Finds that improperly functioning on-site sewage systems in marine areas may contaminate ground water and surface water, threatening public health and the environment.

Finds that in these areas enhanced on-site sewage system certification programs must be established to ensure systems are properly functioning to protect public and environmental health.

Requires the department of ecology to designate a marine area of special concern in counties with shorelines adjacent to Puget Sound in areas where concentrations of on-site sewage disposal systems are a significant factor contributing to public health and environmental concerns.

Requires the local board of health with jurisdiction over the area to submit an enhanced on-site sewage system certification program to the department within eighteen months of designation of a marine area of special concern within the county.

Requires the local board of health with jurisdiction over the area to conduct quality assurance of the enhanced on-site sewage system certification program including: (1) Inspection of at least ten percent of certificated on-site sewage disposal systems every three years to determine if the systems are properly functioning and in compliance with this chapter and RCW 43.20.050; and

(2) Follow-up inspections of all new on-site sewage disposal systems within one year of installation to ensure that the system is properly functioning and to provide educational materials to the owner or operator of the system.

Provides that, in areas with shorelines adjacent to Puget Sound where an enhanced on-site sewage system certification program is not required, the owner of an on-site sewage disposal system is responsible for operating, monitoring, and maintaining the system to minimize the risk of failure. In order to accomplish this, the owner shall ensure a complete evaluation of the system's components to determine functionality, maintenance needs, and compliance with regulations and permits as follows: (1) At least once every three years for a conventional on-site sewage disposal system; or

(2) Annually for a complex on-site sewage disposal system.