Flathead Rising

POLSON — The U.S. Army Corps of Engineers is projecting that Flathead Lake may rise four feet and exceed its full-pool elevation of 2,893 feet in early June due to high inflows of water.

“On May 23, the Corps advised PPL Montana, the operator of Kerr Dam, of new projections based on a combination of recent heavy rain, forecasted precipitation and snowpack runoff in the basin,” a PPL Montana press release states.

“In consultation with the Corps, we have been releasing as much water as we can throughout the spring at Kerr Dam to help control flooding,” said David Hoffman, director of external affairs for PPL Montana.

“But with this new information, we want to immediately inform our neighbors in the vicinity of Flathead Lake — around, upstream of it, and downstream of the dam — to make whatever preparations are necessary to protect docks, boats and property in the event of flooding.”

The dam recently has been releasing water at 34,000 cubic feet per second through its three generators and 11 spillways. As of Thursday afternoon, main rivers that empty into Flathead Lake were flowing at a combined 49,000 cfs. On Friday, Kerr Dam officials reported the outflow was approximately 38,500 cfs and elevation is 2,890.31 ft. Continual outflow increases of 1,000 to 2,000 cfs are made daily as channel restriction allows.

“We have a varying outflow depending on the elevation of the lake,” Hoffman said, explaining that restrictions in the river channel below the lake limit outflows. “The elevation of the lake determines how much spill there is.”

The lake is currently at 2,889.93 feet. At the full pool elevation of 2,893 feet, which is expected around June 5, Kerr Dam will be releasing about 55,000 cfs.

Hoffman said the current forecast is for the lake to reach 2,893.91 feet by June 15. At that point, the dam could be releasing up to 60,000 cfs.

For current levels at Flathead Lake, visit the U.S. Geological Survey’s website: http://waterdata.usgs.gov