Irvine Lake draining set to begin Monday for dam repairs

Workers are expected to begin draining Irvine Lake on Monday to allow repairs to Santiago Creek Dam and its water-intake system, NBC Los Angeles reported. The project includes seismic, safety and water-storage improvements and is expected to be completed by 2030.

The work has upset local anglers but is intended to improve infrastructure that serves nearly a million residents, according to the water district. Expanding rainwater storage would also help reduce reliance on imported water.

The Irvine Ranch Water District, which manages the lake, has been planning the work for about a decade, according to NBC Los Angeles. Draining the lake will allow crews to work on the dam and water-intake system.

The dam was built in 1933, according to the district. Assessments that began in 2017 found that it remained functional but needed improvements to meet modern seismic and safety standards.

The project is intended to restore the lake's capacity and accommodate an additional 3,700 acre-feet of water. The storage improvements are designed to capture more rainwater, NBC Los Angeles reported.

Orange County Supervisor Don Wagner acknowledged anglers' frustration and said the repairs were necessary, according to NBC Los Angeles. Wagner said plans to drain the lake were already known when it reopened in 2019.

The district's goal is to return the lake to its intended storage capacity while strengthening the dam's safety, with the project expected to be finished by 2030.