Pacific Gas and Electric Company Requests Temporary Flow Modification for Rock Creek-Cresta Hydroelectric Project

Strategic Insights -

Pacific Gas and Electric Company (PG&E) has submitted a request to the Federal Energy Regulatory Commission (FERC) to modify the minimum instream flow (MIF) requirements for the Cresta bypass Reach of the Rock Creek-Cresta Hydroelectric Project. The modification is necessary to safely facilitate inspections of the Cresta Dam bypass radial gate, which are scheduled for October 22, 2025. PG&E is seeking to reduce the MIF from 200 cfs to 100 cfs to allow for safe diving inspections of the gate and verification of measurements for a cofferdam design.

Key Takeaways:

  • PG&E is requesting a temporary flow modification to reduce the minimum instream flow (MIF) from 200 cfs to 100 cfs for the Cresta bypass Reach.
  • The modification is necessary to safely facilitate inspections of the Cresta Dam bypass radial gate on October 22, 2025.
  • PG&E has initiated projects to replace the bypass gate hoist, upgrade controls, recoat and replace seals at the gate.
  • A cofferdam is being designed to minimize flow fluctuations downstream and isolate the work area to dry conditions during construction.
  • The instream flow release (IFR) valve located near the middle of the dam can pass a maximum of 130 cfs - 140 cfs, depending on reservoir elevation.
  • PG&E will follow the applicable ramping rate of 150 cfs/hr for the Cresta Reach.
  • The proposed flow modification is not expected to affect FYLF in the Cresta Reach, as the tadpoles will be metamorphosed into fully terrestrial young-of-year by October.
  • PG&E has consulted with the Rock Creek-Cresta Project Ecological Resources Committee (ERC) and provided a draft temporary flow modification request for concurrence.
  • The Bank of Water Quality Parameters will not be affected by the proposed flow modification in October.
  • PG&E will initiate informal consultation with USFWS regarding FYLF after receiving a delegation of authority to conduct informal consultation from FERC.

Statistics:

  • The reduction in MIFs from 200 cfs to 100 cfs will allow for safe diving inspections of the radial gate.
  • The cofferdam will be designed to minimize flow fluctuations downstream and isolate the work area to dry conditions during construction.
  • The maximum amount of water that can be passed by the instream flow release (IFR) valve is 130 cfs - 140 cfs, depending on reservoir elevation.
  • The ramping rate for the Cresta Reach will follow the applicable rate of 150 cfs/hr.
  • The current MIF releases in the months of October in the Cresta Reach are listed in Table 1.
  • The proposed minimum instream flow variance for October 22, 2025, is listed in Table 2.

Sources:

  • Pacific Gas and Electric Company, "Debbie-Anne Reese, Secretary Federal Energy Regulatory Commission," July 30, 2025.
  • United States Department of Agriculture-Forest Service, "4(e) Conditions," October 24, 2001.
  • Rock Creek-Cresta Project Ecological Resources Committee, "Agency Email Concurrence," May 21, 2025.
  • USFWS, "California Sportfishing Protection Alliance," August 12, 2025.
  • Plumas County, "American Whitewater," July 15, 2025.