840,000 acre-feet is the amount of water New Mexico is allotted from the Colorado River each year, roughly 11 percent of the river’s total.

30 million  is the number of people who depend on the river who could experience water shortages if the Keystone XL shale gas pipeline is approved, according to a new study.

Every single drop that comes out of the [Colorado] River is already accounted for.—Serena Ingre, spokeswoman for the Natural Resources Defense Council

Predictions of a drying Colorado River Basin come often. In 2008, a study published in Water Resources Research predicted that the basin's two biggest reservoirs would dry up by 2021.

But a new study suggests extracting oil from oil sands will further stress the region's limited water supply. A report by the Natural Resources Defense Council focuses on the potential effect of the Keystone XL pipeline on the basin's resources. The proposed pipeline would import oil sands from Alberta, Canada, to Texas. The study concludes the pipeline would exacerbate the region's water shortage.

"The Colorado River is overextended in all uses that it currently supports," Ingre tells SFR. "If we move forward with oil shale development, the region needs to figure out where to get the extra water."

The pipeline would require extracting oil through strip mining, which Ingre says unsustainably heats rock until oil can be "squeezed out." The National Energy Board of Canada estimates approximately 2.5-4 barrels of water are used to produce one barrel of oil sands.

New Mexico is one of seven states that split the river's water through the Colorado River Compact.

If President Barack Obama approves the pipeline, Ingre says the region will have to develop water management plans to preserve the basin.

At the Washington, DC-based World Resources Institute, researchers are developing a "water risk atlas" that maps out regions around the world anticipating water shortages—including the Colorado River Basin.

Robert Kimball, a program coordinator with WRI, says a host of competing interests tap the river through complex interstate treaties and the many dams. The engineering of the river makes forecasting tougher to predict than natural flows, Kimball says.