Associated Press: An environmental group is suing Interior Secretary Ken Salazar to try to get the government to increase its regulation of mining in the nation’s top-coal producing region. The federal lawsuit WildEarth Guardians filed in Denver this week also seeks to open competition for coal leases in northeast Wyoming’s Powder River Basin, instead of letting the government follow the guidance of mining companies that express interest. The Santa Fe, N.M.-based group petitioned Salazar in …