In order to defray the expenses of the Nebraska Power Review Board, there shall be imposed upon each public power district, public power and irrigation district, electric membership association, electric cooperative company, and municipality having an electric distribution system or generation and distribution system, and also upon all registered groups of municipalities, an assessment each fiscal year in such sum as shall be determined by the board and approved by the Governor. The total of such assessments shall not exceed the expenses of the board which may reasonably be anticipated for the fiscal year for which assessment is made and shall be apportioned among the various agencies in proportion to their gross income in the preceding calendar year. The board shall determine and certify such assessment to each supplier after approval of the board's budget by the Legislature and Governor. The supplier shall remit the amount of its assessment to the board within forty-five days after the mailing of the assessment. Any assessment not paid when due shall draw interest at a rate equal to the rate of interest allowed per annum under section 45-104.02, as such rate may from time to time be adjusted. The proceeds of such assessment shall be remitted to the State Treasurer for credit to the Nebraska Power Review Fund, which fund is hereby created and which, when appropriated by the Legislature, shall be used to administer the powers granted to the Nebraska Power Review Board, except that transfers may be made from the fund to the General Fund at the direction of the Legislature. Any money in the Nebraska Power Review Fund available for investment shall be invested by the state investment officer pursuant to the Nebraska Capital Expansion Act and the Nebraska State Funds Investment Act.