Rain Delays Dam Grouting

Nearly a week of rain in the Clearwater River drainage caught the U.S. Army Corps of Engineers with its turbines down.

That sent Dworshak Reservoir’s level surging upward by nine feet. Dworshak Dam may start spilling water to continue a maintenance project which is currently under water.

Too few turbines in operation at Little Goose Dam downstream on the Snake River led the Corps to store water behind Dworshak Dam when heavy rains started appearing last week.

The rising water level shut down work at the foundation of the Dworshak Dam to seal cracks in the bedrock, a leak that was bothersome but not a safety hazard, Corps officials said. The agency drew Dworshak’s level down to 100 feet below full in October to reduce the amount of water leaking from the cracks to make the grouting easier.

The main problem now is getting the water out of Dworshak so the sealing project can continue without spilling too much water. The turbine problems at Little Goose Dam meant the Corps could not release all the water flowing into Dworshak without spilling at Little Goose and violating dissolved gas standards.

The gas can cause a condition in the fish similar to divers’ “bends.”