Drawdown starts Oct. 26, 2026
What IRWD says: Starting Oct. 26, Irvine Ranch Water District will lower Irvine Lake from 735 feet to about 720 feet, IRWD spokesperson John Fabris told SFGATE. That leaves about 300 acre-feet of water, down from roughly 2,800 acre-feet now. The lake will stay near that level through winter, and if storms raise it, IRWD will draw it back down. Next summer the lake will be drained completely so dam construction can start. It should begin collecting water again in about five years.
Fishing: OC Parks still lists shoreline fishing Fridays through Sundays, 7 a.m. to 4 p.m., with $5 parking, and hasn’t named a final fishing day. Fabris said IRWD “fully anticipates that fishing will resume” after the project, and that the district is talking with fish experts and the California Department of Fish and Wildlife about possibly relocating fish.
Water Board permit: Order R8-2026-0042, the Santa Ana Regional Water Quality Control Board permit for the dam project, was Item 11 on the board’s Oct. 23, 2026, agenda. The staff report recommended adopting the order as presented, without a fish-salvage requirement.
Irvine Ranch Water District begins lowering Irvine Lake on Oct. 26, 2026, the first step toward the Santiago Creek Dam Improvement Project. The lake will sit at about 300 acre-feet through winter and be drained completely next summer, when major dam construction begins. IRWD estimates the project will be finished in 2030.
The work is much more than a renovation of the recreational areas around Irvine Lake. Santiago Creek Dam, which forms the lake, is more than 90 years old, and the project will replace major components of the dam, strengthen the earthen embankment and improve seismic safety and water-storage reliability.
When Is Irvine Lake Closing?
IRWD has already been lowering the lake as part of normal operations. On Oct. 26, 2026, it starts drawing the lake down further, from 735 feet to about 720 feet, according to SFGATE. About 300 acre-feet will stay in the lake until next summer, when it is drained completely for construction. Fabris said the district would need to lower the lake ahead of this winter’s expected El Niño storms even without the project, to leave room for major storms and keep the downstream community safe.
Supervisor Don Wagner first announced the October drain while promoting the September 12, 2026, catfish derby, which he called the last Irvine Lake derby for the foreseeable future (California Sportsman). The Santa Ana Regional Water Quality Control Board set an October 23, 2026, public hearing on the project permit, Tentative Order R8-2026-0042. The notice says the project will cause up to 162.23 acres of temporary and 3.22 acres of permanent impacts to waters, including vegetation impacts from dewatering Irvine Lake. The staff report recommended adopting the order as presented.
Shoreline fishing is open Fridays through Sundays from 7 a.m. to 4 p.m., per OC Parks. Parking is $5 per vehicle. Since July 1, 2026, fishing has been run by James Event Productions, and OC Parks annual passes are no longer accepted. Neither OC Parks nor the IRWD Santiago Creek Dam project page has named a final fishing day. Red flag wind warnings and other hazards can close the lake.
See our Irvine Lake guide for current fishing hours, rules, parking, maps and visitor information.
How Long Will the Irvine Lake Project Take?
IRWD currently expects major construction to begin in summer 2027, with the project estimated to be completed in 2030. Orange County Water District has described the dam construction as spanning four dry seasons and reported that water will not be retained behind the dam during that work.
- 2026: Site preparation and advance construction activities.
- October 23, 2026: Santa Ana Water Board hearing on the project permit (Order R8-2026-0042, Item 11).
- October 26, 2026: IRWD begins lowering the lake from 735 feet to about 720 feet, leaving about 300 acre-feet through winter.
- Summer 2027: The lake is drained completely and major Santiago Creek Dam construction begins.
- 2027–2030: Major dam construction period.
- 2030: Current estimated project completion.
Why Is Irvine Lake Being Drained?
The drawdown is necessary so crews can complete the Santiago Creek Dam improvements safely. The dam was originally constructed in 1933, creating Irvine Lake. IRWD began a comprehensive assessment of the dam in 2017.
According to IRWD, the engineered earthen dam remains operational but could be made safer. The assessment also determined that the existing outlet tower and spillway are reaching the end of their useful lives and should be replaced and upgraded to modern seismic and dam-safety standards.
What Work Will Be Done at Santiago Creek Dam?
The Santiago Creek Dam Improvement Project includes several major improvements:
- Replace the existing outlet tower that controls water entering and leaving Irvine Lake.
- Construct a new spillway designed to current seismic and safety standards.
- Strengthen the earthen dam embankment.
- Improve control of water flowing into and out of the reservoir.
- Restore reservoir storage capacity.
- Improve long-term seismic performance, dam safety and water reliability.
Advance work also includes modifications to the outlet tower, a temporary water line along Blue Diamond Haul Road, an isolation valve for the Irvine Lake Pipeline, demolition of the former dam keeper’s residence and removal of a floating boat dock along the lake’s western shoreline.
Why Irvine Lake Is Important to Orange County
Irvine Lake is best known locally for fishing, but recreation is not its primary purpose. The reservoir stores water for surrounding Orange County communities and supplies water used by the Baker and Howiler treatment plants. IRWD says those facilities collectively provide water to approximately 85,000 homes in Central and Southern Orange County.
The project is also intended to restore additional reservoir capacity, allowing Irvine Lake to capture more local rainwater and helping reduce dependence on imported water.
What Does the Project Mean for Villa Park?
Irvine Lake has a direct connection to Villa Park’s water supply. Serrano Water District, which serves Villa Park and a small portion of Orange, owned 25% of Irvine Lake for more than 90 years. On January 15, 2025, Serrano transferred its ownership of Irvine Lake and Santiago Creek Dam to Irvine Ranch Water District.
Serrano Water District continues to use local surface water stored in Irvine Lake as part of its water supply. The ownership transfer was made in exchange for a new backup water-supply connection between Serrano and IRWD, providing another connection to the regional water system.
Will Irvine Lake Fishing Close?
Fishing at Irvine Lake has been run by James Event Productions since July 1, 2026, while IRWD manages the reservoir and the dam project. OC Parks hasn’t posted a last fishing day. Anglers have asked the Water Board to require a fish-salvage plan before the lake is drained, especially for the white sturgeon, which are catch-and-release only. Fabris told SFGATE that Irvine Lake has no native fish, only stocked fish, and that IRWD is in touch with fish experts and the California Department of Fish and Wildlife about possible relocation plans.
Fishing hours and closures are posted on the OC Parks Irvine Lake page. Construction updates are on the IRWD Santiago Creek Dam Improvement Project page.
Will Irvine Lake Reopen?
The project is meant to keep Santiago Creek Dam and Irvine Lake operating for decades, not to eliminate the reservoir. IRWD has described the work as preparing the facility for another 100 years. When it’s done, the reservoir will return to its full design capacity of 28,000 acre-feet, Fabris told SFGATE, and the lake should start collecting water again in about five years.
IRWD “fully anticipates that fishing will resume” after the project, according to Fabris. No date for the return of shoreline fishing has been announced.