Tacoma, Washington gets most of its drinking water from the Green River watershed — a protected forested area on the western slope of the Cascades that produces some of the cleanest municipal source water in the Pacific Northwest. Tacoma Water serves about 330,000 people in the city and surrounding Pierce County.
The source water is genuinely excellent. But Tacoma’s environmental history adds layers of complexity that residents should understand.
The ASARCO Smelter: Tacoma’s Superfund Legacy
The ASARCO copper smelter operated on Commencement Bay from 1890 to 1985, and its stack emissions deposited arsenic, lead, and other heavy metals across a vast area of the Puget Sound lowlands. The Tacoma Smelter Plume is one of the largest Superfund sites in the country — contaminated soil extends across approximately 1,000 square miles of King and Pierce counties.
This doesn’t directly contaminate Tacoma’s drinking water supply (which comes from the Green River, not local groundwater). But the arsenic and lead in soil throughout the region affect groundwater quality and create exposure risks for residents — particularly children who play in contaminated soil.
The EPA’s cleanup has focused on soil removal and replacement in yards, schools, and parks. If you live in the smelter plume area (which includes most of Tacoma, portions of Seattle, and communities in between), the Tacoma-Pierce County Health Department can test your soil.
Joint Base Lewis-McChord: PFAS
Joint Base Lewis-McChord (JBLM), the massive military installation south of Tacoma, has documented PFAS contamination from decades of AFFF firefighting foam use. PFAS has been detected in groundwater beneath and around the base, and some off-base private wells have been affected.
The Department of Defense has been conducting investigation at JBLM and providing alternative water supplies to affected residents. The contamination plume extends into portions of Lakewood and other communities near the base.
Tacoma Water’s Green River supply isn’t affected by JBLM’s groundwater contamination — different watershed entirely. But residents on private wells in southern Pierce County, particularly near JBLM, should test for PFAS. Washington State has adopted some of the most stringent PFAS standards in the country, with state action levels of 10 ppt for PFOA, 15 ppt for PFOS, and varying levels for other PFAS compounds.
Commencement Bay Superfund Site
Tacoma’s industrial waterfront — Commencement Bay — is a separate Superfund site from the smelter plume. Decades of industrial activity including pulp mills, chemical manufacturing, oil refining, and the smelter contaminated bay sediments and nearshore groundwater with heavy metals, PCBs, and other pollutants.
Again, this doesn’t affect Tacoma’s municipal drinking water supply. But it affects the environmental health of the community and the quality of groundwater in industrial areas of the city.
Green River Watershed Protection
Tacoma’s drinking water advantage is its source. The Green River watershed is largely owned by the City of Tacoma and managed for water supply protection. Public access is restricted. The forest cover provides natural filtration, and the water quality at the intake is consistently excellent.
This protected watershed is why Tacoma operates under a filtration avoidance determination from the EPA — like New York City and a handful of other cities, the source water is clean enough that full filtration isn’t required. Tacoma uses UV disinfection and adds chloramine for residual protection in the distribution system. Fluoride is added as well.
The long-term risk is wildfire. The Pacific Northwest fire seasons of recent years have raised concerns about what a major fire in the Green River watershed would mean for water quality. Tacoma has invested in watershed monitoring and fire prevention, but a severe fire could temporarily compromise the source water quality that makes the current treatment approach work.
Distribution System and Lead
Tacoma’s distribution system is generally newer than East Coast cities, but some older neighborhoods have galvanized steel and potentially lead service connections. Washington State’s proactive lead testing requirements have identified some homes with elevated lead levels.
Tacoma Water has been working through its lead service line inventory and tests water at representative homes throughout the system. The utility’s corrosion control program maintains water chemistry that minimizes lead leaching.
What Residents Can Do
- Check your soil. If you live in the ASARCO smelter plume area, get your soil tested for arsenic and lead — especially if you have children or garden.
- Private well owners near JBLM: Test for PFAS immediately. Washington’s standards are strict, and contamination near the base is documented.
- Filter for lead. Even with good source water, older homes may have lead risks. NSF/ANSI 53 certified filters work.
- Support watershed protection. Tacoma’s Green River source is a remarkable asset. Keeping it protected from development and wildfire is critical.
If you’re concerned about your water quality, a certified water treatment professional can test your water and advise on the right treatment approach.
For more Washington State coverage, see our report on Spokane water quality.
Sources: Tacoma Water, Washington DOE, EPA SDWIS, Tacoma-Pierce County Health Department, USGS