(2) The commission may by rule withdraw from enforcement any or all of its rules or standards adopted pursuant to this chapter within the boundaries of any city or county, if the commission finds such city or county:
(a) Has adopted noise standards that are at least as stringent as and no less protective than those standards adopted by the state; and
(b) Has a program of active enforcement of such standards which, in the commission’s view, is at least as protective of the public health, safety and welfare as would be the enforcement provided by the department.
(3) The commission may modify or repeal such a rule as is made in accordance with subsection (2) of this section with regard to any particular city or county if it finds material change in any of the circumstances relied upon by the commission in making such rule. Such rulemaking shall be in conformance with the provisions of ORS chapter 183.
(4) Nothing in this section is intended to preclude contractual arrangements between a city or county and a state agency for services provided for the enforcement of state or local noise emission control standards. [1977 c.511 §4]