40 CFR 81.239 - Upper Rio Grande Valley Intrastate Air Quality Control Region.
The Upper Rio Grande Valley Intrastate Air Quality Control Region (New Mexico) 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 New Mexico: Los Alamos County, Santa Fe County, Taos County.
Those portions of Rio Arriba County lying east of the Continental Divide.