From the Gallatin County Sheriff's Office: 

Today, at about 5:30 this morning, the 911 center received a report from a motorist driving on Hwy 191 near the mouth of the canyon at mile marker 70. The passing motorist noticed a vehicle in the Gallatin River with a person standing on the roof yelling for help. The passing motorist called 911 and notified authorities.

The Gallatin County Sheriff’s Office, Sheriff’s Search and Rescue with the Gallatin Gateway Fire Dept, Montana Highway Patrol and AMR responded to the scene. First on scene Deputies were able to provide the stranded motorist with a PFD and a throw rope while Search and Rescue launched a boat to make the rescue. There were no other passengers in the vehicle.

The Montana Highway Patrol noted the vehicle was traveling north bound from the Greek Creek Campground. The driver lost control of the vehicle and drove off the west side of the road just before the bridge at the Gallatin River. The vehicle entered the water were it floated down river approximately 100 yards before coming to a rest. The driver crawled out of the vehicle to the roof where he yelled for help.

The Montana Highway Patrol noted that alcohol was a factor in the crash and the driver was arrested and taken to the Gallatin County Detention Center. The swift response of rescuers resulted in the driver being pulled from the river unharmed.