Albeni Falls Dam opens full bore

OLDTOWN — Albeni Falls Dam has transitioned to a free-flow operation to reduce the risk of flooding in the Pend Oreille Basin, the U.S. Army Corps of Engineers has announced.

The dam’s powerhouse was taken off-line on Tuesday and the dam’s spillway gates were raised.

The normal maximum elevation for April on Lake Pend Oreille is 2,056 feet above sea level and the corresponding channel capacity at the lake limits outflows to 56,000 cubic feet per second, the corps said. Since inflows are now surpassing 80,000 cfs, switching to free-flow operations allow the corps to keep the lake level as low as possible in April.

Under this operation, outflow from Albeni Falls was about 65,000 cfs on Tuesday afternoon and is expected to increase as the lake level rises. The current elevation of the lake, as measured by the Hope gauge, is 2,057 feet, according to the corps.

Action stage on Lake Pend Oreille is 2,062.6 feet. Action stage is the point at which water is over the banks, but not flooding manmade structures.

The lake’s flood stage is 2,063.5 feet, which is a foot above flood stage and 2 feet above Lake Pend Oreille’s summer pool elevation.

A corps flood team is responding to a request from Bonner County to stabilize an eroding outfall structure/access road on Lake Cocolalla.

With tributaries downstream from Libby Dam already swelling from snowmelt runoff, outflows from the dam were reduced from 13,400 cfs to 9,000 cfs on Thursday to reduce the flood risk to Bonners Ferry.

“The corps is continually monitoring conditions and will adjust Libby Dam outflows if necessary to compensate for high inflows downstream,” said Kevin Shaffer, a corps water manager.

The Kootenai River at Bonners Ferry is expected to reach approximately 1,762.3 feet, which is about 1.7 feet below flood stage, the corps said.