(a) A district may enter into operating contracts and leases with cities and other governmental subdivisions for the operation of the portions of the district's water system which are designated by the board or the commission.
(b) To the extent that the proceeds of revenue bonds were used to acquire the portion leased, the annual payments paid by the lessee to the district shall be in a sum which is sufficient to permit the district to pay the proportionate part of the principal, interest, reserves, and other requirements provided by the bond proceedings on any revenue bonds which were issued to acquire the leased properties.
(c) Bonds issued to acquire, improve, enlarge, or extend leased properties may mature serially or otherwise not more than 50 years from their date of issue.