Southern Shores weighs use of 2,4-D herbicide in canals to control milfoil

Published 2:29 pm Friday, June 28, 2024

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Before the Town of Southern Shores made a decision about how to treat milfoil, an invasive weed found in the town’s canals, council members heard an online presentation from NC State professor Dr. Paul Richardson at their June meeting.

Richardson explained what milfoil is and why the growth has been increasing in canal waters. Milfoil grows in the sediment layer, and while some presence of the aquatic plant can provide food, shelter and a breeding habitat for fish and wildlife, as well as protection from erosion, too much of the plant can make waters murky and unpleasant for swimming and boating. Warm waters, rainfall, storm events and time can increase milfoil.

Eurasian watermilfoil is especially problematic in warmer areas. Their featherlike leaves are bright green or reddish. Milfoil is a perennial that forms what Richardson called really dense mats that prevent native plants from thriving.

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Invasive aquatic plants can cause damage such as clogging drainage ditches, tangling boat propellers, and preventing native fish and wildlife from thriving. Eradication of the plant may not be possible, Richardson said, but options for management and reduction of the weed are available.

Richardson went through a long list of options to treat milfoil. These included hand weeding, which can only be done on a very small scale, to mechanical techniques similar to mowing or raking the milfoil. These can be temporarily effective but also may disturb turtles, fish and macroinvertebrates. Other options include placing a physical barrier on the bottom of the canal floor, but again, this affects other living organisms.

The introduction of triploid grass carp would eat the milfoil, but there is the risk of the fish getting into the sound waters. Milfoil weevils will feed on the plant but not at the rate necessary to bring resolution to the problem.

Lastly, Richardson introduced another option: the use of herbicides. After explaining several options, he introduced 2,4-D, an herbicide used since 1949 in the United States that affects the plant hormonally, causing it to grow at an unsustainable rate and thereby causing its death.

Richardson said 2,4-D does not bioaccumulate “in either plants or fish or anything else” and there is an extensive history of use. He again clarified this point when council members asked if the herbicide would affect fish or people.

If used in Southern Shores, it would be either injected under the surface of the water or spread as granules that would sink down to the bottom of the canals. It would not be sprayed. Treatment would last between 18 months and four years. It could be reintroduced to canals from boats coming in from the ocean with milfoil attached.

Council member Paula Sherlock questioned Richardson on the safety of the product: “As you probably know, this is a community that’s very sensitive to environmental issues and we have a number of residents that have expressed concerns to us because 2,4-D was a component in Agent Orange and frankly that’s concerning to me. Can you comment on that?”

Richardson replied that Agent Orange had two herbicide compounds: 2,4-D and 2,4,5-T. During the manufacturing process, as a result of a lack of refinement, 2,4,5-T produced dioxin, which is very toxic. This herbicide was later pulled by the EPA and banned; but 2,4-D was deemed suitable for continued use.

Mayor Elizabeth Morey asked about negative effects on non-target flora and fauna. While Richardson said the EPA will not say that a pesticide has no risk, he did say that the department has assessed an extremely low risk associated with the use of 2,4-D to non-target vegetation.

“So even though they impact plants, something that eats a plant is not going to accumulate 2,4-D and it won’t get passed up the food chain,” Richardson stated. He relayed long-term studies on farm workers who apply the herbicide and have not been reportedly affected by it.

When asked by council member Matt Neal for a recommendation, Richardson replied:

“It doesn’t matter to me whether you all manage or don’t manage or which management technique you use. What I would care about is that if you’re going to use a management technique that you use it as well as possible and that you formulate decisions that you know are based on how you need to use those water bodies. I can’t sit here and tell you that you should manage if you get to a certain point. What I would say is, do you get to a certain point where users of your water bodies are impacted? Do you get to a certain point where Eurasian watermilfoil growth is so excessive that it blocks out other plants, other organisms? So these are the things that you would need to either document or think about when you’re thinking about management. At what point to you all does Eurasian watermilfoil really start to impact what you need to be happening from your water bodies? So it’s really based on local needs and local goals for your water body more so than what I think that you should do or not do.”

After disconnecting the online video call, the council opened up the floor to input from residents.

Tommy Karole spoke to council about his concerns with the herbicide, citing a recent Wisconsin study that found its use detrimental to wildlife.

Karole also said that his research has revealed that 2,4-D has been linked to leukemia in children, birth defects, reproductive problems, soft tissue sarcoma, non-Hodgkin’s lymphoma, disrupted liver functions, neurotoxicity like the development of ALS, loss of smell, liver damage, and endocrine disruption.

“I’m going to pass some of that information on you. I can send links, I can bombard you with this,” Karole said to council members. “This is bad stuff. Thank you guys. I appreciate you looking into this and putting the brakes on it when you did at least for us to take a look.”

Town manager Cliff Ogburn agreed to coordinate a comprehensive study of the Southern Shores canals for the presence of milfoil.

“I think we need to know the extent of the problem before we consider some risky solution so, yes, I’m all for it,” said Sherlock.

Council voted unanimously to approve spending for a comprehensive survey.