Irvine Lake is set to be drained next week in preparation for the coming El Niño winter and a major overhaul of the nearly century-old Santiago Creek Dam.
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The planned work has drawn ire from members of the shoreline fishing community.
Water levels will be reduced from about 738 feet to 720 feet on Monday, Oct. 26, according to the Irvine Ranch Water District, which manages the lake. Roughly 300 acre-feet of water will remain in the lake until next summer, when the reservoir will be emptied for construction on the dam improvement project.
The district has already reduced water levels as part of “normal operations,” but the further drawdown is necessary for safety reasons, spokesperson John Fabris said.
“The El Niño-related reason for drawing the water level down now is to ensure we have enough space in the reservoir to accommodate major storms and keep the downstream community safe,” Fabris said in an email.
Irvine Lake was created in 1933 when the Santiago Creek Dam was built. The 750-acre man-made reservoir is the largest body of freshwater in Orange County and a favorite fishing destination for many, drawing visitors across the county. It is regularly stocked with fish by OC Parks.
Though the lake has become a popular fishing spot, its main purpose is to capture and store drinking water for 900,000 residents, Fabris said.
According to a comprehensive assessment conducted by the water district in 2017, the dam’s aging components are nearing “the end of their useful lives” and need to be replaced to meet current “seismic and safety standards,” Fabris said.
The dam project will replace the outlet tower and spillway to enhance safety and restore the reservoir’s original water storage capacity — 3,700 acre-feet more than current capacity, the water district said. The overhaul will allow the reservoir to serve the community for the next century, district officials said, in part by preserving local water supplies rather than having to rely on imported water.
Construction is expected to take five years, during which the lake will remain empty, Fabris said.
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The fishing community has raised concerns about protected fish species in the lake, including white sturgeon and blue catfish, calling on the water district to implement mitigation measures and a fish-salvage plan before draining the lake.
Fabris said the water district has been in communication with the California Department of Fish and Wildlife, as well as numerous fish experts, to explore “options to salvage and move the stocked fish.”
He noted that all the species concerned, including white sturgeon, are “stocked and sterile.” No native fish inhabit the lake.
“We understand the concerns about the effect the project will have on fishing at Irvine Lake,” he said. “After the project is complete, IRWD fully anticipates that fishing will resume.”
OC Supervisor Don Wagner, whose Third District includes the lake area, said management of the reservoir lies with the water district.
“IRWD’s decision to drain the lake is a temporary disruption for our fishing community, but is necessary for renovations to the nearly 100-year-old Santiago Creek Dam and water intake system, and it is their decision to make,” he said in a statement. “We leave the handling of the fish species in the lake to the subject matter experts.”
The lake was previously closed to fishing from 2016 to 2019 over profit-sharing disagreements between two government agencies.
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