To adequately secure the payment of bonds and interest on the bonds, any district issuing bonds under this chapter, and the district’s officers, agents, and employees shall:

1.    Pay or cause to be paid punctually the principal and interest of every bond on the dates, at the places, in the manner, and out of the funds provided in the refunding bond and in accordance with the resolution authorizing its issuance.

2.    Operate the project in an efficient and economical manner and establish, levy, maintain, and collect related necessary or proper fees, tolls, rentals, rates, and other charges. Such fees, tolls, rentals, rates, and other charges must be sufficient, after    making due and reasonable allowances for contingencies and for a margin of error in the estimates, at least:

a.    To pay all current expenses of operation and maintenance of the project; b.    To pay the interest and principal on the bonds as they become due; c.    To comply with the terms of the resolution authorizing the issuance of the bonds or any other contract or agreement with the holders of the refunding bonds; and

d.    To meet any other obligations of the district which are charges, liens, or encumbrances upon the revenues of the project.

3.    Operate, maintain, preserve, and keep every part of the project in good repair, working order, and condition.

4.    Preserve and protect the security of the bonds and the rights of the bondholders and warrant and defend such rights against all claims and demands.

5.    Pay and discharge all lawful claims for labor, materials, and supplies, which, if unpaid, might become by law a lien or charge upon the revenues, or any part of the revenues, superior to the lien of the bonds or which might impair the security of the bonds.

6.    Hold in trust the revenues pledged to the payment of the bonds for the benefit of the holders of the bonds and apply the revenues only as provided by the resolution authorizing the issuance of the bonds, or, if the resolution is modified, as provided in the modified resolution.

7.    Keep proper separate books of record and accounts of the project in which complete and correct entries must be made of all transactions relating to any part of the project. All books and papers of the district are subject to inspection by the holders of ten percent or more of the outstanding bonds or of their representatives authorized in writing.

None of the duties contained in this section require any expenditure by the district of any funds other than revenue received from the project. The performance of the duties enumerated in this section is of the essence of the contract of the district with the bondholders.