Managing the Threat from Invasive Plants

Invasive Plants

We are fortunate that Watchic Lake has not experienced invasive plants such as variable leaf milfoil (Myriophyllum heterophyllum) or Eurasian watermilfoil (Myriophyllum spicatum). Yet, we must be diligent in looking for these invasive plants when launching boats, kayaks, canoes, and in general as we use the lake. If an invasive plant is found early, it may be possible to remediate it quickly and cost effectively. Click or touch here to read our Rapid Response Plan.

Infestation will reduce water quality, and thus impact recreational use of the lake and reduce lakefront property values. Eradication of invasive milfoil is difficult and expensive, costing some Maine lakes $30,000 to $40,000 per year. The threat is real, as evidenced by the 2017 mifoil infestation at nearby Long Lake. and the 2018 infestation of Eurasian water milfoil at Cobbosseecontee Lake in Winthrop.

Click or touch to see the latest research from Maine DEP regarding the risk of an invasive infestation at Watchic Lake. Maine DEP Infested Lakes Brochure.

Avoiding Invasive Plant Infestation

First educate yourself using sources such as the Maine Lakes Environmental Association or the Lake Stewards of Maine (new name for Maine Volunteer Lake Monitoring Program – VLMP). Next, make sure to educate visitors and guests to your camp regarding ways they can protect the lake.

Always remove all plants from your canoe, kayak, boat, trailer, oars/paddles, fishing gear and anchor when going in and out of a body of water. Dispose of any plants in the trash – not onto the ground. Let your watercraft dry. More details can be found in State of Maine Courtesy Boat Inspector Handbook.  In summary:

  • Look for hitchhiking plants anywhere on the boat and trailer where they could be caught by rough edges.
  • Clean off any mud, plants (even small fragments), and animals from boats, trailers and equipment.
  • Drain boat, live well, engine and equipment away from water.
  • Dry anything that comes into contact with water. Let the watercraft dry.
  • Never leave waters with live fish, or release plants or animals into a body of water unless they came out of that body of water.

Draining hulls, bailers, live wells, etc is now the law in Maine! Public Law 203 Chapter 190 is effective June 16, 2023.

Watchic Lake Plant Inventory – Summer 2023

2023 Screening Sectors

In August of 2023, a group of 10 WLA board members and volunteers surveyed Watchic Lake for invasive plant species – none were found. This is eighth year in a row that a thorough inventory of lake plants has been completed. As a member of the Lakes Steward of Maine (formerly VLMP) Invasive Plant Patrol program, we are asked to submit an inventory of the native and invasive plants found in the lake.

LSM 2023 Invasive Aquatic Plant Screening Survey, including a map of the areas surveyed.

26 native plants were identified over the past three years. To learn more about the plants in the lake, and where to get additional information, click on Native Maine Plants Found in Watchic Lake Summer 2023.

Metaphyton algal blooms were noted as well. The higher amounts for algae is likely to do the very rainy summer we have had in 2023.  Algae blooms are fueled by extra nutrient entering the lake, most likely from storm run-off or septic tank issues. More good reasons to keep water from running into the lake.

Thanks to Steve and Kim Lajoie, Don and Martha and Donal Drew, Monica Mahoney, Chris Mahoney, Paul and Nancy McNulty, Stephanie Parker, and Owen Smith for making our 2023 inventory day a success!

Manage the threat of invasive wildlife

All lakes in Maine, including Watchic, are at risk of being harmed by the introduction of illegal fish and other species (such as zebra mussels) posing threats to native fish and other wildlife.

Don’t add any non-Watchic fish or aquatic wildlife to Watchic Lake. Not only does non-native fish introduction cause harm to the lake, it’s illegal. Introduction of any fish into any Maine water is a Class E crime, punishable by fines up to $10,000.

The Maine Department of Inland Fisheries and Wildlife provides as an example “Northern Pike, illegally introduced into the Belgrade Chain of Lakes in the 1970’s, are now present in at least 16 lakes in the Kennebec, Androscoggin, and coastal river drainages. … Pike are voracious predators on other fishes, and their presence in one lake is suspected of destroying one of the state’s premier landlocked salmon populations.”

To learn more about illegal stocking visit The Maine Department of Inland Fisheries and Wildlife.

Reporting suspicious plants

Should you find plants that you fear are invasive, its best to contact a Maine VLMP certified Invasive Plant Monitor (for Watchic Lake fill in our Reporting Suspicious Plants Form). Please be prepared with the following information:

  • Take a digital photo of the plant while it’s floating in water (a small white tray is good) and include something to help show scale (a ruler or quarter).
  • Note the location of the plant (ideally mark it with a buoy for further research)
  • Collect a sample. Do NOT remove the whole plant by its roots, as it might cause fragmentation and further spreading. Carefully snip an 8 to 12-inch specimen with as many features as you can (leaves, stem, fruits). Place the specimen in water (a small baggy works well)

More detailed information can be found on VLMP site “Reporting suspicious aquatic species”.

Highest risk plants for Watchic Lake

There are five aquatic invasive plants known to be in Maine lakes. If Watchic Lake were to be infected, it would likely be one of these plants. Below are highlights on these plants with links noted to the Maine VLMP site for more information. Learn more about the Maine VLMP’s “Eleven Most Unwanted Invasive Aquatic Plants“.

Variable water-milfoil is already present in 27 Maine lake systems, including streams. Variable water-milfoil is an extremely well adapted plant, able to thrive in a wide variety of environmental conditions. It grows well in still and flowing waters, and can survive under ice. Variable water-milfoil grows rooted in water depths from 1 to 5 meters on various substrates including organic muck, silt, sand and gravel.

Variable Water Milfoil Plant ME VLMP   Variable Water Milfoil Insitu ME VLMP

Eurasian water-milfoil is an aggressive colonizer, has been found in several Maine water bodies. This is an extremely well adapted plant, able to thrive in a wide variety of environmental conditions. It grows well in still and flowing waters, tolerates mild salinites and can survive under ice. Eurasian water-milfoil grows rooted in water depths from 1 to 10 meters, generally reaching the surface in depths of 3 to 5 meters. Though adapted to a wide variety of substrate types, this species seems to favor fine-textured, inorganic sediments.

Eurasian Water Milfoil Plant ME VLMP

Eurasian Water Milfoil Insitu ME VLMP

Curly-leaf pond weed  has been found in several Maine lakes. Curly-leaf pondweed is located in the submersed plant community. Generally preferring soft sediments, it grows in waters that are shallow or deep, still or flowing. Curly-leaf thrives where many other aquatic plants do not, for example in waters that are shaded, disturbed, polluted or turbid.


Hydrilla is found in the submersed plant community. The adaptability of this plant to a wide variety of environmental conditions has earned hydrilla its reputation as the perfect weed. Hydrilla can grow in a variety of substrates, in waters still or flowing, low or high in nutrients. Remarkably adapted to low light conditions, hydrilla can photosynthesize earlier and later in the day than most plants, grows well in turbid water and, when the water is clear, to depths exceeding 10 meters. Hydrilla typically occurs in dense, rooted stands, but live fragments may also be found drifting in large mats. Hydrilla is considered one of the most problematic of all aquatic invaders.


European naiad is currently known to occur in one Maine waterbody: Legion Pond in Kittery. European naiad is found in the submersed plant community, growing in ponds, lakes, and slow moving streams in depths up to 5 meters. Preferring sand and gravel, the plants thrive in a wide range of substrates.