Record rains keep Flathead Lake near full pool

Flathead Lake is still bearing the brunt of record-breaking rainfall in October, and the lake’s elevation remains within a foot of full pool well after the seasonal draw-down typically begins.

In recent years, operators of Kerr Dam, since renamed “Séliš Ksanka Ql’ispé Dam,” have begun dropping the lake elevation at the beginning of October, after the end of the summer season. But that month coincided with drenching rains that broke records in several locations throughout the Flathead River Basin.

According to Energy Keepers, Inc., the corporation that’s been managing the dam since the Confederated Salish and Kootenai Tribes took over operations in 2015, the impacts have continued to trickle down from the headwaters throughout the month of November.

“November is turning out to be 242 percent of average, so we’ll have more water coming in than we did in October,” executive director Brian Lipscomb said, referring to total water flowing into the lake throughout the month.

Paired with higher-than-usual releases from Hungry Horse Dam upstream, the swollen waterways have kept the lake elevation close to its full-pool elevation of 2,893 feet above sea level by the end of November.

The surface had fallen to about 8 inches below full pool by Dec. 1, but that’s well above the elevation typical for the start of the winter months. The lake surface had dropped by about 3 feet by that point in every preceding year since 2008.

Lipscomb said that Energy Keepers will continue the draw-down that began over the past week, with a target of a 4-foot drop through December. Lake elevation records available from the U.S. Geological Survey only stretch back 10 years, but December has only seen a drop of 1.5 to 2 feet in each of the last seven years. Flathead Lake dropped about 3 feet during that month in 2008 and 2009.

Upstream flow rates in the Flathead River have begun returning to normal after a relatively dry November; Kalispell received less than half its normal precipitation for the month.

Still, all of the stream gauges listed on the USGS were registering above-average flows as of Dec. 1, ranging from 2 percent above average on the South Fork to nearly double the average flows on the North Fork.

“By the end of December, it’s looking like the inflows will be lower, still above-average, but low enough that we’ll catch up and then draft the lake about 4 feet through the end of December,” Lipscomb said, adding that colder temperatures will also help slow the incoming flow rates.

Outflows at Séliš Ksanka Ql’ispé Dam, meanwhile, are at an all-time high for this time of year and are running about 82 percent above the historical average, according to USGS data.

Reporter Sam Wilson can be reached at 758-4407 or by email at swilson@dailyinterlake.com.