40 CFR 81.16 - Metropolitan Denver Intrastate Air Quality Control Region.
The Metropolitan Denver Intrastate Air Quality Control Region (Colorado) consists of the territorial area encompassed by the boundaries of the following jurisdictions or described area (including the territorial area of all municipalities (as defined in section 302(f) of the Clean Air Act, 42 U.S.C. 1857h(f)) geographically located within the outermost boundaries of the area so delimited):
In the State of Colorado: Adams County, Arapahoe County, Boulder County, Clear Creek County, Denver County, Douglas County, Gilpin County, Jefferson County.
For purposes of identification, the Regions are referred to by Colorado authorities as follows: