Fay Island is a small, partially submerged island in the San Joaquin River delta, in California. It is part of San Joaquin County, and managed by Reclamation District 2113. Its coordinates are 37°56′55″N 121°33′55″W / 37.9485348°N 121.5652291°W / 37.9485348; -121.5652291 (Fay Island). It appears, almost completely submerged, on a 1952 United States Geological Survey map of the area.