Cal. Gov. Code § 26883
In addition to the power now possessed by the board of supervisors to enter into contracts for audits the board shall have the power to require that the county auditor-controller shall audit the accounts and records of any department, office, board or institution under its control and of any district whose funds are kept in the county treasury. The county auditor-controller's report on any such audit shall be filed with the board of supervisors and, if the report discloses fraud or gross negligence a copy thereof shall be filed with the district attorney.
The governing body of any district may agree with the board of supervisors to reimburse the county for its actual cost of any audit of its accounts and records had under this section.
Ca. Gov. Code § 26883