UPDATE - Wednesday, July 29, 2015 at 8:38 p.m.
The Santa Barbara County Fire Department said Wednesday night that the U.S. Coast Guard has determined Wednesday's three-mile-long oil slick off the coast of Goleta was caused by natural seepage.
The county will continue to monitor the sheen's drift in the channel. All Santa Barbara County beaches and parks are open normal hours, as is fishing from the Goleta Pier.
Investigators were called in to determine the slick's source because its large size was cause for concern.