Lake Eden Association
lakeedenvt.org
Eurasian Watermilfoil (EWM)
What is Eurasian Watermilfoil?
Eurasian Watermilfoil (Myriophyllum spicatum, EWM) is a non-native aquatic invasive species (AIS) recognized as one of the leading threats to lake and pond health. It originates from Asia, Europe, and North Africa and is believed to have been introduced into the U.S. by the aquarium and aquatic nursery trades. Specifically through aquarium dumping into water bodies. It is established in 48 U.S. states and in the Canadian provinces of British Columbia, Ontario and Quebec. It was first identified in Vermont in 1962. Since then it has spread to over 80 bodies of water in VT at last count.
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EWM is most often found in shallower waters, less than 13 feet, but has been found in depths of 30 feet or more. It reproduces rapidly and spreads prolifically. It left unmanaged it can overtake a lake forming a dense blanket of tangled weeds on the water’s surface and rendering boating, swimming, and fishing obsolete. It threatens the entire ecosystem of a lake by out competing beneficial native plants thereby reducing fish habitats.
Once EWM has infested a lake it is extremely difficult to eradicate unless it is caught early. Achieving control, and hopefully eradication, is expensive, arduous and takes many years. It requires a sustained and collaborative effort on the part of the local lake community, broader town community and local government. The detection of EWM in lake Eden July 2022 was considered early detection by the state and so we are optimistic that we can reduce the spread and hopefully eradicate it by continuing aggressive management measures.
What is the impact of EWM on a lake?
EWM grows faster and earlier in spring than other aquatic plants. As a result it blocks sun needed by other beneficial native plants. Over time, it outcompetes and suppresses the more beneficial native aquatic plants, severely reducing natural plant diversity within a lake and viable fish spawning and feeding grounds. EWM grows so dense that it is not conducive for fish habitats and is rarely used as a food source for wildlife, waterfowl, fish or insects. It deoxygenates the water as it dies back over the winter (root system remains intact) resulting in the death of fish and other beneficial flora and fauna.
If left untreated, Eurasian Watermilfoil will form a mass of impenetrable weeds below and on the waters surface with no or little open water areas. This blanket of tangled weeds eventually renders recreational activities such as swimming, boating and fishing obsolete. This invasive weed is a threat to the entire lake ecosystem and inherent beauty of the lake. If left untreated, the recreational asset to the town is lost, income from tourism is lost and property values decline.​
How does EWM spread?
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Humans are the main culprits for the spread. EWM can easily be transported into a lake by “hitchhiking” on boats, trailers, fishing gear, and recreational equipment that was previously used in an infested lake. It only takes a single 1” fragment to start a colony.
Milfoil is very fragile and spreads easily by fragmentation when boats, swimmers, waterfowl and fish pass through the plants. Even currents caused by winds and boats can result in breakage of this brittle weed. The smallest fragments can drift to a different area, re-root and form another colony. It is so robust that a small fragment can remain suspended in the water, through the winter, under the ice and then root in the spring. It also spreads through a root system. Although seeds are produced, it is thought that they contribute little to the spread of the plant.
Run off of phosphorus, nitrogen and other nutrients into the lake fuel its spread. Not to mention that they are detrimental to the overall water quality and ecosystem. Fertilizers used along the lakeshore are prime suspects. Runoff into tributaries from properties in the broader community are also a significant factor. Old and inadequately maintained septic tanks can leak into the water providing nutrients that fuel growth. Clearing of properties down to the shoreline is very harmful to lake health as it eliminates filtration of these harmful nutrients allowing them to seep into the lake. Maintaining healthy shoreline barriers is critical to Lake health as a whole.
How can EWM be controlled and prevented?
Despite a variety of treatment methods, Eurasian Watermilfoil is nearly impossible to eradicate once it has invaded. Current control efforts include benthic barriers, mechanical harvesting, diver operated suction harvesting, biological control using watermilfoil weevils, and targeted herbicide treatment. Due to the high costs and continuous effort required, the best management option for milfoil is spread prevention. The plant species is on the Vermont Noxious Weed Quarantine list, making it illegal to buy, plant, or transport milfoil in the state.
Because milfoil fragments can easily stick to boats and equipment, practicing the Clean, Drain, and Dry spread prevention methods is very important. Drain all water from your boat, canoe, kayak, and other vessels and any equipment used in the water. Clean vessels and gear and remove all plant fragments and dispose of properly. If possible, rinse equipment with hot and high-pressure water.
Dry all damp areas of boats and vessels, such as live wells and bilges with a towel and let air dry in the sun for at least five days before using in another water body.
Reducing run off of nutrients into the lake is also critical as they feed the milfoil. For the same reason fertilizer use should be avoided or at least limited along shoreline properties. Lawns and any clearing up to the waters edge should be minimized. Maintaining healthy shoreline barriers, with native plants, will help to filter out nutrients before they reach the water. Vigilance is the key!
What you can do to help the spread?
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Inspect boats, trailers, fishing gear, and recreational equipment before & after using in ANY water body. Remove any plant fragments and dispose of away from the lake
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CLEAN, DRAIN, DRY- Clean (ideally with hot and high powered water) and drain ALL water equipment after use. Dry thoroughly with a towel and let dry in the sun for 5 days prior to using in another body of water. This includes draining and drying of live wells and bilges.
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Avoid boating, fishing and swimming through areas of EWM. The lake association will do our best to indicate these areas with buoys and notifications.
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Remove any floating plant fragments from the lake
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Minimize clearing/lawns along lakes edge. Never clear right to the lakes edge. Maintain a healthy shoreline buffer of minimally 3-5 feet of native plants along your property’s edge.
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VT Shoreline protection act prohibits clearing within 100 feet of lakes without a permit
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VT Shoreline protection Act handbook - link
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Refrain from using fertilizers along the shoreline. VT law prohibits fertilizers with phosphorus and nitrogen (link).
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Correct any areas of soil erosion on your property
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Maintain septic systems to prevent leaching into lake
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Notify the Lake Association if you believe you have located EWM in an unmarked or new area.
How to Identify Eurasian Watermilfoil
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Eurasian Watermilfoil is a rooted, submerged aquatic plant that can grow to the surface forming dense mats.
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The leaves are green, less than 2” long and look like feathers whose tips were bluntly cut. On the waters surface the leaves can be brown to reddish in color.
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Leaves are arranged in whorls of 4 around the stem. These whorls extend the length of the entire stem.
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Each leaf will have 12 or more needle like leaflet pairs that extend from the center spine.
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The steams are light brown to reddish in color and resemble rope.
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Each plant can have many stems. The stems branch near the waters surface. Milfoil flowers in July and August and produces small, reddish flowers a few inches above the surface on spikes grown from the tips of the stems.