Levy Miller, 21, was being held in the Lemhi County Jail on $30,000 bond, officials said.
Miller, a Salmon resident, has worked for the local Bureau of Land Management office as a firefighter for about two years. He was charged in a blaze that charred a half-acre of brush in the Smedley subdivision on Aug. 13.
Police say Miller may have been trying to create work for federal fire crews.
Arson cases among firefighters are not uncommon. Former U.S. Forest Service firefighter Craig Matthew Underwood was sentenced to four months in prison and four months of home detention in July after pleading guilty to starting three fires in 2004 in the Los Padres National Forest in California.
Last year, Leonard Gregg, a firefighter for a tribal fire department in Arizona, was sentenced to 10 years in prison for starting the Rodeo Fire in eastern Arizona.