The department is authorized to prepare and/or adopt a comprehensive water pollution control and abatement plan and to make subsequent amendments thereto, for each basin established pursuant to RCW
90.48.270. Comprehensive plans for sewage drainage basins may be prepared by any municipality and submitted to the department for adoption.
Prior to adopting a comprehensive plan for any basin or any subsequent amendment thereof the department shall hold a public hearing thereon. Notice of such hearing shall be given by registered mail, together with copies of the proposed plan, to each municipality, or other political subdivision, within the basin exercising a sewage disposal function, at least twenty days prior to the hearing date. Such hearing may be continued from time to time and, at the termination thereof, the department may reject the plan proposed or adopt it with such modifications as it shall deem proper.
Following adoption of a comprehensive plan for any basin, the department shall require compliance with such plan by any municipality or person operating or constructing a sewage collection, treatment or disposal system or plant, or any improvement to or extension of an existing sewage collection, treatment or disposal system or plant, within the basin.