Washington County Lead District - Potosi

Overview

The Washington County Lead District near Potosi, Missouri covers roughly 47 square miles where lead and barite mining took place for more than 200 years. The site was added to the National Priorities List in 2008. EPA has divided cleanup into five operable units targeting residential yards, groundwater, mine waste, surface water and sediment, and abandoned railroad lines.

The main contaminants are arsenic, barium, cadmium, and lead. These metals are found in residential yard soil and in groundwater. More than 445 residential properties have heavy metal soil contamination. About 163 private wells have elevated lead or other heavy metals. People can be exposed by ingesting or touching contaminated soil or groundwater. Human exposure is not yet under control, and physical cleanup work is not complete.

EPA began emergency soil removal in residential yards in 2006 and expanded that work starting in 2016. A current contractor, EA Engineering Science and Technology Inc., started excavation in spring 2025. Work pauses each year from December 15 through February 28. About 782 properties still need soil and water sampling, and some property owners have refused access for sampling and cleanup. For groundwater, EPA signed an interim decision in 2022 to install point-of-use treatment systems for residents whose drinking water exceeds health-based lead levels. EPA is also evaluating whether restoring the aquifer across the full contaminated area is practical. Investigations for mine waste and surface water are still ongoing. The railroad lines investigation is estimated to begin between April and June 2027. A five-year review was completed in February 2022, and the next one is estimated between February and April 2027.

EPA offers free testing for yards and private wells. Residents can also access the Technical Assistance Services for Communities program, which provides free independent help including review of technical documents and facilitation of community meetings. To request testing or ask questions, contact Community Involvement Coordinator Shaylee Borcsani by phone or email. EA Engineering staff may also reach out by phone, door knocking, or mail to schedule site walks before excavation begins.