Forest Service district ranger Ron Jablonski said the agency determined that the project about 25 miles north of Medora poses no significant environmental impact.
Roger Lothspeich, of Miles City, Mont., and his fiancee, Peggy Braunberger, have spent most of the last decade proving they own the right to remove gravel and other surface minerals at the 5,200-acre ranch near Medora. The proposed 25-acre site is about a mile from Roosevelt's historic ranch cabin.
The couple signed an agreement in July 2012 with the U.S. Forest Service to work out an exchange for other federal land or mineral rights at a different location. But Lothspeich told The Associated Press on Monday that the government has taken too long to find him land.
"They don't have any land for me to swap, so I'm going to mine my gravel," he said. "I've got to get a return on my investment."
Lothspeich wants to take advantage of the growing demand for rock and gravel needed for roads and other projects in North Dakota's booming oil patch.
"Gravel is like gold right now in North Dakota," he said.
Jablonski has said Lothspeich's mine plan addresses air and water quality concerns, impact on wildlife, and other issues such as noise and dust.
"Our decision space is not very big on this," Jablonski said. "This man's got rights."
The Forest Service purchased the ranch next to Theodore Roosevelt's Elkhorn Ranch site from brothers Kenneth, Allan and Dennis Eberts and their families in 2007. It cost $5.3 million, with $4.8 million coming from the federal government and $500,000 from conservation groups. The purchase did not include mineral rights.
More than 50 wildlife and conservation groups, including the Boone and Crockett Club started by Roosevelt himself, pressed Congress to approve the purchase.
Roosevelt, who was president from 1901 to 1909, set aside millions of acres for national forests and wildlife refuges during his administration. He spent more than three years in the North Dakota Badlands in the 1880s.
The Ebertses had bought the ranch where Roosevelt ran his cattle and half the mineral rights from the Connell family in 1993 for $800,000. Lothspeich, who grew up near the ranch before moving to Montana, bought the other half of the mineral rights from the Connells at an undisclosed price, knowing the government had not obtained them in the Eberts deal.
Jablonski said his agency has since identified more than 40 other people who have mineral rights in the area and could potentially develop them.