Cal. Sts. & Hy. Code § 262
Whenever the department determines that the corridor protection program for any state highway in the state scenic highway system established by this article has been implemented by local governmental agencies and a plan and program has been developed by the department for bringing the highway up to the standards for official scenic highways established by the department, including the concept of the "complete highway," as described in Section 261, the department shall designate the highway as an official state scenic highway and shall so indicate the highway in any publications of the department or in any maps which are issued by the department to the public.
The department shall cause appropriate signs to be placed and maintained along the portions of the state scenic highway system which the department has designated as official state scenic highways that indicate that the highways are official state scenic highways.
If at any time the department determines that the corridor protection program of local governmental agencies, with respect to any highway which has been designated as an official state scenic highway, no longer adequately carries out responsibility of the local governmental agencies for the protection of the scenic corridor, it may revoke the designation of the highway as an official state scenic highway and remove the signs which so indicate the highway.
Ca. Sts. and High. Code § 262