San Clemente Dam Drawdown

San Clemente Dam Drawdown

The San Clemente Dam is located approximately 18.5 river miles upstream from the confluence with the Pacific Ocean and is made up of two distinct arms: the Carmel River arm and the San Clemente Creek arm. The Carmel River arm is almost completely filled in with sediment; accumulation of sediment is so great that the capacity of water stored behind the San Clemente Dam has been reduced from approzimately 1,575 acre-feet when the dam was constructed in 1921 to its current volume of approximately 140 acre-feet. As a result of real pressure on the aging structure, the Depatment of Water Resources, Division of Dam Safety, has required Cal-Am to lower the water surface elevation behind the dam to reduce the risk of flooding that may occur due to an earthquake. Drawdown would occur once the reservoir capacity exceeds 50 acre-feet and streamflow is equal to or less than 30 cfs as measured at the Sleepy Hollow gauge station. The reservoir would be lowered under one of three scenarios: Scenario A would lower the reservoir by discharging water through drawdown ports to an elevation of approximately 515 feet. Scenario B would lower the water through the stovepipe to an elevation of approximately 519 feet. Scenario C would keep the drawdown ports closed so that the discharge to the Carmel River would be reduced by no more than 1 to 2 cfs per day until the reservoir elevation reaches 519 feet, after which water would be discharged through the stovepipes until the reservoir level reaches 515 feet. Measures to protect southern steelhead (Oncorhynchus mykiss irideus) and California red-legged frogs (Rana aurora draytonii) would be incorporated into the project, including capture and relocation of both species from the project site. Issuance of Streambed Alteration Agreement Number 1600-2004-0149-3 pursuant to Fish and Game Code Section 1602.

Monterey