Eurasian Milfoil

Eurasian Milfoil Spread as of 2021

Eurasian Milfoil remains our single largest environmental concern by far.  It’s a challenge in many respects, but ultimately Milfoil critically impacts the usefulness of the lake for swimming, boating and general enjoyment.  It is now one of the most widely distributed invasive aquatic plants on the continent. Because tiny plant pieces can develop into new plants, Eurasian water-milfoil is easily spread when water currents, boat propellers, trailers, or fishing gear carry plant fragments to new areas. The Association works with ABV des 7 to survey the lake, and in 2011 Milfoil covered 185,000 M2 of the lake, in 2015 it was 525,000 M2, and in 2021 it covered over 1,100,000 M2 of the lake!!  It now covers nearly all parts of our lake between .5m and 7 m deep, 57 hectares or 12% of the lake. While our lake is 900 hectares, it’s almost a complete saturation of the shoreline and shallows <4M deep where it grows.  Nothing is slowing it down, and the trajectory is full saturation in the next few years, joining nearby Lac Gauvreau and others that are already done in. 

A Word on Eurasian Milfoil vs. Northern Water Milfoil (native)

Some cottagers have commented that this is nothing new, but they are mistaking native milfoil with Eurasian milfoil! Northern Water Milfoil has been native to our lake for as long as anyone remembers. And it does come and go. However, Eurasian Milfoil is not native milfoil. The Eurasian strain is new to our lake, is much more aggressive, and will choke the life out of a lake because it stays. There is even research showing the two strains are in fact hybridizing to form and even more aggressive strain!

Distinguishing between the two can be challenging, as they share some similarities in appearance. But there are visual differences. If you are in doubt, contact us and/or other local experts or authorities. Here are some general visual differences:

  1. Leaf Arrangement:
    • Northern Water Milfoil: Leaves are typically arranged in whorls of four to six around the stem.
    • Eurasian Milfoil: The whorls are usually three, rarely four, around the stem.
  2. Leaf Characteristics:
    • Northern Water Milfoil: The leaflets are often broader and have more irregularly serrated edges.
    • Eurasian Milfoil: The leaflets are usually finer, feather-like, with a more serrated appearance.
  3. Leaflet Density:
    • Northern Water Milfoil: The density of leaflets along the stem tends to be lower.
    • Eurasian Milfoil: Often appears denser, with more closely spaced leaflets along the stem.
  4. Stem Color:
    • Northern Water Milfoil: The stem is typically red to brown.
    • Eurasian Milfoil: The stem can be reddish-brown to green.
  5. Flower Spikes:
    • Northern Water Milfoil: The flower spikes are often shorter and more compact.
    • Eurasian Milfoil: The flower spikes can be longer and more robust.
The visual below may be helpful in comparing the two types.
Native Milfoil on the Left and Eurasian on the Right
What can be done about Eurasian Milfoil?
  1. Barrier Systems: Physical barriers, such as burlap are installed to lay on the bottom of the lake. These barriers block sunlight and prevent the plant from establishing itself, and will kill off what is already there. The burlap eventually rots though, so this approach only slows down the spread, it dos not remove the milfoil from the lake. It also takes a lot of burlap to cover infested areas, and its a very labor intensive process.
  2. Mechanical Harvesting: This involves physically removing the milfoil from the water by pulling it by the root. (NOT CUTTING IT!) which requires divers. Some specialized equipment is being developed though.
  3. Biological Control: Introducing natural predators or herbivores that feed on Eurasian Milfoil is being trialed in various regions, but not yet in Canada or Quebec. Specific insects or fish that consume milfoil are being introduced to control its growth and in some cases, eradicate it. Once thoroughly tested though, this can be an environmentally friendly approach and so we are monitoring how those trials are proceeding. That said, the would need several levels of approval for use in Canada.
  4. Herbicide Treatment: Chemical herbicides can be used to control Eurasian Milfoil. However, this approach requires careful consideration of potential environmental impacts and is currently not legal in Canada, although we understand this may change.
What’s Important for All of us to Do!
  1. Respect the Milfoil Buoys! It’s perhaps the single most important thing you can do to help the Milfoil situation. The Association has marked off numerous Milfoil beds on the lake with Marker buoys. You can learn more about them here. So please, control Control your Boating and do not boat in marked areas!
  2. Education and Outreach: Raising awareness among our recreational boaters on the lake is crucial. Educating people about the importance of preventing the spread of Milfoil, and any invasive species, including the proper cleaning of boats and equipment, and avoiding areas with milfoil so propeller blades don’t cut. It is well known that Milfoil gets into lakes from boats and trailers, but rapidly spreads when propellers cut it up! So avoid marked areas!
  3. Monitoring and Early Detection: Regular monitoring of lakes for the presence of Eurasian Milfoil is important. Early detection allows for prompt action to prevent the plant from establishing itself and spreading further.
  4. Government and Research Support: The Association, together with other Lake Associations in La Peche are working together to increase the level of awareness in Quebec and Canada regarding the threat of Milfoil to our cottages. Getting their support and funding dollars to help combat Milfoil is key, and any assistance you can offer is welcomed. Being aware of current research and trials is also very helpful, so if you discover something, please pass it along to us

Actions taken by the Association thus far:

  • We are constantly exploring different methods to combat Milfoil as well as funding sources we can access to pay for it.
  • We first raised the issue of the invasive weed issue at the La Pêche Municipal council in May 2015 and hired ABV des 7 to conduct a lake-wide study o determine the extent of the issue and how best to address it. They provided our association with a report on their findings in January 2016. We did the same survey again 2021.
  • Our approach to control milfoil has been to use Burlap as a means to mitigate the growth and spread of the invasive species. Following the advice of the MRC and ABV des 7, Burlap appears to be the only sanctioned mitigation we can use today. The Province also allows private owners to lay down up to 75 square meters of burlap along their waterfront without needing to get a permit. One key thing we’ve learned is that laying burlap should only happen from mid-August onwards, so that we don’t interfere with fish spawning areas.
  • For other areas of the lake, we have a Certificate of Authorization (CA) that was submitted to the Ministry of Environment (MDDELCC) to give us permission to install burlap over selected milfoil beds.
  • The CA requires we use locally found rocks or cement blocks that could be removed after several years. This is to ensure we don’t introduce any other species into the lake. The laying of burlap is very labor intensive when done using the simple techniques we have available to us. A lot of effort goes into covering just a few square meters, so we are focusing on milfoil beds in front of Boat Slips and other high traffic areas. IN the future, we hope to make use of a mechanical barge that is significantly easier to use, and will scale our coverage ability.
  • Today we have piloted several areas, and have learned quite a few lessons. We’ll know in a year or two if our efforts are paying off.
  • We have deployed yellow marker buoys to help steer boats away from dense weed mats areas. We would like to extend the use of these yellow buoys to mark off other areas that should be avoided.
  • The pilot project, funded with the municipal grant and raised funds, was to cover approximately 10,000 square meters. Please note that that the Eurasian milfoil is currently estimated as covering 570,000 square meters. It is obvious that this will be a five to 10-year endeavor to control the milfoil.
  • Map of the lake with Eurasian Milfoil beds (as of 2016) outlined in red
     You may download a .pdf copy of the lake map here. (5MB)

Delimitation of Eurasian watermilfoil beds November 2021 (pdf, 1.4 mb)