The use of an herbicide to control invasive weeds in Lost Lake and Knopp's Pond in Groton may have had the unintended effect of damaging an endangered species of plant nearby.
A colony of Sparganium natans, also called the bur-reed, is one of only five known colonies of the plant in the Commonwealth and is upstream from the area that was treated with the herbicide. The plant resembles a thick grass, accented by small clusters of spiked seeds.
On June 14, the herbicide Diaquat was applied to 25 acres of Lost Lake and Knopp's Pond, while the area with the bur-reeds was avoided. The following week, Cindy Kollarics, a volunteer for the New England Wild Flower Society, checked on the colony and found the plants had a ''ghostly" look, with the chlorophyll drained from the leaves.
A couple of days later, Kollarics brought her friend Bill Eger, who has advocated using herbicides to control invasive weeds, to view the damage. Kollarics, who studied aquatic botany and has monitored this colony of plants for more than 15 years, believes Diaquat caused the problem, and she notified the state's Natural Heritage and Endangered Species Program.
Kollarics believes the lake has suffered a loss. ''When taking native plants away, more aggressive, invasive species will settle in, rather than more passive native species," she said. ''We are definitely not getting ahead."
Eger, a retired physician who lives next to the lake, said he can't explain what happened. He also fears that this development will turn public opinion against the use of the herbicide, which the Groton Lakes Association believes the lake desperately needs to survive.
''Something altered the flow that day. There was no [malicious intent]. It may have been an error in judgment or bad luck, but not a violation," said Eger, referring to the order of conditions issued by the Conservation Commission. Among the conditions was that the herbicide be kept away from the bur-reeds.
''This cannot be compared to the developer that rips out flags placed by the Conservation Commission and then clear cuts. I am as distressed as Cindy [Kollarics]," said Eger.
The problem in Lost Lake and Knopp's Pond is milfoil, a nonnative tropical weed. Without an indigenous enemy to control milfoil, it can grow unchecked and destroy the ecosystem, eventually choking the lake and the pond and turning them into swamps.
Eger's views on the subject have changed over time. When the idea of using of an herbicide to control invasive weeds was brought to the public's attention in 2002, he vehemently protested. But given his background, the association asked him to study the safety of the herbicide. The findings surprised him.
''I did research in 2002 and came to the reluctant conclusion that Diaquat was safe to use. Then, somehow I ended up being the spokesperson," he said. In addition to speaking publicly about the treatment, Eger also serves as chairman of the Lost Lake Weed Management Committee, a committee appointed by selectmen in 2002 after the first treatment, when the public's mistrust was still high.
Lost Lake and Knopp's Pond total 206 acres and are no more than 8 feet deep in most places. Diaquat was first applied to 120 acres along the perimeter of Lost Lake and Knopp's Pond in 2002 to kill milfoil. Last month's application was a spot treatment that cost $30,000, which was fully funded by the Groton Lakes Association. In addition, volunteers each year remove between 75 and 150 tons of non-native weeds from Lost Lake and Knopp's Pond.
What happens next remains to be seen. Natural Heritage is reviewing its findings from a site visit made after the organization heard from Kollarics.
There is the possibility of fines if the state determines there has been a violation of the Massachusetts Endangered Species Act.
The Board of Selectmen, which filed the notice of intent for the herbicide application with the Conservation Commission, would be the responsible party if fines are levied by the state. As of Wednesday, board chairwoman Fran Dillon had not heard from the state.