Any municipality may pay the cost of purchasing, erecting, enlarging, improving, extending, or leasing any municipal plant, system, line, or any part thereof:
A municipality may pay the cost of leasing any municipal plant, system, line, or any part thereof from the state, or any agency or institution of the state under subsection 5 of section 40-33-01 solely from revenues to be derived by the municipality from the ownership, sale, lease, disposition, and operation of the waterworks, mains, and water distribution system; the funds or any other amounts invested by the municipality pursuant to section 21-06-07, or invested on the municipality's behalf by the state, or any agency or institution of the state, in conformity with policies of the industrial commission, including investment in a guaranteed investment contract and any earnings thereon, to the extent pledged therefor; and funds, if any, appropriated annually by the governing body of the municipality or received from federal or state sources.
When such cost, or any part thereof, is to be paid out of the earnings, the cost or the part thereof payable out of the earnings shall not become a general obligation of the municipality payable out of the money raised through taxation but shall be a special obligation payable solely and exclusively out of the earnings derived from the operation of the plant, system, or line.
N.D.C.C. § 40-33-04