Cyanobacteria: Blue-Green Algae
Report a Blue-green Algae Bloom
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- Why be Concerned about Blue-green Algae?
- Monitoring for Blue-green Algae
- Conditions on Lake Champlain
Why be Concerned about Blue-green Algae?
Cyanobacteria, also referred to as blue-green algae, are a common and natural component of the microscopic plants (plankton) in Lake Champlain. Some types of blue-green algae produce natural toxins or poisons. When these algae die and break down, toxins can be released into the water.
There are no documented cases of human illness related to blue-green algae in Lake Champlain. However, caution around the algae is urged, especially for pet owners. If animals ingest the toxin, they can be quickly paralyzed and die. Signs of poisoning include weakness, staggering, difficulty breathing, convulsions and death.
During the summers of 1999 and 2000 the death of two dogs was attributed to blue-green algae poisoning, after drinking large amounts of contaminated water directly from the lake.
Blue-green algae can become very abundant in some sections of Lake Champlain once the water warms up in mid-summer. Particular problem areas are Missisquoi Bay and St. Albans Bay. Under calm conditions, blue-green algae can accumulate in thick layers at the surface or along the shoreline. These accumulations are frequently referred to as “blooms” or “scums.”
While blue-green algae toxins have been detected at many locations in Lake Champlain, the highest concentrations of toxins are usually found in blooms and shoreline scums. These dense accumulations pose the greatest potential health risks. Watch for dense accumulations of algae and avoid these areas.
Blooms generally have the following properties:
- Water may appear cloudy and look like thick pea soup.
- Blooms are generally green or blue-green in color, although they can be brown or purple.
- A thick mat or foam may form when a bloom washes onto shore.
Weather influences where blue-green algae will accumulate in a given location. During extended periods of calm and sunny days, blooms can accumulate at the surface in any location. Wind and waves may cause them to form along shorelines or in protected areas. Shifts in wind direction can move a bloom from one location to another. Periods of cool rainy weather can often lead to the disappearance of a bloom.
Monitoring for Blue-green Algae
The University of Vermont’s Rubenstein Ecosystem Science Laboratory is conducting a monitoring program for blue-green algae, in order to identify locations around Lake Champlain where there may be a potential risk to people and pets.
Working with the Vermont Department of Environmental Conservation, the Rubenstein Lab is monitoring 14 stations around all of Lake Champlain about every two weeks. The lab samples additional sites in Missisquoi Bay, St. Albans Bay, and Burlington Bay on a weekly basis once a bloom occurs.
Because the highest concentrations of toxins are found in shoreline locations where scums can form, and the shorelines are where most people recreate, the Rubenstein Lab has developed a special program focused on these locations.
Working with the Lake Champlain Committee, the lab has recruited a group of citizen volunteers that monitor about a dozen shoreline sites in Missisquoi Bay, St. Albans Bay, the north lake and islands area, and the south lake. These citizen volunteers watch for blooms and take weekly samples that the Rubenstein Lab can analyze for the presence of toxins.
Guidance for Vermont Communities
Blue-green Algae (Cyanobacteria)
Guidance for Vermont Communities 
The appearance of Blue-green algae (cyanobacterial) blooms is expected to continue to increase in the coming years. Lakes and ponds previously not impacted by blooms may experience blooms. This guide is intended for lakes and ponds with new or sporadic appearances of blooms. It is not appropriate for guidance in heavily impacted areas.
The focus of this document is to ensure adequate protection of public and animal health when cyanobacterial blooms occur in lakes and ponds. Its intent is to assist local officials and other community members identify and respond to the cyanobacterial blooms so as to best protect public and animal health. This guide, however, is not a regulatory guide, a prevention manual, nor a practice for public water system operation.