Trout Unlimited (TU), the California Department of Fish and Wildlife (CDFW), the National Fish and Wildlife Foundation (NFWF) and other resource management entities are working toward Lahontan cutthroat trout (LCT) recovery in the Lahontan Basin. As part of this effort, Balance Hydrologics was hired to evaluate the feasibility of implementing a physical barrier on the East Fork Carson River (EFCR) in Alpine County, California. Constructing a barrier to limit upstream passage by non-native fish would reduce the threat of non-native predation and competition with LCT and would create an LCT stronghold in the upper East Fork Carson River Watershed. The feasibility evaluation was completed in order to a) identify suitable sites for a barrier, b) develop and apply criteria for evaluating the sites, c) develop conceptual barrier designs for the three most suitable sites, and d) summarize the opportunities and constraints associated with the three sites. Balance completed field reconnaissance of a six-mile reach of the EFCR identified by CDFW and TU to identify three most suitable sites, then performed photogrammetric and bathymetric surveys to generate basemaps for subsequent two-dimensional hydraulic modeling and conceptual design development. The findings of the feasibility study and the conceptual designs were summarized in a report summited to TU and CDFW in March 2020.
Balance was retained for a second phase to (1) complete additional technical analyses to provide objective information to inform the selection of a final barrier site and (2) advance the conceptual designs from the previous phase to a 65% level. Balance led a team of professionals to identify constraints and opportunities for the three sites related to geotechnical considerations, structural engineering considerations, and construction logistics and costs. The 65% designs and the constraints and opportunities summary are currently being used by the stakeholder group to select one of the three sites to move into the permitting and advanced design phases.