Except as otherwise provided in this section or §§ 10–14A–03 and 10–14B–03 of the State Government Article, an individual shall be certified by the Board in an appropriate classification before a waterworks, wastewater works, or industrial wastewater works may employ the individual as: A superintendent; or An operator or industrial operator in a job function determined by the Secretary. This section does not prevent a governmental agency or a person from continuing to employ in a waterworks, wastewater works, or industrial wastewater works, until July 2, 1982, an operator or industrial operator who is not certified under this title.