From Water Education Colorado (Jerd Smith):
Colorado’s water forecast, already strained by back-to-back drought years, is unlikely to brighten this fall and winter, as forecasts indicate more dry weather lies ahead.
Water planners use something known as the water year to track and predict snow and rain, as well as winds and soil conditions. It begins Oct. 1, leading into the period of critical mountain snows and the spring runoff they generate, and estimations of what it will yield help farmers, cities and others determine how much H20 they will have to work with.
But water year 2022 is getting off to another dusty, dry start.
“The seasonal outlook is not pointing in a favorable direction,” said Peter Goble, a climate specialist at Colorado State University’s Colorado Climate Center. “We’re a lot better off than we were a year ago. Having blue skies as opposed to smoke is a big improvement, but we are going into water year 2022 on shaky footing.”
Goble was referring to Colorado’s disastrous fire season during last year’s drought, when the state saw three of the largest wildfires in its history erupt in late summer and early fall.
Last week, at a meeting of the state’s Water Availability Task Force, forecasters said Colorado was likely to experience another La Niña this coming year, a weather pattern that can bring healthy moisture to the Northern Rockies but which often leaves the southwestern portion of the state dry. Because 2020 saw the same La Niña develop, this year’s may bring less moisture.
In the broader Colorado River Basin, water storage levels continue to drop, with total storage at lakes Powell and Mead down to a combined 39% full, below last year’s already low 49% full mark, according to an update released Sept. 22 by the U.S. Bureau of Reclamation. The Colorado River Basin is made up of seven states. Colorado, Utah, Wyoming and New Mexico comprise the Upper Basin, while Arizona, California and Nevada comprise the lower basin.
In July, Reclamation began a series of emergency water releases from Flaming Gorge, Blue Mesa and Navajo reservoirs in the Upper Basin to help bolster Lake Powell and protect its hydropower generating stations. But conditions there continue to deteriorate.
Lake Powell could see just 44% of average inflows starting in October. Without a snowy winter and spring, hydropower generation at Powell’s Glen Canyon Dam could come to a halt as early as July 2022, according to Reclamation.
“The latest outlook for Lake Powell is troubling,” said Wayne Pullan, director of Reclamation’s Upper Colorado Basin Region.
Weather experts are also deeply worried about a phenomenon that continues to grow in intensity: the arrival of healthy snows that evaporate or seep into parched soils, never reaching streams in the volumes they once did.
Karl Wetlaufer, who is assistant snow survey supervisor at the Natural Resources Conservation Service, said water planners have long relied on a solid connection between snow and subsequent water supplies, where healthy snowpacks were reflected in healthy streamflows.
But with Colorado and other Western states mired in a 20-year drought, where soils get drier and drier each year, streamflow forecasts are becoming less predictable.
“Snowpack [last winter] was not terrible, but with those dry soils and a warm and dry summer we really saw dramatically decreased streamflows,” said Wetlaufer, who is a member of the state’s Water Availability Task Force.
In Northwest Colorado’s Yampa River Basin, snowpack peaked at 90% of average last winter, but streamflows this spring and summer reached only 30% of average.
“As long as I can remember, this is the most dramatic example of the multi-decadal drought’s impact. We are really going to have to start paying closer attention to these dry soils,” Wetlaufer said.
Jerd Smith is editor of Fresh Water News. She can be reached at 720-398-6474, via email at email@example.com or @jerd_smith.