Isaac Parsons, 42, had a blood-alcohol level of 0.19 percent, more than twice the legal limit, Petaluma police Sgt. Ken Savano said.
Parsons told police he left San Francisco after Game 2 of the World Series and thought he was headed to Folsom but instead exited northbound U.S. Highway 101 at the East Washington Street exit, Savano said.
After stopping at a traffic light, Parsons accelerated through a T-intersection and drove his Ford F-250 pickup truck off the road into Washington Creek around 2:30 a.m., Savano said.
He was uninjured in the crash.
Police removed the truck from the creek and impounded it. Parsons was arrested on suspicion of DUI and booked into Sonoma County jail on $3,000 bail.