Contra Costa Water District - Rock Fish Slough

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The Contra Costa Canal (Canal) is part of the Central Valley Project’s Delta Division. Water from the Sacramento-San Joaquin Delta is diverted at Rock Slough conveyed to the beginning of the Canal. This Canal is a major water supply and delivery system for the Contra Costa Water District. Between 120,000 and 130,000 acre-feet of water per year is diverted by the Canal for irrigation and municipal and industrial uses. The Canal diversion at Rock Slough is one of the largest unscreened Delta sites. A number of resident and migratory fish species, including the threatened Delta smelt and the endangered winter-run Chinook salmon, can be drawn into the Canal. A fish screen has been constructed to keep fish from entering the Canal intake. The fish screen functions to: 1. Minimize the entrainment of fish resources associated with the diversion of water at the Rock Slough Intake of the Contra Costa Canal. 2. Reduce potential predation on target species in the Rock Slough Intake. 3. Fulfill legal requirements of the U.S. Fish and Wildlife Service’s 2008 Biological Opinion for the threatened Delta smelt. 4. Complete the mitigation for the Los Vaqueros Biological Opinion. 5. Complete Central Valley Improvement Act requirements in Section 3406(b)(5). There have been operational problems primarily associated with the automated debris handling system. This has included the take of salmon. The system has undergone extensive testing, currently all four rake units are operational, completing the construction contract obligations pending the final punch list details that were sent to the construction contractor Flatiron. A re-design effort has been active to produce new specifications for removing and replacing the rake system. Monitoring of fish response to the automated debris handling system is also ongoing, having been initiated in November 2011 when the first salmon take was identified.

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