"It's not nearly far-fetched that children will eat snow," Rawlinson said. Fletcher wondered how much snow a skier might accidentally ingest during a "faceplant."

Schneider said reclaimed water in Arizona is "used on children's playgrounds, church grounds and crops."

Hopi attorney Scott Canty said "the Hopi have revered this place, this mountain, for more than 1,000 years, where the Hopi have built their entire culture."

He said it was up to the deities, not man, to make snow.

"To usurp their authority is a crime, an insult," he said. "It desecrates the entire mountain that the Hopi believe is a living entity."

Jack Trope, a Hualapai attorney, said the man-made snow also could melt into a nearby spring the tribe uses for healing ceremonies. Once it touches the spring, he said, using those waters is akin to "committing spiritual malpractice."

The ski resort opened in 1937 and now gets minimal snow, allowing only 15 days of skiing last year. It hopes to get more than 100 days of skiing per season by making snow.

The resort sees some 4,000 skiers on busy days. The proposed upgrades would increase skiing from 139 acres on the resort to 205 acres, and would require more than 100 acres of forest thinning and grading.

Arizona Snowbowl is about 14 miles northwest of Flagstaff and 140 miles north of Phoenix.

The court did not indicate when it would rule.

The case is Navajo Nation v. U.S. Forest Service, 06-15371.