What is MERCURY (HG)
Mercury is a naturally occurring element that is toxic to humans and animals. Activities such as burning coal and processing taconite release mercury into the air.
"Mercury released into the atmosphere is mainly in elemental or inorganic forms. Mercury in the atmosphere can travel long distances. When mercury is deposited to an aquatic environment bacteria can convert it to an organic form, methylmercury. Methylmercury can accumulate in fish via bioaccumulation. Fish that are long-lived and higher on the food chain contain the highest levels of methylmercury. Consumption of fish is the major source of human exposure to methylmercury. Mercury in fish is primarily the methylmercury form." * quoted from A Protocol for Mercury-based
Fish Consumption Advice provided by the MN Department of Health .
Clearwater Lake has been on the restricted fish consumption list since 2010. The 2019 data was requested and received by Lake owner Jeff Zernov this winter.
MN DNR tested Mercury in Clearwater Lake fish in 2007 and 2019. The raw data can be viewed in this report from the DNR: Clearwater Lake Mercury Levels.
Recommended fish meals by Parts Per Million
Calculating the limit of fish meals you should eat is a complicated process to define. Please see the MN Department of Health web page on fish consumption guidance for more details. They have put together the following chart.
It warns us to not eat more then 1 meal a month of Northern or Walleye from Clearwater Lake. And no more than 1 meal a week of Small or Large Mouth Bass.
Please see the MN Department of Health web page on fish consumption guidance for more details.