Source Water Assessment Program (SWAP) Mapping Tool

The Source Water Assessment Program (SWAP) GIS mapping tool was developed to provide a graphical representation of drinking water source protection areas. Making this information available helps utilities protect their sources from unintended contamination. This site provides information about drinking water sources and known contaminants, helping users determine if their activity could impact a drinking water source.

How do I find a source water protection area?

  • Click to open SWAP Maps (Interactive GIS Mapping Tool)
  • When the page opens, click on the "Start" button at the bottom of the page.
  • When the welcome window opens, press “Go”
  • You now have four choices: you may browse the map to find the area of interest, use the water system ID, the water system name, or a known address to find an area.

What if there are errors in my source location or watershed protection areas? 

Let us know if you find errors in ODW data source location or protection areas data. You can provide corrections to Nikki Guillot, 360-236-3114, Source Water Protection Program Manager. If you have digital maps or shape files please provide those to follow the guidelines identified in DOH publication 331-391 (PDF)

Corrections to Ecology's contamination data should be sent to Ecology at

  • Browse the map to find the area of interest. Turn on the layers under “Data” that you would like to view. Use the zoom tools along the left margin or use your mouse to scroll in or out. Once you get to the area of interest you can click on any entity visible to obtain additional information.
  • Use the "Search by System Name or ID" box: input the water system ID or name, a drop down list will appear as you type, select the system you want. The map will zoom to the system and display source protection areas and service area. You will need to turn on layers to obtain additional data.
  • Use the "Find Address or Place" box: input an address, a drop down menu will appear, add information necessary to obtain the desired address. The map will zoom to that address. At any time you can turn on any layer listed under “data” on the top of the page.
    For additional help or hints use the Help "button." For even more information, use the "More Help / Links” link to access the user guide.

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