The 4,900 ha (12,000 acres) island is bounded on the north by Empire Cut, on the northeast by Whiskey Slough, on the southeast by Trapper Slough, and on the west, Middle River.

The tracts are bifurcated by the parallel running Mokelumne Aqueduct, West Lower Jones Road, and a railroad originally built by the Achison Topeka and Santa Fe Railroad, which now carries freight trains of the BNSF Railway and Amtrak California's San Joaquin.

It is in San Joaquin County, and managed by Reclamation District 2039.

[1] It appears on 1913 and 1952 United States Geological Survey maps of the area.

The island, which lies 3 metres below sea level, required three weeks to repair the breach, and an additional five months for de-watering after the pumps were shut down on 18 December 2004.