FLAGSTAFF, Ariz. (AP) – A federal judge on Wednesday upheld a decision by the U.S. Forest Service to allow snowmaking by using treated wastewater at a northern Arizona ski resort.

The ruling dealt a blow to environmentalists in their latest effort to stop snowmaking on the San Francisco Peaks – a fight that American Indian tribes lost in a separate yearslong lawsuit filed on religious grounds.

The Save the Peaks Coalition and a group of citizens sued the Forest Service in September 2009. They sought to have a judge force the agency to do a more thorough environmental assessment on the health and safety risks of using treated wastewater to spray artificial snow on the mountain that at least a dozen tribes consider sacred.

Snowbowl owner Eric Borowsky said he's pleased with the judge's ruling and that snowmaking equipment will be in place for next year's ski season.

"This is a vendetta by a vocal minority that is trying to close down the ski area,'' he said.

The plaintiffs' attorney, Howard Shanker, said any reasonable person who read the environmental assessment would disagree with the judge and vowed to appeal the ruling. He has likened a ski resort that uses treated wastewater for snow to a "test facility with our children as the laboratory rats.''

"The fact is that not even the government has a good grasp on all the contaminants that are left in this treated sewage effluent,'' Shanker said.

U.S. District Judge Mary Murguia in Phoenix said that the Forest Service adequately considered the impacts of the snowmaking plan and that the record supported the agency's decision to allow it.

"Although the plaintiffs have consistently conveyed to this court their desire that the agency had reached a different conclusion and determined that the potential risk to human health posed by the ingestion of snow made from reclaimed water during recreation is too great to approve the proposal, that is not the court's decision to make,'' Murguia wrote.

She also said the plaintiffs lacked diligence in failing to join the tribes' 2005 lawsuit. Instead, they waited until that one was resolved before bringing another lawsuit that she said has prejudiced the defendants, who might be subject to serial lawsuits.

The U.S. Department of Agriculture, which oversees the Forest Service, granted a permit in July for the construction of snowmaking equipment after a failed attempt to forge a compromise among tribal leaders and Snowbowl owners on the water source for snowmaking.

The city of Flagstaff later affirmed its original contract to sell treated wastewater to the ski resort.

Murguia previously agreed to a temporary injunction on any ground-disturbing activity at the resort, which expired Tuesday. Shanker said he'll again seek to halt construction at the resort until the appeal is decided.

A panel of the 9th U.S. Circuit Court of Appeals sided with tribes who asserted in the previous lawsuit that drinking water tainted by runoff from the man-made snow could pose health risks. The full court later overturned the decision, saying the plaintiffs never properly raised the issue in the lower court.

Brady Smith, a spokesman for the Coconino National Forest where the improvements are planned, said the agency would defer comment until it reviews the ruling.

Forest officials have signed off on plans to build a conveyor belt to ferry beginning skiers uphill and to clear an area north of one of the ski lodges.

About 205 acres of the 777-acre ski resort will have snow made from reclaimed water.

The Forest Service said while the use of reclaimed water for snowmaking is not considered hazardous for recreational skiing and snow play, signs will be posted to urge people not to intentionally ingest snow.