Neb. Rev. Stat. § 81-15,132

The director may provide for certification without examination of any operator recommended by a governing body or owner as having been in charge of the operation or supervising the operation of a wastewater treatment facility on August 30, 1987, and whose competence has been demonstrated. Certificates issued under this section shall be valid for a period of four years from August 30, 1987. After such four-year period, certificates granted under this section shall no longer be valid, and such operators shall become fully certified under the Wastewater Treatment Operator Certification Act.