Residents hear proposal about Rogers Lake weeds
Old Lyme — About 75 residents heard a presentation Monday on a proposal to use a contact herbicide to control weeds within Rogers Lake, the 260-acre lake between Lyme and Old Lyme.
A study, by New England Environmental Inc. of Amherst, Mass., recommends the application of the herbicide Flumioxazin to 43 acres of the lake, about 17 percent of the lake's total size, to combat the non-native species of variable-leaf milfoil and fanwort, according to the presentation.
The study, commissioned by a committee formed by the Old Lyme and Lyme selectmen along with representatives of the Rogers Lake Authority, further recommends hydro-raking of water lilies. The study included a plant survey, development of water quality monitoring, domestic well impact evaluation, and impacts on wildlife and human health.
On Monday, Mark June-Wells, a limnologist who conducted the plant study, said Rogers Lake was a "very diverse lake" with 27 total species, making it within the top 10 percent of lakes in Connecticut in terms of plant diversity. Plant diversity is "generally considered a metric for a healthy ecosystem," he said.
But he said the two non-native species — fanwort and variable leaf milfoil — are inhibiting boating and recreational uses of the lake. He said 30.5 acres of the lake's 94-acre "littoral zone," in which plants grow, contain the two non-native species.
Scott Fisher of New England Environmental presented the options investigated in the report and the pros and cons of mechanical, biological - such as placing grass carp or milfoil weevils in the lake - and chemical options.
He said mechanical options, such as hand-pulling and harvesting, can often break up the weeds. This can make the weeds "spread heavily" throughout the lake. He said harvesting was previously used at Rogers Lake, but was deemed unsuccessful for the cost, likely due to the fragmenting.
Fisher said hydroraking is "very effective" on lilies, but is not effective on non-native species. He said it's fairly expensive, but can be cost effective if used for small areas.
The study also explored chemical options and recommended Flumioxazin, a contact herbicide which can begin degrading within a few hours to a day, costs about $990 per acre, and has no signs of toxicity to humans under the permitted parameters, said Fisher. The herbicide can be moderately toxic to juvenile fish and aquatic invertebrates, he said.
The presentation said state permitting would be required for the use of herbicides in the lake.
In addition, the study included a report by Fuss & O'Neill of Manchester on the proposal's impact on wells. About 300 lots around the lake draw water from wells.
John Hankins, a Fuss & O'Neill consultant, said that groundwater flows from properties toward the lakes. He said it would be possible to draw lake water from a well, but that it would be unlikely unless the well was being pumped all the time.
After the presentation, residents asked questions: including why dredging was not recommended, if the study considered methods to control weeds by drawing down the lake, and if water-quality testing would include shallow wells downstream from the lake.
June-Wells said a draw down of the lake wouldn't touch most non-native components, but would affect certain species within the lake. He also said that dredging was not found to be optimal for the lake and is also costly.
First Selectwoman Bonnie Reemsnyder said the state would determine if well testing would be required under the plan and if that would include downstream wells. She also said the recommendation will first move to the Rogers Lake Authority and then to the Boards of Selectmen of both Lyme and Old Lyme.
The studies are available on the town of Old Lyme's website.
Twitter: @KimberlyDrelich
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