In this project fish passage analysis alternatives were prepared for the Dyke Diversion on Twentymile Creek near Adel, Oregon in the Warner Lakes basin.
The purpose of the alternatives analysis is to review three potential fish passage alternatives that meet current ODFW fish passage criteria while also maintaining the surface water diversion and minimizing diversion maintenance. The alternatives analysis is a collaborative effort including the landowner, LCUWC, BLM, ODFW, and U.S. Fish and Wildlife Service (USFWS).
Warner sucker (Catostomus warnerensis) and Warner Lakes redband trout (Oncorhynchus mykiss newberrii) are the species of interest for the Dyke Diversion project. Both species are endemic to the Warner Lakes basin and are known to inhabit Twenty-mile Creek (Scheerer et al. 2011). Warner sucker are listed as federally threatened due to stream degradation, migration corridor barriers, diversion entrainment, and predation by non-native fishes.
Findings of the Warner Suckers migration suggest downstream larval drift is not a significant dispersal mechanism for Warner suckers. Higher sucker densities were found between the Dyke Diversion and the Twelvemile Creek canyon, than in other areas of the Twentymile Creek subbasin (Scheerer et al. 2011).
Inland redband trout were reviewed for possible listing under the Endangered Species Act (ESA), but listing was determined to be unwarranted by U.S. Fish and Wildlife Service (2000). The State of Oregon recognizes inland redband trout as a Sensitive-Vulnerable species.
Warner Lakes redband trout are distributed throughout the perennial streams and lakes in the Warner Valley as conditions allow. Redband trout densities are high in headwater and mid-watershed areas, but tend to decrease in lower watershed reaches due to extreme environmental fluctuations and degraded habitat. It is unclear if the adfluvial life history remains in the Twentymile Creek population (ODFW 2005), although adfluvial life history rearing habitat is available in Crump Lake and Greaser Reservoir.
U.S. Fish and Wildlife Service
Natural Resource Innovations paired with Lake County Umbrella Watershed Council (LCUWC) and U.S. Bureau of Land Management (BLM) to prpeare the fish passage alternatives analysis. The project was funded by the Ruby Mitigation Fund, retained River Design Group, Inc. (RDG).