Mercury from an industrial source was introduced in the 1960's into Pickwick Lake, an impoundment on the Tennessee River in northwest Alabama. Liver and muscle tissue of catfish (Ictalurus furcatus) collected from this lake were analyzed to determine if Hg continues to be a contaminant in this system. Low concentrations of mercury were detected in all of these fish. Catfish (Ictalurus furcatus) from an adjacent upstream lake and catfish (Ictalurus punctatus) from five surrounding farm ponds were also collected. Tissue levels of Hg were found to be higher in fish from the upstream lake and from the farm ponds than those from Pickwick Lake. Although Hg is still accumulating in fish in Pickwick Lake, the source does not appear to be from the historic industrial releases. A possible source for the Hg at all the sites is atmospheric deposition from local coal-burning electrical generation plants. Mercury residues in muscle tissue did not exceed the USFDA limit for any of the catfish collected in this area.