Marin County Lowers Lake Phoenix to Lessen Likelihood of Winter Flooding
Marin County officials announced last week they’ll begin lowering the water at the Lake Phoenix reservoir to reduce flood risk in San Anselmo and Ross ahead of heavy winter storms.
Starting Monday, officials plan on pumping out between 60 and 160 acre-feet of water — roughly 29 to 70 Olympic-size swimming pools — from the lake over the next four to six weeks, said Jessie Underhill, spokesperson for the Marin Municipal Water District.
“This effort is being done in advance of the winter,” Underhill said, “to help lower the reservoir level and provide extra room which will help absorb runoff from the first storms of the season.”
Lake Phoenix, west of Kentfield and Ross, provides safe drinking water to more than 191,000 people in Marin County, according to a county press release.
Officials said they based the effort on an observation following the 2021 drought, when the reservoir’s “lower water level provided room to capture runoff that otherwise would have flowed into Ross Creek and, ultimately, Corte Madera Creek.”
However, they cautioned that the benefits of their experiment would “depend on the timing, intensity and duration of storms and the lake’s water level when rain arrives.”
In January, strong storms flooded many parts of Marin County, leading to emergency service outages, road closures and property damage. Experts say the coming El Niño is likely to produce similar effects, including torrential downpours, rain instead of snow events, flooding, temporarily elevated sea levels, severe thunderstorms and even isolated tornadoes.
Daniel Swain, a climate scientist with UC Agriculture and Natural Resources, told KQED earlier this month, “This might be a year when the Hollywood version of bad weather in California actually ends up coming true.”
The drawdown comes as cities and counties across the Bay Area steel bayshores and coastlines against a possible wet winter. Last month, the Marin County Board of Supervisors approved an additional $3 million in winter storm preparedness.
Officials said preparedness can reduce risk, but cannot eliminate the possibility of flooding. The county encourages residents to sign up for AlertMarin for emergency updates.