Two native fishes, Crenichthys nevadae and Gila bicolor, inhabit the Railroad Valley system, which is comprised of Little Fish Lake, Hot Creek, Sand Spring, and Railroad Valleys. Crenichthys nevadae is indicative of past connections with the Colorado River system, estimated to have occurred in the early Pleistocene. Crenichthys nevadae is restricted to two springs in the Duckwater area, five springs in the Lockes Ranch area, and two transplant sites. The presence of Gila bicolor is indicative of late Pleistocene connections with the Lahontan system. Several undescribed subspecies of G. bicolor in the Railroad Valley system occur in Duckwater Creek and two springs in northern Railroad Valley, several springs along the east-central edge of' Railroad Valley, Twin Springs and several springs north of Twin Springs Ranch in Hot Creek Valley, several springs in Little Fish Lake Valley, and one transplant site. The native fishes are faced with a variety of threats. One population of C. nevadae and two populations of G. bicolor have been significantly impacted by exotic fishes. Diversion and channelization of aquatic habitats, often accompanied by overgrazing by cattle, is a common problem in the valleys. Oil drilling in Railroad Valley and the proposed MX Missile System are potential threats due to interference with aquifers. Increased human activity associated with any development can be expected to have deleterious impacts on the native fishes and their habitats.
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