photo credit: Kenneth James/CA Department of Water Resources
Lake Mendocino sits full behind Coyote Valley Dam on 16 January, 2023.

What's the shape of the North Bay's water?

This week, Sonoma County supervisors got their latest look in to future, as part of a regular 5-year update to California's Department of Water Resources.

They learned about the latest urban water management, UWMP, and water shortage contingency, WSCP, plans from Sonoma Water.

Sonoma Water's Paul Piazza, speaking to the board at their May 12th meeting, said, "projected water demands have decreased since the 2020 urban water management plan projection."

"The contractors projected reliance on their local supplies has actually increased," Piazza said. "Fortunately, the modeling results showed that there's adequate water supply to meet forecasted water demands through 2050."

The main concern for the medium term isn't whether or not faucets will run dry.

Water engineer Rene Guillen, and Piazza noted, the concern rather is about keeping water flowing through the Russian River if Lake Mendocino goes disastrously dry.

"It does maintain adequate supply during the average and multiple dry year scenarios, but it does not appear to have adequate supply from 2035 to 2050 under the single dry year run," Guillen said. "It's important to note that this would not impact Sonoma Water's ability to deliver water to its retail customers."

"I think this is where the headlines will come, to be honest with you," Piazza said.

Guillen said in a worst case scenario for Lake Mendocino, water conservation tactics and restrictions would almost certainly go in place early on to prevent the reservoir from running dry.

Operators at Lake Sonoma are also hoping to use the reservoir's water more strategically in the near future. The US Army Corps of Engineers is weighing up whether to implement the innovative FIRO program - Forecast Informed Reservoir Operations - at Lake Sonoma. FIRO is already used at Lake Mendocino.

The updated urban water management and water shortage contingency plans are available for public view on sonomawater.org.