(Francisco Kjolseth | The Salt Lake Tribune) In this Aug. 23, 2016 photo, clean air, public health and national park advocates march to Rocky Mountain Power headquarters in Salt Lake City, in support of the Environmental Protection Agency's (EPA) recently approved plan to reduce coal pollution in beloved national parks such as Arches, Canyonlands and Zion. A 20-year plan by Utah's largest electricity provider stipulating that it will not add pollution-control systems to its coal power plants has received criticism from some in the state who say the proposal may violate a U.S. Environmental Protection Agency requirement and get in the way of the federal push to curb regional haze, The Salt Lake Tribune reports.