It’s a local sign of summer: Flathead Lake has effectively reached its full summer level a week early, following a month marked by swollen streams and faster-than-average snowmelt.

The license guiding the operation of Séliš Ksanka Ql’ispé Dam (formerly Kerr Dam) is enforced by the Federal Energy Regulatory Commission and requires dam operators to hold back enough water to bring the lake to full pool — 2,893 feet — by June 15.

The exact elevation can fluctuate slightly to allow wiggle room for rain events that could temporarily raise water levels. As of Tuesday morning, the lake’s surface elevation had reached 2,892.48 feet, according to the gauge in Polson.

Brian Lipscomb is the chief executive officer of Energy Keepers Inc., the tribal corporation that took over operation of the dam last year. He said Energy Keepers brought the level of the lake to within 1 1/2 feet of full pool by Memorial Day, when the license requires lake elevation to be within three feet of the maximum.

“The way the snowpack came off this year, we’re really on the backside of the runoff now,” Lipscomb said Tuesday. “Normally we’re in the middle of runoff right now.”

Last year, low snowpack levels in the river’s mountain headwaters and scant spring rain forced the dam operator at the time, NorthWestern Energy, to request a variance on its federal permit that would have extended the June 15 deadline. 

That request proved unnecessary, however, and Flathead Lake reached full pool on June 9, 2015.

While remaining snowpack and streamflow forecasts for the upper Flathead River drainage are below the historical average, they are a substantial improvement over last year.

The Natural Resource Conservation Service’s monthly report, released Monday, noted that while 25 to 50 percent of statewide snowpack typically remains in the mountains by June 1, Montana’s river basins had only 10 to 40 percent left.

The report predicts the Flathead basin’s streamflows through July will be 70 percent of average. An unusually warm spring has also brought the basin’s snowpack to 63 percent of normal as of Tuesday, despite above-average precipitation this year.