Flood control releases planned from Lake Sonoma for 1st time in nearly 4 years amid heavy rain

A series of high-flow releases from Lake Sonoma are set to begin Wednesday as recent rainfall bolstered the reservoir to levels not seen since 2019.

Lake Sonoma was at nearly 119% of its seasonal water supply as of Tuesday afternoon, according to the U.S. Army Corps of Engineers, which co-manages the reservoir with Sonoma Water.

The reservoir, located west of Cloverdale in northern Sonoma County, has a 245,000 acre-foot water supply pool, with a total 381,000 acre-foot capacity.

The reservoir had reached 114.3% of its water supply by Monday, prior to Tuesday’s heavy rain.

The high-flow releases, which will start mid-morning Wednesday from the reservoir’s Warm Springs Dam, are meant to create space for additional runoff and maintain capacity for flood control through the upcoming weeks.

They are the first such releases in nearly four years, according to the Army Corps of Engineers.

Releases are expected to increase through Wednesday and possibly into Thursday morning, timed to coincide with falling downstream river levels.

Lake Mendocino was also expected to shed some water through releases from its Coyote Valley Dam, the Army Corps of Engineers said Tuesday.

The reservoir, located southeast of Redwood Valley in Mendocino County, is currently at about 103% of its water supply, according to a news release from the U.S. Army Corps of Engineers San Francisco District.

High-flow releases were first triggered at Lake Mendocino in January after a series of heavy storms. It had been four years since such flood-control measures were needed at that smaller reservoir, as well.