New Signs of Trouble Ahead for #ColoradoRiver Basin Water Managers — Allen Best #COriver

Morning on the upper Colorado River. Photo: Brent Gardner-Smith/Aspen Journalism

From RouteFifty.comn (Allen Best):

Peak runoff in the Colorado River this year has arrived exceptionally early and with unusual modesty. It’s part of a pattern in the 21st century, one that scientists warn will become even more common in the future.

One measuring site is at Cameo, located amid sandstone cliffs coated with desert varnish two hours downstream from Aspen and Vail and a short distance from Grand Junction. There, runoff in the Colorado River reached 6,650 cubic feet per second on Monday. Unless surpassed by a second surge of runoff predicted for Saturday, it is likely to be the earliest date for peak runoff at the site in 50 years, according to the Colorado River Water Conservation District.

It’s also a runoff of modest flows, the fourth lowest in 85 years of record-keeping at Cameo. The lowest was in 1977, according to the Glenwood Springs-based River District, followed by those of 2002 and 2012—and now 2018.

Winter was warmer and drier than usual, and the last month has been the same: 2 to 4 degrees Fahrenheit warmer than average. Spring precipitation has similarly lagged across western Colorado…

Taking the long view, [Jeff] Lukas notes there’s a lot of “noise” or natural variability in the climate records. But this clustering suggests a changed norm. What used to be the sort of runoff that might occur every 25 years could now, perhaps, be expected about every 10 years.

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