The district may be dissolved by the district board by a resolution of the district board upon a determination that the district has no outstanding bond obligations. The district shall not be dissolved if any bonds of the district remain outstanding unless an amount of money sufficient, together with investment income thereon, to make all payments due on the bonds either at maturity or prior redemption has been deposited with a trustee or escrow agent and pledged to the payment and redemption of the bonds. The district may continue to operate after dissolution only as needed to collect money and make payments on any outstanding bonds.