California Code, Streets and Highways Code - SHC § 1489

Unless a bridge is constructed in accordance with Section 1490, all persons excavating irrigation, mining or drainage ditches across county highways shall construct bridges across such ditches wherever such ditches cross such highways. If such persons fail to construct such bridges, the road commissioner shall construct them and shall recover from such persons, in an action at law brought in the name of the county, the expense of such construction.