I would like to explain the use of the herbicide, Reward (Diquat) that has been applied to Highland Lake since 2004. As Water Quality/Environmental Chairperson, I have been very involved with the decision to apply the herbicide Diquat to Highland Lake in an effort to control the spread of the highly invasive aquatic plants, Eurasian and Variable Leaf Milfoil. Much research was done to gain information about the Environmental Protection Agency’s approval of the herbicide, the history and effectiveness of its use.

Diquat (Reward) is a compound chemical that quickly returns to the components that are combined by formula. The actual application of the herbicide is done by trained, licensed professionals who have determined the correct strength needed to wither the milfoil plants without overuse of the chemical. Aquatic Control Technologies, Inc. (ACT) has been hired for the past several years. This company is well respected by the Connecticut Department of Environmental Protection (DEP)and it goes through a strenuous application process for approval to use the herbicide. ACT is required to make a site visit to the lake each June to map the location, density and area-size of the milfoil weedbeds. The biologist, using Global Positioning System technology, identifies the exact location of the weedbeds and takes samples of the weeds to assure proper identification. This information accompanies the application for review and feedback from the DEP Pesticides Division, Fisheries Division, Boating Division and Water Protection and Land Use Division. If there are any questions, such as the existence of Eastern Pond Mussels that were suspected last year, ACT must provide follow-up information before approval is granted. Last spring a professional mussel survey was conducted by a licensed mussel expert, as required by the DEP Wildlife Division, before the application was approved.

We have applied Diquat since 2004 when there were approximately 40 acres of invasive milfoil in Highland Lake. Most of the plants were located at the north rim of the lake near the State Boat Launch and Holland Beach, several coves, and at the south end by Taylor Brook Cove. When the weed survey was conducted in June 2008, there were only 10 acres of milfoil.

While other variables may have contributed to the reduction, such as deep-water-level drawdowns, most of the change in the deeper waters was due to the Diquat.

Diquat has been approved by the EPA for over 30 years and, as used in Highland Lake, is restricted to just the spots where the invasive weeds grow. We do not treat the entire lake, and the herbicide is weighted in order to help it sink into the weeds and not move far outside their perimeter. The lake is closed to boat traffic in order to keep wave action from spreading and diluting the herbicide, which would render it less effective. It is precautionary that swimming is prohibited for 24 hours. You are asked not to use lake water on your landscape for five days since it might contain trace amounts of the herbicide and slightly damage your foliage.

Aquatic Control Technologies, Inc. (ACT) is in the process of applying to the DEP for a permit to treat Highland Lake this spring. ACT will again come to the lake to map where the milfoil is growing and specifically identify it. This has usually been toward the end of June when the milfoil plants are mature enough to identify by species, density and area of coverage. He creates the “weedbed map” that is sent to the DEP; then the DEP completes its review. We hope this process will be complete by the end of June and application of the Diquat will be well in advance of the 4th of July weekend or after it has occurred to keep any inconvenience to a minimum. Thus, you can make your 4th of July plans knowing the lake will not be closed to swimming or boating for one day during that time. We will try to give you as much advance notice as possible via email.

Some of you have called me with concerns that Diquat was not applied to your cove that has many troublesome weeds. The reason it has not been applied is the milfoil (invasive) has been eliminated and the native (noninvasive) weeds are growing more abundantly. Now that the invasive aquatic plants are gone, at least temporarily, the native plants have the sunlight and nutrients to grow . . . and they are growing in large, dense beds. I am exploring methods of “controlling” them. However, the DEP typically will not permit native aquatic plants to be killed; they are habitat for many of our native fish and other aquatic plant and animal life. Please remember our lake is not a swimming pool or bathtub; it is a natural waterbody and has no chlorine! We are fortunate to have such clean, untainted water for recreation of all types!