WASHINGTON — The Supreme Court today turned down an appeal from Indian tribes that wanted to block expansion of a ski resort on a mountain they consider sacred.

The justices said they would not get involved in the dispute between a half-dozen Western tribes and the Arizona Snowbowl ski area north of Flagstaff. The tribes wanted to block the expansion because the resort plans to use treated wastewater to make artificial snow on the mountain. The case is Navajo Nation v. Forest Service, 08-846.

The tribes have argued that the proposal violates a federal law on religious freedom, but the federal appeals court in San Francisco last year disagreed.

The full 9th U.S. Circuit Court of Appeals in San Francisco said the treated sewage could be used on the ski slopes, reversing the decision of a three-judge panel on the same court. The panel had held earlier that using wastewater on a mountain sacred to the tribes would violate the federal Religious Freedom Restoration Act.

The full court, however, also said the tribes would still have full use of the mountain for their ceremonies and that the snowmaking would not affect that. No plants would be harmed, no ceremonies would be physically affected and no places of worship would be made inaccessible, the court said.

The tribes asked the Supreme Court to step into the case and find that the use of treated sewage would constitute a "substantial burden" on the tribes' exercise of their religion.

The U.S. Forest Service earlier had approved the ski area's expansion. The Obama administration opposed the high court's intervention in the case, noting that the ski resort has been in operation for more than 70 years and that recent snowfall has been sporadic.

The tribes challenging the proposal are the Havasupai Tribe, the Hopi Tribe, the Hualapai Tribe, the Navajo Nation, the White Mountain Apache Nation and the Yavapai-Apache Nation.

The Hopi have been making pilgrimages to the peaks since at least the 1540s. The tribe directs prayers toward the peaks and considers them home to the spiritual Kachinas that bring the world water, snow and life. To the Navajo, the peaks are central to their creation story. Navajo members consider the mountain as family and greet the peaks daily with prayer songs.

The mountains include Humphrey's Peak, the tallest in Arizona, one of the only ski slopes within easy driving distance of Phoenix. One of the only alternatives is Sunrise Park Resort, which is owned and operated by the White Mountain Apaches.

Indian tribes have fought previous development plans by ski resort owners on Humphrey's Peak since at least the 1970s.