Arsenic Detections in Washington Public Water Supplies


Map of Arsenic Detections in Washington Public Water Supplies (PDF)

The public water system sources shown on the map have exceeded an arsenic level of 10 ppb (black dots) or 50 ppb (red dots) at least once over the sampling history for that source. This does not necessarily mean that an MCL (maximum contaminant level) was exceeded for the source since the current 10 ppb standard did not come into effect until January, 2006. The data contained in the above map covers the time period from 1/1/1993 - 07/31/2007.


For drinking water & statewide source monitoring questions, call your regional office:

Southwest Region, Tumwater: 360-236-3030

Northwest Region, Kent: 253-395-6750

Eastern Region, Spokane: 509-329-2100

Health effects of arsenic-contaminated water: Office of Environmental Public Health Sciences, 360-236-3385

Viable treatment technology options: Sam Perry, alternative treatment engineer, 253-395-6755