Radar getting another look at snowpack — The Pueblo Chieftain

Conejos River
Conejos River

From The Pueblo Chieftain (Matt Hildner):

Water officials in the San Luis Valley will once again set up a temporary radar station this winter to help measure the region’s snowpack.

Although the technology was in use last winter, it’s hoped another season of gathering data from radar and other new technologies will eventually lead to a model that can more accurately translate snowpack to stream flows.

“No one in the country has ever used radar to measure snow,” Nathan Combs, manager of the Conejos Water Conservancy District, told a committee of state lawmakers Monday.

Getting an accurate prediction of stream flows is important for valley water users, who are often forced to forgo flows to help the state comply with the Rio Grande Compact.

Delivery obligations under the compact, which divvies up the river’s flows between Colorado, New Mexico and Texas, go up in wet years and down in dry years.

Combs told lawmakers in April the forecast for the Conejos called for 235,000 acre-feet of stream flow for the year, with a delivery requirement of 65,000 acre-feet for the compact.

But runoff was bigger than expected, boosting both stream flow projections for the year and the amount of restrictions on irrigators.

As of the beginning of the month, the Conejos’ stream flow projection had jumped to 255,000 acre-feet and its compact obligation grew by another 12,000 acre-feet.

Combs said that kind of jump is hard to deal with after runoff has come and gone.

“The farther we get down the season, the less water there is to pay this increased obligation,” he said.

Nor is an overestimation of stream flows any help.

“If we’ve overpaid early and then we go through and our stream forecast goes down, now we’ve sent all this water we can’t get back,” he said.

Combs said in the past the snow measurements and forecast data from the Natural Resources Conservation Service had not caused problems.

But that has changed over the last decade as forest fires, spruce-beetle infestations and increasing dust storms have changed the snowpack’s behavior.

Combs’ district has taken part in a pilot project funded by the Colorado Water Conservation Board and Rio Grande Basin roundtable that also added extra stream and snow gauges to the Conejos’ watershed.

Likewise, water officials have also been active in the revision of the Rio Grande National Forest Plan.

“We need more instrumentation in the wilderness areas,” said Travis Smith, who represents the Rio Grande on the state conservation board.

The tour and hearing with the Water Resources Review Committee did not include any funding requests for projects and was mainly a way for water officials to educate lawmakers about valley water issues, Smith said.

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