Pacific Gas and Electric Company's Compliance Report on Fish Passage Facility Operations at Cape Horn Dam

Strategic Insights -

The Pacific Gas and Electric Company (PG&E) has submitted a document to the Federal Energy Regulatory Commission (FERC) regarding their compliance with fish passage facility operations at Cape Horn Dam, part of their Potter Valley Hydroelectric Project. The report provides a follow-up to the deviation report submitted in April 2025, detailing actions taken to protect the fish passage facility during storm events in March 2025. The report highlights the successful operation of the fish hotel sediment doors and the lamprey passage system, as well as the continuous tracking of adult salmonid and Pacific lamprey migration through the fish ladder.

Key Takeaways:

  • In April 2025, PG&E reported that they had closed the fish hotel sediment doors during storm events in March 2025, and committed to provide a follow-up report detailing actions to protect the fish passage facility.
  • Table 1 details the dates, times, flows measured at Gage E11, and actions taken at the fish passage facility in April 2025, showing that the fish hotel sediment doors were opened on April 10, 2025, and the lamprey tubes were returned to service on April 11, 2025.
  • A qualified biologist regularly assessed the fish ladder during the period when the sediment exclusion doors were closed, finding no lamprey attempting to migrate through the fish ladder.
  • The sediment exclusion doors were opened on April 11, 2025, and the lamprey passage system returned to service on April 11, 2025.
  • A video monitoring system continuously tracks adult salmonid and Pacific lamprey migration through the fish ladder, with daily counts of adult and subadult steelhead and adult Pacific lamprey migrating through the fish passage facility.
  • Figure 1 shows daily counts of adult and subadult steelhead and adult Pacific lamprey migrating through the fish passage facility and average hourly flow at E11 in April 2025, indicating successful operation of the fish passage facility.

Statistics:

  • Flows measured at Gage E11 in April 2025 ranged from 1720 to 1498 cfs.
  • The fish hotel sediment doors were closed for a total of 10 days in April 2025.
  • The lamprey passage system was disconnected on March 10, 2025, and returned to service on April 11, 2025.
  • No lamprey were observed attempting to migrate through the fish ladder while the sediment exclusion doors were closed.
  • The sediment exclusion doors were opened on April 11, 2025, and remained open for the remainder of April.

Sources:

  • Pacific Gas and Electric Company's document submitted to the Federal Energy Regulatory Commission (FERC) on May 14, 2025.