Sweetwater Marsh National Wildlife Refuge is an urban refuge located on San Diego Bay in southern California. The refuge, comprising 316 acres of salt marsh and coastal uplands surrounded by urban development, is a critically important area for wildlife because over 90 percent of the historic wetlands of San Diego Bay have been filled in, drained, or diked.
Sweetwater Marsh provides habitat for four endangered or threatened species, including the light-footed clapper rail. It is also the only place in the United Sates where yerba reuma, a member of the heath family, grows naturally. More than 200 species of birds have been recorded on the refuge.