Marin Water to lower Phoenix Lake 4 feet by mid-November

Marin Water began lowering Phoenix Lake's water level on Monday to create additional storage capacity for storm runoff. The agency is implementing this measure to help reduce flooding risks in the towns of San Anselmo and Ross ahead of the winter storm season.

Pump operations commenced following equipment modifications conducted between October 19 and October 23. The agency expects these operations to continue through mid-November, with specific timing dependent on current weather conditions and water quality assessments.

According to a county news release dated October 22, the lowered water levels will provide extra room for rainwater before it enters Ross Creek and Corte Madera Creek. This strategy aims to lower downstream water levels during heavy rainfall events.

Marin County Supervisor Brian Colbert addressed the urgency of the situation in the release. "For neighbors who have experienced flooding, another winter can bring real worry about their homes, businesses and families," Colbert said. Officials noted that a similar approach proved effective during an October 2021 storm by capturing runoff that would otherwise have flowed into local creeks.

Marin Water will manage the pumping schedule and monitor both weather patterns and reservoir quality. The agency retains the authority to determine the final depth of the reservoir and the exact date to cease pumping, balancing flood mitigation needs with the requirement to maintain a reliable drinking water supply.

While the additional storage capacity is expected to mitigate some flooding, officials stated that the risk in San Anselmo and Ross will not be eliminated. Residents and local businesses are advised to continue their standard preparations for winter storms.