Oregon Revised Statutes Water Resources: Irrigation, Drainage, Flood Control, Reclamation § 552.428

After advertising for bids, the board shall let a contract for construction of the whole or any part of the project to the lowest responsible bidder; or the board may reject any or all bids and readvertise; or it may construct the project under its own superintendence. Good and sufficient bond, or an irrevocable letter of credit issued by an insured institution as defined in ORS 706.008 running in favor of the district, shall be required of each contractor, conditioned that the contractor will well and truly comply with all the provisions of the contract and perform all work in accordance with the terms thereof.