The flagpole and its cement anchor may soon follow the flag off the mountain.
A spokeswoman for The Church of Jesus Christ of Latter-day Saints confirmed that missionaries in the Salt Lake City East Mission installed the flagpole.
"The mission is looking into this and will address it appropriately," Jessica Moody said.
A Forest Service spokeswoman acknowledged the pole's installation likely violated federal law.
"You would need to get a permit to put up a flagpole [on Forest Service lands]. In wilderness it wouldn't be allowed at all," said Kathy Jo Pollock of Uinta-Wasatch-Cache National Forest.
A wilderness designation means no mechanized equipment or permanent improvements are allowed. There are no exemptions for patriotic displays and memorials.
A decade ago, Salt Lake City police had to retrieve a plaque they attached to the summit of Kings Peak, Utah's highest mountain, honoring the memory of their fallen comrade James Cawley, a detective and Marine reservist who was the first Utah soldier to die in the Iraq war.
President Lyndon Johnson signed the Wilderness Act into law nearly 50 years ago, establishing procedures for protecting scenic and biologically important landscapes "where the earth and its community of life are untrammeled by man, where man himself is a visitor who does not remain."
Several Wasatch and Uinta summits, including Kings Peak, were included in Utah's first major wilderness bill in 1984, setting aside about 750,000 acres of national forest.
The summit of Mount Olympus, perhaps the most visible peak in the Salt Lake Valley, is just a three-mile hike above Wasatch Boulevard. The trail is steep, ascending some 4,000 feet, but hikers can see freeways and Utah's largest city sprawling to the northwest.
The 9,026-foot summit hovering over Neffs Canyon is the cornerstone of the 15,300-acre Mount Olympus Wilderness, which includes Mount Raymond and Gobbler's Knob on the divide between Mill Creek and Big Cottonwood canyons. The area is some of Utah's most heavily used backcountry, thanks to its easy access from one of the Intermountain West's largest metropolitan areas.