Maryland Code, Environment § 12-501

(a) A person or municipal or private corporation may not operate a waterworks, wastewater works, or industrial wastewater works unless the facility is under the responsible charge of a certified superintendent or certified operator as provided under § 12-402 of this title.

(b) After July 1, 1982, a person or municipal or private corporation may not operate a waterworks or wastewater works unless all operators in the waterworks or wastewater works are certified operators.

(c) After July 1, 1982, a person or municipal or private corporation may not operate an industrial wastewater works unless all industrial operators in the industrial wastewater works are certified industrial operators.

(d) The Department shall enforce this section.