Extremely Dry Conditions Spill Across the American West — Circle of Blue #drought #aridification

West Drought Monitor map May 11, 2021.

From Circle of Blue (Brett Walton):

Drought and climate change are sapping the region’s water. The numbers indicate challenging years ahead.

Spring is generally a time of renewal for the watersheds of the western United States.

Warmed by the lengthening days, the region’s towering mountain ranges shed their mantle of snow, releasing freshets of water into welcoming streams and reservoirs.

This year, though, the cycle is in disarray. Outside of the Olympic and Cascade ranges of Washington state, winter snows were subpar. The spring melt has been a dud. From the Klamath to the Colorado and Rio Grande, watersheds are under stress once again, and water managers face difficult tradeoffs between farms, fisheries, and at-home uses. The main thing being renewed is concern over the seeming inadequacy of the region’s water supply.

“This is a drought emergency,” said Becky Bolinger, the Colorado assistant state climatologist.

Bolinger was referring to the latest runoff forecast for Lake Powell, a large reservoir on the Colorado River. The amount of water projected to flow into the country’s second-largest reservoir this spring and summer is 28 percent of the 30-year average. Dan Bunk of the Bureau of Reclamation said this year’s inflows are on pace to be the third or fourth lowest in the last century. Today, the lake is just 34 percent of capacity — or, looking at the math another way, about two-thirds empty. Downstream states like Arizona are bracing for mandatory cutbacks next year.

What is worrisome is that Bolinger could have been discussing any number of western watersheds.

In California on Monday, Gov. Gavin Newsom expanded a drought declaration to include 41 of the state’s 58 counties. Water levels in the state’s two largest reservoirs — Oroville and Shasta — are about half of what they usually hold this time of year.

In the Klamath basin of southern Oregon and northern California, there are already lawsuits over how the Bureau of Reclamation is allocating scarce water from Upper Klamath Lake. The drought is forcing the federal agency to balance the needs of endangered fish species both upstream and downstream. It told farmers in the upper basin to expect very little irrigation water this summer.

In New Mexico, water managers say the Rio Grande through Albuquerque could run dry this summer, which would complicate water management efforts. Mike Hamman, chief executive officer of the Middle Rio Grande Conservancy District, told Circle of Blue that his district faces a “three-pronged challenge:” delivering irrigation water to farmers, sending water downstream to Texas that is required under a federal compact, and protecting endangered species like the silvery minnow that rely on the river…

Instead of calling these dry years a drought, they recommend the term “aridification.” Drought suggests a temporary departure from normal. Aridification implies that the region’s climate, under the influence of heat-trapping gases in the atmosphere, is entering a different reality…

As in the Colorado River basin, precipitation in California this winter and spring was quickly eaten by a hot and thirsty atmosphere and dry soils.

Leave a Reply