Thirsty Future for American West, as ”#Megadrought” Grips Some of the Fastest-Growing U.S. Cities — Fair Warning #ColoradoRiver #COriver #aridification

Farm Security Administration members post on a cooperative pipe line used for irrigation in Saint George in 1940. Contributor Names Lee, Russell, 1903-1986, photographer Created / Published-1940 Oct.-Subject Headings – United States–Utah–Washington County–Saint George

From Fair Warning (Alexandra Tempus):

In 2002, Utah was reeling from four years of dry conditions that turned the state ‘’into a parched tinderbox,’’ as the Associated Press reported at the time. “Drought Could Last Another 1-2 years,” the headline proclaimed. Right on time, in 2004, the Salt Lake Tribune ran a similar article, on “Coming To Terms with Utah’s Six-Year Drought,” that was “believed to be the worst to strike the Southwest in half a millennium.”

Almost two decades later, the drought has raged on. In October 2019, the water supplier for St. George, a rapidly growing resort and retirement community in southwest Utah, released a statement declaring the city’s longest-ever dry spell: 122 days without rain.

A study published last month in the journal Science identified an emerging “megadrought” across all or parts of 11 western states and part of northern Mexico—a drought likely, with the influence of climate change, to be more severe and long-lasting than any since the 1500s. The area includes Utah, Nevada, Arizona, California and portions of Oregon, Idaho, Montana, Wyoming, Colorado, New Mexico and Texas.

This region is also experiencing explosive population growth—with Idaho, Nevada, Arizona and Utah topping the list of states with the highest percentage increase in residents from 2018 to 2019, according to the U.S. Census Bureau. For decades, these states and their mushrooming municipalities have been grappling with the twin concerns of rapid growth and dwindling water supply projections. Now, in the midst of an historic megadrought predicted to last many more years, the issue has grown increasingly urgent.

For the megadrought study, scientists analyzed tree rings from nearly 1,600 trees that had grown across the region over hundreds of years, says the study’s lead author, A. Park Williams, an associate research professor at Columbia University’s Lamont-Doherty Earth Observatory. Examining the rings under a microscope, the researchers could see when growth was slow, indicating time periods when the region was especially dry.

The authors identified megadroughts—droughts more severe and much longer than anything observed in the written record, says Williams—over the last 1200 years. The most recent was in the late 1500s, until now. Today’s megadrought has been marked by more frequent and severe wildfires, a decline in groundwater, lake and river levels and a reduced snowpack.

And climate change, added Williams, is “making it easier to go into a megadrought without the ocean and atmosphere needing to team up in as extreme of a way” as they did to create such conditions in the past.

In Utah, the situation might be considered dire.

“Our population is one of the fastest-growing in the country and we’re also one of the driest states in the country and our water supply in large part is mountain snow,” said Michelle Baker, an aquatic hydrologist at Utah State University who was project director for iUtah, a years-long research effort to transition the state to sustainable water usage.

With the mountain snowpack dwindling due to climate change, Utah researchers identified several ways to help close the supply gap, said Baker. One included storing more water underground than in reservoirs to limit the amount of water lost to evaporation. Another involved replacing Utah’s old-fashioned dirt-lined irrigation canals with pipes to curb evaporation and seepage.

In March, Utah adopted a law creating a new water banking program, similar to those in other states, that will allow water rights holders to “bank” their unused water rights and lease them temporarily to others without selling them outright…

St. George currently uses 33,000 acre-feet of water per year, Karry Rathje, a spokesperson for the Washington County Water Conservancy District, told FairWarning in an email. (An acre-foot is enough water to cover an acre of land with one foot of water, and is roughly enough to supply three homes for a year.

Washington County, which includes St. George, “is projected to need an additional 86,000 acre feet of water to meet the demands of a population that’s projected to nearly triple by 2060,” Rathje said.

This is to say nothing of exponential growth in greater Salt Lake City, which by 2060 could swell to the size of the Seattle metropolitan area of 3.7 million residents, according to one estimate.

Utah Rivers map via Geology.com

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