Cal. Sts. & Hy. Code § 261
The department shall establish and apply pertinent planning and design standards for development of official scenic highways.
In establishing and applying such standards for, and undertaking the development of, official scenic highways, the department shall take into consideration the concept of the "complete highway," which is a highway which incorporates not only safety, utility, and economy but also beauty. The department shall also take into consideration in establishing such standards that, in a "complete highway," pleasing appearance is a consideration in the planning and design process. In the development of official scenic highways, the department shall give special attention both to the impact of the highway on the landscape and to the highway's visual appearance. The standards for official scenic highways shall also require that local governmental agencies have taken such action as may be necessary to protect the scenic appearance of the scenic corridor, the band of land generally adjacent to the highway right-of-way, including, but not limited to, (1) regulation of land use and intensity (density) of development; (2) detailed land and site planning; (3) control of outdoor advertising; (4) careful attention to and control of earthmoving and landscaping; and (5) the design and appearance of structures and equipment.
Ca. Sts. and High. Code § 261