Authorizes the department of health and any interested counties, in partnership with the department of ecology, to capitalize and administer a sustainable unified low-interest loan program to assist homeowners with the repair and replacement of on-site sewage systems and to ensure the full implementation of a county's on-site program management plan.

Authorizes the department of health, interested counties, and the department of ecology to use any appropriate funding source for the implementation of the program and mutually develop the administration of the program in the manner that is deemed the most efficient, which may include administrating the program through the department of ecology's water quality financial assistance program.

Allows the low-interest loan program to be offered to a county, required to determine marine recovery areas, only if the county develops, funds, and fully implements an on-site program management plan that has received approval from the department of health.