DIVERTING DAM ANNUAL MAINTENANCE

Background: Upon completion (in 1887) the Cuyamaca and Diverting dams became integral pieces of infrastructure for the San Diego Flume Company (Helix Water District isthe successor). Water was stored behind Cuyamaca dam during the rainy season and then transferred via Boulder Creek and the San Diego River to the Diverting dam. Once at the Diverting dam, water was released into the flume, and eventually stored in La Mesa for distribution to its customers. By 1937, the flume was abandoned, due to the construction of EI Capitan Dam and Reservoir. The District retains the right to store up to 10,000 acre-feet of water annually in EI Capitan Reservoir. The Diverting Dam continues to be used as a metering station to account for the District's storage rights in EI Capitan Reservoir, and will continue to be used in this manner for the foreseeable future. An average of 6,565 acre feet per year flows through this metering station and is ultimately transferred from EI Capitan Reservoir to either Lake Jennings, or Helix Water District's R. M. Levy Water Treatment Plant thusly serving as local water supply and helping to reduce the amount of imported wafer required in the County. Project: The District is proposing a maintenance project to remove trash, debris, silt and vegetation that facilitates the inspection and continued safe operation of the dam and metering station. Since 2003 the district has maintained a Streambed Alteration Agreement with the California Department of Fish and Wildlife. The current agreement is EPIMS-SDO-57397-R5, issued on January 7, 2026. All project work will be in compliance with the SAA; per SSA Section 2.1 (Work Period), no vegetation or sediment removal work will be performed between February 2 and September 15, to avoid potential impacts to nesting birds. The benefits associated with the proposed project include the ability to transfer local water supply in an efficient manner, reduce the dependence on imported water, and the continued integrity of the dam. Another benefit will be the reestablishment of a small pool of water behind the dam that in the past has been used by wildlife. This will benefit both the customers of Helix Water District as well as the continued safety of downstream properties. Project is slated to begin after September 15th in accordance with the SAA permit and be completed by February 1, 2027.