The spill was reported in the right lane at the midway point of the bridge, just west of the Contra Costa-Marin County line, at about 4:50 a.m., the CHP reported.
Crews from the California Department of Transportation responded to clean up the spill, according to the CHP.
Traffic was backed up to Novato during the closure, the CHP reported.
A Sig-alert issued at 5:15 a.m. was lifted at 8:39 a.m.
