Cyanobacteria

Cyanobacteria blooms can look very different depending on the species present, weather conditions, and where the bloom is in its life cycle. Early on, you may notice small green flecks, streaks, or suspended particles in the water, sometimes described as fuzzy green pinhead size balls. As cells accumulate, blooms can appear as cloudy or murky water, surface scums, or thick mats that may be green, blue-green, yellow-green, or even brown.  

Blooms often form in patches rather than evenly across a lake or shoreline and can shift quickly with wind and waves. In some cases, especially as cells are stressed or begin to break down, the water may take on a bright turquoise or blue-green coloration due to released pigments, but this does not occur in all blooms. You can learn more about identifying potential cyanobacteria blooms here or during one of our cyanobacteria monitoring trainings. 

Compounds produced by cyanobacteria can trigger skin irritations, gastro-intestinal illness, and other health effects. Toxins in aerosols may cause itching and irritation of eyes, nose, or throat. Some species produce toxins that affect the liver, while other species’ compounds affect the nervous system. Not all blooms produce toxins, and the presence and severity of health effects can vary.  

Children and dogs are most vulnerable for a number of reasons: they are less particular about what they eat or drink or where they swim; they are smaller; and they are more likely to ingest water. Dogs can receive a larger dose of toxins when they swim in a bloom then lick their fur. The deaths of two dogs during the summers of 1999 and 2000 were attributed to cyanobacteria poisoning from Lake Champlain water. 

Cyanobacteria blooms tend to be more prevalent in warm, shallow waters such as Missisquoi Bay. Deep, cold water locations with fewer nutrients, such as the Main Lake are less likely to support blooms. However, with warmer water temperatures associated with climate change and extensive nutrient loading from frequent storms and flooding, blooms are appearing in a broader area of the lake. Blooms are likely to occur during extended periods of calm sunny days. Wind and waves may cause them to accumulate along shorelines or in protected areas. Shifts in wind direction can move a bloom from one location to another. Cool rainy weather may disrupt a bloom. 

You can Report on Lake Champlain or Inland Lake conditions by becoming a cyanobacteria monitor! Volunteer monitors commit to going out once per week from mid-June through mid-fall if possible. (Cyanobacteria blooms are occurring later in the year so we are looking for monitors who can continue assessing conditions into late October if possible.) Observations are submitted via an online form and used to update the Lake Champlain Cyanobacteria Tracking map. Repeatedly visiting the same site helps us know of not just the presence of blooms, but also their absence. LCC provides training in detecting blooms and distinguishing them from other floating phenomena.

Learn more and sign up here!