1
Introduction

The Everglades of south Florida once encompassed about 4,600 mi2 (three million acres) of slow-moving water and associated biota that stretched from the Lake Okeechobee drainage basin in the north to Florida Bay in the south (Figure 1-1) (Davis et al., 1994). The drainage basin for Lake Okeechobee extends north to a series of lakes near Orlando, and thus the Everglades drainage basin covers an area of approximately 10,890 mi2 (seven million acres) (Light and Dineen, 1994; Ogden et al., 2003). Today, human settlements and associated flood-control structures have reduced the Everglades itself to about half its original size (Davis et al., 1994). Everglades National Park includes areas such as Florida Bay and coastal mangroves that are not usually considered part of the “true Everglades” (Davis et al., 1994).

To remedy the degradation of the Everglades, the Comprehensive Everglades Restoration Plan (the CERP, referred to in this report as “the Restoration Plan”; USACE and SFWMD, 1999), was unveiled in 1999 with the goal of restoring hydrologic characteristics as close as possible to their original conditions in what remains of the natural ecosystem. Also in 1999 the National Academies established the Committee on the Restoration of the Greater Everglades Ecosystem (CROGEE) in response to a request from the Department of the Interior on behalf of the South Florida Ecosystem Restoration Task Force (SFERTF1). The committee’s task (see Box ES-1) was to provide the Task Force with scientific overview and technical assessment of the restoration activities and plans, while also providing focused advice on technical topics of importance to the restoration efforts. This report does both. It evaluates the many storage options considered by Everglades scientists, engineers, and planners, including some that are not in the Restoration Plan. Storage is a critical aspect of the functioning of the Everglades ecosystem and of the Restoration Plan, but other critical factors, such as timing of land acquisition, intermediate states of restoration, and evaluating tradeoffs among competing goals or ecosystem components, provide the context for choosing and implementing storage options. Therefore, this report considers them as well.

1  

The SFERTF was established by the Water Resources Development Act of 1996, which also specified its composition. Its 14 members include the secretaries of Interior (chair), Commerce, Army, Agriculture, and Transportation; the Attorney General, and the Administrator of the Environmental Protection Agency, or their designees. One member each is appointed by the Secretary of the Interior from the Seminole Tribe of Florida and the Miccosukee Tribe of Indians of Florida. The Secretary of the Interior also appoints, based on recommendations of the Governor of Florida, two representatives of the State of Florida, one representative of the South Florida Water Management District, and two representatives of local Florida governments. Current membership and information about the SFERTF are available at http://www.sfrestore.org/.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 13
Re-Engineering Water Storage in the Everglades: Risks and Opportunities 1 Introduction The Everglades of south Florida once encompassed about 4,600 mi2 (three million acres) of slow-moving water and associated biota that stretched from the Lake Okeechobee drainage basin in the north to Florida Bay in the south (Figure 1-1) (Davis et al., 1994). The drainage basin for Lake Okeechobee extends north to a series of lakes near Orlando, and thus the Everglades drainage basin covers an area of approximately 10,890 mi2 (seven million acres) (Light and Dineen, 1994; Ogden et al., 2003). Today, human settlements and associated flood-control structures have reduced the Everglades itself to about half its original size (Davis et al., 1994). Everglades National Park includes areas such as Florida Bay and coastal mangroves that are not usually considered part of the “true Everglades” (Davis et al., 1994). To remedy the degradation of the Everglades, the Comprehensive Everglades Restoration Plan (the CERP, referred to in this report as “the Restoration Plan”; USACE and SFWMD, 1999), was unveiled in 1999 with the goal of restoring hydrologic characteristics as close as possible to their original conditions in what remains of the natural ecosystem. Also in 1999 the National Academies established the Committee on the Restoration of the Greater Everglades Ecosystem (CROGEE) in response to a request from the Department of the Interior on behalf of the South Florida Ecosystem Restoration Task Force (SFERTF1). The committee’s task (see Box ES-1) was to provide the Task Force with scientific overview and technical assessment of the restoration activities and plans, while also providing focused advice on technical topics of importance to the restoration efforts. This report does both. It evaluates the many storage options considered by Everglades scientists, engineers, and planners, including some that are not in the Restoration Plan. Storage is a critical aspect of the functioning of the Everglades ecosystem and of the Restoration Plan, but other critical factors, such as timing of land acquisition, intermediate states of restoration, and evaluating tradeoffs among competing goals or ecosystem components, provide the context for choosing and implementing storage options. Therefore, this report considers them as well. 1   The SFERTF was established by the Water Resources Development Act of 1996, which also specified its composition. Its 14 members include the secretaries of Interior (chair), Commerce, Army, Agriculture, and Transportation; the Attorney General, and the Administrator of the Environmental Protection Agency, or their designees. One member each is appointed by the Secretary of the Interior from the Seminole Tribe of Florida and the Miccosukee Tribe of Indians of Florida. The Secretary of the Interior also appoints, based on recommendations of the Governor of Florida, two representatives of the State of Florida, one representative of the South Florida Water Management District, and two representatives of local Florida governments. Current membership and information about the SFERTF are available at http://www.sfrestore.org/.

OCR for page 13
Re-Engineering Water Storage in the Everglades: Risks and Opportunities In its several previous reports, the NRC has provided scientific and technical advice about aquifer storage and recovery (NRC, 2001a), regional issues in aquifer storage and recovery (NRC, 2002a), research programs in Florida Bay (NRC, 2002b), the planning and organization of science (NRC, 2003a), adaptive monitoring and assessment (NRC, 2003b), and the importance of water flow in shaping the Everglades landscapes (NRC, 2003c). THE EVERGLADES ECOSYSTEM Florida’s Everglades, often referred to as the splendid River of Grass, is a rich and unique ecosystem. Shaped by the flow of slow-moving water, its flourishing landscape of sawgrass plains, ridges, sloughs and tree islands is a home to alligators, many kinds of wading birds, and other plant and animal life, some of which is found in few or no other locations. By the mid-twentieth century, a vast network of canals and levees, built to drain water for flood control, water supply, agriculture, and urban development, had profoundly altered the region’s wetlands and reduced the Everglades to half its original size. Today, the wading bird population has sharply declined, and 70 plant and animal species in South Florida are threatened or endangered. Throughout the past century, the Everglades has epitomized the American conflict between economic development and environmental conservation. In recent years, the governmental agencies and the people in the region have embraced the challenge of protecting and restoring native species and ecosystems while still meeting human needs for space and natural resources. Restoration of the Everglades is a daunting task. It is extremely complicated for several reasons. First, the Greater Everglades ecosystem is huge, stretching from the Kissimmee River drainage basin to Florida Bay and adjoining coral reefs (see Figure 1-1). Second, the Restoration Plan must attempt to balance the interests of many stakeholders. Third, restoration goals must consider and resolve the complex and often competing needs of different plant and animal species. Fourth, the plan must be robust in the face of unknown factors such as future climate change and urban population growth. Finally, and perhaps most important, there are competing visions of what will constitute successful restoration. Since 1993, a coalition of local, state, and federal agencies, as well as non-government organizations, local tribes, and citizens, has been working to reverse the damage to the Everglades. The effort is led by two organizations that have considerable expertise regarding the water resources of south Florida—the U.S. Army Corps of Engineers (USACE), which built most of the canals and levees in the Everglades, and the South Florida Water Management District, which has primary responsibility for operating and maintaining this complicated water collection and distribution system. In 1999, the USACE issued its blueprint for the restoration effort, the Comprehensive Everglades Restoration Plan (the Restoration Plan). The plan, which was approved by Congress in the Water Resources Development Act of 2000, seeks to “get the water right”—that is, to deliver the right amount and quality of water to the right places at the right times. The plan proposes more than 50 major projects to be constructed over an estimated 36 years at a cost of approximately $7.8 billion.2 2   All costs, including construction, real-state, and operations and maintenance costs, are in 1999 dollars. See Appendix A for list and schedule of projects.

OCR for page 13
Re-Engineering Water Storage in the Everglades: Risks and Opportunities FIGURE 1-1. Much bigger than just Everglades National Park, the Greater Everglades Ecosystem (or south Florida ecosystem) extends south from the Kissimmee River watershed to Lake Okeechobee, through the remaining Everglades, and on to the waters of Florida Bay and the coral reefs. SOURCE: Information on locations of existing and proposed storage components from USACE and SFWMD. Since the publication of the Restoration Plan in 1999, the USACE, after public comment, established programmatic regulations to set the procedural framework for implementing the plan. The key provisions include a process for establishing interim goals to provide hydrologic, water-quality, and ecological targets against which to measure restoration progress; the establishment of an interagency group called “RECOVER” (Restoration, Coordination and Verification) that assesses the individual projects to ensure that the system-wide goals and purposes of the Restoration Plan are achieved; the establishment of an adaptive management program to assess whether the responses of the natural system to restoration plan activities match expectations, and to recommend modifications to the plan based on new information; and

OCR for page 13
Re-Engineering Water Storage in the Everglades: Risks and Opportunities a process for establishing an independent scientific review [committee of the National Research Council] of the National Academy of Sciences to review progress in meeting the restoration goals. (http://www.evergladesplan.org/pm/pm_docs/prog_regulations/110403_prog_regs_faq_final.pdf) The Restoration Plan continues to be modified. For example, an aquifer storage and recovery (ASR) regional study has been added to address issues raised by this committee (2001a) and others, including potential effects of the ASR program on communities, industry, other groundwater users, and the environment (http://www.evergladesplan.org/pm/projects/proj_44_asr_regional.cfm). On a broader scale, the hydrologic models are in the process of being updated and recalibrated with 1996-2000 data, improved topography, and other information through a process known as the “Initial CERP update” (http://www.evergladesplan.org/pm/recover/icu.cfm). Generally speaking, however, the simulations, analysis, and budgets done for the Restoration Plan still form the most consistent and internally comparable data set available, and accordingly this report makes broad use of those data. The Restoration Plan is divided into components—conceptual parts of the plan, like decompartmentalization—and individual projects. The proposed schedule for construction of the projects of the Restoration Plan is called the Master Implementation Sequencing Plan (MISP) and it is described at the Everglades Restoration web site at http://www.evergladesplan.org/pm/misp.cfm. The MISP includes the sequencing and scheduling of all of the projects of the Restoration Plan, including pilot projects and operational elements. The latest version of the MISP no longer gives specific dates for completion of the projects; instead, the sequence is divided into seven 5-year bands during each of which a number of projects are scheduled for completion. Appendix A of this report is a table that compares the initial schedule of projects with the current MISP. MAJOR STORAGE AND WATER-CONSERVATION COMPONENTS IN THE RESTORATION PLAN Major components of the restoration include operational modifications, modifications to existing structures and canals, decompartmentalization of the Water Conservation Areas, stormwater treatment areas, water reuse, expanded storage capacity and seepage management. Water reuse, storage and seepage management are introduced in the following section and described in detail in Chapter 3. In the current water management system, the major storage components are Lake Okeechobee and the Water Conservation Areas. Together these provide over four million acre-feet of storage. Several additional components either are included in the Restoration Plan or could contribute to total storage. Kissimmee surface reservoirs include an above-ground reservoir of approximately 200,000 acre-feet of storage and a 2,500-acre stormwater treatment area (STA). The Everglades Agricultural Area (EAA) and vicinity. The area covered by the EAA stored considerable amounts of water in the natural Everglades system, and although its character has changed, it could provide for substantial surface storage capacity in the future. Two projects that are included in the Restoration Plan will create above-ground reservoirs within the EAA (http://www.evergladesplan.org/pm/projects/proj_08_eaa_phase_1.cfm

OCR for page 13
Re-Engineering Water Storage in the Everglades: Risks and Opportunities and http://www.evergladesplan.org/pm/projects/proj_09_eaa_phase_2.cfm). Together they will have a capacity of about 360,000 acre-feet. Aquifer Storage and Recovery (ASR). This is the largest planned storage component in the Restoration Plan, anticipated to accommodate an average of more than 500,000 ac-ft of water added to storage each year, and a capacity for accumulated recoverable storage of more than four million acre-feet (based on the cumulative volume in storage at the end of the D13R3 31-year simulation after the assumed 30 percent injection loss. Lake Belt Storage. This component is planned to consist of in-ground reservoirs developed from converted limestone quarries. Two reservoirs are planned in Miami-Dade County, both up to 80 feet deep with a combined storage capacity of nearly 280,000 acre-feet. Seepage Management. Although not a storage component, this water-conservation component aims to reduce water flow across levees, reservoir walls and other containment structures, and it would have the same net effect as a storage component. It is essential to the success of some storage components, particularly Lake Belt storage. Water Reuse and Conservation. Advanced wastewater treatment technology will be used to reclaim urban wastewater from Miami-Dade Counties to supplement water in natural areas such as the West Palm Beach’s Catchment Area, Biscayne National Park, and the Bird Drive basin. A number of smaller, conventional reservoirs and stormwater treatment areas in the Upper East Coast. These are included in the Indian River Lagoon–South component of the Restoration Plan and will provide an addition of approximately 170,000 acre-feet of storage. WHY IS STORAGE IMPORTANT? A basic premise of the Restoration Plan is that if the water is “right,” then the ecosystem will become “right” as well. That implies that the water is not “right” today, and indeed the amount of water in the Greater Everglades Ecosystem, and its spatial and temporal distributions, are very different from conditions in the natural system. (The history of human efforts to control water in south Florida and the resulting changes in the system are well reviewed by Light and Dineen [1994], the Science Sub-Group [1993], and on the Restoration Plan’s web site.) More than half of the original Everglades wetlands have been converted to human use, thus reducing water storage and flux that buffered extremes of flood and drought. As things now stand in the Everglades and in the surrounding human settlements, there is more water at some times and places than occurred under pre-European settlement conditions, and at other times and other places water levels and/or flows are much lower than occurred naturally. In particular, drought conditions are longer, more severe, and cover wider areas in the current system than under presettlement conditions, and efforts to mitigate these droughts involve storage of water in “Conservation Areas” northeast of Everglades National Park that previously had (on average) lower water levels. In addition, some restoration goals compete with the ecological goals for the use of stored water. For example, the human demand for water in south Florida is much greater than it 3   Simulation D13R uses the same projected land use and water demands as in the 2050 Base simulation, but also assumes a completed Restoration Plan (and other) projects. It is known as alternative D13R based on its sequence in a series of simulations.

OCR for page 13
Re-Engineering Water Storage in the Everglades: Risks and Opportunities was 100 years ago, and the need for flood control in developed areas does not necessarily enhance the availability of water for ecological restoration. As a result, the Restoration Plan includes large amounts of new storage as a mechanism for supplying the water that is needed for both people and the ecosystem and changes in the delivery system that enable water to be supplied at the times and in the places where it is currently in shortest supply. Below we describe the general changes that have occurred to the hydrologic system of the Everglades and their effects on water supply and the need for storage. The description is based on many papers in Davis and Ogden (1994) and on hydrologic principles. The natural system included the Kissimmee River drainage north of Lake Okeechobee, the lake, and the Everglades system south of the lake. Before drainage and other human modifications to the landscape that began in the late 1800s, seasonal variations in the amount and distribution of water in the system must have been strongly damped by the combined effects of storage in wetlands and Lake Okeechobee in the northern part of the system, and by relatively slow flows through the meandering channels of the Kissimmee River. Thus, despite strong daily and seasonal variations in rainfall and potential evapotranspiration, the system would not have been as prone as it is today to rapid water-level changes that cause flooding. Lake Okeechobee would have been free to contract or expand its large surface area into surrounding areas containing extensive wetlands and pond-apple forests. This would have provided additional buffering against droughts as water eventually flowed from the sawgrass plain to the south of the lake. Topographic variations within the ridge-and-slough landscape beyond the sawgrass plain must have provided further damping. Damping in the north must have provided a buffer to the southern portion of the system against the effects of seasonal and multiyear dry spells, which readily lead to desiccation under current conditions. The natural system in the south would still have experienced seasonal and shorter-term variations in water flows and levels, which probably were important to the development and functioning of the ecosystem. Those fluctuations would have resulted mainly from local rainfall patterns and would have been smaller and more gradual than would be expected without upstream damping. Initial modifications to the system were made between 1881 and 1894. These included Hamilton Disston’s projects to make “channel improvements” (i.e., dredging and straightening) in the Kissimmee River, to construct new channels in the headwaters of the Kissimmee River basin, and to connect Lake Okeechobee to the Caloosahatchee River, providing an outlet from the lake to the Gulf of Mexico. These projects drained areas north of Lake Okeechobee and most likely increased peak flows in the Kissimmee River. These increases in peak flow caused rapid expansion of the lake area. The diversion of water from the lake to the Gulf through the Caloosahatchee River reduced the amount of water stored within the Everglades ecosystem, reducing water available to maintain flows to the south during dry periods. A second major drainage effort, spanning the period 1905-1928, focused on the area south of Lake Okeechobee that is now the Everglades Agricultural Area. Drainage canals extending through this area to the Lower East Coast lowered water levels to allow for farming. Construction of the St. Lucie Canal, connecting Lake Okeechobee to the Atlantic, and further dredging of the Caloosahatchee River increased the efficiency of rainfall runoff diversion to further reduce the potential for flooding south of the lake. The result of these diversions was further reduction in the amount of water stored within the Everglades Ecosystem and the potential for enhanced desiccation of wetlands in the southern part of the system during droughts. Despite the flood control provided by diversions from Lake Okeechobee to the St. Lucie Canal and the Caloosahatchee River, flooding of the Everglades Agricultural Area (EAA) was

OCR for page 13
Re-Engineering Water Storage in the Everglades: Risks and Opportunities still a problem, particularly during severe hurricanes in 1926 and 1928 when winds and torrential rains caused overflow from Lake Okeechobee. Construction of the Herbert Hoover Dike between 1932 and 1938 was undertaken to provide additional flood control. On its completion, the dike dramatically altered the functioning of Lake Okeechobee. It was no longer free to expand or contract its boundaries within the historical littoral zone and water levels were now managed by a number of control structures. While flooding potential was reduced with completion of the dike, another problem became apparent during successive dry years between 1931 and 1945. During this drought, the lowered water levels created by agricultural drains, coupled with the reduced storage resulting from diversion of runoff to the Gulf and Atlantic, led to regional lowering of the water table, resulting in desiccation of many of the remaining wetland areas and a threat of saltwater intrusion into the coastal aquifer. This highlighted the need to develop additional storage capacity to provide water to wetlands and the canals during dry seasons and extended droughts. This capacity eventually was developed in the Water Conservation Areas (WCAs), south of the EAA, in a region that was historically dominated by ridges, sloughs, and tree islands. Storage of water in the WCAs, which increased water levels in parts of them, altered the vegetation community and landscape patterns. The drought broke in 1947, during which year 100 inches of rain fell and severe flooding covered 90 percent of southeastern Florida. At this point it was clear that a water management strategy was required to address flooding and drought hazards, as well as water supply and environmental issues. The Central and Southern Florida (C&SF) project, designed by the USACE and authorized in the federal Flood Control Act of June 30, 1948, was intended to meet these needs by providing flood control, water level control, water conservation, prevention of saltwater intrusion, and preservation of fish and wildlife. While some new storage was created in the WCAs, additional flood control measures have continued to shunt the majority of runoff water out of the terrestrial system and into the Gulf and the Atlantic via the Caloosahatchee River and St. Lucie Canal. To avoid flooding private lands that lie west of the Miami ridge in the southern Everglades, much of the water in this portion of the Everglades is diverted from east to west. The result of the many changes in the Everglades hydrologic system made in the twentieth century is that parts of the Everglades are water-starved at times, other parts are submerged, and the natural timing and amplitudes of high-water and drying events have been severely disrupted. Large pulses of fresh water diverted to the coasts also have had detrimental effects on estuaries. This, then, describes how the water is “wrong” and why a major goal of the Restoration Plan is “to get the water right.” All the options for “getting the water right” envisioned by the Restoration Plan—indeed, any option envisioned by anyone—will require additional, and at least short-term, storage, as well as alterations in how water is directed through the system. Decompartmentalization—the dismantling of some water control structures, such as dams and levees, to convert the Everglades from the hydrologically-compartmentalized system that exists today—is critical to restoring sheet flow that characterized the natural system; other components will enable the timing and direction of sheet flow to be restored. Simply diverting the runoff pulses that currently are discharged to the Gulf and Atlantic and routing them into the southern Everglades might restore the historical volumes of flow on an annual basis. However, because the damping that once was provided by upstream features—in the Kissimmee River basin, Lake Okeechobee, the sawgrass plain, and northern ridge-and-slough landscapes—has been removed from the system, the timing

OCR for page 13
Re-Engineering Water Storage in the Everglades: Risks and Opportunities and magnitudes of water level fluctuations would be very different from those in the historical system and these could have detrimental effects on the ecosystem. Furthermore, the additional demand for water in south Florida by the growing human population almost surely will require additional and possibly longer-term storage. Water demand in south Florida is projected to grow from 3.5 billion gallons per day (BGD) in 1995 to nearly 4.5 BGD in 2020 due to an expected 43 percent increase in human population during the period (Kranzer, 2003). Because there is less water in the system and greater demand for water than before, and because of the degree to which the system has been engineered, moving any part of the water to a place where it is needed or removing any structure that impedes its flow implies the likelihood of water shortages elsewhere, increased risk of flooding, or both, unless additional storage is available. For example, if the levees and canals in the WCAs were breached to decompartmentalize that portion of the system, with no other change, the adjacent areas would once again be short of water in the dry season, as they had been before construction of the WCAs, and the lack of buffering resulting from the channelization of the system would make the same areas prone to flooding during wet periods. This is why the Restoration Plan has such a large component devoted to providing additional storage. It is not clear exactly what ecological conditions will accompany hydrologic change, but there is merit in concluding that more natural hydrologic conditions will lead to improved ecosystem functioning. Thus attempting to “get the water right” (or at least better) is a reasonable approach to restoration. STORAGE, FLOW, AND RESTORATION OF THE EVERGLADES ECOSYSTEM In executing its task of providing advice about the technical and scientific aspects of restoration and planning (Box ES-1), the committee was mindful of previously published approaches for restoring aquatic ecosystems (e.g., NRC, 1992, 2001b; Science Sub-Group, 1993). The committee judges that the Restoration Plan is proceeding in accordance with many such principles, but not in all aspects. In particular, the committee has concern that too little weight has been given to the following principles of sustainable restoration. Prevent additional habitat loss. The first priority in a restoration project is to secure it against the risk of additional damage. For most projects this means protecting from additional damage the remaining habitat and areas that potentially could provide usable habitat. In particular, protecting against irreversible habitat loss should be the first priority of a restoration program. This principle implies that heavy emphasis should be placed on purchasing land intended to be part of the restored system or obtaining conservation easements on such lands as soon as possible. Provide ecological benefits as early as possible. Restoration projects often have other goals in addition to ecological restoration, and compromises often must be made with other goals (e.g., flood control) or constraints (e.g., budget or the need to compensate for previously degraded aspects of the environment). To the extent that the project can achieve ecological goals early, the outcome is likely to be improved.

OCR for page 13
Re-Engineering Water Storage in the Everglades: Risks and Opportunities These principles are discussed in detail in Chapter 3 in the context of sequencing components of the Restoration Plan. Two other issues are important in addition to those mentioned above. The first—a difficulty acknowledged by the Restoration Plan—is that ecological outcomes are quite uncertain, and some outcomes could be seen as unacceptable. The committee has taken seriously the advice of the 1990s Science Sub-Group of the South Florida Management and Coordination Working Group (Science Sub-Group, 1993) to consider the whole system and to take a regional approach in this regard, and consequently this report examines problems of diminished areal extent of the restored ecosystem, endangered species, invasive exotic plants, and water quality to assess the likelihood that uncertainty can be reduced and its consequences managed, and that unacceptable outcomes can be avoided. Finally, the report addresses the expectation that adaptive management will provide an early opportunity to repair possible shortfalls in the Restoration Plan. An example of such a shortfall might be the occurrence of a real estate market boom that prevents the planned footprint from being acquired. Because the restored system will be highly engineered, it also will be vulnerable to failure of the engineered systems to function as intended or to unexpected changes in conditions considered external to system design and operation. Examples of the latter are climate change, sea level rise, extraordinary population growth, large-scale land-use change, elevated energy costs, and reduction or elimination of crop subsidies. Adaptive management can lead to the improvement of design details and operating practices within the overall design concept, but it cannot easily address violations of the contextual and efficacy assumptions made in the engineering design. The possibility of unexpected shifts in external drivers should be addressed through concerted attention to contingency planning, including reconsideration of alternatives already discarded such as those related to Lake Okeechobee and the EAA. This planning should be directed at major decision points that have already been passed or that will arrive soon, rather than at fine adjustments of the extant Restoration Plan. Contingency planning should be allowed to lead to re-design of the conceptual plan if that becomes necessary, possibly more than once. The opportunity provided by adaptive management may also yield an early warning of unexpected outcomes and hence the need for implementation of contingency plans. REPORT ORGANIZATION Chapter 2 describes each of the major storage components of the plan, emphasizing sequencing and water-quality issues and the potential to rely on natural as opposed to engineered processes. Chapter 3 discusses cross-cutting issues that the committee considered in evaluating the science underlying the implementation of the plan, especially with respect to storage. They include the ordering of the Restoration Plan’s components in space and time, including criteria and uncertainties associated with that sequencing; ecological uncertainties; contingency planning; adaptive management; and the relative merits of using natural versus highly engineered processes in the restoration. Chapter 4 discusses the potential need to reconsider the full range of available storage options as an adaptive management strategy during the course of implementation of the Restoration Plan. Chapter 5 suggests a quantitative framework that could be used to evaluate restoration progress and alternatives, including re-evaluation and refinement of restoration goals. Chapter 6 summarizes the committee’s major findings and recommendations.