are Met 

(40 Percent Minimum to Achieve Objective)

Flow 

(cfs) Historic Baseline

FWOP Scenarios FWP Scenarios***

FWOP* FWOPD** A1 A2 A3 A4 A2D A4D

0 3.9% 6.1% 27.4% 33.7% 

1,000 26.7%

5,000 33.7%

7,000 31.7% 36.7% 43.6% 43.0% 48.1%

10,000 41.6% 46.2% 

15,000 55.2%

20,000 63.3%

30,000 75.4%

NOTES: 

Alternative

Gap between MRGO and Lake Borgne 

- Open or Closed Diversions at Maurepas Swamp

A1 Open < 1ppt

A2 Closed < 1ppt

A3 Open < 1ppt

A4 Closed < 1ppt

A2D Closed 4,500 cfs

A4D Closed 4,500 cfs

*FWOP indicates future without project conditions with Maurepas Swamp salinities maintained below 1 ppt. 

** FWOPD includes the selected alternative for the Blind River Diversion, which is a constant 3,000 cfs flow.

***See below for FWP Scenarios
Chapter 2 Alternative Formulation

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Restoration Plan 2-79 June 2012

Hydrodynamic modeling performed for the study indicates that based on average 

conditions, the diversion would need to be operated at 1,000 cfs for the majority of the 

year with a 7,000 cfs pulse beginning mid-April and continuing through May to achieve 

the salinity targets and habitat goals for the study. Because “average” conditions very 

rarely occur in nature, the freshwater diversion is planned to be adaptively managed to 

respond to actual environmental conditions. When measured salinity is at or below target 

levels, the diversion flow amounts could be reduced accordingly; when salinity readings 

are high, the diversion flow could be increased. Particularly, the flow of the Pearl River 

and rainfall levels need to be monitored and responded to in operations planning and 

execution. Other potential issues that need to be considered in the development of a 

detailed operations plan include: localized flooding in the portion of the Central Wetlands 

between the Forty Arpent Levee and the Chalmette Loop Levee; drastic changes in 

volume of water on a month to month time frame; observed adverse or beneficial 

ecological impacts; and weather events such as tropical systems, cold fronts, and rainfall 

events.

Use of the Existing Violet Canal

Some stakeholders have expressed a preference for a diversion that can be located in the 

existing Violet Canal. On May 4, 2010, the St. Bernard Parish Council adopted 

Resolution SBPC #637-05-10 stating that the St. Bernard Parish Government, in 

conjunction with the St. Bernard Parish Coastal Zone Advisory Committee, is “fully 

supportive of the restoration of the Central Wetlands area of St. Bernard Parish, but 

unanimously opposes another canal being dug to deliver the freshwater that can be 

delivered by using the existing conveyance and delivery canal.” To address these 

concerns, the capacity and benefits of the existing canal were investigated to determine 

what benefits could be achieved. 

Based on preliminary analysis, the implementation of the proposed 1,000/7,000 cfs 

freshwater diversion, independent of other restoration measures, is anticipated to produce 

14,637 net acres of wetlands at the end of 50 years. A diversion operating at 1,000 cfs 

constant flow would produce 7,323 net acres over the same period of analysis. The 

addition of a 2,000 cfs pulse in April and May would increase the benefits in net acres by 

1,594 acres, for a total of 8,917 net acres. 

The MIKE21 modeling conducted for this study indicates that a 1,000 cfs diversion 

would influence salinity in the Central Wetlands. A 1,000 cfs diversion, along with the 

introduction of dredged material could maintain salinities below 2 ppt throughout the 

subunit most of the time. Higher salinities would occur locally during periods of high 

inflow with a 1,000 cfs diversion. A smaller diversion would have some benefits outside 

of the Central Wetlands by adding nutrients, freshwater, and suspended solids into the 

ecosystem. However, the ability to significantly regulate salinity with a 1,000 cfs 

diversion would be limited to the Central Wetlands. The restoration of cypress swamp in 

all of the areas proposed may not be possible due to the uncertainties associated with 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-80 June 2012

increasing salinities during periods of high inflow of saltier water into the Central 

Wetlands.

Achievement of the salinity targets is anticipated to increase commercial harvests of 

oysters in the Biloxi Marsh, white shrimp, blue crab, croaker, menhaden, and catfish 

(USACE 1984). Diversions that do not include a 7,000 cfs or greater pulse in April and 

May would not achieve the targets, and therefore would not produce the same benefits to 

commercial and recreational fisheries. Smaller diversions would not restore salinity 

conditions in the Lake Borgne estuary, and would not mimic the natural overbank 

flooding of the Mississippi River. Additionally, a smaller diversion would not provide 

opportunities for adaptive management to restore and maintain the habitat type 

objectives. For these reasons, smaller diversions located in the existing Violet Canal will

be further investigated in the feasibility phase of analysis with appropriate NEPA 

documentation. 

Violet, Louisiana Freshwater Diversion Site Evaluation

As part of the preliminary alternatives analysis, four alternative locations were evaluated 

in the vicinity of Violet. These sites are numbered 1 to 4 from north to south moving 

downriver. Locations 1, 2, and 4 are located in undeveloped areas. Location 3 is the 

existing Violet Canal. Because hydrodynamic modeling indicates that all of the locations 

would produce the same benefits, the locations were evaluated to determine differences 

in potential costs and impacts. 
Chapter 2 Alternative Formulation

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Restoration Plan 2-81 June 2012

Figure 2-12: Alternative Locations for the Violet, Louisiana Freshwater Diversion 

Considered in Initial Analysis

Eleven site selection factors to consider in evaluating the potential diversion locations. 

These factors are identified in table 2-21. Each of the factors was identified to help 

highlight significant considerations for site comparison including sizing, costs, impacts, 

and construction considerations. A GIS system was used to overlay diversion footprints 

between the river and the MRGO within each of the four corridors. Using the GIS 

system and field observations, each of the factors was identified and the results were 

tabulated for comparison of the preliminary alternative locations. 

Table 2-21: Alternative Violet, Louisiana Freshwater Diversion Location Comparison

Site Selection Factor Alternative 1 Alternative 2 Alternative 3 Alternative 4

Number of Businesses, Residences and 

Secondary Structures (Relocations)

0 1 121 0

Number of Scenic Streams 0 0 4 2

Number of Roads 2 2 10 2

Wetland Acres (acres) 227 267 738 836

Number of Levees 2 2 4 2

Number of Cultural and Historic 

Resources

0 1 3 2

Docks/Maritime Infrastructure 0 0 7 1

Utilities & Pipelines 2 2 4 5

Diversion Channel Length (miles) 4.19 4.32 5.53 6.27
Chapter 2 Alternative Formulation

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Restoration Plan 2-82 June 2012

Table 2-21: Alternative Violet, Louisiana Freshwater Diversion Location Comparison

Site Selection Factor Alternative 1 Alternative 2 Alternative 3 Alternative 4

Community Facilities 0 1 1 0

Number of Bridge Replacements 0 0 1 0

Alternative Location 1 (figure 2-13) was preliminarily considered to be the best 

hydraulic location for the freshwater diversion, because it is the shortest, most-efficient 

route to the MRGO; however, the diversion will be further investigated in the feasibility 

phase of analysis with appropriate NEPA documentation. The distribution of freshwater 

throughout the Central Wetlands is more efficient at this location because it is centrally 

located. Alternative 1 also has the fewest wetland impacts of all four locations and may

not involve any potential cultural or historic resources.

Figure 2-13: Alternative Location 1

Alternative Location 2 (figure 2-14) is a comparable hydraulic location to Alternative 

Location 1. However, Alternative 2 would impact historic oak trees and a pecan grove. 

The pecan grove includes an area designated for local schools to use as an outdoor 

learning center, and therefore impacts business and community facilities. Alternative 2 

also has greater wetland impacts than Alternative 1. Because Alternatives 1 and 2 are 

hydraulically similar, and Alternative Location 1 has less wetland impacts and no 

cultural/historic or community impacts, Location 2 was removed from further 

consideration. 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-83 June 2012

Figure 2-14: Alternative Location 2

Alternative Location 3 (figure 2-15) is the site of the existing Violet Canal. The use of 

this site would require the relocation of approximately 121 structures. Alternative 3 has 

the greatest potential impacts to businesses, homes, scenic streams, roads, bridges, levees, 

cultural and historic resources, docks and other maritime infrastructure. The existing 

Violet Canal site would impact 738 acres of wetlands, and is over a mile longer than 

Locations 1 and 2. Despite these potential impacts, this location was retained for further 

evaluation with Alternative Location 1, due to stakeholder interest. 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-84 June 2012

Figure 2-15: Alternative Location 3

Location 4 (figure 2-16) is the longest route, and the land between the Mississippi River 

and the Forty Arpent Levee is at a higher elevation than at the other locations, which 

would require the largest structures of all four locations. Additionally, distribution to the 

northern portion of the Central Wetlands would be difficult from this location. 

Alternative 4 would require the largest structures due to its location on the river. 

Alternative 4 has the greatest potential impacts to existing wetlands, utilities and 

pipelines. The site includes in-river maritime infrastructure used for docking vessels that 

support the Military Sealift Command. Therefore, Location 4 was removed from further 

consideration. 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-85 June 2012

Figure 2-16: Alternative Location 4

A preliminary alternative analysis was conducted using a 15,000 cfs diversion size to 

determine if the existing Violet Canal (Location 3) or Alternative Location 1 would be 

the best site for the proposed freshwater diversion. Preliminary analyses indicated that an 

approximately 15,000 cfs freshwater diversion would be needed to restore the salinity 

regime for the area. Although subsequent hydrodynamic modeling conducted for this 

study indicates that a 7,000 cfs diversion would be sufficient to achieve the targets in 

average conditions, in order to account for the effects of drought and RSLR, the design 

capacity of the diversion is actually larger than 7,000 cfs. Therefore, the use of 15,000 

cfs in this screening analysis is sufficient to determine the scale of design differences 

between the two sites. This initial analysis concluded that Alternative Location 1 was 

preferable to the use of the existing canal for a number of reasons. 

Violet, Louisiana Freshwater Diversion Preliminary Capacity Evaluation

From the preliminary analysis, it was indicated that the Violet Canal location would 

require a 50-foot wider and 1-foot deeper channel than Alternative Location 1. In 

addition, the outflow channel length for the Violet Canal site is over a mile longer; 

therefore, dredging quantities, impacts to existing marsh, and costs would be greater than 

Alternative Location 1. In this preliminary analysis, the structure size for Alternative 

Location 1 was four 35-foot x 15-foot box culverts in comparison to four 40-foot x 15-

foot box culverts for Location 3. A culvert is a conduit used to enclose a flowing body of 

water and allow water to pass underneath a road, railway, or embankment, such as a 

levee. The findings of the more detailed design for the preliminary site i.e. Alternative 

Location 1 and volume, which considered increased RSLR indicate that the difference 

between the designs for the two locations would be even greater. 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-86 June 2012

Data Report for Violet Canal Freshwater Diversion and Mississippi River Gulf Outlet 

Water Control Structure analyzed 2,000 cfs, 5,000 cfs and 10,000 cfs diversions at the 

Violet Canal site (LDNR, 1996). This report found that a 5,000 cfs diversion would 

require additional dredging of the existing canal and the 10,000 cfs diversion would 

require significant dredging of the existing canal. The channel sizes used to develop 

quantities for the 10,000 cfs diversion in the 1996 report are smaller than the calculated 

quantities for the recommended plan diversion because the 1996 report did not consider 

RSLR or the ability to achieve the salinity targets for the study at least 40 percent of the 

time. Considering these factors, a significant widening of the existing channel would be 

necessary to convey the required diversion flows. The existing canal is approximately 

100 feet wide on average. In order to convey the required flows, the channel would need 

to be widened to 500 feet at the bottom, resulting in a top width of nearly 600 feet. 

Because the Violet Canal would require larger structures, a longer channel, and multiple 

relocations, the cost of constructing the freshwater diversion at this site appears to be 

considerably more than Alternative Location 1. There appear to be no additional 

environmental benefits associated with the use of the existing canal. Because the same 

restoration outputs can be produced with fewer impacts and lower costs at Alternative 

Location 1, the use of the existing canal is not the most cost-effective or efficient location 

to site the freshwater diversion. 

Violet, Louisiana Freshwater Diversion Recommendations

The Violet, Louisiana Freshwater Diversion is an important component of the plan to restore 

historic salinity conditions and provide freshwater and nutrients to nourish existing and 

restored wetlands in the study area. 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, 

design and implementation of the Violet, Louisiana Freshwater Diversion under and in 

accordance with its authorization in WRDA 2007 Section 3083. 

Environmental Impacts Analysis

Based on all of the preliminary analysis performed for the Violet, Louisiana Freshwater 

Diversion, the Alternative Location 1 shown in figure 2-17 was considered the best 

hydraulic location; however, the diversion will be further investigated in the feasibility 

phase of analysis with appropriate NEPA documentation. For the purposes of impact 

analysis for this FEIS, the footprint for the Alternative Location 1 was utilized. In order 

to run the models, such as CASM, to develop the potential impacts and benefits of the 

overall project, parameters for the diversion had to be established and utilized. 

Therefore, in the chapter 4 impacts analysis for each environmental resource, the 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-87 June 2012

parameters of Alternative Location 1 for the Violet, Louisiana Freshwater Diversion were 

used. 

2.6.2.2 Alternative B - MRGO Restoration Plan 2

Alternative B would restore approximately 54 acres of ridge habitat along Bayou La 

Loutre in the Biloxi Marsh area, provide 122 acres of shoreline protection, create and 

nourish 10,319 acres of cypress swamp habitat in the Central Wetlands, and create and 

nourish 19,630 acres of wetlands in the Lower Pontchartrain sub-basin. The freshwater 

diversion, pulsing 7,000 cfs from April to May would influence approximately 115,078 

acres. Reference figure 2-18 for alternative B features. The diversion channel at 

Alternative Location 1 would result in the permanent loss of 302 acres of prime/unique 

farmland and 227 acres of wetland. Restoration of the ridge would result in permanent 

impacts to 54 acres of wetland. A description of the restoration measures proposed for 

this alternative are included in appendix U, along with the preliminary engineering 

footprints for each individual measure. 

2.6.2.3 Alternative C - MRGO Restoration Plan 7

Alternative C would restore approximately 54 acres of ridge habitat in the Biloxi Marsh 

area, provide 1,937 acres of shoreline protection, create and nourish 10,318 acres of 

cypress swamp habitat in the Central Wetlands, and create and nourish 44,188 acres of 

wetlands in the Lower Pontchartrain sub-basin. The freshwater diversion, pulsing 7,000 

cfs from April to May would influence approximately 115,078 acres. The diversion 

channel at Alternative Location 1 would result in the permanent loss of 302 acres of 

prime/unique farmland and 227 acres of wetland. Restoration of the ridge would result in 

permanent impacts to 54 acres of wetland. Reference figure 2-19 for alternative C 

features. A description of the restoration measures proposed for this alternative are 

included in appendix U, along with the preliminary engineering footprints for each 

individual measure. 

2.6.2.4 Alternative D - MRGO Restoration Plan 10

Alternative D would restore approximately 54 acres of ridge habitat in the Biloxi Marsh 

area, provide 2,494 acres of shoreline protection, create and nourish 10,318 acres of 

cypress swamp habitat in the Central Wetlands, and create and nourish 44,892 acres of 

wetlands in the Lower Pontchartrain sub-basin. The freshwater diversion, pulsing 7,000 

cfs from April to May would influence approximately 115,078 acres. The diversion 

channel at Alternative Location 1 would result in the permanent loss of 302 acres of 

prime/unique farmland and 227 acres of wetland. Restoration of the ridge would result in 

permanent impacts to 54 acres of wetland. Reference figure 2-20 for alternative D 

features. A description of the restoration measures proposed for this alternative are 

included in appendix U, along with the preliminary engineering footprints for each 

individual measure.
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-88 June 2012

Figure 2-17: Alternative Location 1 for the Violet Freshwater Diversion
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-89 June 2012

Figure 2-18: Alternative B – MRGO Restoration Plan 2
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-90 June 2012

Figure 2-19: Alternative C – MRGO Restoration Plan 7 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-91 June 2012

Figure 2-20: Alternative D – MRGO Restoration Plan 10
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-92 June 2012

2.7 EVALUATION OF ALTERNATIVE PLANS

The evaluation of effects, or comparison of the future without-project and with-project 

conditions for each alternative, is a requirement of NEPA and Engineering Regulation 

(ER) 1105-2-100. The evaluation was conducted by assessing or measuring the 

differences between each without- and with-project condition and by appraising those 

differences. The evaluation consisted of four general tasks described below: 

1. Forecast the most likely with-project condition expected under each alternative 

plan, 

2. Compare each with-project condition to the without-project condition and 

document the differences between the two, 

3. Characterize the beneficial and adverse effects by magnitude, location, timing and 

duration, and 

4. 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 National Ecosystem Restoration, 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 also be evaluated based on CE/ICA and 

significance of ecosystem outputs must be determined. Display of the environmental 

quality account is required for this study using a minimum of two categories of effects: 

costs and ecosystem restoration outputs. 

MRGO Ecosystem project was evaluated first by individual measures. Then plans were 

combined based on cost effectiveness. Three plans were selected as the final array of 

plans for further evaluation. The final three plans were evaluated by a combination of 

measures within a subunit for each of the three final array plans. There were five 

subunits including A-Biloxi, D-Central Wetlands, E-East Orleans Landbridge, F-Terre 

aux Boeufs, and H-Hopedale. The subunits that are influenced by the diversion (ABiloxi, D-Central Wetlands, and E-East Orleans Landbridge) were evaluated with the 

diversion. There were a total of 74 WVA evaluations completed to date (see table 2-22

for final array of WVA results).

Habitat acreage, shoreline erosion, and interior marsh loss rate data were obtained from 

the USGS. WVA projections were made by members of the HET, which included 

representatives of the CEMVN, USFWS, OCPR, Department of Commerce – National 

Marine Fisheries Service (NMFS), NRCS, and Louisiana Department of Wildlife and 

Fisheries (LDWF). Prior to making those projections, HET members made onsite field 

inspections in June and October 2009. 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-93 June 2012

Table 2-22: Final Array of WVA Results

Feature AAHU*

Net 

Acres 

(TY50)

TY1 

Acres 

FWOP

TY1 

Acres 

FWP

TY50 

Acres 

FWOP

TY50 

Acres 

FWP

Alternative B – MRGO Restoration Plan 2

A-Biloxi 11.7 +19 58 61 43 62

D-Central Wetlands 7,365.6 +9,543 16,324 18,212 11,841 21,384

E-East Orleans Landbridge 4,419.1 +6,138 44,750 42,282 33,016 39,154

F-Terre aux Boeufs 1,811.8 +3,358 9,651 10,459 6,923 10,281

Total Alternative B 13,608.1 +19,058 70,783 71,014 51,823 70,881

Alternative C – MRGO Restoration Plan 7

A-Biloxi 1,948.6 +3,013 56,237 55,930 42,602 45,615

D-Central Wetlands 7,463.4 +9,543 16,324 18,218 11,841 21,384

E-East Orleans Landbridge 5,120.1 +7,546 48,570 42,788 36,323 43,869

F-Terre aux Boeufs 3,043.6 +5,566 10,823 10,846 7,763 13,329

H-Hopedale 164.3 +299 1,363 1,365 1,064 1,363

Total Alternative C 17,575.7 +25,967 133,317 129,147 99,593 125,560

Alternative D – MRGO Restoration Plan 10

A-Biloxi 2,018.6 +3,197 56,749 57,239 42,848 46,045

D-Central Wetlands 7,616.7 +9,543 16,324 18,217 11,841 21,384

E-East Orleans Landbridge 4,408.9 +7,699 48,570 29,102 36,323 44,022

F-Terre aux Boeufs 2,907.8 +5,566 10,823 10,846 7,763 13,330

H-Hopedale 164.3 +299 1,363 1,365 1,064 1,363

Total Alternative D 17,116.3 +26,304 133,829 116,769 99,839 126,144

*AAHUs are based on individual plan measures within five planning units.

Field data, results from similar projects in the area, SBEACH models, and hydrologic 

models were used in conjunction with the above-discussed mathematical models to 

compute a HSI value for each target year (TY). Target years were established when 

significant changes in habitat quality or quantity were expected during the 50-year period 

of analysis, under FWP and FWOP conditions. 

The product of an HSI and the acreage of available habitat for a given target year is 

known as the HU. The HU is the basic unit for measuring project effects on fish and 

wildlife habitat. Future HUs change according to changes in habitat quality and/or 

quantity. Results are annualized over the period of analysis to determine the AAHUs 

available for each habitat type.

The change in AAHUs for each FWP scenario, compared to FWOP project conditions, 

provides a measure of anticipated impacts. A net gain in AAHUs indicates that the 

project is beneficial to the habitat being evaluated; a net loss of AAHUs indicates that the 

project is damaging to that habitat type. In determining FWP conditions, all projectrelated direct (construction) impacts were assumed to occur from TY1 through TY10 for 

marsh restoration and nourishment, TY1 through TY5 for the Violet, Louisiana

Freshwater Diversion, and TY1 for shoreline protection and the ridge. 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-94 June 2012

Using the WVA methodology, impact assessments were conducted by the HET for the 

Final Array of Alternative Plans with the resulting benefits shown in table 2-11. 

Alternative C is estimated to produce the greatest benefit to habitat based on the highest 

valued of AAHUs (17,575.7) compared to alternatives B and D. Over a 50-year period, 

TY50, 25,967 acres of additional habitat is anticipated under alternative C (FWP) 

compared to TY50 FWOP conditions. Based on this initial WVA analysis, alternative C 

was deemed the best alternative that would produce the greatest benefit to fish and 

wildlife resources.

Once a best alternative determination was made, the CASM was run to model the effect 

of the tentatively selected plan on fisheries productivity. The CASM was run on the 

diversion flow regime which was a component of all the action alternatives and therefore, 

did not influence the selection of the tentatively selected plan. 

2.7.1 Risks and Uncertainties

Risk is the product of the likelihood of failure and its consequences. There are significant 

risks and uncertainties associated with all ecosystem restoration plans in the study area. 

The adaptive management plan will address specific risks and uncertainties associated 

with the implementation of the selected alternative, 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 (see appendix T). The following section describes 

major sources of risk and uncertainty and how they could impact each alternative 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. 

Approximately 52,480 acres of marsh were permanently or temporarily converted to open 

water in the study area following Hurricane Katrina, an area roughly equivalent to the 

amount of restoration proposed by the tentatively selected plan (Barras, 2009). There is a 

risk that a single storm event, or multiple storms in a short period of time, could 

significantly reduce or eliminate anticipated benefits of restoration plans in areas 

susceptible to storm surge and shearing. All of the features of the tentatively selected

plan (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 of risk and uncertainty. 

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 
Chapter 2 Alternative Formulation

FEIS MRGO Ecosystem

Restoration Plan 2-95 June 2012

dredged material in the study area could promote the natural recovery of areas affected by 

storms. The nutrients and suspended solids associated with the freshwater diversion 

would also assist in minimizing the adverse effects of storms to restored marsh. 

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 tentatively selected plan 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 

FWOP 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 
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Restoration Plan 2-96 June 2012

restoration plans. Proposed restoration features adjacent to open water are more 

susceptible to the effects of increased sea level rise than more interior areas.

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 

(see appendix T). 

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 riskaware 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 7 ppt following the closure of the MRGO. 

Coastwide Reference Monitoring Stations indicate that Central Wetlands salinity is lower 

than 4 ppt 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. 
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Restoration Plan 2-97 June 2012

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 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 for 

the majority of the plan.

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 2-23 evaluates the susceptibility of plan features to risks.

Table 2-23: 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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Restoration Plan 2-98 June 2012

Table 2-23: 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

All of the alternatives in the final array of alternatives are equally likely to be impacted 

by these risk factors. The relative risk of each alternative is based on the differences in 

consequences. Because it has the lowest benefits and costs, alternative A has the lowest 

risk. However, because alternative A involves no action, the ecosystem is more at risk 

under this scenario. Alternative B involves more risk than alternative A in terms of risks 

to benefits and investments, but risk to existing marsh and ecosystem function would be 

less than alternative A. Because alternative C has greater anticipated benefits and 

requires a larger investment than alternative B, the associated risks are greater. 

Conversely, because alternative C has greater benefits than alternatives A and B, the 

overall risk to the ecosystem is less than with alternatives A and B. Similarly, alternative

D involves more restoration features and greater benefits in critical landscape features 

than alternative C. Therefore, the risk of loss of benefits and investment is greater, but 

risk to ecosystem form and function is reduced. 

2.7.2 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)
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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) 

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 2-24: Sustainability under Relative Sea Level Rise by Feature

Area ID Plans

Sustainability Factors

Elevation Score

FW 

Influence

Wave 

Energy

Natural 

Feature

East Orleans 

Landbridge

EM2 B, C (TSP), D N Y N Y 2 Good

EM3 C (TSP), D N Y Y Y 3 Very Good

EM4 C (TSP), D N Y N Y 2 Good

EM1 B, C (TSP), D N N N Y 1 Fair

EM5 D N N N Y 1 Fair

ES1 C (TSP), D N N N N 0 Poor

ES2 C (TSP), D N N N N 0 Poor

ES3 C (TSP), D N N N N 0 Poor

EV1 D N N N N 0 Poor

MRGO

MRGO1 B, C (TSP), D N N N N 0 Poor

MRGO2 B, C (TSP), D N N N N 0 Poor

MRGO3 B, C (TSP), D N N N N 0 Poor

MRGO4 B, C (TSP), D N N N N 0 Poor

MRGO5 B, C (TSP), D N Y N Y/N 1.5 Fair/Good

MRGO6 B, C (TSP), D N N N N 0 Poor

MRGO7 B, C (TSP), D N Y N Y/N 1.5 Fair/Good

MRGO8 C (TSP), D N Y N Y/N 1.5 Fair/Good

South Lake 

Borgne

LM1 B, C (TSP), D N Y N Y 2 Good

LM2 B, C (TSP), D N Y N Y 2 Good

LM3 B, C (TSP), D N Y N Y 2 Good

LM4 C (TSP), D N Y Y Y 3 Very Good

LS1 C (TSP), D N N N N 0 Poor

tral 

Wet

landCC1 –

CC6

B, C (TSP), D Y Y Y Y 4 Excellent
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Restoration Plan 2-100 June 2012

Table 2-24: Sustainability under Relative Sea Level Rise by Feature

Area ID Plans

Sustainability Factors

Elevation Score

FW 

Influence

Wave 

Energy

Natural 

Feature

CM1-

CM5

C (TSP), D N Y Y Y 3 Very Good

Terre aux 

Boeufs

TM1 B, C (TSP), D N N Y Y 2 Good

TM2 B, C (TSP), D N N Y Y 2 Good

TM7 C (TSP), D N N Y Y 2 Good

TM8 C (TSP), D N N Y Y 2 Good

HM1 C (TSP), D N N Y Y 2 Good

Biloxi 

Marsh

BR1 B, C (TSP), D Y Y Y Y 4 Excellent

BS1 C (TSP), D N N N N 0 Poor

BS2 C (TSP), D N N N N 0 Poor

BS3 D N N N N 0 Poor

BM1 C (TSP), D N Y N Y 2 Good

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 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 2-25

provides a summary of how each alternative plan meets the study objectives. 
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2.9 IDENTIFICATION OF THE TENATIVELY SELECTED

PLAN

The tentatively selected plan is the NER plan as determined by the evaluation criteria 

discussed in section 2.7. The CASM Model is a tool in determining the effects of the 

plan on fisheries productivity. Once the tentatively selected plan was determined, the 

CASM was run on the diversion flow regime, which was a component of all the action 

alternatives and therefore, did not influence the selection of the tentatively selected plan. 

The NER plan reasonably maximizes environmental benefits while passing tests of cost 

effectiveness and incremental cost analyses, significance of outputs, acceptability, 

completeness, efficiency, and effectiveness. WRDA 2007 requires the plan to be cost 

effective, environmentally acceptable, and technically feasible in order to be carried out 

by the Secretary of the Army. Additional factors to consider include the involvement of 

other agencies and the reasonableness of costs.

Alternative C is the tentatively selected plan and NER plan for this study because it is the 

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

storm surge benefit objective. Other plans were evaluated that provide additional 

benefits, but the increases in costs were not considered reasonable given the relative 

outputs. Alternative C is cost-effective, and maximizes the opportunities to achieve the 

objectives of the study for the least cost. The incremental costs associated with 

alternative C are considered reasonable for the significance of the outputs achieved. 

The anticipated outputs of the tentatively selected plan would help address the current 

trend of degradation of the Lake Borgne ecosystem, support Nationally significant 

resources, provide a sustainable and diverse array of fish and wildlife habitats, provide 

infrastructure protection, and make progress towards a more sustainable ecosystem. 

Table 2-25: Comparison of Alternatives to Study Objectives

Objective Alternative A Alternative B Alternative C Alternative 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

6. Ridge Habitat No Yes Yes Yes

7. Landscape Features for

Surge Reductiona No

Yes

5,100 acres

Yes

20,523 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.
Chapter 2 Alternative Formulation

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Restoration Plan 2-102 June 2012

The implementation of the tentatively selected plan is anticipated to restore significant 

ecosystem function, structure, and dynamic processes through a comprehensive systemsbased approach. The tentatively selected plan would restore unique habitat in a 

nationally significant watershed. The costs associated with the tentatively selected plan

are significant, and would represent a continuing national commitment to the protection 

and 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 tentatively selected 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 (EO) 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 estuarinedependent 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 EFH. By letter dated October 27, 2008, the 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 

tentatively selected plan include those found in the Bayou Sauvage National Wildlife 

Refuge and the Pearl River and Biloxi Wildlife Management Areas (WMA). 

In October 2009, President Obama formed the Louisiana-Mississippi Gulf Coast 

Ecosystem Restoration Working Group, co-led by the White House CEQ and the Office 

of Management and Budget (OMB) and comprising senior-level officials from the 
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NOAA, the 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. 

2.9.1 Description of the Tentatively Selected Plan

The tentatively selected plan (alternative C) would restore 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. Alternative C includes approximately 71 miles of shoreline 

protection. These acreage values are based on WVA results, which take into account 

marsh creation behind the shoreline protection features. 

Approximately 10,221 acres of the restoration and protection features would be located in 

the East Orleans Landbridge/Pearl River area and approximately 9,861 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. 

Further analysis and implementation of a freshwater diversion in the vicinity of Violet is 

a key component of the tentatively selected plan. The freshwater diversion is a system 

driver to create conditions conducive to the full restoration of historic salinity levels in 

the vicinity of the MRGO. The Violet, Louisiana Freshwater Diversion would mimic 
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Restoration Plan 2-104 June 2012

natural processes and enhance the sustainability of the system through the input of 

freshwater, nutrients, and sediment. 

Below is a summary of the construction techniques that would be used for each 

restoration component. Specific construction and implementation information for each 

proposed restoration site is included in appendix U on the engineering footprints for each 

feature.

2.9.1.1 Marsh Restoration 

A hydraulic dredge would be used to discharge slurry into shallow water areas and 

degraded marsh areas. Material would be obtained from study area borrow sites as noted 

for each feature. Slurry would be discharged to an elevation conducive to the 

development of wetlands habitat following dewatering and compaction. It is anticipated 

that the final result of this dredge material placement would be a combination of 

wetlands, mud flat, and shallow water habitat within the placement site. Following 

compaction and dewatering, the area would be planted with marsh vegetation appropriate 

for the site.

In general for marsh restoration, it was assumed that existing elevations within the marsh 

restoration site average -0.5 foot and that adjacent marsh is approximately +1.5 feet. 

Maximum slurry elevation would be +4.0 feet. Retention dikes and interior weirs were 

included where needed. Dikes would be constructed from adjacent borrow and would be 

at +6.0 feet with a 5-foot crown width and 1 vertical on 3 horizontal side slopes and a 40-

foot interior berm. Interior weirs will be built from adjacent borrow to an elevation of 

+3.0 feet with a 5-foot crown width and 1 vertical on 3 horizontal side slopes. In some 

cases, closures comprised of either adjacent earthen borrow material, sheet pile or stone 

may be required in order to retain the dredged slurry. 

Earthen dikes/closures would be allowed to degrade naturally. If earthen dikes/closures 

do not sufficiently degrade to provide fisheries and tidal ingress/egress following 

appropriate settlement of dredge material placed within the disposal area, earthen 

dikes/closures would be mechanically breached and/or degraded within three years of 

construction, as necessary. 

Canal Closures

An earthen plug would be constructed in the canal utilizing sediments from the canal. 

The earthen plug would serve to prevent the flow of sediment laden water from the 

dredging activity to flow outside of the designated area of impact. The method for 

plugging canals would be the same for marsh nourishment as well as swamp restoration 

and nourishment features.
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Interior low-level earthen weirs may be constructed within the marsh restoration areas to 

facilitate sediment deposition to enhance wetlands development. Borrow material for 

weir construction would be taken from within the restoration area. Earthen 

dikes/closures would be allowed to degrade naturally. If earthen dikes/closures do not 

sufficiently degrade to provide fisheries ingress/egress and tidal exchange after settlement 

of dredge material, earthen dikes/closures would be mechanically breached and/or 

degraded within three years of construction, as necessary.

Weirs

Planting Plan

Below is a summary of the planting plan for the marsh restoration features. Refer to 

appendix Z. 

Fresh and Intermediate Marsh 

Location within the marsh depends on their ability to withstand depth and length of 

flooding. The CWPPRA estimate for vegetative planting is 625 plants/acre planted on 8-

foot center on rows 8 feet apart. Some are available commercially and can be 

propagated. 

Some of the dominant marsh plants in freshwater and intermediate wetlands are: 

maidencane (Panicum hemitomon), bull tongue (Sagittaria lancifolia), giant cutgrass 

(Zizaniopsis miliacea) California bulrush (Schoenoplectus californicus), coast cockspur 

(Echinochloa walteri), marsh-hay cordgrass (Spartina patens), and Common reed 

(Phragmites australis). 

Brackish Marsh 

CWPPRA estimate for vegetative planting is 875 plants/acre planted on 7-foot centers on 

rows 7 feet apart. Some are available commercially and can be propagated. Species 

usually dominant in a brackish marsh are: marsh-hay cordgrass (Spartina patens), 

saltgrass (Distichlis spicata), American bulrush (Schoenoplectus americanus), black 

needle rush (Juncus roemerianus), seashore paspalum (Paspalum vaginatum), and 

switchgrass (Panicum virgatum). The low marsh is typically dominated by (Spartina 

alterniflora). 

2.9.1.2 Marsh Nourishment 

For marsh nourishment it was assumed that existing marsh is between +0.5 foot and 1.0 

foot and fill would be to +2.0 feet. Retention dikes and interior weirs were included 

where needed. Dikes would be constructed from adjacent borrow and would be at +6.0 

feet with a 5-foot crown width and 1 vertical on 3 horizontal side slopes and a 40-foot 

interior berm. Interior weirs will be built from adjacent borrow to an elevation of +3.0 

feet with a 5-foot crown width and 1 vertical on 3 horizontal side slopes. In some cases, 

closures comprised of either adjacent earthen borrow material, sheet pile or stone may be 

required in order to retain the dredged slurry. 
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Dredged material would be obtained from study area borrow sites as noted for each 

feature. The elevation of marsh nourishment areas varies from +1.0 foot to +1.5 feet. 

Material would be allowed to overflow existing emergent marsh vegetation and into 

waterbodies within the project boundaries; some shallowing of these features would be 

anticipated.

Unlike marsh restoration features, no plantings are associated with marsh nourishment 

features. Dikes/closures would be allowed to degrade naturally and would be breached 

and/or degraded within 3 years following construction to provide fisheries access if they 

do not sufficiently degrade following settlement of dredged material. 

2.9.1.3 Swamp Restoration 

Swamp restoration is proposed in shallow water areas that were historically cypresstupelo swamps. Swamp restoration consists of pumping dredged material from borrow 

areas, as noted for each feature, to a maximum elevation of +4.5 feet within containment 

dikes. Swamp restoration areas would be planted with cypress trees.

The construction of swamp restoration features is similar to marsh restoration features as 

described above. In general, for swamp restoration an existing average elevation of -1.0 

foot to -3.0 feet was assumed based on the bathymetry available with an adjacent marsh 

elevation of +1.5 feet. The maximum slurry elevation would be +4.5 feet and effluent 

would be discharged on adjacent swamp/marsh lands for nourishment. Retention dikes 

would be constructed where needed. Dikes would be constructed from adjacent borrow 

to an elevation of +6.5 feet with a 5-foot crown width and 1 vertical on 3 horizontal side 

slopes and a 40-foot interior berm. In some cases, closures comprised of either adjacent 

earthen borrow material, sheet pile or stone may be required in order to retain the dredged 

slurry. Dikes would be allowed to degrade naturally and would be breached and/or 

degraded within three years following construction to provide fisheries access if they do 

not sufficiently degrade following settlement.

General Operations Scheme

The Violet diversion presents the opportunity to aid in reestablishment of natural 

hydrologic cycles conducive to bald cypress and tupelo establishment, growth, and 

reproduction. The Coastal Wetland Forest Conservation and Use Science Working 

Group (CWFCU-SWG) was commissioned by the Governor of Louisiana with the 

mission “to provide information and guidelines for the long-term utilization, 

conservation, and protection of Louisiana’s coastal wetland forest ecosystem, from both 

environmental and economic perspectives” (CWFCU-SWG, 2005). The subsequent 

research, findings, and recommendations are invaluable tools when determining 

conditions needed for establishment, growth, and reproduction of bald cypress swamp 

and were incorporated in determining the operational scheme. The general operations 

scheme is presented in appendix M. 

 
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Adaptive management for (1) habitat switching; and (2) pulsing to reach target salinity. 

1. No pulsing in the first 2 years to 3 years to achieve habitat switching and allow 

cypress seedlings time to establish. 

2. After first 2 years to 3 years, ramp up pulsing from few days – one week pulse 

toward a two week pulsing cycle (cycle includes maximum pulsing of no more 

than 2 weeks with 2 weeks of no flow between pulses) to achieve target salinity. 

3. Every 3 years to 5 years a drawdown should be initiated to elevation -4.0 feet to -

6.0 feet below surface beginning in March for cypress regeneration. After seed 

fall to achieve successful reestablishment of cypress, the area should not be 

flooded (soils saturated but no water above the -4.0 feet elevation) during growing 

season (March – November) for the next two growing seasons. 

4. After drawdown, flows should be introduced slowly – not more than +2.0 inches 

initially and gradually increasing over the year not to exceed +8.0 inches by the 

end of that growing year. 

5. Flows for months other than pulsing or drawdown months would be at a level to 

achieve fresh wetlands (0 ppt to 0.5 ppt mean growing season March to 

November) with a maximum peak of 2 ppt or less. 

Planting Plan

Below is a summary of the planting plan for the swamp restoration features. Refer to 

appendix Z. 

Construction of cypress swamp habitat would begin at the completion of the Violet 

Diversion. An average of 200 bald cypress per acre with 75 percent bare-root seedlings 

or saplings and 25 percent container-grown would be planted from October through 

March. All of the cypress trees would have a nutria protection device. Threes would be 

monitored monthly for survivorship and replaced as necessary. 

Initially the diversion would operate at a reduced level for the first two to three years 

after swamp plantings to allow for establishment and habitat switching. Every three to 

five years, a drawdown should be initiated in March, after seed fall and dispersal, to 

approximately four to six inches below swamp surface. The drawdown should continue 

through the growing season until November to aid in reestablishment. 

2.9.1.4 Swamp Nourishment 

Swamp nourishment is proposed for areas that are currently at marsh elevation, and 

consists of placing a layer of dredge material to nourish the area, raise elevation to 

approximately +2.0 feet, and encourage the recruitment of cypress-tupelo community 

species. The depth of dredged material would be determined on a site-by-site basis to 

adjust for varying topography. 
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2.9.1.5 Shoreline Protection 

These features consist of either foreshore (shore between high water and low water) rock 

dikes or rock dikes placed near the existing shoreline to dissipate wave energy before it 

reached the shoreline. Foreshore rock dikes would be constructed by placing rock in a 

linear mound at the -1.5 foot to -2.0 feet depth contour, to a height above the water’s 

surface. 

Shoreline protection designs were based on designs for existing features constructed in 

similar locations. The work consists of protection on the north and south banks of the 

MRGO, the shore of Lake Borgne, the Biloxi Marsh, the East Orleans Landbridge, and 

other areas as shown on the engineering footprints in appendix U. 

Work along the banks of the MRGO consists mainly of repairs to existing foreshore 

dikes. Existing dikes would be brought up to elevations range from +3.0 feet to +6.0 feet

depending on the location. Crown widths range from 4 feet to 5 feet. For areas with no 

existing dike a concrete panel wall to elevation +4.0 feet was assumed. 

Protection along the Biloxi Marsh consists of a stone dike constructed of 5,000 pound 

stone with a crown width of 8 feet to 10 feet and a top elevation of from +4.0 feet to +8.0 

feet. Gulf-side slope would be 1 vertical on 3 horizontal and land side slop would be 1

vertical on 2 horizontal. To minimize subsidence, the dike section would be underlain 

with a 2-foot crushed stone blanket. 

Protection along Lake Borgne consists of a rock dike to elevation +4.0 feet with a crown 

width of 4 feet and 1 vertical on 2 horizontal side slopes. The dike would be constructed 

on geotechnical filter fabric to minimize settlement.

Protection along the East Orleans Landbridge would consist of a rock foreshore dike 

constructed to a crown elevation of +3.5 feet with a 5-foot crown and 1 vertical on 2 

horizontal side slopes. The dike would be constructed on a layer of geotextile fabric to 

minimize settlement.

Based on recommendations from the USFWS, the shoreline protection features would 

include fish dips in the final design. Fish dips are breaks or low points in the shoreline 

protection feature, which allow aquatic organisms to access the marsh habitat behind the 

rock features. This exchange is important for both spawning and feeding of numerous 

aquatic species. The fish dips would be included every 1,000 feet, with a 25-foot bottom 

width set to the pre-project water bottom elevation. The 1,000-foot spacing would be 

adjusted based on existing exchange points, as well as coordinated consulting with the 

NMFS.

Oyster Reefs 

Oyster larvae develop a shell and feed on algae, drifting on currents and riding the tide. 

By the third week, they attach themselves to a hard surface - usually other oysters - here 
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Restoration Plan 2-109 June 2012

they transform into a tiny oyster called spat and bond with others to form a reef. As 

oyster reefs decline larvae have less of a chance of finding a suitable surface. Globally, 

scientists estimate an 85 percent loss of native oyster reef habitat.

Oyster reefs are the ecosystem engineers of bays and estuaries. They provide important 

services to people and nature by improving water quality through filtering impurities 

from the water, providing food and habitat for a variety of marine and estuarine fish and 

invertebrates and providing a natural coastal buffer. 

The plan is to create 30,750 linear feet (5.8 miles) of potential artificial oyster reef 

development on the Chandeleur Sound side of the Biloxi Marsh from Eloi Point to the 

south side of the mouth of Bayou La Loutre. There would be three sections: 1) loose 

shells; 2) interlocking triangular structures; and 3) concrete rings, each 2.5 miles long 

with the loose shells in the middle. The purpose of this demonstration measure is to 

determine which oyster reef alternative is the most beneficial to oyster production over 

time.

Oyster Reef Alternatives

Loose Oyster Shells

Using loose oyster shells would mimic the natural process of oyster production. Two and 

a half miles of reef would be created. Shells should be stacked within approximately 3 

feet of water to a height of approximately 3-4 feet and a width of approximately 10 feet. 

Shells may be mixed with riprap or contained in mesh bags. If contained in mesh bags, 

approximately 56,000 bags will be needed and stacked with a 4 bag base, 2 bag middle 

base and single bag top layer. If mixed with riprap, the configuration would be a 1 part 

riprap to 2 parts oyster shells at the same height and width as the bags. Figure 2-21 

depicts the Oyster Reef Alternative – Loose Oyster Shells.

Figure 2-21: Oyster Reef Alternative - Loose Oyster Shells
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Restoration Plan 2-110 June 2012

Interlocking, Triangular Welded Steel Structures

Interlocking triangular structures made of welded steel with space for mesh bags of 

oyster shells,– a technique proven to be highly successful in a Nature Conservancy 

project in Texas, is one alternative to construct 2.5 miles of oyster reefs within the project 

area. Once in place, these artificial reefs come alive as oyster larvae attach to the 

structures and grow. To create a reef of 2.5 miles approximately 1,500 units (steel 

triangles with each side approximately 3 feet long x 2 feet high x 1 foot wide) and 

approximately 1,200 cubic yards recycled oyster shell would be placed in approximately

3 feet of water. Figure 2-22 depicts the Oyster Reef Alternative – Interlocking, 

Triangular Welded Steel Structures.

Figure 2-22: Oyster Reef Alternative - Interlocking, Triangular Welded Steel 

Structures
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Restoration Plan 2-111 June 2012

Interlocking Concrete Rings

These interlocking concrete rings (5 feet in diameter) use the same concept as the 

triangular welded steel structures. These are designed specifically for the soft substrate 

of Louisiana's coast (www.nature.org). Concrete rings with oyster shells show 

significantly more success than simply plain concrete rings (Dehon, 2010). To create 2.5 

miles of reef, three rows would be placed approximately 1 foot from each other within 

approximately 4-5 feet of water. Figure 2-23 depicts the Oyster Reef Alternative – 

Interlocking Concrete Rings. 

Figure 2-23: Oyster Reef Alternative - Interlocking Concrete Rings

2.9.1.6 Ridge Restoration 

A ridge restoration feature is proposed on the south side of Bayou La Loutre. Restoration 

would consist of the placement of dredged silty sand material to be obtained from the 

Mississippi River. The initial elevation of the ridge would be approximately +8 feet, 

with a crown width of 25 feet and 1:8 side slopes. The base width of the ridge would 

vary, with an average width of approximately 120 feet. A 50-foot access corridor on the 

south side would be designated for construction equipment. Access along Bayou La 

Loutre may require excavation to the channel’s authorized depth. If excavation is 

required material excavated for floatation would be placed in the footprint of the 

proposed ridge restoration work. The ridge would be planted to develop forested habitat 

as described in the planting plan for this study (appendix Z).

Planting Plan

Based on the ongoing studies and evaluation of current projects, the following guidelines 

have been developed. A layered, phased approach may be the most suitable to help 

stabilize the ridge, promote growth of the different tree stories, and create habitat for 

neotropical migrant birds. 
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Restoration Plan 2-112 June 2012

Side slopes of the ridge affected by tides would be seeded for critical area cover and/or 

planted with herbaceous species in much the same manner as above based on salinity and 

depth of flooding. Plantings on the bayou-side of the ridge should mimic the pattern 

outlined for shorelines with no protection while behind the ridge would be planted as 

applicable marsh is.

Side slopes of the ridge not affected by the tides as well as the ridge top are suitable for 

midstory/shrub-scrub species such as wax myrtle (Myrica cerifera), groundsel bush 

(Baccharis halimifolia), marsh elder (Iva frutescens), and yaupon (Ilex vomitoria). These 

would aid in stabilization and provide needed habitat for neo-tropical migrants. It is 

suggested to plant bare-root seedlings with typically 200 to 300 plant/acre density. Other 

woody species such as red mulberry (Morus rubra), hackberry/sugarberry (Celtis laevigata), 

California desert-thorn (Lycium carolinianum), and green ash (Fraxinus pennsylvanica) 

could also be used on the high side slopes. 

Hardwoods should be planted on upper sides of the ridge slopes and the ridge top. 

Several species typically grow on ridge tops based on studies of cheniers, dredge material 

banks, and a few natural ridges left in the deltaic plain. Hardwoods such as live oak

(Quercus virginiana), sugarberry (Celtis laevigata), dwarf palmetto (Sabal minor), and 

red cedar (Thuja occidentalis) would likely be suitable for high ridge planting. Seedlings 

should be planted on 8-foot by 8-foot spacing totaling about 680 trees/acre. Chinese 

Tallow control would be included in operations and management. 

2.9.1.7 Access Corridors 

Access corridors for construction equipment and dredge pipeline are depicted in the plan 

view for each feature (appendix U). Access corridors would be a maximum of 

approximately 350 feet in width and would cross over wetlands and shallow water as 

necessary. Access corridors for some features may occur across existing levees and 

different methods would be utilized to best prevent compromise of the levee while 

allowing access. The level of protection provided by these levees would be maintained 

throughout construction, and any damage to levee vegetation would be repaired upon 

removal of the construction equipment. The construction or designation of staging areas 

would be necessary for construction equipment; however, they have not been identified at 

this time. At the point when staging areas are identified, if they do not fall within the 

area assessed for project impacts, a supplemental NEPA document would be required 

prior to construction. 

Where access corridors cross existing wetlands, board roads would be utilized for 

equipment and pulling pipe. Upon completion of construction, the wetlands impacted by 

the board roads would be restored by dredge material. It is anticipated that a thin layer of 

dredged slurry would overflow and nourish adjacent marsh.
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2.9.1.8 Flotation Access Channels 

Flotation access channels would be excavated, as needed, in shallow water areas to allow 

construction equipment to access the project features. If necessary, flotation access 

channels would be excavated by a mechanical dredge. It is estimated that access

channels would average approximately -2 feet. Flotation access channel material would 

be used in dike/closure construction or refurbishment, to backfill flotation access 

channels, or would be placed adjacent to and behind the dikes and closures in shallow 

water to a maximum initial elevation conducive to wetlands development following 

consolidation of the material. Flotation access channel material used to backfill the 

flotation access channels following completion of disposal work would be temporarily 

stockpiled on the water bottom adjacent to the flotation access channel. 

If existing canals are used for access, they may be dredged to facilitate flotation of 

pipeline and other necessary equipment from the dredging reach to pipeline discharge 

sites within the designated staging areas. Dredge material removed from existing canals 

would be placed on adjacent existing levees and/or into shallow water on either side of 

canals. Canal dredge material placed in shallow water areas would be placed to a height

conducive for wetlands development. 

2.9.1.9 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 salinity conditions or other factors to be sustainable. 

Tier 1 features are recommended for construction. 

• 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 3 includes further study of the Violet Freshwater Diversion, features 

dependent on freshwater diversion, and features in Tier 2 that further analyses 

indicate favorable conditions for ecological success and long term sustainability 

do not exist. 

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 7 ppt following the closure of the MRGO. 

Coastwide Reference Monitoring Stations indicate that Central Wetlands salinity is lower 
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FEIS MRGO Ecosystem

Restoration Plan 2-114 June 2012

than 4 ppt 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 TSP, 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 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 appendix U, 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 

appendix U. 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. 
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Restoration Plan 2-115 June 2012

Increased Relative Sea Level Rise

A detailed WVA analysis of the three relative sea level rise scenarios was performed for 

the TSP. Table 2-26 below shows the net acres projected under each of the three relative 

sea level rise scenarios based on feature locations. 

Table 2-26: Robustness of Features in TSP under all Relative Sea Level Rise Scenarios*

 

Features

LOW RSLR MEDIUM RSLR HIGH RSLR

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 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 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 TSP 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.
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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 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 Freshwater Diversion as authorized by WRDA 2007 Section 

3083 is the highest priority for Tier 3, because all of the features included in this tier 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.

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. An initial adaptive increment of cypress restoration would be constructed in the 

Bienvenue Triangle area for monitoring and adaptively management. The knowledge 

lessons learned from this initial adaptive increment will be applied to future cypress 
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Restoration Plan 2-117 June 2012

restoration projects. Additionally, there are some uncertainties regarding the potential 

water quality impacts of dredging in Lake Borgne. The MAMP outlines a monitoring 

program to reduce uncertainties and apply knowledge gained to future projects. 

The MAMP for this study has developed decision criteria, also referred to as AM 

triggers, to determine if and when AM opportunities should be implemented. These 

criteria are described below and are based on the monitoring of indicators. 

Table 2-27: Adaptive Management Threshold and Trigger Matrix

Indicator Threshold

Ecological Success 

Criteria Response Options

Salinity

Threshold set by 

Snedden and Steyer, in 

review

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, Bonnet Carré 

Spillway, Small Diversion at 

Convent Bline 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 TBD

Evaluate options for increasing 

freshwater input and hydrologic 

restoration measures such as bank 

gapping and salinity barriers.

The plan includes an implementation sequence that was used to help in the assessment of 

wetlands benefits and that is based upon performance support logic. The implementation 

sequence provides a time scale of when projects would be constructed and is based upon 

assumptions about ecological conditions, construction capabilities, and performance 

assurances. Assumptions factoring into the sequence include elements such as production 

rates for building rock projects and issues like dredge equipment availability for use in 
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Restoration Plan 2-118 June 2012

marsh creation. Other implementation sequencing factors include considerations such as 

land loss rates, required construction work order, and ecosystem drivers. 

Table 2-28 provides brief description of each restoration feature included in the 

tentatively selected plan and proposed implementation approaches. 

Table 2-28: Implementation Table

Measure

1

Description

TIER 1 RECOMMENDED FOR CONSTRUCTION

(CONTINGENT UPON IDENTIFICATION OF NON-FEDERAL SPONSOR)

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.

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.
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Measure Description

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

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

Tier 3A

VIOLET The Violet Freshwater Diversion as authorized in WRDA 2007 Section 3083. A freshwater 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.
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Measure Description

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.

Figure 2-24 illustrates the tentatively selected plan timetable.
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Figure 2-24: MRGO Tentatively Selected Plan Implementation Timetable
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2.9.1.10 Borrow Sites

The tentatively selected plan would restore and/or protect approximately 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. The implementation of 

the tentatively selected plan would require a significant amount of sediment. Figure 2-25 

illustrates the proposed borrow site for each feature included in the tentatively selected

plan. 

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, 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 jeopardize the continued existence of species 

listed as endangered or threatened under the Endangered Species Act or resutls in the 

likelihood of destruction or adverse modification of critical habitat. Lake Borgne includes 

some sandy bottoms that are the preferred foraging habitat for these species. These areas 

were surveyed and excluded from consideration as potential borrow sources.

The proposed borrow plan is detailed in figure 2-25. As the borrow plan depicts, 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), as well as to 

avoid existing oyster leases to the maximum 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 environmental or 

cultural resources are discovered during construction that require avoidance. Borrow 

areas would be designed to minimize hypoxic (lack of dissolved oxygen) formation by 

minimizing the depth of the dredge cut to the maximum extent practicable. In addition, 

adaptive management and monitoring would be utilized to minimize any potential 

hypoxic formation as described below. 
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Figure 2-25: Borrow Sites for Tentatively Selected Plan
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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 implementation plan actually spans 14 years with a 

monitoring period in place for two years after test borrow pits are dredged. A cycle does 

not necessarily last for 365 days and some features could take 12 to 16 months to 

complete. The borrow plan limits dredging to one lobe of Lake Borgne per 

implementation cycle, therefore isolating increased turbidity to one lobe of the lake. A 

minimum of 365 days of dredging would occur in one lobe before switching to the other 

lobe. 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. The availability of 

borrow material associated with the phased borrow plan has dictated the construction 

implementation schedule for the restoration features that were previously depicted in 

table 2-28. 

To ensure that water quality is not sacrificed within Lake Borgne, MVN has included two 

years of water quality monitoring into the proposed action. Three test borrow pits would 

be constructed in implementation cycle number 1. The first pit would be constructed to 

15 feet deep below the water surface, the second pit would be constructed to the proposed 

depth of 20 feet deep below the water surface, and a third pit would be constructed to 

approximately 25 feet deep below the water surface. These three test borrow pits would 

impact approximately 2,191 acres of water bottom in Lake Borgne. After the borrow pits 

are constructed, monthly water quality monitoring would be used to determine if hypoxia 

formation was occurring within the borrow pits. Once the two years of monitoring is 

complete, the remaining borrow pits would be adjusted to ensure that hypoxia formation 

would not result within the remaining borrow pits. The MVN believes that the design of 

the borrow pits, coupled with the proposed water quality monitoring, would ensure that 

the proposed action would only temporarily impact the water quality of Lake Borgne. 

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 re-colonization of muddy-sand substrate that 

would assist in future assessments of impacts to Gulf sturgeon prey items.
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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

Legally, it is unclear whether dredging the MRGO channel for non-navigation purposes 

is contrary to the Congressional intent. However, 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). 

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 PDT analyzed MRGO as a borrow option for marsh creation features. Using the 

channel could supply <10 percent of the identified 150+ mcy of sediment need for the 

entire tentatively selected plan. Dredging the channel would provide some cost savings 

(estimated at -$20 million) over the Lake Borgne option. As illustrated above, MRGO 
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dredging for borrow is a publicly sensitive issue that was adamantly opposed in some 

scoping comments. 

Consultation with NMFS on the critical habitat impacts is being conducted. The USACE

BA determined there to be no likelihood of destruction or adverse modification of critical 

habitat for the Gulf sturgeon. The plan that is presented may be further refined as a result 

of this consultation. 

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 feet by 500 feet with a 1 foot over-depth, approximately 15.5 mcy 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). The 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 by the majority of the PDT, 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. 

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 
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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 (Thomson, 2010). 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. 

2.10 ADAPTIVE MANAGEMENT

Section 2039 of WRDA 2007 directs the Secretary of the Army to ensure that, when 

conducting a feasibility report for a project (or component of a project) for ecosystem 

restoration, the recommended project includes a plan for monitoring the success of the 

ecosystem restoration. The implementation guidance for Section 2039, in the form of a 

CECW-PB Memo dated 31 August 2009, also requires that an adaptive management plan 

(see appendix T) be developed for all ecosystem restoration projects. It is recommended 

that adaptive management be conducted substantially in accordance with the 

recommendations made in the MRGO Ecosystem Restoration Plan Feasibility Report. 

The adaptive management plan for the selected alternative addresses the potential 

impacts of increased SLR rates (see appendix T). The implementation plan provides 

opportunities for adaptive management by constructing marsh restoration features with 

the lowest land loss rates first. If SLR increases in the initial implementation phase, the 

plan can be assessed for potential adjustments to changing conditions. This strategy 
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allows for the initial investment to be made in features expected to retain benefits for the 

longest period. 

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 (MSL). 

Coastal marshes may accrete at a rate that keeps pace with a slow rate of SLR; however, 

as the rate of SLR increases, coastal mashes cannot maintain their elevation, and they 

submerge and are transformed to open water. Some Louisiana marshes are able to 

survive current SLR conditions; increased SLR 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 RSLR in 

managing, planning, engineering, designing, constructing, operating, and maintaining 

USACE projects. The National Research Council’s (NRC’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 RSLR for both “with” 

and “without” project conditions as shown in table 2-29. 

Table 2-29: 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.

Under the medium and high scenarios, the cost-effectiveness of all of the action plans 

would decrease significantly. To maintain the level of benefits projected for the historic 

rate for the medium and high scenarios, additional lifts and maintenance of restoration 

features would be required, significantly increasing the costs of the alternatives. The 

alternative to increased maintenance would be significantly reduced benefits. 

2.11 ENVIRONMENTAL COMMITMENTS

Measures developed during alternative formulation were designed to first avoid adverse 

environmental effects and where adverse effects could not be avoided they were 

minimized to the greatest extent possible. 
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Section 2039 of WRDA 2007 directs the Secretary of the Army to ensure that, when 

conducting a feasibility report for a project (or component of a project) for ecosystem 

restoration, the recommended project includes a plan for monitoring the success of the 

ecosystem restoration. The implementation guidance for Section 2039, in the form of a 

CECW-PB Memo dated August 31, 2009, also requires that an adaptive management 

plan be developed for all ecosystem restoration projects (see appendix T). 

Throughout the planning process, efforts were made to avoid impacts to the extent 

practicable. The tentatively selected plan would impact approximately 227 acres of 

intermediate marsh and shallow open water that would be excavated for the outfall 

channel. However, restoration of approximately 17,352 acres of marsh habitat, 

nourishment of 26,836 cumulative acres of emergent marsh habitat, and restoration of 54 

acres of ridge habitat would mitigate for wetland impacts resulting from construction 

activities.

Best management practices would be included in construction specifications and they 

would be employed during construction activities to minimize environmental effects. 

Many of these best management measures are required by Federal, state, or local laws 

and regulations, regardless of whether they are specifically identified in this document or 

not. Project implementation would comply with all relevant Federal, state, and local 

laws, ordinances, regulations, and standards during the implementation of the preferred 

alternative. Implementation of the environmental commitments would be documented to 

track execution and completion of the environmental commitments. 

A summary of the environmental and related commitments made during the planning 

process and incorporated into the proposed project plan are listed below: 

1. Ensure construction contractors limit ground disturbance to the smallest extent 

feasible. 

2. Use accepted erosion control measures during construction. 

3. Use board roads where dredge pipelines or equipment would cross existing marsh.

4. Conduct a search for bald eagle, other raptors and colonial nesting wading bird 

active nests within three-quarter of a mile from proposed disturbance activities 

prior to construction. Appropriate protective measures and no-work distance 

restrictions would be implemented to avoid or minimize nest disturbance if active 

nests are identified. 

5. Contact pipeline and gas well companies prior to construction activities to 

identify and avoid existing hazards. 

6. Implement best management practices and measures contained in erosion control 

guidelines to control soil erosion from construction areas. 

7. Implement measures to control fugitive dust during construction. 

8. Implement a program to compensate for losses of archaeological sites (if any) that 

would occur as a result of construction and operation of the proposed project. 

9. All retention dikes constructed for marsh creation/restoration features would 

contain an opening of at least 100 feet in width and have a depth as deep as the 
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deepest natural entrance into the disposal site in order to accommodate the escape 

of protected species.

10. Ensure construction contractors are educated on the Marine Mammal Protection 

Act of 1972 (MMPA) and the Endangered Species Act (ESA) and the species of 

concern.

11. Conduct a search for coastal bottlenose dolphins, sea turtles, and Gulf sturgeon 

within marsh creation/restoration sites. Appropriate best management practices 

(BMP) would be implemented to avoid or minimize potential entrapment of these 

protected species. These BMPs are included in detail in the contract and include 

the following: 

a. Observe the area to be enclosed for protected species at least 24 hours prior to 

and during closure of any levee, dike or structure. This is best accomplished 

by small vessel or aerial surveys with at least two experienced marine 

observers on board scanning for protected species. 

b. If any protected species are sighted within the area to be enclosed all 

appropriate precautions shall be implemented by the Contractor to ensure 

protection of the animal. These precautions shall include avoiding direct 

contact with and not feeding the protected species. 

c. Any sightings of protected species within an enclosed project site shall be 

reported immediately to the COE.

d. If observers' note the animals are not leaving the area, but are visually 

disturbed, stressed, or their health is compromised then the COE may require 

any pumping activity to cease until the animals either leave on their own or 

are moved under the direction of NMFS. NMFS would then conduct any 

necessary measures (detailed in contract) to ensure protection of the species.

e. In addition to those environmental and related commitments, several 

construction technicians and visual monitoring would be undertaken to further 

protect any protected species in construction areas.

Chapter 6 also contains a detailed list of USFWS (Service) positions and 

recommendations that USACE concurs with (see section 6.6.1) as well as NMFS EFH 

conservation recommendations that the USACE concurs with (see section 6.9.1). 

2.12 MODEL DEVELOPMENT AND UNCERTAINTIES

2.12.1 Predicting Future Conditions

Predicting future conditions is in itself uncertain. As described in chapter 1, there are 

several important hurricane risk reduction projects currently under construction in the 

immediate project area. These levees and barriers individually and cumulatively are 

expected to have significant impacts on the future conditions of the area without 

implementation of this restoration study. Water quality monitoring conducted by USGS 

in the MRGO channel just prior to construction of the closure structure and after 

construction commenced indicate the system is in a state of flux and trying to establish a 

new equilibrium. Once the IHNC barrier is completed along with the other proposed 
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gated structures it is likely the system would continue to be in a state of flux trying to 

establish a new equilibrium for several years. Water quality monitoring conducted by 

USGS is indicating a reduction in salinity that would affect aquatic and fishery conditions 

in the FWOP conditions for this studied 50-year period of analysis. Because these 

conditions are in a state of flux it is difficult at this time to predict with accuracy what the 

future outcome would look like without this restoration plan. Important among the 

anticipated changes is the reduction in salinity levels in the area as demonstrated by the 

hydrologic modeling summarized in chapter 3. The boxes covering the Biloxi Marsh 

(13, 74, 78) indicate a salinity reduction by approximately 1-2 ppt. More in-depth 

discussions of the impacts are described further in chapter 4 for the applicable resources 

affected. 

In addition to construction of the HSDRRS projects, Section 7006 of WRDA 2007 

authorized feasibility studies for LCA near-term critical restoration features. Authorized 

near term projects in the Upper Pontchartrain Basin include a small diversion at Hope 

Canal; a small diversion at Convent/Blind River and Bank Gapping for Amite River 

Diversion canal. Authorized near term critical projects in the Lower Pontchartrain Basin 

includes re-authorization of Caernarvon Freshwater Diversion and a medium diversion at 

White’s ditch. As per WRDA 2007, Section 7006(e)(3) the Secretary of the Army 

submitted a favorable Report of the Chief of Engineers for the Convent/Blind River, 

Amite River Diversion Canal Modification and White’s Ditch projects on December 30, 

2010. The construction of the LCA restoration projects plays an integral part in 

predicting the future conditions of the MRGO ecosystem restoration study. The UNO 

box model demonstrates that with these restoration projects operating in the Upper 

Pontchartrain sub-basin, salinity conditions in the Lower Pontchartrain sub-basin achieve 

the Chatry targets in all months except May where it is met 33.7 percent of the time. The 

FWOP condition in which impacts are assessed in this EIS is based on the authorized 

LCA projects discharging a total of 4,500 cfs in the Upper Pontchartrain sub-basin. 

Without construction of one or all of these projects, the FWOP conditions were modeled 

to maintain a salinity level of <1 ppt in Maurepas. With this FWOP condition, the Chatry 

targets are still maintained 11 months of the year, except May where the Chatry target is

met 27 percent of the time.

Although numerous scientific studies have been conducted within the Louisiana coastal 

environments, considerable uncertainty remains regarding key ecological processes and 

the efficacy of some of the proposed restoration measures. Limitations in analytical tools 

to assess ecosystem responses also exist, and were compounded by the short timeframe in 

which the MRGO ecosystem restoration study was formulated. These limitations and 

uncertainties substantiate the value of a truly adaptive approach to the ecosystem 

restoration plan and suggest that some plan components, such as the freshwater diversion, 

may require further and more detailed study prior to implementation. Many details 

concerning the construction and operation of the diversion structure were unavailable at 

the time of this assessment. 

Some variation between forecast conditions and reality is without a doubt. The degree to 

which these variations affect planning decisions in this study may be offset by 
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recognizing the uncertainties and associated risks in the decision-making process. Large 

uncertainties such as climate change; SLR; subsidence; timing, frequency and intensity of 

tropical storm events and/or changes in drought conditions affect outcome of projections 

for future conditions. Each one of these factors, alone or in combination contributes to 

the degradation within the study area.

2.12.2 Uncertainties Related to 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 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 risks. 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.

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.

The first features proposed for implementation are in Tier 1 and include LS1, MRGO1 

and MRGO6 because these areas are critical for ecosystem structure (maintaining the 

MRGO landbridge), subject to high rates of erosion, in close proximeity to the MRGO, 

and are currently unprotected. The next features in Tier 1 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. 
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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 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.

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. 

2.12.3 UNO Mass Balance Model Uncertainties

Modeling efforts have uncertainties. The quantification, understanding, and 

minimization of these uncertainties are critical for the correct interpretation of model 

results. Uncertainty may arise in the input data, in the geometry of the model grid, and/or 

in the data used to verify and calibrate the model. 

Uncertainty in the input data results from having to define freshwater flows from the 

rivers and streams in the Pontchartrain Basin and along the Mississippi Coast. Input 

flows for the numerous ungaged areas were assumed to be similar to the input in the 

gaged areas. While this is a valid assumption, it adds some uncertainty to the model.

Uncertainties in the model geometry can be more significant than those in the input data. 

Large areas are approximated with an average depth and the boxes have an area for 

runoff and a contributing area for evaporation. All of these areas and depths are 

estimated based on the best available data.

Field data for calibration and validation can contribute the highest uncertainty to the 

modeling effort as data are critical in interpreting model results. Much of the data are 

spot data, and the exact time with respect to the tide and meteorological forcing is 

unknown. The ensemble of measurements was assumed to indicate average conditions. 

The UNO Mass Balance model had previously been validated for Lake Pontchartrain and 

Lake Maurepas, but was not validated for the Lake Borgne and Biloxi Marsh. The data 

was utilized to ascertain if the model reproduces seasonal trends. 

The calibration and validation process for the expanded model was not thoroughly 

undertaken due to the limited data; therefore, uncertainty in the model results exists. 

Based on the model calibration error of 17 percent, a standard error in the prediction of 
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Restoration Plan 2-134 June 2012

the salinity in any cell can be +/-17 percent. Despite the uncertainties, the UNO Mass 

Balance model is a good, efficient tool to investigate the impact of proposed diversions. 

2.12.4 Sediment and Nutrient Diversion (SAND2) Model 

Uncertainties

The combination of relative sea level rise and river/marsh disconnection has created a 

deficit of available soil and accompanying land loss in a large portion of coastal 

Louisiana. The Congress recently charged the USACE, State of Louisiana, and other 

Federal and local agencies with restoring the coastal wetlands of Louisiana and 

Mississippi. Many alternative combinations of restoration measures have been proposed, 

and assessment of the advantages and disadvantages of these efforts must be made to 

determine the optimal design. One technique being applied for coastal restoration is the 

reconnection of rivers to coastal marshes through flow diversions. 

Freshwater flow diversions offer significant nutrient and sediment inputs to marshes that 

induce both organic and inorganic accumulation of soil. Boustany (2007) presented a 

screening level model for assessing both the nutrient and sediment benefits of flow 

diversion over long time scales. 

As stated in section 2.10.2, given the short schedule the SAND2 model was utilized. The 

SAND2 version differs from the SAND1 model by incorporating an improved method for 

determined nutrient benefits, plus it includes the ability to capture diversion synergies 

with proposed marsh restoration measures constructed within the diversion benefit area. 

Given the great uncertainties regarding future subsidence rate changes, SLR changes, and 

many other factors that might affect future wetland loss rates over the period of analysis, 

there is considerable uncertainty regarding the accuracy of the predicted river diversion 

benefits. However, the SAND models do provide an objective means for comparing 

alternative measures and plans. 

The SAND2 model results are limited due to the exclusion of a variety of important 

system processes. Some of the major assumptions and limitations of the model were: 

 

• Benefits of flow diversion are independent (in reality the benefits are likely nonlinearly coupled due to vegetation inducing sediment deposition and 

sedimentation increasing suitable habitat for vegetation); 

• Nutrients serve as a reduction in land loss, not a source of land gain benefits 

(Deposition of particulate organic matter neglected); 

• Spatial uniformity – vegetation, roughness, bulk density, and other parameters are 

highly heterogeneous in coastal marshes; 

• Temporal resolution is only represented intra-annually, not continuously. 

Rectangular wetland geometry; 

• No vegetative component to settling/roughness; 

• Organic accumulation is not considered as a function of time even though 

biomass production is highly seasonal; 
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• No habitat switching with time; 

• Canals are not accounted for as a sediment loss mechanism; 

• Sheet-flow was assumed for all diversion flow rates; 

• No sediment re-suspension due to rainfall, tidal flows, waves, or hurricanes; 

• Uniform distribution of sedimentation; and 

• Nutrient recycling neglected. 

2.12.5 Wetland Value Assessment Model Uncertainties

The WVAs were initially run by groupings by geographic locations (Biloxi, East Orleans 

Landbridge, Central Wetlands, Terre aux Boeufs, and Hopedale). Preliminary WVAs 

were run on restoration measures based on the percentage of each feature within the 

larger group. The Final Array of alternative plans was evaluated with full WVAs. 

Additional information includes impacts to wetlands for the diversion footprint and 

access footprints for each measure and dredging capabilities (see below for details). 

Correlation and interactions between the restoration measures within each geographic 

location were based on the expertise and experience of the HET. For the initial 

geographic group of WVAs, the HET established dependencies on measures that 

influenced each other as follows: 

• Shoreline protection features were initially grouped with the adjacent marsh 

creation/nourishment features. 

• Further into the study, each feature was evaluated individually before alternative 

plans were combined. 

• Within the diversion influence areas the entire subunit with all its features were 

evaluated together.

• A simplifying assumption was made where shoreline protection measures 

protected portions of a marsh creation measure. Rather than determine actual 

interactions, the interacting shoreline protection and marsh creation measures 

were treated independently according to their respective protocols. The only 

exception to this was that of the MRGO Channel Narrowing measures, where

marsh creation measures along the MRGO are protected by concrete panels. For 

those measures, it was assumed that marsh creation measures reduced the loss of 

created marsh by 50 percent, and the shoreline protection measures reduced the 

remaining loss by 50 percent, resulting in a combined 75 percent reduction in 

FWOP loss (polygon40 – South Lake Borgne polygon). 

FWP analyses considered changes from processes such as equilibrium, storm events, and 

subsidence, and resulted in an overall change in the platform area or in the conversion of 

one WVA habitat type to another. Salinity was based on modeling results. Most 

subunits consisted of one major habitat type. Only Subunit 23 (Terre aux Boeufs) had 

two habitat types (saline and brackish); therefore, different WVA models were used to 

reflect the habitat difference. 

• Fresh/intermediate – average salinity during the growing season (March through 

November) 
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• Brackish and saline – average annual salinity

• Swamp – mean high salinity for March through October 

As part of the Corps certification process, the Wetland Value Assessment (WVA) Models 

were evaluated for their appropriateness of use in the Corps planning process. As a 

result, changes to the existing WVA marsh models were made. The changes primarily 

addressed concerns regarding how the existing WVA marsh models assigned greater 

habitat values to wetlands that had a greater amount of vegetated area. That assignment

of values is consistent with the authorization and goals of the CWPPRA program (i.e., 

restoration of vegetated wetlands) and is therefore appropriate for its evaluations. 

Revisions to the WVA marsh models were incorporated to reduce the degree of influence 

vegetated areas had on project benefits and to reflect the habitat values for most species 

utilizing all natural habitats within each marsh type. See appendix B for WVA 

assumptions. 

During the later stages of the MRGO project planning, these changes to the WVA models 

were applied to the final TSP WVAs. Since the new WVA models were applied to only 

the final TSP, a sensitivity analysis was run to determine if the changes in the model 

would have affected the outcome of alternative selection. Please see table 2-30. 

There were no apparent equivalent trends or relationships regarding the amount of change 

to calculated benefits (i.e., AAHUs) for each individual project feature resulting from the 

change in models. However, the relative degree of benefits produced (high, medium and 

low) by each project feature appeared to be generally consistent between the models. All 

three sea–level rise rates were evaluated using the revised WVA models and again, no 

equivalent changes were noted between the analyses. As previously seen, the relative 

degree of benefits appeared to be consistent. It is believed that individual site conditions 

(e.g., greater subsidence or shoreline erosion rates, etc.) for each project feature can 

produce differences between the models as well as the sea-level rise rates. Those 

individual site conditions can confound any predictions regarding specific definable 

differences in benefits calculated by the different models and those resulting from 

application of different sea-level rise rates. 
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Table 2-30: Wetland Value Assessment Sensitivity Levels

Final TSP 

Feb. 24, 2012

AAHU Low RSLR AAHU Medium RSLR AAHU High RSLR

Low 

New 

Certified 

WVAs

Low 

Original 

WVAs

Difference 

Old 

Minus 

New

% 

Difference

Medium 

New 

Certified 

WVAs

Medium

Original

WVAs

Difference 

Old 

Minus

New

% 

Difference

High 

New 

Certified

WVAs

High 

Original 

WVAs

Difference

Old 

Minus

New

% 

Difference

Inner Biloxi Marsh 1,684 1,591 -93 -5.9% 1,947 1,540 -407 -26.4% 401 434 33 7.7%

Bayou La Loutre 

Outer SP 0.5 0.3 -0.2 -53.2% 0.4 0.2 -0.2 -71.3% 0.2 0.1 -0.1 -50.7%

Bayou La Loutre 

Ridge 33 38 5 13.0% 34 40 5 13.3% 49 56 6 11.4%

Central Wetlands 

Marsh 5,275 6,231 956 15.3% 9,289 9,990 700 7.0% 8,934 8,753 -180 -2.1%

Central Wetlands 

Swamp 4,600 5,230 630 12.0% 4,843 5,398 556 10.3% 5,584 5,926 342 5.8%

Diversion Footprint 

Impacts -165 -134 32 -23.6% -155 -127 27 -21.3% -95 -72 22 -30.6%

East Orleans 

Landbridge 2,110 1,908 -202 -10.6% 1,612 1,300 -312 -24.0% 718 718 0 0.0%

Lower Pearl River 419 1,709 1,290 75.5% 505 1,492 987 66.1% 121 558 437 78.3%

Lower Lake 

Borgne Marsh 18,112 15,573 -2,538 -16.3% 18,034 14,935 -3,099 -20.8% 10,021 9,421 -599 -6.4%

Hopedale 176 468 292 62.3% 192 421 230 54.5% 70 196 125 64.1%

Inner Terre Aux 

Bouefs 1,595 3,277 1,681 51.3% 1,678 2,951 1,272 43.1% 519 1,189 670 56.3%

Total 33,839 35,891 2,052 6.0% 37,980 37,940 -41 -0.1% 26,322 27,179 856 3.0%
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Diversion

An operations plan for the diversion is not planned until the planning, engineering and 

design phase of the study is funded for construction. Without modeling the operations, 

assumptions were incorporated in the WVA modeling effort. The HET assumed that 

freshwater flows over 7,000 cfs would overwhelm the Central Wetlands and potentially 

result in flooding to Paris Road given the existing two structure openings at Bayou Dupre 

and Bayou Bienvenue. As a result, it was further assumed and demonstrated by the H&H 

Mike 21 model that not more than 1,000 cfs would flow through the Central Wetlands 

area. The effects of the diversion on the flooding of Paris Road are unknown, but 

assumed that as long as flows did not exceed 1,000 cfs in the Central Wetlands it may not 

be an issue. To control the pulsing diversion flows in the Central Wetlands, a water 

control structure would be built in the channel to regulate the height of the water in the 

Central Wetlands. It was assumed that existing openings would remain open and any 

structures constructed would be constructed to the same diameter and dimensions that 

currently exist. The WVAs would have to be re-evaluated if the assumption changes as a 

result of this method. 

Marsh Creation and Dredging

An implementation plan had not been developed at the time of the WVA; therefore, for 

purposes of the analysis, the HET incorporated dredge production in marsh creation, 

marsh nourishment, and swamp creation benefits developed from several scenarios. The 

details of these scenarios can be found in the WVA report located in appendix M. The 

HET assumed dredge production at 15,000 cubic yards per day and water depths based 

on engineering assumptions for each feature. The HET dredging scenarios provided by 

the engineers to determine annual wetland creation acreage and assumed that two dredges 

were operating year round. The HET prioritized wetland creation areas by subunit, based 

on subunit loss rates (low loss rate areas by subunit are constructed first, high loss rate 

areas last). It was further assumed that marsh and swamp creation would begin in 2015 

(TY1). 

At this stage of the feasibility report, marsh and swamp settlement curves were not 

prepared; therefore, it is assumed that enough borrow would be utilized to construct 

marsh and swamp features to a height conducive to sustaining these habitats. Without 

settlement curves, specific borrow quantities are based on previous projects and 

knowledge of the soil types where the features would be constructed. 

Marsh creation utilizes retention features to build up marsh to required elevation. In 

some cases, existing marsh or shoreline protection features would act as retention. 

Overflow from marsh creation would nourish surrounding existing marsh. After 

compaction and dewatering, containment features would be breached to allow exchange 

of materials. Breaching is assumed to occur in most cases within one year of 

construction unless naturally degrades on its own. 
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2.12.6 Land Change Uncertainties

In addition to sea-level rise, future climate change would influence the quantity and 

timing of freshwater delivery to coastal estuaries. Future changes in the flow regime of 

the Mississippi River are important considerations for the design and operation of river 

diversions to restore the coast of Louisiana. As indicated in Historical and Projected 

Coastal Louisiana Land Changes: 1978-2050, USGS (Barras et al., 2004), climate 

projections agree that precipitation regimes in the future would be characterized by more 

frequent high-intensity rainfall events and that runoff regimes would therefore become 

more intense. 

2.12.7 Comprehensive Aquatic Ecosystem Model (CASM) 

Uncertainties

By definition, simplifications and assumptions were necessary in developing the MRGO 

version of the CASM. Nevertheless, the resulting model successfully addressed the 

original modeling objectives. It is possible to use the current CASM MRGO to project 

the effects of freshwater diversions on modeled populations. One possible 

recommendation would be to accept the model in its current form. However, it would be 

possible to refine the model by revisiting some of its basic assumptions and making 

necessary modifications – assuming additional data might become available. The 

following recommendations are offered as possible improvements to the CASM MRGO: 

• Physical transport of dissolved and suspended constituents (e.g., nutrients, 

particulate organic carbon, plankton) can influence spatial-temporal patterns of 

productivity in hydrodynamically complex systems such as the MRGO 

ecosystem. Future refinements to the model could include more direct linking of 

a physical model to the CASM MRGO. The CASM has been integrated with the 

USACE Adaptive Hydrology Model (ADH) in separate applications for 

Navigation Pool 5 on the Upper Mississippi River (Bartell et al., in prep.) and the 

Caernarvon Diversion on the Lower Mississippi River (Savant et al., in prep). 

Similar integration may be possible to provide more realistic physical transport 

for the CASM MRGO.

• Additional spatial resolution could be incorporated to provide more accurate 

whole-system estimates of the potential effects of freshwater diversions on 

MRGO food webs. The model currently estimates these large-scale effects based 

on the 23 modeled locations, each multiplied by the surface area associated with 

the modeled location. Increased spatial resolution would likely result from more 

sophisticated coupling of the CASM MRGO to a physical model (e.g., ADH). 

• The modeled food web and associated bioenergetics parameters represents one 

hypothesis concerning ecological structure and function. The model reflects a 

preliminary consensus opinion concerning important populations of producers and 

consumers and realistic estimates of model parameters as determined by 

calibration. However, critical model parameters, for example, maximum growth 

rates and light saturation constants for phytoplankton, and maximum consumption 

and respiration rates for consumers (especially oysters, Gulf sturgeon), might be 
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Restoration Plan 2-140 June 2012

measured directly for the MRGO populations. In addition, key resource agencies 

(e.g., NMFS, USFWS, LDWF) recommended some changes to the trophic 

interactions currently specified in the model. For example, the model incorrectly 

specifies predation by Atlantic croaker on juvenile red drum, which is not 

supported by empirical analysis of local croaker diets. Concerns were also 

expressed regarding the effects of aggregating diverse zooplankton and 

zoobenthos communities into corresponding single modeled populations (i.e., 

“zooplankton, zoobenthos”) on model performance. Detailed 

sensitivity/uncertainty analysis of model results to current model assumptions 

regarding food web structure and input parameter values could help future 

structural revisions to the model and assist in the selection of key parameters to 

measure under field conditions.

• Reviewing resource agencies have identified potential revisions to the model in 

relation to spatial-temporal patterns of biomass production by certain modeled 

populations. For example, modeled Gulf sturgeon biomass appears greater than 

expected, given the listed status of this fish. Oyster production appears to be 

overestimated in the modeled portion of Lake Pontchartrain. In contrast, 

population production by several of the forage fish (e.g., striped mullet, Bay 

anchovy, Gulf menhaden) populations seem underestimated. Predation rates on 

these forage fish populations by other modeled fish populations may require 

additional review and revision. In addition, predation rates by higher trophic level 

fish (e.g., Atlantic croaker) on forage populations should be further examined; the 

absence of fishing mortality on Atlantic croaker and other fish populations might 

be overestimating the effects of predation on the forage populations. 

• The initial model results suggest that modifications of the spatial occurrences of 

some populations are required. For example, modeled population biomass values 

for Node 9 seem high, given that this node is largely terrestrial. Additionally, sea 

trout are not growing in model nodes 1-5, where observations and experience 

suggest otherwise. 

• The resource agencies also recommended that seasonal differences in the 

production of white shrimp and brown shrimp need to be further examined. The 

well-defined seasonal differences in the production of these species are not well 

reflected in the current simulations. Similarly, oyster spat and juvenile shrimp 

production should also demonstrate more pronounced seasonal pulses of biomass 

than in the current model results. 

• Evaluation and refinement of the environmental input factors based on additional 

data, if available, might further improve model performance. For example, in the 

absence of nutrient loading data and more sophisticated physical transport, daily 

concentrations of dissolved inorganic nitrogen, dissolved inorganic phosphorus, 

and silica (diatoms) provide initial conditions that influence phytoplankton 

growth. It might be possible to develop nutrient loading values based on more 

realistic models of flow in combination measured concentrations from major 

nutrient sources. Measured concentrations in the reservoir that currently drive the 

model could then be more properly used in refined calibration of the CASM 

MRGO or as additional indicators of overall model performance. 
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Restoration Plan 2-141 June 2012

• In response to agency review, the method for deriving the 55-year sequence of 

environmental input data should be further evaluated to determine if cyclic 

climate patterns relevant to the MRGO region can be more realistically 

represented. 

• One of the greatest limitations in evaluating current model performance is the 

comparative absence of benthic invertebrate and fish standing stock information 

for the MRGO ecosystem. 

Implementation of any or all of these recommendations can improve performance of the 

CASM MRGO. At the same time, specification of performance criteria would greatly 

facilitate further evaluation of the current model and guide any future refinements. In 

basic research, models are developed with the intent of falsifying them. Model failures 

generate new testable hypotheses that can advance science and in turn improve the 

model. In management, the contrasting emphasis is on model reliability within specified 

performance criteria. The question, “how good is good enough?” needs to be translated 

into objective performance criteria (i.e., model:data comparisons) that are usually based 

on some goodness of fit estimator. Development of such criteria for the CASM MRGO 

could improve the efficiency of continued model refinement and evaluation until the 

model is deemed adequate. Nevertheless, the recommended revisions to the model 

should be performed to the extent possible given time and resources. The FWOP and 

FWP scenarios should then be re-run with the revised model to (1) determine the 

significance of the model revisions on the preliminary CASM MRGO results used to 

develop the DEIS and (2) to provide more accurate model results to revise the DEIS as 

necessary.

2.12.8 Oil Spill Uncertainties

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

uncertain at this time. The impacts of the oil spill as well as the various actions taken to 

address oil spill impacts (e.g., use of oil dispersants, creation of sand berms, use of Hesco 

baskets, rip-rap, sheet piling and other actions) could potentially impact USACE water 

resources projects and studies within the Louisiana coastal area, including the MRGO 

Ecosystem Restoration project. Potential impacts could include factors such as changes 

to existing, future-without, and future-with-project conditions, as well as increased 

project costs and implementation delays. The USACE will continue to monitor and 

closely coordinate with other Federal and state resource agencies and local sponsors in 

determining how to best address any potential problems associated with the oil spill that 

may adversely impact project implementation. Supplemental planning and 

environmental documentation may be required as information becomes available. If at 

any time petroleum or crude oil is discovered on project lands, all efforts would be taken 

to seek clean up by the responsible parties, pursuant to the Oil Pollution Act of 1990 (33 

U.S.C. 2701 et seq.). 

The USACE, New Orleans District Regulatory Branch has considered and responded to 

approximately 58 emergency permits related to the Deepwater Horizon oil spill. The 

State of Louisiana received a permit to dredge and fill to construct a six sand berm 
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Restoration Plan 2-142 June 2012

reaches along the shoreline of the Chandeleur Islands/Breton National Wildlife Refuge 

westward to Baptiste Collette Bayou and along the seaward shoreline of Timbalier Island 

eastward to Sandy Pont. Material to construct the berms would be dredged from Ship 

Shoal, South Pelto, the Mississippi River Offshore Disposal Site, Pass a Loutre, St. 

Bernard Shoal and Hewes Point (see http://www.mvn.usace.army.mil/pao/mvnoilspill.asp

for information on permits issued within the MRGO study area). 

As is evident from the numerous ongoing actions, the dynamic nature of the impacts 

associated with the Deepwater Horizon oil spill will likely require additional 

consideration in the near future for USACE Civil Works projects. Potential impacts and 

affects are briefly described by environmental constraint below: 

• Hydraulics and Hydrology Modeling – No impacts to this resource have 

occurred within the project area from the oil spill and conditions will continue to 

be monitored. 

• Water Quality - There is the potential for contamination and decreased water 

quality from the oil and chemical dispersants. Tar balls, sheen, and heavy oil was 

reported in portions of Lake Borgne, the Western Mississippi Sound, Chandeleur 

Sound, and Breton Sound increasing the potential for decreased water quality and 

possible contamination in these portions of the project area 

(http://www.wlf.louisiana.gov/oilspill). Water quality testing in Lake Borgne and 

other areas is ongoing and these results will shed more light on to the level of 

possible contamination and impacts to water quality from the spill in the longterm. 

• Navigable Waterways – No navigable waterways were closed due to the oil spill 

and the only impacts included decontamination stations near the mouth of the 

River for all vessels entering the Mississippi River. 

• Soils - No impacts to this resource have occurred within the project area from the 

oil spill and conditions will continue to be monitored as circumstances change. 

• Air Quality - The oil spilled into the Gulf, and the dispersants sprayed on the oil, 

contain some chemicals that evaporate into the air and could be carried via the 

wind toward shore. The EPA has set up a network of stationary and mobile 

monitors along the coastline. If the winds shift or the oil moves, it may be 

expected to see a change in EPA air monitoring results from other locations. 

Since the MRGO project area is approximately 40+ miles away from the 

immediate oil impact site, the air quality impacts may not be as significant.

• Noise - No impacts to this resource have occurred within the project area from the 

oil spill and conditions will continue to be monitored as circumstances change. 

• Hazardous, Toxic, and Radioactive Waste - No impacts to this resource have 

occurred within the project area from the oil spill and conditions will continue to 

be monitored as circumstances change. The potential impacts from the use of 

dispersants are an unknown quantity at this time and will require further study. 

• Barrier Island Resources - Oil is significant, but has not completely surrounded 

the Chandeleur Island shoreline. Oil has been reported in sea grass and wetlands 

on the western side of the islands. The USACE has approved emergency permits 
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for the construction of sand berms on the island chain. The purpose of the berms 

is to trap oil before it reaches the delicate and fragile wetlands.

• Coastal Vegetation Resources - At the time of publication, oil spill related 

impacts had been reported in the saline, brackish and intermediate marshes of the 

Biloxi marsh region, the East Orleans Landbridge and the Lake Borgne area. The 

extent of the impact on coastal vegetation, both acute and chronic, cannot be 

quantified with the oil still coming ashore in the vast expanse of coastal marshes 

in Southeast Louisiana. Natural Resource Damage Assessments will be required 

to evaluate the primary and secondary impacts on the coastal marsh habitat. 

• Wildlife Resources – There have been numerous documented incidents of 

various bird species, including the brown pelican, directly impacted by oil on the 

barrier islands, as well as confirmed sea turtle deaths. While much of the project 

area has yet to be directly affected by the oil spill, substantial indirect effects are 

likely to have occurred to many birds and some mammals, and will continue for 

an extended period. 

• Aquatic and Fishery Resources - Impacts to fisheries populations within the 

project area, based upon ongoing water quality studies and fisheries sampling 

events, is unknown. The results of these sampling efforts by Federal and state 

agencies will eventually quantify potential short- and long-term impacts.

• Commercial Fisheries - Impacts to commercial fisheries included the closure of 

certain fishing grounds in both Federal and state waters throughout large portions 

of the Gulf and other coastal waters. A potentially lingering impact includes the 

National perception that seafood taken from the Gulf may be unsafe for 

consumption.

• Oyster Resources - Oyster beds were closed throughout the project area and most 

of coastal Louisiana. Testing of oysters meant for human consumption is 

ongoing. At this time there is no definitive results of the impacts and potential 

contamination of oyster beds. In order to help prevent oil entering the marsh, 

several freshwater diversions were opened. The impacts of these freshwater 

spikes on oysters is still unknown

• Water Bottoms and Benthic Resources - The extent of oil and dispersants 

currently located on the sea floor is unknown. There is a potential for suffocation 

of benthic invertebrates.

• Plankton Resources - The presence of oil and dispersants in the estuarine waters 

of the Louisiana marshes is anticipated to have impacts on the vast plankton 

resources that are dependent on the tidal marshes. The extent of the short-term 

and long-term impacts of oil on plankton species will require in-depth study to 

assess the adverse effects of the oil on the plankton of the Gulf of Mexico and 

interdependent estuarine life stages.

• Essential Fish Habitat - Ongoing water quality studies and fisheries sampling 

events are currently being conducted. Impacts to EFH within the project area, 

based upon these sampling efforts, are unknown. The results of these sampling 

efforts by Federal and state agencies will eventually quantify potential short- and 

long-term impacts.

• Threatened and Endangered Species - Potential impacts include direct impacts 

to endangered species critical habitat and reduction in available uncontaminated 
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habitat refuges. Coordination with the USFWS, NMFS, and LDWF is ongoing in 

determining how to best address potential problems associated with the oil spill 

that may adversely impact the threatened and endangered species that are found 

within the project area. 

• Socioeconomic and Human Environment - According to an economic analysis 

conducted by Dun and Bradstreet (2010 Deepwater Horizon Oil Spill: 

Preliminary Business Impact Analysis for Coastal Areas in the Gulf States, Dunn 

& Bradstreet, June 7, 2010) there are 315 Louisiana businesses and 78 Mississippi 

businesses that are directly related to the seafood industry in the Gulf of Mexico 

and could be severely impacted by the oil spill. These negative impacts would in 

turn alter the socioeconomic stability of the coastal communities of Louisiana and 

Mississippi as related to population, employment and income, community 

cohesion, etc. Data is not available as of the time of this analysis (August 2010) 

to estimate specific impacts.

• Environmental Justice - No impacts to this resource have occurred within the 

project area from the oil spill and conditions will continue to be monitored as 

circumstances change. 

• Recreational Resources - In the short-term, recreational fishing is being 

significantly impacted by the ongoing oil spill. Recreational fishing areas are 

currently open but can close at any time due to movement of the oil sheen. 

Regardless if fishing areas are open or closed, recreational fishing is impacted by 

the perception of negative effects of oil and chemical dispersants. In the longterm, recreational fishing could be impacted by the effect of the oil spill on 

fishery habitat and spawning areas.

• Aesthetics - The oil globules, particles and the sheen that flows along the top of 

the water, are a dramatic visual blight to any landscape setting. However, loss of 

plant materials could impact scenic quality by reducing color and texture in the 

numerous marshes, wetlands and swamps throughout the ecosystem restoration 

project area. Wildlife plays an integral role in the scenic quality of the landscape, 

providing focal points and drama to the scenery. The loss of habitat would cause 

wildlife to move to another area or, as a worst case scenario, die off completely. 

• Scenic Streams – There have been no reports of tar balls, sheen, or oil within the 

Central Wetlands area or the Golden Triangle marsh area where the seven scenic 

streams within the project area are located. However, if oil would eventually 

infiltrate these areas, impacts could include the loss of plant material and harm to 

wildlife which in turn reduces the aesthetic value of the area and diminishes the 

publics’ ability to enjoy these scenic streams. 

2.12.9 Engineering Level of Design

The engineering level of effort for the proposed restoration features is considered at full 

feasibility level of design except for the Violet, Louisiana freshwater diversion which is 

still preliminary. However, the preliminary engineering that has been conducted thus far 

provides adequate detail regarding the location and design components associated with 

the Violet, Louisiana freshwater diversion. Furthermore, the preliminary level of 

engineering detail is considered adequate as it relates to determining environmental 
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impacts. The possibility remains that as this feature is further refined, additional surveys 

and borings would need to be obtained and supplemental NEPA documentation would 

be necessary for unidentified impacts resulting from project changes.

2.13 RESEARCH AND TECHNOLOGY DEVELOPMENT 

NEEDS

Although many studies have been conducted in the Louisiana coastal area, most were 

limited in geographic extent or technical scope. Therefore, while much has been learned 

from previous efforts, many scientific and technical uncertainties remain. As listed in the 

LACPR Coastal Appendix, some areas of high uncertainty include: 

• availability of sediment (riverine and offshore) 

• subsidence rates and sea level rise

• benefits and impacts of pulsed freshwater diversions 

• channel evolution in freshened areas

• effect of diversions on Mississippi River sediment transport 

• cumulative effect of multiple diversions in a basin or region 

• over freshening of estuaries

• fisheries impacts associated with river diversions

• pipeline conveyance technologies and costs 

• thin-layer sediment placement techniques 

• salt transport inland with sediments from offshore 

• benthic habitat impacts

To effectively use existing knowledge and gain the increased understanding necessary to 

deal with the issues described above, it is essential that appropriate predictive tools are 

developed. The tools include numerical modeling approaches to predicting patterns of 

water level, salinity, and sediment distribution. Hydrologic models must be developed, 

which specifically encompass flows across marsh surfaces and through channels and 

structures, must be developed. Ecological models must address marsh accretion (mineral 

and organic), nutrient budgets, and soil biogeochemical processes. 

To fully achieve the ecosystem goals of this study, a better understanding of ecological 

and biogeomorphic processes and functions is needed. Critical questions still need 

answers, such as “What is the effect on ecosystem sustainability of a seasonal river 

diversion that increases the annual range of salinity within the receiving basin? How 

important to coastal marshes is nutrient input alone vs. freshwater and sediment delivery 

from the river? How does this vary with marsh type?” 

Due to uncertainties associated with sustaining Louisiana’s coast through sediment 

placement, a sediment-needs budget and sources inventory should be developed. Further 

study of sediment loads in the lower Mississippi River is needed due to variation between 

sampling frequency and methods at various sites. The LCA Mississippi River 
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Hydrodynamic Study is anticipated to increase available data and understanding about the 

sediment loads in the river.
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CHAPTER 3: AFFECTED ENVIRONMENT

3.1 INTRODUCTION

The National Environmental Policy Act (NEPA), 40 CFR Part 1500 et seq., provides 

guidance for the preparation of environmental impact statements (EIS). The Affected 

Environment chapter includes a description of the existing environment within the study 

area, as well as more specific descriptions of conditions within the proposed project area. 

Guidance for preparation of the Affected Environment chapter is contained in Section 

1502.15 of the Council on Environmental Quality (CEQ) regulations. The regulation 

states that this section shall contain data and analysis “commensurate with the importance 

of the impact, with less important material summarized, consolidated, or simply 

referenced.”

This chapter provides a description of the physical, biological, and socioeconomic 

environments occurring within the study area as a result of past and present actions. 

Emphasis is placed on resources of particular concern such as water quality, hydrology, 

wetlands, fisheries, threatened and endangered (T&E) species and associated critical 

habitat. Of particular concern in the Pontchartrain Basin are the increases in salinity 

intrusion and the accelerated loss of wetland vegetation due partly to the construction of 

the Mississippi River Gulf Outlet Navigation Channel (MRGO). The MRGO was 

deauthorized early in June 2008 and a rock closure structure was completed in July 2009 

near the Bayou La Loutre Ridge (figure 3-1).

Figure 3-1: MRGO Closure Structure at Bayou La Loutre Completed July, 2009 
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3.2 SIGNIFICANT RESOURCES 

The U.S. Corps of Engineers (USACE) Engineering Regulation 1105-2-100 provides 

guidance for ecosystem restoration studies. The USACE policy recommends the 

identification of significant resources within the study area and consideration provided 

for the effects of the restoration plan on those resources during the evaluation process. 

Resources protected or governed through legislation or valued in technical reports and by 

the public are considered significant. Institutional sources include global or National 

publications and conservation status rankings as well as protection plans and statutes. 

Input on locally significant resources was obtained during scoping meetings, stakeholder 

group meetings and from local, state, and Federal resource agencies. Technical sources 

ranged from national and regional research papers to local college, university, agency, 

and group expertise. 

Louisiana’s coastal areas are economically, recreationally, and ecologically important to 

the region, the Nation, and internationally. The loss and restoration of Louisiana’s 

coastal wetlands have been a concern and issue of major importance for many decades.

 

The existing conditions of the affected environment represent the baseline conditions 

against which future conditions are evaluated. The affected environment is described by 

resource categories. Table 3-1 lists the identified resources that are discussed in this 

chapter as well as the state or Federal legislation governing the importance of the 

resource. 

Table 3-1: Significant Resource and Institutional Recognition

Significant Resource Institutional Recognition

General Biological Resources

Executive Order (EO) 11988 Floodplain Management

National Environmental Policy Act of 1969

Coastal Zone Management Act of 1972

Water Resources Development Acts of 1976, 1986, 1990, 1992

Barrier Island Resources Coastal Barrier Resources Act of 1982

Aquatics and Fisheries

Marine Mammal Protection Act

Anadromous Fish Conservation Act

Fish and Wildlife Conservation Act of 1980

Fish and Wildlife Coordination Act of 1958, as amended

Marine Protection, Research and Sanctuaries Act

Fishery Conservation and Management Act

Essential Fish Habitat

Magnuson-Stevens Fishery Conservation and Management Act of 

1976, as amended (MSA)

Magnuson-Stevens Act Reauthorization of 2006

Threatened and Endangered 

Species (T&E) Endangered Species Act of 1973

Wildlife

Fish and Wildlife Conservation Act of 1980

Fish and Wildlife Coordination Act of 1958, as amended

Migratory Bird Conservation Act

Migratory Bird Treaty Act

EO 13186 Migratory Bird Habitat Protection
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Table 3-1: Significant Resource and Institutional Recognition

Significant Resource Institutional Recognition

Coastal and Migratory Birds Bald and Golden Eagle Protection Act (BGEPA)

Prime and Unique Farmlands Farmland Protection Policy Act of 1981

Invasive Species EO 13112 Invasive Species

Wetlands

EO 11990 Protection of Wetlands

Clean Water Act (CWA)

Estuary Protection Act of 1968

North American Wetlands Conservation Act

Emergency Wetlands Resources Act of 1986

Scenic Streams Louisiana Scenic Rivers Act (LSRA) - Acts 1988, No. 947, §1, eff. 

July 27, 1988

Recreation Federal Water Project Recreation Act of 1965, as amended

Land and Water Conservation Fund Act of 1965, as amended

Aesthetics National Environmental Policy Act of 1969

Cultural Resources Section 106, National Historic Preservation Act of 1966

36 CFR Part 800, Protection of Historic Properties

Air Quality

Clean Air Act of 1963, as amended

Louisiana Environmental Quality Act of 1983

29 CFR, part 1910, Occupational Safety and Health Standards

Noise Noise Control Act of 1972

Title 29 Code of Federal Regulations (CFR), Part 1910, subpart G

Water Quality Clean Water Act of 1977

Hazardous, Toxic, and

Radioactive Waste (HTRW)

ER 1165-2-132

42 U.S.C. 6905 Resource Conservation and Recovery Act

Comprehensive Environmental Response, Compensation, and 

Liability Act (CERCLA)

Environmental Justice EO 12898

Social Economic Resources National Environmental Policy Act of 1969

3.3 STUDY AREA

The study area covers approximately 3.86 million acres (over 6,000 square miles) which 

includes portions of the Mississippi River Deltaic Plain in southeast Louisiana and parts 

of southwest Mississippi (figure 3-2). In Mississippi, the study area includes the 

Western Mississippi Sound, the surrounding wetlands, and Cat Island. In Louisiana, the 

study area includes the Pontchartrain Basin, which is comprised of the Upper, Middle, 

and Lower sub-basins. The Upper Pontchartrain sub-basin includes Lake Maurepas and 

its adjacent wetlands and swamps. The Middle Pontchartrain sub-basin is comprised of 

Lake Pontchartrain, the adjacent cities and towns, and surrounding wetlands. 

As described in chapter 1, the Lower sub-basin includes Lake Borgne, the deauthorized 

MRGO, the Mississippi River, Chandeleur and Breton Sounds, portions of Western 

Mississippi Sound and the Gulf of Mexico, including the surrounding wetlands, barrier 

islands, and communities. Lake Borgne is hydrologically linked to Lake Pontchartrain 

through tidal passes at the Rigolets, Chef Menteur Pass, and the manmade Inner Harbor 

Navigation Canal (IHNC). The Lake Borgne ecosystem is also influenced by the Pearl 

River to the north and receives hydrologic interchange from areas located as far south as 
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the River Aux Chenes Ridge, which is located between the MRGO and the Mississippi 

River. Major navigation channels include the Mississippi River, IHNC, and the Gulf 

Intracoastal Waterway (GIWW). 

Figure 3-2: Study Area – Pontchartrain Basin and Western Mississippi Sound

Following identification and screening of features and formulation of final alternatives, 

the proposed project area was identified as the Lower Pontchartrain sub-basin. 

3.4 GEOMORPHIC AND PHYSIOGRAPHIC SETTING

Most of the present landmass of southeast Louisiana was formed by deltaic processes of 

the Mississippi River. Over the past 7,000 years, the Mississippi River deposited massive 

volumes of sediment in five deltaic complexes. The study area lies within the Mississippi 

Delta Region (figure 3-3) comprised of three geomorphic regions, which are divided 

further into multiple smaller geomorphic areas.
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Figure 3-3: Mississippi Deltaic Region (Coast 2050)

The Pleistocene Terrace Region is the area north of Lakes Maurepas, Pontchartrain, and 

Borgne. This region is defined as the area north of the Mississippi River Deltaic Plain 

and the lowlands surrounding Lakes Pontchartrain and Maurepas. 

The Marginal Deltaic Basin is comprised of estuarine marshes and forested wetlands of 

the Lakes Pontchartrain and Maurepas. This region includes some of the largest 

remaining tracts of forested wetlands in the Lower Mississippi River Valley. The 

Marginal Deltaic Basin is divided into the following eight geographic areas: Maurepas 

Swamp, Manchac Landbridge, Southwest Pontchartrain, Lake Pontchartrain, North Shore 

Marsh, Bayou Sauvage, East Orleans Landbridge, and Pearl River Mouth (figure 3-4). 

The Marginal Deltaic Basin lies within the coastal zone of Louisiana and is influenced by 

wetland loss, subsidence, saltwater intrusion and shoreline erosion. USACE data 

indicates relative sea level rise in the region of less than 0.5 feet per century, but in many 

localized areas, the rate is greater. Shoreline erosion is taking place around the entire 

perimeter of Lakes Pontchartrain, Maurepas, and Borgne, except at armored sections. 
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Figure 3-4: Marginal Deltaic Basin

The Mississippi River Deltaic Region lies south of the lakes. The salinity gradient within 

this region decreases from east (saltwater of the Gulf of Mexico) to west (fresher waters 

in the coastal plain) through the Pontchartrain Basin (figure 3-5). 

The proposed restoration features of this study are located within the St. Bernard Deltaic

Complex, the oldest deltaic complex within the Mississippi Deltaic Plain Region. The 

areas contained in this geomorphic region are associated with the delta-building cycle of 

the Mississippi River and are removed from Lake Pontchartrain. 

The Mississippi River Deltaic Plain Region is divided into the following geographic 

areas: Central Wetlands, South Lake Borgne, Lake Borgne, St. Bernard Wetland, BretonChandeleur Sound, Chandeleur Island, Plaquemines Wetland, and Birdfoot Delta. The 

Central Wetlands, Lake Borgne, South Lake Borgne and Chandeleur Island Areas are all 

part of the St. Bernard Delta. The Mississippi River naturally abandoned this older delta 

lobe when it switched its course some 2,000 years ago and began building the Lafourche 

Delta. Consequently, land building declined in this portion of the Lake Pontchartrain 

Basin well before European settlement. USACE data show relative sea level rise in the 

region ranging from less than 0.5 foot per century to one foot to four feet per century, 

making it the most rapidly subsiding portion of the Lake Pontchartrain Basin. The 

Chandeleur Islands mark the outer edge of this system, but they are migrating landward. 

Wetlands consist of poorly consolidated soils and elevations are slightly above mean gulf 

level. Uplands adjacent to the deltaic plains are geologically older with higher elevation 
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and firmer soils. Narrow alluvial ridges, resembling finger-like patterns that were formed 

by overbank processes, extend toward the Gulf of Mexico. The ridges serve as natural 

levees, having higher elevation and firmer soils and occur along active, abandoned 

distributaries of the Mississippi River (Coast, 2050). The natural and man-made ridges 

form hydrologic basin divides and are more resistant to erosion than wetlands. 

Figure 3-5: Mississippi River Deltaic Region

Construction of the MRGO impacted the natural geomorphology and hydrology of the St. 

Bernard Deltaic Complex. In an analysis of the tidal flow across the region, it was 

demonstrated that the Bayou La Loutre Ridge served as a basin boundary. Dredging 
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through the ridge interrupted the circulation pattern along the southeastern length of the 

channel and the areas between Breton Sound and Lake Borgne (Wicker et al., 1982). 

3.5 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 dynamic fashion. 

The distribution and abundance of wetland habitats in the deltaic plain has been, and 

continues to be, in constant flux — a function of the differing salinity gradients that occur 

during the land building and degradation phases of the deltaic processes, as well as the 

myriad of other key processes that influence wetland and estuarine conditions. The 

following sections summarize the key processes involved in this ecosystem. 

3.5.1 The Deltaic Processes

The 186-mile wide Mississippi River Deltaic Plain and its associated wetlands and barrier 

shorelines are the product of the continuous 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 

catastrophic 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 islands formed and eventually were separated 

from the mainland by shallow bays and lagoons (LACPR, 2008). 

The result of the building and subsequent abandonment of these delta lobes by the River 

was the construction of a modern deltaic coastal plain. Each delta cycle lasts about 1,000 

years, and the most recent delta (the Mississippi Birdfoot Delta) is approaching the end of 

that time scale (LACPR, 2008). These processes are discussed in detail in the Louisiana 

Coastal Area (LCA) (2004) report.

3.5.2 Mud Stream

Every active subdelta has a “mud-stream” that consists of the fine grained sediments 

(silts and clay) that stay in suspension beyond the immediate area of the active 

distributary outlets and move along the coast in response to coastal currents (Morgan et 

al., 1953; van Lopik, 1955; Adams et al., 1978; van Heerden, 1983; Wells and Roberts, 

1980; Kemp, 1986; Roberts, 1998). Twenty-five percent or more of the transported 

sediment escapes deposition in the immediate area of the distributary outlets and is 

carried away in the mud-stream. Distributary outlets that discharge into deep waters (far 

out on the continental shelf or beyond the shelf edge, as in the case of the modern 

Birdfoot Delta) may deposit mud-stream sediment on the sea bottom of the shelf or into 
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the depths of the gulf. In the case of the modern Mississippi River Delta, mud-stream 

sediments are largely lost to the land building and maintenance processes. 

3.5.3 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 .04 to .08 

inches per year, but are projected to increase due to climate change (Titus and Richman, 

2001). Superimposed on this long-term trend is a mean water level that varies seasonally 

by .79 inches to .98 inches, with peaks in the spring and late summer. Part of this 

seasonal variation is related to the dominant variable wind regime over the Gulf of 

Mexico; east and southeast winds in spring and fall move water toward the shore whereas 

westerly winds strengthen the Mexican current and draw a return flow of water from the 

estuaries during winter and summer (Baumann 1980). Superimposed on the seasonal 

water level change is a diurnal tide, which averages about 11.81 inches at the coast. 

Because of the broad, shallow expanse of the coastal estuaries, the tides decrease inland.

These marine processes serve to redistribute sediments and nutrients, as well as regulate 

salinity levels and fluxes in the estuaries. Large, episodic storms can significantly alter 

the landscape developed as a consequence of the more normal marine processes. 

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 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).

3.5.4 Fluvial Processes

The largest source of freshwater and sediment in the study area is the Mississippi River. 

The Pearl River and other smaller rivers contribute additional water and sediments from 

local watersheds. Flow is strongly seasonal, peaking in late spring, fed by melting snow 

and spring rains in the Upper Mississippi watershed. Flows on the Mississippi River are 

independent of local rainfall because of the size of the watershed, but freshwater and 

sediment from local rivers and streams along the coast is supplied mainly during periods 

of heavy local rainfall (LACPR, 2008). 

The inactive delta of the Mississippi River (the part that has been abandoned by the 

River) is isolated from direct riverine input by natural and artificial levees. The 

Mississippi and Pearl Rivers discharge into the Gulf of Mexico. Most of the Mississippi 

River waters are carried westward along the coast, freshening the Gulf of Mexico waters 

that move in and out of the Barataria, Terrebonne, and Vermilion estuaries, rather than 

reaching estuaries in the study area (LACPR, 2008). 
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3.5.5 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 taken up and fixed in the tissues of rapidly 

growing vascular plants. These substances may be incorporated or otherwise transformed 

by microbial assemblages associated with the complex of surfaces provided by the 

sediment, live plants, litter, and detritus (LACPR, 2008). 

Biogeochemical processes within the wetland are also affected by offsite inputs from the 

surrounding drainage area. Eutrophication caused by anthropogenic nutrient enrichment 

of coastal ecosystems has been a major concern for resource managers for the last few 

decades. The effects of nutrient enrichment include stimulation of primary production by 

algae and phytoplankton and depletion of oxygen, which can lead to hypoxia (a 

deficiency of oxygen while not being devoid of oxygen) (Deegan, 2002). Nutrient 

enrichment can also cause shifts in plant species distribution and zonation in mixed 

species tidal wetlands, resulting in increased dominance of S. alterniflora at the expense 

of other tidal marsh species (Pennings et al., 2002). 

Recent research has shown that anthropogenic eutrophication may cause shifts in benthic 

invertebrate and fish community food webs that are manifested long before actual loss of 

the habitat occurs (Deegan, 2002). Furthermore, the cumulative effects of nutrient 

enrichment on a landscape scale may cause increased or decreased rates of subsidence, 

although these predictions have not yet been tested (Deegan, 2002). Highly developed or 

industrial watersheds may also serve as sources of metals, hydrocarbons, and other toxins 

that may be deposited in wetland sediments, posing risks for benthic organisms that 

inhabit them. As predators consume these organisms, food web dynamics may be altered 

through accumulation of toxins in the tissues of higher trophic level organisms. The 

accumulation of toxins in animal tissues may reduce growth and fecundity (or 

productivity), and may render them unsuitable for consumption as food. 

3.5.6 Biological Processes

Coastal fringe marshes provide habitat for a variety of vertebrate wildlife 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 (e.g., mallard [Anas 

platyrhynchos] and American wigeon [A. americana]), whereas the muskrat (Ondatra 

zibethicus) and raccoon (Procyon lotor) are valuable furbearers. The American alligator 

(Alligator mississippiensis) is harvested for both its skin and meat. Many of the birds that 

commonly use coastal fringe wetlands, especially larger species such as ospreys, herons, 

egrets, and Roseate Spoonbills (Ajaia ajaia) provide recreational opportunities for 

birdwatchers, nature enthusiasts, and wildlife photographers (LACPR, 2008). 

The majority of wildlife species that utilize tidal marsh have neither commercial nor 

recreational value, but simply are ecologically important members of the ecosystem. For 
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example, the rice rat (Oryzomys palustris) 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 (Myocastor 

coypus), consume copious amounts of forage and at high densities may have significant 

impacts on marsh vegetation (LACPR, 2008). 

Tidal marshes provide forage habitat, spawning sites, and a predation refuge, and serve as 

a nursery 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, as nurseries. A number of ecologically and economically important nekton 

and benthic species are dependent on the availability of suitable tidal marsh habitat. 

Nekton refers to the aggregate of actively swimming aquatic organisms in a particular 

body of water. Estuarine-dependent species such as the penaeid shrimp 

(Farfantepenaeus spp., Litopenaeus spp.), the blue crab (Callinectes sapidus), the 

sciaenids (Cynoscion spp., Sciaenops ocellatus, Leiostomus xanthurus, Micropogonias 

undulatus, and Bairdiella chrysoura, etc.), and others use tidal marshes and shallow, 

subtidal bottoms as nurseries. The ubiquitous killifishes (Fundulus spp.), grass shrimp 

(Palaemonetes spp.), and gobies (Gobiosoma spp., Gobionellus spp., Microgobius spp., 

etc.) are characteristic residents of Atlantic and Gulf Coast intertidal wetlands. These 

organisms are consumed by nektonic and avian predators and are considered to represent 

an important link in marsh-estuarine trophic dynamics (LACPR, 2008). 

Most evidence suggests that resident organisms (e.g., killifishes, grass shrimps) utilize 

the entire marsh surface across the range from low to high elevations, but that the dense 

vegetation characteristic of high marsh habitats may offer greater protection from natant 

predators than low marshes. However, resident nekton are also widely distributed 

throughout the lower intertidal marsh early and late in the tidal cycle in Louisiana and 

Mississippi (Rozas and Reed, 1993; Fulling et al., 1999; Hendon et al., 2000), and may 

use these areas as staging areas prior to marsh flooding. Resident nekton can make 

extensive use of high marsh when spring tide conditions facilitate access to the upper 

intertidal zone. Several resident killifish species, including Fundulus grandis, F. similis, 

F. pulverus, and Adinia xenica, rely on availability of high intertidal marsh, coincident 

with spring tidal events, for use as spawning sites (Greeley and MacGregor, 1983; 

Greeley, 1984; Greeley et al., 1986; Greeley et al., 1988). Killifishes also use tidal 

marshes for foraging sites; as Rozas and LaSalle (1990) noted, the Gulf killifish (F. 

grandis) consumed more prey when it had access to the marsh surface than when it was

confined to subtidal areas by low tides (LACPR, 2008). 
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3.6 HYDROLOGY – HYDRAULICS

3.6.1 Historic and Existing Conditions

Prior to the construction of levees on the Mississippi River, the River would overflow its 

banks during periodic floods. Flow from the River into Breton Sound was via various 

bayous such as Bayous Bienvenue, Dupre, and La Loutre that were part of the remnant 

tributary system that extended from the Mississippi River eastward to the Biloxi Marsh 

and Mississippi Sound. These channels were used by smaller crafts, mostly commercial 

and recreational fishing. With the construction of levees, and the strengthening of these 

levees with the Mississippi River and Tributaries (MRT) program, the River no longer 

overflows into the project area. The only introduction of river water into the project area 

is from the Caernarvon Freshwater Diversion structure to the south of the project area, a 

small amount from lockage at the IHNC lock, and the Bonnet Carré Spillway to the north 

of the project area.

The Bonnet Carré Spillway is periodically operated for flood control. The frequency of 

operation is about once a decade. During operation of the structure, large volumes of 

river water (up to a capacity of 250,000 cubic feet per second [cfs]) are introduced into 

Lake Pontchartrain to lessen flow and stages in the River. During high river stages (but 

not high enough to necessitate operation of the structure) there is leakage through the 

needles of the structure. This leakage is on the order of 5,000 cfs to 10, 000 cfs. 

The project area is an estuary in which freshwater, predominantly from run-off into the 

Pontchartrain Basin and the Pearl River Basin, mixes with the saltwater of the Gulf of 

Mexico. The tides in the Gulf near the project area are mostly diurnal with a spring tide 

range of 1.9 ft. to 2.3 ft. During periods with flood discharges in the Pearl and 

Pontchartrain Basins, salinity levels in the project area tend to be reduced. During 

periods of drought conditions in the Basins, salinity levels in the project area will tend to 

increase.

There are three navigation channels in the project area, which may have modified the 

hydrologic regime of the Biloxi Marsh. These are the IHNC, the GIWW, and the 

recently de-authorized MRGO. 

The IHNC Lock, connecting the Mississippi River and Lake Pontchartrain, was 

completed in 1923 with the construction of the IHNC lock at the Mississippi River 

preventing high stages in the River from producing strong currents in the channel. In the 

1930s, the GIWW was constructed from the mid-point of the IHNC going east and later 

routed through the IHNC lock. The construction of the GIWW east of the IHNC allowed 

for additional tidal exchange with Lake Pontchartrain, in addition to the larger channels 

of the Rigolets and Chef Menteur Pass.

 

Prior to construction of the MRGO, a typical tidal flow from the Breton Sound area was 

reduced as it moved across the marshes and wetlands inward toward the Lake

Pontchartrain. There are a number of factors resulting from construction of the MRGO 
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that have contributed to the alteration of circulation patterns and water quality along the 

length of the MRGO and outward into the surrounding wetlands and marshes. The 

MRGO provided a more direct flow of more saline, higher density water inland toward 

areas of St. Bernard and eastern Orleans Parishes. Dredging through of the Bayou La 

Loutre Ridge, as a basin boundary, significantly altered circulation patterns in areas along 

the lower southeastern length of the channel and across areas between Breton Sound and 

Lake Borgne.

Dredging performed for construction of the MRGO to an approximate depth of 36 feet 

resulted in the generation of an abundance of dredged material. The dredged material 

was deposited in a continuous strip along the channel’s southwestern limits. Dredged 

material deposition interrupted the local circulation patterns of natural waterways that 

transect areas along the length of the MRGO. 

The sector gates on the GIWW and Bayou Bienvenue presently being constructed for the 

authorized improvements to the Hurricane and Storm Damage Risk Reduction System 

(HSDRRS) would alter flow patterns in and near the western end of the project area. 

Construction of this storm surge barrier structure includes dredging of an access channel 

to construct the floodwall. The access channel connects the MRGO with the GIWW 

across the Golden Triangle. The gates across Bayou Bienvenue and the GIWW would 

remain open, except when a storm is approaching. 

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. Whereas, prior to the construction of this project, 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 Bayou 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 blocked. Modeling of the project area with the UNO Mass balance model has 

shown a slight reduction in salinity in the project area, but not sufficient to alleviate the 

need of a freshwater diversion to restore historic conditions. 

The Lake Borgne storm surge barrier would prevent saltwater intrusion into the interior 

marshes to the west of the barrier in storm situations, while minimally impeding tidal 

flows under normal circumstances. This barrier would not influence salinity in marshes 

to the east of the barrier, nor would it influence salinity within the Central Wetlands area 

as the gates of the Bayou Dupre and Bayou Bienvenue control structures are closed 

during tropical events. 

Modeling scenarios for the barrier structures indicate that the proposed flood protection 

levee could raise the water levels by 0.1 foot or less (see Hydrology and Hydraulics 

(H&H) Report, appendix L). However, the authors of this modeling study caveat their 

results as follows: “this change in average water volume represents a difference of less 
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than 1 inch of water depth distributed across the region. This difference in volume may 

be smaller than the precision achievable with present computational resources.” 

3.7 WATER QUALITY

3.7.1 Historic and Existing Conditions

This resource is institutionally significant because of the NEPA of 1969; the Clean Water 

Act (CWA) of 1972; the Coastal Zone Management Act of 1972; and the Estuary 

Protection Act of 1968. Water quality is technically significant because it is an important 

factor in the physical, chemical, and biological processes throughout the entire estuarine 

system. This resource is publicly significant because the public demands clean water and 

healthy wildlife and fishery species for recreational and commercial use. The CWA 

established a process for each state to monitor and report on its surface and groundwater 

quality. The Environmental Protection Agency (EPA) compiles and summarizes the data 

from the state reports and transmits them to Congress along with an analysis of the status 

of nationwide water quality. Requirements for this process are found in Section 305(b) 

of the CWA. The National Water Quality Inventory 305(b) Report to Congress identifies 

widespread water quality problems of national significance and describes various 

programs to restore and protect water quality. The Section 305(b) Water Quality Report 

(2008) prepared by the Louisiana Department of Environmental Quality (LDEQ) 

summarizes the monitoring data that characterizes the quality of waters in the project area 

(table 3-2).

Table 3-2: 2008 Louisiana Water Quality – 303(d) List

Subsegment 

Number

Subsegment 

Description

PCRSCRF&WP ONROYS

Suspected Cause 

of Impairment

Suspected 

Source of 

Impairment

LA041401

New Orleans 

East Levee 

Water Bodies

N N N - - Fecal Coliform / 

Dissolved Oxygen 

Municipal / 

Sanitary Sewer 

Overflows

LA041805

Lake Borgne 

Canal (also 

known as the 

Violet Canal)

F F N N - Dissolved Oxygen 

/ Turbidity

Natural Sources /

other Permitted 

Small Flow 

Discharges

LA041806 Pirogue Bayou F F N F - Dissolved Oxygen Natural Conditions

LA041807 Terre Beau 

Bayou F F N F - Dissolved Oxygen Natural Conditions

LA041808 New Canal F F N - - Dissolved Oxygen Natural Conditions

LA042102 River Aux 

Chenes F F F - N Fecal Coliform Wildlife other than Waterfowl

SOURCE: Final Draft 2008 Louisiana Water Quality Integrated Report – Category 5 and 5RC “303(d) List”

NOTES:

F – Indicates that the water body fully supports the resource.

N – Indicates that the water body does not support the resource.
Chapter 3 Affected Environment

FEIS MRGO Ecosystem

Restoration Plan 3-15 June 2012

The LDEQ assesses four categories for water use under the Louisiana Environmental 

Regulatory Code (LAC Title 33, Chapter 11) that apply to those portions of the study 

area within Louisiana: 

a. Primary Contact Recreation (PCR) includes activities such as swimming, water 

skiing, tubing, snorkeling, skin diving, and other activities that involve prolonged 

body contact with water and probable ingestion. 

b. Secondary Contact Recreation (SCR) includes fishing, wading, recreational 

boating, and other activities that involve only incidental or accidental body 

contact and minimal probability of ingesting water. 

c. Fish and Wildlife Propagation (F&WP) includes the use of water by indigenous 

fishes and invertebrates, reptiles, amphibians, and other aquatic biota consumed 

by humans for habitat, food, resting, reproduction, and cover. 

d. Oyster Propagation (OYS) includes the use of water to maintain biological 

systems that support economically important species of oysters, clams, mussels, 

and other mollusks consumed by humans, so that their productivity is preserved 

and the health of human consumers of these species is protected. 

According to guidance provided by the EPA, a water body may fall within one of three 

use support categories depending on the percent of measurements for any one physical or 

chemical parameter that exceeds the state’s numerical water quality standards. These 

categories include Fully Supporting, Partially Supporting, and Not Supporting. In the 

case where more than one parameter defines a designated use, support for each 

designated use is defined by the poorest performing parameter. General water quality 

criteria against which ambient concentrations are evaluated to make use support decisions 

are promulgated in the Louisiana Administrative Code, Title 33, Part XI, Chapter 11. 

General criteria include numeric values for temperature, hydrogen ion (pH), dissolved 

oxygen (DO), turbidity, and total dissolved solids (TDS). The general criteria 

concentrations applicable in the study area are: temperature less than 95°F, pH range of 

6.5 to 9 standard units, DO greater than 4 milligrams per liter (mg/l), turbidity less than 

50 NTU, and total suspended solids less than 500 mg/l. A detailed breakdown of each 

category is given in table 3-3. 

Table 3-3: Summary of Use Support Categories

Designated Use

Measured

Parameter

Support Classification for Measured Parameter

Fully Supporting

Partially 

Supporting Not Supporting

Primary Contact 

Recreation (PCR)

Designated swimming 

months of May - October 

only. 

Fecal coliform

Temperature

0-25% do not meet

criteria

0-30% do not meet

criteria

--

>30-75% do not

meet criteria

>25% do not meet

criteria

>75% do not meet

criteria

Secondary Contact

Recreation (SCR)

(All months)

Fecal coliform 0-25% do not meet

criteria

-- >25 % do not meet

criteria
Chapter 3 Affected Environment

FEIS MRGO Ecosystem

Restoration Plan 3-16 June 2012

Table 3-3: Summary of Use Support Categories

Designated Use

Measured

Parameter

Support Classification for Measured Parameter

Fully Supporting

Partially 

Supporting Not Supporting

Fish and Wildlife

Propagation (F&WP)

Dissolved oxygen3

DO

Temperature, pH, 

chloride, sulfate, 

TDS, turbidity

Metals and Toxics

0-10% do not meet

minimum of 3.0

ppm and median >

criteria of 5.0 ppm

0-10% do not meet

criteria

0-30% do not meet

criteria

< 2 exceedances of

chronic or acute

criteria in most

recent consecutive

3-year period, or 1- 

year period for

newly tested waters

--

>10-25% do not

meet criteria

>30-75% do not

meet criteria

--

>10% do not meet

minimum of 3.0 ppm

or median < criteria of 

5.0 ppm

>25% do not meet

criteria

>75% do not meet

criteria

2 or more exceedances

of chronic or acute

criteria in most recent 

consecutive 3-year 

period, or 1-year 

period for newly tested 

waters

Drinking Water

Source (DWS)

Color, fecal coliform

Metals and Toxics

0-30% do not meet

criteria

< 2 exceedances of

drinking water

criteria in most

recent consecutive

3-year period, or 1- 

year period for

newly tested waters

>30-75% do not

meet criteria

>75% do not meet

criteria

2 or more exceedances

of drinking water

criteria in the most

recent consecutive 3-

year period, or 1-year 

period for newly tested 

waters

Outstanding

Natural Resource (ONR)

Turbidity 0-10% do not meet

criteria

>10-25% do not

meet criteria

>25% do not meet

criteria

Agriculture (AGR) None -- -- --

Oyster Production

(OYS)

Fecal coliform Median fecal

coliform < 14

MPN/100 ml; and

< 10% of samples

< 43 MPN/100 ml

--

Median fecal coliform

> 14 MPN/100 ml;

and > 10% of samples

> 43 MPN/100 ml

Limited Aquatic

and Wildlife (LAW)

DO 0-10% do not meet

criteria

>10-25% do not

meet criteria

>25% do not meet

criteria

In the project area, F&WP and OYS were identified as being impaired in some areas. 

The EPA and LDEQ identified low DO levels and high fecal coliform levels as the 

suspected causes for impairment for both categories, but were not able to identify the 

sources of these problems (LDEQ, 2005). Coliform levels along the MRGO have usually 

exceeded the LDEQ criteria, indicating a widespread area of water and wetlands that are 

ppm = parts per million; TDS = Total Dissolved Solids; MPN = Most Probable Number, DO = Dissolved Oxygen 

SOURCE: EPA, 2010
Chapter 3 Affected Environment

FEIS MRGO Ecosystem

Restoration Plan 3-17 June 2012

subject to bacterial pollution. The suspected source is runoff from nearby populated 

areas in St. Bernard and Orleans Parishes. Measured DO levels at Bayou Dupre have 

consistently been above the minimum state standard and EPA criteria. With rare 

exceptions, the pH measurements have been within the desirable range of 6.5 to 9.0. 

Toxic substances, including heavy metals and synthetic organics, have been measured 

above EPA criteria levels, but no patterns consistently exceeding the criteria for 

particular substances have been observed. The Louisiana Department of Health and 

Hospitals (LDHH), Office of Public Health, Molluscan Shellfish Program (LDHH, 2007) 

prohibited the harvesting of oysters for human consumption from leases in the project

area south of the Lake Borgne shoreline through February 2008, at which time the 

prohibition was re-evaluated and lifted. A recent search of the LDHH Molluscan 

Shellfish Program website in April 2010 confirmed that no oyster harvesting areas within 

the project area were closed.

 

The Mississippi Department of Environmental Quality (MDEQ) assesses three categories 

for water use under Mississippi State Code of 1972 as amended (MSC Title 49, Chapter 

17) that apply to those portions of the project area within Mississippi. Waters classified 

for Shellfish Propagation are for propagation and harvesting shellfish for sale or use as a 

food product. These waters must meet the requirements set forth in the latest edition of 

the National Shellfish Sanitation Program, Manual of Operations, Part I, Sanitation of 

Shellfish Growing Areas, as published by the U. S. Public Health Service. Waters that 

meet the criteria for Shellfish Propagation are also considered suitable for recreational 

purposes. Recreation includes activities such as swimming and water skiing that involve 

prolonged body contact with water. Fish and wildlife includes activities such as fishing 

and propagation of fish, aquatic biota, and wildlife. Waters that meet the Fish and 

Wildlife Criteria are also considered suitable for Secondary Contact Recreation (MDEQ, 

2007). 

All data on existing water quality described below in sections 3.7.1.1 through 3.7.1.6 was 

taken from the Preliminary Assessment of Potential Water Quality Impacts for a 

Proposed Freshwater Diversion in the Vicinity of Violet, Louisiana (USACE, 2010). 

3.7.1.1 Mississippi River Existing Water Quality

The general water quality statistics for the Mississippi River during 1990 to 2010 from 

aggregated samples taken by the U.S. Geological Survey (USGS) and LDEQ are 

presented in table 3-4. This information was taken from the Preliminary Assessment of 

Potential Water Quality Impacts for a Proposed Diversion in the Vicinity of Violet, 

Louisiana (USACE, 2010). 

Table 3-4: Mississippi River Group General Summary Statistics from 1990-2010

General Units Mean

Number of 

Observations Max Median Min

Dissolved Oxygen mg/l 8.83 529 25.2 8.4 0.1

Water Temperature F 65.1 549 90.8 64.7 32.2

Sulfate mg/l 47 530 488 43.4 9.3

Total Dissolved Solids mg/l 271 369 630 268 67
Chapter 3 Affected Environment

FEIS MRGO Ecosystem

Restoration Plan 3-18 June 2012

Table 3-4: Mississippi River Group General Summary Statistics from 1990-2010

General Units Mean

Number of 

Observations Max Median Min

pH SU 7.94 531 16.2 7.73 0.1

Specific Conductance, 

Field μmhos/cm 401 515 839 394 0.1

Nitrate+Nitrite Nitrogen mg/l 1.55 453 9.38 1.41 0.02

Total Organic Carbon mg/l 5.5 399 28 4.9 2

Turbidity NTU 50 478 252 42 1.6

Total Suspended Solids mg/l 88 434 800 72.5 2 

SOURCE: USACE, 2010.

DO concentrations are normally well above values cited as being desirable for 

maintenance of well-balanced fish populations. Measured DO at the Mississippi River 

sites averaged 8.8 mg/l. During this period, violations of the State DO standard of 5.0 

mg/l were noted in only two percent of the 529 observations reported. The State of 

Louisiana has also published numerical standards for temperature (90°F) and ambient 

concentrations of chloride (CL - 75 mg/l), sulfate (SO4 

 

- 120 mg/l), pH (6.0-9.0), and 

TDS (400 mg/l). Data were not available for chloride at the stations and time period used 

for this water quality report. The average water temperature was 66°F with a maximum 

of 91°F. 

Violations of state standards for SO4, pH, and TDS occurred during the time period 

investigated. While the average sulfate concentration was 47 mg/l, values were reported 

up to 488 mg/l. Values exceeded the sulfate threshold in less than one percent of the 

samples collected in the Mississippi River. The pH data, taken from LDEQ and USGS 

sample locations, averaged 7.9 with a range from 0.10 to 16.2, although low and high 

values are likely erroneous (due to their extremely acidic and basic values). Within the 

dataset analyzed, pH exceeded the numerical standards set by the State of Louisiana. 

TDS averaged 271 mg/l compared to the 400 mg/l standard for this reach of the 

Mississippi River. TDS values were reported up to 630 mg/l. The Mississippi River 

exceeded the TDS threshold in two percent of the samples collected. Specific 

conductance averaged 400 μmhos/cm with a maximum value of 839 μmhos/cm; 

therefore, this reach of the Mississippi River is classified as a freshwater system. 

Freshwater streams ideally should have conductivity between 150 to 500 μmhos/cm to 

support diverse aquatic life. 

The Mississippi River has a high concentration of nitrogen with the majority of inorganic 

nitrogen in the form of nitrate and nitrite (NOx). This reach of the River had an average 

NOx concentration of 1.55 mg/l. The average total organic carbon was 5.48 mg/l with a 

maximum of 28 mg/l. 

The River is normally characterized by highly turbid waters due to the enormous 

suspended sediment load transported. Data from the USGS indicates that approximately 

77 percent of the River's suspended sediment discharge is transported as silt and clay 

(particles smaller than 0.062 millimeter in diameter). Maximum concentrations generally 

occur in late winter or early spring and have an average composition of about 82 percent 
Chapter 3 Affected Environment

FEIS MRGO Ecosystem

Restoration Plan 3-19 June 2012

silt and clay, with about 18 percent sand in the upper 20 percent of the water column. 

The suspended sediment concentration in the reach investigated averaged 88 mg/l and 

turbidity averaged 50 NTU. The maximum turbidity level was 252 NTU. The 

Mississippi River exceeded the turbidity standard of 150 NTU in two percent of the 

samples analyzed.

The average fecal coliform concentration in the Mississippi River was 297 cfu/100ml. 

This average value is greater than the value of 200 cfu/100ml for the primary contact 

recreation standard, which is exceeded in 18 percent of the samples. The comparison of 

the observed bacteria densities in the Mississippi River to the state shellfish harvesting 

standards, fecal coliform median most probable number (MPN) shall not exceed 14 fecal 

coliform cfu/100 ml, and not more than 10 percent of the samples shall exceed a MPN of 

43 cfu/100 ml. The fecal coliform concentrations exceed 43 cfu/100ml in 83 percent of 

the samples for the Mississippi River.

Agricultural and industrial chemicals, such as pesticides and volatile and semi-volatile 

organic compounds (VOCs), are discharged to surface waters from several sources and 

make their way into the Mississippi River. Several pesticides in the Mississippi River 

exceed Louisiana freshwater chronic and acute criteria. Chemicals such as 

organochlorine insecticides: DDT, DDE, chlordane, dieldrin, endrin heptachlor, and 

toxaphene are detected frequently.

Data for unfiltered concentrations of trace metals and trace inorganics indicate that high 

trace metal concentrations are associated with suspended particulates in the River. The 

trace metals lead, mercury, copper and chromium have been detected at average 

concentrations of 2.66, 0.12, 6.62 and 3.27 μg/l respectively. Such high concentrations 

are indicative of the impact of industrial and urban stormwater discharges to the River. 

The trace metals lead, mercury, copper, and chromium consistently exceed the freshwater 

chronic criteria. Data also indicates potential problems associated with recurrent high 

concentrations of copper and chromium, which exceed the acute criteria.

3.7.1.2 Central Wetlands Area Existing Water Quality

The general water quality statistics for the Central Wetlands area over the time period of 

1990 to 2010 from aggregated samples (USACE, 2010) are presented in table 3-5. The 

Central Wetlands area, shown on figure 3-31 in section 3.24.2.1, is a large tract of tidal 

marsh habitat located within the hurricane levee protection system between the MRGO 

and communities along the Mississippi River in St. Bernard Parish. DO concentrations 

fluctuate widely, with values ranging from 1.01 mg/l to 12.73 mg/l. Measured DO in the 

Central Wetlands area averaged 6.1 mg/l during the period of 1990 to 2010, and 

violations of the State DO standard of 4.0 mg/l were noted in 24 percent of the 240 

observations reported. The State of Louisiana has not published numerical standards for 

CL, SO4 and TDS. A pH range of 6.5 to 9.0 and temperature criteria of 95°F have been 

established by the State of Louisiana for this water segment (table 3-5). Data were not 

available for chloride at the stations and time period of this investigation. The average 

water temperature was 72°F with a maximum of 90°F. The average sulfate concentration 
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FEIS MRGO Ecosystem

Restoration Plan 3-20 June 2012

was 836 mg/l, and values were reported up to 2,756 mg/l. The pH averaged 7.3 with a 

range from 6.28 to 8.24. TDS averaged 9,822 mg/l with a maximum value of 22,460 

mg/l. The specific conductance averaged 15,786 μmhos/cm with a range of 227 

μmhos/cm to 30,900 μmhos/cm. Therefore, the Central Wetlands area fluctuates 

between freshwater and brackish to marine salinity. 

Table 3-5: Central Wetlands Area Group General Summary Statistics from 1990-2010

General Units Mean

Number of 

Observations Max Median Min

Dissolved Oxygen mg/l 6.11 240 12.7 5.8 1.01

Water Temperature F 71.6 248 89.9 74.3 44.1

Sulfate mg/l 836 248 2,756 789 38.6

Total Dissolved Solids mg/l 9,822 248 22,460 9,730 72.0

pH SU 7.34 248 8.2 7 6.28

Specific Conductance, 

Field μmhos/cm 15,786 240 30,900 15,600 227

Nitrate+Nitrite Nitrogen mg/l 0.16 193 1.7 0.08 0.01

Total Organic Carbon mg/l 9.99 144 28.9 8.5 2.0

Turbidity NTU 13.29 248 140 11.0 1.0

Total Suspended Solids mg/l 23.93 248 260 18.8 4.0

SOURCE: USACE, 2010.

The average NOx concentration in the Central Wetlands area was 0.157 mg/l with values 

ranging from 0.01 mg/l to 1.72 mg/l. The average total organic carbon was 9.97 mg/l

with a maximum of 28.9 mg/l. The suspended sediment concentration averaged 24 mg/l, 

and the turbidity averaged 13 NTU during the period 1990 through 2010. The maximum 

turbidity level was 140 NTU. The maximum turbidity level established by the State of 

Louisiana for estuarine lakes, bays, bayous, and canals is 50 NTU. The Central Wetlands 

area exceeded this criterion in two percent of the 248 samples collected. 

The sanitary quality of the waters in the Central Wetlands area, as characterized by 

observed fecal coliform bacteria densities, was 92 cfu/100ml, and the primary contact and 

oyster propagation standards were exceeded (five percent and 44 percent respectively). 

Several pesticides have been detected in the Central Wetlands area. It is important to 

note that the Central Wetlands area is not designated for drinking water or oyster 

propagation. Additionally, vinyl chloride was found to exceed the drinking water supply 

in 100 percent of the samples. No pesticide concentrations exceeded the acute or chronic 

aquatic life criteria for freshwater, marine, or brackish water in the Central Wetlands 

area. However, 1,2-dichloroethane was found to exceed the human health standards for 

drinking water supply in three percent of the samples. Several trace metals have been 

detected in the Central Wetlands area. Mercury and lead exceeded the chronic freshwater 

aquatic life criteria (100 percent and one percent respectively). Additionally, mercury 

exceeded the marine and brackish chronic criteria. 

 
Chapter 3 Affected Environment

FEIS MRGO Ecosystem

Restoration Plan 3-21 June 2012

3.7.1.3 Mississippi River Gulf Outlet (MRGO) Existing Water 

Quality

The general water quality statistics for the MRGO, over the time period of 1990 to 2010, 

from aggregated samples (USACE, 2010) are presented in table 3-6. DO concentrations 

are relatively stable with values ranging from 4.48 mg/l to 10.4 mg/l. During this period, 

violations of the State DO standard of 5.0 mg/l were noted in 9 percent of the 23 

observations reported. The State of Louisiana has not published numerical standards for 

CL, SO4, pH, and TDS. A pH range of 6.5 to 9.0 and temperature criteria of 95°F have 

been established by the State of Louisiana for this water segment. Data were not 

available for chloride at the stations and time period of this investigation. The average 

water temperature was 73°F with a maximum of 90°F. The average sulfate concentration 

was 1,709 mg/l, and values were reported up to 8,912 mg/l. The pH averaged 7.72 with a 

range from 7.33 to 8.36. TDS averaged 15,823 mg/l with a maximum value of 23,340 

mg/l. The specific conductance averaged 23,970 μmhos/cm with a range of 16,680 

μmhos/cm to 34,350 μmhos/cm; therefore, the MRGO fluctuates from brackish to marine 

salinity. 

Table 3-6: MRGO Group General Summary Statistics from 1990-2010

General Units Mean

Number of 

Observations Max Median Min

Dissolved Oxygen mg/l 7.34 23 10.40 6.91 4.48

Water Temperature F 73.5 23 89.7 72.9 40.9

Sulfate mg/l 1,709 23 8,912 1,251 826

Total Dissolved Solids mg/l 15,823 23 23,340 15,440 11,120

pH SU 7.72 23 8.36 7.68 7.33

Specific Conductance, 

Field μmhos/cm 23,970 23 34,350 23,410 16,680

Nitrate+Nitrite Nitrogen mg/l 0.08 12 0.27 0.06 0.02

Total Organic Carbon mg/l 6.96 16 10.40 6.80 5.20

Turbidity NTU 9.50 23 19.00 8.20 2.60

Total Suspended Solids mg/l 19.23 23 40.50 19.30 4.00

SOURCE: USACE, 2010.

The average NOx concentration in the MRGO was 0.078 mg/l with values ranging from 

0.02 mg/l to 0.27 mg/l. The average total organic carbon was 6.96 mg/l with a maximum 

of 10.4 mg/l. The suspended sediment concentration averaged 19 mg/l, and the turbidity 

averaged 9.5 NTU during the period 1990 through 2010. The maximum turbidity level 

was 19 NTU. The maximum turbidity level established by the State of Louisiana for 

estuarine lakes, bays, bayous, and canals is 50 NTU. The MRGO did not exceed this 

criterion in any of the 23 samples collected.

The sanitary quality of the waters in the MRGO, as characterized by observed fecal 

coliform bacteria densities, was 17 cfu/100ml, and the oyster propagation standard was 

exceeded in eight percent of samples. Several pesticides have been detected in the 

MRGO. No pesticide concentrations exceeded the acute or chronic aquatic life criteria 

for freshwater, marine, or brackish water in the MRGO. Several trace metals have been 
Chapter 3 Affected Environment

FEIS MRGO Ecosystem

Restoration Plan 3-22 June 2012

detected in the MRGO; however, only mercury exceeded the chronic freshwater, marine, 

and brackish aquatic life criteria. 

3.7.1.4 Lake Borgne Wetlands Area Existing Water Quality

The general water quality statistics for the Lake Borgne Wetlands Area (LBWA), over 

the time period of 1990 to 2010, from aggregated samples (USACE, 2010) are presented 

in table 3-7. DO concentrations were relatively constant with values ranging from 4.17 

mg/l to 11.33 mg/l. Measured DO in the LBWA averaged 7.5 mg/l during the period of 

1990 - 2010. During this period, violations of the State DO standard of 4.0 mg/l were not 

noted in the 108 observations reported. The State of Louisiana has not published 

numerical standards for CL, SO4, and TDS. A pH range of 6.5 to 9.0 and temperature 

criteria of 95°F has been established by the State of Louisiana for this water segment. 

Data were not available for chloride at the stations and time period of this investigation. 

The average water temperature was 72°F with a maximum of 90°F. The average sulfate 

concentration was 807 mg/l, and values were reported up to 1,691 mg/l. The pH 

averaged 7.5 with a range from 6.39 to 8.04. TDS averaged 10,318 mg/l with a 

maximum value of 18,880 mg/l. The specific conductance averaged 15,984 μmhos/cm 

with a range of 21.5 to 28,600 μmhos/cm; therefore the LBWA fluctuates from 

freshwater to marine salinity. 

The average NOx concentration in the LBWA was 0.10 mg/l with values ranging from 

0.05 mg/l to 0.55 mg/l. The average total organic carbon was 7.5 mg/l with a maximum 

of 20.6 mg/l. The suspended sediment concentration averaged 20 mg/l, and the turbidity 

averaged 11 NTU during the period 1990 through 2010. The maximum turbidity level 

was 36.5 NTU. The maximum turbidity level established by the State of Louisiana for 

estuarine lakes, bays, bayous, and canals is 50 NTU. The LBWA did not exceed this 

criterion in any of the 248 samples collected.

Table 3-7: LBWA Group General Summary Statistics from 1990-2010

General Units Mean

Number of 

Observations Max Median Min

Dissolved Oxygen mg/l 7.55 108 11.33 7.22 4.17

Water Temperature F 71.1 108 89.5 73.3 46.2

Sulfate mg/l 806.94 108 1,691 768.50 375

Total Dissolved Solids mg/l 10,319 107 18,880 9,840 4,724

pH SU 7.52 108 8.04 7.53 6.39

Specific Conductance, 

Field μmhos/cm 15,985 107 28,600 15,270 21.5

Nitrate+Nitrite Nitrogen mg/l 0.10 47 0.55 0.08 0.05

Total Organic Carbon mg/l 7.54 51 20.6 7.0 2.0

Turbidity NTU 10.82 108 36.5 9.0 3.2

Total Suspended Solids mg/l 19.97 108 81.0 16.0 4.0

SOURCE: USACE, 2010.

 

The sanitary quality of the waters in the LBWA, as characterized by observed fecal 

coliform bacteria densities, was 36 cfu/100ml with oyster propagation standard exceeded 
Chapter 3 Affected Environment

FEIS MRGO Ecosystem

Restoration Plan 3-23 June 2012

in 21 percent of the 102 samples collected. Several pesticides have been detected in the 

LBWA. No pesticide concentrations exceeded the acute or chronic aquatic life criteria 

for freshwater, marine, or brackish water in the LBWA. However, 1,2-dichloroethane 

and carbon tetrachloride were both found to exceed the human health standards for 

drinking water supply in 10 percent of the samples. Several trace metals have been 

detected in the LBWA; however, no trace metals exceeded the numerical criteria 

established by the State. 

3.7.1.5 Lake Borgne Existing Water Quality

The general water quality statistics for Lake Borgne, over the time period of 1990 to 

2010, from aggregated samples (USACE, 2010) are presented in table 3-8. DO 

concentrations were relatively constant with values ranging from 5.67 mg/l to 10.71 mg/l, 

which is expected as the flushing time averages 17 days. Measured DO in Lake Borgne 

averaged 7.8 mg/l during the period of 1990- 2010. During this period, violations of the 

State DO standard of 5.0 mg/l were not observed in the 23 observations reported. The 

State of Louisiana has not published numerical standards for CL, SO4, and TDS. A pH 

range of 6.5 to 9.0 and temperature criteria of 95°F have been established by the State of 

Louisiana for this water segment. Data were not available for chloride at the stations and 

time period of this investigation. The average water temperature was 72°F with a 

maximum of 87°F. The average sulfate concentration was 626 mg/l, and values were 

reported up to 2,033 mg/l. The pH averaged 7.4 with a range from 6.91 to 7.83. TDS 

averaged 7,391 mg/l with a maximum value of 15,700 mg/l. The specific conductance 

averaged 11,830 μmhos/cm with a range of 1,256 μmhos/cm to 26,100 μmhos/cm; 

therefore, Lake Borgne fluctuates from brackish to marine water conditions. 

Table 3-8: Lake Borgne Group General Summary Statistics from 1990-2010

General Units Mean

Number of 

Observations Max Median Min

Dissolved Oxygen mg/l 7.84 23 10.71 7.61 5.67

Water Temperature F 71.6 23 87.4 74.2 46.6

Sulfate mg/l 626 24 2,033 497 1.30

Total Dissolved Solids mg/l 7,391 24 15,700 6,279 2,068

pH SU 7.36 23 7.83 7.38 6.91

Specific Conductance, 

Field μmhos/cm 11,830 23 26,100 9,520 1,256

Nitrate+Nitrite Nitrogen mg/l 0.08 14 0.14 0.08 0.05

Total Organic Carbon mg/l 7.19 17 9.4 7.1 5.3

Turbidity NTU 11.76 24 50 8.8 2.8

Total Suspended Solids mg/l 18.06 23 72 14.0 4.5

SOURCE: USACE, 2010.

The average NOx concentration in Lake Borgne was 0.084 mg/l with values ranging from 

0.05 mg/l to 0.14 mg/l. The average total organic carbon was 7.2 mg/l with a maximum 

of 9.4 mg/l. The suspended sediment concentration averaged 18 mg/l, and the turbidity 

averaged 12 NTU during the period 1990 through 2010. The maximum turbidity level 

was 50 NTU. The maximum turbidity level established by the State of Louisiana for 
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FEIS MRGO Ecosystem

Restoration Plan 3-24 June 2012

estuarine lakes, bays, bayous, and canals is 50 NTU. Lake Borgne did not exceed this 

criterion in any of the 24 samples collected.

The sanitary quality of the waters in Lake Borgne, as characterized by observed fecal 

coliform bacteria densities, was 18 cfu/100ml, and the oyster propagation standard was 

exceeded in nine percent of the 23 samples collected. Several pesticides have been 

detected in Lake Borgne; however, no pesticide concentrations exceeded the acute or 

chronic aquatic life criteria for freshwater, marine, or brackish water in Lake Borgne. 

Vinyl chloride was found to exceed the drinking water supply in 100 percent of the 

samples. Several trace metals have been detected in Lake Borgne; however, no trace 

metals exceeded the numerical acute or chronic aquatic life criteria established for 

freshwater, marine, or brackish water. 

3.7.1.6 Biloxi Marsh Existing Water Quality

The general water quality statistics for Biloxi Marsh, over the time period of 1990 to 

2010, from aggregated samples (USACE, 2010) are presented in table 3-9. DO 

concentrations were relatively constant with values ranging from 4.35 mg/l to 11.33 mg/l. 

Measured DO in the Biloxi Marsh averaged 7.3 mg/l during the period of 1990 to 2010. 

During this period, violations of the State DO standard of 4.0 mg/l were not observed in 

the 138 observations reported. The State of Louisiana has not published numerical 

standards for CL, SO4, and TDS. A pH range of 6.5 to 9.0 and temperature criteria of 

95°F has been established by the State of Louisiana for this water segment. Data were 

not available for chloride at the stations and time period of this investigation. The 

average water temperature was 73°F with a maximum of 90°F. The average sulfate 

concentration was 1,569 mg/l, and values were reported up to 3,837 mg/l. The pH 

averaged 7.7 with a range from 6.25 to 8.58. TDS averaged 18,130 mg/l with a 

maximum value of 36,860 mg/l. The specific conductance averaged 27,210 μmhos/cm 

with a range of 21 μmhos/cm to 43,500 μmhos/cm; therefore, the Biloxi Marsh fluctuates 

from a brackish to marine water body. 

Table 3-9: Biloxi Marsh Group General Summary Statistics from 1990-2010

General Units Mean

Number of 

Observations Max Median Min

Dissolved Oxygen mg/l 7.26 138 11.33 6.81 4.35

Water Temperature F 73.0 138 89.3 76.4 37.6

Sulfate mg/l 1,569 138 3,837 1,455 186.00

Total Dissolved Solids mg/l 18,130 138 36,860 18,220 7,700

pH SU 7.77 138 8.58 7.80 6.25

Specific Conductance, 

Field μmhos/cm 27,210 138 43,500 27,240 21.30

Nitrate+Nitrite Nitrogen mg/l 0.11 72 0.80 0.05 0.03

Total Organic Carbon mg/l 6.57 76 10.30 6.45 0.52

Turbidity NTU 14.82 138 60.00 12.00 1.50

Total Suspended Solids mg/l 29.91 137 133.00 22.50 0.30

SOURCE: USACE, 2010.
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Restoration Plan 3-25 June 2012

The average NOx concentration in the Biloxi Marsh was 0.106 mg/l with values ranging 

from 0.03 mg/l to 0.8 mg/l. The average total organic carbon was 6.6 mg/l with a 

maximum of 10.3 mg/l. The suspended sediment concentration averaged 30 mg/l, and 

the turbidity averaged 15 NTU during the period 1990 through 2010. The maximum 

turbidity level was 60 NTU. The maximum turbidity levels established by the State of 

Louisiana for estuarine lakes, bays, bayous, and canals are 50 NTU. The Biloxi Marsh 

exceeded this criterion in three percent of the 138 samples collected.

The sanitary quality of the waters in the Biloxi Marsh, as characterized by observed fecal 

coliform bacteria densities, was 11 cfu/100ml, and the oyster propagation standard was 

exceeded in four percent of the 144 samples collected. Several pesticides have been 

detected in the Biloxi Marsh; however, no pesticide concentrations exceeded the acute or 

chronic aquatic life criteria for freshwater, marine, or brackish water in the Biloxi Marsh. 

Vinyl chloride was found to exceed the drinking water supply in 100 percent of the 

samples. Several trace metals have been detected in the Biloxi Marsh; however, only 

mercury exceeded the chronic freshwater, marine, and brackish aquatic life criteria. 

 

3.7.1.7 Mississippi Territorial Waters Existing Water Quality

A survey was taken in 2005, Water Quality Study of Bays in Coastal Mississippi (EPA, 

2005), to provide water quality information for each of the major bay systems feeding 

Mississippi Sound. Water quality sampling, in-situ monitoring, and sediment sampling 

were conducted at selected stations within each bay or riverine system to provide an 

estimate of pollutant concentrations. The sampling area (see figure 3-6) encompassed 

four major bay systems on the Mississippi Coast including Bayou Casotte (including 

Bangs Lake), the Pascagoula/West Pascagoula River systems, the Back Bay of Biloxi, 

and St. Louis Bay (including Bayou Caddy, and the Pearl River). Table 3-10 shows the 

water quality indicators taken from several sample points in the Mississippi coastal area. 
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Restoration Plan 3-26 June 2012

Table 3-10: Mississippi Coastal Area Water Quality Indicators

System Station

Dissolved 

Oxygen (mg/l) Salinity (ppt) pH

Total Nitrogen 

(mg/l)

Total Phosphorus 

(mg/l)

Bangs Lake BL1 6.38 23.54 7.47 0.81 0.18

Bayou Casotte BC1 4.61 29.2 7.86 0.31 0.21

Bayou Casotte BC2 4.54 29.1 7.78 0.266 0.54

Bayou Casotte BC3 4.32 29.4 7.77 0.315 0.38

Bayou Casotte BC4 11.46 25 7.81 1.955 17

W. Pascagoula River WPR1 5.35 4.07 7.48 0.44 0.05

W. Pascagoula River WPR2 4.48 10.43 6.47 0.54 0.036

Pascagoula River PR1 4.94 28.53 7.8 0.346 0.087

Pascagoula River PR2 4.1 2.86 7.02 0.532 0.052

Escatawpa River ER1 4.12 24.1 7.69 0.5 0.063

Escatawpa River ER2 2.54 7.2 6.66 0.589 0.041

Back Bay of Biloxi BBB1 6.33 15.07 7.88 0.73 0.04

Back Bay of Biloxi BBB2 6.25 12.76 7.49 0.77 0.041

Back Bay of Biloxi BBB3 6.24 8.66 7.33 1.25 0.046

Back Bay of Biloxi BBB4 6.03 4.32 7.03 0.87 0.049

Back Bay of Biloxi BBB5 5.46 5.01 6.94 1.041 0.033

Back Bay of Biloxi BBB6 3.32 3.2 6.9 1.51 0.14

St. Louis Bay SLB1 7.09 15.24 7.8 0.6 0.03

St. Louis Bay SLB2 8.03 13.82 7.87 0.73 0.036

St. Louis Bay SLB3 7.59 14.34 7.8 0.76 0.54

St. Louis Bay SLB4 7.21 12.55 7.67 0.72 0.031

St. Louis Bay SLB5 7.73 12.02 7.84 0.7 0.026

St. Louis Bay SLB6 5.91 11.57 7.63 0.81 0.026

St. Louis Bay SLB7 7.34 10.55 7.78 0.77 0.025

Wolf River WR1 7.49 14.27 7.35 0.77 0.061

Jordan River JR1 6.74 6.5 6.88 1.04 0.032

Bayou La Croix BLC1 4.04 7.41 7.11 0.76 0.029

Bayou Caddy BCD1 6.16 9.15 7.49 1.04 0.093

Pearl River Pearl1 3.9 2.22 6.91 0.78 0.062

SOURCE: EPA, 2005.
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Restoration Plan 3-27 June 2012

Figure 3-6: Site Location Map – Gulf Coast Water Quality Monitoring

Results of the survey of coastal Mississippi showed few detectable priority pollutant 

compounds in the surveyed bays and rivers. In general, the compounds present in surface 

waters were low in concentrations compared to EPA National Ambient Water Quality 

Criteria for priority toxic pollutants. In addition to this report done by the EPA, the State 

of Mississippi conducts its own water quality assessment for all surface waters in the 

state. Data for the pertinent rivers that drain into the Mississippi Sound was taken from 

the State of Mississippi Water Quality Assessment 2008 Section 305(b) Report (MDEQ, 

2008). The area of interest summarized below covers the southern edge of Mississippi's 

contiguous land mass, which borders the Mississippi Sound, and the coastline along the 

Mississippi Sound, totaling approximately 84 linear miles. The total area of estuarine 

waters is approximately 758 square miles. This area includes the St. Louis Bay, Back 

Bay of Biloxi, Pascagoula Bay, and Mississippi Sound. As noted earlier, the MDEQ 

assesses three categories for water use under Mississippi State Code of 1972, as 

amended. 

These three categories include Shellfish Propagation, Recreational Use, including 

Primary and Secondary Contact Recreation, and Fish and Wildlife Usage. Table 3-11

lists the water bodies that influence water quality in the Mississippi Sound, their uses, and 

assessment status.
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Restoration Plan 3-28 June 2012

Table 3-11: 2008 Mississippi Water Quality Assessment – 303(d) List

Water Body Name Use Assessment Status

Bayou Casotte Aquatic Life Support Not Attaining

Biloxi River Aquatic Life Support Attaining

Bay St. Louis Beach Primary Contact Recreation Not Attaining

Biloxi Beach Primary Contact Recreation Attaining

Gulfport Beach Primary Contact Recreation Not Attaining

Wolf River Aquatic Life Support Attaining

East Pascagoula River Fish Consumption Not Attaining

Escatawpa River Secondary Contact Recreation

Fish Consumption

Attaining

Not Attaining

West Pascagoula River Fish Consumption Not Attaining

Pearl River Primary Contact Recreation

Fish Consumption

Attaining

Attaining

SOURCE: MDEQ, 2008.

3.7.2 Altered Hydrology

The MRGO extends approximately 70 miles from Breton Sound to eastern New Orleans, 

and traverses wetlands and marshes in Plaquemines, St. Bernard, and eastern Orleans 

Parishes. A hydrologic study across areas of the current channel was conducted from 

1959 to 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. 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 between Breton Sound and

Lake Borgne (Wicker et al., 1982).

Prior to construction of the MRGO, typical tidal flow from the Breton Sound area was 

reduced as it moved across the marshes and wetlands inward toward Lake Borgne 

(USACE, 2004). Concurrent tidal flow into and across Lake Borgne toward Shell Beach 

did not encounter similar forces of resistance and arrived at Shell Beach with more 

energy relative to the inward tidal flow originating from the Breton Sound area 

(Rounsefell, 1964). The present circulation and tidal flow patterns across this area are 

typically inward from Breton Sound and appear to closely resemble a reversal of the 

earlier circulation patterns that characterized this area prior to construction of the MRGO.

There are a number of factors resulting from construction of the MRGO that have 

contributed to the alteration of circulation patterns and water quality along the length of 

the MRGO and outward into the surrounding wetlands and marshes. The MRGO 

provides a more direct flow of more saline, higher density water inland toward areas of 

Plaquemines, St. Bernard, and eastern Orleans Parishes (Wicker et al., 1981). At high 

tide, the MRGO provides a direct passage for tidal exchange and allows any freshwater 

surpluses to exit regularly at low tide and be replaced by the inflow of more saline water. 

The reduced integrity of the Bayou La Loutre Ridge, as a basin boundary, since 

construction of the MRGO has significantly altered circulation patterns in areas along the 
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Restoration Plan 3-29 June 2012

lower southeastern length of the channel and across areas between Breton Sound and 

Lake Borgne.

Dredging performed for construction of the MRGO to an approximate depth of 36 feet 

resulted in the generation of an abundance of dredge material. In most areas, the dredge 

material was deposited in a continuous strip along the channel’s southwestern limits. 

Dredge material deposition interrupted the local circulation patterns of natural waterways 

that transect areas along the length of the MRGO. This disruption of water flow caused 

wetlands on the southwestern side of the dredge material to become semi-impounded 

(Wicker et al., 1982). 

The de-authorization of the MRGO from the Gulf of Mexico to Mile 60 at the southern 

bank of the GIWW and construction of the authorized MRGO closure structure at Bayou 

La Loutre; a flood control sector gate and bypass barge gate on the GIWW; a new 

navigable flood control sector gate at Bayou Bienvenue; and a braced concrete wall 

across the MRGO located southeast of the existing Bayou Bienvenue flood control 

structure and across the marsh (Golden Triangle area) between these waterways have 

already begun and will continue to affect the salinity levels within the project area. Since 

the closure of the MRGO at Bayou La Loutre, there have been noticeable decreases in 

salinity levels recorded in the MRGO, Lake Borgne, Central Wetlands area, and even into 

Lake Pontchartrain. While the decrease in salinity has changed water quality, it could 

also result in the long-term effect of changing some of the marsh habitat types in the 

Central Wetlands and Lake Borgne. Along with the decrease in salinity, a sharp increase 

in hypoxic and anoxic conditions in the MRGO has also been noted since the 

construction of the closure at Bayou La Loutre. It is believed that these hypoxic and 

anoxic conditions are the result of decreased water movement and turnover since the 

closure was constructed. Hypoxic conditions or hypoxia is a phenomenon that occurs in 

aquatic environments as DO becomes reduced in concentration to a point detrimental to 

aquatic organisms living in the system. When the DO concentration is in the range 

between one percent and 30 percent, the water body is classified as hypoxic. An aquatic 

system lacking DO (zero percent saturation) is termed anoxic. 

3.7.2.1 MRGO Salinity

Over the past 6,000 to 7,000 years, salinity in the project area has shifted with the major 

deltaic meandering of the Mississippi River. Modern efforts to control flooding and 

improve navigation include numerous bank stabilization, channel alignment, dredging, 

lock, dam, levee, and spillway projects on the Mississippi River. Such alterations to the 

Mississippi River and surrounding wetlands have increased salinity in the project area by 

altering the flow of freshwater in the region (LCA, 2004). 

The influence of the MRGO on traversed areas and outward into surrounding wetlands, 

marshes, and waterways was determined by the USACE by comparing the findings of 

investigations conducted prior to channel construction with data collected from these 

same areas following completion of construction activities (USACE, 1999). Alteration of 

salinity in waters along the channel and outward in adjacent areas was first observed in 
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Restoration Plan 3-30 June 2012

studies conducted immediately following channel construction (USACE, 1962). 

Observations indicated that the influx of more saline water into these areas following 

MRGO construction provided a salinity increase that has fluctuated over time. The 

magnitude of this increase in salinity across the subjected areas are typically a function of 

numerous hydrological and ecological factors that include the intensity of saline water 

influx, variation in circulation patterns, and the sensitivity of the habitat within the 

impacted area.

Mean annual salinity data collected from stations that have been influenced by the influx 

of more saline waters since construction of the MRGO is presented in table 3-12. 

Table 3-12: Mean Salinity Data from Stations Affected by MRGO

Yearly Average Salinity (ppt) and Ranges

Year

Lake Borgne Lena's Lagoon Stump Lagoon Lake Eloi

Avg Range Avg Range Avg Range Avg Range

1960-61 5 3-8 7.5 3.5-15 --- --- 18 7-31

1961-62 4 1-9 8 1-17.5 9 3-22 11.5 2-17.5

1962-63 10.5 7-14 16 11-26 20 17-24 24.5 18-31

1963-64 4 1-8.5 12 9-16 15 10.5-18 21.5 15-31

1964-65 7 3-10 12 7-16 13 6-18.5 14 8-23

1965-66 10 6-18 14 8-20 16 6.5-20 15 8-21

1966-67 10 5-13 13.5 4.5-19 14.5 11-19.5 16 10-24

1967-68 10 7.5-13.5 14 8.5-19 14 10-18 16 10-21

2001 5.2 2.6-9.5 --- --- --- --- 16.6 12-21.5

The locations of Lake Eloi, Stump Lagoon, Lena Lagoon, and Lake Borgne are shown on 

figure 3-7. Mean annual salinity data for the period from 1960 to 1968 are based upon 

discrete sampling at three week intervals and demonstrates an observed net increase in 

salinity following channel construction (Fontenot and Rogillio, 1970). Variations in 

salinity increases appears to be dependent upon the initial salinity of the area prior to 

construction activities and highly influenced by the influx migration distance within the 

channel and outward beyond the channel limits into various energy absorbing habitats. 

Lake Eloi located along the southeastern region of the channel has shown minimal 

fluctuations in salinity over time due to its proximate location to the more saline source 

waters of inland tidal flow and the maintenance of circulation patterns. The observed 

salinity variations at Stump Lagoon and Lena Lagoon display the direct influence from 

the influx of more saline waters across these areas. Fluctuations in the salinity of Lake 

Borgne appear to be influenced by rainfall and tidal flow from the southeast and less 

influenced by the MRGO and altered water circulation patterns.

 SOURCES: Fontenot and Rogillio, 1970; LDEQ, 2001.
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Restoration Plan 3-31 June 2012

Figure 3-7: Primary Area Station Locations 
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Restoration Plan 3-32 June 2012

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) (appendix V). MRGO channel construction, the dredging of the 

channel and placement of dredged material, resulted in the conversion of 19,400 acres of 

wetlands and 4,750 acres of shallow open water to deep open water or dredge material 

banks. 

Further data, demonstrating the influence of construction of the MRGO on the salinity 

regime at monitoring stations located throughout the length of the channel, are presented 

in table 3-13. A comparison of data prior to channel construction and following 

completion of construction demonstrates the steep increase in salinity, which has resulted 

from the influx of more saline waters inland along the deepened channel passageway. 

Salinity data from LDEQ monitoring stations, where available, indicates that the 

influence of the channel in these areas continues to occur. The inland reduction of 

salinity in areas along the channel appears to be primarily determined by the distance of 

influx from the more saline source waters. The IHNC receives input from the MRGO via 

the GIWW and flows into Lake Pontchartrain. Monthly salinity data in 2001 for the 

IHNC had a mean value of 6.5 parts per thousand (ppt) (LDEQ, 2001) and appeared 

similar to surface salinity in areas of Lake Pontchartrain near the entrance of the IHNC 

(Schurtz and St. Pe’, 1984). 

Table 3-13: MRGO Influence on Salinity Regime

Yearly Average Salinity (ppt) Pre and Post MRGO

Station 

Pre-MRGO Post-MRGO

1959-1961 1962-1964 2001

Bayou Bienvenue 1.62 10 8

Bayou Dupre 2.39 7.8 9.3

Shell Beach 3.5 11.8 ---

Hopedale 4.5 13 ---

Bayou La Loutre 5.5 13.5 14.1

Lake Athansio 14.2 21.5 ---

Lake Fortuna 16.8 21.5 ---

In January 2009, construction began on a rock closure structure that was placed across 

the MRGO just to the south of the intersection of the MRGO and Bayou La Loutre. 

Since the closure’s completion in July 2009, there have been significant changes in the 

salinity in the MRGO as well as adjoining water bodies in the project area. Salinity 

levels in the MRGO have decreased substantially, with lower salinity numbers also 

observed in the GIWW, Lake Borgne, and Lake Pontchartrain, as well as adjoining marsh 

habitat including the Central Wetlands area. Table 3-14 displays the yearly average 

salinity for certain areas of the project area before and after the construction of the 

closure based on model results from August of 2009. 

SOURCES: Amstutz 1964; LDEQ 2001; Kerlin, 1979
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Restoration Plan 3-33 June 2012

Table 3-14: MRGO Closure Influence on Salinity Regime

Yearly Average Salinity (ppt) Pre and Post MRGO Closure

Box Location Pre-Closure Post-Closure % Change

MRGO at Bayou La Loutre 17.01 8.87 48%

Lake Borgne 8.16 5.62 32%

Central Wetlands 14.67 5.26 64%

GIWW 14.72 5.07 66%

Lake Pontchartrain 6.12 4.01 35%

Along with substantial changes in salinity, a hypoxic zone has also developed as a result 

of the closure structure. On the downstream side, a hypoxic zone has developed from the 

closure in the bottom-most 35 plus feet of water, probably in response to lack of water 

movement, with uniform salinity through the water column except near the surface. The 

hypoxic zone on the upstream side of the closure is generally near the bottom of the 

channel, and the oxygen content increases toward the surface. 

 

3.7.2.2 Lake Pontchartrain Salinity

The Lake Pontchartrain estuary is located north of New Orleans and has an approximate 

mean salinity of four ppt and a surface area of 629 square miles (Abadie and Poirrier, 

2000). Lake Pontchartrain receives tidal input of saline waters from eastern estuaries 

through Chef Menteur Pass and the Rigolets, which connect to Lake Borgne and the 

IHNC, which links the lake and the GIWW and MRGO. Since construction of the 

MRGO was completed in 1968, higher saline waters entering Lake Pontchartrain have 

increased salinity in areas of the southern and eastern parts of the lake. 

The higher saline waters that enter Lake Pontchartrain from the IHNC produce salinity 

stratification in the water column, resulting in low bottom DO concentrations in southern 

regions of the estuary (Poirrier, 1978). Salinity stratification in the water column occurs 

when higher saline, denser waters are introduced into lower saline, less dense waters. 

Water entering Lake Pontchartrain from the IHNC is distinctly stratified with denser 

bottom water having higher salinity than that identified in Lake Pontchartrain. Salinity 

stratification and low bottom water DO concentrations are not apparent in the saline 

waters that enter Lake Pontchartrain from the natural tidal passes because of the 

similarity in salinity of these waters and Lake Borgne. 

The presence and degree of salinity stratification in southern regions of Lake 

Pontchartrain appear to be influenced by vertical mixing from wind action and the 

movement of water in and out of the IHNC. A direct correlation has been developed 

between established salinity stratification and low DO concentration in the bottom waters 

of Lake Pontchartrain (Schurtz and St. Pe’, 1984). DO concentrations appear at their 

lowest levels in the summer and fall when salinity stratification is occurring and the 

salinity gradient between bottom and surface water is greatest. A non-mixing condition 

SOURCE: MRGO Closure Report, USACE, 2009.
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Restoration Plan 3-34 June 2012

results from the density difference between the more saline bottom water and the upper 

less saline water in the stratified water column. 

The hypoxic conditions of near-bottom water associated with salinity stratification in the 

overlying water column can affect the diversity and distribution of benthic organisms 

(Junot et al., 1983). The impact on diversity and distribution can be attributed to the 

identified low oxygen levels in near-bottom waters that are associated with salinity 

stratification that occur near the IHNC. Further studies have identified the absence or 

low densities of large Rangia cuneata clams (Rangia clams) from sites located north of 

the IHNC as an indicator that episodic hypoxia, resulting from salinity stratification, has 

affected the establishment of older larger Rangia clams in the area (Abadie and Poirrier, 

2000). 

Station to station differences in bottom salinity and the resulting variation in water 

column stratification appear to vary with depth and distance from the IHNC. The 

importance of wind action on the development of salinity stratification in Lake 

Pontchartrain is seen by the typical seasonal occurrence of stratification across southern 

areas of the estuary in the spring, summer, and fall. During the winter months, strong 

northerly winds across the area promote vertical mixing of the water column and 

diminished stratification. Studies indicate stratified water is seldom identified west of the 

Causeway Bridge, may occur east of the Lakefront Airport, and, under favorable 

conditions, may extend northward by several miles into Lake Pontchartrain (Poirrier, 

1978). Salinity stratification in southern Lake Pontchartrain in the area of the IHNC has 

also been identified in other investigations (Swenson, 1980). 

Salinity stratification has also been identified in greater magnitude in large bottom dredge 

holes (borrow pits) located across the estuary. The water quality dynamics of these 

borrow pits have been investigated and provide additional information on the 

characteristics of more saline water that enters Lake Pontchartrain from the IHNC 

(Franze and Poirrier, 2000). Borrow pits may be dredged to depths in excess of 65 feet. 

The increased water column depth within the area of these pits is characterized by welldefined salinity stratification that is determined by distance from the IHNC. A borrow pit 

investigated in these studies is located approximately 4,000 feet north of the Lakefront 

Airport and displayed well-defined salinity stratification patterns. Studies conducted 

from 1998 to 2000 of this pit area identified surface salinity ranging from 2.4 ppt to 10.8 

ppt and bottom salinity ranging from 15.8 ppt to 24.4 ppt. The variation in spatial surface 

salinity and the gradient of salinity stratification within southern Lake Pontchartrain 

dredge pits is further evidence of the influence of the IHNC and the influx of more saline 

waters on this area of the estuary.

The USACE Engineer Research and Development Center’s 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 (USACE, 2009). In the Historical Salinity section of the report, 

data for five stations in the project area were analyzed. The stations are Pass Manchac 

near Ponchatoula, Lake Pontchartrain at Little Woods, Chef Menteur Pass near Lake 
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Restoration Plan 3-35 June 2012

Borgne, Lake Pontchartrain at North Shore all in the secondary area, and Bayou La 

Loutre at Alluvial City in the primary area. The mean pre- and post-MRGO salinity 

information is from 1951 to 1963 and 1963 to 1977 respectively and is presented in table 

3-15. The table shows that the salinity increased at all five stations throughout the years 

after the MRGO was opened.

 

Table 3-15: Salinity for Pre- and Post-MRGO Salinity (ppt)

Month

Alluvial City Pass Manchac North Shore Little Woods

Chef Menteur 

Pass

Pre Post Pre Post Pre Post Pre Post Pre Post

January 6.8 9.8 1.1 1.5 3.0 4.0 3.8 5.0 3.8 5.7

February 6.4 9.7 1.0 1.5 2.5 3.0 3.0 6.5 2.9 4.8

March 6.3 10.4 1.0 1.2 1.9 2.6 2.3 4.4 2.2 4.3

April 7.0 10.0 0.8 1.3 1.9 2.6 2.4 4.0 2.2 4.0

May 9.5 10.2 1.0 1.1 2.4 2.7 2.2 3.8 2.6 4.0

June 9.0 12.3 1.0 1.5 3.6 3.0 2.2 3.8 3.3 4.2

July 7.9 16.0 1.0 1.6 3.0 4.6 2.1 4.4 3.2 6.3

August 8.6 16.1 1.2 1.7 4.6 5.6 2.5 4.8 4.8 7.5

September 8.2 12.9 1.7 2.0 5.4 7.5 4.5 6.2 6.0 8.5

October 7.6 13.8 1.8 2.2 4.7 7.3 4.9 6.8 5.2 8.4

November 8.0 13.1 1.8 2.1 4.6 6.7 4.8 6.8 5.2 8.0

December 8.0 12.5 1.2 1.8 4.5 5.4 4.7 6.2 4.2 7.0

3.7.2.3 Lake Maurepas Salinity

Lake Maurepas is located at the western end of Lake Pontchartrain. The Manchac 

Landbridge separates the two lakes. Manchac Pass and numerous waterways transect the 

landbridge between Lake Maurepas and the more saline waters of western Lake 

Pontchartrain. Water quality data from 2001 identified increasing salinity in Lake 

Maurepas and the south Maurepas Swamp (Lee Wilson and Associates, Inc. et al., 2001). 

Salinity data records collected from the USACE station at Pass Manchac indicate that 

during the 1998 to 2000 drought period, mean annual salinity was higher than in previous 

years. Salinity increases in Lake Maurepas are supported by comparing mean monthly 

salinity from the 1955 to 1981 period to mean monthly data for the 1998 to 2000 period. 

An average monthly increase of two ppt to three ppt was observed during the two-year 

sampling period. 

The main sources of freshwater input into Lake Maurepas are the Blind River, the 

Tickfaw River, the Amite Diversion Canal, and area rainfall runoff. During the typical 

low rainfall season that occurs from summer to fall, highest mean monthly salinity have 

been identified in Lake Maurepas.

Due to the distance of Lake Maurepas to the IHNC, and from the tidal passes from Lake 

Borgne, the possible impact from the MRGO on the Lake Maurepas area is not clearly 

defined. 

SOURCE: USACE, 2009.
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Restoration Plan 3-36 June 2012

3.7.2.4 Mississippi Territorial Waters Salinity

Six rivers empty into the Mississippi Sound including the Pearl River, Wolf River, Jordan 

River, Biloxi River, and the East and West Pascagoula Rivers. The influx of rivers 

creates a salinity gradient within the 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 from 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 (MsCIP, 

2008). Overall salinity levels within Mississippi Sound are shown in tables 3-16 through

3-18 and give the salinity levels at points which have the greatest influence on the 

Mississippi Sound including St. Louis Bay, Biloxi Bay, and the Pascagoula area. These 

salinity values were taken at sample points throughout the sound and the bays and rivers 

that feed into it and are shown on figures 3-8 through 3-10. 

St. Louis Bay is a small bay in the northwest portion of the Mississippi Sound. The Wolf 

and Jordan Rivers flow into this bay before reaching the Sound, as well as Bayou 

Portage, Bayou La Croix, and Indian Bayou. These waterways constitute the bulk of 

freshwater entering the system. Salinity levels for St. Louis Bay were taken at ten 

stations throughout the bay and two stations southwest of the bay at Bayou Caddy and 

Pearl River in 2005 and are noted in table 3-16 and shown on figure 3-8. 

Table 3-16: Existing Salinity in St. Louis Bay

Station

Depth

(feet)

Salinity (ppt)

Max Average Min

SLB1 11 15.29 15.24 15.21

SLB2 6 14.65 14.04 13.77

SLB3 8 14.51 14.15 13.25

SLB4 4 13.07 12.72 12.5

SLB5 5 12.26 12.11 12.02

SLB6 7 12.83 11.9 11.55

SLB7 5 11.15 10.74 10.53

WR1 4 9.02 8.03 7.06

JR1 9 9.28 882 7.49

BLC1 9 7.72 6.31 5.12

BCD1 9 14.27 14.26 14.27

Pearl1 17 4.26 3.34 2.15

SOURCE: Water Quality Study of Bays in Coastal Mississippi, EPA 2005.
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Figure 3-8: Site Location Map – St. Louis Bay and Associated Waterways 

Biloxi Bay is a long, narrow bay in the central portion of the Mississippi Sound. Bernard 

Bayou and the Biloxi River flow into the bay on the west end, the Tchoutacabouffa River 

enters from the north at the midpoint of the bay, and Old Fort Bayou enters on the eastern 

end just before the bay’s connection with the Sound. These waterways constitute the 

bulk of freshwater entering the system. Salinity levels for Biloxi Bay were taken at six 

stations throughout the bay in 2005 and are noted in table 3-17 and shown on figure 3-9. 

Table 3-17: Existing Salinity in Biloxi Bay

Station

Depth

(feet)

Salinity (ppt)

Max Average Min

BBB1 12 21.52 16.83 13.34

BBB2 11 15.28 12.25 8.59

BBB3 7 11.59 8.83 7.8

BBB4 10 6.75 4.5 4.07

BBB5 9 8.83 5.7 4.13

BBB6 15 4.53 3.38 2.43

SOURCE: Water Quality Study of Bays in Coastal Mississippi, EPA 2005.
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Figure 3-9: Site Location Map – Back Bay of Biloxi 

Pascagoula Bay is actually just a portion of the eastern end of the Mississippi Sound. 

The West Pascagoula River, Pascagoula River, and Escatawpa River empty into the 

Mississippi Sound at Pascagoula Bay. These waterways constitute the bulk of freshwater 

entering the system on the eastern end. Salinity levels for Pascagoula Bay were taken at 

six stations located at various locations on each of the rivers in 2005 and are noted in 

table 3-18 and shown on figure 3-10. 

. 

Table 3-18: Existing Salinity in Pascagoula Bay

Station

Depth

(feet)

Salinity (ppt)

Max Average Min

WPR1 26 25 20.45 5.63

WPR2 28 11.81 5.96 0.72

PR1 40 30.28 26.86 5.2

PR2 23 26.46 14.26 2.21

ER1 23 28.02 18.81 3.69

ER2 19 21.45 13.62 1.8

SOURCE: Water Quality Study in Bays in Coastal Mississippi, EPA 2005.
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Figure 3-10: Site Location Map – Pascagoula, Escatawpa, West Pascagoula Rivers 

3.7.2.5 Lake Pontchartrain Hypoxic/Anoxic Zone

A hypoxic/anoxic (H/A) zone in Lake Pontchartrain was first described by Poirrier 

(1978). Hypoxic conditions or hypoxia is a phenomenon that occurs in aquatic 

environments as DO becomes reduced in concentration to a point detrimental to aquatic 

organisms living in the system. When the DO concentration is in the range between one 

percent and 30 percent, the water body is classified as hypoxic. An aquatic system 

lacking DO (zero percent saturation) is termed anoxic. 

The H/A zone’s existence was verified by extensive water quality sampling done by 

LDEQ in 1980 and 1982 (Schurtz and St. Pe’, 1984). This zone appears to be caused 

primarily because the MRGO carries bottom water in excess of 20 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 

bottom lake currents and can cover at least 1/6 of the lake’s bottom (Schurtz and St. Pe’, 

1984). This stratified water inhibits both mixing and oxygenation, generally leading to 

H/A conditions near the lake bottom. This H/A zone appears most often in the spring and 

summer (Abadie and Poirrier, 2001). 

As a result of the MRGO closure structure, Dr. Poirrier of the University of New Orleans 

(UNO) reports that 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 DO levels. Monitoring conducted 
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by USGS during the late summer and early fall of 2009 of borrow pits along the south 

shore of Lake Pontchartrain indicate that DO at depths below 15 feet dropped to below 

.75 mg/l and lower and salinity averaged approximately 12.7 at depths of 15 feet and 

lower in mid-September 2009 and 7.0 ppt at all depths in October 2009 (appendix S).

3.8 NAVIGABLE WATERWAYS

3.8.1 Historic and Existing Conditions

The major navigation channels in the project area include the Mississippi River Deep 

Draft Navigation Channel, the IHNC, the GIWW and the MRGO. Lake Borgne is 

hydrologically-linked to Lake Pontchartrain through tidal passes at the Rigolets, Chef 

Menteur Pass, and the manmade IHNC. Although the Rigolets and Chef Menteur Pass 

are navigable, they are used mainly by commercial fishing and recreational vessels, as are 

many of the small bayous and canals in the project area.

The Mississippi River Deep Draft Navigation Channel is Federally maintained by the 

USACE to insure navigation in the Mississippi River. The IHNC, connecting the 

Mississippi River and Lake Pontchartrain, was completed in 1923 with the construction 

of the IHNC lock at the Mississippi River. The lock allows for navigation by preventing 

high stages in the Mississippi River from producing strong currents in the channel. In the 

1930s, the GIWW was constructed from the mid-point of the IHNC going east and by 

1949 went west all the way to Brownsville, Texas. 

Other Federally maintained channels in the project area are Bayous Dupre, La Loutre, St. 

Malo and Yscloskey. Bayou Dupre was authorized by the Rivers and Harbors Act of 

1937. The authorization was for a 6-foot deep by 80–foot wide channel from the 

Highway 39 Bridge at Violet to Lake Borgne and thence a 6-foot deep by 100-foot wide 

channel to the 6-foot contour in Lake Borgne. Construction was completed in 1939. The 

7.3 mile channel extended almost two miles out into Lake Borgne. A contemporary 

navigation chart (NOAA chart 11371) shows the channel markers extending about 1.4 

miles into Lake Borgne and the water depths as being 7 feet. Bayous La Loutre, St. 

Malo, and Yscloskey were also authorized by the Rivers and Harbors Act of 1937. These 

are all small depth (5 feet or 6 feet) narrow channels (30 feet or 40 feet) with construction 

completed in 1956. Maintenance dredging has not been required. 

Prior to construction of the MRGO (1958-1968), main navigation channels were the 

IHNC, GIWW, and the Mississippi River. Bayous Bienvenue, Dupre, and La Loutre that 

were part of the remnant tributary system that extended from the Mississippi River 

eastward to the Biloxi Marsh and Mississippi Sound and were used by smaller crafts, 

mostly commercial and recreational fishing. Construction of the MRGO cut thorough 

these bayous. Construction also breached the Bayou La Loutre Ridge resulting in direct 

connection of Lake Borgne to the Gulf of Mexico through Breton Sound. 

The MRGO was completed in 1968 and extended approximately 70 miles from Breton 

Sound to eastern New Orleans, traversing wetlands and marshes in Plaquemines, St. 
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Bernard, and eastern Orleans Parishes. Following completion of construction, the size 

and draft of vessels using the MRGO increased to meet the competitive demand for more 

efficient movements of bulk commodities. With the construction of the Lake 

Pontchartrain and Vicinity Hurricane Protection Project, control structures were 

constructed at Bayous Bienvenue and Dupre to allow tidal flow and navigation while 

maintaining the integrity of the Chalmette Loop Levee System. Structures at Bayous 

Bienvenue and Dupre allow for passage of small recreational and commercial fishing 

vessels into the Central Wetlands where they are home-ported in small marinas and along 

marginal docks along the bayous. 

The MRGO was deauthorized in 2008 and the closure structure near Bayou La Loutre 

was completed in August 2009 resulting in changes to navigation. Hurricane Katrina 

silted in much of the MRGO channel across Breton Sound with the result that large 

vessels are no longer able to transit Breton Sound and reach eastern Orleans Parish. 

Construction of the closure structure on the southern part of the La Loutre Ridge has 

changed navigation in the project area. Instead of a direct route down the MRGO to 

reach Breton Sound or the Gulf of Mexico, vessels must now use the Bayou La Loutre 

channel. Bayou La Loutre is also a Federal channel authorized by the Rivers and Harbors 

Act of 1937. The authorization for Bayous La Loutre, St. Malo and Yscloskey called for 

a channel 5 feet by 40 feet for deep water in Lake Borgne to the shoreline at the mouth of 

Bayou Yscloskey; a channel 6 feet by 40 feet for deep water in Lake Borgne through 

Bayous St. Malo, La Loutre and Eloi to deep water in Lake Eloi (Breton/Chandeleur 

Sound); and a channel 5 feet by 30 feet in Bayou la Loutre between Hopedale and Bayou 

St. Malo. Total length on improvements was 30 miles and all construction was 

completed by 1956. 

Sector gates on the GIWW and Bayou Bienvenue being constructed as part of the 

authorized improvements to the HSDRRS will alter navigation in and near the western 

end of the project area. The operation of the sector gates should have minimal impact on 

passage of vessels, since the structures will remain open except for storm conditions. The 

access construction channel for the storm surge barrier structure will connect the MRGO 

with the GIWW across the Golden Triangle allowing another navigable route for small 

vessels, but this channel will not be a maintained channel. However, the storm surge 

barrier will close off the existing connection. Navigation in the MRGO and the Central 

Wetlands is now relegated to small recreational craft and smaller commercial vessels, 

generally fishing and shrimp boats, small barges and tugs. The use of the MRGO is 

relegated to a conduit between Bayou Dupre and Bayou La Loutre. 

There presently exists a channel (part of the Bayou Dupre authorized channel) that allows 

passage from the MRGO into Lake Borgne. This channel has been reduced to an 

approximately 500 feet width by a recently constructed rock dike structure that was built 

to reduce erosion and restore shoreline along the tangent formed by the MRGO and the 

western shoreline of Lake Borgne.
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3.9 SOILS AND SEDIMENTS

3.9.1 Historic and Existing Conditions 

Soil resources are institutionally significant under the following statutes and memoranda: 

the CEQ Memorandum of August 11, 1980, entitled “Analysis of Impacts on Prime or 

Unique Agricultural Lands in Implementing the NEPA,” EO 11990 – Protection of 

Wetlands; and Agriculture and Food Act of 1981 (Public Law 97-98), which includes the 

Farmland Protection Policy Act (FPPA). Soil plays a significant role in the environment 

because it supports vegetative growth and open-water benthic productivity in coastal 

habitats. This resource is publicly significant because of the high value the public places 

on agricultural production and wildlife supported by the soils in the area. 

Within coastal areas, soils provide a critical biotic component of ecosystems, affecting 

biogeochemical processes, species composition, productivity, and other factors essential 

to ecosystem integrity and functioning (Brady and Weil, 2002; Anderson and Lockaby, 

2007). Soil types in the study area are formed in materials (i.e., gravel, sand, silt, and 

clay) that were deposited over time during seasonal and intermittent flooding events 

(USACE, 2009). Soils with finer textures (fine silts and clay) are predominantly located 

farther away from major waterways than soils dominated by heavier textures (i.e., sands 

and gravels) because the heavier materials drop out of suspension in the water column 

first as flowing water slows down. Therefore, relatively fine textures are often found on 

natural river levees in the backswamp farther away from the river.

The project area includes both hydric and non-hydric soils (NRCS, 2007). Hydric soils 

are saturated all or part of the year and are a defining characteristic of wetlands. 

Somewhat poorly drained, poorly, and very poorly drained soils are typically found in 

topographically lower landscape positions or depressions that are subject to prolonged, 

excessive, or frequent saturation. Lands near or in the outer fringes of the coastal plain 

marshes are usually made up of hydric soils in areas that are temporarily or permanently 

flooded. Somewhat well drained and well drained non-hydric soils are typically found on 

topographically higher landscape positions farther away from open water bodies and 

wetland areas. Figure 3-11 below shows the distribution of hydric soils within the study 

area. An accumulation of organic material in the surface soil horizon, evident across 

most of the project area, is typical of hydric soils due to slow decomposition under 

anaerobic conditions during saturation. Soil samples from Maurepas Swamp had soil 

bulk densities typically seen in fresh and intermediate marshes (lesser salinity than salt 

marshes) and the soil pH was slightly acidic (typical of organic soils with low bulk 

densities) (e.g., Hatton, 1981); higher bulk densities were measured in areas receiving 

agricultural and other runoff (Shaffer et al., 2003). The low bulk densities and 

corresponding high organic matter content were likely the result of insufficient sediment 

input since the leveeing of the Mississippi River. According to the Department of 

Agriculture – Natural Resources Conservation Service (NRCS) soil survey report of the 

Plaquemines and St. Bernard Parishes, the project areas in the middle and lower subbasins consist of mucky clay/muck soils.
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Study Area Soils

The dominate soil series in the Livingston, Plaquemines, St. Bernard, Orleans, and St. 

Tammany Parishes study areas are shown in the table below followed by brief 

descriptions of the major soil types in each (see table 3-19). 

Table 3-19: Dominant Soil Series of the Study Area

Parish Soils

Livingston

Soils on uplands Calhoun, Bude

Soils on streams or marine terraces Colyell, Encrow, Myatt, Satsuma, 

Soils on floodplains Ouachita and Guyton

Soils in Marshes and swamps that are frequently flooded and ponded Barbary, Maurepas

Orleans

Soils on a natural levee protected from flooding Sharkey, Commerce

Soils in Marshes and swamps that are frequently flooded and ponded Clovelly, Lafitte, Gentilly

Soils in former swamps that are drained and protected from flooding Harahan, Westwego, Allemands

Soils on dredge material banks and sandy ridges that are rarely or 

frequently flooded Aquents

Plaquemines

Soils on a natural levee protected from flooding Sharkey, Commerce

Soils in Marshes and swamps that are frequently flooded and ponded

Larose, Kenner, Allemands, Clovelly, 

Lafitte, Gentilly, Bellpass, Timbalier, 

Scatlake

Soils in former swamps that are drained and protected from flooding Harahan, Westwego,

Soils on dredge material banks and sandy ridges that are rarely or 

frequently flooded Aquents

St. Bernard

Soils on a natural levee protected from flooding Sharkey, Commerce

Soils in Marshes and swamps that are frequently flooded and ponded Barbary, Lafitte, Clovelly, Timbalier, 

Bellpass, Scatlake, Fausse

Soils in former swamps that are drained and protected from flooding Harahan, Westwego

Soils on dredge material banks and sandy ridges that are rarely or 

frequently flooded Aquents

St. Tammany

Soils on streams or marine terraces Guyton, Abita, Brimstone

Soils in Marshes and swamps that are frequently flooded and ponded Clovelly, Lafitte, Larose, Allemands, 

Kenner

Soils in former swamps that are drained and protected from flooding Aquents
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Figure 3-11: Distribution of Hydric Soils in Study Area – Pontchartrain Basin and Western Mississippi Sound
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Abita

The Abita series consists of deep, somewhat poorly drained, slowly permeable soils that 

formed in silty sediments on low, broad stream or marine terraces of late Pleistocene age 

with slopes ranging from zero percent to five percent.

Allemands

The Allemands series consists of very deep, very poorly drained, soils that are rapidly 

permeable in the organic materials and very slowly permeable in the underlying clay 

horizons. These soils are on the landward side of low coastal freshwater marshes and 

formed in decomposed herbaceous material over alluvial sediments with slopes ranging 

from zero percent to 0.2 percent. 

Aquents

Aquents are young soils that have very little horizon development. The soils in this 

group are found in marshes and formed in alluvium. They are frequently flooded. They 

are deep (often greater than 80 inches to a restrictive feature) and are very poorly drained.

Barbary

The Barbary series consists of very deep, very poorly drained, very slowly permeable 

soils. These soils formed in geologically recent (less than 10,000 years old) clayey 

sediments that have been deposited in water and are continuously saturated and flooded. 

These soils are mainly on low, broad, ponded backswamps of the lower Mississippi River 

Alluvial Plain with a slope of less than one percent.

Bellpass 

The Bellpass series consists of very deep, very poorly drained, very slowly permeable 

soils that formed in moderately thick herbaceous organic materials overlying clayey 

sediments in saline coastal marshes with slopes ranging from zero percent to 0.2 percent. 

These soils are flooded very frequently by saltwater during high tides. 

Brimstone

The Brimstone series consists of deep, poorly drained, slowly permeable soils that are 

high in exchangeable sodium. They formed in loamy sediments on low late Pleistocene 

age terraces. These soils are on broad flats at intermediate elevations with slopes that are 

zero percent to one percent. Water runs off the surface at a slow rate.

Bude

The Bude series consists of somewhat poorly drained, slowly permeable soils with a 

fragipan. They formed in a silty mantle, less than four feet thick, and the underlying 
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loamy sediments. These are nearly level to gently sloping soils on uplands and terraces 

in the Southern Mississippi Valley Silty Uplands Major Land Resource Area with slopes 

ranging from zero percent to five percent.

Calhoun

The Calhoun series consists of level, poorly drained, slowly permeable soils. These soils 

formed from loess or loess-like material with low sand content. They mainly are at low 

local elevations on Pleistocene age terraces, and less commonly on floodplains with 

slopes ranging from zero percent to one percent.

Clovelly

The Clovelly series consists of very deep, very poorly drained, very low permeability 

soils. These soils formed in moderately thick accumulations of herbaceous organic 

material overlying clayey alluvial sediments. These soils are on broad coastal marshes 

that are nearly continuously flooded with brackish water with slopes ranging from zero

percent to 0.2 percent. 

Commerce

The Commerce series consists of deep, somewhat poorly drained, moderately slowly 

permeable soils that formed in loamy alluvial sediments. These soils are on level to 

undulating alluvial plains of the Mississippi River and its tributaries with a slope that is 

dominantly less than one percent, but ranges up to five percent.

Colyell

The Colyell series consists of somewhat poorly drained slowly permeable soils that 

formed on low terraces in a thin mantle of loess over late Pleistocene age sediments with 

slopes ranging from one percent to three percent.

Encrow

The Encrow series consists of poorly drained, slowly permeable soils that formed in a 

blanket of mixed loess and local alluvium over clayey late Pleistocene age sediments. 

They are at low local elevations on level or depressed areas on terraces with slopes 

ranging from zero percent to one percent.

Fausse

The Fausse series consists of very deep, very poorly drained, very slowly permeable soils 

that formed in clayey alluvium. These soils are found in low, ponded backswamp areas 

of the lower Mississippi River alluvial plain with slopes that are less than one percent.
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Gentilly

The Gentilly series consists of very deep, very poorly drained, very slowly permeable 

slightly to moderately saline soils. These soils formed in thin accumulations of 

herbaceous plant remains and clayey alluvium over consolidated clayey deposits with 

slopes that are less than one percent. Typically they occur on subsiding distributaries of 

the Mississippi River.

Guyton

The Guyton series consists of very deep, poorly drained and very poorly drained, slowly 

permeable soils that formed in thick loamy sediments. These soils are on coastal plain 

local stream floodplains and in depressional areas on late Pleistocene age terraces with 

slopes ranging from zero percent to one percent.

Harahan

The Harahan series consists of very deep, poorly drained, very slowly permeable soils. 

They formed in moderately thick firm clayey alluvium overlying fluid clayey sediments. 

These soils are on broad backswamp positions on the lower Mississippi River flood plain. 

Slopes range from 0 to 1 percent. 

Kenner

The Kenner series consists of very deep, very poorly drained, very slowly permeable, 

organic soils. These soils formed in herbaceous plant remains stratified with clayey 

alluvium. They are in freshwater marshes along the Gulf of Mexico with slopes ranging 

from zero percent to 0.2 percent. 

Lafitte

The Lafitte series consists of very deep, very poorly drained, moderately rapidly 

permeable organic soils that formed in herbaceous plant remains over sediments. These 

soils are in intermediate and brackish marshes in the extreme lower Mississippi River 

Delta and coastal areas with slopes ranging from zero percent to 0.2 percent. 

Larose

The Larose series consists of very deep, very poorly drained, very slowly permeable soils 

that formed in fluid clayey sediments in freshwater coastal marshes. The sediments were 

deposited under water and have never air-dried and consolidated with slope ranging from 

zero percent to 0.2 percent. These soils are subject to flooding by runoff and tides. 
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Maurepas

The Maurepas series consists of very deep, very poorly drained, rapidly permeable 

organic soils that formed in woody plant remains. These soils are in large backswamps 

of the lower Mississippi River delta and associated coastal areas with slopes that are less 

than one percent.

Myatt

The Myatt series consists of deep, poorly drained, moderately slowly permeable soils on 

stream terraces and upland flats of the coastal plain. They are saturated during the winter 

and spring. Water runs off the surface slowly with slopes ranging from zero percent to 

two percent.

Ouachita

The Ouachita series consists of deep, well drained, moderately slowly permeable soils 

that formed in loamy alluvium mainly from coastal plains uplands. These level to nearly 

level soils are on floodplains and natural levees along streams in the western coastal 

plains with slopes ranging from zero percent to three percent. 

Satsuma

The Satsuma series consists of somewhat poorly drained soils that formed in mixed loess 

and loamy stream terrace deposits of late Pleistocene age. Permeability is moderate in 

the upper part of the subsoil and slow in the lower part of the subsoil with slopes ranging 

from one percent to three percent.

Scatlake

The Scatlake series consists of very deep, very poorly drained, very slowly permeable 

soils. These soils formed in unconsolidated saline clayey and organic sediments. These 

soils are in saline marsh areas along the Gulf Coast with slopes ranging from zero percent 

to 0.2 percent. 

Sharkey

The Sharkey series consists of very deep, poorly and very poorly drained, very slowly 

permeable soils that formed in clayey alluvium. Sharkey soils are on the floodplain, 

lower parts of natural levees, in backswamps and abandoned channels and on interfluves 

and low terraces of the Mississippi River with a slope that is dominantly less than one 

percent, but ranges to five percent.
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Timbalier

The Timbalier series consist of very deep, very poorly drained, rapidly permeable soils 

that formed in thick herbaceous, highly decomposed organic material. These soils are on 

saline Gulf Coast marshes and are very frequently flooded by saltwater during high tides 

with slopes ranging from zero percent to 0.2 percent. 

Westwego

The Westwego series consists of a level poorly drained mineral soil with a slope that is 

typically less than 1 percent. These soils are in swamps that have been drained and are 

protected from most flooding. The elevation of these soils ranges from sea level to about 

3 feet above sea level.

3.9.2 Prime and Unique Farmlands

The FPPA (Public Law 97-98; U.S.C. 4201 et seq.) states that Federal agencies must 

“minimize the extent to which Federal programs contribute to the unnecessary conversion 

of farmland to nonagricultural uses...” However, the FPPA definition of farmland does 

not include land already in or committed to urban development. Prime farmlands are 

designated by the NRCS and are lands that have the best combination of physical and 

chemical characteristics for agricultural production. Unique farmlands are used for the 

production of specific high value food and fiber crops. It has the special combination of 

soil quality, location, growing season, and moisture supply needed to economically 

produce sustained high quality and/or high yields of a specific crop when treated and 

managed according to acceptable farming methods; examples of such crops are citrus, 

tree nuts, olives, cranberries, fruit, and vegetables. 

3.9.3 Sediments

This section describes the general sediment characteristics within the project area

including the Mississippi River, MRGO, GIWW – Lake Borgne, Michoud Channel, Lake 

Lery, Breton Sound, and offshore sources such as the former MRGO Ocean Dredged 

Material Disposal Site (ODMDS). 

Lake Borgne

Existing soil boring data from Lake Borgne indicate that the sediment is mainly organic 

clay and clay with minor amounts of silt and silty sand. Sediment sampling of Lake 

Borgne was conducted by the USACE in 2007 at a depth of 10 feet for all samples. Of 

50 sediment samples taken by USACE, 42 of them were classified as clay. Some of the 

clays have a high percentage of organic matter and are thus considered “organic clays.” 

Five of the remaining eight samples were classified as peat (decomposed organic matter), 

and three were classified as silty sand.
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In terms of sediment contamination within Lake Borgne, brief summaries of report and 

data evaluations are provided below. 

The United States Coast Guard (USCG), National Response Center, maintains a database 

of reported oil and chemical spills for U.S. waterways. A search was conducted for any 

spills reported within the last 20 years in the projects vicinity, including Lake Borgne, 

Bayous Bienvenue, Dupre, and Yscloskey, the MRGO, and GIWW between the lake and 

MRGO. Four minor oil and fuel spills were reported in the lake between 1998 and 2005 

(Report #’s 443981, 615335, 739379, and 777114). A minor oil spill was reported in 

Bayou Bienvenue in 2006 (report # 796247). A larger spill of automotive gasoline (70 

gallons) was reported west of the MRGO in Bayou Dupre in 1996 (report #344785). 

Based on review of the USCG reports, the USACE-CEMVN does not have a reason to 

believe that sediments within the lake are contaminated.

Sediment chemistry data for Lake Borgne was provided by the EPA, Gulf Ecology 

Division. Sediment samples were collected from 13 sites in the lake between 1991 and 

2005, including four post-Hurricane Katrina collections. The sediment data were 

reviewed for the presence of 141 contaminants of concern (COC), including metals, polyaromatic hydrocarbons (PAHs) pesticides, polychlorinated biphenyls (PCBs), 

semivolatiles, and volatiles.

The concentrations of detected contaminants were compared to a set of screening values 

developed by National Oceanic and Atmospheric Administration (NOAA) to identify 

substances which may potentially threaten resources of concern at the marsh creation 

sites. A contaminant with concentrations near conservative screening values may pose 

little potential threat or only limited toxicity to sensitive species. A contaminant with 

concentrations above upper threshold screening values are more likely toxic or frequently 

can be expected to have adverse biological effects.

Thirty-five contaminants were detected at quantifiable levels from the 13 sediment 

samples. Detected contaminants included 15 metals, 15 PAHs (including measures of 

total PAHs, high molecular weight PAHs, and low molecular weight PAHs), three 

pesticides (including total DDT), and one VOC. Of the detected contaminants only 

arsenic, cadmium, chromium, nickel, and fluorine exceeded either a total exposure limit 

(TEL) or environmental risk limit (ERL) screening benchmark. Arsenic exceeded a TEL 

at two stations. Cadmium exceeded a TEL at six stations, and ERL at two stations. 

Nickel exceeded a TEL at eight stations. Chromium and fluorine each exceeded a TEL at 

one station. 

There were no instances of more than two COC exceeding a conservative benchmark at a

single station. Based on comparison to these screening values, little or no adverse 

biological effects would be expected as a result of the discharge of lake sediments into 

the marsh creation sites. Lake Borgne has limited natural sediment replenishment

sources. In addition, there are no longshore transport sources. As a result, little sediment 

accretes in Lake Borgne. 
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Other Potential Borrow Areas 

The sediments within the portion of the Mississippi River that are being considered for 

use as a borrow site are primarily comprised of silty sand with less organic matter than 

sediments in Lake Borgne. There are sand deposits at the southern end of Breton Island 

that could provide a source of material for future barrier island restoration feature. 

3.10 AIR QUALITY

3.10.1 Historic and Existing Conditions

The Clean Air Act of 1963 (CAA), which was last amended in 1990, requires EPA to set 

National Ambient Air Quality Standards (NAAQS) for pollutants considered harmful to 

public health and the environment. These standards are significant as they set limits to 

protect the public health of humans and of public welfare including protection against 

decreased visibility, damage to animals, crops, vegetation, and buildings. 

The Federal CAA requires that all states comply with the NAAQS developed for seven 

pollutants: carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), ozone (O3), sulfur 

dioxide (SO2), and two forms of particulate matter (PM10 – particulate matter with a 

diameter of 10 micrometers or less; and PM2.5 - particulate matter with a diameter of 2.5 

micrometers or less). The NAAQS include primary and secondary standards. The 

primary standards were established at levels sufficient to protect public health with an 

adequate margin of safety. The secondary standards were established to protect the 

public welfare from the adverse effects associated with pollutants in the ambient air. The 

primary and secondary standards are presented in table 3-20. 

The study area boundary includes the parishes of Ascension, Jefferson, Livingston, 

Orleans, Plaquemines, St. Bernard, St. Charles, St. James, St. John the Baptist, St. 

Tammany, and Tangipahoa in Louisiana and counties Hancock and Harrison in 

Mississippi. Of the counties/parishes in the study area, Ascension and Livingston are 

nonattainment for the 8-hour ozone standard (standard effective prior to May 2008, 0.08 

parts per million [ppm]). Currently, all parishes/counties in the construction portion of the 

study area are in “attainment” for all criteria pollutants. Although the project area 

includes waterways within the Mississippi counties, this section will only discuss existing 

air quality conditions in the project area as described in chapter 1. 

Air monitoring stations within the project area include Meraux, Chalmette High School, 

Chalmette VISTA, and Algiers Entergy. Air quality data were collected at these 

monitoring stations for the St. Bernard Air Monitoring Project that began in May, 2006. 

O3, SO2 , Hydrogen Sulfide (H2S) and VOC data were collected from 2006 - 2008. The 

VOC samples were analyzed for 107 VOC compounds, including many LDEQ Toxic Air 

Pollutants (TAPs) and EPA Hazardous Air Pollutants (HAPs). The data collected in this 

project indicates that the air quality in the Chalmette area of St. Bernard Parish is meeting 

all EPA and state ambient air standards (St. Bernard Air Monitoring Project Final 
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Report, Office of Environmental Assessment, Air Quality Assessment Division, July 30, 

2009).

Table 3-20: National Ambient Air Quality Standards for the Seven Criteria 

Pollutants

Pollutant

Primary Standards

Secondary 

Standards

Attainment Status 

Level for Louisiana

Averaging

Time Level

Averaging 

Time

Carbon

Monoxide 

9 ppm 8-hour (a)

None

Attainment (10 mg/m3

35 ppm

) 

1-hour (a) Attainment (40 mg/m3

) 

Lead

0.15 μg/m3 (b)

Rolling 3-

Month 

Average

Same as Primary Not Designated

1.5 μg/m Quarterly 

Average

3 Same as Primary Not Designated

Nitrogen

Dioxide

0.053 ppm Annual

Same as Primary Attainment (100 μg/m3 (Arithmetic 

Mean) ) 

0.100 ppm 1-hour (c) None

Particulate

Matter 

(PM10)

150 μg/m3 24-hour (d) Same as Primary Attainment

Particulate

Matter 

(PM2.5)

15.0 μg/m3

Annual (e)

(Arithmetic Same as Primary Attainment

Mean)

35 μg/m3 24-hour (f) Same as Primary Attainment

Ozone

0.075 ppm

8-hour (g) Same as Primary

EPA will make 

designations under this 

standard in 2010 (2008 std)

0.08 ppm

8-hour (h) Same as Primary

Based on 2006-2008 

monitored data, all areas 

are in attainment and the 

State will be requesting 

redesignation by EPA

(1997 std)

0.12 ppm 1-hour (i) Same as Primary

Based on monitored 

data, all areas are in 

attainment and LA is 

requesting from EPA 

the Clean Data 

Determination in 

accordance with EPA's 

Clean Data Policy

Sulfur

Dioxide

0.03 ppm

Annual 0.5 

ppm

3-hour (a)

Attainment

(Arithmetic 

Mean)

(1,300 

μg/m3 Attainment ) 

0.14 ppm 24-hour (a) Attainment
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In accordance with Section 107(d) of the Clean Air Act Amendments of 1990, 

designation recommendations for the 2008 8-hour O3 NAAQS (0.075 ppm) were 

published on March 27, 2008 (73 FR 16436). These LDEQ designation 

recommendations are based on a review of the quality-assured ozone monitoring data for 

the period 2006-2008. The recommended designations classified as nonattainment for 

ozone include Ascension, Jefferson, Livingston, and St. John Parishes in the study area. 

It will be necessary to monitor the final EPA designations made to these parishes for the 

duration of the proposed project. 

A final rule introducing a new 1-hour NOx ambient air standard was published in the 

Federal Register on February 9, 2010. The final rule is effective on April 12, 2010. 

There are no monitors in place at this time to determine attainment status in Louisiana 

parishes.

A final rule establishing a new 1-hour SO2 ambient air standard was published in the 

Federal Register on June 22, 2010. EPA is also reworking the existing 24-hour and 

annual primary SO2 standards. The final rule is effective on August 23, 2010. Monitors 

are not in place to determine attainment status for any Louisiana parishes at this time. 

EPA is also considering a new 8-hour standard for ozone (less than the current 0.075 ppm 

standard). It is possible that an increased number of parishes may be classified as nonattainment for ozone in Louisiana. 

Greenhouse Gases 

Greenhouse gases (GHGs) are the gases that absorb heat (infrared rays) released by the 

sun-warmed surface of the earth and reflect some of these rays back toward the earth, 

contributing to the greenhouse effect and potentially to climate change. 

The main GHGs that enter the atmosphere as a result of human activities are as follows:

a. Carbon Dioxide (CO2

b. Methane (CH

) 

4

NOTES:

) 

(a) Not to be exceeded more than once per year. (b) Final rule signed October 15, 2008. (c) To attain this standard, the 3-year average of the 98th percentile of the daily maximum 1-hour average at each monitor 

within an area must not exceed 0.100 ppm (effective January 22, 2010). 

(d) Not to be exceeded more than once per year on average over 3 years. (e) To attain this standard, the 3-year average of the weighted annual mean PM2.5 concentrations from single or multiple 

community-oriented monitors must not exceed 15.0 μg/m3

. (f) To attain this standard, the 3-year average of the 98th percentile of 24-hour concentrations at each population-oriented 

monitor within an area must not exceed 35 μg/m3 (effective December 17, 2006). 

(g)To attain this standard, the 3-year average of the fourth-highest daily maximum 8-hour average ozone concentrations 

measured at each monitor within an area over each year must not exceed 0.075 ppm (effective May 27, 2008). 

(h) [1] To attain this standard, the 3-year average of the fourth-highest daily maximum 8-hour average ozone concentrations 

measured at each monitor within an area over each year must not exceed 0.08 ppm. [2] The 1997 standard—and the 

implementation rules for that standard—will remain in place for implementation purposes as EPA undertakes rulemaking to 

address the transition from the 1997 ozone standard to the 2008 ozone standard. [3] EPA is in the process of reconsidering 

these standards (set in March 2008). 

(i) [1] EPA revoked the 1-hour ozone standard in all areas, although some areas have continuing obligations under that 

standard ("anti-backsliding"). [2] The standard is attained when the expected number of days per calendar year with 

maximum hourly average concentrations above 0.12 ppm is < 1.
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c. Nitrous Oxide (N2

d. Fluorinated Gases

O)

The EPA published its finding that greenhouse gases threaten public health in the Federal 

Register on December 15, 2009, setting the stage for a series of rules to begin regulating 

GHG emissions.

3.11 NOISE

3.11.1 Historic and Existing Conditions

The Noise Control Act of 1972 regulates and promotes both an environment for all 

Americans free from noise that jeopardizes their health or welfare and the Occupational 

Safety and Health Standards (29 CFR, part 1910) regarding protection against the effects 

of noise exposure. Noise levels exceeding sound pressure levels are technically 

significant because noise can negatively affect the physiological or psychological wellbeing of an individual (Kryter, 1994). These effects can range from annoyance to 

adverse physiological responses, including permanent or temporary loss of hearing, and 

other types of disturbance to humans and animals, including disruption of colonial 

nesting birds. Noise is publicly significant because of the public's concern for the 

potential annoyance and adverse effects of noise on humans and wildlife. 

Occupational noise exposure is regulated by Title 29 CFR, Part 1910, subpart G. The 

United States Department of Labor - Occupational Safety and Health Administration 

(OSHA) is the enforcing agency. OSHA has established noise exposure standards to 

protect the hearing of employees. Noise exposure for the construction industry is 

regulated by Title 29 CFR, Part 1926.52, and Occupational Noise Exposure. 

Both the City of New Orleans and the Parish of St. Bernard have noise ordinances 

addressing loud machinery. Noise is typically associated with human activities and 

habitations, such as operation of commercial and recreational boats, water vessels, air 

boats, and other recreational vehicles; operation of machinery and motors; and human 

residential-related noise (air conditioner, lawn mower, etc.). Much of the project area is a 

remote and uninhabited marsh with low ambient noise levels. The noise from distant 

urban areas surrounding the uninhabited portions of the project area contributes little, if 

any, to the natural noise levels of the area.

The Federal and municipal regulations above are addressed strictly to human receptors. 

Significant impacts of noise to terrestrial and aquatic animals probably have been related 

to localized situations where dredging and/or construction have occurred. As discussed 

in section 4.9 the proposed restoration project, impacts to aquatic animals (especially 

fishes) may be relatively significant in some areas.
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3.12 HAZARDOUS, TOXIC, AND RADIOACTIVE WASTE

3.12.1 Historic and Existing Conditions

The USACE is obligated under Engineer Regulation (ER) 1165-2-132 to assume 

responsibility for the reasonable identification and evaluation of all HTRW 

contamination within the vicinity of the tentatively selected plan. USACE policy is to 

avoid the use of project funds for HTRW removal and remediation activities. Costs for 

necessary special handling or remediation of wastes (e.g., those regulated by the 

Resource Conservation and Recovery Act [RCRA]), pollutants and other contaminants, 

which are not regulated under the Comprehensive Environmental Response, 

Compensation, and Liability Act (CERCLA), will be treated as project costs if the 

requirement is the result of a validly promulgated Federal, state or local regulation. 

The discharge of dredge material into waters of the U.S. is regulated under the CWA, and 

the Marine Protection, Research and Sanctuaries Act governs the transportation of dredge 

material to ocean waters for the purpose of disposal. The RCRA hazardous waste 

management regulations, promulgated pursuant to RCRA (42 U.S.C. 6905) specifically 

exempt dredge material from the hazardous waste definition if that material is covered 

by: 

a. a permit issued under Section 404 of the Clean Water Act, 33 U.S.C. 1344; 

b. a permit issued under Section 103 of the Marine Protection, Research and 

Sanctuaries Act of 1972 33 U.S.C. 1413; or 

c. the administrative equivalent of such permits where the work involves a USACE 

civil works project, 40 C.F.R. 261.4(g), 63 F.R. 65874, 65921; November 30, 

1998. 

ER 1165-2-132 states, dredge material and sediments beneath navigable waters proposed 

for dredging qualify as HTRW only if they are within the boundaries of a site designated 

by the EPA or a state for a response action (either a removal or a remedial action) under 

CERCLA, or if they are a part of a National Priority List (NPL) site under CERCLA. 

As reported in the Phase I Environmental Site Assessment Report, Mississippi River Gulf 

Outlet Ecosystem Restoration, February 1, 2010, (see appendix Q), during review of 

historic records, the presence of a former World War II training facility, known as the 

Shell Beach, Anti-Aircraft Training Center (AATC), 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 (MEC) dredging experts. These surveys did not identify the presence of MEC in 

the dredge material deposited within an existing shoreline protection project. The MEC 

dredging experts reported a low probability of encountering MEC in the project area. 
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The MEC dredging experts also recommended that borrow area sediments be monitored 

during the project for MEC. 

3.13 BARRIER ISLAND RESOURCES

3.13.1 Historic and Existing Conditions

The Chandeleur Islands, formed 1,800 years ago as the rim of the St. Bernard Lobe of the 

Mississippi River delta, are composed of an 50-mile long arcuate-shaped barrier island 

chain located in southeast Louisiana approximately 60 miles east of the City of New 

Orleans on the north-central coast of the Gulf of Mexico (figure 3-12 shows the general 

location while figure 3-13 and figure 3-14 exhibits the configuration of the islands). 

Accessible only by seaplane or boat, the islands are separated from the Louisiana 

mainland wetlands by the approximately 15-mile to 25-mile wide Breton and Chandeleur 

Sounds, where water depths average 10 feet to 15 feet. They are the oldest transgressive 

barrier island arc in the Mississippi River delta plain system. The Chandeleur Islands 

barrier system is divided into two sections: North Chandeleur Islands (New Harbor, 

North and Freemason islands and Chandeleur Island) and South Chandeleur Islands 

(Breton, Grand Gosier, and Curlew islands). The North Chandeleur Islands extend from 

Hewes Point to Curlew Island Pass and the South Chandeleur Islands extend from 

Curlew Island to Breton Island. These islands are extremely dynamic, but in their present 

state they are characterized by a relatively sand-rich northern section (north of Redfish 

Point) and a sand-starved southern section that extends south to Breton Island (figures 3-

13 and 3-14). 

In 1904, the island chain became the Nation's second wildlife refuge, Breton National 

Wildlife Refuge (URL http://www.fws.gov/breton/) and in 1975, it became part of the 

National Wilderness Preservation System. The islands have been home to wildlife, a 

lighthouse station (destroyed by Hurricane Katrina), a quarantine station, a small fishing 

village, and even an oil-production facility. 
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Figure 3-12: Chandeleur Islands, Breton Island, and Breton Sound

This section is primarily based on findings and discussions presented in two studies: Sand 

Resources, Regional Geology, and Coastal Processes of the Chandeleur Islands Coastal 

System — an Evaluation of the Resilience of the Breton National Wildlife Refuge (Lavoie, 

2009), a study conducted by the USGS and the University of New Orleans-Pontchartrain 

Institute for Environmental Sciences (UNO-PIES) and funded by the U.S. Fish and 

Wildlife Service; and, MRGO Ecosystem Restoration Feasibility Study, Chandeleur and 

Breton Islands (December 2009; revised April 2010) conducted by Coastal Planning & 

Engineering, Inc. and the UNO-PIES and funded by USACE. 

SOURCE: Dreher, Flocks and Lavoie, December 2007
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Figure 3-13: Shoreline Configuration and Bathymetry for the 1920s 

SOURCE: Miner, Kulp, Weathers and Flocks, 2009
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Figure 3-14: Shoreline Configuration and Bathymetry for 2005 

SOURCE: Miner, Kulp, Weathers and Flocks, 2009

Major Tidal Inlets

1. Inlet north of Hewes Point 

2. Inlet south of Breton Island 

3. MRGO Inlet 

4. Grand Gosier Pass 

1

2

3

4
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3.13.2 Shoreline Changes: History and Storm Impacts

The Chandeleur Islands were produced by marine reworking of seaward portions of 

abandoned Mississippi River delta lobes beginning approximately 1,800 years ago; a 

process dominated by lateral spit accretion downdrift from a central deltaic headland 

sediment source. Lateral transport along the Chandeleurs has produced up to a 33-foot 

thick spit platform deposit and a series of relict recurved spits that today are overlain by 

back-barrier marsh. During island landward retreat (approximately 50 feet/year from

1855-2008), sands from the subsurface relict spit deposits are liberated in the nearshore, 

providing a local sand source to the active littoral system. Where barrier marshes overlie 

relict deltaic or lagoonal muds instead of relict sandy spits, shorelines are sand-starved, 

and island disintegration rates are highest. 

The long-term reduction in barrier island sand volume (a trend that was accelerated by 

Hurricane Katrina) inhibits the islands from maintaining subaerial exposure by means of 

landward transfer of sand by overwash processes and subsequent colonization of 

overwash deposits by back-barrier marsh vegetation. During the past two decades, 

landward transfer of sand has been limited to post-storm recovery periods and is 

facilitated by: (1) landward migration of offshore bars that weld to marsh islets, (2) 

recurved spit formation at hurricane-cut inlets, (3) aeolian processes constructing dunes 

wind tidal flats, and (4) shoal aggradation and landward migration. In their present state, 

the islands are sediment-starved, and these recovery processes appear to have exhausted 

most of the available sand supply, limiting further recovery. 

According to the USGS, there is a transition from relatively sediment-rich barriers (1855 

to 1922) that built new land in the back-barrier by overwash, flood tidal delta, and 

recurved spit formation to sediment-starved barriers that no longer build new back-barrier 

land and begin to thin in places (1922 to 2005). Once the thinning has reached the point 

where no back-barrier marsh exists, the barriers cross the transgressive submergence 

threshold. They become mobile sand bodies that migrate landward through a cycle 

encompassed by storm destruction that is typically followed by emergence landward of 

their former positions during calm weather. 

The northern Chandeleur Islands have been in a constant state of shoreline retreat and 

decreasing island area during the past century. There have been two periods of time 

when a temporary reversal of the shoreline erosion trend occurred: 1) between 1965 

(post-Hurricane Betsy) and 1969 (pre-Hurricane Camille) when the shoreline moved 

seaward; and 2) between 2002 and 2004 recovery period following Hurricane Georges in 

1998 and prior to the impacts of Hurricane Ivan in late 2004 (Lavoie, 2009). 

 

The southern Chandeleur Islands are ephemeral barrier islands undergoing early stages of 

transgressive submergence and conversion to an inner shelf shoal. Storm intensity and 

frequency are the major controls on island/shoal evolution. The islands are destroyed and 

converted to submerged shoals during period of high storm frequency and historically 

have emerged and naturally rebuilt as relatively robust barrier shorelines during extended 

periods of calm weather. Curlew and Grand Gosier Islands recovered from complete 
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Restoration Plan 3-61 June 2012

destruction between 1969 (post Hurricane Camille) and 1998 (pre Hurricane Georges) 

resulting in the development of backbarrier marsh, mangrove swamp, and submerged 

seagrass beds landward of the islands. The submergence of the southern islands and 

subsequent reemergence at a location landward of their pre-storm positions result in the 

landward translation of the entire barrier island (Lavoie, 2009). 

The most significant shoreline damage was from Hurricane Katrina in 2005 when sand 

from the islands’ marsh platforms along the entire island chain were stripped and exposed 

to waves. For over 50 percent of the shore, the marsh platforms continued to erode 

rapidly. The massive reduction in land cover at the Chandeleur Islands is exhibited in 

figure 3-13 and figure 3-14. The eroded conditions have not changed since Hurricane

Katrina. 

3.13.3 Tidal Inlets

A tidal inlet is a shore-perpendicular channel along a barrier shoreline that cuts through a 

barrier island and connects the gulf with bays, lagoons, marsh, and tidal creeks (Brown, 

1928; Escoffier, 1940; Davis and Fitzgerald, 2004). Tidal currents maintain the inlet 

channel by flushing sediment that is transported alongshore by waves. There are four 

large tidal inlets responsible for the majority of tidal exchange between the Gulf of 

Mexico and the Chandeleur/Breton Sound and numerous (greater than 60) ephemeral 

hurricane-cut inlets along the northern island arc. 

The major tidal inlets in the Chandeleur Islands system are the channels that flank the 

terminal spits of the barrier arc and include the inlet north of Hewes Point and an inlet 

that is south of Breton Island (see figure 3-14). These two flanking channels are 

responsible for the majority of tidal flow into and out of Chandeleur and Breton Sounds 

(Hart and Murray, 1978). The north inlet extends from the back-barrier and curves 

around Hewes Point, where maximum channel depths are greater than 50 feet. Lateral 

spit accretion towards the north at Hewes Point has forced a northerly migration of this 

inlet.

The inlet at the southern extent of the Chandeleur Islands located south of Breton Island 

has migrated south and undergone considerable infilling. Strong tidal currents flow 

through this broad channel. 

The MRGO intersects the Chandeleur Islands just north of Breton Island and was cut 

through the existing tidal inlet of Breton Island Pass (figure 3-14). Although the natural 

inlet configuration was downdrift-offset (the inlet channel was oriented to the south in an 

alongshore direction), the MRGO trends perpendicular to the shoreline. The MRGO 

construction did not result in the abandonment of the natural channel in favor of the 

engineered one, and both channels remained open. The MRGO required frequent 

maintenance dredging to remove sand before being decommissioned in 2008. Strong 

tidal currents flow through the MRGO because it is a major conduit for tidal exchange for 

much of the Lake Pontchartrain Basin. 
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Grand Gosier Pass is a natural tidal inlet located between Curlew and Grand Gosier 

Shoals and trends perpendicular to the shoals (figure 3-14). This inlet was not present on 

the 1870s bathymetric charts, but by 2007 had scoured to a depth of greater than 30 feet. 

The date of inlet formation is not known, but the inlet is denoted on navigational charts 

dating to the 1950s (McBride et al., 1992). An ebb tidal delta has developed here as 

indicated by a seaward excursion of the 10-foot contour offshore of Curlew Shoal since 

the 1870s. 

Historically, numerous ephemeral hurricane-cut inlets along the barrier chain have been 

active for several years after a storm impact and then fill in to form a continuous barrier 

shoreline along the northern arc during extended periods of calm weather (Kahn, 1986). 

Since Hurricane Katrina, more than 60 hurricane cut tidal inlets have remained open. 

Based on the 2006 bathymetric surveys, widths range from approximately 250 to 10,000 

feet and maximum depths exceed 10 feet.

3.13.4 Spits

A spit is a sandy ridge attached to land at one end and terminating in open water at the 

other (Evans, 1942). Spits are built by lateral accretion of sand due to wave-induced 

transport. Spits accrete laterally over the subaqueous spit platform, which progrades 

ahead of the subaerial spit. Seasonal variations in wave approach and the refraction of 

waves bending around the spit end often form a hook-shaped recurved spit that extends 

into the back-barrier. Lateral accretion of a terminal spit (at the end of a barrier island) 

usually results in development of a thick sand body because the leading edge of the 

prograding spit fills a relatively deep inlet channel. Hewes Point is the terminal spit

system at the northern end of the Chandeleur Islands and is prograding, due to northerly 

longshore transport, into the marginal deltaic basin that flanks the St. Bernard Delta 

Complex. 

3.13.5 Barrier Shoals

The barrier shoals that occur along the Chandeleur Islands are present in the southern 

portion south of Monkey Bayou and include Curlew and Grand Gosier Shoals (formerly 

Curlew Island and Grand Gosier Island). These are actually ephemeral barrier islands 

that are destroyed during storms and reemerge during extended fair weather periods 

(Otvos, 1981; Penland and Boyd, 1985; Fearnley et al., 2009; Miner et al., 2009d). 

Recent increased storm frequency and a decrease in sediment supply has inhibited island 

emergence since Hurricane Katrina (Fearnley et al., 2009). The same factors leading to 

submergence and inhibiting reemergence have also forced other historically more stable 

portions of the Chandeleur Islands into ephemeral island/shoal mode. 
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3.13.6 Back-Barrier Platform, Habitat and Submerged Aquatic 

Vegetation 

Over the years, the islands have provided sanctuary for endangered wildlife species that 

seasonally inhabit them. In addition, they have supported vital habitats such as 

submerged aquatic vegetation (SAV) and back-barrier salt marshes by reducing wave 

energy and allowing shallow water habitats to exist over large, shallow expanses (Hester, 

Spalding and Franze, Spring 2005). The northern island arc (north of Monkey Bayou) is 

backed by a broad (maximum width about 1.5 miles), sandy platform that averages about 

3 to 6 feet in depth (Miner et al., 2009c) and is blanketed by SAV (Porrier and Handley, 

2006; Bethel and Martinez, 2008). Storm-generated flood tidal deltas have formed 

landward of deeper hurricane-cut inlets. The back-barrier platform is intersected by 

channels that were scoured during storms. Coastal SAV meadows that are critical habitat 

for juvenile aquatic species, sea turtles, Florida Manatee, and wintering migratory 

waterfowl in the northern Gulf of Mexico are rapidly declining (Byron and Heck, 2006; 

Poirrier and Handley, 2006; Michot et al., 2008). 

3.13.6.1 Plant Communities

The Chandeleur Islands are an important and dynamic component of the coastal 

landscape with plant assemblages ranging from terrestrial dune habitats to swales and 

intertidal back-barrier marshes. They also offer unique, isolated habitats and support 

species and communities that are not found along the rest of the Louisiana Gulf mainland 

shoreline. Without vegetation, barrier islands can be harsh environments with windblown sand, salt spray and soils with low nutrients. Currently, the presence of vegetation 

protects the islands from both high wind and wave energy and allows for the formation of 

protective dunes. Subsequently, dune vegetation serves to reduce wind velocity, causing 

sand deposition, which in turn stimulates plant growth leading to additional dune 

creation. This loop process facilitates other barrier plant communities and lends to the 

structural and protective role that barrier islands play in the estuarine ecosystem (Hester, 

Spalding and Franze, Spring 2005). 

3.13.6.2 Wildlife and Habitat Associations

Among myriads of coastal creatures, most of Louisiana’s T&E coastal species such as sea 

turtles, brown pelicans, piping plovers, and Gulf sturgeon rely on barrier island habitat 

for survival. The elimination of barrier islands because of erosion, lack of sedimentation 

from rivers, and vegetation necessary for the formation of protective dunes clearly pose a 

risk to these species. These plant and animal species thrive on the delicate balance of 

wave energy influence, salinity, marshland, and other factors and conditions that exist in 

the Chandeleur Islands. 

Ten Federally T&E species found in coastal Louisiana are strictly dependent on the 

sheltered conditions from barrier islands for their survival. Of these, the loggerhead sea 

turtle (Caretta caretta) is the only sea turtle known to nest in Louisiana with the female 

turtles selecting high-energy beaches on barrier strands adjacent to continental 
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landmasses. The Chandeleur Islands contain the only such nesting sites in Louisiana 

(O’Connell, Franze, Spalding and Poirrier, Spring 2005). 

In addition to supporting T&E species, the Chandeleur Islands also serve as a stopover 

for migratory birds and a shelter to plant life and SAV. They also provide a barrier that 

reduces the wave and wind action from the frequent storms and hurricanes protecting the 

wetland resources on the islands as well as estuaries, habitat and populated communities 

on the mainland Louisiana coastline. 

3.13.6.3 Submerged Aquatic Vegetation

SAV adjacent to the Chandeleur Islands is composed of seagrass beds/seagrass meadows. 

Seagrass is dependent upon the calm, shallow bays provided by islands. Seagrasses are 

important in stabilizing shoals on the bay side of the islands. Seagrass species at the 

Chandeleurs include turtle grass (Thalassia testudinum), manatee grass (Syringodium 

filiforme), shoal grass (Halodule wrightii), star grass (Halophila engelmanii), and wigeon 

grass (Ruppia maritima) (Porrier and Handley, 2006). The northern Chandeleur Islands 

provide a relatively pristine seagrass habitat due to their distance from pollution sources 

and high turbid water such as Biloxi, Mississippi, the mouth of Pearl River, and passes of 

Lake Pontchartrain. The southern Chandeleur chain does not support significant seagrass 

meadows due to high freshwater, plant nutrients, and turbidity levels from the Mississippi 

River and by the constantly changing morphology of the southern islands. These 

seagrass beds are extremely resilient to hurricanes and recover rapidly after storms when 

destroyed; however, the occurrence, distribution and abundance of seagrass at the 

Chandeleur Islands is directly related to the presence of a fronting barrier island (Poirier 

and Handley, 2006; Bethel and Martinez, 2008). The island dissection and rapid land 

loss associated with Hurricane Katrina has resulted in decreased suitable conditions for 

the seagrass colonization (Bethel and Martinez, 2008). 

Seagrass meadows provide important physical benefits to the stability of the Chandeleur 

Islands by baffling water flow and reducing wave energy and current velocity (Koch et 

al., 2006; Chen et al., 2007). This process results in back-barrier sediment trapping 

(vertical accretion) and protection of back-barrier marsh shorelines from wave attack in 

Chandeleur Sound. The latter is important at the Chandeleurs because of the large fetch 

distance across Chandeleur Sound, especially during the passage of winter cold fronts. 

3.13.7 Sediment Dynamics

With regard to longshore sediment transport, the arcuate barrier island trend is 

characterized by a bidirectional system with material moving from the central arc to the 

flanks. The nodal point is in the central portion of the Chandeleurs. Typically, south of 

this point, the longshore current is directed southwards, and north of the point, longshore 

currents are directed northwards. The seasonal variations in wind dominance cause an 

imbalance in transport gradients through time by forcing higher rates of transport 

potential in a northward direction (Georgiou and Schindler, 2009). Significant wave 

heights along the northern portion of the barrier have a peak of 1.5 feet based on a 25-
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year hourly average. Significant wave heights in excess of 3.3 feet occur approximately 

4 percent of the year and greater than 6.6-foot waves have a return period of less than one 

percent (Georgiou and Schindler, 2009). Net longshore transport rates north of the nodal 

point that are directed northwards have rates increasing away from the nodal point toward 

the flanks reaching values greater than 144,000 cubic yards/year (Georgiou and 

Schindler, 2009). Transport rates south of the nodal point that are generally directed to 

the south have potential rates reaching about 150,000 cubic yards/year (Georgiou and 

Schindler, 2009). 

Under non-storm conditions, significant sediment transport is restricted to the upper 

shoreface, landward of the 16-foot isobath (Penland and Boyd, 1981); however, recent 

studies along Louisiana barrier islands demonstrate that storm-associated seafloor scour 

and transport occurs at depths greater than 50 feet (Miner et al., 2009a; 2009b; Allison et 

al., 2007). Recent observational and numerical modeling studies suggest that storm 

wave-induced currents play a major role in sediment transport within the lower shoreface 

zone and inner continental shelf off of Louisiana coast (Jaffe et al., 1997; Teague et al., 

2006; Miner et al., 2009a; Georgiou and Schindler, 2009b). 

3.14 COASTAL VEGETATION RESOURCES

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 (MBTA); Endangered Species Act of 

1973; MSA; NEPA of 1969; the North American Wetlands Conservation Act; the Water 

Resources Development Acts of 1976, 1986, 1990, and 1992; CWA; EO 11990 

Protection of Wetlands; and EO 13186 Migratory Bird Habitat Protection. Coastal 

vegetation resources are technically significant because they are a critical element of 

coastal habitats. In addition, coastal vegetation resources serve as the base of primary 

productivity, contribute to ecosystem diversity, provide habitat 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.

The USFWS, in a letter dated October 31, 2008, (appendix B), formally requested that 

significant fish and wildlife resources and important habitats be fully considered and 

addressed in the DEIS including: emergent marsh, SAV, and shallow open water habitats. 

The Department of Commerce – National Marine Fisheries Service (NMFS), in a letter 

dated October 27, 2008, (appendix C), indicated that in addition to being designated as 
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essential fish habitat (EFH), the water bodies and wetlands in the study area provide 

nursery and foraging habitat supportive of a variety of important marine fishery species. 

Coastal wetlands, as well as nearshore marine and estuarine habitat, are the nursery 

grounds for the entire marine food chain in the Gulf of Mexico. Numerous species of 

marine flora and fauna begin their life cycles in these wetland, marine, and estuarine 

habitats. Pollution, development, and other factors are destroying and degrading these 

habitats throughout the Gulf of Mexico region. As these habitats are destroyed, species 

that form the base of the food chain are depleted. Ultimately, the entire Gulf of Mexico 

ecosystem is threatened by the accelerated destruction of these habitats. Failure to 

address the loss of these habitats threatens the long-term health of the entire ecosystem.

Coastal wetlands include swamps, tidal flats, coastal marshes, and bayous. They form 

sheltered coastal environments often in conjunction with river deltas, barrier islands, and 

estuaries. Coastal wetlands are rich in wildlife resources and provide nesting grounds 

and important stopovers for waterfowl and migratory birds, as well as spawning areas and 

valuable habitats for commercial and recreational fish. The intertidal and subtidal 

bottoms of coastal wetland habitats are populated by diverse benthic communities. The 

structure of the benthic communities is dependent upon several physical characteristics 

such as substrate composition, vegetative types, salinity, water temperature, and water 

depth. According to the National Coastal Condition Report II (2005), Gulf Coast 

estuaries are among the most productive natural systems producing more food per acre 

than the most productive Midwestern farmland and are second only to Alaska for 

domestic landings of commercial fish and shellfish. 

3.14.1 Land Cover

The study area encompasses approximately 3.8 million acres. Land cover within the 

study area is shown in figure 3-15. The vegetation classification descriptions and 

acreage within the study area are described in the following sections and can be found in 

figure 3-16. 

 

3.14.2 Wetland Vegetation

Wetland vegetation is adapted to withstand long-term inundation and saturated, oxygendepleted soils. Wetlands within the study area are comprised of palustrine (or freshwater) 

and estuarine (or saltwater) wetlands. These are further divided into forested, 

shrub/scrub, and emergent wetlands. Unconsolidated shores are also included as 

wetlands. There is over 912,000 acres of wetlands within the study area comprised of: 

a. Palustrine Forested Wetland = 354,226 acres 

b. Palustrine Scrub/Shrub Wetland = 39,448 acres 

c. Palustrine Emergent Wetland = 85,505 acres 

d. Estuarine Scrub/Shrub Wetland = 2,050 acres 

e. Estuarine Emergent Wetland = 430,944 acres 
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Figure 3-15: Land Cover in Study Area
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Figure 3-16: Vegetation Types
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3.14.3 Plant Community Types

The Louisiana and Mississippi coastal vegetative landscapes are characterized by a 

diversity of plant communities that have been previously classified and mapped 

according to major association or type (Penfound and Hathaway, 1938; O’Neil, 1949; 

Chabreck et al., 1968; Chabreck, 1970, 1972b; Cowardin et al., 1979; Chabreck and 

Linscombe, 1978, 1988; Visser et al., 1998, 1999, 2000; Omnerik, 1986; and Chabreck et 

al., 2001). 

These habitats are strongly influenced by the salinity regime of the surface water. 

Historically, the habitats were maintained by freshwater introduced through rivers, such 

as the Mississippi River, and other natural water sources. The construction of flood 

protection levees has limited the flow of freshwater into the marsh, while the construction 

of canals has allowed intrusion of saltwater into the estuary. These and other changes 

have resulted in an unnatural shift of habitats inland. Soils may be highly organic and 

prone to settlement. Each plant species adapts to a range of environmental conditions, 

and those species that are adapted to similar conditions form communities or associations 

that are best able to grow and successfully compete for a particular site.

In habitats within a narrow range of physical conditions, such as those with extreme 

salinity, species diversity is reduced. Since the source of saltwater in coastal Louisiana 

and Mississippi is the Gulf of Mexico, salinity levels exist along a gradient, which 

declines further inland. Plant species richness increases from saltwater to freshwater 

marshes and dominance decreases (Gosselink, 1984). Salinity predominantly drives the 

change in vegetation types among fresh, intermediate, brackish, and saline habitats. 

Below are descriptions of the major plant community types within the study area along 

with approximate acreages. The community types are based on the classification scheme 

developed by the USGS. 

3.14.3.1 Swamp (0-3 ppt Salinity) – 180,279 Acres 

Swamps in the study area are dominated by bald cypress (Taxodium distichum) and water 

tupelo (Nyssa aquatica), which have regenerated since extensive logging of virgin forest 

more than 70 years ago. The Louisiana swamps generally lack a mature canopy as was 

present in the forests before logging occurred and have lower productivity where isolated 

from riverine influences (Shaffer et al., 2003). The greatest potential to restore and 

sustain coastal forests is near the Mississippi River where freshwater reintroductions may 

be implemented. Other local sources of freshwater may be municipal wastewater or 

storm water. Economically important natural resources associated with these swamps 

include fisheries of crawfish (Procambarus clarkii), blue catfish (Ictalurus furcatus), and 

channel catfish (Ictalurus punctatus), as well as logging.
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3.14.3.2 Freshwater Marsh (0-3 ppt Salinity) – 78,720 Acres 

Fresh marsh has the highest plant diversity of all the coastal habitat types including as 

many as 93 species. Productivity is higher in freshwater marshes than forested swamps. 

In the fresh marsh the dominant plant species are maidencane (Panicum hemitomon), 

arrowhead (Sagittaria falcate), spikerush (Eleocharis spp.), and alligatorweed 

(Alternanthera philoxeroides). Floating and submerged aquatic plants are common and 

are significant for waterfowl. Freshwater and intermediate marshes contain SAV such as 

pondweed (Potamogeton pectinatus), southern naiad (Najas guadalupensis), coontail 

(Ceratophyllum demersum), and wild celery (Vallisneria americana). Dense mats of 

submerged aquatic vegetation harbor very large concentrations of macroinvertbrates, 

such as damselfly and dragonfly nymphs, midges, beetles, aquatic worms, snails and 

crawfish. These are all rich protein sources for migrating waterfowl. The amount and 

type of submerged aquatic vegetation is dependent on the salinity level. 

Economically important natural resources include fisheries of crawfish, blue catfish, and 

channel catfish. Waterfowl hunting and largemouth bass (Micropterus salmoides) fishing 

are important recreational activities. 

Portions of the these freshwater systems have been designated as critical habitat for the 

threatened Gulf sturgeon (Acipenser oxyrinchus desotoi), an anadromous fish that use 

both the Pearl and Pascagoula River systems for staging, spawning, migration routes, and 

feeding. The juvenile Gulf sturgeon may spend several years upriver before migrating to 

the ocean. This valuable habitat is important for survival of the species. 

The freshwater marsh serves as havens for shrimp, crabs, and other invertebrates during 

periods of drought, which cause higher salinity within the estuary and salt marshes. 

Many species of waterfowl and other avian species use these freshwater systems. They 

are important components of the Central and Mississippi Flyway, the direct route of 

migrating waterfowl (i.e. their north-south route). Many avian species use coastal 

Louisiana and Mississippi as overwintering grounds and forage on the diverse 

invertebrates, plant roots, and tubers. 

3.14.3.3 Intermediate Marsh (2-8 ppt Salinity) – 185,272 Acres 

Intermediate marshes have a lower species diversity than freshwater marsh, but may have 

higher productivity. Dominant plant species in the intermediate marsh are saltmeadow 

cordgrass (Spartina patens) with Common reed (Phragmites australis), arrowhead, and 

waterhyssop (Bacopa monnieri). This habitat provides important nurseries for brown 

shrimp (Farfantepenaeus aztecus), white shrimp (Litopenaeus setiferus), blue crab 

(Callinectes sapidus), and Gulf menhaden or pogy (Brevoortia patronus). Soils have very 

high organic content. Important species are rangia clams (Rangia cuneata) and Common 

reed. Clams are important for filtration and may compose a significant portion of the 

biomass in lakes or bays. Common reed is an aggressive and highly tolerant plant. Its 

root system is dense and resists shoreline erosion. Submerged aquatic vegetation within 
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lakes and bays are vital to secondary productivity. Economically important natural 

resources include fisheries of blue crab, shrimp, catfish, and drum. Waterfowl hunting 

and recreational fishing are important recreational activities.

3.14.3.4 Brackish Marsh (4-18 ppt Salinity) – 197,223 Acres 

Brackish marshes have the lowest plant diversity, but may be the most productive type of 

marsh within the study area. The dominant plant species are emergent saltmeadow 

cordgrass, saltgrass (Distichlis spicata), smooth cordgrass (Spartina alterniflora), 

needlegrass rush (Juncus roemerianus), and three-cornered grass (Scirpus olneyi). 

Oysters (Crassostrea virginica) are an exceptionally significant component of the habitat 

due to filtration, biomass, reef building, and commercial value. Historically, natural reefs 

had more vertical structure and were larger than managed oyster beds. Natural oyster 

reefs have generally been lost due to mining or salinity increases. Presently, oysters are 

located further inland and generally have little vertical reef due to harvesting practices. 

Economically important natural resources include several fisheries such as shrimp, blue 

crab, oyster, drum, mullet, and Gulf menhaden. Waterfowl hunting and recreational 

fishing are important recreational activities. Speckled trout, redfish, and flounder are 

popular sport fish. 

3.14.3.5 Salt Marsh and Barrier Islands (8-29 ppt Salinity) – 231,345 

Acres

Generally, salt marshes contiguous with the coast and salt marshes associated with the 

offshore barrier islands have high overall species diversity compared to brackish. 

Smooth cordgrass and saltmeadow cordgrass dominate the saline marsh with needlegrass 

rush, saltgrass and turtleweed (Batis maritima) as subdominants (Gosselink, 1984). In 

addition to their special ecologic value, these habitats have high aesthetic and recreational 

value. These habitats contain rookeries for a variety of birds including T&E species. 

Some islands also have true seagrasses on their bay side lagoons and provide habitat for 

the endangered West Indian manatee (Trichechus manatus) during migration. 

Hancock County, Mississippi Marsh

The Hancock County Marsh is the second largest continuous marsh area in Mississippi. 

It is located in Western Hancock County adjacent to Louisiana along the Mississippi 

Sound. The Hancock County Marsh consists of extensive marshes that have suffered 

from lack of sediment and freshwater resulting in increased saltwater intrusion and 

coastal erosion. The lack of sediment has resulted in a reduction of natural accretion and 

marsh building. The boundary of this 13,570-acre preserve includes all of the adjoining 

marshlands bordering the Mississippi Sound from the Pearl River to Point Clear. This 

saline marsh area includes a historically significant captured relic barrier island 

(Campbell Island) and an Indian shell midden (Cedar Island) over 1,600 years old. 

Included within the marshes are several low ridges and small hummocks that are above 

mean high tide. Most important of these areas are Point Clear Island and Campbell 

Island, which are sandy areas with characteristics similar to the barrier islands. The 
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islands of this marsh support several rare plant species including one of the rarest shrubs 

in the U.S., the tiny-leaved buckthorn (Sageretia minutiflora), found on the shell midden. 

The marsh area is also well-known for an abundance of waterfowl. 

The largely mesohaline area of Bayou Caddy and Point Clear Island consists of a mosaic 

of elevation zones bordering both sides of old dune/ridge systems (Point Clear Island and 

Campbell Island to the west) that are forested (pines, cedar, oak). The Pearl River and 

associated river swamp are freshwater tidal with bald-cypress, blackgum (Nyssa sylvatica 

var biflora), and water tupelo balancing the swamp canopy. This area is experiencing 

saltwater intrusion as less freshwater inflows from the west due to extensive levee 

systems of the Mississippi River and smaller systems in Plaquemines Parish in coastal 

Louisiana. As the salt tolerance of species in the tidal marshes and seagrasses is 

exceeded, changes in the food web and reductions in fish and shellfish productivity 

occur. Also, the yield of estuarine-dependent fisheries, such as shrimp, will be 

influenced by the quality of the habitat over time. 

3.14.4 Invasive Species

Invasive species are a major cause of the extinction of native species (second only to 

habitat loss). Disturbed ecosystems are more vulnerable to invasive species than stable 

ecosystems. 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. Invasive species frequently out-compete native plants 

and alter ecosystem function. Ecosystems vary in their vulnerability to invasion (USGS 

2000). 

In the study area, water hyacinth (Eichhornia crassipes), alligator weed (Alternanthera 

philoxeroides), hydrilla (Hydrilla verticillata), 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 (LACPR, 2008). 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 (LACPR, 2008). Cogongrass (Imperata 

cylindrica) is a fast-growing perennial grass that is infesting Gulf coast wetlands, 

savannas, and forests (LACPR, 2008). Invasive species occurring in coastal vegetation 

within the study area are listed in table 3-21 below: 
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Table 3-21: Invasive Species Occurring in Coastal Vegetation

Invasive Species Distribution

Nutria (Myocastor coypus) Louisiana and Mississippi

Water Hyacinth (Eichhornia crassipes) Study Area within Louisiana

Cogon grass (Imperata cylindrica) 

Ascension, St. James, St. Tammany, Livingston, Tangipahoa, 

St. Tammany, Saint Bernard, and Orleans Parishes, Louisiana, 

as well as Hancock and Harrison Counties, Mississippi

Chinese Tallow Tree (Sapium sebiferum) Louisiana and Mississippi

Parrot Feather (Myriophyllum aquaticum) Louisiana

Giant Salvinia (Salvinia molesta) Mississippi

Common Reed (Phragmites Australia) Louisiana and Mississippi

Nutria are large semi-aquatic rodents introduced from South America. Nutria are smaller 

than a beaver, but larger than a muskrat; unlike beavers or muskrats; however, nutria 

have a round, slightly haired tail. Nutria breed year round and are extremely prolific. 

Nutria live in fresh, intermediate, and brackish marsh feeding on vegetation that is vital to 

sustaining Louisiana’s coastline. These animals consume approximately 25 percent of 

their weight daily. Because of the nutria’s feeding habits, high population densities are 

damaging to wetland vegetation and further wetland loss (figure 3-17). Nutria 

predominately feed on the base of plant stems and dig for roots and rhizomes in the 

winter. Their grazing can strip large patches of marsh, and their digging overturns the 

marsh’s upper peat layer. 

Imported from fur farms, nutria were released in the Louisiana marshes in the 1930s. In 

the late 1940s, nutria were promoted as biological agents for controlling aquatic weeds, 

primarily water hyacinth, and were transplanted throughout southeastern Louisiana. In 

1965, nutria were added to the protected wildlife list as nutria furs were promoted as a 

natural resource. 

The 1980s aerial surveys confirmed coastal marshes, particularly southeastern marshes, 

were being damaged by nutria. The Louisiana Department of Wildlife and Fisheries 

(LDWF) began more extensive aerial damage surveys in 1993. Survey results indicate 

that nutria damage in recent years is concentrated in the deltaic plain in southeastern 

Louisiana. Aerial surveys reveal an estimate of 80,000 acres of marsh damaged by 

nutria. This estimate is considered conservative since only the worst (most obvious) 

nutria eat-outs can be detected from aerial surveys. 

The first coast-wide nutria herbivory survey was flown in 1998 and continued through 

2001 as part of the Nutria Harvest and Wetland Demonstration Program. The Louisiana 

Coast-wide Nutria Control Program was introduced in 2002, and since implementation of 

that program, the number of impacted marsh acres has dropped to 23,141 acres. 
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Figure 3-17: Nutria Damage in Louisiana Marsh (Louisiana Department of Wildlife 

and Fisheries)

Table 3-22 shows the annual totals of nutria damage sites and damaged acres 

documented for years 1998 to 2008 within the study area. 

Table 3-22: Estimated Annual Number of Wetland 

Acres Damaged by Nutria

Date Estimated Damage Acres*

1998 23,960

1999 27,356

2000 25,939

2001 22,139

2002 21,185

2003 21,888

2004 16,906

2005 14,260

2006 12,315

2007 9,244

2008 6,171

Water hyacinth (Eischhornia crassipes) is an aquatic plant that forms thick green mats, 

which fill bayous, canals, and lakes. The plant mats deplete the water body’s supply of 

oxygen, asphyxiating fish and other aquatic organisms. The water hyacinth was first 

SOURCE: Louisiana Department of Wildlife and Fisheries.

*When extrapolated to a coastwide estimate, the acres impacted over these years 

ranges from 102,585 to 23,141 acres (damaged acres x 3.75). The 3.75 

multiplication factor comes from the area actually surveyed along transect lines (0.5 

miles) and the distance between transect lines (1.87 miles).
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brought to U.S. as part of the 1884 Cotton Exposition held in New Orleans, when the 

Japanese delegation distributed several plants imported from Venezuela. In natural 

waterways near agricultural communities, it thrives on the constant supply of nutrients 

from fertilizer runoff. The water hyacinth can reproduce asexually, breaking into small 

pieces, which can each form a complete organism.

Cogongrass (Imperata cylindrica) is a fast-growing perennial grass that is infesting Gulf 

Coast wetlands, savannas, and forests. Considered one of the top-ten worst weeds in the 

world, cogongrass invades dry to moist natural areas and forms dense colonies with 

extensive root/rhizome systems that displace native plant and animal species. The plant 

was first reported in Grand Bay, Alabama in 1912. It spread through the Gulf Coast 

states as the seeds were distributed as packing material for Satsuma oranges. Cogongrass 

was also intentionally introduced in other southern states as a potential forage crop. 

Following the storms of 2005, cogongrass has increased its percent coverage in most of 

the coastal preserve systems and other areas of coastal Mississippi. Cogongrass has been 

recorded in parts of Louisiana (Center for Aquatic & Invasive Plants, 2000) and recently 

has been found to be locally abundant in a few areas (LCA, 2008). 

Chinese tallowtree (Triadica sebifera, also referred to as Sapium sebiferum) because of 

its tolerance to flooding and salt stress, rapidly colonize higher disturbed open ground 

and interrupt the natural succession of native prairie, scrub shrub, and woody species. 

Escaped populations of Chinese tallowtree have established extensive, self-replacing 

monocultures that have radically altered ecosystems (USGS, 2000). Chinese tallowtree is 

an extremely fast-growing generalist that tolerates shade, full sun, drought, flood, and 

alkaline, acidic, or saline soils. Mature specimens can produce 100,000 seeds in a 

season, which are dispersed by moving water and many different species of birds. 

Prolific reproduction combined with a high germination rate and rapid growth easily 

leads to single species stands of the tree within 10 years. Reduction in biodiversity can 

have direct effects on dependent wildlife. Chinese tallow is now naturalized in all the 

southeastern coastal states and Arkansas.

Parrot Feather (Myriophyllum aquaticum) is a member of the water-foil family that 

prefers warmer, milder climates and is spread quickly via plant fragments through 

waterways and drainage systems. Its escape from cultivation through its extensive use in 

outdoor aquaria and water gardens has been a major factor in the spread of the plant. M. 

aquaticum is a very hardy species that is established in a wide range of aquatic habitats. 

It prefers nutrient rich, quiet, or slow-moving shallow waters, but can tolerate the salinity 

of coastal waters and emergent sections withstand routine water level fluctuations.

Giant salvinia (Salvinia molesta), or floating fern, occurs in still or slow-moving 

freshwaters including lakes, ponds, ditches, canals, or sluggish streams and rivers. Giant 

salvinia is native to southern Brazil/South America. Giant salvinia has been found in all 

Gulf Coast states, in the Atlantic coast states of Georgia, South Carolina, North Carolina, 

and Virginia, and in Arizona, California, and Hawaii. This fern represents a significant 

danger to still or sluggish freshwater systems. It is believed to have spread naturally 

throughout the tropics and subtropics. The ornamental trade for fish and ponds is 
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responsible for expansion of its distribution. It consists of a free-floating rootless aquatic 

fern that forms dense mats. The dense mats over lakes and slow-moving rivers impede 

the movement of commercial and recreational watercraft, limit fishing access, may alter 

fisheries by preventing oxygen and light from entering water, and degrade waterside 

aesthetics. Following the hurricane events of 2005, the State of Mississippi experienced 

a rise in the colonization of this invasive species. 

Common reed (Phragmites australis) is often found in savannahs, upper marshes, shell 

middens, and barrier islands. Common reed is known to have been at least an occasional 

wetland plant in North America for 3,000 years, so it is considered native. The concern 

is that it is being overtaken by a more aggressive, introduced strain of the same species. 

There are 27 different strains of P. australis recognized, so identification of the strain 

based on morphological characteristics can be difficult. There appears to be a Gulf Coast 

strain of the species that is invasive. 

3.14.5 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 the basis for its productivity, and stability.

3.14.5.1 Marine Submerged Aquatic Vegetation Communities 

Seagrass beds, or marine SAV, are vascular plants that occur in shallow, relatively clear 

offshore marine systems with unconsolidated substrate. The primary seagrass species 

present are turtle grass (Thalassia testudinum), manatee grass (Syringodium filiforme), 

shoal grass (Halodule wrightii), and widgeon grass (Ruppia maritima). They are 

currently restricted to the northern shores of the barrier islands and small patches 

throughout the immediate shorelines. Approximately 20,000 acres of SAV were present 

in Mississippi Sound prior to 1969; however, in late 1969, Hurricane Camille caused a 

substantial destruction of these areas (Moncrieff, 1998). 

The overall distribution of SAV among Mississippi’s barrier islands has also decreased 

considerably in the same time period following Hurricane Camille, with Cat Island losing 

approximately 430 acres and Ship Island losing approximately 1,280 acres. Areas of 

SAV along the western portion of coastal Mississippi’s mainland have also declined. 

Buccaneer State Park is estimated to have lost about 150 acres. By 1975, vascular 

seagrasses had been reduced to 33 percent and algal cover had been reduced by 41 

percent. Additional losses of seagrass beds from 1971 to 1975 occurred as a result of the 

prolonged exposure to low salinity-water during the springs and winters of those years.

Seagrasses in Mississippi Territorial Waters are threatened by the cumulative effects of 

both natural events and anthropogenic activities in the coastal environment. The primary 

factors contributing to the decline of seagrass populations in the Mississippi Territorial 

Waters are an overall decline in water quality, physical loss of habitat, decreased 

availability of light, extended periods of depressed salinity, and physical disturbances, 
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such as tropical storms and hurricanes. Seagrass habitat loss in Mississippi Sound 

coincides with areas where rapid coastal erosion and massive long-term movement of 

sand have occurred (Moncrieff et al., 1998). Coastal development is likely to result in 

indirect and cumulative adverse effects on seagrass beds by contributing to elevated 

nutrient levels, higher sediment loads, and the introduction of contaminants leading to 

degraded water quality. 

Increased turbidity within Mississippi Territorial Waters causes less light penetration 

through the water column, which results in the lack of SAV photosynthesis. Replanting 

seagrass beds has been found to be expensive and not always successful. It is imperative 

that a public outreach and awareness building campaign begin that would include signage 

and materials to promote recreational boat use that is compatible with these sensitive 

areas.

Seagrass meadows in Louisiana waters occur on shallow shoals in protected waters 

behind barrier islands. Seagrass meadows decrease in the western bays of Chandeleur 

and Curlew Islands and in the shoals near Freemason, North, and New Harbor Islands. 

The southern Chandeleur chain, including Breton and Gosier Islands, are nine miles (15 

kilometers) to 19 miles (30 kilometers) from major passes of the Mississippi River. This 

chain does not support significant seagrass meadows (Poirrier & Handley, 2007). 

3.14.5.2 Estuarine Submerged Aquatic Vegetation Communities 

Composed primarily of water celery (Vallisneria americana), widgeon grass, southern 

naiad (Najas guadalupensis), and horned pondweed (Zannichellia palustris), these 

brackish SAV 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. This community is 

ranked as imperiled by the Louisiana Natural Heritage Program.

3.14.5.3 Coastal Mangrove Thicket 

Dominated by black mangrove (Avicennia germinans), 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. 

3.14.5.4 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. The frequent flooding, erosion, and shifting dune substrate constantly 

influence the dynamic community composition. Marsh-hay cordgrass is usually the 

dominant species, but saltgrass, seashore paspalum (Paspalum vaginatum), beach 
Chapter 3 Affected Environment

FEIS MRGO Ecosystem

Restoration Plan 3-78 June 2012

panicgrass (Panicum amarum), seacoast bluestem (Schizachyrium maritimum), and 

broomsedges (Andropogon spp.) are common associates.

The islands of Breton Sound have undergone a dramatic reduction in size. Erosion 

exacerbated by several major storm events has all but reduced the area to a shoal and has 

eliminated the original dune features that previously characterized the islands. 

3.14.5.5 Live Oak Forest 

Live oak (Quercus virginiana) forests occur principally on natural levees, ridges, or 

frontlands and on islands within marshes and swamps in the coastal zone of the study 

area. Live oak dominates the stand, but water oak (Quercus nigra), American elm 

(Ulmus americana), sugarberry (Celtis laevigata), red maple (Acer rubrum), and green 

ash (Fraxinus pennsylvanica) are usually prominent community members. There are 

only a small number of populations known to exist, and they are vulnerable to extirpation 

(local extinction).

3.14.5.6 Coastal Live Oak-Hackberry Forest 

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 

(also referred to as sugarberry) are the dominant canopy species, and other common 

species are red maple, sweet gum (Liquidambar styraciflua), water oak, green ash, and 

American elm. These species populate ridges composed primarily of reworked sand and 

shell that are normally four to five feet above sea level. Cheniers serve as natural 

hydrologic buffers providing some protection for the interior marshes against saltwater 

intrusion. 

3.15 WILDLIFE RESOURCES

3.15.1 Historic and Existing Conditions

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 

NEPA; 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 (MBTA); the Endangered Species Act 

of 1973, as amended; the Fish and Wildlife Conservation Act of 1980; the North 

American Wetlands Conservation Act; EO 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.
Chapter 3 Affected Environment

FEIS MRGO Ecosystem

Restoration Plan 3-79 June 2012

The USFWS, in a letter dated October 31, 2008, formally requested that the EIS fully 

consider and address significant fish and wildlife resources, including: seabirds, 

shorebirds, wading birds, migratory and resident waterfowl, and estuarine-dependent 

fishes and shellfishes (appendix B). In addition, USFWS requested that important 

habitats (such as emergent marsh, submerged aquatic vegetation, and shallow open water) 

also be addressed in the DEIS. The USFWS identified several T&E species and critical 

habitat (Gulf sturgeon and critical habitat, pallid sturgeon, piping plover and critical 

habitat, brown pelican, West Indian manatee, and sea turtles) of concern within the 

study and project areas in southern Mississippi and Louisiana. T&E species and 

critical habitats are addressed in section 3.18 and section 6.8. 

Kerlin (1979) described the wetlands of St. Bernard Parish, south of Lake Borgne, as 

being “second only to the marshes of the lower Mississippi River Delta in 

importance to waterfowl in southeastern Louisiana.” The area supported at least 

250,000 ducks during the winter and was important for the production of muskrat, 

nutria, mink, river otter, and raccoon – all staples of the Louisiana fur industry.

Since about 1970, waterfowl and furbearers have declined in the lower sub-basin (Kerlin, 

1979); however, they are still present. Alligators have also declined, but are still 

present (Kinler and Campbell, 2002). Birds found in the study area include nine species of 

wading birds, more than five species of seabirds, four species of shorebirds, six 

species of songbirds, and several raptor species. Game mammals present are swamp 

rabbit, raccoon, fox/gray squirrels, and whitetail deer. Non-game mammals include 

opossum, nine-banded armadillo, and several species of bats, rodents, and shrews 

(LCWCRTF & WCRA, 1999).

Coastal Louisiana's wetlands support millions of 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. The 

rigors of long distance flight require most neotropical migratory birds to rest and refuel 

several times before they reach their final destination. 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, especially transitional habitat between estuarine and marine environments, 

used for shelter, nesting, feeding, roosting, cover, nursery, and other life 

requirements.

Emergent fresh, intermediate, and brackish wetlands are typically used by many 

different wildlife species, including: seabirds; wading birds; shorebirds; dabbling and 

diving ducks; raptors; rails; coots; and gallinules; other emergent brackish marsh 

residents and migrants; nutria; muskrat; mink, river otter, and raccoon; rabbits; deer; 

and American alligator. Emergent saline marshes are typically utilized by: seabirds; 

wading birds; shore birds; dabbling and diving ducks; rails, coots, and gallinules; other 

saline marsh residents and migrants; nutria; muskrat; mink, river otter, and raccoon; 

rabbits; deer; and American alligator (LCWCRTF & WCRA, 1999). 
Chapter 3 Affected Environment

FEIS MRGO Ecosystem

Restoration Plan 3-80 June 2012

Open water habitats such as Lake Borgne provide wintering and multiple use 

functions for brown pelicans, seabirds, and other open water residents and migrants. 

Open water habitats in the project area provide wintering and multiple use functions 

for: brown pelicans; seabirds; dabbling and diving ducks; coots, and gallinules; and 

other open water residents and migrants (LCWCRTF & WCRA, 1999). 

The bald eagle was officially removed from the List of Endangered and Threatened 

Species as of August 8, 2007. However, it continues to be protected under the 

MBTA and the Bald and Golden Eagle Protection Act (BGEPA). Bald eagles are 

currently winter breeding residents in southern Mississippi and Louisiana.

The Chandeleur Barrier Island Chain is home to the world's largest concentration of 

Sandwich terns. These terns nest regularly on the chain and range in numbers from 

50,000 to 100,000. USGS biologists estimate that the tern population on the 

Chandeleur Chain is 55 percent to 91 percent of the total U.S. breeding population and 34 

percent to 61 percent of the entire world’s population. The barrier islands provide 

important habitat for 20,000 redhead ducks that winter in the area each year. Other birds 

found on the islands include: white and brown pelicans, gulls, terns, black skimmers, 

endangered piping plovers and other shorebirds and seabirds (LCWCRTF & WCRA, 

1999). 

Personnel from the LDWF, USFWS and NRCS provided relevant (since 1985) trends 

in wildlife for the 1998 Coast 2050 Study (LCWCRTF & WCRA, 1999). They assessed 

common wildlife in the planning subunit of the Middle and Lower Pontchartrain Basin. 

The study showed that populations of seabirds, shorebirds, dabbling and diving ducks, and 

raptors have been generally steady since 1985. Around Lake Pontchartrain, populations 

of furbearers, game mammals, and alligators have been in slight decline. In the lower 

basin, these animals have generally been decreasing since 1985. Table 3-23 shows 

the status, functions of interest, trends, and projections through 2050 for avifauna, 

furbearers, game mammals, and reptiles within the current project area (LCWCRTF & 

WCRA, 1999). 

Note that table 3-23 indicates that wildlife numbers have declined in many parts of 

the project area. These include wading birds, shorebirds, ducks, raptors, rails, coots, 

gallinules, open water resident birds, open water migrant birds, furbearers, game 

mammals, and alligators. Many factors are likely to have affected some of the 

animals, but many of these factors stem from changes in habitat which are related to 

encroaching salinity that occurred directly or indirectly after the installation / 

operation of the MRGO. For example, the loss of marsh would have removed or 

degraded cover, food, and nesting structure. Another major factor for some of the 

native furbearers and game mammals has been the proliferation of the invasive 

nutria. Nutria typically feed on the base of plant stems, consuming large quantities 

of plant matter that are important for most native herbivores. Nutria also dig for 

roots and rhizomes in a manner that disturbs the soil/sediment (LeBlanc, 1994; 

USGS, 2001).
Chapter 3 Affected Environment

FEIS MRGO Ecosystem

Restoration Plan 3-81 June 2012

Table 3-23: Status, Functions of Interest, Trends, and Projections through 2050 for Avifauna, Furbearers, Game Mammals, and Reptiles within the Project Area (LCWCRTF & WCRA, 1999)

Mapping Unit

1988 

Habitat

Avifauna

Brown Pelican Bald Eagle Seabirds Wading Birds Shorebirds Dabbling Ducks Diving Ducks Geese Raptors

Rails, Coots, and 

Gallinules

Type

% of Unit

Function

Status

Trends

Projections

Function

Status

Trends

Projections

Function

Status

Trends

Projections

Function

Status

Trends

Projections

Function

Status

Trends

Projections

Function

Status

Trends

Projections

Function

Status

Trends

Projections

Function

Status

Trends

Projections

Function

Status

Trends

Projections

Function

Status

Trends

Projections

MIDDLE PONTCHARTRAIN BASIN

Lake 

Pontchartrain

OW 100 W MO I I NH MU MO SY SY NH NH W LO SY SY W HI SY SY NH NH W LO SY SY

North Shore 

Marshes

OW 27 W MO I I NH MU MO SY SY NH NH W LO SY SY W LO SY SY NH NH W LO SY SY

IM 25 NH NH MU MO SY SY MU HI I SY MU HI SY SY W LO SY SY W LO SY SY NH MU LO SY SY MU LO SY SY

BM 40 NH NH MU MO SY SY MU HI I SY MU HI SY SY W LO SY SY W LO SY SY NH MU LO SY SY MU LO SY SY

HF 6 NH NE LO SY SY NH NH NH MU LO SY SY NH NH MU HI I D NH

Bayou Sauvage OW 23 W LO I I NH MU MO SY SY NH NH W MU SY SY W MO SY SY NH NH W MO SY SY

FM 36 NH NH MU LO SY SY MU HI I SY MU HI SY SY W MO SY SY W MO SY SY NH MU LO SY SY MU MO SY SY

IM 8 NH NH MU MO SY SY MU HI I SY MU HI SY SY W MO SY SY W MO SY SY NH MU LO SY SY MU MO SY SY

HF 26 NH NH NH NH NH MU LO SY SY NH NH MU HI SY D NE

East Orleans 

Landbridge

OW 39 W MO I I NH MU MO SY SY NH NH W MO SY D W MO SY D NH NH W MO SY SY

BM 56 NH NH MU MO SY D MU HI SY D MU HI SY D W MO SY D W MO SY D NH MU LO SY D MU MO SY SY

Pearl River 

Marsh

OW 28 W LO I I NH MU MO SY SY NH NH W MO SY SY W MO SY SY NH NH W MO SY SY

FM 1 NH NE LO SY SY MU LO SY SY MU HI I SY MU HI SY SY W MO SY SY W MO SY SY NH MU LO SY SY MU MO SY SY

IM 17 NH NH MU MO SY SY MU HI I SY MU HI SY SY W MO SY SY W MO SY SY NH MU LO SY SY MU MO SY SY

BM 15 NH NH MU MO SY SY MU HI I SY MU HI SY SY W MO SY SY W MO SY SY NH MU LO SY SY MU MO SY SY

HF 21 NH NE LO SY SY NH NH NH MU LO SY SY NNH NH MU HI I D NH

LOWER PONTCHARTRAIN BASIN

Central 

Wetlands

OW 29 W LO I I NH MU HI SY SY NH NH W LO D D W LO D D NH NH W LO D D

FM 5 NH NH MU LO SY D MU HI I SY MU HI SY SY W LO D D W LO D D NH MU LO SY SY MU LO D D

BM 45 NH NH MU HI SY D MU HI I SY MU HI SY SY W LO D D W LO D D NH MU LO SY SY MU LO D D

AU 26 NH NH NH ST LO I SY MU LO I SY NH NH NH NH NH

South Lake 

Borgne

OW 42 W MO I I NH MU HI SY SY NH NH W LO D D W LO D D NH NH W LO D D

BM 24 NH NH MU HI SY D MU HI SY D MU HI SY D W LO D D W LO D D NH MU LO SY D MU LO D D

SM 32 NH NH MU HI SY D MU HI SY D MU HI SY D W LO D D W LO D D NH NH MU LO D D

Lake Borgne OW 100 W MO I I NH MU HI SY SY NH NH NH W HI SY SY NH NH NH

Biloxi Marshes OW 76 W MO I I NH MU HI SY SY NH NH W MO SY SY W HI SY SY W LO SY SY NH NH

BM 10 NH NH MU HI SY D MU HI SY D MU HI SY D W MO SY SY W MO SY SY W LO SY SY MU LO SY D MU MO SY SY

SM 14 NH NH MU HI SY D MU HI SY D MU HI SY D W MO SY SY W MO SY SY W LO SY SY NH MU MO SY SY

Eloi Bay OW 69 W MO I I NH MU HI SY SY NH NH W MO SY SY W MO SY SY W LO SY SY NH NH

BM 5 NH NH MU HI SY D MU HI SY D MU HI SY D W MO SY SY W MO SY SY W LO SY SY MU LO SY D MU MO SY SY

SM 20 NH NH MU HI SY D MU HI SY D MU HI SY D W LO SY SY W LO SY SY W LO SY SY NH MU MO SY SY

AU 5 NH NH NH ST LO I SY MU LO I SY NH NH NH NH NH

Chandeleur 

Sound

OW 100 W HI I I NH MU HI SY SY NH NH NH W MO SY SY NH NH NH

Chandeleur 

Islands

OW 87 W HI I I NH MU HI SY SY NH NH NH W MO SY SY NH NH NH

AB 8 W HI I I NH MU HI SY D NH NH W LO SY SY W MO SY SY NH NH NH

SM 2 NE HI I I NH NH NH NH W LO SY SY W MO SY SY NH NH MU LO SY SY

BB 3 NE HI I I NH MU HI SY D NH NH NH NH NH NH NH

TYPE: OW = Open Water; BM = Brackish Marsh; SM = Salt Marsh; IM = Intermediate Marsh; FM = Fresh Marsh; HF = Hardwood Forest; AU = Agriculture/Upland; BB = Barrier Beach; AB = Aquatic Bed; Function: NE = Nesting; ST = Stopover Habitat; W = Wintering; MU = Multiple Use; 

Status: NH = Not Historically Present; NL = No Longer Present; LO = Low Numbers; MO = Moderate Numbers; HI = High Numbers; Trends (since 1985) / Projections (through 2050): SY = Steady; D = Decrease; I = Increase; U = Unknown.
Chapter 3 Affected Environment

FEIS MRGO Ecosystem

Restoration Plan 3-82 June 2012

Table 3-23: Status, Functions of Interest, Trends, and Projections through 2050 for Avifauna, Furbearers, Game Mammals, and Reptiles within the Project Area (LWCRTF & WCRA, 1999) (Continued)

Mapping 

Unit

1988 

Habitat

Avifauna (continued) Furbearers Game Mammals Reptiles

Other Marsh / OW 

Residents

Other Woodland 

Residents

Other Marsh / OW 

Migrants

Other Woodland 

Migrants Nutria Muskrat Mink, Otter, and Raccoon Rabbit Squirrel Deer American Alligator

Type

% of Unit

Function

Status

Trends

Projections

Function

Status

Trends

Projections

Function

Status

Trends

Projections

Function

Status

Trends

Projections

Function

Status

Trends

Projections

Function

Status

Trends

Projections

Function

Status

Trends

Projections

Function

Status

Trends

Projections

Function

Status

Trends

Projections

Function

Status

Trends

Projections

Function

Status

Trends

Projections

MIDDLE PONTCHARTRAIN BASIN

Lake 

Pontchartrain

OW 100 M

U 

MO SY SY NH MU MO SY SY NH NH NH NH NH NH NH NH

North Shore 

Marshes

OW 27 M

U 

MO SY SY NH MU MO SY SY NH MU MO SY SY MU MO SY SY MU LO SY SY NH NH NH MU MO I SY

IM 25 NE HI SY SY NH NE HI SY SY NH MU MO SY SY MU MO SY SY MU LO SY SY MU LO SY SY NH MU LO SY SY MU MO I SY

BM 40 NE HI SY SY NH NE HI SY SY NH MU MO SY SY MU MO SY SY MU LO SY SY MU LO SY SY NH MU LO SY SY MU MO I SY

HF 6 NH NE HI I D NH MU HI SY D MU LO SY SY MU LO SY SY MU LO SY SY MU LO SY SY MU LO SY SY MU LO SY SY MU LO SY SY

Bayou 

Sauvage

OW 23 M

U 

MO SY SY NH MU MO SY SY NH MU MO SY SY MU LO SY SY MU LO SY SY NH NH NH MU MO I I

FM 36 NE HI SY SY NH NE HI SY SY NH MU MO SY SY MU LO SY SY MU LO SY SY MU LO SY SY NH MU LO SY SY MU MO I I

IM 8 NE HI SY SY NH MU MO SY SY NH MU MO SY SY MU LO SY SY MU LO SY SY MU LO SY SY NH MU LO SY SY MU MO I I

HF 26 NH NE HI I D NH MU HI SY D MU LO SY SY MU LO SY SY MU LO SY SY MU LO SY SY MU M

O

SY SY MU LO SY SY MU LO SY SY

East Orleans 

Landbridge

OW 39 M

U 

MO SY SY NH MU MO SY SY NH MU LO SY SY MU LO SY SY MU LO SY SY NH NH NH MU LO SY SY

BM 56 NE HI SY SY NH MU HI SY D NH MU LO SY SY MU LO SY SY MU LO SY SY MU LO SY SY NH MU LO SY SY MU LO SY SY

Pearl River 

Marsh

OW 28 M

U

MO SY SY NH MU MO SY SY NH MU MO SY SY MU MO SY SY MU MO SY SY NH NH NH MU MO SY SY

FM 1 NE HI SY SY NH MU HI SY SY NH MU MO SY SY MU MO SY SY MU MO SY SY MU LO SY SY NH MU LO SY SY MU MO SY SY

IM 17 NE HI SY SY NH MU HI SY SY NH MU MO SY SY MU MO SY SY MU MO SY SY MU LO SY SY NH MU LO SY SY MU MO SY SY

BM 15 NE HI SY SY NH MU HI SY SY NH MU MO SY SY MU MO SY SY MU MO SY SY MU LO SY SY NH MU LO SY SY MU MO SY SY

HF 21 NH NE HI I D NH MU HI SY D MU LO SY SY MU LO SY SY MU LO SY SY MU LO SY SY MU LO SY SY MU LO SY SY MU LO SY SY

LOWER PONTCHARTRAIN BASIN

Central 

Wetlands

OW 19 M

U 

MO SY SY MU LO SY SY NH MU LO D D MU LO D D MU LO D D NH NH NH MU LO D D

FM 5 NE HI SY SY MU HI SY SY NH MU LO D D MU LO D D MU LO D D MU LO D D NH MU LO D D MU LO D D 

BM 45 NE HI SY SY MU HI SY SY NH MU LO D D MU LO D D MU LO D D MU LO D D NH MU LO D D MU LO D D

AU 26 NH NE LO I SY MN LO SY SY MU LO D D MU LO D D MU LO D D MU M

O

SY SY NH MU M

O

SY SY MU LO D D

South Lake 

Borgne

OW 42 M

U

MO SY SY MU MO SY SY NH MU LO D D MU LO D D MU LO D D NH NH NH MU LO D D

BM 24 NE HI SY D MU HI SY D NH MU LO D D MU LO D D MU LO D D MU LO D D NH MU LO D D MU LO D D

SM 32 NE HI SY D MU HI SY D NH MU LO D D MU LO D D MU LO D D MU LO D D NH MU LO D D MU LO D D

Lake Borgne OW 100 M

U

MO SY SY MU MO SY SY NH NH NH NH NH NH NH NH

Biloxi 

Marshes

OW 76 M

U

MO SY SY MU MO SY SY NH MU LO D D MU LO D D MU LO D D NH NH NH MU LO D D

BM 10 NE HI SY D MU HI SY D NH MU LO D D MU LO D D MU LO D D MU LO SY SY NH NH MU LO D D

SM 14 NE HI SY D MU HI SY D NH MU LO D D MU LO D D MU LO D D MU LO SY SY NH NH MU LO D D 

Eloi Bay OW 69 M

U 

MO SY SY MU MO SY SY NH MU LO D D MU LO D D MU LO D D NH NH NH MU LO D D

BM 5 NE HI SY D MU HI SY D NH MU LO D D MU LO D D MU LO D D MU LO SY SY NH NH MU LO D D

SM 20 NE HI SY D MU HI SY D NH MU LO D D MU LO D D MU LO D D MU LO SY SY NH NH MU LO D D

AU 5 NH NE LO I SY MU NH MU LO SY SY MU LO D D MU LO D D MU LO D D MU M

O 

SY SY NH MU LO SY SY MU LO D D

Chandeleur 

Sound

OW 100 M

U 

MO SY SY MU MO SY SY NH NH NH NH NH NH NH NH

Chandeleur 

Islands

OW 87 M

U 

MO SY SY MU MO SY SY NH NH NH NH NH NH NH NH

AB 8 NH NH NH NH NH NH NH NH NH NH

SM 2 NH NH NH NH NH NH NH NH NH NH

BB 3 M

U 

MO SY D MU MO SY D NH NH NH NH NH NH NH NH

TYPE: OW = Open Water; BM = Brackish Marsh; SM = Salt Marsh; IM = Intermediate Marsh; FM = Fresh Marsh; HF = Hardwood Forest; AU = Agriculture/Upland; BB = Barrier Beach; AB = Aquatic Bed; Function: NE = Nesting; ST = Stopover Habitat; W = Wintering; 

MU = Multiple Use; Status: NH = Not Historically Present; NL = No Longer Present; LO = Low Numbers; MO = Moderate Numbers; HI = High Numbers; Trends (since 1985) / Projections (through 2050): SY = Steady; D = Decrease; I = Increase; U = Unknown.
Chapter 3 Affected Environment

FEIS MRGO Ecosystem

Restoration Plan 3-83 June 2012

3.16 AQUATIC AND FISHERY RESOURCES

3.16.1 Historic and Existing Conditions

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; MSA, 

as amended; 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.

The NMFS oversees and manages our Nation’s domestic fisheries through development 

and implementation of fishery management plans and actions. The Magnuson-Stevens 

Act (first enacted in 1976, amended in 1996, and reauthorized in 2006) is the primary law 

governing marine fisheries management in United States Federal waters to end 

overfishing, promote market-based management approaches, improve science, serve a 

larger role in decision-making, and enhance international cooperation. 

Major water bodies within the study area include Lake Maurepas, Lake Pontchartrain, 

Lake Borgne, Breton Sound, Chandeleur Sound, and Mississippi Territorial Waters. By 

letter dated October 27, 2008, the NMFS indicated that these water bodies and adjacent 

wetlands provide nursery and foraging habitats which support varieties of economically 

important marine fishery species, including striped mullet (Mugil cephalus), Atlantic 

croaker (Micropogonias undulatus), Gulf menhaden (Brevoortia patronus), spotted and 

sand sea trout (Cynoscion nebulosus and C. arenarius respectively), southern flounder 

(Paralichthys lethostigma), black drum (Pogonias cromis), and blue crab (Callinectes 

sapidus). 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 

(GMFMC) (e.g., mackerel, snapper, and grouper) and highly migratory species managed 

by NMFS (e.g., billfish and shark). 

The existing emergent wetlands and shallow open water within the project area provide 

important habitat and EFH, including transitional habitat between estuarine and marine 

environments used by migratory and resident fish, as well as other aquatic organisms for 

nursery, foraging, spawning, and other life requirements. Historically and currently, the 

area provides valuable recreational and commercial fishing habitat, oyster culture, and 

nursery areas for a wide variety of finfish and shellfish (Rounsefell, 1964; Penland et al., 

2002). 

3.16.1.1 Mississippi Territorial Waters

Large amounts of freshwater empty into Mississippi Territorial Waters from the east by 

the Pascagoula and Alabama Rivers, from the west by the Pearl River and to an extent, 

the Mississippi River further west. Several nutrient-rich freshwater coastal streams and 
Chapter 3 Affected Environment

FEIS MRGO Ecosystem

Restoration Plan 3-84 June 2012

rivers, such as the Wolf, Biloxi, and Tchoutacabouffa Rivers, empty into Mississippi 

Territorial Waters between the Pascagoula and Pearl Rivers, providing great productivity. 

Recent studies have determined that, of the approximate 1,200 species of fish found 

within the northern Gulf of Mexico, excluding the southern Florida reef habitats, almost 

400 species are found on the Mississippi-Alabama Continental Shelf. Prime habitat is 

provided within Mississippi Territorial Waters for various life stages of red snapper 

(Lutjanus campechanus), tuna (Thunnus spp.), red drum (Sciaenops ocellatus), Spanish 

mackerel (Scomberomorus maculatus), king mackerel (Scomberomorus cavalla), grouper 

(Epinephelus spp.), spotted sea trout (Cynoscion nebulosus), crevalle jack (Caranx 

hippos), cobia (Rachycentron canadum), amberjack (Seriola spp.), marlin (Makaira 

spp.), and various species of sharks. 

3.16.1.2 Louisiana Estuaries

Rounsefell (1964) characterized fishery resources in marsh and bayou areas traversed by 

the MRGO using bimonthly sampling data collected by Texas Agricultural and 

Mechanical Research Foundation from July 1959 to March 1961 (El-Sayed, 1961). 

Estuarine/marine species dominated fish communities with spotted sea trout, Atlantic 

croaker, anchovy (Anchoa spp.); and sand sea trout ranking among the top 10 species in 

every area sampled, however only two freshwater species, blue catfish (Ictalurus 

furcatus) and sunfish (Lepomis spp.), ranked among the top ten species. Four nonmigratory estuarine species ranked among the top ten species in each of the lower salinity 

areas. Four marine species were among the top ten most abundant species in higher 

salinity areas (El-Sayed, 1961). The five most widespread and economically important 

fish species: spotted sea trout, Atlantic croaker, anchovy, sand sea trout, and Gulf 

menhaden, were more abundant in higher salinity areas. The five fish species most 

landed during recreational fishing in Louisiana are the red drum, black drum, spotted sea 

trout, Atlantic croaker, and sand sea trout (Pattillo et al., 1997). Neither brown shrimp 

(Farfantepenaeus axtecus) nor white shrimp (Litopenaeus setiferus) exhibited notable 

salinity preferences and were transient residents of the marshes. Small blue crabs were 

most abundant in low salinity waters (Rounsefell, 1964). 

Of the 22 species of freshwater fishes documented by Fontenot and Rogillio (1970) in the 

study region, nine freshwater species disappeared after the completion of the MRGO. 

These species included shovelnose sturgeon (Scaphirhynchus platorynchus), chain 

pickerel (Esox niger), four species of sunfish, largemouth bass (Micropterus salmoides), 

and sauger (Sander canadensis). Fontenot and Rogillio (1970) attributed the timing of 

their disappearance as “...during the latter half of the project due to an increase in salinity 

as a result of saltwater intrusion from the newly constructed MRGO.” 

The most significant source of recent data identified for the project area was a very large 

sampling database developed and maintained by the LDWF (2000). LDWF conducted 

extensive sampling of coastal marshes, bayous, and lakes extending between Lake 

Pontchartrain and Breton Sound for several decades. The data was collected from 1967 
Chapter 3 Affected Environment

FEIS MRGO Ecosystem

Restoration Plan 3-85 June 2012

until 2000, with the exception of three missing years: 1970, 1971, and 1972. However, 

this data did not assess conditions prior to construction of the MRGO (LDWF, 2000). 

Shellfish and finfish were included in the first three years of data. Beginning in 1976, the 

majority of reported catch data were brown, white, and pink shrimp (Farfantepenaeus 

duorarum). Due to database size and lack of summarized information, two sampling 

stations located closest to the project area were chosen to characterize existing conditions 

within the study area. As presented below, findings from two key monitoring stations 

support the trend of aquatic species conversion in the project area to a predominately 

marine species composition due to an increase in salinity. 

LDWF trawl data (LDWF, 2000) show the response of fisheries in the project area to the 

introduction of higher salinity waters. Estuarine fishes remained dominant in the area 

along with a few freshwater fishes. The most likely freshwater fish to be found in marine 

conditions were white crappie (Pomoxis annularis), alligator gar (Atractosteus spatula), 

and blue catfish. However, finfish species collected from the two selected sampling 

stations indicate the beginning of a trend toward the emergence of a predominantly 

marine species in these areas. As salinity levels increased in areas immediately adjacent 

to the MRGO, more marine fishes, such as Atlantic midshipman (Porichthys plectrodon), 

leatherjacket (Oligoplites saurus), gray snapper (Lutjanus griseus), and crevalle jack, 

began to appear in the sampling trawls (LDWF, 2000). 

3.16.2 Commercial Fisheries 

Located within the very center of what fisheries biologists term the “Fertile Fisheries 

Crescent,” within the northern part of the Gulf of Mexico lies what has been referred to 

as “the core of the Gulf’s $800-million fishing industry.” Of the total fishery products of 

the United States, 28 percent to 30 percent are produced in the Gulf of Mexico. 

Louisiana’s coastal estuaries are one of the most productive in the nation. This large 

expanse of coastal wetlands and estuaries provides support during critical life stages of 

important commercial species. As such, 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. 

The most recent landings in 2008 for commercial fisheries in Louisiana, estimated at 

approximately 918.5 million pounds, were the largest for any state within the continental 

United States, second only to Alaska (NMFS, 2010). These landings represent over ten 

percent of total landings in the United States, valued at approximately $274.9 million. 

This productivity is ideal for sport fishermen, commercial fishing, and local recreational 

use (MsCIP, 2008). Mississippi’s fishing industry accounted for approximately $1.1 

billion of Mississippi’s annual economy prior to Hurricane Katrina. According to the 

Mississippi Department of Marine Resources (MDMR), the Mississippi shrimping 

industry accounted for five to seven percent of all shrimp landings in the United States, 

with the total value of commercial landings amounting to $39.3 million in 2007 (NMFS, 
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2010). Table 3-24 shows landings of all the fisheries species combined in the State of 

Louisiana for 2005 through 2008 including finfish, shrimp, crabs, clams, and oysters. 

Table 3-24: Annual Landing Statistics for all Fisheries Species Combined for the 

State of Louisiana, 2005 – 2008 

Year Metric Tons Pounds Value ($)

2005 385,231 849,280,372 251,687,265

2006 416,628 918,498,167 278,111,830

2007 452,382 951,000,000 259,600,000

2008 416,616 918,471,079 274,885,853

Grand Totals 1,600,857 3,617,249,618 1,064,284,948

Table 3-25 lists the commercially and recreationally important fishes grouped by fishery 

classification and the statewide value for each group.

Table 3-25: Dollar Value of Representative Game and Commercial Fisheries 

Species Occurring in Louisiana and Mississippi Territorial Waters

Common Name Scientific Name Value in 2008 Dollars ($)

Marine Species

Brown shrimp Farfantepenaeus aztecus 31,907,169

White shrimp Litopenaeus setiferus 115,345,298

Pink shrimp Farfantepenaeus duorarum 14,562

Atlantic croaker Micropogonias undulates 32,583

Red drum Sciaenops ocellatus 42,329

Black drum Pogonias cromis 1,836,754

Sea trout Cynoscion sp. 108,859

Sheepshead Archosargus probatocephalus 354,188

Southern flounder Paralichthys lethostigma 111,382

Striped mullet Mugil cephalus 780,096

Gulf menhaden Brevoortia patronus 64,301,799

Herrings Cluperids 280,498

Eastern American oyster Crassostrea virginica 45,687,910

Blue crab Callinectes sapidus 32,206,576

Freshwater Species

Alligator gar Atractosteus spatula 521,396

Catfish Ictalurus spp. 1,734,832

Flathead catfish Pylodictis olivaris 161,872

Gizzard shad Dorosoma cepedianum 281,627

Buffalo Ictiobus sp. 614,734

Freshwater drum Aplodinotus grunniens 74,922

Blue Crab

In 2008, Gulf region landings of blue crab totaled 49 million pounds valued at $39.1 

million (NMFS, 2010). Louisiana is the leading blue crab producer in the United States, 

producing 32 percent of the Nation’s total in 2008 (NMFS, 2010). Statewide, a total of 

41.5 million pounds of blue crab were landed in 2008, valued at $31.8 million (NMFS, 

SOURCE: NOAA 2007.

SOURCE: Gulf States Marine Fisheries Commission (GSMFC) 2009.
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2010). Mississippi produced 450,037 pounds from its waters, valued at $446,756. Blue 

crabs are an important commercial species in the Lake Pontchartrain Basin. A decline in

blue crab landings from Lake Pontchartrain in the 1970s resulted in a mean annual catch 

of 1.4 million pounds, or only about nine percent of the total state landings, compared to 

2.6 million pounds, or about 27 percent, in 1959-64 (Thompson and Stone, 1980). By the 

years 1978 to 1981, mean annual catch had increased to 2.1 million pounds or about 12 

percent of the total state catch (Thompson and Stone, 1980). 

Trawl surveys within the project area (Rounsefell, 1964) revealed that blue crab 

abundance declined as salinity increased. Rounsefell (1964) observed that small blue 

crabs (less than 2 inches) were most abundant in the open, low-salinity waters of Lake 

Borgne. Slightly larger crabs (2 inches to 4 inches) were more abundant in the Bayou 

Dupre area, indicating that smaller crabs tend to migrate toward shallow and low-salinity 

areas while growing. Mature female crabs eventually migrate considerable distances 

over a few days to reach higher salinity water for spawning and hatching. 

Shrimp

In 2008, Gulf region landings of shrimp were the Nation’s largest with 184.5 million 

pounds valued at $354.5 million (NMFS, 2010). In Louisiana, a total of 24.9 million 

pounds of brown shrimp and 63.7 million pounds of white shrimp were landed in 2008, 

valuing at $22.7 million and $107.4 million respectively (NMFS, 2010). In Mississippi 

Territorial Waters, a total of 5.4 million pounds of brown shrimp and 3.2 million pounds 

of white shrimp were landed in 2008, valuing at $92 and $7.9 million respectively 

(NMFS, 2010). Pink shrimp landings for 2008 totaled 901 pounds ($756 value) and 

5,066 pounds ($13,777 value) for Louisiana and Mississippi respectively. 

3.16.3 Oyster Resources

American eastern oysters (Crassostrea virginica) are indigenous to coastal Louisiana and 

Mississippi Territorial Waters, providing a rich ecological and commercial resource. 

Salinity plays a key role in oyster sustainability (Eastern Oyster Biological Review Team, 

2007). Adult oysters can tolerate salinity from 0 ppt to 42 ppt with an optimal range of 

14 ppt to 28 ppt (EOBRT, 2007). Waters with lower salinity fail to support biological 

function, while more saline waters promote disease and predation. Oysters grow faster in 

areas with fluctuating salinity within their normal ranges compared to constant salinity 

(Pierce and Conover, 1954). Since they are sessile and cannot relocate with changing 

water quality conditions, adult oysters are more prone to impacts from changes in water 

quality than mobile fish and crustaceans. 

In 2008, the Gulf region led the United States in oyster production with 20.5 million 

pounds, 63 percent of the national total (NMFS, 2010). In Louisiana, a total of 12.8 

million pounds of oyster were harvested in 2008 with a value of $31.9 million (NMFS, 

2010). Although oyster habitat has been lost due to coastal erosion and other habitat 

alterations, Louisiana remains a top oyster producer with more than 350,000 acres 

generating around $35 million a year in economic activity (Louisiana Oyster Task Force, 
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2001). For the 2008-2009 oyster season, LDWF reported 373,030 sacks of oysters 

harvested from within the project area and adjacent water bodies (LDWF, 2009). The 

Louisiana oyster industry has been experiencing many stressors over the past several 

decades that threaten long-term sustainability of both the industry and resource 

(Coleman, 2003). Increasing coastal land loss is reducing the amount of marsh that 

provides shelter to reefs, and saltwater intrusion is exacerbating disease and predation. In 

addition, the industry is faced with changing environmental conditions, fluctuating 

market demands, public perception issues, and increased competition. Figure 3-18

shows the location of oyster reefs and seeding grounds within Louisiana territorial waters 

encompassing the project. 

Figure 3-18: Location of Oyster Reefs and Seeding Grounds within the Louisiana 

Portion of the Project Area (Outlines in Purple)

 

Oyster reefs of commercial importance are subtidal and form aggregates covering 

thousands of acres within Mississippi territorial waters. The areal extent of these oyster 

reefs is estimated at 10,000 acres to 12,000 acres, of which over half is located in 

Mississippi territorial waters south of Pass Christian. In 2008, 2.6 million pounds of 

oyster were harvested in Mississippi with a total value of $6.9 million (NMFS, 2010). 

For the 2008-2009 oyster seasons, MDMR reported a total catch of 385,949 sacks from 
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16,261 boat trips (MDMR, 2009). Figure 3–19 shows the location of oyster reefs and 

seeding grounds within the Mississippi territorial waters of the project. 

Figure 3-19: Location of Oyster Reefs and Seeding Grounds within the Mississippi 

Territorial Waters

3.16.4 Water Bottoms and Benthic Resources

Benthic resources are significant institutionally, technically, and publicly. They are 

institutionally important, from acts such as NEPA of 1969; Coastal Zone Management 

Act; and the Estuary Protection Act. They are technically important, due to their ability 

to regulate or modify most chemical, physical, biological, and geological processes 

throughout an entire estuarine system, known as the “benthic effect” (Day et al., 1989). 

They are publicly important, considering members of the epibenthic community, such as 

oysters and mussels, provide commercial as well as recreational fisheries. 

The benthic resources of an estuary regulate or modify most physical, chemical, 

geological, and biological processes throughout the entire estuarine system via what is 

called a “benthic effect” (Day et al., 1989), Benthic animals are directly or indirectly 

involved in most physical and chemical processes that occur in estuaries (Day et al., 

1989). Oysters are part of the epibenthic community (i.e., living on the surface of the 

substrate). As described in section 3.16.3, they are important components of commercial 
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and recreational fisheries in the project area. In addition, they create reef habitat that is 

used by many marine and estuarine organisms. 

Benthic community structure is not static. There are seasonal, as well as yearly, changes 

in benthic communities. Benthic communities are storehouses of organic matter and 

inorganic nutrients, as well as sites for many vital chemical exchanges and physical 

interactions. Day et al., (1989) describe categories (based on size and location within 

substrate) and functional groups (based on feeding mode) of estuarine benthic organisms, 

which include macrobenthic (e.g., mollusks, polychaetes, decapods); microbenthic (e.g., 

protozoa); meiobenthic (e.g., nematodes, harpacticoid copepods, tubellaria); epibenthic; 

infauna (e.g., most bivalves); interstitial fauna (e.g., beach meiofauna, tardigrades); 

suspension-feeders (e.g., bryozoans and many bivalves); filter-feeders (e.g., poriferans, 

tunicates, bivalves); nonselective deposit feeders (e.g., gastropods); selective deposit 

feeders (e.g., nematodes, sand dollars, fiddler crabs); raporial feeders and predators (e.g., 

star fish and gastropod drills); and parasites and commensuals (e.g., parasitic flatworms 

and copepods, pea crabs). 

According to Mitsch and Gosselink (1993), the salt marsh is a major producer of detritus 

for both the salt marsh system and adjacent estuary. Mitsch and Gosselink (1993) point 

out that detritus exported from marshes is more important to the estuary than 

phytoplankton-based production in the estuary. Detritus and shelter found along marsh 

edges make salt marshes important nursery areas for many commercially important fish 

and shellfish. Salt marshes have been shown at times to be both sources and sinks of 

nutrients, particularly nitrogen. 

Within a salt marsh, less than ten percent of above-ground primary production of salt 

marsh is grazed by aerial consumers. Most plant biomass dies and decays, and its energy 

is processed through the detrital pathway. Major benthic consumer groups of detritus

include bacteria and fungi, microalgae, meiofauna, and microfauna (Mitsch and 

Gosselink, 1993). 

A benthic survey was performed by USACE Engineer Research Development Center 

(ERDC) to assess potential benthic species assemblages within Lake Borgne and Biloxi 

Marsh (Lake Borgne 2008). A total of 111 infaunal samples and seven sediment grain 

size samples were collected between May 21, 2007 and May 24, 2007. Depths at sample 

sites ranged from 5 feet to 10 feet, salinity ranged from 9.1 ppt to 11.2 ppt, and DO

concentrations ranged from 6.0 mg/l to 8.0 mg/l. Sediments sampled were poorly sorted 

sandy mud with a mean grain size in the range of very coarse silts. Total silts and clays 

accounted for more than 64 percent of the sediment with the remainder dominated by 

very fine sand. Sediments in proposed access channel sites differ somewhat with 

innermost (shoreward) stations dominated by peat and outermost stations resembling 

those of borrow areas. 

The benthic species assemblage of the study area is dominated by polychaetes (62 

percent), bivalves (14 percent), and amphipods (11 percent). The most abundant species, 

the polychaete Mediomastus ambiseta, accounts for more than 28 percent of all animals 
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collected. Other important polychaete species include Parandalia americana, 

Streblospio benedicti, Sigambra bassi, Glycinde solitaria, Nereis succinea, Pectinaria 

gouldii, and Capitella sp. The most abundant bivalve mollusks are Macoma mitchelli, 

Mulinia lateralis, and Mulinia pontchartrainensis. Amphipods are dominated by 

Ampelisca abdita, Ameroculodes sp., and Cerapus benthophilus. Other numerically 

abundant species include the gastropod Acetocina canaliculata, two unidentified species 

of nemerteans, and the oligochaete Tubificoides sp. Together, these 18 species comprised 

nearly 94 percent of all animals encountered. This assemblage is typical of soft bottom, 

mesohaline (5.0 ppt to 18 ppt) communities throughout the northern Gulf of Mexico and 

similar to previous reports from Lake Borgne.

3.17 PLANKTON RESOURCES

3.17.1 Historic and Existing Conditions

Plankton communities are comprised of plants (phytoplankton) and animals 

(zooplankton). Plankton serve an important role in the trophic dynamics of the coastal 

waters of Louisiana and Mississippi. Phytoplankton are the primary producers of the 

water column and form the base of estuarine food web. Zooplankton provide the trophic 

link between phytoplankton and intermediate level consumers, such as aquatic 

invertebrates, larval fish, and smaller forage fish species (Day et al., 1989). 

Phytoplankton are also important for their role in nutrient cycling through photosynthesis 

and are the major source of autochthonous organic matter in most estuarine ecosystems 

(Day et al., 1989). Perret et al. (1971) provided a summary of zooplankton across the 

coastal estuaries of Louisiana in the late 1960s. The dominant member of the 

zooplankton community throughout that study was the copepod (Acartia tonsa). The 

largest concentrations of zooplankton were in Breton Sound, while lowest concentrations 

were in Chandeleur Sound and Lake Borgne east of the Mississippi River, Lakes Barre 

and Raccourci, and Terrebonne and Timbalier Bays. Species diversity was greatest in 

Breton Sound and Mississippi River, East Bay, Garden Island Bay, and West Bay areas. 

Rotifers, copepods, and cladocerans are the dominant organisms in freshwater. In 

intermediate and brackish waters, the Acartia tonsa and copepod nauplii were found to be 

the most numerous zooplankters. The inshore saline waters were also found to have 

copepod nauplii and Acartia tonsa as the most common zooplankters, with more 

abundant numbers in saline waters than brackish waters (Conner and Day, 1987). 

Changes in zooplankton density have been directly correlated to the breeding cycle of 

holoplanktonic copepods. 

Plankton form the lowest trophic food level for many larger organisms important to 

commercial and recreational fishing. In addition, there is a public health concern with 

noxious plankton blooms (red and brown tides) that produce toxins, and large-scale 

blooms can lead to hypoxic conditions, resulting in fish kills. 
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3.18 ESSENTIAL FISH HABITAT

3.18.1 Historic and Existing Conditions

Essential fish habitat (EFH) is defined as “those waters and substrate necessary to fish for 

spawning, breeding, feeding or growth to maturity.” Table 3-26 and table 3-27 list the 

Federally managed species within the project area, as well as, representative EFH known 

to occur within the Gulf of Mexico (Louisiana and Mississippi Territorial Waters). The 

1996 amendments to the MSA set forth a mandate for the NMFS of the 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 (seagrasses and algae), and adjacent intertidal 

vegetation (marshes and mangroves). 

In a letter dated October 27, 2008, NMFS identified EFH resources within the study area 

(including Mississippi Territorial Waters) as estuarine emergent wetlands; SAV/seagrass 

beds; mud, sand, and shell substrates; and the estuarine and marine water column. 

Detailed information on Federally managed fisheries and their EFH is provided in the 

2005 Generic Amendment of the Fishery Management Plans (FMP) for the Gulf of 

Mexico prepared by the Gulf of Mexico Fishery Management Council (GMFMC). 

In addition to being designated as EFH for species listed in Table 3-27, water bodies and 

adjacent wetlands within the project area provide nursery and foraging habitats which 

support a variety of economically important marine fishery species, including 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 MSA by GMFMC (e.g., mackerels, snappers, and groupers) and 

highly migratory species managed by NMFS (e.g., billfishes and sharks). 

Table 3-26: Life Stages of Federally Managed Species and EFH Present in the 

Project Area

Species Life stage System EFH

Brown shrimp

Larvae Marine <269 feet; sand/shell/soft bottom, SAV, emergent 

marsh, oyster reef

Juvenile Estuarine <59 feet; SAV, sand/shell/soft bottom, emergent 

marsh, oyster reef

Adult Marine <46-360 feet; sand/shell/soft substrate

White shrimp Juvenile Estuarine <98 feet; SAV, soft bottom, emergent marsh

Pink shrimp Juvenile Estuarine <213 feet; sand/shell substrate

Gulf Stone Crab

Eggs Estuarine/Marine <59 feet; sand/shell/soft bottom

Larvae/post 

larvae Estuarine/Marine <59 feet; oyster reefs, soft bottom

Juvenile Estuarine <59 feet; sand/shell/soft bottom, oyster reef
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Table 3-26: Life Stages of Federally Managed Species and EFH Present in the 

Project Area

Species Life stage System EFH

Red Drum

Larvae/post 

larvae Estuarine All estuaries, SAV, sand/shell/soft bottom, emergent marsh

Juvenile Estuarine/Marine

Gulf of Mexico (GOM) <16 feet west from 

Mobile Bay; all estuaries SAV, 

sand/shell/soft/hard bottom, emergent marsh

Adult Estuarine/Marine

GOM 3-150 feet west from Mobile Bay; all 

estuaries SAV, pelagic, sand/shell/soft/hard 

bottom, emergent marsh

Lane Snapper

Larvae Estuarine/Marine 13-433 feet; reefs, SAV

Juvenile Estuarine/Marine <65 feet; SAV, mangrove, reefs, sand/shell/soft 

btm.

Dog Snapper Juvenile Estuarine/Marine SAV, mangrove, emergent marsh

Dwarf Sand 

Perch Juvenile Marine hard bottom

King Mackerel

Larvae Marine 30-590 feet

Juvenile Marine <30 feet; pelagic

Adults Marine 115-590 feet; pelagic

Spanish 

Mackerel

Eggs Marine <164 feet

Larvae Marine 30-275 feet

Juvenile Estuarine/Marine <164 feet; pelagic

Adults Estuarine/Marine <246 feet; pelagic

Cobia

Eggs Marine

Larvae Marine 36-174 feet

Juvenile Marine 16-600 feet; pelagic

Bonnethead 

Shark Juvenile Marine Inlets, estuaries, coastal waters <82 feet, FloridaKeys to Cedar Key; Louisiana and Texas

Atlantic 

Sharpnose 

Shark

Adults Marine <164 feet Mississippi Sound and Galveston to 

Laguna Madre, Texas

Table 3-27: Representative Categories of EFH Known to Occur Within the Gulf of 

Mexico Region (Louisiana and Mississippi Territorial Waters)

Estuarine Areas Marine Areas

Estuarine emergent wetlands Water column

Mangrove wetlands Vegetated bottoms

Submerged aquatic vegetation (SAV) Non-vegetated bottoms

Algal flats Live bottoms

Mud, sand, shell, and rock substrates Coral reefs

Estuarine water column Geological features

Continental shelf features

Brown Shrimp (Farfantepenaeus aztecus)

There is a high probability that juvenile brown shrimp could occur within the estuarine 

open water and in SAV habitats located within the project area. Both post-larval and 

juvenile life stages of brown shrimp are likely to use open water in the IHNC as a conduit 

to estuarine open water, emergent marsh, and SAV in Lake Pontchartrain. It is thought 

that this species occupies and migrates through the project area from the Gulf of Mexico 

SOURCE: NMFS EFH Gulf of Mexico Region, 2008.
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via three main routes: the GIWW and Lake Borgne, the Golden Triangle marsh, and 

Bayou Bienvenue. Prior to its de-authorization, the MRGO provided access for the 

largest number of organisms compared to the GIWW and Lake Borgne because it 

provided the most direct route with a strong tidal pulse. 

Adult brown shrimp typically inhabit offshore waters (Patillo et al., 1997), such as those 

off the coast of Louisiana, although individual adults may occur within the project 

vicinity in open water habitat with turbid waters and soft sediments (Patillo et al., 1997; 

Lassuy, 1983c). Post-larval brown shrimp feed on phytoplankton, zooplankton, 

epiphytes, and detritus. Juveniles and adults prey primarily on amphipods, polychaetes, 

and chironomid larvae as well as algae and detritus (Patillo et al., 1997; Lassuy, 1983c). 

Post-larval brown shrimp have been captured in salinity from essentially fresh (Swingle, 

1971) to 69 ppt (Simmons, 1957) with 19 ppt being optimal within this given range 

(Lassuy, 1983). 

White Shrimp (Litopenaeus setiferus)

Juvenile white shrimp are common to abundant within the project vicinity from July 

through October (GMFMC, 2004). Post-larval white shrimp seek shallow, estuarine 

water with muddy sand bottoms high in organic detritus or vegetative cover; while 

juvenile white shrimp inhabit turbid estuaries, marsh edges, and SAV (Patillo et al., 

1997). Post-larval white shrimp use soft muddy or peat-like bottoms for burrowing 

(Muncy, 1984). White shrimp can be replaced by brown shrimp in muddy areas due to 

competition for habitat (Muncy, 1984). GMFMC (2004) maps show that adult white 

shrimp habitat includes Irish Bayou, Lake Catherine, Lake Borgne, and the eastern shore 

of Lake Pontchartrain. 

Like brown shrimp, post-larval white shrimp feed on phytoplankton, zooplankton, 

epiphytes, and detritus. Juveniles and adults prey on amphipods, polychaetes, and 

chironomid larvae and also consume algae and detritus (Patillo et al., 1997). 

Post-larval white shrimp prefer a mesohaline salinity regime; juveniles prefer lower 

salinity habitats (6 to 8 ppt); and larger late juvenile stage individuals prefer brackish 

habitats (10 to 18 ppt). Adult white shrimp spend most of their life offshore, where they 

spawn in waters that have salinity of approximately 23-27 ppt. 

Pink Shrimp (Farfantepenaeus duorarum)

According to the GMFMC (2004), juvenile pink shrimp are expected to occur in the 

project vicinity; however, (Patillo et al., 1997) indicate occurrences are rare. Juveniles 

may prefer SAV meadows, where they burrow into coarse substrate; post-larval pink 

shrimp prefer a mixture of course sand/shell/mud with immature stages found on 

substrates with vegetative detritus. Although densities of pink shrimp are considered 

highest in SAV habitat by (Patillo et al., 1997) the GMFMC (2004) clarifies that 

juveniles prefer high salinity SAV over low salinity SAV. Post-larval pink shrimp feed 
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on phytoplankton, zooplankton, epiphytes, and detritus. Juveniles and adults consume 

algae and detritus (Darnell, 1961) and prey on amphipods, polychaetes, and chironomid 

larvae (Patillo et al., 1997). 

Gulf Stone Crab (Menippe mercenaria)

Gulf stone crabs are found within areas of high salinity within the project area. Larval 

stone crabs are sensitive to lower salinity, while adults sometimes considered euryhaline, 

are typically found in higher salinity approaching full seawater (Linberg and Marshall, 

1984). Considered to be eurythermal, they have been collected in temperatures ranging 

from 46oF to 90oF (Bender, 1971). However, on the lower end of the range they seal 

themselves in burrows, while at the higher end of the range typically seek the coolness of 

deeper water. 

Planktonic larvae develop in estuarine/marine environments near oyster reefs or soft 

bottoms with optimal salinity ranging from 30 to 35 ppt (Linberg and Marshall, 1984). In 

studies conducted within laboratories, Ong and Costlow (1970) found that no larvae stone 

crabs survived in waters with salinity equal to or less than 10 ppt. Larvae stone crab prey 

on other planktonic larval stages and zooplankton, while juvenile and adults consume 

polychaetes, bivalves, oyster drills, and fish (Linberg and Marshall, 1984). 

EFH exist for three stages of the Gulf stone crab (eggs, larvae/post larvae, and juvenile) 

within the project vicinity, including, sand; shell; soft bottoms; or oyster reefs at depths 

less than 59 feet in marine or estuarine habitats. 

Red Drum (Sciaenops ocellatus)

Adult and juvenile red drum occurs in a variety of habitats within the project vicinity. 

Both adults and juveniles can be found in the project vicinity’s shallow open water and 

brackish emergent marsh habitats year round; however, adults are more common April 

through October (GMFMC, 2004), and juvenile red drum are common to abundant yearround (GMFMC, 2004; Nelson et al., 1992). Adult red drum may also occur in the scour 

holes north and south of the Seabrook Bridge, in emergent marsh in Lake Pontchartrain, 

and in open waters and emergent marsh within and adjacent to the GIWW, the IHNC, the 

MRGO, and the Golden Triangle marsh. 

Spawning typically occurs outside the project vicinity (GMFMC, 2004) in deeper water 

near the mouths of bays and inlets (Pearson, 1929) near the Gulf of Mexico. Planktonic 

red drum larvae are carried by currents into bays and estuaries (Peters and McMichael, 

1987), such as Lake Pontchartrain, where they settle into the tidally influenced emergent 

wetlands (Stunz et al., 2002a). Juvenile red drum prefer specific habitat types, occurring 

at higher densities in SAV (Stunz et al., 2002a). They grow faster in SAV as well as in 

brackish emergent marsh and oyster reefs (Stunz et al., 2002b). Additionally, juvenile 

red drum prefers a mesohaline (5 to 16 ppt) to euryhaline salinity regime (16 to 36 ppt), 

and growth rates are highest between 65oF and 88oF (GMFMC, 2004). 
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Red drum is considered predators in estuaries, and the project site is considered an area of 

high abundance of the red drum (Reagan, 1985). They are considered intermediate 

feeders due to their use of the bottom for foraging (eating oysters, clams, and blue crabs), 

as well as the pelagic habitat to hunt for prey fish species. Locally in Louisiana, red 

drum are also known for their preference for crabs (LDWF, 2009b). Juvenile red drum 

show preferences for fish, crabs, and shrimp, particularly mysid shrimp (Reagan, 1985). 

Adult red drum feed primarily on fish, shrimp, and crabs. Fish, primarily menhaden 

(Brevoortia) and anchovies (Anchoa spp.), are an important source of food in the winter 

and spring, while crabs and shrimp are important in the summer and fall (Reagan, 1985). 

Lane Snapper (Lutjanus synagris)

EFH only occurs for the larvae and juvenile lane snapper within the project vicinity. 

Lane snapper occur within a wide variety of habitats, from coral reefs in clear water to 

turbid, brackish water over soft substrates (Borone et al., 1986). Croker (1962) indicates, 

most snappers (including the lane snapper) spawn in groups in an offshore marine 

environment. Larval lane snapper prefer an estuarine/marine environment with depths 

ranging from 13 to 433 feet. While adult lane snappers prefer marine areas with hard 

bottoms and reefs, juvenile lane snapper prefer mangrove areas with sand, shell, or soft 

bottoms at depths less than 66 feet. As such, lane snappers feed on a wide variety of 

organisms (Borone et al., 1986), such as crabs, shrimp, worms, gastropods, and 

cephlapods. Lane snapper are typically found in waters with temperatures ranging from 

61oF to 84oF, and salinity of 19.1 to 35.0 ppt (Borone et al., 1986). While adults typically 

live offshore with salinity near the higher end of the range, juveniles use estuaries as 

nursery areas. 

Dog Snapper (Lutjanus jocu)

Juvenile dog snapper are typically found in estuaries, mangrove, emergent marsh, and 

submersed aquatic vegetation, which is EFH included in the project vicinity. They have 

been collected at depths ranging from 6 to 131 feet, although they typically inhabit the 

water column between 16 to 98 feet. Dog snappers feed on a wide variety of organisms 

such as, crabs, shrimp, worms, gastropods, and cephlapods nocturnally. Dog snapper are 

typically found in waters with temperatures ranging from 61oF to 84oF, and salinity of 

approximately 19 to 35 ppt. While adults typically live offshore with salinity near the 

higher end of the range, juveniles use estuaries as nursery areas. 

Dwarf Sand Perch (Diplectrum bivittatum)

Inhabiting bays and seagrass beds at depths from 3 to 262 feet, the sand perch is 

primarily a warm-water, inshore fish occasionally observed offshore associated with 

wrecks and reefs or occasionally deep channels. EFH only exist for juvenile life stages 

within the project area. The sand perch lives in holes in the sandy bottom or under rocks. 

The holes are either pre-existing, made by other organisms, or the sand perch excavates a 

new hole. It lies on the bottom, vibrating its body to push the sand away. As a bottom 

inhabitant of reefs and rocky areas, the sand perch feeds primarily on benthic crustaceans, 
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including shrimps, crabs, and amphipods, as well as small fishes such as small sea bass 

(Centropristis spp.), sea robins (Prionotus spp.), gobies, blennies, flatfishes (Symphurus

spp.), and filefish (Monacanthus spp.). Sand perch are synchronously hermaphroditic 

fish - individual fish possess both male and female organs, producing sperm and eggs at 

the same time.

King Mackerel (Scomberomorus cavalla) and Spanish Mackerel (Scomberomorus 

maculatus)

Water temperature and salinity levels are the most important factors governing 

distribution of both king and spanish mackerel (Godcharles and Murphy, 1986). Both 

species prefer water temperature ranging from 70oF to 81oF, rarely being collected in 

temperature below 64oF. All life stages (eggs, larvae, juvenile, adult) inhabit waters with 

salinity ranging from 32 to 35 ppt (Godcharles and Murphy, 1986). Both of these species 

in the juvenile and adult stages are primarily pelagic carnivores. Juveniles of both 

species are piscivorous (primarily feeding on schooling fish), but king mackerels have a 

preference for invertebrates. 

Both species in the larvae stage are planktonic in marine environments from depths of 30 

to 590 feet. Juvenile king mackerel prefer a marine pelagic environment at depths less 

than 30 feet, while juvenile spanish mackerel use more estuarine/marine environment at 

depths less than 164 feet. Adult phases of both species are pelagic, while king mackerel 

prefer marine environments and spanish mackerel use estuarine/marine environments at 

depths of 115 to 591 feet and less than 246 feet, respectively. 

Cobia (Rachycentron canadum)

Cobia are found nearly worldwide in tropical, sub-tropical, and warm temperature waters 

ranging from approximately 61oF to 90oF with salinity ranging from 22.5 to 44.5 ppt 

(NMFS, 2010). Eggs and larvae are typically found offshore in water depths from 36 to 

174 feet, while early juvenile stages tend to move toward more inshore areas, inhabiting 

coastal areas, bays, beaches, and river mouths. Occasionally entering estuaries, adults are 

more prevalent on the continental shelf and in coastal waters. They can be found within 

varying depths of the water column; however, they are more of a pelagic species (NMFS, 

2010). Habitats vary from mud, rock, sand and gravel bottoms, over coral reefs, and in 

mangrove sloughs. Along coastal inshore areas they can be found around pilings and 

buoys, as well as drifting and stationary objects. Cobia migrate to areas with high food 

abundance, typically eating crabs and other crustaceans, benthic invertebrates, and fish. 

 

Bonnethead Shark (Sphyrna tiburo)

Bonnethead sharks are found on the continental and insular shelves, on inshore and 

coastal areas, over mud and sand bottoms, and on coral reefs and occur in shallow water 

including estuaries, shallow bays and over coral reefs. They feed primarily on 

crustaceans, consisting mostly of blue crabs, but also shrimp, mollusks and small fish. 

They are subtropical, brackish/marine fish with depths ranging from 33 to 262 feet. 
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Juveniles are typically found in inlets of estuaries and coastal waters less than 82 feet, 

typically warmer than 70oF. 

Atlantic Sharpnose Shark (Rhizoprionodon terraenovae)

Atlantic sharpnose sharks are abundant in continental shelves, from the intertidal to 

deeper waters at depths of 33 to 918 feet and often occur close to the surf zone off sandy 

beaches, and also enclosed bays, sounds, and harbors, in estuaries and river mouths, 

mostly over sandy or muddy bottoms. During summer months, juveniles, subadults, and 

adults inhabit shallow inshore waters (Benson, 1982). An offshore migration occurs in 

the fall, as they often tend to concentrate in even deeper offshore waters during the winter 

(Benson, 1982). They feed on small bony fishes such as menhaden and parrotfish 

(Benson, 1982), shrimp, crabs, segmented worms and mollusks. Females migrate inshore 

during summer months to give birth. 

3.19 THREATENED AND ENDANGERED SPECIES

3.19.1 Historic and Existing Conditions

Within the State of Louisiana there are 30 animal and three plant species (some with 

critical habitats) under the jurisdiction of the USFWS and/or the NMFS, presently 

classified as endangered or threatened. 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 (see table 3-28 and also appendix G). 

Although some of these species may have historically occurred within the project area, 

those species that may be potentially impacted by the tentatively selected plan are 

described in detail within appendix G. In Louisiana, Plaquemines and St. Bernard 

Parishes have experienced some of the most dramatic environmental changes within the 

state over the past century. These changes have stressed listed species in Louisiana as 

their habitats are lost or modified. Some species that historically may have inhabited the 

project area, but are now extirpated are the red wolf (Canis rufus) and the Louisiana 

black bear (Ursus americanus luteolus). Other species that were listed on the 

Endangered Species List, but have since then been de-listed because population levels 

have improved are the bald eagle (Haliaeetus leucocephalus) and the brown pelican 

(Pelecanus occidentalis). 

Red wolf (Canis rufus)

The red wolf is one of the world’s most endangered wild canids. Once common 

throughout the southeastern United States, red wolf populations were decimated during 

the 1960s due to intensive predator control programs and loss of habitat. The last 

remnant population of red wolves was found along the Gulf Coasts of Texas and 

Louisiana. Those individuals were trapped and used for a captive breeding program. The 

USFWS declared red wolves extinct in the wild in 1980 (USFWS, 2007). At one time 
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red wolves may have occurred in the project area, but no documented sightings have 

occurred since they were declared extinct in the wild.

Table 3-28: Threatened and Endangered Species

Species State

Critical 

Habitat Status

Jurisdiction

USFWS NFMS

Animal

Louisiana Black Bear (Ursus americanus 

luteolus) LA T X 

West Indian Manatee (Trichechus 

manatus) LA E X 

Brown Pelican (Pelecanus occidentalis) LA E X

Piping Plover (Charadrius melodus) LA X T X

Red Cockaded Woodpecker (Picoides 

borealis) LA E X 

Dusky Gopher Frog (Rana sevosa) LA E X

Ringed Map Turtle (Graptemys oculifera) LA T X

Hawksbill Sea Turtle (Eretomchelys 

imbricata) LA E X X 

Kemp’s Ridley Sea Turtle (Lepidochelys 

kempii) LA E X X 

Leatherback Sea Turtle (Dermochelys 

coriacea) LA E X X 

Green Sea Turtle (Chelonia mydas) LA T X X

Loggerhead Sea Turtle (Caretta caretta) LA T X X

Pallid Sturgeon (Scaphirhynchus albus) LA E X

Gulf Sturgeon (Acipenser oxyrinchus 

desotoi) LA X T X X 

Alabama Shad (Alosa alabamae) LA C X

Plant

Inflated Healsplitter (Potamilus inflatus) LA T X

Louisiana Quillwort (Isoetes louisianensis) LA E X

Louisiana Black Bear (Ursus americanus luteolus)

The Louisiana black bear was listed as a threatened species in 1992. The Louisiana black 

bear is a subspecies of the American black bear, found in Louisiana, south Mississippi 

and east Texas. This bear is usually black in color and typically weighs 150 to 300 

pounds as an adult (USFWS, 2008). The Louisiana black bear was numerous during 

colonial times and may have inhabited the project area, but no documented cases exist in 

this area for the twentieth century.

Bald Eagle (Haliaeetus leucocephalus)

Bald eagles live near rivers, lakes, and marshes where they can find fish, their staple food 

(USFWS, 2009a). The successful recovery of bald eagle populations within the 

continental United States resulted in the delisting of the species from the Endangered 

Species List by the USFWS on August 9, 2007. Bald eagles may occur in the project 

area but no nest trees are documented within the area of direct project impacts. 
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Brown Pelican (Pelecanus occidentalis)

The listed brown pelican, completely extirpated from Louisiana by the 1960s (source: 

http://www.lacoast.gov/articles/bps/2/index.htm), now commonly feeds in adjacent 

shallow estuarine waters, using sand spits and offshore sand bars as resting and roosting 

areas. Brown pelicans commonly breed on Breton Island, which is within the project 

area. They also forage in the waters of Breton and Chandeleur Sounds and Lake Borgne. 

Major threats to this species include chemical pollutants, colony site erosion, disease, and 

human disturbance. Brown pelicans live in coastal regions along the Gulf and feed 

primarily on fish. The successful recovery of the brown pelican population within the 

continental United States resulted in the delisting of the species from the Endangered 

Species List by the USFWS on November 17, 2009. Brown pelicans inhabit the area, but 

are highly mobile and expected to move to the nearby Chandeleur Islands while 

restoration operations are occurring on Breton Island. 

Piping Plover (Charadrius melodus)

The piping plover (including the threatened [Great Plains] and endangered [Great Lakes] 

populations) was listed as T&E on December 11, 1985. The piping plover is a shorebird 

that inhabits open beaches, alkali flats, and sandflats of North America. It breeds 

primarily along the Atlantic coast from North Carolina to southern Canada, along rivers 

and wetlands of the northern Great Plains, from Nebraska to the southern prairie 

provinces, and along portions of the western Great Lakes. The species may occasionally 

use exposed flats in the project area, especially around the Chandeleur and Breton 

Islands. In winter, most individuals are found on coastal beaches and sand flats from the 

Carolinas to Yucatan, while some scatter through the Bahamas and West Indies (Haig, 

1992). Wintering plovers feed by probing for invertebrates at or just below the surface 

on exposed wet sand in wash zones; intertidal ocean beach; wrack lines; wash over 

passes; mud-, sand-, and algal-flats; and shorelines of streams, ephemeral ponds, lagoons, 

and salt marshes. Beaches adjacent to foraging areas are used for roosting and preening. 

Small sand dunes, debris, and sparse vegetation within these adjacent beaches provide 

shelter from wind and extreme temperatures (source: 

http://www.fws.gov/plover/facts.html). Major threats to this species include: loss and 

degradation to breeding habitat, disturbance of breeding plovers by humans and pets, 

non-motorized beach activities, motor vehicles, beach cleaning, predation, winter habitat 

loss, severe cold weather and storms, hurricanes, and oil spills and other contaminants 

(source: http://www.fws.gov/northeast/pipingplover/recplan/threats.html). 

West Indian Manatee (Trichechus manatus)

The West Indian manatee was listed as endangered on June 2, 1970. The West Indian 

manatee is a large gray or brown aquatic mammal. Adults average approximately 10 feet 

in length and weigh up to 2,200 pounds. Manatees inhabit both salt and freshwater of 

sufficient depth (5 feet to usually less than 20 feet) throughout their range. A few 

individuals have been known to stray as far north as the southern Virginia coast and as far 

west as the coastal waters of Louisiana (USFWS, 2001). The West Indian manatee may 
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occasionally enter Lakes Pontchartrain and Maurepas, and associated coastal waters and 

marshes of Louisiana (USFWS, 2006). In 2001, a manatee was observed passing through 

the IHNC into the Mississippi River (USFWS, 2006). Manatees are found within local 

waterways only during months with warm enough conditions. Manatee populations have 

declined due to collisions with watercraft, entrapment in flood control structures, 

poaching, habitat loss, and pollution. Populations may also be adversely affected by cold 

weather and red tide outbreaks. While rare, the potential exists for the manatee to be 

within the project area.

Gulf Sturgeon (Acipenser oxyrhynchus desotoi)

The Gulf sturgeon was listed as threatened throughout its range on September 30, 1991. 

Gulf sturgeon live in the estuaries and coastal shelf regions of the Gulf of Mexico during 

the cooler months of the year (October to March). Distribution of Gulf sturgeon in 

Louisiana extends from the Mississippi River east to the Pearl River. The majority of 

these sturgeon have their origins in the Pearl River system, where the largest population 

occurs (Carr, Tatman, & Chapman, 1996). Gulf sturgeon have been reported in rivers 

and lakes of the Lake Pontchartrain Basin, and adjacent estuarine areas (USFWS, 2006). 

Within Louisiana, 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). According to the final critical habitat designation, elements 

essential for Gulf sturgeon conservation are habitat components supporting feeding, 

resting, sheltering, reproduction, and migration. Important physical features include: 

abundant prey items within riverine habitats; riverine spawning sites; riverine aggregation 

areas; appropriate flow regime and water quality characteristics; sediment quality; and 

safe and unobstructed migratory pathways (e.g., a river unobstructed by a permanent 

structure, or a dammed river that still allows for passage). Poor water quality, overfishing and habitat alterations that limit or prevent spawning have negatively affected 

Gulf sturgeon populations. 

Pallid Sturgeon (Scaphirynchus albus)

The pallid sturgeon was listed as endangered throughout its range on October 9, 1990. 

The pallid sturgeon is a bottom oriented, large river obligate inhabiting the Missouri and 

Mississippi Rivers from Montana to Louisiana and the Atchafalaya River. The pallid 

sturgeon is adapted to the predevelopment habitat conditions that historically existed in 

these large rivers (USFWS, 2009b). The pallid sturgeon was listed due to the apparent 

lack of recruitment for over 15 years, and the habitat threats existing at the time of listing. 

Destruction and alteration of habitats by human modification of the river system is 

believed to be the primary cause of decline in reproduction, growth, and survival of the 

pallid sturgeon. The curtailment of range and habitat destruction/modification were 

primarily attributed to the construction and operation of dams on the upper Missouri 

River and modification of riverine habitat by channelization of the lower main stem 

Missouri and Mississippi Rivers. Dams substantially fragmented pallid sturgeon range in 

the upper Missouri River. However, free-flowing riverine conditions currently exist 
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throughout the lower 2,000 miles (60 percent) of the pallid sturgeon’s historical range. 

(USFWS, 2009) Until this past decade, they were considered a rare occurrence in the 

Lower Mississippi. New information from recent collection efforts indicates that the 

Mississippi River currently supports substantial numbers of wild fish. Since 1997, more 

than 200 pallid have been collected at more than 60 locations in the Mississippi River 

between the confluence of the Missouri River and New Orleans (Bettoli, 2006). When 

listed, there were only 28 recognized records of pallid sturgeon from the Mississippi 

River, with no recognized records from the Atchafalaya River. (USFWS, 2009) 

Sea Turtles

Five listed sea turtle species may occur in the project area, but typically are found in Gulf 

of Mexico waters: the Kemp’s Ridley sea turtle, Atlantic green sea turtle, hawksbill sea 

turtle, loggerhead sea turtle, and leatherback sea turtle. All sea turtles occurring within 

the Gulf of Mexico are generally found in and around the Breton and Chandeleur Sounds. 

The barrier island restoration feature would be the portion of the project area where there 

is the likelihood of encountering these turtles. 

Green Sea Turtle (Chelonia mydas)

The green sea turtle was listed as threatened in U.S. waters, except for the Florida 

breeding population which was listed as endangered, on July 28, 1978. Due to the 

inability to distinguish between these populations away from the nesting beach, green 

turtles are considered endangered wherever they occur in U.S. waters. The green sea 

turtle is one of the largest marine turtles with adult weights averaging between 250 to 450 

pounds (Dundee, 1989). In the Atlantic and Gulf of Mexico waters, the green sea turtle 

typically inhabits areas adjacent to the coastline and has been known to have a range 

spanning from Texas to as far north as Massachusetts (NOAA-1).

Kemp’s Ridley Sea Turtle (Lepidochelys kempii)

The Kemp’s ridley sea turtle was listed as endangered throughout its range, on December 

2, 1970. The Kemp’s ridley sea turtle is the smallest of the sea turtles with adults 

reaching an approximate length of two to 2.5 feet and weighing around 110 pounds 

(Dundee, 1989). During the months of May to October, this species can be found in and 

around the shoreline of Louisiana with adults occupying areas around the mouth of the 

Mississippi River during the spring and summertime (LDWF, 2005). 

Loggerhead Sea Turtle (Caretta caretta)

The loggerhead sea turtle was listed as threatened throughout its range on July 28, 1978. 

The loggerhead sea turtle is also one the larger marine turtles with average adult lengths 

ranging from 3 to 7 feet and weighing approximately 300 to 1,100 pounds (Dundee, 

1989). In Louisiana, this species has been found nesting on the Chandeleur Islands, Isle 

Dernieres, and Grand Isle in Terrebonne Parish (Dundee, 1989). 
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Hawksbill Sea Turtle (Eretmochelys imbricata)

The hawksbill sea turtle was listed endangered throughout its range on June 2, 1970. 

Commercial harvest, habitat degradation, coastal development, disease, and predation 

have all contributed to the decline of the species. In the Gulf region, this species has 

been sighted along the Florida coast, specifically in the reef, as well as along the Texas 

coastline. 

Leatherback Sea Turtle (Dermochylys coriacea)

The Leatherback sea turtle was listed as endangered throughout its range on June 2, 1970. 

Commercial harvest, habitat degradation, coastal development, disease, and predation 

have all contributed to the decline of the species. The leatherback typically inhabits deep 

ocean waters, but migrates to barrier islands and coastal beaches to nest. Nesting of 

leatherback sea turtles in Florida occurs from April to July, while nesting of this species 

in Louisiana has never been reported. 

3.20 SOCIOECONOMIC AND HUMAN ENVIRONMENT

3.20.1 Historic and Existing Conditions

This resource is 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.

3.20.2 Population

The study area includes portions of the Mississippi River Deltaic Plain within coastal 

southeast Louisiana and parts of southwest Mississippi encompassing approximately 3.8 

million acres (over 6,000 square miles) of land and open water. In Louisiana, the study 

area includes the Upper, Middle, and Lower Lake Pontchartrain sub-basins. In 

Mississippi, the study area includes the western Mississippi Sound, its bordering 

wetlands, and Cat Island. These areas include portions of the Pearl River and the coastal 

stream hydrologic basins in Mississippi. The study area was developed to encompass the 

Lake Borgne ecosystem and areas that may have been affected by the MRGO navigation 

channel. The MRGO channel may have affected salinity as far west as Lake Maurepas. 

To the east, the MRGO channel was dredged through open water between the Breton and 

Grand Gossier Islands. The MRGO channel affected portions of the Lake Borgne 
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ecosystem to the north and altered hydrology potentially as far south as the River Aux 

Chenes Ridge.

Louisiana parishes in the study area include Ascension, Jefferson, Livingston, Orleans, 

Plaquemines, St. Bernard, St. Tammany, St. Charles, St. James, St. John the Baptist, and 

Tangipahoa Parishes. Mississippi counties in the study area include Hancock and 

Harrison. The 2008 estimated population for the study area parishes and counties in 

Louisiana and Mississippi respectively, are shown in table 3-29. 

 Table 3-29: 2008 Estimated 

Population – Post Katrina

Parish / County Population

Louisiana

Ascension 101,789 

Jefferson 436,181 

Orleans 311,853 

Livingston 120,256 

Plaquemines 21,276 

St. Bernard 37,722 

St. Tammany 228,456 

St. Charles 51,546 

St. James 21,331 

St. John the Baptist 46,994 

Tangipahoa 117,001 

Mississippi

Hancock 40,140

Harrison 178,460 

Due to the absence of project related construction features in large portions of the study 

area, the study area was reduced in order to facilitate ease of discussion of existing 

conditions and potential impacts. The proposed project footprints (also known as 

measures) are located in mostly remote and uninhabited coastal wetlands within St. 

Bernard and Orleans Parishes. There are no communities or human populations 

identified at the census block level within the specific project footprints. However, there 

are some population centers near the project footprints. These include the towns of 

Arabi, Meraux, Violet, and Poydras located in St. Bernard Parish, along with the larger 

City of Chalmette. To the northwest in Orleans Parish is Michoud, which falls in the 

Greater New Orleans area. Orleans Parish had a population of 484,674 in 2000; in 

contrast, the estimated post-storm population in July 2009 was 354,850 

(http://www.gnocdc.org/census_pop_estimates.html). St. Bernard Parish reported a 

population of 67,229 persons in 2000. The post-storm population reported in July 2009 

was reported to be 40,655 persons. Post-storm July 2009 population estimates for the 

smaller population centers were calculated by multiplying active residential address by 

zip code by the average number of members per household. Table 3-30 summarizes the 

July 2009 population for cities and towns within the project area. Among the areas near 

the project footprints, Chalmette is reported to be the largest population center, followed 

by Michoud and Violet, respectively. 

SOURCE: US Census Bureau
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Table 3-30: July 2009 Census Populations of 

Cities and Towns near the Project Area

City, Town, or Municipality Population

Arabi 4,103

Chalmette 17,279

Meraux 3,907

Violet 5,499

Poydras 4,269

Michoud 7,705 1

3.20.3 Community Cohesion

A community can be defined as a group of people that share common behavior patterns, 

such as social interactions, use of local facilities, participation in local organizations, 

shared attitudes, and identification with and commitment to a particular area. Based on a 

review of U.S. Census data and local population studies, it can be concluded that many of 

the population centers near the proposed project areas were well established prior to 

Hurricane Katrina. Long-standing residency in an area typically increases community 

interaction and cohesion among residents. According to 2000 census data, 42.3 percent

of Violet householders living in owner-occupied housing moved into those units between 

the years of 1970 and 1989; an additional 10.8 percent moved into those units in 1969 or 

earlier. For Chalmette the numbers are more drastic: 39.7 percent of Chalmette 

householders living in owner-occupied housing moved into those units between the years 

of 1970 and 1989, and an additional 25.0 percent moved into those units in 1969 or 

earlier. Results for population centers are shown in table 3-31. 

Table 3-31: Tenure by Year Householder Moved into Unit

for Owner-Occupied Housing Units (% )

City, Town, or 

Municipality

1999 to 

March 2000

1995 to 

1998 

1990 to 

1994 

1980 to 

1989 

1970 to 

1979 

1969 or 

earlier

Arabi 5.2 11.8 11.2 13.0 12.8 46.0

Chalmette 6.1 16.2 13.0 15.2 24.5 25.0

Meraux 8.8 21.6 20.7 19.9 17.4 11.5

Violet 7.8 21.4 17.7 24.9 17.4 10.8

Poydras 7.9 21.1 19.1 27.5 19.3 5.1

Michoud 7.6 1 18.6 16.9 35.6 16.7 4.6

Housing statistics beyond the year 2000 are not yet available from the census. However, 

despite the displacement of many residents in these areas due to the impact of Hurricane 

Katrina, local population studies as well as the rise in the number of community activist 

groups show that a consistent repopulation has been occurring. Strong ties to 

neighborhoods and a desire to return to previous communities have propelled this 

repopulation, and post-Katrina studies indicate that this trend should continue. 

1

SOURCE: (http://www.gnocdc.org)

 Michoud is included in the Greater New Orleans Metropolitan Area

1

SOURCE: (http://www.gnocdc.org)

 Michoud is included in the Greater New Orleans Metropolitan Area
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3.20.4 Employment and Income

The project footprints are located in mostly remote and uninhabited coastal wetlands 

within St. Bernard and Orleans Parishes. There are no communities or human 

populations within the specific project footprints; hence, there is no employment or 

income base. However, the population centers near the project footprints do support 

sources of income related to oil and gas exploration as well as commercial and 

recreational fishing. Based on the 2005-2007 American Community Survey 3-year 

Estimates, in Orleans Parish nearly 10 percent of the labor force was employed in 

occupations connected with the petroleum industry. Corresponding information for St. 

Bernard Parish is not reported for this time period due to the large-scale displacement of 

persons after Hurricane Katrina. 

In general, the petroleum industry in the state accounts for almost 25 percent of the total 

state revenues and employs more than 116,000 people (about 6 percent of the state’s total 

workforce). These workers earn almost twelve percent of the total wages paid in 

Louisiana. Indirect employment levels in support industries make this economic sector 

more important than is indicated by the direct employment figures. However, the recent 

British Petroleum oil leak in the Gulf of Mexico as well as the 6-month moratorium on 

deep water exploration and production makes it difficult to provide data reflective of the 

current employment situation.

The most recent data show median household income in 2008 for Arabi as $44,906; for 

Chalmette $48,561; for Meraux $60,514; for Violet $43,683; and for Poydras $35,489. 

Data was not available for Michoud. (http://www.city-data.com/city/Louisiana.html) 

3.20.5 Infrastructure

The project footprints are located in mostly remote and uninhabited coastal wetlands 

within St. Bernard and Orleans Parishes. In St. Bernard Parish, the Alabama Great 

Southern Railroad (a.k.a. Southern Norfolk), E. St. Bernard Highway, and E. Judge Perez 

Highway are all adjacent to the Mississippi River levee and would be crossed by the 

Violet Freshwater Diversion. Other than buried oil, gas, and utilities pipelines and 

communication and cable lines that pass through the area, there is no infrastructure 

(roads, buildings, etc.) within the rest of the project footprints. 

3.20.6 Oil, Gas and Utility

The total assessed value of interstate pipelines alone in Louisiana is over $600 million 

and the pipeline industry employs 4,855 persons with an annual payroll of $250 million. 

Louisiana is laced with thousands of pipelines conveying oil, gas, and other liquid and 

gaseous materials for short and long distances.

There are 13 utility crossings along the MRGO managed by seven companies that are 

provided in table 3-32 and shown in figure 3-20. The Air Products and Chemical 

Company has pipelines at Miles 58.9 and 58.7. The Tenneco Company has a pipeline at 
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Mile 57.9 and two pipelines at Mile 42.7. The Collins Pipeline Company has a pipeline 

at Mile 57.7. The Southern Natural Gas Company has four pipelines at Miles 54.7, Mile 

54.7, Mile 54.6, and Mile 23.7. The Chevron Pipeline Company has a pipeline at Mile 

45.6. The Bellsouth Company has a telephone cable line at Mile 41.6. The LA Intrastate 

Gas Company has a pipeline at Mile 26.5. Figure 3-21 displays the existing pipelines 

and oil and gas wells located in Lake Borgne. 

Figure 3-20: Utility Crossings in and near the Project Area

Table 3-32: MRGO Utility Crossings and Owners

Mile Marker Description Owner

58.9 9” Sub Gas Pipeline Air Products and Chemical

58.7 12” Sub Hyd Pipeline Air Products and Chemical

57.9 12” Sub Gas Pipeline Tenneco Oil Co.

57.7 16” Sub Gas Pipeline Collins Pipeline Co.

54.7 20” Sub Gas Pipeline Southern Natural Gas Co.

54.7 24” Sub Gas Pipeline Southern Natural Gas Co.

54.6 30” Sub Gas Pipeline Southern Natural Gas Co.

45.6 20” Sub Gas Pipeline Chevron Pipeline Co.

42.7 36” Sub Gas Pipeline Tenneco Oil Co.
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Table 3-32: MRGO Utility Crossings and Owners

Mile Marker Description Owner

42.7 30” Sub Gas Pipeline Tenneco Oil Co.

41.6 Sub Telephone Cable Bellsouth Telephone

26.5 16” Sub Gas Pipeline LA Intrastate Gas

23.7 6” Sub Gas Pipeline Southern Natural Gas Co.

Figure 3-21: Pipelines and Oil and Gas Wells in Lake Borgne and Vicinity

3.20.7 Flood Control and Protection Levees

Continued degradation of the landbridge separating Lake Borgne from the MRGO 

channel, the conversion of existing wetlands to open water habitats, and the continued 

bank-line erosion and sloughing of the shoreline are concerns for southern Louisiana. 

The project footprints do not presently contain any flood control or hurricane protection 

structures. However, a portion of the hurricane protection system, a series of levees and 

floodgates designed to protect against storm surges associated with tropical systems, is 

located immediately adjacent to these areas to the north and west (see figure 3-22). 
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Restoration Plan 3-109 June 2012

Alternative plan formulation considered providing shoreline protection measures along 

the MRGO to protect portions of the HSDRRS. Along the southwestern shoreline of the 

MRGO, a portion of the HSDRRS levee extends from Mile 47 to Mile 60 to protect the 

population centers of Chalmette, Arabi, Poydras, Meraux, and Violet. This levee system 

is built to a height of 20.0 feet North American Vertical Datum (NAVD88) and has 

floodgates at Bayou Dupre and Bayou Bienvenue. A levee along the northern shoreline 

of the GIWW protects portions of eastern New Orleans and Michoud, and levees along 

the IHNC protect portions of eastern New Orleans and Arabi. Many of these levees were 

damaged during Hurricane Katrina and have been rebuilt.

There are on-going efforts to raise the level of protection to conform to the updated 

requirement for a 100-year level of protection. The floodwall proposed for the HSDRRS

would be located in the northwest corner of the project area (see figure 3-22). It would 

consist of a floodwall constructed to an elevation of 26 feet above the average water level 

with a closure structure across the MRGO channel south of Bayou Bienvenue and sector 

gates across Bayou Bienvenue and the GIWW that would be closed during storm surge 

situations (USACE, 2008).

Figure 3-22: Flood Protection Features near the Project Area
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3.21 ENVIRONMENTAL JUSTICE 

Environmental Justice (EJ) is institutionally significant because of Executive Order (EO) 

12898 of 1994 (EO 12898) and the Department of Defense’s Strategy on Environmental 

Justice of 1995, which direct Federal agencies to identify and address any 

disproportionately high adverse human health or environmental effects of Federal actions 

to minority and/or low-income populations. Minority populations are those persons who 

identify themselves as Black, Hispanic, Asian American, American Indian/Alaskan 

Native, and Pacific Islander. A minority population exists where the percentage of 

minorities in an affected area either exceeds 50 percent of the total population or is 

meaningfully greater than in the general population. Low-income populations as of 2000 

are those whose income are $22,050 for a family of four and are identified using the 

Census Bureau’s statistical poverty threshold. The Census Bureau defines a “poverty 

area” as a Census tract with 20 percent or more of its residents below the poverty 

threshold and an “extreme poverty area” as one with 40 percent or more below the 

poverty level. This is updated annually at http://aspe.hhs.gov/poverty/09poverty.shtml. 

This resource is technically significant because the social and economic welfare of 

minority and low-income populations may be positively or disproportionately impacted 

by the proposed actions. This resource is publicly significant because of public concerns 

about the fair and equitable treatment (fair treatment and meaningful involvement) of all 

people with respect to environmental and human health consequences of federal laws, 

regulations, policies, and actions. 

A potential disproportionate impact may occur when an adverse impact is predominately 

borne by the percent minority (50 percent) and/or percent low income population (20 

percent) in an EJ study area which may be greater than those in the reference community. 

For purposes of this analysis, all Census Block Groups within a one mile radius of the 

project footprint are defined as the EJ study area. St. Bernard Parish, which has the 

nearest and most significant community population in the MRGO area, is considered the 

reference community of comparison, whose population is therefore considered the EJ 

reference population for comparison purposes within various city limits. In some 

instances, parish figures may be used for unincorporated areas located within one mile of 

the proposed project footprint. 

The methodology, consistent with EO 12898, to accomplish this EJ analysis includes, 

identifying low-income and minority populations within the MRGO project area using 

up-to-date socio-economic statistics, aerial photographs, 2000 U.S. Census records, 

Environmental Systems Research Institute, Inc. (ESRI) estimates, as well as conducting 

community outreach activities such as public meetings. Despite the 2000 U.S. Census 

being nine years old, it serves as a logical baseline of information and is the primary 

deciding variable per data accuracy and reliability for the following reasons:

• Census 2000 data is the most accurate source of data available due to the sample 

size of the Census decennial surveys. With one of every six households surveyed, 

the margin of error is negligible.
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• The Census reports data at a much smaller geographic level than other survey 

sources, providing a more defined and versatile option for data reporting. 

• Census information sheds light upon the demographic and economic 

characteristics of the area prior to Hurricane Katrina. By accounting for the 

absent population, the analysis does not exclude potentially low income and 

minority families that wish to return home. 

3.21.1 Historic Conditions

The concept of “environmental justice” is rooted in Title VI of the Civil Rights Act of 

1964, which prohibited discrimination based on race, color and national origin, and other 

nondiscrimination statutes as well as other statutes including the National Environmental 

Policy Act of 1969, the Uniform Relocations Assistance and Real Property Acquisition 

Policies Act of 1970, and 23 U.S.C Section 109 (h). In 1971, the CEQ’s annual report 

acknowledged racial discrimination adversely affects the environment of the urban poor. 

During the next ten years, activists maintained that toxic waste sites were 

disproportionately located in low-income and areas populated by “people of color.” By 

the early 1980s, the environmental justice movement had increased its visibility and 

broadened its support base (Commission for Environmental Equality, 2009). 

This led to the United Church of Christ (UCC) undertaking a nationwide study and 

publishing Toxic Waste and Race in the United States (UCC, 1987). This eventually 

gained the attention of the federal government and in 1992 the EPA’s Office of 

Environmental Equity was established. In 1994, EJ was institutionalized within the 

federal government through EO 12898 (EPA, 1995a), which focused federal attention on 

human-health and environmental conditions in minority and low-income communities 

(EPA, 1995a, 1995b, 1995c, 1995d). 

EO 12898 requires greater public participation and access to environmental information 

in affected communities. The results of early efforts and research (UCC, 1987) into EJ 

suggested that environmental amenities and toxic waste sites were not uniformly 

distributed among income groups, classes, or ethnic communities. Disparities of this 

nature may have been and continue to be the result of historical circumstances, lack of 

community participation, or simply inadequate or inappropriate oversight. Consequently, 

dialogue with some community groups were not conducted and their concerns not 

considered in the decision making process on local or federal actions. 

3.21.2 Existing Conditions

Biloxi Marsh

The proposed Biloxi Marsh area extends from Biloxi, Mississippi to Eloi Bay along the 

eastern coastal wetlands of St. Tammany Parish, Louisiana. According to the 2000 U.S. 

Census, minority persons accounted for 15.8 percent of the population compared to 38.6 

statewide. The low income figures for this area was 10 percent compared to 19.6 

statewide. As these figures are less than state figures for Louisiana and because no 
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Restoration Plan 3-112 June 2012

minority or low-income populations have been identified that would be adversely 

impacted by the proposed project as determined above this area did not receive further EJ 

consideration per requirements of EO 12898. 

MRGO Shoreline Protection

The proposed MRGO Shoreline Protection project area is located along the MRGO 

shoreline in St. Bernard Parish, Louisiana. According to the 2000 U.S. Census, minority 

persons accounted for 17.6 percent of the population compared to 38.6 statewide. The 

low income figures for this area was 13.1 percent compared to 19.6 statewide. As these 

figures are less than both parish and state figures for Louisiana and because no minority 

or low-income populations have been identified that would be adversely impacted by the 

proposed project as determined above this area did not receive further EJ consideration 

per requirements of EO 12898. 

Central Wetlands Area

The proposed Central Wetlands area is within one mile of residential areas and extends 

from Verret, Louisiana to Arabi, Louisiana in the Central Wetlands along the MRGO. 

According to the 2000 U.S. Census, minority persons accounted for 48 percent of the 

population compared to 38.6 statewide. The low income figures for this area was 17.6 

percent compared to 19.6 statewide. As these figures are significantly higher than both 

county and state figures for Louisiana and because this area is inhabited by such a large 

minority and/or low-income populations it received further EJ consideration, such as 

additional outreach efforts, per requirements of EO 12898. 

Violet, Louisiana Freshwater Diversion

The proposed Violet Freshwater Diversion is located in the community of Violet, 

Louisiana. According to the 2000 U.S. Census, minority persons accounted for 46.5 

percent of the population compared to 38.6 statewide and 17.6 parish-wide. The low 

income figures for this area were 21.7 percent compared to 19.6 statewide and parishwide. The minority and low-income populations in Violet are more than parish and state 

figures for Louisiana. While the city of Violet does not meet the 50 percent population 

standard it does, however, exceed the 20 percent low-income population standard and 

therefore has received further EJ consideration per requirements of EO 12898. The 

proposed project footprint is adjacent to two subdivisions that are predominately minority 

neighborhoods and thus meet EO 12898 requirements. 

East Orleans Landbridge

The proposed East Orleans Landbridge area extends from the Rigolets in Louisiana to 

Shell Beach along the western shoreline of Lake Borgne. According to the 2000 U.S. 

Census, minority persons accounted for 19 percent of the population compared to 38.6 

statewide. The low income figures for this area was 11.8 percent compared to 19.6 

statewide. As these figures are less than both parish and state figures for Louisiana and 
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Restoration Plan 3-113 June 2012

because no minority or low-income populations have been identified that would be 

adversely impacted by the proposed project as determined above this area did not receive 

further EJ consideration per requirements of EO 12898. 

Terre aux Boeufs

The proposed Terre aux Boeufs area extends from Reggio, Louisiana to Black Bay along 

the Central Wetlands and eastern coastal wetlands of St. Bernard Parish, Louisiana. 

According to the 2000 U.S. Census, minority persons accounted for 16 percent of the 

population compared to 38.6 statewide. The low income figures for this area was 13.1 

percent compared to 19.6 statewide. As these figures are less than both parish and state 

figures for Louisiana and because no minority or low-income populations have been 

identified that would be adversely impacted by the proposed project as determined above 

this area did not receive further EJ consideration per requirements of EO 12898. 

Florissant

The proposed Florissant area is located along Florissant Highway in a wetland area 

adjacent to the MRGO. According to the 2000 U.S. Census, minority persons in St. 

Bernard Parish, Louisiana accounted for 16 percent of the population compared to 38.6 

statewide. The low income figures for this area was 13.1 percent compared to 19.6 

statewide. As these figures are less than both parish and state figures for Louisiana and 

because no minority or low-income populations have been identified that would be 

adversely impacted by the proposed project as determined above this area did not receive 

further EJ consideration per requirements of EO 12898. 

Hopedale

The proposed Hopedale area is located in a wetland adjacent to Hopedale Highway in St. 

Bernard Parish, Louisiana. According to the 2000 U.S. Census, minority persons 

accounted for 16 percent of the population compared to 38.6 statewide. The low income 

figures for this area was 13.1 percent compared to 19.6 statewide. As these figures are 

less than both parish and state figures for Louisiana and because no minority or lowincome populations have been identified that would be adversely impacted by the 

proposed project as determined above this area did not receive further EJ consideration 

per requirements of EO 12898. 

3.22 HISTORIC AND CULTURAL RESOURCES

3.22.1 Louisiana

Prehistoric and historic archaeological sites, as well as standing structures, are generally 

located along the natural levees bordering active streams and abandoned stream channels. 

Any projects that cross or run along such geographic features will have the possibility of 

impacting historic properties that may be eligible for listing on the National Register of 
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Historic Places (NRHP). Adverse impacts to historic properties can be mitigated by 

either avoiding the historic properties or by performing data recovery (excavation). 

Identification of historic properties is made through a Phase I survey which simply 

identifies the location, extent, and depth of potential historic properties. If these potential 

historic properties cannot be avoided, then a Phase II study is required. In a Phase II 

study, the sites are tested by standard archaeological procedures to determine if they are 

indeed eligible for the NRHP or if standing structures are involved, then more detailed 

research will be performed. If a site is found to be eligible and the project cannot be 

designed to avoid such properties, full scale excavations will be conducted for 

archaeological sites and buildings will be recorded following the procedures of the 

Historic American Buildings Survey or the Historic American Engineering Record. 

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 

NHRP. 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 which 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 bodies of water, 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. 

3.22.2 Mississippi

Southern Mississippi is within the coastal plain which forms the northern margin of the 

Gulf of Mexico. Most of the coastal plain consists in Pleistocene deposits and is 

bordered by saltwater marshes. The coastal zone of Mississippi is comprised to the 

Mississippi Sound while the extreme western portion of the Mississippi coast is within 

the Pearl River basin. 

The prehistory of southern Mississippi dates from the Paleo-Indian period (10,000 – 

6,000 B.C.) to the Mississippi period (A.D. 1200 – 1700). Historic settlement of the 

Mississippi coast dates to 1699 when Pierre Le Moyne, Sieur d’Iberville founded Fort 

Maurepas near modern day Ocean Springs.

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 USACE, 

1995. 
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3.23 RECREATIONAL RESOURCES

3.23.1 Historic Conditions

Historically, many residents of New Orleans and the surrounding areas, such as Jefferson 

and St. Bernard Parishes, constructed fishing camps along the old US 90 corridor near 

Lake Catherine and along the natural ridges in St. Bernard Parish in communities such as 

Yscloskey, Hopedale, and Delacroix. As these areas grew in popularity for recreational 

fishing and hunting, supporting facilities such as marinas and boat launches developed. 

Consumptive recreational uses both in Louisiana and Mississippi waters have 

traditionally been saltwater fishing along with recreational crabbing, shrimping, 

freshwater fishing, and hunting for waterfowl, deer, and small game in wooded swamps 

and along natural ridges. Non-consumptive activities, hiking, boating, bird watching, 

camping, and picnicking, attract far fewer participants. 

The project area has traditionally provided excellent saltwater fishing opportunities. 

Anglers have traveled from throughout the region to fish in these waters, especially for 

the nationally televised Redfish Cup. 

As throughout much of coastal Louisiana, the project area has experienced substantial 

coastal erosion, loss of wetlands and increasing salinity levels. Some of the effects were 

exacerbated by past and recent hurricanes. As wooded swamp, marsh habitat, and 

submerged aquatic vegetation in the area have disappeared, waterfowl habitat has 

diminished and duck hunting opportunities have decreased. 

Along with coastal erosion, the area has experienced substantial subsidence and together 

these forces have deteriorated wooded swamps and natural ridges that formerly supported 

habitat for deer and other small game species. As this habitat has diminished, hunting 

opportunities have decreased. 

3.23.2 Louisiana Recreational Resources

Recreation areas that were examined in the project area include two National Wildlife 

Refuges (NWR), two Wildlife Management Areas (WMA), and one State Historic Site 

(SHS), as well as other significant recreation areas. These areas alone represent 

approximately 100,000 acres that are visited annually nearly 450,000 times for 

recreational purposes. Recreation areas include 15 miles of trails for hiking and biking, 

38 boat ramps, four fishing piers, one classroom space, two visitor centers or museums, 

two picnic shelters, and one historic site. These recreation areas provide opportunities for 

hunting, hiking, biking, boating, bird watching, fishing and crabbing, crawfishing, 

shrimping, education, camping, picnicking, and playing. 

Recreation resources are publicly significant because of: the high value that the public 

places on fishing, boating, and hunting as measured by the large number of fishing and 

hunting licenses sold in Louisiana and the large per-capita number of recreation boat 

registrations in Louisiana. 
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The table 3-33 below shows the number of fishing licenses, hunting licenses and boat 

registrations in the project area.

Table 3-33: FY 2008 Boater Registrations, Fishing / Hunting Licenses

Parish / 

County

Fishing Licenses Hunting Licenses

Boater 

Registrations

ResidentFreshwaterResidentSaltwater

Non-Resident 

(NR) - 

Freshwater

NR - 

Saltwater

NR -

Salt 

Season Resident

NonResident

St. Bernard 2,686 2,683 308 300 101 1,043 14 2,294

Plaquemines 3,104 3,136 1,215 1,211 160 822 34 3,340

Orleans 4,844 4,837 960 909 117 1,523 59 4,157

St. Tammany 26,512 25,837 4,834 4,324 1,179 9,756 336 18,054

Jefferson 49,267 49,131 11,406 11,151 1,571 13,319 369 19,258

Hancock, MS 961 232 166 26 6 584 85 4,943

Harrison, MS 7,515 983 1,181 142 56 3,937 417 15,170

The fishing industry alone is the second largest industry in the state, and has brought in 

over one billion dollars in the last year from waterways east of Lake Pontchartrain. 

Fishing and boating marinas will get damaged from hurricanes, and some completely 

obliterated, but because of the high demand of this recreational activity, marinas rebuild 

almost immediately. This industry has proven to be strong, and it is important to 

maintain and prolong the surrounding land area, including the boat launches. 

There are several boat launches throughout the project area. People enjoy pleasure 

boating and fishing in and around these recreational launches. Typical launch sites 

within St. Bernard and Plaquemines Parishes east of the Mississippi River are detailed 

below. 

a. The Belair Pump Station launch provides a gravel ramp approximately 18 feet 

wide by 15 feet in length. There is parking for 15 vehicles; however, no lighting, 

power, water or services are available. The launch is located at a pipeline canal 

which could possibly be taken to the other pipeline canals that run east into the 

marsh or connect to River aux Chenes and head south into various small lakes, 

bays, canals, and eventually Breton Sound. 

b. The Pointe a la Hache Marina Boat Launch provides two concrete boat ramps, 

each 15 feet wide by 20 feet in length. There is also an electric boat lift as well as 

parking for approximately 870 vehicles. The launch provides lighting, power, and 

water along with a fuel station and a small grocery store and bait shop. The 

marina has a launch, as well as in-water slips located at the back levee on a canal 

that runs parallel to the Mississippi River. Numerous bayous and cut offs of this 

canal provide access to bays and lakes in the marsh, all of which eventually lead 

to Breton Sound. 

c. Dean’s Free Boat Launch provides two concrete ramps, each 11 feet wide by 22 

feet in length. There is parking for approximately 93 vehicles and lighting is 

provided. The launch does not have available power, water, or other services. 

The launch is located at the end of a company canal and runs south connecting to 
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a bayou which leads into Lake Lery. From the lake, there is a connection to 

Bayou Lery near Delacroix which provides access to various bays and canals on 

its way to Breton Sound. 

d. The End of the World Marina is located in Delacroix and is a pay launch that 

costs $5.00. It provides a shell ramp approximately 37 feet wide by 25 feet in 

length. There is parking for 156 vehicles and lighting is provided. There is no 

power, water, or other services provided. Serigne’s Boat Launch is also located in 

Delacroix and is a pay launch. The launch does not have a ramp, but provides an 

electric lift. There is parking for 355 vehicles, as well as lighting, fuel, and water. 

There is also a small grocery and bait shop. Both of these launches are at the end 

of the Delacroix community located on Bayou Lery. The bayou can be taken all 

the way to Breton Sound and also has numerous bayous and canals off the main 

bayou into the surrounding marsh. 

e. Hopedale Marina and Convenience Store is a pay launch that costs $5.00. The 

facility includes a concrete ramp approximately 21 feet wide by 8 feet in length. 

There is also an electric lift and parking for 146 vehicles. No lighting or power is 

provided, but water and fuel are available. There is also a convenience store and 

bait shop. The launch is located on Bayou La Loutre and provides access to the 

MRGO and Breton Sound to the east. There are also several pipeline canals off 

the bayou that run south into the marsh, bays, and lakes. 

f. The Reggio Marina is a pay launch that costs $5.00 and includes a gravel ramp 

approximately 23 feet wide by 30 feet in length and a concrete ramp 26 feet wide 

by 30 feet in length. There is also an electric lift and parking for 143 vehicles. 

Fuel, water, power, and lighting are all available, as well as a small grocery store. 

The launch is located at the juncture of a pipeline canal and Bayou Lery. The 

pipeline canal connects to Lake Amedee and various outlets into the marsh area. 

g. Frank Campo’s Marina is a pay launch that costs $7.00 to $12.00. There is no 

ramp, but an electric lift is provided as well as parking for 61 vehicles. Power, 

water, fuel, and lighting are provided. The launch is located at the MRGO and 

Shell Beach with access to Lake Borgne, Bayou La Loutre, and Breton Sound via 

the MRGO. 

h. The Breton Sound Marina is a pay launch that provides a concrete ramp 28 feet in 

width by 4 feet in length, as well as an electric lift. Parking is available for 464 

vehicles and water, fuel and lighting are also available. There is a small grocery 

and bait shop. The launch is located on Bayou La Loutre at the MRGO and 

several pipeline canals off the bayou provide access to the marsh and lagoons to 

the south. The MRGO provides direct access to Breton Sound. 

i. Bayou Bienvenue Marina is a pay launch that costs $5.00. The facility includes 

two concrete ramps approximately 25 feet wide by 50 feet in length and 15.5 feet 

wide by 32 feet in length. There is parking for 203 vehicles, as well as 58 

launched stalls. Water, power and lighting is provided, but fuel is not available. 

There is also a small store, Bait Incorporated, which sells tackle and lubricants. 

The launch is located on Bayou Bienvenue near Parish Road just north of 

Chalmette. The bayou can be taken out to the MRGO, surrounding marsh, or into 

Lake Borgne. 
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j. The launch near Fort Pike is a free public launch located at the Fort Pike 

Commemorative Area. The facility includes a concrete ramp approximately 20 

feet wide by 40 feet in length. There is parking for 157 vehicles; however, no 

lighting, power, water or services are available. The launch is located on the 

Rigolets with direct access to Lake Pontchartrain or Lake St. Catherine. The 

Rigolets can also be taken east into Lake Borgne and the Mississippi Sound. 

k. Pip’s Launch is a pay launch that charges $4.00 and includes a concrete ramp 22 

feet in width by 20 feet in length, as well as an electric lift. There is parking for 

143 vehicles and power, fuel, and water are available. There is also a small 

grocery store. The launch is located between the Hopedale Marina and Breton 

Sound Marina on Bayou La Loutre and provides access to the same areas. 

3.23.2.1 Recreational Resource Facilities in the Project Area

The following table lists the state and Federal recreational facilities that are located in the 

project area and provides information about size and annual usage. For many sites, 

visitors are not counted because no parking or entrance fees are collected and there are 

many entrances to the areas.

The state- and Federally-managed facilities in the project area vary widely in terms of the 

recreational opportunities provided. The table is based on data gathered through a review 

of publicly available brochures, contacts with park or refuge managers, and site visits. It 

provides details about the availability of different types of recreational opportunities at 

each of the facilities.

The 2003-2008 Louisiana Statewide Comprehensive Outdoor Recreation Plan (SCORP) 

(available online June 1, 2008 through http://www.crt.state.la.us/parks/iSCORP.aspx) 

provides a statewide inventory of recreation resources and identifies recreational needs. 

While regions defined in the SCORP do not fit perfectly within the study area, SCORP 

Region 1 is a larger region which includes the project area. The state- and Federallymanaged areas described above represent just a portion of the more than 282,000 acres of 

recreational facilities inventoried for SCORP Region 1. Federal, state, parish, and 

municipal public recreational facilities provide more than 196,000 acres for hunting, 123 

boat ramps, 1,833 picnic tables, ten beaches, and 320-acres for camping with 263 tent 

sites and 1,739 trailer sites. The SCORP-prioritized needs in this region include 

improving access to enable fishing and boating, funding to support consumptive and nonconsumptive activities on all public recreation areas, more wilderness or primitive 

camping areas, identifying and acquiring large tracts of waterfront lands for large scale 

parks, and addressing the dwindling state of marine resources. 

Other recreational features are provided by parishes and historic communities that attract 

visitors to a variety of heritage and cultural festivals, historical sites, and parks offering 

opportunities for active and passive recreation that include tennis courts, soccer and 

softball fields, swimming pools, and golf courses. 
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Funds from the Land and Water Conservation Fund (LWCF) have supported 47 different 

recreational projects in the study area since 1964. LWCF projects in the project area have 

provided numerous boat ramps and other facilities that enhance opportunities for 

recreation. Actual LWCF expenditures not adjusted for inflation exceed $10 million in 

the study area. Table 3-34 summarizes the number and cost of projects implemented in 

parishes in the project area. (Source: http://waso-lwcf.ncrc.nps.gov/public/index.cfm) 

Table 3-34: LWCF Expenditures in Study Area for Recreational 

Resources

Parish Number of Projects Actual1

Orleans

LWCF Funds Expended

25 $6,610,700.95

St. Bernard 3 $1,214,738.78

St. Tammany 19 $2,258,501.45

Total 47 $10,083,941.18

3.23.3 Mississippi Recreational Resources

Buccaneer State Park is located in the project area in Hancock County. Due to damage 

from Hurricane Katrina, it has been closed since 2005. The two 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. 

Other recreational opportunities in the state territorial waters of Mississippi that are in the 

project area include saltwater fishing and boating. The Mississippi Charter Boat 

Captain's Association has an organized membership of over 120 and offers recreational 

fishing experiences in the Mississippi sound, the Louisiana marshes and the Gulf of 

Mexico. The charter boats regularly take trips to all of the barrier islands including the 

Chandeleur Islands and to the Louisiana and Biloxi marsh. The Association states that the 

variety of fish population in the Mississippi waters is enhanced by the estuaries of the 

Back Bay and the Louisiana marsh, the "nursery-grounds" of the Gulf of Mexico. 

Recreational fish caught also include Spanish mackerel, kings, bull redfish, bonito, and 

tarpon from mid-spring through fall. Bottom fishing includes trout, black drum, 

spadefish, flounder, ground mullet, sheepshead, and croaker during the short winter 

season. They also venture out to the offshore oil rigs for red snapper, grouper, bluefish, 

smoker kings, amberjack, and dolphin (Mahi-Mahi). A popular trip for recreational 

fishing enthusiasts is wade or skiff-fishing for speckled trout and redfish at Chandeleur 

Island. 

1

Dollar values expended in the years since 1964 are not adjusted for inflation.
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Table 3-35: State and Federal Recreation Areas

Name

Parish 

Location

Managed 

By

Size in 

Acres

Estimated 

Number of 

Visitors During 

2008 Brief Description Trails Boating

Hunting 

or 

Trapping Fishing

Observe 

Birds, 

Wildlife

Educational 

Programs

Play, 

Picnic, 

Swim Camping Other

Bayou 

Sauvage 

NWR

Orleans U.S. Fish and 

Wildlife 

Service

23,000 400,000 Park is entirely within the 

city limits of New Orleans 

and is the nation’s largest 

urban wildlife refuge.

3-mile hiking 

trail; another 

9-mile biking 

trail

1 boat ramp; 

motor 

boating and 

non-motor 

boating

No Fishing from 

boat, bank; 

craw-fishing, 

crabbing

Yes; 

observation 

deck 

Classroom space, 

educational 

programming, 

interpretive panels

Yes; 1 

picnic 

shelter

No

Biloxi WMA St. Bernard Louisiana 

Department of 

Wildlife and 

Fisheries

39,583 Data not available Biloxi WMA is accessible 

only by boat via 

commercial launches at 

Hopedale and Shell Beach. 

The area is owned and 

leased to the Louisiana 

Department of Wildlife 

and Fisheries by the Biloxi 

Marsh Lands Corporation. 

No Motor 

boating

Small 

game, 

waterfowl, 

birds, 

alligator

Boat, bank 

fishing, 

crabbing, 

shrimping, 

shellfishing

Yes No No No

Breton NWR St. Bernard U.S. Fish and 

Wildlife 

Service

Data not 

available

Data not available Breton NWR is the second 

oldest refuge in the 

country and was 100 years 

old on October 4th, 2004. 

President Theodore 

Roosevelt heard about the 

destruction of birds and 

their eggs on Chandeleur 

and Breton Islands in 1904 

and soon afterward created 

Breton NWR.

No Motor 

boating

No Fishing from 

boat, bank; 

crabbing

Yes No No No

Fort Pike 

SHS

St. Tammany Louisiana 

Department of 

Culture, 

Recreation 

and Tourism

94 0 

[This park was 

temporarily 

closed]

Fort Pike, a military 

installation, was completed 

in 1826. The park offers 

educational programs and 

demonstrations.

No 1 boat ramp No No Yes Museum, historic 

site, educational 

programming, 

interpretive panels

Picnic 

tables

No

Pearl River 

WMA

St. Tammany Louisiana 

Department of 

Wildlife and 

Fisheries

35,031 48,066 Pearl River WMA includes 

Honey Island Swamp, one 

of the least altered river 

swamps in the country.

1-mile trail for 

hiking and allterrain 

vehicles

7 boat ramps 

on or near 

WMA; 

motor, nonmotorized 

boating

Deer, small 

game, 

waterfowl, 

birds, 

alligator 

Boat, bank 

fishing, 

crawfishing, 

crabbing, 

shrimping, 

shell fishing

Yes No Area for 

water 

skiing, 

wind 

surfing

Unimproved 

camping

Shooting 

range
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3.24 AESTHETICS

3.24.1 Historic and Existing Conditions

3.24.1.1 East Orleans Landbridge

The East Orleans Landbridge area’s landscape is made up primarily of marshland with a 

slight introduction of trees and forestation (within the limits of the Bayou Sauvage 

National Wildlife Refuge). There is a variety of permanent water features, both natural 

and man-made, that dot the landscape within the project area. The terrain is relatively 

flat and characteristic of the lands present in the region. Primary view sheds to the 

proposed site are offered via Highway 90 and watercraft. The proposed site is made up 

of single-family residential land uses. Attached to many of these residential uses are 

somewhat light-industrial/ commercial uses related to the fishing that takes place here. 

One final land use is public/ natural, pertaining to the Bayou Sauvage National Wildlife 

Refuge. View sheds along Highway 90 are very dramatic showing all forms of the 

landscape features and forms discussed above. 

The site is extremely remarkable, due to the wildlife refuge. There are several sites along 

Highway 90 that offer excellent views into the refuge. 

The nature of this project area presents an outdoor recreator’s dream with fishing and 

nature observation as the most predominant potential forms of outdoor recreation in and 

around the project area. Other forms of potential recreation could include some hiking 

and biking, though it will most likely be limited to the Highway 90 corridor only. 

Figure 3-23: Bayou Sauvage near Highway 90 
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Figure 3-24: Bayou Sauvage near Highway 90 

The Bayou Sauvage area’s landscape is made up primarily of a broad mixture of 

forestation, marshland, wetland and swampland. There is a variety of permanent water 

features that dot the area within Bayou Sauvage National Wildlife Refuge adding to the 

variety of terrain and landscape found there. The terrain is relatively flat and 

characteristic of the lands present in the region. Primary view sheds to the proposed site 

are offered via Highway 90, Highway 11 and Interstate 10 (I-10). The proposed site is 

relatively devoid of any kind of development and is primarily a natural area. View sheds 

along Highway 90 are very dramatic showing all forms of the landscape features and 

forms discussed above. 

Land uses in the area include public, natural areas and what appears to be industrial along 

the eastern border of the project area. The site is extremely remarkable, due to the 

wildlife refuge. There are several sites along Highway 90 that offer excellent views into 

the refuge via boardwalks and piers. Parking and pavilions are available at most of these 

sites.

3.24.1.2 Central Wetlands

The Central Wetlands’ landscape is made up primarily of marshland, wetland and swamp 

mixed with a variety of water bodies and canals. The terrain is predominantly flat and 

open with low growing grasses, some scrub shrub and the occasional medium sized tree. 

The site is very accessible. The route of Interstate 510 (I-510) traverses near the center of 

the proposed project area. This route offers a variety of dramatic views into the 

landscape. The best views come from the I-510 Bridge. There are a variety of land uses 

along the I-510 corridor including residential, commercial, and some industrial. 
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Restoration Plan 3-123 June 2012

Figure 3-25: Central Wetlands from I-510 

Figure 3-26: Central Wetlands from I-510 

3.24.1.3 Pearl River Mouth – LA

The Pearl River Mouth (LA) area’s landscape is made up primarily of marshland with 

dense trees and forestation and a variety of water bodies and channels leading out to the 

channel between Lake Pontchartrain and Lake Borgne. The primary developed areas are

located along the northern and southwestern borders of the study area (within the project

area boundaries). This developed area is relatively compact with land uses focusing on 

single-family residential. The rest of the project area remains natural and scenic, 

especially around the Pearl River WMA, which, more or less, forms the eastern boundary 

of this particular project area. Highway 90 and LA 433 are the major thoroughfares in 

the area and offer fantastic view sheds into the site. Both highways offer views into the 
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Restoration Plan 3-124 June 2012

more natural areas of the site. Other view sheds are offered via watercraft, from the 

waterways and channels connecting Lake Pontchartrain and Lake Borgne.

3.24.1.4 Pearl River Mouth – MS

The Pearl River Mouth (MS) area’s landscape is made up primarily of marshland with 

dense trees and forestation and a variety of water bodies and channels leading out to Lake 

Borgne. The primary developed areas are located along the northern border of the project

area (just outside and adjacent to the project area boundaries). This developed area has 

land uses focusing on single-family residential. The rest of the project area remains 

natural and scenic, especially around the Pearl River WMA, located on the western side 

of the study area. There are no major thoroughfares traversing the study area and no 

public view sheds from the interior. Other view sheds are offered via watercraft, from 

the waterways and channels connecting to Lake Borgne.

3.24.1.5 Biloxi Marshes Exterior

The Biloxi Marshes Exterior area’s landscape is made up primarily of marshland. The 

marshland here is much denser than that found in Biloxi Marshes Exterior. The terrain is 

flat and aquatic. There are no view sheds to the site except from the water located within 

the site itself, or that of Lake Borgne (located to the west). There are no thoroughfares, 

nor is there any development available to offer view sheds into the project area. 

The remote nature of the area presents an outdoor recreator’s dream with fishing and 

nature observation as the most predominant potential forms of outdoor recreation in and 

around the project area. 

3.24.1.6 Biloxi Marshes Interior

The Biloxi Marshes Interior area’s landscape is made up primarily of marshland and 

large, open water features. The terrain is flat and aquatic. There are no view sheds to the 

site except from the water of Mississippi Sound (located to the north) or Chandeleur / 

Breton Sound (located to the east). There are no thoroughfares, nor is there any 

development available to offer view sheds into the project area. 

The remote nature of the area presents an outdoor recreator’s dream with fishing and 

nature observation as the most predominant potential forms of outdoor recreation in and 

around the project area. 

3.24.1.7 Eloi Bay

The Eloi Bay area’s landscape is made up primarily of marshland and large, open water 

features. The terrain is flat and aquatic. There are no view sheds to the site except from 

the water of Eloi Bay itself (located to the southeast). There are no thoroughfares, nor is 

there any development available to offer view sheds into the project area. Access is 

strictly offered only by watercraft.
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Restoration Plan 3-125 June 2012

The site is located in the vicinity of the Biloxi Marshes. The remote nature of the area 

presents an outdoor recreator’s dream with fishing and nature observation as the most 

predominant potential forms of outdoor recreation in and around the project area. 

3.24.1.8 Hopedale

The Hopedale area’s landscape is made up primarily of marshland mixed with some 

forestation and small water bodies. The terrain is predominantly flat and is characteristic 

of similar sites found in the region. The site is located in an area that is very remote. The 

nearest major thoroughfare is LA 624, which offers excellent views into the surrounding 

marshland and water features. 

The site is located in the vicinity of Terre aux Boeufs and the MRGO dredge material 

bank. The remote nature of the area presents an outdoor recreator’s dream with fishing, 

hunting, and nature observation as the most predominant potential forms of outdoor 

recreation in and around the project area. 

3.24.1.9 IHNC/GIWW

The IHNC/GIWW area’s landscape is made up primarily of a dense, industrialized, urban 

environment with some small natural areas along the banks of the waterways. There are 

many crossing thoroughfares traversing the proposed project area. All of these 

thoroughfares offer small and simple views into the project area. Vegetation is minimal 

within the proposed site, offering little in the way of screening and buffering, much less 

natural areas or other areas of interest. As a somewhat redeeming feature, views from the 

water channels themselves may offer better views of natural, relatively undisturbed sites 

along the MRGO. The site is located to the northwest of the Central Wetlands. 

3.24.1.10 Terre aux Boeufs

The Terre aux Boeufs area’s landscape is made up primarily of marshland, wetland and 

swamp mixed with a variety of water bodies and canals leading out to Chandeleur / 

Breton Sound to the southeast. The terrain is predominantly flat and characteristic of 

other aquatic terrains and landscapes in the region. 

The site is located just south of Florissant, Hopedale and the MRGO dredge material 

bank. The site’s location is extremely remote. Access to the site is offered via LA 300 

and LA 624, both of which offer a variety of dramatic views into the marshland and 

natural areas in the vicinity The nearest developed areas (which includes residential, 

commercial, and some industrial) is located along LA 300 and 624. This development is 

just inside and adjacent to the project area boundary. 
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Figure 3-27: Terre aux Boeufs near LA 624

The remote nature of the area presents an outdoor recreator’s dream with fishing and 

nature observation as the most predominant potential forms of outdoor recreation in and 

around the project area. 

Figure 3-28: Terre aux Boeufs near LA 624

3.24.1.11 Lake Borgne

The Lake Borgne area’s features are completely aquatic but surrounded on “roughly” 

three sides by land or land like features. Access to the site is granted through some local 

roads. Primary access takes place from other connecting waterways, such as the 

marshlands and canals landside, and the Mississippi Sound to the northeast. View sheds 

are open and vast, with no obstructions. The Lake itself can be accessed only by 

watercraft. 
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3.24.1.12 South Lake Borgne

The South Lake Borgne area’s landscape is made up primarily of marshland and open 

water features leading out to Lake Borgne. The terrain is flat and aquatic. There are no 

view sheds to the site except from the water of the MRGO or Lake Borgne. There are no

thoroughfares, nor is there any development available to offer view sheds into the project

area. 

The remote nature of the area presents an outdoor recreator’s dream with fishing and 

nature observation as the most predominant potential forms of outdoor recreation in and 

around the project area. 

3.24.1.13 MRGO Dredge Material Bank

The MRGO dredge material bank area’s landscape is made up primarily of marshlands 

mixed with some forestation, water features and the levee system. Though this site is not 

included to directly receive any of the proposed restoration measures, it is central to the 

project area, and therefore important to mention. The terrain varies due to the local levee 

system, but appears to be relatively flat and open with low growing grasses, some scrub 

shrub and the occasional medium sized tree. The site is very remote with access via the 

MRGO and watercraft or from atop the levee system. There is no development located in 

this project area. It remains natural, scenic and relatively untouched.

The MRGO dredge material bank is located along the southern (or western, depending on 

point of view) bank of the MRGO itself, extending the length of the waterway from 

Orleans East to Chandeleur/Breton Sound. The remote nature of the area presents an 

outdoor recreator’s dream with fishing and nature observation as the most predominant 

potential forms of outdoor recreation. 

3.24.1.14 Western Mississippi Sound

The West Mississippi Sound’s features are almost completely aquatic. The northern 

border of the proposed site offers view sheds from the beaches along the gulf coast of 

Mississippi and Cat Island (located in the southeastern corner of the proposed site) offers 

views in a 360 degree panorama. View sheds are open and vast, with no obstructions. 

While Cat Island can be accessed only by watercraft, the gulf coast beaches can be 

accessed from any number of local streets and thoroughfares.

The landscape of Cat Island is made up of sand dunes, low growing foliage plants and 

what appears to be marshland. The terrain is relatively flat with some slight variations in 

elevation along the areas with denser foliage and along the dunes of the beaches. 
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3.24.2 Scenic Streams

3.24.2.1 Historic and Existing Conditions

The Louisiana Scenic Rivers Act of 1988 was established to preserve, protect, and 

enhance the wilderness qualities, scenic beauties, and ecological regimes of rivers and 

streams in the state. There are seven identified scenic streams located within the project 

area (see figure 3-29). These include: Bayou Dupre, Lake Borgne Canal (Violet Canal),

Bashman Bayou, Terre Beau Bayou, Pirogue Bayou, Bayou Bienvenue, and Bayou 

Chaperon. 

The portion of Bayou Bienvenue classified as scenic is located within the Golden 

Triangle Marsh area and includes the portion of the bayou from Bayou Villere to Lake 

Borgne. The remaining six scenic streams are all located within the Central Wetlands 

area. The portion of Bayou Dupre protected as scenic is from the Violet Canal to Terre 

Beau Bayou; the Violet Canal is protected from the Forty Arpent Canal to Bayou Dupre; 

Bashman Bayou is protected from its origin to Bayou Dupre; Terre Beau Bayou is 

protected from Bayou Dupre to the New Canal; and Pirogue Bayou is protected from 

Bayou Dupre to the New Canal. Bayou Chaperon is protected as a scenic stream along 

its entire length. 

The general landscape surrounding the scenic streams within the project area consists 

mainly of coastal marsh habitat. As noted above, six of the scenic streams are located 

within the Central Wetlands area which consists of flat, open marshland vegetated with 

numerous grass species, some scrub/shrub habitat, and the occasional medium-sized tree. 

Bayou Chaperon is located in the mid-portion of the Central Wetlands area. Near the 

start of the bayou at the Forty Arpent Canal, the open marsh land is scattered with small 

to medium-sized cypress trees, giving a glimpse as to what the area looked like in the 

past. As the bayou proceeds northeast the few cypress trees give way to open brackish 

marsh habitat that is fairly contiguous with few open water areas. The bayou terminates 

at a large open water body near the MRGO dredge material bank. 

The remaining five scenic streams are interconnected in the southern portion of the 

Central Wetlands area. The scenic portion of the Violet Canal runs from the 40-Arpent 

Canal to its connection with Bayou Dupre. The viewshed along this stretch of the canal 

consists of open marsh habitat with a narrow bank that runs along both sides of the canal 

and rises a few feet above the surrounding marsh. The banks on both sides of the canal 

consist of scrub/shrub habitat including baccharis, palmetto, and elderberry with scattered 

small to medium-sized trees, mostly live oaks and hackberry, interspersed along the 

banks. 

Bashman Bayou, Bayou Dupre, Terre Beau Bayou, and Pirogue Bayou all interconnect 

between the terminus of the Violet Canal and the MRGO dredge material bank. The 

surrounding viewshed consists of fairly contiguous marshland with a few open ponds and 

smaller tributaries off the main bayous. Just beyond the scenic portion of Bayou Dupree 
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Restoration Study 3-129 June 2012

near its entrance to the MRGO are several fishing camps and a lock structure, all of 

which are visible from portions of Bayou Dupre, Bashman Bayou, and Terre Beau 

Bayou. For all of the scenic streams in this area, views to the east of Lake Borgne and 

associated marsh habitats are blocked by the dense shrub/scrub habitat of the MRGO 

dredge material bank and the hurricane protection levees. 

Bayou Bienvenue is located just north of the Central Wetlands area within the Golden 

Triangle Marsh. This marsh area is bordered by the MRGO to the southwest, the GIWW 

to the north, and Lake Borgne to the east. The scenic portion of the bayou extends from 

the juncture with Bayou Villere to the entrance into Lake Borgne. The habitat 

surrounding the bayou consists of very broken brackish marsh with large areas of open 

water. There is also a fairly large pipeline canal that cuts across the bayou just east of 

Bayou Villere. 

In accordance with LDWF policy concerning the protection of those water bodies 

classified as scenic, any construction within 100 feet of a scenic stream requires a scenic 

streams permit. In those areas where the construction limits are more than 100 feet from 

the scenic stream, the implementation of best management practices (BMPs) would be 

required to prevent sediment runoff during construction. These BMPs would include, but 

are not limited to, the use of stacked hay bales or silt fences, mulching and reseeding, use 

of buffer zones, and the collection and treatment of storm water runoff prior to discharge 

into a scenic stream, where appropriate.

The Mississippi Scenic Stream Stewardship Act was passed in the 1999 Legislative 

Session and was signed into law on March 16, 1999. This legislation created the Scenic 

Streams Stewardship Program, which began August 9, 1999. The goal of the program is 

to encourage voluntary private conservation efforts by riparian (stream-side) landowners. 

In a non-regulatory framework, landowners will be assisted in voluntary management 

agreements which seek to maintain scenic values while ensuring their rights to continue 

customary uses along the stream. There are no scenic streams in the immediate coastal 

areas surrounding the Mississippi Sound or St. Louis Bay that would need to be reviewed 

as part of this study. 
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Restoration Plan 3-130 June 2012

Figure 3-29: Scenic Streams and Central Wetlands Area
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3.25 FLOODPLAINS

3.25.1 Historic and Existing Conditions

Protection of floodplains and floodways is required by EO 11988, Floodplain Management and 

23 CFR Part 650, Location and Hydraulic Design of Encroachments of Floodplains. These 

regulations were designed to minimize permanent encroachments within the 100-year floodplain 

and to avoid land use development inconsistent with floodplain values. During periods of high 

water, floodplains serve to moderate flood flow, provide water quality maintenance, and serve as 

temporary habitat for a number of plant and animal species. The Flood Insurance Rate Maps 

(FIRM) available for the project area were reviewed to determine if any regulated floodplains or 

floodways are located within the project area. 

The majority of the project area is located in undeveloped coastal areas that generally are not part 

of any type of regulated floodplain or floodway. The main portions of the project area that are 

managed and mapped under the FEMA Flood Insurance Rate Mapping System include the 

developed portions of St. Bernard Parish between the Mississippi River and the Forty Arpent

Canal. All of the maps for this area where modified after Hurricane Katrina and the Base Flood 

Advisory Maps include LA-AA36 through LA-AA43, LA-BB34 through LA-BB40, LA-CC33 

through LA-CC39, LA-Z36 through LA-Z44, and LA-41 through LA-45. 

Based on these maps, the majority of the project area, including everything located outside the 

Hurricane Protection System is within Zone VE as classified by FEMA. Zone VE are areas 

within the 100-year floodplain and also susceptible to high velocity mainly from wave action. 

The portions of St. Bernard Parish within the Hurricane Protection System are either Zone C or 

Zone A. Zone C denotes areas of minimal flood hazard and above the 500-year flood level. 

Zone C may have ponding or local drainage problems that don’t warrant a detailed study or 

designation as a base floodplain. These areas are mainly directly adjacent to the Mississippi 

River. The remainder of the Parish is within Zone A. The area classified as Zone A is in the 

100-year floodplain meaning it has a 1 percent chance of flooding annually. 
Chapter 4 Environmental Consequences

FEIS MRGO Ecosystem

Restoration Plan 4-1 June 2012

CHAPTER 4: ENVIRONMENTAL CONSEQUENCES

4.1 INTRODUCTION

In this document, the deauthorized Mississippi River Gulf Outlet navigation channel is 

referred to as the “MRGO.”

The no action alternative must always be included in an Environmental Impact Statement 

(EIS). The no action alternative is an analysis of the future without project (FWOP) 

condition. The no action alternative (alternative A) serves as a benchmark against which 

the impacts of the other alternatives can be compared.

The no action alternative would have direct, indirect, and cumulative impacts 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.

• Land loss: 131,100 acres of emergent wetlands are projected to be converted to 

open water (USGS, 2010). 

• Bank/shoreline erosion: Erosion would continue threatening the 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 

diversion projects in the study area would not fully address the need for additional 

freshwater, sediments, and nutrients to nourish emergent vegetation and 

counteract subsidence and sea level rise.

• Saltwater intrusion: The channel closures at Bayou La Loutre and the Inner 

Harbor Navigation Canal (IHNC) are projected to decrease saltwater intrusion 

into the IHNC and Lake Pontchartrain via the MRGO. 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. 
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Restoration Plan 4-2 June 2012

• 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 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.

For comparison of alternatives, the period of analysis is from 2015 to 2065. The 50-year 

period begins with the first year of operation (2015 – first year when benefits would be 

realized) and extends to 2065. 

Based on all of the preliminary analysis performed for the Violet, Louisiana Freshwater 

Diversion, Alternative Location 1 was considered the best hydraulic location; however, 

the diversion will be further investigated in the feasibility phase of the analysis with 

appropriate NEPA documentation. For the purposes of impact analysis for this FEIS, the 

footprint for the Alternative Location 1 was utilized. In order to run the models, such as 

CASM, to develop the potential impacts and benefits of the overall project, parameters 

for the diversion had to be established and utilized. Therefore, in the chapter 4 impacts 

analysis for each environmental resource, the parameters of Alternative Location 1 for 

the Violet, Louisiana, Freshwater Diversion were used. 

4.2 TENTATIVELY SELECTED PLAN SUMMARY

The tentatively selected plan (TSP) referenced throughout chapter 4 as alternative 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; 10,318 acres of cypress 

swamp; 466 acres of saline marsh; and 54 acres of ridge habitat. The tentatively selected plan 

also identifies 71 miles of shoreline protection including 5.8 miles of oyster reef restoration. 

The tentatively selected plan is the National Ecosystem Restoration Plan.

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. Tier 1 would restore and protect 21,684 acres of 

marsh, 54 acres of ridge, and includes 61 miles of shoreline protection (including 

5.8 miles of oyster reef restoration) 

• Tier 2 includes features with feasibility level detail that are dependent upon 

salinity conditions but may be sustainable without the implementation of a 
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FEIS MRGO Ecosystem

Restoration Plan 4-3 June 2012

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 would restore 1,580 acres of marsh and 1,465 acres of cypress 

swamp.

• Tier 3 includes further study of the Violet Freshwater Diversion, any features that 

are dependent on freshwater diversion, and features in Tier 2 that future 

conditions and further analyses indicate are not sustainable. 

Following the identification of the TSP, 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 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 appendix U, 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 

appendix U. 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. 

4.3 ENVIRONMENTAL CONSEQUENCES SUMMARY 

TABLE

Impacts by alternative and resource are described in table 4-1. 
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FEIS MRGO Ecosystem

Restoration Plan 4-4 June 2012

Table 4-1: Evaluation of Potential Impacts to Significant Resources by Alternative

Environmental 

Resources

Alternatives

Alternative A

No Action Alternative B Alternative C Alternative D

HYDROLOGY AND 

HYDRAULICS (H&H)

No direct impacts. Indirect and cumulative 

impacts include altered flow patterns, altered 

paths of tidal propagation, and loss of tidal 

connection. Slight reduction in salinity due 

to other projects. Continued loss of 

wetlands is expected due to lack of hydraulic 

connectivity and sediment source, as well 

salinity levels. 

Flow velocities would be negligibly 

increased as a result of 1,000 cubic feet 

per second (cfs) background flow and 

would not impede fish passage. 

Increased flow velocity and local eddies 

expected at point of discharge during 

7,000 cfs discharge. Flow velocity 

rapidly decreases when discharged into 

the MRGO. 

No change in diversion flow 

regime so impacts would be 

similar to alternative B.

No change in diversion flow 

regime so impacts would be similar 

to alternative B.

WATER QUALITY

Current water quality conditions would 

persist; dissolved oxygen (DO) levels and 

bacterial concentration would persist; 

continued loss of wetlands reduces ability to 

filter and absorb pollutants. 

Create 7,444 acres and nourish 12,186

acres marsh; create 4,225 acres and 

nourish 6,093 acres swamp; benefit 

water quality in terms of increased DO, 

reduced turbidity, and filtration and 

trapping of pollutants once construction 

completed.

Create 17,352 acres and nourish 

26,836 acres marsh; create 4,225

acres and nourish 6,093 acres 

swamp; benefit water quality in 

terms of increased DO, reduced 

turbidity, and filtration and 

trapping of pollutants once 

construction completed.

Create 18,056 acres and nourish 

26,836 acres marsh; create 4,225

acres and nourish 6,093 acres 

swamp; benefit water quality in 

terms of increased DO, reduced 

turbidity, and filtration and 

trapping of pollutants once 

construction completed.

WATER QUALITY

(salinity)

Potential reduction of 2-3 parts per thousand 

(ppt) in salinity based on the proposed 

construction of several diversion projects in 

the study area.

A maximum salinity change of -1.0 to -

1.4 ppt in Lake Borgne from May to 

December based on proposed diversion 

of 1,000 cfs and peak diversion flow of 

7,000 cfs. Salinity in the Mississippi 

Territorial Waters are predicted to be 

reduced by -0.6 to -0.9 ppt under 

combined influence of Violet, Louisiana

Freshwater Diversion and the 4,500 cfs 

of the combined Maurepas Swamp area 

diversions.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

NAVIGABLE 

WATERWAYS

Current conditions would persist. Other 

projects such as other freshwater 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

may be affected by current from 

diversion flow. Velocities at Bayou 

Bienvenue and Bayou Dupre control 

structures would not affect navigation. 

Impact to navigation in Central 

Wetlands area from increased velocities 

or gate closures.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.
Chapter 4 Environmental Consequences

FEIS MRGO Ecosystem

Restoration Plan 4-5 June 2012

Table 4-1: Evaluation of Potential Impacts to Significant Resources by Alternative

Environmental 

Resources

Alternatives

Alternative A

No Action Alternative B Alternative C Alternative D

SOILS Continued loss of sediments due to shoreline 

erosion and wetland loss.

Diversion channel (Alternative 1

location) would impact approx. 442 

acres of soils designated as prime 

farmland. 

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

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 

alternative B.

Impacts would be similar to 

alternative B.

NOISE No impacts anticipated from FWOP 

condition

No significant impacts anticipated; 

potential temporary impacts to 

communities near the diversion; may be 

temporary and local disturbance of 

some wildlife. 

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

HAZARDOUS, TOXIC, 

AND RADIOACTIVE 

WASTE (HTRW) 

No potential impacts due to any associated 

construction activities. 

An HTRW Phase I was performed for 

the study area, and identified a low 

probability of encountering 

contaminants of concern.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

BARRIER ISLAND 

RESOURCES 

The Chandeleur Islands would continue to 

erode: it is estimated that by 2014, Breton 

Island would be subaerial and the entire 

island chain completely eroded. 

No impacts from this alternative. 

Preliminary modeling efforts for the 

barrier islands indicate additional study 

is warranted. Additionally, modeling 

parameters that involve the impacts of 

the oil spill have to be considered and 

the future is uncertain based on the 

magnitude of the spill and the constantly 

changing efforts to alleviate the 

immediate environmental impacts.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.
Chapter 4 Environmental Consequences

FEIS MRGO Ecosystem

Restoration Plan 4-6 June 2012

Table 4-1: Evaluation of Potential Impacts to Significant Resources by Alternative

Environmental 

Resources

Alternatives

Alternative A

No Action Alternative B Alternative C Alternative D

COASTAL 

VEGETATION

RESOURCES 

Loss of 131,091 acres by 2065. 

Restoration plan includes 54 acres 

ridge; create 4,225 acres, nourish 6,093

acres swamp; create 7,444 acres, 

nourish 12,186 acres marsh; Diversion 

channel (Alternative 1 location) would 

adversely impact 227 acres of existing 

wetlands. While the project area will 

see an increase in wetland acreage, the 

system as a whole could continue to 

encounter some vegetative losses.

Restoration plan includes 54 acres 

ridge; create 4,225 acres, nourish 

6,093 acres swamp; create 17,352

acres, nourish 26,836 acres marsh; 

Diversion channel would 

adversely impact 227 acres of 

existing wetlands. While the 

project area will see an increase in 

wetland acreage, the system as a 

whole could continue to encounter 

some vegetative losses.

Restoration plan includes 54 acres 

ridge; create 4,225 acres, nourish 

6,093 acres swamp; create 18,056

acres, nourish 26,836 acres marsh; 

Diversion would adversely impact 

227 acres of existing wetlands. 

While the project area will see an 

increase in wetland acreage, the 

system as a whole could continue 

to encounter some vegetative 

losses.

WILDLIFE 

RESOURCES 

Continued decline in quality of wildlife 

habitat adversely impacts wetland dependent 

wildlife populations.

Restoration plan would provide 54 acres 

ridge; 19,630 acres of new marsh; 

10,318 acres swamp habitat and protect 

35,367 linear feet of shoreline vital to 

neotropical migratory birds; colonial 

nesting birds, waterfowl and mammals. 

Restoration plan would provide 54

acres ridge; 44,188 acres of new 

marsh; 10,318 acres swamp 

habitat and protect 314,944 linear 

feet of shoreline vital to 

neotropical migratory birds; 

colonial nesting birds, waterfowl 

and mammals. 

Restoration plan would provide 54

acres ridge; 44,892 acres of new 

marsh; 10,318 acres swamp habitat 

and protect 410,567 linear feet of 

shoreline vital to neotropical 

migratory birds; colonial nesting 

birds, waterfowl and mammals. 

AQUATIC AND 

FISHERY RESOURCES

Wetland fragmentation, emergent wetland 

loss, shoreline and bank line erosion result 

in substantial decrease of critical essential 

fish habitat (EFH) needed for important fish 

life cycles, reducing the area’s ability to 

adequately support Federally managed 

species.

Convert 7,444 acres of shallow open 

water and nourish 12,186 acres of marsh 

to create a more continuous emergent 

transitional wetland and 35,367 linear 

feet of shoreline protection. Based on 

preliminary aquatic impact analysis,

results show no significant impacts to 

fishery species including Atlantic 

croaker, red drum (juveniles and adults), 

spotted sea trout (juveniles and adults), 

stripped mullet, sheepshead, Gulf 

menhaden, and bay anchovy. However, 

the potential for localized impacts to 

some species in areas closest to the 

Violet, Louisiana Freshwater Diversion 

could occur, as well as potential 

increases further away.

Creation of approximately 17,356

acres of marsh, 314,944 linear feet 

of shoreline protection, nourish 

26,836 acres of existing marsh 

habitat. Based on preliminary 

aquatic impact analysis, results 

show no significant impacts to 

fishery species including Atlantic 

croaker, red drum (juveniles and 

adults), spotted sea trout 

(juveniles and adults), stripped 

mullet, sheepshead, Gulf 

menhaden, and bay anchovy. 

However, the potential for 

localized impacts to some species 

in areas closest to the Violet, 

Louisiana Freshwater Diversion 

could occur, as well as potential 

increases further away.

Similar to that of alternative C, 

with the following exceptions, 

additional 95,623 linear feet of 

shoreline protection, 704 acres of 

additional marsh created. Based on 

preliminary aquatic impact 

analysis, results show no 

significant impacts to fishery 

species including Atlantic croaker, 

red drum (juveniles and adults), 

spotted sea trout (juveniles and 

adults), stripped mullet, 

sheepshead, Gulf menhaden, and 

bay anchovy. However, the 

potential for localized impacts to 

some species in areas closest to the 

Violet, Louisiana Freshwater

Diversion could occur, as well as 

potential increases further away.
Chapter 4 Environmental Consequences

FEIS MRGO Ecosystem

Restoration Plan 4-7 June 2012

Table 4-1: Evaluation of Potential Impacts to Significant Resources by Alternative

Environmental 

Resources

Alternatives

Alternative A

No Action Alternative B Alternative C Alternative D

COMMERCIAL 

FISHERIES 

Decline expected as habitat loss and 

degradation from erosion due to salinity 

changes lead to overfishing of the resource.

Convert 7,444 acres of shallow open 

water and nourish 12,186 acres of marsh 

to create a more continuous emergent 

transitional wetland and 35,367 linear 

feet of shoreline protection. Based on 

preliminary aquatic impact analysis,

results show slight increase in net 

productivity for juvenile white shrimp 

and brown shrimp within Lake Borgne. 

Restoration of approximately 

17,356 acres of marsh, 314,944

linear feet of shoreline protection, 

nourish 26,836 acres of existing 

marsh habitat. Based on 

preliminary aquatic impact 

analysis, results show slight 

increase in net productivity for 

juvenile white shrimp and brown 

shrimp within Lake Borgne. 

Similar to alternative C, additional 

95,623 linear feet of shoreline

protection, 704 acres of additional

marsh created. Based on 

preliminary aquatic impact 

analysis, results show slight 

increase in net productivity for 

juvenile white shrimp and brown 

shrimp within Lake Borgne. 

OYSTER RESOURCES

Loss of wetlands in the project area would 

likely alter the detritus-based food web of 

the oyster, thereby reducing the localized 

carrying capacity for oyster leases in the 

area.

Would borrow 87 million cubic yards

(mcy) of borrow in Lake Borgne. 

Convert 7,444 acres of shallow open 

water and nourish 12,186 acres of marsh 

to create a more continuous emergent 

transitional wetland and 35,367 linear 

feet of shoreline protection. Based on 

preliminary aquatic impact analysis,

results show slight decreases to oysters 

and spat through Lake Borgne and the 

Inner Biloxi Marsh. 

Restoration of approximately 

17,352 acres of marsh, 314,944

linear feet of shoreline protection, 

nourish 26,836 acres of existing 

marsh habitat using 152 mcy of 

borrow. Based on preliminary 

aquatic impact analysis, results 

show slight decreases to oysters 

and spat through Lake Borgne and 

the Inner Biloxi Marsh.

Similar to that of alternative C, 

additional 95,623 linear feet of 

shoreline and 704 acres or marsh 

created using an additional 2.3 mcy

of borrow. Based on preliminary 

aquatic impact analysis, results 

show slight decreases to oysters 

and spat through Lake Borgne and 

the Inner Biloxi Marsh.

PLANKTON 

RESOURCES 

No Action would have an additive impact 

due to increasing salinity and a transition to 

more marine-dominated community.

Minor changes in salinity (-0.6 to -1.4 

ppt) in Lake Borgne and the Biloxi 

Marsh would not have a substantial 

effect on plankton abundance or 

distribution.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative 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 mcy of material, to 

depths of ten feet with a maximum 

depth of twelve feet, from a total of 

9,036 acres of water bottom. Based on 

preliminary aquatic impact analysis,

results show slight increase in annual 

net productivity for benthic species in 

East Lake Pontchartrain and Lake 

Borgne. 

Excavation of 152 mcy of 

material, to depths of ten feet with 

a maximum depth of twelve feet, 

from a total of 15,724 acres of 

water bottom. Based on 

preliminary aquatic impact 

analysis, results show slight 

increase in annual net productivity 

for benthic species in East Lake 

Pontchartrain and Lake Borgne. 

Excavation of 154.3 mcy of 

material, to depths of ten feet with 

a maximum depth of twelve feet, 

from a total of 15,724 acres of 

water bottom. Based on 

preliminary aquatic impact 

analysis, results show slight 

increase in annual net productivity 

for benthic species in East Lake 

Pontchartrain and Lake Borgne. 
Chapter 4 Environmental Consequences

FEIS MRGO Ecosystem

Restoration Plan 4-8 June 2012

Table 4-1: Evaluation of Potential Impacts to Significant Resources by Alternative

Environmental 

Resources

Alternatives

Alternative A

No Action Alternative B Alternative C Alternative 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. 

Convert 7,444 acres of shallow open 

water and nourish 12,186 acres of marsh 

to create a more contiguous emergent 

transitional wetland. Based on 

preliminary aquatic impact analysis,

results show slight decrease in net 

productivity for juvenile red drum, 

white shrimp, and brown shrimp within 

Lake Borgne. Construction of retention 

dikes and reverse tidal flows could 

reduce utilization of Central Wetlands 

by certain species.

Restoration of approximately 

17,352 acres of marsh, 314,944

linear feet of shoreline protection, 

nourish 26,836 acres of existing 

marsh habitat. Based on 

preliminary aquatic impact 

analysis, results same as 

alternative B. Construction of 

retention dikes and reverse tidal 

flows could reduce utilization of 

Central Wetlands by certain 

species.

Similar to that of alternative C, 

with the following exceptions, 

additional 95,623 linear feet of 

shoreline protection, and 704 acres 

of additional marsh created. Based 

on preliminary aquatic impact 

analysis, results same as alternative 

B. Construction of retention dikes 

and reverse tidal flows could 

reduce utilization of Central 

Wetlands by certain species.

THREATENED AND 

ENDANGERED (T&E) 

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 mcy borrow 

materials, 122 acres impacts from 

shoreline protection from Gulf sturgeon 

critical habitat. 

Approximately 152 mcy borrow 

material, 1,937acre impacts from 

shoreline protection from Gulf 

sturgeon critical habitat.

Approximately 154.3 mcy borrow 

material 2,494 acre impacts from 

shoreline protection from Gulf 

sturgeon critical habitat. 

SOCIO-ECONOMIC 

RESOURCES - 

Population

The no action alternative, would have no 

direct, indirect, or cumulative impacts on 

human populations. 

There are no direct impacts to human 

populations within the project area. 

Hence, this alternative would not be 

expected to have any cumulative effects 

on nearby populations.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

SOCIO-ECONOMIC 

RESOURCES – 

Community Cohesion

The no action alternative would have no 

impact on community cohesion

The construction of the diversion would 

create a new canal temporarily 

impacting traffic and thus affecting flow 

linkage between the two subdivisions 

and connected community residents.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

SOCIO-ECONOMIC 

RESOURCES – 

Employment and Income

The no action alternative would result in 

continued wetland loss and localized 

impacts on employment and income. 

Alternative B would work 

synergistically with other projects and 

programs to support coast wide 

wetland-dependent employment.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

SOCIO-ECONOMIC 

RESOURCES - 

Infrastructure 

The decline wetlands would contribute to 

the deterioration of substrate upon which 

infrastructure features are constructed. 

Alternative B would restore or protect 

30,002 acres in the project area, which 

would assist with protection of existing 

infrastructure. 

Alternative C would provide 

greater beneficial impacts through 

the restoration of 24,558 acres 

more than alternative B.

Impacts would be slightly greater 

than alternative C, because 704 

additional acres would be restored.
Chapter 4 Environmental Consequences

FEIS MRGO Ecosystem

Restoration Plan 4-9 June 2012

Table 4-1: Evaluation of Potential Impacts to Significant Resources by Alternative

Environmental 

Resources

Alternatives

Alternative A

No Action Alternative B Alternative C Alternative D

SOCIO-ECONOMIC 

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 alternative 

B would prevent the increase in 

maintenance and relocation costs for 

pipelines in and around the project area.

Alternative C would provide more 

complete protection for oil and 

gas infrastructure than alternative 

B, and would produce more 

beneficial impacts through the 

restoration of 24,558 additional 

acres.

Impacts would be slightly greater 

than alternative C, because 704 

additional acres would be restored.

SOCIO-ECONOMIC 

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.

Alternative B would provide important 

fisheries habitat. Overall, the industry 

would be more stable near the project 

area due to a long-term increase in the 

quality of fisheries habitat.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

SOCIO-ECONOMIC 

RESOURCES – Oyster 

Leases

The loss of wetlands in the project area 

would likely alter the detritus-based food 

web of the oyster thereby reducing the 

localized carrying capacity for oyster leases 

in the area. 

Creation, protection and nourishment of 

emergent wetlands in the project area in 

conjunction with other actions proposed 

and implemented in the vicinity would 

not affect the productivity of planktonic 

resources upon which oysters feed.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

SOCIO-ECONOMIC 

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. 

Alternative 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 area to be maintained.

Benefits would be greater than 

alternative B, by providing an 

additional 24,558 acres of marsh 

benefits.

Impacts slightly greater than 

alternative C, by providing 704 

acres of additional marsh benefits.

SOCIO-ECONOMIC 

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.

Alternative 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 

alternative B.

Impacts would be similar to 

alternative B.
Chapter 4 Environmental Consequences

FEIS MRGO Ecosystem

Restoration Plan 4-10 June 2012

Table 4-1: Evaluation of Potential Impacts to Significant Resources by Alternative

Environmental 

Resources

Alternatives

Alternative A

No Action Alternative B Alternative C Alternative D

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 areas where the proposed 

diversion would be located (Alternative 

1 location). Concerns raised at public

meetings include: a perceived potential 

for induced flooding, disapproval of the 

location, a perceived lack of benefits to 

St. Bernard Parish, and community 

cohesion.

Potential impacts would be the 

same as alternative B.

Potential impacts would be the 

same as alternative B.

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 either have 

to be avoided or adverse effects would 

have to be mitigated. 

Alternative C includes 24,558

additional acres of restoration 

activities, and therefore greater 

potential impacts.

Alternative D includes 704

additional acres of restoration 

activities, 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 should improve recreational 

fishing and wildlife hunting 

opportunities. Freshwater diversion 

could improve duck hunting. 

Freshening from diversion may push 

some recreational fishing further into 

more saline waters within the project 

area. Based on preliminary aquatic 

impact analysis, results show decrease 

in net productivity for spotted sea trout 

in the Inner Biloxi Marsh but a slight 

increase in net productivity for juvenile 

white shrimp and brown shrimp within 

Lake Borgne

Similar effect as alternative B for 

diversion feature, for wetland 

measures, impacts are to a greater 

extent. 

Effects to resource similar to 

alternative C. 
Chapter 4 Environmental Consequences

FEIS MRGO Ecosystem

Restoration Plan 4-11 June 2012

Table 4-1: Evaluation of Potential Impacts to Significant Resources by Alternative

Environmental 

Resources

Alternatives

Alternative A

No Action Alternative B Alternative C Alternative D

AESTHETICS

(Scenic Rivers)

Continued habitat deterioration, land loss, 

and conversion to open water reducing 

scenic qualities of area.

Temporary impacts from the 

Restoration Plan could include a 

reduction in access, reduced water 

quality, and possible sedimentation. 

However, the overall project would 

create and nourish 4,317 acres of marsh 

and 7,693 acres of swamp in the vicinity 

of the scenic streams restoring their 

viewscape to its original habitat types. 

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.

FLOODPLAINS

A large portion of the project area is coastal 

marsh habitat, which would continue to 

degrade and increase the flood risk to 

developed portions of the floodplain.

Approximately 529 acres within the 500 

and/or 100-year floodplain would be 

converted to floodway as part of the 

construction of the diversion canal

(Alternative / Location. Guide levees 

and control structures would eliminate 

the flood risk to communities or 

development in the adjacent floodplain.

Impacts would be similar to 

alternative B.

Impacts would be similar to 

alternative B.
Chapter 4 Environmental Consequences

FEIS MRGO Ecosystem

Restoration Plan 4-12 June 2012

4.4 HYDROLOGY – HYDRAULICS

4.4.1 Alternative A - No Action Plan

Direct Impacts

In the FWOP condition (no action alternative) there would be no direct adverse impacts 

to hydrology; however, through other programs such as Coastal Wetlands Planning, 

Protection, and Restoration Act (CWPPRA), Coastal Impact Assistance Program (CIAP),

and Louisiana Coastal Area (LCA), there are direct beneficial impacts from other 

freshwater diversion projects proposed or authorized for construction within the study 

area. These diversions would be expected to have some impacts to the hydrology in the 

basin. Based upon storm surge and wave modeling in support of the Louisiana Coastal 

Protection and Restoration (LACPR) evaluation of comprehensive hurricane risk 

reduction, the loss of wetland areas increases storm surge and wave potential (draft 

LACPR report, 2008). However, with the present level of scientific knowledge it is 

difficult to determine the acreage of wetlands lost, and because the levee heights and 

alignments, shoreward depths, and storm characteristics all affect the height of storm 

surge, thus it is difficult to determine the effect of wetland loss in the project area on 

storm surge. 

Indirect Impacts

Programs such as CWPPRA, CIAP, and LCA as well as ongoing hurricane risk reduction 

projects would have indirect impacts on the study area. An example of ongoing or 

recently constructed projects includes the MRGO rock closure structure that was 

completed in August 2009. This structure, along with the sector gates on the GIWW and 

Bayou Bienvenue planned for the authorized improvements to the Greater New Orleans 

Hurricane and Storm Damage Risk Reduction System (HSDRRS), would alter flow 

patterns in and near the western end of the project area. Construction of this storm surge 

barrier structure would include dredging of an access channel on the Lake Borgne side of 

the floodwall (USACE, 2008). The access channel would connect the MRGO with the 

GIWW across the Golden Triangle, but would close off an existing connection. 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. Whereas, prior to the construction of this project (which at the time of this 

writing, although not near completion, has reached a point of effecting the changes of 

tidal flow), 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 Bayou 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. Modeling of the project 
Chapter 4 Environmental Consequences

FEIS MRGO Ecosystem

Restoration Plan 4-13 June 2012

area with the UNO Mass balance model has shown a slight reduction in salinity in the 

project area, but not sufficient to alleviate the need of a freshwater diversion. 

The HSDRRS barrier would prevent salt-water intrusion into the interior marshes to the 

west of the barrier in storm situations, while minimally impeding tidal flows under 

normal circumstances. This barrier would not influence salinity outside of the barrier, 

nor would it influence salinity within the Central Wetlands area as the gates of the Bayou 

Dupre and Bayou Bienvenue control structures are closed during tropical events. 

Modeling scenarios for the barrier structures indicate that the proposed flood protection 

levee could raise the water levels by 0.1 foot (0.03 m) or less, (USACE, 2008). However, 

the authors of this modeling study caveat their results as follows: “this change in average 

water volume represents a difference of less than one inch of water depth distributed 

across the region. This difference in volume may be smaller than the precision 

achievable with present computational resources.” 

Because of the high uncertainty inherent in sea level rise projections, the Mississippi 

Coastal Improvements Program (MsCIP) and the LACPR efforts used scenarios to 

evaluate the effects of different relative sea level rise (RSLR) rates over a 50-year 

planning period. The RSLR values used for the MsCIP scenarios were 0 feet, 2 feet, and 

3.4 feet (MsCIP, 2008). The RSLR values used for the LACPR scenarios were 1.3 feet 

and 2.6 feet (LACPR, 2008). Relative sea level rise has the potential to accelerate the 

land loss problem through several feed-back mechanisms. Open water areas could 

become deeper thus allowing for more wave growth and thus more shoreline erosion 

which could increase wind fetch length again enhancing wave growth. Relative sea level 

rise could also inundate some vegetation and create additional open water areas. The 

greater extent of open water could increase the tidal prism allowing for greater tidal 

exchange with the more saline waters of the Gulf of Mexico. Increased salinity in the 

project area should be anticipated for the no action alternative. Because the magnitude of 

relative sea level rise is uncertain and the resulting increase in the wetland loss rate is 

equally uncertain, it is difficult to quantify the magnitude of the increase of salinity in the 

project area for the no action alternative. 

Cumulative Impacts

Cumulative impacts include the synergistic effect of alternative A 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 chapter 2. Under 

alternative A, no restoration projects would be implemented and, therefore, would not 

contribute incrementally to cumulative impacts on hydrology and hydraulics in the 

project area. Other reasonably foreseeable state and Federal projects, as described in 

chapter 2 would combine to have further impacts on hydrology and hydraulics in the 

project area. 
Chapter 4 Environmental Consequences

FEIS MRGO Ecosystem

Restoration Plan 4-14 June 2012

4.4.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

Proposed wetland creation and nourishment and shoreline protection features associated 

with alternative B would not directly alter existing hydrology and hydraulics. Hydrologic 

connectivity between the wetland creation and nourishment sites and Lake Borgne would 

be temporarily disrupted by the construction of retention dikes. However, retention dikes 

would be designed to naturally degrade following completion of construction thereby 

maintaining hydrologic connectivity with Lake Borgne and other associated waterbodies. 

Fish access gaps incorporated into shoreline protection features would maintain 

hydrologic connectivity between the shoreline and adjacent waterbodies. The potential 

borrow sites in Lake Borgne would be located at least 3,000 feet from shorelines. This 

would prevent potential borrow site-induced changes to the wave climate thereby 

reducing the risk of increased shoreline erosion rates. 

Indirect Impacts 

The flow regime for this plan is for freshwater diversion flow of 1,000 cubic feet per 

second (cfs) ten and a half months of the year with a pulse to 7,000 cfs during the months 

of mid-April through May. The two-tiered diversion scheme is to address two separate 

project goals. The 7,000 cfs flow is to meet salinity goals for the month of May in the 

Biloxi Marsh area. For the other months of the year the existing salinity levels in the 

Biloxi marsh meet the specified criteria for enhanced oyster production. Because of the 

distance from the diversion location, relatively large flows are required to effect a 

relatively small (but significant) salinity reduction in the Biloxi marsh area. The 1,000 

cfs flow is designed to maintain the Central Wetlands area as a fresh system so as to 

enable the establishment of a cypress swamp. 

The introduction of Mississippi River (fresh) water into the project area would change 

flow patterns, water levels, and salinity in the project area. Each of these three items 

(flow patterns, water levels, and salinity) is discussed separately for both the 1,000 cfs 

flow and the 7,000 cfs flow, both inside and outside of the Central Wetlands area.

The preliminary design for the proposed Violet, Louisiana Freshwater Diversion consists 

of culverts under the Mississippi River levee and the highway and railroad adjacent to the 

levee, a channel through the Central Wetlands area and culverts under the hurricane levee 

and T-wall adjacent to the MRGO. By adjusting the opening of the culverts under the 

hurricane levee, water levels in the Central Wetlands area can be managed for optimal 

growth and regeneration of the cypress swamp. By throttling the opening size during the 

7,000 cfs flow the cypress swamp can be totally inundated for the purpose of reducing 

competition from other plants that are not as flood tolerant as cypress. By completely

opening the culverts during the 1,000 cfs flow, it would be possible to lower the water 

level below ground elevation to allow for cypress regeneration. 
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Inside the Central Wetlands area, flows from the diversion would not produce large 

currents. A diversion channel sized to carry the 7,000 cfs flow with velocities of 2 feet 

per second would be dug through the Central Wetlands area. This channel would be 

more than adequate to handle the smaller 1,000 cfs. Flows through the culverts would be 

of a larger magnitude (approximately 6 feet per second [fps] for the 7,000 cfs flow). 

However these flows would discharge into the MRGO, which would act essentially as a 

large reservoir. There would be flow from the discharge point through the estuary and 

out to sea, but the volume of flow would be significantly less than the tidal volume of 

flow. Thus, the flow velocities in and beyond the MRGO reservoir would be very slow. 

The only significant velocities would be at the discharge point where the flow from the 

culverts drains into the MRGO reservoir. This would create local eddies, but the flow 

velocity would rapidly diminish away from the discharge point. If the 1,000 cfs flow is 

directed toward the existing control structures (Bayou Bienvenue control structure and 

Bayou Dupre control structure), assuming an equal distribution, the velocities in the 

throat of the structures would be increased (or decreased on the incoming tide) by about 

one foot per second. These velocities would be significantly less than the existing tidal 

velocities and are less than current velocities that would impede fish passage.

Water levels outside of the Central Wetlands area would not be measurably increased 

away from the immediate area of the discharge point. Water levels inside the Central 

Wetlands area would be managed. The greatest hydrologic impact of the project would 

be on salinity. The Central Wetlands area would become an essentially fresh system. 

Salinity as far away as the Biloxi Marsh and the western Mississippi Sound would 

experience a slight reduction in salinity, especially in the late spring months resulting 

from the 7,000 cfs pulse during April and May. Areas between the Biloxi Marsh and the 

Central Wetlands area would be progressively freshened westward. This means that the 

western portion of Lake Borgne may have salinity reductions to the extent that oyster 

production may be impacted. 

Cumulative Impacts

Cumulative impacts to hydrology and hydraulics would primarily be associated with 

incremental impacts of reasonably foreseeable future wetland restoration and shoreline 

protection features in and near the project area as well as throughout coastal Louisiana. 

As described above in the direct and indirect sections, alternative B would not add 

incrementally to the direct impacts to hydrology and hydraulics, but would contribute to 

indirect cumulative impacts. 

4.4.3 Alternative C - MRGO Restoration Plan 7

Direct Impacts

Direct impacts to hydrology and hydraulics associated with alternative C would be the 

same as the impacts from alternative B, as delineated in section 4.3.2, since the flow 

regime and the timing are the same.
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Indirect Impacts

Indirect impacts to hydrology and hydraulics associated with alternative C would be the 

same as the impacts from alternative B, as delineated in section 4.3.2, since the flow 

regime and the timing are the same.

Cumulative Impacts

Cumulative impacts to hydrology and hydraulics associated with alternative C would be 

the same as the impacts from alternative B, as delineated in section 4.3.2, since the flow 

regime and the timing are the same.

4.4.4 Alternative D - MRGO Restoration Plan 10

Direct Impacts

Direct impacts to hydrology and hydraulics associated with alternative D would be the 

same as the impacts from alternative B, as delineated in section 4.3.2, since the flow 

regime and the timing are the same.

Indirect Impacts

Indirect impacts to hydrology and hydraulics associated with alternative D would be the 

same as the impacts from alternative B, as delineated in section 4.3.2, since the flow 

regime and the timing are the same.

Cumulative Impacts

Cumulative impacts to hydrology and hydraulics associated with alternative D would be 

the same as the impacts from alternative B, as delineated in section 4.3.2, since the flow 

regime and the timing is the same.

4.5 WATER QUALITY

4.5.1 Alternative A - No Action Plan

Direct Impacts

The no action alternative would have 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 project area. These diversions could have both 

adverse and beneficial impacts to water quality depending on the quality of the source 

water, as well as physical location conditions of the receiving waters. Current water 

quality conditions, as described in chapter 3, would likely persist and coastal wetlands 

could continue to be affected by natural and man-made factors that have both beneficial 
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Restoration Plan 4-17 June 2012

and adverse effects on water quality. Emergent wetland plants would likely continue to 

diminish as land loss and subsidence convert marshes to open water. The continual loss 

of emergent wetland 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. 

DO levels at Bayou Dupre, located in the Central Wetlands portion of the project area, as 

well as other areas along the MRGO have measured consistently above the minimum 

criteria levels for both the state and Environmental Protection Agency (EPA). With rare 

exceptions, the pH measurements have been within the desirable range of 6.5 to 9.0. 

Toxic substances, including heavy metals and synthetic organics, have been measured 

above EPA criteria levels, but no patterns consistently exceeding the criteria for 

particular substances have been observed in the project area. Existing programs, such as 

the National Pollutant Discharge Elimination System (NPDES), Louisiana Department of 

Environmental Quality’s (LDEQ’s), and Mississippi Department of Environmental 

Quality’s (MDEQ’s) Nonpoint Source Pollution Program, Louisiana Department of 

Natural Resources (LDNR’s) Coastal Nonpoint Pollution Program, and Total Maximum 

Daily Loads (TMDLs), would continue. The Lake Pontchartrain Basin Foundation 

(LPBF) activities, such as water quality monitoring, habitat protection, environmental 

education, and public events, would be expected to continue. 

The de-authorization of the MRGO from the Gulf of Mexico to Mile 60 at the southern 

bank of the GIWW and construction of a closure structure at Bayou La Loutre have been 

completed. A flood control sector gate and bypass barge gate on the GIWW, a navigable 

flood control lift gate at Bayou Bienvenue, a braced concrete wall across the MRGO 

located southeast of the existing Bayou Bienvenue flood control structure, and a concrete 

floodwall across the marsh (Golden Triangle area) between these waterways have already 

begun. Since the closure of the MRGO at Bayou La Loutre, there have been noticeable 

decreases in salinity levels recorded in the MRGO, Lake Borgne, Central Wetlands area, 

and even into Lake Pontchartrain. These salinity decreases would be anticipated to 

remain or decrease further under the no action alternative. While the decrease in salinity 

has changed water quality, it could also result in the long-term effect of changing some of 

the marsh habitat types in the Central Wetlands area and Lake Borgne. Along with the 

decrease in salinity, an increase in hypoxic and anoxic conditions in the MRGO below 

the closure structure has also been noted since the construction of the closure at Bayou La 

Loutre. Indications are that these hypoxic and anoxic conditions are the result of 

decreased water movement and turnover since the closure was constructed. Under the no 

action alternative, these conditions could continue, resulting in deteriorating water quality 

conditions for the MRGO, Lake Borgne, and associated marsh and open water habitat. 

Wetland losses could potentially be offset to some extent by projects stated in the 

previous paragraph as well as other Federal, state, local, and private restoration efforts. 

Under Section 7006 of the Water Resources Development Act of 2007 (WRDA 2007), 

the LCA program has authority for feasibility-level reports of six near-term critical 

restoration features. Future projects that are planned independently of the tentatively 
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Restoration Plan 4-18 June 2012

selected plan in this FEIS and would affect baseline water quality conditions within the 

study area include:

l. Medium Diversion at White Ditch – The draft recommended plan would 

divert up to 35,000 cfs of freshwater from the Mississippi River left 

descending bank at river mile (RM) 60.0 into the Breton Sound Basin, as 

well as create 31 acres of ridge and terrace habitat and restore 385 acres of 

marsh. The diversion influence area is approximately 98,000 acres. 

m. Convent/Blind River Diversion – 3,000 cfs 

n. Hope Canal / Maurepas Swamp Freshwater Diversion – 1,000 cfs 

Other restoration projects occurring in the study area that have and would have an effect

on future baseline water quality conditions include: 

• CWPPRA PO-29 River Reintroduction into Maurepas Swamp. 

• CWPPRA PO-30 Lake Borgne Shoreline Protection project has been completed.

• CWPPRA PO-32 Lake Borgne and MRGO Shoreline Protection project. This 

project was authorized in April 2003. Phase I design was complete in 2005 and 

phase II design was complete in 2007. Construction of the Lake Borgne portion 

has been completed and the MRGO portion has been proposed for 

deauthorization. Anticipated net acres benefited are 266 acres.

• CWPPRA PO-34 Alligator Bend Marsh Restoration and Shoreline Protection. 

This project is currently in planning and design. Construction is anticipated to 

start in October 2011 and end in September 2012. Anticipated net acres benefited 

would be 127 acres. 

• CWPPRA PO-36 (EB) Orleans Landbridge Shoreline Protection and Marsh 

Creation. The goal of the project is to protect approximately 1,400 acres. 

• Lake Borgne and MRGO Shoreline Protection and accretion behind shoreline 

protection structures – Area 1 Doulluts Canal to Jahncke’s Ditch. Construction 

would commence in 2010 and protect approximately 3.8 acres per year and 

restore approximately 17 acres by 2030. 

• Lake Borgne and MRGO Shoreline Protection – Area 3 Doulluts Canal to Lena’s 

Lagoon. Construction would commence in 2010 and is anticipated to stop land 

loss and restore approximately 8.2 acres per year. 

• USACE 3rd and 4th

• CIAP, The Rigolets Shoreline Protection and Marsh Creation – Grand Coin 

Pocket, tier 2. Anticipated net acres benefited would be 100 acres. 

 Supplemental Funds - Lake Borgne Shoreline Protection and 

Marsh Restoration Project. This restoration project would create and nourish 

marsh in the Golden Triangle and Shell Beach area and protect shoreline in the 

Shell Beach area. Anticipated net acres benefited would be approximately 29 

acres per year. 

• CIAP, Lake Pontchartrain Shoreline Protection and Marsh Creation – Irish Bayou 

to Chef Menteur Pass, tier 2. Anticipated net acres benefited would be 46 acres. 

• CIAP, Fritchie Marsh Stormwater Diversion.

• State Shoreline Protection Project along the interior Biloxi Marsh funded with 

Federal surplus funds. 
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• WRDA 2007 – The Violet, Louisiana Freshwater Diversion Project – Project to 

construct a freshwater diversion to meet or maximize the ability to meet the 

benefits identified in the Bonnet Carré Feasibility Study and Report prepared in 

1984. The Violet WRDA 2007 project is pending the findings of this study. 

• CIAP-Violet Diversion. 

• Orleans Parish Sewerage and Water Board plan to redirect wastewater effluent 

from the Mississippi River into the Central Wetlands to provide nutrients and 

freshwater to restore cypress swamp as well as fill and plant cypress trees. 

Information taken from the Preliminary Hydrodynamic and Hydraulic Modeling for a 

Proposed Freshwater Diversion in the Vicinity of Violet, Louisiana (USACE, 2010) 

states that future conditions under the no action alternative are based on the following: 

existing diversions at Violet Siphon, Bonnet Carré, and Caernarvon, and planned 

diversions at Maurepas Swamp (Convent/Blind River, Hope Canal or Maurepas Swamp 

River Reintroduction), Caernarvon, and the Orleans Parish Sewerage and Water Board 

Waste Water Treatment Program. Planned diversions from the lower Mississippi River 

located below the Caernarvon Diversion were not included in the model. The diversion 

value for the Violet Siphon is 100 cfs, which is assumed to be the yearly average. The 

flow at Bonnet Carré is the same as the flow used for the calibration/historic run - 

240,000 cfs. The combined diversions into the Maurepas swamp area (Convent/Blind 

River Diversion – 3,000 cfs, Hope Canal / Maurepas Swamp River Reintroduction - 

1,000 cfs) have a potential capacity of 4,500 cfs under the no action alternative. Input 

flows for the Caernarvon diversion were increased by roughly 25 percent in line with the 

projected increase in the capacity of the structure. 

The Chatry goal for salinity levels, established based on the 1984 Feasibility Study, 

“Freshwater Diversion to Lake Pontchartrain Basin and Mississippi Sound” and agreed to 

by the Habitat Evaluation Team (HET) and Salinity Working Group as the target for 

salinity levels with the implementation of the MRGO Restoration project, states that the 

target salinity levels within the Biloxi Marsh for optimum oyster production range from 

12 ppt to 17 ppt for the months of June through March and 7 ppt to 8 ppt for April and 

May. The model results indicate that the planned Caernarvon diversion does modify the 

salinity regime in the Biloxi Marsh. For the month of April, salinity decreases compared 

to the baseline condition and the amount of time that salinity is under the Chatry target 

increases from 41 percent to 86.9 percent in the future for existing conditions (no action 

alternative). This reduction in salinity from the diversions infers that additional 

diversions may not be necessary during April. Salinity in the month of May were also 

lowered, and the target salinity is predicted to be met 27.4 percent of the time under the 

no action alternative. These are significant improvements, and indicate that additional 

management changes may help meet the targeted salinity goals to improve water quality 

in the project area. This modeling scenario also verifies that additional freshwater 

diversions will be necessary in lowering salinity levels in the Biloxi Marsh to meet the 40 

percent Chatry goal. 
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Indirect Impacts

The programs discussed above would continue to develop or remain in place under the 

existing conditions in order to ensure protection of Louisiana’s and Mississippi’s public 

health and natural resources. Other reasonably foreseeable efforts that would likely 

improve water quality conditions include Federal, state, local, and private ecosystem 

restoration projects. The continued degradation of water quality under the no action 

alternative would result in a decline in overall water quality within the project area; 

however, other activities that have adverse effects on water quality would continue to 

occur into the future, such as continued urban storm-water runoff and the discharge of 

untreated or poorly-treated sewerage.

Cumulative Impacts

Cumulative impacts to water quality would be the synergistic effect of combined wetland 

loss and continued salinity increases throughout the project area and larger study area in 

combination with the reasonably foreseeable future restoration and diversion projects that 

would be implemented under other state and Federal efforts. Under the alternative A, 

there would be no restoration projects implemented. As the wetland habitats continue to 

deteriorate and convert to open water, salinity would continue to increase, turbidity from 

wave action would increase, and the ability for pollution and storm water runoff from 

urban areas to be filtered before entering local waterbodies would be reduced. 

All of these actions would contribute to decreased water quality in coastal and inland 

waters. These negative impacts could be offset, to some extent, under the no action 

alternative by the five reasonably foreseeable future diversions that were discussed above 

as well as numerous other wetland restoration and shoreline protection projects listed in 

the direct impacts section. Along with features authorized under HSDRRS and the 

MRGO closure structure, the water quality in the project area could see some 

improvements. 

The closure structure near Bayou La Loutre has reduced tidal exchange between Lake 

Borgne and Breton Sound, which has reduced salinity in the project area. It is projected 

that this closure could reduce salinity by up to 6.6 ppt. Additionally the closure structure 

and sector gates on the GIWW and lift gates on Bayou Bienvenue under construction 

near the confluence of the GIWW and the MRGO channel for the authorized 

improvements to the HSDRRS would alter flow patterns in the project area. Along with 

these potential improvements, the proposed diversions mentioned above that would be 

constructed under other authorizations could further reduce salinity in the area by 2-3 ppt. 

While these other restoration and diversion projects could offset some of the adverse 

impacts to water quality in the project area, the continued loss of habitat throughout 

coastal Louisiana in combination with continued loss in the project area would ultimately 

continue to reduce water quality. The continued adverse impacts to water quality could 

lead to a reduction in the quality of the waterbodies for fish and wildlife propagation, 
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Restoration Plan 4-21 June 2012

particularly commercially viable species, and a reduction in human usage of the area 

waters for both primary and secondary contact recreational uses.

 

4.5.2 Alternative B - MRGO Restoration Plan 2

The project has the potential to improve the water quality within the project area by 

returning salinity to historical conditions, as outlined by Section 3083 of the WRDA 

2007. Section 3083 states that a freshwater diversion and other habitat restoration efforts 

must be designed to meet, or maximize the ability to meet, salinity levels identified by 

(Chatry et al., 1984), while creating and nourishing marsh habitat, which traps pollutants 

and sediments. 

Direct Impacts

The majority of the direct impacts would be associated with dredging, placement of 

borrow material, and placement of rock during project construction. These activities 

would result in elevated levels of turbidity, re-suspension of pollutants or other trapped 

sediments, hypoxic conditions at borrow locations, and rapid changes to salinity levels 

and temperature at the placement sites. The rapid changes in salinity levels could result 

from mixing of the water column, while temperature could be affected by turbidity as 

well as mixing of the water column. Colder and more saline water would be deeper in 

the water column and could be brought to the surface during construction efforts. The 

majority of the borrow material would be placed in existing open water habitats, so that 

once the material has dispersed and settled to project goal elevations, water quality would 

begin to return to ambient conditions several hours after dredging operations ceased. 

Therefore, the adverse impacts during project construction would be temporary and 

localized. 

In order to reduce impacts to critical habitat within Lake Borgne, areas of hard bottom, 

including sand and shell, would be avoided for potential borrow locations. The result is 

that the majority of borrow locations would be in areas with bottom sediments composed 

of silt and clay soils. These types of soils are finer in size and require a longer time 

period to settle out of the water column after disturbance. Therefore, the duration and 

potential impact of turbidity from suspended sediments during construction of the 

restoration measures to water quality could be longer than if sediments with a greater 

sand component were utilized. 

The restoration measures implemented with alternative B would require approximately 

87 mcy of borrow material. Direct impacts for alternative B borrow would include up to 

9,036 acres of disturbance to the bottom sediments associated with the borrow pits. 

Dredging in the borrow sites would result in short-term adverse effects on marine water 

quality, including localized increases in turbidity and slight decreases in DO at the 

location of the drag head and in the surrounding sediment plume. Suspended sediment 

concentrations would be elevated during and for a period (several hours) after dredging 

Borrow Sites 
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operations. No other water quality parameters would be anticipated to be substantially 

affected during dredging operations. 

The overall DO levels in Lake Borgne could experience a slight decrease throughout the 

ten years of dredging activity and could potentially continue long-term post-construction. 

The current depths of borrow pits could lead to anoxic or hypoxic conditions. To avoid 

the potential for this impact, monitoring water quality during the ten years of dredging 

could show that modifications to borrow pits through adaptive management may alleviate 

potential impacts from decreased DO levels.

The creation of access channels to move dredged material to the placement sites and the 

creation and backfilling of floatation channels, which would be used to access the 

proposed shoreline protection areas, would include approximately 122 acres of 

disturbances to the bottom sediments and result in direct adverse impacts on water quality 

during construction. Excavation and backfilling within these channels would cause 

temporary localized increases in turbidity, slight temperature increases, and DO decrease. 

Dredge sediments would begin to settle out from the water column immediately 

following construction activities with larger particles, such as sand, settling out within 

minutes and finer particles, including silts and clays, taking several hours to several days 

to completely clear from the water column. 

Access and Floatation Channels 

 

Alternative B would result in the placement of fill material and other construction 

activities (i.e., creation of dikes and a breakwater) at the sites listed below. 

Placement and Construction Sites

Marsh Restoration: 

• Conversion of 7,444 acres of open water and fragmented marsh to freshwater, 

brackish, and saline marsh habitat. 

• Nourishment of 12,186 acres of existing marsh habitat. 

• 4,468 acres of perimeter retention dikes and earthen weirs for conversion of open 

and fragmented marsh to freshwater, brackish, and saline marsh. 

Cypress Swamp Restoration: 

• Conversion of 4,225 acres of open water to cypress swamp. 

• Nourishment of an additional 6,093 acres of swamp. 

• 1,143 acres of perimeter retention dikes needed for the cypress swamp creation. 

Ridge Restoration: 

• 54 acres of ridge being increased in elevation.

Shoreline Protection Measures: 

• 35,367 linear feet of rock breakwater would be constructed to protect marsh 

habitat and reduce shoreline erosion. 
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Creation of marsh habitats, retention dikes, elevation of ridges, and shoreline protection 

measures would all cause temporary localized increases in turbidity, re-suspension of 

pollutants or other trapped sediments, and rapid changes to temperature. The duration of 

construction-related impacts due to dredging in Lake Borgne would persist over a period 

of ten years. Increased vegetation growth and productivity from marsh habitat would 

benefit water quality in terms of increased DO, reduced turbidity, and filtration and 

trapping of pollutants once all project construction was completed. The shoreline 

protection measures would substantially reduce the potential for erosion of the restored 

marsh areas, and therefore would reduce the potential for elevated levels of turbidity from 

eroded sediments becoming suspended in the water column. 

Section 3083 of the WRDA 2007 authorized a diversion of freshwater from the 

Mississippi River at or near Violet, Louisiana in order to reduce salinity levels in the 

region of Western Mississippi Sound and the Biloxi Marsh in St. Bernard Parish, 

Louisiana. Section 3083 states that the freshwater diversion must be designed to meet, or 

maximize the ability to meet, salinity levels identified by (Chatry et al., 1984), needed for 

overall ecosystem maintenance. Modeling also indicated that the combination of the 

closure of the MRGO, the closure of the existing connection between the MRGO and 

Lake Borgne, and the Violet, Louisiana Freshwater Diversion of around 7,000 cfs during 

the months of April and May would be capable of reducing salinity within the Biloxi 

Marsh by 2 ppt to 3 ppt. In months other than April and May, a diversion rate of 

approximately 1,000 cfs is proposed. 

Violet, Louisiana Freshwater Diversion Channel

The monthly quantity and quality of Mississippi River water to be diverted was used to 

calculate a constituent load for nitrate plus nitrite, total nitrogen, total phosphorus, and 

total suspended solids, which could all have significant adverse effects on the overall 

water quality within the Violet, Louisiana Freshwater Diversion channel and receiving 

water bodies (primarily Lake Borgne). Constituent loads were then modified by the 

reduction and dispersion of water via the Central Wetlands area for flows of 1,000 cfs, 

followed by the reduction and dispersion of water in the associated Lake Borgne 

wetlands. For flows of 7,000 cfs, travel times through the Central Wetlands area would 

be shortened compared to lower flows and slower moving water, such that little treatment 

within the Central Wetlands area would be expected. 

Lake Borgne is a fairly shallow water body with a tidal range - approximately twice that 

of nearby Lake Pontchartrain - so it has relatively short residence times for river waters 

which are mixed with ocean waters. In addition, circulation within Lake Borgne is not 

restricted by physical barriers, and storm fronts generating considerable wave energy 

commonly occur. The configuration of and circulation conditions in Lake Borgne helps 

to minimize the potential for algal blooms (which result in decreased DO) from poor 

water quality delivered to the lake from the Violet, Louisiana Freshwater Diversion, 

particularly during higher diversion flows when larger amounts of pollutants would be in 

the water. However, as is noted in section 4.18.2, the initial introduction of river water 

into estuarine systems may have a short-term impact on plankton populations in the 

adjacent coastal waters including Lake Borgne. In areas of Lake Borgne where the 
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Restoration Plan 4-24 June 2012

borrow areas are located, the eventual influx of freshwater from the Violet Diversion 

could result in salinity stratification. An increase in algal, or plankton populations, as 

well as salinity stratification could potentially decrease the DO levels in Lake Borgne.

Construction of the Violet, Louisiana Freshwater Diversion channel would have direct 

impacts on 529 acres including 227 acres of brackish marsh and open waters within the 

Central Wetlands area. The Violet, Louisiana Freshwater Diversion would result in longterm changes in water quality and salinity levels in the Central Wetlands area, Biloxi 

Marsh, and West Mississippi Sound. The Central Wetlands area would be converted 

from a brackish system into a freshwater habitat from the introduction of large amounts 

of freshwater from the Mississippi River. Sufficient flows of freshwater would meet the 

Chatry et al (1984) salinity targets for oyster development in Biloxi Marsh. In Western

Mississippi Sound, changes in salinity would be in the range of an approximately one ppt 

decline; changes in total nitrogen, total suspended solids, and chlorophyll-a would be 

expected to be minor to non-detectable. 

Within the Central Wetlands area, diversion quantities would be likely to create 

conditions where salinity would be similar to the Mississippi River itself. During the 

months with inflows of 1,000 cfs (June to March), the quantity diverted would be 

approximately 2,000 acre-feet per day, a volume capable of covering the Central 

Wetlands area to a water depth of up to 2 inches each day. The quantity of water 

available, even during the low-flow months, is sufficient to introduce a volume of water 

capable of reducing salinity stress for remnant Cypress trees and other salinity-sensitive 

species. 

Within the MRGO, diversions of Mississippi River water through the Central Wetlands 

area would likely result in noticeable increases in turbidity, especially during the 7,000 

cfs flows during the months of April and May. It is likely that differences in salt content 

are sufficiently large that diverted water from the Mississippi River may form a localized 

layer of freshwater on top of the saltier waters of the MRGO, especially during high 

freshwater inflow months of April and May. Consequently, it is possible that salinitybased stratification of the water column could occur within the MRGO. Stratification of 

the water column could in turn create conditions where biological oxygen demand (BOD)

of materials within the bottom waters could bring about subsequent declines in the levels 

of DO in the bottom waters of the MRGO. 

Although levels of total suspended solids and total nitrogen would likely increase 

substantially in Lake Borgne with diversions (especially in April and May), changes in 

levels of chlorophyll-a would be much more modest due to the already-turbid nature of 

Lake Borgne (which reduces light availability needed for algal growth) and the shallow 

and well-flushed nature of the system. 

Information taken from the Preliminary Hydrodynamic and Hydraulic Modeling for a 

Proposed Freshwater Diversion in the Vicinity of Violet, Louisiana (USACE, 2010) 

indicates a maximum salinity change of -1.0 ppt to -1.4 ppt in Lake Borgne from May to 

December based on the proposed diversion base flow of 1,000 cfs and a peak diversion 
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flow of 7,000 cfs. Salinity in the Mississippi Territorial Waters is predicted to be reduced

by -0.6 to -0.9 ppt under the combined influence of the 1,000 cfs Violet, Louisiana

Freshwater Diversion with 7,000 cfs pulse and the 4,000 cfs of the combined Maurepas 

Swamp Area diversions. 

Despite the overall conclusion that water quality impacts would not be of sufficient 

concern to override the value of diversion projects such as that anticipated for Violet 

(Caffrey et al., 2002), a number of water quality related impacts can be identified. These 

include the following: 1) a decrease in salinity in Lake Borgne sufficient to adversely 

affect oyster production; 2) the lowering of water temperatures in the Central Wetlands 

area and MRGO due to the cooler temperatures of diverted Mississippi River water; and

3) elevated levels of metals, bacteria, and various organochlorine compounds in areas 

nearest the diversion. The impact, if any, of these potential stressors would increase with 

proximity to the diversion itself, and the size and intensity of the potential impact would 

likely be maximal during times of maximum discharge rates (i.e., April and May). 

The dredging contractor would be responsible for proper storage and disposal of any 

hazardous material such as oils and fuels used during the dredging, transport, and pumpout operations. The EPA and United States Coast Guard (USCG) regulations require the 

treatment of waste (e.g., sewage, graywater) from dredge plants and tender/service 

vessels and prohibit the disposal of debris into the marine environment. The dredge 

contractor would be required to implement a marine pollution control plan to minimize 

any direct impacts to water quality. No accidental spills of diesel fuel from the dredge 

plant or tender vessels would be expected. Personnel would implement USCG-approved 

safety response plans to prevent and minimize any impacts associated with a spill.

Hazardous Waste Procedures 

Indirect Impacts

Indirect impacts from alternative B would include the potential for temporary nutrient 

enrichment associated with suspended sediments during dredging and fill placement 

operations, as well as the freshwater diversion that could possibly lead to localized 

increased algae blooms. Localized short-term increases in turbidity could possibly lead 

to temporary displacement of estuarine organisms. Borrow activities could slightly 

increase the temperature of the ambient water by increasing the solar absorption through 

increased suspended sediments. However, any such construction related impacts would 

be expected to be minor and conditions would return to ambient following construction, 

while impacts from the freshwater diversion would be long term in nature. 

 

Borrow pit dimensions may influence the potential formation of DO deficits. The 

tendency for a borrow pit to accumulate organic material can be reduced by: 1) limiting 

the depth of the pit; 2) increasing the pits surface area; and 3) decreasing side-slopes that 

transition from the pit to adjacent water bottoms. A shallow and broad “pan-shaped” 

borrow pit would facilitate circulation with adjacent waters, thereby decreasing the 

likelihood that organic material would become entrained, as well as allow for periodic 

flushing of the pit during storm events. In contrast, narrow and deep pits would be less 

influenced by circulation in the overlying water column and would require greater energy 
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Restoration Plan 4-26 June 2012

for flushing of organic material. Shallower pits would require less energy to mix the 

water column and would facilitate the mixing with adjacent waters (FEIS for MRGO and 

Lake Borgne Wetland Creation and Shoreline Protection, USACE 2009). 

Borrow pits in Lake Borgne that would be utilized as a sediment source for marsh 

creation projects would have dimensions restrictive of DO deficit formation. Borrow pits 

would be pan-shaped with large surface area (acreages would differ by borrow site 

locations) and relatively shallow depths (not to exceed 12 feet below existing depth) and 

would gradually transition from adjacent water bottoms to project depth (side slopes of 

2:1). The borrow pits would be located some distance from sources of rock inputs for 

shoreline protection measures (3,000 feet minimum distance from shoreline or tidal 

passes), and sedimentation rates within the project area are relatively low without the 

presence of predominant organic layers. Moreover, circulation within Lake Borgne is not 

restricted by physical barriers, and storm fronts generating considerable wave energy 

commonly occur. Proposed borrow pit dimensions combined with observed 

characteristics of the project area would therefore not be expected to favor the formation 

of DO deficits. 

Cumulative Impacts

Water quality throughout coastal Louisiana and the project area is a constantly changing 

resource that is influenced by many different factors. Salinity fluctuates based on 

freshwater inputs including rainfall, runoff, and man-made diversions. These inputs, 

along with tidal movement and storm related wave action, in turn have an effect on 

turbidity and nutrient levels. Finally the quality, type, and amount of wetland habitats in 

the area influence all of the water quality aspects in terms of filtration, wave absorption, 

and tidal movements. 

The wetland losses that continue to affect the region and project area would be offset by 

both the restoration efforts proposed under alternative B, as well as other reasonably 

foreseeable future projects in the region. Project benefits, listed above under direct 

impacts, would be partially supplemented by the overall net acres created, nourished, and 

protected by other Federal, state, local, and private restoration efforts in section 2.6.1. 

Along with 4,000 cfs of potential freshwater inputs though the upper Pontchartrain subbasin and up to 35,000 cfs at White Ditch, the Violet freshwater diversion would 

introduce 1,000 cfs with a 7,000 cfs pulse and an influence area of 115,078 acres. 

Alternative B would work together with those projects to provide more complete 

protection of marsh habitat that would result in long-term beneficial impacts on water 

quality in the region. These restoration efforts include 19,630 acres of marsh and 10,318 

acres of swamp creation and nourishment as well as 35,367 linear feet of shoreline 

protection. 

Cumulative impacts from alternative B in combination with the reasonably foreseeable 

future projects would primarily provide long-term improvement of water quality within 

the project area because of the restoration of emergent wetlands serve as natural filters for 

improving water quality (Day et al., 1998). By restoring and protecting these critical 

marsh habitats, including the Biloxi Marsh and East Orleans Landbridge, alternative B 
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Restoration Plan 4-27 June 2012

would help prevent the degradation of water quality in Lake Borgne and Lake 

Pontchartrain that would likely occur as the marsh is eroded. 

While the overall cumulative impacts from this restoration project should have a net 

positive benefit in terms of habitat creation and protection, there are several external 

factors that could offset a portion of these benefits. The project area in southeast 

Louisiana is located along the Gulf Coast and is susceptible to tropical cyclone activity 

every year from June through November. There is a moderate risk every year for a 

tropical storm or hurricane to impact the area causing land loss and inundation with saline 

waters that would have an immediate and long-term impact to the restoration features and 

project area as a whole. A second key factor in the potential cumulative effects to the 

region is from the oil and gas industry. Oil and gas exploration, production, and 

transportation are major economic drivers in the project area and coastal Louisiana. A 

comprehensive list of future projects would be very difficult to develop due to the private 

and rapidly changing nature of the industry. However, it is prudent to assume the 

potential for future impacts from dredging, due to the development of oil and gas 

infrastructure including pipelines, platforms, or exploration activities, to the restoration 

features or other wetland habitat in the project area. In addition, there are potential 

impacts to water quality from oil spills that may occur within the project area.

4.5.3 Alternative C - MRGO Restoration Plan 7

Alternative C shares many of the same restoration features as discussed for alternative B 

including a freshwater diversion and ridge restoration; however, this alternative includes 

additional restoration measures not identified under alternative B. The type of restoration 

measures between alternative C and alternative B are the same with differences being in 

the acreage of marsh creation and the linear feet of shoreline protection put in place. In 

addition to the measures proposed for alternative B, this alternative includes 9,908 acres 

of additional marsh creation in the Biloxi Marsh, Central Wetlands area, and East Orleans 

Landbridge areas and 279,577 linear feet of additional shoreline protection in the Biloxi 

Marsh, Central Wetlands area, MRGO Channel, and East Orleans Landbridge areas. 

Direct Impacts

In addition to the impacts stated previously, construction of the restoration measures for 

alternative C would require approximately 152 mcy of borrow material. This would 

include 15,724 acres of water bottom being disturbed for the creation of borrow pits. 

This borrow material would come from various sources in Lake Borgne and surrounding 

water bodies. Borrow pit creation, as well as an additional 1,937 acres of disturbance for 

access channels and excavation of floatation channels to move the material and the 

placement of shoreline protection would cause temporary local increases in turbidity, 

slight temperature increases, and DO decrease. Dredged sediments would begin to settle 

out from the water column immediately following construction activities with larger 

particles, such as sand, settling out within minutes and finer particles, including silts and 

clays, taking several hours to several days to completely clear from the water column.

Borrow Sites 
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Restoration Plan 4-28 June 2012

The overall DO levels in Lake Borgne could experience a slight decrease throughout the 

ten years of dredging activity and could potentially continue long-term post-construction. 

The current depths of borrow pits could lead to anoxic or hypoxic conditions. To avoid 

the potential for this impact, monitoring water quality during the ten years of dredging 

could show that modifications to borrow pits through adaptive management may alleviate 

potential impacts from decreased DO levels.

Alternative C would result in the placement of fill material and other construction 

activities (i.e., creation of dikes and a breakwater) at the additional sites listed below. 

Placement and Construction Sites

Marsh Restoration: 

• Alternative C would convert 17,352 acres of open water and fragmented marsh to 

freshwater, brackish, and saline marsh habitat. 

• Nourish 26,836 acres of existing marsh habitat. 

• Approximately 8,905 acres of perimeter retention dikes and earthen weirs. 

Cypress Swamp Restoration: 

• Conversion of 4,225 acres of open water to cypress swamp. 

• Nourish an additional 6,093 acres of swamp. 

• 1,143 acres of perimeter retention dikes needed for the cypress swamp restoration. 

Ridge Restoration: 

• Consist of 17,500 feet, approximately 54 acres, of ridge being increased in 

elevation. 

Shoreline Protection Measures: 

• 314,944 linear feet of shoreline protection measures consisting of rock breakwater 

would be constructed to protect marsh habitat and reduce shoreline erosion. 

Direct impacts associated with alternative C would be very similar to those discussed 

under alternative B including temporary increases in turbidity, re-suspension of pollutants 

or other trapped sediments, hypoxic conditions at borrow locations, and rapid changes to 

temperature. The duration of construction-related impacts due to dredging in Lake 

Borgne would persist over a period of ten years. However, the results of the restoration 

measure would include increased vegetation growth and productivity of marsh habitat, 

which would in turn benefit water quality in terms of increased DO, reduced turbidity, 

and filtration and trapping of pollutants once all project construction was completed. 

Information taken from the Preliminary Hydrodynamic and Hydraulic Modeling for a 

Proposed Freshwater Diversion in the Vicinity of Violet, Louisiana (USACE, 2010) 

indicates a maximum salinity change of -1.0 ppt to -1.4 ppt in Lake Borgne from May to 

December based on the proposed diversion base flow of 1,000 cfs and a peak diversion 

flow of 7,000 cfs. Salinity in the Mississippi Territorial Waters are predicted to be 

Violet, LouisianaFreshwater Diversion Channel 
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reduced by -0.6 ppt to -0.9 ppt under the combined influence of the 1,000 cfs Violet, 

Louisiana Freshwater Diversion with 7,000 cfs pulse and the 4,500 cfs of the combined 

Maurepas Swamp Area diversions.

Three recreational sites have been identified for construction as part of this restoration 

project. The first feature would be located at the Bienvenue Triangle marsh area at the 

terminus of Caffin Avenue in Orleans Parish. The second would be developed on either 

side of the proposed Violet, Louisiana Freshwater Diversion between St. Bernard 

Highway and Judge Perez Drive in St. Bernard Parish. The third feature would be 

developed in Shell Beach at the terminus of Ycloskey Highway at the MRGO in St. 

Bernard Parish. All of the recreation features are further discussed in section 2.5.3.2 and 

appendix W. 

Recreation Features

The Bienvenue Triangle and Shell Beach recreation features consist of boardwalks over 

the water as well as parking and picnic areas on land. Impacts to water quality would 

consist of the potential for increased surface water runoff during rain events from the 

improved surfaces. Less than one acre of impervious surfaces would be constructed with 

these two features. The Violet Diversion Park would have similar impacts with 

approximately 3.5 acres of impervious surface, trails and parking, being constructed and 

potentially increasing water runoff during rain events. Overall the potential impacts to 

water quality from these recreation features would be minimal.

Indirect Impacts

Indirect impacts associated with alternative C would be similar to those described under 

alternative B. 

Cumulative Impacts

Cumulative impacts associated with alternative C would be similar to those described 

under alternative B. 

4.5.4 Alternative D - MRGO Restoration Plan 10

Alternative D shares many of the same restoration features as discussed for alternative B 

and alternative C, including a freshwater diversion and ridge restoration; however, this 

alternative includes additional restoration measures not identified under either alternative 

B or alternative C. The type of restoration measures proposed for alternative D and 

alternatives B and C are the same with differences being in the acreage of marsh creation 

and the linear feet of shoreline protection put in place, as well as repair work to existing 

foreshore protection and submerged aquatic vegetation (SAV) protection measures. In 

addition to the measures proposed for alternative B and alternative C, this alternative 

includes 704 acres of additional marsh creation in the Biloxi Marsh, Central Wetlands 

area, Hopedale, and East Orleans Landbridge areas and 95,623 linear feet of additional 
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Restoration Plan 4-30 June 2012

shoreline protection in the Biloxi Marsh, Central Wetlands area, Lake Borgne, the 

MRGO, and East Orleans Landbridge areas.

Direct Impacts

Borrow Sites 

In addition to the impacts stated above, construction of the restoration measures for 

alternative D would require approximately 154.3 mcy of borrow material. This would 

include 15,724 acres of water bottom being disturbed for the creation of borrow pits. 

This borrow material would come from various sources in Lake Borgne and surrounding 

water bodies. Borrow pit creation, as well as an additional 2,494 acres of disturbance for 

access channels and excavation of floatation channels to move the material and the 

placement of shoreline protection would cause temporary local increases in turbidity, 

slight temperature increases, and DO decrease. Dredge sediments would begin to settle 

out from the water column immediately following construction activities with larger 

particles, such as sand, settling out within minutes and finer particles, including silts and 

clays, taking several hours to several days to completely clear from the water column. 

The overall DO levels in Lake Borgne could experience a slight decrease throughout the 

ten years of dredging activity and could potentially continue long-term post-construction. 

The current depths of borrow pits could lead to anoxic or hypoxic conditions. To avoid 

the potential for this impact, monitoring water quality during the ten years of dredging 

could show that modifications to borrow pits through adaptive management may alleviate 

potential impacts from decreased DO levels.

Alternative D would result in the placement of fill material and other construction 

activities (i.e., creation of dikes and a breakwater) at the additional sites listed below. 

Placement and Construction Sites

Marsh Restoration: 

• Conversion of 18,056 acres of open water and fragmented marsh to freshwater, 

brackish, and saline marsh habitat. 

• Nourish 26,836 acres of existing marsh habitat. 

• Approximately 8,914 acres of perimeter retention dikes and earthen weirs. 

Cypress Swamp Restoration: 

• Conversion of 4,225 acres of open water to cypress swamp. 

• Nourish an additional 6,093 acres of swamp. 

• 1,143 acres of perimeter retention dikes needed for the cypress swamp restoration. 

Ridge Restoration: 

• Consist of 17,500 feet, approximately 54 acres, of ridge being increased in 

elevation. 

Shoreline Protection Measures: 
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Restoration Plan 4-31 June 2012

• 410,567 linear feet of shoreline protection measures consisting of rock breakwater 

would be constructed to protect marsh habitat and reduce shoreline erosion. 

In addition to the similar measures described under alternative B and alternative C, 

alterative D would have 15,000 linear feet of submerged aquatic vegetation (SAV) 

protection structures that would be constructed in Lake Pontchartrain just off the existing 

eastern shoreline. The structures would be 5,000 feet in length with each structure 

consisting of five 750-foot low level rock weirs at 100 foot spacing. 

Direct impacts associated with alternative D would be very similar to those discussed 

under alternative B including temporary increases in turbidity, re-suspension of pollutants 

or other trapped sediments, hypoxic conditions at borrow locations, and rapid changes to 

temperature. The duration of construction-related impacts due to dredging in Lake 

Borgne would persist over a period of ten years. However, the results of the restoration 

measure would include increased vegetation growth and productivity of marsh habitat, 

which would in turn benefit water quality in terms of increased DO, reduced turbidity, 

and filtration and trapping of pollutants once all project construction was completed. 

Information taken from the Preliminary Hydrodynamic and Hydraulic Modeling for a 

Proposed Freshwater Diversion in the Vicinity of Violet, Louisiana (USACE, 2010) 

indicates a maximum salinity change of -1.0 ppt to -1.4 ppt in Lake Borgne from May to 

December based on the proposed diversion base flow of 1,000 cfs and a peak diversion 

flow of 7,000 cfs. Salinity in the Mississippi Territorial Waters are predicted to be 

reduced by -0.6 ppt to -0.9 ppt under the combined influence of the 1,000 cfs Violet, 

Louisiana Freshwater Diversion with 7,000 cfs pulse and the 4,500 cfs of the combined 

Maurepas Swamp Area diversions. 

Violet, Louisiana Freshwater Diversion Channel

Indirect Impacts

Indirect impacts associated with alternative D would be similar to those described under 

alternative B and alternative C. 

Cumulative Impacts

Cumulative impacts associated with alternative D would be similar to those described 

under alternative B and alternative C. 

4.6 NAVIGABLE WATERWAYS

4.6.1 Alternative A - No Action Plan

Direct Impacts

There would be no direct navigation impacts associated with alternative A, the no action 

plan. 
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Indirect Impacts

Indirect impacts would result from the MRGO closure and IHNC Barrier. There are two 

major Federal navigation projects in the project area, the Mississippi River and the 

GIWW and several small Federal navigation projects (Bayou Dupre, Bayou La Loutre, 

Bayou St. Malo, and Bayou Yscloskey). These projects were completed a half century 

ago and have not required any maintenance dredging. 

The Mississippi River and the GIWW would not be impacted by the no action plan. In 

addition to these two authorized projects, the MRGO was de-authorized after Hurricane 

Katrina and officially closed July 2009 with the construction of a rock closure structure 

near the Bayou La Loutre Ridge. The IHNC surge barrier structure is presently being 

constructed on the MRGO just south of the Bayou Bienvenue gate. Both Bayou 

Bienvenue and Bayou Dupre have control structures that allow for passage of small 

recreational and commercial fishing vessels. 

Navigation through these control structures would not be impacted by the no action 

alternative. Under alternative A, the rock closure structure on the MRGO and the 

Hurricane Risk Reduction Barrier currently under construction to prevent storm surge 

from entering the IHNC would have an indirect impact on navigation. The MRGO 

closure structure has altered small craft navigation. Access to Breton Sound is no longer 

possible via the direct route of the MRGO. Access is now via Bayou La Loutre and other 

waterways. Construction of the storm surge barrier has eliminated a direct route between 

the Bayou Bienvenue gate and the Bayou Dupre gate via the MRGO. Boat traffic now 

will have to go through the Bayou Bienvenue gate east of the MRGO. 

Cumulative Impacts

As there are no projects proposed that would directly or indirectly impact navigable 

waterways within the project area, alternative A would not contribute to the overall 

cumulative impacts on navigable waterways. 

4.6.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

It is anticipated that the Mississippi River Deep Draft Navigation Channel would not be 

impacted from implementation of the proposed diversion. When the diversion is 

operated at peak flow, currents would be expected on or near the batture, but not in the 

deep draft navigation channel. The river is approximately 2,250 feet in width at the 

location of the proposed diversion. The authorized width of the navigation channel is 

750 feet. Thus 1,500 feet of the river is outside of the authorized navigation channel. 

Assuming that the channel is twice as far from the inside of the bend as from the outside 

of the bend, the navigation channel is, at a minimum, 500 feet from the diversion intake 

location. Further assuming radial flow into the diversion structure and an average flow 

depth of 20 feet for out of channel locations, the average current contribution 500 feet 
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Restoration Plan 4-33 June 2012

from the structure would not exceed 0.2 fps. This current magnitude is insignificant in a 

river that has mean currents up to 7 fps or 8 fps. At peak flows, the proposed diversion is 

slightly less than the peak flows for the Davis Pond and Caernarvon diversions. Neither 

of these two projects has reported any impacts on the navigation channel. 

Navigation in the GIWW may be affected by a slight current from the diversion flow. 

Assuming roughly half of the 1,000 cfs diversion flow goes out the Bayou Bienvenue 

structure this flow would also go out through the GIWW navigation gates. Some of the 

Bayou Bienvenue flow may also go through Seabrook into Lake Pontchartrain. If all of 

the 500 cfs flow assumed to go out Bayou Bienvenue goes through the GIWW navigation 

gates the velocity increase would be on the order of 0.1 fps (500 cfs / two – 16-foot deep 

by 150-foot wide gates). This 0.1 fps velocity is significantly less than the normal tidal 

flows through the gates. 

Similar to the velocities through the GIWW navigation gates, velocities in the throat of 

the Bayou Bienvenue and Bayou Dupre control structures would also be much less than 

the tidal velocities. Assuming that 500 cfs goes through each of the structures, the 

induced velocity would be less than one fps (500 cfs / 56-foot wide by 10-foot deep). 

Potential management schemes may be developed to periodically flood the Central 

Wetlands to reduce or eliminate competition to the cypress and tupelo trees. These 

efforts would mimic naturally swamp inundation to promote tree growth and health. The 

management scenario and methodology for implementing the proposed periodic flooding 

have not yet been finalized. There could be the potential for these management scenarios 

to impact navigation through the Bayou Dupre and Bayou Bienvenue control structures, 

either through increased velocities or by gate closures.

Indirect Impacts

Indirect impacts would result from the MRGO closure and IHNC Barrier in combination 

with the changes to current and flow velocities associated with the Violet, Louisiana

Freshwater Diversion. 

Cumulative Impacts

As described above, alternative B would contribute minor direct and indirect impacts to 

the overall cumulative impacts on navigable waterways from wetland loss and 

degradation throughout coastal Louisiana, as well as the benefits and impacts of other 

Federal, state, and local projects in the vicinity, as detailed in chapter 2. 

4.6.3 Alternative C - MRGO Restoration Plan 7

Direct Impacts

Direct impacts to navigable waterways associated with alternative C would be the same 

as the impacts from alternative B.
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Indirect Impacts

Indirect impacts to navigable waterways associated with alternative C would be the same 

as the impacts from alternative B.

Cumulative Impacts

Cumulative impacts to navigable waterways associated with alternative C would be the 

same as the impacts from alternative B.

4.6.4 Alternative D - MRGO Restoration Plan 10

Direct Impacts

Direct impacts to navigable waterways associated with alternative D would be the same 

as the impacts from alternative B.

Indirect Impacts

Indirect impacts to navigable waterways associated with alternative D would be the same 

as the impacts from alternative B.

Cumulative Impacts

Cumulative impacts to navigable waterways associated with alternative D would be the 

same as the impacts from alternative B.

4.7 SOILS

4.7.1 Alternative A - No Action Plan

Direct Impacts

There would be no direct impacts to soils associated with alternative A, the no action 

plan. 

Indirect Impacts

The ongoing conversion of wetlands to shallow open water under existing conditions 

would continue under the no action alternative. 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 project area would continue to decline and existing wetland vegetation would 

continue to diminish. 
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Restoration Plan 4-35 June 2012

Cumulative Impacts

Cumulative impacts of the projected loss of soil resources from the project 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. 

4.7.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

The Violet, Louisiana Freshwater Diversion channel has been identified as the only 

restoration measure in the study area that has a quantifiable direct impact to soils in the 

project area. Construction of the Violet, Louisiana Freshwater Diversion channel would 

impact a total of approximately 718 acres. This includes the northern portion of the 

canal, which would be constructed within a natural area, reach, and the southern portion, 

which would be constructed within an agricultural area. 

Construction of the southern portion of the Violet, Louisiana Freshwater Diversion 

channel, a new bridge, and rail crossings over the diversion canal would result in the 

permanent loss of approximately 641 acres of farmland from an area that extends from 

the east bank the Mississippi River to Forty Arpent Canal and between Maureen Lane to 

the south and St. Marie Drive on the north (figure 4-1). Approximately 442 acres of this 

area are designated as prime and/or unique farmlands; in compliance with the Farmland 

Protection Policy Act (FPPA), the U.S. Army Corps of Engineers (USACE) would 

consult with the Department of Agriculture – Natural Resources Conservation Service 

(NRCS) to determine the precise acreage that would be affected by construction of the 

Violet, Louisiana Freshwater Diversion by submitting Form AD-1006, the Farmland 

Conversion Impact Rating (FCIR). 

Construction of the northern segment of the Violet, Louisiana Freshwater Diversion 

channel from the Forty Arpent Canal to Lake Borgne would impact approximately 77 

acres, 28 of which are water and 49 of which are a mucky, poorly drained soil. The 

northern segment of the Violet, Louisiana Freshwater Diversion channel would not have 

any impact on farmland including prime or unique farmlands (figure 4-1).

Restoration measures under alternative B would potentially create 7,444 acres of 

wetlands and/or marshland and would have beneficial long-term effect on soils in the 

project area. Initially, wetland and/or marsh creation would be accomplished by the 

placement of fill/borrow material from Lake Borgne to raise the elevation of land to that 

of adjacent marshland for the re-establishment of vegetation. The retention diking, weirs, 

and shoreline protection measures used to provide maintenance to newly restored areas 
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Restoration Plan 4-36 June 2012

would have a direct beneficial long-term impact on nearby soils by reducing their

exposure to erosion. 

Figure 4-1: Distribution of Soil Types and Farmland (Prime and Non-Prime) in the 

Vicinity of the Proposed Violet, Louisiana Freshwater Diversion Channel

Indirect Impacts

Potential indirect impacts in the project area from the restoration measures implemented 

for alternative B (including freshwater diverted by the Violet, Louisiana Freshwater 

Diversion channel, diking, weirs, and shoreline protection, all aimed at restoring the 

historical sediment regime and hydrology) would result in long-term beneficial impacts 

on soils in the project area by nourishing existing wetlands and/or marshes with sediment 

that would in turn increase their productivity, build wetlands, and reintroduce and 

distribute sediment and nutrients throughout the ecosystem. No indirect impact on prime 

or unique farmland would be expected as the result of the restoration activities under 

alternative B.

SOURCE of Soil Layer: Natural Resources Conservation Service, Soil survey area: St. Bernard Parish, Louisiana
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Restoration Plan 4-37 June 2012

Cumulative Impacts

Cumulative long-term impacts on soils in the project area would occur from the 

restoration measures proposed for alternative B combined with direct and indirect 

impacts from other reasonably foreseeable future regional projects such as freshwater 

diversion, fill/borrow, diking, weir, and shoreline protection. The proposed construction 

of the diversion channel itself would result in direct loss of 284 acres of prime/unique 

farmland and 227 acres of wetland. Overall, the beneficial cumulative impacts would be 

the creation and increase the productivity of wetland/marsh, the restoration of salinity 

gradients, and the reintroduction and distribution of sediment and nutrients throughout 

the ecosystem. 

 

4.7.3 Alternative C - MRGO Restoration Plan 7 

Direct Impacts

Potential direct impacts for alternative C would be the same as the impacts discussed for 

alternative B.

Indirect Impacts

Potential indirect impacts for alternative C would be the same as the impacts discussed 

for alternative B.

Cumulative Impacts

Potential cumulative impacts for alternative C would be the same as the impacts 

discussed for alternative B, except alternative C will provide a significantly larger 

(279,577 linear feet) length of shoreline protection, the same amount of cypress swamp 

habitat in the Central Wetlands, and also restore a significantly larger (24,558 acres) area 

of wetlands in the lower Pontchartrain sub-basin. Alternative C will have the same 

potential for the beneficial cumulative impacts would be the creation and increase the 

productivity of wetland/marsh, the restoration of salinity gradients, and the reintroduction 

and distribution of sediment and nutrients throughout the ecosystem. 

4.7.4 Alternative D - MRGO Restoration Plan 10 

Direct Impacts

Potential direct impacts for alternative D would be the same as the impacts discussed for 

alternative B.

Indirect Impacts

Potential indirect impacts for alternative D would be the same as the impacts discussed 

for alternative B.
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Restoration Plan 4-38 June 2012

Cumulative Impacts

Potential cumulative impacts for alternative D would be similar to the impacts discussed 

for alternative B, except alternative D would provide a slightly larger (95,623 linear feet) 

length of shoreline protection, the same amount of cypress swamp habitat in the Central 

Wetlands, and restore a significantly larger (25,262 acres) area of wetlands in the lower 

Pontchartrain sub-basin. Alternative D will have the same potential for beneficial 

cumulative impacts would be the creation and increase the productivity of wetland/marsh, 

the restoration of salinity gradients, and the reintroduction and distribution of sediment 

and nutrients throughout the ecosystem. 

4.8 SEDIMENTS

4.8.1 Alternative A - No Action Plan

Direct Impacts

There would be no direct impacts to sediments associated with alternative A, the no 

action plan. 

Indirect Impacts

Programs discussed in chapter 2 would continue to develop or remain in place under the 

existing conditions in order to ensure protection of Louisiana’s and Mississippi’s coastal 

and natural resources. Other reasonably foreseeable efforts that would likely improve 

and restore critical habitat include Federal, state, local, and private ecosystem restoration 

projects. These projects include diversions and restoration which could have an effect on 

sediment availability. 

Cumulative Impacts

Without the proposed restoration projects and borrow needs, alternative A would not 

contribute to sediment needs and cumulative impacts to sediment within the project area. 

Potential impacts to sediments would occur as a result of the reasonable foreseeable 

future Federal, state, and local projects in the vicinity that would require sediment, as 

detailed in chapter 2. 

4.8.2 Alternative B - MRGO Restoration Plan 2 

Direct Impacts

Effects of implementing alternative B would be related primarily to localized and 

temporary disturbance of water bottoms during placement of shoreline protection features 

and also during dredging and placement of borrow materials. Disturbance to benthic 

species would likely occur from increased turbidity, temperature, and BOD and 
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Restoration Plan 4-39 June 2012

decreased DO due to hydraulic dredging, marsh creation, and placement of shoreline 

protection activities. Some smothering of benthic organisms could also occur from the 

sedimentation of the dredge plume, but these potential impacts could be minimized 

through the use of silt curtains or other construction measures to minimize dredging 

impacts. Once construction is completed it is anticipated that water quality would return 

to pre-construction conditions. 

These actions would directly impact benthic organisms within the proposed borrow areas, 

flotation access channels, wetland creation, and shoreline protection footprints by directly 

removing them along with the sediment as well as burying benthos within the placement 

sites. Other direct impacts to the benthos would be localized and confined to 

construction areas. 

Along with impacts to water quality and benthic organisms, the dredging process and 

associated turbidity would redistribute finer particles throughout the Lake Borgne system 

as well as expose chemicals, metals, and other pollutants that could be trapped in the 

sediments. Also, the impacts of the Deepwater Horizon oil spill on coastal Louisiana are 

uncertain at this time (August 2010). This spill could potentially adversely impact 

USACE abilities to utilize the sediments in Lake Borgne as potential borrow sources for 

wetland restoration. 

Indirect Impacts

Programs discussed in chapter 2 would continue to develop or remain in place under the 

existing conditions in order to ensure protection of Louisiana’s and Mississippi’s coastal 

and natural resources. Other reasonably foreseeable efforts that would likely improve 

and restore critical habitat include Federal, state, local, and private ecosystem restoration 

projects. These projects include diversions and restoration which could have an effect on 

sediment availability. 

Cumulative Impacts

Cumulative impacts would be the synergistic effect of projects requiring borrow 

throughout coastal Louisiana, and the potential borrow impacts and benefits of other 

Federal, state, and local projects in the vicinity, as detailed in chapter 2. 

4.8.3 Alternative C - MRGO Restoration Plan 7

Direct Impacts

Direct impacts to sediments associated with alternative C would be the same as the 

impacts from alternative B.
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Indirect Impacts

Indirect impacts to sediments associated with alternative C would be the same as the 

impacts from alternative B.

Cumulative Impacts

Cumulative impacts to sediments associated with alternative C would be the same as the 

impacts from alternative B.

4.8.4 Alternative D - MRGO Restoration Plan 10

Direct Impacts

Direct impacts to sediments associated with alternative D would be the same as the 

impacts from alternative B.

Indirect Impacts

Indirect impacts to sediments associated with alternative D would be the same as the 

impacts from alternative B.

Cumulative Impacts

Cumulative impacts to sediments associated with alternative D would be the same as the 

impacts from alternative B.

4.9 AIR QUALITY

4.9.1 Alternative A - No Action Plan

Direct Impacts

Under the no action alternative, the current air quality trends would be expected to 

continue. The no action alternative would have no direct beneficial or adverse impacts 

on air quality. 

Indirect Impacts

A large portion of the project area is a remote and uninhabited marsh. Under the no 

action alternative, air quality would continue to be subject to institutional recognition and 

further regulations. However, air quality in the study area could potentially decline 

should the following occur: continued population growth, further commercialization and 

industrialization, increased numbers of motor vehicles, and increased emissions from 

various engines. These impacts would be coupled with the continued loss of Louisiana 
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coastal wetland vegetation that would no longer be available to remove gaseous 

pollutants. 

Cumulative Impacts

Under the no action alternative, there would likely be no changes to onsite air quality or 

construction development projects in the MRGO study area expected to significantly 

change levels of any pollutant of concern. Therefore, there would be no significant 

cumulative air quality impacts as a result of the no action alternative.

4.9.2 Alternative B - MRGO Restoration Plan 2 

Direct Impacts

Under alternative B, direct impacts to ambient air quality would result from construction 

activities within the project area. The air emissions would be mobile in nature, 

temporary, and localized by construction “feature.” There are more than 30 construction 

features of alternative B that would use a total of approximately 87 mcy of borrow to 

create and nourish 19,630 acres of marsh and 10,318 acres of swamp; construct 35,367 

linear feet of shoreline protection; and construct 3,890 acres of retention dikes, 1,721 

acres of earthen weirs, and 54 acres of ridge restoration. Each feature would consist of 

one or more of these construction activities. Construction would take place in three 

Louisiana parishes, including St. Bernard, Orleans, and St. Tammany, with the majority 

of construction in St. Bernard Parish. Construction activity would span a 10-year period.

Emissions of criteria pollutants would be generated during construction activities from 

the following sources: 

• Combustion of diesel fuel from construction and support equipment; 

• Disturbance and movement of soils; and 

• Combustion of diesel fuel or gasoline from cars and trucks used by workers to get 

to and from the construction areas. 

Operation of construction equipment and support vehicles would generate Volatile 

Organic Compounds (VOCs), Particulates of 10 microns or less in diameter (PM10), 

Particulates of 2.5 microns or less in diameter (PM2.5), Nitrous Oxides (NOx), Carbon 

Monoxide (CO), Ozone (O3), and Sulfur Dioxide (SO2) emissions from diesel or 

gasoline engine combustion. 

Calculations were performed to estimate the total combustible air emissions on an annual 

basis from a “worst case” scenario associated with alternative B. It was assumed that 

several construction activities would take place simultaneously, such as shoreline 

protection (potentially two work crews in different features), swamp and marsh 

nourishment (one crew), construction of retention dikes, earthen weirs, ridges (one crew), 

and the Violet, Louisiana Freshwater Diversion construction (one crew). The quantity of 
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equipment needed for each activity can be limited by the availability of such equipment, 

or the availability of construction materials such as rock needed for shoreline restoration. 

Air emissions were calculated for the operation of tug boats, dredgers, draglines and 

other construction and support equipment, such as cranes, bulldozers, and crew boats 

using emission factors from the EPA-approved emission model NONROAD6.2. If there 

was no emission factor for a particular type of equipment, an emission factor was chosen 

that represented emissions from a diesel engine of similar horsepower.

Fugitive dust calculations were made for disturbing soils during marsh and swamp 

creation and nourishment, and construction of retention dikes, ridges, and shoreline 

protection. These emissions were calculated using emission factors from Mid-Atlantic 

Regional Air Management Association using the emission factor of 0.11 ton per acre per 

month. This is a more current standard than EPA’s 1985 Compilation of Air Pollutant 

Emission Factors, also known as AP-42 (EPA, 2001). The construction work would take 

place mainly in remote, uninhabited areas with no roadways nearby; therefore, fugitive 

dust is not anticipated to obstruct visibility on roadways. 

Vehicle traffic due to construction workers commuting and supply delivery trucks driving 

to and from the construction areas would temporarily increase air emissions in the project 

area. The emissions from supply trucks and workers commuting to work were included 

in the air emission analysis. 

Assumptions were made regarding the type and quantity of equipment needed and hours 

of operation for each construction activity. The assumptions, emission factors, and 

resulting calculations are presented in appendix P. A summary of the worst case

emissions are presented in table 4-2. 

 

Table 4-2: Total (Worst Case) Air Emissions (tons/year) 

from Alternative B Construction Activities Pollutant 

Total (tons/year)

Pollutant

Total Emissions 

(Tons/Year)

Carbon Monoxide (CO) 145

Volatile Organic Compounds (VOCs) 32

Nitrous Oxides (NOx) 403

Particulate matter < 10 microns (PM10) 90

Particulate matter < 2.5 microns (PM2.5) 37

Sulfur Dioxide (SO2) 54

During construction, proper and routine maintenance of all vehicles and other 

construction equipment would be implemented to ensure that emissions are within the 

design standards of all construction equipment. 

The air emissions generated from alternative B would be mobile in nature and would be 

emitted from geographically separate construction sites (features) located within three 
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separate Louisiana parishes (St. Bernard, Orleans, and St. Tammany). The features

would be constructed over a 10-year period. The emissions would be generated mainly 

in remote, uninhabited areas. The worst case emissions conservatively assume operation 

year round. 

Air emissions from alternative B would be temporary and are not anticipated to 

significantly impair air quality in the region. Increases in emissions or direct impacts on 

ambient air quality from alternative B would be expected to be short-term and minor and 

would not be expected to cause or contribute to a violation of Federal or state ambient air 

quality standards. 

Indirect Impacts

Over the period of analysis, alternative B would restore approximately 30,002 acres of 

emergent wetland, swamp, and ridge habitat that would help improve local air quality by 

reducing particulates and gaseous air pollutants. Various research findings from the 

Urban Forestry Network indicated that increasing the acreage of trees and other 

vegetation in coastal Louisiana would improve air quality in the region, which would 

provide positive benefits for residents in the project area.

Cumulative Impacts

By its very nature, air pollution is largely a cumulative impact. Ambient air quality 

standards are violated or approach non-attainment levels due to past development. 

Attainment of the NAAQS standards can be jeopardized by increasing emissionsgenerating activity in a specified region. The parishes defined in the MRGO study area 

(St. Bernard, Orleans, and St. Tammany) are classified as attainment for all pollutants. 

 

A project is usually considered not significant (less than NAAQS) for cumulative impacts 

of PM10, NOx, SO2, and CO for projects that are principally development projects, or 

where the majority of the emissions of these pollutants is attributable to motor vehicle 

and construction sources. Therefore, cumulative impacts from the MRGO construction 

activities within the impact study area would be considered less than significant. 

In the event that outside projects are constructed simultaneously, it is possible that 

cumulative emissions may temporarily exceed the significance thresholds. This impact, if 

it occurs, would be short-term, and would be dependent on the construction schedules for 

other projects. If other proposed projects are constructed simultaneously, a significant 

temporary cumulative impact may occur for all pollutants. Implementation of mitigation 

measures can reduce cumulative emissions to below a level of significance.

Cumulative impacts include the incremental effects of projects that may have an 

individually minor, but a collectively significant, impact on air quality. The change in the 

environment and increase of emissions when added to other closely related past, present, 

or reasonably foreseeable future projects, can result from individually minor, but 

collectively significant, projects taking place over a period of time.
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Since the development of the MRGO project would not result in long-term significant 

impacts to regional air quality during on-going operations, the project’s incremental 

contribution to this significant impact would also be less than significant.

The incremental impacts would likely be so small as to be “de minimus” may be 

determined to be not cumulatively considerable. A “de minimus” contribution is one that 

leaves the environmental conditions “essentially the same” whether or not the project is 

implemented.

4.9.3 Alternative C - MRGO Restoration Plan 7

Direct Impacts

Under alternative C, direct impacts to ambient air quality would be similar to those 

described under alternative B, except that the amount of borrow needed and the acreages 

of construction features would be different. The more than 30 construction features of 

alternative C would use a total of approximately 152 mcy of borrow to create and nourish 

44,188 acres of marsh and 10,318 acres of swamp; construct 314,944 linear feet of 

shoreline protection; and construct 6,924 acres of retention dikes, 3,124 acres of earthen 

weirs, and 54 acres of ridge restoration. Each feature would consist of one or more of 

these construction activities. Construction would take place in three Louisiana parishes 

including St. Bernard, Orleans, and St. Tammany, with the majority of construction in St. 

Bernard Parish. Construction activity would span a 10-year period. 

Emissions of criteria pollutants would be generated during construction activities from 

the following sources: 

• Combustion of diesel fuel from construction and support equipment; 

• Disturbance and movement of soils; and 

• Combustion of diesel or gasoline from commuter cars and trucks of workers.

Operation of construction equipment and support vehicles would generate VOCs, PM10, 

PM2.5, NOx, CO, O3, and SO2 emissions from diesel and/or gasoline engine combustion. 

Calculations were performed to estimate the total combustible air emissions on an annual 

basis from a “worst case” scenario associated with alternative C. It was assumed several 

construction activities would take place simultaneously such as shoreline protection 

(potentially two work crews in different features), swamp and marsh nourishment (two

crews), dike retention construction (one crew), and diversion construction (one crew). 

The quantity of equipment needed for each activity can be limited by the availability of 

such equipment, or the availability of construction materials. Alternative C would 

construct six times the amount of shoreline protection as alternative B; however, the 

number of crews may be limited by the availability of rock. For this alternative, the 

number of crews for shoreline protection construction is assumed to be limited to two. 

Alternative C would nourish/create twice the amount of marsh/swamp as alternative B; 

therefore, the crews needed for swamp/marsh creation/nourishment would be double that 
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of alternative B, with two crews. Dike retention crews are estimated at one for 

alternative C, as less than twice the acreage of retention dikes, earthen weirs, and ridges 

would be constructed compared to alternative B. The Violet, Louisiana Freshwater 

Diversion construction remains constant for all three alternatives.

Air emissions and fugitive dust emissions were calculated in the same way as for 

alternative B. A summary of the worst case emissions for alternative C are presented in 

table 4-3. 

During construction, proper and routine maintenance of all vehicles and other 

construction equipment would be implemented to ensure that emissions are within the 

design standards of all construction equipment. 

The air emissions generated from this proposed project would be mobile in nature and 

would be emitted from geographically separate construction sites (features) located 

within three separate Louisiana parishes (St. Bernard, Orleans, and St. Tammany). The 

features would be constructed over a 10-year period. The emissions would be generated 

mainly in rural, uninhabited areas. The worst case emissions above conservatively 

assume operation year round. 

Table 4-3: Total (Worst Case) Air Emissions (tons/year) from 

Alternative C Construction Activities Pollutant Total (tons/year)

Pollutant

Total Emissions 

(Tons/Year)

Carbon Monoxide (CO) 183

Volatile Organic Compounds (VOCs) 40

Nitrous Oxides (NOx) 524

Particulate matter < 10 microns (PM10) 97

Particulate matter < 2.5 microns (PM2.5) 43

Sulfur Dioxide (SO2) 70

Air emissions from alternative C would be temporary and would not be anticipated to 

significantly impair air quality in the region. Increases in emissions or impacts on 

ambient air quality would be expected to be short-term and minor and would not be 

expected to cause or contribute to a violation of Federal or state ambient air quality 

standards. 

There are three recreational features (Bienvenue Triangle, Violet Diversion Park, and 

Shell Beach) considered for alternative C. The details for these recreational 

developments are described in appendix W. The construction of these features will 

include boardwalks, picnic shelters, trails, and parking lots. These minor construction 

activities will have minimal impacts to the total MRGO Project construction emissions.
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Indirect Impacts

Indirect impacts under alternative C would be similar to those described under alternative 

B, except that alternative C would restore approximately 54,560 acres of emergent 

wetlands and ridge habitat that would help improve local air quality by reducing 

particulates and gaseous air pollutants. As with alternative B, research findings indicated 

that increasing the acreage of trees and other vegetation in coastal Louisiana would 

improve air quality in the region, which would provide positive benefits for residents in 

the project area.

Cumulative Impacts

Cumulative impacts under alternative C would be similar to those described under 

alternative B.

4.9.4 Alternative D - MRGO Restoration Plan 10

Direct Impacts

Under alternative D, direct impacts to ambient air quality would be similar to those 

described under alternative C, except that the amount of borrow needed and the acreages 

of some construction features are slightly different. The more than 30 construction 

features of alternative D would use a total of approximately 154.3 mcy of borrow to 

create and nourish 44,892 acres of marsh and 10,318 acres of swamp; construct 410,567 

linear feet of shoreline protection; and construct 6,933 acres of retention dikes, 3,124 

acres of earthen weirs, and 54 acres of ridge restoration. Each feature would consist of 

one or more of these construction activities. Construction would take place in three 

Louisiana parishes including St. Bernard, Orleans, and St. Tammany, with the majority of 

construction in St. Bernard Parish. Construction activity would span a 10-year period. 

Air emissions and fugitive dust emissions were calculated in the same way as for 

alternative C. The same number of crews is estimated as for alternative C; therefore, the 

estimate of worst case emissions would be the same in source, quantity, and nature as 

those presented for alternative C in table 4-3. 

Indirect Impacts

Indirect impacts under alternative D would be similar to those described under alternative 

B, except that alternative D would restore approximately 55,264 acres of emergent 

wetlands and ridge habitat that would help improve local air quality by reducing 

particulates and gaseous air pollutants. As with alternative B, research findings indicated 

that increasing the acreage of trees and other vegetation in coastal Louisiana would 

improve air quality in the region, which would provide positive benefits for residents in 

the project area.
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Cumulative Impacts

Cumulative impacts under alternative D would be similar to those described under 

alternative B.

4.10 NOISE

4.10.1 Alternative A - No Action Plan

Direct Impacts

Under the no action alternative, there would be no direct impacts on noise. If ecosystem 

restoration measures are not implemented, existing noise levels would continue. A large 

portion of the project area is a remote and uninhabited marsh with low ambient noise 

levels. 

Indirect Impacts

Under the no action alternative, there would be no indirect impacts on noise. If

ecosystem restoration measures are not implemented, existing noise levels would 

continue. A large portion of the project area is a remote and uninhabited marsh with low 

ambient noise levels. 

Cumulative Impacts

The no action alternative would not contribute to cumulative impacts on noise. If

ecosystem restoration measures are not implemented, existing noise levels would 

continue. A large portion of the project area is a remote and uninhabited marsh with low 

ambient noise levels. 

4.10.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

Construction activities associated with implementing alternative B would temporarily 

increase noise levels in the project area. However, most of the project area is remote and 

unpopulated, so noise impacts would not affect any nearby human communities. After 

completion of construction activities, noise levels would return to preconstruction 

conditions. 

Some noise impacts may be expected from construction activities, although construction 

equipment would be limited in the level of noise that can be emitted. Institutional 

recognition of noise, such as provided by the regulations for Occupational Noise 

Exposure (29 CFR Part 1910.95) under the Occupational Safety and Health Act of 1970, 

as amended, would continue. This regulation requires that noise levels emitted from 
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construction equipment must be below 90 dBA for exposures of eight hours per day or 

more. Noise impacts from construction activities associated with alternative B would be 

anticipated to be minor, localized, and temporary. 

Wildlife and fish would likely temporarily leave the local project areas during 

construction activities due to noise impacts. However, tolerance of unnatural disturbance 

varies among species. There is an abundance of technical and scientific literature on 

“acoustic ecology,” addressing insects, fishes, frogs, lizards, birds, and mammals. By far 

the most studied are birds and marine mammals (Rabin, et al., 2003; Ord and Stamps, 

2008; Francis, et al., 2009). In the local project areas, occasional and localized noise 

from construction may disturb breeding birds. For example, construction noise could 

interfere with bird communications (bird songs attempting to attract mates, providing 

“alert signals” to other individuals, and/or “begging” [for food] by nestlings). 

Because impacts are anticipated to be minor, localized, and temporary, no significant 

direct impacts to wildlife, fishes, or breeding birds would be anticipated. 

Because sound travels faster and is much less attenuated in water than in air some of the 

proposed dredging or construction activities may adversely affected. Some aquatic

organisms (e.g., fish) are particularly sensitive to high-energy noise sources that produce 

a short, sharp, low-frequency sound. For example, such exposures may damage fish 

sensory organs and other related tissues (McCauley, et al., 2003). Sound travels faster 

and is much less attenuated in water than air. This can result in interference with aquatic 

mammals and fish communications. For example, dolphins have complex acoustic 

signals (especially between females and their young), and many fishes that occur in the 

project area (e.g., silver perch, croakers) use acoustic signals in their breeding activities. 

However, most individuals of such animals are likely to avoid the immediate 

disturbances before serious sound levels become dangerous. 

Indirect Impacts

No additional sources of noise, such as indirect commercial or industrial development, 

would be expected to be constructed as a result of alternative B. Therefore, this 

alternative would have no indirect significant impacts on noise. 

Cumulative Impacts

Cumulative impacts would result principally from potential short-term disruption to fish 

and wildlife behavior due to construction noise and similar impacts from other reasonably 

foreseeable future Federal, state, local, and private restoration activities. Long-term 

adverse cumulative impacts due to noise would not be expected with implementation of 

alternative B. No significant adverse noise impacts were identified due to potential 

increases in the cumulative sound levels of the project areas.

However, it is reasonable to anticipate increased boat traffic noise in some portions of the 

cumulative created and/or improved habitats. The enhanced swamp forests, for example, 

are likely to gradually increase wildlife populations that may be sensitive to noise, as well 
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as increase recreational boating and commercial fishing vessel use. Similar increases in 

other restored habitats could also produce more traffic noise. 

4.10.3 Alternative C - MRGO Restoration Plan 7

Direct Impacts

Direct impacts would be similar to alternative B, but alternative C would provide more 

creation and/or nourishment of marsh habitat, with increased temporary disruptions to 

local fishes and wildlife.

Indirect Impacts

No additional sources of noise, such as indirect commercial or industrial development, 

would be expected to be constructed as a result of alternative C. Therefore, this 

alternative would have no indirect significant impacts on noise. 

Cumulative Impacts

Cumulative impacts would be similar to alternative B, but alternative C would affect a 

larger area due to the creation and/or nourishment of marsh habitat. No significant 

adverse noise impacts were identified due to potential increases in the cumulative sound 

levels of the project areas.

However, it is reasonable to anticipate increased boat traffic noise in some portions of the 

cumulative created and/or improved habitats. The enhanced swamp forests, for example, 

are likely to gradually increase the variety and density of some migratory and resident 

wildlife species that may be sensitive to noise impacts. Similar increases in other 

restored habitats could also produce more vessel use and, therefore, increase traffic noise

levels. 

4.10.4 Alternative D - MRGO Restoration Plan 10

Direct Impacts

Direct impacts would be similar to alternative B, but alternative D would provide more 

creation and/or nourishment of marsh habitat, with increased temporary disruptions to 

local fishes and wildlife.

Indirect Impacts

No additional sources of noise, such as indirect commercial or industrial development, 

are expected to be constructed as a result of alternative D. Therefore, this alternative 

would have no indirect significant impacts on noise. 
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Cumulative Impacts

Cumulative impacts would be similar to alternative B, but alternative D would affect a 

larger area due to the creation and/or nourishment of marsh habitat. No significant 

adverse noise impacts were identified due to potential increases in the cumulative sound 

levels of the project areas.

However, it is reasonable to anticipate increased boat traffic noise in some portions of the 

cumulative created and/or improved habitats. The enhanced swamp forests, for example, 

are likely to gradually increase the variety and density of some migratory and resident 

wildlife species that may be sensitive to noise impacts. Similar increases in other 

restored habitats could also produce more vessel use and, therefore, traffic noise levels. 

4.11 HAZARDOUS, TOXIC, AND RADIOACTIVE WASTE

USACE performed a Phase I Environmental Site Assessment (ESA) in accordance with 

the scope and limitations of the American Society for Testing and Materials (ASTM) 

“Standard Practice for Environmental Site Assessments: Phase I Environmental Site 

Assessment Process, E 1527-05”, for the project area defined as: the MRGO and 

surrounding areas of Lake Borgne, Orleans, St. Tammany, St. Bernard, and Plaquemines 

Parishes. 

Reference appendix Q for the Phase I report and associated appendices. 

The records search showed numerous areas of significance. Eastern Orleans Parish is 

heavily populated with various industries generating and handling large quantities of 

hazardous substances and wastes. Most of these locations are one mile or more from the 

closest project area borders. There are few records of significant accidents, spills, and 

violations in the area that could possibly suggest a release into the project areas. A few 

facilities lie on project borders or within the designated project areas; however, these 

location did not present records suggesting a significant release of hazardous materials.

St. Bernard and Plaquemines Parishes are generally less developed than Orleans Parish; 

however, there are several notable petroleum and natural gas facilities in the area. There 

are no records indicating a significant release into the project areas and the distance of the 

majority of the facilities from the project areas suggest these facilities are of minimal 

concern. A few facilities of interest lie in close proximity to the project borders or within 

the designated project areas; however, these locations did not present records suggesting 

a significant release of hazardous materials. 

In the areas of St. Tammany Parish investigated there are no significant areas of concern.

Past Phase I and Phase II ESAs have been performed throughout the current project 

areas. During the de-authorization of MRGO in 2007, a Phase I ESA was performed by 

BEM Systems Inc. on the MRGO area. The report did not present any documentation of 
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significant release of hazardous materials in the project areas. The report notes the 

concern of the presence of the petroleum industry throughout the area. The report noted 

the likelihood of petroleum releases in the area that were unreported from pipelines and 

gas/oil wells which are ubiquitous throughout the areas (appendix Q). Another general 

concern noted in the 2007 Phase I ESA is contamination transport due to past flooding. 

There are nearby areas of development with facilities of environmental significance, 

which may have contributed indirectly to hazardous materials reaching project areas 

through significant area flooding. 

A specific site of concern was noted; the former Shell Beach Anti-Aircraft Training 

Center, one-half mile north of MRGO Mile Marker 42 on the east side of Lake Borgne 

(appendix Q). This area should be handled with extreme caution in the case on 

encountering ammunition. The report suggested full soil and sediment chemical analysis 

to ensure proper handling of dredged material. It is assumed that this recommendation 

was not based on records, interviews, prior knowledge or site reconnaissance results, but 

on a conservative judgment based on the land/water usage of the area. 

Several Phase II ESAs have been performed in the vicinity of the project areas. Between 

the years 2007 to 2009, there has been no analytical data showing elevated levels of 

contaminants of concern (COCs) surpassing RECAP screening standards. Site 

reconnaissance was limited due to the size of the project areas and remoteness. Facilities 

of interest could not be closely investigated since they are private properties and access 

was not granted. However, there is no documentation to suggest that there has been a 

significant release from the facilities investigated into the project areas. Several levees 

that bordered project areas were driven by vehicle in search of possible recognized 

environmental concerns (RECs), of which, none were found. 

It is suggested by the Environmental Team ED-F that further investigation, possibly 

analytical testing, be explored for project areas in the vicinity of developed areas. The 

project areas are heavily used by the petroleum industry.

The nature of surrounding land usage is very suspect despite the lack of reported 

incidents, lack of significant findings in past Phase I ESAs, and insignificant analytical 

data from past Phase II ESAs. North of the MRGO in eastern Orleans Parish is very 

industrial. Petroleum companies are also located throughout St. Bernard Parish. 

Industrial land usage can be of concern due to contaminant transport to project areas by 

flooding. Caution is advised in all areas of petroleum exploration, including wells and 

pipelines. 

The historical Shell Beach Anti-Aircraft facility just north of Mile Marker 42 of the 

MRGO could present issues of unspent ammunitions, which should be handled with 

extreme caution.

Unexpectedly encountered environmental issues should be handled appropriately, and as 

project areas approach developed areas, more caution is advised. 
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4.11.1 Alternative A - No Action Plan

Direct Impacts

Consistent with E 1527-05, a Phase I ESA investigation of the project area was 

conducted. Based on the finding, the no action alternative would have no direct impacts 

on HTRW sites in the study area. A large portion of the project area is remote and 

uninhabited marsh. HTRW would continue to be subject to institutional recognition and 

further regulations. 

Indirect Impacts

Consistent with E 1527-05, a Phase I ESA investigation of the project area was 

conducted. Based on the finding, the no action alternative would have no indirect

impacts on HTRW sites in the study area. A large portion of the project area is remote 

and uninhabited marsh. HTRW would continue to be subject to institutional recognition 

and further regulations. 

Cumulative Impacts

Consistent with E 1527-05, a Phase I ESA investigation of the project area was 

conducted. Based on the finding, the no action alternative would not contribute to the 

cumulative impacts on HTRW sites in the study area. A large portion of the project area 

is remote and uninhabited marsh. HTRW would continue to be subject to institutional 

recognition and further regulations. 

4.11.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

Direct impacts associated with alternative B would be the same as those described under 

alternative A. 

Indirect Impacts

Indirect impacts associated with alternative B would be similar to those described under 

alternative A. 

Cumulative Impacts

Cumulative impacts associated with alternative B would be similar to those described 

under alternative A. 
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4.11.3 Alternative C - MRGO Restoration Plan 7

Direct Impacts

Direct impacts associated with alternative C would be the same as those described under 

alternative A. 

Indirect Impacts

Indirect impacts associated with alternative C would be similar to those described under 

alternative A. 

Cumulative Impacts

Cumulative impacts associated with alternative C would be similar to those described 

under alternative A. 

4.11.4 Alternative D - MRGO Restoration Plan 10

Direct Impacts

Direct impacts associated with alternative D would be the same as those described under 

alternative A. 

Indirect Impacts

Indirect impacts associated with alternative D would be similar to those described under 

alternative A. 

Cumulative Impacts

Cumulative impacts associated with alternative D would be similar to those described 

under alternative A. 

4.12 BARRIER ISLAND RESOURCES

The restoration of the Chandeleur and Breton Islands are unique from other barrier island 

projects as this restoration is planned to mimic the natural processes that encompass the 

early stages of barrier island evolution including lateral transport of sand to the flanks 

from a centralized sand source. This would enhance the islands’ ability to naturally build 

back-barrier marsh, dunes, and a sandy shoreline. The proposed design is broken down 

into two sections that are prioritized based on predicted effectiveness and longevity: (1) 

Chandeleur Islands, and (2) Breton Island.
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4.12.1 Alternative A - No Action Plan

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 overall 

species diversity and biomass (Hester et al., 2005). Survival of some of the T&E species, 

in particular the loggerhead sea turtle, may be threatened. The Chandeleur and Breton 

Islands exclusively provide the high-energy beaches essential for their nesting sites in the 

region (see section 3.13.5.2) and these would be lost without restoration efforts 

(O’Connell et al., 2005). Other T&E species such as the piping plover and brown pelican 

also thrive on the islands and would lose habitat if the islands continue to deteriorate. 

Without the Chandeleur and Breton Islands, wetland resources on the islands as well as 

estuaries, wetland and aquatic habitats, and populated communities on the mainland 

Louisiana coastline to the west would have no barrier to shield against the wave and wind 

action from the frequent storms and hurricanes from the Gulf of Mexico.

With respect to island restoration, preliminary modeling efforts of proposed alternatives, 

as discussed in section 2.3.4 and shown in appendix J, indicate that additional study is 

warranted for the Chandeleur and Breton Barrier Island Chain. While variables utilized 

in the preliminary modeling efforts were valuable and feasible, it was deemed necessary 

for the engineering team to further develop feasibility design and costs. Therefore, more 

studies and development would be conducted at a later date. 

4.13 COASTAL VEGETATION RESOURCES

4.13.1 Alternative A - No Action Plan

The no action alternative would result in continued direct adverse impacts on coastal 

vegetation resources as there would be no construction activities. Marsh habitat would 

continue to be restored through other restoration projects and programs, such as the 

CWPPRA, the CIAP, and the LCA as described in chapter 2, 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. 
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Direct Impacts

With no action, 9,850 acres of emergent wetlands in the project area are predicted to be 

lost over the next 50 years. Approximately 6,255 acres of brackish marsh and 3,595 

acres of saline marsh are projected to be lost. Overall, the majority of direct land loss 

would be expected to occur to interior wetlands. However, substantial wetland losses 

would also be predicted to occur along the shoreline due to erosion. In addition, if 

landbridges are breached, existing 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).

Indirect Imapcts

Indirect impacts include the continued loss of intermediate and brackish marsh from 

saltwater intrusion. Loss rates would accelerate as marsh is lost and converted to open 

water, allowing increased salinity further inland and into previously buffered marshes. 

Cumulative Imapcts

Cumulative impacts include the synergistic effect of “no action” with the additive 

combination of coast wide wetland loss and degradation, as well as the benefits and 

impacts of reasonably foreseeable future state and Federal projects in the vicinity, as 

detailed in section 4.1.1. 

The WRDA 2007 authorized design and implementation of a freshwater diversion at or 

near Violet, Louisiana, to reduce salinity in the western Mississippi Sound, enhance 

oyster production, and promote the sustainability of coastal wetlands. Feasibility

modeling indicates it would require up to 7,000 cfs to accomplish these goals. Coupled 

with the closure structure on the MRGO at the Bayou La Loutre Ridge, the diversion at 

or near Violet, Louisiana would add freshwater to the surrounding waters. This addition 

of freshwater could result in a conversion of some saline marshes to brackish marshes in 

the Biloxi Marsh portion of the project area. However, such wetland conversion would 

probably have little effect on the species composition of the wetlands in the project area 

other than a slight shift towards less salt tolerant species. The introduction of nutrients 

would likely increase the productivity of the nearby marshes. 

4.13.2 Alternative B - MRGO Restoration Plan 2

Alternative B incorporates all restoration measures under consideration within the areas 

described in section 2.10. These discussions detail both the negative and positive 

impacts of restoration measures by area as it pertains to redistribution of the coastal 

vegetation zones due primarily to changes in area hydrology and salinity. The greatest 

potential to restore and sustain coastal forests is near the Mississippi River where 

freshwater reintroductions may be implemented. Other local sources of freshwater may 

be municipal wastewater or storm water. Cumulative impacts to coastal vegetation by 
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alternative B would be the incremental impact of the implementation of alternative B 

together with present and reasonably foreseeable future projects. 

Direct Impacts

Implementation of alternative B includes freshwater diversion via the proposed Violet, 

Louisiana Freshwater Diversion channel, freshwater introduction from the East Orleans 

POTW effluent discharge, restoration of approximately 19,630 acres of marsh habitats, 

10,318 acres of cypress swamp, and 54 acres of ridge habitat that provide 35,367 linear 

feet of shoreline protection. 

The LCA Study (USACE, 2004) estimated wetland habitat net losses in the project region 

at 2,880 acres/year or approximately 15 percent of the all wetlands in the project area in 

just the last 22 years. Alternative B would reverse this trend and convert 7,444 acres of 

open water to emergent wetland habitat and nourish 12,186 acres of existing habitat. 

The Violet, Louisiana Freshwater Diversion would be constructed along the east bank of 

the Mississippi River for the introduction of freshwater into the Central Wetlands area 

and adjacent open water and ancillary wetlands. The structure would be engineered to 

deliver a minimum discharge of 1,000 cfs and with pulsing capacity of 7,000 cfs. 

Additionally, the effluent discharge from the East Orleans Sewerage Treatment Plant 

would provide an additional 167 cfs of nutrient-laden freshwater to the Central Wetlands 

on the western end of the cypress swamp/fresh marsh complex. Alternative B would 

convert 4,225 acres of open water to cypress swamp and nourish an additional 6,093 

acres of swamp.

The influx of freshwater would be the principal influence on the overall impacts to 

coastal vegetation. These impacts would be manifested through corresponding habitat 

shifts and a possible redistribution of the vegetation zones. Closure of the MRGO has 

already produced tangible reductions in salinity in the Lake Borgne area. Changes to the 

marsh or coastal vegetation zones would be dictated by the salinity tolerances of the 

dominant vegetation along with available nutrients and zone elevation (hence the 

importance of specific site elevations as it relates to flooding and duration). 

The results of the salinity modeling reported in the 2010 Hydraulics & Hydrology 

Modeling Report indicate a maximum salinity reduction of 1.0 ppt to1.4 ppt in Lake 

Borgne from May to December based on the proposed diversion base flow of 1,000 cfs 

and a peak diversion flow of 7,000 cfs. Salinity reductions in this predicted range should 

not substantially alter or shift the existing emergent habitat zones in the Biloxi Marsh, 

East Orleans, or South Lake Borgne regions. 

The results of the aquatics model adapted to assess the ecological effects of the proposed 

freshwater diversion on the emergent vegetation community surrounding the MRGO 

indicated that the year-to-year variations in the systemic environmental parameters (i.e., 

water temperature, nutrient input, etc.) of the project area were primarily responsible for 

the changes in net productivity rather than the predicted influx of water from the 
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diversion. The findings of the aquatics modeling could be reasonably interpreted to infer 

no adverse impacts on the productivity of emergent coastal vegetation in the project 

vicinity.

Earthen retention dikes would be constructed from borrow taken from within each marsh 

creation site. The dike features would be mechanically breached or degraded within three 

years of construction, if natural degradation has not sufficiently removed the earthen 

material. Impacts from the construction of retention dikes would be considered 

temporary and would be mitigated by recruitment of native vegetation and/or the planting 

of the areas. Approximately 3,890 acres of temporary retention dikes would be 

constructed under this alternative. 

Flotation access channels would be excavated, as needed, in shallow water areas to allow 

construction equipment access to some project features (shore protection sites and marsh 

creation areas). The materials would be temporarily stockpiled on water bottoms 

adjacent to the excavated channel. Flotation access channel material would be used to 

backfill the flotation access channels following completion of the work. Increased 

turbidity would be the most immediate impact from the excavation and construction 

activities. Once the activities have been completed and the dredge material is returned to 

the previously excavated areas, natural recruitment and rehabilitation of the disturbed 

areas should occur. 

The area under the influence of the diversion would also be expected to experience a 

revitalization of SAV, such as pondweed, southern naiad, coontail, and wild celery. 

These plants grow from the bottom of shallow marsh ponds and lagoons and would 

benefit from the lower salinity and water clarity as demonstrated by similar SAV growth 

in the vicinity of the Caernarvon Freshwater Diversion project. Wave action, currents, 

temperature, salinity, substrate characteristics, and light penetration (turbidity) determine 

species assemblage (LNDR, 1987). Of these parameters, salinity and turbidity would be 

affected the most by the proposed activities. Impacts would decrease as the distance 

from the point of disturbance increases.

Salinity in the Mississippi Territorial Waters is predicted to be reduced by 0.6 ppt to 0.9 

ppt under the combined influence of the 1,000/7,000 cfs of the Violet, Louisiana

Freshwater Diversion and the 4,000 cfs of the Maurepas Swamp Area diversions. This 

minimal reduction in salinity is well within the tolerance of the dominant emergent and 

submergent coastal vegetation species of the fringing coastal marshes and seagrass beds 

of the Mississippi coastline. Therefore, there would be no impact on coastal vegetation. 

According to Moncreiff et al., (1998), by 1998 Mississippi had lost virtually all but one 

of its marine seagrass species. Only Halodule wrightii (shoal grass) existed in any 

measurable acreage in the Mississippi Sound. Two additional species of seagrasses, 

Ruppia maritima and Vallisneria americana, occur along the shoreline in the vicinity of 

St. Louis Bay in Hancock County. Elevated nutrient levels and higher sediment loads 

have been attributed to the decline in the seagrass beds along with the catastrophic 

disturbance of the sea floor by major hurricanes. The salinity fluctuations anticipated as 
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a result of alternative B should not have an adverse impact on the seagrass beds in the 

Mississippi Territorial Waters.

The most prevalent direct impacts would an increase in cypress swamp habitat through 

nourishment and creation, increased marsh habitat, and a corresponding reduction in 

saltwater intrusion. 

Indirect Impacts

One indirect impact of the introduction of nutrient-rich river water and discharge effluent 

is the potential for eutrophication. The MRGO Salinity Working Group anticipates the 

introduction of nutrients to the aquatic ecosystem following river diversion and POTW 

effluent discharge would enhance productivity of the ecosystem in the long term. 

Predictions of the water quality responses in both Lake Borgne and the Biloxi marsh to 

the probable loading from various constituents in a Mississippi River diversion found 

minimal to non-detectable adverse impacts to water quality in the Biloxi Marsh (USACE, 

2010). Changes expected in the concentrations of total nitrogen, total suspended solids, 

and chlorophyll-a would be expected to be minor in the Biloxi Marsh area, even with 

diversion flows sufficient to meet or maximize the salinity targets for oyster development 

(USACE, 2010).

The Salinity Working Group noted that although levels of total suspended solids and total 

nitrogen would increase substantially in Lake Borgne, the already turbid nature of Lake 

Borgne in concert with the shallow and well-flushed nature of the lake system does not 

provide evidence that sufficient adverse changes to nutrient concentrations would impact 

coastal vegetation. The systematic flushing of the lake and marsh complex would be 

expected to minimize the potential for eutrophication. 

Cumulative Impacts

The area where the potential cumulative impacts would primarily occur would be the 

Lower Pontchartrain sub-basin, which includes Lake Borgne, the deauthorized MRGO, 

Biloxi Marshes and out toward the Chandeleur and Breton Sounds. In Mississippi, the 

area includes the Western Mississippi Sound, including the bordering wetlands and Cat 

Island. 

Construction of several freshwater diversion projects (other than the Violet, Louisiana

Freshwater Diversion) in the study area, have been projected to have a 2-3 ppt reduction 

in salinity in the Lake Pontchartrain sub-basin. The input of freshwater from the 

proposed Violet, Louisiana Freshwater Diversion is projected to reduce salinity change 

from -1.0 to -1.4 ppt in Lake Borgne closer to the source while salinity reductions in the 

Mississippi Sound are predicted to be -0.6 to -0.9 ppt under the influence of the Violet, 

Louisiana Freshwater Diversion. The combined diversion effects on salinity are a 

reduction of -3.0 to -4.4 ppt in the Lake Borgne vicinity and -2.6 to -3.9 ppt in the 

Mississippi Sound. The greater reduction in salinity predicted would be attributable to
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the cumulative effects of the diversions in the Lake Pontchartrain Basin rather than the 

effects of the Violet, Louisiana Freshwater Diversion. The salinity anticipated would be 

within the tolerance range for the dominant intermediate and brackish water species 

present in the project area. The reduction in salinity would have little or no effect on the 

coastal vegetation resources of these habitats.

The combined effect of the introduction of freshwater to retard increasing future salt 

water intrusion along with the proposed march nourishment and restoration plantings 

should have a positive impact through stabilizing or increasing intermediate and brackish 

marsh habitat.

While the overall cumulative impacts from alternative B would have a net positive 

benefit in terms of habitat creation and protection, there are several external factors that 

could offset a portion of these benefits. The project area in southeast Louisiana is located 

along the Gulf Coast and is susceptible to tropical cyclone activity every year from June 

through November. There is a moderate risk every year for a tropical storm or hurricane 

to impact the area causing land loss and inundation with saline waters that would have an 

immediate and long-term impact to the restoration features and project area as a whole. 

A second key factor in the potential cumulative effects to the region is from the oil and 

gas industry. Oil and gas exploration, production, and transportation are major economic 

drivers in the project area and coastal Louisiana. A comprehensive list of future projects 

would be very difficult to develop due to the private and rapidly changing nature of the 

industry. However, it is prudent to assume the potential for future impacts from 

dredging, due to the development of oil and gas infrastructure including pipelines, 

platforms, or exploration activities, to the restoration features or other wetland habitat in 

the project area. In addition, potential oil spills would have negative impacts on coastal 

vegetation. 

4.13.3 Alternative C - MRGO Restoration Plan 7

Similar to alternative B, this alternative includes a freshwater diversion and limited ridge 

restoration; however, this alternative includes restoration and creation measures not 

identified in alternative B. The type of restoration measures between alternative C and 

alternative B are essentially the same with the difference being an increase in the acreage 

created and linear feet of shoreline protection proposed within a planning subunit. 

Direct Impacts

Implementation of alternative C includes freshwater diversion via the proposed Violet, 

Louisiana Freshwater Diversion channel, freshwater introduction from the East Orleans 

POTW effluent discharge, restoration of approximately 44,188 acres of marsh habits,

10,318 acres of cypress swamp, and 54 acres of ridge habitat that provide 314,944 linear 

feet of shoreline protection. Alternative C is estimated to convert 17,352 acres of exiting 

open water to emergent wetlands habitat and nourish 26,836 acres of existing marsh 

habitat and 6,093 acres of swamp. 
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In addition to the measures proposed in alternative B, this alternative includes 24,558 

acres of additional marsh restoration and nourishment, plus 314,944 linear feet of 

shoreline protection measures in the Biloxi Marsh, East Orleans, and South Lake Borgne 

areas. An additional 6,924 acres of retention dikes would be required for implementation 

of this alternative. Wetland vegetation in these areas would be temporarily impacted by 

dike and channel construction. However, these earthen retention dikes would breached or 

degraded within three years of construction, if necessary. 

Impacts from implementation of alternative C would be similar to alternative B; however, 

the quantity of acreage impacts would be greater.

Indirect Impacts

Indirect impacts to coastal vegetation by alternative C would be similar to alternative B 

with a greater quantity of acreage impacted. 

Cumulative Impacts

Alternative C would contribute to the cumulative impacts to coastal vegetation to a 

similar degree to those described in alternative B with a great quantity of acreage impacts 

due to additional engineering measures. These impacts would result from the combined 

effects of the existing and proposed diversion projects in the study area together with the 

freshwater influx from Violet, Louisiana Freshwater Diversion along with the added 

effects of the additional engineering measures proposed for this alternative. Due to the 

very small fluctuation in salinity, no substantial cumulative impact would be anticipated 

in the Mississippi Territorial Waters.

4.13.4 Alternative D - MRGO Restoration Plan 10

Alternative D is similar to the other action alternatives, but with additional restoration 

measures not identified in alternative C. The restoration measures identified for 

alternative C and alternative D are essentially the same with the contrast being an

increase in acreage created and length of shoreline protected within a planning subunit. 

In addition to the measures proposed in alternative C, this alternative includes 704 acres 

of additional wetland restoration and nourishment as well as 95,623 linear feet of 

shoreline protection. 

Direct Impacts

Implementation of alternative D includes freshwater diversion via the proposed Violet, 

Louisiana Freshwater Diversion channel, freshwater introduction from the East Orleans 

POTW effluent discharge, restoration of approximately 18,056 acres of marsh habitats, 

4,225 acres of cypress swamp, and 54 acres of ridge habitat that provide 410,567 linear 

feet of shoreline protection. 
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Impacts from implementation of alternative D would be similar to alternatives B and C 

with the quantity of impacts being greater for this alternative. Alternative D would 

convert 18,056 acres of open water to emergent wetlands habitat and nourish 26,836 

acres of marsh habitat and 6,093 acres of swamp.

As with alternatives B and C, alternative D would provide significant benefits to coastal 

vegetation within the project area. Forested wetlands and emergent marsh habitats would 

receive the input of freshwater nutrients from the diversion in addition to the lower 

salinity derived from the increased freshwater input to the area. In addition, the 

additional sediment from borrow areas would increase marsh elevations and compensate 

for anticipated ongoing land subsidence and sea level rise. 

Indirect Impacts

Indirect impacts to coastal vegetation by alternative D would be similar to those 

described in alternative B with a greater quantity of acreage impacted due to additional 

engineering measures. 

Cumulative Impacts

Cumulative impacts to coastal vegetation under alternative D would be similar to those 

described in alternative B due to additional engineering measures. These impacts would 

result from the synergistic effects of all the existing and proposed diversion projects in 

the study area combined with the freshwater influx from Violet, Louisiana Freshwater 

Diversion along with the added effects of the additional engineering measures proposed 

for this alternative. Due to the very small fluctuation in salinity, no substantial 

cumulative impact would be anticipated in the Mississippi Territorial Waters.

4.14 WILDLIFE RESOURCES

4.14.1 Alternative A - No Action Plan

Direct Impacts

Under alternative A, there would be no direct adverse impacts to wildlife resources. 

Indirect Impacts

Habitat quality would decline as wetlands continue to deteriorate and fragment, 

specifically in the critical landbridges within the project 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). 
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The Coast 2050 Plan shows the status, functions of interest, trends, and projections 

through 2050 for avifauna, furbearers, game mammals, and reptiles across the state by 

mapping units (LCWCRTF & WCRA, 1999). The South Lake Borgne mapping unit 

encompasses the landbridge between the MRGO and Lake Borgne, and the Lake Borgne 

mapping unit encompasses the open waters of Lake Borgne northward to the Rigolets 

(see table 3-23). Bald eagles, geese, woodland residents or migrant birds, and squirrels 

are not historically present in these mapping units. Avian resources in the study area 

would be expected to either remain steady or decline with the exception of brown 

pelican, which would be expected to increase use of open water habitats in both mapping 

units. Most other wildlife resources would be expected to decline with the no action 

alternative.

Cumulative Impacts

Without an extensive ecosystem restoration plan, marsh habitat in the project area would 

continue to be restored through other restoration projects and programs, such as those 

authorized for construction through CWPPRA, CIAP, and LCA; these projects would 

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. Adverse 

cumulative impacts would result from the no action alternative as follows: 

• continued conversion of existing vegetated wetlands used as foraging, nesting, 

and over-wintering habitat to open water habitats; 

• continued bankline erosion and sloughing of the shoreline; and

• continued encroachment of salinity in areas with brackish and freshwaters.

4.14.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

During construction, marsh creation and restoration activities would temporarily affect 

wildlife by disrupting their activities and displacing them (and their prey) from the 

immediate construction zone. These impacts would be temporary and localized. Once 

construction is complete, most if not all wildlife and prey species would return to the 

area. Any habitat impacted during construction would be restored before leaving the 

area. Board roads and marsh buggies would be used in access routes crossing existing 

wetlands. When the access is no longer needed, the board roads would be removed, and 

the impacted wetlands would be restored by pumping dredged material onto the site to a 

height conducive to marsh restoration. 

Indirect Impacts

Under alternative B, the restoration plan would create and nourish 19,630 acres of marsh 

and 10,318 acres of swamp, protect 35,367 linear feet of shoreline, and restore 54 acres 

of unique ridge habitat that would be used by resident and migrant avian species for 

nesting, rearing of young, resting, and foraging activities. The freshwater diversion 
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would impact approximately 529 acres. The restored habitat would provide important 

stopover habitat for neotropical migrants and wintering habitat for waterfowl. Brackish 

and saline marsh is an important nesting habitat for avian species, such as anhinga, least 

bittern, and seaside sparrow (Frederick and Siegel-Causey, 2000; Gibbs, et al., 2009; Post 

and Greenlaw, 1994). This alternative would create, nourish, and protect estuarine areas 

frequented by wintering waterfowl.

Cumulative Impacts

Cumulative impacts would be the synergistic effect with the additive combination of 

impacts and benefits for overall net acres created, nourished, and protected by other 

reasonably foreseeable future Federal, state, local, and private restoration efforts, as 

summarized in chapter 2. Incremental impacts, as a result of alternative B, would 

combine with CWPPRA projects to provide more complete protection of the landbridge 

and its associated wetland habitats. Wildlife species, including migratory birds, game 

animals, furbearers, reptiles, amphibians, and invasive species (especially nutria and feral 

hogs) that use the project area would also benefit from the cumulative effects of creating, 

nourishing, and protecting the wetlands. Overall, cumulative effects would be positive 

through the anticipated increase in wildlife diversity based on the Coast 2050 Plan. 

As summarized in chapter 2, substantial efforts among the various organizations 

involved in restoration have agreed on combined present and proposed activities. 

Reasonably foreseeable activities could ideally follow a similar approach. However, 

many factors such as global climate change, scientific advancements, and human 

behavior may alter some potential activities.

4.14.3 Alternative C - MRGO Restoration Plan 7

Direct Impacts

Direct impacts would be similar to alternative B, except that alternative C would include 

the creation and nourishment of 44,188 acres of marsh and 10,318 acres of swamp, the 

protection of 314,944 linear feet of shoreline, and the restoration of 54 acres of ridge 

habitat. The freshwater diversion would influence approximately 529 acres. 

Indirect Impacts

Indirect impacts associated with alternative C would be similar to those described under 

alternative B. 

Cumulative Impacts

Cumulative impacts associated with alternative C would be similar to those described 

under alternative B, except that creation and nourishment of marsh and shoreline 

protection could be greater. 
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4.14.4 Alternative D - MRGO Restoration Plan 10

Direct Impacts

Direct impacts would be similar to alternative B, but alternative D would create and 

nourish 44,892 acres of marsh, as well as 10,318 acres of swamp, protect 410,567 linear 

feet of shoreline, and restore 54 acres of ridge habitat. The freshwater diversion would 

influence approximately 529 acres.

Indirect Impacts

Indirect impacts associated with alternative D would be similar to those described under 

alternative B. 

Cumulative Impacts

Cumulative impacts associated with alternative D would be similar to those described 

under alternative B or alternative C, except that creation and nourishment of marsh and 

shoreline protection could be greater than either alternatives B or C. 

4.15 AQUATIC AND FISHERY RESOURCES

An aquatics model (appendix I) has been utilized to assess direct and indirect ecological 

effects of proposed freshwater diversions into Lake Borgne and associated coastal and 

marine areas that define the MRGO ecosystem (subsequently referred to as the aquatics 

model). The aquatics model is a bioenergetics-based ecosystem model that simulates the 

daily production dynamics (gC/m2) of modeled populations of aquatic plants and animals. 

The principal modeling objective was to assess the potential effects of alterations in 

salinity and other water quality parameters that would result from the proposed 

freshwater diversion on selected populations of valued ecological resources in the MRGO 

ecosystem (Bartell et al., 2010).

The aquatics modeling study focused on key species of ecological, recreational, and 

commercial value including oysters, brown shrimp, white shrimp, blue crab, red drum, 

spotted sea trout, striped mullet, Gulf menhaden, bay anchovy, sheepshead, and Atlantic 

croaker. Gulf sturgeon was additionally included because of its threatened species status. 

To address different habitat requirements (e.g., salinity, depth,) juvenile (or immature) 

and adult stages were modeled as separate populations for oysters, blue crab, brown 

shrimp, white shrimp, red drum, and spotted sea trout. The aquatics modeling also 

included zooplankton and zoobenthos as separate generalized consumer populations 

because of their importance as food resources in the model food web. Broadly defined 

populations of phytoplankton and periphyton (i.e., diatoms, green algae, bluegreen algae) 

were modeled as key primary producers in the aquatics model. The modeled food web 

also included four representative submerged aquatic plants: Myriophyllum, Vallisneria, 

Halodule, and Thalassia. The modeled emergent aquatic plant community consisted of 
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individual populations of Distichlis, Phragmites, Sagittaria, Juncus, and Spartina. The 

resulting composition of primary producers and consumers defines a food web structure 

relevant to the MRGO ecosystem. The aquatics model exists as perhaps the most 

complex aquatic food web model ever developed (Bartell et al., 2010). 

The aquatics model was used to simulate the daily biomass of the modeled populations 

for 55 years for 23 selected inshore and offshore locations in the MRGO ecosystem. The 

aquatics model domain includes approximately the southern half of Lake Pontchartrain, 

Lake Borgne, the Biloxi Marsh and extends eastward past Bay St. Louis and Biloxi, and 

southwards past the Chandeleur Islands into the Gulf of Mexico. The 23 locations 

represent a subset of the larger domain defined by the University of New Orleans (UNO) 

hydrology and hydraulics model. The UNO model was developed to characterize 

changes in salinity throughout this larger region projected for several MRGO future 

without-project and with-project conditions (i.e., freshwater diversions) (Bartell et al., 

2010). 

The aquatics model was used to assess changes in fisheries production. These models 

predict changes in Federally managed species (addressed in section 4.18) and other 

commercially important fishery species (addressed in section 4.14), which, combined 

with other factors, were used to predict annual net productivity and biomass within the 

modeled project area (Bartell et al., 2010). 

The daily values of the environmental factors that determine the growth of the 

populations included in the aquatics model were developed from several sources. 

Importantly, the salinity values for each of the 23 locations modeled by the aquatics 

model were obtained from the University of New Orleans (UNO) model results for 

selected without-project and with-project (i.e., freshwater diversion) conditions. The 

UNO model also provided corresponding values of nitrogen, phosphorus, and total 

suspended solids to the aquatics model. Daily surface light intensities were summarized 

from 30 years of data recorded at the New Orleans International Airport. Water 

temperatures were developed from limited UNO results (i.e., node 18) and interpolations 

based on the CRMS monitoring program. Depths were obtained from recent USGS 

bathymetry surveys (Bartell et al., 2010). 

4.15.1 Alternative A - No Action Plan

Direct Impacts

The no action alternative would result in 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. 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 show no significant impacts 

based on aquatics modeling. Reduction in emergent wetlands would result in shifts of 
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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 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. 

Based upon the aquatics model (Bartell et al., 2010) results and Preliminary 

Hydrodynamic and Hydraulic Modeling for a Proposed Freshwater Diversion in the 

Vicinity of Violet, Louisiana (USACE, 2010), under the no action alternative there would 

be no significant impacts to net productivity for the following modeled species from 2015 

to 2065: Atlantic croaker, red drum (juveniles and adults), spotted sea trout (juveniles and 

adults), striped mullet, sheepshead, Gulf menhaden, and bay anchovy. 

As there would be no dredging, wetland restoration, or shoreline protection construction 

activities proposed under the no action alternative, there would be no construction-related 

impacts to aquatic and fishery resources.

Indirect Impacts

Indirect impacts would include continued degradation and loss of habitat used for 

spawning, foraging, cover, nursery, and other life requirements, especially the transitional 

habitat between estuarine and marine environments. Indirect impacts to species that do 

not utilize the wetlands, but whose prey species utilize the wetlands would cause 

competition between resident and migratory fish and other aquatic species for decreasing 

wetland resources.

Cumulative Impacts

Under the no action plan, cumulative impacts to aquatic and fishery resources would 

result from primarily indirect impacts from habitat deterioration. The combination of 

wetland loss within the MRGO ecosystem restoration project area, together with impacts

of other coastal wetland loss would impact foraging, cover, nursery, and spawning 

habitat. Some of these impacts would be offset by implementation of reasonably 

foreseeable future restoration activities in or near the project vicinity such as: CWPPRA 

PO-30 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 (NonContinuous), St. Bernard Parish, LA (07-C-0089) project; and other wetland restoration 

efforts authorized under the LCA Plan in WRDA 2007. Features of the authorized 

HSDRRS as well as the closure structure on the MRGO channel near the Bayou La 

Loutre Ridge could affect the hydrology of the study area. The closure structure near 

Bayou La Loutre has reduced tidal exchange between Lake Borgne and Breton Sound, 

which has reduced salinity in the project area. Additionally, a 2-3 ppt salinity decrease is 
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Restoration Plan 4-67 June 2012

expected within Lake Borgne from freshwater diversion projects such as the 1,000 cfs 

Hope Canal / Maurepas Diversion; and the 3,000 cfs Blind/Convent River Diversion; all 

of which have been authorized under Section 7006 of the WRDA 2007. The Convent 

Blind River Diversion is in the feasibility phase with a final report due in December 

2010. 

Adverse cumulative impacts associated with the no action alternative would include the 

continued deterioration of habitat quality and quantity in the project area causing coastal 

land losses and deterioration of critical habitats along large areas of southeastern 

Louisiana and the Gulf Coast. This deterioration of habitat quality would further stress 

species that are dependent on these habitats for all or a part of their life cycle. Adverse 

cumulative impacts would be offset, to some degree, by the positive impacts of 

implementing the reasonably foreseeable future state and Federal projects (detailed in 

chapter 2) as mentioned above. 

4.15.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

Implementation of alternative B includes a freshwater diversion at/near the Violet Canal, 

restoration of approximately 19,630 acres of marsh habitats, and 10,318 acres of cypress 

swamp. 

Alternative B would convert some open water to emergent wetland habitat and nourish 

12,186 acres of existing marsh habitat and 6,093 acres of swamp. Placement of dredged 

material for marsh restoration could bury aquatic resources resulting in localized 

mortality. Most fish species would likely escape the direct impacts of project 

construction. 

The restoration and creation of wetlands through the beneficial use of dredged material 

would have a positive effect on commercial and recreational fisheries. Wetlands play an 

important role in providing habitat for foraging, spawning, rearing, and cover for most 

fish species, such as spotted and sand seatrout, red drum, Atlantic croaker, and 

sheepshead. Recreational fisheries are of major importance to the local and state 

economies. 

 

Access channels would be necessary for access to marsh restoration sites, which would 

directly impact 122 acres of water bottom habitat and various wetland habitats in each of 

the subunits within the project area. Dredged material from the flotation channels would 

be side cast onto adjacent marsh resulting in direct impacts to water bottoms accessible to 

fish within the area. However, this would be offset by the creation and nourishment of 

important emergent wetlands within the project area. Access channels would be 

backfilled using the side cast material once construction was complete. Excavation of 

access channels and placement of dredged material would cause temporary local 

increases in turbidity, slight temperature increase, and DO decrease. Best management 

practices (BMPs) would be implemented to reduce areas affected by return water. 
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Borrow pits would be required to provide the necessary material for the restoration 

projects. Approximately 9,036 acres of water bottom would be directly impacted from 

creation of borrow pits and associated impacts to the water quality would be similar to 

that discussed for the flotation channels. Borrow would be taken from Lake Borgne at 

depths of ten feet, with a maximum depth of twelve feet. They may be relatively 

permanent features on the bottom in this low-energy system. However, excavation of 

borrow pits to these depths (10 feet to 12 feet) will not change the physical and 

geochemical properties as existing data indicates uniform sediment composition at these 

depths. These post-dredging lake bottoms should remain suitable for fishery resources in 

the area.

For some marsh restoration measures, retention dikes would need to be constructed to 

contain dredged material. Sediment needed for dike construction would be excavated to 

the inside of the containment cell. Approximately 3,890acres of marsh would be directly 

impacted by construction of the retention dikes. The retention dikes would be temporary 

in nature being mechanically degraded after project construction. 

Approximately 35,367 linear feet of shoreline protection would be constructed. In order 

to facilitate the movement of aquatic and fish species between open water and marsh 

habitat, fish dips would be incorporated in the final design of these features. The 

frequency and design of the fish dips would be coordinated with the USFWS and NMFS. 

Initial influxes of freshwater from diversion structures would result in reductions in 

salinity and would also result in a shift of fish species to higher salinity parts of the 

project area. Longer freshwater diversions could result in basin-scale fisheries 

displacement. However, species-specific variables, structure location, flow rates, as well 

as, environmental conditions would also control the degree to which the displacement 

may occur. Predicting these effects is difficult due to many complicated and interrelated 

factors.

The restoration of the Central Wetlands involves an alteration of the existing hydrologic 

conditions that may result in reverse tidal flow at the water control structures at Bayou 

Bienvenue and Bayou Dupre, as a result of the Violet, Louisiana Freshwater Diversion 

and the construction of 1,143 acres of retention dikes for swamp creation and 

nourishment. These impacts could potentially result in the loss or reduction in marine 

fishery productivity in the Central Wetlands, and the potential conversion of EFH to an 

area no longer supportive of federally managed marine fishery species. 

The Violet, Louisiana Freshwater Diversion would be constructed to discharge 

freshwater into the Central Wetlands, as well as, adjacent open water and wetland areas. 

The structure would be designed to discharge a minimum of 1,000 cfs with a pulsing 

capacity of 7,000 cfs. The diversion would be operated to provide freshwater during the 

months of April and May, to meet salinity targets for four out of every 10 years. This 

would decrease the salinity within the project area (including Mississippi territorial 

waters) by 0.6 ppt to 0.9 ppt. Historical data show salinity ranging in this area from 3 ppt 

to 27 ppt with the higher salinity from late summer to early fall and the lower salinity 
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from winter to late spring. Based upon salinity modeling, this change would not be 

substantial enough to affect the fisheries population within Lake Borgne and surrounding 

water bodies included within the MRGO Ecosystem Restoration Project. 

The Caernarvon Freshwater Diversion structure has the capacity to produce similar flows 

(up to 8,000 cfs) as the proposed Violet, Louisiana Freshwater Diversion. Louisiana 

Department of Wildlife and Fisheries (LDWF) conducted pre- and post-construction 

monitoring showing increased catch rates at seven of the eight sampling stations for red 

drum, sheepshead, Atlantic croaker, and Gulf menhaden once the Caernarvon Freshwater 

Diversion was operational. Only spotted sea trout showed a post-construction decrease,

which may have been caused by a severe freeze in 1989. Although spotted sea trout have 

shown decreases at the Caernarvon area sampling locations, charter boat captains have 

reported that overall catches have not been affected detrimentally, although they have 

reported displacement since the diversion has been operational. 

Based on results from the Caernarvon Freshwater Diversion, it is clear that freshwater 

diversions can have negative short-term impacts on some fisheries populations while also 

enhancing the productivity of other fisheries. Such was the case with the Caernarvon 

Freshwater Diversion reviving two fisheries (shad and largemouth bass) near the 

diversion itself.

Based upon (Bartell et al., 2010) the aquatics modeling results for alternative B and

Preliminary Hydrodynamic and Hydraulic Modeling for a Proposed Freshwater 

Diversion in the Vicinity of Violet, Louisiana (USACE, 2010), there would be no 

significant impacts to net productivity for the following modeled species: Atlantic 

croaker, red drum (juveniles and adults), spotted sea trout (juveniles and adults), stripped 

mullet, sheepshead, Gulf menhaden, and bay anchovy. 

Indirect Impacts

Indirect impacts include protection, creation, and nourishment of marsh habitat, and 

protecting habitat for aquatic resources within the project area. Shoreline protection 

features would not only prevent the erosion of interior emergent wetlands, but would also 

protect interior shallow ponds, which are essential nursery habitats for many fishery 

species. Shoreline protection features would also prevent the conversion of transitional 

wetland habitats, including inner marsh and marsh edge habitats, to less productive 

habitat categories, such as open water. Alternative B would not only increase the areal 

extent of habitat, but would also improve the quality of transitional wetland habitats used 

by fish for spawning, nursery, forage, cover, and other life requirements. Some species 

serve as prey for others; therefore, predator populations may indirectly benefit, albeit to 

an unknown extent. 

Low dissolved oxygen (DO) levels could be a potential impact during construction 

activities in Lake Borgne and continue to persist after construction. Additionally, there is 

the potential that the Violet, Louisiana Freshwater Diversion could exacerbate low DO 

conditions in Lake Borgne, due to the high level of nutrients causing algal blooms. The 
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Restoration Plan 4-70 June 2012

potential for this impact could be monitored in the future after implementation addressed 

with adaptive management. 

Lagged potential for diversions is overall enhancement of estuarine productivity, such as 

additional vegetation providing important habitat for larval fish and decomposition of 

vegetation augmenting the detrital food web. 

Cumulative Impacts

Project benefits under alternative B would be partially supplemented by the overall net 

acres created, nourished, and protected by other reasonably foreseeable future Federal, 

state, local, and private restoration efforts including: CWPPRA 33,690 acres; State 2,543 

acres; Vegetation 535 acres; Section 204/1135, Beneficial Use 226 acres; WRDA 16,000 

acres for a total of 53,009 acres. The CWPPRA PO-30 has been completed and PO-32 

Lake Borgne portion has been constructed and the MRGO portion has been proposed for 

deauthorization under CWPPRA. These projects provide shoreline protection near to or 

adjacent to feature in this plan, and would protect additional portions of the landbridge 

between Lake Borgne and the MRGO channel. Additionally, there will be a maximum 1 

to 1.4 ppt reduction in salinity in addition to the 2 ppt to 3 ppt for the no action alternative 

salinity change in Lake Borgne from May to December based upon the proposed Violet, 

Louisiana Freshwater Diversion in combination with the 4,000 cfs of the combined 

Maurepaus Swamp area diversions. The combination of these diversions is predicted to 

reduce salinity in the Mississippi Territorial Waters by 0.6 to 0.9 ppt. Alternative B 

would work synergistically with those projects to provide more complete protection for 

the land in the project area, and increased habitat resources for aquatic and fishery 

resources. 

Cumulative impacts to listed species would result from the incremental impacts of the 

anticipated restoration features, in combination with the numerous other reasonably 

foreseeable future restoration projects that would occur in southeastern Louisiana. These 

projects would slow the rate of shoreline retreat and restore some of the delicate wetland 

habitats within the area. Aquatic and fishery resources that utilize the project area would 

benefit from the effects of creating, nourishing, and protecting the wetlands. Detailed 

impacts from other state and Federal projects can be viewed in chapter 2. 

4.15.3 Alternative C - MRGO Restoration Plan 7

Direct Impacts

Alternative C is similar to alternative B with the following exceptions, an increase in the 

acreage of proposed wetland creation and linear feet of shoreline protection creating 

additional habitat to be utilized by aquatic and fishery resources within a planning 

subunit. Alternative C would include the creation/nourishment of approximately 44,188 

acres of marsh habitats and provide 314,944 linear feet of shoreline protection. 
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Restoration Plan 4-71 June 2012

Impacts from implementation of alternative C would be similar to alternative B; however, 

the quantity of impacts would be greater. Borrow pits would be required to 15,724 acres 

of water bottom. Approximately 6,924 acres of marsh would be directly impacted by 

construction of the retention dikes. Direct impacts include the loss of 1,937 acres of 

water bottom for the construction of rock breakwater structures for shoreline protection. 

Preliminary aquatics model results show direct impacts to fishery resources would be 

similar to those described under alternative B.

The restoration of the Central Wetlands involves an alteration of the existing hydrologic 

conditions that may result in reverse tidal flow at the water control structures at Bayou 

Bienvenue and Bayou Dupre, as a result of the Violet, Louisiana Freshwater Diversion 

and the construction of 1,948 acres of retention dikes for swamp creation and 

nourishment. These impacts could potentially result in the loss or reduction in marine 

fishery productivity in the Central Wetlands, and the potential conversion of EFH to an 

area no longer supportive of federally managed marine fishery species. 

Indirect Impacts

Indirect impacts associated with alternative C would be similar to those described under 

alternative B. 

Cumulative Impacts

Cumulative impacts for alternative C would be similar to those of alternative B. 

4.15.4 Alternative D - MRGO Restoration Plan 10

Direct Impacts

Alternative D is similar to alternative C with the following exceptions. There would be 

an additional 95,923 linear feet of shoreline protection, 704 acres of marsh 

creation/nourishment, and an additional 9 acres of water bottoms impacted from the use 

of retention dikes for marsh restoration under alternative D. 

Preliminary aquatics model results show direct impacts to fishery resources would be 

similar to those described under alternative B. 

The restoration of the Central Wetlands involves an alteration of the existing hydrologic 

conditions that may result in reverse tidal flow at the water control structures at Bayou 

Bienvenue and Bayou Dupre, as a result of the Violet, Louisiana Freshwater Diversion 

and the construction of 1,948 acres of retention dikes for swamp creation and 

nourishment. These impacts could potentially result in the loss or reduction in marine 

fishery productivity in the Central Wetlands, and the potential conversion of EFH to an 

area no longer supportive of federally managed marine fishery species. 
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Restoration Plan 4-72 June 2012

Indirect Impacts

Indirect impacts associated with alternative D would be similar to those described under 

alternative B.

Cumulative Impacts

Cumulative impacts for alternative D would be similar to those of alternative B. 

4.16 COMMERCIAL FISHERIES

4.16.1 Alternative A - No Action Plan

Direct Impacts 

The no action alternative would result in 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. 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 

commercial 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 and decline in commercial fish productivity. 

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 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. 

Based upon the aquatics model (Bartell et al., 2010) results and Preliminary 

Hydrodynamic and Hydraulic Modeling for a Proposed Freshwater Diversion in the 

Vicinity of Violet, Louisiana (USACE, 2010), under the no action alternative there would 

be no significant impacts to net productivity for the following modeled species from 2015 

to 2065: white shrimp (juveniles and adults), brown shrimp (juveniles and adults), as well 

as, blue crab (juveniles and adults). 

As there would be no dredging, wetland restoration, or shoreline protection construction 

activities proposed under the no action alternative, there would be no construction-related 

impacts to commercial fishery resources.
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Restoration Plan 4-73 June 2012

Indirect Impacts 

Indirect impacts would result in the persistence of existing conditions including the 

continued conversion of existing wetlands to open water habitats, continued bankline 

erosion, and sloughing of the shoreline. Wetland habitat provides important spawning, 

forage, and shelter habitat for a number of commercial fish species would be expected to 

decrease in the future. Indirect impacts to species that do not utilize the wetlands, but 

whose prey species utilize the wetlands would cause competition between resident and 

migratory fish and other aquatic species for decreasing wetland resources. The Coast 

2050 Report (LCWCRTF & WCRA, 1999) predicts that coastal wetland loss would 

impact most commercially important species, including black drum, brown and white 

shrimp, and blue crab, leading to declining abundances in the project area. 

Cumulative Impacts 

No restoration projects would be implemented under alternative A. Cumulative impacts 

to commercial fisheries would result from a combination of continued loss of habitat 

within the project area. These losses would be offset somewhat from the benefits of 

restoration activities that are anticipated to occur within or near the project vicinity such 

as: CWPPRA PO-30 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; and other wetland 

restoration efforts authorized under the LCA Plan in WRDA 2007. Features of the 

authorized HSDRRS as well as the closure structure on the MRGO channel near the 

Bayou La Loutre Ridge could affect the hydrology of the study area. The closure 

structure near Bayou La Loutre has reduced tidal exchange between Lake Borgne and 

Breton Sound, which has reduced salinity in the project area. Additionally, a 2-3 ppt 

salinity decrease is expected within Lake Borgne from freshwater diversion projects such 

as the 1,000 cfs Hope Canal / Maurepas Diversion; and the 3,000 cfs Blind/Convent 

River Diversion; all of which have been authorized under Section 7006 of the WRDA 

2007. The Convent Blind River Diversion is currently in the feasibility phase with a final 

report due in December 2010. 

Adverse cumulative impacts associated with the no action alternative would be the 

additive effect of the continued deterioration of habitat quality and quantity in the project 

area causing continued coastal land losses and deterioration of critical fish habitat along 

large areas of southeastern Louisiana and the Gulf Coast that would further stress species 

that are dependent on these habitats for all or a part of their life cycle. Negative 

cumulative impacts would be offset, to some degree, by the positive impacts of 

implementing the reasonably foreseeable future state and Federal projects as mentioned 

above. Additional state and Federal projects in the vicinity are detailed in chapter 2. 
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Restoration Plan 4-74 June 2012

4.16.2 Alternative B - MRGO Restoration Plan 2 

Direct Impacts

Direct impacts would be localized, temporary, and primarily related to construction 

activities that would make the areas unavailable to conduct commercial fishing activities. 

Following completion of construction activities, those areas would become available for 

commercial fishery activities. This alternative includes excavation of 87,000,000 cubic 

yards of material, to depths of ten feet with a maximum depth of twelve feet, from a total 

of 9,036 acres of water bottom in Lake Borgne. Placement of this material for emergent 

wetland creation and nourishment would cover approximately 19,630 acres of shallow 

open water and existing fragmented marsh. Dredging floatation access for construction 

activities would impact 122 acres of water bottoms. Material dredged for retention dikes 

would be placed over approximately 3,890 acres of shallow water bottoms and marsh. 

It is anticipated that borrow pits would have no impact on commercial fishing trawling 

equipment. Each of these species (white shrimp, brown shrimp and blue crab) follows a 

circular migration which encompasses a broad range of estuarine salinity. For instance, 

productivity for commercial harvest is incorrectly equated to higher salinity due to 

targeting late juvenile and adult stages of these species. Though higher salinity tends to 

favor higher harvest, they are not directly linked to absolute productivity. Sampling by 

LDWF confirmed significant nursery use by juvenile brown shrimp (salinity 0.3 to 5 ppt), 

juvenile white shrimp, and juvenile blue crab (both found in salinity as low as 0.2 ppt). 

LDWF also conducted pre- and post-construction sampling events for the Caernarvon 

Freshwater Diversion using trawls and seines at 21 sampling locations located throughout 

Breton Sound estuary. Post-construction sampling showed a decrease in catch per unit 

effort (CPUE) for brown shrimp, while white shrimp showed an increase in CPUE. 

CPUE data was inconclusive for blue crab. Commercial landing data collected from 

local seafood dealers yielded no detectable post-construction effect. The Caernarvon 

Freshwater Diversion has resulted in a shift of the optimal harvest zones from the interior 

marshes to more seaward marshes and waterbodies, while no significant reductions of 

either three of these species has been recorded. Similar results could be produced from 

the Violet, Louisiana Freshwater Diversion; however, they are unknown at this time. 

The restoration of the Central Wetlands involves an alteration of the existing hydrologic 

conditions that may result in reverse tidal flow at the water control structures at Bayou 

Bienvenue and Bayou Dupre, as a result of the Violet, Louisiana Freshwater Diversion 

and the construction of 1,143 acres of retention dikes for swamp creation and 

nourishment. These impacts could potentially result in the loss or reduction in marine 

fishery productivity in the Central Wetlands, and the potential conversion of EFH to an 

area no longer supportive of federally managed marine fishery species. 

Based upon (Bartell et al., 2010) aquatics modeling results and Preliminary 

Hydrodynamic and Hydraulic Modeling for a Proposed Freshwater Diversion in the 

Vicinity of Violet, Louisiana (USACE, 2010) there would be no significant impacts to the 
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Restoration Plan 4-75 June 2012

following modeled species: white shrimp (juveniles and adults), brown shrimp (juveniles 

and adults), as well as, blue crab (juveniles and adults). 

Indirect Impacts

Over the period of analysis alternative B would protect, create, and nourish transitional 

emergent wetlands providing important habitat that would support populations of 

commercially important fish species and enhance commercial fishing opportunities. 

The Caernarvon Freshwater Diversion has created low salinity marsh expanding the 

nursery habitat required for juvenile development of brown and white shrimp, as well as 

blue crab. Similar results could be produced from the Violet, Louisiana Freshwater 

Diversion; however, they are unknown at this time. 

Low dissolved oxygen (DO) levels could be a potential impact during construction 

activities in Lake Borgne and continue to persist after construction. Additionally, there is 

the potential that the Violet, Louisiana Freshwater Diversion could exacerbate low DO 

conditions in Lake Borgne, due to the high level of nutrients causing algal blooms. The 

potential for this impact could be monitored in the future after implementation addressed 

with adaptive management. 

Cumulative Impacts 

Cumulative impacts to commercial fisheries would be the result from the combination of 

continued wetland loss and habitat changes and the benefits anticipated from alternative 

B combined with other restoration efforts. Project benefits would be partially 

supplemented by the overall net acres created, nourished, and protected by other Federal, 

state, local, and private restoration efforts including: CWPPRA 33,690 acres; State 2,543 

acres; Vegetation 535 acres; Section 204/1135, Beneficial Use 226 acres; WRDA 16,000 

acres for a total of 53,009 acres. The CWPPRA PO-30 has been completed and PO-32 

Lake Borgne portion has been constructed and the MRGO portion has been proposed for 

deauthorization under CWPPRA. These projects provide shoreline protection near to or 

adjacent to feature in this plan, and would protect additional portions of the landbridge 

between Lake Borgne and the MRGO channel. 

Additionally, there will be a maximum 1 to 1.4 ppt in addition to the 2 ppt to 3 ppt for the 

no action alternative salinity change in Lake Borgne from May to December based upon 

the proposed Violet, Louisiana Freshwater Diversion in combination with the 4,000 cfs of 

the combined Maurepaus Swamp area diversions. The combination of these diversions is

predicted to reduce salinity in the Mississippi Territorial Waters by -0.6 to -0.9 ppt. 

Alternative B would work synergistically with those projects to provide more complete 

protection for the land in the project area, and increased habitat resources for aquatic and 

fishery resources. Cumulative impacts to commercial fish species would be related to the 

incremental impacts of the anticipated restoration features. The combination of this effort 

with the numerous other restoration projects occurring in southeastern Louisiana will be 

the slowing of the rate of shoreline retreat and restoring some of the delicate wetland 
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Restoration Plan 4-76 June 2012

habitats within the area. Detailed impacts from other state and Federal projects can be 

viewed in chapter 2. Commercial fish species that utilize the project area would benefit 

from the effects of creating, nourishing, and protecting the wetlands.

4.16.3 Alternative C - MRGO Restoration Plan 7

Direct Impacts

Direct impacts are similar to alternative B with 44,188 acres of marsh creation and 

314,944 linear feet for shoreline protection, which would lead to more disruption to areas 

fished by commercial fishermen. Impacts would be longer due to the fact that 

construction/dredging activities would last longer. 

The restoration of the Central Wetlands involves an alteration of the existing hydrologic 

conditions that may result in reverse tidal flow at the water control structures at Bayou 

Bienvenue and Bayou Dupre, as a result of the Violet, Louisiana Freshwater Diversion 

and the construction of 1,948 acres of retention dikes for swamp creation and 

nourishment. These impacts could potentially result in the loss or reduction in marine 

fishery productivity in the Central Wetlands, and the potential conversion of EFH to an 

area no longer supportive of federally managed marine fishery species. 

Indirect Impacts

Indirect impacts associated with alternative C would be similar to those described under 

alternative B. 

Cumulative Impacts

Cumulative impacts associated with alternative C would be similar to those described 

under alternative B. 

4.16.4 Alternative D - MRGO Restoration Plan 10

Direct Impacts

Direct impacts are similar to alternative C with an additional 704 acres of marsh creation 

and 95,623 linear feet for shoreline protection. 

The restoration of the Central Wetlands involves an alteration of the existing hydrologic 

conditions that may result in reverse tidal flow at the water control structures at Bayou 

Bienvenue and Bayou Dupre, as a result of the Violet, Louisiana Freshwater Diversion 

and the construction of 1,948 acres of retention dikes for swamp creation and 

nourishment. These impacts could potentially result in the loss or reduction in marine 

fishery productivity in the Central Wetlands, and the potential conversion of EFH to an 

area no longer supportive of federally managed marine fishery species. 
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Restoration Plan 4-77 June 2012

Indirect Impacts

Indirect impacts associated with alternative D would be similar to those described under 

alternative B. 

Cumulative Impacts

Cumulative impacts associated with alternative D would be similar to those described 

under alternative B. 

4.17 OYSTER RESOURCES

4.17.1 Alternative A - No Action Plan

Direct Impacts

Direct impacts from the no action alternative include potential reduction in salinity of two 

to three ppt based upon proposed construction of several diversion projects that would be 

expected to be implemented without the MRGO restoration including: 1,000 cfs diversion 

at the Hope Canal; and a 3,000 cfs diversion at the Blind/Convent River. The Convent 

Blind River diversion project is in the feasibility stage with a final report due in 

December 2010. Work has been initiated under CWPPRA for the Hope Canal diversion. 

Reductions of 2-3 ppt in salinity could result in a decrease of net productivity in oyster 

beds within the Lake Borgne area due to salinity being lower than target optimums. 

Dugas (1977) and Eleuterius (1977) reported that areas containing average salinities

ranging from 10 to 16 ppt support the maximum oyster production in Louisiana and 

Mississippi, respectively, resulting in a seaward shift in oyster productivity; however, the 

extent of these impacts are currently unknown. 

Reductions in salinity further east in Mississippi Territorial Waters from the proposed 

freshwater diversions mentioned above would be less than 2-3 ppt, albeit to an unknown 

extent. However, with productive oyster reefs in the Mississippi Territorial Waters 

ranging from 2-22 ppt, no impacts are anticipated to occur. 

No impacts to oyster reefs from sedimentation from these diversions are expected given 

their geographical location to one another. 

Indirect Impacts

Indirect impacts would result from the persistence of existing conditions including the 

continued conversion of existing transitional estuarine wetlands to open water habitats, as 

well as bankline erosion and sloughing of the shoreline. The continued loss of 

transitional estuarine wetlands due to sediment starvation and sea level rise would 

adversely affect the local detritus-based oyster food web. Organic detritus, derived 

mainly from vascular plants, is a major food source for estuarine consumers including 
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Restoration Plan 4-78 June 2012

oysters (Day et al., 1989). Loss of estuarine wetlands not only reduces detritus, which is 

used directly by oysters, but also reduces catabolic products (i.e., process by which 

complex substances are converted to more simple compounds) that are more often 

utilized by primary producers (e.g., phytoplankton), which can then be used by oysters 

and other species (Kilgen and Dugas, 1989). As discussed in chapter 3, oysters depend 

on estuarine wetlands for protection and food when they are juveniles. Hence, the loss of 

wetlands in the project area would likely alter the detritus-based food web of the oyster, 

thereby reducing the localized carrying capacity for oyster leases in the area. 

Based upon (Bartell et al., 2010) aquatics modeling results (see section 4.13 for 

description) and Preliminary Hydrodynamic and Hydraulic Modeling for a Proposed 

Freshwater Diversion in the Vicinity of Violet, Louisiana 

 

(USACE, 2010) there would be 

no significant impacts to oysters or oyster spat production under alternative A. 

Cumulative Impacts

Cumulative impacts include the combined effect of the no action plan together with the 

anticipated benefits of restoration activities in or near the project vicinity from reasonably 

foreseeable future projects such as: CWPPRA PO-30 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; and other wetland restoration efforts authorized under the LCA Plan in WRDA 

2007. Features of the authorized HSDRRS as well as the closure structure on the MRGO 

channel near the Bayou La Loutre Ridge could affect the hydrology of the study area. 

Additionally, a 2-3 ppt salinity decrease is expected within Lake Borgne from freshwater

diversion projects such as the 1,000 cfs Hope Canal / Maurepas Diversion; and the 3,000 

cfs Convent Blind River Diversion; all of which have been authorized under Section 

7006 of the WRDA 2007. The Convent Blind River Diversion is currently in the 

feasibility phase with a final report due in December 2010. 

The adverse incremental impacts associated with the no action alternative would include 

the continued deterioration of oyster habitat quality and quantity in the project area and 

also large areas of southeastern Louisiana and the Gulf Coast. However, reductions in 

salinity from the proposed freshwater diversion projects may result in a seaward shift in 

oyster bed productivity, albeit to an unknown extent. Negative cumulative impacts of 

wetlands loss would be offset, to some degree, by the positive impacts of implementing 

the state and Federal projects as mentioned above. Additional state and Federal projects 

in the vicinity are detailed in chapter 2. 

4.17.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

Alternative B would result in the excavation of 87 mcy of borrow material, thereby 

impacting up to 9,036 acres of water bottom. Borrow locations that would be located 
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Restoration Plan 4-79 June 2012

within historical oyster leases have been removed from restoration measures. There is 

still potential for impacts, for example, from water quality changes such as increased 

turbidity due to dredging and construction activities. The magnitude of such impacts 

remains highly uncertain. Measures to reduce impacts, such as seasonal windows and 

turbidity screens, could be employed during construction work. 

Impacts to oysters and oyster leases would be primarily associated with the dredging of 

borrow material and floatation access. These dredging related impacts to oyster leases 

located near borrow areas, as well as, flotation access channels would include increased 

turbidity, siltation, entrainment of oyster larvae during dredging operations, temperature 

changes, increased BOD due to the introduction of organic matter into water column, and 

decreased DO. Turbidity impacts as a result of dredging and construction would be 

temporary, with the anticipation that ambient water quality conditions would return once 

all activities have ceased after 10 years in the area. Isolated impacts from individual 

subprojects would be shorter in duration. However, direct impacts to the bottom habitat 

may persist for many years as the borrow footprints fill with sediment. 

Oysters found within flotation access channels would suffer major disturbance and/or 

mortality from dredging and construction. However, access channels, shoreline 

protection, borrow sites and wetland creation/nourishment sites would be designed to 

avoid oyster leases and nearby Louisiana Oyster Seed Grounds using best management 

practices. Wetland creation/nourishment sites would be constructed using retention dikes 

and silt curtains to prevent or reduce dredged slurry runoff, turbidity, and other 

construction-related impacts. 

Preliminary aquatics model results (Bartell et al., 2010) for alternative B showed 

decreases in annual net productivity (gC/m2) of oysters (based upon +/- 20 percent model 

error) at target year 2015 for east Lake Pontchartrain (Nodes 3,4,5), Golden Triangle 

(Node 9), Lake Borgne (Nodes 1, 2, 9) and Inner Biloxi (Nodes 8, 73). These areas id 

not historically support oyster reefs prior to the construction of the MRGO (LDWF – 

Dugas, 1979). Additional decreases were predicted within the Golden Triangle at target 

year 2040, and Lake Borgne at target year 2065. Upper Lake Borgne (Node 1) and Inner 

Biloxi (Nodes 8, 73) model results show decreases based upon oyster spat modeling 

across all of the target years. However, oyster monthly productivity (metric tons/km2

) 

shows a decrease in productivity would be caused by the Violet, Louisiana Freshwater

Diversion during the months of August and September. When integrated over the entire 

modeled area and project planning horizon, the preliminary aquatics modeling results and 

associated model uncertainties indicate an average 5 percent reduction in oyster 

production and 6 percent reduction in oyster spat production. These potential impacts 

could be interpreted as insignificant impact, given the uncertainties associated with the 

aquatics and UNO models. 

Pre- and post-construction monitoring of the Caernarvon Freshwater Diversion by LDWF 

biologists at 41 stations within the Breton Sound estuary are similar to the aquatics 

modeling results run for the Violet, Louisiana Freshwater Diversion. They are also 

similar to what has happened to oysters at interior stations (closer to the diversion) likely 
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due to extended periods of reduced salinity lower than 5 ppt. However, outward 

migration of the optimal production zone has revived beds that had become dormant due 

to excessive salinity. Oyster production had increased dramatically in the first three years 

of the Caernarvon Freshwater Diversion according to dockside surveys with fishermen. 

A more seaward shift in productivity as a result of the Caernarvon Freshwater Diversion 

was predicted in the 1984 EIS. Similar results could be produced from the Violet, 

Louisiana Freshwater Diversion; however, they are unknown at this time. 

Information taken from the Preliminary Hydrodynamic and Hydraulic Modeling for a 

Proposed Freshwater Diversion in the Vicinity of Violet, Louisiana (USACE, 2010) 

indicates a maximum reduction in salinity of 1.0 ppt to 1.4 ppt in Lake Borgne from May 

to December based on the proposed diversion base flow of 1,000 cfs and a peak diversion 

flow of 7,000 cfs. Salinity in the Mississippi Territorial Waters is predicted to be reduced 

by 0.6 ppt to 0.9 ppt under the combined influence of the 1,000 cfs Violet Freshwater

Diversion with 7,000 cfs pulse and the 4,500 cfs of the combined Maurepas Swamp Area 

diversions. Adult oysters can tolerate salinity from 0 to 42 ppt with an optimal range of 

14 ppt to 28 ppt (EOBRT, 2007). Waters with lower salinity fail to support biological 

function, while more saline waters promote disease and predation. Oysters grow faster in 

areas with fluctuating salinity within their normal ranges compared to constant salinity 

(Pierce and Conover, 1954). Within Mississippi sound productive oyster reefs range 

from 2 ppt to 22 ppt (Eleuterius, 1977). No impacts would be anticipated to occur to 

oyster leases from the diversion caused by sedimentation or such slight changes in 

salinity within the Lake Borgne area as well as the entire project area. 

Indirect Impacts

Indirect impacts to oyster resources from alternative B would include the creation of 

additional wetland habitat and a reduction in shoreline erosion. During the period of 

analysis, alternative B would create and nourish a net total of 19,630 acres of emergent 

wetlands that would provide protection and food resources (nutrients and detritus) for 

oyster resources in the area. Plankton productivity would increase along with the 

production of organic matter through decomposition processes. The resulting dissolved 

organic matter can be utilized directly by primary producers and subsequently used by 

oysters (Kilgen and Dugas, 1989). Alternative B would also provide 35,367 linear feet of 

shoreline protection to prevent erosion of emergent marsh shoreline thereby indirectly 

benefitting oysters. 

 

Oyster natural predators include, oyster drill (Thais haemastoma), blue crab, stone crab, 

and black drum (Pogonias cromis). Based upon (Bartell et al., 2010) preliminary 

aquatics model results and Preliminary Hydrodynamic and Hydraulic Modeling for a 

Proposed Freshwater Diversion in the Vicinity of Violet, Louisiana (USACE, 2010) it 

appears that there would be no impacts to oysters natural predators. However, it must be 

emphasized that given the uncertainties associated with the hydrodynamic and hydraulic 

modeling, the preliminary aquatics model results could be fairly interpreted as no 

significant impacts on the resources of interest. There would be insignificant impacts to 

blue crab (juveniles and adults). 
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When the Caernarvon Freshwater Diversion became operational, LDWF data indicates 

that approximately 8,200 oyster leases were held in coastal Louisiana. Most of these 

leases were within the interior marshes of the Breton Sound estuary, and most public 

grounds were on the outside. These outside reefs are public (owned by LDWF) and 

provide an important source of juvenile “seed” oysters throughout southeast Louisiana. 

LDWF post-diversion monitoring has shown increased seed production on public oyster 

reefs, as well as, a shift in oyster fishermen becoming more reliant on public oyster seed 

grounds. Similar results could be produced from the Violet, Louisiana Freshwater 

Diversion; however, they are unknown at this time. 

Low dissolved oxygen (DO) levels could be a potential impact during construction 

activities in Lake Borgne and continue to persist after construction. Additionally, there is 

the potential that the Violet, Louisiana Freshwater Diversion could exacerbate low DO 

conditions in Lake Borgne, due to the high level of nutrients causing algal blooms. The 

potential for this impact could be monitored in the future after implementation addressed 

with adaptive management. 

Cumulative Impacts

Cumulative impacts include the combined effect of Alternative B together with the 

anticipated benefits of restoration activities in or near the project vicinity from reasonably 

foreseeable future projects such as: CWPPRA PO-30 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; and other wetland restoration efforts authorized under the LCA Plan in WRDA 

2007. Features of the authorized HSDRRS as well as the closure structure on the MRGO 

channel near the Bayou La Loutre Ridge could affect the hydrology of the study area. 

Additionally, a 2-3 ppt salinity decrease is expected within Lake Borgne from freshwater 

diversion projects such as the 1,000 cfs Hope Canal / Maurepas Diversion; and the 3,000 

cfs Convent Blind River Diversion; all of which have been authorized under Section 

7006 of the WRDA 2007. The Convent Blind River Diversion is currently in the 

feasibility phase with a final report due in December 2010. 

The incremental beneficial impacts associated with alternative B would offset the 

continued deterioration of oyster habitat quality and quantity in the project area and along 

large areas of southeastern Louisiana and the Gulf Coast. However, reductions in salinity 

from the proposed freshwater diversion projects may result in a seaward shift in oyster 

bed productivity, albeit to an unknown extent. In addition, negative cumulative impacts 

of wetlands loss would be offset, to some degree, by the positive impacts of 

implementing the state and Federal projects as mentioned above. Additional state and 

Federal projects in the vicinity are detailed in chapter 2. 
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4.17.3 Alternative C - MRGO Restoration Plan 7

Direct Impacts

Impacts are similar to alternative B with an additional 24,558 acres of emergent marsh 

created/nourished, as well as, an additional 279,577 linear feet of shoreline protection. 

Additional wetland nourishment/creation and shoreline protection features would include 

additional dredging disturbing more water bottom causing increased turbidity, 

temperature, and BOD and decreased DO. 

Indirect Impacts

Indirect impacts associated with alternative C would be similar to those described under 

alternative B. 

Cumulative Impacts

Cumulative impacts associated with alternative C would be similar to those described 

under alternative B. 

4.17.4 Alternative D - MRGO Restoration Plan 10

Direct Impacts

Impacts are similar to alternative C with additional 704 acres of emergent marsh 

created/nourished, as well as, an additional 95,623 linear feet of shoreline protection. 

Additional wetland nourishment/creation and shoreline protection features would include 

additional dredging disturbing more water bottoms causing increased turbidity, 

temperature, and BOD and decreased DO. 

 

Indirect Impacts

Indirect impacts associated with alternative D would be similar to those described under 

alternative B. 

Cumulative Impacts

Cumulative impacts associated with alternative D would be similar to those described 

under alternative B. 

 
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4.18 WATER BOTTOMS AND BENTHIC RESOURCES

4.18.1 Alternative A - No Action Plan

Direct Impacts

The no action alternative, by not implementing shoreline protection and wetland 

creation/nourishment, would have no direct impacts on water bottoms and benthic 

resources. 

Indirect Impacts

Indirect impacts of not implementing proposed action restoration measures would result 

in persistence of existing conditions, including the loss of existing emergent wetlands as 

they convert to open water. As a result of the change in habitat type, benthic 

communities are anticipated to change. Other indirect impacts include decreasing 

availability of nutrients and detritus, as well as, and a conversion of primarily estuarine 

benthic species to more marine open water species. 

Cumulative Impacts

Under the no action alternative, dredging impacts for borrow would not occur in Lake 

Borgne and, as a result, alternative A would not contribute to direct cumulative impacts 

on water bottoms and benthic resources. However, under alternative A, water bottom and 

benthic resources associated with wetland habitat would continue to deteriorate into the 

future. These negative impacts would be offset somewhat by benefits of other reasonably 

foreseeable future restoration activities that would be implemented in or near the project 

vicinity such as: CWPPRA PO-30 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; and 

other wetland restoration efforts authorized under the LCA Plan in WRDA 2007. 

Features of the authorized HSDRRS as well as the closure structure on the MRGO 

channel near the Bayou La Loutre Ridge could affect the hydrology of the study area. 

The closure structure near Bayou La Loutre has reduced tidal exchange between Lake 

Borgne and Breton Sound, which has reduced salinity in the project area. Additionally, a 

2-3 ppt salinity decrease is expected within Lake Borgne from freshwater diversion 

projects such as the, 1,000 cfs Hope Canal / Maurepas Diversion; and the 3,000 cfs 

Blind/Convent River Diversion; all of which have been authorized under Section 7006 of 

the WRDA 2007. The Blind/Convent River Diversion is currently in the feasibility phase 

with final reports expected in December 2010. 

Adverse cumulative impacts associated with the no action alternative would include 

continued deterioration of habitat quality and quantity in the project area causing 

continued coastal land losses and deterioration of critical habitats along large areas of 

southeastern Louisiana and the Gulf Coast would further stress benthic species dependent 
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Restoration Plan 4-84 June 2012

on these habitats for all or a part of their life cycle. Negative cumulative impacts would 

be offset, to some degree, by the positive impacts of implementing the state and Federal 

projects as mentioned above. Additional state and Federal projects in the vicinity are 

detailed in chapter 2. 

Under the no action alternative, preliminary aquatics modeling results from (Bartell et al., 

2010) shows a slight increase of annual net productivity due to the Violet, Louisiana

Freshwater Diversion for benthic species (gC/m2) in east Lake Pontchartrain (Nodes 3, 4, 

5) at target years 2015 and 2065 and Lake Borgne (Nodes 2 and 9) at target year 2015. 

More details for the aquatics modeling can be found within appendix I. 

4.18.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

This alternative includes excavation of 87 mcy of material, to depths of 10 feet with a 

maximum depth of 12 feet, from a total of 9,036 acres of water bottom. Placement of this 

material for emergent wetland creation and nourishment would cover approximately 

19,630 acres of shallow open water and existing fragmented marsh, as well as 10,318 

acres for swamp creation and nourishment. Placement of rock for shoreline protection 

features would cover 122 acres (35,367 linear feet). Material dredged for retention dikes 

and earthen weirs would be placed over approximately 5,611 acres of shallow water 

bottoms and marsh. 

Effects of implementing alternative B would be related primarily to localized and 

temporary disturbance of water bottoms during placement of shoreline protection features 

and also during dredging and placement of borrow materials. Direct impacts to the 

benthic community would include removal and entrainment with the dredged sediment. 

Additional disturbance to benthic species would likely occur from increased turbidity, 

temperature, and BOD and decreased DO due to hydraulic dredging, marsh creation, and 

placement of shoreline protection activities. Some smothering of benthic organisms 

could also occur from the sedimentation of the dredge plume, but these potential impacts 

could be minimized through the use of BMPs to minimize dredging impacts. Once 

construction is completed it is anticipated that water quality would return to preconstruction conditions. 

These actions would directly impact benthic organisms within the proposed borrow areas, 

flotation access channels, wetland creation, and shoreline protection footprints by directly 

removing them along with the sediment as well as burying benthos within the placement 

sites. Other direct impacts to the benthos would be localized and confined to 

construction areas. 

Dredging sediment would have a significant and immediate negative impact on the local 

benthic community. The primary direct effect would be the removal of sediment and 

entrainment of the infauna and epifauna that reside within and on the sediment. Because 

the majority of the benthos live in the upper 15 cm (6 in) of sediment, dredging to a depth 
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Restoration Plan 4-85 June 2012

of approximately 10 feet to 12 feet would result in a significant decrease in the 

abundance, biomass, and number of species of benthic organisms in the immediate area 

of the dredge footprint. It is expected that there would be a negligible impact on the 

regional benthic ecosystem because; (1) the benthic assemblages within the borrow sites 

are not unique and similar to assemblages in adjacent areas, and (2) the spatial extent of 

the dredged area is small compared to the broad area of the nearshore coastal 

environment. 

Existing boring data from Lake Borgne indicates that the sediment composition is 

relatively uniform over the proposed dredging depth (10 feet to 12 feet). Therefore, 

changes in the physical and geochemical properties of the pre- and post-dredging lake 

bottom should be negligible. Anaerobic sediment will be exposed after dredging is 

completed. The post-dredging lake bottom should remain suitable for burrowing, 

feeding, and larval settlement of the benthos. 

Because of the dynamic nature of benthic communities and their variability over time, the 

recolonization and recovery of the dredged areas can proceed at various rates. In 

addition, dredging activities will take place over a period of time and therefore, dredged 

areas will be in various stages of recovery. Dependent of the time of year, benthos can 

recolonize the dredged area in varying degrees via larval recruitment as well as from 

immigration of adults from adjacent, undisturbed areas. Benthic abundances and total 

species numbers may reach predredge ranges relatively quickly (within several months to 

a year); however, it may take several years before the benthic community recovers to its 

predredge levels of community composition and biomass. 

In the early stages of recovery of the benthic community, there could be shifts in the 

dominant species in the dredged areas. There are species with life history characteristics, 

such as multiple reproductive events per year that allow them to rapidly recolonize 

unoccupied space. These opportunistic species are adapted to exploit suitable habitat 

when it becomes available. 

The timing of dredging would be important factor in determining the eventual recovery 

of the dredged area because many benthic species have distinct reproductive and 

recruitment periods. Recovery would be primarily from larval recruitment and adult 

immigration for adjacent undisturbed areas. 

There would be additional direct impacts on benthos from dredging activities. Settlement 

of sediment from the turbidity plumes created by the dredging operation would bury 

benthos outside the dredging footprint. The extent and the thickness of the sediment is 

dependent on the grain size of the sediment as well as the hydrodynamic conditions 

within the project area. Mobile benthic species are able to burrow through deposited 

sediment, while more sedentary species may be suffocated. 

Preliminary aquatics modeling results from (Bartell et al., 2010) the revised model 

showed a slight increase of annual net productivity for benthic species (gC/m2

) in east 

Lake Pontchartrain (Nodes 3, 4, 5) at target years 2020 and other modeled years (e.g., 
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Restoration Plan 4-86 June 2012

2014, 2017, 2025). Increases in benthic species resulted for Lake Borgne (Nodes 2, 9) in 

the same years. Benthic production increased in nearly all of the modeled years for the 

Golden Triangle (Node 9). Across the entire project monthly benthic productivity would 

be higher in the month of September within the Lake Borgne and Biloxi Marsh. 

Uncertainties associated with the preliminary aquatics modeling results are on the order 

of ~+/-20 percent. Therefore, the minimal increases and decreases in modeled benthic 

productivity could be reasonably interpreted as no adverse impact. 

Indirect Impacts

Dredging activities would cause temporary habitat degradation to existing benthic 

habitats and species with various life requirements. However, these impacts would be 

temporary and benthos would likely re-colonize areas disturbed from dredging activities. 

Actions taken to reduce potential impacts during construction could include use of 

retention dikes to minimize runoff and overland flow, as well as reduced sediment 

movement and erosion into adjacent waterways and marshes, except were restoration and 

nourishment activities are desired. These actions could also help to minimize increases in 

turbidity and suspended particulates and restrict such impacts to the immediate 

construction area. 

Low dissolved oxygen (DO) levels could be a potential impact during construction 

activities in Lake Borgne and continue to persist after construction. Additionally, there is 

the potential that the Violet, Louisiana Freshwater Diversion could exacerbate low DO 

conditions in Lake Borgne, due to the high level of nutrients causing algal blooms. The 

potential for this impact could be monitored in the future after implementation addressed 

with adaptive management. 

Wetland habitats protected, created, and nourished by alternative B would indirectly 

benefit benthic resources by increasing dissolved organic compounds and detritus that 

would in turn provide food resources for benthic organisms. This would eventually 

increase local epifauna (such as oysters), which would indirectly help reduce turbidity, 

regenerate ammonia and phosphorus, and provide food sources for birds, fish, and people 

(Day et al., 1989). 

Cumulative Impacts

The incremental impacts to water bottoms and benthic resources described above would 

contribute to the overall cumulative impacts to these resources from other activities in the 

project area, such as dredging projects, infrastructure projects, and continuing wetland 

habitat deterioration. Impacts to benthic resources would result from the removal of 

sediment, as well as the placement of material on water bottoms. The cumulative impacts 

would be offset somewhat by project benefits derived by anticipated Federal, state, local, 

and private restoration efforts including: CWPPRA 33,690 acres; State 2,543 acres; 

Vegetation 535 acres; Section 204/1135, Beneficial Use 226 acres; WRDA 16,000 acres 

for a total of 53,009 acres. 
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The CWPPRA PO-30 has been completed and PO-32 Lake Borgne portion has been 

constructed and the MRGO portion has been proposed for deauthorization under 

CWPPRA. These projects provide shoreline protection near to or adjacent to feature in 

this plan, and would protect additional portions of the landbridge between Lake Borgne 

and the MRGO channel. Additionally, there will be a maximum 1-1.4 ppt salinity 

reduction in addition to the 2-3 ppt salinity change for the no action alternative in Lake 

Borgne from May to December based upon the proposed Violet, Louisiana Freshwater 

Diversion in combination with the 4,500 cfs of the combined Maurepaus Swamp area 

diversions. Together, these diversions are predicted to reduce salinity in the Mississippi 

Territorial Waters by -0.6 to -0.9 ppt. Alternative B would work synergistically with 

those projects that are reasonably foreseeable to occur to provide greater habitat quality

for benthic resources in the area. The combination of these efforts will result in the 

slowing of the rate of shoreline retreat and restoration of wetland benthic habitats within 

the area. Detailed impacts from other state and Federal projects can be viewed in 

chapter 2. Alternative B would contribute to those projects and provide more complete 

protection of marsh habitat that would preserve these resources in the project area. 

4.18.3 Alternative C - MRGO Restoration Plan 7

Direct Impacts

Direct impacts for this alternative would be similar to those described for alternative B, 

with the following exceptions. Alternative C includes the excavation of 152 mcy of 

material from 15,724 acres of water bottom in Lake Borgne to depths of 10 feet, with a 

maximum depth of 12 feet. Placement of this material for emergent wetland creation and 

nourishment would cover approximately 44,188 acres of shallow open water and existing 

fragmented marsh. Placement of rock for shoreline protection features and dredging 

floatation access for construction activities would impact 1,937 acres (314,944 linear 

feet) of water bottoms. Of these potential impacts, 1,705 acres of impacted water 

bottoms are located in Lake Borgne, which is designated as critical habitat for Gulf 

sturgeon. Approximately 382 acres of impact would be permanent impacts from 

construction of the rock shoreline protection. The remaining 1,323 acres would be 

temporary construction related impacts from flotation channel excavation and placement 

and access corridors. Material dredged for retention dikes and earthen weirs would be 

placed over approximately 10,048 acres of shallow water bottoms and marsh. As a result 

of the additional dredging requirements and placement acreages, more benthic habitat and 

water bottom would be directly impacted. Construction-related impacts would be longer 

as the dredging activities would be increased. 

Impacts to benthic resources from the Violet, Louisiana Freshwater Diversion would be 

the same for alternative C as they are for alternative B. 

Indirect Impacts

Indirect impacts associated with alternative C would be similar to those described under 

alternative B. 
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Cumulative Impacts

Cumulative impacts associated with alternative C would be similar to those described 

under alternative B. 

4.18.4 Alternative D - MRGO Restoration Plan 10

Direct Impacts

Direct impacts for this alternative would be similar to those described in alternative B, 

with the following exceptions. Alternative D uses 154.3 mcy of borrow material from 

15,724 acres of water bottoms in Lake Borgne. Placement of this material for emergent 

wetland creation and nourishment would cover approximately 44,892 acres of shallow 

open water and existing fragmented marsh. Placement of rock for shoreline protection 

would impact 2,494 acres (410,567 linear feet). Of these potential impacts, 1,705 acres 

of impacted water bottoms are located in Lake Borgne, which is designated as critical 

habitat for Gulf sturgeon. Approximately 382 acres of impact would be permanent 

impacts from construction of the rock shoreline protection. The remaining 1,323 acres 

would be temporary construction related impacts from flotation channel excavation and 

placement and access corridors. Material dredged for retention dikes and earthen weirs 

would be placed over approximately 10,057 acres of shallow water bottoms and marsh. 

Impacts to benthic resources from the Violet, Louisiana Freshwater Diversion would be 

the same for alternative D as they are for alternative B. 

Indirect Impacts

Indirect impacts associated with alternative D would be similar to those described under 

alternative B. 

Cumulative Impacts

Cumulative impacts associated with alternative D would be similar to those described 

under alternative B. 

4.19 PLANKTON RESOURCES

4.19.1 Alternative A - No Action Plan 

Direct Impacts

The no action alternative would result in no direct adverse impacts on plankton resources. 

Marsh habitat would continue to be restored through other restoration projects and 

programs such as CWPPRA, CIAP, and LCA that would benefit plankton resources; 

however, these would not be as beneficial at a magnitude which would completely restore 
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Restoration Plan 4-89 June 2012

natural processes and features vital to the long-term success of the watershed. The no 

action alternative would result in the continued degradation and eventual loss of 

wetlands. 

Without the freshwater diversion and the proposed engineering measures, saltwater 

intrusion would continue in the project area. With the continued increase in salinity, the 

plankton community would begin to transition to a more marine-dominated community 

as estuarine wetlands continue to degrade with sea level rise and subsidence.

Indirect Impacts

The indirect impact of not implementing wetlands creation/nourishment and shoreline 

protection features would result in the continuing loss of wetlands. This loss of wetlands 

would result in a decrease of available nutrients and detritus, which could lead to the 

alteration of the distribution and abundance estuarine-dependent plankton species. 

Cumulative Impacts

Because there are no restoration projects proposed under alternative A the no action 

alternative would not contribute incrementally to the cumulative impacts on plankton 

resources. Reasonably foreseeable restoration projects would be expected to positively 

benefit resources through improvement in water quality. 

4.19.2 Alternative B - MRGO Restoration Plan 2

Alternative B incorporates all marsh restoration/creation and shoreline protection 

measures proposed for implementation under this alternative. These discussions detail 

both negative and positive impacts of restoration measures as they pertain to 

redistribution of the plankton resources due primarily to changes in area salinity. 

Salinity appears to be one of the main controlling factors of zooplankton diversity. The 

introduction of freshwater through diversion sites could alter the community composition 

and distribution of zooplankton in the project area. While some zooplankton is

euryhaline, others have distinct salinity preferences (Day et al., 1989). 

Freshwater introduced from the Mississippi River would provide an influx of colder, 

nutrient-laden water that would spread through the Central Wetlands area and lower Lake 

Borgne ecosystem. Zooplankton peaks in the area east of the Mississippi River have 

been recorded in May, when the average temperature was 54o

F and the average salinity 

was 17.0 ppt (Perret et al., 1971). Maximum flow from the Violet, Louisiana Freshwater 

Diversion would be approximately 7,000 cfs during the months of April and May, which 

would be capable of reducing salinity within the Biloxi Marsh by 2 ppt to 3 ppt in May 

(on average) (2010, draft summary document, USACE). 
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Direct Impacts

The proposed release of river water through the Violet, Louisiana Freshwater Diversion 

channel and into the Lake Borgne and Biloxi Marsh ecosystems would result in a greater 

reduction of ambient salinity in the adjacent Lake Borgne region than in the more distant 

Biloxi Marsh. There appears to be no compelling evidence that changes in water quality

would be sufficiently adverse in the overall restoration of the Biloxi Marsh and Lake 

Borgne ecosystem and therefore have an effect on plankton within these ecosystems 

(Corps Salinity Working Group, 2010). Projected salinity changes of 2 ppt to 3 ppt 

resulting from maximum diversion flows would have only minor temporal and spatial 

effect on plankton in Lake Borgne and little to no impact in the Biloxi Marsh. Plankton 

species that are primarily eurythermal and euryhaline would not likely be impacted by the 

higher flows and resulting low salinity changes. The initial introduction of river water 

into estuarine systems may have dramatic short-term impacts on plankton populations in 

adjacent coastal waters (Hawes and Perry, 1978).

The results of the aquatics model adapted to assess the ecological effects of the proposed 

freshwater diversion on the plankton community indicated the natural year-to-year 

variations in the systemic environmental parameters (i.e., water temperature, nutrient 

input, etc.) of the project area would be more responsible for the changes in net 

productivity than any changes resulting from the influx of water from the diversion. The 

findings of the aquatics modeling indicate that there would be no adverse impact on 

plankton productivity in the project vicinity. 

Indirect Impacts

With only minor projected salinity changes in Lake Borgne, only slight water quality 

changes projected in the Biloxi marsh area and the well-flushed nature of the Lake 

Borgne and Biloxi marsh systems, no substantial indirect impacts would be anticipated 

from the influx of freshwater. 

Cumulative Impacts

The cumulative impacts would result from the synergistic effects of the existing and 

proposed diversion projects in the study area combined with the freshwater influx from 

Violet, Louisiana Freshwater Diversion along with the added effects of the engineering 

measures proposed for this alternative. Due to the very small fluctuation in salinity, no 

substantial cumulative impact would be anticipated in the Mississippi Territorial Waters. 

4.19.3 Alternative C - MRGO Restoration Plan 7

Similar to alternative B, this alternative includes a freshwater diversion; however, this 

alternative includes restoration and creation measures not identified in alternative B. The 

type of restoration measures between alternative C and alternative B are essentially the 

same with the difference being an increase in the acreage created and linear feet of 
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shoreline protected proposed within a planning subunit. As a result, the potential impacts 

to plankton would be expected to be similar to those described under alternative B. 

Direct Impacts

The direct impacts of the implementation of this alternative would be additional habitat 

and food sources for plankton provided through the increased emergent and submerged 

vegetation established in the marsh creation and restoration acreage. Increased nutrients 

and detritus flushed from marsh areas into open water by diversion flows would provide 

additional food sources for phyto and zoo-plankton. 

Indirect Impacts

With only minor projected salinity changes in Lake Borgne and the well flushed nature of 

the Lake Borgne system, no substantial indirect impacts would be anticipated from the 

influx of freshwater. Additionally, with little to no salinity change projected in the Biloxi 

marsh ecosystem, no substantial indirect impacts would be anticipated from the influx of 

freshwater.

Cumulative Impacts

Cumulative impacts from implementation of alternative C would be similar to the 

impacts of alternative B. The cumulative impacts would result from the synergistic 

effects of the existing and proposed diversion projects in the study area combined with 

the freshwater influx from Violet, Louisiana Freshwater Diversion along with the added 

effects of the engineering measures proposed for this alternative. Due to the very small 

fluctuation in salinity, no substantial cumulative impact would be anticipated in the 

Mississippi Territorial Waters. 

4.19.4 Alternative D - MRGO Restoration Plan 10

Alternative D incorporates all restoration measures under consideration for this 

alternative. The impacts of restoration measures would be directly related to possible 

redistribution of the plankton resources due primarily to changes in area hydrology. 

Alternative D is similar to the other action alternatives with the addition of restoration 

measures not identified in alternative C. The restoration measures identified for 

alternative C and alternative D are essentially the same with the difference being 

increases in wetland acreage that would be created and linear feet of shoreline protection 

within a planning subunit. In addition to the measures proposed in alternative C, this 

alternative includes 704 acres of additional wetland restoration and wetland nourishment, 

as well as 95,623 linear feet of shoreline protection measures. 
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Direct Impacts

The direct impacts of implementation of alternative D would be similar to alternative B 

and alternative C. The minor changes in salinity (-0.6 ppt to -1.4 ppt) projected would 

not be anticipated to have a substantial effect on the distribution of plankton species in 

Lake Borgne or the Biloxi marshes.

Indirect Impacts

With only minor projected salinity changes in Lake Borgne and the well flushed nature of 

the Lake Borgne system, no substantial indirect impacts would be anticipated from the 

influx of freshwater. Additionally, with little to no salinity change projected in the Biloxi 

marsh ecosystem, no substantial indirect impacts would be anticipated from the influx of 

freshwater.

Cumulative Impacts

Cumulative impacts from implementation of alternative D would be similar to the 

impacts of alternatives B and C The cumulative impacts would result from the 

synergistic effects of all the existing and proposed diversion projects in the study area 

combined with the freshwater influx from Violet, Louisiana Freshwater Diversion along 

with the added effects of the engineering measures proposed for this alternative. Due to 

the very small fluctuation in salinity, no substantial cumulative impact is anticipated in 

the Mississippi Territorial Waters. 

4.20 ESSENTIAL FISH HABITAT

4.20.1 Alternative A - No Action Plan

Direct Impacts

The no action plan would result in the persistence of existing conditions, including; 

wetland fragmentation and emergent wetland loss, as well as shoreline and bankline 

erosion. These conditions would contribute to the continued degradation of EFH for 

species utilizing these habitats such as larvae and juvenile brown shrimp, juvenile white 

shrimp, all life stages of red drum, and juvenile dog snapper. Under the no action 

alternative, no changes would be anticipated to EFH for Gulf stone crab, and adult brown 

shrimp or marine pelagic species such as; king and Spanish mackerel, cobia, bonnethead, 

and Atlantic sharpnose shark. 

Under the no action alternative, estuarine emergent wetlands and submerged aquatic 

vegetation would substantially decrease due to the continued lack of sediment input and 

SLR. These areas would convert to open water marine environments and reduce the 

area’s ability to adequately support larvae and juvenile brown shrimp, juvenile white 

shrimp, all life stages of red drum, larvae lane snapper, as well as juvenile dog snapper. 
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These habitat changes would shift predator/prey relationships and decrease fish 

productivity for species utilizing these habitats, which would reduce recreational and 

commercial fishing opportunities. 

No impacts would be anticipated under the no action alternative for adult brown shrimp, 

Gulf stone crab, dwarf sand perch, Spanish and king mackerel, cobia, bonnethead shark, 

and Atlantic sharpnose shark, all of which use marine environments (table 3-23). Other 

important marine EFH occurring within the project vicinity such as non-vegetated 

bottoms, water column, and vegetated bottoms would not be impacted. 

Aquatics modeling was used to assess changes in fisheries productivity (see section 4.13

for CASM description). Preliminary aquatics modeling results (Bartell et al., 2010) show 

no significant impacts to Federally-managed species under the no action alternative. 

Indirect Impacts

Continued degradation and loss of wetlands, especially transitional habitat between 

estuarine and marine environments (used for spawning, foraging, cover, nursery, and 

other life requirements), would also result in the degradation and loss of important EFH 

such as; inner marsh and marsh edge, estuarine water column, and mud, sand, shell, 

substrates. The distribution and abundance of aquatic organisms would decrease, 

indirectly impacting other species linked in the food web to directly affected species. 

Cumulative Impacts

Cumulative impacts to EFH would result from the combination of wetland loss and 

conversion of water bottoms. Without habitat restoration under alternative A, habitat 

losses would continue and EFH would be impacted. EFH impacts would be partially 

offset through the benefits of restoration activities in or near the project vicinity such as: 

CWPPRA PO-30 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 (NonContinuous), St. Bernard Parish, LA (07-C-0089) project; and other wetland restoration 

efforts authorized under the LCA Plan in WRDA 2007. Features of the authorized 

HSDRRS as well as the closure structure on the MRGO channel near the Bayou La 

Loutre Ridge could affect the hydrology of the study area. The closure structure near 

Bayou La Loutre has reduced tidal exchange between Lake Borgne and Breton Sound, 

which has reduced salinity in the project area. Additionally, a 2-3 ppt salinity decrease is 

expected within Lake Borgne from freshwater diversion projects such as the, 1,000 cfs 

Hope Canal Diversion; and the 3,000 cfs Blind/Convent River Diversion; all of which 

have been authorized under Section 7006 of the WRDA 2007. The Blind/Convent River 

Diversion is currently in the feasibility phase with final reports expected in December 

2010. 

Adverse impacts to EFH associated with the no action alternative would be the continued 

deterioration of habitat quality and quantity in the project area. This habitat deterioration 
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of critical habitats along large areas of southeastern Louisiana and the Gulf Coast will 

further impact Federally-managed species dependent on these habitats for all or a part of 

their life cycle. Negative impacts would be offset, to some degree, by the positive 

impacts of implementing the state and Federal projects as mentioned above. Additional 

state and Federal projects in the vicinity are detailed in chapter 2. The LCA Study 

(USACE, 2004) estimated a net loss of 328,000 acres of coastal wetland habitats may 

occur by 2050, which is nearly 10 percent of Louisiana's remaining coastal wetlands. As 

described previously, these habitats provide EFH to several species within the project 

area. 

4.20.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

Implementation of alternative B would convert 7,444 acres of shallow open water to 

wetlands and nourish 12,186 acres of marsh to create a more continuous emergent 

transitional wetland habitat. This habitat would provide grounds for spawning, nursing, 

foraging, cover, as well as various other life requirements important to Federally 

managed species within the MRGO Ecosystem Restoration project area. An increase in 

vegetation and productivity would also reduce competition between resident and 

migratory fish species for limited resources. 

Placement of rock for shoreline protection and dredged material for retention dikes would 

directly impact 35,367 linear feet and 122 acres of existing EFH, respectively, making it 

unavailable to fisheries species. However, the loss of EFH would be offset by the 

increase in the quality of EFH by the newly created and nourished emergent wetland 

habitat. It is important to note that retention dikes will degrade once construction is 

complete; thereby, rendering the habitat once again available for fisheries species. 

During construction activities it is anticipated fish species would temporarily avoid the 

immediate area. 

Access channels necessary for marsh restoration sites would directly impact water bottom 

and various wetland habitats that are EFH to a number of Federally managed species. 

Dredged material from the flotation channels would be sidecast on adjacent marsh, 

causing temporary localized increases in turbidity, slight temperature increase and BOD, 

and DO decrease. Material dredged would be used beneficially for important emergent 

wetland nourishment and creation. BMPs would be used to reduce disturbances to EFH 

and fish mortality during construction including use of silt curtains and retention dikes to 

minimize runoff and overland flow, as well as reduced sediment movement and erosion 

into adjacent waterways and marshes, except were restoration and nourishment activities 

are desired. These actions could also help to minimize increases in turbidity and 

suspended particulates and restrict such impacts to the immediate construction area. 

The Violet, Louisiana Freshwater Diversion would be constructed to discharge 

freshwater into the Central Wetlands, as well as, adjacent open water and wetland areas. 

The structure would be designed to discharge a minimum of 1,000 cfs and a maximum of 
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7,000 cfs. The diversion would be operated to provide freshwater during the months of 

April and May, for 4 out of 10 years. This would decrease the salinity within the project 

area (including Mississippi territorial waters) from 0.6 ppt to 0.9 ppt. Historical data 

show salinity ranging in this area from 3 ppt to 27 ppt with the higher salinity from late 

summer to early fall and lower salinity from winter to late spring. Based upon salinity 

modeling, the salinity change from the Violet, Louisiana Freshwater Diversion would not 

be substantial enough to affect the fisheries population or EFH within this given area. 

With minor changes in the salinity levels (0.6 ppt to 1.4 ppt decrease) from the Violet 

Canal diversion, it is anticipated that there would be no adverse impacts to EFH within 

Louisiana and Mississippi territorial waters. However, impacts to turbidity would 

increase closer to the source of the diversion during periods of high flow (April through 

May, maximum flow of 7,000 cfs), although BMPs would be used during construction to 

ensure impacts were temporary and localized. Impacts from increased turbidity may 

include reduced feeding opportunities from visual predators and gill clogging. However, 

it is anticipated that species would move out of areas currently under construction. 

With the implementation of these restoration measures, alternative B would help protect 

EFH within the project area such as emergent marsh, oyster reefs, and SAV being utilized 

by Federally managed species within estuarine environments. Since all construction 

measures are taking place within the estuarine environment, it is anticipated that marine 

EFH would not be impacted. 

Based upon (Bartell et al., 2010) preliminary aquatics modeling results and Preliminary 

Hydrodynamic and Hydraulic Modeling for a Proposed Freshwater Diversion in the 

Vicinity of Violet, Louisiana (USACE, 2010), there would be a decrease in net 

productivity (gC/m2

) for juvenile red drum at Nodes 2 and 9 within Lake Borgne, and 

Nodes 8 and 73 within the inner Biloxi Marsh. Juvenile white and brown shrimp also 

show slight decreases in productivity within Lake Borgne (Nodes 2, 9) and upper Lake 

Borgne (Node 1). Modeled monthly productivity (metric tons/km2) for white shrimp in 

September shows impacts, albeit to an unknown extent. 

The model results indicate locations and years within the modeled domain and planning 

horizon characterized by both increases and decreases in the production of modeled 

fishes, brown shrimp, white shrimp, and blue crab. However, it must be emphasized that 

given the uncertainties associated with the hydrodynamic and hydraulic modeling, the 

preliminary aquatics modeling results when integrated over the modeled area and time 

horizon could be fairly interpreted as no significant impacts on the resources of interest.

Indirect Impacts

Indirect impacts include protection, creation, and nourishment of marsh habitat, and EFH. 

Shoreline protection features would not only prevent the erosion of interior emergent 

wetlands, but would also protect interior shallow ponds, which are essential nursery 

habitats for many fishery species. Shoreline protection features would also prevent the 

conversion of transitional wetland habitats, including inner marsh and marsh edge 

habitats, to less productive EFH categories, such as open water. Alternative B would not 
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only increase the areal extent of EFH, but would also improve the quality of transitional 

wetland habitats used by fish for spawning, nursery, forage, cover, and other life 

requirements. Some species serve as prey; therefore, predator populations may indirectly 

benefit, albeit to an unknown extent. 

Low dissolved oxygen (DO) levels could be a potential impact during construction 

activities in Lake Borgne and continue to persist after construction. Additionally, there is 

the potential that the Violet, Louisiana Freshwater Diversion could exacerbate low DO 

conditions in Lake Borgne, due to the high level of nutrients causing algal blooms. The 

potential for this impact could be monitored in the future after implementation addressed 

with adaptive management.

Cumulative Impacts

As described above, alternative B will result in direct and indirect impacts to EFH. These 

impacts would contribute incrementally to the cumulative impacts from ongoing habitat 

losses from natural occurring processes, as well as activities such as dredging, oil and gas 

development, and infrastructure development. Impacts to EFH would be offset from 

habitat restoration proposed under alternative B, as well as those from other anticipated 

restoration efforts. Project benefits would be partially supplemented by the overall net 

acres created, nourished, and protected by other Federal, state, local, and private 

restoration efforts including: CWPPRA 33,690 acres; State 2,543 acres; Vegetation 535 

acres; Section 204/1135, Beneficial Use 226 acres; WRDA 16,000 acres for a total of 

53,009 acres. The CWPPRA PO-30 has been constructed and PO-32 Lake Borgne 

portion has been constructed and the MRGO portion has been proposed for 

deauthorization under CWPPRA. These projects provide shoreline protection near to or 

adjacent to feature in this plan, and would protect additional portions of the landbridge 

between Lake Borgne and the MRGO channel. Additionally, there will be a maximum 1-

1.4 ppt reduction in salinity in addition to the 2-3 ppt salinity change in Lake Borgne 

from May to December based upon the proposed Violet, Louisiana Freshwater Diversion 

in combination with the 4,500 cfs of the combined Maurepaus Swamp area diversions. In 

combination, these diversions are predicted to reduce salinity in the Mississippi 

Territorial Waters by -0.6 to -0.9 ppt. 

Alternative B would work synergistically with those projects to provide increased habitat 

resources and EFH quality for Federally-managed fish species. The combination of this 

effort with the numerous other restoration projects occurring in southeastern Louisiana 

will be the slowing of the rate of shoreline retreat and restoring some of the delicate 

wetland habitats within the area. Detailed impacts from other state and Federal projects 

can be viewed in chapter 2. Alternative B would incrementally provide additional EFH 

with other restoration projects proposed within the region and provide more complete 

protection for the associated EFH in project area.
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4.20.3 Alternative C - MRGO Restoration Plan 7

Direct Impacts

Alternative C would restore approximately 17,352 acres of marsh habitats, 4,225 acres of 

cypress swamp, and add 314,944 linear feet of shoreline protection. Alternative C would 

convert open water to emergent wetland habitat and nourish 26,836 acres of existing 

marsh habitat and 6,093 acres of swamp. 

Approximately 10,048 acres of marsh would be directly impacted by construction of the 

perimeter dikes and earthen weirs. Direct impacts include the loss of 1,937 acres of 

water bottom for the construction of rock breakwater structures for shoreline protection. 

Of these potential impacts, 1,705 acres of impacted water bottoms are located in Lake 

Borgne, which is designated as critical habitat for Gulf sturgeon. Approximately 382 

acres of impact would be permanent impacts from construction of the rock shoreline 

protection. The remaining 1,323 acres would be temporary construction related impacts 

from flotation channel excavation and placement and access corridors. 

With the implementation of these restoration measures, alternative C would help protect 

EFH within the project area such as emergent marsh, oyster reefs, and SAV being utilized 

by Federally managed species within estuarine environments. Since all construction 

measures are taking place within the estuarine environment, it is anticipated that marine 

EFH would have no impacts. 

Excavation of access channels and placement of dredged material would cause temporary 

localized increases in turbidity, slight temperature increase and BOD, and DO decrease. 

Material dredged would be used beneficially for important emergent wetland 

nourishment and creation. BMPs would be used to reduce disturbances to EFH and fish 

mortality during construction including use of silt curtains and retention dikes to 

minimize runoff and overland flow, as well as reduced sediment movement and erosion 

into adjacent waterways and marshes, except were restoration and nourishment activities 

are desired. These actions could also help to minimize increases in turbidity and 

suspended particulates and restrict such impacts to the immediate construction area. 

Indirect Impacts

Indirect impacts associated with alternative C would be similar to those described under 

alternative B. 

Cumulative Impacts

Cumulative impacts associated with alternative C would be similar to those described 

under alternative B. 
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4.20.4 Alternative D - MRGO Restoration Plan 10

Direct Impacts

Impacts for alternative D are similar to that of alternative C, with the following 

exceptions, additional 557 acres of shoreline protection, 9 acres of retention dikes, and 

704 acres of marsh created. 

Excavation of access channels and placement of dredged material would cause temporary 

localized increases in turbidity, slight temperature increase and BOD, and DO decrease. 

Material dredged would be used beneficially for important emergent wetland 

nourishment and creation. BMPs would be used to reduce disturbances to EFH and fish 

mortality during construction including use of silt curtains and retention dikes to 

minimize runoff and overland flow, as well as reduced sediment movement and erosion 

into adjacent waterways and marshes, except were restoration and nourishment activities 

are desired. These actions could also help to minimize increases in turbidity and 

suspended particulates and restrict such impacts to the immediate construction area. 

With the implementation of these restoration measures, alternative D would help protect 

EFH within the project area such as emergent marsh, oyster reefs, and SAV being utilized 

by Federally managed species within estuarine environments. Since all construction 

measures would take place within the estuarine environment, it is anticipated that marine 

EFH would have no impacts. 

Indirect Impacts

Indirect impacts associated with alternative D would be similar to those described under 

alternative B. 

Cumulative Impacts

Cumulative impacts associated with alternative D would be similar to those described 

under alternative B. 

4.21 THREATENED AND ENDANGERED SPECIES

4.21.1 Alternative A - No Action Plan 

Direct Impacts

As a result of the devastating effect of Hurricane Katrina that made landfall in 2005, 

several important hurricane protection projects are under construction in the study area 

that are expected to have significant impacts on the future conditions of the area without 

implementation of this restoration study. These projects individually and cumulatively 

are anticipated to change the future environmental conditions of the basin regardless of 
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whether a restoration plan is implemented or not. Important among the anticipated 

changes, is the reduction in salinity levels from the construction of the MRGO closure 

structure and from freshwater in-puts from other projects in the project area, as 

demonstrated by the hydrologic modeling discussed in more detail in chapter 2. 

Shoreline retreat, subsidence, and habitat switching is expected to continue at the current 

rates. The net primary productivity within the project area would continue to decline and 

existing wetlands vegetation would continue to diminish. Without the input of sediment 

within the project area, the conversion of existing fragmented emergent wetland habitat

to shallow open water habitat would indirectly impact threatened and endangered species. 

The loss of coastal habitat, fish and wildlife resources, and EFH supported by this habitat 

is one cause of decline among threatened and endangered species that live within the 

project area. 

 

Land loss in the project area would reduce the availability of habitat for T&E species. 

Piping plover would lose access to some forage and roosting habitat as it shifts to shallow 

open water. As interior marshes are lost, shoreline retreat rates increase. The coastal 

habitat utilized by sea turtles would continue to be impacted from this accelerated 

shoreline retreat rate. The continued erosion in the southern lobes of Lake Borgne may 

result in additional salt water intrusion into the Central Wetlands area resulting in 

additional cypress swamp loss. This loss could affect the availability of nesting habitat 

for the recently delisted bald eagle. Conversely, the recently delisted brown pelicans will 

gain access to more shallow water foraging areas, resulting from the shoreline retreat and 

Gulf sturgeon could gain more foraging areas as more open water habitat is created. 

Indirect Impacts

The primary consequence of not implementing the MRGO ecosystem restoration, 

shoreline protection, and freshwater diversion in the project area would be the continued 

degradation and loss of emergent wetland habitats used by many different fish and 

wildlife species for shelter, nesting, feeding, roosting, cover, nursery, and other life 

requirements. The loss and deterioration of transitional wetland habitats over time could 

continue to indirectly affect, to an undetermined degree, all listed species that may 

potentially utilize the project area including: Gulf sturgeon, piping plovers, green sea 

turtles, Kemp’s Ridley sea turtles, loggerhead sea turtles, hawksbill sea turtle, leatherback 

sea turtle, and the West Indian manatee. The recovery of some sensitive/delisted species 

such as brown pelican, bald eagle, and colonial nesting birds could be indirectly impacted 

if habitat loss goes unabated. 

Without the construction of the proposed Violet, Louisiana Freshwater Diversion, the 

pallid sturgeon would not run the risk of entrainment. Though catch data has indicated 

that the pallid sturgeon population is not large within this stretch of river there would be a 

decreased risk of take with the no action alternative.
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Cumulative Impacts

Negative cumulative impacts to threatened and endangered species would be offset, to 

some extent, by the positive benefits of the reasonably foreseeable restoration activities in 

and near the project area. These include: the CWPPRA PO-30 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; and other wetland restoration efforts authorized under the LCA 

Plan in WRDA 2007. Features of the authorized HSDRRS, as well as the closure 

structure on the MRGO channel near the Bayou La Loutre Ridge would affect the 

hydrology of the study area. The closure structure near Bayou La Loutre has reduced 

tidal exchange between Lake Borgne and Breton Sound, which has reduced salinity in the 

project area. It is projected that this closure could reduce salinity by up to 6.6 ppt. 

Additionally, the closure structure and sector gates on the GIWW and Bayou Bienvenue 

planned near the confluence of the GIWW and the MRGO channel for the authorized 

improvements to the HSDRRS would alter flow patterns in the project area. 

Adverse cumulative impacts associated with the no action alternative would be the result

of the continued deterioration of habitat quality and quantity in the project area. Loss of 

suitable habitat can limit the recovery of listed species. The continued coastal land losses 

and deterioration of critical habitats along large areas of southeastern Louisiana and the 

Gulf Coast would further stress the species that are dependent on these habitats for all or 

a part of their life cycle. Cumulative effects on listed species would be offset, to some 

degree, by the positive impacts of implementing the other state and Federal projects

mentioned above. 

4.21.2 Alternative B - MRGO Restoration Plan 2

Compliance with the Endangered Species Act (7 U.S.C. 136; 16 U.S.C. 460 et seq.) is 

being coordinated with the USFWS and the NMFS for those species under their 

respective jurisdictions. A final BA is included in the FEIS in appendix G. The USACE 

has provided a copy of the BA to the USFWS and NMFS and initiated formal 

consultation with the USFWS on potential impacts to the endangered pallid sturgeon 

(Scaphirhynchus albus), and initiated formal consultation with NMFS on potential 

impacts to the threatened Gulf sturgeon (Acipenser oxyrhynchus desotoi) and its critical 

habitat and the five species of sea turtles that may be in the project area. NMFS issued a 

biological opinion (BO) on May 3, 2012, which is also included in appendix G. 

Direct Impacts

Alternative B would restore and/or protect approximately 10,318 acres of cypress swamp, 

19,630 acres of wetlands in the Lower Pontchartrain sub-basin, 54 acres of ridge habitat, 

and provide 122 acres of shoreline protection. The freshwater diversion, pulsing 7,000 cfs 

from April to May would influence approximately 115,078 acres. The dredging for this 

alternative will result in the direct impacts and disposal of material during the restoration 
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process, and the construction and operation of the diversion and associated outfall 

management features, will result in tangible environmental changes within the project 

area. Reference figure 2-9 for alternative B features.

Gulf sturgeon critical habitat would experience permanent and temporary impacts from 

implementation of this alternative. Direct impacts include the permanent loss of water 

bottom from placement of the shoreline protection features as well as temporary impacts 

associated with a 150 feet by 500 feet flotation channel necessary for access during the 

construction. Approximately 35,367 linear feet (122 acres) of shoreline protection 

measures would permanently remove water bottoms from critical habitat eliminating use 

of this area by Gulf sturgeon. This construction would occur in waters typically less 

than 2 meters deep and is not expected to adversely affect Gulf sturgeon that may be in 

the project area. Ecological benefits from this alternative include the protection of 

valuable shoreline from transitioning into more fragmented emergent marsh. 

Temporary impacts would include dredging of floatation channels parallel to the 

shoreline protection features and access dredging to the floatation channels for shoreline 

protection feature construction. Dredged flotation channel material would be used in 

dike/closure construction or refurbishment, would be stockpiled adjacent to the channel 

to backfill flotation access channels, or behind the dikes and closures in shallow water to 

an elevation conducive to wetlands development. Floatation channel excavation would 

disturb 699 acres of critical habitat. Floatation channel dredged material placement 

would disturb 694 acres of critical habitat. Access channel excavation to the floatation 

channels would disturb 118 acres of critical habitat. Excavation of floatation/access

channels, placement of dredged material, and backfilling of the floatation/access channels 

would cause temporary local increases in turbidity, slight temperature increase, and DO 

decrease. 

The borrow sites for the proposed action fall largely within the designated critical habitat 

for the Gulf sturgeon. Lake Borgne water bottoms were determined to be the most costeffective and feasible borrow source for construction of the remaining restoration features 

requiring sediment. Impacts to the prey items within Critical habitat Unit 8, which 

includes Lake Pontchartrain, Lake Borgne, and the Mississippi Sound, would result from 

the implementation of the tentatively selected plan during the construction of shoreline 

protection features, borrow material removal, flotation access channel construction, and 

stock piling of flotation access material within Lake Borgne. The proposed action could 

result in a permanent change to the bathymetry of approximately 15,724 acres of Lake 

Borgne following the removal of borrow material. In order to reduce impacts to critical 

habitat, hard bottom areas would be avoided because it is considered preferred foraging 

habitat for the Gulf sturgeon. Although hard bottom areas would provide better material 

for restoration features and the duration of the potential impacts of turbidity could be 

reduced if sediments with a greater sand component were utilized, it was ultimately 

determined that impacts to Gulf sturgeon would be minimized by avoiding these essential 

foraging habitat locations. Lake Pontchartrain is the closest site for a few of the marsh 

creation features. However, the portion of Lake Pontchartrain in the study area close to 

the marsh creation features is also designated critical habitat for Gulf sturgeon. Due to 
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the sandy composition of Lake Pontchartrain bottoms in the vicinity, these areas are 

considered prime foraging habitat, and were removed by the CEMVN from consideration 

as a potential borrow source. 

This alternative would require dredging 87 mcy of borrow material from 9,036 acres of 

Lake Borgne to a depth of 10 feet plus 2 feet of allowable overdredge from Gulf sturgeon 

critical habitat. During any given construction year, it is believed that up to three 

hydraulic dredges will be working within Lake Borgne at any given time. Entrainment of 

Gulf sturgeon is not expected since hydraulic dredges are slow moving and use of them is 

not known to impact the species. During borrow dredging operations Gulf sturgeon 

would be unable to utilize these construction areas. The removal of the lake bottom will 

result in the loss of all benthic organisms established within the borrow areas. However, 

the benthic community is expected to recover quickly from these impacts. This 

oligohaline estuarine zone is composed of opportunistic species that respond rapidly to 

dynamic abiotic factors such as salinity and DO, and populations can rapidly recover by 

recruitment from adjacent coastal waters. Resistance and resilience to periodic habitat 

disturbance, the presence of natural cycles in distribution and abundance, and the 

occurrence of alternate community states have to be considered in evaluating habitat 

quality and restoration status (Poirrier, Spalding, and Franze). There will be a temporary 

decrease in the amount of Gulf sturgeon prey species available within Lake Borgne at the 

location of the borrow pits; however, the borrow sites have been situated so as to avoid 

the hard bottom substrates Gulf sturgeon prefer to forage over. Access from borrow sites 

to marsh restoration sites would not involve dredging any primary constituent elements 

within critical habitat. A detailed analysis of the impacts to the Gulf sturgeon can be 

found within the biological assessment in appendix G. 

The BO issued by NMFS concluded that the project activities in the Lower Pontchartrain 

Sub-basin will not reduce the critical habitat’s ability to support the Gulf sturgeon’s 

conservation. Following project activities it is expected that the majority of the benthic 

community structure in the 16,694 acres to be dredged will return to, or return nearly to, 

pre-project status (i.e., in terms of species diversity, species richness, species abundance), 

with some inherent natural variability. NMFS does not expect the 382 acres of adverse 

impacts to the abundance of prey items resulting from the construction of foreshore 

protection barriers to appreciably reduce the value of Gulf sturgeon critical habitat. 

The proposed freshwater diversion at Violet, Louisiana would be constructed along the 

eastern side of the Mississippi River at river mile (RM) 84 to discharge freshwater into 

the Central Wetlands and adjacent open water and wetland areas. The structure would be 

designed to discharge a minimum of 1,000 cfs and a maximum of 7,000 cfs. The 

diversion would be operated to provide freshwater during the months of April and May 

for four out of ten years to meet the Chatry salinity targets. Impacts near the diversion 

will include a shift to more freshwater tolerant species near the diversion during the 

months of operation. Resistance and resilience to periodic habitat disturbance, the 

presence of natural cycles in distribution and abundance, and the occurrence of alternate 

community states have to be considered in evaluating habitat quality and restoration 

status (Poirrier, Spalding, and Franze). The freshwater diversion will reduce the salinity 
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to values that were historically recorded before the MRGO was constructed. The 

freshwater input will result in prey and predatory fish populations to shift slightly within 

the project area. The operation of the Violet, Louisiana Freshwater Diversion will mimic 

historic conditions when Mississippi River experience flood stages and over topped its 

banks, freshening of the Lake Pontchartrain/Lake Borgne ecosystem. Gulf sturgeon are 

either making their way to or already in their spawning grounds in the rivers at the time 

the diversion will be operated in April and May. Any juvenile Gulf sturgeon that could 

possibly still be in the area would not be affected by the lowered salinity as they typically 

reside in areas with lower salinity during this part of the year. As such, the CEMVN 

expects that the reduction in salinity should have little effect on resident populations of 

Gulf sturgeon as the aquatic modeling suggests. 

West Indian manatees are infrequent visitors to Louisiana. Sightings of the West Indian 

manatee in Louisiana have primarily occurred in Lakes Pontchartrain and Maurepas, and 

associated coastal waters and streams (i.e., Amite, Blind, Tchefuncte, and Tickfaw 

Rivers) and from a few rare sightings along the Gulf coast during the summer months 

(i.e., June through September) There is no known resident population within the State. 

To avoid potential impacts to manatees during restoration activities the following 

standard protective measures would be implemented; 

• All contract personnel associated with the project should be informed of the 

potential presence of manatees and the need to avoid collisions with manatees, 

which are protected under the Marine Mammal Protection Act of 1972 and the 

Endangered Species Act of 1973. 

• All construction personnel are responsible for observing water-related activities 

for the presence of manatee(s). 

• Temporary signs should be posted prior to and during all construction/dredging 

activities to remind personnel to be observant for manatees during active 

construction/dredging operations or within vessel movement zones (i.e., work 

area), and at least one sign should be placed where it is visible to the vessel 

operator. 

• Siltation barriers, if used, should be made of material in which manatees could not 

become entangled, and should be properly secured and monitored. 

• If a manatee is sighted within 100 yards of the active work zone, special operating 

conditions should be implemented, including: no operation of moving equipment 

within 50 feet of a manatee; all vessels shall operate at no wake/idle speeds within 

100 yards of the work area; and siltation barriers, if used, should be re-secured 

and monitored. Once the manatee has left the 100-yard buffer zone around the 

work area on its own accord, special operating conditions are no longer necessary, 

but careful observations would be resumed. 

• Any manatee sighting should be immediately reported to the U.S. Fish and 

Wildlife Service (337/291-3100) and the LDWF, Natural Heritage Program 

(225/765-2821). 

Also, to prevent entrapment of manatee inside of dredged material receiving areas that 

have dikes or other retention features that enclose an area of open water, the area would 
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be inspected for the presence of manatee: 1) before complete closure of the confining 

features; and 2) again before material is discharged in to the receiving area. Any manatee 

that is sighted should be allowed to leave the area before work resumes. 

Adherence to the protection measures would help ensure that any manatee that wanders 

into the project area would not be adversely affected. The disturbance to the manatee 

would only be temporary during project construction, and would result in temporary 

displacement. The manatees would likely move to another area for foraging or resting 

purposes, and there would be other available areas to which the animals may relocate. 

Since Louisiana has no resident population of West Indian manatee and the protection 

measures will be adhered to, it is expected that the proposed MRGO ecosystem 

restoration project is “Not Likely to Adversely Affect” the species. 

Since no barrier island restoration components are incorporated in this alternative; direct 

impacts to piping plover and the green, Kemp’s Ridley, loggerhead, hawksbill, and 

leatherback sea turtles are not expected.

The CEMVN has worked to reduce any negative impacts to the Gulf sturgeon or its 

critical habitat that could result from the proposed action by not borrowing material from 

areas that are found to be prime foraging habitat for the Gulf sturgeon, designating 

borrow sites larger than needed (so that avoidance of undiscovered environmental issues 

can take place), situating shoreline protection measures in waters 2 meters or less in 

depth, backfilling floatation/access channels, and alternating the removal of borrow 

material between the northern and southern lobes of Lake Borgne will reduce impact to 

the primary constituent elements of the Gulf sturgeon. Benthic community recovery 

within borrow sites will be monitored following implementation cycle 1. Once removed, 

Gulf sturgeon would once again be able to forage within these areas. Although the 

proposed construction of this alternative will affect Gulf sturgeon critical habitat, given 

the previous information, the CEMVN believes the action may affect the species and 

would not likely adversely affect critical habitat. The CEMVN is engaged in formal 

consultation with the NMFS. NMFS included two conservation recommendations in 

their BO, which they believe could work to minimize or avoid effects from the proposed 

action on the Gulf sturgeon. The USACE had stated that the recommendations would be 

implemented as part of the project. The conservation recommendations include: 1) 

Gather data describing 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; and 2) Gather data describing Gulf sturgeon movements 

within the Lower Pontchartrain Sub-basin. 

In order for NMFS to be kept informed of actions minimizing or avoiding adverse effects 

or benefiting listed species or their habitats, NMFS would be notified of the 

implementation of any conservation recommendations, or other updates as the project is 

implemented. 

The threatened loggerhead is the most abundant species of sea turtle occurring in U.S. 

waters. The nearshore waters of the Gulf of Mexico are believed to provide important 
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developmental habitat for juvenile loggerheads. Studies conducted on loggerheads 

stranded on the lower Texas coast (south of Matagorda Island) have indicated that 

stranded individuals were feeding in nearshore waters shortly before their death (Plotkin 

et al., 1993). Loggerhead sea turtles may be found within the project area. Habitat in 

Louisiana that is suitable for Loggerheads to nest on is typically associated with that of 

barrier islands. CEMVN believes that the proposed action will only temporarily disrupt 

foraging loggerhead sea turtles that may be in the area. Coastal erosion and habitat loss 

is one limiting factor for the successful recovery of sea turtle populations in the Louisiana 

coastal zone. Coastal restoration efforts such as the MRGO project, should prove to be 

beneficial to the loggerhead sea turtle. After the selection of a barrier island restoration 

alternative, coordination regarding the specific impacts of this proposed action will need 

to be conducted. After assessing the MRGO project area along with the needs of the 

loggerhead sea turtle, CEMVN concludes that the MRGO ecosystem restoration project 

is “Not Likely to Adversely Affect” the species. 

 

The nearshore waters of the Gulf of Mexico are believed to provide important 

developmental habitat for juvenile Kemp's ridley sea turtles. Ogren (1988) suggests that 

the Gulf coast, from Port Aransas, Texas, through Cedar Key, Florida, represents the 

primary habitat for subadult ridleys in the northern Gulf of Mexico. Stomach contents of 

Kemp's ridleys along the lower Texas coast had a predominance of nearshore crabs and 

mollusks, as well as fish, shrimp and other foods considered to be shrimp fishery discards 

(Shaver, 1991). Analyses of stomach contents from sea turtles stranded on upper Texas 

beaches apparently suggest similar nearshore foraging behavior (Plotkin, pers. comm.). 

Impacts to Kemp’s Ridley sea turtle population should be negligible or non-existent. The 

potential temporary removal of food sources by dredging operations may cause the 

Kemp’s Ridley sea turtle to forage elsewhere along the Gulf coast until the area is recolonized by prey species. Coastal erosion and habitat loss is one limiting factor for the 

successful recovery of sea turtle populations in the Louisiana coastal zone. After 

assessing the MRGO project area along with the needs of the Kemp’s Ridley sea turtle, 

CEMVN concludes that the MRGO ecosystem restoration project is “Not Likely to 

Adversely Affect” the species. 

The hawksbill turtle is relatively uncommon in the waters of the continental United 

States, preferring coral reefs, such as those found in the Caribbean and Central America. 

The likelihood of encountering a hawksbill sea turtle in waters of the U.S. is low. 

Hawksbill sea turtles typically nest on beaches in the Caribbean and Central America. 

Given the habitat preferences, the CEMVN concludes that the MRGO restoration project 

is “Not Likely to Adversely Affect” the species. 

The likelihood of encountering a leatherback sea turtle in waters of the U.S. is low. 

Leatherback sea turtles typically are found in deep ocean waters and typically nest on 

beaches along Central America and Costa Rica. Given the habitat preferences, the 

CEMVN concludes that the MRGO restoration project is “Not Likely to Adversely 

Affect” the species. 
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Currently, green turtles are uncommon in offshore waters of the northern Gulf, but 

abundant in some inshore embayments. Given the lack of extensive back-barrier marsh 

and sea grass beds and the low incidence of sightings in the proposed project areas, 

adverse impacts to the green sea turtle population are not expected. Additionally, the use 

of a hydraulic cutterhead-type dredge is not known to take sea turtles. After assessing the 

MRGO project area along with the needs of the Green sea turtle, CEMVN concludes that 

the MRGO ecosystem restoration project is “Not Likely to Adversely Affect” the species. 

Piping plover is a shorebird that inhabits open beaches, alkali flats, and sandflats of North 

America. Ideal wintering habitat for the piping plover on the Gulf of Mexico coast would 

contain large sand flats or sand-mud flats adjacent to a tidal pass or tidal inlet (Haig, 

1985; Nicholls, 1989). A thin layer of mud covering the sand seems to attract plovers, 

due to possible food or refuge association (Nicholls, 1989). Nicholls observed that 

barrier beaches with over wash areas or sections of old marshes also attract plovers. 

Plovers are attracted to intertidal areas with little to no emergent vegetation. The project 

area contains no known areas other than the Chandeleur Barrier Islands that would 

provide this type of suitable habitat for the piping plover. Restoration features were 

discussed for this proposed action but it was determined that further analysis would be 

required. No restoration of the barrier islands is associated with this alternative. Given 

this information, CEMVN concludes that the proposed construction in this alternative 

would have no effect on the Piping Plover species. 

Indirect Impacts

Indirect impacts would include protection, creation, and nourishment of 19,630 acres of 

marsh habitat, which would improve diversity of habitat types within the project area by 

preventing these areas to all become shallow open water. Shoreline protection features 

would not only prevent the erosion of interior emergent wetlands but would also protect 

interior shallow ponds, which are essential nursery habitats for many fishery species. 

Shoreline protection features would also prevent the conversion of transitional wetland 

habitats, including essential inner marsh and marsh edge habitats, to open water. An 

increase in the acreage of transitional habitat would result in decreased inter- and intraspecific competition between resident and migratory fish species and would sustain a 

larger variety and greater diversity of species. 

Water diversions are used for flood control, water supply, and habitat restoration in the 

lower Mississippi River (LMR) but their impacts on imperiled sturgeon populations are 

unknown. USACE sponsored sampling efforts have shown catch data that suggests that 

pallid sturgeon populations decline as you progress further downstream (RM 0 to RM 

320). Pallid and shovelnose sturgeon, as well as evidence of recruitment are noticeably 

present with RM 80-160 of the LMR. The proposed diversion at Violet will be located at 

RM 85. This falls within a reach of the MRGO that ERDC has shown has a population 

of pallid sturgeon that are showing signs of recruitment. This increased presence of 

adult, sub-adult, post-larval, and larval pallid sturgeon within the LMR suggests that 

there is an increased potential of entrainment of small sized sturgeon in diversions. The 

extent of impacts to this sturgeon population from entrainment in water diversion 
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structures is currently not quantifiable. Further population analysis is needed to be able 

to project the size of the LMR pallid population and what impact pallid sturgeon 

entrainment has on this population. Given this current information CEMVN concludes 

that there is a risk of entrainment of pallid sturgeon by this diversion structure and that 

therefore the proposed MRGO ecosystem restoration project “May Affect” the species. 

Cumulative Impacts

The direct and indirect impacts described above for alternative B would contribute to the 

overall cumulative impacts to listed species within the project area. Listed species would 

continue to be adversely affected by other sources such as dredging projects, oil and gas 

development, oil spills, and infrastructure development. Cumulative impacts on listed 

species would include adverse effects from habitat deterioration as well and the benefits 

from other restoration efforts. Project benefits from alternative B would be partially 

supplemented by the overall net acres created, nourished, and protected by other 

anticipated Federal, state, local, and private restoration efforts including: CWPPRA 

33,690 acres; State 2,543 acres; Vegetation 535 acres; Section 204/1135, Beneficial Use 

226 acres; and WRDA 16,000 acres for a total of 53,009 acres. The CWPPRA PO-30 

has been constructed and PO-32 Lake Borgne portion has been constructed and the 

MRGO portion has been proposed for deauthorization under CWPPRA. These projects 

provide shoreline protection near to or adjacent to features in this plan, and would protect 

additional portions of the landbridge between Lake Borgne and the MRGO channel. 

Alternative B would work synergistically with the other reasonably foreseeable projects 

to provide more complete protection and restoration of listed species habitat in the project 

area. The combination of beneficial habitat impacts from alternative B with the 

numerous other restoration projects occurring in southeastern Louisiana would slow the 

rate of shoreline retreat and restore some of the important habitat for listed species within 

the area. These coastal habitats are requisites for some portion of the life cycle of all of 

the listed species that occur within the project area. The improvement of this habitat will 

reduce at least one stressor that is hindering the recovery of these listed species. 

4.21.3 Alternative C - MRGO Restoration Plan 7

The following is a summary of impacts to the threatened and endangered species from the 

proposed action. For a complete analysis please review the biological assessment 

included in appendix G. 

Direct Impacts 

Impacts would be similar to alternative B except this alternative includes additional 

restoration measures and borrow requirements not identified in alternative B. The 

tentatively selected plan would restore and/or protect approximately 10,318 acres of 

cypress swamp, 44,188 acres of wetlands in the Lower Pontchartrain sub-basin, 54 acres 

of ridge habitat, and provide 314,944 linear feet of shoreline protection. Reference

figure 2-10 for alternative C features. To create these additional features, 152 mcy of 
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Restoration Plan 4-108 June 2012

borrow material would be removed 15,724 acres of Gulf sturgeon critical habitat within 

Lake Borgne. Additional borrow pits would be required to provide the necessary 

material for the restoration projects and would impact approximately 6,924 acres of 

marsh would be directly impacted by construction of the perimeter dikes. Direct impacts 

include the loss of 1,937 acres of water bottom for the construction of rock breakwater 

structures for shoreline protection, as well as flotation channels. The additional 1,881 

acres of shoreline protection would even further abate shoreline loss within the area. 

Restoring the additional 17,493 acres of wetland will provide more habitat diversity and 

ecological benefits for the T&E species within the lower Pontchartrain basin. 

The additional dredging and disposal of material associated with this action will require 

that more of the Gulf sturgeon critical habitat be disturbed by dredging and construction 

activities. 471 acres of permanent impacts to Gulf sturgeon critical habitat would occur 

from the construction of the shoreline protection features. 1,511 acres of temporary 

impacts to Gulf sturgeon critical habitat would result from the excavation of flotation 

access channels (138), stockpiling of dredged material (134), and the excavation of 

access channels (14) to access the flotation access channels. This increased need for 

borrow will increase the duration of construction activities within Lake Borgne resulting 

in longer duration and quantity of direct impacts to water quality. This will result in less 

of the lake being accessible to the Gulf sturgeon for the duration of dredging activities. 

Given this information, CEMVN concludes that the proposed construction in this 

alternative “May Affect” the Gulf sturgeon species and that formal consultation with the 

NMFS has been initiated. NMFS issued a biological opinion (BO) on May 3, 2012, 

which is included in appendix G. 

Impacts to pallid sturgeon, piping plover, West Indian manatee, and the green, Kemp’s 

Ridley, loggerhead, hawksbill, and leatherback sea turtles will be the same as in 

alternative B. 

Indirect Impacts

Indirect impacts associated with alternative C would be similar to those described under 

alternative B. 

Cumulative Impacts

Cumulative impacts associated with alternative C would be similar to those described 

under alternative B. 

4.21.4 Alternative D - MRGO Restoration Plan 10

Direct Impacts

Impacts would be similar to alternative C except this alternative includes additional 

restoration measures not identified in alternative C. Alternative D would restore and/or 

protect approximately 10,318 acres of cypress swamp, 44,892 acres of wetlands in the 
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Lower Pontchartrain sub-basin, 54 acres of ridge habitat, and provide 410,567 linear feet 

of shoreline protection. Reference figure 2-11 for alternative D features.

To create these additional features 154.3 mcy of borrow material would be removed from 

the bottom of Lake Borgne. Approximately 6,933 acres of marsh would be directly 

impacted by construction of the perimeter dikes. Direct impacts include the loss of an 

additional 466 acres of water bottom for the construction of rock breakwater structures 

for shoreline protection, as well as flotation channels. The additional borrow material 

required for these restoration measures will require additional impacts to Gulf sturgeon 

critical habitat from the associated excavation of borrow material. 

Indirect Impacts

Indirect impacts associated with alternative D would be similar to those described under 

alternative C. 

Cumulative Impacts

Cumulative impacts associated with alternative C would be similar to those described 

under alternative B. 

4.22 SOCIOECONOMIC AND HUMAN ENVIRONMENT

The recreation features proposed for Bayou Bienvenue, the Violet, Louisiana Freshwater 

Diversion, and Shell Beach are not anticipated to cause any socioeconomic impacts on 

the project footprints. Utility connections would be from existing utility lines and there 

would be no disruptions or relocations. Additionally, solar lighting would be used 

whenever possible. The only possible socioeconomic impact would be to community 

cohesion as described in its section below. 

4.22.1 Population

4.22.1.1 Alternative A - No Action Plan 

Direct Impacts

The no action alternative would have no direct impacts on human populations. Under the 

no action alternative, no restoration efforts would take place under this authority. Under 

the no action plan, communities closer to the MRGO would continue to be impacted by 

storm surge and flooding during major storm events, incurring associated cost in damage 

to housing, local economy and commercial structures. Portions of the HSDRRS have 

been built to provide some protection to the population centers of Chalmette, Arabi, 

Poydras, Meraux, and Violet. 
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Restoration Plan 4-110 June 2012

Indirect Impacts

The no action alternative would have no indirect impacts on human populations. 

Cumulative Impacts

Cumulative impacts of implementing the no action alternative would be the additive 

combination of impacts to persons in the area by this and other Federal, state, local, and 

private restoration efforts. The no action alternative would work synergistically with 

other restoration and protection projects to provide critical and essential marsh 

restoration, which, in turn, would provide some protection to communities in the area that 

may otherwise be damaged due to continued erosion and land loss. The no action 

alternative would not contribute to any impact to persons in the area rather, the MRGO 

would contribute toward achieving and sustaining a coastal ecosystem that would support 

and protect the environment, local economy and culture of the region. 

4.22.1.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

There are no human populations within the project footprints, and the proposed action 

would have no direct effects outside of these footprints. Hence, this alternative would not 

be expected to have any direct effects on nearby populations. The location of the 

proposed Violet, Louisiana Freshwater Diversion would not require the acquisition of any 

residential structures or businesses in the area.

Indirect Impacts

There are no human populations within the project footprints, and the proposed action 

would have no direct effects outside of these footprints. Hence, this alternative would not 

be expected to have any direct effects on nearby populations.

Cumulative Impacts

Cumulative impacts of implementing alternative B would be the additive combination of 

impacts to persons in the area by this and other anticipated Federal, state, local, and 

private restoration efforts. Alternative B would work synergistically with other 

restoration and protection projects to provide critical and essential marsh restoration, 

which, in turn, would provide some protection to communities in the area that may 

otherwise be damaged due to continued erosion and land loss. Alternative B would not 

contribute to any impacts to persons in the area, rather, the MRGO would contribute 

toward achieving and sustaining a coastal ecosystem that would support and protect the 

environment, local economy and culture of the region. 
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4.22.1.3 Alternative C - MRGO Restoration Plan 7

Direct, indirect, and cumulative impacts associated with alternative C would be the same 

as the impacts from alternative B. 

4.22.1.4 Alternative D - MRGO Restoration Plan 10

Direct, indirect, and cumulative impacts associated with alternative C would be the same 

as the impacts from alternative B. 

4.22.2 Community Cohesion

4.22.2.1 Alternative A - No Action Plan

Direct Impacts

The no action alternative would have no direct impacts on community cohesion. 

Indirect Impacts

The no action alternative would have no indirect impacts on community cohesion. 

Cumulative Impacts

The no action alternative would not contribute to cumulative impacts on community 

cohesion. 

4.22.2.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

Alternative B, which includes implementing shoreline protection, wetland 

creation/nourishment, and the Violet, Louisiana Freshwater Diversion, would have 

minimal direct impacts on community cohesion. The only project footprint that borders a 

neighborhood is that of the Violet, Louisiana Freshwater Diversion. The construction of 

this diversion would create a new canal in a field measuring approximately 3,150 feet in 

width that currently separates two subdivisions. The field is an open track of agricultural 

land that contains no paths or walkways connecting the two subdivisions. No residential 

or business displacement is anticipated under this alternative. The addition of a canal in 

this empty field should minimally affect the neighborhood’s community cohesion. 

Indirect Impacts

Indirect impacts of implementing shoreline protection, wetland creation/nourishment, and 

the Violet, Louisiana Freshwater Diversion should be minimal. Although the 

construction of the diversion may increase feelings of separation between the two 
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subdivisions, there is a proposal to add recreation features as part of the Violet, Louisiana

Freshwater Diversion design. These proposed recreation features should draw more 

residents to the site than would have previously gathered in an open agricultural field. 

The coming together of residents for recreational purposes at this site may, in fact, 

strengthen the community cohesion of the neighborhood. The recreation features 

proposed for Bienvenue Triangle and Shell Beach would likely have the same positive 

effect.

The proposed Violet, Louisiana Freshwater Diversion will require the relocation of two 

highways in the area. These highways are currently used by Fire and Emergency Medical 

Services (EMS) personnel to respond to emergencies locally and within the region. In 

order to minimize impacts during the construction phase of the channel, a bypass road 

would be temporarily constructed to divert traffic from E. Judge Perez Drive while the 

diversion channel is constructed. A bridge will be built over the channel to maintain 

traffic movement along E. Judge Perez Drive. Similarly, traffic along St. Bernard 

Highway will be maintained by constructing a bypass road. 

Cumulative Impacts

Cumulative impacts include the incremental effect of alternative B with the combination 

of impacts and benefits for overall net acres created, nourished, and protected by other 

anticipated Federal, state, local, and private restoration efforts. For example, the coming 

together of residents for recreational purposes at the Violet Freshwater Diversion site 

may, in fact, outweigh any negative feelings of physical separation and actually 

strengthen the community cohesion of the neighborhood. The recreation features 

proposed for Bienvenue Triangle and Shell Beach would likely have the same positive 

effect.

4.22.2.3 Alternative C MRGO Restoration Plan 7

Direct, indirect, and cumulative impacts associated with alternative C would be the same 

as the impacts from alternative B. 

4.22.2.4 Alternative D MRGO Restoration Plan 10

Direct, indirect, and cumulative impacts associated with alternative D would be the same 

as the impacts from alternative B. 

4.22.3 Infrastructure

4.22.3.1 Alternative A - No Action Plan

Direct Impacts

The no action alternative would have no direct impacts on infrastructure. 
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Indirect Impacts

Indirect impacts to infrastructure would result from the persistence of existing conditions 

including impacts related to continuing coastal land loss.

Cumulative Impacts

The projected continued coast wide decline of emergent wetlands would contribute to the 

deterioration of substrate upon which infrastructure features (e.g., oil, gas and water 

pipelines and telephone and electric transmission wires) are constructed. The no action 

plan would not propose any restoration projects to offset the deterioration of wetlands. 

As a result, the cumulative effects of land loss and degradation could lead to increased 

costs for maintaining and repairing existing infrastructure. However, these impacts 

would be somewhat offset by construction of the CWPPRA PO 30 project and similar 

anticipated projects. 

4.22.3.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

Implementing this alternative would have a temporary disruption of rail and highway 

service (Alabama Great Southern Railroad (Norfolk), E. St. Bernard Highway, and E. 

Judge Perez Highway). As part of this alternative, a control structure 500 feet long in the 

Mississippi River with four 13-foot by 13-foot gated box culverts would be built. Bypass 

routes for the railroad and E. St. Bernard Highway (totaling approximately 2,750 feet) 

would be built before beginning construction of the diversion structure at the Mississippi 

River. Railroad access would be maintained throughout the bypass construction process, 

and the bypass would be designed to allow railroads to maintain existing speeds. 

Therefore there would be no rail delays. Delays along E. St. Bernard Highway would 

occur for less than one week as the two-lane road is reduced to one lane of traffic during 

the tie-in process. Once completed, the Alabama Great Southern Railroad (Norfolk) 

tracks and E. St. Bernard Highway would pass over the structure, and the temporary 

bypass routes would be removed. Similarly, a temporary bypass road would be 

constructed at E. Judge Perez Highway at the proposed diversion alignment. The bypass 

route would be approximately 3,450 feet long. A small bridge would be constructed at 

the existing roadway alignment, and the approach over the diversion structure would be 

elevated above grade when the road is reconstructed. As with the bypass for E. St. 

Bernard Highway, delays along E. Judge Perez Highway would occur for less than one 

week as the two-lane road is reduced to one lane of traffic during the tie-in process. 

Travel would resume on the reconstructed highway along its existing alignment. 

Indirect Impacts

Over the 50-year period of analysis, this alternative would protect, create and nourish 

emergent wetlands that would reduce shoreline erosion and land loss thereby reducing the 

need for relocation, repair or replacement of infrastructure.
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Cumulative Impacts

Alternative B would result in direct and indirect impacts that would contribute to the 

cumulative impacts on infrastructure within the project area. The combination of impacts 

and benefits under alternative B for overall net acres created, nourished, and protected 

together with other anticipated Federal, state, local, and private restoration efforts would 

provide more protection for the landbridge, which would continue to provide protection 

to existing infrastructure in the project areas. 

4.22.3.3 Alternative C - MRGO Restoration Plan 7

Direct, indirect, and cumulative impacts associated with alternative C would be the same 

as the impacts from alternative B. 

4.22.3.4 Alternative D - MRGO Restoration Plan 10

Direct, indirect, and cumulative impacts associated with alternative D would be the same 

as the impacts from alternative B. 

4.22.4 Employment and Income

4.22.4.1 Alternative A - No Action Plan

Direct Impacts

The no action alternative would have no direct impacts on employment or income. 

Indirect Impacts

Indirect impacts would result in the persistence of existing conditions including 

continued wetland loss and degradation of the Lake Borgne-MRGO ecosystem. This 

continued wetland loss would have localized impacts on employment and income. For 

example, the effects of wetland loss and degradation of the Lake Borgne-MRGO 

Landbridge would lead to a decline in transitional wetland habitats, an important EFH 

which, in turn, could lead to some undetermined level of jobs and income losses in local 

fishery related employment and income.

Cumulative Impacts

As described above, the no action plan would have no direct impact and some indirect 

impact on employment and income in the area. Other anticipated state and Federal 

projects in the project area would be expected to provide some construction jobs. In 

addition, habitat restoration from these other projects would be expected to offset job and 

income losses that would otherwise be expected to occur due to habitat declines for 

Federally-managed species. Although these other anticipated projects and programs 

would provide some undetermined level of positive benefits to employment and income, 
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they would not be sufficient to offset the impacts of the long-term, coast wide wetland 

losses projected for Louisiana (USACE, 2004). Coastal Louisiana's continued wetland 

loss and the resulting depletion of wetland-dependent natural resources (fisheries, oysters, 

hunting, recreation, etc.) could likely result in a decline of job opportunities and personal 

income throughout rural coastal areas (USACE, 2004). Other supporting economic 

activities such as marinas, bait and tackle shops could also be adversely impacted by the 

degradation and eventual loss of these wetlands and wetland-dependent resources. The 

loss of storm buffering provided by wetlands could result in the need for greater 

expenditures for maintaining and repairing existing infrastructure. This could provide 

localized employment and income benefits. However, these benefits would likely be 

offset by the expenditures necessary for maintaining, upgrading and constructing new 

hurricane and flood protection. 

4.22.4.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

There may be a temporary increase in local employment due to the construction activities 

related to implementation. There should be no permanent effects on employment and 

income.

Indirect Impacts

Over the 50-year period of analysis alternative B would protect, create and nourish 

thousands of acres of emergent wetlands that would benefit, to some undetermined level, 

local employment in wetland-dependent jobs such as commercial and recreational 

fisheries, ecotourism. Creation of the wetlands would provide benefits for supporting 

economic activities such as marinas, bait and tackle shops, and other fishery dependent 

business activities. 

Cumulative Impacts

Cumulative impacts would be the synergistic effect with the additive combination of 

impacts and benefits for overall net acres created, nourished, and protected by other 

anticipated Federal, state, local, and private restoration efforts. Alternative B would work 

synergistically with these other projects and programs to provide not only more complete 

protection for the Lake Borgne-MRGO landbridge but also help support coast wide 

wetland-dependent employment. 

4.22.4.3 Alternative C - MRGO Restoration Plan 7

Direct, indirect, and cumulative impacts associated with alternative C would be the same 

as the impacts from alternative B. 
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4.22.4.4 Alternative D - MRGO Restoration Plan 10

Direct, indirect, and cumulative impacts associated with alternative D would be the same 

as the impacts from alternative B. 

4.22.5 Oil, Gas And Utilities

4.22.5.1 Alternative A - No Action Plan

Direct Impacts

The no action alternative would have no direct impacts on oil, gas, and utilities pipelines. 

Indirect Impacts

Indirect impacts would result in the persistence of existing conditions including the 

fragmentation and degradation of the Lake Borgne - MRGO landbridge. These 

conditions would expose buried pipelines thereby increasing the risk of failure or damage 

due to lack of structural stability, anchor dragging, and boat collisions. 

Cumulative Impacts

The no action plan would not contribute to direct cumulative impacts on oil, gas, and 

utilities in the project area. It would contribute incrementally to indirect impacts because 

without restoration projects being implemented, degradation of wetlands and the MRGO 

landbridge would likely increase the exposure of buried infrastructure to impacts. 

4.22.5.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

Pipelines would be relocated by directionally drilling and replacing the pipelines 

underneath the channel. Water and sewer mains, power lines, communication lines and 

cable lines would also require relocation. Relocations would be conducted to minimize 

any impacts to service.

Indirect Impacts

Restoration features could potentially reduce some maintenance costs through increased 

protection of buried pipelines compared to the no action alternative. Alternative B is 

designed to be constructed in a manner that would avoid the need to relocate any 

pipelines in the project area.
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Cumulative Impacts

Alternative B would work synergistically with other anticipated Federal, state, local, and 

private restoration projects to provide more complete protection for the landbridge, which 

would prevent the increase in maintenance and relocation costs for pipelines in and 

around the project area. 

4.22.5.3 Alternative C - MRGO Restoration Plan 7

Direct, indirect, and cumulative impacts associated with alternative C would be the same 

as the impacts from alternative B. 

4.22.5.4 Alternative D - MRGO Restoration Plan 10

Direct, indirect, and cumulative impacts associated with alternative D would be the same 

as the impacts from alternative B. 

4.22.6 Flood Control And Protection Levees

4.22.6.1 Alternative A - No Action Plan

Direct Impacts

The no action alternative would have no direct impacts on flood control or hurricane 

protection levees.

Indirect Impacts

Indirect impacts would result in the persistence of existing conditions including 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 

bank-line erosion and sloughing of the shoreline. 

Cumulative Impacts

Cumulative impacts on flood control and hurricane protection levees include the 

synergistic effect on the no action alternative with the additive combination of coast wide 

impacts to flood control and hurricane protection levees due to wetland loss and 

degradation, as well as the benefits and impacts of other anticipated state and Federal 

projects in the vicinity. Based upon recent sensitivity studies conducted by ERDC in 

support of the LACPR evaluation of comprehensive hurricane protection analysis and 

designs, the loss of wetland areas increases storm surge and wave potential at the 

hurricane protection system. These increases are amplified in areas where the levees 

have irregular shapes and form “pockets” or “funnels”. However, because the acreage of 

wetlands lost, levee heights and alignments, shoreward depths and storm characteristics 

all affect the height of storm surge, it is difficult to determine at this stage of scientific 
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knowledge the effect of wetland loss in the area around Lake Borgne on storm surge. 

Consequently, degradation of the landbridge could expose existing flood control 

infrastructure, including the authorized flood control structure for the HSDRRS located in 

the western portion of the Golden Triangle, more directly to the wave climate of Lake 

Borgne, potentially resulting in higher erosion rates and increased maintenance needs.

4.22.6.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

Wetland creation and shoreline protection would have no direct impact on flood control 

or hurricane protection structures. 

Indirect Impacts

Over the 50-year period of analysis alternative B would protect, create and nourish 

thousands of acres of emergent wetlands that would maintain the Lake Borgne - MRGO 

landbridge. However, increasing the acreage of wetlands in the project area (landbridge 

between Lake Borgne and the MRGO) may not significantly reduce storm surge or wave 

heights in this area. Rather, protecting wetlands (preventing their loss) would have a net 

effect of lowering storm surge and wave heights, to some undetermined level, compared 

to the no action alternative future condition with extensive wetland loss. Although a 

significant increase in wetland acreage in the area could have an effect on significantly 

reducing storm surge and wave heights, the acreage required to accomplish this has not 

been quantified.

Cumulative Impacts

Cumulative impacts to flood control and hurricane protection structures would primarily 

be associated with incremental impacts of similar wetland and protection features. 

Cumulative impacts would be the synergistic effect with the additive combination of 

impacts and benefits for overall net acres created, nourished, and protected by other 

Federal, state, local, and private restoration efforts. Alternative B would work 

cooperatively with those projects to provide more complete protection for the landbridge, 

which would continue to provide the current level of storm surge reduction in the project 

area and vicinity.

The landbridge between Lake Borgne and the MRGO channel would continue to 

fragment and degrade albeit to a lesser degree with implementation of the following 

shoreline protection projects: 

• CWPPRA PO 30;

• the MRGO 2006 Lake Borgne Shoreline Protection, (Doulluts Canal to Jahncke’s 

Ditch), St. Bernard Parish, LA (06-C-0210) project; and 

• 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). 
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4.22.6.3 Alternative C - MRGO Restoration Plan 7

Direct, indirect, and cumulative impacts associated with alternative C would be the same 

as the impacts from alternative B. 

4.22.6.4 Alternative D - MRGO Restoration Plan 10

Direct, indirect, and cumulative impacts associated with alternative D would be the same 

as the impacts from alternative B. 

4.23 ENVIRONMENTAL JUSTICE 

4.23.1 Alternative A - No Action Plan

Direct Impacts

Under the no action alternative, no restoration efforts would take place under this 

authority. Under the no action plan, communities closer to the MRGO would continue to 

be impacted by storm surge and flooding during major storm events, incurring associated 

cost in damage to housing, local economy and commercial structures. Portions of the 

HSDRRS have been built to provide some protection to the population centers of 

Chalmette, Arabi, Poydras, Meraux, and Violet, Louisiana. The communities 

surrounding the MRGO include minority and/or low-income to non-minority and nonlow income populations. All persons, irrespective of race or income status, would be 

equally impacted in a future without project conditions. Therefore, no disproportionately 

high or adverse human health or environmental effects on minority or low-income 

populations would occur. 

Indirect Impacts

No disproportionately high or adverse human health or environmental indirect impacts on 

minority or low-income populations is anticipated under this alternative. 

Cumulative Impacts 

Cumulative impacts of implementing the no action alternative include the additive 

combination of impacts to minority and/or low-income populations from the no action 

alternative and other Federal, state, local, and private restoration efforts. The no action 

alternative would work synergistically with other restoration and protection projects to 

provide critical and essential marsh restoration, which, in turn, would provide some 

protection to communities in the area that may otherwise be damaged due to continued 

erosion and land loss. The no action alternative would not contribute to any additional 

Environmental Justice (EJ) issues rather, the MRGO would contribute toward achieving 

and sustaining a coastal ecosystem that would support and protect the environment, local 

economy and culture of the region. 
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4.23.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts 

Under the alternative B, restoration efforts would take place under this authority. 

Communities closer to the MRGO, as in other coastal communities, would continue to be 

impacted by storm surge and flooding during major storm events, incurring associated 

cost in damage to housing, local economy and commercial structures. However, portions 

of the HSDRRS have been built along the southwestern shoreline of the MRGO, with a 

portion of the HSDRRS levee extending from Mile 47 to Mile 60 that would help to 

protect the population centers of Chalmette, Arabi, Poydras, Meraux, and Violet. 

The communities surrounding the MRGO include minority and/or low-income to nonminority and non-low income populations. The location of the proposed Violet, 

Louisiana Freshwater Diversion would be constructed in an open field which sits between 

two subdivisions that are predominately minority and/or low-income populations. No 

residences or businesses have been displaced due to this alternative. Construction efforts 

such as noise, dust, traffic delays, etc., would temporarily impact those in the immediate 

project vicinity as well as other groups that work or live in the surrounding area. These 

temporary impacts will equally affect all population groups in the project area and, 

therefore, will not result in a disproportionately high adverse impact on minority and/or 

low-income populations in the area. This alternative is not anticipated to adversely 

impact or contribute to existing interior drainage issues expressed by residents of the 

subdivisions. 

Indirect Impacts 

No disproportionately high or adverse human health or environmental indirect impacts on 

minority or low-income populations is anticipated under this alternative. Beneficial 

impacts to minority and/or low-income populations are expected to occur under this

alternative. A recreation development plan is proposed to maintain the community 

cohesion between two subdivisions near Violet, which will be called the Violet, 

Louisiana Park. Additionally, recreational improvements to the New Shell Beach fishing 

area and the Bienvenue Triangle pier near the Martin Luther King Elementary School in 

the Lower-ninth ward are proposed for recreation and educational use. These proposed 

improvements are an additional benefit to the local community, which continues to 

rebuild after Hurricane Katrina. Community groups in the project vicinity would benefit 

from the proposed improvements and experience some impacts with the proposed 

alternative B. Therefore, no disproportionately high or adverse human health or 

environmental effects on minority or low-income populations is anticipated under this 

alternative. 

Cumulative Impacts 

Cumulative impacts of implementing the alternative B include the combination of 

impacts to minority and/or low-income populations from this alternative and other 
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Federal, state, local, and private restoration efforts. Alternative B would work 

synergistically with other restoration, improvement and protection projects to provide 

critical and essential marsh restoration, which, in turn, would provide some protection to 

communities in the area that may otherwise be damaged due to continued erosion and 

land loss. Alternative B would not contribute to any adverse EJ issues, rather, the MRGO 

would contribute toward achieving and sustaining a coastal ecosystem that would support 

and protect the environment, local economy and culture of the region. 

4.23.3 Alternative C - MRGO Restoration Plan 7

Direct Impacts

Under the alternative C, restoration efforts would take place under this authority. 

Communities closer to the MRGO, as in other coastal communities, would continue to be 

impacted by storm surge and flooding during major storm events, incurring associated 

cost in damage to housing, local economy and commercial structures, however, portions 

of the HSDRRS have been built along the southwestern shoreline of the MRGO, with a 

portion of the HSDRRS levee extending from Mile 47 to Mile 60 that would help to 

protect the population centers of Chalmette, Arabi, Poydras, Meraux, and Violet. 

The communities surrounding the MRGO include minority and/or low-income to nonminority and non-low income populations. The location of the proposed Violet, 

Louisiana Freshwater Diversion would be constructed in an open field which sits between 

two subdivisions that are predominately minority and/or low-income populations. No 

residences or businesses have been displaced due to this alternative. Construction efforts 

would result in an increase in noise, dust and cause some traffic delays in the area. These 

temporary impacts will equally affect all population groups in the project areas and, 

therefore, will not result in a disproportionately high adverse impact on minority and/or 

low-income populations in the area. These effects would temporarily impact those in the 

immediate project vicinity as well as other groups that work or live in the surrounding 

area. However, these are only temporary in nature. This alternative is not anticipated to 

adversely impact or contribute to existing interior drainage issues expressed by residents 

of the subdivisions. 

Indirect Impacts

No disproportionately high or adverse human health or environmental indirect impacts on 

minority or low-income populations is anticipated under this alternative. Beneficial 

impacts to minority and/or low-income populations are expected to occur under this 

alternative. A recreation development plan is proposed to maintain the community 

cohesion between two subdivisions near Violet, which will be called the Violet Park. 

Additionally, recreational improvements to the New Shell Beach fishing area and the 

Bienvenue Triangle pier near the Martin Luther King Elementary School in the Lowerninth ward are proposed for recreation and educational use. These proposed 

improvements are an additional benefit to the local community, which continues to 

rebuild after Hurricane Katrina. Community groups in the project vicinity would benefit 
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from the proposed improvements and experience some impacts with the proposed 

alternative C. Therefore, no disproportionately high or adverse human health or 

environmental effects on minority or low-income populations is anticipated under this 

alternative. 

Cumulative Impacts

Cumulative impacts of implementing the alternative C include the combination of 

impacts to minority and/or low-income populations from this alternative and other 

Federal, state, local, and private restoration efforts. Alternative C would work 

synergistically with other restoration, improvement and protection projects to provide 

critical and essential marsh restoration, which, in turn, would provide some protection to 

communities in the area that may otherwise be damaged due to continued erosion and 

land loss. Alternative C would not contribute to any adverse EJ issues, rather, the MRGO 

would contribute toward achieving and sustaining a coastal ecosystem that would support 

and protect the environment, local economy and culture of the region. 

4.23.4 Alternative D - MRGO Restoration Plan 10

Direct Impacts

Direct impacts would be similar to alternative C. Therefore, no disproportionately high 

or adverse human health or environmental effects on minority or low-income populations 

is anticipated to occur.

Indirect Impacts

Indirect impacts would be similar to alternative C. Therefore, no disproportionately high 

or adverse human health or environmental effects on minority or low-income populations 

is anticipated to occur. 

Cumulative Impacts

Cumulative impacts would be similar to alternative C. Therefore, no disproportionately 

high or adverse human health or environmental effects on minority or low-income 

populations is anticipated to occur. 
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4.24 HISTORIC AND CULTURAL RESOURCES 

4.24.1 Alternative A - No Action Plan

Direct Impacts

The no action alternative would have no direct beneficial or adverse impacts on historic 

and cultural resources; however, adverse indirect and cumulative impacts would result 

from the no action alternative as follows. 

Indirect Impacts

Without implementation of ecosystem restoration measures, future conditions would 

include continued conversion of current marsh to open water habitats, continued bankline 

erosion and sloughing of the shoreline. The erosion caused by natural forces and human 

activity 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. 

Cumulative Impacts

Alternative A would not cause any direct impacts and, therefore, would contribute to 

cumulative direct impacts to historic and cultural resources. Without any restoration 

projects proposed, the no action alternative would indirectly contribute to cumulative 

impacts through the continuation of bankline and shoreline erosion. 

4.24.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

Only one archaeological site could be affected by this alternative. Deposition of dredged 

material on this site would increase the rate of subsidence and the disappearance of this 

site from the archaeological record. National Register eligible sites would either have to 

be avoided or adverse effects would have to be mitigated. A variety of mitigative 

measures are possible, ranging from data recovery to other types of documentation. 

Mitigation could take place at the site directly affected or could be concentrated at any 

one site. Decisions on mitigative strategies would be made under a Memorandum of 

Agreement among the CEMVN, the Louisiana State Historic Preservation Officer 

(SHPO) and any interested Indian groups. Sites unevaluated for National Register 

eligibility would either have to be avoided or further research would be carried out in 

order to determine National Register eligibility.

Effects to submerged resources and borrow dredging is unknown. Survey of flotation 

channels and shoreline protection using sidescan sonar, magnetometer and subbottom 

profiler has not identified any submerged archaeological or nautical resources. Survey of 

offshore borrow areas will be performed using sidescan sonar and magnetometer.
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Indirect Impacts

Implementation of ecosystem restoration measures under alternative B could work to 

reduce continued conversion of current marsh to open water habitats, continued bankline 

erosion and sloughing of the shoreline. The erosion caused by natural forces and human 

activity 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. 

Cumulative Impacts

Previous projects along Lake Borgne (Gagliano et al., 1975; Heller et al., 2009; Jones and 

Franks 1993; Labadia et al., 2007; Warren, 2004; Wiseman et al., 1979) have identified 

cultural resources along natural streams and along the shoreline of lakes as being the 

areas with the highest probability of finding archaeological and historic sites. While 

there have been many projects conducted in the MRGO region, the construction of all 

have failed to have an adverse effect on historic properties. None of these projects; 

however, considered the effects on archaeological sites located offshore as this project 

will as none of these projects have attempted to identify offshore sites. Locating and 

treating offshore sites would be a challenge and would take close consultation with the 

Louisiana SHPO and interested tribes. At this time it is impossible to say whether the 

previous projects had an adverse effect on offshore sites.

4.24.3 Alternative C - MRGO Restoration Plan 7

Direct Impacts

As above, deposition of dredged material would increase the rate of erosion. Ridge 

restoration along Bayou La Loutre could also destroy historic properties. However, 

shoreline protection would decrease the amount of erosion on sites located along the edge 

of Lakes Borgne and Pontchartrain. Shoreline protection could adversely affect sites 

located offshore. Offshore sites could be avoided by placing gaps in the rockwork. This, 

however, would increase on shore erosion and could adversely affect shoreline sites. 

Any National Register eligible or unevaluated sites would be treated as under alternative 

B.

Indirect Impacts

Implementation of ecosystem restoration measures under alternative C could work to 

reduce continued conversion of current marsh to open water habitats, continued bankline 

erosion and sloughing of the shoreline. The erosion caused by natural forces and human 

activity 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. 
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Cumulative Impacts

Previous projects along Lake Borgne (Gagliano et al., 1975; Heller et al., 2009; Jones and 

Franks 1993; Labadia et al., 2007; Warren, 2004; Wiseman et al., 1979) have identified 

cultural resources along natural streams and along the shoreline of lakes as being the 

areas with the highest probability of finding archaeological and historic sites. While 

there have been many projects conducted in the MRGO region the construction of all 

have failed to have an adverse effect on historic properties. None of these projects;

however, considered the effects on archaeological sites located offshore as this project 

will as none of these projects have attempted to identify offshore sites. Locating and 

treating offshore sites would be a challenge and would take close consultation with the 

Louisiana SHPO and interested tribes. At this time it is impossible to say whether the 

previous projects had an adverse effect on offshore sites. 

4.24.4 Alternative D - MRGO Restoration Plan 10

Direct Impacts

This is the largest plan and incorporates all elements and additional acreages of the 

previous two alternatives. It has the potential to adversely affect two known sites that 

have an undetermined status for National Register eligibility but are clearly National 

Register eligible. As with the above plans, ridge construction along Bayou La Loutre has 

the potential to adversely affect sites. Deposition of dredged material has the potential to 

increase the rate of subsidence and may bury the sites removing them from the 

archaeological record. Offshore rock placement and the excavation of floatation channels 

may adversely affect off shore sites. Excavation of off shore borrow areas may adversely 

affect historic shipwrecks. As with alternative C, the construction of shoreline protection 

would protect sites along the shoreline of Lakes Borgne and Pontchartrain, though it may 

harm offshore sites. Gaps in the rockwork would increase the rate of erosion at those 

locations and decisions may have to be made as to whether to protect shore line sites 

while damaging sites that are not located off shore.

Indirect Impacts

Implementation of ecosystem restoration measures under alternative D could work to 

reduce continued conversion of current marsh to open water habitats, continued bankline 

erosion and sloughing of the shoreline. The erosion caused by natural forces and human 

activity 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. 

Cumulative Impacts

Previous projects along Lake Borgne (Gagliano et al., 1975; Heller et al., 2009; Jones and 

Franks 1993; Labadia et al., 2007; Warren, 2004; Wiseman et al., 1979) have identified 

cultural resources along natural streams and along the shoreline of lakes as being the 

areas with the highest probability of finding archaeological and historic sites. While 
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there have been many projects conducted in the MRGO region the construction of all 

have failed to have an adverse effect on historic properties. None of these projects, 

however considered the effects on archaeological sites located offshore as this project 

will as none of these projects have attempted to identify offshore sites. Locating and 

treating offshore sites would be a challenge and would take close consultation with the 

Louisiana SHPO and interested tribes. At this time it is impossible to say whether the 

previous projects had an adverse effect on offshore sites. The proposed project will have 

little if no effect on sites along the Mississippi coast, the Pearl River basin or the 

Mississippi Sound.

4.25 RECREATIONAL RESOURCES

4.25.1 Alternative A - No Action Plan

Recreational resources may be affected both positively and negatively by the various 

projects that would be implemented without the MRGO Ecosystem measures. These 

projects include a variety of measures supported by a number of sources including 

CWPPRA, WRDA 2007, and HSDRRS. These projects include freshwater diversions, 

storm water management, marsh creation and nourishment, shoreline protection, barrier 

island restoration, and hydrologic restoration, as well as levees, floodgates, and locks. 

The following discussion addresses potential effects of these projects on recreational 

resources in the project area, which would likely occur if the no action alternative is 

implemented.

Direct Impacts

Freshwater diversion projects at Amite and Convent Rivers and Maurepas Swamp River 

Reintroduction would likely benefit freshwater fishing and waterfowl hunting by 

increasing and enhancing the habitat for freshwater fish species and waterfowl but may 

increase access distance to saltwater fishing as saltwater species migrate towards the Gulf

of Mexico. During high flow periods, turbidity and associated reduction in water quality 

may temporarily reduce both freshwater and saltwater fishing and waterfowl hunting 

opportunities. 

Marsh creation projects for Biloxi marshes, Lake Lery, and the East Orleans Landbridge 

are supported through the CIAP and would likely benefit recreation by providing 

additional habitat for waterfowl and birds, which would enhance opportunities for bird 

watching and hunting. Enhanced marsh habitat would likely also benefit fishing in the 

area as marshes are very productive nursery habitat for fish. However, in the short term, 

during the process of delivering sediment to these areas for building marshes, increased 

levels of turbidity may deter fish from the area, which would be temporarily detrimental 

for recreational fishing in the immediate area. There is a possibility that marsh creation 

could impact boating access if newly created marshes impede familiar and direct access 

routes to fishing areas. 
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The Cypress Marsh Restoration project of the Bayou Bienvenue Central Wetlands is 

supported through the CIAP and designed to restore the natural structure and function of 

the ecosystem in the deteriorating wetlands. The project would rebuild wetlands where 

subsidence has been occurring. Ultimately the project should improve wetland habitat, 

which would benefit recreational fishing. However, as waters become less saline, the 

project may have an effect on saltwater fishing as anglers would have to travel further 

towards the Gulf to catch desired saltwater species. 

A shoreline restoration project in the Lake Lery area supported through CWPPRA (BS16) will be accomplished with measures designed to cause silt and sediment to 

accumulate along shorelines. Restored shorelines will provide additional nursery habitat 

for fish, which would benefit recreational fishing. In limited locations, such projects may 

benefit fishing by providing opportunities for bank fishing. Shoreline restoration would 

provide general benefits by minimizing impacts and protecting important fish and 

wildlife areas from the effects of coastal storm surge. 

Barrier island restoration projects for the Chandeleur Islands supported through 

CWPPRA (PO-27) will similarly benefit the Breton National Wildlife Refuge 

recreational area by potentially reducing damage from storm surge and this would benefit 

recreation by increasing the availability of unique habitat areas for fish and birds. 

Hydrologic restoration projects supported through CWRRPA (PO-24) and designated for 

the Hopedale area will restore natural flows of water. Such projects may benefit 

recreational fishing and bird watching as natural habitats are protected and the numbers 

and diversity of species increases. 

Planned structural measures include improvements of existing levees as part of the 

HSDRRS in New Orleans East, St. Bernard Parish and along the GIWW including areas 

near the Bayou Sauvage National Wildlife Refuge. Excavation of borrow pits near Lake 

Lery to implement structural measures would disturb the sediment in the nearby waters 

which may impact nearby fish habitat; this effect would be temporary. Another potential 

effect of structural measures associated with increased levee heights and associated flood 

protection measure may be reduced access across flood control structures, possibly 

resulting in the need for longer access roads where possible. 

Four major floodgate projects are planned as part of the HSDRRS for the project area. 

Their locations will be at GIWW East, Bayou Bienvenue, Violet Canal/Bayou Dupre, and 

MRGO. When water levels rise more than two feet above sea level, these floodgates are 

to be closed. This could impact access to recreational resources. Boat launches and 

marinas located near these floodgates inside the flood protection system would not be 

able to provide boaters access to the recreational resource outside the flood protection 

system when the gates were closed. In turn, there is the potential for floodgates to restrict 

boaters’ access to recreational resources in the area. However, marinas located inside the 

flood protection system would benefit by having a reduced risk of damage from storm 

surge and experiencing shorter periods with loss of function. 
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Indirect Impacts

Depending upon the success of barrier island restoration efforts, the long term benefit for 

recreation may be increased opportunities for camping on the islands. 

Cumulative Impacts

The cumulative impacts of the other ongoing and reasonably foreseeable projects are 

expected to generally benefit recreation resources. The no action alternative would not 

contribute to cumulative impacts to recreation resources. The risk of destruction of 

recreational infrastructure such as boat ramps, marinas, and fishing piers by storm surge 

would be reduced and habitat areas supporting recreational fish and wildlife resources 

would be enhanced. The closure structure on the MRGO channel near the Bayou La 

Loutre Ridge is affecting the hydrology of the study area. The closure structure near 

Bayou La Loutre has reduced tidal exchange between Lake Borgne and Breton Sound, 

which has reduced salinity in the project area. Additionally, a 2-3 ppt salinity decrease is 

expected within Lake Borgne from freshwater diversion projects, such as the 1,000 cfs 

Hope Canal / Maurepas Diversion; and the 3,000 cfs Blind / Convent River Diversion; all 

of which have been authorized under WRDA 2007, Section 7006. These projects would 

potentially enhance freshwater based recreation, as well as stabilize and maintain 

saltwater based recreation.

4.25.2 Alternative B - MRGO Restoration Plan 2

In summary, alternative B contains a freshwater diversion at Violet that would be 

constructed in year 2027. It includes 29,948 acres of swamp and marsh restoration and 

nourishment throughout the study area, ridge restoration near Bayou La Loutre and 

protection of 35,367 linear feet of shoreline. 

Direct Impacts

Direct impacts to recreational resources include those effects from marsh and swamp 

nourishment, restoration of natural ridges, and shoreline protection measures. Measures 

to stabilize marsh and swamp habitats and to restore deteriorated wetlands would be 

beneficial to recreational fishing by enhancing the sustainability of productive nursery 

habit for this resource. Restoring marsh and swamp improves nursery habitat in the 

interior marshes, which could improve recreational fishing opportunities in offshore 

waters, including Mississippi waters, as juveniles become adults and move to deeper 

waters. By using estuaries during their early life stages, estuarine-dependent species may 

increase survivorship because these habitats offer more protection from predation and 

damaging wave action (Able and Fahay, 1998; Minello, 1993; Minello and Zimmerman, 

1983). Another benefit of estuarine use is access to increased food sources (Turner and 

Brody, 1983; Zimmerman et al, 2000). This need for a protected nursery habitat with 

high local productivity is especially crucial for key commercial and recreational species. 

For example, a study that analyzed 21 years of coastal Louisiana fishery data revealed 

that 9 of the 10 most abundant fishery species collected by trawls (including invertebrates 
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and fishes) were estuarine dependent (Chesney, Baltz, and Thomas, 2000). Without 

access to estuaries during their early life stages, populations of commercial and 

recreational species such as brown shrimp (Farfantepenaeus aztecus), white shrimp 

(Litopenaeus setiferus), blue crab (C. sapidus), Gulf menhaden (B. patronus), Atlantic 

croaker (Micropogonias undulatus), and spotted sea trout (Cynoscion nebulosus) would 

likely decline over time. 

Development of additional marsh and swamp habitat is potentially beneficial for bird 

watching as it would support more birds and increase the diversity of species in the area. 

Waterfowl hunting opportunities may increase due to increased and enhanced freshwater 

habitat. Potential negative effects include temporary turbidity and reduced water quality 

associated with construction of marsh and swamp restoration projects and near borrow 

areas in Lake Borgne during excavation. An effect of marsh creation is the potential for 

reduced access to fishing areas as boaters would have to potentially navigate around 

newly created land area. Restoration of natural ridges would provide stabilization and 

potentially additional habitat for deer, small game, and birds, which would be beneficial 

for hunting and bird watching. Restored ridges would also enhance protection available 

to adjacent swamps and marshes during coastal storms, which would also potentially 

benefit recreational resources. 

As described for the no action alternative, shoreline protection would potentially benefit 

recreational fishing by providing additional productive nursery habitat for fish and can be 

expected to benefit recreation by providing an enhanced level of protection to resource 

lands from effects of coastal storm surge. Potential effects of shoreline protection 

measures would be the temporary displacement of fish populations due to increased 

turbidity both near the shorelines and near borrow areas during project implementation. 

In year 2027, the Violet Canal freshwater diversion would be constructed to discharge 

freshwater into the Central Wetlands, as well as, adjacent open water and wetland areas. 

Review of LDWF Caernarvon data helps to understand the potential effects of a further 

freshening of the project area on recreational fishing. As was discussed in the 

commercial fishery section of this report (citation), LDWF conducted pre- and postconstruction sampling events for the Caernarvon Freshwater Diversion using trawls and 

seines at 21 sampling locations located throughout Breton Sound estuary. Postconstruction sampling showed a decrease in catch per unit effort (CPUE) for brown 

shrimp, while white shrimp showed an increase in CPUE. 

Alternative B may result in impact to recreational shrimping opportunities in the MRGO 

project area. Sampling by LDWF confirmed significant nursery use by juvenile brown 

shrimp (salinity 0.3 to 5 ppt), juvenile white shrimp, and juvenile blue crab (both found in 

salinity as low as 0.2 ppt). Most shrimp thrive in a saltwater environment; however, in 

years with heavy freshwater flow through Caernarvon, brown shrimp catches decreased 

in quantity, while white shrimp catches improved. If there is a long term lowering of 

salinity levels, the brown shrimp may migrate further south into the lower reaches of the 

study area, but white shrimp may thrive closer to the diversion canal. 
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CPUE data was inconclusive for blue crab (citation). Commercial landing data collected 

from local seafood dealers yielded no detectable post-construction effect. However, 

LDWF data on spotted sea trout (aka speckled trout) shows sea trout catch was positively 

related to salinity of stations within the Breton Sound Basin, meaning trout catch was 

higher at the higher-salinity stations within the basin. The Caernarvon Freshwater 

Diversion has resulted in a shift of the optimal harvest zones from the interior marshes to 

more seaward marshes and water bodies, while no significant reductions of either three of 

the species has been recorded. Similar results could be produced from the Violet, 

Louisiana Freshwater Diversion. 

Potential impacts to recreational fisherman could include longer travel distances towards 

the Gulf of Mexico for saltwater based opportunities. In the long term, the distribution of 

saltwater fish species would be further south resulting in longer travel time to reach 

quality saltwater fishing opportunities. On the other hand, decreases in salinity within the 

intermediate marsh zone could potentially enhance conditions for freshwater fish species 

and improve habitat for waterfowl hunting within this portion of the project area. 

While some habitat transition based on decreased salinity levels is anticipated, overall 

benefits associated with marsh creation, and improved aquatic habitat for fisheries and 

waterfowl should result in improved recreational experiences during normal flow 

conditions. In addition, deer and other small game hunting could improve over time due 

to stabilization and improved ridge habitat. 

Indirect Impacts 

Marsh creation projects would likely benefit fishing well beyond the project area as 

marshes are very productive nursery habitat for saltwater fish that live in open waters. 

Depending upon the success of barrier island restoration efforts, the long-term benefit for 

recreation may be increased opportunities for camping on the islands. Potential indirect 

impacts from alternative B would primarily consist of effects on recreational fishing from 

increased turbidity to the water bodies of Lake Borgne and other areas due to dredging 

and placement of borrow material. These impacts could include fish species temporarily 

migrating away from these disturbed conditions. Impacts from the dredging and 

placement of borrow material, including an increase in water turbidity, could last for ten 

years, which is the timeframe of the implementation plan.

Recreational boating would also be affected by the proposed action. Floating pipelines 

would convey dredged material from borrow areas to sites being restored. These 

pipelines would, in some cases, block access to fishing areas and fisherman may have to 

travel longer distances to arrive at their preferred destination. However, canals that are 

frequently used by fisherman would not be blocked as the pipeline crossing these 

locations would be submerged. 
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Cumulative Impacts

The cumulative effects of the alternative B measures together with those of ongoing and 

reasonably foreseeable projects would be beneficial to recreational resources. In 

combination, these projects would create, restore, nourish, and protect important marsh, 

swamp and ridge habitat that would support fish and wildlife and the increase in 

freshwater habitat for waterfowl and birds. This in turn should increase freshwater based 

recreational activities while maintaining and stabilizing saltwater based recreation 

activities. Slowing or reversing land loss and marsh erosion may protect or increase 

recreation resources, such as boat ramps, marinas, and park facilities. 

Specifically, marsh creation measures being proposed in the MRGO Bank Stabilization 

project would increase fish habitat production and therefore have a positive impact on 

recreational fishing resources. Proposed river diversions at Caernarvon and White Ditch 

would increase vegetative growth (especially in fresh habitats) and promote land building 

thereby leading to increased recreation opportunities. 

Cumulative impacts of these projects, along with the closure of the deep-draft MRGO 

channel, would have some level of localized changes to salinity regimes over the Future 

Without-Project conditions. The CWPPRA PO-30 project has been authorized for 

construction, and portions of the original CWPPRA PO-32 project are currently under 

construction as part of the HPS authority. Both of those projects will construct shoreline 

protection features near or adjacent to the features in this plan, and will protect portions 

of the landbridge area between the MRGO channel and Lake Borgne. Most importantly, 

marsh creation in the project area would positively impact recreational fishing and 

hunting. The localized reduction of salinities and the increased acres of freshwater 

habitats would result in a concomitant increase of freshwater recreation activities and a 

decrease of saltwater recreation activities in areas of freshwater reintroduction; as well as 

an overall positive effect on most wildlife-dependent recreation activities. Potential 

impacts would include longer transit distances to the Gulf of Mexico for saltwater based 

opportunities and a temporary reduction in the recreational activity during project 

construction. 

Reducing land loss and possible land building may protect valuable infrastructure that 

supports certain recreation activities. Potentially, cumulative impacts of the above 

mentioned projects could therefore reduce loss of recreation-based infrastructure and 

access thereby decreasing expenses related to relocation, repair, or replacement. 

Together these ongoing, planned and proposed measures for the study area would help to 

maintain, stabilize, and potentially enhance economic benefits relative to recreation. 
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4.25.3 Alternative C - MRGO Restoration Plan 7

Direct Impacts

The anticipated direct impacts of alternative C measures are similar to those described for 

alternative B, but would include additional measures. Alternative C measures add 

shoreline protection to the shores of Lake Borgne and Lake Pontchartrain and more 

extensive shoreline protection near Eloi Bay; and additional marsh nourishment and 

restoration measures in the Central Wetlands and marsh restoration measures along 

Bayou Terre aux Boeufs and Lake Calebass. 

The direct effects of alternative C would be the restoration, and nourishment of 54,506 

acres of swamp and marsh and 314,944 linear feet of shoreline protection. 

These additional measures and resultant increased number of acres of swamp and marsh 

restored and nourished would further improve the habitat for recreational resources in the 

study area and would likely result in an increase in recreational opportunities. It would 

also further enhance protection of recreational resources from the devastating effects of 

storm surge.

Indirect Impacts

The anticipated indirect impacts of alternative C measures would be similar to those

described for alternative B.

Cumulative Impacts

The anticipated indirect impacts of alternative C measures would be similar to those

described for alternative B.

4.25.4 Alternative D - MRGO Restoration Plan 10

Direct Impacts

The anticipated direct impacts of alternative D measures are similar to those described for 

alternative C, plus alternative D additional measures. Alternative D measures add 

shoreline protection along the east bank of the MRGO and more extensive shoreline 

protection near Eloi Bay. 

The direct effects of alternative D would be the restoration, and nourishment of 55,210 

acres (just slightly more than alternative C) of swamp and marsh and 410,567 linear feet 

of shoreline protection. 
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Indirect Impacts

The anticipated indirect impacts of alternative D measures would be similar to those

described for alternative B.

Cumulative Impacts

The anticipated cumulative impacts of alternative D measures would be similar to those 

described for alternative B.

4.26 AESTHETICS

4.26.1 Alternative A - No Action Plan

Direct Impacts

The visual complexity surrounding the MRGO project area is related to its geomorphic 

features including ridge, swamp, marsh, and open water. All of these elements are 

critical systems inclusive to the MRGO study area. Together, all of these elements 

provide pleasing aesthetic scenery to the public from certain points of view, especially 

those areas closest to national parks, national refuges, wildlife management areas or other 

state or nationally designated areas. Direct impacts would evolve from the natural 

processes of the area and the associated changes to these geomorphic structures. 

Indirect Impacts

Indirect impacts can also be derived from the conversion of wetland and marshlands into 

open water. These landscape types provide excellent habitat for a variety of wildlife and 

fisheries. Excellent examples of habitat and their associated wildlife typically provide 

the viewer with focal points and accents (typically made up of both the landscape and the 

wildlife) that make a view shed dynamic, scenic and memorable.

Cumulative Impacts

Cumulative impacts as a result of implementing the no action alternative would include 

the incremental impacts to visual (aesthetic) resources resulting from the past, present, 

and reasonably foreseeable future impacts associated with conversion and loss of marsh, 

wetland and/ or swamps from natural processes and anthropogenic sources. Landscape 

changes would continue to occur in the future as a result of the conversion of marsh, 

wetland, and swamp habitat to open water. Without implementation of wetland creation 

and other protection measures, continued conversion of existing fragmented wetlands to 

open water habitats would persist. Degradation of the land would convert existing view 

sheds of marsh and wetland to more open water views. Because they lack vertical and 

horizontal features, open water does not provide a viewer with the necessary elements of 
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form, line, texture, and color that make a view scenic and memorable such as is provided 

by an expanse of salt marsh. 

4.26.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

Those aesthetic features that are unique to a particular landscape or bring unique design 

to a landscape. These features typically adhere to the basic design elements of form, line, 

texture, color, and repetition. 

The proposed marsh and swamp nourishment and restoration, ridge restoration, and 

shoreline protection projects would work to reclaim former land mass that has been 

converted to a more open water setting. The reclamation would present the possibility of 

creating vertical features (derived from future landscape and vegetation growth) that, 

along with ground features could work to frame the large open water areas beyond. This 

creates an aesthetic setting that is much more desirable and contains the basic design 

elements of form, line, texture, and color. 

Many of the proposed project sites (including the sites at Terre aux Boeufs, Biloxi Marsh, 

and South Lake Borgne) are very remote with few public view sheds. The other sites 

(near Central Wetlands and East Orleans Landbridge) feature residential development 

and major thoroughfares that have access to superior view sheds throughout the project 

area. Highways 300, 624, 46, 39, 90, and 11, along with Interstates 10 and 510 would be 

impacted by the proposed alternative. Land restoration would increase the visual 

characteristics of the project area.

Other impacts result from the proposed Violet, Louisiana Freshwater Diversion. The 

diversion itself would not negatively impact the aesthetics within its project vicinity. 

However; the impacts associated with the potential marsh nourishment and restoration 

would be extremely positive.

Indirect Impacts

Marsh nourishment and restoration projects would increase habitat for wildlife, which 

would be expected to increase wildlife populations. Wildlife typically provides the 

viewer with focal points and accents that make a view shed dynamic, scenic, and 

memorable.

Another indirect impact would be the addition of the recreation features at Bienvenue 

Triangle, Shell Beach, and Violet Diversion. In terms of aesthetics, the designs presented 

in the plan would serve to create space that is memorable and unique and bring people 

into the marsh, wetland, and landscape restoration areas. Viewers would be provided the 

unique opportunity of seeing restoration in progress, while it’s happening. These 

recreational features would also bring unique view sheds to places that would typically 

not be available to the public.
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Cumulative Impacts

Cumulative impacts to aesthetics would be the result of implementing alternative B 

together with ongoing and reasonably foreseeable projects that would restore and 

enhance marsh, wetland, and swamp habitat within the project area. Restoration act ivies

would convert existing view sheds of open water into marsh, wetland, swamp, or a 

variety of landscape types that frame large bodies of open water and use the basic design 

elements of form, line, texture, color, and repetition to create an aesthetically pleasing 

view shed. 

Reasonably foreseeable projects across southern Louisiana include the Louisiana Coastal 

Restoration projects, which include a number of diversion projects, marsh and swamp 

restoration and nourishment, and shoreline protection; CWPPRA projects that include 

diversions, marsh creation, shoreline protection, and siphons; lock replacement projects; 

and operation and maintenance projects, like that found at Bonnet Carrè Spillway. Future 

and existing freshwater diversions for Davis Pond, Caernarvon, Myrtle Grove and White 

Ditch will impact the MRGO study area by providing needed nutrients and fresh water to 

the area, augmenting alternative B objectives. Past, present, and future projects of this 

type would maintain existing and future marshes, thereby diminishing open water areas 

and creating land mass.

4.26.3 Alternative C - MRGO Restoration Plan 7

Direct Impacts

Direct impacts associated with alternative C would be similar to those presented in 

alternative B. Alternative C is planned on a grander scale and includes greater 

implements of marsh nourishment and restoration throughout the project area, increased 

swamp nourishment and restoration in the Central Wetlands area, increased shoreline 

protection on the eastern side of the Biloxi Marshes, as well as other shoreline protection 

along the shores of Lake Borgne, and the eastern shore of Lake Pontchartrain near the 

East Orleans Landbridge and Pearl River Mouth project sites.

The proposed recreational features at Bienvenue Triangle, Violet, Louisiana Freshwater 

Diversion and Shell Beach would have direct impacts to the aesthetic (visual resources) 

of the project areas that they are associated with. Each recreational feature has been 

designed to provide access for viewing and understanding the overall ecosystem 

restoration process, as well as providing sources for recreation to local and regional 

participants. The designs themselves are not overly embellished and, over time, would 

blend in well with their surroundings, creating a haven for nature observation and other 

recreational possibilities that will bring the viewer directly inside the ecosystem itself. 

The view sheds would be unobstructed from these features, adding to the visual quality 

and experience of the three project areas.
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Indirect Impacts

Indirect impacts associated with alternative C would be similar to those presented in 

alternative B. Alternative C is planned on a grander scale and includes more marsh 

nourishment and restoration throughout the project area, increased swamp nourishment 

and restoration in the Central Wetlands project area, increased shoreline protection on the 

eastern side of the Biloxi Marshes, as well as other shoreline protection along the shores 

of Lake Borgne, and the eastern shore of Lake Pontchartrain near the East Orleans 

Landbridge and Pearl River Mouth project sites. These elements, in turn, would 

indirectly work to increase habitat and opportunities for wildlife growth and 

development. 

Cumulative Impacts

Cumulative impacts associated with alternative C would be similar to those presented in 

alternative B.

4.26.4 Alternative D - MRGO Restoration Plan 10

Direct Impacts

Direct impacts associated with alternative D would be similar to those presented in 

alternative B and alternative C. Alternative D is planned on a grander scale and includes 

greater implements of marsh nourishment and restoration throughout the project area. 

This includes new sites on the eastern edge of the Biloxi Marshes and the northern side of 

the East Orleans Landbridge near the Pearl River Mouth. Other features include 

increased shoreline protection on the eastern side of the Biloxi Marshes, Terre aux 

Boeufs and the northern (or eastern depending on point of view) shore of the MRGO 

itself, as well as other shoreline protection that includes breakwaters along the eastern 

shore of Lake Pontchartrain near the East Orleans Landbridge.

Indirect Impacts

Indirect impacts associated with alternative D would be similar to those presented in 

alternative B and alternative C. Alternative D is planned on a grander scale and, as with 

alternative C, includes greater implements of marsh and swamp nourishment and 

restoration, and increased shoreline protection. These elements, in turn, would indirectly 

work to increase habitat and opportunities for wildlife growth and development. 

Cumulative Impacts

Cumulative impacts associated with alternative D would be similar to those presented in 

alternative B and alternative C. 
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4.26.5 Scenic Streams

4.26.5.1 Alternative A - No Action Plan

Direct Impacts

The no action alternative would have no direct adverse or beneficial impacts to the seven 

scenic streams located within the project area in Louisiana. There are no scenic streams 

in the immediate coastal areas surrounding the Mississippi Sound or St. Louis Bay; 

therefore, there would be no direct impacts to scenic streams in Mississippi from the 

continuation of existing conditions under alternative A. 

Indirect Impacts

Under the no action alternative, the continued degradation of marsh habitat would result 

in a gradual decline in overall habitat quality within the study area, which would 

indirectly adversely affect scenic streams in the project areas within Louisiana. The 

continued decline in habitat quality is the result of continued fragmentation of the marsh 

and creation of large open water areas. As the marsh deteriorates, the natural aesthetics 

of a marsh lined bayou transitions to open water with little aesthetic value including an 

eventual loss of the actual channel itself. The eventual result could be the loss of these 

Louisiana scenic streams completely to open water. Because there are no scenic streams 

in the immediate coastal areas surrounding the Mississippi Sound or St. Louis Bay, there 

would be no indirect impacts to scenic streams in Mississippi from the no action 

alternative.

Cumulative Impacts

Cumulative impacts would include the synergistic effect of the no action alternative on 

scenic streams with the additive combination of similar impacts throughout coastal 

Louisiana, as well as the benefits and impacts of other state and Federal projects in the 

vicinity, as detailed in section 2.6.1. Cumulative adverse and beneficial impacts to the 

scenic streams located within the project area in Louisiana would result from the 

implementation of freshwater diversion projects or other programs, such as CWPPRA, 

CIAP, and LCA, within the study area. These projects and programs could have both 

adverse and beneficial impacts to scenic streams by reducing water clarity and 

interrupting flow patterns; however, the introduction of freshwater into the system could 

potentially benefit surrounding marsh habitat by helping to slow the marsh deterioration 

that has plagued the area in the recent past. Without implementation of wetland 

creation/nourishment and shoreline protection features, marsh habitat deterioration would 

continue as land loss and subsidence convert marshes to open water. 
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4.26.5.2 Alternative B - MRGO Restoration Plan 2

Direct Impacts

Direct impacts for alternative B would result from disturbances to the existing habitats 

along scenic streams in Louisiana to create/nourish marsh habitats and construct 

temporary retention dikes and earthen weirs. The majority of the direct detrimental 

impacts would occur during project construction in terms of turbidity, placement of 

material in existing marsh and open water habitats, the construction of retention dikes 

along project sites, and placement and creation of access channels to move material to the 

project sites. These impacts would be temporary and localized. While the aesthetics and 

viewsheds along the scenic streams will be temporarily directly impacted during 

construction, the long-term result would be the overall improvement of habitat necessary 

to create the natural landscapes for which these scenic streams were originally protected. 

Over time, the containment dikes and other earthwork would be removed to allow for the 

reestablishment of natural habitats and viewsheds for scenic streams. 

In the Golden Triangle marsh area where the scenic portion of Bayou Bienvenue is 

located, measure LM1 would include the creation and nourishment of marsh habitat. 

Approximately 3,253 acres of shallow water and 1,064 acres of adjacent areas of existing 

marsh would be filled to an elevation conducive to create marsh and marsh restoration, 

not to exceed +1.25 feet over marsh. To assist in marsh creation and hold in this dredged 

sediment, 595 acres of containment dikes and 538 acres of earthen weirs would be 

created in the area. These temporary earthen dikes would be created along portions of 

Bayou Bienvenue and would directly impact the habitat adjacent to the bayou. A portion 

of these dikes would be constructed along the entire western bank of the scenic portion of 

Bayou Bienvenue and a small section of the eastern bank. The overall goal of measure 

LM1 is to create and nourish viable brackish marsh habitat consistent with historic 

habitats once found in the Golden Triangle marsh area. 

Within the Central Wetlands area, there would be six measures constructed under 

alternative B. Of these six measures, only four (CC1, CC2, CC5, and CC6) are adjacent 

to or in proximity to designated scenic streams. These four measures would create a total 

of 2,390 acres of swamp. Another 5,303 acres of swamp would be nourished by the four 

project measures. These measures would include the construction of retention dikes and 

earthen weirs, which would impact 691 acres of existing marsh habitat. 

Measure CC1 in the area north of the existing Violet Canal along the Forty Arpent Levee 

consists of the restoration of approximately 1,020 acres of shallow water to be filled to an 

elevation conducive to swamp creation and approximately 935 acres of existing marsh to 

be restored by placement of a thin layer of sediment not to exceed +1.0 foot over marsh. 

This measure would include 205 acres of retention dikes, a portion of which runs parallel 

to the Violet Canal. Along with potential impacts to the Violet Canal, a large portion of 

Bayou Chaperon is located within the area affected by measure CC1. Potential impacts 

could include a reduction in access, reduced water quality, and sedimentation. Further 

engineering analysis is being performed to determine the length and cost for the 
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construction of additional retention dikes along either side of Bayou Chaperon. The 

retention dikes would prevent effluent from entering the scenic stream and reduce 

potential impacts. 

With measure CC2, approximately 250 acres of shallow water would be filled to an 

elevation conducive to swamp creation and approximately 250 acres of existing marsh in 

the area would be restored by placement of a thin layer of sediment not to exceed +1.0 

foot over marsh. A portion of the 66 acres impacted by the construction of retention 

dikes is in proximity to the northern portion of Bayou Chaperon. 

Measure CC5 is located in the area south of the Violet Canal along the alignment of the 

Forty Arpent Levee and the Chalmette Loop Levee. Approximately 1,120 acres of 

shallow water would be filled to an elevation conducive to swamp creation and 

approximately 1,550 acres of existing marsh would be restored by placement of a thin 

layer of sediment not to exceed +1.0 foot over marsh. Measure CC5 would also have 216 

acres of impact relevant to the construction of retention dikes. A portion of these dikes 

run parallel to the Violet Canal and could potentially result in direct impacts to the scenic 

stream. These impacts include the direct loss of the 216 acres of habitat that parallel the 

Violet Canal as well as visual impacts from the natural habitat being converted to an 

earthen dike to hold in the fill material. 

With measure CC6, approximately 2,568 acres of existing marsh would be restored by 

placement of a thin layer of sediment not to exceed +1.0 foot over marsh in an effort to 

restore swamp habitat. This measure is not expected to directly impact any scenic 

streams. While this measure is not expected to directly impact any scenic streams, both 

Pirogue Bayou and Terre Beau Bayou are in close proximity and could have water 

quality impacts during restoration work as discussed under indirect impacts. Measure 

CC6 would also have 162 acres of impact relevant to the construction of retention dikes. 

Due to the absence of any scenic streams in the immediate coastal areas surrounding the 

Mississippi Sound or St. Louis Bay, there would be no direct impacts to scenic streams in 

Mississippi from construction of alternative B. 

 

Indirect Impacts

Indirect impacts of wetland creation and nourishment and retention dike construction 

would include temporary increases in turbidity levels and sedimentation in scenic 

streams. Other indirect impacts primarily consist of long-term improvement to the scenic 

streams by preserving and re-establishing the natural habitats that both protect and add to 

the aesthetic qualities of this resource. By protecting these critical marsh habitats, 

including the Biloxi Marsh and Eastern Orleans Landbridge, alternative B would help 

prevent the degradation of marsh habitat in the areas surrounding scenic streams in the 

project areas within Louisiana. Due to the absence of any scenic streams in the 

immediate coastal areas surrounding the Mississippi Sound or St. Louis Bay, there would 

be no indirect impacts to scenic streams in Mississippi from construction of alternative B. 
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Cumulative Impacts

Cumulative impacts to the seven scenic streams in the project area would primarily be 

associated with combined impacts of wetland creation, nourishment, and shoreline 

protection projects. Cumulative impacts would include the overall effect with the 

additive combination of impacts and benefits for overall net acres created, nourished, and 

protected by other Federal, state, local, and private restoration efforts as summarized in 

section 2.6.1. Alternative B, combined with those projects, would provide more 

complete protection of marsh habitat that would preserve the integrity and aesthetic 

quality of the scenic streams in the project area. 

While the overall cumulative impacts from alternative B should have a net positive 

benefit on scenic streams, there are several external factors that could offset a portion of 

these benefits. The project area in southeast Louisiana is located along the Gulf Coast 

and is susceptible to tropical cyclone activity every year from June through November. 

There is a moderate risk every year for a tropical storm or hurricane to impact the area 

causing land loss and inundation with saline waters that would have an immediate and 

long-term impact to the restoration features and project area as a whole. A second key 

factor in the potential cumulative effects to the region is from the oil and gas industry. 

Oil and gas exploration, production, and transportation are a major economic driver in the 

project area and coastal Louisiana. A comprehensive list of future projects would be very 

difficult to develop due to the private and rapidly changing nature of the industry. 

However, it is prudent to assume the potential exists for future adverse impacts to scenic 

streams from dredging, due to the development of oil and gas infrastructure including 

pipelines, platforms, or exploration activities, in the project area. 

4.26.5.3 Alternative C - MRGO Restoration Plan 7

Alternative C shares all of the restoration measures discussed for alternative B with the 

addition of measures CM3 and CM4, which are described below. 

Direct Impacts

Measure CM3 in the area north of Bayou Dupre and south of the MRGO consists of the 

restoration of approximately 300 acres of shallow water to be filled to an elevation 

conducive to marsh creation and approximately 215 acres of existing marsh to be restored 

by placement of a thin layer of sediment not to exceed +1.0 foot over marsh. The 

measure would include 154 acres of impacts relevant to retention dikes and would have 

an additional 54 acres of impacts from earthen weirs. A portion of the retention dikes 

parallel Bayou Dupre from its juncture with the Violet Canal north to its juncture with 

Bashman Bayou. Along with these potential impacts to Bayou Dupre, one of the areas of 

marsh creation and nourishment runs the length of Bashman Bayou to the east and would 

also have two sections of earthen weir constructed parallel to the bayou. Potential 

impacts to Bashman Bayou could include reduction in access, reduced water quality, and 

sedimentation of the channel. While the reduction in access and reduced water quality 

would be temporary during construction, the sedimentation of the channel would be a 
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permanent impact that may require dredging of the channel once construction is 

complete. 

With measure CM4, approximately 98 acres of shallow water would be filled to an 

elevation conducive to marsh creation and approximately 129 acres of existing marsh 

would be restored by the placement of a thin layer of sediment not to exceed +1.0 foot 

over the marsh. A portion of the 132 acres impacted by the construction of retention 

dikes runs parallel to portions of Bayou Dupre, Pirogue Bayou, and Terre Beau Bayou. 

All of the areas of marsh creation and nourishment are located adjacent to portions of 

Bayou Dupre, Pirogue Bayou, and Terre Beau Bayou. Potential impacts to these scenic 

streams could include reduction in access, reduced water quality, and sedimentation of 

the channel. While the reduction in access and reduced water quality would be 

temporary during construction, the sedimentation of the channel would be a permanent 

impact that may require dredging of the channel once construction is complete.

Due to the absence of any scenic streams in the immediate coastal areas surrounding the 

Mississippi Sound or St. Louis Bay, there would be no direct impacts to scenic streams in 

Mississippi from construction of alternative C. 

Three recreational sites have been identified for construction as part of this alternative. 

All three recreation features are detailed in appendix W. Due to the fact that these 

features are located over five miles from the scenic streams, no impacts from the 

recreation features are expected.

Indirect Impacts

Indirect impacts associated with alternative C would be similar to those described under 

alternative B. 

Cumulative Impacts

Cumulative impacts associated with alternative C would be similar to those described 

under alternative B. 

4.26.5.4 Alternative D - MRGO Restoration Plan 11

Alternative D shares all of the same restoration measures as discussed for alternative C.

Direct Impacts

Direct impacts associated with alternative D would be the same as those described under 

alternative C. 
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Indirect Impacts

Indirect impacts associated with alternative D would be similar to those described under 

alternative B. 

Cumulative Impacts

Cumulative impacts associated with alternative D would be similar to those described 

under alternative B.

4.27 FLOODPLAINS

4.27.1 Alternative A - No Action Plan 

Direct Impacts

Under the no action alternative, there would be no direct impacts to the floodplain. A 

large portion of the project area is coastal marsh habitat which would continue to degrade 

and increase the flood risk to developed portions of the floodplain. 

Indirect Impacts

Flood protection and restoration programs discussed in chapter 2 would continue to 

develop or remain in place under existing conditions in order to ensure protection of 

Louisiana’s and Mississippi’s coastal and natural resources. Other reasonably 

foreseeable efforts that would likely improve and restore critical habitat include Federal, 

state, local and private ecosystem restoration projects. These projects include diversions 

and restoration which would have an effect on the floodplain. 

Cumulative Impacts

Cumulative impacts would be the synergistic effect of projects requiring development in 

the floodplain throughput coastal Louisiana, and the potential floodplain impacts and 

benefits from other Federal, state, and local projects in the vicinity, as detailed din 

chapter 2. 

4.27.2 Alternative B – MRGO Restoration Plan 2

Direct Impacts

All of the restoration features involve marsh or swamp restoration and nourishment, 

shoreline protection, and ridge restoration and would be developed in uninhabited areas 

outside of the floodplain areas that are managed by the floodplain coordinator and fall 

under the jurisdiction of EO 11988. 
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The proposed Violet, Louisiana Freshwater Diversion would be constructed in the 

vicinity of Violet, Louisiana. The diversion feature would connect the Mississippi River 

to the MRGO and Lake Borgne and would be located in portions of the 500 and 100-year 

floodplain. The channel that would be created as part of the diversion would have guide 

levees on either side and would not pose a flood risk to any of the communities or 

developments within the floodplain. Approximately 529 acres within the Hurricane 

Protection System would be converted to floodway as part of the construction of the 

diversion canal. 

Indirect Impacts

Programs discussed in chapter 2 would continue to develop or remain in place under 

existing conditions in order to ensure protection of Louisiana’s and Mississippi’s coastal 

and natural resources. Other reasonably foreseeable efforts that would likely improve 

and restore critical habitat include Federal, state, local and private ecosystem restoration 

projects. These projects include diversions and restoration which would have an effect 

on the floodplain. 

Cumulative Impacts

Cumulative impacts would be the synergistic effect of projects requiring development in 

the floodplain throughput coastal Louisiana, and the potential floodplain impacts and 

benefits from other Federal, state, and local projects in the vicinity, as detailed din 

chapter 2. 

4.27.3 Alternative C – MRGO Restoration Plan 7

Direct Impacts

Direct impacts to floodplains associated with alternative C would be the same as the 

impacts from alternative B. 

Indirect Impacts

Indirect impacts to floodplains associated with alternative C would be the same as the 

impacts from alternative B. 

Cumulative Impacts

Cumulative impacts to floodplains associated with alternative C would be the same as the 

impacts from alternative B.
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4.27.4 Alternative D – MRGO Restoration Plan 10

Direct Impacts

Direct impacts to floodplains associated with alternative D would be the same as the 

impacts from alternative B. 

Indirect Impacts

Indirect impacts to floodplains associated with alternative D would be the same as the 

impacts from alternative B. 

Cumulative Impacts

Cumulative impacts to floodplains associated with alternative D would be the same as the 

impacts from alternative B. 

4.28 ANY ADVERSE ENVIRONMENTAL IMPACTS WHICH 

CANNOT BE AVOIDED SHOULD THE TENTATIVELY 

SELECTED PLAN BE IMPLEMENTED

The tentatively selected plan includes conversion of 17,352 acres of open water and 

fragmented marsh to freshwater, brackish, and saline marsh habitat and nourishing 

26,836 acres of existing marsh habitat. Approximately 4,225 acres of open water would 

be converted into cypress swamp and an additional 6,093 acres of swamp would be 

nourished. Ridge restoration would consist of 17,500 feet, approximately 54 acres, of 

ridge being increased in elevation. Approximately 314,944 linear feet of shoreline 

protection measures consisting of rock breakwater would be implemented to protect 

marsh habitat and reduce shoreline erosion. However, in order to facilitate the 

construction of these restoration measures some adverse impacts, while only temporary, 

could occur within the project area. Lake Borgne is designated as critical habitat for the 

endangered Gulf Sturgeon and borrow material for these restoration measure would need 

to be taken from the lake bottom. Lake Borgne includes some sandy bottoms that are the 

preferred foraging habitat for these species. These areas were surveyed and excluded 

from consideration as potential borrow sources. Approximately 152 mcy of borrow 

material or roughly 15,724 acres of water bottom could be disturbed for the creation of 

borrow pits. This borrow material would come from various sources in Lake Borgne and 

surrounding water bodies. 

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 implementation plan actually spans 14 years with a 

monitoring period in place for two years after test borrow pits are dredged. A cycle does 

not necessarily last for 365 days and some features could take 12 to 16 months to 
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complete. The borrow plan limits dredging to one lobe of Lake Borgne per 

implementation cycle; therefore, isolating increased turbidity to one lobe of the lake. A 

minimum of 365 days of dredging would occur in one lobe before switching to the other 

lobe. 

The tentatively selected plan would assist in the long-term productivity of the Lower 

Pontchartrain Basin ecological community by improving the water quantity, water 

quality, nutrients, and sediments in the basin. This, in turn, would facilitate the growth 

and productivity of emergent marsh and the invertebrates, fish, and wildlife that utilize 

these habitats. The tentatively selected plan would also result in enhancing the long-term 

productivity of the natural communities throughout the region. These long-term 

beneficial effects of the tentatively selected plan outweigh the adverse environmental 

impacts resulting primarily from project construction. 

As part of the restoration efforts, the construction of a freshwater diversion near Violet, 

LA is also being considered. While additional study is needed to improve decisions 

regarding where, when, and how to provide a freshwater diversion, construction of the 

Violet, Louisiana Freshwater Diversion channel (Alternative 1 location) would have 

direct impacts on 118 acres, which includes 59 acres of brackish marsh and open waters 

within the Central Wetlands area. The Violet, Louisiana Freshwater Diversion would 

result in long-term changes in water quality and salinity levels in the Central Wetlands 

area, Biloxi Marsh, and West Mississippi Sound. These changes would restore the 

system to pre-existing conditions thought to have occurred before construction of the 

MRGO. The Alternative 1 location for the diversion would be constructed in an open 

field which sits between two subdivisions that are predominately minority and/or lowincome populations. Construction efforts such as noise, dust, traffic delays, etc., would 

temporarily impact those in the immediate project vicinity as well as other groups that 

work or live in the surrounding area. Enhancement measures are proposed in order to 

maintain the community cohesion between the two subdivisions. 

4.29 ANY IRREVERSIBLE AND IRRETRIEVABLE 

COMMITMENTS OF RESOURCES INVOLVED IN THE 

IMPLEMENTATION OF THE TENTATIVELY 

SELECTED PLAN

NEPA requires that environmental analysis include identification of “any irreversible and 

irretrievable commitments of resources which would be involved in the tentatively 

selected plan should it be implemented.” Irreversible and irretrievable resource 

commitments are related to the use of nonrenewable resources and the effects that the use 

of these resources have on future generations. Irreversible effects primarily result from 

use or destruction of a specific resource (e.g., energy and minerals) that cannot be 

replaced within a reasonable time frame. Irretrievable resource commitments involve the 

loss in value of an affected resource that cannot be restored as a result of the action (e.g., 

extinction of a T&E species or the disturbance of a cultural site). 
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The tentatively selected plan would result in the direct and indirect commitments of 

resources. These would be related mainly to construction components. Energy typically 

associated with construction activities would be expended and irretrievably lost under all 

of the alternatives excluding the no action alternative. Fuels used during the construction 

and operation of dredging equipment and barges would constitute an irretrievable 

commitment of fuel resources.

For the tentatively selected plan, most resource commitments are neither irreversible nor 

irretrievable. The dredging of borrow material from Lake Borgne is considered 

reversible although it is anticipated that the natural infilling of the borrow pits may take 

several years. Given the hydrodynamics of the lake and similar pits constructed in Lake 

Pontchartrain, there is little accretion and sediment movement in the lakes. Benthic 

communities would be removed and lost along with the sediment during dredging 

operations. Benthic communities would also take several years to recover. Fish and 

plankton would be entrained in the dredge during the dredging of the borrow areas. 

These losses will be irretrievable. However, most impacts to fish and plankton are short 

term and temporary and would only occur during dredging and construction activities. 

For example, access channels that would be dredged and retention dikes that are 

constructed would be restored to natural conditions after construction. 

While additional study is needed to improve decisions regarding where, when, and how 

to provide a freshwater diversion, a few impacts resulting from construction of the Violet, 

Louisiana Freshwater Diversion structure (Alternative 1 location) are long-term and 

permanent including the conversion of 118 acres, which includes 59 acres of brackish 

marsh in the Central Wetlands area, to the diversion canal. Other impacts including 

disruption of community cohesion that may have a longer effect can be reduced through 

appropriate enhancement measures and best management practices. There are no 

irreversible or irretrievable commitments of resources which would preclude formulation 

or implementation of reasonable alternatives for this project. 

4.30 RELATIONSHIP BETWEEN LOCAL SHORT-TERM 

USES OF MAN’S ENVIRONMENT AND THE 

MAINTENANCE AND ENHANCEMENT OF LONGTERM PRODUCTIVITY

NEPA Section 102(2)(c)(iv) and 40 CFR 1502.16 requires that an EIS include a 

discussion of the relationship between short-term uses of the environment and the 

maintenance and enhancement of long-term productivity. This section describes how the 

tentatively selected plan would affect the short-term use and the long-term productivity of 

the environment. 

For the tentatively selected plan, “short-term” refers to the temporary phase of 

construction of the proposed project, while “long-term” refers to the operational life of 

the proposed project and beyond. Chapter 4 of this document evaluates the direct, 

indirect, and cumulative effects that could result from the tentatively selected plan. 
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Construction of the tentatively selected plan would result in short-term constructionrelated impacts within parts of the project area and would include to some extent 

interference with local traffic, minor limited air emissions, and increases in ambient noise 

levels, disturbance of fisheries and wildlife, increased turbidity levels, lower DO, and 

disturbance of recreational and commercial fisheries. These impacts would be temporary 

and would occur only during construction, and are not expected to alter the long-term 

productivity of the natural environment. 

The tentatively selected plan would assist in the long-term productivity of the Lower 

Pontchartrain Basin ecological community by improving the water quantity, water 

quality, nutrients, and sediments. This in turn would facilitate the growth and 

productivity of emergent marsh and the invertebrates, fish, and wildlife that utilize these 

habitats. The tentatively selected plan would also result in enhancing the long-term 

productivity of the natural communities throughout the region. These long-term 

beneficial effects of the tentatively selected plan would outweigh the impacts to the 

environment resulting primarily from project construction. 

With an increase in the amount wetland habitat and increase in wetland habitat quality, 

fish populations would experience beneficial impacts. These improvements in 

productivity would beneficially impact long-term commercial and recreational fishing in 

the study region. 
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CHAPTER 5: PUBLIC INVOLVEMENT

5.1 GENERAL

The U.S. Army Corps of Engineers (USACE) invites full public participation in the 

National Environmental Policy Act (NEPA) process and promotes open communication 

between the public and the USACE for better decision-making. All persons and 

organizations that have an interest in the tentatively selected plan, including minority, 

low-income, disadvantaged, and Native American groups, are urged to participate in the 

NEPA environmental analysis process. The scoping process is useful in helping the 

USACE focus the Environmental Impact Statement (EIS) on issues of importance to the 

public and other interested agencies and organizations. 

The President’s Council on Environmental Quality (CEQ) guides public participation 

opportunities with respect to the tentatively selected plan on environmental regulations. 

Compliance guidance for NEPA is contained in Title 40 of the Code of Federal 

Regulations (CFR), Parts 1500 through 1508, and in the USACE regulations 33 CFR 230 

and 325, Environmental Quality and Procedures for Implementing NEPA. These 

regulations provide for six major elements of public participation available in conjunction 

with preparation of this EIS including: 

1) Notice of Intent (NOI), 

2) Scoping

3) Public review of the Draft EIS (DEIS), 

4) Public hearing on the DEIS, 

5) Public release of the Final EIS (FEIS) and 30-day waiting period, and 

6) Publication of the Record of Decision (ROD). 

5.2 AGENCY COORDINATION

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 Louisiana and 

Mississippi participated in the discussions.

Agencies were invited by email on August 27, 2008, and by letter dated October 23, 

2008, to participate in the study as cooperating agencies and provide a team member for 

the Project Delivery Team (PDT) and Habitat Evaluation Team (HET). Informal agency 

coordination meetings occurred throughout the period when the Preliminary Draft 

Environmental Impact Statement (PDEIS) was being prepared to discuss issues and 

clarify information.

Preparation of the MRGO Ecosystem Restoration Plan Feasibility Report (“MRGO” 

former Mississippi River Gulf Outlet Navigation Channel) and DEIS has been 
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coordinated with appropriate Congressional, Federal, state, and local interests, as well as 

environmental groups and other interested parties as listed below: 

• United States Fish and Wildlife Service, Louisiana and Mississippi 

• United States Environmental Protection Agency, Region VI 

• National Marine Fisheries Service, Louisiana and Mississippi

• Natural Resources Conservation Service, Louisiana 

• State Historic Preservation Officer

• Advisory Council on Historic Preservation, 

• Louisiana’s Governor’s Executive Assistant for Coastal Activities

• Louisiana Department of Wildlife and Fisheries

• Louisiana Department of Natural Resources, Coastal Management Division 

• Louisiana Department of Natural Resources, Coastal Restoration Division 

• Louisiana Department of Environmental Quality 

• Mississippi Department of Environmental Quality

• Mississippi Department of Marine Resources

• Lake Pontchartrain Basin Foundation (LPBF)

• American Rivers

5.3 PUBLIC INVOLVEMENT ACTIVITIES TO DATE

Throughout the study, public and stakeholder involvement was encouraged and 

facilitated. Several stakeholder forums were facilitated by the USACE, including a 

Central Wetlands Forum, Recreation Forum, LPBF Ridge Restoration Workshop, and St. 

Bernard Parish Central Wetlands Workshop. Other stakeholder engagements included 

participation in quarterly non-Government Organization meetings and small group 

meetings. A full discussion of stakeholder and public involvement activities, as related to 

the feasibility report and DEIS is included in the accompanying MRGO Ecosystem 

Restoration Plan Feasibility Report, Chapter 5. 

5.3.1 Study Website

The MRGO website, http://www.mrgo.gov, is dedicated to not only the MRGO 

Ecosystem Restoration Feasibility Report, but many other aspects, including the MRGO 

De-Authorization Study and MRGO Navigation Channel Closure. 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, and 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. A comment button on the left navigation 

panel is provided for the public to submit comments. The site is updated as new products 

and reports are released. 
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5.3.2 Scoping

Scoping was discussed in chapter 1, section 1.4.4. The scoping comment period began 

with the filing of the NOI and continues through release of the DEIS for public comment. 

Public scoping meetings were held on November 3, 2008, in Chalmette, Louisiana and 

November 6, 2008, in Waveland, Mississippi. Higher participation was received in 

Chalmette, Louisiana 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 report is available in appendix A. 

5.3.3 Summary of Major Scoping Issues

The top five recurring themes account for 52 percent of the comments and are briefly 

described below:

5.3.3.1 Use Sediment Diversions for Wetland Restoration

Of the 379 occurrences, 13.5 percent suggested that sediment diversions are needed for 

restoration of the marshes and wetlands. Comments specifically mention the Biloxi 

Marsh and the Central Wetlands. Sediment from the Mississippi River was suggested as 

a source by several attendees, (e.g., “Mississippi River sediment should be routed to 

marsh restoration.”) One commenter asked why more marshes are not planned, such as 

in the White Ditch area. The subject matter expert explained that there are limited areas 

suitable for borrowing marsh material.

Several comments indicated that sediment, and not just freshwater, must be moved and 

managed. (e.g., “Ensure that the diversion projects actually moved sediment and not just 

freshwater and that the sediment is managed so it doesn’t all go to one place, but it goes 

to where it needs to go to restore the marshes.” and “Must capture the bottom water 

instead of just the effluent.”) 

The use of spillways was mentioned as being necessary to build the marshland (e.g., 

“Spillways only way to re-build Marsh along with sediment,” and “Spillways build 

marshland.”). One individual suggested to “Pump material into the wetlands using huge 

hopper dredges such as the WB Fairway (59,000 m3

) to restore the wetlands.” 

5.3.3.2 Restore the Ecosystem to Pre-Disturbance/Historical 

Condition

The next most dominant theme, which appeared in 11.3 percent of the comments, 

emphasized the need to restore the ecosystem to the state that existed prior to the MRGO. 

As stated by one person, “Restoration goal should be to make area like before Corps 

built MRGO.” One commenter suggested, “Use aerial documentation of pre-MRGO to 

establish baseline of restoration.” Comments of record received from American Rivers 
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and the Department of the Interior - U.S. Fish and Wildlife Service (USFWS) reiterated 

the need to restore the ecosystem to pre-MRGO conditions. 

Of the 43 comments regarding the ecosystem, 50 percent specifically mention cypress 

trees or forests. There was also concern about invasive plants caused by the ecosystem 

imbalance, such as water hyacinths and salvia.

5.3.3.3 Restoring the First Line of Hurricane Defense for Public 

Safety is a Priority

Prioritizing public safety by restoring the first line of hurricane defense appeared in 10.6 

percent of the comments, almost as frequently as the top two occurring themes. As one 

comment indicated, “public safety is priority #1.” Almost all of the comments reflected 

the opinion that the barrier islands were the first line of defense. The barrier islands were 

mentioned specifically seven times. Other lines of defense mentioned include marshes 

and wetlands, vegetation, reefs, and the total ecosystem. Comments indicated that levees 

were the third line of defense.

More specifically, from one of the breakout groups came the comment: “Several times it 

was brought up that we need to address the first line of defense at the south end of the 

basin and in the Chandeleur Islands area. In that area they talk specifically about drop 

armoring, marsh creation.”

5.3.3.4 Focus on Restoring Flow of Water (Hydrology)

Hydrology appeared in 8.7 percent of the comments. This was sometimes stated 

succinctly, as in “restore natural hydrology,” but more frequently appeared in 

combination with other themes, such as maintaining proper freshwater and salinity levels. 

One individual saw this as a priority: “If I had to choose an issue, I would say get more 

freshwater back into the marshes – addressing saltwater intrusion should be the priority 

for the Corps.” 

Suggestions included: “slow down the water as it flows into the channel—mud should be 

dropped at the end of the MRGO;” “fill the canal that runs parallel to the channel with 

rock in order to truly solve the problem because the flow of water will be diverted into 

that canal when the channel is closed;” and “freshwater diversions should be pulsed so 

that the salinity of the water is not affected to a point where it’s detrimental to the area.”

There were also some concerns, questions, and proposals for the use of treated 

wastewater for diversions.

5.3.3.5 Implement/Incorporate Existing Plans

Participants indicated in 7.9 percent of theme occurrences that they were anxious for 

existing plans to be implemented or incorporated. Typical of the comments grouped 
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under this theme were, “I believe we should be taking the plans that already exist, 

prioritizing our steps and putting the plan into action.” 

Also included in this theme were comments indicating the need for a comprehensive 

approach, such as, “a comprehensive systemic approach is needed, rather than the 

project-by project approach they are currently seeing.” 

Of the top five themes, this is the most negative in tone, since some of the comments 

indicated a level of frustration typified by statements such as, “Studies have been done 

already, why not just refer to them?”

5.3.4 Environmental Justice Public Outreach Efforts

An Environmental Justice (EJ) meeting was held at W. Smith Elementary School in St. 

Bernard Parish in the community of Violet on February 22, 2010, to present information 

about the diversion and to assess the concerns of residents and businesses in the local 

area. The meeting was videotaped and recorded by a court reporter. While many of the 

residents support marsh creation and restoration in the project area, many were opposed 

to the location of the proposed diversion location and suggested the USACE, Mississippi 

Valley Division, New Orleans District (CEMVN) utilize the existing canal/diversion in 

the area. Concern was raised about interior drainage and flooding issues as well as 

salinity levels and sediment placement. Further outreach efforts are being conducted to 

target the communities adjacent to the diversion to develop enhancement measures that 

would not interfere with community cohesion and further explain in detail how the 

diversion is designed, how it works, and its potential impacts. 

5.3.5 Public Meeting

A public meeting was held at Holy Cross Church, in New Orleans, Louisiana on April 20, 

2010, to study alternatives for a freshwater diversion proposed in the vicinity of Violet, 

Louisiana, and receive comments from the public. Approximately 70 people participated 

in the meeting. Concern was expressed for construction of the diversion structure in St. 

Bernard Parish and the potential for increased flooding. Participants questioned what 

additional alternative locations were considered and whether the CEMVN considered the 

old water plant at the historic battlefield to the north or measures to utilize the existing 

Violet Siphon. Concerns were also expressed regarding adverse impacts of freshwater on 

the recreation and commercial fisheries. Positive comments were expressed for the 

extensive restoration measures proposed, but participants wanted the study to move more 

quickly toward constructible features. 
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5.4 STAKEHOLDER FORUM

5.4.1 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 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 Study. Presentations 

were made by the MRGO Ecosystem Restoration Study PDT, the New Orleans Sewerage

and Water Board, LSU School of Landscape Architecture, and the Environmental 

Defense Fund. 

5.4.2 USACE Recreation Forums 

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 (charter boat

operators, hunting and fishing clubs, boat ramp operators, marinas, etc.). 

Several groups from the Lower 9th Ward in Orleans Parish expressed a desire to meet 

with USACE staff to share recreation studies discussing community needs and potential 

designs for the Bienvenue Triangle viewing platform. Two meetings were held with 

various groups; the first occurred on June 3, 2010 in the Lower 9th Ward and the second 

took place on June 10, 2010 at Tulane and Xavier’s Center for Bioenvironmental 

Research. Recreation designs and studies prepared by NGOs and university students 

were presented during the meetings. Discussions centered around recreation plans for 

Bienvenue Triangle prepared by the University of Colorado and results of a survey 

administered by the University of Wisconsin students at the platform, which gathered 

data on recreation use at the Triangle platform.

A meeting with local St. Bernard parish officials took place June 17, 2010 to present the 

USACE’s recreation feature design for Shell Beach. Comments and ideas shared by St. 

Bernard officials resulted in modifications to the proposed recreation plan. The 

Bienvenue Triangle and Shell Beach recreation features are presented in section 2.5.3.2. 
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5.4.3 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 Study were discussed at this workshop. Participants 

included members of the academic community, non-governmental organizations, 

engineers, planners, landscape architects, and other stakeholders. 

5.4.4 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, and Deputy District Engineer for Project 

Management. Restoration priorities were identified and alternative implementation 

strategies were discussed at this workshop. 

5.5 U.S. FISH AND WILDLIFE COORDINATION

A scope of work and funding was provided to the USFWS, Lafayette Field office so that 

office could assist with the development of restoration alternatives, become an active 

participant in PDT and HET meetings, participate in site visits, and assist with habitat 

assessments. The USFWS provided a final Fish and Wildlife Coordination Act Report on 

March 13, 2012 to document existing and future conditions including impacts, as well as

to present USFWS positions and recommendations and conservation measures.

5.6 DRAFT ENVIRONMENTAL IMPACT STATEMENT

The DEIS was made available for public review and comment. A Notice of Availability 

(NOA) was published in the Federal Register on December 17, 2010, to inform the 

public that the DEIS had been released. A notice of availability letter was mailed to the 

USACE New Orleans District stakeholder and NEPA mailing lists also on December 17, 

2010. This notice provided a description of the proposed action including the project 

features, points of contact to obtain more information regarding the DEIS, and a means of 

commenting on the DEIS and companion MRGO Ecosystem Restoration Plan Feasibility 

Report. The DEIS was available for review by agencies, organization, and individuals 

for an extended 78-calendar day comment starting with the publication of the NOA in the 

Federal Register on December 17, 2010 through March 5, 2011. 
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5.6.1 DEIS Public Hearings

Three Public Hearings were scheduled on January 20, 2011, January 25, 2011 and 

February 3, 2011. Due to inclement weather, the February 3, 2011 meeting was 

rescheduled for February 8, 2011. Public meeting notices were published in advance of 

each meeting in local newspapers including The Times-Picayune, The St. Bernard Voice, 

and The Sun Herald.

The Public Hearings were scheduled 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 and 

feasibility report. Information on the locations and participation at the Public Hearings is 

shown in table 5-1. The number of individuals that provided a verbal comment at each 

meeting is also presented. Appendix Y, Public Hearing Record and DEIS Comment 

Summary, provides additional details regarding the Public Hearings.

Table 5-1: MRGO DEIS Public Hearing Summary

Date Location Attendees Speakers/Commenters

January 20, 2011 C.F. Rowley Alternative School; 

Chalmette, LA 261 19

January 25, 2011 Leo Seal Community Center; 

Waveland, MS 73 14

February 8, 2011 Light City Christian Academy; 

New Orleans, LA 104 22

Total 438 55

5.6.2 DEIS Public/Agency Comment and Response

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 comments, 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 
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issues. All comments were reviewed to determine significance of each comment 

regardless of the recurrence of the comment.

Appendix Y presents summarizes the comments received during the comment period and 

the responses to comments for recurring comment themes.

5.6.3 Final Environmental Impact Statement

The FEIS has been updated to include refinements in the plan including further 

engineering associated with the restoration measures. Where applicable, comments 

received on the DEIS have been incorporated into the FEIS. The FEIS will be made 

available for public review and comment. A Notice of Availability (NOA) will be 

published in the Federal Register on June 22, 2012, to inform the public that the FEIS 

has been released. A 30 day wait period will follow the NOA to provide interested 

parties with an additional opportunity to review and comment upon the FEIS. 

5.6.4 Record Of Decision

A Draft ROD is being released along with the final EIS and is subject to change upon 

receipt of comments on the final report.
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CHAPTER 6: ENVIRONMENTAL REQUIREMENTS

This chapter documents the coordination and compliance efforts regarding statutory 

authorities including: environmental laws, regulations, executive orders, policies, rules, 

and guidance. Consistency of the tentatively selected plan with other Louisiana coastal 

restoration efforts is also described. 

Relevant Federal statutory authorities and executive orders are listed in table 6-1. 

Relevant State of Louisiana statutory authorities are listed in table 6-2. Full compliance 

with statutory authorities would be accomplished upon agency review and concurrence of 

resource effects and consistency determinations, upon review of the Final Environmental 

Impact Statement by appropriate agencies and the public, and the signing of a Record of 

Decision (ROD). 

6.1 CLEAN AIR ACT – AIR QUALITY DETERMINATION

Compliance with the Clean Air Act (42 U.S.C.A. §7401) has been coordinated with the 

Air Quality Section of the Louisiana Department of Environmental Quality (LDEQ). As 

required by Louisiana Administrative Code, Title 33 (LAC 33:III.1405 B), an air quality 

applicability determination has been developed for the tentatively selected plan. This 

includes consideration of the proposed action for the category of general conformity, in 

accordance with the Louisiana General Conformity, State Implementation Plan (LDEQ, 

1994). An air quality determination has been calculated, based upon direct and indirect 

air emissions. Generally, since no other indirect Federal action, such as licensing or 

subsequent actions, would likely be required or related to the restoration construction 

actions, it is likely that indirect emissions, if they would occur, would be negligible. 

Therefore, the air quality applicability determination analysis was based upon direct 

emission for estimated construction hours. Considering that total emissions for each 

work item separately (or even when all work items are summed) would not exceed the 

threshold limit applicable to volatile organic compounds (VOCs) for parishes where the 

most stringent requirement (50 tons per year in serious non-attainment parishes) is in 

effect, (see General Conformity, State Implementation Plan, Section 1405 B.2), the VOC 

emissions for the proposed construction would be classified as de minimus and no further 

action would be required. LDEQ correspondence dated January 11, 2011 indicates that 

“Currently, St. Bernard Parish is classified as attainment with the National Ambient Air 

Quality Standards and has no general conformity determination obligations.” 

6.2 CLEAN WATER ACT – SECTION 401 WATER 

QUALITY

Under provisions of the Clean Water Act (33 U.S.C. § 1251) of 1972, any project that 

involves the placement of dredge or fill material in waters of the United States or 

wetlands, or mechanized clearing of wetlands would require water quality certification 

from the LDEQ, Office of Environmental Services. An application for water quality 
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certification describing the impacts of the proposed action to water quality as described in 

section 4.4, along with a copy of the DEIS, has been provided to the LDEQ. LDEQ

correspondence dated February 2, 2012 indicates “that the requirements for a Water 

Quality Certification (WQC) has been met... therefore, the Department hereby issues a 

WQC to the U.S. Army Corps of Engineers – New Orleans District.”

Table 6-1: Relevant Federal Statutory Authorities and Executive Orders

(Note: This list is not complete or exhaustive)
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Table 6-2: Relevant State Statutory Authorities

(Note: this list is not complete or exhaustive)

6.3 CLEAN WATER ACT – SECTION 404(B)(1)

The United States Army Corps of Engineers (USACE) is responsible for administering 

regulations under Section 404(b)(1) of the Clean Water Act. Potential project-related 

impacts subject to these regulations, such as the discharge of dredged material into 

shallow open water areas to create wetlands and the placement of rock for shoreline 

protection, is evaluated in accordance and compliance with Section 404(b)(1) of the 

Clean Water Act (appendix E). The evaluation of potential impacts to water quality 

indicate that, on the basis of the guidelines, the proposed disposal sites for the discharge 

of dredged material and stone comply with the requirement of these guidelines, with the 

inclusion of appropriate and practicable best management practices to minimize adverse 

effects to the aquatic ecosystem.

6.4 COASTAL ZONE MANAGEMENT ACT OF 1972

Section 307 of the Coastal Zone Management Act of 1972 (16 U.S.C. 1456(c)(1)(A)) 

directs Federal agencies proposing activities or development projects (including civil 

work activities), whether within or outside the coastal zone, assure that those activities or 

projects are consistent, to the maximum extent practicable, with the approved state 

coastal zone management program. A Coastal Zone Consistency Determination is 

included in appendix F and was submitted to the Louisiana Department of Natural 

Resources (LDNR) for consistency review concurrent with the release of the DEIS for 

public comment. Implementation of the tentatively selected plan is considered 

consistent, to the maximum extent practicable, with the approved Louisiana State Coastal 

Management Program. LDNR correspondence dated February 8, 2011 indicates “The 

project, as proposed in the application, is consistent with the Louisiana Coastal Resources 

Program (LCRP)”.

6.5 FARMLAND PROTECTION POLICY ACT

Congress passed the Farmland Protection Policy Act (FPPA) as a result of a substantial 

decrease in the amount of open farmland. The purpose of the Act is to minimize the 

extent to which Federal actions contribute to the unnecessary and irreversible conversion 

of farmland to nonagricultural uses. Approximately 442 acres of soils designated as 

prime and unique farmland would be impacted by the construction of the diversion canal 

(Alternative 1 location). The area is currently utilized as pasture. A Farmland 
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Conversion Impact Rating (FCIR) Form AD 1006 was prepared and submitted to the 

Department of Agriculture – Natural Resources Conservation Service (NRCS) for 

evaluation. Correspondence dated January 12, 2011 includes completion of Form AD 

1006 by NRCS (appendix R). 

6.6 FISH AND WILDLIFE COORDINATION ACT OF 1958

The USACE and the Department of the Interior - U.S. Fish and Wildlife Service 

(USFWS) have formally committed to work together to conserve, protect, and restore fish 

and wildlife resources while ensuring environmental sustainability of our Nation’s water 

resources under the January 22, 2003, Partnership Agreement for Water Resources and 

Fish and Wildlife. Accordingly, in a letter dated October 31, 2008, the USFWS entered 

into an agreement to serve as a Cooperating Agency (per National Environmental Policy 

Act (NEPA) section 1501.6) in developing the EIS for the proposed project in accordance 

with applicable NEPA and Council on Environmental Quality (CEQ) guidance. 

Participation of the USFWS includes: 1) participating in meetings and field trips to obtain 

baseline information on project-area fish and wildlife resources; 2) evaluating the 

proposed project’s impacts to wetlands and associated fish and wildlife resources, and 

assisting in the development of measures to avoid, minimize, and/or compensate for those 

impacts; and 3) providing technical assistance in the development of a biological 

assessment (BA) describing the impacts of the proposed activity to Federally listed 

threatened and endangered (T&E) species and/or their critical habitat. In the October 31, 

2008, letter, the USFWS also provided specific guidance on avoiding impacts to West 

Indian manatees (Trichechus manatus); Brown pelicans (Pelecanus occidentalis); and 

endangered and threatened sea turtles. A final Fish and Wildlife Coordination Act Report 

(FWCAR) was provided by USFWS on March 13, 2012 (appendix B). Positions and 

recommendations by the USFWS, also referred to as the Service, are listed below in 

section 6.6.1. 

6.6.1 Service Positions and 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 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 period of analysis 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, 
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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 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. A reevaluation of benefits should be conducted for features during future phases 

of this project as uncertainties (e.g., implementation schedule, O&M, etc.) are 

resolved. Further detailed benefits analysis should be coordinated with the State 

and federal natural resource agencies

USACE Response. Concur. Benefits would be reevaluated during future phases 

of the project. USACE will continue to coordinate with the state and federal 

resource agencies.

3. 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. 
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4. 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. This means 

the Violet, Louisiana Freshwater 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 Diversion. 

5. 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. 

6. 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. 

7. 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.
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8. 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. 

9. 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. 

10. 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 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. 

11. 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 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 period of analysis, search for borrow from 

outside sources should continue as alternative sources may become economically 

feasible or as new advances in technology become available. 
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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.

12. 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.

13. 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. 

14. 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.
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15. 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. 

16. 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.

17. 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. 

18. 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. 

19. 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. 
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20. 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. 

21. 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. 

22. 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 
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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. 

23. 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 

24. 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 (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. 

25. 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.

26. 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. 
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27. 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. 

6.7 ENDANGERED SPECIES ACT OF 1973

Compliance with the Endangered Species Act (7 U.S.C. 136; 16 U.S.C. 460 et seq.) is 

being coordinated with the USFWS and the National Oceanic and Atmospheric 

Administration (NOAA) for those species under their respective jurisdictions. A final

BA will be included with the public release of the FEIS in appendix G. The USACE has 

provided a copy of the BA to the USFWS and NOAA and has requested the initiation of 

formal consultation with the USFWS on potential impacts to the endangered pallid 

sturgeon (Scaphirhynchus albus), and requested the initiation of formal consultation with 

NOAA on potential impacts to the threatened Gulf sturgeon ((Acipenser oxyrhynchus 

desotoi) and its critical habitat.

The Lake Pontchartrain, Lake Borgne and Mississippi Sound are designated as critical 

habitat for the Gulf sturgeon and the Chandeleur Barrier Island Chain is designated as 

critical habitat for the piping plover. Reference section 4.19 and the final BA located in

appendix G for additional information on the pallid sturgeon, Gulf sturgeon and piping 

plover as well as critical habitat constituents. The effects determination for the pallid 

sturgeon and piping plover and its critical habitat is not likely to adversely affect the 

continued existence of the species. The effects determination for the Gulf sturgeon and 

its critical habitat may affect, but is not likely to adversely affect the continued existence 

of the species. Preliminary aquatic modeling for the Gulf sturgeon and restoration 

measures and benefits analysis for the barrier islands have been completed and results are 

discussed in section 4.19. 

The use of recommended primary activity exclusion zones and timing restrictions would 

be utilized, to the maximum extent practicable, to avoid project construction impacts to 

any T&E species or their critical habitat within the project area. The USACE would 

continue to closely coordinate and consult with the USFWS and the NMFS regarding 

T&E species under their jurisdiction that may be potentially impacted by implementing 

the proposed action. 

In a letter from the USFWS dated February 8, 2012, the agency agreed with the USACE 

determination that implementation of the proposed MRGO Ecosystem Restoration 

Project is not likely to adversely affect the endangered West Indian manatee and the 

threatened piping plover, or its critical habitat.
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In a Biological Opinion (BO) from the NMFS dated May 3, 2012, the agency stated that 

the action, as proposed, may affect, but is not likely to adversely affect sea turtles and 

Gulf sturgeon. It is also the NMFS opinion that the project is likely to adversely affect 

Gulf sturgeon critical habitat, but is not likely to destroy or adversely modify it.

NMFS included two conservation recommendations in their BO, which they believe 

could work to minimize or avoid effects from the proposed action on the Gulf sturgeon. 

The USACE has stated that the recommendations would be implemented as part of the 

project. The conservation recommendations include: 1) Gather data describing recovery 

rates of Gulf sturgeon prey species in response to re-colonization of muddy-sand 

substrate that would assist in future assessments of impacts to Gulf sturgeon prey items; 

and 2) Gather data describing Gulf sturgeon movements within the Lower Pontchartrain 

Sub-basin. 

In order for NMFS to be kept informed of actions minimizing or avoiding adverse effects 

or benefiting listed species or their habitats, NMFS would be notified of the 

implementation of any conservation recommendations or the other updates as the project 

is implemented.

6.8 LOUISIANA STATE RARE, THREATENED AND 

ENDANGERED SPECIES, AND NATURAL 

COMMUNITIES COORDINATION

The USACE reviewed the database maintained by the Louisiana Natural Heritage 

Program that provides the most recent listing and locations for rare, T&E species of 

plants and animals and natural communities within the State of Louisiana. The proposed 

action would not adversely impact any rare, T&E species, or unique natural communities. 

The proposed action would increase the extent of fresh, intermediate, brackish and saline 

marsh as well as swamp habitat and ridge habitat in the project area (see also section 

4.11).

6.9 MAGNUSON-STEVENS FISHERY CONSERVATION 

AND MANAGEMENT ACT OF 1996 AND THE 

MAGNUSON-STEVENS ACT REAUTHORIZATION OF 

2006 (ESSENTIAL FISH HABITAT)

As directed by the Magnuson-Stevens Fishery Conservation and Management Act 

(Public Law 104-297), the USACE has coordinated with the NMFS and that agency’s 

experts on various marine organisms, as well as EFH. The NMFS provided a letter dated 

October 27, 2008, to help guide the development of the DEIS for the proposed action 

(appendix C). The NMFS identified shrimp, red drum, reef fish, and stone crabs as 

species managed by the Gulf of Mexico Fishery Management Council that have EFH in 

the project area. They also listed estuarine emergent wetlands, mud, sand and shell 
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substrates, and estuarine and marine water column as primary categories of EFH in the 

project area. The analysis of potential impacts of the tentatively selected plan on EFH is 

described in section 4.18. Consultation with NMFS has been completed. NMFS 

provided a letter on the DEIS dated February 11, 2011 with EFH recommendations. The 

USACE responded March 3, 2012 accepting the NMFS recommendations (see section 

6.9.1). The NMFS submitted a final letter on March 28, 2012 stating that all EFH 

conservation recommendations have been satisfactorily addressed and a further 

consultation under the Magnuson-Stevens Act was not necessary. EFH conservation 

recommendations are listed below in section 6.9.1. 

6.9.1 NOAA/NMFS

1. To avoid and minimize impacts to EFH and associated marine fisheries resources, 

specific details and documents for each restoration feature of the tentatively 

selected plan (TSP) shall be provided to NMFS for evaluation, discussion, review 

and comment during the preliminary engineering and design (PED) stage.

USACE Response: Concur. Detailed documents will be provided to NMFS 

during the PED stage. 

2. The borrow pits in Lake Borgne initially shall be limited to no deeper than 15 feet 

below the water surface (i.e., total water depth) unless monitoring and adaptive 

management, or modeling of the hydrology of the borrow pits clearly indicate 

deeper pits would have little impact on water quality.

USACE Response: Concur. USACE in coordination with NMFS has developed 

a borrow plan and Monitoring and Adaptive Management Plan (MAMP) to 

minimize impacts to water quality. This includes three test pits to determine the 

depth at which water quality might be affected.

3. The MAMP shall be revised to include monitoring of benthic communities and 

dissolved oxygen (DO) levels within borrow areas in Lake Borgne. Water quality 

monitoring shall be conducted at least during April through October for a 

minimum of three years post-dredging to verify the relative success of the borrow 

pit design in avoiding impacts to water quality. Specific conductance, 

temperature, DO, and pH shall be sampled from the bottom to the surface in fivefoot profiles. Samples shall be collected at least one time during April, 

September, and October. Samples shall be collected twice, about two weeks 

apart, during May, June, July, and August. Benthos should be sampled annually 

pre- and post-construction to evaluate changes in community structure. This 

information shall be used to adaptively manage borrow site design to minimize 

adverse impacts, if any.

USACE Response: Both pre- and post-construction monitoring will be utilized 

to determine project success. Nutrient sampling will be designed in coordination 

with Louisiana Department of Environmental Quality, if needed as to not 
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contribute to low dissolved oxygen (DO) conditions. Hourly salinity, 

temperature, water level, and turbidity monitoring will be initiated in PED and 

maintained throughout construction and 10 years post-construction at seven 

locations within the project area. Gulf sturgeon have been found to feed primarily 

on species associated with sandy, polyhaline habitats which are absent from Lake 

Borgne. Nearby boring data indicates that the sediment stratification within Lake 

Borgne is fairly uniform. Fat clay interspersed with small bands of lean clay, silty 

sand and pear are the predominant sediments occurring in the project area, based 

on this data. Once borings are completed for the borrow pits, if sediment 

composition does not conform to the before mentioned assumption of uniformity, 

then consultation with the resource agencies would be re-initiated to document 

impacts to sediment composition and the benthic assemblage. 

4. The retention dikes constructed for marsh creation and nourishment areas shall be 

gapped and degraded within three years of used in a manner acceptable to NMFS.

USACE Response: Concur. The dike features would be mechanically breached 

or degraded within three years of construction, if natural degradations have not 

sufficiently removed the earthen material.

5. Shoreline protection features in the TSP shall include 25-foot wide gaps down to 

pre-project depth elevations for fisheries ingress and egress every 1,000 linear 

feet, unless otherwise refined in coordination with NMFS during PED. Scour 

aprons may be incorporated so as not to decrease the pre-project water depth, or 

offset sections of rock in front of or behind foreshore rock dikes may be included 

to minimize erosion in the vicinity of gaps. 

USACE Response: Concur. During the detail design phase for each feature, 

USACE would closely coordinate with USFWS and NMFS before 

implementation of these measures.

6.10 MIGRATORY BIRD TREATY ACT AND MIGRATORY 

BIRD CONSERVATION ACT

No migratory birds would be adversely affected by project activities. The project is in 

compliance with the Migratory Bird Conservation Act, 16 U.S.C. 715-715d, 715e, 715f715r; 45 Stat. 1222 and the Migratory Bird Treaties and other international agreements 

listed in the Endangered Species Act of 1973, as amended, Section 2(a)(4). A final 

FWCAR was completed on March 13, 2012 and is included in section 6.6.1. 
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6.11 NATIONAL HISTORIC PRESERVATION ACT OF 1966

In compliance with Section 106 of the National Historic Preservation Act of 1966, as 

amended and 36 CFR 800, Federal agencies are required to identify and consider 

potential effects that their undertakings might have on significant historic properties, 

district, site, building, structure, or object that is included in or eligible for inclusion in 

the National Register. Additionally, a Federal agency shall consult with any tribe that 

attaches religious and cultural significance to such properties. Agencies shall afford the 

State Historic Preservation Officer (SHPO) and tribes a reasonable opportunity to 

comment before decisions are made. National Register eligible sites would be avoided to 

the maximum extent possible and any potential adverse effects would be mitigated. A 

variety of mitigation measures are possible, ranging from avoidance to data recovery to 

other types of documentation. Mitigation can take place at the site directly affected or 

can be concentrated at any one site. Decisions on mitigation strategies would be made 

under a Memorandum of Agreement among the USACE, the Louisiana SHPO, and any 

consulting Indian groups. Sites unevaluated for National Register eligibility would either 

have to be avoided or further research would be carried out in order to determine 

National Register eligibility. 

Cultural surveys are currently underway for terrestrial sites and for shoreline protection. 

The borrow sites identified for use in the first five years of implementation are in the 

process of being surveyed. Additional cultural resource surveys are anticipated, but may 

not be complete prior to finalizing this NEPA document; therefore, a programmatic 

agreement is required. A Programmatic Agreement for the treatment of cultural 

resources was prepared and was provided to SHPO and the Advisory Council on Historic 

Preservation (ACHP) for comment. Letters of interest were also sent to all Federally 

recognized tribes with interest within the New Orleans District (appendix D). Two 

tribes, the Jena Band of Choctaw and the Chitimacha Tribe of Louisiana, expressed 

interest in being consulting parties to the Programmatic Agreement. A Programmatic 

Agreement was finalized and signed by the SHPO, ACHP, the Jena Band of Choctaw and 

the Chitimacha Tribe of Louisiana on a path forward in identifying and preserving 

cultural resources that may occur in or be affected by the project.

6.12 RESOURCE CONSERVATON AND RECOVERY ACT 

(RCRA) AS AMENDED BY THE HAZARDOUS AND 

SOLID WASTE AMENDMENTS (HSWA) OF 1984

A Phase I Environmental Site Assessment ESA was performed as part of this project and 

complies with the requirements of RCRA and HSWA. The ESA that was completed on 

February 1, 2010 can be found in appendix Q.
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6.13 EXECUTIVE ORDER 11988, FLOOD PLAIN 

MANAGEMENT 

This Executive Order (EO) instructs Federal agencies to avoid development in 

floodplains to the maximum extent feasible. The current project is not a "development," 

but rather a floodplain restoration action. This project is being developed in compliance 

with EO 12898. The proposed Violet, Louisiana Freshwater Diversion (Alternative 1 

location) would be coordinated with the St. Bernard Parish Floodplain Administrator for 

a final determination upon further study of the freshwater diversion. 

6.14 EXECUTIVE ORDER 11514, PROTECTION OF

ENVIRONMENT

EO 11514, Protection and Enhancement of Environmental Quality, directs Federal 

agencies to "initiate measures needed to direct their policies, plans and programs so as 

to meet national environmental goals." This project complies with EO 11514. 

6.15 EXECUTIVE ORDER 11990, PROTECTION OF 

WETLANDS 

EO 11990, Protection of Wetlands, works to avoid to the extenet possible the long and 

short term adverse impacts associated with the destruction or modification of wetlands 

and to avoid direct or indirect support of new construction in wetlands wherever there is a 

practicable alternative. The overall goals of this project include the restoration and 

nourishment of approximately 59,363 acres of habitat in the study area, including 13,790 

acres of fresh and intermediate marsh; 34,460 acres of brackish marsh; 10,431 acres of 

cypress swamp; 723 acres of saline marsh. This project complies with the goals of EO 

11990. 

6.16 EXECUTIVE ORDER 13186, MIGRATORY BIRD 

HABITAT PROTECTION

Section 3a and e of EO 13186 directs Federal agencies to evaluate the effects of their 

actions on migratory birds, with emphasis on species of concern, and inform the USFWS 

of potential negative effects to migratory birds. Implementation of the tentatively 

selected plan is not anticipated to have a measurable negative effect on migratory bird 

populations and in fact, would benefit migratory bird population as a whole by restoring 

valuable wetlands, swamp barrier island and ridge habitat. 
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Restoration Plan 6-18 June 2012

6.17 EXECUTIVE ORDER 12898, ENVIRONMENTAL 

JUSTICE

Title VI, Section 601 of the Civil Rights Act of 1964 (Public Law 88-352) states: 

“No person in the United States shall, on the grounds of race, color, or national origin, 

be excluded from participation in, be denied the benefits of, or be subjected to 

discrimination under any program or activity receiving Federal financial assistance.” 

On February 11, 1994, President Clinton issued EO 12898 regarding Federal actions to 

address environmental justice (EJ) issues in minority populations and low-income 

populations: 

“To the greatest extent practicable and permitted by law, and consistent 

with the principles set forth in the report on the National Performance 

Review, each Federal agency shall make achieving environmental justice 

part of its mission by identifying and addressing, as appropriate, 

disproportionately high and adverse human health or environmental 

effects of its programs, policies, and activities on minority populations and 

low-income populations in the United States and its territories and 

possessions, the District of Columbia, the Commonwealth of Puerto Rico, 

and the Commonwealth of the Mariana Islands.” 

EJ is the fair treatment and meaningful involvement of all people regardless of race, 

color, national origin, or income with respect to the development, implementation, and 

enforcement of environmental laws, regulations, and policies. EO 12898 focuses Federal 

attention on the environmental and human health conditions in the minority and lowincome communities, enhances the provisions of nondiscrimination in Federal programs 

affecting human health and the environment, and promotes meaningful opportunities to 

the access of public information and participation in matters relating to minority and lowincome communities and their environment. The EO is directed internally to all Federal 

departments and Federal agency heads to take the appropriate steps to identify and 

address any disproportionately high and adverse human health or environmental effects 

of Federal programs, policies, and activities on minority and low-income populations. 

Potential EJ issues have been considered throughout the entire study process, and will 

continue to be considered through project implementation. As part of the NEPA process, 

a scoping input request was provided to the public and interested parties. Four scoping 

comments were received and did not identify any potential EJ issues. The USACE is 

committed to ensuring that any potential EJ issues are addressed as the study proceeds. 

As project specifications were developed, one area of concern was identified in the Violet 

area where a proposed diversion would be located. While the proposed wetland creation 

and nourishment and shoreline protection measures would equally impact all potential 

users (e.g., commercial and recreational fishers) in the area, the Violet, Louisiana

Freshwater Diversion (Alternative 1 location) is located between two subdivisions that 

are classified as minority and/or low-income.
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6.18 EXECUTIVE ORDER 13112, INVASIVE SPECIES

On February 3, 1999, President Clinton issued EO 13112 establishing the National 

Invasive Species Council to prevent the introduction of invasive species, provide for their 

control, and to minimize the economic, ecological, and human health impacts resulting 

from invasive species. The tentatively selected plan is consistent with EO 13112. Only 

native plant species would be utilized in the implementation of the tentatively selected

plan. Implementation of the tentatively selected plan would adhere to programs and 

authorities preventing the introduction or spread of invasive species in the study area. 

6.19 WILD AND SCENIC RIVER ACT OF 1968

The Louisiana Scenic Rivers Act of 1988 was established to recognize and implement the 

Federal law of 1968, to preserve, protect, and enhance the wilderness qualities, scenic 

beauties, and ecological regimes of rivers and streams in the state. In accordance with 

LDWF policy concerning the protection of those water bodies classified as scenic, any 

construction within 100 feet of a scenic stream requires a scenic streams permit. A scenic 

streams permit is being completed as part of this FEIS and coordination with the LDWF 

Scenic Streams Coordinator is ongoing to minimize and prevent impacts to those scenic 

streams potentially affected by the project. In those areas where the construction limits 

are more than 100 feet from the scenic stream, the implementation of best management 

practices (BMPs) would be required to prevent sediment runoff during construction. 

These BMPs would include, but are not limited to, the use of stacked hay bales or silt 

fences, mulching and reseeding, use of buffer zones, and the collection and treatment of 

storm water runoff prior to discharge into a scenic stream, where appropriate. A final 

Scenic River Use Permit would be complete and submited to the LDWF in May 2012 as 

part of the FEIS. Further coordination would be deferred pending additional review of 

the Violet Diversion and final engineering on those restoration features noted as 

impacting a scenic stream. 

6.20 MARINE MAMMAL PROTECTION ACT OF 1972

According to NOAA website http://nmfs.noaa.gov/pr/laws/mmpa/ the Marine Mammal 

Protection Act (MMPA) was enacted in October 21, 1972 and amended in 1994. All 

marine mammals are protected under the MMPA.

The MMPA was enacted in response to increasing concerns among scientists and the 

public that significant declines in some species of marine mammals were caused by 

human activities. The Act established a national policy to prevent marine mammal 

species and population stocks from declining beyond the point where they ceased to be 

significant functioning elements of the ecosystems of which they are a part.
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Restoration Plan 6-20 June 2012

The MMPA prohibits, with certain exceptions, the “take” of marine mammals in U.S. 

waters and by U.S. citizens on the high seas, and the importation of marine mammals and 

marine mammal products into the U.S.

The following commitments have been made to ensure compliance with the MMPA and 

ESA:

1. Ensure construction contractors are educated on the MMPA and the ESA and the 

species of concern.

2. Conduct a search for coastal bottlenose dolphins, sea turtles, and Gulf sturgeon 

within marsh creation/restoration sites. Appropriate best management practices 

(BMPs) would be implemented to avoid or minimize potential entrapment of 

these protected species. These BMPs are included in detail in the contract and 

include the following: 

• Observe the area to be enclosed for protected species at least 24 hours prior to 

and during closure of any levee, dike or structure. This is best accomplished 

by small vessel or aerial surveys with at least two experienced marine 

observers on board scanning for protected species. 

• If any protected species are sighted within the area to be enclosed, all 

appropriate precautions shall be implemented by the Contractor to ensure 

protection of the animal. These precautions shall include avoiding direct 

contact with and not feeding the protected species. 

• Any sightings of protected species within an enclosed project site shall be 

reported immediately to the USACE.

• If observers’ note the animals are not leaving the area, but are visually 

disturbed, stressed or their health is compromised, then the USACE may 

require any pumping activity to cease until the animals either leave on their 

own or are moved under the direction of NMFS. NMFS would then conduct 

any necessary measures (detailed in the contract) to ensure protection of the 

species.
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CHAPTER 7: CONCLUSIONS AND RECOMMENDATIONS

7.1 AREAS OF CONTROVERSY AND UNRESOLVED 

ISSUES

Construction and operation of the MRGO (former Mississippi River Gulf Outlet 

Navigation Channel), in synergistic combination with other natural and man-made 

factors, has caused direct, indirect and cumulative land loss, shoreline erosion, saltwater 

intrusion, habitat modification, and impacts to wildlife and fisheries resources throughout 

the project area. Determining the extent to which the MRGO contributed to these impacts 

and what, if any, actions would be necessary to remediate any such impacts remains a 

controversial issue. 

7.1.1 Proposed Violet, Louisiana Freshwater Diversion

The Violet, Louisiana Freshwater Diversion is an important component of the plan to 

restore historic salinity conditions and provide freshwater and nutrients to nourish 

existing and restored wetlands in the study area. 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 related to 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. 

The location of the proposed Violet, Louisiana Freshwater Diversion (Alternative 1 

location) would be constructed in an open field that is located between two subdivisions 

that are predominately minority and/or low-income populations. Construction operations 

such as noise, dust, and traffic diversions would temporarily impact residents located in 

the immediate project vicinity as well as others that work or live in the surrounding area. 

A recreation feature that includes multi-use paths, open space, picnic tables and shelters 

is proposed adjacent to the Violet, Louisiana Freshwater Diversion to enhance the quality 

of life for residents of Violet (see section 2.5.3.2) 

St. Bernard Resident Concerns

A meeting was held at W. Smith Elementary School in Violet on February 22, 2010 to 

present information about the freshwater diversion and to assess the concerns of residents 

and businesses (see section 5.3.4). While many of the residents that attended the meeting 

indicated support for marsh creation and restoration within the project area, many were 

opposed to the location of the proposed diversion and suggested that the USACE should 
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FEIS MRGO Ecosystem

Restoration Plan 7-2 June 2012

utilize the existing canal/diversion in the area. Concern was raised about interior 

drainage and flooding issues as well as salinity levels and sediment placement. 

A public meeting was held at Holy Cross Church in New Orleans on April 20, 2010 to 

further present information regarding the freshwater diversion and to receive comments 

from the public (see section 5.3.5). Meeting attendees expressed concern for 

construction of the diversion structure and the potential for increased flooding. 

Participants questioned what additional alternative locations were considered and 

whether the USACE considered the old water plant at the historic battlefield to the north 

or measures to utilize the existing Violet Siphon. Concerns were also expressed 

regarding adverse impacts of freshwater on recreation and commercial fisheries. Positive 

comments were expressed for the extensive restoration measures proposed. 

St. Bernard Parish Government Position on the Proposed Violet, Louisiana

Freshwater Diversion

On May 4, 2010, the St Bernard Parish Council – the governing authority for the parish, 

formally adopted Resolution SBPC #637-05-10 stating that the St. Bernard Parish 

Government, in conjunction with the St. Bernard Parish Coastal Zone Advisory 

Committee, is “adamantly opposed to the proposed freshwater diversion project.” The 

Resolution (partial) further states the following:

• “the existing Violet Canal can be, and should be retro-fitted to deliver the 

freshwater that the 2007 Water Resources Development Act (WRDA) mandates;” 

• “The St. Bernard Parish Coastal Zone Advisory Committee is fully supportive of 

the restoration of the Central Wetlands area of St. Bernard Parish, but 

unanimously opposes another canal being dug to deliver the freshwater that can 

be delivered by using the existing conveyance and delivery canal.” 

These concerns were reiterated by St. Bernard Parish President Craig Taffaro, Jr. at the 

July 20, 2011 Public Hearing.

USACE Response

The USACE recognizes the concerns that have been brought forth by the St. Bernard 

Parish Council as well as residents of the parish and is committed to resolving these 

issues.

7.1.2 Deepwater Horizon Oil Spill

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

uncertain at this time (May 2012). The impacts of the oil spill as well as the various 

emergency actions taken to address oil spill impacts could potentially impact USACE 

water resources projects and studies within the Louisiana coastal area, including the 

MRGO Ecosystem Restoration project. Potential impacts could include factors such as 

changes to existing, future-without, and future-with-project conditions, as well as 
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Restoration Plan 7-3 June 2012

increased project costs and implementation delays. The USACE will continue to monitor 

and closely coordinate with other Federal and state resource agencies and local sponsors 

in determining how to best address any potential problems associated with the oil spill 

that may adversely impact project implementation. Supplemental planning and 

environmental documentation may be required as information becomes available. 

7.2 CONCLUSIONS

The tentatively selected plan (alternative C) would restore 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. Alternative C includes approximately 71 miles of shoreline 

protection and adaptively managed freshwater diversion near Violet, Louisiana. 

Approximately 10,221 acres of the restoration and protection features would be located in 

the East Orleans Landbridge/Pearl River area and approximately 9,861 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 demonstrated 

as having some storm surge damage risk reduction benefits. 

The Violet, Louisiana Freshwater Diversion is an important component of the plan to 

restore historic salinity conditions and provide freshwater and nutrients to nourish 

existing and restored wetlands in the study area. 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 related to 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.. 

The anticipated outputs of the tentatively selected plan would help address the current 

trend of degradation of the Lake Borgne ecosystem, support Nationally significant 

resources, provide a sustainable and diverse array of fish and wildlife habitats, provide 

infrastructure protection, and make progress towards a more sustainable ecosystem. 

Before the ecosystem restoration plan can be implemented, a non-Federal sponsor would 

need to be identified and a cost sharing agreement executed. The States of Louisiana and 

Mississippi have been identified as potential non-Federal sponsors. The non-Federal 

share will be 35 percent of the costs of implementing the ecosystem restoration plan, 

except for the Violet, Louisiana Freshwater Diversion for which the non-Federal share is 

25 percent. The non-Federal sponsor is responsible for providing all lands, easements, 
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Restoration Plan 7-4 June 2012

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.

In accordance with WRDA 2007 Section 3083, implementation of the Violet, Louisiana 

Freshwater Diversion would be cost shared 75 percent Federal, 25 percent non-Federal, 

with the States of Louisiana and Mississippi providing the non-Federal cost share. The 

provision of LERRDs and the costs of OMRR&R are a non-Federal responsibility.

The States of Louisiana and Mississippi have expressed support for the tentatively 

selected plan. The State of Mississippi has issued a letter of intent to USACE expressing 

its understanding of and willingness to provide its required cost share for the Violet, 

Louisiana Freshwater Diversion, although the letter of intent notes the state’s belief that 

the USACE should pursue full federal funding for the project. 

The State of Louisiana disagrees with USACE over the cost-share requirements for plan 

implementation 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 States of Louisiana and Mississippi to finalize the ecosystem 

restoration plan and to identify a non-Federal sponsor to cost share in plan 

implementation.

7.3 RECOMMENDATIONS

The District Commander has considered all the significant aspects of this study including 

the environmental, social, and economic effects, the engineering feasibility, and the 

comments received from other resource agencies, the non-Federal sponsors, and the public 

and has determined that the tentatively selected plan presented in this report is in the 

overall public interest and a justified expenditure of Federal funds. As a comprehensive 

approach to protect, stabilize, and augment the landbridge between Lake Borgne and the 

MRGO, the District Commander recommends the construction of rock dikes for shoreline 

protection along the south bank of Lake Borgne in the reaches referenced as Bayou 

Bienvenue, Bayou Dupre, and West of Shell Beach. The District Commander also 

recommends the construction of marsh creation projects in the Golden Triangle, Central 

Wetlands, Terre aux Bouefs, Hopedale, Pearl River, and Shell Beach areas. 

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. 
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Restoration Plan 7-5 June 2012

• Tier 2 includes features with feasibility level detail that aren’t 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 if 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. 

• 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 2-28 provides the TSP feature descriptions by tier and Figure 2-24 depicts the TSP 

timetableRecommendations are . 
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-1 June 2012

CHAPTER 8: DISTRIBUTION LIST AND OTHER

8.1 DISTRIBUTION LIST

Preparation of this FEIS was coordinated and distributed to appropriate Congressional, 

Federal, state and local interests, as well as environmental groups and other interested 

parties. The following agencies, as well as other interested parties would receive copies 

of this revised FEIS. The complete distribution lists are provided in appendix K. 

• U.S. Department of the Interior, Fish and Wildlife Service 

• U.S. Environmental Protection Agency, Region VI 

• U.S. Department of Commerce, National Oceanic and Atmospheric 

Administration Fisheries, National Marine Fisheries Service

• U.S. Natural Resources Conservation Service, State Conservationist 

• Advisory Council on Historic Preservation 

• Governor's Executive Assistant for Coastal Activities

• Louisiana Department of Wildlife and Fisheries

• Louisiana Department of Natural Resources, Coastal Management Division 

• Louisiana Department of Natural Resources, Coastal Restoration Division

• Louisiana Department of Environmental Quality, PER-REGC

• Louisiana Department of Environmental Quality, EP-SIP

• Louisiana State Historic Preservation Officer

8.2 LIST OF PREPARERS

Many individuals were involved with the completion of this document. Listed below are 

those staff members who played a role in the development of the MRGO Ecosystem 

Restoration Plan DEIS and FEIS. 

Name

Job Description/Experience/

Education/Registration Subject Matter

USACE, MVN

Behrens, Elizabeth Environmental Manager/Biologist, Ecological 

Planning and Restoration Section/16 years/B.S. 

Wildlife Management – Louisiana State University

Biological Assessments

Brandstetter, Charles Lead Structural Engineer/13 years/B.S. and M.S.

Civil Engineering – University of New 

Orleans/P.E.

Structural Engineer

Britsch, Del Geologist/27 years/Ph.D./Registered P.G. 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)/4

years/J.D/M.E.M. - Duke University

Legal Review
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-2 June 2012

Name

Job Description/Experience/

Education/Registration Subject Matter

Chaisson, Kathryn Geotechnical Engineer/3 years/B.S. Geological 

Engineering

Geotechnical Design

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

Project Engineering 

DeMarcay, Gary Archaeologist (MVN)/24 years/MA

Anthropology - Texas A&M University

Cultural Resources

Feldmeier, Paula Assistant District Counsel (MVN)/8 years/J.D. - 

Mercer University; L.L.M. in Environmental Law – 

University of Denver

Legal Review

Gilmore, Tammy Environmental Resources Specialist, Regional 

Planning and Environmental Division, South New 

Orleans Environmental Branch/3 years/B.S. 

Biology – Southeastern Louisiana University

Environmental Manager

Glisch, Eric Environmental Engineer, Hydraulics and 

Hydrologic Branch/4 years/E.I.T., B.S. in Civil and 

Environmental Engineering – University of 

Wisconsin

Section 404 Permit and 

Coastal Zone Consistency

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. Marine 

Science and International Business - University of 

Alabama, M.A. Marine Affairs - University of 

Rhode Island

Plan Formulation, Project 

Management, and Public 

Involvement

Napolitano, Matthew Regional Economist, Regional Planning and 

Environmental Division, South New Orleans 

Economic Branch/17 years/B.A. Economics – 

University of Pennsylvania, M.B.A. – Tulane 

University

Socioeconomic and Human 

Environment

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

Petitbon, John Civil/Cost Engineer/23 years/BSCE Louisiana State 

University, E.I.T.

Cost Engineer

Richardson, Jerica Archaeologist (MVN)/13 years/B.A., 

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

Taylor, Ron Hydraulics Engineer (MVN)/9 years/B.S. Civil 

Engineering, University of New Orleans/P.E.-LA

Functional Team Leader 

Engineering, Hydraulic

Engineering

Whalen, Daniel Regional Economist/B.S. Economics University of 

New Orleans/ MBA University of New Orleans.

Socioeconomics Impacts

URS

Boers, Aaron Environmental Scientist (URS)/5 years/B.S. 

Environmental Science – University of Wisconsin, 

Ph.D. Botany – University of Wisconsin

Section 404 Permit, Coastal 

Zone Consistency and 

Scenic Streams Permit

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
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-3 June 2012

Name

Job Description/Experience/

Education/Registration Subject Matter

Conner, J.V. Senior Ecologist (URS)/45 years/Ph.D. - Tulane 

University

Wildlife, Noise

Esmail, Muna Senior Environmental Engineer (URS)/11

years/B.S. Civil Engineering - Tulane University

Air Quality

Goh, Yong Sr. Project Scientist/Environmental Specialist/27

years/Ph.D. - Soil Chemistry, Morphology and 

Classification, MS – Agronomy, Soil Science, 

Experimental Statistics, BS – Agronomy, Soil 

Science – Louisiana State University

Soils 

Kunza, Amy Environmental Scientist (URS)/5 years/B.S. Botany 

– University of Georgia, M.S. Biology – University 

of Houston

Section 404 Permit, Coastal 

Zone Consistency and 

Scenic Streams Permit

LeBlanc, Jim Sr. Environmental Scientist/31 years/B.S. Marine 

Science - Nicholls State University

Coastal Vegetation 

Resources; Plankton 

Resources

Magiera, Doree Senior Project Manager (URS)/28 years/B.S. Civil 

Engineering - Texas A&M University

Project Management

Marler, Bradley Senior Project Scientist/22 years/M.S. Wildlife 

Ecology/Fisheries Management – Mississippi State 

University

Barrier Islands, URS 

Independent 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

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

Pollock, Jeff Environmental Scientist (URS)/4 years/B.S. 

Ecology – University of Georgia, Ph.D. Aquatic 

Ecology – University of Alabama

Section 404 Permit, Coastal 

Zone Consistency and 

Scenic Streams Permit

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

Atkins

Carson, Josh Environmental Scientist (Atkins)/4 years/ B.S. in 

Biology, Baldwin-Wallace College

Project Manager

Lanford, Caroline Lead Planner/11 years/M.U.R.P University of New 

Orleans/American Institute of Certified Planners 

(AICP) 

Plan Formulation, Project 

Manager Support

Spalding, Elizabeth Senior Staff Scientist II (Atkins)/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 

Winer, Harley Coastal/Hydraulic/Civil Engineer (Atkins)/21

years/Ph.D. University of Florida/P.E.- LA, MS, 

AL, FL

Hydraulic Engineering
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-4 June 2012

8.3 LITERATURE CITED

The following documents have been used and/or referenced as source material in the 

preparation of this DEIS 

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Barras, J. A., 2006, Land area change in coastal Louisiana after the 2005 hurricanes—a 

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Restoration Plan 8-5 June 2012

Benson, N. G. ed. 1982. Life history requirements of selected finfish and shellfish in 

Mississippi Sound and adjacent areas. U. S. Fish and Wildlife Service, Office of 

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Special Issue No. 20 103 p. 

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environmental requirements of coastal fisheries and invertebrates (South Florida) 

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MD. 130 pp. 

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Chandra Dreher, Jim Flocks and Dawn Lavoie. Assessing the Resilience of a Vital 

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Sustainable Coast. CRPA. Baton Rouge, LA. 140 pp + Appendices. 

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M University, College Station, Texas. 

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configuration (Age of Discovery): 1700's to 2005, in Lavoie, D., ed., Sand 

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communities and species interactions. Current Biology 19:1-5 

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Restoration Plan 8-17 June 2012

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Restoration Plan 8-18 June 2012

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8.4 GLOSSARY

Adaptive 

Management

An interdisciplinary approach acknowledging an insufficient 

information base for decision-making; that uncertainty and change 

in managed resources are inevitable; and that new uncertainties 

will emerge. An iterative approach that includes monitoring and 

involves scientists, engineers and others who provide information 

and recommendations that are incorporated into management 

actions; results are then followed with further research, 

recommendations, and management actions. 

Air Quality 

Determination

The Louisiana Department of Environmental Quality ensures that 

projects do not adversely affect air quality through this 

determination as a requirement of the Clean Air Act.

Alternative Plan Combinations of management measures that collectively meet 

study goals and objectives within the defined study constraints. 

Amplitude The maximum absolute value of a periodically varying quantity.

Anadromous Ascending rivers from the sea for breeding.

Anoxia Absence of oxygen.

Anthropogenic Caused by human activity.

Average Annual 

Habitat Unit 

(AAHU)

Represents a numerical combination of habitat quality and 

quantity (acres) existing at any given point in time. The habitat 

units resulting from the future without- and future with-project 

scenarios are annualized and averaged over the period of analysis, to 

determine AAHUs.

Benefits Valuation of positive performance measures.

Benthic Living on or in sea, lake, or stream bottoms.
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-20 June 2012

Biomass The total mass of living matter (plant and animal) within a given unit 

of environmental area.

Bottomland 

Hardwood Forest

Low-lying forested wetlands found along streams and rivers.

Brackish Marsh Intertidal plant community typically found in the area of the 

estuary where salinity ranges between 4-15 ppt.

Clean Water Act 

Section 404 (b) (1)

There are several sections of this Act which pertain to regulating 

impacts to wetlands. The discharge of dredged or fill material 

into waters of the United States is subject to permitting specified 

under Title IV (Permits and Licenses) of this Act and specifically 

under Section 404 (Discharges of Dredge or Fill Material) of the 

Act.

Coastal Zone 

Consistency 

Determination

The U.S. Environmental Protection Agency reviews plans for 

activities in the coastal zone to ensure they are consistent with 

Federally approved State Coastal Management Programs under 

Section 307(c)(3)(B) of the Coastal Zone Management Act.

Congressional 

Authorization

Authorization for investigation to prepare necessary feasibilitylevel report to be recommended for authorization of potential 

future project construction by Congress. 

Connectivity Property of ecosystems that allows for exchange of resources and 

organisms throughout the broader ecosystem.

Constraint A limitation or restriction on plans. Planning constraints may not 

be absolute restrictions, but rather something to minimize or avoid.

Control Structure A gate, lock, or weir that controls the flow of water.

Cumulative Impacts The combined effect of all direct and indirect impacts to a 

resource over time.

Decomposition Breakdown or decay of organic materials.

Degradation Phase The phase of the deltaic cycle when sediments are no longer 

delivered to a delta, and it experiences erosion, dieback, or 

breakup of marshes.
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-21 June 2012

Deltaic Cycle The repeating pattern of delta development, progression, and 

abandonment. As sediments are deposited at the mouth of the 

distributary channels, the delta progresses seaward. The main 

channel then switches to a new course with a shorter reach to the 

depositional basin. Abandoned delta lobes decrease in elevation 

due to continued subsidence and sediment compaction, resulting 

in retreat of the shoreline. Abandoned lobes may be partially or 

wholly covered by new lobes during later deltaic cycles.

Deltaic Deposits Mud and sand deposited at the mouth of a river.

Deltaic Plain The land formed and reworked as the Mississippi River switched 

channels in the eastern part of the Louisiana coastal area.

Detritus The remains of plant material that has been destroyed or broken 

up.

Dewatering The process of dredged sediments compacting while losing water 

after being deposited.

Discharge The volume of fluid passing a point per unit of time, commonly 

expressed in cubic feet per second (cfs), millions of gallons per 

day (mgpd), or gallons per minute (gpm). 

Dissolved Oxygen Oxygen dissolved in water, available for respiration by aquatic 

organisms. One of the most important indicators of the condition 

of a water body.

Direct Impacts Those effects that result from the initial construction of a measure 

(e.g., marsh destroyed during the dredging of a canal). Contrast 

with “Indirect Impacts.”

Diurnal Relating to or occurring in a 24-hour period; daily.

Diversion A turning aside or alteration of the natural course or flow of 

water. In coastal restoration this usually consists of such actions 

as channeling water through a canal, pipe, or conduit to introduce 

water and water-borne resources into a receiving area.

Dredged Material 

Embankments 

(Side-cast Banks, 

Excavated Material 

Banks)

Dredged material removed from canals and piled in a linear 

mound along the edge of canals.
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-22 June 2012

Dynamic Characterized by continuous change and activity.

Ecological Refers to the relationship between living things and their 

environment.

Ecosystem An organic community of plants and animals viewed within its 

physical environment (habitat); the ecosystem results from the 

interaction between soil, climate, vegetation, and animal life.

Ecosystem 

Restoration

Activities that seek to return an organic community of plants and 

animals and their habitat to a previously existing or improved 

natural condition or function.

Effectiveness Having an intended or expected effect. One of the USACE four 

requirements for a project.

Efficiency The quality of exhibiting a high ratio of output to input. One of 

the USACE four requirements for a project.

Egress A path or opening for going out; an exit.

Embankment A linear mound of earth or stone existing or built to hold back 

water or to support a roadway.

Encroachment Entering gradually into an area not previously occupied, such as a 

plant species distribution changing in response to environmental 

factors such as salinity.

Endangered Species Animals and plants that are threatened with extinction.

Enhance To augment or increase/heighten the existing state of an area.

Environmental 

Impact Statement 

(EIS)

A document that describes the positive and negative 

environmental effects of a tentatively selected plan and the 

possible alternatives to that action. The EIS is used by the 

Federal government and addresses social issues as well as 

environmental ones.

Estuary A semi-enclosed body of water with freshwater input and a 

connection to the sea where freshwater and saltwater mix.

Estuarine Related to an estuary.
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-23 June 2012

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.

Evaporation The process by which any substance is converted from a liquid 

state into, and carried off in, vapor; as, the evaporation of water.

Exotic Species Animal and plant species not native to the area; usually 

undesirable (e.g., hyacinth, nutria, tallow tree, giant salvinia).

Feasibility Report A description of a tentatively selected plan, previously outlined in 

a general fashion in a Reconnaissance Report, that will satisfy the 

Federal interest and address the problems and needs identified for 

an area. It must include an assessment of impacts to the 

environment (either in an Environmental Assessment, or the more 

robust Environmental Impact Statement), an analysis of 

alternative methods of completion, and the selection of a 

Tentatively Selected Plan through the use of a cost-effectiveness 

analysis.

Feature A constructible increment of an alternative plan.

Final Array The final grouping of the most effective coast-wide plans from 

which a final recommendation can be made.

Foreshore Dikes An embankment of earth and rock built to prevent floods or 

erosion that is built in the area of a shore that lies between the 

average high tide mark and the average low tide mark.

Fresh Marsh Intertidal herbaceous plant community typically found in that area 

of the estuary with salinity ranging from 0 ppt to 3 ppt.

Furbearer An animal whose skin is covered with fur (mammal), especially 

fur that is commercially valuable, such as muskrat, nutria, and 

mink.

Geomorphic Related to the geological surface configuration.

Gradient A slope; a series of progressively increasing or decreasing 

differences in a system or organism.

Habitat The place where an organism lives; part of physical environment 

in which a plant or animal lives.
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-24 June 2012

Habitat Loss The disappearance of places where target groups of organisms 

live. In coastal restoration, usually refers to the conversion of 

marsh or swamp to open water.

Habitat Units (HUs) Represent a numerical combination of quality (HSI) and quantity 

(acres) existing at any given point in time. The HUs resulting 

from the future without- and future with-project scenarios are 

annualized and averaged over the period of analysis, to determine 

AAHUs. The “benefit” of a project can be quantified by 

comparing AAHUs between the future without- and future withproject scenarios. The difference in AAHUs between the two 

scenarios represents the net benefit attributable to the project in 

terms of habitat quantity and quality.

Hazardous, Toxic, 

and Radioactive 

Wastes (HTRW)

Wastes that contain toxic constituents, or that may cause 

hazardous chemical reactions, including explosive or flammable 

materials, or radioactive wastes, which, improperly managed, 

may present a hazard to human health or the environment.

Herbaceous A plant with no persistent woody stem above ground.

Hydrodynamic The continuous change or movement of water.

Hydrology The pattern of water movement on the earth's surface, in the soil 

and underlying rocks, and in the atmosphere.

Hypoxia The condition of low dissolved oxygen concentrations.

Indirect Impacts Those effects that are not as a direct result of project construction, 

but occur as secondary impacts due to changes in the environment 

brought about by the construction. Contrast with “Direct 

Impacts.”

Infrastructure The basic facilities, services, and installations needed for the 

functioning of a community or society, such as transportation and 

communications systems, water and power lines, and public 

institutions including schools, post offices, and prisons.

Ingress An entrance or the act of entering.

Inorganic Not derived from living organisms; mineral; matter other than 

plant or animal.

Interdistributary 

Deposits

Sand and mud deposited between the river channels or between 

bayous.
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-25 June 2012

Intermediate Marsh Intertidal herbaceous plant community typically found in that area 

of the estuary with salinity ranging from 2 ppt to 5 ppt.

Intertidal Alternately flooded and exposed by tides.

Invertebrates Animals without backbones, including shrimp, crabs, oysters, and 

worms.

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. 

Larvae The stage in some animals’ life cycles between egg and adult 

(most invertebrates).

Leeward Sheltered from the wind; away from the wind.

Levee A linear mound of earth or stone built to prevent a river from 

overflowing; a long, broad, low ridge built by a stream on its 

flood plain along one or both banks of its channel in time of flood.

Maintain To keep in existing state.

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 NourishmentA type of management measure that nourishes existing marsh and 

decreases the depth of nearby open water.

Methodology A set of practices, procedures, and rules.

Mineral Substrate Soil composed predominately of mineral rather than organic 

materials; less than 20 percent organic material.

Mudflats Flat, unvegetated wetlands subject to periodic flooding and minor 

wave action.

National Ecosystem 

Restoration (NER)

USACE standard for cost-effectiveness based on ecosystem, not 

economic, benefits.
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-26 June 2012

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.

Near-shore 

Currents

Movement of water parallel to the shoreline. Usually generated by 

waves breaking on the shore at an angle other than perpendicular.

National 

Environmental 

Policy Act (NEPA)

Ensures that Federal agencies consider the environmental impacts 

of their actions and decisions. NEPA requires all Federal agencies 

to consider the values of environmental preservation for all 

significant actions and prescribes procedural measures to ensure 

that those values are fully respected. 

Net Gain The amount of cumulative land gain less land loss, when gain is 

greater than loss.

Net Loss The amount of cumulative land gain less land loss, when gain is 

less than loss.

No Action 

Alternative

The alternative in the DEIS which describes the ecosystem of the 

coastal area if no restoration efforts/projects were done.

Nursery A place for larval or juvenile animals to live, eat, and grow.

Objectives More specific statements than “Goals,” describing how to achieve 

the desired targets.

Organic Composed of or derived from living things.

Oscillations Fluctuations back and forth, or up and down.

Oxidation of 

Organic Matter

The decomposition (rotting, breaking down) of plant material 

through exposure to oxygen.

Oxygen-depleted Situation of low oxygen concentrations where living organisms 

are stressed. 

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 2015 to 2065. 
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-27 June 2012

Planning Scale Planning term that reflects the degree to which environmental 

processes would be restored or reestablished, and the resulting 

ecosystem and landscape changes that would be expected over the 

next 50 years. This uppermost scale is referred to as “Increase.” 

No net loss of ecosystem function is “Maintain.” Reducing the

projected rate of loss of function is “Reduce.” The lowest possible 

scale was no further action above and beyond existing projects 

and programs.

Potable Water Water that is fit to drink.

ppt Parts per thousand. The salinity of ocean water is approximately 

35 ppt.

Prime Farmland Land that has the best combination of physical and chemical 

characteristics for producing food, feed, fiber, forage, oilseed, and 

other agricultural crops with minimum inputs of fuel, fertilizer, 

pesticides, and labor, and without intolerable soil erosion. One of 

the categories of concern in the DEIS.

Productivity Growth of plants and animals.

Progradation The phase during the deltaic cycle where land is being actively 

accreted through deposition of river sediments near the mouth.

Programmatic 

Environmental 

Impact Statement 

(PEIS)

An Environmental Impact Statement that supports a broad 

authorization for action, contingent on more specific detailing of 

impacts from specific measures.

Province A major division of the coastal area of Louisiana. (e.g., Deltaic 

Plain and Chenier Plain).

Pulsing Letting a diversion flow periodically at a high rate for a short 

time, rather than continuously.

Quantitative Able to assign a specific number; susceptible to measurement.

Rebuild To some extent, build back a structure/landform that had once 

existed.

Reconnaissance 

Report

A document prepared as part of a major authorization that 

examines a problem or need and determines if sufficient methods 

and Federal interest exists to address the problem/need. If so, then 

a “Feasibility Report” is prepared, which details the solution and 

its impacts further.
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-28 June 2012

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.

Rehabilitate To focus on historical or pre-existing ecosystems as models or 

references while emphasizing the reparation of ecosystem 

processes, productivity, and service.

Relative Sea Level 

Rise

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. 

Restore Return a wetland to an approximation of its condition or function 

prior to disturbance by modifying conditions responsible for the 

loss or change; reestablish the function and structure of that 

ecosystem.

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). 

Saline Marsh Intertidal herbaceous plant community typically found in that area 

of the estuary with salinity ranging from 12-32 ppt.

Salinity The concentration of dissolved salts in a body of water, 

commonly expressed as parts per thousand (ppt). 

Salt Marshes See “Saline Marsh.”

Scoping Soliciting and receiving public input to determine issues, 

resources, impacts, and alternatives to be addressed in the DEIS.

Sea level Long-term average position of the sea surface.

Sediment Plume Caused by sediment rich rainwater runoff entering the ocean. The 

runoff creates a visible pattern of brown water that is rich in 

nutrients and suspended sediments that forms a kind of cloud in 

the water spreading out from the coastline. Commonly forms at 

river and stream mouths, near sloughs, and along coasts where a 

large amount of rain runoff flows directly into the ocean.
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-29 June 2012

Sheet Flow Flow of water, sediment, and nutrients across a flooded wetland 

surface, as opposed to through channels.

Shoaling The shallowing of an open-water area through deposition of 

sediments.

Social Relating to human society and its modes of organization.

Socioeconomic Involving both social and economic factors.

Stabilize To fix the level or fluctuation of; to make stable.

State Historic 

Preservation Office 

(SHPO)

The part of the Louisiana Department of Culture, Recreation, and 

Tourism that deals with Native American sites and other 

archaeological/historic sites.

Storm Overwash The process by which sand is transposed landward over the dunes 

during a storm event by waves. 

Storm Surge An abnormal and sudden rise of the sea along a shore as a result 

of the winds of a storm.

Strategy Ecosystem restoration concept from the Coast 2050 Plan.

Submergence Going under water.

Subprovince The divisions of the two Provinces (see “Province”) into smaller 

groupings: 1) east of the Mississippi River; 2) west of the 

Mississippi River to Bayou Lafourche; 3) Bayou Lafourche to 

Freshwater Bayou; 4) Freshwater Bayou to Sabine River.

Subsidence The gradual downward settling or sinking of the Earth’s surface 

with little or no horizontal motion.

Sustain To support and provide with nourishment to keep in existence; 

maintain.

Target A desired ecosystem state that meets and objective or set of 

objectives.

Terrestrial Habitat The land area or environment where an organism lives; as distinct 

from water or air habitats. 

Toxicity The measure of how poisonous something is.
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-30 June 2012

Transpiration The process by which water passes through living plants into the 

atmosphere.

Turbidity The level of suspended sediments in water; opposite of clarity or 

clearness.

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 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. 

Upland A general term for non-wetland elevated land above low areas 

along streams or between hills.

Water Resources 

Development Act 

(WRDA) 

A bill passed by Congress that provides authorization and/or 

appropriation for projects related to the conservation and 

development of water and related resources.

Weir A dam placed across a canal or river to raise, divert, regulate or 

measure the flow of water.

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 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.

8.5 ACRONYMS, ABBREVIATONS AND SYMBOLS

AAHU Average Annual Habitat Unit 

AATC Anti-Aircraft Training Center
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-31 June 2012

ACHP Advisory Council on Historic Preservation 

ADA American’s with Disabilities Act

ADH Adaptive Hydrology Model 

AGR Agriculture 

ASAP As Soon as Possible 

ASTM American Society for Testing and Materials

BA Biological Assessment

BCR Benefit-to-Cost Ratio

BGEPA Bald and Golden Eagle Protection Act 

BMP Best Management Practices

BOD Biological Oxygen Demand 

CAA Clean Air Act of 1963 

CASM Comprehensive Aquatic Systems Model 

CEDEP Cost Engineering Dredge Estimating Program

CEM Conceptual Ecological Model

CEMVN United States Army Corps of Engineers – Mississippi Valley Division, 

New Orleans District

CE/ICA Cost Effectiveness/Incremental Cost Analysis

CEQ Council on Environmental Quality 

CERCLA Comprehensive Environmental Response, Compensation, and Liability 

Act

CFR Code of Federal Regulations

cfs Cubic Feet per Second

cfu/100 ml Colony Forming Unit per Milliliter

CH4

CIAP Coastal Impact Assistance Program

Methane

CL Chloride 

CO Carbon Monoxide 

CO2

COC Contaminants of Concern 

 Carbon Dioxide 

CPUE Catch per Unit Effort
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-32 June 2012

CWA Clean Water Act

CWFCU-SWG Coastal Wetland Forest Conservation and Use Science Working Group 

CWPPRA Coastal Wetland Planning, Protection and Restoration Act 

cy Cubic Yard

dBA A-weighted decibel

DDT Dichlorodiphenyltrichloroethane 

DEIS Draft Environmental Impact Statement

DO Dissolved Oxygen 

DOI U.S. Department of the Interior 

DWS Drinking Water Source 

E&D Engineering and Design 

EA Environmental Assessment 

EFH Essential Fish Habitat

EIS Environmental Impact Statement

EJ Environmental Justice 

EL Environmental Laboratory

EMS Emergency Medical Services

EO Executive Order

EPA Environmental Protection Agency 

ER Engineering Regulation

ERDC Engineer Research Development Center

ERL Environmental Risk Limit

ESA Environmental Site Assessment

ESRA Environmental Systems Research Institute, Inc.

F&WP Fish and Wildlife Propagation

FEIS Final Environmental Impact Statement

FCIR Farmland Conversion Impact Rating 

FMC Fishery Management Council

FMP Fishery Management Plan

FONSI Finding of No Significant Impact

FPEIS Final Programmatic Environmental Impact Statement
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-33 June 2012

FPPA Farmland Protection Policy Act

fps Feet per Second

FWCAR Fish and Wildlife Coordination Act Report 

FWOP Future without Project 

FWP Future with Project 

GHGs Green House Gases

GIWW Gulf Intracoastal Waterway

GIS Geographic Information System 

GMFMC Gulf of Mexico Fishery Management Council 

GOM Gulf of Mexico

GSMFC Gulf States Marine Fisheries Commission

H&H Hydrology and Hydraulics 

H/A Hypoxic/Anoxic 

H2

HAPs Hazardous Air Pollutants 

S Hydrogen Sulfide 

HEP Habitat Evaluation Program

HET Habitat Evaluation Team

HSDRRS Hurricane and Storm Damage Risk Reduction System 

HSI Habitat Suitability Index

HTRW Hazardous, Toxic, and Radioactive Waste

HU Habitat Unit

IHNC Inner Harbor Navigation Canal 

IPCC Intergovernmental Panel on Climate Change 

IWR Institute for Water Resources

LACPR Louisiana Coastal Protection and Restoration 

LAW Limited Aquatic and Wildlife

LBWA Lake Borgne Wetlands Area

LCA Louisiana Coastal Area

LDEQ Louisiana Department of Environmental Quality 

LDHH Louisiana Department of Health and Hospitals 
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-34 June 2012

LERRD lands, easements, rights-of-way, utility or public facility relocations, and 

dredged or excavated material disposal area

LDNR Louisiana Department of Natural Resources

LDWF Louisiana Department of Wildlife and Fisheries

LMR Lower Mississippi River

LPBF Lake Pontchartrain Basin Foundation 

LWCF Land and Water Conservation Fund 

MAMP Monitoring and Adaptive Management Plan 

MBTA Migratory Bird Treaty Act

MEC Munitions and Explosives of Concern 

mcy Million Cubic Yards 

MDEQ Mississippi Department of Environmental Quality

MDMR Mississippi Department of Marine Resources

mg/l Milligrams per Liter

mg/m3

μg/m

Milligrams per Cubic Meter

3

μmhos/cm Micromhos per Centimeter

Micrograms per Cubic Meter

MMPA Marine Mammal Protection Act of 1972 

MPN Most Probable Number 

MRGO Former Mississippi River Gulf Outlet Navigation Channel 

MRT Mississippi River and Tributaries 

MSA Magnuson-Stevens Fishery Conservation and Management Act of 1996 

MsCIP Mississippi Coastal Improvements Program

MSL Mean Sea Level

N2

NAAQS National Ambient Air Quality Standards

O Nitrous Oxide 

NAVD North American Vertical Datum

NEPA National Environmental Policy Act

NER National Ecosystem Restoration

NGO Non-governmental Organization 

NMFS Department of Commerce – National Marine Fisheries Service
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-35 June 2012

NOx

NO

Nitrous Oxides (Nitrate and Nitrite)

2

NOA Notice of Availability

Nitrogen Dioxide

NOAA National Oceanic and Atmospheric Administration

NOI Notice of Intent to Prepare an Environmental Impact Statement

NPDES National Pollutant Discharge Elimination System

NPL National Priority List

NRC National Research Council

NRCS Department of Agriculture – Natural Resources Conservation Service

NRHP National Register of Historic Places

NTU Nephelometric Turbidity Limits

NWR National Wildlife Refuge

O&M Operations and Maintenance

O3

OCPR Office of Coastal Protection and Restoration

Ozone 

ODMDS Offshore Dredged Material Disposal Site

OMB Office of Management and Budget

OMRR&R Operation and Maintenance, Repair, Rehabilitation and Replacement

ONR Outstanding Natural Resource

OSHA United States Department of Labor – Occupational Safety and Health 

Administration

OYS Oyster Propagation 

P&G Principles and Guidelines 

PAH Poly-Aromatic Hydrocarbons

Pb Lead

PCB Polychlorinated Biphenyls

PCR Primary Contact Recreation

PDEIS Preliminary Draft Environmental Impact Statement

PDT Project Delivery Team

PED Preliminary Engineering and Design

PEIS Programmatic Environmental Impact Statement
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-36 June 2012

pH Hydrogen Ion

PM Particulates of Matter

ppm Parts per Million

ppt Parts per Thousand 

REC Recognized Environmental Concern 

RCRA Resource Conservation and Recovery Act 

RM River Mile

ROD Record of Decision

RSLR Relative Sea Level Rise

S&A Supervision and Administration 

SAND1 Sediment and Nutrient Diversion Model vs. 1 

SAND2 Sediment and Nutrient Diversion Model vs. 2 

SAV Submerged Aquatic Vegetation 

SCORP Statewide Outdoor Recreation Plan

SCR Secondary Contact Recreation

SHPO State Historic Preservation Officer

SHS State Historic Site

SLR Sea Level Rise

SO2

SO

 Sulfur Dioxide 

4 

T&E Threatened and Endangered

Sulfate

TAPS Toxic Air Pollutants

TDS Total Dissolved Solids 

TEL Total Exposure Limit

TMDL Total Maximum Daily Loads

TSP Tentatively Selected Plan

TY Target Year

UCC United Church of Christ 

UNO University of New Orleans

UNO-PIES University of New Orleans-Pontchartrain Institute for Environmental 

Sciences
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-37 June 2012

USACE United States Army Corps of Engineers

USCG United States Coast Guard

USDA United States Department of Agriculture

USFWS Department of Interior – United States Fish and Wildlife Service

USGS Department of Interior – United States Geological Survey

VOC Volatile Organic Compounds 

WMA Wildlife Management Area

WRDA 2007 Water Resource Development Act of 2007 

WVA Wetlands Value Assessment

8.6 INDEX

Access channels 2-49, 2-107, 4-21, 4-26, 4-29, 4-38, 4-56, 4-66, 4-78, 4-83, 4-93, 4-96, 

4-97, 4-100, 4-103, 4-106, 4-136, 4-144 

Aesthetics ES-16, 2-133, 3-3, 3-76, 3-121, 4-10, 4-131, 4-133, 4-134, 8-2

Air quality ES-10, 1-37, 2-131, 3-3, 3-51, 3-52, 4-4, 4-39, 4-40, 4-42 - 4-45, 6-1, 8-

3, 8-10, 8-13, 8-19, 8-34 

Alternative ES-1, ES-4, ES-6 - ES-17, 1-1, 1-7, 1-23, 1-24, 1-30 - 1-32, 1-35, 1-37,

1-39, 2-1 - 2-3, 2-5, 2-16, 2-19, 2-20, 2-31 - 2-39, 2-47 - 2-50, 

2-53 - 2-57, 2-62, 2-68, 2-71, 2-72, 2-74, 2-75, 2-77 - 2-91, 2-94 - 2-96, 

2-98, 2-103 - 2-105, 2-116 - 2-121, 2-123 - 2-125, 3-4, 3-109, 

4-1 - 4-16, 4-18 - 4-21, 4-24 - 4-49, 4-51 - 4-66, 4-68 - 4-83, 

4-85 - 4-101, 4-103 - 4-145, 5-5 - 5-8, 6-3, 6-4, 6-16, 7-1, 7-4, 8-2, 

8-19, 8-22, 8-26, 8-28 

Average annual 

habitat units 

(AAHUs)

1-26, 2-1, 2-34, 2-37, 2-38, 2-53, 2-57, 2-90, 2-91, 2-125, 2-126, 6-4, 

8-20, 8-24, 8-30 

Bank stabilization 1-33, 1-34, 3-29, 4-129, 8-16, 8-17, 8-18

Bayou Bienvenue ES-10, ES-18, 1-36, 2-18, 2-22, 2-53, 2-54, 2-59, 2-69, 2-110, 2-116,

2-127, 3-13, 3-29, 3-32, 3-41, 3-50, 3-94, 3-109, 3-117, 3-128, 3-129, 

4-3, 4-11, 4-12, 4-14, 4-16, 4-19, 4-31, 4-32, 4-67, 4-70, 4-73, 4-75, 

4-99, 4-108, 4-125, 4-126, 4-136, 4-137, 7-4 
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-38 June 2012

Bayou Dupre ES-9, ES-18, 2-22, 2-27, 2-41, 2-56, 2-59, 2-61, 2-109, 2-110, 2-127, 

3-13, 3-17, 3-32, 3-40, 3-41, 3-50, 3-87, 3-109, 3-128, 3-129, 4-3, 4-11, 

4-12, 4-14, 4-16, 4-31, 4-32, 4-67, 4-70, 4-73, 4-75, 4-126, 4-139, 

7-4, 8-18 

Bayou La Loutre ES-7, ES-8, 1-12, 1-15, 1-16, 1-22, 1-26, 1-28, 2-7, 2-14, 2-18,

2-21 - 2-23, 2-28 - 2-30, 2-36, 2-49, 2-51, 2-53, 2-54, 2-58, 2-84, 2-92, 

2-103, 2-105, 2-109, 2-116, 2-126, 3-1, 3-7, 3-13, 3-28, 3-29, 3-32, 

3-33, 3-35, 3-40, 3-41, 3-114, 3-117, 3-118, 4-1, 4-2, 4-11, 4-16, 4-19, 

4-31, 4-54, 4-65, 4-72, 4-77, 4-80, 4-82, 4-92, 4-99, 4-123, 4-124, 

4-127 

Bayou Sauvage 

National Wildlife 

Refuge

2-97, 3-121, 3-122, 4-126

Benthic resources ES-12, 2-132, 3-89, 4-6, 4-82, 4-85 - 4-87, 8-3

Benthos 2-34, 2-129, 4-38, 4-63, 4-83 - 4-85, 6-7

Biloxi Marsh E-6, E-6 - E-8, E-12, E-15, E-17, 1-5, 1-9, 1-10, 1-19, 1-24 - 1-27, 1-29, 

1-30, 2-10, 2-16, 2-24 - 2-28, 2-32, 2-35, 2-36, 2-41 - 2-43, 2-47 - 2-49, 

2-51, 2-53, 2-54, 2-56 - 2-58, 2-71, 2-72, 2-76, 2-84, 2-95, 2-98, 2-102, 

2-103, 2-109, 2-121, 2-122, 2-126, 2-132, 3-12, 3-24, 3-25, 3-40, 3-81, 

3-82, 3-90, 3-111, 3-119, 3-120, 3-124, 3-125, 4-6, 4-9, 4-13, 4-14, 

4-18, 4-22, 4-23, 4-25, 4-26, 4-28, 4-54, 4-55, 4-57, 4-59, 4-64, 4-85, 

4-88 - 4-91, 4-94, 4-125, 4-132, 4-134, 4-135, 4-138, 4-143, 5-3, 7-3, 

8-7 

Borrow sources 2-49, 2-50, 2-11, 2-34, 2-115 - 2-117, 4-38, 4-100, 4-101, 4-143, 6-7

Brackish marsh ES-6 - ES-8, ES-17, 1-14, 1-20, 1-25, 1-28, 2-36, 2-38, 2-53, 2-54, 

2-60 - 2-62, 2-98, 2-100, 2-113, 3-47, 3-71, 3-73, 3-79, 3-81, 3-82, 

3-128, 3-129, 4-23, 4-54, 4-58, 4-137, 4-143, 4-144, 6-14, 7-3, 8-20 

Breton Sound ES-3, 1-5, 1-9, 1-13, 1-15, 1-33, 2-4, 2-33, 2-50, 2-70, 2-113, 2-131,

3-3, 3-8, 3-12, 3-13, 3-28 - 3-41, 3-49, 3-57, 3-61, 3-78, 3-83, 3-84, 

3-91, 3-116 - 3-118, 3-124, 3-125, 3-127, 4-11, 4-17, 4-19, 4-31, 4-57, 

4-65, 4-72, 4-73, 4-78, 4-80, 4-82, 4-92, 4-99, 4-127, 4-128, 8-9 

Clean Air Act 1-37, 3-3, 3-51, 3-53, 6-1, 8-19, 8-31

Clean Water Act 1-38, 3-3, 3-14, 3-55, 3-103, 6-1, 6-3, 8-20, 8-31

Closure structure 1-12, 1-15, 2-5, 2-9, 2-13, 2-50, 2-69, 2-74, 2-120, 3-1, 3-13, 3-29, 

3-32, 3-33, 3-39, 3-41, 3-109, 4-11, 4-16, 4-19, 4-31, 4-54, 4-65, 4-72, 

4-77, 4-80, 4-82, 4-92, 4-98, 4-99, 4-127 

Coast 2050 Plan 4-61, 4-62, 8-29
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-39 June 2012

Coastal Impact 

Assistance Program 

(CIAP)

ES-7, 2-3, 2-18, 2-27, 2-68, 2-71, 2-72, 4-11, 4-15, 4-17, 4-18, 4-53, 

4-61, 4-65, 4-71, 4-87, 4-125, 4-136, 8-31 

Coastal Zone 

Management Act

1-38, 3-2, 3-14, 3-65, 3-78, 3-83, 3-89, 6-3, 8-20

Commercial fisheries ES-12, ES-14, 2-132, 3-85, 3-86, 4-6, 4-8, 4-71, 4-72, 7-44, 4-145, 5-5,

7-2, 8-3, 8-14 

Council on 

Environmental 

Quality (CEQ)

1-32, 2-97, 3-1, 3-42, 3-111, 5-1, 6-4, 8-31

Cultural resources ES-15, 2-73, 2-113, 3-3, 3-113, 3-114, 4-9, 4-121 - 4-124, 6-13, 8-2, 

8-6, 8-8, 8-9, 8-15, 8-18 

Coastal Wetlands 

Planning, Protection 

and Restoration Act 

(CWPPRA) 

ES-7, 1-29, 1-34, 2-3, 2-18, 2-42, 2-68, 2-70, 2-71, 2-99, 2-100, 2-125, 

4-11, 4-15, 4-17, 4-53, 4-61, 4-62, 4-65, 4-69, 4-71, 4-72, 4-74, 4-76, 

4-77, 4-80, 4-82, 4-85, 4-86, 4-87, 4-92, 4-95, 4-99, 4-105, 4-111, 

4-117, 4-125, 4-126, 4-130, 4-133, 8-7, 8-11, 8-32 

Dissolved oxygen

(DO)

ES-9, 2-9, 2-113, 3-14 - 3-24, 3-26, 3-29, 3-33, 3-39, 3-40, 3-90, 4-3, 

4-15, 4-16, 4-19 - 4-27, 4-25, 4-27, 4-28, 4-29, 4-36, 4-38, 4-64, 4-66, 

4-68, 4-74, 4-77, 4-79, 4-80, 4-83, 4-85, 4-89, 4-91 - 4-93, 4-95 - 4-97, 

4-100, 4-136, 4-137, 6-9, 6-10, 8-21, 8-24, 8-32 

Employment ES-13, 2-133, 3-106, 4-7, 4-113, 4-114

Environmental justice

(EJ)

1-39, 2-133, 3-3, 3-109 - 3-113, 4-118, 4-119, 4-121, 5-5, 6-15, 8-2, 

8-32 

Essential fish habitat 

(EFH)

ES-11, ES-13, 1-38, 2-6, 2-97, 2-132, 3-66, 3-83, 3-92, 3-93, 3-95, 

3-96, 4-5, 4-7, 4-67, 4-70, 4-73, 4-75, 4-91 - 4-98, 4-113, 6-6, 6-7, 6-12, 

8-3, 8-32 

Eustatic sea level rise 8-23

Farmland Protection 

Policy Act (FPPA)

1-39, 3-3, 3-42, 3-49, 4-34, 6-3, 8-33

Fish and Wildlife 

Coordination Act 

Report (FWCAR)

1-38, 1-39, 8-18, 8-33
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-40 June 2012

Fisheries ES-5, ES-12, ES-14, 1-27, 1-31, 2-15, 2-22, 2-34, 2-76, 2-89, 2-91, 

2-94, 2-95, 2-99 - 2-101, 2-132, 2-134, 3-1, 3-2, 3-65, 3-69 - 3-74, 3-76, 

3-83, 3-85, 3-86, 3-89, 3-90, 3-92, 3-120, 4-6, 4-8, 4-64 - 4-68, 4-71, 

4-72, 4-74, 4-92 - 4-94, 4-113, 4-114, 4-129, 4-132, 4-145, 5-2, 5-5, 

6-5 - 6-8, 6-10, 7-1, 7-2, 8-1, 8-3 - 8-9, 8-11 - 8-16, 8-18, 8-33, 8-34 

Flotation access 

channels 

2-107, 4-38, 4-56, 4-78, 4-83, 4-100, 4-103, 4-106

Flood protection 

levees

1-21, 3-69

Freshwater diversion ES-2 - ES-9, ES-15, ES-17, 1-2, 1-3, 1-24 - 1-26, 1-28, 2-6, 2-10 - 2-12, 

2-15, 2-17 - 2-21, 2-33 - 2-36, 2-39 - 2-42, 2-38, 2-40, 2-41, 2-46, 

2-55, 2-57, 2-60, - 2-62, 2-65 - 2-67, 2-70 - 2-78, 2-82 - 2-85, 2-90, 

2-92, 2-94, 2-98, 2-107, 2-108, 2-121, 2-128, 2-132, 2-134, 3-12, 3-13, 

3-17, 3-106, 3-112, 4-1 - 4-3, 4-9, 4-11 - 4-13, 4-17, 4-18, 4-20, 

4-22 - 4-28, 4-30, 4-32, 4-34 - 4-36, 4-40, 4-44, 4-54, 4-66 - 4-80, 4-83, 

4-82 - 4-98, 4-99, 4-101, 4-108 - 4-110, 4-119, 4-120, 4-125, 4-127, 

4-128, 4-133, 4-134, 4-136, 4-141, 4-143, 4-144, 5-4, 5-5, 6-5, 6-8, 

6-10, 6-14, 6-16, 7-1 - 7-5, 8-4, 8-15 

Geomorphic and 

physiographic setting 

3-4

Goals and objectives ES-1, ES-7, 1-1, 1-24, 2-16, 2-20, 2-21, 2-52, 2-55, 2-61, 2-72, 2-89, 

2-95, 8-19 

Golden Triangle ES-18, 1-19, 1-25, 2-20, 2-23, 2-24, 2-27, 2-43, 2-61, 2-71, 2-109, 

2-133, 3-13, 3-29, 3-41, 3-94, 3-95, 3-128, 3-129, 4-11, 4-16, 4-17, 

4-78, 4-85, 4-116, 4-136, 4-137, 7-4 

Gulf Intracoastal 

Waterway (GIWW)

ES-3, ES-9, ES-14, ES-19, 1-5, 1-8, 1-9, 1-12, 1-35, 2-22, 2-27, 2-59,

2-60, 2-61, 2-69, 2-109, 2-113, 2-114, 2-117, 3-4, 3-12, 3-13, 3-29, 

3-32, 3-33, 3-40, 3-41, 3-49, 3-50, 3-94, 3-95, 3-109, 3-125, 3-129, 4-3, 

4-8, 4-11, 4-16, 4-19, 4-31, 4-32, 4-99, 4-126, 8-33 

Gulf sturgeon ES-13, 2-34, 2-113, 2-115, 2-116, 2-128, 2-129, 3-63, 3-70, 3-79, 3-98, 

3-99, 3-101, 4-7, 4-63, 4-86, 4-87, 4-96, 4-98, 4-103, 4-106, 4-107, 

4-143, 6-7, 6-11, 8-14 

Habitat Evaluation 

Program (HEP)

2-36, 8-33

Hazardous, Toxic,

and Radioactive 

Waste (HTRW)

ES-10, 1-39, 2-131, 3-3, 3-55, 4-4, 4-49, 4-51, 6-14, 8-24, 8-33

Hurricane Gustav 2-8
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-41 June 2012

Hurricane Katrina 1-12, 2-8, 2-9, 2-66, 2-69, 2-70, 2-91, 3-41, 3-50, 3-56, 3-60 - 3-62, 

3-64, 3-85, 3-104, 3-106, 3-109, 3-110, 3-119, 3-131, 4-31, 4-97, 4-119, 

4-120, 8-16 

Hurricane Protection 

System

3-108,3-131, 4-116, 4-141

Hurricane Rita 2-8, 2-9, 2-52, 2-70, 8-16

Hydrology ES-2, ES-9, 1-3, 1-7, 1-16, 1-20 - 1-22, 1-25, 1-26, 1-36, 2-7, 2-10, 

2-12, 2-13, 2-24, 2-37, 2-128, 2-131, 3-1, 3-7, 3-12, 3-13, 3-28, 3-104, 

4-1, 4-3, 4-11 - 4-15, 4-35, 4-54, 4-55, 4-64, 4-65, 4-72, 4-77, 4-80, 

4-82, 4-90, 4-92, 4-99, 4-127, 5-4, 8-24, 8-31, 8-33 

Infrastructure ES-3, ES-14,ES-17, 1-23, 2-11, 2-18, 2-19, 2-78, 2-80, 2-81, 2-96, 

2-97, 3-106, 4-7, 4-8,4-26, 4-58, 4-85, 4-95, 4-105, 4-111 - 4-113, 

4-115, 4-116, 4-126, 4-130, 7-3, 8-23 

Inner Harbor 

Navigation Canal 

(IHNC)

ES-3, 1-5, 1-8, 1-11, 2-19, 2-22, 2-61, 2-69, 2-73, 2-109, 2-113, 2-116, 

2-120, 3-3, 3-4, 3-12, 3-32 - 3-35, 3-39, 3-40, 3-93, 3-95, 3-101, 3-109, 

3-125, 4-1, 4-31, 4-32, 8-17, 8-33 

Intermediate marshes ES-7, 1-8, 1-14, 1-25, 1-28, 2-21, 2-36, 2-55, 2-62, 2-73, 2-92, 2-98, 

2-99, 2-113, 2-119, 2-132, 3-42, 3-70, 3-81, 3-82, 4-129, 6-5, 6-6, 6-14, 

7-3, 8-25 

Invasive species ES-2, 1-7, 1-10, 1-22, 1-23, 1-25, 1-26, 1-39, 2-8, 2-11, 2-13 - 2-15,

3-3, 3-72, 3-73, 3-76, 4-2, 4-62, 6-16, 8-6, 8-11, 8-16 

Lake Borgne ES-1 - ES-3, ES-5, ES-8, ES-9, ES-12, ES-15, ES-17, ES-18, 1-2, 1-3, 

1-5, 1-7 - 1-10, 1-13, 1-15, 1-16, 1-19, 1-21 - 1-23, 1-25, 1-26, 1-29, 

1-33 - 1-37, 2-4, 2-9, 2-10, 2-16, 2-17, 2-19, 2-20, 2-21, 2-23 - 2-32, 

2-34, 2-35, 2-41 - 2-43, 2-47 - 2-51, 2-54, 2-55, 2-58 - 2-62, 2-69, 2-75, 

2-77, 2-92, 2-96, 2-102, 2-108 - 2-111, 2-113, 2-115 - 2-117, 2-122, 

2-124, 2-126, 2-131, 2-132, 3-3, 3-6, 3-8, 3-13, 3-14, 3-17, 3-22 - 3-24, 

3-28 - 3-30, 3-32, 3-33, 3-35, 3-40, 3-41, 3-49 - 3-51, 3-55, 3-79 - 3-83, 

3-87, 3-90, 3-91, 3-94, 3-100, 3-101, 3-103, 3-107, 3-108, 3-112, 3-114, 

3-117, 3-118, 3-123, 3-124, 3-126 - 3-129, 4-3, 4-6 - 4-9, 4-11, 4-13, 

4-14, 4-16, 4-17, 4-19 - 4-30, 4-34, 4-38, 4-49, 4-50, 4-55, 4-57, 4-59, 

4-61, 4-63 - 4-69, 4-72 - 4-74, 4-76 - 4-80, 4-82 - 4-92, 4-94, 4-96, 

4-98 - 4-103, 4-105 - 4-107, 4-113 - 4-117, 4-123, 4-124, 4-127, 4-130, 

4-132, 4-134, 4-141, 4-143, 4-144, 6-7, 6-8, 6-10, 6-11, 7-4, 7-5, 8-12, 

8-18, 8-20, 8-34 

Lake Pontchartrain 

Basin Foundation 

(LPBF)

1-28, 1-29, 2-52, 2-116, 4-16, 5-2, 5-7, 8-10, 8-14, 8-35
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-42 June 2012

Landbridge ES-6, ES-7, ES-14, ES-17, 1-5, 1-8 - 1-10, 1-26, 1-29 - 1-31, 2-20,

2-24, 2-26, 2-41 - 2-43, 2-47 - 2-49, 2-51, 2-54, 2-56, 2-71, 2-73, 2-89, 

2-90, 2-92, 2-95, 2-98, 2-102, 2-103, 2-115, 2-124, 2-126, 2-132, 3-5, 

3-35, 3-81, 3-82, 3-108, 3-112, 3-121, 4-8, 4-17, 4-25, 4-26, 4-28, 4-54, 

4-60 - 4-62, 4-69, 4-74, 4-86, 4-95, 4-105, 4-112 - 4-117, 4-125, 4-130, 

4-133 - 4-135, 4-138, 7-3, 7-4 

Louisiana Coastal 

Area (LCA)

ES-2, ES-5, ES-7, 1-1, 1-2, 1-7, 1-14, 1-15, 1-29, 1-32 - 1-34, 2-3, 2-17, 

2-18, 2-20, 2-34, 2-70, 2-72, 2-121, 2-130, 2-134, 3-8, 4-11, 4-16, 

4-34, 4-53, 4-55, 4-65, 4-72, 4-77, 4-80, 4-82, 4-87, 4-92, 4-93, 4-99, 

7-2, 8-4, 8-17, 8-21, 8-33 

Louisiana Coastal 

Protection and 

Restoration (LACPR)

ES-2, 1-2, 1-7, 1-8, 1-24, 1-27, 1-32, 2-3, 2-15, 2-19, 2-31, 2-39, 2-134, 

4-11, 4-12, 4-116, 8-28, 8-33 

Louisiana 

Department of 

Environmental 

Quality (LDEQ)

1-31, 1-37, 1-38, 3-14, 3-18, 3-32, 3-39, 3-51, 3-53, 4-16, 5-2, 6-1, 6-2, 

8-1, 8-10, 8-16, 8-19, 8-33 

Louisiana 

Department of 

Natural Resources 

(LDNR)

1-14, 1-27, 1-38, 1-39, 4-16, 5-2, 6-3, 6-10, 8-1, 8-4, 8-10, 8-11, 8-19, 

8-33 

Louisiana 

Department of 

Wildlife and 

Fisheries (LDWF)

1-27, 1-31, 1-39, 2-52, 2-89, 2-137, 3-73, 3-74, 3-84, 3-85, 3-88, 3-120, 

3-129, 4-68, 4-73, 4-78, 4-80, 4-128, 5-2, 6-7, 6-8, 6-16,8-1, 8-9, 8-11, 

8-16, 8-34 

Magnuson-Stevens 

Fishery Conservation 

and Management Act

(MSA) 

1-38, 3-2, 3-92, 6-12, 8-34

Marsh creation ES-5, ES-7, ES-17, ES-18, 1-32, 2-24, 2-25, 2-61, 2-64, 2-73, 2-98, 

2-108, 2-110, 2-116, 2-124, 2-127, 3-50, 4-17, 4-25, 4-26, 4-28, 4-34, 

4-38, 4-42, 4-56, 4-61, 4-70, 4-75, 4-83, 4-90, 4-100, 4-125, 4-128, 

4-129, 4-130, 4-133, 4-136, 4-139, 5-4, 5-5, 6-10, 6-11, 7-1, 7-4, 8-25 

Migratory birds ES-11, 1-37, 2-15, 2-97, 3-3, 3-64, 3-66, 3-79, 4-5, 4-62, 6-9, 6-13, 

6-14 

Mississippi River and 

Tributaries (MRT)

2-74, 3-12, 8-34
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-43 June 2012

National 

Environmental Policy 

Act (NEPA)

ES-1, ES-4, ES-6, ES-7, 1-1, 1-32, 1-33, 1-35, 1-38, 2-1, 2-11, 2-16, 

2-68, 2-70, 2-77, 2-78, 2-83, 2-89, 2-106, 2-133, 3-1 - 3-3, 3-14, 3-42, 

3-65, 3-78, 3-89, 3-103, 3-111, 4-2, 4-144, 4-145, 5-1, 5-2, 5-7, 5-8, 

6-4, 6-13, 6-15, 8-2, 8-3, 8-26, 8-34 

National Historic 

Preservation Act

1-39, 3-3, 6-13

National Marine 

Fisheries Service 

(NMFS)

1-27, 1-31, 1-38, 2-89, 2-97, 2-116, 3-65, 3-83, 3-92, 3-93, 3-98, 4-99, 

4-106, 5-2, 6-4, 6-6 - 6-8, 6-10, 6-12, 8-1, 8-6, 8-12, 8-13, 8-34 

Navigation ES-1, ES-2, ES-5, ES-9, ES-14, ES-17, 1-2, 1-3, 1-5, 1-7 - 1-9, 1-11, 

1-12, 1-14, 1-19, 1-21, 1-24 - 1-26, 1-33, 1-35, 2-1, 2-3, 2-7 - 2-10, 

2-19, 2-21, 2-30, 2-31, 2-33, 2-51, 2-53, 2-62, 2-69, 2-73, 2-74, 2-83, 

2-97, 2-115, 2-117, 2-128, 3-1, 3-3, 3-4, 3-12, 3-29, 3-40, 3-41, 3-62, 

3-103, 4-1, 4-3, 4-8, 4-30 - 4-32, 5-1, 5-2, 7-1, 7-3, 7-4, 8-1, 8-17, 8-33, 

8-34 

Neotropical 

migratory birds

ES-11, 2-97, 3-79, 4-5

Net benefits 2-34, 2-43 - 2-46

Noise ES-5, ES-10, 2-131, 3-3, 3-54, 4-4, 4-46 - 4-49, 4-120, 4-143, 4-145, 

7-1, 8-2, 8-7 - 8-9, 8-14, 8-15 

Notice of Intent 

(NOI)

ES-4, 1-35, 1-36, 5-1, 5-3, 8-34

Oil, gas, and utilities 3-106, 4-114, 4-115

Oyster leases ES-12, ES-14, 2-113, 4-6, 4-8, 4-77 - 4-80, 8-9

Pipelines ES-2, ES-14, 1-21, 2-23, 2-28, 2-50, 2-78, 2-81, 2-2-106, 2-107, 2-113, 

2-117, 2-120, 3-106 - 3-108, 3-116, 3-117, 3-129, 4-8, 4-26, 4-50, 4-58, 

4-111, 4-114, 4-115, 4-129, 4-139 

Plan formulation 1-30, 2-1, 2-3, 2-36, 2-54, 2-57, 2-93, 3-109, 8-25

Plankton ES-12, ES-14, 2-34, 2-128, 2-129, 2-132, 3-10, 3-90, 3-91, 3-94, 3-95, 

3-97, 4-6, 4-8, 4-22, 4-63, 4-77, 4-79, 4-87 - 4-94, 4-144, 8-3, 8-8 

Population ES-5, ES-11, ES-13, ES-15, 1-23, 2-5, 2-8, 2-34, 2-35, 2-128, 2-129, 

2-132, 2-133, 3-10, 3-18, 3-53, 3-73, 3-75, 3-76, 3-78, 3-80, 

3-98 - 3-106, 3-109 - 3-113, 3-119, 4-5, 4-7, 4-9, 4-22, 4-39, 4-47, 4-63, 

4-64, 4-68, 4-74, 4-89, 4-94, 4-95, 4-98, 4-101, 4-105, 4-108, 4-109, 

4-118 - 4-121, 4-127, 4-128, 4-133, 4-143, 4-145, 6-14, 6-15, 7-1, 8-8, 

8-30 
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-44 June 2012

Primary productivity 3-65, 4-33, 4-98

Principles and 

Guidelines (P&G) 

2-1, 2-2, 8-35

Proctor Point 2-56, 2-61, 2-109

Project Cost ES-5, 2-130, 3-55, 7-3

Project Delivery 

Team (PDT)

ES-4, ES-6, 1-14, 1-36, 2-11, 2-55, 2-107, 2-116, 2-117, 5-1, 5-6, 5-7, 

8-33 

Purpose and need ES-1, 1-7, 2-16

Record of Decision 

(ROD)

1-1, 1-33 - 1-35, 1-37 - 1-39, 5-1, 5-9, 6-1, 8-36

Recreation ES-15, 1-2, 1-26, 1-30, 1-39, 2-5, 2-8, 2-16, 2-21, 2-34, 2-35, 2-51, 

2-59, 2-60, 2-63 - 2-68, 2-76, 2-133, 3-2, 3-3, 3-10, 3-12, 3-14, 3-15, 

3-17, 3-19, 3-27, 3-28, 3-40, 3-41, 3-54, 3-65, 3-66, 3-70, 3-71, 

3-76 - 3-78, 3-83 - 3-86, 3-89 - 3-92, 3-106, 3-115, 3-116, 

3-118 - 3-121, 3-124 - 3-127, 4-9, 4-19, 4-26, 4-28, 4-44, 4-48, 4-63, 

4-65, 4-66, 4-92, 4-108, 4-110, 4-111, 4-113, 4-114, 4-119, 4-120, 

4-125 - 4-131, 4-133, 4-134, 4-139, 4-145, 5-2, 5-5, 5-6, 6-16, 7-1, 7-2, 

8-2, 8-29, 8-35, 8-36 

Ridge restoration ES-6, ES-17, 1-25, 1-26, 2-6, 2-11, 2-14, 2-16, 2-28 - 2-30, 2-36, 2-50, 

2-54, 2-58, 2-93, 2-98, 2-105, 2-107, 2-109, 4-21, 4-26 - 4-29, 4-40, 

4-43, 4-45, 4-58, 4-123, 4-127, 4-132, 4-141, 4-142, 5-2, 5-7, 7-3 

Saline marsh ES-17, 1-1, 1-14, 1-28, 2-9, 2-36, 2-37, 2-56, 2-92, 2-98, 2-113, 3-48, 

3-71, 3-79, 4-21, 4-27, 4-29, 4-53, 4-54, 4-62, 4-142, 6-4, 6-12, 6-14, 

7-3, 8-28 

Salinity ES-8, ES-9, ES-12, ES-17, 1-3, 1-8, 1-9, 1-14 - 1-17, 1-20 - 1-25, 

1-27 - 1-29, 1-31, 2-4, 2-9, 2-10, 2-12, 2-13, 2-15, 2-18, 2-21, 2-33, 

2-34, 2-35, 2-37, 2-40, 2-61, 2-62, 2-69, 2-72 - 2-76, 2-82, 2-83, 2-94, 

2-95, 2-98, 2-101, 2-106, 2-108, 2-120, 2-121, 2-123 - 2-125, 2-134, 

3-1, 3-6, 3-8, 3-9, 3-12, 3-13, 3-20 - 3-22, 3-26, 3-28 - 3-30, 

3-32 - 3-40, 3-42, 3-63, 3-66, 3-69 - 3-71, 3-75, 3-76, 3-80, 3-84, 3-85, 

3-87, 3-90, 3-94 - 3-97, 3-103, 3-115, 4-3, 4-6, 4-12 - 4-14, 4-16, 

4-18 - 4-20, 4-22 - 4-25, 4-27, 4-30, 4-36, 4-37, 4-54 - 4-61, 

4-63 - 4-65, 4-67 - 4-69, 4-72 - 4-74, 4-76, 4-77, 4-79,4-80, 4-82, 

4-86 - 4-95, 4-98, 4-99, 4-101, 4-102, 4-127 - 4-130, 4-143, 5-4, 5-5, 

6-5, 7-1, 7-2 - 7-4, 8-7, 8-14, 8-15, 8-20, 8-22, 8-23, 8-25, 8-27, 8-28 

Saltwater intrusion ES-2, ES-5, 1-2, 1-7, 1-9, 1-10, 1-12, 1-14, 1-15, 1-20, 1-21, 1-25, 1-29, 

1-36, 2-3, 2-6 - 2-10, 2-12, 2-13, 2-23, 2-52, 2-62, 2-68, 2-91, 3-5, 3-9, 

3-13, 3-71, 3-72, 3-78, 3-84, 3-88, 4-1, 4-53, 4-54, 4-57, 4-88, 5-4, 7-1 
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-45 June 2012

Scoping ES-4, ES-6, 1-35 - 1-37, 2-11, 2-15, 2-16, 2-115, 2-116, 3-2, 5-1 - 5-3, 

6-15, 8-28 

Sediments ES-10, 1-20 - 1-22, 1-32, 2-4, 2-7, 2-39 - 2-41, 2-50, 2-99, 2-117,

2-134, 3-8 - 3-10, 3-42, 3-45 - 3-51, 3-55, 3-56, 3-77, 3-90, 3-94, 4-1, 

4-4, 4-20 - 4-22, 4-24, 4-26, 4-27, 4-29, 4-30, 4-37 - 4-39, 4-100, 

4-143, 4-145, 6-4, 6-7, 8-21, 8-27, 8-28 - 8-30 

Sheetpile 2-50

Shell Beach ES-18, 1-16, 1-34, 2-27, 2-46, 2-56, 2-59, 2-61, 2-66 - 2-68, 2-71, 

2-109, 3-28, 3-32, 3-55, 3-112, 3-117, 3-120, 4-17, 4-28, 4-44, 4-50, 

4-108, 4-110, 4-111, 4-119, 4-120, 4-133, 4-134, 5-6, 7-4, 8-17, 8-19 

Shoreline erosion ES-2, ES-5, ES-10, 1-7, 1-8, 1-10, 1-16, 1-19, 2-6, 2-10, 2-14, 2-51, 

2-89, 2-125, 3-5, 3-60, 3-70, 4-1, 4-4, 4-5, 4-21, 4-27, 4-29, 4-53, 4-79, 

4-112, 4-122, 4-143, 7-1 

Shoreline protection ES-6 - ES-8, ES-11 - ES-13, ES-17, 1-25, 1-26, 1-34 - 1-36, 2-6, 2-11, 

2-16, 2-24 - 2-28, 2-32, 2-36, 2-43, 2-45, 2-48, 2-49, 2-50, 2-53, 2-54, 

2-56 - 2-58, 2-60, 2-61, 2-71, 2-84, 2-90, 2-92, 2-93, 2-98, 2-102, 

2-103, 2-107, 2-109, 2-116, 2-124, 2-127, 3-55, 3-109, 3-112, 4-5 - 4-7, 

4-13, 4-14, 4-17 - 4-19, 4-21 4-22, 4-24 - 4-27, 4-34 - 4-38, 4-40, 4-41, 

4-43, 4-45, 4-55, 4-58, 4-59, 4-62, 4-63, 4-65, 4-67 - 4-72, 4-74, 4-75, 

4-77 - 4-83, 4-86 - 4-88, 4-90, 4-92 – 4-100, 4-103, 4-105 - 4-107, 

4-110, 4-116, 4-117, 4-122, 4-125, 4-127, 4-128, 4-130, 4-136, 4-138, 

4-141, 4-143, 6-3, 6-8, 6-13, 6-15, 7-3, 7-4, 8-10, 8-11

Soil resources 3-42, 4-34

Storm surge ES-2, ES-5, ES-7, ES-9, ES-17, 1-2, 1-7, 1-8, 1-12, 1-15, 1-16, 1-20, 

1-23 - 1-26, 1-29 - 1-31, 2-6 - 2-16, 2-31, 2-51, 2-56, 2-57, 2-68, 2-69, 

2-91, 2-92, 2-96, 2-98, 2-117, 3-9, 3-13, 3-41, 3-108, 3-109, 4-2, 4-3, 

4-11, 4-31, 4-108, 4-116, 4-117, 4-118, 4-120, 4-126, 4-128, 4-131, 7-3, 

8-28, 8-29 

Supplemental 

Appropriations Act 

1-12

Tentatively Selected 

Plan

ES-1, ES-2, ES-3, ES-8, ES-15, ES-17, 1-1 - 1-3, 1-32, 1-37, 1-38, 

2-2, 2-34, 2-35, 2-48, 2-49, 2-57, 2-65 - 2-67, 2-70, 2-83, 2-91 - 2-98, 

2-109, 2-111 - 2-114, 2-116, 2-119, 3-55, 3-98, 4-17, 4-100, 4-106, 

4-142 - 4-145, 5-1, 6-1, 6-3, 6-11, 6-12, 6-14, 6-16, 7-3, 8-23 

Threatened and 

Endangered Species 

(T&E)

ES-13, 2-132, 2-133, 3-1, 3-2, 3-63, 3-64, 3-71, 3-79, 3-98 - 3-100, 4-7, 

4-53, 4-93, 4-97, 4-99, 4-106, 4-144, 6-4, 6-12, 8-36 
Chapter 8 Distribution List and Other

FEIS MRGO Ecosystem

Restoration Plan 8-46 June 2012

Tropical storms 1-16, 1-19, 1-23, 2-8, 2-10, 2-15, 2-68, 2-91, 2-122, 3-9, 3-77, 4-26, 

4-38, 4-138 

U.S. Fish and 

Wildlife Service 

(USFWS)

1-30, 1-31, 1-37 - 1-39, 2-36, 2-89, 2-94, 2-96, 2-103, 2-120, 2-129, 

2-132, 3-57, 3-65, 3-79, 3-80, 3-98 - 3-102, 4-67, 4-99, 4-102, 5-4, 5-7, 

6-4, 6-8, 6-9, 6-11 - 6-14, 8-6, 8-8, 8-11, 8-18, 8-36 

Vegetative plantings 1-25, 1-26, 2-59, 2-60, 2-65- 2-67, 2-93, 8-25

Violet, Louisiana ES-17, 2-20, 2-21, 2-35, 3-17, 3-112, 4-18, 4-22, 4-23, 4-27, 4-30, 4-54, 

4-65, 4-68, 4-71, 4-73, 4-77, 4-79, 4-94, 4-141, 5-5, 7-3, 8-4 

Volatile Organic 

Compounds (VOC) 

3-19, 3-50, 3-51, 4-40, 4-41, 4-43, 4-44, 6-1, 8-36

Water quality ES-9, ES-16, 1-15, 1-29, 1-38, 2-15, 2-19, 2-21, 2-34, 2-103, 2-108, 

2-115, 2-120, 2-131, 2-132, 3-1, 3-3, 3-13 - 3-15, 3-17 - 3-19, 

3-21 - 3-29, 3-34 - 3-39, 3-76, 3-77, 3-87, 3-101, 3-131, 4-3, 4-10, 

4-15 - 4-30, 4-38, 4-57, 4-63, 4-67, 4-78, 4-83, 4-88, 4-89, 4-106, 

4-125, 4-127, 4-137 - 4-139, 4-143, 4-145, 6-1 - 6-3, 8-3, 8-10 

Water Resources 

Development Act of 

2007 (WRDA 2007) 

ES-1, ES-2, ES-8, ES-17, 1-1 - 1-3, 1-7, 1-25, 2-18, 2-33, 2-70, 2-71, 

2-73, 2-83, 2-96, 2-118, 2-119, 2-121, 4-16, 4-18, 4-20, 4-22, 4-54, 

4-65, 4-66, 4-72, 4-77, 4-80, 4-82, 4-92, 4-99, 4-125, 4-127, 6-5, 7-1, 

7-3 - 7-5, 8-37 

Wetland creation 1-8, 1-34, 1-35, 2-112, 2-127, 2-116, 4-13, 4-24, 4-38, 4-69, 4-73,

4-78, 4-82, 4-83, 4-86, 4-87, 4-110, 4-116, 4-132, 4-136, 4-138, 6-15 

Wildlife ES-5, ES-10, ES-11, ES-15, ES-17, 1-27, 1-30, 1-31, 1-37, 1-38, 2-5,

2-15, 2-36, 2-37, 2-63, 2-64, 2-67, 2-89, 2-90, 2-91, 2-96, 2-97, 2-116, 

2-131 - 2-133, 3-2, 3-10, 3-14 - 3-17, 3-27, 3-42, 3-54, 3-56, 3-57, 3-63, 

3-65, 3-66, 3-73 - 3-75, 3-78 - 3-80, 3-83, 3-115, 3-120 - 3-122,4-4, 

4-5, 4-9, 4-19, 4-47 - 4-49, 4-60 - 4-62, 4-68, 4-102, 4-126, 4-127, 

4-129, 4-130, 4-132 - 4-135, 4-143, 4-145, 5-2, 5-4, 5-7, 6-4, 6-5, 6-8, 

7-1, 7-3, 8-1 - 8-3, 8-5 - 8-12, 8-14, 8-16 - 8-19, 8-30, 8-32 - 8-37