Energy & Environment

With cyanobacteria blooms into fall, is Vermont doing enough to protect public health?

Burlington beach
Three Burlington beaches were closed Friday after blue-green algae was spotted. Photo by Aidan Quigley/VTDigger

After yet another summer with headline-grabbing cyanobacteria blooms in Vermont, the state still does not have recreational or drinking water standards for cyanotoxins.

State officials say that Vermont has instead mounted a robust — albeit voluntary — effort to inform the public about risks of cyanobacteria blooms and test drinking water for toxins. 

During the last week of October, multiple locations on Lake Champlain, Lake Carmi and Derby Bay in Lake Memphremagog had alerts for cyanobacteria blooms.

The blooms, which are expected to become more common in Vermont with warming waters and heavier precipitation events due to climate change, are considered an “emerging public health issue” by the Centers for Disease Control and Prevention. While cyanobacteria are native to Vermont, nutrient-laden runoff combined with warm waters can lead to explosive — and potentially toxic — blooms.  

With two dogs dying this summer in Stowe from cyanotoxin exposure and blooms lasting until November, some environmental advocates question whether Vermonters are informed enough about the risks posed by the ever-changing blooms. 

Exposure to cyanobacteria can lead to rashes or skin irritation, diarrhea, vomiting, liver damage and numb limbs. Children and pets are at greater risk of being exposed to cyanobacteria because they’re more likely to swallow water or play near the shoreline, where blooms are generally densest.

Recreation safety based on visual monitoring

Vermont has had a cyanobacteria tracking program for the past 16 years to monitor beaches and lake accesses, mostly in Lake Champlain, for the potentially toxic blooms.

Monitors originally took water samples to test for cyanobacteria toxins, but in 2012 the state and the Lake Champlain Committee switched to visual inspections in order to monitor at more sites. Reports are classified as “generally safe” if little to no cyanobacteria are present, “low alert” if small amounts of cyanobacteria are present, and “high alert” if high amounts are present — forming dense blooms or colored waters.

Department of Health, Department of Environmental Conservation and LCC staff review incoming reports, reaching out to beach managers as soon as possible if incoming reports show there might be a bloom present. At some town beaches, like in Burlington, staff also conduct visual inspections for blooms and do not reopen beaches until after toxins testing comes back clean. 

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But beach managers are not required to test for cyanotoxins before reopening beaches. James Ehlers, executive director of Lake Champlain International, feels it’s “irresponsible” to list any beach as generally safe without testing for toxins. 

“There should be standing warnings for water bodies that have had historic cyanobacteria outbreaks that toxins may be present all season,” he said. “I mean, we shouldn’t be relying on the death of people’s pets as our educational moments.” 

However, Bridget O’Brien, toxicological analyst with the state Department of Health, said that Vermont data indicate that the toxins do not persist after the blooms are gone.

O’Brien said that the state has been collaborating with towns on “new and better ways” to spread the word about cyanobacteria, including over social media. The department has also been meeting with parks and recreation staff at lakes around Vermont to encourage them to regularly monitor for blooms. 

“Lake Champlain gets so much attention that some folks aren’t aware that cyanobacteria blooms can be present other places as well,” she said.  

Lake Carmi
Lake Carmi was closed for three months in late 2017 because of toxic algae blooms caused by pollution from local dairy farms. File photo by Mike Polhamus/VTDigger

In recent years, scientists have started looking into whether the toxins can become airborne in water droplets produced by waves or boats. The concern is that even for people who are not swimming in water, aerosolization of the toxins could be another route for exposure

Dartmouth neurologist Dr. Elijah Stommel has found a correlation between areas with cyanobacteria blooms and occurrences of ALS, including Shelburne Bay and Mascoma Lake in New Hampshire.

However, a 2017 review by USGS found that the hypothesis that cyanobacteria could contribute to degenerative neurological diseases is “not supported by existing data.” 

No drinking water standards

Vermont has health advisories for three cyanotoxins — microcystin, cylindrospermopsin, and anatoxin-a. The state Health Department has health advisories for dozens of potential drinking water contaminants but drinking water managers are not required to test and treat for contaminants unless there are also federal or state drinking water standards. 

Currently, Ohio is the only state with legally enforceable drinking water standards for cyanotoxins. 

The state Department of Environmental Conservation’s drinking water program encourages public drinking water supply managers to conduct daily visual inspections for cyanobacteria during the summer and fall, and to reach out to the state to see if cyanotoxin testing is needed. 

The state has also worked with the Lake Champlain Committee for the past five years to obtain funding for weekly cyanotoxin testing at the 22 drinking water supplies in Vermont that take in water from Lake Champlain. Testing this year cost $22,000. 

None of the Lake Champlain samples taken since 2015 have detected cyanotoxins in raw or treated water. There are also 10 drinking water utilities in Vermont that are testing for cyanotoxins through the EPA’s unregulated contaminant monitoring program

In addition to inspecting for algal blooms, water managers have been trained to look for other indicators of cyanobacteria blooms, like changes in pH, turbidity and an increased demand on chlorine. 

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The state’s drinking water program also advises private well owners to test their water — and to, of course, not drink any green water. About 30% of households in Vermont drink from private wells, according to the Health Department. 

However, managers of public drinking water supplies in Vermont are not required by law to test for any of the toxins. 

“I believe that it should be a drinking water standard,” said Jen Duggan, Vermont director of Conservation Law Foundation. “I think without a regulatory requirement to test and treat, you’re not protecting public health.” 

Ehlers expressed concerns that the Lake Champlain drinking water managers stop testing for toxins at the end of September, though blooms in recent years have persisted through the fall

“It’s worse now than it is in June and this is the case every year,” he said. 

Bryan Redmond, drinking water and groundwater protection division head for the state Department of Environmental Conservation, said that “there is not a cause for concern in drinking water at this time” from cyanobacteria in Vermont. 

He added that the division’s limited resources are focused on federally mandated testing and two new programs Vermont launched this past year to test for lead in daycares and schools and for PFAS compounds in drinking water systems around the state

“The data so far show that we are prioritizing our limited resources where the biggest risks are to make sure Vermonters are protected,” he said. 

Ohio, which ramped up its cyanotoxin testing after detecting microcystin in Toledo’s drinking water in 2014, became the first state in the country to set drinking water standards for cyanotoxins. The state also partnered with universities in a landmark research project to better understand and reduce harmful blooms. 

Tom Bridgeman, a University of Toledo limnologist who is the co-chair of the research initiative, said daily testing of water during the bloom season is important. The Ohio initiative has put buoys in Lake Erie that act as sensors “to detect when a bloom is coming toward the water intake” point. 

Bridgeman said beach and drinking water managers should not solely rely on visual inspections of blooms. For one thing, scientists, including researchers at UVM, are still trying to better understand what leads the blooms to become toxic, as even toxin-generating species do not always produce toxins. 

“One thing we’ve learned is that the amount of toxin produced by the algae can vary by a factor of 10,” he said. “So the amount of cyanobacteria doesn’t necessarily correspond that well to the amount of toxins being produced.” 

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jeffrey green

Algae blooms are happening. Agree. But WHY do all the enviro’s immediately paint (slam) farmers as the evil culprit? Every lake affected has a BIG CLUE in common. ALL the lake Camps and houses are NOT on any sewage treatment hookup. They are primitive, stand alone systems…often right on the lakes shore and are untreated. In older days, many camps straight piped into the lakes!!! The author above stated in an earlier piece, that polluted sediments build up on the lake bottoms…to such a point they eventually release bacteria upwards and cause the algae blooms. SO WHY hasn’t ANY “enviro scientist” thought of taking lake bed sediment core samples and simply analyze – is the bad sediment human related sewage -bacterial entity. OR, is it commercial ferilizer build up from farms. Both very different makeups.. My bet is they would find decades and decades of human untreated sewage, slowly built up on the lake floor… and now releasing. Will NO ONE will check??

Jim Tomczak

This should concern the leader of the state. Wake him up.

Peter Chick

Please don’t blame Vermont for Burlingtons wastewater problems.

RICHARD Bernstein

Sad to see that cyanobacteria blooms and heavy growth of lake weeds are becoming the new normal for these precious Vermont resources. When are we going to get real serious about reducing phosphorus loading into our lakes?

Crea Lintilhac

“However, Bridget O’Brien, toxicological analyst with the state Department of Health, said that Vermont data indicate that the toxins do not persist after the blooms are gone.”
This analysis seems to run counter to what the EPA website reports as follows:
According to the EPA, when those species anatoxin-a and the microcystin, cells die or the cell membranes rupture, the toxins are released into the water (extracellular toxins). “

So, when the blooms die and are no longer visible, the toxins are released. This must be borne out by EPA scientists conclusions from their collecting and analysis of water quality, right?

jeffrey green

One here asked when to.. “get serious of phosphorus in lakes”? Why not find the root cause first, instead of seeking an instant “blames & victims”.. Here are facts: an article of August 2019, from a paper in the NY Adirondacks. They too are suffering outbreaks of algae blooms. But a glaring problem is this: in the lakes they mention in Adirondacks, with algae blooms, not a single one is anywhere NEAR a farm. Too Mountainous & rocky. No farms. No phosphorus fertilizers ANYWHERE near. So if NO fertilzer/phosphorus is anywhere, why aren’t the Enviros asking “How can that be”. I’m all for cutting back any fertilizer drift to all lakes. But, I’m also out for facts & truth – not victims to blame.. Ask yourself WHY no farms are near these Adirondack lakes, but they have same algae bloom as VT? Read:

Robert Gifford

I saw farmers today spreading liquid manure adjacent to lewis creek. Two days ago I saw farmers spreading liquid manure adjacent to the Huntington river. This manure will mostly end up in the lake. This practice is not something that should continue. If a farm can’t deal with its waste it should be forced to just like every homeowner in the state that has a failed septic system. How long would I be able to dump waste from my septic tank on the ground, get it all over the roads, stink up the whole neighborhood? Come on people we need new rules. This spreading of liquid Cow waste has to stop. It’s a failed idea. Its know to be the major contributor of phosphorus in the lake. Why does it continue?

morgan rye

it is of course essential to find out the WHY of the bacteria but the fact is that it IS and it is my opinion that the state is not doing enough in the monitoring department. people need to know when and where the blooms are so they can stay out of the water and keep their animals out of it as well.


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