The risk assessment is integrated with the SECURE Water Act, legislation passed in 2009, in which Congress determined there should be a full-scale report on the Colorado's water supply.
According to the first report under the SECURE Water Act, "As the effects of climate change and snowpack are realized throughout the Colorado River Basin, these effects will drive changes in the availability of natural water supplies."
Earlier independent research also shows that with climate variability, risks to the precious Colorado water resources increase.
"Virtually all the climate models suggest there will be a reduction of inflows in the river. It could be 10 to 30 percent," said Tim Barnett of the Scripps Institution of Oceanography, who published a report on the Colorado River in 2009. "It's not a problem you can cavalierly say, 'We will worry about this in 20 to 30 years.'"
The year of a little relief
Lake Powell, largely in Utah, and Lake Mead, along the Nevada-Arizona border, account for approximately 85 percent of the Colorado River's water storage capacity. Wet years come as a huge relief to the reservoir managers, but when the lakes get low, tensions start to run high.
"We had such a large hole in that reservoir, such a large amount of available capacity, that the water has been very welcome," said Richard Clayton, who operates Lake Powell for the Bureau of Reclamation.
"It's been a banner year for us at Lake Powell. We're going to see over 50 feet of filling from the low point, and year over year, we're going to see a net gain of 20 feet," said Clayton. "It doesn't seem like much, but it is. It's great for recreation, power supply; there are a lot of smiles because of how wet this year has been."
There are only two years -- 1983 and 1984 -- that have had more unregulated inflow than in 2011. This stands in stark contrast to less than a decade ago, when in 2002, the flow was as low as it has ever been in the history of Lake Powell, beginning in 1963.
The spring runoff has been so great it has even overwhelmed some northern areas of the basin, where authorities are still trying to assess the damages caused by flows that were 160 percent higher than average. In some places, the water caused lowland flooding and bank erosion and lapped up against the underbellies of bridges, restricting access to roadways, said Aldis Strautins of the Grand Junction Weather Forecast Office in western Colorado. Over July, the water levels have steadily receded.
Farther downstream, Lake Mead is also experiencing high water flows and levels. However, the reservoir will still be only 57 percent full by December 2011. This will take it 50 feet higher than last year, when the lake was at an elevation of only 1,083.8 feet -- had it dropped to 1,075 feet, it would have triggered a shortage declaration and forced Nevada and Arizona to curtail their use of the Colorado River.
Still struggling to reach the Sea of Cortez
To curtail the drain on the Colorado River, there have been some improvements in consumption practices. The Southern Nevada Water Authority, for instance, created a Water Smart Landscapes Rebate, which has helped convert 150 million square feet of lawn in the Las Vegas Valley into water-efficient landscaping. The project has saved the area billions of gallons of water.
Conservation efforts have also led to overall savings. According to a report by the Pacific Institute released in June, 28 water agencies in five separate states delivered less water in 2008 than they did in 1990, despite population and industry growth.
But continued population increases, coupled with the drains of development, farming and recreation, plus the impacts of climate change, have meant that more conservation needs to take place while there's still time to do it.