Two Day County lakes added to mercury list

By George Thompson, Reporter and Farmer

The list of South Dakota lakes with high levels of mercury in fish grew again in 2012, although state environmental specialists say that doesn’t mean people need to stop eating fish.

Three lakes, including two in Day County, were added to the existing list of 12 where the state recommends limiting consumption of certain fish species. This list of lakes can be found at http://doh.sd.gov/fish/default.aspx.

The two new Day County lakes are Minnewasta and Middle Lynn for walleyes 18 inches and longer. Elm Lake in Brown County was also added for walleyes 22 inches and longer.

Other Day County lakes already on the list are Bitter for all sizes of walleyes and northern pike 30 inches and larger and Opitz Lake for northern pike over 26 inches.

Brian Blackwell, a GFP region fisheries biologist says the mercury found in area lakes occurs naturally and typically turns up in higher concentration in water bodies that have expanded or are newly created. He said the concentrationoften comes from decomposing bullrushes and works itsway through the system.

Blackwell said the two local lakes added to the list will be targeted for additional study next summer. He also noted the state agencies are contemplating lowering the recommended mercurylevels which could result in even more lakes being added to the list.

The state’s lakes and rivers are tested for metals, pesticides and PCBs as a collaborative effort by the GFP, DENR and DOH. The recommended guidelines for consumption are for healthy adults, no more than one seven-ounce meal per week (52 per year); high-risk groups (women who plan to become pregnant, are pregnant or breast feeding), no more than one seven-ounce meal per month (12 per year) and children under age seven, no more than one four-ounce meal per month (12 per year).

Blackwell pointed out that fish from these lakes can beconsumed safely simply following the recommended guidelines, adding, “The fish you buy in the grocery store (fresh or salt water) are likely to contain as much mercury as the fish in our lakes do.”