A blunt Nevada court ruling that could reverberate in Utah accuses the Silver State's top water official of making up data when he granted Las Vegas the right to pipe groundwater from a geographical basin that includes Snake Valley.

Judge Norman Robinson of Nevada's 7th Judicial District in Lincoln County struck down State Engineer Tracy Taylor's July 2008 decision to allow the Southern Nevada Water Authority to siphon millions of gallons of water per year from Cave, Delamar and Dry Lake valleys to feed Las Vegas growth.

"The State Engineer's decision was arbitrary, oppressive and a manifest abuse of discretion," says the ruling, which likens Taylor's assessment of the water potential in the valleys to printing money.

The Southern Nevada Water Authority plans to appeal the Oct. 19 ruling to the Nevada Supreme Court, agency spokesman Scott Huntley said Wednesday. Huntley said the judge had ignored 100 years of Nevada water law and appeared to display bias against Las Vegas during court proceedings.

Simeon Herskovits, the attorney who represented the Nevada ranchers suing Taylor and the state Division of Water Resources, predicted the appeal likely would fail. And that, he said, could doom Las Vegas's plan to build a 300-mile, $3.5 billion pipeline from Snake Valley, which lies mainly in Utah, to the desert megalopolis.

"If the water rights are eliminated in these valleys that are downstream [from Snake Valley] it's likely to make the project economically unfeasible," Herskovits said. "It will certainly make it irrational."

Opponents of a proposed Snake Valley water-sharing deal with Nevada said the court decision proves Utah doesn't need to rush to sign any agreement, especially because the judge said Taylor didn't have proof for his estimate of the Nevada valleys' perennial yield -- that is, the amount of water that can economically be pumped from the ground each year over a long period.

"You can't go with these estimated perennial yields when you don't have good science saying the water is available," said Steve Erickson, spokesman for the Great Basin Water Network, a coalition of conservation groups.

Taylor's ruling would allow the Southern Nevada Water Authority to take 18,755 acre-feet of water annually from three Lincoln County valleys that are part of the basin that includes Snake Valley. An acre-foot is about 326,000 gallons, enough to cover an acre of ground with a foot of water or provide for up to two households for a year.

The Las Vegas water utility wants to pipe 50,000 to 60,000 acre-feet from Snake Valley. Officials say 108,000 acre-feet per year could be pumped safely. Though both states insist the agreement would evenly divide the groundwater, the proposal would allow a 7-to-1 split of the valley's unallocated water in favor of Nevada.

Mike Styler, executive director of the Utah Department of Natural Resources, supports the agreement and would have the authority to sign it. He declined comment on Robinson's ruling Wednesday, saying he had yet to read it.

Water experts and ranchers say the Las Vegas pipeline could cause the entire basin's water table to drop far enough to kill off the vegetation that now holds the soil in place. That could send dust storms straight to the Wasatch Front and further escalate unhealthy air pollution levels.