Puget Sound Energy's Baker River Hydroelectric Project Experiences Instream Flow and Downramping Rate Deviation on July 16, 2025

Strategic Insights -

On July 16, 2025, Puget Sound Energy's (PSE) Baker River Hydroelectric Project experienced a deviation from the minimum instream flow (MIF) and downramping rate requirements. The incident occurred when Unit 3 tripped offline due to a loss of station service caused by a bird electrocution, resulting in a 3,200 cfs discharge drop to 564 cfs. The synchronous bypass valve (SBV) took 14 minutes to fully react, and Unit 4 failed to start automatically due to a stuck wicket gate. The deviation lasted for 14 minutes, during which the plant discharge was below the MIF requirement.

Key Takeaways:

  • The Baker River Hydroelectric Project has a minimum instream flow (MIF) requirement of 1,200 cfs between October 21 and July 31, as specified in settlement agreement article (SA) 106, aquatics table 1, in appendix A of the Project's license.
  • The MIF deviation occurred on July 16, 2025, when Unit 3 tripped offline and the synchronous bypass valve (SBV) took 14 minutes to fully react, resulting in a drop to 564 cfs.
  • Unit 4 failed to start automatically due to a stuck wicket gate, which is attributed to the gate getting stuck.
  • A repair plan is underway to address the slow response of the SBV, which may have been caused by corrosion in the valve.
  • The incident resulted in a 14-minute deviation from the MIF requirement, during which the plant discharge was below the required 1,200 cfs.
  • The Baker Aquatic Resources Group (ARG) was notified via e-mail regarding the potential downramping rate deviation, but no comments were received.
  • PSE has scheduled its annual outage for September to address the wicket gate issue and fix it by then.

Statistics:

  • The minimum instream flow (MIF) requirement at the Baker River Hydroelectric Project is 1,200 cfs between October 21 and July 31.
  • The discharge at Lower Baker was 3,200 cfs when Unit 3 tripped offline on July 16, 2025.
  • The synchronous bypass valve (SBV) took 14 minutes to fully react during the incident.
  • The 15-minute drop at the USGS gage downstream was 2.13 feet from 01:15 to 01:30.
  • The hour-to-hour drop was 1.47 feet from 01:15 to 02:15.
  • The lowest flow at the USGS gage downstream was 564 cfs.
  • The average of the 15-minute flow readings for the 01:00 to 01:45 hour at the Plant was 910 cfs, which is below the MIF requirement.

Sources:

  • Puget Sound Energy, INC. (2025) Federal Energy Regulatory Commission Mail Code: DHAC, PJ-12 888 First Street, NE Washington, DC 20426 Re: Follow-up Letter for a Potential Minimum Instream Flow and Downramping Rate Deviation on July 16, 2025.
  • 125 FERC P 62,064 (2008)