California Code, Public Contract Code - PCC § 20813

(a) All contracts for the construction or completion of any building, structure, or improvement, when the expenditure required for the work exceeds ten thousand dollars ($10,000), shall be contracted for and let to the lowest responsible bidder after notice.  If two or more bids are the same and the lowest, the district board may accept the one it chooses.

(b) The notice inviting bids shall set a date for the opening of bids.  The first publication or posting of the notice shall be at least 10 days before the date of opening the bids.  Notice shall be published at least twice, not less than five days apart, in a newspaper of general circulation in the district, or if there is none, it shall be posted in at least three public places in the district.  The notice shall distinctly state the work to be done.

(c) In its discretion, the district board may reject any bids presented and readvertise.

(d) In the case of an emergency, the district board may act pursuant to Chapter 2.5 (commencing with Section 22050).

(e) The district board may, subject to the provisions of Chapter 5 (commencing with Section 9550) of Title 3 of Part 6 of Division 4 of the Civil Code, require the posting of those bonds it deems desirable as a condition to the filing of a bid or the letting of a contract.

(f) Cost records of the work shall be kept in the manner provided in Chapter 1 (commencing with Section 4000) of Division 5 of Title 1 of the Government Code.