Experts: Green ponds no cause for alarm
WILTON — Some of the ponds in the area are looking particularly green right now, but it is likely nothing to be concerned about.
Some of the places where what looks like a green slime is being seen are the pond at Cherry Lane Park, Horsehoe Pond and along the edges of Kent Pond in Wilton.
According to Chris Bellucci, monitoring program supervisor at the state’s Bureau of Water Protection and Land Reuse, what is growing along the edges of Kent Pond is an aquatic plant called duckweed. Without seeing photos, he said it is hard to say what is in the pond at Cherry Lane Park or Horseshoe Pond, but it is likely duckweed or algae, which looks like floating mats of vegetation. Algae is common, particularly on smaller ponds, at this time of year, he said.
When it’s “not fibrous, more like a soup consistency,” he said, it’s likely a cyanobacteria bloom.
The bacteria is also known as bluegreen algae, which occur naturally in lakes and ponds throughout Connecticut, according to the state website. The organisms that make up the algae are generally harmless, but “when nutrient loading exceeds certain levels, a water body can experience nuisance bluegreen algae blooms that may produce and release toxins,” the site said. These toxins can be harmful to people and animals.
Here, most algae blooms occur from midsummer to early fall. During a bloom surface water:
⏩ May be cloudy or even thick like pea soup.
⏩ May look like someone spilled paint on the water.
⏩ Will likely be green or brown. There may be a mat of algae, scum or foaming on the water surface.
A change in the weather will change the water conditions.
“Just like plants on land, plants in the water need nutrients and sun,” Bellucci said. “As the temperature rises, it is more conducive to growing. As fall comes, there will be less sunlight, the temperature goes down and there are fewer nutrients.”
He also noted that a yellowish hue on water during the spring is likely pollen that has fallen from trees.