California Code, Streets and Highways Code - SHC § 941

(a) Boards of supervisors shall, by proper order, cause those highways which are necessary to public convenience to be established, recorded, constructed, and maintained in the manner provided in this division.

(b) No public or private road shall become a county highway until and unless the board of supervisors, or its designee, by appropriate action, has caused the road to be accepted into the county road system.  No county shall be held liable for failure to maintain any road unless and until it has been accepted into the county road system by action of the board of supervisors or its designee.

(c) The acceptance of any road or the acceptance of any road subject to improvements pursuant to Section 66477.1 of the Government Code does not constitute the acceptance of the road into the county road system in the absence of the adoption of a resolution by the board of supervisors accepting the road into the county road system.

(d) In lieu of the procedures set forth in subdivisions (b) or (c), boards of supervisors may, by ordinance, designate a county officer to accept, on behalf of the board, roads or portions thereof, into the county road system and to record conveyances to the county of real property interests for road uses and purposes.  The designee shall, prior to recording any conveyance under this section, affix a certificate to the instrument stating the acceptance into the county road system and designating the name or number, or both, of the county road.  The designee shall report all acceptances and recordings to the board at the end of the fiscal year, or at more frequent intervals as determined by the board.