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|Jonathan P. Thompson|
It’s that time of the month—and season—again, when we check out the first-of-the-month and end-of-winter health of the Southwestern snowpack. Yes, end of winter: Although the mountains are likely to see another couple of months of winter weather, meteorological spring began on March 1, which means average temperatures are beginning to rise. And, indeed, over the last few days Denver hit 73° F, Cortez topped out at 69° F, and Moab and other low-lying areas also climbed into the sixties during the day and barely dropped below freezing at night.
That’s great news if you want to work on your suntan after catching some spring-condition skiing. It’s not so hot for the health of the snowpack and spring runoff levels, as some of the gains from the late February storms melted away. Regardless of the season’s name or temperatures, the watersheds of the Upper Colorado River Basin are now entering what has historically been the snowiest part of the year. The median peak date for the Upper Colorado snowpack is April 6, with the latest peak (across 131 SNOTEL sites) on record falling on May 20 (during the notorious 1983 water year, when Glen Canyon Dam almost overflowed).
Glen Canyon Dam overflowing is certainly one thing we don’t have to worry about this year—or ever, I imagine. Quite the opposite:
- 3,526.63 feet: Lake Powell’s water surface level as of March 2, 2022.
- 36.63 feet Number of feet the current level is above the “minimum power pool,” or the lowest level at which hydroelectricity generation is possible.
- 44 feet Amount by which the lake’s level has dropped over the last year, for an average rate of 1.44 inches per day (which has accelerated to 2.4 inches per day over the last couple of weeks).
In other words, if current drawdown rates continue, Glen Canyon Dam will no longer be generating power in a year from now without modifications to the dam’s power plant. While the warm temperatures will melt some snow, bolster river flows, and increase inflow levels to Lake Powell, they have also upped the evaporation rate from the reservoir. Tune in next week for a detailed dispatch on what that will mean for the grid; for now let’s stay focused on the snow and the water it will hopefully bring.
At this point, snowpack levels are looking healthier across the basin than they did a year ago, but only barely.
The San Juan Mountain snowpack generally is more abundant than across the region as a whole, but still varies from place to place.
As predicted, the new snow (seen as the steep incline on the above graphs) atop the snow rotted out by the preceding freeze-thaw cycle (the flat line in January and February) set the stage for an active avalanche cycle. A slide near Marble, Colorado, caught three snowshoers and two dogs. While two of the people were able to dig themselves out, a third died, along with both dogs. And in the La Plata Mountains a Durango backcountry skier and his companion triggered an avalanche. One skier was caught in an avalanche he and a companion triggered and carried to the bottom of the chute. He suffered serious injuries, including a compound femur fracture, but his companion and rescuers were able to get him out alive.
Avalanches have killed 11 people in the U.S. so far this winter, and four in Colorado. Last winter the U.S. recorded 37 avalanche fatalities and Colorado 12.