The Chesapeake Bay Program is the unique regional partnership which has been directing and conducting the restoration of the Chesapeake Bay since the signing of the historic 1983 Chesapeake Bay Agreement. The Chesapeake Bay Program partners include the states of Maryland, Pennsylvania, and Virginia; the District of Columbia; the Chesapeake Bay Commission, a tri-state legislative body; the Environmental Protection Agency, representing the federal government; and participating advisory groups. As the largest estuary in the United States and one of the most productive in the world, the Chesapeake was this nation's first estuary targeted for restoration and protection. In the late 1970s scientific and estuarine research on the Bay pinpointed three areas requiring immediate attention: nutrient over-enrichment; dwindling underwater Bay grasses; and toxic pollution. Once the initial research was completed, the Chesapeake Bay Program evolved as the means to restore this exceptionally valuable resource.