Big Boggy National Wildlife Refuge is a coastal bird sanctuary in southeastern Matagorda County, Texas, along a bay behind a Gulf barrier island. Established in 1983 to help conserve Texas coastal wetlands, it protects 5,000 acres of salt marsh and is part of a larger refuge complex with Brazoria and San Bernard that supports more than 300 bird species. Its marshes are vital habitat for waterfowl, shorebirds, wading birds, and other waterbirds, including nesting egrets, spoonbills, and pelicans in East Matagorda Bay, as well as the threatened eastern black rail. The refuge is managed chiefly for wildlife, so public access is limited.