(a) The proceeds from the sale of bonds shall be deposited in the construction fund.
(b) Money deposited in the construction fund shall be used to pay expenses, debts, and obligations necessarily incurred in the creation, establishment, and maintenance of the district and to pay the purchase price of property and construction contracts, including purchases for which the bonds were issued.
(c) If the bonds were issued in accordance with a contract with the United States, debts and obligations may be paid from the construction fund under the terms of or incident to the contract.
(d) After the payment of obligations for which the bonds were issued, any remaining money in the construction fund may be transferred to the maintenance fund.