Species: Margaritifera falcata

F - 20,000-200,000 square km (about 8000-80,000 square miles) - F - Clarke (1981) lists former distribution as from California to the southern interior of British Columbia, to the Queen Charlotte Islands, and to Revillagigedo Island in Southeast Alaska. Once present from southern Alaska and British Columbia to central California, eastward to western Montana, western Wyoming, and northern Utah in the headwaters of the Missouri River (Nedeau et al., 2005), this species now persists only locally in parts of the Coeur d'Alene system, including the Coeur d'Alene River and St. Maries River (Frest and Johannes, 1995). In Oregon it historically occurred in the Klamath River system, rivers of the Coastal Range, and the main stem and tributaries of the Columbia River, including the Snake, Willamette, and Walla Walla Rivers (Brim Box et al., 2004). Hovingh (2004) found it in the upper Snake River in Wyoming and Idaho, upper Bear River in Wyoming, and Malheur Basin in Oregon. It has been recorded historically north to Naha Bay, Alaska (at 55 degrees North latitude); in the Fraser River; the Snake River in Idaho (Stanford, 1942); at Spokane, Yakima, Walla Walla, The Dalles, and Portland on the Columbia River; in Lake Crescent and the Chehalis River on the Olympic Peninsula; in North Creek (Sammamish River drainage), Whatcom Creek, Samish River, and Snoqualmie River in the Puget Sound lowlands; in the Deschutes River (at Bend, Oregon); in the Umpqua and Coos Rivers in Oregon; "Pinyon Canyon" [locality questionable] and the the Humboldt River, Nevada (UMMZ specimens as <i>Margaritifera margaritifera</i>); and in the Sacramento River, California (Dall, 1905; Henderson, 1929; 1936; Ingram, 1948; Clarke, 1981).