LOS ANGELES - The federal government on Wednesday ordered a company at the center of a Southern California oil spill to continue its efforts to clean up the pipeline breach that dumped crude onto a pristine stretch of shoreline and into the Pacific Ocean. The order from the U.S. Environmental Protection Agency (EPA) and the Coast Guard also requires Texas-based Plains All American Pipeline to submit a written plan by June 6 that will outline measures for analyzing the spill’s effects on the environment. The May 19 spill dumped as much as 2,400 barrels (101,000 gallons, or 382,000 liters) of crude onto a pristine stretch of the Santa Barbara coastline and into the Pacific, leaving slicks that stretched over 9 miles (14 km) along the coast. “Our action today is to make sure the oil response work continues until the Santa Barbara County coastline is restored,” Jared Blumenfeld, an EPA regional administrator, said in a statement. About 1,000 workers, including federal and state employees, are taking part in cleanup work. Two state beaches were closed indefinitely, along with fishing in the area. Coast Guard Captain Jennifer Williams, the federal on-scene coordinator for the response team handling the spill, said in a statement the order defines Plains All American as the “responsible party” and that government agencies would continue to work alongside the company on the cleanup. A representative for Plains All American could not be reached for comment. Also on Wednesday, conservation group the Center for Biological Diversity urged California regulators to reject a proposed expansion of the only offshore drilling operation still permitted in state waters along the Santa Barbara coastline, seizing on public outrage over the latest spill. Privately owned Venoco Inc is seeking permission to drill on 3,400 acres (1,400 hectares) of the sea floor within a state-designated coastal sanctuary adjacent to the company’s current offshore lease site. It said the plan would increase petroleum production by 6,400 barrels a day. Petroleum from Venoco’s rig ultimately is added to refinery-bound supplies that get pumped through the failed 28-year-old transmission line owned by Plains All American Pipeline. “It would be a grave mistake for the state to approve a project that will feed more crude into a pipeline system that just spewed thousands of gallons of oil into the Pacific,” said Miyoko Sakashita, the Center for Biological Diversity’s oceans program director. Denver-based Venoco had no immediate comment.