Heavy traffic is expected during the evening commute.
The northbound lanes were shut down after a crash involving a fuel tanker and another big-rig around 6:30 a.m.
The collision, which happened north of state Highway 116 in Cotati, caused a significant amount of fuel to spill from the tanker, CHP Officer Jon Sloat said.
The fuel tanker was stopped in traffic when another big-rig swerved to avoid it and clipped a fuel pipe or piece of equipment on the tanker, Sloat said.
Between 1,200 and 1,500 gallons of fuel spilled, and the fuel will have to be sucked from the roadway before it is known whether there is enough damage to require repaving, Sloat said.
Traffic was diverted onto Highway 116 and back onto northbound Highway 101 at Rohnert Park Expressway, Sloat said.
Construction is under way in that area for a roadway-widening project.
No injuries were reported in the crash.
