A Kenwood woman who apparently fell asleep at the wheel of her pickup truck, drifting off Highway 12 and shearing of a utility pole early Thursday morning, was later arrested for suspicion of driving under the influence of methadone, a synthetic opioid, the CHP said.

Jean Wonnacott, 46, was traveling eastbound on Highway 12 in Kenwood at about 55 mph when she struck the utility pole at Randolph Avenue shortly after 6:30 a.m., the CHP said.

The impact of the crash sheared off the pole, dropping live power lines and telephone wires onto the highway below and closing both lanes of traffic for nearly three hours, authorities said.

Wonnacott had to be cut from the wreckage of her 1988 Nissan pickup and was taken to Santa Rosa Memorial Hospital for treatment of moderate injuries, the CHP said.

Officers at the scene said her seatbelt probably saved her life.

She was arrested for suspicion of driving while impaired but was released so she could be treated at the hospital, the CHP said.

Morning traffic was routed onto side streets during the nearly three hours that Highway 12 was closed.

They road was reopened at 9:24 a.m., the CHP said.