Project B.1 Gravel Additions to the Upper Sacramento River
Construction of Shasta and Keswick dams eliminated the recruitment of spawning gravel to the main-stem river immediately below the dams and resulted in “armoring” of the riverbed making much of the substrate unsuitable for spawning. Based on underwater surveys, the Sacramento River downstream of Keswick Dam has become scoured to bedrock in many areas and armored with large cobbles. Overall, the elimination of gravel recruitment from sources upstream of the dams and gradual armoring of riverbed substrates downstream of the dams has resulted in a chronic, but nevertheless important, adverse impact to salmonids by reducing the quantity and quality of spawning areas. Synoptic spawning substrate surveys elsewhere in the mainstem Sacramento River indicate that the substrates are sub-optimal for spawning. The Resources Agency of California believed that the loss of spawning gravel downstream of Keswick Dam and gravel mining in some tributaries partially caused the decline in upper Sacramento River Chinook salmon.
This project would add up to 100,000 tons of spawning gravel to this stretch of the river to substantially enhance its spawning potential. 15,000 tons of gravel were added to the river in 2013 and more is planned in 2014.
The Bureau of Reclamation is managing this project and it is linked to the ongoing gravel studies conducted by the Bureau, The US Fish and Wildlife Service and the California Department of Fish and Wildlife. Gravel will be released at multiple locations.