2025 Minimum Instream Temporary Flow Amendment Request

Updated 4/16/25:

On February 14, 2025, PG&E submitted a temporary license flow amendment (previously referred to as a temporary flow variance) to the Federal Energy Regulatory Commission (FERC) for the Potter Valley Project 2025 operations.

PG&E requests a temporary variance of its minimum flow requirements at two project locations.  Due to seismic risk at Scott Dam, PG&E has elected to leave the spillway gates at Scott Dam open indefinitely, thereby reducing the storage capacity in Lake Pillsbury by approximately 20,000 acre-feet to 56,000 acre-feet water storage.  PG&E also states that there is a high potential for bank sloughing and ensuing dam safety and operational constraints should the reservoir recede to a pool level of between 5,000 and 12,000 acre-feet, with 12,000 acre-feet becoming the planning minimum for water management. 

To preserve water storage in Lake Pillsbury and conserve cold water for downstream aquatic resources, PG&E proposes to release flows below Scott Dam (as measured at gage E-2) to be consistent with a critical water year type minimum flow of 20 cubic feet per second (cfs).  However, actual releases would be closer to the minimum facility limitation of 35 cfs from the low-level outlet.  In addition, PG&E would reduce minimum flows in the East Branch Russian River (as measured at gage E-16) to match the dry water year minimum flow requirement of 25 cfs with the flexibility to further reduce flows to the critical water year requirement of 5 cfs, depending on water availability, safety concerns, and water temperature conditions in the Eel River.  After September 30, 2025, PG&E would resume the dry water year flow release of 25 cfs.  In addition, PG&E requests that compliance with the minimum flow requirement in the Eel River below Cape Horn Dam (as measured at gage E-11) be modified to a 24-hour average instead of an instantaneous requirement to allow for a tighter compliance buffer. 

PG&E's request also includes provisions for water temperature and biological monitoring, environmental mitigation, and monthly consultation throughout implementation of the proposed variance.  PG&E requests that the variance begin immediately upon FERC approval and conclude when Lake Pillsbury storage exceeds 36,000 acre‑feet following October 1, 2025, or is superseded by another variance or license amendment.

On April 16, 2025, FERC opened the comment period on PG&E’s Application for Temporary Variance of Flow Requirements. With this notice, FERC is inviting federal, state, local, and Tribal agencies with jurisdiction and/or special expertise with respect to environmental issues affected by the proposal, that wish to cooperate in the preparation of any environmental document, if applicable, to follow the instructions for filing such requests.  Cooperating agencies should note the Commission's policy that agencies that cooperate in the preparation of any environmental document cannot also intervene. Deadline for filing comments, motions to intervene, and protests is May 16, 2025. More information on how to file comment can be found in the document linked below:

Comments on the Flow Variance: