A man who drove a car off the road and caused a collision that seriously injured a passenger on North Whidbey last December is facing a felony charge, according to court documents.

Prosecutors charged 30-year-old Everett resident William F. Holtz in Island County Superior Court Dec. 18 with vehicular assault.

Holtz was driving a Ford Ranger with two passengers on the night of Dec. 18. Traveling north on Jones Road, the vehicle left the roadway at a curve, continued through a grassy area, struck a large bolder, became airborne, went down an embankment and overturned, finally coming to a rest back on its wheels, the police report states.

A man who was riding in the bed of the truck was ejected during the crash. He suffered fractured vertebrae, a fractured sternum and fractured ribs. The other passenger had a laceration to the scalp.

A trooper with the Washington State Patrol detected an odor of intoxicants on Holtz and obtained a warrant for a sample of his blood, the report states. Six months later, the officers received the results of the tests.

According to court documents, Holtz’s blood-alcohol level was 0.17, which is more than twice the legal limit of 0.08. The level of THC in his blood was 5.4 mg/ml; the state set the limit at 5 mg/ml.