The Utah (desert) valvata snail (Valvata utahensis) is a small freshwater gastropod found primarily in the main stem Snake River of Idaho. The shell has up to four whorls (curls or turns in the shell) and reaches a maximum size of about 4 millimeters. The lifespan of the Utah valvata snail is about one year. Populations of the species vary largely across its range. The Utah valvata snail was listed as an endangered species on December 14, 1992 due to threats from proposed hydroelectric development, operation of existing hydroelectric dams, degraded water quality, diversion of water for irrigation and aquaculture, lack of regulatory protections for spring habitats, and invasion of the introduced New Zealand mudsnail. In 1995 the Service described the distribution of the Utah valvata at Snake River mile 585, just below the Thousand Springs Preserve, to Snake River mile 709, just below American Falls Dam. Recent surveys indicate the species is now known to be more widespread than thought at the time of listing, and it is tolerant of a variety of habitat conditions such as reservoirs, springs and riverine habitats without spring influence. The species occurs on a variety of substrate types, and has been collected at a range of water depths and temperatures. Today, it is known to occur in the Snake River from RM 585 to the confluence of the South Fork and Henry’s Fork, Snake River at RM 837. The species is also known from portions of Box Canyon Creek and the Big Wood River in southern Idaho.