Cal. Health & Safety Code § 101350

Any board of supervisors may levy a special tax on all the property in the county, outside of any city pursuant to Article 3.5 (commencing with Section 50075) of Chapter 1 of Part 1 of Division 1 of Title 5 of the Government Code, and spend the proceeds to prevent the introduction of, and to eradicate, dangerous, infectious, or communicable diseases, and for general sanitation purposes.