Cal. Pub. Res. Code § 13117

The district may sell the bonds so issued at the times or in the manner the board deems to be to the public interest, provided, that all bonds shall be sold on sealed proposals to the highest bidder. Public notice shall be given in the manner determined by the board. If no bids are received or if the board determines that the bids received are not satisfactory as to price or responsibility of the bidders, the board may reject all bids received, if any, and either readvertise or sell the bonds at private sale.