California Code, Public Resources Code - PRC § 49019

(a) The board of supervisors may enter into contracts for the disposal of garbage and other refuse matter.  Whenever the board enters into, or renews such a contract, it shall advertise for bids for the performance of the work in a newspaper of general circulation in the county.  The advertisement shall be published pursuant to Section 6062 of the Government Code.  If there is no newspaper of general circulation published in the county, the notice shall be given by posting in three public places for at least two weeks.

(b) All bidders shall be granted an opportunity to ascertain the details of the nature of the work to be done under the contract.  The contract shall be let to the lowest responsible bidder.  If no satisfactory bid is obtained, the board may reject all bids.  If all bids are rejected, the board of supervisors may readvertise for bids or, without the necessity of readvertising, may enter into contracts for the disposal of garbage and other refuse for a term not to exceed six months on terms that are necessary or proper in the exercise of the district's powers.