Snowpack level rebounds after week’s steep climb in Upper Colorado River Basin

LAS VEGAS (KLAS) — Snowpack that will feed the Colorado River this summer has reached 100% of normal levels for the first time in 2024, according to tracking by the U.S. Bureau of Reclamation.

Atmospheric rivers this week have soaked Southern California, Southern Nevada and northern Utah. But another flow of moisture through Arizona and into Colorado has produced snow that has helped raise SWE (snow water equivalent) levels to 101% of normal.

Just a week ago, Bureau of Reclamation maps showed SWE levels at 85%. But it’s been a very good seven days for the Upper Colorado River Basin. Maps showing precipitation and SWE levels (compared to normal levels over the past 30 years) provide detailed information for nine areas within the region, along with an average for the entire basin (represented by the blue box):

Feb. 8, 2024: Upper Colorado River Basin

Snow levels are highest in southwest Colorado and southwest Utah — the Lower San Juan region — where SWE went from 102% of normal on Feb. 1 to 129% on Feb. 8. A look at changes for all the regions:

  • Upper Green: From 79% on Feb. 1 to 89% on Feb. 8

  • Lower Green: From 85% on Feb. 1 to 118% on Feb. 8

  • White-Yampa: From 89% on Feb. 1 to 98% on Feb. 8

  • Colorado Headwaters: From 90% on Feb. 1 to 98% on Feb. 8

  • Gunnison: From 86% on Feb. 1 to 101% on Feb. 8

  • Dirty Devil: From 80% on Feb. 1 to 110% on Feb. 8

  • Lower San Juan: From 102% on Feb. 1 to 129% on Feb. 8

  • Dolores: From 83% on Feb. 1 to 109% on Feb. 8

  • Upper San Juan: From 76% on Feb. 1 to 97% on Feb. 8

The nine regions are named for the rivers that collect runoff in the regions that make up the Upper Colorado River Basin. The gray boxes in the map show how full reservoirs are.

The Upper Green River region was in the path of the atmospheric rivers that flooded Los Angeles neighborhoods, but it is currently the area with the lowest snow levels.

For comparison: Feb. 1, 2024, Upper Colorado River Basin

High levels in some of the regions can be deceiving. For example, the 80-mile-long Dirty Devil River in southern Utah doesn’t contribute as much to the Colorado River’s volume as the Colorado Headwaters. Dirty Devil is a desert region, and much of the moisture from the snowfall will soak into the ground. But the snowpeaked Rocky Mountains will hold snowpack longer and supply water to the river for an extended time. A 98% SWE level for the Colorado Headwaters is more important for the river than a 129% level at Dirty Devil.

And the overall snowpack on Feb. 8, while encouraging, is not as important as the season totals that we won’t know until April 1. Last year, the total hit 160% on April 1, and the Bureau of Reclamation was able to raise Lake Mead and Lake Powell over the past year.

Snow built up over the week, but it could just as easily shrink if it warms up.

Scientists have found other important factors besides temperature.

Snow “albedo” — or brightness — is a big factor in snowmelt because bright white snow reflects solar energy. But as snow gets dirty from airborne particles from dust or smoke, it absorbs more solar energy.

Snow cover factors into that, too. The more ground that is covered in snow, the less likely it is that dust will blow over the snowpack. But winds can carry particles from far away.

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