UPDATE: 9:35 a.m.
According to CHP the semi-truck driver was driving with a blood alcohol level over the legal limit.
As a truck driver you are over the legal limit at .04 blood alcohol content.
The truck driver will lose his truck driving license, but can apply for a Class C license once he completes his DUI classes.
UPDATE: 6:10 a.m.
Highway Patrol now opening one lane of traffic as they work to clear overturned big rig from southbound Hwy 99 in Chico between Cohasset Road and East Avenue
An overturned semi-truck is blocking both lanes of southbound Highway 99.
The California Highway Patrol says it happened at around 11:30 p.m. Thursday in the area from the Cohasset Road exit and East Avenue exit.
We've learned the truck driver was able to walk away uninjured. He was later arrested for DUI. The truck was hauling a load of potatoes from Washington State to Los Angeles.
The California Highway Patrol is currently undergoing traffic control. It is advised that drivers avoid the area or expect delays.
There is no estimated time when the roadways will reopen. Check back as we continue to update this developing story.