Libby Dam spill increased; flooding at Bonners Ferry

The Daily Inter Lake

With reservoir inflows exceeding forecasts, the U.S. Army Corps of Engineers increased spills at Libby Dam even though the Kootenai River is flooding at Bonners Ferry, Idaho.

Flows from Libby Dam were increased to 55,000 cubic feet, with turbines running at full capacity of 24,000 cfs and the rest going over the dam's spillway.

Forecasts generated by the National Weather Service River Forecast Center are used by the Corps to make decisions on dam operations.

Throughout the week, the Corps maintained releases at 38,000 cfs in an effort to curb spilling water, which causes gas damage to fish below the dam, and potential flooding at Bonners Ferry.

But heavy rain boosted inflows to 49,000 cfs Thursday and by midnight, Lake Koocanusa had risen to within less than a foot of full pool.

Once at full pool, all inflows over the powerhouse capacity of 24,000 cfs must be released over the spillway.

As a result of the boosted spill, the Kootenai River was nearly a foot above the 1764.8 flood stage at Bonners Ferry, and the National Weather Service was projecting it to crest at 1766.4 by today.

Corps emergency management teams are on the ground providing technical assistance in flooded areas, a corps press release stated.

The Corps is assisting local emergency management officials in Bonners Ferry by strengthening levees and providing assessments on weakened structures, the release states.

In Montana, the Corps is working with local emergency management officials on identifying areas of concern.

The public is urged to be aware and take caution near the river during these higher flows. The water velocities are high and water temperatures are still quite cold. An added danger is debris accumulation along the river and possible stream bank erosion in some locations.