40 C.F.R. § 81.163
The Sacramento Valley Intrastate Air Quality Control Region (California) 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 California: Butte County, Colusa County, Glenn County, Sacramento County, Sutter County, Tehama County, Yolo County, Yuba County.
Shasta County-that portion of Shasta County which lies west and south of a line described as follows: Beginning at the Shasta-Siskiyou County boundary and running south along the range line common to R. 2 E. and R. 1 E., Mt. Diablo Base and Meridian, to the southwest corner of T. 35 N., R. 2 E.; then east along the township line common to T. 35 N. and T. 34 N. to the northwest corner of T. 34 N., R. 3 E.; then south along the range line common to R. 3 E. and R. 2 E. to the southwest corner of T. 33 N., R. 3 E.; then east along the township line common to T. 33 N. and T. 32 N. to the northwest corner of T. 32 N., R. 4 E.; then south along the range line common to R. 4 E. and R. 3 E. to the point of intersection with the northwest corner of the Lassen Volcanic National Park boundary; then east along the north boundary of Lassen Volcanic National Park to the Point of intersection with the Lassen-Shasta County boundary.
Solano County-that portion of Solano County which lies north and east of a line described as follows:Beginning at the inersection of the westerly boundary of Solano County and the 1/4 section line running east and west through the center of section 34, T. 6 N., R. 2 W., M.D.B. & M., thence east along said 1/4 section line to the east boundary of section 36, T. 6 N., R. 2 W., thence south 1/2 mile and east 2.0 miles, more or less, along the west and south boundary of Los Putos Rancho to the northwest corner of section 4, T. 5 N., R. 1 W., thence east along a line common to T. 5 N. and T. 6 N. to the northeast corner of section 3, T. 5 N., R. 1 E., thence south along section lines to the southeast corner of section 8, T. 3 N., R. 2 E., thence east to the boundary between Solano and Sacramento Counties.
40 C.F.R. §81.163