PG&E Requests Variance to Conduct Work on Powerhouse

Pacific Gas and Electric Company, owners of the Potter Valley Project (PVP), are beholden to regulations of the Federal Energy Regulatory Commission (FERC). When PG&E needs to alter management of the project, including changes to water releases which affect stream flow, they must first receive approval from FERC. The below excerpt from the Press Democrat describes the recent variance request. Read the full article here.

A plan by PG&E to temporarily shut down a powerhouse that feeds water from the Eel River to the Russian River may cut into consumer supplies this winter by further reducing the amount of water coming into Lake Mendocino.

Already, the reservoir, the second-largest on the Russian River and the main surface supply for residents and agricultural users north from Healdsburg to the Ukiah Valley, is at historically low levels. Parched by more than three years of drought, it currently sits at just more than 33 percent of normal.

Water managers say that supply could be further strained by PG&E’s proposal to unplug its Potter Valley Powerhouse for 3½ months to replace two massive valves in the penstocks and make additional repairs to keep the powerhouse operational.

PG&E says the repairs are needed to prevent the aging facility from breaking down.

But depending on the kind of rainfall the region experiences this season, the impact of PG&E’s plans on the local water supply could be “pretty significant,” said Pam Jeane, assistant general manager of the Sonoma County Water Agency.

As much as 70 or 80 percent of the normal actual diversions are at stake — upwards of 25,000 acre feet over the course of the repair period, according to Water Agency personnel. That’s almost as much water as is currently held in Lake Mendocino, or close to half of the nearly 55,000 acre feet the Water Agency delivered last year to its 600,000 customers in Sonoma and northern Marin counties, though that supply comes from a variety of sources, including the much larger Lake Sonoma.

Federal regulators hold authority to approve the shutdown and are expected to do so, pending a 30-day comment period underway.

But the power company has pledged to maintain minimum diversions to ensure some continued boost of wintertime flows through the Russian River’s East Fork and on to Lake Mendocino.

It would use a dry creek channel near the powerhouse to divert at least 20 cubic feet per second into the Russian River, though PG&E says it hopes it will be closer to 23 cfs. That’s actually more than the average amount of water put through the plant last winter because of severe dry weather after December, said Alvin Thoma, director of power generation and hydropower licensing for PG&E.

“But it is still substantially less than would flow during this time period if we were not doing the work,” he said.

Decent rainfall in the Russian River watershed would be enough to fill Lake Mendocino and ensure sufficient water supply next year even without supplementation from the Eel River, water managers say. Abundant rain would potentially force releases from Lake Mendocino for flood control purposes anyway, nullifying any water supply impact from the Potter Valley work.


The Sonoma County Water Agency and County of Sonoma (collectively “Sonoma”) have filed comments that request (among other things) for the flows to be “made up” at a later date, for PG&E to meet semi-annually with their agency to discuss future plans for the project, and for PG&E to provide written written notice to Sonoma at least 90 days before filing any future requests with FERC that would reduce flows in the Russian River watershed.

Read for yourself Sonoma’s Motion to Intervene , and Protest and Comments.

Friends of the Eel River also filed comments stating that the decision to release “make up” flows after this repair work needs to be considered in a second variance request that includes public process. FOER comments also point out that the Sonoma County Water Agency does not have a water right for Eel River water not associated with operation of the PVP, and that it is not irregular for PG&E to provide very limited notice to water users impacted by variances – as happened in December of last year (more about variance requests in the last year here).

Read for yourself FOER’s Motion to Intervene.

Pacific Gas and Electric Company filed a response to both Sonoma and FOER. They make several points, one of which is to acknowledge that any future “make-up” flows greater than allowed for in their operating license would “require a variance supported by the various stakeholders and approved by FERC”.

Read for yourself PG&E’s Response.

Federal Energy Regulatory Commission issued an order approving the temporary variance for PG&E to conduct work on the PVP power house. Unfortunately FERC also sided with Sonoma, in that they are requiring PG&E to consult with stakeholders (of which, Friends of the Eel River is excluded) and “to file with the Commission within 60 days of the date of this order, a detailed plan and schedule for compensatory flow releases to the East Branch Russian River, including the magnitude, timing, and potential impacts associated with the flow releases.”.

It is also worth noting that FERC uses the term “downstream users” to refer to water users outside of the Eel River watershed who benefit from Eel River water. Those who receive water from Lake Mendocino are outside of the Eel River watershed, and thus not downstream Eel River water users. By this poor-logic, all of central and southern California would be “downstream” of all neighboring water sources within and outside of the state.

Read for yourself FERC’s Order Approving Temporary Variance.