By Tom Latta

Aquatic Invasive Species are a critical threat to our lakes and communities. Not only do they degrade the quality and appeal of our lakes, the presence of AIS can reduce property values and even hurt our businesses and economy. If you love your lake and want to see it preserved for future generations, become informed and active about AIS eradication. While some of the lakes in the Memphremagog Watershed are presently free from Eurasian Milfoil and other aquatic invasives, it is important that we all do our part to keep them that way.

Aquatic Invasive Species (AIS) are present in many Vermont lakes. While Eurasian Milfoil is among the most prevalent, Curly Leaf Pondweed, Starry Stonewort, Purple Loosestrife, Phragmites, Yellow Flag Iris, and Flowering Rush are all found in Lake Memphremagog. While the Zebra Mussel was first discovered in 2017 around the Magog area on the Canadian side of Lake Memphremagog, monitoring indicates a widening presence and potential spread, which poses a serious threat to our region.

High-risk areas for spreading AIS are boat ramps, public docks, marinas, shallow bays, and stream entrances. Eurasian Milfoil, like many other invasives, moves from lake to lake on boat propellers, trailers, anchors, boat bilges, fishing gear, duck decoys and even footwear. Milfoil, like other plants, moves by fragmentation: small pieces of a plant can be easily broken off by a boat motor, kayak paddle or a fishing lure, float around the lake and take root to start a new infestation. 

Educating the public and increasing awareness among recreationalists are key to preventing spread and to keeping AIS from jumping to other areas or lakes. Here is what you can do to help: 

Learn – Educate yourself and others how to identify, avoid and dispose of AIS

• Learn to identify AIS plants and animals when on or in the water (many invasives are very similar to their native Vermont cousins). Check out these websites: VT Dept of Environmental Conservation and VT Fish & Wildlife.
• Boaters and paddlers should stay clear of infested areas. Fragments are easily spread by propellers and paddles.
• Always properly dispose of any fragments away from the water.
• Waterfront owners can inspect their waterfront for AIS and hand-pull any found and dispose of all fragments properly away from the water.

Inspect – Develop the “Clean, Drain, Dry” habit!

• Boaters should carefully inspect their boats and trailers for ‘unwanted hitchhikers’ before launching and after taking them out of the water.
• Fishermen should make sure boating and fishing gear are clear of any fragments before putting them into the water and when taking them out.
• Paddlers should make sure the outside and inside of their boats as well as their paddles are clear of any fragments and mud (or substrate).
• Waterfowl hunters should ensure that decoys, lines and weights, blind material, watercraft, and waders are clear of any fragments.

Support – VIP, the Public Access Greeter Program & MWA

• Become a Vermont Invasives Patroller (VIP). For information, go to the VT DEC website.
• Support the Vermont Public Access Greeters. They educate, inspect, and when needed, clean boats in order to prevent the spread of these invasives. They make a difference!
• Join the Memphremagog Watershed Association (MWA) as a member, donor or volunteer. Together, in numbers, we can increase awareness.

AIS Management – Removal Methods 

Fighting AIS spread is an on-going battle! MWA has hosted several Phragmites Pulling Parties this summer at Prouty Beach, to do our part in fighting back the spread at one area on our beloved lake. Below are some options to consider for your property or to assist in public places. Some methods do require a permit. 

• Hand-pulling is something that can be done but sometimes requires a permit. For the most part, if someone wants to clear aquatic vegetation around their dock, they can do so by hand without a permit. But if the whole neighborhood or an association gets together, there may be additional considerations. There are exceptions for the hand pulling without permit described in https://dec.vermont.gov/watershed/lakes-ponds/permit/control/aquatic-nuisance-control .
• A benthic barrier is a solid or mesh type barrier that is laid on the lake bottom and blocks the sunlight to the plant growth. These can’t be placed before July 1 and have to be removed by October 15. The barriers need to be weighted down because as the plants underneath the barriers die and decay, they generate gasses that create air pockets in the barriers. Solid benthic barriers require weekly inspections and burping of the air pockets, while the mesh type require less maintenance.
• Diver Assisted Suction Harvesting (DASH) is a method in which a diver pulls out the AIS, including its roots, and feeds them into a suction device that brings it to the surface where it is bagged for proper disposal away from the water.
• Herbicides and pesticides are chemicals used to help eradicate AIS. There is a lot of control and oversight to ensure proper application as well as ensuring no effect on the ecosystem.
• Hydro raking is usually the last resort. Barge-type watercraft cuts the milfoil below the surface and pulls it out of the lake on conveyor belts and transports it to shore for disposal. Floating barriers encompass the area being harvested in an effort to contain floating fragments.

To learn more about AIS and what you can do to help fight the problem, go to the Vermont Department of Environmental Conservation website for more details and training.