California Code, Public Contract Code - PCC § 21203

If all proposals are rejected or no proposals are received pursuant to advertisement, or where the estimated cost of the work does not exceed five thousand dollars ($5,000), or where the work consists of channel protection, maintenance work, or emergency work, the board, by unanimous vote of all members present, may, without advertising for bids, have the work done by force account.In case of an emergency, if notice for bids to let contracts will not be given, the board shall comply with Chapter 2.5 (commencing with Section 22050). The district may purchase in the open market, without advertising for bids, materials and supplies for use in any work either under contract or by force account.