Snake River Aquaitc Species Recovery Plan

U.S. Fish and Wildlife Service

On December 14, 1992, the Service added 5 aquatic snails from the Snake River in south central Idaho to the Federallist of Threatened and Endangered Wildlife (57 FR 59244). The Service determined the Idaho springsnail or Homedale Creek springsnail (Pyrgulopsis idahoensis),the Utah valvata snail (Valvata utahensis),Snake Riverphysasnail (Physa natricina), and the undescribed Banbury Springs lanxinthe genus Lana as endangered; and the Bliss Rapids snail (Taylorcncha serpenticola) as threatened. Habitat elements important to the continued survival of these species include cold, unpolluted, well-oxygenated flowing water with low turbidity (orhigh clarity). These species also prefer gravel-to-bouldersize substrate, with the exception of Utah valvata and possibly the Idaho springsnail. The recovery priority for each of the listed species is as follows: - Idaho springsnail, Utah valvata, and SnakeRiver physa: The recovery priority for each of these taxa is five C (SC), indicating that: 1) taxonomically, all 3 are species; 2) each species is subject to a high degree of threat; 3) is rated low in terms of recovery potential; and4) each species has a high degree ofpotential conflict associated with recovery. - Bliss Rapids snail: The recovery priority for this taxon is seven C (7C), indicating that: 1) taxonomically, it is a monotypic genus; 2) is subject to a moderate degree of threat; 3) the recovery potential is high; and 4) the degree of potential conflict during recovery is high. - Banbury Springs lanx: The recovery priority for thistaxon is eight (8), indicating that: 1) although taxonomically undescribed, it is believed to be a species; 2) is subject to a moderate degree of threat; and 3) the recovery potential is high. The Snake River from C.J. StrikeReservoir to American Falls Dam (Figure 1) provides habitat for 25 extant native fish taxa (Appendix A) and at least 42 native molluscs (Appendix B). This includes the 5 listed Snake River snails, as well as 4 additional snails and fish taxa currently considered Species of Concern (SC) by the Service [the California floater (Anadonta californiensis), Columbia pebblesnail (Fluminicola columbiana). Shoshone sculpin (Cottus greenei) and redband trout (Oncorhynchus mykiss gairderni)], and a State Species ofSpecial Concern (SSC) fish taxon, the white sturgeon (Acipenser trafismontanus). With the advent of exploration and development, the Snake River ecosystem has undergone a significant transformation from a primarily free-flowing, cold-water system to a slower moving, warmer system. The human-induced environmental stressors to the Snake River include numerous pointand nonpoint pollution sources, diversion of water for irrigation or hydropower, and construction of several mainstemdams (see Figure 7). This recovery plan specifically addresses the 5 federally listed Snake Riversnails (Service 1992). However, the aquatic habitats essential to these listed species and other aquatic species between C.]. Strike and American Falls Damare similar and cannot be isolated for recovery purposes. Therefore, in order to be successful,this recovery planand the entire recovery effort are designed to address the middle Snake Riverecosystem rather thantreating each individual species separately. For the purposes of this recovery plan, the middle Snake Riveris defined as the reach between C.J. Strike Reservoir (rkm 834, rm 518) upstream to American Falls Dam (rkm 1,150, rm 714) (Figure 1). Additional information about the location, history, natural history and history of water use of the middle Snake River can be reviewed in Appendix C. For information regarding landmarks and associated river miles/kilometers along the Snake River, see AppendixD.

Snake River Aquaitc Species Recovery Plan

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