Andrus Island is an island in the Sacramento-San Joaquin River Delta in Sacramento County, California, twenty kilometres northeast of Antioch. The 3,000-hectare (7,400-acre) island is bounded on the north, and northwest by the Sacramento River, on the west, Georgiana Slough, on the southeast, Mokelumne River, and San Joaquin River, on the southwest Jackson Slough, and Seven Mile Slough.