Project that supports Marin water supply gets $2M grant

Sonoma Water has received a $2 million grant to advance a plan for “fish-friendly” water diversion to the Russian River, one of the sources of Marin’s supply.

The U.S. Bureau of Reclamation announced the grant last month. The funding, which comes from the Bipartisan Infrastructure Law, will support a study of options for water diversion from the Eel River to the Russian River that will have the least amount of impact on salmon and steelhead trout.

U.S. Rep. Jared Huffman, a San Rafael resident, helped author the law and advocated for the grant to be delivered to Sonoma Water, also known as the Sonoma County Water Agency. The grant is part of the federal WaterSMART program that supports ecosystem restoration projects that provide regional and environmental benefits, including improved fisheries.

“This grant is a key part of the path forward,” said Huffman, a Democrat. “It provides the resources to develop a new and fish-friendly diversion that can maintain water reliability while we remove dams on the Eel River.”

The diversion project is part of multi-agency plan to purchase Pacific Gas & Electric Co.’s Potter Valley Project, a 110-year-old hydropower plant in Mendocino County. PG&E has decided to remove the Scott and Cape Horn dams in the Eel River and end the operations.

A coalition of organizations in Sonoma and Mendocino made a proposal to buy portions of the plant to enable water diversions.

Last month, the Sonoma Water board approved an agreement with the Mendocino County Inland Water and Power Commission to form the Eel-Russian Project Authority. The new entity will have the power to negotiate the purchase.

Pending successful negotiations, the new authority would have the capacity to own, construct and operate a new water diversion facility near the Cape Horn dam. Water diverted by the plant feeds into the Russian River watershed, which is a key part of Marin’s water portfolio. Electricity production is not part of the plan.

The new authority intends to preserve the water diversions and improve the fish passage. Its plan is called the New Eel-Russian Facility.

“Funding for this design work represents a major milestone in the progress toward a true regional solution for the Potter Valley Project,” said Sonoma County Supervisor James Gore, who also serves on the Sonoma Water board.

Sonoma Water has two main reservoirs, Lake Sonoma and the smaller Lake Mendocino. Diversions from the Potter Valley Project flow into Lake Mendocino.

Sonoma Water is also required to make dam water releases for the environment from Lake Mendocino as part of its state water rights. If the diversions from the hydropower plant end, more water might need to be released from Lake Sonoma, making water supply less reliable for its contractors, including Marin’s water agencies.

Sonoma Water officials said estimates show that Lake Mendocino would experience water shortages in eight out of 10 years, and run dry five out of 10 years, if diversions end. It’s estimated that would directly affect the drinking water supply for approximately 97,000 people, and the supply for some 600,000 would be less reliable.

The Marin Municipal Water District and the North Marin Water District support the proposal. The two Marin districts purchase Russian River water through Sonoma Water. The Russian River provides about 75% of the greater Novato area’s water supply and about 25% of the water supply for central and southern Marin.

“The lack of diverted water would cause tens of millions of dollars of economic damage per year, result in drastic conservation measures and increased water rates, curtail needed new housing, and increase the region’s vulnerability to droughts, wildfires and climate change,” Tony Williams, general manager of the North Marin Water District, wrote in a letter to PG&E in support of the proposal.

Paul Sellier, water resources director of the Marin Municipal Water District, said the grant is good news.

“We need to make sure that the environment is protected at the same time that we’re trying to manage our water supply,” Sellier said. “Sonoma Water is doing a good job leveraging all of their resources as they’re continuing to study the options to continue diversion.”

PG&E has included the authority’s proposal as part of its draft surrender application and decommissioning plan. PG&E will release a final draft surrender application in June. The final application is expected to be submitted in January 2025.