California Agriculture

Spring-run chinook salmon historically migrated far upstream into Sierra Nevada rivers but are now confined to gravel-limited reaches below large dams ringing the Central Valley. In this study, topographic analysis and photo interpretation reveal the 100-year history of channel conditions in the bedrock canyon on the Yuba River below Englebright Dam, which also abuts the UC Sierra Foothill Research and Extension Center. Historical evidence shows that alluvial bars provided spring-run chinook salmon habitat in the reach prior to gold mining and that the influx of hydraulic mining debris dramatically expanded it. However, when Englebright Dam was completed in 1941, shot rock was left in the canyon and allowed to migrate downstream, where it buried gravel bars. We recommend that shot rock be removed to exhume a pre-existing large gravel bar and that new river gravels be placed in the canyon to create salmon habitat.