All construction contracts by the district, where the amount of the contract shall exceed two thousand, five hundred dollars ($2,500.00), shall be made upon at least three weeks’ public notice by advertisement in a newspaper of general circulation in the district, which notice shall state the thing to be done and invite sealed proposals, to be filed with the secretary of the district, to do the work; and in all such cases, before the notice shall be published, the plans and specifications for the work shall be filed with the secretary of the district and there remain. The board of directors of the district shall award the contract to the lowest and best bidder, who will comply with the terms imposed by such board and enter into bond with sufficient sureties, to be approved by the board, in such penalty as shall be fixed by such board but in no case to be less than the contract price, conditioned for the prompt, proper, and efficient performance of the contract.