40 C.F.R. § 81.17
The Metropolitan Los Angeles Air Quality Control Region consists of the following territorial 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):
Ventura County-the entire county;
Orange County-the entire county;
Riverside County-that portion of Riverside County which lies west of a line described as follows: Beginning at the point where the range line common to R. 4 E. and R. 3 E. intersects with Riverside-San Diego County boundary and running north along said range line; then east along the township line common to T. 8 S. and T. 7 S. to the southeast corner of sec. 36, T. 7 S., R. 3 E.; then north along the range line common to R. 4 E. and R. 3 E.; then east along the township line common to T. 8 S. and T. 7 S.; then north along the range line common to R. 5 E. and R. 4 E.; then west along the township line common to T. 6 S. and T. 7 S. to the southwest corner of sec. 34, T. 6 S., R. 4 E.; then north along the west boundaries of secs. 34, 27, 22, 15, 10, and 3, T. 6 S., R. 4 E.; then west along the township line common to T. 5 S. and T. 6 S.; then north along the range line common to R. 4 E. and R. 3 E.; then west along the south boundaries of secs. 13, 14, 15, 16, 17, and 18, T. 5 S., R. 3 E.; then north along the range line common to R. 2 E. and R. 3 E.; then west along the township line common to T. 4 S. and T. 3 S. to the intersection with the southwest boundary of partial sec. 31, T. 3 S., R. 1 W.; then northwest along that line to the intersection with the range line common to R. 2 W. and R. 1 W.; then north to the intersection of said range line with the Riverside-San Bernardino County line;
San Bernardino County-that portion of San Bernardino County which lies west and south of a line described as follows: Beginning at the point where the San Bernardino-Riverside County boundary is intersected by the range line common to R. 3 E. and R. 2 E. and running east along said county boundary; then north along the range line common to R. 3 E. and R. 2 E.; then west along the township line common to T. 3 N. and T. 2 N. to the intersection of said township line with the San Bernardino-Los Angeles County boundary;
Los Angeles County-that portion of Los Angeles County which lies south and west of a line described as follows: Beginning at the point where the township line common to T. 3 N. and T. 2 N. intersects with the Los Angeles-San Bernardino County boundary and running west along said township line; then north along the range line common to R. 8 W. and R. 9 W.; then west along the township line common to T. 4 N. and T. 3 N.; then north along the range line common to R. 12 W. and R. 13 W. to the southeast corner of sec. 12, T. 5 N., R. 13 W.; then west along the south boundaries of secs. 12, 11, 10, 9, 8, and 7, T. 5 N., R. 13 W. to the boundary of the Angeles National Forest which is collinear with the range line common to R. 13 W. and R. 14 W.; then north and west along the Angeles National Forest boundary to the point of intersection with the township line common to T. 7 N. and T. 6 N. (point is at the northwest corner of sec. 4 in T. 6 N., R. 14 W.); then west along the township line common to T. 7 N. and T. 6 N.; then north along the range line common to R. 15 W. and R. 16 W. to the southeast corner of sec. 13, T. 7 N., R. 16 W.; then west along the south boundaries of secs. 13, 14, 15, 16, 17, and 18, T. 7 N., R. 16 W.; then north along the range line common to R. 16 W. and R. 17 W. to the north boundary of the Angeles National Forest (collinear with township line common to T. 8 N. and T. 7 N.); then west and north along the Angeles National Forest boundary to the point of intersection with the south boundary of the Rancho La Liebre Land Grant; then west and north along this land grant boundary to the point at which it intersects with the Los Angeles-Kern County boundary; then west along said county boundary to the northwest corner of Los Angeles County;
Santa Barbara County-that portion of Santa Barbara County which lies south of a line described as follows: Beginning at the point where the Jalama Creek runs into the Pacific Ocean and running east and north along Jalama Creek to a point of intersection with the west boundary of the San Julian Land Grant; then south along the San Julian Land Grant boundary to its southwest corner; then east along the south boundary of the San Julian Land Grant to the northeast corner of partial sec. 20, T. 5 N., R. 32 W.; then south and east along the boundary of the Las Cruces Land Grant to the southwest corner of partial sec. 22, T. 5 N., R. 32 W.; then northeast along the Las Cruces Land Grant boundary; then east along the north boundaries of sec. 13, T. 5 N., R. 32 W., and secs. 18, 17, 16, 15, 14, 13, T. 5 N., R. 31 W., and secs. 18, 17, 16, 15, 14, 13, of T. 5 N., R. 30 W., and secs. 18, 17, 16, 15, T. 5 N., R. 29 W.; then south along the east boundary of sec. 15, T. 5 N., R. 29 W.; then east along the north boundaries of secs. 23 and 24, T. 5 N., R. 29 W., and secs. 19, 20, 21, 22, 23, 24, T. 5 N., R. 28 W., and secs. 19 and 20, T. 5 N., R. 27 W.; then south along the east boundary of sec. 20, T. 5 N., R. 27 W.; then east along the north boundaries of secs. 28, 27, 26, 25, T. 5 N., R. 27 W., and sec. 30, T. 5 N., R. 26 W.; then south along the east boundary of sec. 30, T. 5 N., R. 26 W.; then east along the north boundaries of secs. 32, 33, 34, 35, T. 5 N., R. 26 W.; then south along the east boundary of sec. 35, T. 5 N., S. 26 W.; then east along the township line common to T. 4 N. and T. 5 N. to the intersection of said township line with the Santa Barbara-Ventura County boundary.
40 C.F.R. §81.17