Sunday, January 29, 2023

Decommissioning the Potter Valley Project Is Off to a Rough Start


The Cape Horn Dam and Van Arsdale Reservoir on the Eel River an essential part of the infrastructure for the Potter Valley power plant [Photograph from CalTrout]

Decommissioning the Potter Valley hydro project is off to a rough start. There have been two developments in the ongoing saga of the Potter Valley hydropower project this week. The 20-year license has expired, but PG&E still owns and operates the project on an annual license. On Monday, PG&E submitted a rough schedule to surrender that license to the Federal Energy Regulatory Commission (FERC).

In a separate filing, PG&E argued that it should be allowed to continue operating the project under the biological protections that were attached to the license when it was issued in 2002.

The 100-year-old project consists of two dams and two reservoirs that impound water on the Eel River; and a diversion tunnel that sends Eel River water into the East Fork of the Russian River, eventually making up the majority of Lake Mendocino. At its height, the project was capable of generating 9.4 megawatts of power, but it’s not currently producing power due to a broken transformer. The project provides water that’s key to agriculture in the Russian River and has long been a hot-button issue for environmental organizations that argue it harms endangered fish in the Eel. 

On Monday, PG&E submitted a four-page proposal for a two-and-a-half-year timeline to surrender the license and decommission the project. The bulk of that time will be devoted to interacting with agencies and stakeholders as PG&E drafts more detailed documents. Environmentalists are pushing for a speedy removal of both dams. But PG&E spokeswoman Deanna Contreras said in an email, “We expect it will take many years following PG&E’s submittal to FERC for a Decommissioning Order to be issued.” She added that PG&E still plans to replace the broken transformer, expecting it to amortize over a period of five years. Replacing the part could take up to two years.

The Russian River at the base of Frog Woman Rock provides water to nearly half a million in Mendocino and Sonoma Counties [Picture by Matt LaFever]

Water-using stakeholders include the Potter Valley Irrigation District, which has contractual rights to some of the water; and the City of Ukiah, which has pre-1914 rights to water further down the East Fork, before it flows into Lake Mendocino. The Sonoma County Water Agency claims the bulk of the water in the lake. The Russian River Flood Control and Water Conservation Improvement District also has water rights to the lake, and sells wholesale water in Mendocino County. All these interests are currently in suspense about whether or not PG&E will be allowed to drastically reduce the water flowing through the diversion tunnel. PG&E has stated that one of its reasons for asking FERC to allow it to cut down on the flows is to preserve a cold-water pool for young salmonids in the Eel River.

But it’s not just environmental advocacy organizations that are concerned about the project’s impact on wildlife and the environment. Back in 2002, the National Marine Fisheries Service, or NMFS, wrote a Biological Opinion, laying out the measures that PG&E needed to take in order to comply with the Endangered Species Act. That opinion was incorporated into the license that was issued at that time, and which expired three months ago.

In March of this year, NMFS wrote a letter to FERC, saying that the project was causing take, or killing and harming fish that are listed under the Endangered Species Act, “in a manner not anticipated in the Opinion and from activities not described in the Opinion.” The letter goes on to say that the fish passage facility at Cape Horn Dam has not undergone the proper consultations regarding endangered species, and that none of the operations at the facility are covered in the 20-year-old opinion. NMFS wants to re-open consultations about the license in order to update and strengthen the environmental protection measures. This means that the license for the project would be undergoing amendments at the same time that it is being surrendered.

Lake Pillsbury in December 2020 [Photograph provided by Hannah Foster]

Within a few weeks of the NMFS letter, environmental advocates filed a notice of intent to sue PG&E under the Endangered Species Act, citing among other things that the fishway at Cape Horn Dam made the fish easy prey for river otters.

In a 16-page letter to FERC, PG&E wrote that NMFS doesn’t have evidence to back up its claims. PG&E also protested that NMFS failed to mention “any of the voluminous monitoring record covered by over 20 years of monitoring Project operations.”

Redgie Collins is the legal and policy director for California Trout, one of the organizations arguing that PG&E is in violation of the Endangered Species Act. He believes the biological opinion expired along with the license, and that it needs to be updated. CalTrout is threatening litigation as part of a pressure campaign to speed up dam removal and install other structures that will enable a winter diversion from the Eel to the Russian. “We have plenty of information that shows that these 100-year-old plus Eel River dams kill fish,” he declared. “And becasue they kill fish, and because we believe that the Biological Opinion has ended, that PG&E is required to either re-consult, or open themselves up to litigation that we are preparing, as we speak.”

Collins is inspired by plans to remove four hydropower dams from the Klamath River, which is scheduled to start next year. “It took them about 18 years to get to the point of the surrender process,” he said. “And once it kick-started there, the writing was on the wall for the eventual solution, which was worked on by a host of stakeholders, including tribal nations. Here we have a very similar path, and so we’re hoping that they use the existing information that we’ve put forth, and the removal plan, and try to beat that 30-month window. That’s our goal. It will never be quick enough for us.”

The Round Valley Indian Tribes have weighed in on the NMFS request to amend the license, saying the tribes support all the protective measures proposed by the service. The tribes are one of the few entities PG&E notified of its intent to reduce flows coming through the project, much to the chagrin of the Russian River water users, who argued that PG&E should have assembled a full drought working group before asking FERC to sign off on the reduction, or variance.

Collins says PG&E could have cut down the flows any time, without waiting around on FERC. “If they truly wanted to save listed species, they would have implemented the variance,” he said. “That cold pool will be functionally gone in a short period of time. We think just in a matter of weeks that cold pool will be drained based on the variance not being implemented.”

With ag users writing angry letters pleading for more water and environmentalists threatening lawsuits, one thing is clear: the initial outreach to stakeholders is not going well. And the decommissioning process hasn’t gotten started yet.



  1. 400,000 people depend on the water flowing through the Potter Valley Project. If this water supply is not maintained people from Potter Valley to the Golden Gate Bridge will lose a valuable water supply. This will cause Lake Mendocino to dry up and Ukiah Valley’s Wells to go dry. Along with every water rights holder all the way to Healdsburg. This is a disaster waiting to happen. They cannot cut this water supply off. It would devastate Mendocino county.

    • The Russian river has no water right to the Eel river, just water rights after the power plant.
      Years ago the Eel river went dry by fortuna and everyone blamed the cannabis farmers, but no one mentioned the giant diversion that goes south.
      Start storing water now, build off stream resorvoirs, buy water tanks.
      Also why does lake Sonoma never go dry?
      Because Sonoma county keeps it for recreation

      • The diversion amount averages 60,000 acre feet annually, less than 2% of the entire Eel River watershed. The area above Scott Dam is the hottest and driest portion of the watershed. If Scott Dam is removed and Lake Pillsbury is eliminated, the Eel River will return to its natural state and it will dry up intermittently and have skipping during drought years. Be careful what you wish for.

      • 60,000 acre feet is 19,554,000,000 gallons of water.
        If that’s not alot to you than maybe you have a better spot to store that water.
        I have personally walked the headwaters of the Eel and still saw water flowing in late summer. Might be hot, and dry but way more water then the Russian river has naturally.

      • And 60,000 acre feet is roughly 3% of the Russian River watershed, so its similarly insignificant to the Russian, funny how that works. If the area above the dam is so dry, then why build a dam there in the first place? Ditch the dam, do a winter diversion and store it in Lake Mendo. Solves everyone’s problems.

    • No one seems to actually know how many people benefit from the Eel River’s water. 400,000? 600,000? a million? I wonder why that is? Probably because no one has any idea. This is just fear mongering so grape growers can keep their free water. This isn’t about drinking water, its about cheap water for ag.

  2. Excellent article, Sarah!! What a mess of a situation. The water rights are divided among so many users, and there are so many agencies involved. We need to have secure water sources in place for the half a million people who depend on this water before decommissioning the dam. That should be the number one priority. I doubt if all the users downstream are aware of what is happening.

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Sarah Reith
Sarah Reith
Sarah Reith is a radio and print reporter working in Mendocino and Humboldt counties, focusing on local politics and environmental news.

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