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All Subdivision applications are submitted to the Island County Planning Department.  During the review process, the application is routed from the Planning Department to Environmental Health and Public Works for comments. 

Environmental Health Review Criteria

Environmental Health conducts a general review of the proposals to determine any potential impacts on proposed drinking water supply, proposed sewage disposal systems, and minimum land area.  Possible additional review criteria include addressing critical aquifer recharge protection and seawater intrusion protection. 
Drinking Water Supply Methods and Requirements
A supply of potable (drinking) water must be available to each proposed lot in a new subdivision. The method of water supply may vary, depending on resource availability, number of lots to be created, and priorities of the landowner. To check the requirements for preliminary and final plant approval please refer to the related document on the right called Drinking Water Requirements for Subdivisions.  
Sewage Disposal Methods and Requirements
The application for a new subdivision must demonstrate the capability of providing an approved means of sewage disposal for each of the proposed lots. The application must include either an approved Site Registration that shows adequate soils on each proposed lot (for on-site sewage systems) or documentation of another means of sewage disposal. To check the requirements for preliminary and final plant approval please refer to the related document on the right called Sewage Disposal Requirements for Subdivisions. 
Minimum Land Area
The area requirements are based on soil types and the type of water supply. Prior to preliminary plat approval for a subdivision proposing on-site sewage disposal systems, conformance to the minimum land areas must be shown. Minimum land area can also be reviewed through a “Method II” analysis, though this is a complex process that generally requires a hydro-geologic report on the site. Please see the related document on the right, ICC 8.07D.320, for more information. 
Critical Aquifer Recharge Area Protection
The subdivision projects may be subject to Critical Aquifer Recharge Area Protection review (ICC 8.09.097). The Health Officer may impose conditions to mitigate impacts to groundwater resources, or may modify, alter or deny a project if no mitigation measures are found or agreed upon.  
Seawater Intrusion Protection
Subdivision projects may be subject to Seawater Intrusion Protection review (ICC 8.09.099 - Seawater Intrusion Protection). Public Health has classified areas of the county into seawater intrusion risk categories based upon groundwater elevation information and proximity to existing groundwater wells with chloride data. The risk categories are Low, Medium, High, and Very High. The risk rating will be determined during the water system approval process and/or during review of the subdivision application. In addition, staff in the Drinking Water Program can provide the risk rating of a parcel upon request at any time. 

For additional questions about Subdivisions call (360) 678-7267.

Helpful Resources

Island County Environmental Health - ​Plat Approval Requirements for Sewage Disposal

Island​ County Environmental Health - Plat Approval Requirements for Drinking Water