Wet February boosted snowpack, but promptness of spring runoff a deciding factor

Wet February boosted snowpack, but promptness of spring runoff a deciding factor

Source: Bozeman Daily Chronicle
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By Michael Wright Chronicle Staff Writer

A wet February improved snowpacks in river basins around southwestern Montana, and there’s still spring left to go.

The Natural Resources Conservation Service’s March 1 snowpack report showed river basins around southwest Montana are either near or above average for their annual snow-water equivalent. But there can always be more, and snowpack doesn’t typically peak until later in the spring, said Lucas Zukiewicz, a water supply specialist for the NRCS.

“We have another month, month and a half before we see what our peak snowpack is going to be like,” he said.

Zukiewicz said one of the keys for the snowpack to be used efficiently will be that spring unfolds in a more typical way than it has in the last few years, meaning more precipitation needs to arrive and runoff needs to wait a little while before it begins.

“The last two years we’ve seen snow start melting as early as March,” he said. “We want to keep it up there a little later.”

He said that when runoff begins early, the water doesn’t soak into the ground as well as it does when it begins later in the year.

The report said the Gallatin River basin’s snowpack is at about 98 percent of normal, but that number varies from mountain range to mountain range. The upper Gallatin range has fared well so far this year, as winter storms have brought the snowpack there up to 106 percent of normal.

The Hyalite and Bridger ranges are a slightly different story. The Bridgers came in at 95 percent of average, boosted slightly by February snows. The big storm that brought good powder to Bridger Bowl didn’t bump the snowpack all that much, however, as the snow wasn’t very dense, meaning it included more air than water. About 60 inches of snow were reported, but that amounted to about 2 inches of snow water equivalent, Zukiewicsz said.

South of the valley, the Hyalite range is hurting a little bit. Overall, the snowpack is listed at about 85 percent of average, but some snow monitoring sites recorded numbers as low as 70 percent of normal. Zukiewicz said that will be important as irrigators and the city of Bozeman look to the reservoir for water later this year.

“That ground can be made up, it just so far hasn’t come through for Hyalite,” he said.

Other river basins in this portion of the state are also doing well. The Madison clocked in with 113 percent of its normal snowpack, while the Jefferson was recorded at 103 percent of normal. Both were boosted by well above average snowfall in the Tobacco Root Mountains for February, where total snow set a monthly record.

Snow monitoring sites in the Beartooth Range and in Yellowstone National Park also set records for February snowfall, which bodes well for the upper Yellowstone River. The snowpack in that basin was recorded at 128 percent of normal.

Zukiewicz also said that the snow water equivalent on the upper Yellowstone is already near its average peak, which normally occurs in mid-to-late April. The average peak is about 17.1 inches of snow water equivalent, and Zukiewicz said the basin had recorded 16.8 inches as of Tuesday.