Within one year following the effective date of this act, all water supply systems and wastewater treatment facilities used or intended for use by or for the benefit of the public, whether publicly or privately owned, shall be under the supervision of an operator or operators certified by the secretary in a classification corresponding to the classification of the water supply system or wastewater treatment facility to be supervised by such operator or operators. No operator shall be required to be certified or to complete a training program or course of education for certification in a classification other than the classification corresponding to the classification of the water supply system or wastewater treatment facility to be supervised by such operator.