Pacific Gas and Electric Company Submits Notification to Federal Energy Regulatory Commission for Hat Creek Hydroelectric Project

A temporary increase in water surface elevation at Cassel Pond, part of the Hat Creek Hydroelectric Project, occurred on June 11, 2025, due to an exciter critical trip caused by a high temperature alarm. The incident resulted in a brief elevation exceedance, which was promptly addressed by Pacific Gas and Electric Company (PG&E) through the removal of flashboards and returning the elevation to normal. The event was deemed a short-term deviation from the normal run-of-river operations and was reported to the Federal Energy Regulatory Commission (FERC) as required by the project's license.

Key Takeaways:

• The Hat Creek Hydroelectric Project's License Article 403 allows for run-of-river operations to be temporarily modified in the event of operating emergencies beyond the control of the licensee.
• On June 11, 2025, the Hat Creek No. 1 Powerhouse tripped offline due to an exciter critical trip, causing a temporary increase in water surface elevation at Cassel Pond.
• PG&E immediately dispatched an operator to initiate a spill by removing flashboards, which successfully returned the elevation to normal within 1.5 hours.
• A qualified biologist evaluated the incident and determined that the brief increase in surface water elevation and flow likely did not have significant adverse effects on aquatic biota in Cassel Pond.
• The incident was reported to FERC as required by the project's license, and PG&E does not consider it a deviation from the License.
• The incident highlights the importance of monitoring and emergency response procedures in place for the Hat Creek Hydroelectric Project.

Statistics:

• The water surface elevation at Cassel Pond exceeded the normal maximum elevation by 0.52 feet (from 3,208.30 feet PG&E Datum to 3,208.82 feet PG&E Datum) for an approximate duration of 1.5 hours.
• The Hat Creek Hydroelectric Project's License Article 403 requires PG&E to notify FERC of any temporary modifications to run-of-river operations within 10 days of the incident.
• The project's annual fish spawning rate was not significantly impacted by the brief elevation exceedance.

Sources:

• Pacific Gas and Electric Company, Notification to Federal Energy Regulatory Commission for Hat Creek Hydroelectric Project, June 16, 2025.
• Federal Energy Regulatory Commission, Hat Creek Hydroelectric Project, FERC No. 2661.
• Order Denying Request for Rehearing (102 FERC P 61,125), issued February 4, 2003.