ST. ALBANS – Is my water safe to drink? That’s the question the 200,000 Vermonters whose drinking water comes from Lake Champlain should be asking in the wake of one of the worst blue-green algae infestations in years.
Answering the question is complicated by a water testing program that was never intended to safeguard drinking water, rapidly changing conditions within the lake and scientific debates over the possible dangers of toxins from the algae.
Locally, 3,000 customers of the Swanton Village water utility and 10,000 customers of the St. Albans City utility are drinking water drawn from the lake.
“Every time you open your tap, you’re rolling the dice,” said James Ehlers, president of Lake Champlain International.
Residents are unaware of the symptoms associated with exposure to toxins from algae, which concerns Ehlers. “They think they ate a bad burrito,” he said.
Several studies have shown a connection between exposure to microcystin, one of the toxins produced by algae, and gastrointestinal distress.
Vermont’s testing system was designed with recreational users in mind, explained Angela Shambaugh, an aquatic biologist who oversees Vermont’s blue-green algae testing program.
State staff, volunteers and UVM scientists visit 15 stations on both the New York and Vermont sides of the lake twice a week. The sites are most commonly found near recreation sites, not drinking water intakes.
If the scientists and volunteers see evidence of an algal bloom, they will take samples to test. The state tests for microcystin and anatoxin, but not beta-methylamino-L-alanine (BMAA), the toxin tentatively linked to amyotrophic lateral sclerosis (ALS), better known as Lou Gehrig’s disease.
“Visual cues in and of themselves are not enough because the toxins are released after the cells die,” said Ehlers.
The toxins remain contained within the algae’s cells until the cells die, then they’re released into the water, explained Shambaugh. Not all blue-green algae produce the toxins, even if they have the genes to do so.
How long the toxins persist after death of the algae is an open question.
Researchers in Finland found that microcystin remained dissolved in lake water for 30 days following the death of a bloom. Shambaugh said that when UVM researchers were developing the state’s testing protocol they tested for toxins for two weeks after blooms dissipated in Missisquoi Bay and did not find significant amounts of dissolved microcystin.
The state has rarely found toxins in areas where a bloom wasn’t present, said Shambaugh. “When it does happen, the concentration has been very, very low,” she said.
One of the challenges of monitoring blue-green algae blooms is that the blooms can form and dissipate rapidly. “The conditions, they can change pretty much before I get back to the car (after visiting a site),” said Shambaugh.
Blooms can form, die, and release toxins without ever being captured by the state’s monitoring system, she acknowledged.
Three inches of blue-green algae floating on the surface of the water when the water is calm can quickly be dispersed through nine feet of water when the winds pick up, explained Shambaugh. “The population is really mobile,” she said.
“That’s one of the things that makes this very hard not only to monitor but to tell people how to respond,” said Shambaugh.
While the state can test samples fairly quickly – a test for microcystin can be completed in less than two hours – the changing conditions mean that a bloom could form, die and release toxins without ever being noted by monitors, Shambaugh said.
That means the state is reliant on operators of water facilities to watch for blooms near intakes and draw samples. Shambaugh acknowledged that not all operators are clear about when samples should be taken.
Swanton & St. Albans City
Swanton’s water intake is located more than 900 feet offshore in water that is typically 20 feet deep.
“We’re pretty fortunate where our intake is,” said Brian Bishop, the senior water plant operator. One of the state’s testing sites for blue-green algae is near the intake, he said.
In addition, Bishop keeps an eye out for blooms and has test vials on hand for taking samples. “I look for any kind of signs on the shoreline,” he said. “I’ve been here 15 years, and we’ve only had one bloom that I can remember.”
The city’s intake is further out, about 1,200 feet and is 20 to 30 feet down, depending on the lake depth. “There pretty much a constant current through there,” said Allen Robtoy, the city’s director of public works. “It’s placed in such a manner that the water there is constantly turning over.”
The city uses 2.2 million gallons per day, with 800,000 gallons coming from Lake Champlain. The rest comes for the reservoir the city owns in Fairfax, explained senior water operator Troy Baker.
“You can see the way it just keeps flowing north. Even when there’s no breeze you can see the waves,” Baker said of the area around the intake.
Although no testing is done at the plants for blue-green algae or toxins, the water is monitored constantly for turbidity. More turbid water is more likely to have algae.
Shallow intakes, like those in St. Albans and Swanton, are at a greater risk, said Shambaugh, who said water operators with intakes less than 60 feet need to be more vigilant.
Yet, Ehlers is doubtful of the safety created by depth, pointing to a study of a Turkish lake that found the highest concentrations of microcystin were at depths of 45 to 75 feet.
In 2013, Canadian scientists studying the health impact of algal blooms advocated that water facilities be provided with a plan for managing blue-green algae toxins. Benoit Levesque, et. al., studied the effects of exposure to blue-green algae on residents near Missisquoi Bay and two other Quebec lakes. The results were published in the journal Science of the Total Environment.
They found that residents exposed to blue-green algae during recreational use of the lakes were more likely to develop gastrointestinal illness. More severe cases coincided with higher concentrations of algae and toxin
However, those whose drinking water came from a public water system drawing water from Missisquoi Bay also showed a significantly higher instance of muscle pain, skin symptoms, and ear symptoms. The symptoms were mild.
“While it is premature to speak of a causal association, it is plausible that exposure to cyanobacteria contributed to the presence of these symptoms and that the water treatment process reduced the importance of symptoms without preventing them entirely,” Levesque et. al. wrote.
Their results supported the creation of management plans for public water systems near bodies of water contaminated by blue-green algae, Levesque, et. al. concluded.
Vermont’s Commissioner of Environmental Conservation David Mears has said the state will be improving its testing protocols in response to concerns about drinking water.