Water releases from Montana's Hungry Horse Dam have been bumped up over the last week to make room for runoff from a persistent, well-above-average snowpack.
On Monday, the Bureau of Reclamation took the unusual action of releasing water through the dam’s outlet works, bypassing the penstocks and turbines. The outlet works are lower in the dam structure than the spillway, which is fixed near the top of the dam.
“What’s happening lately, the weather stayed cold and we continued to get rainfall so that snowpack at higher elevations continues to increase,” said Dennis Philmon, the dam’s facility manager.
As of March 31, water releases from the dam were 8,800 cubic feet per second, and the flow has since been bumped to 10,700 cfs.
Philmon said increased releases will ensure plenty of storage room for the peak runoff. Hungry Reservoir’s water elevation is currently at 3,497 feet, well shy of the full pool elevation of 3,560.
The reservoir is just a few feet shy of the latest adjusted target elevation of 3,493 feet.
In comparison, during a relatively dry year two years ago, the dam was releasing just 1,890 cfs at the end of March 2009.
Philmon said the reservoir’s target elevation could be lowered if there continues to be above-normal rain and snow. Dam operators have to plan for cutting releases back considerably during peak runoff to compensate for higher flows on the other forks of the Flathead River system.
“We’re going to see the North Fork and Middle Fork ramp up high, so we have to hold back the flow during that period to minimize the flooding risk that those rivers pose,” Philmon said.
The Natural Resources Conservation Service on Thursday released the latest mountain snowpack numbers for the end of March.
Montana drainages west of the Continental Divide are at 121 percent of average, with the snowpack in the Flathead River Basin at 129 percent of average and the Kootenai Basin at 126 percent.
Both the Flathead and Kootenai basins have twice the amount of snow they did at this time last year.
And in some parts of the Flathead Basin, mountain snowpack is well above the combined average.
The Emery Creek automated snow measuring site above Hungry Horse Reservoir is at 140 percent of average. The Noisy Basin measuring site on the Swan Range has snow levels at 159 percent of average.
High elevation snow has been persistent if not increasing.
Both Flathead Valley ski areas have more than 12 feet of snow. There are 156 inches of settled snow on the summit of Whitefish Mountain Resort and 142 inches of snow at midmountain at Blacktail Mountain Ski Area.
Based on the snowpack, the Natural Resources Conservation Service predicts that stream flows in the Flathead Basin will be 36 percent above normal through July 31.