Hydraulic fluid leak from small hydropower plant quickly contained at Clearwater and Dworshak Fish Hatcheries

Hydraulic fluid leak from small hydropower plant quickly contained at Clearwater and Dworshak Fish Hatcheries

OROFINO – (Feb. 27, 2025) – In the early morning hours of Wednesday, Feb. 26, 2025, Idaho Department of Fish and Game staff at the Clearwater Fish Hatchery and Nez Perce Tribe Fisheries staff at the Dworshak National Fish Hatchery (NFH) noticed an oily sheen in the fish-rearing raceways. Those raceways hold over 6 million young steelhead and salmon smolts that are the future for the Clearwater River Basin under the U.S. Fish and Wildlife Service’s Lower Snake River Compensation Plan (LSRCP) and an additional 2 million juvenile steelhead reared in an U.S. Army Corps of Engineers-funded mitigation program at the Dworshak NFH.

Hatchery staff quickly identified that the fluid was leaking from the hydroelectric generator on the main water supply pipeline for both hatcheries. The fluid has been identified as a type of hydraulic oil that is not expected to be harmful to aquatic organisms. The leak was quickly stopped; an estimated 4.6 gallons left the facility.

Fishers along the shore of the North Fork Clearwater should use caution. Rocks along the riverbank may be slippery.  The spill has been identified as Chevron Clarity Hydraulic Oil AW32l. The Safety Data Sheet (SDS) for Chevron Clarity Hydraulic Oil AW32 states that skin contact is not expected to cause prolonged or significant irritation, but fishers should wash exposed skin with soap and water after potential contact. The SDS also states that ingestion and eye exposure aren’t expected to be harmful.

The hydropower generation unit at the fish hatcheries is owned and operated by the Idaho Water Resource Board (IWRB). The plant produces significant amounts of power for Clearwater County by harnessing the power of 40,000 gallons per minute of water needed to grow fish at the hatcheries. The U.S. Fish and Wildlife Service, Idaho Department of Fish and Game, and the Nez Perce Tribe work closely with IWRB to balance hydropower generation with fish-rearing demands for the water.

After the leak was detected, staff notified all of the agencies involved and began deploying available spill containment at the hydroelectric plant, the fish hatcheries, and in the North Fork of the Clearwater River. Additional resources and staff have been deployed to contain and clean up the hydraulic fluid and diagnose the cause of the leak. In addition, water samples were taken, and the young fish were put under constant observation.

Due to quick responses, no immediate fish losses have been observed, officials said. Biologists are working to implement conservation measures for federally listed fish in the area.

IWRB officials commended the hatchery staff and all state and federal agency personnel for taking quick action to stop and contain the leak.

The LSRCP is a Federal fisheries mitigation program and was congressionally authorized by the Water Resources Development Act of 1976, Public Law (PL) 94-587, to offset losses of fish and wildlife caused by construction and continued operation of the four lower Snake River dams.