More than 6,000 firefighters battled the flames, which destroyed more than 1,000 homes, businesses and other structures.
Maynard is accused of setting the Cascade and Everitt fires, on 20 and 21 July, and the Ranch and Conard Fires on 7 August.
Investigators followed Maynard’s black Kia Soul car as they pursued their inquiries.
Agents with the US Forest Service started investigating him after the Cascade Fire was reported on the western slopes of Mount Shasta.
According to court papers, Maynard was found under the car, its front wheels stuck in a ditch and its undercarriage on a boulder.
When a second fire erupted on Mount Shasta the following day, investigators apparently found tyre tracks similar to those made by the Kia.