California Code, Public Contract Code - PCC § 20192

(a) Whenever the cost of construction of any office building, warehouse, or garage of the district constructed under Section 20191 exceeds the sum of two thousand dollars ($2,000), the district shall adopt plans and specifications and working details, as may be proper, and shall advertise for bids for the work in accordance with the plans and specifications so adopted. All bidders shall be afforded an opportunity to examine the plans and specifications and the district shall award the contract to the lowest responsible bidder.

(b) All bids for construction work shall be presented under sealed cover and shall be accompanied by one of the following forms of bidder's security:

(c) The person or corporation to whom the contract is awarded shall be required to execute a bond for the faithful performance of the contract. The form of the bond shall be approved by the board of directors. In cases of great emergency and when necessary to protect life and property, the board of directors, by unanimous vote of all members present, may without advertising for bids therefor, have the work done by day labor.