The Obama administration Monday unveiled a new rule designed to protect streams and groundwater from coal mining, but the threat of a Republican-led challenge of the measure looms large after President-elect Donald Trump takes office. The Interior Department said in a news release that the rule “updates 33-year-old regulations and establishes clear requirements for responsible surface coal mining that will protect 6,000 miles of streams and 52,000 acres of forests over the next two decades, preserving community health and economic opportunities while meeting the nation’s energy needs.”