A BART review is required by sections 169A[1] and 169B[2] of the Clean Air Act for pollution sources which might cause haze in a "Federal Class 1 area".
An example of such a source is the Navajo Generating Station in Page, Arizona which could affect visibility in Grand Canyon National Park.
[3][4] BART provisions were included in the "Clean Air Visibility Rule," published by the United States Environmental Protection Agency (EPA) in 1999, and amended in 2005.
In the case of Navajo Generating Station, EPA solicited input from stakeholders: the Department of the Interior, the Central Arizona Project, the Navajo Nation, the Gila River Indian Community, the Salt River Project, the Environmental Defense Fund, and Western Resources Advocates.
A technical working group negotiated a "Reasonable Progress Alternative to BART" which was submitted by the Department of the Interior to the EPA on July 26, 2013 for consideration in development of a final rule.