Edgewater is a census-designated place in Anne Arundel County, Maryland, United States. The population was 9,023 at the 2010 census. Edgewater is a suburb located southwest of Annapolis on the south side of the tidal South River. It is bordered by Mayo to the east, gd Riva to the west, and Lothian to the south. To the north, across the South River, …Edgewater is a census-designated place in Anne Arundel County, Maryland, United States. The population was 9,023 at the 2010 census. Edgewater is a suburb located southwest of Annapolis on the south side of the tidal South River. It is bordered by Mayo to the east, gd Riva to the west, and Lothian to the south. To the north, across the South River, are the communities of Parole and Annapolis Neck.