Rogers Lake, the 260-acre body of water between Lyme and Old Lyme surrounded by residences, a state boat launch and a beach area, will not receive an herbicide application to treat invasive weeds this summer.

The non-native weeds of variable-leaf milfoil and fanwort, as well as lily species, live in the lake, particularly prevalent in certain patches.

In 2013, the towns of Lyme and Old Lyme formed a committee to analyze the weeds and then commissioned a study, which ultimately recommended applying the herbicide Flumioxazin to targeted areas of the lake.

The towns had anticipated potentially using the herbicide as early as this July.

But it was discovered during the process of preparing an application for a state permit that three species of concern to the state — banded sunfish, bridle shiner and eastern pondmussel — may live in the lake, Old Lyme First Selectwoman Bonnie Reemsnyder told the Rogers Lake Authority on Wednesday.

This is part of the regulatory process, but will add time and cost to the project, she said.

Reports of these species were found on the Natural Diversity Data Base, which means that these species possibly, but not definitively, live in the lake, Reemsnyder said. 

The towns will conduct a survey of targeted areas within the lake in the next few months to determine if the species are present there, Reemsnyder said.

The survey will cost about $8,000, and there are enough funds budgeted by both towns for the project to cover the expense. 

Depending on the results, the towns could then apply for a permit this spring to apply the herbicide to the lake in June 2016, she said.

But if, for example, a large colony of the eastern pondmussel lives in a targeted area, the first selectmen of the two towns have discussed that it could be too costly to move them —potentially putting the brakes on the project.

Town officials will make a decision after receiving the results of the survey.

"If the colony is of significant size, it is probably not practical to relocate them, which was explained to us as an option," Lyme First Selectman Ralph Eno said in a phone interview. 

It will depend on the size of the colony and what the state will allow for weed treatment.

But if the towns get the go-ahead, treating the lake early in the season next year will yield better results than an application in July, he explained.

The study by New England Environmental of Massachusetts, presented to the public in the spring, had recommended applying the herbicide to specific areas in the lake, as well as hydroraking areas to control lilies.

The study said the herbicide "is cost efficient, low in human health toxicity, effective and highly regulated" by DEEP and the state Department of Public Health.

The study also said that some of the previous mechanical methods used on Rogers Lake, such as harvesting, could cause the weeds to break apart and spread even more.

The consulting firm also recently completed a long-term lake management plan for the Rogers Lake Authority, which was posted on the town of Old Lyme's website this week.

The plan recommends applying Flumioxazin on 31 acres in June 2016, as well as collecting data from water and soil monitoring.

It also recommends reaching out to residents through a newsletter about the treatment dates and best-management practices.

Meanwhile, the Rogers Lake Authority said Wednesday that it will note in the meeting minutes that residents should take care when swimming or boating, due to the growth of weeds.

Some residents say the weeds seem to worsen each year.

Lyme resident Toni Phillips said the cove where she lives is becoming seemingly enveloped with lilies and invasive weeds.

"Either we do something other than what we've done, or we sit by and watch as the lake shrinks in size, becomes hard to utilize for swimming and boating, and becomes like a swampy field — and property values decrease," she said.

Old Lyme resident Joanne Centola said she finds the overgrowth of weeds has made it difficult to take boats out on the lake. She said she is concerned about a potentially dangerous situation arising, if for example, a rower became stuck and tangled in them. 

"Something has to be done before we lose the lake," Old Lyme resident Roger Breunig said.

But some say the towns will now have more time to consider other options.

"We've encouraged going slow on this," said Tom Sherer, the chairman of Old Lyme's Conservation Commission.

The commission, which has discouraged the use of pesticides on fields and lawns whenever possible, particularly since the community uses wells and septic systems, is in favor of looking at alternatives to herbicide treatment on the lake, he said.

The commission is planning to roll out a plan with about a dozen alternatives, which together could help control and manage the weeds, he said.

The alternatives include silt ponds for incoming streams to diminish silting in the lake and more frequent septic-system pump-outs.

Sherer said drawdowns or dredging should be investigated as long-term solutions. He said that while those options potentially are costly, the treatment with herbicide is temporary and would need to be repeated. 

He said he would like to see a cost analysis comparing the methods over a 20-year period.

k.drelich@theday.com

Twitter: @KimberlyDrelich