A minor landslide caused the break in the oil fields near Faria Beach, about 10 miles northwest of Ventura.
Officials say about 55 gallons of oil flowed down the ravine and made its way to the sand.
Ventura City and County hazardous materials squads along with the Coast Guard were working with environmental health officials to clean up the mess.
The cause of the spill was under investigation. No reports of injured wildlife had been received as of Tuesday afternoon.