Demand for water from the Colorado River is projected to outstrip supply by 2060, a study indicates.

The 163-page Colorado River study, released this week, is a three-year cooperative effort among the federal government and the seven states -- Arizona, California, Colorado, New Mexico, Nevada, Utah and Wyoming -- in the river basin as well as agricultural, environmental and tribal groups and water agencies who depend on the river for irrigation and drinking supplies.

The Colorado River Basin provides water to about 40 million people. By 2060, that figure is expected to increase to 49.3 million and perhaps 76.5 million people, under a high-growth scenario.

The study projects most of the increase in demand will come from municipal and industrial users, due to population growth.

By 2060, the study says, the water supply in the Colorado River and its tributaries will fall at least 3.2 million acre-feet short of demand and could be as much as 8 million acre-feet less than needed.

By way of contrast, 3.2 million acre feet are more than five times the amount of water annually consumed by Los Angeles. One acre-foot of water is approximately the amount of water used by a single household in one year.

Also by 2060, the flows in the Colorado and its tributaries will drop 9 percent from what they are today, the study says.

"There's no silver bullet to solve the imbalance between the demand for water and the supply in the Colorado River Basin over the next 50 years -- rather, it's going to take diligent planning and collaboration from all stakeholders to identify and move forward with practical solutions," U.S. Secretary of the Interior Ken Salazar said in a release.

Speaking on a telephone conference call, Salazar said that proposals such as piping water 600 miles from the Missouri River to Denver or towing icebergs from the arctic to Southern California aren't being considered.

Instead, a range of practical steps could be pursued, Salazar said, including desalination of seawater and brackish water, recycling and conservation by both the agricultural and urban sectors.

"This study should serve as a call to action," said Salazar, who was a U.S. senator from Colorado before President Barack Obama tapped him for the Interior position. "We can plan for this together."

Commenting on the study in his blog, Barry Nelson, senior policy analyst, Water Program for the Natural Resources Defense Council, warned that without a new approach, water users who rely on the Colorado River "could face an aquatic version of the fiscal cliff."

"Far-sighted elected officials and business leaders should join water managers and environmentalists in calling for ambitious, economically credible action in response to the study," Nelson stated.