DENVER (AP) -- A $500,000 study shows the "Big Straw" water project to move Colorado River water from the Western Slope to thirsty eastern Colorado cities and towns could cost up to $15 billion.

It also would take 27 years to build and carry high environmental costs, according to a copy of the report obtained by The Denver Post.

The report by Boyle Engineering of Lakewood is scheduled to be reviewed by the Colorado Water Conservation Board at a meeting on Thursday.

There are five possible routes for the project and three locations from which Colorado River water could be siphoned for the state's growing and thirsty Front Range and eastern plains cities and towns.

One proposal would divert water from the environmentally critical Colorado Canyons National Conservation Area near Grand Junction, the report said.

Lawmakers commissioned the assessment earlier this year, and it leaves legislators to deal with the difficult questions of engineering and environmental impacts, as well as how to pay for it.

The project would cost between $3.8 billion and $15 billion, depending on its route and other factors, according to the study.

The report suggests hydroelectric power could help offset the sticker shock.

With much of the West still in a drought, Colorado is trying to find ways to direct its water to areas where consumers want it. The proposed pipeline would pump billions of gallons from near the Utah border 200 miles east to the Eagle River basin to be used on farms, and in industries and homes.

Big Straw opponents said the report doesn't surprise them, and it doesn't convince them.

"Yeah, it's feasible to build it if you find $15 billion to pay for it, if you can pony up for the environmental mitigation, if you can deal with the endangered-species issues, if you can build the power plant to pump it, if you can figure out how to deal with the water treatment," said Melinda Kassen, a lawyer and director of Trout Unlimited's Colorado Water Project.

State Rep. Diane Hoppe, R-Sterling, who carried the legislation to fund the study, supports the Big Straw in spirit.

"I think, number one, (the study) is going to show it's a very expensive proposition," Hoppe said. "(But) at some point in Colorado's future, it may be the only alternative we have" to capture water Colorado is entitled to that is leaving the state.