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Mercury Concentrations in Fish from the St. Louis River on and near the Fond Du Lac 



Indian Reservation 



Introduction 



The Minnesota Department of Health (MDH) has listed separate advisories for three main 

 segments of the St. Louis River (above Qoquet, below Qoquet, and below Fond du Lac) in 

 the May 1992 Minnesota Fish Consumption Advisory (MDH, 1992). The upper two sections 

 of the river are the most relevant to the concerns of the Fond du Lac Indian Reservation 

 (FDLIR) because they are part of the northern and eastern boundaries of the FDLIR. The 

 fish contaminants of concern, listed by the MDH, are mercury (above Cloquet) and mercury 

 and PCBs (below Cloquet). In general, the advisory lists one meal per week as the restriction 

 for most species and sizes. Below Cloquet, however, the advisory suggests that meals should 

 be restricted to one per month for yellow perch, carp, and larger walleye. 



Because of several landfills, waste disposal sites, municipalities, industries, and the construction 

 of several reservoirs along the Sl Louis River (StLR) there exists a potential for locally higher 

 mercury concentration "hot spots" (StLR RAP, 1992; Bodaly et al.. 1984). The limited data 

 from which the consumption advisories are derived are inadequate to detect these potential 

 hot spots and may, thus, be inadequate for advising the public to limit consumption of fish 

 along this river stretch. 



The objective of this study was to quantify mercury concentrations in fish commonly caught 

 and eaten by local fishermen in conjunction with the data needs for the Subsistence 

 Fishermen/Mercury Study on the FDLIR and to provide baseline information for evaluating 

 possible mercury sources and transports. This work was initiated as part of a larger project 

 studying St. Louis River Water Resources being conducted by the Natural Resource Program 

 of FDLIR. 



Study Design 



Thirteen StLR fish study areas (Figure 1) were selected between Chambers Grove (near 

 southeast comer of FDLIR) and Paupores (near northwest comer of FDLIR). The goal was to 

 collect the widest possible range of fish sizes per species from each area in order to model 

 mercury concentrations as a function of fish size. Results of this modeling should give bener 



