SANDPOINT — The chorus of voices calling for further study of a Bonneville Power Administration proposal to fluctuate Lake Pend Oreille’s winter pool is growing.

The U.S. Army Corps of Engineers is considering a BPA request to manipulate the lake level with a 5-foot range this winter for power generation and downstream water management purposes.

But the proposal has sparked concern in Idaho that variations in the winter pool could exacerbate shoreline erosion, cause sedimentation in near-shore areas and harm docks, water intakes and other infrastructure.

The Pend Oreille Basin Commission has strong objections to the BPA proposal and has rallied the support of four Panhandle lawmakers in its push for further study before a decision is rendered.

Corps officials have indicated they intend to judge the BPA proposal against an existing environmental impact statement on Albeni Falls Dam operations. A decision is expected this month.

However, the most recent EIS on dam operations the basin commission is aware of was conducted more than a quarter century ago.

“There’s just too many unknowns for anybody to be comfortable with this. The environmental impact statement from 1983 doesn’t seem like it’s going to be adequate or appropriate,” said the basin commission’s Kate Wilson.

Representatives George Eskridge and Eric Anderson, in addition to Sens. Shawn Keough and Joyce Broadsword agree.

“We believe this information is outdated and that there is more recent information available on potential environmental and economic impacts that should be evaluated and incorporated in an updated environmental document before any decision is made to change the operations of Albeni Falls Dam,” the lawmakers said in a Dec. 23 letter to the corps.

The basin commission is asking the corps to turn over all documents directly affecting dam operations.

The BPA proposal is also cause for concern downstream, according to Pend Oreille County Public Utility District No. 1 in eastern Washington.

The district operates the Box Canyon Dam near Metaline Falls, Wash. The dam is a run-of-river facility with no storage capacity and is currently upgrading one of the dam’s four turbines

If downstream flows exceed 21,000 cubic feet per second, as is contemplated in one instance of the variation proposal, it would require the utility district to spill excess water, which poses a threat to equipment, structures and personnel when temperatures dip below freezing.

The spillage would reduce power generation opportunities and the district estimates that it would result in losses of $3,000 per day for each thousand cfs over 21,000 cfs.

“This would put an even greater economic burden on an already stressed region,” Charles O’Hare, chief operating officer of the PUD, said in a Dec. 11 letter to the corps.

Anderson, a Priest Lake lawmaker, said the motivations influencing the BPA request remain vague. Anderson also serves on the Northern Lights energy co-op board and keeps tabs on power demands in the region and sees no pressing needs.

“The way it was left with us is they really didn’t tell us why they have to do it,” he said. “I know they were talking about some peak energy storage to release later on, but I don’t know why you would need to do that if there’s no great demand right now.”