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Eurasian Milfoil Control: What Works for Michigan Waterfronts

Quick Answer

Eurasian watermilfoil (EWM) in Michigan is primarily controlled using a combination of permitted aquatic herbicides, careful hand or diver removal, and prevention at boat launches. No single method provides a permanent solution, requiring a long-term management program tailored to the specific waterbody and adherence to Michigan's EGLE permitting requirements. EWM is a widespread invasive species, reported in 65 of Michigan's 83 counties, and is identifiable by its feather-like leaves with 12 or more pairs of leaflets per leaf. Cutting or raking EWM in an active infestation can worsen the problem by spreading fragments, and grass carp are not recommended as they prefer native plants.

Eurasian watermilfoil (EWM) is controlled in Michigan with a mix of permitted aquatic herbicides, careful hand or diver removal, and prevention at the boat launch. No single method wipes it out for good. If you have a dense mat in front of your dock, the realistic goal is to keep it below nuisance levels year after year, using methods that match your waterbody and your permit.

This guide walks through how to confirm what you have, which control options exist, what Michigan law requires, and the mistakes that make milfoil worse.

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What are the key takeaways for controlling Eurasian milfoil?

Table of Contents

How to tell Eurasian watermilfoil from native milfoil

EWM is a submerged plant with feather-like leaves arranged in whorls around the stem. The usual field clue is leaflet count: Eurasian watermilfoil has 12 or more pairs of leaflets per leaf, while native northern milfoil has fewer. Stems tend to branch heavily near the surface and form a dense canopy.

That canopy is the problem. EWM grows rapidly and forms a thick surface mat that interferes with swimming, boating and fishing, and it crowds out native plants. It is also widespread: the State of Michigan’s strategy document notes reports of EWM in 65 of Michigan’s 83 counties, and it was first recognized in state waters in 1970.

Before you pay for any treatment, get the plant identified. A pond or lake manager can take a sample and confirm the species. Native milfoil is a useful part of the lake. EWM is a prohibited species in Michigan.

How to tell Eurasian watermilfoil from native milfoil — overview diagram

Your control options, compared

There are four families of control: chemical, physical removal, biological and prevention. Each fits a different situation.

Method Best for Main limits
Systemic herbicides (2,4-D, triclopyr, combinations, ProcellaCOR) Established beds, larger areas Permit required; must be tailored to the waterbody
Contact herbicides (such as endothall products) Smaller spot areas, quick knockdown Michigan limits some to once per year before June 15
Diver-assisted suction harvesting (DASH) or hand pulling Small or scattered patches, sensitive areas Must remove the root base; labor intensive
Cutting or harvesting Opening a boat lane in a mature, non-spreading bed Can create fragments and spread the plant
Grass carp Not recommended for EWM Prefer native plants
Prevention (boat cleaning, inspection) Every waterbody Does not remove existing plants

Herbicide treatment

For most established beds in Michigan lakes and ponds, herbicide is the workhorse. EGLE publishes a table of approved products, and it lists systemic herbicides including 2,4-D, triclopyr and their combinations, plus ProcellaCOR, for Eurasian watermilfoil. The same table shows that contact products such as Aquathol K are restricted to one application per calendar year before June 15, while the systemic options carry no such calendar limit.

The Texas A&M AquaPlant guide also rates several active ingredients, including endothall and fluridone, as effective on EWM. Which one is right depends on water exchange, treatment area size, nearby native plants, and the permit conditions. That is a decision for a licensed applicator, not a label you read in a store.

Two cautions apply here. First, always follow the product label and permit conditions, and use only herbicides approved for aquatic use by the U.S. EPA. Second, heavier is not better. A Michigan State University technical report on treated lakes found that Sonar treatments eliminated nearly all milfoil and other plants for about a year, and the lost fish cover was only partly replaced by plants such as Chara or Vallisneria. Fish need plants for shelter and food. Clearing everything can leave a lake with weaker fish populations.

Hand removal and DASH

For small patches, pulling the plant by hand can work, but only if you get the root crown. Cutting the stems leaves the plant to regrow. A Michigan Sea Grant interview with a volunteer who helped run a DASH program on Higgins Lake makes the same point: divers must remove the plant at the root base, and a proper program needs specialized equipment and permit management.

Diver removing milfoil at its root base

The same source stresses persistence. Successful lake programs rely on regular surveying and dedicated diver crews over many years, not on the expectation of eradication.

If you wade in to pull milfoil yourself, bag every piece and take it out of the water. Do not toss it back near the shoreline.

Cutting, raking and harvesting

It is tempting to rake or cut milfoil in front of your dock. The trouble is that mechanical cutting or harvesting can create fragments that drift to new areas and take root. In a lake where the infestation is still spreading, professionals often advise against it. Harvesting has a place in some mature, widespread infestations, where the goal is only to open channels, but it is a lake-level decision, not a lot-level one.

Why grass carp are the wrong answer

People often ask whether grass carp will eat milfoil. In practice they are nonselective feeders that prefer native plants and turn to milfoil only after those are gone. You can end up with a lake stripped of native vegetation and milfoil still standing. Another extension guide states that there are no known biological controls for EWM.

Is winter drawdown an effective method for Eurasian milfoil control?

Winter drawdown, where a lake is lowered to dry out and freeze the plants, is listed among the options in a Mississippi State publication on EWM. It only applies to lakes with controllable outlets, and it affects everything else in the lake, so it is a community decision and not a homeowner project.

What Michigan law requires before you treat

If your plan involves any chemical, the permit comes first. EGLE’s Aquatic Nuisance Control program says that permits are required to chemically control nuisance aquatic plants and algae, and each application is reviewed for environmental and human health impact. EGLE also publishes a FAQ on aquatic nuisance control that explains what the program covers.

Practical points for riparian owners:

  1. Check whether your lake has a lake association or special assessment district. Many Michigan lakes run a shared treatment program, and a lone treatment can conflict with it.
  2. Treatment maps are specific. The permit and its approved treatment map set the conditions for each treatment, so the area and the chemical are not up to the applicator on the day.
  3. Ponds are not exempt just because they are private. If the water connects to waters of the state, rules can apply. Ask before you buy product.
  4. Keep records. Treatment dates, products and areas matter for the next season’s plan.

Because rules and approved product lists change, check the EGLE pages above for the current version before you act.

Prevention: the cheapest control there is

Boats move milfoil from lake to lake. The USGS fact sheet’s guidance is simple: remove all visible plant fragments from propellers, trailers and equipment and let everything dry completely before launching somewhere else. Do it at the ramp, every time, including for guests who bring their own watercraft and kayaks.

If you manage a small private pond, the same logic applies to anything that goes in the water: pumps, nets, even plants bought from a garden center. Do not add aquatic plants unless you know exactly what they are.

Planning a long-term program

Milfoil is rarely finished business. A lake manager quoted by Michigan Sea Grant describes the work as a permanent, ongoing effort with regular surveys and multi-year funding. A good annual plan usually includes:

  • Spring survey. Look for early growth and map it before beds thicken.
  • Targeted treatment. Spot-treat or treat the mapped beds under your permit, rather than the whole shoreline.
  • Follow-up check. Return a few weeks later to see what survived.
  • Native plant protection. Leave desirable plants where you can. They compete with milfoil and keep fish habitat intact.
  • Fall review. Note what worked and adjust next year’s plan.

If you also maintain landscaped beds along the water’s edge, keep upland weed control separate from what happens in the water. For the garden side, this guide on organic weed control for home gardeners covers approaches that avoid putting herbicide anywhere near runoff.

Our perspective: milfoil is a relationship, not a one-time job

We are a family-owned company that has worked on Michigan ponds and lakefronts for more than 30 years. The most common mistake we see is a homeowner who treats milfoil as a single event. They clear a patch, feel relief, and are surprised when it is back the next summer.

We would rather set expectations honestly: you are managing the plant, not erasing it. That means identifying it correctly, treating only what needs treating, keeping native plants and fish habitat in mind, and handling the permit properly. It also means teaching our clients what to watch for between visits, because the earlier you spot a new bed, the smaller the response needs to be.

We also tell clients not to start with a rake or a boat propeller. It feels productive and it often seeds the next patch. A short conversation and a site visit is cheaper than a lake full of fragments.

— Jim

How we help with milfoil and other invasive weeds

Water Landscapes provides pond management for homeowners, HOAs and commercial properties in southeastern Michigan, including weed control treatment, permitting assistance and custom maintenance plans. For emergent invaders like cattails and phragmites, we offer systemic herbicide treatments, cutting and year-round weed control. After a treatment season, our waterfront cleanup service handles raking, trimming, weed and algae removal, and debris.

If you are not sure whether what you see is Eurasian watermilfoil, request a free quote and describe the plant and waterbody. We will tell you what we would check first. We serve communities including Waterford, Clarkston, Lake Orion, Brighton, Novi, Ann Arbor, South Lyon, Livonia, Plymouth and Canton.

Common questions about milfoil control

Is Eurasian milfoil really invasive in Michigan?

Yes. It is not native to the Great Lakes region and is listed as a prohibited species in Michigan. It displaces native plants and can interfere with recreation on the lakes it invades.

Can I pull Eurasian milfoil by hand?

For a small, new patch, yes, if you remove the whole plant with its root base and bag every fragment. Cutting stems alone leads to regrowth. For larger beds, hand removal is slow, and a licensed professional will usually recommend a permitted treatment or a diver-based program.

Will grass carp eat milfoil?

Not reliably. They typically consume native plants first and only turn to milfoil when little else is left, which can damage the lake. They are not a recommended milfoil control.

Do I need a permit to treat milfoil in my lake?

If you use herbicide in Michigan waters, you generally need EGLE permit coverage, and the approved chemicals and treatment areas are set by that permit. Contact EGLE’s Aquatic Nuisance Control program or a licensed applicator before buying any product.

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