In the 83 years since representatives of the seven Colorado River Basin states first divvied up the river’s water, there’s always been enough to meet the states’ needs. Not anymore. A relatively wet winter has done little to offset five years of the worst drought in the region’s recorded history, and Lake Powell and Lake Mead, the river system’s "backup batteries," are at less than half of their combined capacity. Representatives from the seven states are squinting hard at the fine print in the 1922 Colorado River Compact and arguing about what, exactly, will happen when there’s not enough water to go around.

A lot is at stake: Twenty-five million people depend on water stored behind the Colorado River dams, which are operated by the federal Bureau of Reclamation. If water levels drop low enough, U.S. Secretary of the Interior Gale Norton will declare a "shortage" on the river. The Central Arizona Project, which supplies water to Phoenix and Tucson, and Las Vegas, Nev., will be the first to lose their shares (HCN, 3/21/05: Arizona returns to the desert). If the drought deepens, Denver and its suburbs, which draw water from the Colorado River across the Continental Divide, may not be far behind.

Last December, Secretary Norton directed the seven states to come up with a plan for weathering a continuing drought. She warned that, without agreement among the states, she would be forced to impose new federal rules that would reduce water deliveries (HCN, 1/24/05: A crisis brews on the Colorado). That ultimatum touched off a series of meetings between the states this spring. But at the end of April, the talks ended in stalemate. All eyes turned to Norton, who did something no one expected: She blinked.

Low-flow negotiations
At the center of the struggle is Lake Powell, the uppermost of the two reservoirs. The Upper Basin states — Colorado, Utah, Wyoming and New Mexico — use the reservoir to meet water-delivery requirements to the Lower Basin states — California, Arizona and Nevada — and Mexico during dry years, rather than cutting off their own users.

During the meetings this spring, Colorado and Arizona, which under the complex calculus of the law of the river have the most at stake, fought a tug-of-war over how much water should be released from Lake Powell. Traditionally, the Bureau of Reclamation releases 8.23 million acre-feet of water every year from Lake Powell downstream to Lake Mead. (One acre-foot of water is about 326,000 gallons, a year’s supply for a family of four.) But in response to the drought, late last year Norton pledged to review the water conditions this April and determine how much water to release through the end of September.

The Upper Basin states, citing a long-standing difference in interpretation of how the river should be "operated," argued that Norton should reduce releases below 8.23 million acre-feet. They pointed out that the Lower Basin is already getting plenty of water, thanks to the first wet year since the drought began, which pumped twice as much as normal into Lower Basin tributaries.

"The release of 8.23 million acre-feet is not a number required in the compact," says Don Ostler, the director of the Upper Colorado River Commission. "It’s just a number that the Bureau developed … in about 1970." Upper Basin states maintain it’s simply a rough average that includes an ample cushion to ensure that downstream users won’t be shorted.

But Arizona and the other Lower Basin states argued for the standard 8.23 million acre-feet release. That would make more water available to Arizona, which could "bank" much of its share in underground aquifers for use in the future, as well as ensuring that Las Vegas’ water intakes in Lake Mead actually stay below the water.

The meetings between the various state representatives this spring only hardened their differences. Arizona Department of Water Resources director Herb Guenther says that, at one point, "We were going to hire a plane and tow a banner that said ‘8.23 or Bust’ over Hoover Dam." "Discretion," he says, dictated otherwise; he simply showed up at the meeting brandishing a gag "8.23" sign.

Betting against the future
Finally in late April, after the states failed to come up with a plan, they turned to Secretary Norton. On May 2, citing the slightly above-average snowpack this winter, Norton announced that the Bureau of Reclamation would deliver the full 8.23 million acre-feet this year.

The wet winter has, indeed, pushed the risk of a shortage declaration off to at least 2008. But long-term river flow models based on tree-ring studies show that the likelihood of continued, severe drought is fairly high. While nobody will be shorted water this year, Norton’s decision has placed the Upper Basin states at greater risk in the future by eroding more of their drought hedge in Lake Powell.

"The Upper Basin legitimately looks on Lake Powell as its insurance policy. As Powell drops, the risk of that insurance running out is heightened," says David Getches, the dean of the University of Colorado law school and an expert on Colorado River politics. "I think the Upper Basin states are rightly concerned."

The Interior Department will hold another meeting of Colorado River water users before the end of the month in an effort to devise a long-term strategy for dealing with the drought. When Norton made her May 2 announcement, she reiterated her authority to reduce releases from Lake Powell in the future, a signal that she may soon take a harder line on the river.

"(Secretary Norton) has enormous power over the river," says Getches. "I think she’s in a good position right now to say it could have been a lot worse for the Lower Basin, and it’s time for the Basin states to all get serious."

The author is HCN associate editor.