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Recognizing and Monitoring Blue-Green Algae

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Lakes naturally contain many forms of algae that, when balanced, are part of a healthy ecosystem. However, when blue‑green algae (cyanobacteria) appear in abundance, there is the potential for harmful toxin production.

This occurred locally during the summer of 2012 in Lower Bolton Lake, when a significant blue‑green algae bloom impacted the lake. The event highlighted how quickly water quality can change when environmental conditions allow algae to proliferate.

Many other lakes in Connecticut and beyond face similar challenges. As a local example, you may have seen ponds in the region that appear completely coated with green algae during late summer.

Exposure to this bloom may pose health risks, including:
  • Irritation of the skin, eyes, or ears
  • Gastrointestinal symptoms such as vomiting or diarrhea
  • Muscle cramps
  • In rare cases, more serious effects involving the nervous system or liver

To protect yourself, your family, and your pets, residents and visitors are advised to avoid the following during a bloom:
  • Any contact with lake water, including swimming, diving, playing, or wading
  • Drinking the water or allowing pets or livestock to drink it
  • Using lake water for filling pools or outdoor showers
  • Boating through areas where surface scums or algae are visible

A helpful guide developed by the Lake Champlain Committee - Recognizing Blue Green Algae in Lake Champlain - provides useful information for identifying blooms.
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Additionally, some lake communities have established Blue Green Algae Monitoring Programs to track conditions and protect public health. Their experience, including documented results from 2012, may offer a valuable model should monitoring efforts expand in Bolton Lakes.
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