Thurston County, Washington: drinking water report. Thurston County includes Olympia, Washington's state capital, with a population of about 300,000.
Thurston County includes Olympia, Washington's state capital, with a population of about 300,000. The county relies almost entirely on groundwater – the City of Olympia, the City of Lacey, and numerous smaller water systems pump from wells tapping glacial aquifer deposits. Joint Base Lewis-McChord, the largest military installation on the West Coast, occupies the northern portion of the county and neighboring Pierce County. The base's operations have direct implications for groundwater quality in the region.
Joint Base Lewis-McChord is a major confirmed PFAS contamination source. According to the Department of Defense's 2024 environmental report, AFFF-related PFAS has been detected at over 20 locations on the base, with groundwater monitoring wells showing PFOS concentrations exceeding 1,000 ppt in some areas near fire training sites. The contamination plume extends off-base and has affected private wells and small water systems in the Lacey area.
Washington's PFAS action levels of 10 ppt for individual compounds triggered investigations at multiple Thurston County systems. A 2024 Washington DOH report documented four public water systems in the county exceeding state action levels, leading to well shutdowns and treatment system installations.
If you are in the Lacey area or near JBLM, PFAS is not a theoretical concern – it is a documented one. The state has been proactive about testing, and some affected properties have received treatment systems from the military.
Check your water to see the latest data for your area. For PFAS at the concentrations found near JBLM, reverse osmosis is the strongest household defense. Our water filter guide identifies systems with the highest certified PFAS removal rates. Pull your detailed report for historical data, and visit our Washington page for statewide context.