Cal. Gov. Code § 33201
All personnel, including the heads of units, within departments organized pursuant to this division and formed from units formerly within the county health, mental health, or welfare departments, shall possess the particular qualifications required by the Health and Safety Code or the Welfare and Institutions Code or the regulations enacted pursuant to either of those codes.
The county health department itself or the health related functions of the departments organized pursuant to this division may be under the direction of the health officer, or the board of supervisors may appoint personnel who possess qualifications, including standards of education and experience to assure competence, appropriate for the direction of the health department or the local administration of county health functions. The board of supervisors shall ensure that the final determination regarding issues of professional nursing practice shall be made by a person who is licensed as a registered nurse and certified as a public health nurse.
Ca. Gov. Code § 33201