Editor's note: The attached video originally aired in December 2018.

A generator failure at a Pierce County hatchery that led to the death of millions of Chinook salmon fry was caused by a loose or cracked connection with the battery, according to a state report released Monday.

The Washington State Department of Fish and Wildlife investigation, which was conducted by outside contractors, found the poor connection could have been detected and repaired “under normal conditions” if Minter Creek Hatchery staff routinely tested and inspected the generator.

“I believe Minter is an isolated incident, but I’ve asked staff to take additional precautions to keep hatchery generators in good condition,” Kelly Cunningham, acting assistant director of WDFW’s fish program, said in a statement.

A windstorm knocked out power at the hatchery on December 14, 2018, and the hatchery’s generator wouldn’t start. The department initially reported it lost about 6.2 million Chinook salmon fry, but later revised that number to 4.1 million fish.

Three WDFW employees have been disciplined for not keeping the generator in working order, according to the department.

Log books at the hatchery showed the generator equipment hadn't been inspected for 67 days before the failure, according to the investigation. WDFW says it has told hatchery managers statewide to increase generator testing and will ensure hatchery staff are trained on generator operations.

Since the incident, WDFW has received federal approval to move 2.26 million excess fish from six other hatcheries to Minter to offset the loss.

RELATED: Hatchery changes aim to increase number of salmon in Puget Sound for orcas

Back in December, the deaths sparked concern among fishermen and orca advocates, as salmon runs were already predicted to be low this season.