RCW 70A.125.130: Local government authority.

(1) Local governments may establish separate operating permit requirements for public water systems provided the operating permit requirements have been approved by the department. The department shall not approve local operating permit requirements unless the local system will result in an increased level of service to the public water system. There shall not be duplicate operating permit requirements imposed by local governments and the department.

(2) Except as provided in RCW 70A.125.010(4)(b), local governments may establish requirements for group B public water systems in addition to those established by rule by the state board of health pursuant to RCW 43.20.050(2) or other rules adopted by the department, provided that the requirements are at least as stringent as the state requirements.