Las Vegas could save rivers' worth of water, but instead it is falling behind other Western cities in water conservation, according to a report from two conservation groups.

According to Steve Erickson of the Salt Lake-based Citizens Education Project, the findings call into question plans to pipe underground water from the Nevada-Utah border to the Las Vegas area. Conservationists and ranchers claim the water table could drop drastically, harming resources on both sides of the state boundary.

The report, "Hidden Oasis: Water Conservation and Efficiency in Las Vegas," was prepared by the Pacific Institute in Oakland, Calif., and Western Resource Advocates of Boulder, Colo.

The report concludes that "installing water-efficient fixtures and appliances could reduce current indoor water demand by 40 percent in single-family homes and nearly 30 percent in hotels and casinos."

If water-efficient landscapes were installed throughout the Las Vegas area, that could reduce the present outdoor water demand by 40 percent in single-family homes, the report adds.

"Many of these efficiency improvements can be implemented at a lower cost and with fewer social and environmental impacts than developing new water supplies," the report said. The entire report is available on the Web at pacinst.org/reports/las_vegas.

The report concludes that with the right steps, the Las Vegas area could save 86,000 acre-feet of water per year.

"We basically do science and analysis for policy purposes," said Peter H. Gleick, co-founder and president of the Pacific Institute. "We looked at the way Las Vegas uses water and their potential to reduce inefficient and wasteful uses of water."

Heather Cooley, senior research associate at the institute, said the potential water saving from homes, hotels and casinos "was equivalent to about 80,000 to 90,000 acre-feet a year."

That is a significant savings and was based on technological changes such as switching to front-end-loading clothes washers, using water-saving toilets and modern shower heads. "We looked at installing the appliances and fixtures that meet current national standards," she said.

According to Bart Miller of Western Resource Advocates, the water authority indicated "they're spending 14 times as much money in seeking out new supplies than they're spending on conservation." About 90 percent of the authority's conservation spending is on an outdoor turf replacement program, he added.