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Lake Management Plans (Eagle Lake) Page
The following is a very brief excerpt of the dozen plus management practices described in the DRAFT Supplemental Environmental Impact Statement (SEIS) prepared by the environmental consulting firm ENSR in 2000. The report was prepared at the request of DEC Jim Sutherland in anticipation of Eagle Lake being used as a demonstration/test site for the use of Sonar as a whole lake treatment within the Adirondack Park. These informational snippets are a brief synopsis of the more viable milfoil control methodologies for Eagle Lake. Additional information has been added where applicable updates have been required since the report was issued, as well as new information as it has come along.
 The full report 2000-January DRAFT Supplement Environmental Impact Study (SEIS): A comprehensive management assessment comparing methods for the control of eurasian water milfoil in Eagle Lake with Flouridone (Sonar). Prepared for the NYS DEC by ENSR (11mb).
  • Lake Management Planning Guides Page- General guides to forming a lake management plan as well as management alternatives on other lakes.
  • Plant Surveys (Eagle Lake) Page- Surveys of Eagle Lake that studied either individually or in combination the location and distribution of native vegetation or the locations and distributions of the invasive Eurasian Water Milfoil.
 
They are described as:

No Action- this method entails doing nothing to stop the spread of milfoil within Eagle Lake, allowing it to spread throughout the lake usually achieving a high density within the lake in 10 years. "The no action alternative is not a sound strategy for Eagle Lake ... The native plant assemblage provides far more habitat value than could any stage of milfoil growth..."(ENSR p20)
 
Physical Methodologies-

Benthic Barriers- Mats made using varying formats are laid out over the lake bottom to cover patches of milfoil, with weights holding them in place. The mats block the sunlight from reaching the plants underneath the mat causing them to die from a lack of photosynthesis, this also keeps plants from taking root where the mat is in place limiting the spread of milfoil. This is a non-selective method of weed control, and is not intended for use in large areas.

Sediment Addition- this involves adding additional sediment to the lake bottom (or moving it from one location to anther) with the intent of making the bottom less hospitable for plant growth or to bury the plant.  This method can be extremely disruptive to the environment, and is non-selective.

Dredging and Excavation- this involves the large scale removal of sediment from the bottom of the lake to remove the offending plants.  This method can be extremely disruptive to the environment, and is non-selective.

Hand Harvesting- This is a highly selective method that involves hand removal of individual plants. This is labor intensive and highly effective method of removing plant biomass. It is not useful in large patches.

Mechanical Harvesting- this form of control involving hydro-raking, roto-tilling or other mechanical removal methodology disturbs the surrounding bottom sediment and leaves the milfoil fragments free to propagate around the lake.

Suction Harvesting- this variation of mechanical harvesting utilizes surface mounted water pumps (usually on a floating platform) to move aquatic plants into a collection hopper where they can drain. This has the advantage over mechanical harvesting of being readily usable by a team of underwater divers, and unlike dredging, suction harvesting minimizes the amount of sediment disturbance, as divers control where the end of the suction line is placed suction line is placed.

Water Level Control- this involves draw downs of the lake to disrupt the growth of plants at varying water depths. Non selective and can be highly disruptive to native plant species.

 

Herbicides- this is a relatively selective method that kills plants or limits their growth. Requires contact with the plant material and may decrease dissolved oxygen while plant matter decays.

  • For more information on aquatic herbicides please see the Washington State Department of Ecology web site here.
  • For an innovative idea on the application of aquatic herbicides to minimize product drift please visit here.
 

Biological Controls- this method involves the introduction of herbivorous fish or insects that feed on plant matter, or damage plants preventing additional growth. May be selective or non-selective, and provides “control with limited growth.” Care should be exercised when using some herbivorous fish as they have been deemed invasives or nuisances by the Illinois DEC; for more information see this USA Today article.

  • Triploid Grass Carp- Triploid grass carp are plant-eating fish from the Amur River Basin and lowland rivers in China and Russia. Grass carp are generally not recommended for milfoil control because milfoil is not a highly preferred food. As a result, the concern is that they can enhance milfoil growth by removing competition from native plants and opening up more area for milfoil to colonize. In Washington state, grass carp can be used for milfoil eradication/control only in water bodies where the eradication of ALL submersed aquatic plants can be tolerated.
  • Brant Lake Milfoil Control- Internet Research on the Milfoil Weevil, David King (Personal Opinion)