Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) The range is primarily west of the Cascade-Sierra Nevada crest from south-central Washington and north-central Oregon (mainly west of Cascade crest) south through western Oregon and California to northern Baja California, including islands off southern California and northern Baja California (Stebbins 2003). Isolated populations exist east of the Sierra Nevada at Grant Lake, Mono County, California; Alabama Hills and Walker Pass, Kern County, California; Walker Creek near Olancha, Inyo County, California, and along the Mojave River, California; there is also an isolated occurrence at Sierra La Asamblea, Baja California Sur (Stebbins 2003). The species was introduced at Las Vegas, Nevada (Stebbins 2003). Unconfirmed sight record at Boulder Beach Campground, Clark County, Nevada (Stebbins 2003). DNA data suggest that the population on San Nicolas Island, California, may have been recently transported there (Mahoney et al. 2003). Elevational range is from sea level to around 5,000 feet (1,524 meters) (Stebbins 2003).