Pub. Contract Code, § 21001

By resolution or resolutions the board of supervisors may order the work to be done, and if it does so it shall fix a time for receiving proposals or bids for doing the work, and shall direct the clerk to give notice, inviting sealed proposals or bids. Such notice shall include a statement that the work is to be done under the provisions of the Drainage District Improvement Act of 1919 and according to the plans and specifications on file, except insofar as such plans and specifications were changed by the board of supervisors in conclusion of the hearing on the resolution of intention in said act provided; to which said act, to the resolution of intention and all proceedings had thereunder the attention of bidders is hereby directed, and which are by this reference made part of said notice.