6
The LCA Study and the Feasibility of Its Components

HIGHLIGHTS

This chapter

  • Describes and reviews various Louisiana Coastal Area (LCA), Louisiana—Ecosystem Restoration Study (LCA Study) elements, including economic analysis

  • Provides an overview of the LCA Study’s feasibility

  • Discusses the modeling strengths and uncertainties and recommends a protocol for future conduct of the modeling program

  • Addresses the role of adaptive management and examines management alternatives

  • Suggests Third Delta alternatives, including a large, more southern diversion and a full abandonment of the Birdsfoot Delta

The activities proposed in the LCA Study are intended to be a series of interactive efforts that develop the necessary knowledge base to inform longer-term and possibly more expansive restoration efforts, while making some near-term progress by undertaking relatively low-risk projects that will result in a tangible development of what the LCA Study refers to as near-term critical restoration features. The success of these parallel efforts to slow land loss, while developing information needed to support



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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana 6 The LCA Study and the Feasibility of Its Components HIGHLIGHTS This chapter Describes and reviews various Louisiana Coastal Area (LCA), Louisiana—Ecosystem Restoration Study (LCA Study) elements, including economic analysis Provides an overview of the LCA Study’s feasibility Discusses the modeling strengths and uncertainties and recommends a protocol for future conduct of the modeling program Addresses the role of adaptive management and examines management alternatives Suggests Third Delta alternatives, including a large, more southern diversion and a full abandonment of the Birdsfoot Delta The activities proposed in the LCA Study are intended to be a series of interactive efforts that develop the necessary knowledge base to inform longer-term and possibly more expansive restoration efforts, while making some near-term progress by undertaking relatively low-risk projects that will result in a tangible development of what the LCA Study refers to as near-term critical restoration features. The success of these parallel efforts to slow land loss, while developing information needed to support

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana more aggressive project design, is a key component of the strategic approach championed in the LCA Study. As can be seen in Table 6.1, significant resources have been requested to further the study of various scientific and engineering challenges and to help integrate the results and other lessons learned into the overall program management process. The commitment to continued study further underscores the emphasis the LCA Study places on developing a two-pronged approach. The principal restoration efforts proposed in the LCA Study are directed at the development of five restoration features, where each feature may be completed through either a single project or a series of individual projects. The conditionally authorized cost of the five features, including land easements, rights of way, relocation, and disposal, is estimated to be roughly $864 million. Development of the underlining knowledge base to undertake more robust restoration efforts comprises three additional components of the LCA Study, with a combined budget of $300 million. The first two components include applied research (carried out as part of the Science and Technology [S&T] Program with an estimated budget of $100 million) and formally described demonstration projects (with an estimated budget of $100 million). Lessons learned in dealing with emerging challenges and information developed through the demonstration projects and the S&T Program are expected to enter the ongoing program management decision process through the third component, a formal adaptive management process referred to as Adaptive Environmental Assessment and Management (AEAM; also with an estimated cost of $100 million). This chapter reviews each of these components of the LCA Study in turn, beginning with proposed on-the-ground restoration projects. TABLE 6.1 LCA Study Estimated Restoration Costs Item Cost Mississippi River Gulf Outlet environmental restoration features $80,000,000 Small diversion at Hope Canal $10,645,000 Barataria Basin barrier shoreline restoration $181,000,000 Small Bayou Lafourche reintroduction $75,280,000 Medium diversion with dedicated dredging at Myrtle Grove $142,920,000   Subtotal $489,845,000 Land easements, rights of way, relocation, and disposal $178,619,000 First cost Subtotal $668,464,000 Feasibility-level decision documents $54,673,000 Preconstruction, engineering, and design $36,252,000 Engineering and design $29,018,000 Supervision and administration $68,973,000 Project monitoring $6,685,000

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana Item Cost Conventionally authorizeda cost Subtotal $864,065,000 Science and Technology Program (10 years) $100,000,000 Demonstration program (10 years)b $100,000,000 Beneficial use of dredge material programb $100,000,000 Investigations of modifications of existing structures $10,000,000 Authorized total LCA Study cost $1,174,065,000 Multipurpose operation of Houma Navigation Canal Lockc — Terrebonne Basin barrier shoreline restoration $84,850,000 Maintain land bridge between Caillou Lake and Gulf of Mexico $41,000,000 Small diversion at Convent/Blind River $28,564,000 Increase Amite River Diversion Canal influence by gapping banks $2,855,000 Medium diversion at White’s Ditch $35,200,000 Stabilize Gulf shoreline at Point Au Fer Island $32,000,000 Convey Atchafalaya River water to northern Terrebonne marshes $132,200,000 Modification of Caernarvon diversion $1,800,000 Modification of Davis Pond diversion $1,800,000   Subtotal $360,269,000 Land easements, rights of way, relocation, and disposal $208,100,000 First cost Subtotal $568,369,000 Feasibility-level decision documents $47,529,000 Preconstruction, engineering, and design $36,027,000 Engineering and design $45,635,000 Supervision and administration $58,673,000 Project monitoring $5,683,000 Approved projects requiring future Congressional authorization for construction $761,916,000 Mississippi River hydrodynamic study $10,250,000 Mississippi River Delta management study $15,350,000 Third Delta study $15,290,000 Chenier Plain freshwater and sediment management and allocation reassessment study $12,000,000 Acadiana Bays estuarine restoration feasibility study $7,110,000 Upper Atchafalaya Basin studyd — Large-scale and long-term studies cost Subtotal $60,000,000 Total LCA Study restoration cost $1,995,981,000 a“Conventionally authorized” refers to items proposed in the Chief’s Report and authorized by Congress through the Water Resources Development Act. bProgram total costs include any estimated real estate costs for these activities. cFeature of the Mississippi River and Tributaries’ Morganza, Louisiana, to the Gulf of Mexico Hurricane Protection Project. dStudy to be funded under the Mississippi River and Tributaries Authority. SOURCE: U.S. Army Corps of Engineers, 2004a. (Refer to U.S. Army Corps of Engineers [2005b] for cost revisions.)

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana THE FIVE MAJOR RESTORATION FEATURES Five near-term critical restoration features were selected utilizing the criteria discussed in the previous chapter. A brief description of each (excerpted from the LCA Study) follows. Although these features represent the most significant component of the restoration efforts evaluated in the LCA Study, they are still only the first stage of a long-term restoration program for coastal Louisiana. Mississippi River Gulf Outlet Discussed at length in Chapter 3, the Mississippi River Gulf Outlet (MRGO), originally defined as a restoration study during the framework selection process, appears in the final project description as consisting of the construction of 61.2 kilometers (km) (38 miles [mi]) of rock breakwaters to prevent high rates of erosion along the north bank of MRGO and at critical points along the southern shoreline of Lake Borgne that are in peril of breaching (U.S. Army Corps of Engineers, 2004a). This feature is expected to protect 25.7 square kilometers (km2) (9.9 square miles [mi2]) of marsh over the next 50 years at a cost of $108.3 million1 (or $42,140 per hectare [$17,052 per acre]). It is interesting to note the recommended change for MRGO from closure in Coast 2050: Toward a Sustainable Coastal Louisiana (Coast 2050) to a study and then to repair in the LCA Study. Of the five features, the justification for MRGO is the most poorly documented and appears to be the weakest. In 2004, a concurrent resolution was passed by the Louisiana State House and Senate calling on the U.S. Army Corps of Engineers (USACE) to “promptly close” MRGO. At the time of this writing, some speculation about the role MRGO may have played in enhancing the storm surge during Katrina and the subsequent flooding of St. Bernard Parish was being put forward. What is known is that the levee that separates MRGO from St. Bernard Parish was topped during Katrina, as predicted in advance by some storm surge models. Small Diversion at Hope Canal The Hope Canal diversion includes construction of culverts in the Mississippi River levee and a receiving pond reinforced with riprap to slow flow and remove heavy sand, excavation of a new leveed channel from the existing south terminus of Hope Canal, enlargement of the Hope 1   USACE, in the 2005 Chief’s Report, updated the cost of the proposed MRGO feature to be $105.3 million (U.S. Army Corps of Engineers, 2005b).

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana Canal cross section, implementation of outfall management measures to direct water to the Maurepas Swamp, and installation of navigable constrictions. The feature is designed to restore approximately 145 km2 (56 mi2) of swamp at a cost of $70.5 million2 (or $4,862 per hectare [$1,967 per acre]) (U.S. Army Corps of Engineers, 2004a). Barataria Basin Barrier Shoreline Restoration This feature involves dredging and placement of sand from Ship Shoal onto Caminada Headland and Shell Island (east and west), sediment nourishment and replanting of eroding marsh and dune, and removal of failing breakwaters. These activities are expected to increase dune and berm area by 2.6 km2 (1 mi2) and saline marsh area by 7.2 km2 (2.8 mi2) on Caminada Headland and to increase barrier island habitat by 0.6 km2 (0.2 mi2) on Shell Island over the next 50 years at a cost of $247.2 million3 (or $237,692 per hectare [$96,187 per acre]) (U.S. Army Corps of Engineers, 2004a). Small Bayou Lafourche Reintroduction This feature will upgrade the existing sediment slurry pump and siphon facility to operate at the full capacity (9.6 cubic meters [m3] per sec [12.9 cubic yards {yd3} per sec]), construct a new 18.7 m3 per sec (24.5 yd3 per sec) pump facility, improve channel capacity by dredging and weir removal, stabilize the channel bank, operate water monitoring stations, install adjustable weirs at Thibodeaux and Donaldsonville to control water levels, and construct a sediment trap at Donaldsonville to control main channel siltation. The estimated cost is $144.1 million.4 This feature proposes reliance on a heavily engineered approach (i.e., pumping sediment-laden water) with significant constructed features rather than recreating a more natural distributary channel. After 50 years, there would be approximately 10.1 km2 (3.9 mi2) more marsh (at a cost of $142,673 per hectare [$57,732 per acre]) in the project area than if the feature were not built (U.S. Army Corps of Engineers, 2004a). 2   USACE, in the 2005 Chief’s Report, updated the cost of the small diversion at Hope Canal to be $68.6 million (U.S. Army Corps of Engineers, 2005b). 3   USACE, in the 2005 Chief’s Report, updated the cost of the Barataria Basin shoreline restoration feature to be $242.6 million (U.S. Army Corps of Engineers, 2005b). 4   USACE, in the 2005 Chief’s Report, updated the cost of the small Bayou Lafourche reintroduction to be $133.5 million (U.S. Army Corps of Engineers, 2005b).

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana Medium Diversion with Dedicated Dredging at Myrtle Grove Major elements of this feature are a gated diversion structure near Myrtle Grove with 141.6 m3 per sec (185.2 yd3 per sec) capacity, inflow, and outflow channels (4,877 meters [m] [16,000 feet {ft}]); channel guide levees and infrastructure relocation; and creation of 26.3 km2 (10.2 mi2) of new marsh through dedicated dredging. The estimated cost is $294 million5 (or $111,787 per hectare [$45,238 per acre]). It is expected to prevent significant loss of intermediate, brackish, and saline marsh in the Barataria Basin (despite continued soil subsidence) and to improve sustainability of the Lafitte and Barataria communities and industries. This feature would support opportunities for demonstration projects and AEAM efforts (U.S. Army Corps of Engineers, 2004a). OTHER ELEMENTS OF THE LCA STUDY The Mississippi Valley, New Orleans District of USACE has the largest channel operations and maintenance program in USACE dredging 54 million m3 (70.6 million yd3) annually. More than 11 million m3 (14.4 million yd3) is used beneficially. The LCA Study requests authority for beneficial use of the sediment up to an additional 23 million m3 (30.1 million yd3) (U.S. Army Corps of Engineers, 2004a). USACE has also requested authority to investigate modification of existing structures, such as Davis Pond, Bonnet Carre Spillway, MRGO, Bayou Sorrel Lock, and Leland Bowman Lock (U.S. Army Corps of Engineers, 2004a). Demonstration Projects Five demonstration projects are included in the LCA Study. These projects are intended to support long-range planning and, in some cases, may represent precursors to larger-scale future projects. Some are synergistic with major projects or their components. The generic characteristics of these projects encompass the following: (1) marsh restoration and/or creation using nonnative sediment, (2) marsh restoration using long-distance conveyance of sediment, (3) canal restoration using different methods, (4) shoreline erosion prevention using different methods, and (5) barrier island restoration using offshore and riverine sources of sediment. 5   USACE, in the 2005 Chief’s Report, updated the cost of the medium diversion at Myrtle Grove to be $278.3 million (U.S. Army Corps of Engineers, 2005b).

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana Science and Technology Program The goal of the S&T Program is to provide a sound basis to effectively address coastal ecosystem restoration needs. It is intended to improve coastal restoration decision making; provide scientific data, analysis, and interpretation; develop tools, methods, and protocols for restoration planning and assessment; minimize knowledge gaps that limit restoration planning and execution; assess the effectiveness of restoration actions in meeting LCA Study goals; and provide information and synthesis in a rapid and useful manner. Key tools to accomplish these goals are considered to be sound baseline data, monitoring over time and space, models, data management, and continued research. Cyber-infrastructure will have to be a key component of the S&T Program to facilitate access to information and communication among agencies, universities, other interested parties, and the general public. The program management called for in the LCA Study includes independent technical review committees and advisory boards and reviews of existing data through conferences and meetings (Figure 4.5) (U.S. Army Corps of Engineers, 2004a). An annual review and update is planned. The S&T Program, as described in the LCA Study, focuses on the physical and natural sciences. Although this is appropriate, the impacts on the human population are also important. Therefore, economic, urban planning, sociological, and public policy expertise in the S&T Program appears to be insufficient. There is an inherent conflict between the required independence of the S&T office from the LCA Study management and the need for significant involvement and insertion of S&T results into LCA Study decision making that is critical for adaptive management. Since the skills needed for this type of interdisciplinary work are not readily available, LCA Study planners have to acknowledge and strive to resolve or, at least, reduce the impact of this conflict. Modeling A key role for the S&T office is development of analytical tools. This includes development, revision, and refinement of hydrodynamic and ecosystem modeling, which is considered fundamental to the S&T charge. Appendixes A and C of the LCA Study (U.S. Army Corps of Engineers, 2004a) outline the key roles of models and the different types of mathematical models—natural and resource, engineering, and economic. (See Chapter 5 for detailed discussion and analysis of the modeling used to develop the LCA Study.)

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana Peer Review Peer review of program planning is considered a key element; yet, it is unclear who will identify and select peer reviewers and what pool of candidates might be considered (U.S. Army Corps of Engineers, 2004a). As recommended in the National Research Council (2002) report Review Procedures for Water Resources Project Planning, complex water resources project planning studies undertaken by USACE should be subject to external, independent review. One or more panels of impartial, highly qualified experts should conduct this external review. External review panels should not include USACE staff members and should not be selected by USACE. External reviews should be overseen by an organization independent of USACE, which will provide the highest degree of credibility of review (National Research Council, 2002). Uncertainties A primary role of the S&T office is the identification of uncertainties and funding for projects to reduce these uncertainties. The LCA Study (U.S. Army Corps of Engineers, 2004a) describes these knowledge gaps as “uncertainties” and lists the following four types: Type 1: Physical, chemical, geological, and biological baseline conditions Type 2: Engineering concepts and operational methods Type 3: Ecological processes, analytical tools, and ecosystem response Type 4: Socioeconomic and political conditions and responses These knowledge gaps are real, and the proposed demonstration projects to alleviate these deficiencies are definitely valid. However, the LCA Study fails to acknowledge several other important knowledge gaps, which are discussed at some length in Chapter 7. More specific guidance to address uncertainties or knowledge gaps is also presented in Chapter 7; however, it is appropriate in this discussion of the interactions with various components of the S&T Program to point out that the LCA Study appears to place insufficient emphasis on some key strategies for reducing uncertainties of this type: (1) use of existing literature and information; (2) use of available but uncollated and unsynthesized data; (3) professional experience; (4) bench-, micro-, and mesocosm-scale studies; (5) expansion of existing projects; (6) field trials using intermediate-scale demonstrations; (7) prototype-scale demonstrations; (8) undertaking these analyses within a formal adaptive management process; and (9) application of numerical models.

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana ADAPTIVE MANAGEMENT The adaptive management process for the LCA Study is referred to as AEAM (U.S. Army Corps of Engineers, 2004a). The theory, importance, and essential elements of a successful adaptive management process for natural resources management are well documented in Adaptive Management for Water Resources Project Planning (National Research Council, 2004b). The six identified elements of adaptive management are as follows: Management objectives that are routinely reviewed and revised, as needed Management system model(s) A variety of management choices The monitoring and evaluating of outcomes Mechanism(s) to include lessons learned in future decisions A collaborative method for stakeholder involvement and education The underlying premises of the AEAM process are that (1) knowledge gaps exist when attempting to manipulate a large-scale ecosystem and (2) a need exists for an iterative and flexible approach to management and decision making. Therefore, the AEAM process is designed to allow for future actions to be changed based on observing the efficacy of past actions on the ecosystem. AEAM is also important in dealing with wicked problems (see Chapter 5), wicked unknowns, and decision-making relationships. The AEAM process is described in the LCA Study as supporting passive adaptive management, which currently occurs with Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA) projects, and active adaptive management, as used with the Caernarvon Freshwater Diversion. The proposed AEAM process indicates that all organizations within the LCA Study’s management structure have a role in implementing AEAM; however, the S&T office will have primary responsibility for making recommendations to the program management team (PMT) and the program execution team, based on the assessment of monitoring data and the development of new technologies (U.S. Army Corps of Engineers, 2004a). These two teams then formulate and implement any needed adjustments to the program or projects. The AEAM process is proposed as a three-phase cycle consisting of (1) decision making by PMT; (2) implementation by the program execution team (physical and operational); and (3) monitoring, assessment, and reporting by the S&T office. A review of the AEAM process indicates an

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana appropriate effort to integrate sound science in understanding the efficacy of past actions on the ecosystem in order to modify or change future actions. Effective adaptive management is, and will continue to be, critical to the long-term success of the Louisiana restoration program. It is not clear what mechanisms are in place to incorporate the “learning” aspect of monitoring and assessment outcomes. Although the role of science (especially monitoring and assessment) is a central principle of adaptive management, an effective adaptive management process is much more than just the integration of good science. Adaptive management is a process that requires the integration of learning and adaptation throughout all aspects of decision making and implementation (National Research Council, 2004b). To successfully evaluate the efficacy of Louisiana’s restoration activities, objectives must be developed for the overall program, as well as for individual projects. These objectives have to be clear, specific, quantifiable, and at a scale appropriate to their purpose. Of particular importance are project-level objectives against which monitoring outcomes will be assessed. The absence of such objectives creates knowledge gaps and ambiguity as to what future adjustments need to be made, as well as to the success of the restoration effort. AEAM will depend heavily on routine and continuous monitoring, numerical model application and data, and information management and communication. (See U.S. Army Corps of Engineers’ [2004a] Appendix A for details.) These activities are envisioned as taking place entirely within the domain of Louisiana’s coastal area. There is no acknowledgment that major national investments are being made and will soon be accelerated in connection with the coastal ocean observing and watershed monitoring programs. Opportunities currently exist for the coastal Louisiana restoration to coordinate activities with ongoing environmental data collection efforts to avoid wasteful duplications and take advantage of resources that will be funded from outside the restoration budget. If the information that emerges from restoration observations and model output is to be credible and utilized effectively by others (thus maximizing the benefit of data collection), it should comply with a set of standards and information communication protocols that are now in an intermediate stage of development under the auspices of the data management and communication working group within the Ocean.US integrated and sustained ocean observing system. Finally, one of the essential elements required in a successful adaptive management process is the inclusion of a collaborative structure for stakeholder participation and learning. Stakeholder participation is missing from the AEAM process, and meaningful stakeholder involvement seems to be absent in the overall implementation of the LCA Study. As

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana stated by the National Research Council (2004b), “achieving meaningful stakeholder involvement that includes give and take, active learning (through cooperation with scientists), and some level of agreement among participants, represents a challenge but is essential to adaptive management” (emphasis added). Stakeholder participation needs to be part of AEAM and should include, at a minimum, representatives from local government, industry, key organizations, and citizens at large. PROPOSED MANAGEMENT APPROACHES The LCA Study presents the proposed management structure of the restoration program and describes the roles of the various entities involved in the implementation of this program (Figure 4.5). What is more important is a description of what the entities will do; this description lacks crucial information regarding the institutional mechanisms of how they will do it. The proposed decision support system is supposed to overcome this problem. “Management of the [Louisiana] restoration efforts would also include a decision support system that relies on clearly defined procedures to assess knowledge gaps and develop alternatives for the decision-making process” (U.S. Army Corps of Engineers, 2004a). The effectiveness of the decision support system will be one of the determining factors in the success of the restoration program, and its development should be peer-reviewed prior to adoption. A review of the proposed management structure and of the description of roles reveals several areas in which further clarification and modification are appropriate. The organizational structure includes a recommendation for the U.S. Congress to authorize the establishment of a task force whose purpose would be to “facilitate coordination and collaboration among various agencies involved in implementation of major coastal restoration activities and provide recommendations to the Secretary of the Army” (U.S. Army Corps of Engineers, 2004a). Establishment of such a task force would be beneficial to the restoration program by ensuring senior-level support among the key participants in the program; however, the benefit of having a regional working group separate from PMT is not clear. It would be more efficient, ensure better participation and commitment, and strengthen linkages between the senior agency officials and the restoration program for PMT to be expanded to include the regional federal agency representatives. The LCA Study’s management strategies rely heavily on the interaction of numerous groups and committees that will provide direction, assessment, and feedback to the program through an adaptive management process. The success of implementing an effective adaptive management process will rely heavily on day-to-day lines of communication, resolute

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana Third Delta The Third Delta envisioned in the LCA Study would divert water from the Mississippi River near Donaldsville through a 88.5-km (55-mi) long conveyance channel to the Barataria and Terrebonne Basins (Regions 2 and 3) as shown in Figure 6.3. Two diversion designs with maximum river discharges of 3,398 m3 per sec (4,444 yd3 per sec) and 6,796 m3 per sec (8,889 yd3 per sec) are envisioned in the LCA Study. Examined below are the present and projected land loss rates, the wetland formation benefits of a Third Delta, and the anticipated difficulties. The projected land changes resulting from current CWPPRA and LCA Study projects over the next 50 years are summarized in Table 6.2 (U.S. Army Corps of Engineers, 2004a). If the land gain and loss estimates are correct, there will be an average net land loss of 26.7 km2 per yr (10.3 mi2 per yr) without construction and implementation of the LCA Study’s five recommended restoration features. Implementing these restoration efforts would reduce this land loss by 4.4 km2 per yr (1.7 mi2 per yr) to 22.3 km2 per yr (8.6 mi2 per yr) at a cost of approximately $20 million per km2 ($51 million per mi2) of reduced loss over this 10-year period; however, the wetland benefits (gains or loss prevention) are projected to continue over 50 years, thereby reducing the cost per unit area. At these unit costs, the annual cost required to eliminate net land losses would be approximately $525 million using 10-year rates or $105 million using 50-year rates. “The goal of [the projects proposed in] the LCA [Study] is to reverse the current trend of degradation of the coastal ecosystem” (U.S. Army Corps of Engineers, 2004a), which will require reducing unit costs of land gain and loss prevention to the degree possible. The Third Delta is one means of potentially reducing the unit costs through the delivery of large volumes of sediment and the associated economies of scale. To evaluate the efficacy of the Third Delta in sediment delivery and relative wetland gain, it is useful to develop very approximate conversion factors between a unit of water diverted and a unit area of wetland gain. This can be based on the combined average discharges of the Mississippi and Atchafalaya Rivers and their associated mineral sediment loads, as summarized in Table 6.3, and on the approximation that one unit of mineral sediment will result in 4–10 units of wetland volume and that the average effective vertical dimension of wetland generated is 2 m (6.6 ft). These conversion ratios are shown in Table 6.4. Thus, it appears that within the assumptions and considerations applied, implementation of the Third Delta project could more than offset projected net losses; however, the resulting gain would not occur in the same locations or possibly with the same wetland quality as the losses. As noted, the Third Delta as planned would not contribute to the reinstate-

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana FIGURE 6.3 Various restoration features considered, including the Third Delta (U.S. Army Corps of Engineers, 2004a; used with permission from the U.S. Army Corps of Engineers). (NOTE: cfs = cubic feet per sec.)

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana TABLE 6.2 Land Change Projections Under Various Considerations Consideration Land Changes in km2 per yr (mi2 per yr in parentheses) Loss reduction due to funded CWPPRA and other projects 6.7 (2.6) Existing situation with funded CWPPRA and other projects –26.7 (–10.3) Anticipated reduction due to the LCA Study 4.4 (1.7) Net change with the LCA Study –22.3 (–8.6) SOURCE: Modified from U.S. Army Corps of Engineers, 2004a. TABLE 6.3 Estimates of Average Annual River Flows and Sediment Delivery Combined Average Mississippi River and Atchafalaya River Flows in m3 per sec (yd3 per sec in parentheses) Combined Mineral Sediment Delivery in m3 per sec (yd3 per sec in parentheses) 19,737 (25,815) 4 (5) SOURCE: Data from U.S. Geological Survey, 2005. TABLE 6.4 Wetland Gain Based on Third Delta Diversion Discharge Rates Design Maximum Discharge in m3 per sec (yd3 per sec in parentheses) Ratio (R) of Mineral Sediment to Wetland Volume Annual Wetland Gain/Loss Prevention in km2 per yr (mi2 per yr in parentheses) R = 1:4 R = 1:10 3,398 (4,444) 10.9 (4.2) 28.0 (10.8) 6,796 (8,889) 22.3 (8.6) 55.9 (21.6) NOTE: These calculations are based on the average diversion discharges of one-quarter the maxima. For a ratio of 1:4 mineral sediment to wetland gain, 1 yd3 per sec = 0.0034 acres per yr = 0.00014 mi2 per yr, and for a ratio of 1:10 mineral sediment to wetland gain, 1 yd3 per sec = 0.0085 acres per yr = 0.00036 mi2 per yr.

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana ment or maintenance of the barrier islands since most of the sediment would be finer than required for barrier island purposes. The barrier island restoration in the first five LCA Study projects may provide some of the sediment for barrier island restoration at the lower end of the Third Delta (Figure 6.3). Anticipated Third Delta Challenges The Third Delta challenges are broad and include engineering, ecological, and social dimensions. Here, the emphasis is on the stakeholders with issues of real estate (including obtaining right of way) and habitat, each of which could delay the Third Delta project indefinitely. The project, as described in the LCA Study, includes the construction of a 88.5-km (55-mi) long conveyance channel through both public and private property and the discharge of freshwater into Barataria and Terrebonne Basins. Securing right of way and other real estate issues could be costly and present political challenges, each of which could prove to be insurmountable. Despite USACE’s power to take possession before questions of compensation have been settled, real estate issues could take decades to resolve with many costly and lengthy legal and political challenges. Although the Third Delta design may provide an overall benefit for stakeholders, some will recognize early benefits and some either will be impacted adversely or will perceive or claim this to be the case. If initial investigations indicate that insurmountable difficulties exist with implementation of the Third Delta as now planned, it is suggested that an alternate plan be considered, such as a diversion much farther south, leaving a “slack water” channel gulfward. This option and the associated merits and challenges are discussed in more detail in Chapter 7. Abandonment of the Active Birdsfoot Delta Another alternative that has not yet received serious consideration or assessment by the LCA Study is the complete abandonment of the Birdsfoot Delta. As noted in Chapter 2, coastal dispersal of Mississippi River sediment has been dominated more by the processes of episodic avulsion of deltaic lobes than by ocean forcings (Wright and Nittrouer, 1995). This is of fundamental importance to understanding how the Louisiana coast differs from other deltaic coasts and is attributable in large measure to the generally low-energy ocean conditions that prevail except during storm events (Wright, 1995). Recent field studies on the Louisiana inner continental shelf have shown that fair weather conditions are incapable of resuspending and transporting recently deposited muds most of the time (Wright et al., 1997). For this reason, historically, elongated and

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana relatively delicate delta lobes have extended well across the shelf before being abandoned and ultimately destroyed by storm waves. Today, however, the prevalence of low-energy conditions is only partially responsible for the anomalous Birdsfoot Delta that crosses the entire Louisiana shelf before discharging its (potentially) coast-nourishing sediment load near the shelf break. Human intervention has reinforced this outcome. Not only does this impede the along-shelf transport system, it deprives the coastal areas to the west of land-replenishing sediment, including marsh-building muds, as well as fine sands that could nourish barrier islands. If the sediment that presently enters the Gulf of Mexico via Southwest Pass, South Pass, and Pass al’Outre were to enter further to the west in shallower waters, the sediment would be delivered where it would be more effective for wetland formation. In addition, the eventual disappearance of the Birdsfoot Delta protrusion would lead to a restructuring of the shelf physical ocean conditions and probably to a moderate strengthening of east-to-west flows, which as noted in Chapter 2 are presently separated in two distinct cells (Smith and Jacobs, 2005). An alternative scenario for the retention of sand and silt now lost beyond the shelf break would involve diverting the main flow of the Mississippi River toward the west of its present main channel somewhere between New Orleans and Head of Passes. An intermediate- and long-term consequence of this action would be the abandonment of the active Birdsfoot Delta by the Mississippi River. A clear benefit would be the nourishment of eroding coastal reaches to the west. Although this alternative has been widely acknowledged as possible, its feasibility has, for various reasons, not been seriously considered by USACE. Therefore, unlike the Third Delta scenario, it is not yet possible to assess the potential advantages and disadvantages of Birdsfoot Delta abandonment. Obviously, implementation of such a strategy would have to be accompanied by the creation of a deep navigation access channel somewhere downstream of New Orleans but upstream of Head of Passes. Although the size of the area it would impact would make it controversial, such a diversion represents the type of project that deserves greater consideration as restoration efforts move forward. ENHANCING THE FEASIBILITY OF THE OVERALL APPROACH An undertaking as complex as restoring and protecting coastal Louisiana presents several challenges to the understanding of many natural and anthropogenic processes, as well as fundamental engineering design. Thus, a robust program is needed to identify key knowledge gaps as they are identified and to implement research and demonstration projects to

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana provide the basis for effective problem solving. Analysis of the LCA Study suggests that major knowledge gaps exist that may require acknowledgment and addressing early in any implementation effort. Uncertainties associated with relative sea level change, bathymetric and topographic data quality, adequacy of resources, and distribution methods suggest that greater emphasis may have to be placed on environmental monitoring to provide adequate baseline information. In addition, process-based models for prediction of land building, which link socioeconomic outcomes to biophysical processes, will likely also be needed. As pointed out in Chapter 5, models often play a key role in project selection and adaptive management. A modeling effort as complex as the one needed for restoring the Louisiana coast requires a great deal of observational data and modeling coordination. In addition, the best modeling is done when the process is open to collaborating scientists (physical, biological, and social) nationally and from around the world. A new modeling program, involving multiple state and federal agencies and academic institutions, is needed to draw together experience creating an open scientific forum. This forum will generate the confidence of scientists, engineers, and the public. The cost of developing such a program will be insignificant compared to the implementation costs, the scale and complexity, and the long-term nature of Louisiana’s restoration process. Guidance developed through this program can be expected to reduce the risk of failures, anticipate future problems (physical, biological, social, political, and economic), and reduce the overall costs as experience and data result in improved projections. The coastal Louisiana restoration endeavor would benefit greatly from a coordinated effort that would result from the establishment of a more robust informatics and modeling effort focusing on the lower Mississippi River. This effort should have the following characteristics: Leadership by a prominent academic or research scientist and a consortium of universities within the state, state and federal agencies, and federal research facilities Acceptance of new technologies and facilitation of open-access, community-wide scientific research on a national and global scale New technologies and open research with the national and global scientific community A scientific steering committee of internationally recognized modelers and scientists Facilitation of capacity building to train and educate (in disciplinary and interdisciplinary fashion) the next generation of engineers and scientists who will inherit the management of the lower Mississippi River

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana University campus location but with resident representatives of all agencies involved in the restoration and management of the lower Mississippi River Cyber-infrastructure for communication, modeling (physical, biological, social, and economic), and data management for the restoration process Cyber-infrastructure that includes (1) the data warehouse, data archiving, computational core capable of running large models, and communication facilities for collaborating with national and local researchers and managers and (2) a web portal for the general public to track current conditions and various alternatives being investigated The S&T Program envisioned in the LCA Study is an innovative and essential element that provides a process for planning and assimilating monitoring results and developing adaptive management strategies. In addition, the S&T Program is an appropriate administrative home for model development and maintenance. The proposed S&T Program represents a very positive step in the development of a coordinated approach for an adequate knowledge base of how coastal Louisiana may respond to various restoration efforts or evolve in the absence of some of those efforts. The S&T Program requires a more explicit statement of program responsibilities and means for setting priorities; it must be integrated more effectively into the central management structure through the adaptive management process and include better representation of social sciences and ecological processes. It is unreasonable to expect any region to have all the necessary experience and human resources to address most effectively the challenges of the magnitude represented by land loss in coastal Louisiana. Just as the funding of the LCA Study and its extensions includes a combination of state and federal resources, the scientific and other elements of the LCA Study should draw on the best state, national, and international talents available. Therefore, the LCA Study should direct efforts toward capacity building that enables the program to address its stated objectives by drawing on the widest possible pool of national and international technical expertise. The AEAM process for the LCA Study lays out a mechanism to integrate emerging technical information into the management processes, in addition to the use of sound science in understanding the efficacy of past actions in order to modify or change future actions. AEAM efforts, however, appear to be marginalized within the overall management structure. The full benefit of taking an adaptive management approach to complex projects, such as proposed in the LCA Study, will be realized only if it represents a core theme of the overall project management strategy. Steps

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana should be taken to strengthen the AEAM process throughout the management structure. CWPPRA, Coast 2050, and efforts to develop Louisiana Coastal Area, LA—Ecosystem Restoration: Comprehensive Coastwide Ecosystem Restoration Study (draft LCA Comprehensive Study) placed greater emphasis on stakeholder involvement than is evident in the LCA Study. Stakeholder participation (including, at a minimum, representation from local government, industry, key organizations, and citizens at large) should be accounted for in the management structure of the Louisiana coastal area program. The LCA Study presents sufficient information about the importance of some components of the natural and built environment in coastal Louisiana (e.g., system of deep water ports, oil and gas receiving and transmission facilities, complex and extensive urban landscape, robust commercial fishery) to suggest that substantial economic interests are at stake in coastal Louisiana and that these interests have national significance. The immediate impacts of Katrina underscore the importance of New Orleans and adjacent areas of the Gulf Coast to the national economy. Establishing the true, national economic significance of efforts to restore coastal wetlands in Louisiana as proposed in the LCA Study, however, must go beyond simply identifying and characterizing these components and should include an analysis of how specific restoration efforts will preserve or enhance their value (i.e., some restoration efforts may have little influence on the vulnerabilities of specific components of the natural and built environment in coastal Louisiana) and determine how the national economy would respond to their loss or degradation (e.g., what is the capacity for similar components in other regions to compensate for their loss and on what time scales?). If greater emphasis is to be placed on the national economic benefits of restoring and protecting coastal Louisiana, future planning efforts should incorporate meaningful measures of the economic benefits of these projects to the nation consistent with procedures normally employed to determine the value of a project or a suite of projects proposed as National Economic Development. Conversely, the significance of the coastal Louisiana wetlands to the nation in terms of both their inherent uniqueness and the ecosystem services they provide is more thoroughly documented in the LCA Study, its predecessor reports, and the scientific literature. Although efforts to restore and protect Louisiana’s wetlands will likely provide some unknown but potentially significant protection against coastal storms and hurricanes, those efforts should not be evaluated primarily on their significance for National Economic Development. It would appear that a more effective means to provide sediment to restore areas to the southwest and southeast of New Orleans would be to

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana develop a large-scale diversion located closer to the Head of Passes such that most of the river water is diverted, and the river below this diversion point would essentially become a “slack water” channel but would still be maintained for navigation. This would allow most of the suspended sediments to be carried eastward to shallower water areas where they could nourish the wetlands rather than being discharged into deep water and substantially lost to the system. Finer-grained sediments could be directed into wetlands on either side of the channel. Most of the coarser bedload would either be deposited in the channel or eventually be carried out by the flows to the shallower area to be transported to the west by the waves and currents to nourish the existing barrier islands and to form new barrier islands. The slack water navigation channel would require more dredging downstream of the diversion location than is presently necessary, but this is the price if a majority of the sediments are to be captured, an essential requirement to the optimal restoration of wetlands and barrier islands. Regardless of the diversion design adopted, if the present navigation channel is to be maintained and the coarse fraction captured, substantial dredging will be required. Some consideration should be given to an alternative or companion to the planned Third Delta, such as a larger-scale diversion closer to the Gulf of Mexico that would capture and deliver greater quantities of coarse and fine sediments for wetland and barrier island development and maintenance. The majority of the projects proposed in the LCA Study are based on commonly accepted, sound scientific and engineering analyses. However, it is not clear that, in the aggregate, if these projects represent a scientifically sound strategy for addressing coastal erosion at the scale of the affected area. Thus, at foreseeable rates of land loss, the level of effort described by the LCA Study will likely decrease land loss only in areas adjacent to the specific proposed projects. As found in numerous USACE policy statements and recommended in past National Research Council reports, planning and implementation of water resources projects (including those involving environmental restoration) should be undertaken within the context of the larger system (National Research Council, 2004a). This philosophy reflects the recognition that a group of projects within a given watershed or coastal system may interact at a variety of scales to produce beneficial or deleterious effects. Cost and benefit analyses discussed in the LCA Study and in supporting documents reflect an effort to identify least-cost alternatives but do not appear to reflect a system-wide effort to maximize beneficial synergies among various projects with regard to habitat loss. The selection of any suite of individual projects in future efforts to restore coastal Louisiana should include a clear effort to maximize the beneficial, synergistic effects of individual projects to minimize or reverse future land loss. For example, in addition to the

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Drawing Louisiana’s New Map: Addressing Land Loss in Coastal Louisiana series of relatively modest diversions and barrier island restoration efforts discussed in the LCA Study, more robust efforts may be contemplated. Two large projects not in the LCA Study, the Third Delta and abandoning the Birdsfoot Delta, may deserve greater consideration. Chapter 7 notes the gaps in knowledge that impact project choices and implementation strategies. Finally, coastal Louisiana lies at the nexus between the Gulf of Mexico and the nation’s largest watershed (the Mississippi River Basin). The current loss of wetlands and other environmental problems on and along the delta have many causes, but several of them are the result of the current management of the Mississippi River Basin. Taking a system-wide approach to determining contributing causes and potential approaches to reducing their adverse impact on the environmental quality of coastal Louisiana should include consideration of (1) changes in the sediment flux from the basin resulting from past dam construction on the tributaries to the Mississippi River, (2) the effects of armoring the river banks, (3) the loss of wetlands in the upper part of the watershed, and (4) the impacts of runoff from agricultural operations and other activities in the Mississippi River Basin.

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