Officials with the Tooele County Detention Center identified the suspect as 27-year-old Timothy West.
West is a former volunteer firefighter in Stockton.
The fire started Wednesday afternoon and grew to about 400 to 500 acres. It forced evacuations of about 20 to 30 homes.
Crews deployed fire engines, tankers, and helicopters to fight the blaze.
The town's water supply was contaminated when a structure that sits atop the town's water tower caught on fire. Residents were told to avoid using the water to drink or wash as it had been contaminated with chemical while crews fought to put out the blaze. On Friday, that order was lifted and changed to a boil order.
The Red Cross along with the LDS Church provided drinking water for residents at the LDS church and behind city hall.
Red Cross held an evacuation shelter located at the LDS Stake Center at 2053 S. 200 E. in Tooele for about 600 residents.
Fire officials say the fire is 75% contained. An aerial survey revealed it burned 179 acres, down from the original 500 acres reported.
Residents west of Silver Ave were allowed back into their homes Wednesday evening.
Evacuation order still in effect for homes east of Silver Ave.
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