About 1,000 Clearwater River steelhead died Wednesday and Thursday after being trapped by a routine generator maintenance project at Dworshak Dam near Orofino, Idaho.
Dam workers rallied to save 511 of the big sea-run rainbows and return them to continue their spawning migration.
Dworshak staff, Clearwater and Dworshak hatcheries personnel and other local helpers worked until about midnight Wednesday and resumed their efforts early Thursday morning, according to U.S. Army Corps of Engineers officials.
The dead fish were salvage and donated to the Idaho Correctional Institution in Orofino and local food banks, which provided three workers to help filet fish and store them in ice.
Most of the fish were of hatchery orgin, but some were wild fish protected by federal law.
The Corps’ Walla Walla District Commander Lt. Col. David A. Caldwell is conducting an official investigation on this occurrence, which affected a species listed as “threatened” under the Endangered Species Act.