California Code, Public Contract Code - PCC § 21111

(a) All contracts for the construction of any unit of work, except as provided in this article, estimated to cost in excess of ten thousand dollars ($10,000) shall be let to the lowest responsible bidder in the manner provided in this article.  The board of directors of the agency shall advertise by three insertions in a daily newspaper of general circulation or two insertions in a weekly newspaper of general circulation published in the agency's jurisdiction inviting sealed proposals for the construction of the work before any contract shall be made, and may let by contract separately any part of the work.  The board shall require the successful bidder 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 the claims for labor and material.  The faithful performance bond shall contain terms and conditions as the board may specify, and the payment bond shall be subject to the provisions of, and shall contain the terms and conditions set forth in Title 3 (commencing with Section 9000) of Part 6 of Division 4 of the Civil Code, as applicable.  The board shall also have the right to reject any bid, in which case the board may advertise for new bids.  In the event no proposals are received pursuant to advertisement, or where the estimated cost of the work does not exceed ten thousand dollars ($10,000), or the work consists of emergency work, the board of directors 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 agency may purchase in the open market, and may authorize the Purchasing Agent of the County of Santa Barbara to purchase, without advertisement for bids, materials and supplies for use in any work either under contract or by force account.

(b) If the work to be performed by or on behalf of the agency does not involve an expenditure of ten thousand dollars ($10,000) or more, or if the work consists of emergency work, the agency may require a faithful performance bond.  The agency may require a payment bond on work performed on behalf of the agency which does not involve an expenditure of more than ten thousand dollars ($10,000).