BISMARCK, N.D. — A Montana businessman began mining gravel Tuesday near President Theodore Roosevelt’s historic western North Dakota ranch, after an eight-year battle with U.S. regulators and amid an ongoing legal dispute with environmentalists.

“We’re finally good to go,” Roger Lothspeich told The Associated Press. “I am very happy and very, very pleased.”

The 25-acre mine site is about a mile from Roosevelt’s historic ranch cabin, which environmentalists have called “the cradle of conservation.”

The mine is being dug in a 5,201-acre ranch owned by the U.S. Forest Service that is next to Roosevelt’s Elkhorn Ranch site. Although the Forest Service owns the land, Lothspeich of Miles City, Montana, owns the mineral rights.

Lothspeich had been in a dispute with the Forest Service since shortly after Congress approved the government’s purchase in 2007 of the ranch in a deal worth about $5.3 million. More than 50 wildlife and conservation groups, including the Boone and Crockett Club started by Roosevelt himself, pressed Congress to approve the purchase.

Lothspeich spent years proving he owned the mineral rights and offered to sell them back to the government or to environmental groups that opposed his project. Lothspeich signed an agreement with the Forest Service three years ago to work out an exchange for other federal land or mineral rights at a different location. But he said the government was too slow in responding, and he decided to mine gravel at the site instead to take advantage of a growing need for roads and other projects in North Dakota’s oil patch.

The Forest Service in January said it found no significant impact with the project, and on Monday it gave final approval for the plan and a 4-mile road to the mine. Lothspeich had crews digging at the site a day later.

“He’s got a valid set of permits, and he went through all the steps,” said Shannon Boehm, a Forest Service district ranger in nearby Dickinson. “We’re holding him to the tenets of the approved operating plan.”

The Chicago-based Environmental Law and Policy Center in September filed a lawsuit on behalf of the Washington, D.C.-based National Parks Conservation Association challenging the Forest Service’s decision to approve the project, and wants a more thorough environmental analysis of how the gravel pit affects the historic ranch. The lawsuit is pending in federal court.

“We’re hopeful the court will move quickly to require the Forest Service to go back to the drawing board,” said Bart Melton, a spokesman for National Parks Conservation Association.