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NPL Site Narrative for Milltown Reservoir Sediments
MILLTOWN RESERVOIR SEDIMENTS
Milltown, Montana
Federal Register Notice: September 8, 1983Conditions at listing (December 1982): In May 1981, Missoula County took routine samples from seven drinking water wells in Milltown, Montana. Four showed levels of arsenic that exceed the Interim Primary Drinking Water Standard. Subsequent analyses by the State confirmed that the four wells, serving a total of 35 residences, were contaminated with up to 10 times the standard of 0.05 milligram of arsenic per liter (mg/l). Residents were advised to seek alternate supplies of drinking water.
Possible sources of contamination are leachate from an abandoned landfill east of town or dissolution of metals from mill tailings, the sediments deposited behind Milltown Dam located south and immediately adjacent to the town and across the Clark Fork River. Analyses of these sediments show total recoverable arsenic levels of up to 148 mg/l.
Status (July 1983): In June 1983, EPA awarded the State $513,000 to conduct a remedial investigation to determine the extent and sources of contamination at the site and a feasibility study to identify alternatives for remedial action. The work is scheduled to be completed in the first quarter of 1985.
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 http://www.atsdr.cdc.gov/toxfaq.html or by telephone at 1-888-42-ATSDR or 1-888-422-8737.