Cal. Pub. Util. Code § 103222

(a) The purchase of all supplies, equipment, and materials, when the expenditure required exceeds one hundred fifty thousand dollars ($150,000), shall be by contract let to the lowest responsible bidder, or, in the district’s discretion, to the responsible bidder who submitted a proposal that provides the best value to the district on the basis of the factors identified in the solicitation. “Best value” means the overall combination of quality, price, and other elements of a proposal that, when considered together, provide the greatest overall benefit in response to the requirements described in the solicitation documents.

(b) To the extent practicable, the district shall obtain a minimum of three quotations, either written or oral, that permit prices and terms to be compared whenever the expected expenditure required for the purchase of supplies, equipment, or materials exceeds five thousand dollars ($5,000), but does not exceed one hundred fifty thousand dollars ($150,000).

(c) Notice requesting bids required by this section shall be published at least once in a newspaper of general circulation and on the district’s procurement Internet Web site. These publications shall be made at least 10 days before the bids are received. The board may reject any and all bids and readvertise at its discretion.