In the 1977 Clean Air Act Amendments, Congress directed the Environmental Protection Agency (EPA) to establish a program for protecting visibility in pristine areas.¹ This action was a response to fears that the unique scenic vistas so much a part of the nation's heritage, especially in the West, would be irrevocably lost.

Since the outset, however, efforts to put the program in place have been met with heated opposition.² The costs, it was argued, would be excessive, perhaps involving widespread retrofitting of existing sources with expensive pollution control equipment. Furthermore, the program could create an intolerable ceiling on western growth and energy development. Attempting to grapple with these concerns in the face of a less than complete understanding of the scientific issues related to visibility impairment, EPA fell well behind the statutory timetable.³