Global Range: (100-1000 square km (about 40-400 square miles)) Once thought to have the most restricted distribution of any fairy shrimp (Eng et al., 1990), but now found to be more widespread (USFWS, 2000). The five original pools from which it was collected are all in western Riverside County in an area about 13 by 7 km, between elevations of 348 and 413 m, near Temecula and Rancho California. (Eng et al. 1990). Subsequent localities have been found in Los Angeles, Orange, San Diego, and Ventura Counties, California. In total range extends from coastal southern California south to northwestern Baja California, Mexico (USFWS, 2000; Eriksen and Belk, 1999).