California Code, Streets and Highways Code - SHC § 2010

In order that the provisions of this chapter may be effectively carried out, the members of the board of supervisors of their respective counties shall make reasonable inspection from time to time of the roads within their counties maintained from funds supplied by this chapter.  The additional mileage entailed by this section, not to exceed six hundred dollars ($600) in any one year, shall be a proper charge against and shall be paid from the one thousand six hundred sixty-seven dollars ($1,667) monthly apportionment to the county under subdivision (a) of Section 2104.

Such mileage shall be deemed to be in addition to any other mileage allowed by law or county charter, and each supervisor who uses a privately owned automobile in the discharge of duties imposed upon him in connection with the county road system shall receive for the performance of such duties in addition to the compensation and any other allowances paid him as supervisor, but not in duplication of any other mileage allowed by law or county charter, twenty-five dollars ($25) per month for the first 250 miles traveled, without filing a report of the specific inspection tours requiring such mileage.  For mileage traveled in excess of 250 miles, each supervisor shall be paid ten cents ($0.10) for each mile traveled up to 250 miles or twenty-five dollars ($25) for a total not to exceed 500 miles or fifty dollars ($50).  The supervisor claiming such additional mileage shall file a report of the inspection tour or tours requiring such travel.