Feb 22,2007 00:00
Climate change and soaring population growth across the Southwest threaten to overwhelm the main water source for tens of millions of people, the National Research Council said Wednesday in a major report that synthesized decades of research on the
The potentially affected areas include
Historically, droughts across the desert Southwest may have been longer and more severe than scientists understood, the report's authors said. With the addition of global warming, the evidence strongly suggests that gradual temperature increases will further reduce the
The combination of factors "will inevitably result in increasingly costly, controversial and unavoidable trade-off choices," the council's researchers wrote. They are part of the congressionally chartered National Academies, which advises the government on science issues.
The council's findings were underscored by warnings in the report that conservation and technology likely won't be enough to offset the
For one thing, the report suggested the possibility of transferring more water from agricultural to urban areas.
The council also highlighted the need for ways to deal with climate change while reducing its impacts. However, it steered away from policy recommendations, saying that more study was needed.
"We better be prepared. That is the message," said Ernest Smerdon, chairman of the committee that wrote the report. He is a retired dean of the
The gloomy conclusions substantiate concerns among water managers in
The waterway's basin is showing the effects of a drought that started in 2000. Water managers don't predict supply shortages for this year, but it's harder to forecast beyond that.
Meanwhile, a 2006 report on the State Water Project - and the Northern California rivers that are the other main source of
"It's not something that we can bide our time (on) until we retire," state water chief Lester Snow said at a climate-change conference a few weeks ago in
Statewide, water officials are ramping up several efforts to address the West's changing water dynamics. Some of the plans are generating controversy due to environmental impacts. Others are expensive and would drive up the cost of water in
The Metropolitan Water District of Los Angeles, the leading wholesale water supplier for
"If you lose part of your water supply, then you need to replace it and (that's) almost always at a higher cost," said Roger Patterson, the agency's assistant general manager.
Down south, the San Diego County Water Authority is diversifying its portfolio by, for instance, purchasing more water from
"We are trying to prepare for the time that could come when there are shortages on the river," said Gordon Hess, director of imported water for the county water authority.
Wednesday's report was put together using dozens of research papers on the
Studies of tree rings show that the
Specifically, the report mentioned the 1922 agreement that apportions the river's water among the states that now share it. The researchers said that pact was based on exceptionally wet years, while recent years have been notably dry.
Global warming is likely to compound historic water variations, said Connie Woodhouse, a geography professor at the
Several climate models suggest a hotter future for the
"Droughts ... could get worse," Woodhouse said.