The South Florida ecosystem encompasses a broad range of natural, urban, and agricultural areas surrounding the remnant Everglades. Before human intervention, freshwater in the ecosystem flowed south from Lake Okeechobee to Florida Bay in a broad, slow-moving sheet, creating the mix of wetlands that form the ecosystem. These wetlands, interspersed with dry areas, created habitat for abundant wildlife, fish, and birds. The South Florida ecosystem is also home to 6.5 million people and supports a large agricultural, tourist, and industrial economy. To facilitate development in the area, in 1948, Congress authorized the U.S. Army Corps of Engineers to build the Central and Southern Florida Project—a system of more than 1,700 miles of canals and levees and 16 major pump stations—to prevent flooding and intrusion of saltwater into freshwater aquifers on the Atlantic coast. The engineering changes that resulted from the project, and subsequent agricultural, industrial, and urban development, reduced the Everglades ecosystem to about half its original size, causing detrimental effects to fish, bird, and other wildlife habitats and to water quality. Figure 1 shows the historic and current flows of the Everglades ecosystem as well as the proposed restored flow. Efforts to reverse the detrimental effects of development on the ecosystem led to the formal establishment of the Task Force, authorized by the Water Resources Development Act (WRDA) of 1996. The Task Force, charged with coordinating and facilitating the restoration of the ecosystem, established three overall goals to: Get the water right: restore more natural hydrologic functions to the ecosystem while providing adequate water supplies and flood control. The goal is to deliver the right amount of water, of the right quality, to the right places at the right times. Restore, protect, and preserve the natural system: restore lost and altered habitats and change current land use patterns. Growth and development have displaced and disconnected natural habitats and the spread of invasive species has caused sharp declines in native plant and animal populations. Foster the compatibility of the built and natural systems: find development patterns that are complementary to ecosystem restoration and to a restored natural system. Figure 2 shows the relationship of the agencies participating in restoration, the Task Force, and the three restoration goals. Because of the complexity of the ecosystem and efforts underway to restore it, and the urgency to begin the long-term ecosystem restoration effort, not all of the scientific information that is needed is available to make restoration decisions. As a result, scientists will continually need to develop information and restoration decision makers will continually need to review it. According to the Task Force, scientists participating in restoration are expected to identify and determine what information is needed to fill gaps in scientific knowledge critical to meeting restoration objectives and provide managers with updated scientific information for critical restoration decisions. Generally, decisions about restoration projects and plans have been—and will continue to be—made by the agencies participating in the restoration initiative. To provide agency managers and the Task Force with updated scientific information, the Task Force has endorsed adaptive management, a process that requires key tools, such as models, continued research, and monitoring plans. Federal and state agencies spent $576 million from fiscal years 1993 through 2002 to conduct mission-related scientific research, monitoring, and assessment in support of the restoration of the South Florida ecosystem. Eight federal departments and agencies spent $273 million for scientific activities, with the Department of the Interior spending $139 million (about half) of the funds. The level of federal expenditures, which increased by over 50 percent in 1997, has since remained relatively constant. The South Florida Water Management District—the state agency most heavily involved in scientific activities for restoration—spent $303 million from 1993 through 2002. The District’s expenditures have increased steadily since 1993, with significant increases in 2000 and 2002. Figure 3 shows the total federal and state expenditures for scientific activities related to restoration over the last decade. Eight federal agencies are involved in scientific activities for the restoration: the Department of the Interior’s U.S. Geological Survey, National Park Service, Fish and Wildlife Service, and Bureau of Indian Affairs; the Department of Commerce’s National Oceanic and Atmospheric Administration; the Department of Agriculture’s Agricultural Research Service; the U.S. Army Corps of Engineers; and the Environmental Protection Agency. Within the Department of the Interior, four agencies spent $139 million on scientific activities. The U.S. Geological Survey spent over half of the Interior funding, or $77 million, primarily on its Placed-Based Studies Program, which provides information, data, and models to other agencies to support decisions for ecosystem restoration and management. The National Park Service spent about $48 million for the Critical Ecosystem Studies Initiative (CESI), a program begun in 1997 to accelerate research to provide scientific information for the restoration initiative. The National Park Service used CESI funding to support research (1) to characterize the ecosystem’s predrainage and current conditions and (2) to identify indicators for monitoring the success of restoration in Everglades National Park, other parks, and public lands and to develop models and tools to assess the effects of water projects on these natural lands. Of the remaining Interior funding, the Fish and Wildlife Service and the Bureau of Indian Affairs spent $10 million and $3 million, respectively. Four agencies spent the other federal funds—$134 million. The Corps of Engineers and the National Oceanic and Atmospheric Administration spent approximately $37 million each, primarily on research activities. Two other federal agencies—the Agricultural Research Service and the Environmental Protection Agency—spent the remaining $60 million in federal funds. In addition to the $273 million spent by federal agencies, the State of Florida’s South Florida Water Management District provided $303 million for such activities from 1993 to 2002. The District spent much of its funding on scientific activities related to water projects in line with its major responsibility to manage and operate the Central and Southern Florida Project and water resources in the ecosystem. With these federal and state expenditures, scientists have made some progress in developing scientific information and adaptive management tools. In particular, scientists now better understand the historic and current hydrological conditions in the ecosystem and developed models that allow them to forecast the effects of water management alternatives on the ecosystem. Scientists also made significant progress in developing information on the sources, transformations, and fate of mercury—a contaminant that affects water quality and the health of birds, animals, and humans—in the South Florida ecosystem. Specifically, scientists determined that atmospheric sources account for greater than 95 percent of the mercury that is added to the ecosystem. In addition, scientists made progress in developing (1) a method that uses a natural predator to control Melaleuca, an invasive species, and (2) techniques to reduce high levels of nutrients—primarily phosphorus—in the ecosystem. While scientists made progress in developing scientific information, they also identified significant gaps in scientific information and adaptive management tools that, if not addressed in the near future, will hinder the overall success of the restoration effort. We reviewed 10 critical restoration projects and plans and discussed the scientific information needs remaining for these projects with scientists and project managers. On the basis of our review, we identified three types of gaps in scientific information: (1) gaps that threaten systemwide restoration if they are not addressed; (2) gaps that threaten the success of particular restoration projects if they are not addressed; and (3) gaps in information and tools that will prevent restoration officials from using adaptive management to pursue restoration goals. An example of a gap that could hinder systemwide restoration is information on contaminants, such as fertilizers and pesticides. Scientists are concerned that the heavy use of fertilizers and pesticides—which are transported by water and soil and are deposited in sediments—near natural areas in South Florida increases the discharge of chemical compounds into these areas. Contaminants are absorbed by organisms such as aquatic insects, other invertebrates, and fish that live in the water and sediment, affecting the survival and reproduction of these organisms and those that feed on them. Scientists need information on the amount of contaminants that could be discharged into the environment, the amounts that persist in water and sediment, and the risks faced by organisms living in areas with contaminants—even low levels of contaminants on a long- term basis. If this information is not available, scientists cannot determine whether contaminants harm fish and other organisms or whether the redistribution of water will introduce potentially harmful contaminants to parts of the ecosystem that are relatively undisturbed. An example of a gap that could hinder the progress of a specific project is information needed to complete the Modified Water Delivery project, which has been ongoing for many years and has been delayed primarily because of land acquisition conflicts. The Modified Water Delivery project and a related project in the Comprehensive Everglades Restoration Plan are expected, among other purposes, to increase the amount of water running through the eastern part of Everglades National Park and restore the “ridge and slough” habitat. However, scientists identified the need for continued work to understand the role of flowing water in the creation of ridge and slough habitat. If the information is not developed, the project designs may be delayed or inadequate, forcing scientists and project managers to spend time redesigning projects or making unnecessary modifications to those already built. An example of a gap in key tools needed for adaptive management is the lack of mathematical models that would allow scientists to simulate aspects of the ecosystem and better understand how the ecosystem responds to restoration actions. Scientists identified the need for several important models including models for Florida Bay, Biscayne Bay, and systemwide vegetation. Without such tools, the process of adaptive management will be hindered because scientists and managers will be less able to monitor and assess key indicators of restoration and evaluate the effects created by particular restoration actions. The Water Resources Development Act of 1996 requires the Task Force to coordinate scientific research for South Florida restoration; however, the Task Force has not established an effective means to do so, diminishing assurance that key scientific information will be developed and available to fill gaps and support restoration decisions.