One of the country's largest environmental groups has accused the federal government of failing to follow pipeline safety planning laws, alleging that for more than two decades the Department of Transportation (DOT) has illegally allowed companies to operate oil pipelines that cross waterways without adequate preparation for spills and other disasters. The National Wildlife Federation, which filed a notice of its intent to sue on Tuesday, accused the Pipeline and Hazardous Materials Safety Administration (PHMSA), part of the DOT, of failing to properly enforce the Oil Pollution Act, enacted by Congress in the wake of the Exxon Valdez spill.