The term construction work as herein used, shall be deemed to include the erection of pump houses and electrical and other pumps or appliances for raising water onto the lands, as well as dams, headgates, ditches, laterals and other irrigation works. There may be included in any contract for construction, maintenance, interest and power charges for such period as the directors and the contractor may agree, not to exceed three (3) years, and when so included, interest, electrical, or other power and maintenance charges for the term agreed upon may be paid in bonds of the district to the amount agreed upon.