Lake Conditions and Blue-green Algae Bloom Updates

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. Learn more: Facts about Blue-green Algae

Current Conditions

September 22 Update

During the weekend, Missisquoi Bay developed a dense diatom bloom (Aulocoseira) which gave the water a brownish color. Foam had accumulated along the shoreline on Friday at the fishing access on Rt 78. This is likely caused by organic material released from the diatoms and aquatic plant fragments.

September 19, 2014

Limited numbers of reports coming in at this point in the season. Most locations reported good conditions this week and are considered generally safe. Variable conditions are to be expected in the St. Albans Bay area, in the southern region of the main lake, and Lake Carmi. Anyone on the water or shoreline in these areas should watch for changing conditions and avoid contact with blue-green algae blooms.

Many beaches and parks are now closed for the season, and volunteer reporting is wrapping up for the year. We will continue to report on selected areas through the end of September.

Thanks to all of the volunteer reporters, and our partners at the Department of Environmental Conservation Watershed Management Division and the Lake Champlain Committee.

Check Conditions Using our Interactive Map

Other Bodies of Water

Not all Vermont bays, lakes, and ponds are monitored. Be aware of changing conditions, and keep out of the water if you think blue-green algae may be present.

Thank you to all the volunteer monitors. Updates and data are provided in cooperation with the Department of Environmental Conservation Watershed Management Division and the Lake Champlain Committee.

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Lake Conditions Interactive Map

The map status of blue-green algae reflects conditions and data as of the date of report. Test site observations and samples are collected once each week.

Map and Report Archive: 2013 | 2012

Current lake conditions may change. If you see blue-green algae, don't go in the water.

For more information call 1-800-439-8550 or email our Environmental Health Division.

The interactive Lake Champlain status map brings together in one place environmental and public health surveillance data about Blue-green algae. The map is a data collaboration project of the Departments of Health and Environmental Conservation.

Find searchable data and information about the links between the environment and public health at our Vermont Environmental Public Health Tracking Portal.

Alert Levels

The interactive map color codes correspond with alert levels.

Generally Safe - green
No toxic blue-green algae blooms were present along these shoreline areas when we sampled. These areas should be safe for recreational uses.

Low Alert - yellow
These shoreline areas have blue-green algae that produce toxins, but toxin concentrations are currently below levels of concern. These areas are open for recreation, but caution is advised in any areas where dense accumulations or scums are apparent.

High Alert - red
These shorelines have blue-green algae in dense scums at least in some areas, and toxin concentrations are above levels of concern. The water is not safe for recreational use in areas that contain scums. Please see Department of Health information about beach closings and hazardous areas.

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Watch for and Avoid Blooms

Wind and waves can move algae around. Blooms can appear or disappear very rapidly, so conditions around the lake are likely to change over the course of the week. As always, watch for and avoid blue-green algae blooms.

Report Suspected Algae Blooms

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Illness concerns

If you believe that someone has become ill because of exposure to blue-green algae, seek medical attention and contact the Health Department at 1-800-439-8550.

Keep pets away from algae blooms.

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