Species: Gonidea angulata

F - 20,000-200,000 square km (about 8000-80,000 square miles) - F - This species formerly ranged from Central California, north to British Columbia and east to southern Idaho and northern Nevada (Burch, 1975; Taylor, 1981). In Oregon it historically occurred in rivers of the Coastal Range, and the main stem and tributaries of the Columbia River, including tributaries to the Snake and Malheur Rivers and John Day River mainstem (Brim Box et al., 2004). It remains in portions of the Snake River system, namely the Okanogan River in Washington, and Clearwater River, Hells Canyon and middle Snake River in Idaho, but is extirpated from many former locations (Frest and Johannes, 1995). Is "probably extinct in most of the Central Valley and southern California" (Taylor, 1981). It is absent from the Olympic Mountains, Washington and points north but occurs sporadically in Willapa Hills (sw Washington) and northwest Oregon, and occurs more continuously from southwest Oregon south to southern California (COSEWIC, 2003). In Canada, it is found in Columbia River system in southern British Columbia and known only from the main water bodies from Penticton south to the border (COSEWIC, 2003; Metcalfe-Smith and Cudmore-Vokey, 2004). Hovingh (2004) found it in abundance in the Humboldt River drainage in Nevada. Despite early reports by Henderson (1924; 1929; 1936) for Utah and Montana, more recent surveys (Chamberlin and Jones, 1929; Jones, 1940; Oliver and Bosworth, 1999; Gangloff and Gustafson, 2000; Lippincott and Davis, 2000) of these states have failed to find any individuals, however Gangloff and Gustafson (2000) speculate that if it were in Montana, it might be in free-flowing stretches of the Clark Fork River and perhaps some pristine headwater streams such as Rock Creek. Reports for Colorado were recently found to be misinterpreted California localities (Cordeiro, 2007).