News center
Articulate and proficient in their expertise.

Uncertainty over Potter Valley Power Plant, Eel River diversions continues to grow

Oct 03, 2023

An equipment failure has shut down PG&E's 1908 Potter Valley power plant indefinitely, adding uncertainty to the future of Eel River diversions that have augmented the Russian River for more than a century.

The transformer failure means that, even if the next few winters are rainy and wet, it still may not be possible to refill Lake Mendocino, which is at critically low levels, because supplemental water would be needed from the Eel River to do so.

An inoperable plant would also add substantial complexity to efforts by regional stakeholders to carve out a future for the project that would ensure continued water transfers critical to sustaining water supplies for well over 600,000 people in Sonoma and Mendocino counties.

"It's going to be a huge problem," said Beth Salomone, general manager of the Mendocino County Russian River Flood Control & Water Conservation Improvement District, which sells wholesale water to small municipal suppliers and agricultural users in the upper Russian River.

Turbines in the 1908 plant must be running for maximum water transfers through the milelong pipeline that connects the Eel River and the Russian River's East Fork on either side of a mountain.

Though some water can be sent past the plant through a bypass channel, the capacity is only half the volume that could otherwise flow through, officials said. Pacific Gas & Electric is talking about diverting far less water even than that, according to Potter Valley rancher Janet Pauli, chairwoman of the Mendocino County Inland Water and Power Commission.

In addition, PG&E could decide not to invest in costly, time-consuming repairs at all, since it's preparing to give up its license for the small, aged plant anyway. Spokesman Paul Moreno said it's likely to be months before an evaluation is complete.

The power plant had been offline for months because too little water was available to draw from the Eel River to operate it, Moreno said. Diversions from the Eel River are down to about 10 cubic feet per second, compared to closer to 270 cfs when the power plant is generating electricity.

But replacing the transformer bank comes with a cost of $5 million to $10 million and would take 18-to-24 months, according to early estimates, Moreno said.

That means the plant would remain offline through the next two winters even if PG&E were to invest in replacing the damaged equipment.

And if it doesn't, the plant — the very reason the Russian River doesn't run dry most summers — becomes just another hunk of junk and the diversions that power it a big question mark.

"There's not a lot of answers right now," said Don Seymour, principle engineer with the Sonoma County Water Agency.

Revelations about the damaged transformer bank are just the latest setback for coalition partners committed to what's called a "two-basin solution" once PG&E relinquishes the plant.

The Two-Basin Solution Partnership — the Sonoma County Water Agency, the Mendocino County Inland Water and Power Commission, the Round Valley Indian Tribes, Humboldt County and Cal Trout — notified federal energy regulators it wanted to license the plant itself in January 2019, days after PG&E said it no longer wanted to.

The coalition's motive is to ensure wintertime water deliveries through Potter Valley to the East Branch of the Russian River and on into Lake Mendocino. It also seeks to enhance Eel River fisheries by improving access to the river's upper reaches, which are currently blocked off by Scott Dam, which impounds Lake Pillsbury.

The dam was built in 1922 to store high, wintertime flows and has allowed for more regular, even releases of Eel River water downstream. But anglers and conservationists have long called for it to come down because of its impact on fish spawning and habitat.

Regional stakeholders have struggled to identify funding to cover what North Coast Congressman Jared Huffman said was an estimated $18 million in studies and evaluations needed to put together a plan to submit to federal regulators to take the process further.

A September request for postponement of due dates and revisions to the application schedule was denied, throwing stakeholders up against an April 14 deadline that most agree would be almost impossible to meet.

In the meantime, disclosures that PG&E may no longer have a functional plant could render the re-licensing issue moot, officials said.

"If that were to occur it would be absolutely new territory for us," Pauli told the Mendocino County Drought Task Force at a recent meeting.

Huffman, D-San Rafael, spearheaded the Two-Basin Solution and said recent developments could show the partners a cleaner, faster way to reach their goals without having to acquire a license for a power plant that is operating at a $9-million-dollar-a-year loss — the very reason PG&E wants rid of it.

Allowing PG&E to pursue license surrender and decommissioning of the power plant adds risk to downstream users but may mean corporate funding picks up the cost of advance studies otherwise would be borne by coalition partners.

"They wanted to take over the FERC (Federal Energy Regulatory Commission) license, and they wanted to run this as a hydroelectric project. But I will tell you I’m really encouraged by the way the stakeholders have held together around this set of principles and this concept of a two-basin solution and, in a strange way, this may be a faster and easier way to get there."

You can reach Staff Writer Mary Callahan at 707-521-5249 or [email protected]. On Twitter @MaryCallahanB.

Environment and Climate Change, The Press Democrat

I am in awe of the breathtaking nature here in Sonoma County and am so grateful to live in this spectacular region we call home. I am amazed, too, by the expertise in our community and by the commitment to protecting the land, its waterways, its wildlife and its residents. My goal is to improve understanding of the issues, to find hope and to help all of us navigate the future of our environment.

Environment and Climate Change, The Press Democrat