January 2026

PG&E’s Files Temporary Flow Amendment (Variance) to FERC for Potter Valley Project

On January 30th, PG&E filed a request for a Temporary Flow Amendment (Variance) for the Potter Valley Hydroelectric Project, Federal Energy Regulatory Commission (FERC) No. 77.

In 2023, PG&E determined that the seismic risk to Scott Dam is greater than previously understood and a 10-ft elevation restriction was placed on Lake Pillsbury reservoir indefinitely, reducing the water storage capacity from approximately 70,800 acre-ft (AF) to 52,600 AF for safety purposes. This loss of 18,200 AF of potential storage above the spillway further compounds the challenges to meet license-required flows. This has resulted in annual flow amendments (variances) that reduce minimum instream flow requirements to the East Branch Russian River during summer months.

This variance proposes a flexible management flow release strategy including the following:

• While Lake Pillsbury is spilling, Russian River diversions will follow license flows.

Once spilling ends:

• Diversions to the East Branch Russian River will initially be set at 25 cubic feet per second (cfs) with the exception of critical water years.
• The diversions will then be adjusted between 5 and 5 cfs to support management aims.

Management Aims:

• Prioritize facility safety with a storage target of 25,000 acre feet on October 1st and a minimum storage set at 12,000 acre feet.
• Preserve cool-waer pool/limit water temperature increases.

PG&E has requested this temporary variance be approved by FERC no later than May 25, 2026, which would be 2 full months prior to the 2025 approval and implementation. The variance would end when Lake Pillsbury storage is greater than 36,000 af after September 30th. FERC has not yet opened the public comment period. 

PG&E is also pursuing a license amendment for long term permanent flow requirement changes. A filing was made a year ago but PG&E provided notification that it would supplement the license amendment application, which is underway.

2026, 1-31 PG&E 2026 Flow Variance Request to FERC ( ).pdf