Record February snowfall shores up Montana water supplySource: Great Falls Tribune
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Karl Puckett , firstname.lastname@example.org
Record-breaking February snowfall single-handedly has returned vital snowpack in Montana river basins to near or above-normal levels after two straight years of below-normal conditions caused water shortages in some areas.
“Looking very good,” Erling Juel, district manager for Fairfield-based Greenfield Irrigation District, which operates three reservoirs east of the Continental Divide, said of mountain snowpack.
Those reservoirs store water from the snow-melt charged Sun River used by grain growers and ranchers to irrigate 93,000 acres of cropland and pasture west of Great Falls.
Greenfields falls within the Sun-Teton-Marias basin, where snow-water equivalent was 133 percent of normal Wednesday.
That was tied with the Upper Yellowstone basin for the highest snow-water equivalent amounts in Montana.
Temps could reach 70 Saturday; flood advisory issued
“This is great news considering last year it was pretty much the lowest on record for most of the year for SNOTEL sites,” said Lucas Zukiewicz, a water supply specialist for the U.S. Department of Agriculture’s Natural Resources and Conservation Service.
NRCS provides mountain snowpack and precipitation information from a network of snow telemetry (SNOWTEL) sites that inform decisions on water supply management, flood control, climate modeling, recreation and conservation planning.
Records for gains in snow-water equivalent in February were set at 12 SNOTEL locations along the Continental Divide, according to NRCS.
Another six sites had their second-highest recordings of snow water in February.
Snow water is the amount of water that will be released from the snowpack when it melts.
A normal snow year could translate to a normal irrigation year for farmers and ranchers in Greenfields Irrigation District — as long as cooler temperatures control the melting of the copious amounts of snow and the release of the water into streams and rivers, Juel said.
“If it all comes off prematurely, before we’re irrigating, then we lose it because we can’t use it,” he said.
And in 2015 and 2016, because of the short supply of snow, the district cut its water allotment for the farmers and ranchers by 25 percent, Juel said. An allotment is the quantity of water for an acre of land.
“This year looks like we’ll have a full allotment,” Juel said.
Less water was one factor in a drop in the value of the district’s crops from $45 million in 2014 to $31 million in 2015 and $36 million in 2016, Juel said.
And last year, the irrigation season for Greenfields members was terminated in the second week of August.
The season usually continues until well after Labor Day, which falls on the first Monday of September.
The additional water will be a tremendous benefit for pastures, hay and alfalfa, Juel said. And it will boost soil moisture for wheat and barley growers.
Snowfall in February, which isn’t usually a big snow month, is fueling the snow water and the optimism heading into spring.
Between 6.6 feet and 8.3 feet of snow was recorded during the month at mountain SNOTEL sites up and down the Continental Divide, according to the NRCS.
As a result, almost every river basin in the state experienced substantial improvements in February in snow water equivalent with many now above normal or close to it.
East of the Divide, the river basins combined were 120 percent of normal for snow water equivalent as of March 1, and 96 percent west of the Divide.
“So we’re ahead of the curve,” Greenfield’s Juel said.
One of the February snow water record breakers is Flattop Mountain in Glacier National Park, which sits 6,300 feet, where a SNOWTEL has calculated the equivalent of 42.6 inches or 3.5 feet of water in the snow.
And 12.5 inches of that 42.6 inches of snow-water equivalent is the result of February snowfall. The 30-year normal for snow-water equivalent for February for Flattop is 5.3 inches.
“That’s pretty substantial if you think almost a third of the snow water for the year came during that one month,” Zukiewicz said.
Fisher Creek SNOTEL near Cooke City northeast of Yellowstone National Park received 10.9 inches of snow water in 12 days between Jan. 31 and Feb. 11. So much snow fell it prompted the first “extreme” avalanche warning for the area.
The exception has been the Big Belt and Little Belt mountains, which haven’t seen the snowfall that’s accumulated in other parts of the state. But there’s time for them to recover, said Zukiewicz, noting that March, April and May are usually big precipitation months. Snowpack usually peaks in mid-April.
Due to the abundant snowfall, the state already has exceeded the amount of water that usually accumulates in a full year, and it’s only mid-March, Zukiewicz said.
It’s a significant turnaround in the state’s snowpack conditions, Zukiewicz said.
“So they are going to have a lot more water to deal with when we get into run-off this year,” Zukiewicz said of reservoir managers and irrigation districts like Greenfields.
Kraig Lang, a wilderness ranger for the Rocky Mountain Ranger District in Helena-Lewis and Clark National Forest in Choteau who conducts snow surveys in the Bob Marshall Wilderness, said snowpack is significantly deeper this year compared to the past two years when snowpark was so sparse he was able to use horses on his trips.
“We can’t really get horses out of the trailhead this year so it’s a hike and ski option only,” Lang said.
But water content in that snow was not as as high as he expected to find.
“Once I saw the snow depth, I was surprised at how little water there was for the depth of snow we had,” he said.
He attributes the lower water content to the cold, dry storms that produced the snowfall this winter.
A wet storm that deposits 6 inches of snow might have a full inch of water, Lang said. On the other end of the spectrum, a dry, cold storm may have 18 inches of snow but only an inch of water.
He’s cautious in making comparisons between years because the snowpack over the past two years has been near-record lows. And it’s hard to say what normal is any more, he added.
“We’ve kind of gotten used to these more open seasons,” he said.
Automated SNOTEL equipment isn’t allowed in the wilderness, so measurements there must be taken manually. Lang, a snow ranger in the winter, recently completed a 65-mile round trip by foot to check three snow survey sites in the Bob Marshall Wilderness.
At the Wrong Creek Cabin in the northern end of the North Fork of the Sun River, he found 43.5 inches of snow depth on average.
“That’s a significant amount of depth for that site,” he said.
There was 11.8 inches of water.
Snow-water equivalent is one of the primary measurements taken at the automated SNOTEL sites, Zukiewicz said.
It’s a better measurement than snow depth in predicting stream run-off because snow depth can vary greatly due to settlement. The amount of water, on the other hand, remains consistent, he said.
SNOTEL sites have a big pillows that measure snow-water equivalent. As snow accumulates on the pillows, it displaces liquid in the pillows into lines that lead into a shelter building with electronic equipment that measures the pressure of the fluid.
“We can measure how much water is on there by converting pressure to inches of water,” Zukiewicz. “It’s a pretty nifty system.”
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Too soon to predict flooding
There’s deep snow in the mountains this year, but it’s too soon to say whether flooding will occur, said Lucas Zukiewicz, a water supply specialist for the U.S. Department of Agriculture’s Natural Resources Conservation Service.
Weather patterns in the coming months will play a critical role in the timing and magnitude of water in rivers this spring and summer, Zukiewicz said. To date, cooler, wetter weather has kept the water locked in the snowpack.
“Until we see a major change, the cool, wet weather looks to continue in this region,” he said.
Snowpack was deep in 2014, but spring precipitation was low and flooding was minimal, he noted.