 In November 2007, BPXA pleaded guilty to negligent discharge of oil, which prosecutors said was the result of BP's knowing neglect of corroding pipelines,a misdemeanor under the federal Clean Water Act, and was fined US$20 million.In July 2011, BPXA paid a $25 million civil penalty, the largest per-barrel penalty at that time for an oil spill, and agreed to take measures to significantly improve inspection and maintenance of its pipeline infrastructure on the North Slope to reduce the threat of additional oil spills.In November 2012, it was announced that the U.S. state of Alaska would collect $255 million related to BP Plc's pipeline leaks and a resulting shutdown in 2006.