California Code, Water Code - WAT § 1092

(a) That due notice has been given of the time and place of attendance of the witness or for the production of evidence and that the witness has been summoned in the manner prescribed in this chapter.

(b) That the witness has failed and refused to attend or produce the evidence required by the subpena before the board in the proceeding named in the notice and subpena, or has refused to answer questions propounded to him in the course of the proceeding.