The Florida Everglades is a unique network of subtropical wetlands that is currently half its historical size. The federal government has a long history of involvement in the Everglades, beginning in the 1940s with the U.S. Army Corps of Engineers (the Corps) constructing flood control projects that shunted water flowing south into the Everglades to make way for agricultural and urban development. Other factors, including major nonfederal development efforts, also have contributed to shrinking and altering the Everglades ecosystem. In recognition of the unique nature of the Everglades, federal and state agencies began ecosystem restoration activities in the Everglades in the early 1990s, and many of these activities are ongoing. However, it was not until 2000 that federal and state restoration activities were coordinated under an integrated plan. In the Water Resources Development Act of 2000 (WRDA 2000; P.L. 106-541 ), Congress approved the Comprehensive Everglades Restoration Plan (CERP) as a framework for Everglades restoration. In addition to the CERP framework and related processes, the WRDA 2000 authorized an initial round of projects with federal participation by the Corps and the Department of the Interior (DOI). The plan envisioned 50 major projects to restore the quantity, quality, and timing of water deliveries in south Florida to historical conditions. According to the process established under CERP, Everglades restoration projects are to be studied and presented to Congress for authorization as their planning is completed (presumably in water resources development acts, typically referred to as WRDAs). Since passage of CERP, nine non-pilot CERP projects have been authorized. Other projects are ongoing in the study phase (including projects that have completed the study phase and are awaiting congressional authorization). Most observers agree that, although progress has been made on Everglades restoration, much more time and funding would be required to achieve restoration as currently contemplated. Previously, some have highlighted what they consider to be the "slow" pace of restoration as an argument for increased and expedited financial support. Conversely, others have argued that restoration activities in the Everglades receive too much funding relative to other priorities, and that the level of support provided for these activities is not appropriate given larger fiscal concerns and the uncertainty of results. At issue for Congress is oversight and implementation of efforts to restore the Everglades, including the ongoing federal funding commitment and the priority of Everglades restoration relative to other federal commitments. Stakeholders involved with planning other large-scale restoration initiatives (e.g., Great Lakes, Chesapeake Bay) look to the Everglades as a model and a test case. The achievements realized and challenges faced in Everglades restoration efforts may provide additional information on the possibilities and limitations inherent to all large-scale ecosystem restoration efforts. This report provides information on Everglades restoration, with a focus on the federal role in funding this restoration and related issues for Congress. The report discusses background, trends, and major accomplishments and challenges to date in federal efforts to restore the Everglades. Federal efforts to restore the Everglades are often divided into two broad categories: CERP and non-CERP (or "Foundation" projects). CERP efforts refer to projects and programs authorized in the Comprehensive Everglades Restoration Plan, enacted in WRDA 2000. Non-CERP refers to the subset of federal Everglades restoration activities that were not enacted in CERP (many of these efforts predate CERP). CERP considered and assumed implementation of a number of non-CERP projects; thus, both efforts are considered to be complementary. Federal CERP funding was first authorized in WRDA 2000, with a focus on increasing storage and treatment of excess water in the rainy season to provide more water during the dry season for the Everglades ecosystem and for urban and agricultural users. In the original documents presented to Congress in 1999, CERP was expected to consist of 50 projects and was estimated to cost $8.2 billion (in 1999 dollars) to complete. Over time, the reported funding requirement to complete the projects has increased, although some of this increase has been due to inflation (see Table 1 , below). As of 2014 (when the total cost estimate was last updated), the Corps estimated that completing construction of CERP projects would take more than 50 years and would cost $16.4 billion. Approximately 60% of $8.2 billion (rounded) in cost increases from 1999 to 2014 were attributed to inflationary increases, and the remainder has been attributed to other factors. Pursuant to CERP, project construction costs are shared 50/50: the federal government is required to pay half of project costs, and an array of state, tribal, and local agencies (i.e., nonfederal sponsors) must pay the other half. The same cost share applies to all project operation and maintenance costs. WRDA 2000 included initial projects (including pilots), established the aforementioned cost-sharing ratios and created a process for additional projects to be authorized as part of the CERP framework. Subsequent legislation has built on this: WRDA 2007 authorized three additional CERP projects; four other projects completed the study phase between 2007 and 2014 and were thus authorized for construction in the Water Resources Reform and Development Act of 2014 (WRRDA 2014; P.L. 113-121 ); and two other CERP projects were authorized in the Water Infrastructure Improvements for the Nation Act (WIIN Act; P.L. 114-322 ), enacted on December 16, 2016. The status of these projects is discussed later in this report. Federal Everglades restoration activities not authorized under CERP are often referred to as "non-CERP" or "Foundation" activities. Most (but not all) of the authorities for this funding predate the enactment of CERP in 2000. For example, this category includes funding for the Modified Water Deliveries Project that originally was authorized under the Everglades National Park Protection and Expansion Act of 1989 ( P.L. 101-229 ). Depending on how broadly the non-CERP category is defined, it can encompass a wide variety of Everglades restoration activities undertaken by multiple agencies. Similar to CERP funding, non-CERP activities of the Department of the Interior and the Corps typically receive much attention and are often the focal point of congressional consideration. Unlike for CERP, there is no statutorily required cost-share split for non-CERP projects. Federal funding for Everglades restoration is largely provided through DOI and the Corps and is concentrated in two annual appropriations bills—the Interior and Environment appropriations bill (which provides funds for much of DOI) and the Energy and Water Development appropriations bill (which funds the Corps). Additional funding in other appropriations bills is sometimes noted as contributing to Everglades restoration, but is not formally tracked under the Administration's non-CERP totals. Although the Administration's budget request typically identifies restoration funding totals for CERP and non-CERP for both DOI and the Corps, appropriations laws and conference reports typically do not tabulate and specify their recommended appropriations levels for Everglades restoration activities (for either CERP or non-CERP totals). Rather, these totals are embedded within project and account-level totals of the Corps and DOI. A summary of funding for DOI and Corps CERP and non-CERP activities in recent years is shown in Table 2 . Everglades restoration funding within the Department of the Interior, Environment, and Related Agencies Appropriations bill is generally allotted to four agencies within DOI: the National Park Service (NPS), the Fish and Wildlife Service (FWS), the U.S. Geological Survey (USGS), and the Bureau of Indian Affairs (BIA). Within these agencies, two types of Everglades funding are often highlighted in appropriations debates: funding for CERP and funding for the Modified Water Deliveries Project for Everglades National Park (also known as the Mod Waters project). Mod Waters is a non-CERP project that has received significant attention from Congress. It aims to improve water deliveries to Everglades National Park by removing barriers in and around the Tamiami Trail. Although Mod Waters is technically a non-CERP project, it is widely considered to be a keystone project for Everglades restoration, with an important nexus to CERP. DOI's CERP funding largely goes to NPS and FWS to carry out CERP project activities related to NPS and FWS units (e.g., national parks, wildlife refuges) and authorities that fall under CERP. Non-CERP DOI Everglades restoration funding provides for a number of different activities in addition to the Mod Waters project. These activities include management of national parks and national wildlife refuges in the Everglades, research and monitoring, implementation of relevant laws in the Everglades such as the Endangered Species Act (16 U.S.C. §§1531-1544) and the Migratory Bird Treaty Act (16 U.S.C. §§703-712), and BIA funding for the Seminole and Miccosukee to carry out water- and ecosystem-related planning and studies. Non-CERP DOI funding also includes operations of the South Florida Ecosystem Restoration Task Force, which supports DOI, the Corps, and the state of Florida in carrying out Everglades restoration. The FY2018 Trump Administration request for DOI bureaus receiving Everglades restoration funds was $54 million. That included $8 million for CERP projects and $46 million for non-CERP projects. Corps funding is directed toward planning and construction of projects authorized under CERP and other authorities.