The Colorado River Basin is more prone to drought than had been thought, a panel of experts reported yesterday, and as the climate warms and the population in the region grows, pressure on water supplies will become greater.

The severe droughts the region suffered in the 1990s and early 2000s would not stand out in the record of the last few centuries, the panel said, and the future presents “a sobering prospect for elected officials and water managers.” The panel said residents of the region should prepare for more frequent and more severe dry spells, and “costly, controversial and unavoidable trade-offs” in water use.

The data discussed in the report have been published before in scholarly journals and elsewhere. But Ernest T. Smerdon, a former dean of the College of Engineering and Mines at the University of Arizona, who led the panel, said its members hoped with this publication to pull the findings into a single document that ordinary people could understand.

Severe droughts will recur, Dr. Smerdon said, “and we better be prepared. That is the message.” He spoke at a news conference yesterday in Las Vegas, where the report was made public.

The panel recommended an “action-oriented” study of water use patterns and demands, including drought planning, population projections and possible effects of transferring water to urban areas from agriculture, still the dominant consumer. Dialogue between policy makers and scientists who study water issues should be “a permanent fixture within the basin,” it said.

The panel, organized by the National Research Council, the research arm of the National Academy of Science, noted that the water allocation agreement for the basin, the Colorado River Compact, was negotiated in 1922 based on river flow records dating to the 1890s, when gauging stations were established. The agreement assumed that the annual river flow was 16.4 million acre feet — enough to cover 16.4 million acres to a depth of one foot.

But for some time, the panel said, researchers have known that the early 20th century was unusually wet and that 15 million acre feet was a more accurate estimate of the flow. Recent studies based on tree rings put the figure lower still — as low as 13 million acre feet — and suggest that “drought episodes are a recurrent and integral feature of the region’s climate.”

Because trees grow more when it is wet, scientists use tree ring size as an indicator of water abundance. The report says the federal Bureau of Reclamation and other agencies requested the panel’s review in the wake of the new findings.

Global warming is already making things worse, the experts said. For one thing, warmer weather means less precipitation in the form of snow, which is stored in the region’s mountain snowpack. And the snowpack itself forms later and melts sooner each winter. As a result, the steady reliability of snowpack water storage is compromised. Also, warmer weather itself increases consumer, environmental and agricultural demands for water.

Rainfall patterns are difficult to predict, another panel member, Connie A. Woodhouse, a geographer at the University of Arizona, said at the news conference. But the report said it was probable that the region would experience less precipitation over all in a warmer world.

Cloud-seeding, water desalinization and improved underground water storage have yet to emerge as solutions, the report said, and even conservation, while helpful, “is no panacea,” Dr. Smerdon said.

The report, which is available at www.nationalacademies.org, notes that the basin, 240,000 square miles in Wyoming, Utah, Colorado, New Mexico, Arizona, Nevada, California and Mexico, has seen rapid population growth in recent decades. Until about 30 years ago, the panel wrote, growing demands for water were met through building dams and reservoirs. But today, the report says, “prospects for constructing additional large dams in the Colorado River basin have diminished.”

Instead, “there is going to have to be some kind of reallocation of who gets the water,” said Richard Seager, a climate expert at the Lamont Doherty Earth Observatory, who was not involved in the panel’s report.

Dr. Seager, who studies the drought history of North America, said that it was “silly” to put golf courses in the region’s desert areas and that hotels and other businesses were already installing water-conserving toilets and other fixtures.

But he added, referring to cattle and cotton raising, “Let’s think whether it makes sense to have all this subsidized agriculture in the region, people who aren’t even paying the full cost of the water they do use.”

The U.S. Department of the Interior, which oversees the Colorado's management, is reviewing a drought plan the states put together last year.

Because California holds some of the most senior rights to the river, Arizona, Nevada and Mexico would all see cuts in deliveries before California, said Roger Patterson, the MWD's assistant general manager.

He said that under the states' drought proposal, there is only a 1% chance that shortages will fall to a level that will affect California.

The river is a major source for the MWD [Metropolitan Water District], Southern California's biggest urban water supplier. Last year about 30% of the agency's water deliveries came from the Colorado, which provides about one-tenth of California's overall urban and agricultural supplies.

Most of the state's river allotment — the largest in the system — goes to the Imperial Irrigation District, which distributes water to the sprawling croplands of the Imperial Valley, one of the nation's biggest lettuce producers.

Noting that farms remain the dominant water user in the Colorado River basin, the report called agricultural water "the most important and perhaps final large reservoir of available water for urban use in the arid U.S. West."

But that supply is also finite, the authors emphasized, and shifting water from farm to city can have negative impacts. Transfers can hurt rural economies, lower food production and rob wildlife of leaking irrigation water that nourishes important habitat.

The Colorado River Basin covers portions of seven Western states. The river has an average annual flow of 15 million acre- feet and supports tens of millions of Americans.

As the population boom continues, Western water wars will grow fiercer, water costs will rise and more agricultural water will be diverted to urban use, the report notes. Now, about 80 percent of Western water is used for crop production.

But "the availability of agricultural water is finite," and all signs point to a future "in which the potential for conflict among existing and prospective new users will prove endemic," the report says.

[...]

The new National Research Council document calls for further study of the Colorado River Basin but offers no solutions for the West's water woes.

"The Colorado River has been called the hardest-working river, but how much more work can it be asked to do?" said study co-author Kelly Redmond, a climatologist at the Desert Research Institute in Reno, Nev.

"The issue of limitations has to be confronted eventually, and it's just a question of which generation is going to take it on," Redmond said.

"Down the road, we'll either decide that the population cannot continue to grow inexorably, or we will have to go to greater and greater lengths to find (other sources of) water and move it to where the people are."

"There's not much in here that should be a surprise to anybody," Eric Kuhn, manager of the Colorado River Water Conservation District in Glenwood Springs, said of the new study.

"The big question is, will the water management infrastructure - meaning the big state and federal agencies - adopt it or dismiss it because it's telling them things they don't want to hear?"

River of trouble

The Colorado River has an annual average flow of about 15 million acre-feet of water. Several recent studies have concluded that the average flow will decline in coming decades because of climate warming. A look at different computer models' scenarios:

• 20 percent decreases were projected by the end of the century in a 2005 study.



• 14 percent to 18 percent declines were forecast over the next half century in 2004.



• 8 percent to 11 percent drops were foreseen by the end of the century in a study completed last year.

Land is one thing: a map can be carved up however you will, walls and fences erected, ownership enforced. But rivers don't dally, they cross boundaries and national borders. So do aquifers: tapped at one location, their level may be lowered far awar. How, then, can flowing water be owned?

In trying to apply our concept of ownership to a resource whose very nature runs contracy to the idea, we have a recipe for conflict. Damming of the course of a river denies this nature, and complex social factors enter the equation of relative benefits and drawbacks. Yes, we can confer fertility on famished lands and provide electricity to cities - but among the overheads are the displacement of populations, disease, pollution, catastrophic flooding, and armed conflict.

The tensions that arise from the management of water provide a good litmus test for the prevailing social climate in which it is conducted. According to social scientists John Donahue and Barbara Rose Johnston, systems for controlling access to and use of water resources typically recreate and reproduce the inequities in the societies that generate them. Historian Karl Wittfogel goes further: he saw that "it was as the arbiters of water that tyrannies annointed themselves as legitimate."

Philip Ball
Life's Nature: A Biography of Water (1999)
citing Karl Wittfogel
Oriental Despotism: A Comparative Study of Power (1957)

Water is (obviously) the basic necessity for human life and for sustaining civilization, so water wars are notoriously harsh, and not infrequently result in actual warfare. We're unlikely to see a civil war over water in the Amercian West break out, but the war of words will surely be severe.

(These articles don't mention that Mexico is a player in this drama as well. Because of treaties between the US and Mexico, the Colorado, which passes through that country on the way to emptying into the Gulf of California, is required to deliver a certain amount of usable water to Mexico every year. Because of the allocations to the Compact states, in drought years the river fails to meet that requirement, and that results in potable water being trucked from the US to Mexico in huge amounts, to fulfill our treaty obligations.)

Clearly, the easiest way to adjust the Compact would be to determine the river's actual flow, and adjust the amount each state is slated to get by the percentage of difference. But that's hardly the fairest way, considering that some states (such as Arizona) don't actually use all the water they're supposed to get, while other states (most notably California) use every drop, and more. Big users, like the MWD, which provides water for 26 cities in California, including Los Angeles and San Diego, and the Imperial Valley Irrigation District aren't interested in percentages, they're interested in actual acre-feet of water that they need to provide for their customer. Since the Los Angeles basin is semi-arid, and the Imperial Valley is a desert, this water is vital for their continued existence.

Of course, one could argue with the wisdom of having our second largest metropolitan area, with a population of 13 million people and rising, in an area which can naturally support only tens of thousands, or of growing crops like lettuce and watermelon, which require a lot of water in a desert, regardless of how fertile the soil is. Still, since 95% of our lettuce comes from California and Arizona, the fate of our salads, not to mention the continued existence of celebrities in revealing gowns on red carpets, seems to lie in getting the Colorado River Compact straightened out.

I shouldn't make light of this, because it really is a serious problem. Rational planning wouldn't have put all those people in Southern California, but that's the way it happened -- they're there, they're not going away (any more than the millions of people who live in the flood plains of our rivers, or in the path of hurricanes, or in tornado alley, or in earthquake country, or along the eroding coastlines are going away) and they have to be provided for. That may in some ways squelch the continued growth of Arizona and New Mexico, not to mention Las Vegas and the rest of Nevada (whose growth is intimately related to that of Southern California, considering it's where many people fleeing Los Angeles seem to end up, thereby re-creating the same urban sprawl they're trying to leave behind), but that's the current reality -- there's just not enough water in the west for everyone to continue growing at an unbridled pace.

Then there's the problem that neither Los Angeles nor Las Vegas are exactly circumspect about the way the use their water.

In the West, of course, where water is concerned, logic and reason have never figured prominently in the scheme of things. As long as we maintain a civilization in a semidesert with a desert heart, the yearning to civilize more of it will always be there. It is an instinct that followed closely on the heels of food, sleep, and sex, predating the Bible by thousands of years. The instinct, if nothing else, is bound to persist.

Marc Reisner
Cadillac Desert: The American West
and its Disappearing Water (1986)