Me. Stat. tit. 32 § 4172
The department shall establish the classifications for all wastewater treatment plants with due regard to the size, type, character of wastewater to be treated and other physical conditions affecting those treatment plants and shall specify whether each classification requires the employment of an operator and the qualifications the operator must have to successfully manage and supervise the operation of those facilities so as to protect the public health or prevent nuisance conditions or unlawful conditions. A wastewater treatment plant required by its classification to employ an operator may employ more than one operator but must designate one operator as the operator in responsible charge for the facility. [2021, c. 173, §4(AMD).]
32 M.R.S. § 4172