[Water_news] 1. DWR'S CALIFORNIA WATER NEWS - Top Item for 4/21/09

Department of Water Resources

California Water News

A daily compilation for DWR personnel of significant news articles and comment

 

April 21, 2009

 

1.   Top Items–

 

Study: Shortages likely on Colorado River by 2050

The Associated Press

 

As early as 2025, Southwest will demand more water than is in river, UCSD scientists say

The San Diego Union Tribune

 

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Study: Shortages likely on Colorado River by 2050

The Associated Press – 4/20/09

By Mike Stark

 

If the West continues to heat up and dry out, odds increase that the mighty Colorado River won't be able to deliver all the water that's been promised to millions who rely on it for their homes, farms and businesses, according to a new study.

 

Less runoff — the snow and rain that fortify the 1,400-mile river — caused by human-induced climate change could mean that by 2050 the Colorado won't be able to provide all of its allocated water 60 percent to 90 percent of the time, according to two climate researchers at the Scripps Institution of Oceanography at the University of California at San Diego.

 

The more parched the landscape, the more difficult the choices will be for those with dibs on the Colorado's water and those in charge of divvying it up, said Tim Barnett, lead author of the study.

 

"The dry year scenarios in the future are going to be absolutely brutal," he said.

 

Barnett and fellow Scripps scientist David Pierce made waves last year with a study saying there's a 50 percent chance that Lake Mead, the reservoir created by the Hoover Dam, could run dry by 2021.

 

They teamed up on the latest study to predict when the river — under different climate scenarios predicting 10 percent to 30 percent reductions in runoff — will be unable to fully meet all of the demands put on it.

 

The results were published Monday in the journal Proceedings of the National Academy of Sciences.

 

"Without numbers like this, it's pretty hard for resource managers to know what to do," Barnett said.

 

The Colorado is a lifeline of the southwest, flowing through seven states and into Mexico and quenching the thirsts of some 27 million people who use it to irrigate crops, water lawns, produce drinking water and operate businesses.

 

Drought has already stressed the river. The problem is being compounded by growing populations demanding more water and the expected effects of climate change, said Brad Udall, director of the University of Colorado's Western Water Assessment.

 

"We're on a collision course between supply and demand," Udall said.

 

The Bureau of Reclamation, the federal agency that plays a key role in how the river system is managed, has used a different set of calculations than the Scripps researchers to reach a similar — though less dire — prediction, according to Terry Fulp, the agency's Nevada-based deputy regional director for the Lower Colorado.

 

His agency's calculations predict the Colorado could run short of water 58 percent to 73 percent of the time by 2050.

There's room to quibble over percentages, Fulp said, but the overriding point remains.

 

"We've got some serious issues to grapple with," he said.

 

Under conservative climate change scenarios in the West, Barnett and Pierce found decreases in runoff could short the Colorado River by about 400,000 acre feet of water 40 percent of the time by 2025. That's equivalent to the amount of water needed to supply 400,000 to 800,000 households.

 

Those figures double later in the century, according to the Scripps researchers.

 

The signs point toward tough decisions about who will get less water. Agricultural operations use about 80 percent of the water taken out of the Colorado, Barnett said. He knows the arguments, though: Shorting farms could drive up food prices. Curbing development in cities and suburbs will make developers unhappy. Whatever the case, he said, some decisions need to be made soon.

 

"The actions that need to be taken aren't going to be fun," Barnett said. "It's not going to be life as usual."

But, Barnett and Pierce said, it isn't too late to buffet some of the harshest effects.

 

Measures such as conservation and water exchanges, which can require upfront investments and flexibility, could play a key role in avoiding some of the biggest shortfalls, they said.

 

In 2007, officials from the seven states that get water from the river — Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming — and then-Interior Secretary Dirk Kempthorne signed a far-reaching agreement aimed at conserving and sharing the scarce resource. The 19-year plan formalized rules for cooperating during the ongoing drought.

 

Meanwhile, researchers will continue gathering information on climate change and looking for ways to keep the Colorado functioning — albeit with a new set of climate-driven rules.

 

"It really depends on how innovative people get," Fulp said.#

 

http://www.sfgate.com/cgi-bin/article.cgi?f=/n/a/2009/04/20/state/n145427D24.DTL&type=science

 

As early as 2025, Southwest will demand more water than is in river, UCSD scientists say

The San Diego Union Tribune – 4/20/09

By Dave Downey

 

As Southern Californians brace for water cuts this summer, UC San Diego researchers have concluded that climate change will trigger shortages on the Colorado River up to 88 percent of the time by midcentury.

The findings of marine physicist Tim Barnett and climate researcher David Pierce of the Scripps Institution of Oceanography, published Monday in the journal Proceedings of the National Academy of Sciences, are remarkable given that the mighty river of the Southwest always has filled all orders for its water.

But that is about to change, the scientists said. Soon the water in the river will fall short of demands.

"We considered the question: Can the river deliver water at the levels currently scheduled if the climate changes as we expect it to?" Barnett said. "The answer is no."

This year's shortage of Sierra Nevada water is a hint of what is to come.

"We'll get a little taste of it this summer ---- of what the future is going to look like," Barnett said in a telephone interview Thursday.

In the future, as in the past, the economies of seven states will depend on the abundance, or lack thereof, of a river that flows 1,450 miles from Colorado's Rocky Mountain National Park to the Gulf of California.

California, Arizona, Nevada, Utah, Colorado, Wyoming and New Mexico, as well as a portion of northern Mexico, count on the river to slake the thirst of nearly 30 million people and to irrigate more than 3 million acres of farmland.

The majority of the people live in Southern California.

Lifeblood

The lifeblood of the Southwest was divided among the states in 1922. They split 15 million acre-feet in half between the lower and upper basin states. The lower basin is defined as California, Arizona and Nevada; the other four states comprise the upper basin.

Then, in 1944, the United States signed a treaty promising Mexico 1.5 million acre-feet a year.

An acre-foot is 326,000 gallons, or the amount of water two families use in a year.

Together, the agreements allocate 16.5 million acre-feet annually. The number is based on how much water flowed down the river during the early part of last century. Every drop is spoken for.

There's a problem, however. And it's a big one.

Those measurements were taken during a wet period. As the 20th century marched on, officials gradually discovered the river's flow averaged closer to 15 million acre-feet, which means there isn't enough to go around.

Luckily for the river, not every state takes its full share.

"It's oversubscribed, but it's not fully used at this point," said Bob Walsh, a spokesman for the U.S. Bureau of Reclamation in Las Vegas. "Mexico has been using its water. The lower basin is pretty much at full use. The upper basin is not there yet."

So the Colorado is still able to meet its commitments.

But officials acknowledge that, at some point in the future, the river will run short once growth really takes off in Colorado, Utah, Wyoming and New Mexico.

What the Scripps study shows, for the first time, said Barnett and Pierce, is that the day of reckoning is going to arrive sooner rather than later.

"Although it has been known for many decades that the Colorado River water was originally overallocated and that this problem would have to be addressed eventually," the authors wrote, "our results show this is no longer a problem for future generations to debate."

Tree rings and climate change

Here's why.

For starters, Barnett and Pierce determined that even the revised 15 million-acre-feet-a-year estimate is overstated. By studying tree rings, they learned that the 1900s constituted the wettest century in the last 1,200 years.

And the researchers concluded that a more reliable estimate of the flow is 14 million acre-feet.

That's a concern because users already draw 13.5 million acre-feet a year. And the number is on the rise.

Then there's climate change.

Climate scientists say the steady increase in the release of greenhouse gases such as carbon dioxide from cars, factories and power plants is creating an invisible blanket that is trapping heat and causing the planet to warm.

For California and the Southwest, a changing climate means not only a warmer future, but also a drier one ---- with up to 20 percent less water.

It means the river's flows will average between 11 million and 13.5 million acre-feet a year by the middle of this century ---- about the time upper basin states demand their full share, the report concludes.

By 2040, and as early as 2025, the Colorado River will deliver on average less than what is being asked of it.

"People have talked for at least 30 years about the Colorado being oversubscribed, but no one ever put a date on it or an amount. That's what we've done," Barnett said.

"What's that famous Clint Eastwood quote? 'A man's got to know his limitations.' It couldn't apply any more than it does now," he said.

Barnett said the study suggests that now, not later, officials must face politically difficult choices about how to live with less, possibly by limiting development, golf courses and backyard lawns, and moving toward seawater desalination on a large scale.

Of course, there are people in the scientific community who are skeptical about global warming, suggesting the planet isn't going to change as much as many scientists predict, if at all.

And Don Ostler, executive director for the Upper Colorado River Commission in Salt Lake City, said it is difficult for climate change models to pinpoint what will happen in small areas, such as the high peaks of the Rockies where most of the Colorado River's water falls as snow.

On the other hand, Ostler said, there is no denying the lengthy droughts of the distant past that show up in the tree ring records.

"We can see the dry cycles in those tree rings, and they are scary," he said.#

 

http://www.northcountytimes.com/articles/2009/04/20/news/sandiego/z040ff289e0fef1f38825759a00743245.txt

 

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