Officers say the woman was driving a Toyota Corolla on Road 16 south of Avenue 5 Saturday morning when she lost control of the vehicle.
The car left the road and slammed into two pistachio trees.
The woman was rushed to a hospital with major injuries.
The California Highway Patrol says she was wearing her seatbelt, and at this time, drugs and alcohol are not suspected to be a factor.
Officials are investigating what led to the crash.