Cal. Gov. Code § 23113
The boundaries of Imperial County are as follows:
Beginning on the second standard parallel south of S.B.B. & M., at the common corner of T.9 S., R.9 E., and T.9 S., R.8 E., said corner being the northwest corner of Imperial County and the northeast corner of San Diego County; thence south on the range line between R.8 E. and R.9 E. to the boundary line between the United States and Mexico; thence easterly following the boundary line between United States and Mexico as fixed by the treaty of Guadalupe Hidalgo to Boundary Point No. 34, which is the intersection of the centerline of the Colorado River and the International Boundary Line between California and the United Mexican States, which point is common to the boundaries of Arizona, the United Mexican States, and California, said Boundary Point No. 34, and all other boundary points mentioned hereafter, being described in "Interstate Compact Defining the Boundary Between the States of Arizona and California," a true and complete copy of which is on file for a permanent public record in the office of the California Secretary of State, and certified copies of which are on file in the office of the California State Lands Commission and also in the office of the County Recorder of Imperial County; thence northeasterly and easterly along the centerline of the Colorado River to Boundary Point No. 33 in the Colorado River vertically below the center of the new U. S. Highway 80 Bridge; thence easterly along the centerline of the Colorado River to Boundary Point No. 32 on the centerline of the Colorado River where said centerline intersects the east line of Section 35, T. 16 S., R. 22 E., S.B.M. ; thence leaving the Colorado River, north along the east line of said Section 35 to Boundary Point No. 31; thence due East approximately 110 feet to Boundary Point No. 30; thence northerly to Boundary Point No. 29; thence due East to Boundary Point No. 28; thence northerly approximately 700 feet to Boundary Point No. 27; thence easterly about 1.93 miles to Boundary Point No. 26, being the west quarter corner of Section 13, T. 8 S., R. 23W., Gila and Salt River Meridian; thence north and east along Section lines between Boundary Points Nos. 26 through 21; thence from Boundary Point No. 21, easterly to Boundary Point No. 20, being a point on the centerline of the Colorado River; thence northerly up the Colorado River, along the Interstate Boundary as described in above mentioned Interstate Compact, to its intersection with the line of the second standard parallel south of the S.B.B. & M.; thence westerly and following the said second standard parallel to the place of beginning.
That portion of the Imperial County boundary line which coincides with the Arizona-California Interstate Boundary is shown on a series of Planimetric Maps appearing in Exhibit "A" of above mentioned Interstate Compact.
Geographic Positions and Plane Coordinates of all boundary points mentioned in above description are listed in Exhibit "A" of said Interstate Compact.
Ca. Gov. Code § 23113