(a) A representative of the district shall inspect the work being done during its progress, and on completion of the contract, the district shall draw a warrant on the district depository or issue a check in favor of the contractor or the contractor's assignee for the amount of the contract price. The warrant or check shall be paid from the construction and maintenance or operating fund.
(b) If the district considers it advisable, it may contract to pay for the work in partial payments as the work progresses. Partial payments may not be more in the aggregate than the amount allowed under applicable laws. The amount of the work shall be shown by a certificate of a representative of the district.
(c) The provisions of this section do not apply to improvements carried out or performed by the United States.