Sunday, July 12, 2020

Local snow surveys aid in state-wide water calculations

NRCS co-op program predicts strong river flows ahead

By Katherine Nettles

Data collected from recent snowpack surveys suggest a much wetter spring than last year, according to local and state water officials. A late-March survey of local snowpack, both manually through snow course sites and automatically through snowpack telemetry (SNOTEL) sites, has indicated a major change in snow water equivalent (SWE) from this winter compared to that of 2018.

The survey is taken monthly each winter and spring by the Natural Resources Conservation Service (NRCS) Cooperative Snow Survey Program in the Upper Gunnison River Basin, which includes a partnership with the Bureau of Land Management (BLM), the NRCS, the Gunnison Conservation District, Trout Unlimited, the Crested Butte Land Trust, the Wildbird Community, Freeport-McMoRan (owner of the Keystone mine on Mt. Emmons), Upper Gunnison River Watershed Conservation District, Colorado Parks and Wildlife, Colorado Department of Natural Resources, HCCA and Crested Butte Nordic.

The surveys taken in March are considered to be at the height of the snowpack for the season, says BLM hydrologist Andrew Breibart. “This data is used to forecast water runoff in the Gunnison River Basin,” he says. That data is then used by water experts across Colorado and throughout the West to determine state of drought and water situations.

Breibart and Bill Ketterhagen, vice president of the Gunnison Conservation District, conducted two of the local snow course surveys, one near the Keystone mine and one near the Magic Meadows Yurt in Crested Butte, on March 29.

“The Keystone and Crested Butte are additional data points that provide more information for water supply forecasters and water managers,” explains Upper Gunnison River Water Conservancy District general manager Frank Kugel.

The Crested Butte site near Oh-Be-Joyful Creek and the Slate River, established in 1936 and situated at an elevation of 8,920 feet, measured a (provisional) snow depth of 57 inches and SWE of 18 inches. The Keystone site, installed in 1961 and situated at an elevation of 9,960 feet, measured a (provisional) average snow depth of 60 inches and SWE of 22 inches.

The following week, the Natural Resources Conservation Service (NRCS) released its monthly data collected throughout the state, which pieces together a larger picture of what the snowpack looks like for the whole Colorado River Basin. This helps water forecasters and water experts such as Kugel set their expectations for spring runoff, for seasonal river and stream flows, and for replenishing reservoirs such as Blue Mesa. The monthly data is collected in January, February, March and April.

Breibart noted a “year in extremes” at the Lake City snow course, where the April 1, 2018 snow survey showed a record low SWE of .8 inches, and the April 1, 2019 survey nearly reached the record high SWE of 14.7 inches, reached in 1958.

Another notable thing, said Kugel, was the extremes in weather with wet snow, rain and a high volume of precipitation overall in early March. “It was an epic year for snow and for slides,” says Kugel.

For more information and data, go to www.nrcs.usda.gov/wps/portal/nrcs/main/co/snow/waterproducts/supply/

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