FINAL Environmental Impact Statement (EIS) for the

Transcription

1 FINAL Environmental Impact Statement (EIS) for the Mississippi River-Gulf Outlet (MRGO), Louisiana, and Lake Borgne Wetland Creation and Shoreline Protection Project U.S. Army Corps of Engineers New Orleans District June 2009

2 Please direct inquiries on this Final Environmental Impact Statement to Dr. William P. Klein, Jr., Environmental Manager, U.S. Army Corps of Engineers New Orleans District; P.O. Box 60267, New Orleans, LA , (504) , Cover picture is Lake Borgne (foreground), MGRO Channel (middle), and the community of Yscloskey (background). Picture provided by Kenneth Duffy, Ph.D., BEM Systems, Inc.

3 Abstract FINAL ENVIRONMENTAL IMPACT STATEMENT MISSISSIPPI RIVER-GULF OUTLET (MRGO), LOUISIANA, AND LAKE BORGNE Wetland Creation and Shoreline Protection LEAD AGENCY: U.S. Army Corps of Engineers- Mississippi Valley, New Orleans District (CEMVN). ABSTRACT: The U.S. Army Corps of Engineers, New Orleans District (CEMVN), proposes to construct shoreline protection features along the Lake Borgne shoreline and restore and nourish wetlands in the Mississippi River Gulf Outlet (MRGO) and Lake Borgne estuarine complex. Construction of the MRGO, in synergistic combination with other natural and man-made factors, has caused land loss, shoreline erosion, saltwater intrusion, habitat modification, and adversely impacted wildlife and fisheries within the project area. Without action, land loss in the project area is predicted to continue at the same or accelerated rates, with approximately 9,850 acres (3,991 hectares [ha]), including 6,255 acres (2,534 ha) of brackish marsh and 3,595 acres (1,456 ha) of saline marsh, projected to be lost over the 50-year period of analysis. Without action, critical landscape components of this estuarine complex, such as the land bridge separating Lake Borgne and the MRGO, would continue to degrade and fragment thereby increasing the number and size of breaches through the land bridge. The land bridge is an important geomorphic feature that isolates tidal processes in the lake and channel; protects inland barge traffic on the Gulf Intracoastal Waterway; and provides critical and essential fish and wildlife habitat. Recent numerical sensitivity studies generally show that protecting wetlands (preventing their loss) has a net effect of lowering storm surge and wave heights compared to a future condition with extensive wetland loss. 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 knowledge the effect of wetland loss in the area around Lake Borgne on storm surge. Ten alternative plans, with various combinations of wetland creation and nourishment and shoreline protection, were developed and evaluated with the assistance of the U.S. Fish and Wildlife Service as a Cooperating Agency. Screening criteria were developed to select an alternative plan that would best meet the planning goals and objectives. Seven alternative plans were eliminated from further consideration because they did not adequately address the problems or meet all of the planning goals or objectives. Three alternatives (Alternatives 2, 3, and 10) were examined in detail. These three alternatives maximized the number of wetland acres that would be protected and restored, contained elements that would work together to produce a greater overall benefit to the land bridge, and limited detrimental environmental impacts to the project area. Alternative 2 would initially create, nourish, and protect a total of 3,897 acres (1,579 ha) of wetlands with a net total of 2,264 acres (917 ha) of wetlands and a value of 1,278 Average Annual Habitat Units (AAHUs) over the 50-year period of analysis. Alternative 3 would initially create, nourish, and protect a total of 4,050 acres (1,640 ha) of wetlands with a net total of 2,284 acres (925 ha) of wetlands and a value of 1,423 AAHUs over the 50-year period of analysis. Alternative 10 would initially create, nourish, and protect a total of 3,867 acres (1,567 ha) of wetlands with a net total of 2,162 acres (876 ha) of wetlands and a value of 1,189 AAHUs over the 50-year period of analysis. Alternative 10, with total estimated cost of $62,400,000 inclusive of associated investigation, environmental, engineering and design, construction, and supervision, is the Selected Plan (SP). The SP best meets the screening criteria; would accomplish the planning objectives and goals; would be consistent with the Environmental Operating Principles; and would best satisfy the Congressional mandate provided in Public Law and Public Law for the repair, construction or provision of measures or structures necessary to protect, restore or increase wetlands, to prevent saltwater intrusion or storm surge along the MRGO. Comments: Please direct inquiries on this Final Environmental Impact Statement (FEIS) to the U.S. Army Corps of Engineers, New Orleans District, Attention: Dr. William P. Klein, Jr., P.O. Box 60267, New Orleans, Louisiana Telephone: (504) ; FAX: (504) The official closing date for receipt of comments will be 30 days from the date on which the Notice of Availability of the FEIS appeared in the Federal Register (July 20, 2009). Abstract 1

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5 Executive Summary EXECUTIVE SUMMARY S.1 PURPOSE AND NEED FOR ACTION The U.S. Army Corps of Engineers, Mississippi Valley Division, New Orleans District (CEMVN), proposes to construct shoreline protection features along the Lake Borgne shoreline and restore and nourish wetlands in the Mississippi River Gulf Outlet (MRGO) and Lake Borgne estuarine complex. Construction of the MRGO, in synergistic combination with other natural and man-made factors, has caused land loss, shoreline erosion, saltwater intrusion, habitat modifications, and adversely impacted wildlife and fisheries within the project area. Without action, land loss in the project area is predicted to continue at the same or accelerated rates, with approximately 9,850 acres (3,991 hectares [ha]) including 6,255 acres (2,534 ha) of brackish marsh and 3,595 acres (1,456 ha) of saline marsh, projected to be lost over the 50-year period of analysis. Without action, critical landscape components of this estuarine complex, such as the land bridge separating Lake Borgne and the MRGO, would continue to degrade and fragment thereby increasing the number and size of breaches through the land bridge. The land bridge is an important geomorphic feature that isolates tidal processes in the lake and channel; protects inland barge traffic on the Gulf Intracoastal Waterway (GIWW); and provides critical and essential fish and wildlife habitat. Tropical storms and hurricanes with varying levels of storm surge and flood stages have impacted, and would likely continue to impact southeastern Louisiana. Recent numerical sensitivity studies generally show that protecting wetlands (preventing their loss) has a net effect of lowering storm surge and wave heights compared to a future condition with extensive wetland loss. 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 knowledge the effect of wetland loss in the area around Lake Borgne on storm surge. Environmental impacts from the continued degradation and fragmentation of the land bridge would include disruption of natural littoral flows; increased tidal prism; increased hydraulic flushing; degradation and loss of wetlands that provide critical and essential fish and wildlife habitats used for shelter, nesting, feeding, roosting, cover, nursery, and other life requirements; reduction in productivity; degradation and loss of essential fish habitat (EFH), especially transitional habitat between estuarine and marine environments; and increased inter- and intraspecific competition between resident and migratory fish and wildlife species for decreasing wetland resources. S.2 STUDY AUTHORITY In December 2005, the Department of Defense, Emergency Supplemental Appropriations to Address Hurricanes in the Gulf of Mexico, and Pandemic Influenza Act, 2006 (Public Law ) directed the USACE to repair navigation channels and other projects damaged by the 2005 hurricanes and to restore flood damage reduction and hurricane and storm damage reduction projects to the level of protection for which they were designed. The Act appropriated $75,000,000 for authorized operation and maintenance activities along the ES 1

6 Executive Summary Mississippi River-Gulf Outlet channel. In June 2006, Congress clarified the intended purpose of the $75,000,000 appropriated for authorized operation and maintenance activities along the MRGO. Consistent with the language in the Third Supplemental Conference Report, Section 2304 in Title II, Chapter 3 of the Emergency Supplemental Appropriations Act for Defense, the Global War on Terror, and Hurricane Recovery, 2006 (Public Law ) states that the $75,000,000 is 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. S.3 STUDY AREA The 92,217-acre (37,361 ha) project area, part of the Pontchartrain Basin, is located in the vicinity of New Orleans in Orleans and St. Bernard parishes, Louisiana. The project area is located within the St. Bernard delta complex, the oldest deltaic complex within the Mississippi Deltaic Plain Region. The project area is part of the Lake Borgne estuarine complex and is comprised of the MRGO navigation channel and Lake Borgne land bridge and the southern portion of Lake Borgne. S.4 PUBLIC INVOLVEMENT The National Environmental Policy Act provides for an early and open public process for determining the scope of issues, resources, impacts, and alternatives to be addressed in the draft environmental impact statement (DEIS). A Notice Requesting Scoping Comments was sent out on December 8, 2006, to all individuals, organizations, and agencies believed to have an interest in or that may be affected by the proposed action project. The CEMVN also held an interagency meeting on December 19, 2006 to present the proposed action and request comments. A DEIS was released to the public on October 31, 2008, followed by a 45-day public review period. This Final Environmental Impact Statement incorporates the comments received from the 45-day review period of the DEIS. S.5 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 construction and operation of the MRGO contributes to these impacts and what, if any, actions would be necessary to remediate any such impacts remains a controversial issue. Based upon recent sensitivity studies conducted by the Engineer Research and Development Center (ERDC) in support of the South Louisiana Comprehensive Coastal Protection and Restoration (LACPR) evaluation of comprehensive hurricane protection analysis and designs, the loss of wetland areas does increase storm surge and wave potential at the nearby hurricane protection system. 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 knowledge the effect of wetland loss in the area around Lake Borgne on storm surge. ES 2

7 Executive Summary S.6 ALTERNATIVES Alternative plan features were developed as specific solutions that, when properly combined into alternative plans, would meet the project goals and objectives and be consistent with the Congressional mandate. Based upon the problems of wetland loss, shoreline erosion, saltwater intrusion, and storm surge threats in the project area, the PDT initially considered alternative plan features including wetland creation and nourishment, shoreline protection, surge barriers or wave breaks, ridge restoration, vegetative plantings, freshwater diversion, and saltwater barriers. Alternative plan features were combined into ten alternative plans, each with a total construction cost of about $55,000,000. Various combinations and sizes of wetland creation and nourishment and shoreline protection features were developed and evaluated to determine the best combinations of features that would meet the planning objectives. In addition to the No Action Alternative, ten alternative plans with various combinations of wetland creation and nourishment and shoreline protection features were developed and evaluated. Initial evaluation of the ten alternative plans examined how well the combination of features would protect the critical land bridge and complement existing projects, as well as meet the other sorting criteria. Seven alternative plans were eliminated from further consideration and not carried over for detailed analyses. While the features in all of the alternative plans would provide benefits, the alternative plans eliminated from further consideration either did not adequately complement existing/authorized projects along the Lake Borgne shoreline or would not sufficiently meet the other planning objectives, such as protecting the critical land bridge. Initial analysis found Alternatives 2, 3, and 10 would best meet the planning goals and objectives. These three alternatives were subsequently analyzed in greater detail to allow a more thorough comparison of potential benefits. Benefits were measured in three ways: (1) the initial acres created/protected/restored; (2) the net acres created/protected/restored over the 50-year study period; and, (3) Average Annual Habitat Units (AAHUs). Alternative 2. This alternative would create 1,500 acres (608 ha) and nourish 1,350 acres (547 ha) of brackish marsh in the Golden Triangle. Alternative 2 would also construct five shoreline protection features. Foreshore rock dikes would be located along the Lake Borgne shoreline in the Golden Triangle area (17,700 linear feet [lf]; 5,395 m) to protect 223 acres (90 ha); in the vicinity of Bayou Bienvenue (16,230 lf; 4,946 m) to protect 186 acres (75 ha); in the vicinity of Bayou Dupre (17,650 lf; 5,379 m) to protect 142 acres (58 ha); and west of Shell Beach (15,400 lf; 4,694 m) to protect 194 acres (79 ha). One shoreline protection feature would consist of the installation of ACM between Mile 45 and Mile 47 along the southern shoreline of the MRGO (10,840 lf; 3,304 m) to protect 301 acres (122 ha). These shoreline protection features would protect a total of 1,047 acres (424 ha) of adjacent fragmented wetlands from degradation and wave erosion. Alternative 2 would require a total 9.5 million cubic yards (cy) (7.3 million cubic meters) of borrow for wetland creation and nourishment that would be removed from approximately 1,070 acres (433 ha) of Lake Borgne waterbottoms. Alternative 2 would place a total of 284,350 square yards (sq yd) (238,020 sq m) of geotextile fabric and 572,800 tons (565,728 metric tons) of rock for the Lake Borgne shoreline protection features, and 24,600 tons (24,296 metric tons) of crushed rock and 10,840 lf (3,304 m) of ACM along the MRGO shoreline. A total of acres (75.4 ha) of Lake Borgne and MRGO waterbottoms ES 3

8 Executive Summary would be dredged for floatation access. Material dredged for floatation access would be used beneficially to the maximum extent practicable to create wetlands between the shoreline protection dike and the shoreline, or temporarily stockpiled adjacent to the floatation channel and returned to the channel following completion of construction features. Over the 50-year period of analysis Alternative 2 would protect, create and nourish a net total of 2,264 acres (917 ha) and provide 1,278 AAHUs. Alternative 3. This alternative would create 1,400 acres (567 ha) and nourish 1,350 acres (547 ha) of brackish marsh in the Golden Triangle; and create 500 acres (203 ha) and nourish 420 acres (170 ha) of saline marsh in the area west of Shell Beach. Alternative 3 would also construct two shoreline protection features located along the Lake Borgne shoreline in the vicinity of Bayou Bienvenue (16,230 lf; 4,946 m) to protect 186 acres (75 ha) and west of Shell Beach (15,400 lf; 4,694 m) to protect 194 acres (79 ha). These shoreline protection features would protect a total of 381 acres (154 ha) of adjacent fragmented wetlands from degradation and wave erosion. Alternative 3 would require a total 11.4 million cy (8.7 million cubic meters) of borrow for wetland creation and nourishment that would be removed from approximately 1,850 acres (750 ha) of Lake Borgne waterbottoms. Alternative 3 would place a total of 134,000 sq yd (112,167 sq m) of geotextile fabric and 286,200 tons (282,667 metric tons) of crushed rock along the Lake Borgne shoreline. A total of 59.9 acres (24.3 ha) of Lake Borgne waterbottoms would be dredged for floatation access. Material dredged for floatation access would be used beneficially to the maximum extent practicable to create wetlands between the shoreline protection dike and the shoreline, or temporarily stockpiled adjacent to the floatation channel and returned to the channel following completion of construction features. Over the 50-year period of analysis Alternative 3 would protect, create and nourish a net total of 2,284 acres (925 ha) and provide 1,423 AAHUs. Alternative 10. This alternative would create 1,250 acres (506 ha) and nourish 1,400 acres (567 ha) of brackish marsh in the Golden Triangle; and create 425 acres (172 ha) and nourish 270 acres (109 ha) of saline marsh west of Shell Beach. Alternative 10 also includes three shoreline protection features located along the Lake Borgne shoreline: in the vicinity of Bayou Bienvenue (16,230 lf; 4,946 m) to protect 186 acres (75 ha); in the vicinity of Bayou Dupre (17,650 lf; 5,379 m) to protect 142 acres (58 ha); and west of Shell Beach (15,400 lf; 4,694 m) to protect 194 acres (79 ha). These shoreline protection features would protect a total of 522 acres (211 ha) of adjacent wetlands from degradation and wave erosion. Alternative 10 would require a total 9.7 million cy (7.4 million cubic meters) of borrow for wetland creation and nourishment that would be removed from approximately 1,850 acres (750 ha) of Lake Borgne waterbottoms. Alternative 10 would place a total of 208,650 sq yd (174,654 sq m) of geotextile fabric and 423,200 tons (417,975 metric tons) of rock along the Lake Borgne shoreline. A total of acres (47.9 ha) of Lake Borgne waterbottoms would be dredged for floatation access. Material dredged for floatation access would be used beneficially to the maximum extent practicable to create wetlands between the shoreline protection dike and the shoreline, or temporarily stockpiled adjacent to the floatation channel and returned to the channel following completion of construction features. Over the 50-year period of analysis Alternative 10 would protect, create and nourish a net total of 2,162 acres (876 ha) and provide 1,189 AAHUs. ES 4

9 Executive Summary S.7 COMPARISION OF IMPACTS No Action Alternative. Proposed wetland creation/nourishment and shoreline protection features would not be implemented under the No Action Alternative. The No Action Alternative would have no direct impacts on significant resources. Rather, impacts would primarily be indirect and cumulative, and related to continued land loss and shoreline erosion of Lake Borgne and the MRGO, including the eventual loss of the critical land bridge separating these two water bodies. Although the MRGO channel is deauthorized for navigation, land loss in the project area would continue at the same or accelerated rates, with approximately 9,850 acres (3,991 ha), including 6,255 acres (2,534 ha) of brackish marsh and 3,595 acres (1,454 ha) of saline marsh, projected to be lost over the 50-year period of analysis. Continued wetland fragmentation and the eventual conversion to shallow open water habitat would have negative consequences on a variety of important environmental resources in the project area. Indirect impacts would primarily result from the continued wetland loss, degradation, and fragmentation from the land bridge between Lake Borgne and the MRGO. Impacts would include an increase in the acres of water bottoms, disruption of natural littoral flows, increased tidal prism, increased hydraulic flushing, degradation and loss of wetlands that provide important and essential fish and wildlife habitats used for shelter, nesting, feeding, roosting, cover, nursery, and other life requirements; reduction in productivity; conversion of essential fish habitat (EFH) from higher quality categories to lower quality categories, especially from emergent wetlands to open water bottoms; localized decline in commercial fisheries and oyster leases; and increased inter- and intra-specific competition between resident and migratory fish and wildlife species, including endangered and threatened species, for decreasing wetland resources. Plankton and benthic populations would continue their shift towards more salinetolerant species. Continued land loss in the Lake Borgne estuarine complex would threaten cultural and historic resources as well as reduce the aesthetic visual complexity of the area. Wetland-related recreation resources would be potentially lost. Projected land loss would result in increased flows and water levels as area is converted from an estuarine system to a more marinedominated system. There would also be some redistribution of eroded sediments, especially during tropical storms. Other hydrology resources including water use and supply, and groundwater would remain similar to existing conditions. Socioeconomic and human resources within the uninhabited project area would generally be similar to existing conditions, with the following exceptions. Wetland degradation and loss throughout the project area would continue to threaten the stability of existing infrastructure and likely result in increased maintenance and possibly some relocation. Deauthorization of the MRGO provided in the Water Resources Development Act (WRDA) of 2007, coupled with the authorized construction of a closure structure and the Greater New Orleans Hurricane and Storm Damage Risk Reduction System (GNOHSDRRS), would eliminate navigation access from the Gulf of Mexico to New Orleans along this channel. Increasing human populations and infrastructure in surrounding areas would indirectly adversely effect air and water quality in the project area. Under the No Action Alternative, the land bridge between Lake Borgne and the MRGO channel would continue to degrade thereby reducing the storm buffering capability of this estuarine complex. Based upon recent sensitivity studies conduced by the ERDC in support of the ES 5

10 Executive Summary LACPR evaluation of comprehensive hurricane protection analysis and designs, the loss of wetland areas does increase storm surge and wave potential at the hurricane protection system. Increasing the acreage of wetlands in the proposed action area (landbridge between Lake Borgne and the MRGO) will not significantly change storm surge height in this area. A significant increase in wetland acreage in the area could have an effect on storm surge. Cumulative impacts would be the synergistic combination of wetland loss within the land bridge between Lake Borgne and the MRGO with the impacts of other coastal wetland loss, and the benefits of restoration activities. Negative impacts would be offset, to some extent, by the positive benefits of restoration activities in and near the project area, including: the Coastal Wetlands Planning, Protection, and Restoration Act (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 of Features of the authorized GNOHSDRRS 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 would reduce tidal exchange between Lake Borgne and Breton Sound, which is projected to reduce salinities in the project area 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 GNOHSDRRS would alter flow patterns in and near the western end of the project area. These features, in combination with the authorized diversion near Violet, Louisiana, would further reduce salinities to an unknown level. Alternative 10 (Selected Plan [SP]). The land bridge between Lake Borgne and the MRGO is a critical geomorphic feature of the Lake Borgne estuarine complex. Direct impacts of implementing Alternative 10 (SP) include the creation, nourishment, and protection of a total of 3,867 acres (1,567 ha) of brackish and saline wetlands of this critical geomorphic feature. Approximately 1,850 acres (750 ha) of Lake Borgne water bottoms would be unavoidably impacted by removing 9,700,000 cy (7,406,454 cubic meters) of borrow material for marsh creation and nourishment. Other adverse direct impacts would be localized, temporary and primarily related to construction activities. These impacts would include increased turbidity, water temperatures and biological oxygen demand (BOD), and decreased dissolved oxygen. However, these impacts would generally be temporary and waters would return to ambient conditions following completion of construction. Any slow-moving or sessile organisms (e.g., benthic organisms) would likely suffer unavoidable injury or mortality due to dredging operations and placement of fill and rock. Indirect impacts of implementing Alternative 10 (SP) include the creation, nourishment, and protection of a net total of 2,162 acres (876 ha) of brackish and saline wetlands with a value of 1,189 AAHUs over the 50-year period of analysis. Alternative 10 (SP) would restore and protect a large portion of the Lake Borgne estuarine complex that provides important and essential vegetated habitats, especially transitional habitat between estuarine and marine environments. These habitats are used by fish and wildlife for spawning, nursery, nesting, foraging, cover, and predator refugia habitats that support numerous economically and recreationally important fish and wildlife species. Increased wetland vegetative growth and ES 6

11 Executive Summary productivity would also reduce inter- and intra- specific competition between resident and migratory fish and wildlife species for limited coastal vegetated wetland resources. Shoreline protection features would reduce wave-induced erosion and alter sheet flows from Lake Borgne into adjacent emergent wetlands. However, shoreline protection features would be constructed to maintain interconnectivity and allow the ingress and egress of aquatic organisms throughout the Lake Borgne estuarine complex. In addition, natural bayous and other waterways and channels would not be affected by the proposed actions and their existing connectivity would continue. There would be localized changes in flows and sediment accretion and deposition patterns due to shoreline protection features. Shoreline protection features would impede previously open access between Lake Borgne and the brackish and saline emergent wetland marshes. However, shoreline protection features would reduce the wave energy between the dikes and the shoreline, which would encourage deposition of suspended sediments. The project area is remote and uninhabited. Consequently, there would be no direct, indirect or cumulative impacts to socioeconomic and human resources such as populations, employment and personal income, agriculture, or forestry. However, implementing Alternative 10 (SP) would protect and restore some portions of the land bridge between Lake Borgne and the MRGO channel that would provide some socioeconomic and human resource benefits. Alternative 10 (SP) would protect and restore portions of the land bridge that is an important geomorphic feature that isolates tidal processes in the lake and channel; protects inland barge traffic on the Gulf Intracoastal Waterway (GIWW); and provides critical and essential fish and wildlife habitat, especially transitional habitat between estuarine and marine environments that are important for commercial fisheries. Cumulative impacts would be the synergistic effect of the combination of impacts of other wetland loss and the benefits from 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 (13,649 ha); State 2,543 acres (1,030 ha); Mitigation Civil Works 4,990 acres (2,022 ha); Mitigation Regulatory Permits 6,411 acres (2,597 ha); Vegetation 535 acres (217 ha); Section 204/1135, Beneficial Use 226 acres (92 ha); WRDA 16,000 acres (6,482 ha) for a total of 64,410 acres (26,095 ha). The CWPPRA PO-30 and 32 projects are under construction, including the Lake Borgne shoreline between Doulluts Canal and Jahncke s Ditch and the north bank of the MRGO between Mile 40 and Mile These projects would provide shoreline protection near or adjacent to the features in this plan, and would protect portions of the land bridge area between the MRGO channel and Lake Borgne. Additionally, a diversion near Violet, Louisiana, coupled with the closure structure south of Bayou La Loutre and the features of the GNOHSDRRS, would serve to decrease salinities in the project area by up to 6.6 ppt. Alternative 10 (SP) would work synergistically with those projects to provide more complete protection for the land bridge, and increased habitat resources for wildlife and aquatic organisms, including fishery species. These projects would also interact synergistically to increase opportunities for recreation. Alternative 2. Direct, indirect and cumulative impacts of Alternative 2 would be similar to those described for Alternative 10 (SP), with the following exceptions. Alternative 2 would create, nourish, and protect a total of 3,897 acres (1,579 ha) of brackish and saline wetlands. Indirect impacts of implementing Alternative 2 include the creation, nourishment, and ES 7

12 Executive Summary protection of a net total of 2,264 acres (917 ha) of brackish and saline wetlands with a value of 1,278 AAHUs over the 50-year period of analysis. Alternative 3. Direct, indirect and cumulative impacts of Alternative 3 would be similar to those described for Alternative 10 (SP), with the following exceptions. Alternative 3 would create, nourish, and protect a total of 4,050 acres (1,640 ha) of brackish and saline wetlands. Indirect impacts of implementing Alternative 3 include the creation, nourishment, and protection of a net total of 2,284 acres (925 ha) of brackish and saline wetlands with a value of 1,423 AAHUs over the 50-year period of analysis. S.8 THE SELECTED PLAN Of the three alternative plans carried over for detailed analysis, Alternative 10 would best satisfy the Congressional mandate for the repair, construction, or provision of measures or structures necessary to protect, restore or increase wetlands, to prevent saltwater intrusion or storm surge. Alternative 10 best meets the screening criteria and would accomplish the planning objectives and goals. In addition, Alternative 10 would best meet the Economic and Environmental Principles and Guidelines for Water and Related Land Implementation Studies (P&G) criteria of completeness, effectiveness, efficiency, and acceptability. Alternative 10 would also be consistent with the USACE Environmental Operating Principles. Hence, Alternative 10 is the Selected Plan (SP). The SP would create a total of 1,675 acres (679 ha) of marsh and nourish an additional 1,670 acres (677 ha) of emergent wetlands in the Golden Triangle and Shell Beach vicinities. The SP would also provide shoreline protection in the form of foreshore rock dikes along three reaches of the Lake Borgne. Shoreline protection features would protect a total of 522 acres (211 ha) of adjacent wetlands from degradation and wave erosion. Over the 50-year period of analysis, the SP would create, nourish and protect a net total of 2,162 acres (876 ha). S.9 CONCLUSIONS The Selected Plan (SP) would create and nourish approximately 3,345 acres (1,355 ha) of brackish and saline wetlands within the Lake Borgne estuarine complex and provide 49,280 ft (15,020 m), or approximately 9.3 miles (15.0 km), of shoreline protection along Lake Borgne. Primary features of the SP include: 1. Wetland creation and nourishment along the MRGO and Lake Borgne critical land bridge at the Golden Triangle and in the Shell Beach area. 2. Shoreline protection (using foreshore rock dikes) in the vicinity of Bayou Bienvenue, Bayou Dupre, and west of Shell Beach in Lake Borgne. Wetland creation/nourishment and shoreline protection features of the SP would restore fragmented brackish and saline wetlands in the Golden Triangle and Shell Beach areas of the Lake Borgne estuarine complex. This action would also protect and restore a large portion of the MRGO and Lake Borgne critical land bridge; contribute to the overall goals of hurricane protection and wetlands restoration in southeast Louisiana; and foster advancing salinity reduction goals in the Pontchartrain Basin. The SP is the plan that would best meet the planning objectives implicit in the Congressional mandate to repair, construct, or provide measures or structures necessary to protect, restore or ES 8

13 Executive Summary increase wetlands, to prevent saltwater intrusion or storm surge in the MRGO. The SP would also best meet the four P&G criteria of completeness, effectiveness, efficiency, and acceptability. S.10 RECOMMENDATIONS The recommended plan presented in this report is in the overall public interest and a justified expenditure of Federal funds. As a comprehensive approach to protect, stabilize, and augment the land bridge 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 estimated cost for the project is $62,400,000 inclusive of associated investigation, environmental, engineering and design, construction, and supervision. Construction of this project is funded 100 percent by the Federal Government. However, the operations and maintenance of this project would be assumed by the non-federal sponsor (Coastal Protection and Restoration Authority of Louisiana) as recommended by the Legislative EIS prepared for the closure of the MRGO channel. The recommendation contained herein reflects the information available at this time, January 2008 price levels, and current Departmental policies governing the formulation of individual projects. They do not reflect program and budgeting priorities inherent in the formulation of a national civil works construction program, nor the perspective of higher levels of review within the Executive Branch. Consequently, the recommendation may be modified before they are transmitted to the Congress as proposals for authorization and/or implementation funding. ES 9

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15 Table of Contents TABLE OF CONTENTS CHAPTER 1 INTRODUCTION AUTHORITY FOR THE PROPOSED ACTION PROJECT AREA DESCRIPTION PURPOSE AND NEED FOR ACTION Purpose of Action Problems and Need for Action Opportunities GOALS AND OBJECTIVES NATIONAL ENVIRONMENTAL POLICY ACT REQUIREMENTS PRIOR STUDIES, REPORTS, AND PROJECTS Gulf Intracoastal Waterway (GIWW) 1826 and others Mississippi River and Tributaries (MR&T), Bayous La Loutre, St. Malo and Yscloskey, Mississippi River-Gulf Outlet, September Inner Harbor Navigation Canal Lock Study, Lake Pontchartrain and Vicinity, Louisiana, Hurricane Protection Project, Mississippi River Outlets, Venice, Louisiana, MRGO St. Bernard Parish, Louisiana, Reconnaissance Report, February Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA), MRGO North Bank Foreshore Protection Evaluation, Coast 2050: Toward a Sustainable Coastal Louisiana, MRGO Reevaluation Study, Environmental Assessment for the Lake Borgne Shoreline Protection Project, Ecological Review, Lake Borgne and MRGO Shoreline Protection, Continuing Authorities Program Louisiana Coastal Area Ecosystem Restoration Study (LCA Plan), Second Emergency Supplemental Appropriations Act to Meet the Immediate Needs Arising from the Consequences of Hurricane Katrina, 2005 (Public Law ) Emergency Supplemental Appropriations Acts, Coastal Impact Assistance Program, TOC i

16 Table of Contents Louisiana Coastal Protection & Restoration (LACPR), Investigation of the Performance of the New Orleans Flood Protection Systems in Hurricane Katrina on August 29, 2005, Final Report, July Performance Evaluation of the New Orleans and Southeast Louisiana Hurricane Protection System, Draft Final Report of the Interagency Performance Evaluation Task (IPET) Force, USACE, Violet Freshwater Distribution (Deauthorized as of September 11, 2006) Integrated Ecosystem Restoration and Hurricane Protection: Louisiana s Comprehensive Master Plan for a Sustainable Coast, Water Resources Development Act of Individual Environmental Report (IER), #11 Improved Protection on the Inner Harbor Navigation Canal, Orleans and St. Bernard Parishes, Louisiana, Mississippi River Gulf Outlet Environmental Restoration, ongoing efforts Integrated Final Report to Congress and Legislative Environmental Impact Statement for the MRGO Deep-Draft Deauthorization Study, Mississippi River Gulf Outlet Operations and Maintenance Mississippi River Gulf Outlet Ecosystem Restoration Plan Feasibility Study Storm Surge Risk Reduction Projects Environmental Assessments and Environmental Impact Statements CHAPTER 2 ALTERNATIVES GENERAL PLAN FORMULATION Overview Preliminary Alternative Plan Formulation Environmental Operating Principles Planning Approach DEVELOPMENT AND EVALUATION OF FEATURES Development of Alternative Plan Features Wetland Creation and Nourishment Shoreline Protection Features Surge Barriers and/or Wave Breaks Ridge Restoration Vegetative Plantings Freshwater Diversions Saltwater Barriers Screening Alternative Plan Features TOC ii

17 Table of Contents Features Having Major Value Wetland Creation and Nourishment Shoreline Protection Features Features Having Limited or No Value DEVELOPMENT AND SCREENING OF ALTERNATIVE PLANS Development of Alternative Plans Description of Alternative Plans Plans Not Carried Over for Detailed Analysis Alternative Plans Retained for Detailed Analysis Plan 2 Summary Plan 3 Summary Plan 10 Summary NO-ACTION ALTERNATIVE PLAN FORMULATION RESULTS Description of the Selected Plan (SP) Components of the Selected Plan Effectiveness of the SP in Meeting Objectives and Goals Effectiveness of the SP in Meeting Environmental Operating Principles Project Costs Plan Implementation and Accomplishments Summary of Tentatively Selected Plan Accomplishments CHAPTER 3 AFFECTED ENVIRONMENT GENERAL CLIMATE GEOMORPHIC AND PHYSIOGRAPHIC SETTING SOILS Historic and Existing Conditions COASTAL VEGETATION RESOURCES Historic and Existing Conditions WILDLIFE RESOURCES Historic and Existing Conditions FISHERY RESOURCES General Historic and Existing Conditions Finfish Shrimp TOC iii

18 Table of Contents Blue Crab Oyster PLANKTON RESOURCES Historic and Existing Conditions WATER BOTTOMS AND BENTHIC RESOURCES ESSENTIAL FISH HABITAT Historic and Existing Conditions ENDANGERED AND THREATENED SPECIES Historic and Existing Conditions HYDROLOGY Flow and Water Levels Historic and Existing Conditions Sediment Historic and Existing Conditions WATER QUALITY Historic and Existing Conditions Salinity RECREATIONAL RESOURCES Historic and Existing Conditions PUBLIC LANDS Historic and Existing Conditions CULTURAL RESOURCES INCLUDING NATIONAL REGISTER LISTINGS Historic and Existing Conditions Cultural Setting Previous Investigations Previously Conducted Cultural Resources Surveys AESTHETICS Historic and Existing Conditions Scenic Rivers and Streams NOISE Historic and Existing Conditions AIR QUALITY Historic and Existing Conditions SOCIECONOMIC AND HUMAN RESOURCES Historic and Existing Conditions Population TOC iv

19 Table of Contents Infrastructure Employment and Income Navigation Oil, Gas and Utilities Pipelines Commercial Fisheries Oyster Leases Flood Control and Hurricane Protection Levees HAZARDOUS, TOXIC AND RADIOACTIVE WASTES Historic and Existing Conditions CHAPTER 4 ENVIRONMENTAL CONSEQUENCES SOILS The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts COASTAL VEGETATION RESOURCES The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts WILDLIFE RESOURCES The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts FISHERY RESOURCES The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts PLANKTON RESOURCES The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts WATER BOTTOMS AND BENTHIC RESOURCES TOC v

20 Table of Contents The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts ESSENTIAL FISH HABITAT (EFH) The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts ENDANGERED AND THREATENED SPECIES The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts HYDROLOGY RESOURCES Flow and Water Levels The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Condition Indirect Impacts Future With Project Conditions Cumulative Impacts Sediment The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Condition Indirect Impacts Future With Project Conditions Cumulative Impacts WATER QUALITY RESOURCES The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts Salinity Regimes The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts RECREATIONAL RESOURCES The No-Action Alternative Future With Project Conditions Direct Impacts TOC vi

21 Table of Contents Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts PUBLIC LANDS The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts CULTURAL RESOURCES INCLUDING NATIONAL REGISTER LISTINGS The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts AESTHETICS The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts NOISE The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts AIR QUALITY The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts SOCIOECONOMIC AND HUMAN RESOURCES Population The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts Infrastructure The No-Action Alternative Future With Project Conditions Direct Impacts TOC vii

22 Table of Contents Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts Employment and Income The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts Navigation The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts Oil, Gas and Utilities Pipelines The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts Commercial Fisheries The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts Oyster Leases The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts Flood Control and Hurricane Protection Levees The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts HAZARDOUS, TOXIC, AND RADIOLOGICAL WASTE (HTRW) The No-Action Alternative Future With Project Conditions Direct Impacts Future With Project Conditions Indirect Impacts Future With Project Conditions Cumulative Impacts TOC viii