Dear Fellow Lake Residents,

I wanted to bring all of you up to date on activities at our lakes last year. Lost Lake/Knops Pond succeeded in receiving two grants from the Community Preservation Committee for treatment of the non-native invasive weeds and a second grant to study the areas within the watershed (the total area that drains into the lake) that contribute to the inflow of phosphorus, nitrogen and total solids caused by stormwater run-off and erosion. These efforts were also supported financially by the Groton Lakes Association and the Great Ponds Advisory Committee.

First of all, the treatment last year was difficult because of the continual heavy rains that followed each treatment. This tended to dilute the herbicide and slow the decline of the invasive weeds. In addition, curly leaf pondweed (Fig 1) which begins growing early, made a mess as it began to die-off. SOLitude, our applicator, thinks the diluted herbicide hit this weed when it had already matured making it less effective. We added Diquat to the next treatment which we normally use in the spring for this weed. It was very effective and the curly leaf died. The spread of curly leaf probably began after our last whole lake treatment in 2013. The removal of Cabomba from the water column presented the opportunity for this weed to spread. You can see the extent in the pretreatment map below.

Figure 2: Pretreatment Map, April 2021

Some of you noticed clumps with lily plant roots being ripped up and floating around as small “islands.” This, unfortunately, is one of the side effects of treatment. These should eventually sink to the bottom. The lilies and other native weeds will recover during the next season. I photographed one of the largest “floating islands” last fall that had become stranded at Sargisson Beach. It will have to be broken up next spring during clean-up. Here is the photo in Figure 3.

A third booster was applied in September to knock-out any remaining weeds. The post-treatment map shows how well the treatments cleaned up the lake. There were a few remnants of Cabomba (fanwort) near the Martins Pond Brook inlet. The water flowed in all season as if someone left a faucet on full! This, the result of continued rainstorms this summer. As the treatment came in under budget, members of GPAC appeared before the Community Preservation Committee to make a plea to use the unexpended funds to treat these weeds in Spring of 2022. They voted unanimously to support this plan. We cannot thank the CPC enough for their help in making these programs successful.

Figure 4: Post Treatment Map, September 2021

The second study, conducted by Geosyntec, was completed just before the year ended. This report is a blueprint for future actions to reduce the phosphorus loading in the lake that contributes to explosive weed growth. Much of the work needs to be accomplished close to the lake shore where stormwater flow and erosion wash these minerals into the lakes.This study makes the lake community eligible for federal grants to begin to apply best management practices to curb these pollution sources. The consultant produced a “hotspot” map to show the areas of greatest concern (see below). The report itself is available here…

The lake will not take care of itself. The weeds will come back and treatments will be needed, and long term we need to reduce the stormwater run-off and erosion. We now have those tools and a blueprint to carry it out. There are a number of new residents on the lake. We are all here to enjoy the water, but without volunteers to take on these projects, the lake’s condition will deteriorate. The Groton Lakes Association and the Great Ponds Advisory committee are two ways to become involved with the future health of the lakes. Many people have stepped forward in the past, but we need new residents to become committed and involved.

The harvesting of weeds in Baddacook Pond this year has continued to make a difference. The Town and the Groton Water Department have allocated funds to make this program sustainable.

The residents of Duck Pond were successful in receiving another grant from the CPC to continue its experimental aeration program. The condition of the pond is good as dissolved oxygen levels are high. The reduction of bottom muck has not decreased. SOLitude, the contractor, will continue to monitor and check on progress.

Finally, the Great Ponds Advisory Committee, funded an updated study of Whitney Pond and noted the increased invasion of non-native weeds as well as the significant proliferation of Purple Loosestrife enveloping private property in the area where Lost Lake empties into the pond. The search for a way to safely launch the weed harvester to help contain the invasive weeds continues.

I hope the coming season will be an enjoyable for all, but please seriously consider becoming involved in preserving and protecting our beautiful lakes.

Respectfully submitted,
Alex Woodle, Member
Groton Lakes Association
Great Ponds Advisory Committee