Study: Potentially harmful chemical used in area lakes and ponds

The DNR doesn't put the toxin directly into Clear Lake, but they have spread it in Ventura Marsh, which is attached to Clear Lake.

Posted: Jul 18, 2018 10:15 PM
Updated: Jul 19, 2018 6:43 AM

CLEAR LAKE, Iowa- Dave Howlett and his granddaughter, Brandy, are two of thousands of people who swim in Clear Lake every year.
“It’s kind of like our home away from home,” he said.
But a study done by the Environmental Health Perspective shows that a compound know as rotenone can lead to developing the central nervous system disease, Parkinson’s.
“I never heard of that,” said Howlett.
We reached out to the Iowa DNR Wednesday. They said rotenone is commonly used to kill invasive species in area lakes and ponds as well as manage fish and improve water quality.
They don’t put the toxin directly into Clear Lake, but they have spread it in Ventura Marsh, which is attached to Clear Lake. If you are still wondering what exactly rotenone is, the Iowa DNR describes it as a naturally occurring compound that is derived from the roots of a tropical plant in the bean family. The study was done on farmers who use the chemical on their crops and those with the DNR said the spray they use us only 5% Rotenone. They said in small amounts it shouldn’t have any impact on those swimming like Howlett and Brandy, which is a good thing because they plan to continue regardless.
“I want to enjoy my time out here,” he said. “There are a lot of things that can be bad for your health, but with a little moderation and being wise, you can still have fun.”
The complete statement from the Iowa DNR is below:
"One part of lake restoration projects is to remove all undesirable fish species that have detrimental impacts to the aquatic vegetation, fishery, and water quality. It's imperative that successful removal of these fish species occurs in order to achieve water quality and public recreation goals with these projects, prior to refilling the lake.
Rotenone, a botanical pesticide, is the only management tool that has been proven to remove all of the fish from a waterbody or stream. It is used world-wide and has been since the 1930s. It is a common tool for fish managers when managing sport fish, improving water quality, or for endangered species management. Rotenone is a naturally occurring compound that is derived from the roots of a tropical plant in the bean family. We commonly use the commercially available formulation, 5% Prenfish, which has been approved for fishery management by the U.S. Environmental Protection Agency (EPA). The EPA has concluded that the “use of rotenone for fish control does not present a risk of unreasonable adverse effects to humans or the environment”. The EPA certifies all pesticides based on use according to label directions and the Iowa DNR is equipped to fulfill these obligations. Without this very necessary step in the lake restoration process, much of the benefit to water quality and angling will not be realized.

The DNR and other agencies meet with stakeholders during public meetings explaining the project and use of Rotenone, prior to the project beginning.
Regarding alternatives, we use alternatives when we can, such as fish removal (capture) and alternative methods such as dewatering. At this time, we are not considering scaling back the use of Rotenone."

Typically the DNR spends on average between $50,000-$100,000 annually on Rotenone.

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