SANDPOINT — Flexible winter pool levels are underway on Lake Pend Oreille.

U.S. Army Corps of Engineers announced Friday that it is filling the lake to generate additional power. The lake will be raised about a foot over a 10-day period before releasing the water to generate power.

"As part of FWPO operations, people living or recreating around the Lake may see Lake Pend Oreille fluctuate from elevations 2051 to 2056 [feet], but this planned operation will not utilize the full allowed range," Leon Basdekas, Upper Columbia senior water manager for the Corps, said in an email announcing the move.

Flexible winter pool operations allow the generation of additional power for the hydropower grid when there is a power shortage, Molly McMahon, Lakes Commission executive director, said.

In the email, Basdekas said Bonneville Power Administration officials asked the Corps to conduct FWPO operations to store water so that it could be released at a later date for power generation.

The process to collect additional water in the lake began about 7 a.m. Friday and is expected to take about 10 days. Friday, the Corps lowered outflow at Albeni Falls Dam near Oldtown from 13,000 cubic feet per second to 8,000 CFS. Basdekas said the plan was to maintain the lower outflow for 10 days and store the water, holding the lake at between 2052 and 2053 feet. The additional water will be released at a later date to generate power, he said in the email.

As of Saturday afternoon, the level of the lake in Hope was 2,051.58 feet.

While not required, a winter pool elevation of 2,051 feet has been the norm for the past 10 years, allowing for 11.5 feet of stored water before it is lowered for flexible winter pool operations, McMahon said.

In sharing news of BPA's request for flexible winter pool levels, McMahon urged residents who might be out on the lake or on the Pend Oreille River to exercise caution.

"If you are recreating on the water during this time, please use caution and be aware of potential ice breakup and floating ice," she said.

McCahon said previously that the Pend Oreille River is one of the Columbia River's three tributaries. It makes a significant contribution to the entire Columbia River Basin, which creates pressures on waters in the Pend Oreille Basin. Balancing those uses is complex, said McCahon.

The Lakes Commission was formed, in part, to advise state officials on levels for Lake Pend Oreille. A natural lake, Pend Oreille was dammed in 1955 to hold and control the top 11.5 feet, with a typical summer pool of between 2,062 and 2062.5 feet and a winter pool for the past 10 years of roughly 2051 feet.

That water is manipulated with certain restrictions for power generation, recreation, fish and wildlife, and flood control.