Western U.S. states face the challenge this week of how to squeeze every useable drop from the overtaxed Colorado River that flows into Mexico as worries about water supply grow in the largely dry region.
The U.S. interior secretary five months ago declared that the river — already described as the most plumbed and regulated in the world — would be unable to meet demands of a growing regional population over the next 50 years.
"We're looking at a very significant chance of declaring a shortage in the Colorado River basin in 2016," Michael Connor, commissioner of the Bureau of Reclamation, said in an interview.
Connor heads the federal agency responsible for what he called the most litigated and fought-over resource in the U.S. He said data projects 2013 will be the fourth-driest year in the Colorado River basin over the past 100 years. Last year was the fifth-driest year on record.
The river provides drinking water, power and recreation for some 40 million people in California, Arizona, Colorado, Nevada, Utah, New Mexico and Wyoming. Its largest reservoirs — Lake Mead near Las Vegas and Lake Powell in Arizona — are projected to drop to 45 percent capacity by September, Connor said.
U.S. and Mexican officials signed a pact in November for new rules on sharing Colorado River water, including a deal that lets Mexico store water in Lake Mead. The deal provides for international cooperation to ensure that river water reaches the Gulf of California for the first time in decades.
The recent report said that by 2060, with the Southwest's population expected to swell, the river won't be always able to serve all the residents, businesses, ranchers, Native Americans and farmers who rely on it.
When the Colorado River was tamed by dams and canal water allocations were made nearly a century ago, agricultural interests gained broad water and irrigation rights that helped transform California's vast arid Imperial Valley into one of the most productive winter fruit and vegetable, cotton and grain farming regions in the country.
Tension has grown in recent years along with the sprawl of thirsty cities including Denver, Los Angeles, Las Vegas and Phoenix.
Tuesday's meeting comes two months after an annual report by the advocacy group American Rivers labeled the Colorado River the most endangered waterway in the nation.
Jennifer Pitt, head of the Environmental Defense Fund's Colorado River Project, said environmental groups want to see more water banking, along with more efficient use of existing urban water supplies, the reuse of waste water, better watershed management and improved agricultural techniques.
"Communities that depend on the Colorado River — for water supply or as the foundation of a $26 billion recreation economy — cannot afford to wait," Pitt said in a statement.