Extreme Temperature Diary- Wednesday August 17th, 2021/ Main Topic: Why The Western Drought Is The First U.S. Big City Ending Threat

The main purpose of this ongoing blog will be to track planetary extreme or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials).😉

Main Topic: Why The Western Drought Is The First U.S. Big City Ending Threat

Dear Diary. I’ve often stated on this blog that it’s never a good idea to build a large city in a desert. Nevertheless, that’s what the United States did during the 20th century with Las Vegas and Phoenix. Engineers figured that once the Hoover Dam was erected to expand Lake Meade, enough water would be supplied to cities and agriculture in abundance from a fairly stable climate. Snow melt from the Rockies would mostly feed into Lake Meade and also Lake Powel, and be abundant enough to sustain Las Vegas and Phoenix for hundreds of years given a stable seasonal water cycle.

Now civil engineer are getting awfully nervous as the water level in western lakes has gotten precipitously lower most years during the 21st century. Obviously, climate change was getting the water cycle out of balance such that not enough water was flowing into Lake Meade to keep current civilization in many portions of the Southwest sustainable. At some point they had to pull the trigger on water restrictions, and this week was that time.

At the current rate Las Vegas and Phoenix could run out of water before Miami goes underwater, events that would pretty much end these cities as we know them now.

Here are more details from the New York Times:

In a First, U.S. Declares Shortage on Colorado River, Forcing Water Cuts

Arizona farmers will take the initial brunt, but wider reductions loom as climate change continues to affect flows into the river.

Drought Takes a Toll on the Colorado River, Forcing Water Cuts

Years of drought have severely depleted the reservoirs that feed the Colorado River, and deeper restrictions on water use are expected. “Additional actions will likely be necessary in the very near future,” a senior official said.

“We are seeing the effects of climate change in the Colorado River basin through extended drought, extreme temperatures, expansive wildfires, and in some places, flooding and landslides. And now is the time to take action to respond to them. The basin is experiencing its 22nd year of drought. And earlier this summer, the reservoirs hit their lowest levels since they were originally filled.” “There’s never been a declaration of shortage, so the fact that we are seeing the first declaration is quite significant, historically.”

By Henry Fountain Aug. 16, 2021

With climate change and long-term drought continuing to take a toll on the Colorado River, the federal government on Monday for the first time declared a water shortage at Lake Mead, one of the river’s main reservoirs.

The declaration triggers cuts in water supply that, for now, mostly will affect Arizona farmers. Beginning next year they will be cut off from much of the water they have relied on for decades. Much smaller reductions are mandated for Nevada and for Mexico across the southern border.

But larger cuts, affecting far more of the 40 million people in the West who rely on the river for at least part of their water supply, are likely in coming years as a warming climate continues to reduce how much water flows into the Colorado from rain and melting snow.

“As this inexorable-seeming decline in the supply continues, the shortages that we’re beginning to see implemented are only going to increase,” said Jennifer Pitt, who directs the Colorado River program at the National Audubon Society. “Once we’re on that train, it’s not clear where it stops.”

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The Bureau of Reclamation, an agency of the Interior Department, declared the shortage as it issued its latest outlook for the river for the next 24 months. That forecast showed that by the end of this year Lake Mead, the huge reservoir near Las Vegas, would reach a level of 1,066 feet above sea level. It hasn’t seen a level that low since it began to fill after the completion of Hoover Dam in the 1930s. The lake will be at 34 percent of capacity.

“Today’s announcement highlights the challenges we face in the Colorado River basin and elsewhere in the West,” said Tanya Trujillo, assistant interior secretary for water and science.

Water levels at Lake Mead and the other large Colorado reservoir, Lake Powell, in Utah, have been falling for years, leaving a telltale white “bathtub ring” of mineral deposits along the shoreline as demand has outpaced supply.

The mandatory cuts, referred to as Tier 1 reductions, are part of a contingency plan approved in 2019 after lengthy negotiations among the seven states that use Colorado River water: California, Nevada and Arizona in the lower basin, and New Mexico, Utah, Colorado and Wyoming in the upper basin. American Indian tribes and Mexican officials have also been involved in the planning.

The shortage announced Monday affects only the lower basin states, but the Bureau of Reclamation may declare a similar shortage for the upper basin, perhaps as early as next year.

The shortage declaration will reduce Arizona’s supply of Colorado River water, delivered by a system of canals and pumping stations called the Central Arizona Project, by about 20 percent, or 512,000 acre-feet. (An acre-foot is about 325,000 gallons, enough water for two or three households for a year.)

Park visitors explored a part of Lake Powell in Big Water, Utah, in June that used to be underwater. Credit…Justin Sullivan/Getty Images

In anticipation of the cuts, some farmers have fallowed fields or switched to less water-intensive crops. Others will be pumping more groundwater to make up for the cuts, which raises additional questions about sustainability because groundwater supplies are not unlimited.

“The river is the iconic resource,” said Kevin Moran of the Environmental Defense Fund. “But we have to think about managing our groundwater as well.”

Recent Updates

Updated Aug. 18, 2021, 7:39 a.m. ET3 hours ago3 hours ago

The question for Lake Mead and the Colorado is whether the Tier 1 cuts will be enough to halt the decline in supply as climate change continues to affect the river’s flow. Additional tiers, which could go into effect soon if the lake level continues to decline, as the forecast released Monday projects, would involve increasingly draconian cuts. And even further reductions may have to be negotiated.

This year has been one of the worst ever for runoff into the Colorado River, said Ted Cooke, general manager of the Central Arizona Project. “The big question is, what’s going to happen in 2022?” he said. After two decades of drought, “one thing that we don’t have is the resiliency in the reservoirs, because they’re so low, to withstand the type of year that we had this year back to back.”

Sharon B. Megdal, director of the Water Resources Research Center at the University of Arizona, said she thought the declaration’s focus on the dire state of the river would lead to more efforts in the region to use less water. “I think we’re going to see some adaptation,” she said. “But I don’t know if we can do that much to avoid further cuts.”

With the various tier cuts that were negotiated, “We’re really only talking through 2025,” Dr. Megdal said. “If things continued to get worse and worse, I think there would be some interventions to do even more. We can’t let the river system fail.”

Lake Mead now contains about 12 million acre-feet of water, far below its capacity of nearly 30 million acre-feet. The last time it was anywhere near full was two decades ago.

Since then, much of the Southwest has been mired in a drought that climate scientists say rivals some long-lasting droughts in the past 2,000 years.

Even in the occasional recent year with good snowpack in the Rocky Mountains, the amount of water running off into the river has declined. Researchers say warming is largely to blame, as soils have become so dry that they soak up much of the melting snow like a sponge, before it can reach the river.

Planning for the likelihood of a reduced supply of Colorado River water began shortly after the drought first set in. By 2007, the states had developed guidelines for coping with shortages, which the 2019 agreement fleshed out.

“The announcement today is a recognition that the hydrology that was planned for years ago and we hoped we’d never see is here,” said Camille Touton, a deputy commissioner of the Bureau of Reclamation.

“The river is in uncharted territory,” Mr. Moran said. “Climate scientists have pretty well articulated that something like 40 to 60 percent of the decline is due to a warming climate.”

Mr. Moran said that the new infrastructure bill, which has passed the Senate but faces a rockier road in the House, includes at least several billion dollars that could help the region cope with this new reality. This includes money to improve so-called natural infrastructure, including forests, watersheds and underground aquifers, which could help bolster the supply, or at least slow the decline.

“Our water infrastructure is not just man-made reservoirs and treatment plants,” he said. “It’s the natural system, too.”

Credit…The New York Times

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Henry Fountain specializes in the science of climate change and its impacts. He has been writing about science for The Times for more than 20 years and has traveled to the Arctic and Antarctica. @henryfountain • Facebook

Here are some “ET” reports from the last couple of days:

Here is more climate and weather news from Wednesday:

(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article. The most noteworthy items will be listed first.)

Now here are some of today’s articles and notes on the horrid COVID-19 pandemic:

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Guy Walton “The Climate Guy”

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