Spokeswoman Melissa Yunas says the blasting in the rocky terrain at the northwest end of the fire was used to create the type of fire break that fire crews typically create by hand.
The lightning-caused fire has grown to cover nearly 14 square miles and is just 15 percent contained. It's being fought by more than 700 people.
The fire has burned six homes and 13 other buildings.
Smoke from a new fire in central Washington near Cle Elum was visible Friday from Interstate 90. That fire started Thursday and has grown to about 400 acres. It was not seriously threatening any homes.
More than 100 miles to the northeast, a wildfire burning on the Colville Reservation has grown to 16 square miles. It's just 2 percent contained.
Residents of about 40 homes have been told to leave and the fire threatens dozens of other homes.