Neb. Rev. Stat. § 70-509
Any instrument, statement and report, or certificate filed with the Nebraska Power Review Board, as provided for in Chapter 70, article 5, or certified copies thereof, shall be competent evidence in any hearing or proceeding involving the valuation of the electric light and power plant, distribution system, or transmission lines covered by the statement and report and certificate, for ratemaking purposes, taxation, or in any other matter in which the facts and statements in such instrument, statement and report, or certificate, may be involved or drawn in question, and the purchaser thereof and his, her, or its successor or assigns, shall be forever estopped to deny the facts set forth in such instrument, statement and report, or certificate.
Neb. Rev. Stat. § 70-509