Cal. PCC § 21531

(a) The Santa Clarita Valley Water Agency shall have power to prescribe methods for the construction of works and for the letting of contracts for the construction of works, structures, or equipment, or the performance or furnishing of labor, materials, or supplies, necessary or convenient for carrying out any of the purposes of this act or for the acquisition or disposal of any real or personal property; provided, that all contracts for any improvement or unit of work, when the cost according to the estimate of the engineer will exceed thirty thousand dollars ($30,000), shall be let to the lowest responsible bidder or bidders as provided in this article. The board shall first determine whether the contract shall be let as a single unit or divided into severable parts. The board shall advertise for bids by three insertions in a daily newspaper of general circulation published in the agency or by two insertions in a nondaily newspaper of general circulation published in the agency or, if no newspaper is published in the agency, in any newspaper of general circulation distributed in the agency, inviting sealed proposals for the construction or performance of the improvement or work. The call for bids shall state whether the work shall be performed in one unit or divided into parts. The work may be let under a single contract or several contracts, as stated in the call. The board shall require the successful bidders to file with the board good and sufficient bonds to be approved by the board conditioned upon the faithful performance of the contract and upon the payment of their claims for labor and material. The bonds shall comply with Title 3 (commencing with Section 9000) of Part 6 of Division 4 of the Civil Code. The board may reject any bid.

(b) In the event all proposals are rejected or no proposals are received, or the estimated cost of the work does not exceed thirty thousand dollars ($30,000), or the work consists of channel protection, maintenance work, or emergency work, the board may have the work done by force account without advertising for bids. 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).

(c) The agency 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; provided, however, that materials and supplies for use in any new construction work or improvement, except work referred to in subdivision (b), may not be purchased if the cost exceeds thirty thousand dollars ($30,000), without advertising for bids and awarding the contract to the lowest responsible bidder.