Worumbo Hydroelectric Project: Downstream Fish Passage Damage and Repairs

Strategic Insights -

Brown Bear II Hydro, Inc., the Licensee of the Worumbo Hydroelectric Project, has submitted a report to the Federal Energy Regulatory Commission detailing a temporary change in the operation of the downstream fish passage caused by a partial blockage of entrance #3 to the fish passage. On May 12, 2025, a hydraulic boom used for clearing debris pulled the trash rack away from the face of the dam, preventing further clearing and causing a partial blockage of the entrance to the fish passage. The incident was reported to the National Marine Fisheries Service, U.S. Fish and Wildlife Service, and the Maine Department of Marine Resources, who suggested opening the other fish passage entrances to ensure safe downstream passage.

Key Takeaways:

  • The Worumbo Hydroelectric Project operates a downstream fishway between April 1 and December 30 of each year.
  • The project's downstream passage facilities include three entrance gates with trash racks, a connecting gallery, a downstream passage pipe, and a plunge pool with a depth controlled by two sectional gates.
  • Typically, only one of the three entrance gates, entrance #3, is opened during the required season.
  • The floodgates are also used to allow downstream fish passage at certain times.
  • The incident occurred on May 12, 2025, when a hydraulic boom used for clearing debris pulled the trash rack away from the face of the dam, causing a partial blockage of entrance #3.
  • The other two entrances to the fish passage were opened to accommodate downstream fish movement and prevent debris buildup.
  • Repairs to the trash rack and debris removal are estimated to take 1 day.
  • The incident was reported to the National Marine Fisheries Service, U.S. Fish and Wildlife Service, and the Maine Department of Marine Resources.
  • The agencies suggested opening the other fish passage entrances to ensure safe downstream passage.

Statistics:

  • 1 day estimated time for trash rack repairs and debris removal.
  • 3 entrance gates with trash racks at the Worumbo Hydroelectric Project.
  • 2 sectional gates control the depth of the plunge pool at the project.
  • May 12, 2025, date of the incident.
  • May 11, 2018, date of the Final Species Protection Order.

Sources:

  • Brown Bear II Hydro, Inc. (2025). Report of Downstream Fish Passage Damage and Repairs.
  • Species Protection Plan (SPP).
  • Federal Energy Regulatory Commission (FERC No. P-3428-ME).
  • National Marine Fisheries Service (NMFS).
  • U.S. Fish and Wildlife Service (USFWS).
  • Maine Department of Marine Resources (MDMR).