@USBR announces 2021 #ColoradoRiver operating conditions #COriver #aridification

Here’s the release from the Bureau of Reclamation (Patti Aaron):

The Bureau of Reclamation today released the Colorado River Basin August 2020 24-Month Study, which sets annual operations for Lake Mead and Lake Powell in 2021. Based on projections in the Study, Lake Mead will operate in the Normal Condition in Calendar Year 2021 and Lake Powell will operate in the Upper Elevation Balancing Tier in Water Year 2021 (October 1, 2020 through September 30, 2021).

The August 2020 24-Month Study projects:

– Lake Mead’s Jan. 1, 2021, elevation to be 1,085.28 feet, about 10 feet above the Lower Basin shortage determination trigger of 1,075 feet.

– Lake Powell’s Jan. 1, 2021, elevation to be 3,591.60 feet — 109 feet below full and 101 feet above minimum power pool.

Because Lake Mead is projected to begin the year below the Drought Contingency Plan elevation threshold of 1,090 feet, Arizona, Nevada and Mexico will make water savings contributions to Lake Mead in calendar year 2021. Those Drought Contingency Plans, adopted by the seven Basin States, the U.S. federal government and Mexico in 2019, continue to proactively reduce risk in the basin.

“After a promising start to the snow season last winter, spring and summer turned very dry,” said Reclamation Commissioner Brenda Burman. “Thankfully, our reservoirs continue to do what they were built to do and are providing reliable water by holding it over from wetter years.”

The Upper Basin experienced a dry spring in 2020, with April to July runoff into Lake Powell totaling just 52% of average. The projected water year 2020 unregulated inflow into Lake Powell—the amount that would flow to Lake Mead without the benefit of storage behind Glen Canyon Dam—is only 58% of average. Total Colorado River system storage today is 51% of capacity, down from 55% at this time last year. Drought contingency plans are proactively addressing risks to the system from the ongoing 21-year drought.

A key component of Reclamation’s Colorado River Basin activities is the integration of sophisticated modeling tools and scientific research to inform water management decisions. Through a decades-long partnership with the Center for Advanced Decision Support for Water and Environmental Systems at the University of Colorado in Boulder, Reclamation hydrologic engineers and hydrologists are actively collaborating with climate, hydrology and decision support scientists to provide advanced modeling tools.

“This scientific expertise is key,” Commissioner Burman continued. “It helps us understand what’s happening in the basin now and how changes to climate and demand are likely to impact the river in the future so we can best operate our reservoirs to protect water reliability for generations to come.”

Their work is helping Reclamation link advances in science to water resource management decisions in the face of greater uncertainty and increased hydrologic and operational risks. Reclamation’s modeling and operations teams further refine these tools, such as the 24-Month Study, to make annual operational determinations for Lake Powell and Lake Mead through close coordination with water and power customers throughout the basin.

This giant #climate hot spot is robbing the West of its #water — The Washington Post #ActOnClimate #KeepItInTheGround #ColoradoRiver #COriver #aridification

Orchard Mesa Irrigation District power plant near Palisade. Water from Colorado’s snowpack is distributed across the region through a complex network of dams, pipelines and irrigation canals. Photo credit: Orchard Mesa Irrigation District

Here’s a deep-dive into the Upper Colorado River Basin climate from Juliet Eilperin that’s running in The Washington Post. Click through and read the whole article and to find your county on their dropdown to learn how much it has warmed. Here’s an excerpt:

Here, on Colorado’s Western Slope, no snow means no snowpack. And no snowpack means no water in an area that’s so dry it’s lucky to get 10 inches of rain a year…

A 20-year drought is stealing the water that sustains this region, and climate change is making it worse.

“In all my years of farming in the area, going back to about 1950, 2018 was the toughest, driest year I can remember,” said [Paul Kehmeier’s] father, Norman, who still does a fair share of the farm’s tractor work at 94.

Colorado Drought Monitor January 2, 2018.

This cluster of counties on Colorado’s Western Slope — along with three counties just across the border in eastern Utah — has warmed more than 2 degrees Celsius, double the global average. Spanning more than 30,000 square miles, it is the largest 2C hot spot in the Lower 48, a Washington Post analysis found…

On the Kehmeiers’ farm, like the rest of the area, just under two inches of rain fell between Jan. 1 and July 19. Less than half an inch has fallen since the farming season began on April 1, just 25 percent of the long-term average.

“The seasons where you don’t want to see the warming are warming faster,” said Jeff Lukas, a researcher at the University of Colorado at Boulder’s Western Water Assessment…

Farming in America’s dry interior has always amounted to an act of defiance. Water has reinvented the landscape that Kehmeier’s ancestors began working on more than a century ago. A vast irrigation network of pipes, tunnels and dams steers melted snow into fields across the valley and has transformed this sagebrush terrain into a thriving agricultural hub.

Bicycling the Colorado National Monument, Grand Valley in the distance via Colorado.com

With his family’s century-old water rights, Kehmeier stores water in a reservoir atop Grand Mesa. Facing long odds on the farm in 2018, he [leased] it for $100 an acre foot — quadruple the normal price — to a nearby fruit grower and Orchard City. (An acre foot is what it takes to cover an acre of land in a foot of water, roughly 325,000 gallons.)

“It would have to come about 16 miles from the top of that mountain down the creek,” he said, pointing toward Grand Mesa, “and the chance of getting it down the creek in a hot dry year when there’s not much water in the creek and a lot of thieves beside the creek, it was questionable. So, let somebody else deal with that.”

Kehmeier, who grows alfalfa and grass hay, didn’t agonize over his decision, but he didn’t like driving by his dried-up field every day. Call it a blessing or a curse, but farming is in his blood.

“And if it’s in your blood, you want to do it,” he said. “I want to go out kicking and scraping if I have to, but I don’t want to give up.”

He could always plant hay the following year, he thought. Surely, the snow would return…

Starting in 1898, Henry Kohler recorded the monthly mean temperature, the total precipitation and other details. He and other observers sent their reports to be compiled in Denver.

These early records, written in cursive, form the foundation of NOAA’s official temperature records, which show that around the close of the 19th century, Delta County’s climate was more than 2 degrees Celsius cooler than it is today…

Winters in the Northeast are less cold, but experts cannot say yet whether a warmer Atlantic Ocean is driving it. Western Colorado is experiencing a feedback loop, according to Colorado State University senior scientist Brad Udall, because there is less soil moisture to absorb the solar energy and transfer it to the air through evaporation.

“Heating begets drying, and then drying further begets heating,” he said.

Dry areas warm faster for lack of moisture to cool things down, said Chris Milly, a senior resource scientist at the U.S. Geological Survey. Land use, irrigation and natural variability could also help explain part of the disparity.

Milly and another colleague recently found that much of the Colorado River’s climate-induced decline — amounting to 1.5 billion tons of missing water — comes from the fact that the region’s snowpack is shrinking and melting earlier. That’s as much water as 14 million Americans use in a year…

“What we’re seeing is changes in real time,” said Mark Harris, who directs the Grand Valley Water Users Association. “As water managers, regardless of our personal beliefs, we can’t totally disregard these worst-case scenarios. The trends are leading in one direction.”

Screenshot of Washington Post graphic August 2020. Temperature change C 1895-2019. Credit: John Muyskens/The Washington Post