McElwain Creek is a second order
tributary to lower Nevada Creek. It flows northeast from its headwaters in the Garnet
Mountains and onto the Nevada Valley before entering Nevada Creek at river mile 1.2.
McElwain Creek headwaters on Bureau of Land Management property before entering a large
private cattle ranch in the lower reaches.
In order to prioritize restoration
resources, we developed a fisheries-based restoration priority scorecard, based on
biological, social and financial considerations, for 83 impaired tributaries of the
Blackfoot River. McElwain Creek ranked 21 of 83 streams surveyed.
In 1998, we conducted fish population
surveys in two sections, one located on Bureau of Land Management land at approximately
stream mile 2.5. Another section was established on private land at stream mile 1.0.
Westslope cutthroat trout were the only fish species captured in either station. We
collected tissue samples from 25 fish in the upstream station and determined they are
genetically pure strains of westslope cutthroat trout. The catch per unit effort (CPUE) at
stream mile 2.5 was 14.4 fish/100 feet verses 0.9 fish/100 feet at stream mile 1.0.
Once McElwain Creek leaves the
mountains, most of its flow is seasonally diverted for irrigation and has several fish
passage barriers. The 1998 assessment also indicated this reach was incised with eroding
banks and high water turbidity. In 2000, we worked with the rancher to remove a large
feedlot at river mile 1.5. This involved developing off-site water and establishing a
grazing system on the lower two miles of McElwain Creek.