Lake Pend Oreille’s water levels will fluctuate by as much as 5 feet this winter, allowing federal agencies more flexibility in managing electricity generation throughout the Columbia River hydropower system.
The Bonneville Power Administration wanted more latitude in managing the water in Idaho’s largest lake so it can be strategically released to respond to periods of peak power demand, such as a regional cold snap.
Lake Pend Oreille is impounded by Albeni Falls Dam. About 16 hours after the water flows over the dam, it reaches the reservoir behind Grand Coulee Dam on the upper Columbia.
In the past, Lake Pend Oreille’s winter lake level fluctuated by no more than a foot. BPA and the U.S. Army Corps of Engineers signed off Friday on the new plan, which calls for keeping lake levels at elevations between 2,051 and 2,056 feet above sea level. However, the daily rise and fall of lake levels can’t exceed 6 inches.
The decision on Lake Pend Oreille’s water levels comes after a two-year study of how fluctuating levels could affect shoreline erosion, wildlife habitat and boat docks.
Many local residents opposed the change.
The study said that poorly constructed docks could suffer damage, particularly when areas of the lake are frozen, but it said the risk isn’t expected to increase significantly compared with current conditions. The study also acknowledged that shoreline erosion is an ongoing problem and that the loss of submerged plant vegetation has reduced habitat for Lake Pend Oreille’s large population of wintering redhead ducks.
However, changes in winter water levels are expected to have only “incremental” effects on shoreline erosion and wildlife habitat, the study said.