Sherman Island is an island in the Sacramento-San Joaquin River Delta at the confluence of the two rivers in Sacramento County, California, 1.2 miles northeast of Antioch. The 5,500 ha island, mostly managed by Reclamation District 341, is the meeting point of Sacramento, Solano, and Contra Costa Counties, and is bordered on the north and northwest by the Sacramento River, on the northeast by Three Mile Slough, and on the east, and south west by the San Joaquin River.