Cal. Sts. & High. Code § 1487

A person who, by means of ditches or dams, obstructs or injures any county highway, diverts any watercourse into any county highway, or drains water from his or her land upon any county highway, to the injury of the highway, shall, upon notice by the road commissioner, immediately cease and discontinue the obstruction and injury, and shall repair the highway at his or her own expense. He or she is liable to a penalty of three hundred fifty dollars ($350) for each day the obstruction or injury remains, recoverable as provided in Section 1496, and is also guilty of a misdemeanor.