Cal. Gov. Code § 23136
The boundaries of San Bernardino County are as follows:
Beginning at the northwest corner of Sec. 1, T. 25 S., R. 40 E., M. D. B. & M.; thence east along the township line between T. 24 and 25 S. of the Mount Diablo base line, being the sixth standard south, Mount Diablo Base, and continuing east by said standard line and extension thereof, to the western boundary of T. 19 N., R. 12 E., San Bernardino Base and Meridian; thence north along said western boundary to the northern line of said township; thence east along the northern line of said township to the eastern boundary of the State of California, being the oblique boundary line between the states of California and Nevada, as surveyed and monumented by the U. S. Coast and Geodetic Survey in 1899 and approved by Act of the California Legislature on March 1, 1901, and by the state of Nevada on February 27, 1903; thence southeasterly along said interstate boundary to its intersection with the centerline of the channel of the Colorado River as constructed by the U. S. Bureau of Reclamation, said point being common to the boundaries of Arizona, California, and Nevada, where the 35th degree of north latitude intersects the centerline of said channel, the above mentioned centerline being a portion of the interstate boundary between the States of Arizona and California as described in "Interstate Compact Defining the Boundary Between the States of Arizona and California", a certified copy of which is recorded and filed in the office of the County Recorder of San Bernardino County; thence downstream along said centerline to the southerly end of construction; thence, continuing downstream, along said interstate boundary to its intersection with the east and west center line of T. 1 S., R. 24 E., S. B. B. & M., or the prolongation thereof; thence westerly along the northern boundary of Riverside County to the corner common to Orange, Riverside, and San Bernardino Counties; thence northwesterly along the boundary line established by joint survey in December, 1876, and January, 1877, as the line between Los Angeles and San Bernardino Counties to the corner common to San Bernardino, Los Angeles and Orange Counties; thence northerly along the eastern boundary of Los Angeles County to the corner common to Los Angeles, Kern and San Bernardino Counties; situated at the northeast corner of T. 8 N., R. 8 W., S. B. B. & M.; thence east on the township line between T. 8 and 9 N. of San Bernardino base line to the section line between Secs. 32 and 33, T. 9 N., R. 7 W., S. B. B. & M.; thence north following section lines to the eighth standard parallel south of Mount Diablo base line; thence east along said eighth standard parallel to the southwest corner of T. 32 S., R. 41 E., M. D. B. & M.; thence north along the township line to the seventh standard parallel south of Mount Diablo base line; thence along said standard parallel to the southwest corner of Sec. 36, T. 28 S., R. 40 E., M. D. B. & M.; thence north along section lines to the southwest corner of Section 24, T. 26 S., R. 40 E; thence east along the south line of said Section 24 to an intersection with the east line of said Section 24; thence north along said east line, and continuing north along the east line of Section 13, same township and range, to an intersection with the north line of said Section 13; thence west along said north line and continuing west along the south line of Section 11, same township and range, to an intersection with the west line of said Section 11; thence north along said west line and continuing north along the west line of Section 2, same township and range, to an intersection with the north line of said Section 2; thence east along said north line to an intersection with the east line of said Section 2; thence north along section lines to the northwest corner of Sec. 1, T. 25 S., R. 40 E., M. D. B. & M., said point being the place of beginning.
That portion of the San Bernardino 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 § 23136