The Bush administration defended itself yesterday against charges of neglecting the national park system, saying it has spent billions to maintain and repair parks around the country. According to U.S. Interior Secretary Gale Norton, $2.9 billion has been spent on a maintenance and repair backlog and 900 related projects have been completed; in addition, she said, the department is conducting an inventory of the needs of 7,500 facilities at the nation’s 388 parks. Those and other indicators demonstrate “the extent to which we are doing an excellent job in taking care of the parks,” her report to the president claimed. But critics disagreed, saying the progress report was just an attempt to save face after the National Parks Conservation Association gave the Bush administration a D- last month for its neglect of the national park system. They questioned the increase in funds available for park repairs and noted that administration policies on air pollution, road building, and privatization threatened the parks.