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April 30, 2001
Unending water fight
CAP supply could dwindle, and Arizona stands to come up short
By Mitch Tobin
ARIZONA DAILY STAR
When Mayor Bob Walkup flips a switch on Thursday, Tucson will once again dip its straw into one of the most bitterly contested and elaborately engineered rivers on Earth.
The Colorado River, whose muddy torrent carved the Grand Canyon for eons before dams tamed its flow, is now the lifeblood for more than 25 million people in the Southwest and Mexico.
In this fast-growing region spanning two nations, each with a new president, Tucson faces plenty of uncertainty and thirsty competitors when reaching for the Colorado via the 336-mile Central Arizona Project canal.
COLORADO RIVER SYSTEM: A BRIEF HISTORY | 1922 |
The Colorado River compact is approved, allocating 7.5 million acre-feet to California, Arizona and Nevada, and the same amount to the Upper Basin states. Arizona doesn't sign on until 1944. | | 1928 |
Boulder Canyon Project Act is approved by Congress. Besides authorizing Hoover Dam, it divvies up the lower basin states' 7.5 million acre-feet. California gets 4.4 million acre-feet, Arizona gets 2.8 million acre-feet, and Nevada gets 300,000 acre-feet per year.
| | 1945 |
The U.S. Senate approves a treaty with Mexico to deliver it 1.5 million acre-feet of Colorado River water annually.
| | 1947 |
Arizona Sen. Ernest McFarland introduces a bill in the U.S. Senate to build the Central Arizona Project. California resists.
| | 1952 |
Arizona sues California in the U.S. Supreme Court to affirm its right to 2.8 million acre-feet of Colorado River water per year. California believes the flow of the Salt, Verde and Gila rivers in Arizona, which are part of the Colorado's watershed, should be deducted from its allocation of 2.8 million.
| | 1963 |
The Supreme Court rules in favor of Arizona and clears the way for Arizona to seek congressional authorization of the CAP. The interior secretary is given the power to serve as water master of the Colorado. |
| 1968 |
President Lyndon B. Johnson signs the Colorado River Basin Project Act, which includes $3.8 billion for the CAP.
| | 1973 |
Groundbreaking for the CAP takes place on the shores of Lake Havasu.
| | 1985 |
The first Colorado River water is delivered through the CAP to the Harquahala Valley Irrigation District in western Arizona. The 190-mile-long Hayden-Rhodes aqueduct is completed from Lake Havasu to the Salt River near Phoenix.
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Click to enlarge: Colorado River Basin |
Local officials may herald the return of CAP water to Tucson as the end of the city's "water wars," which featured a pair of controversial ballot measures during the 1990s.
But while debates about how Tucson should use its share of the Colorado have quieted for now, water experts predict that conflicts over the river's scarce supply won't melt into the sunset.
Parts of the Southwest still get less than 3 inches of rain each year, and the Census Bureau projects 13.5 million more Americans will live in the region by 2025.
In addition to the water demands of booming cities, global warming and environmentalists' dreams of restoring the Colorado Delta in Mexico promise to complicate the picture.
"We've avoided the headlights in the tunnel because lots of water rights haven't been used yet," said Robert Glennon, a University of Arizona law professor who teaches a course on the Colorado. "At some point, the headlights will be here, and it's not clear what will happen."
The enduring problems of water in the West once inspired plans to tug icebergs from the Arctic to Los Angeles, pump Mississippi River water here using nuclear power plants, and divert the Columbia and Yukon rivers south.
Those ideas are dead - at least for now. And until desalinization of sea water becomes cost-effective, the Colorado will remain the region's most sought-after and fought-over water source.
Following a drop of Colorado River water on its 1,700-mile journey from the glaciers of Wyoming to the Gulf of California reveals four of the tensions lurking on the horizon:
Eye on the snowpack
Starting Thursday, Tucson's water future will partly depend on the Rocky Mountains snowpack.
Melting snow provides 87 percent of the Colorado River supply - which is just 3 percent of the Mississippi's volume.
But hydrologists remain uncertain about how much water the Colorado will deliver in the future.
Tree ring studies conclude the 242,000-square-mile basin has suffered extended droughts, the likes of which haven't been felt in modern times.
Most climate experts believe global warming will affect the region's water supply, but they still haven't determined how changing rain totals, snow levels and evaporation rates will tip the balance.
Even small variations in the river's long-term average flow are critical because the Colorado is already oversubscribed. In 1922, when the river was divided among the basin's seven states, government officials looked at the previous few years of data and estimated its flow at 16.5 million acre-feet per year. (An acre-foot is 325,851 gallons, about what a family of four uses annually.)
But they goofed. The decade preceding the 1922 agreement was the wettest period on record. Subsequent studies have pegged the river's true long-term average closer to 13.5 million acre-feet per year.
One recent study by UA and government researchers predicts the Southwest will get warmer and wetter over the next 100 years. But global warming models lose accuracy as they focus in on specific regions, especially one with complex topography like the Southwest.
UA hydrologist Roger Bales, an expert on the West's snowpack, said his preliminary research suggests the region will have "noticeably less" winter precipitation in the next century.
"I'm not ready to set public policy on that," he said. "But neither am I ready to say things will be fine."
UA hydrologist Soroosh Sorooshian noted that if added rainfall is light, it's more likely to seep into the ground rather than run to the river. And even if the region is wetter, warmer temperatures could create higher evaporation rates and smaller snowpacks that decrease the river's volume.
Banking for Vegas
In 1857, when Lt. Joseph Christmas Ives sailed up the Colorado to a point near today's Las Vegas, he wrote, "Ours was the first and will doubtless be the last party of whites to visit this profitless locale."
Such foresight could cost you a pretty penny in the Strip's casinos.
Powered by electricity from Hoover Dam and quenched by its reservoir, Lake Mead, Las Vegas has become America's fastest-growing city. In the past decade, its population mushroomed 85 percent to 1.4 million.
But when the Colorado was divided in 1922, Las Vegas was a cow town. Nevada only got 1.7 percent of the river's flow.
With its Colorado allocation nearly tapped out, southern Nevada officials are desperately searching for more water.
One place they've found some is in Arizona.
In a process known as "water banking," Arizona will store about 1.2 million acre-feet of its Colorado allocation in the next decade for Nevada's future use.
Details are being finalized, but the process will likely work this way: Arizona, which has customers for only about two-thirds of the CAP aqueduct's capacity, will pull off water for Nevada and store it in underground basins. Nevada will pay the entire cost of banking. It will then get the right to use a portion of Arizona's Colorado allocation in later years while Arizona pumps what it stored for Nevada.
In the long term, Nevada is looking to ground water and streams near Las Vegas for alternative supplies.
What's in the deal for us?
Arizona officials note that playing good neighbor to Nevada reduces the chances it will try to renegotiate the "law of the river" - the complex body of rules that governs the Colorado.
Tim Henley, manager of the Arizona Water Banking Authority, said that with Nevada becoming a full-paying customer of CAP, Arizona will reap millions of dollars in revenues.
"If it hurt Arizona, we wouldn't be doing it," Henley said.
But not everyone is a fan of the program.
Tucson lawyer Steve Weatherspoon, a CAP board member, worries it will be hard to wean Nevada off Arizona's water and thinks Arizona should bank more water for itself.
"If Nevada had such great alternatives, they wouldn't be coming down here to us," he said. "It makes me nervous. Who knows what kind of political power Las Vegas will have in the future?"
Henley counters that Arizona already banks more than 300,000 acre-feet annually for itself and says that adding more would be like buying too much insurance.
In the coming years, a similar banking deal may be worked out with California, he said.
California's water diet
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Jeffry Scott / Staff
The Central Arizona Project canal winds toward Picacho Peak on its way to Tucson, where residents soon will be drinkng water carried 336 miles from the Colorado River.
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Southern California is no stranger to dieting.
For the next 15 years, the river's biggest water user will have to call on that tendency to reduce its ravenous appetite for Colorado River water.
For years, the region's political powerhouse has used far more than its 4.4 million-acre-foot share, sometimes drawing an extra 800,000 acre-feet.
California's overuse has been possible because the four upper-basin states - Colorado, Utah, Wyoming and New Mexico - are using only about half their allocations.
But as California has taken more than its share, other states have worried that the overuse will become entrenched and prevent them from getting their full allotments in the future.
To solve the problem, then-Interior Secretary Bruce Babbitt helped broker a deal last year that forces California to return to its legal limit.
During the next 15 years, a water surplus will be declared on the river, even if none exists. California is supposed to draw a decreasing amount and achieve a "soft landing" at its allocation by 2016. If nature doesn't provide a surplus, Lakes Mead and Powell will be drained - up to a point.
Other states agreed to the "soft landing" plan because they recognize California's congressional clout. It now has 53 seats in the House of Representatives, while the other six basin states have 22 combined. In the Senate, however, California is outnumbered 12 to 2.
If river water shortages occur before 2016, California suffers the first 1 million-acre-foot deficit. But after that, the previous rules are reinstated, in which Arizona's CAP allotment has the lowest priority among lower basin users and is cut first.
"Anytime there's a shortage, CAP takes the first hit," said CAP spokesman Bob Barrett. "It's why we take these issues so seriously."
In total, California has enough water to satisfy its booming coastal cities. But most of the water goes to farms in the Imperial and Coachella valleys near the Colorado. And in California, farmers' water rights take precedence over cities'.
The challenge is for California to "find the political mechanism" to shift its water use from farms to cities, Tucson Water administrator Dennis Rule said.
That shift will occur more easily in Arizona, where cities' water rights trump those of farms.
Tucson Water doesn't expect to face shortages of CAP water for 20 or 30 years. And when cutbacks happen, agriculture will suffer before cities. However, Rule said that during such shortages the utility may get only 80 percent of its CAP allocation.
That could force the city to impose conservation measures and return to greater dependence on its ground-water wells, Rule said.
"Tucson's lucky," noted Deputy Director Marie Pearthree. "We've got two systems, so if something happens to one, we have the other."
Restoring the delta
After dropping 13,000 feet from its farthest headwaters in Wyoming's Wind River Range, the Colorado River reaches the Gulf of California in Mexico. This is where the innards of the Grand Canyon and countless tons of sediment from elsewhere were deposited in a fan-shaped delta.
Before the dams and diversions of the 20th century, the area supported millions of acres of junglelike habitat. Ecologist Aldo Leopold visited in the 1920s and described the delta as a "milk-and-honey wilderness" crawling with jaguars.
Now, just a trickle of water reaches the delta, and most of the area has been denuded of vegetation. Besides hurting the delta's wildlife, the effects of tapping the Colorado have reached far into the Gulf of California, affecting Mexico's shrimp fisheries and threatening marine species, biologists say.
Last year Mexican and U.S. environmental groups sued the U.S. Bureau of Reclamation, manager of the Colorado's flow. They contended the agency was violating the Endangered Species Act and demanded it release more water to the delta. Federal officials, however, contend the law's reach ends at the border.
Although nobody expects the delta to ever return to its former state, researchers such as the UA's Ed Glenn believe a small, continual supply of water - plus periodic surges - could do wonders for the area's environment.
But finding water to spare for the delta is no easy task.
"I don't think anyone is opposed to that," said the CAP's Barrett. "But who's going to give up their water?' "
Even if U.S. interests agree to send more water south of the border, skeptics argue that Mexican farmers would intercept it before it reached the delta.
"There are no ironclad guarantees," said Robert Varaday, deputy director of the UA's Udall Center for Studies in Public Policy and an expert on U.S.-Mexico environmental issues. But Varaday noted that new Mexican President Vicente Fox's appointments to key Cabinet posts suggest a heightened commitment to ecological issues.
In December, the United States and Mexico agreed to study the delta and explore ways to deliver more water to the region.
Tucsonan John Bernal, former commissioner of the International Boundary and Water Commission, signed the pact.
"It's a small step, but an important one," said Bernal, now a public works administrator for Pima County. "At least the two governments are expressing interest to work together. But I don't know where this will go."
* Contact Mitch Tobin at 806-7739 or
by e-mail at mtobin@azstarnet.com.
Find out more about the CAP at its own Web site.
Tucson Water is the delivery source for CAP water, and more.
Get the view of opponents of adding CAP water to local mains.
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