Cal. Pub. Util. Code § 28773

The board of directors may hold public hearings, subpoena witnesses, and perform all other acts necessary to properly carry out its duties. The board may delegate such authority to other officers of the district who shall report thereon to the board. In the case of public hearings, including those pursuant to Sections 29039 to 29046, inclusive, authority may be so delegated to a referee, who need not be an officer of the district.