Cosumnes River Flow Augmentation Project

The Cosumnes River Flow Augmentation Project consisted of a pilot project conducted in 2005 in which Cosumnes River flows were supplemented with water released into the river from the Folsom South Canal. The project water supply was provided by the Central Valley Project – B2 Environmental Water Program. The project objectives were to:

• Improve fall-run chinook salmon migration conditions by allowing the Cosumnes River to connect to tidewater earlier in the fall, and sustaining surface flow continuity in the Cosumnes River after its initial connection.
• Evaluate the rate of groundwater recharge from the river channel between the Folsom South Canal and Twin Cities Road to better guide future groundwater management and environmental restoration efforts along the Cosumnes River corridor.

RBI prepared the 2005 Pilot Project Operation Plan, Monitoring Plan, and CEQA Categorical Exemption, and coordinated implementation of the project with the project’s partners, which included the Southeast Sacramento County Agricultural Water Authority, The Nature Conservancy, and Sacramento County Water Agency.

The Pilot Project demonstrated that it is possible to mimic historical river conditions by releasing supplemental flows into the Cosumnes River from the Folsom South Canal. These conditions supported a more successful fall migration of chinook salmon to the spawning areas at the base of the Sierra foothills.