“Between 1998 and 2011, the skies over Indian country existed
in a regulatory gap. This gap was not merely inadvertent but was a
foreseeable consequence of congressional intent to delegate
regulatory authority under the Clean Air Act (CAA) to Indian
tribes. In 1998, the U.S. Environmental Protection Agency (EPA)
published the Tribal Authority Rule, which allowed-but did not
require-Indian tribes to implement tribal programs under the
CAA, including programs for issuing permits to new and modified
sources of air emissions in areas under the tribe’s jurisdiction. At
the same time, the CAA continued to mandate analogous state
permitting programs for areas under state jurisdiction. The CAA is,
however, perhaps the most technically ambitious environmental
regulatory program for a state or tribal government to undertake.
While Indian tribes have, with some frequency, undertaken
regulations under the Clean Water Act, almost none have availed
themselves of the opportunity under the CAA. As a result, there
was no clear mechanism for tribes and other entities to obtain
permits for new and modified sources in most of Indian country.’
