Snowpack totals? It’s all part of March Madness

Hammered by this month’s snowstorms, Summit and Grand counties provide a big boost to our water supply.

March 24, 2016 | By: Jay Adams

March in the Colorado Rockies can be as wild as a half-court buzzer beater in the NCAA Basketball Tournament.

The first week of the month was dry and unseasonably warm. The second week brought a bounty of snow, and some parts of Summit and Grand counties picked up more than 30 inches. Week three saw 70-degree temperatures in Denver, followed by a blizzard and more heavy snow in the mountains.

Call it our own version of March Madness.

That kind of volatile spring weather is why Denver Water’s planning team remains cautious about predicting the snowpack yield until mid-to late-April. “Weather in March is like the basketball tournament,” said Nathan Elder, water resource engineer. “We really don’t know what we’re going to get every year.”

The frozen Snake River east of Keystone is one of Dillon Reservoir's three main tributaries.
The frozen Snake River east of Keystone is one of Dillon Reservoir’s three main tributaries.

The latest storm delivered impressive snow totals at Denver Water locations. Gross Reservoir in Boulder County picked up 20 inches of wet snow, which contained 2.13 inches of water. Strontia Springs Reservoir in Waterton Canyon received 13 inches of snow with 1.43 inches of water and Cheesman Reservoir in Douglas County received 10.5 inches of snow with 1.07 inches of water content.

Mountain snow provides 80 percent of Denver Water’s water supply (rain accounts for the rest), and March and April alone produce an average of 25 percent of the collection system’s annual precipitation.

“The snow we’ve been getting over the past two weeks has been really good for the mountain snowpack,” said Elder. “We’ve definitely seen a nice spike upward on the charts this month.”

It certainly didn’t look that way earlier this year. “Across most of February and early March we had warm temps and dry conditions and melted quite a bit of snow,” said John Blackwell, Dillon Reservoir operations manager. “But now winter’s back, which is creating a bit of madness here in Summit County.”

Snowpack — in the areas of the Upper Colorado and South Platte River basins where Denver Water captures its snow — was above normal in December and January, below normal in February and then back above normal in late-March.

Colorado River March 24 snowpack

SP March 24 snowpackOn March 14, snowpack in the Colorado River basin stood at 100 percent of normal and snowpack in the South Platte River basin was 95 percent of normal. After two weeks of snow, the two basins shot up to 109 and 107 percent respectively, on March 24.

March and April are critical months for deciding whether the year’s snow totals will produce a championship season of water, or merely play runner-up to previous years.

While this year’s snowpack is looking good, it will likely fall short of the all-time championship seasons in Denver Water’s collection areas. Snowpack peaked at 166 percent of normal in the Colorado River basin in 1984 and an incredible 203 percent of normal in the South Platte basin in 1997.

Dillon Reservoir in Summit County stood at 93 percent full on March 21, 2016. The historic median for this time of year is 87 percent.
Dillon Reservoir in Summit County stood at 93 percent full on March 21, 2016. The historic median for this time of year is 87 percent.

Even in an average snow year, it’s common to see ups and downs on the snowpack charts. “Some years you’re constantly hit by small storms, other times you get nailed with one huge storm like we did in the spring of 2003,” Elder said.

Denver Water’s reservoir levels are above average for this time of year, and Blackwell hopes more snow this spring will fill Dillon Reservoir this summer. “We’re still cautious, we’re optimistic, and the next couple weeks are critical,” he said.

With more snow in the forecast for the last week of March and the National Weather Service’s Climate Prediction Center showing a 40 percent chance of above-average precipitation for most of Colorado in April, the rest of the snow season is looking good. “We’re getting there,” Elder said. “We can’t say we’re good yet, but we are heading in that direction.”

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