LAS VEGAS - Facing dwindling water supplies, Western states are struggling to capture every drop with dam and diversion projects that some think could erode the regional cooperation crucial to managing the scarce resource.

Against that backdrop, eight Western governors meeting in Las Vegas this weekend will address regional water issues, and water managers from seven states arrive next week to work on ways to ensure that 40 million people in the parched Colorado River basin don't go thirsty.

Gary Wockner, a conservationist with the Denver-based advocacy group Save the Colorado, said there's already jostling amid the fear of empty buckets. "Everyone is trying to get the last legal drop of water," he said.

Colorado River Water Users Association representatives deny there's discord at their table.

"Fifteen years of drought has tightened everything. But I don't see this as people are getting ready to fight," said Jeff Kightlinger, general manager of the Metropolitan Water District of Southern California. That agency is dealing with a double-whammy - drought on the Colorado River and more in the Sierra Nevada and Northern California.

Nevada Gov. Brian Sandoval will host Western Governors' Association counterparts from Colorado, Idaho, Montana, New Mexico, South Dakota, Utah, and Wyoming this weekend to consider several issues, including water. Two days of drought workshops follow.

"The motto is, we save the system as a whole," said Pat Mulroy, longtime general manager of the Southern Nevada Water Authority in Las Vegas and now a senior policy fellow with the Brookings Institution. "If we get into 'I'm going to win' and 'You're going to lose,' there won't be a winner."

But Wockner said Colorado, Wyoming, and Utah are considering dams and diversions in the mountains to capture water they are entitled to before it reaches the Colorado and flows to the deserts.

"Diversions extract water from the system," said Jack Schmidt, professor of watershed sciences at Utah State University. He just completed three years studying the Grand Canyon for the U.S. Geological Survey.

"More water use and more water retention in the upper basin means less water flowing through the Grand Canyon to the lower basin."

Schmidt referred to the Colorado River Compact of 1922 and other agreements to share water with Mexico.

"You could say that we decided how to divide the pie, but the pie is smaller than anybody thought," Schmidt said. "With climate change, it is even smaller than that."