(a) For the purpose of providing funds to pay preliminary expenses, to construct improvements according to the plan, or to pay for an improvement already completed, the district may borrow money in an amount not exceeding the estimated cost thereof, including interest on the money borrowed to a date six (6) months subsequent to the estimated date of completion of the work and a reserve not to exceed one (1) year's principal and interest requirements, and may to that extent issue negotiable bonds or certificates of indebtedness.
(b) In order to secure the bonds, the district may pledge and mortgage all uncollected assessments of benefits for the payments of the bonds, and, in addition thereto, the municipality in which the district is created may pledge surplus utility revenues of the city to secure the bonds of the district.
(c) The bonds of the district shall be authorized and issued upon a majority vote of the qualified electors of the municipality.