As many as 6.2 million juvenile Chinook salmon died last weekend when a windstorm cut power to the Minter Creek Hatchery in Pierce County and the facility’s backup generator failed.

The juvenile salmon were in incubators at the Minter Creek Hatchery operated by the Washington Department of Fish and Wildlife. The pump that supplies water to those incubators stopped working when both the main power and a backup generator failed.

WDFW staff tried to start the generator and attempted to provide water to the incubators using other methods, but those efforts were mostly unsuccessful, said Eric Kinne, WDFW hatchery division manager.

“This is a devastating loss,” Kinne said. “The department is conducting an analysis to determine the root cause of what went wrong so that we can improve procedures at Minter Creek and our other hatcheries to help ensure this doesn’t happen again.”

An inventory of the fish lost includes:

• 4.2 million juvenile Deschutes fall Chinook.

• 1.5 million juvenile Minter Creek fall Chinook.

• 507,000 juvenile White River spring Chinook.

Kinne said the department was raising the White River spring chinook as part of the state’s early efforts to provide more food for southern resident orcas, which are listed as endangered both federally and in Washington. The Deschutes and Minter Creek fall chinook were part of WDFW’s ongoing hatchery operations that support state fisheries, not new production for orcas.

Other fish – including roughly 4.2 million chum salmon and 2 million coho salmon — being held at Minter Creek Hatchery survived the power outage.

WDFW is determining whether fish from other facilities can replace some of the juveniles lost at Minter Creek Hatchery, which is located in Gig Harbor. The Chinook were scheduled for release in May or June 2019. Chinook typically returns to their natal streams to spawn after three to five years in marine waters.

The department operates 80 hatcheries across Washington and raises approximately 68 million Chinook annually.