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Rapid Melting in May Takes Significant Toll On State Snowpack

Flooding in Missoula along the north end of Tower Street, May 7, 2018.
Josh Burnham
Montana Public Radio
Flooding in Missoula along the north end of Tower Street, May 7, 2018.

This year’s record snowpack is rapidly melting, and it started earlier than normal.

As a result, there are still plenty of unknowns about Montana’s water supply outlook this summer.

Lucas Zukiewicz compares mountain snowpack to savings in a bank.

“We have a bunch of money in the bank, but we spent a lot of it really early,” he says.

Zukiewicz is a water supply specialist with Bozeman’s Natural Resources Conservation Service.

He says May’s well above-average temperatures and abundant sunshine took a big toll on Montana’s record-breaking winter snowpack.

“Typically in the spring we’ll see periods of these warmer temperatures and some sunshine, but the snowmelt has time to slow down. We’ll have some fronts comes through along with cooler temperatures which slows that down at night. What effective happened this year is that we just had the runoff building upon itself every day; we keep putting snowmelt into the rivers,” Zukiewicz says.

Which, he says, is what lead directly to this year’s extremely high river volumes and widespread flooding.

The Clark Fork River at Missoula is one of the most noteworthy examples.

“More water moved through that river during the month of May than typically moves for the entire runoff season,” Zukiewicz says.

The runoff season starts April first and continues through late September.

Zukiewicz says Montana’s low to mid-elevation snow is now gone. All that’s left to drive river flows is what’s left of the remaining high elevation snowpack, which in most cases remains at near to above-normal levels.

“We have an above-average forecast for many of our rivers across the state because we have that high-elevation snow cover, but June is going to be very telling when we look at what our flows look like later this summer,” Zukiewicz says.

If the accelerated rate of snowmelt continues, The NRCS says the need for summer precipitation will become increasingly important for water users that are not along a reservoir-controlled system.

The latest NRCS water supply outlook report can be found here.

Edward O’Brien first landed at Montana Public Radio three decades ago as a news intern while attending the UM School of Journalism. He covers a wide range of stories from around the state.  
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