"Really, the main underpinning of this is not just supply side, but also demand side," Huntley said.

"First, we continue to monitor the lake levels to determine if states need to come back together for more dramatic and drastic measures," he said. "Second, we diversify our water sources. Third, of course, is continuing our community's efforts to conserve."

The December agreement established triggers that would reduce river water deliveries to states if Lake Mead's water level falls to 1,075 feet above sea level. It also calls for states to create agreements for further restrictions if the level drops to 1,025 feet. The current lake level is 1,117 feet.

Arizona Gov. Janet Napolitano said that while the Scripps findings differ from the Central Arizona Project's, she agrees with the fundamental point made by Scripps, "which is to say that as our population grows, sustainability is going to require action with respect to water."

"We're still the second-fastest growing state in the country and we still have to be planning on that in terms of sustainability, which is a good concept," Napolitano said. "Water needs to be a part of that, obviously."

Launce Rake, a spokesman for the Progressive Leadership Alliance of Nevada in Las Vegas, said the issues of water usage and population growth are often overlooked in a rush to meet the needs of the influential building and development industry.

"Developers have an inordinate amount of clout with our elected leaders," he said. "They have dictated our growth patterns and our water use for years. That's got to end."

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Contributing: Paul Davenport, Ken Ritter