Cal. Food & Agric. Code § 11923

County boards of supervisors may set fees for registration to cover the cost of registering pest control aircraft pilots but in no case shall such fee total more than ten dollars ($10) per year for a pilot who registers in person in the county in which he intends to work, and five dollars ($5) per year for a pilot already registered in another county and who is now registering in an additional county as provided in Section 11921.