Tar Creek sits in Ottawa County, Oklahoma, where lead and zinc mining ran from 1891 through the 1950s and 1960s. That history left behind massive chat piles, fine tailings ponds, acidic mine water, and roughly 100,000 exploratory boreholes. The EPA added the site to the National Priorities List on September 8, 1983. Cleanup is organized into five operable units covering groundwater, residential soil, a former chemical laboratory, mining waste, and creek sediment across seven watersheds spanning about 437 square miles in Oklahoma, Kansas, Missouri, and tribal lands.
The main contaminants are cadmium, iron, lead, and zinc. They appear in groundwater, surface water, soil, fish tissue, and solid waste. Lead in residential soil poses the greatest risk to human health, especially for young children who may ingest contaminated soil during play. The EPA set a cleanup goal of 500 parts per million of lead in residential soil. Residents with private wells showing lead above 0.015 milligrams per liter receive alternative water sources. As of the most recent reporting, human exposure is not under control and construction is not yet complete across the entire site.
The EPA, Oklahoma Department of Environmental Quality (ODEQ), and the Quapaw Nation are the main parties doing cleanup work. Between 1995 and 2015, the EPA excavated contaminated soil at 2,940 residential properties. A total of 628 residences, 74 businesses, and 125 renters were relocated from Picher and Cardin, Oklahoma, and Treece, Kansas. About 7 million tons of mine source material has been cleaned up, and nearly 5,000 acres have been remediated. The Quapaw Nation removed roughly 107,000 tons of chat from a culturally significant 40-acre tract. Passive treatment systems at Mayer Ranch and Southeast Commerce treat contaminated mine drainage. Work on mining waste continues, with some remedial actions planned for 2027 and 2028. The sediment unit is still in the remedial investigation and feasibility study phase.
The EPA completed its Seventh Five-Year Review in September 2025. It found that remedies at Operable Units 1, 2, and 4 are protective of human health and the environment for addressed pathways, but identified seven recommendations for improving long-term protectiveness. The site supports 90 on-site businesses employing 1,233 workers and generating about $195.3 million in annual sales.
Residents throughout Ottawa County can request free yard sampling by calling the ODEQ project manager at 405-702-5138 or 1-800-522-0206. The EPA hosts an annual Tar Creek Open House and Healthy Communities event offering free residential yard testing sign-ups, blood lead testing for children 15 and under, and household lead contamination testing. Site documents are available at the Miami Public Library in Miami, Oklahoma and at the ODEQ office in Oklahoma City.
