If the river runs dry - East Valley Tribune: News

If the river runs dry

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Posted: Sunday, June 27, 2004 6:49 am | Updated: 5:39 pm, Thu Oct 6, 2011.

East Valley water managers have long been a confident bunch.

Yes, we occupy one of the driest places on the planet. Yes, our highways resemble an inbound river of moving vans. Yes, we all know the mantra: "Water — Use it wisely."

But the people in charge of our water have seldom expressed any public worry about whether unbridled growth might outstrip our supply of the precious stuff. We’re not like other places with only one or two water sources, they have said. We are blessed with three, and our water supply is as sturdy as a three-legged stool.

What would happen, though, if someone took a saw to one of the legs?

That possibility has begun to loom in recent months, with federal officials talking ominously about cutting the East Valley’s share of Colorado River water as soon as 2006.

Two key factors are involved.

First, the West is suffering the worst drought in the 98-year recorded history of the Colorado River basin. Lake Powell, a huge reservoir on the Arizona-Utah boundary, now holds less than half the water it stored only five years ago. Lake Mead, between Arizona and Nevada, is only about half of its capacity.

Second, Western water law dictates that some Colorado River users are entitled to their full allocations even if others get no water at all. The East Valley would be one of the losers under that setup.

A WOBBLY STOOL?

Our share of Colorado River water — one leg of the proverbial stool — comes to us via the Central Arizona Project Canal, a $4 billion, 336-mile-long engineering marvel whose completion in 1993 was hailed as a godsend for our thirsty and booming state. It lifts water from Lake Havasu on the Colorado River, brings millions of gallons a year to the East Valley, then wends its way through Pinal County and on to Tucson.

The other two legs of our water supply are the Salt River Project’s system of dams and reservoirs on the Salt and Verde rivers, and a large aquifer that underlies the Valley.

Each of those could be affected if CAP deliveries were cut. The impact would depend on the extent and duration of the cutbacks — things that nobody can predict at present. It also would depend on the outcome of frequent droughtmanagement meetings now being held among federal officials and the seven Colorado River basin states.

Concern over the East Valley’s CAP supply bubbled to the surface this spring when Bennett Raley, the federal government’s top water official, made a highly publicized tour of the Grand Canyon.

Raley, an assistant secretary of the Interior and chief overseer of federal water policy, said then that the drought may force the government to declare a water shortage on the Colorado. "If current trends continue . . . the secretary (of Interior) would be forced to take action, certainly within three years and potentially within two," Raley said then.

CAP would be the most likely early casualty of such a declaration. When Congress approved the project in 1968, Arizona agreed the CAP would be designated as a "junior" user on the Colorado system. The CAP allocation — 1.5 million acre-feet per year — could theoretically trickle down to zero before, say, California, loses a single drop.

Of that allocation, the five largest East Valley cities — Chandler, Gilbert, Mesa, Scottsdale and Tempe — are entitled altogether to a little over 100,000 acre-feet per year. By itself, that would support only about a third of the East Valley’s current population.

The cities have not been using all that, however. Some of the current excess is being stored underground and some is being purchased and distributed by SRP to make up for shortages in its own watershed.

An acre-foot of water is 325,851 gallons. It would cover an acre of ground with a foot of water and is commonly regarded as the amount necessary to support a family of four for a year.

UNCERTAIN TIMING

Bob Barrett, a CAP spokesman, said a lot of things could mitigate the final impact, even if CAP does lose some of its water.

For one thing, it’s impossible to predict just when a shortage would be declared. "That’s like asking me how long a baseball game is going to be in total minutes," he said. While Raley said a shortage could be declared by 2006, Barrett said it’s "more likely in 2011."

Further, a turn in the weather could forestall a shortage altogether.

"It just depends on how many storms we get," he said. And by "we," Barrett is not talking about just Arizona. He means the entire Colorado River watershed, a vast area that stretches to Wyoming.

It appears, however, that dryness may be more the norm than the exception in the Colorado basin. When water planners divvied up the river back in 1922, they based their calculations on short-term measurements in a wetterthan-normal period. As a result, more Colorado River water is allocated than actually exists, to the tune of 3 million to 4 million acre-feet per year.

BACKUP PLANS

Even if CAP were to lose 500,000 acre-feet, a third of its allocation, Barrett said the short-term effect on East Valley cities and industries would be minimal. Agricultural users, he said, would lose their water first, and many of them could get by with groundwater until the CAP flow is restored.

Further, excess CAP water now stored underground could sustain current delivery levels "for some time," Barrett said.

But a cutback could affect the redundancy that has shored up the East Valley’s water supply for decades. Here’s one way to illustrate that:

In normal years, SRP gets enough water from the Salt and Verde rivers to meet its obligations across the Valley. But drought has forced SRP to cut its deliveries of Salt and Verde water by one-third for two straight years. It has been buying excess CAP water to make up the difference.

Since 1996, SRP has purchased well over 600,000 acrefeet of CAP water, said Charlie Ester, SRP’s manager of water resource operations. Roosevelt Lake, the utility’s biggest reservoir, now has only about 572,000 acre-feet in storage.

In theory, Ester said, that means Roosevelt Lake could have been drained by now without those CAP purchases. If CAP allocations are cut, SRP could lose access to that water. It would have to drain the Salt-Verde system even further, or begin large-scale withdrawals of groundwater.

PLANNING AHEAD

Water managers across the West, however, are struggling to prevent such scenarios. In that regard, Ester said, the drought could be a blessing in disguise.

"Maybe the basin states will come to grips with the fact that there are issues with the way the Colorado River has been allocated," Ester said. "Before you can grow in a prudent manner, you need to know what resources you have. Maybe that’s one of the good things that will come of this."

Tom Carr, who oversees Colorado River operations for the Arizona Department of Water Resources, said the seven Colorado River states have begun regular meetings, seeking to delay a shortage and to share the burden if one is declared.

"We have time to plan. We are beginning that planning right now," Carr said.

Dave Mansfield, general manager of water resources for Scottsdale, agreed. The earliest year he’s heard for potential CAP reductions is 2008. "We are a ways off in terms of seeing any reductions," he said, and he expects underwater storage of excess CAP water to help see the city through potential shortfalls.

Still, there are long-term worries. The Interior Department recently issued a report predicting increasing water conflicts throughout the West, and in Arizona, as the new century unfolds.

Rob Smith, Southwest field director for the Sierra Club, an environmental group, said the drought is an "early warning" about long-term problems across the West.

"We will come out of the drought cycle but the same problems will remain," he said.

"We are growing extremely fast in population. We don’t have enough water for everyone to irrigate cotton and have swimming pools and water features and live the sort of life we live now with low water rates."

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