Interest on a judgment in a condemnation proceeding instituted by the department, including interest that is payable pursuant to section 12-1123, subsection B, shall be calculated for each month or portion of a month that interest is owed and shall be either:
1. The prime rate charged by banks on short-term business loans as determined for publication in the bulletin of the board of governors of the federal reserve system, as of the first day of that month.2. In the absence of a determination by the board of governors of the federal reserve system, calculated in the same manner based on comparable data as determined by the United States department of commerce, bureau of economic analysis, for publication in "survey of current business".3. If the prime rate cannot be determined from publication as provided in paragraph 2, determined by a federal agency that is annually designated by the board and that makes and publishes data sufficient to determine the prime rate of interest.