A Border Patrol agent has been charged with a federal misdemeanor for starting the 47,000-acre Sawmill Fire 17 months ago that cost $7.3 million to fight.

Dennis Dickey has been summoned to appear Friday in U.S. District Court in Tucson on the charge of starting a fire without a permit.

If found guilty, Dickey could be fined up to $10,000, ordered to serve up to six months in jail or spend up to five years on probation.

Dickey, who was off duty at the time the fire began, admitted to a Pima County sheriff’s deputy that he unintentionally caused the blaze by firing a high-powered rifle bullet at an explosive target.

The fire started in April 2017 on state-owned land near Madera Canyon. It blew northeastward across the Santa Rita Mountains foothills, spreading to Forest Service and Bureau of Land Management lands, including sections of the Empire Ranch east of Arizona 83. It lasted about a week as nearly 800 firefighters from various agencies battled the blaze.

No homes were destroyed in the fire, but some households in the remote Greaterville and Singing Valley areas were evacuated. At times, hundreds of homeowners living in surrounding areas were under pre-evacuation orders. Arizona 83 was closed during the fire’s peak. The Empire Ranch’s historic buildings were spared, although some of its grassland and tall, aging cottonwoods were burned.

“Dickey started the fire by shooting at a target that he had constructed,” said Forest Service special agent Brent Robinson in an affidavit that was written last week in support of the summons and filed in federal court.

“Inside the target, Dickey placed an amount of Tannerite, an explosive substance, intended to detonate when shot by a high-velocity firearm bullet,” Robinson wrote. “Dickey fired the shot that exploded the Tannerite target, and the resulting explosion caused a fire that spread and resulted in damage to more than 45,000 acres of land, and that explosion was caught on film by a witness,” Robinson wrote.

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Tannerite is a legal, explosive compound.

“Dickey immediately reported the fire to law enforcement, cooperated and admitted that he started the fire. Dickey did not have a permit allowing him to cause timber, trees, slash, brush or grass to burn,” the affidavit said.

Sean Chapman, Dickey’s attorney, declined to comment on the case.

Cosme Lopez, a U.S. Attorney’s Office spokesman, said Wednesday that he doesn’t know if the federal government will seek restitution from Dickey to cover some of the expenses of fighting the fire.

The Border Patrol didn’t immediately respond Wednesday to a question from the Star about Dickey’s employment status.

Contact reporter Tony Davis at tdavis@tucson.com or 806-7746. On Twitter@tonydavis987