The three ponds of Congamond Lake will be treated for nuisance aquatic vegetation June 10. (WNG File Photo)
SOUTHWICK – Treatment of portions of North, Middle and South ponds June 10 means residents must take precautions.
The annual treatment controls the growth of nuisance aquatic vegetation on the three ponds that comprise Congamond Lake.
Lake Management Committee member Richard Grannels said the treatment aims to kill Eurasian water milfoil and curly leaf pond weed specifically.
“It’s a targeted herbicide,” he said, “but the reason you don’t want to use irrigation is it can attack some ornamentals.”
Residents should not use lake water for drinking and cooking from June 10-14. Swimming is restricted through June 11, watering livestock is not allowed from June 10-12, and residents should not use the water for irrigation until June 16.
There are no restrictions on boating and fishing.
Grannels said fish typically do not swim in the shallow waters where the herbicide is used so it’s not a concern. He added that the herbicide dissipates in a matter of days.
The treatment process is very hands-on. The team from the company has a GPS map of the ponds and goes out in a flat-bottom boat. When they come across an area with the invasive species, they pull up a sample and if it is Eurasian water milfoil or curly leaf pond weed, they treat the area.
Grannels said the invasives on Congamond Lake have drastically decreased.
“About 20 years ago they did a whole lake treatment using sonar,” Grannels said, adding all three ponds were infested with the invasive milfoil. “All 420 acres of water were treated and now we are down to about 15-20 acres that we treat every year.”
Grannels said the annual treatment is maintenance to prevent the situation from two decades ago from happening again.
“The Eurasian water milfoil expands quickly,” he said. “This contributes to algae blooms and it’s a vicious cycle.”
The danger, he said, is that the invasives bring phosphorus to the water.
“Phosphorus is the bad stuff,” Grannels said. “In Massachusetts and Connecticut it’s banned in fertilizers, unless it’s to start a lawn.
For more information on the treatment, contact Solitude Lake Management out of Shrewsbury.
