California Code, Public Utilities Code - PUC § 40078

(a) The Auditorof the County of Orange shall provide the board with an annual audit of all books and accounts of the district, unless an audit by a certified public accountant or public accountant is otherwise provided by the board.  The county auditor may make, or may contract with a certified public accountant or public accountant to make, the annual audit.  Any costs incurred by the county auditor, including contracts with or employment of, a certified public accountant or public accountant, in making the audit pursuant to this section shall be borne by the district.

(b) Where an audit of the district's accounts and records is made by a certified public accountant or public accountant, the minimum requirements of the audit shall be prescribed by the State Controller and shall conform to generally accepted auditing standards.  A report shall be filed with the Auditor of the County of Orange within 12 months of the end of the fiscal year under examination.