Washington County Lead District - Old Mines

Overview

The Washington County Lead District – Old Mines site spans about 90 square miles in northeast Missouri. More than two centuries of lead, barite, and other metal mining left behind contaminated soil, groundwater, surface water, and sediment. The site was added to the National Priorities List on March 19, 2008. Cleanup is divided into five operable units covering residential yards, groundwater, mine waste, surface water and sediment, and railroad lines.

The EPA has identified six contaminants of concern: arsenic, lead, barium, and cadmium. Arsenic and lead appear in both residential yard soil and groundwater. Barium and cadmium have been detected in groundwater only. More than 125 residential properties have estimated soil contamination, and about 181 private wells contain elevated levels of lead or other heavy metals. People can be exposed by ingesting or touching contaminated soil or water. Human exposure is not currently under control, meaning unsafe levels have been detected and people could reasonably be exposed.

Since 2006, the EPA has removed lead-contaminated soil from 54 residences and provided bottled drinking water to 108 homes with lead in their wells above federal drinking water standards. Remedial action for residential yards began in September 2013 and was largely completed by April 2025. A contractor, EA Engineering Science and Technology Inc., began excavating additional residential properties in spring 2025. About 920 properties still need soil and water sampling, and roughly one in three tested properties qualifies for cleanup. Property owners have frequently refused access for sampling and cleanup work. For groundwater, the EPA is installing point-of-use filters under kitchen sinks at homes with contaminated wells while studying whether full aquifer restoration is possible. Groundwater remediation started in September 2023. Work on mine waste, surface water, and sediment began in September 2019. The EPA is still searching for parties responsible for railroad line contamination, with that unit's investigation expected to begin between April and June 2027.

A Five-Year Review was completed on February 24, 2022. It confirmed that cleanup at residential properties will be protective of human health and the environment once complete. The next Five-Year Review is estimated between February and April 2027. Physical construction is not complete, and the site is not yet ready for anticipated use.

Residents can get free testing for their yards and private wells by contacting the EPA. The contractor EA Engineering will reach out by phone, door knocking, or mail to schedule access and pre-excavation site walks. The Technical Assistance Services for Communities program offers free, independent help from EPA-contracted scientists and engineers to help residents understand the cleanup process. Community members can also contact the EPA's Community Involvement Coordinator, Shaylee Borcsani, for information and resources.