California Code, Streets and Highways Code - SHC § 27260

The board may construct works across any stream, strait, bay, water course, street, avenue, highway, railway, canal, ditch, or flume which the route of the works may intersect or cross. The works may also be constructed along any street, avenue, or highway, if they are constructed so as to afford security for life and property. The board shall restore the crossings and intersections as nearly as possible to their former state or in a manner not to have impaired unnecessarily their usefulness.