Species: Anodonta nuttalliana

F - 20,000-200,000 square km (about 8000-80,000 square miles) - F - Distribution is confusing as many historical records easily confuse this species with the other western <i>Anodonta</i>, however, it is believed to occur in California, Oregon, Washington, and southern British Columbia (Nedeau et al., 2005) but also east to Utah (Burch, 1975) with Idaho records (Henderson, 1924; 1936) records believed to be <i>Anodonta kennerlyi</i>. Preliminary analysis (K. Mock, Utah State University, pers. comm.) indicates Utah <i>Anodonta </i>are distinct from <i>Anodonta oregonensis</i> of the Pacific northwest and should tentatively be assigned to <i>Anodonta californiensis</i> pending future taxonomic work. Clarke (1981) cites distribution as the Fraser and Columbia River systems in southern British Columbia (absent from Vancouver Island) and south to central California.