This map shows the general pattern of arsenic contamination from the Asarco Tacoma Smelter. You can also view information about other areas of arsenic contamination statewide, by searching an address or viewing that area on the map:
The Tacoma Smelter Plume map (purple, red, orange, yellow) is based on a mathematical model. The calculations are based on a relatively small number of samples, given the large area that is affected.
The map shows an estimate of the highest arsenic levels likely to be found in an area. However, a property may have lower (or higher) amount of arsenic. Property-specific sampling is necessary to determine the actual amount of arsenic on a given property.
Washington’s history of metal ore smelting left a legacy of contamination. This map depicts areas that may have soil contamination within the Tacoma Smelter Plume, Everett Smelter cleanup and Upper Columbia River Lake Roosevelt Cleanup Site. The map also depicts the five counties where soil contamination may exist from agricultural practices (lead arsenate pesticides) in former orchard lands. When available, this map shows soil sampling and soil replacement records at the property level. To locate property specific soil sampling information, please enter an address into the address search box.
The Tacoma Smelter Plume map (purple, red, orange, yellow) shows the general pattern of arsenic contamination from air emissions from the former Asarco smelter in Ruston and north Tacoma. Ecology used soil sampling data to estimate the highest arsenic levels likely to be in a given area. With 90% certainty, at least 1 in 10 parcels will have arsenic in soil at or above levels shown. Predictions are based on distance and direction from the former Asarco smelter, and on sampling data from forested and other soils undisturbed by development.
The plume map is based on relative small number of samples, given the large area that is affected. The map shows an estimate of the highest arsenic levels likely to be found in an area.
A property may have lower (or higher) amount of arsenic. Property-specific sampling is necessary to determine the actual amount of arsenic on a given property. To locate property specific soil sampling information, please enter an address into the address search box.
Tacoma Smelter Plume
For almost 100 years, Asarco operated a copper smelter in Tacoma. Air pollution from the smelter settled on the surface soil of more than 1,000 square miles of the Puget Sound basin. Arsenic, lead, and other heavy metals are still in the soil as a result of this pollution. Visit our website for more information on the history and current programs or call the Tacoma Smelter Plume Project line (360) 407-7688, press 2.
Everett Smelter Cleanup
Learn more about soil sampling and cleanup work in Everett.
Sandra Matthews – Dept. of Ecology - Project Manager
From 1905 to 1947, many apple and pear orchards used lead arsenate pesticides. These pesticides left lasting arsenic and lead contamination in the soil. In parts of Washington, former orchards have been turned into neighborhoods, schools, and parks. People living, working, and playing in these soils may be at risk.
This map depicts the five counties (Okanogan, Chelan, Douglas, Yakima and Spokane) where historical agricultural practices were high, and conversion from agricultural lands to urban development is occurring. You can take simple Healthy Actions to reduce your exposure. If you’d like to know what’s in your dirt, you can self-sample. Ecology has soil sampling guidance to help you through the soil sampling process. You can also check with your local planning department to find out if your neighborhood was built on former orchard lands.
Arsenic and lead soil sampling results are measured in parts per million (ppm), a scientific term to describe how much metal is in the soil. For example, 20 ppm of arsenic means that 20 parts of arsenic are in one million parts of soil.
Sample Result (Low)
Sample Result (Moderate)
Sample Result (Moderate)
Sample Result (High)
Under 20 ppm
Over 100 ppm
Under 50 ppm
Over 500 ppm
The Washington State Department of Ecology sets cleanup and actions levels.
Cleanup level- The cleanup level for arsenic is 20 parts per million (ppm). The cleanup level for lead is 250 ppm. Ecology sets cleanup levels based on state law- The Model Toxics Control Act. These cleanup levels protect both human health and the environment.
Action level- If you are located within the Tacoma Smelter Plume, we use an action level to offer soil replacement to the most contaminated areas, and prioritize the use of limited funding. An action level is the level of soil contamination that Ecology offers soil replacement. The action level for residential yards is 100 parts per million (ppm) arsenic or 500 ppm lead.
A property is offered soil replacement if:
The parcel average is > 100ppm arsenic or > 500 ppm lead*
A single sampling unit has > 200 ppm arsenic or > 1,000 ppm lead.
*The arsenic action level is 100 ppm, but Ecology has set a threshold level of 90 ppm arsenic and 500 ppm lead. Using a lower threshold ensures Ecology will remove and replace soil in yards over the action levels.
The majority of properties sampled in the Yard Program Service Area are above the state cleanup level but below Ecology’s action level. It is important to practice healthy actions to reduce risk. We recommend healthy actions for everyone.
Properties that receive soil replacement have the top 12-18” of soil removed and replaced with clean soil (soil below the state cleanup level).
Soil left behind
During soil replacement we work hard to remove all soil contamination that we find above the action level, however, some soil contamination may remain after soil replacement. Places where soil contamination gets left behind is at the base of trees, and under or around permanent structures (like foundations and cement pads), along fence lines or at the base of excavation. Read our Areas Excluded from Soil Cleanup to learn more about where soil may get left behind.
Rights of Way
Mapped rights of way include alleys and parking strips sampled by Asarco. ROW were sampled within the study area. Zoom into the map to locate the grey, “ROW” circles. Click on the circle to see rights of way soil sampling data.
Soil Safety and Yard Program Service Area Boundaries
The Yard Program Service Area (Yard Program Boundary) is the area where we expect 10% or more of the yards to have arsenic over 100 parts per million (ppm). On the map, the Yard Program Service Area, is the area within the light blue polygon boundary.
What do the numbers and letters mean? The numbers and letters (1,2,3 and A,B,C) within the Yard Program Boundary refer to our Soil Replacement and Soil Sampling Sequence. For information on our soil replacement sequence, please see our webpage.
The Soil Safety Program Boundary is the area within the green polygon boundary. Inside this boundary the program offers sampling in play areas at existing licensed childcares, schools, parks, and camps.
Residential yards outside of the Yard Program Service Area boundary but within the Soil Safety Program boundary can get their soil sampled through their local Health Department and the Home Soil Testing Program. The Home Soil Testing Program is for educational purposes only.
To request ADA accommodation including materials in a format for the visually impaired, call Ecology at 360-407-6790, or visit https://ecology.wa.gov/accessibility. People with impaired hearing may call Washington Relay Service at 711. People with speech disability may call TTY at 877-833-6341.