More South Dakota Lakes Make Mercury Advisory List

My morning paper reminds me that fish in a couple of area lakes continue to carry a bit too much mercury. The Department of Health now posts mercury fish consumption advisories for 21 lakes, up from 16 two years ago.

Mercury Advisory Lakes red triangle: advisory lake blue fish: tested lake Source: SD Dept. Health, screen cap 2016.05.17
Mercury Advisory Lakes
red triangle: advisory lake
blue fish: tested lake
Source: SD Dept. Health, screen cap 2016.05.17


County Lake Fish Species
Brookings/Kingsbury Twin Lakes Walleye – 18″ & larger
Northern Pike – 19″ & larger
Brown Elm Lake Walleye – 25″ & larger
Butte Newell Lake Walleye – 18″ & larger
Northern Pike – over 18″
Clark Reid Lake Walleye – over 23″
Swan Lake Walleye – over 21″
Codington Long Lake Walleye – over 17″
Corson Pudwell Dam Walleye -18″ & larger
Black Crappie – over 12″
Day Bitter Lake Walleye – all sizes
Northern Pike – 30″ & larger
Hazeldon Lake Walleye -21″ & larger
Lake Minnewasta Walleye -18″ & larger
Lardy Lake Walleye -25″ & larger
Lynn Lake Walleye -18″ & larger
Middle Lynn Lake Walleye -18″ & larger
Opitz Northern Pike – over 26″
Dewey Lake Isabel Northern Pike – 25″ & larger
Largemouth Bass – 17″ & larger
Kingsbury/Brookings Twin Lakes Walleye – 18″ & larger
Northern Pike – 19″ & larger
McCook/Minnehaha North Island Lake Walleye – 18″ & larger
Smallmouth Bass – 18″ & larger
Minnehaha Twin Lakes Walleye – all sizes
Perkins Coal Springs Reservoir Northern Pike – over 25″
Potter Lake Hurley Largemouth Bass – 18″ & larger
Tripp Lake Roosevelt Largemouth Bass -18″ & larger
Northern Pike – over 24″

We’re not talking about killer walleye. Our Department of Health simply recommends not eating fish from the listed lakes more than once a week—or, if you’re pregnant, once a month:

Fish is an important source of high-quality protein that provides many health benefits. At the 1ppm mercury level, the Department of Health recommends that people space their meals of such fish to limit consumption to safe levels. The department’s advisory follows the FDA’s action level and recommends that healthy adults eat no more than 7 ounces of fish per week with mercury levels close to or slightly above 1ppm. Women who plan to become pregnant, are pregnant or are breast-feeding, and children under age seven should eat no more than one 7 ounce meal of such fish per month [South Dakota Department of Health, “Mercury and Fish Consumption,” downloaded 2016.05.17].

Mercury gets into our lakes from burning coal, mining (particularly gold), and manufacturing and trashing commercial products made with mercury. (Interestingly, the lakes closest to South Dakota’s last major coal-burning power plant, the Big Stone Power Plant north of Milbank, don’t make the mercury advisory list.) We are reducing mercury emissions by phasing out products containing mercury and requiring stricter emissions controls at power plants, but we’re stuck with significant quantities of mercury in our land and water from all of our past mercury activities. When our lakes expand or flood, they grab mercury from more surrounding soil, and their little fishies become more mercurial.

As long as mercury remains in the soil, it will be difficult to get the above lakes off the mercury warning list. But it doesn’t hurt to decrease mercury emissions now, not just in South Dakota but worldwide, so future generations can eat more walleye.

26 Responses to More South Dakota Lakes Make Mercury Advisory List

  1. Makes you wonder if they are going through and testing the Mercury/Selenium ratio in these fish before posting these advisories.

    Mercury and Selenium have a relationship as such that they cancel eachother out as long as they are present in a 1 mercury:1 selenium ratio in what you consume. If you consume a fish with more selenium than mercury, you are getting none of the harm of the mercury and the benefit of the selenium. In salt water fish, the fish that tend to have more mercury than selenium tend to be the tertiary consumers like sharks and tile fish.

    A diet with an appropriate amount of selenium can have a positive effect on fetal development and has been associated with an approximately 5 point increase in IQ, so selenium is actually more important than the negated health detriment of the mercury.

    If the number of lakes in SD where this is a concern is increasing, it might be worth studying the Se:Me ratio to see if the fish are actually over exposed to mercury. Instead of having to place fear in the fishing public, they can be promoting the health benefits of South Dakota fish (negative tourism to positive tourism).

  2. Robert McTaggart

    “Today only natural gas can provide suitable source of electricity generation that can replace base-load coal and the dispatching flexibility to meet daily changes in demand and thus, provide system reliability.”

    Nuclear can deliver the energy that is desired to replace coal, but it needs to reduce construction costs to better compete economically with natural gas. Renewables have the advantage of low fuel costs, but they need breakthroughs in energy storage to deliver the amount of energy required to replace coal.

  3. Paul Seamans

    I believe that all the waters in North Dakota are under this advisory. They must be willing to share their mercury with South Dakota. Makes a person wonder when people start hollering states rights when we have to accept North Dakota’s mercury blowing and flowing across our borders.

    People along the Cheyenne River, especially below where the Belle Fource River joins the Cheyenne, would be well advised to not eat fish out of that river. There are deposits of soil from mining activities that are high in arsenic. But Gov. Daugaard says these polluting activities create jobs, so… I had hopes for Daugaard at one time. I was wrong.

  4. MD, I assume I can’t chug a shot glass of mercury, chase it with an equal volume of selenium (in solution, of course), and come out feeling great. Does selenium occur naturally in our waters? Are there anthropogenic sources of selenium that would increase the concentration to counter that nefarious mercury?

  5. Paul Seamans

    I don’t know anything about the relationship between mercury and selenium but I have had a little experience with selenium. In my area there are cases of selenium toxicity, probably worse as you go from Vivian to Ft. Pierre on Hwy 83. With high selenium chicken eggs won’t hatch, horses hooves will fall off, and cattle’s coats with be dull. Cattle buyers can spot cattle that have been getting too much selenium when they come into the sale ring. They will be dull and whitish. One reason that the federal government bought up the land that became the Ft. Pierre Grasslands is because farmers were not making a go of it on the high selenium soils.

    Maybe this would be a good area to build a coal fired power plant. Burn coal with a high mercury content.

  6. And that’s not pollution, right, Paul? That’s just natural soil content? Is there any scientific explanation for why your soil has higher selenium than the rest of the state?

    Did that high selenium have the same effect on the buffalo two centuries ago?

  7. Selenium is a naturally occurring, potentially toxic trace element that became an issue of great public concern in California in the early 1980s with the poisonings and deaths of wild birds at the Kesterson Reservoir. Subsequent analysis indicated that selenium in agriculture drainage water was responsible. Ever since, Tokunaga and some two dozen other LBL researchers have been learning how to control selenium contamination.

  8. Nick Nemec

    Cory, SDSU has done extensive research on selenium and its effects. Selenium occurs naturally in some SD soils, primarily West River, it is an essential element for the human diet but can be easily overdone. Wheat grown in high selenium areas can command a premium based on its selenium content. Flour ground from such wheat is mixed with regular flour to make selenium fortified flour.

    Interestingly SDSU historians have documented instances of US Calvary horses at South Dakota Missouri River outposts being sore footed and unable to keep up with Indian ponies. It is speculated that the Army horses grazed strictly around the post on grass growing in areas now known to be high in selenium while Indian ponies grazed wherever the tribe traveled and were less likely to get an overdose of selenium.

  9. Nick Nemec

    Good grief, cavalry not calvary.

  10. Spanish mustangs’ reputation is to outlast the hell out of big grain fed cavalry mounts.

    someone said the other day their often horizontal stripes across the knees are reminders of zebra ancestry.

  11. Nick, good links! The selenium apparently comes from the marine shales from the ancient inland sea that covered the area.

    If we raised a lot of wheat in the area, would it eventually deplete the soil of selenium?

  12. Robert McTaggart

    I think Selenium is an antioxidant, and there are markets that like selenium-enriched food products. But too much of a good thing can be bad.

  13. Nick Nemec

    Reducing selenium through removal of plant matter might be a project for the generations if not eons. I suspect the best we can do is manage it and deal with things as they are.

  14. Don Coyote

    @cah: “Interestingly, the lakes closest to South Dakota’s last major coal-burning power plant, the Big Stone Power Plant north of Milbank, don’t make the mercury advisory list.”

    It might be because much of the mercury deposited (50%+) comes from natural sources such volcanoes and forest fires. The prevailing westerlies will bring all that smoke from the yearly forest fires out west and any volcanic eruption. Mercury emissions showed a huge spike after the eruption of Mt St Helens.

  15. Nick Nemec

    And since the Big Stone plant is nearly on the Minnesota line, the prevailing west winds would tend to blow that pollution to Minnesota.

  16. Dr. McTaggart is right again. My good friend Lar wanted to me to tell you that according to a show called Star Track, they say “too much of anything, even love, can be a bad thing.”

  17. mike from iowa

    The only American study of selenium that included the word Buffalo was done at the U of Buffalo and was about an increased risk of Type 2 diabetes in humans from multi-vitamins.

    The tests with actual buffalo were conducted in Brazil,South Africa, Egypt and possibly India.(The ones I found,anyway)

  18. Donald Pay

    I’m heartened that there are no “mercury deniers” claiming that a “low level” of mercury emissions spewing from coal-fired power plants is “natural” and “good for you.” Apparently (or maybe I missed it), righty think tanks aren’t being paid to manufacture “studies” and righty astro-turf groups aren’t being funded to agitate for more mercury in our food chain, as they are being paid for greenhouse gases nuclear power, etc. But, then, the climate change deniers are actually helping to keep those mercury emissions coming, however, unwittingly. Of course, Republicans always have their boxers in a bunch when anyone attempts to limit or reduce the amount of mercury and other toxics emitted from stacks. Better you can’t eat the fish you caught than have their corporate campaign donors have to clean up their emissions.

  19. mike from iowa

    Here’s the skunk at the picnic as Mr Pay suggests-

  20. mike from iowa

    European Bison (wisent) is the only species of animal that looks anything like America’s bison and I haven’t found any selenium tests done on them.

  21. Robert McTaggart

    The half-life of things like mercury and arsenic are…..infinite. They always stay chemically toxic, so I would rather not try to build up a tolerance to those kinds of elements. Maybe one could either physically isolate them or render them chemically inert under certain conditions, but most of them are either released via emissions or kept in the coal wastes.

    The best use of mercury that I have seen is its use in a reflector for a telescope. Because it is a liquid metal, you can rotate a body of liquid mercury into a curved shape with centripetal force. The surface oxidizes so you have a nice, smooth surface….until bugs impact it. So you have to rebuild the surface every so often. But that is a very niche application, not something the average backyard astronomer would be permitted to do.

  22. Donald Pay

    The real problem with mercury is that when it gets into the environment (as through the stacks) it just doesn’t stay elemental mercury. It falls out onto the soil or water, becomes available to certain bacteria which transform it to methyl mercury. Methyl mercury then bioaccumulates up the food chain. My understanding is that methyl mercury tends to concentrate in the muscle of fish and other organisms, so it is rapidly circulated to humans.

  23. Robert McTaggart

    It would be great if there were a different bacterium that would fix the mercury into a chemistry that would inhibit its bioaccumulation.

  24. More than 50% from natural sources, Don? Once again, you may be wrong:

    “In 1995, it was estimated that forty percent (32 metric tons (t)) of mercury deposited form the air onto U.S. water and soil came from the global mercury reservoir. The other sixty percent came from anthropogenic sources in the U.S.

    “Mercury (Hg) in soils has increased by a factor of 3 to 10 in recent times mainly due to combustion of fossil fuels combined with long-range atmospheric transport processes.”

    Approximately 70% of environmental mercury now comes from human activities including a variety of industrial processes; coal burning, incineration or disposal of mercury-containing products, the use of mercury for chlorine production in the chlor-alkali industry, production of zinc, steel and other metals; cement production, mining and product recycling.”

    As I said above, reducing our emissions of mercury doesn’t make all the mercury already emitted suddenly disappear. But it would help us move that process in the right direction for future generations.