Tar Creek Superfund Site
	Click on map for larger view or click on "Tar Creek Superfund Site" for a close up of that area.

The Tar Creek Superfund site, also known as the Picher Lead/Zinc Mining District, is located in the far northeastern corner of Oklahoma (Figure 1) near the Oklahoma/Kansas border. The site is part of the Tri-State Mining District that includes areas of Kansas and Missouri and was one of the world’s largest lead and zinc mining areas. Mining activity in this area began in 1891 and continued up until the 1970’s during which an estimated 1.7 million tons of lead and 8.8 million tons of zinc were produced.

The Tar Creek Superfund site is now one of the largest Superfund sites in the United States covering an area of approximately 50 square miles and estimated costs of remediation and monitoring ranging from $540 million to $61.3 billion. It was added to the EPA’s Superfund National Priority List on September 8, 1983.

The site is situated in northern Ottawa County and encompasses the towns of Picher, Cardin, Quapaw, Commerce, and portions of North Miami (Figure 2). Approximately 6,400 residents live within the site boundaries.

Tar Creek is the principal drainage system for the Picher Field area, and is a small ephemeral stream characterized by standing pools. Tar Creek flows southerly between the towns of Picher and Cardin and on to its confluence with the Neosho River, one of the two major rivers in northeastern Oklahoma. Along with its major tributary Lytle Creek, Tar Creek drains approximately 53 square miles of area.

Beneath approximately 2,500 acres of this site lie around 300 miles of underground tunnels, and more than 1,300 mineshafts. The Boone Formation was the source of metal ore and is also an aquifer. When mining operations were active, large volumes of water were pumped from the mine workings until mining ceased. Since then, the aquifer and mines began refilling, during which native sulfide materials, which had been oxidized by exposure to air, dissolved, creating acid mine drainage. As a result, the Tar Creek water body has been contaminated with acid mine drainage which has also created a threat of contamination to the underlying Roubidoux Aquifer.

In addition to surface water contamination, there is a significant solid waste problem in the form of mine tailings also known as “chat” piles. The mine tailings were waste by-products of the mining process and were disposed of in piles, flotation or tailing ponds. The chat piles contain high concentrations of heavy metals and vary in size and shape with some as high as 200 feet. The U.S. Geological Survey and the U.S. Army Corps of Engineers estimate that the site contains approximately 75 million tons of chat where many of the chat piles are located near residences in the towns of Picher and Cardin (Figure 3). Some two-thirds of the nearly 300 original chat piles have been partially excavated, with chat being sold as a construction product and as fill in road gravel.