The Sedro-Woolley woman crashed the 2007 Honda TRX 250 ATV while driving too fast under the influence of alcohol, according to the Patrol.
She was airlifted to Harborview Medical Center where is she is in serious condition, a nursing supervisor said.
She was headed north on Fruitdale Road before 6:30 p.m. when she passed a vehicle on the left in a no passing zone, the Patrol reported.
After she passed she re-entered the northbound lane before driving off the road into a drainage ditch where she struck a fence post.
The ATV rolled several times and she was thrown off it. It stopped after hitting a telephone pole.