Cyanobacteria: Blue-Green Algae

Report a Blue-green Algae Bloom

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Blue-green Algae map iconCheck Lake Conditions

 

Why be Concerned about Blue-green Algae?

Blue-green algae bloom in Quebec Cyanobacteria, also referred to as blue-green algae, are a common and natural component of the microscopic plants (plankton) in Lake Champlain.

Learn more: Facts about Blue-green Algae

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:

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.

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Monitoring for Blue-green Algae

Cyanobacteria on Lake Champlain are monitored by joint efforts from the Lake Champlain Committee and the Vermont Departments of Health and Environmental Conservation.

The Lake Champlain Committee coordinates and works with a group of citizen volunteers to monitor shoreline sites in Missisquoi Bay, St. Albans Bay, the north lake and islands area, and the south lake. Shoreline sites on Lake Champlain are of public health interest because there is a higher risk for people or pets to come into contact with cyanobacteria at these locations. Also, generally the highest amounts of toxins can be found in shoreline scums.

The Vermont Department of Environmental Conservation monitors long-term water quality at off-shore stations in Lake Champlain.

taking a sample of a blue-green algae bloomFor Lake Champlain, approximately 40 shoreline sites and 15 off-shore stations are monitored throughout the season.

Throughout the summer months, Lake conditions are reported from state and volunteer monitors to the health department. Lake conditions and an interactive tracking map are updated weekly based upon monitoring reports and tests.

The Health Department, working with local and state partners, began a pilot program in 2013 to get background information of cyanobacteria ecology at four inland lakes. The lakes included in this program are Memphremagog, Carmi, Elmore and Iroquois. The same monitoring protocol used at shoreline sites on Lake Champlain will be used at these sites. This program will focus on recreational areas on these lakes.

On a broader scale, our Vermont Environmental Public Health Tracking portal brings together in one place environmental and public health data, to help us better understand how environmental hazards can contribute to certain illnesses. The Vermont portal also supplies data to the National Tracking Network to address local environmental public health concerns.

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Guidance for Vermont Communities

Blue-green Algae Guidance for Vermont CommunitiesBlue-green Algae (Cyanobacteria)
Guidance for Vermont Communities
PDF document
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.

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