Whenever lands situated in an irrigation district are acquired by any condemner through eminent domain, and such lands at the time of their acquisition by any condemner, are irrigable and are being served or are capable of being served by facilities of the district to the same extent and in the same manner as lands of like character held under private ownership were served, the condemner, as part of the compensable damages of the acquisition and at the time of such acquisition, shall make a lump-sum payment to the irrigation district in an amount sufficient to:
(1) Pay the pro rata share of the district's bonded indebtedness, if any, and the pro rata share of the district's contract indebtedness to the United States or to the State of Nebraska, if any, allocable to such lands, plus interest on such pro rata share in the event such indebtedness is not callable in advance of maturity;
(2) Pay any deferred installments of local improvement district assessments against such lands, if any; and
(3) Produce, if invested at an annual rate of interest equivalent to that set forth in current tables issued by the Director of Banking and Finance of the State of Nebraska, a sum of money equal to the annual increase in operation and maintenance costs against remaining lands in the district resulting from the severance from the district of the lands thus acquired by the condemner. For the purposes of determining the amount of such lump-sum payment, the annual maintenance and operation assessment of the district shall be considered to be the average for the ten years, or so many years as the district has assessment experience, if less than ten years, preceding the date of acquisition.