SAN PEDRO, Calif.—The U.S. Coast Guard Dec. 28 announced that Southern California shoreline segments affected by an oil spill have been returned to their original condition. “The spill response will now enter a transition period; the Unified Command will monitor tarball and oiling incidents along with associated sampling results to determine the source of the oil,” according to a statement released by the U.S. Coast Guard. The United Command consisted of the U.S. Coast Guard, California Department of Fish and Wildlife Office of Spill Prevention and Response (CDFF–OSPR), the County of Orange, the County of San Diego, and the responsible party. “Once the Unified Command determines the transition period should end, the response will officially conclude and the U.S. Coast Guard and CDFW–OSPR will return to their standard pollution response posture as natural resource trustees,” according to the statement. The multi-agency response began on Oct. 2, after reports of an oil release began impacting Southern California. The U.S. Coast …