Cal. Public Contract Code § 20981

All work of construction, repair, or maintenance, the cost whereof exceeds one thousand five hundred dollars ($1,500), shall be done by contract; and all contracts shall be let by the board to the lowest responsible bidder, who will give bond for the faithful performance thereof satisfactory to the board, after advertisement for bids published by their clerk pursuant to Section 6062 of the Government Code in some newspaper of general circulation, designated by the board and published in the county in which the district or some part thereof is situated, specifying the time and place for the opening of bids, and the particular work to be bid for; provided, however, that the board may reject all bids and readvertise, and may by unanimous action in cases of great emergency, the nature of which shall be entered on their minutes, proceed at once to replace or repair any of the works or improvements of the district without advertisement.