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A Once-in-a-Generation Chance to Own Our Water Future

For more than a century, water from the Eel River has flowed through PG&E’s Potter Valley Project into the Russian River watershed, filling Lake Mendocino, supporting farms in Potter Valley, and supplying homes and businesses across Mendocino, Sonoma, and Marin counties. PG&E has decided it no longer wants to operate the Potter Valley Project and has filed a plan to decommission it, including removing Scott Dam and Cape Horn Dam. That wasn’t a decision made by Mendocino County or our local water districts, but our responsibility now is to make sure water continues flowing to our communities and that the infrastructure controlling it stays in local hands, not in the hands of an outside investor.

Some have asked why we don’t just fight to keep Scott Dam and Lake Pillsbury in place. I understand why people ask that question. Lake Pillsbury is important to many people, and losing a lake that has existed for more than 100 years is a big change. But the reality is more complicated than simply deciding that we want to keep it. PG&E owns the project and has decided it no longer wants to operate it. We can’t force a private company to continue maintaining an asset it no longer wants, and no other public agency or private company stepped forward to take over the existing project. But PG&E is only one part of this conversation. The Eel River has its own communities, tribes, fisheries and environmental interests that have to be part of any solution. Tribes along the Eel River have advocated for restoration of the river and its fisheries for generations, and whatever comes next has to recognize that the Russian River watershed depends on this diversion while the Eel River watershed has legitimate interests of its own.

That is why I don’t think framing this as “save Lake Pillsbury or lose our water” is accurate or helpful. Those aren’t our only two choices. We looked at whether taking over the existing project was realistic, but the estimated costs to repair the dam, address fish passage, relicense the project and operate it long term were in the hundreds of millions of dollars. No other entity stepped forward willing to take that on either. Even if someone had, there would still be major questions about fish passage, environmental requirements, tribal interests and whether the project could successfully be relicensed for another generation. The more realistic path is to recognize where this process is headed and make sure Mendocino County isn’t left without a reliable water supply when PG&E’s project is gone.

That is what the Mendocino County Inland Water and Power Commission, or IWPC, has been working on. IWPC is made up of the Mendocino County Water Agency, City of Ukiah, Redwood Valley County Water District, Potter Valley Irrigation District and Mendocino County Russian River Flood Control and Water Conservation Improvement District. IWPC has been working alongside the Round Valley Indian Tribes, Sonoma Water, Humboldt County, the California Department of Fish and Wildlife, Cal Trout and Trout Unlimited to create a plan that recognizes both watersheds. The goal is pretty simple to understand even if getting there is complicated: restore a free-flowing Eel River while maintaining a reliable diversion into the Russian River watershed.

Once the existing PG&E system is gone, having the legal ability to divert water is only part of the equation. We also need infrastructure to physically move that water. That is the purpose of the New Eel-Russian Facility, or NERF, being developed by the Eel-Russian Project Authority. This is an important point that sometimes gets missed in the public conversation: removing Scott Dam does not mean we are simply shutting off Eel River water to the Russian River. NERF is being designed specifically so seasonal diversions can continue after PG&E decommissions its project.

Recently, the region reviewed 13 years of water data to better understand what that future could look like. The modeling showed water would have been available for diversion through NERF in every year studied, including the severe drought year of 2021. It also showed us where the next big challenge is: storage. Under the future system, more water could be available during wet winter periods than we currently have the ability to capture and store. We already know Lake Mendocino has limited storage capacity. To me, that isn’t an argument against NERF. It is an argument for doing the storage work at the same time.

That is why IWPC has prioritized several storage strategies alongside NERF, including increasing storage at Lake Mendocino through modernization of Coyote Valley Dam, groundwater storage in Potter Valley, additional pond storage for local growers and opportunities for new surface storage above Lake Mendocino. If water is available during wet months, we need to get better at capturing it so it is there during our dry summers, for our communities, our farms, our environment and when we need water most.

There is another part of this that is really important to me: local control. For more than a century, PG&E has controlled the infrastructure that determines whether this water moves from one watershed to the other. We now have an opportunity for a public agency representing the communities that actually depend on these watersheds to own and operate the future diversion instead. That doesn’t mean every interest will always agree. Mendocino County, Sonoma County, the Round Valley Indian Tribes and the communities along both rivers do not all come to the table with exactly the same priorities, but that is why working together is so important.

We did not choose the timeline PG&E put us on, and we do not get to make decisions for the Eel River watershed by ourselves. What we do get to decide is whether we spend the next several years fighting to preserve a century-old system that no one has stepped forward to own, or whether we build something that can actually work for the next generation. For me, that means protecting our diversion, expanding our storage, respecting the interests of both watersheds and making sure our future water infrastructure stays in local public hands. This is our once in a lifetime chance to own our water future.

Mo Mulheren is the Second District Supervisor for the County of Mendocino and serves as the County’s alternate commissioner on the Mendocino County Inland Water and Power Commission.

Maureen Mulheren

NEW MODELING CONFIRMS WATER WILL BE AVAILABLE THROUGH FUTURE NEW EEL-RUSSIAN DIVERSION

Analysis reinforces the region’s path forward with new diversion infrastructure, secured water rights, and expanded storage to protect long term water reliability following PG&E decommissioning of Potter Valley Project. (Ukiah, CA – August 11, 2026). New water supply modeling confirms that water would be available for diversion from the Eel River into the Russian River watershed through the proposed New Eel-Russian Facility, including during drought years. The analysis, completed by Sonoma Water, evaluated how water transfers would have occurred in past years, under the diversion rules that have now been established in the 2025 multi-party Water Diversion Agreement.  “The modeling confirms that the New Eel-Russian Facility can work, and that water will truly be available for diversion, every year, including during drought years,” said Dave Koball, Alternate Commissioner for Mendocino County IWPC. “It also reinforces why diversion and storage must be pursued together. Additional storage will allow us to capture more water when it is available and preserve it for the farms, businesses and communities that need it later in the year.”

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WORK CONTINUES TO PREPARE FOR THE NEW EEL RUSSIAN FACILITY AT THE POTTER VALLEY PROJECT

Engineering work and collaboration on potential storage strategies show progress for protecting long-term water supply reliability.  Refer to the ‘Stay Informed, Updates by Topics’ tab for the full story.