RCW 70A.105.050

If the legislative authority of a county or city finds that more restrictive standards than those contained in *section 2 of this act or those adopted by the state board of health for systems allowed under *section 2 of this act or limitations on expansion of a residence are necessary to ensure protection of the public health, attainment of state water quality standards, and the protection of shellfish and other public resources, the legislative authority may adopt ordinances or resolutions setting standards as they may find necessary for implementing their findings. The legislative authority may identify the geographic areas where it is necessary to implement the more restrictive standards. In addition, the legislative authority may adopt standards for the design, construction, maintenance, and monitoring of sewage disposal systems.