Milfoil Management


 For over a decade Lake Iroquois Association(LIA) has been working to improve the water quality of Lake Iroquois. For the past two years LIA has been researching control options to combat Eurasian Water Milfoil(EWM) which was first detected in 1990 near the fishing access. According to the aquatic plant survey of the lake sponsored by the LIA and conducted by Northeast Aquatic Research in 2014, milfoil covers 70 acres of the lake whose total surface area is 244 acres. The milfoil has formed dense surface mats, changing the natural lake environment, out-competing and eliminating the more beneficial native aquatic plants, and severely reducing natural plant diversity within the lake.  In 1984, 45 native aquatic plant species were documented in the lake but by 2014 only 33 native species could be found (a 27% decline). In addition to choking out native plant species, dense milfoil weed beds are poor spawning areas for fish thus reducing native fish populations. In the northern portions of the lake dense surface mats of milfoil are making fishing, boating and swimming virtually impossible.

 Once an invasive like milfoil is established in a water body, it is nearly impossible to completely eradicate.  However, it can be reduced and controlled to a level so that it will cease to interfere with recreational uses of the lake and it will allow a resurgence of native species and an improvement in the overall health and water quality of the lake. The fight against milfoil is a long-term project which will require investment of time and money for years to come.  Not only do we need to reduce what is growing in the lake now but we also must continue to be vigilant in preventing invasives from being carried into the lake  and to continue efforts to reduce the nutrients flowing into the lake that feed the milfoil.

 There are only a few truly effective options for reducing and managing such a milfoil infestation. These include diver-assisted suction harvesting (DASH) and the use of one of two Vermont state approved herbicides: Triclopyr (brand name: Renovate) or Fluridone (brand name Sonar). We estimate that a whole lake treatment with herbicides would cost nearly $100,000 while removing milfoil with suction harvesting alone will likely cost 10 times that amount.  We have requested and received funding from the surrounding towns and grants from the Vermont DEC but we need the help and support of all who live on the lake, use the lake, and care about this very special and unique resource.  While the cost to fight the milfoil is great, the cost of doing nothing is greater.


 LIA Facebook page:

 VT Dept. of Environmental Conservation:

 Background on Eurasian Watermilfoil:

Fluridone Information:            options/herbicides/fluridone/fluridone-faq

Triclopyr Information:

 Diver-Assisted Suction Harvesting:

 Other Vermont Lakes:

 Lake Dunmore:

 Lake Morey:


Aquatic Plant Survey

In the summer of 2014 the LIA hired Northeast Aquatic Research to perform an Aquatic Plant Survey of the lake to measure the overall plant species diversity in the lake as well as to determine an accurate, up to date, estimate of the coverage of Eurasian Milfoil in the lake. The results were published in a report to us on February 11, 2015. Read More and Download the Report Today...