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Washington County Lead District - PotosiPotosi, Missouri
 Washington County

iconSite Location:
   The Washington County Lead District - Potosi site includes soil and groundwater contaminated with arsenic, barium, cadmium, and lead associated with historical mining practices in southeast Missouri. The site is located near the eastern Ozark Mountains in southeastern Missouri. Currently, the Potosi area encompasses approximately 40 square miles in the central eastern portion of Washington County, Missouri.

iconSite History:
   Washington County is part of Missouri's Old Lead Belt, where lead mining has occurred for hundreds of years. The Old Lead Belt provided approximately 80 percent of the lead produced in the United States. In Washington County, the first mines were mostly surface diggings advanced by manual labor with a pick and shovel. Starting in 1799, deeper mines were started in the area. Additionally, this area is part of the barite mineralization district of Missouri. After the Civil War, numerous small barite mines operated in Washington County in the early 1900s. Barite mining boomed in 1926 as the mineral's use for oil drilling mud was discovered and for a number of years, Washington County was the world's leading producer of barite before declining in the 1980s. Many of the later large mining operations reworked lands that were previously hand mined for galena (mineral source of lead) or barite. Washington County has hosted over 1,000 lead and barite mining, milling, or smelting sites.

iconSite Contamination/Contaminants:
   The Potosi area includes source piles, tailing ponds and residences with elevated levels of lead throughout the area. The piles primarily consist of overburden and tailings from mineral mining and processing. Ground water serves as the source of drinking water for numerous private and several public wells. There are 158 residential properties contaminated with lead. There are 138 private residential wells contaminated with lead significantly greater than the Safe Drinking Water Act Maximum Contaminant Level (MCL).

iconPotential Impacts on Surrounding Community/Environment:
   Soil and groundwater in the area contains contaminants typically associated with historical mining districts, including arsenic, barium, cadmium, and lead. Soil contamination is present at elevated concentrations at a number of residential properties. Lead has been detected in the ground water significantly greater than its MCL.

iconResponse Activities (to date):
   EPA is providing bottled water to 120 residential homes. Other response activities include excavation of 58 residential yards. A repository for the contaminated residential yard soil has been established at a former lead tailings impoundment in Washington County.

iconNeed for NPL Listing:
   The State of Missouri and EPA evaluated other cleanup programs and no other viable options were available. EPA received a letter of support for placing this site on the NPL from the State of Missouri.

[The description of the site (release) is based on information available at the time the site was evaluated with the HRS. The description may change as additional information is gathered on the sources and extent of contamination. See 56 FR 5600, February 11, 1991, or subsequent FR notices.]

For more information about the hazardous substances identified in this narrative summary, including general information regarding the effects of exposure to these substances on human health, please see the Agency for Toxic Substances and Disease Registry (ATSDR) ToxFAQs. ATSDR ToxFAQs can be found on the Internet at ATSDR - ToxFAQs (http://www.atsdr.cdc.gov/toxfaqs/index.asp) or by telephone at 1-888-42-ATSDR or 1-888-422-8737.

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