When any assessment, except an operation and maintenance assessment, levied and assessed upon district lands remains unpaid in whole or in part and, in the judgment of the board it would be for the best interest of the district or the landowners therein to issue bonds to obtain money to pay the cost of reclamation, the indebtedness of the district, or any other legal charge, or when a petition signed by the owners of more than one-half of the land in the district is filed with the secretary, the board, by order entered upon its records, shall order a special election to be held at some place in the district to be designated by the board.