Jeremy Deeds, aquatic ecologist with the Maine Department of Environmental Protection, records data and takes water samples on Sabattus Pond. Credit: Patty Wight | Maine Public

This summer’s media coverage of several dogs that died shortly after swimming in water tainted by toxic algae has brought public attention to the phenomenon of algal blooms. Federal agencies consider them an emerging public health issue and a major environmental problem across the U.S.

The intensity and frequency of these blooms are expected to grow because of climate change, and that has federal, state and citizen scientists racing to understand when and why the blooms suddenly turn toxic.

[Subscribe to our free morning newsletter and get the latest headlines in your inbox]

On a sunny September day, the water lapping at the shore of Sabattus Pond just east of Lewiston wasn’t blue — it was green and murky. Jeremy Deeds, an aquatic ecologist with the Maine Department of Environmental Protection, said that indicated that this 1,900-acre body of water had an algal bloom.

“Sabattus Pond, it’s usually having some level of bloom of algae throughout the entire year,” he said.

Deeds said at times, the bloom is so bad it forms a thick scum and looks like green paint.

Credit: Patty Wight | Maine Public

To learn more about this phenomenon, Deeds and other scientists come here every few weeks to gather clues. On a recent September day, he motored out to the middle of Sabattus Pond with Charlie Culbertson, a microbial ecologist with the U.S. Geological Survey. They checked the water’s clarity and took its temperature, and then Culbertson prepared a giant syringe about the size of a frozen popsicle to collect a sample of the water’s DNA.

As Culbertson pushed water through the syringe, the filter inside turned from white to green. What made it green — the source of the bloom — was cyanobacteria, sometimes called blue-green algae, which Culbertson said are among the oldest form of life on the planet.

“They’re fantastic organisms. They’re so well adapted to their environment,” he said.

And climate change, Culbertson said, is creating conditions for them to thrive.

“Warmer, wetter, higher CO2 in the atmosphere — plays right into their wheelhouse,” he said.

There’s another factor in Sabattus Pond that helps cyanobacteria grow: excess nutrients. Agricultural runoff going back decades has deposited phosphorus into the pond, setting the stage for the cyanobacteria population to explode. And Culbertson said those blooms can produce harmful cyanotoxins.

“Just because the organism is here does not mean it’s toxic, but it can shift on a dime,” he said.

Credit: Courtesy of Lisa Branch

That’s worrisome because it can cause serious health problems for people and pets.

Several dogs in southern states died this summer shortly after swimming in water with toxic algal blooms. Here in New England, regional poison center Director Dr. Karen Simone said calls related to algal blooms have been coming in since 2004.

“We’ve had 44 calls involving humans who think they were been poisoned, and six involving animals, mostly dogs, who we think may have been poisoned,” she said.

Simone said just a few of those calls came from Maine, with the rest from New Hampshire and Vermont. She said humans poisoned from algal blooms typically experience nausea, diarrhea, skin rashes and, in more serious cases, liver or kidney damage. Pets — especially dogs -— are more likely to experience more severe neurologic problems.

“One of the cases that stands out to me involved a dog that was swimming, and for this particular dog, there was a weakness and almost paralysis of the back two legs,” she said.

[Dog-killing toxic algae could surface in Maine’s waters]

Though Maine doesn’t see algal blooms with the same severity and frequency as in the south, scientists have said that will likely change. Scott Williams with the Lake Stewards of Maine said, in recent years, several lakes have experienced severe and unexpected algal blooms.

“And in each case, we’re fairly confident that climate change was part of the equation, part of the influence for those blooms,” he said.

Williams stood recently on the shoreline of Lake Auburn, just a short walk from his office. It’s the only public water source for the cities of Lewiston and Auburn.

“And this is a lake that historically has very good water quality. It’s the drinking water supply for two large communities, Lewiston and Auburn. And in 2012, the lake experienced a very serious bloom,” he said.

That year, Williams said, warmer spring temperatures melted the ice early. Then a severe storm caused substantial erosion, dumping nutrients in the watershed. That created ripe conditions for an algal bloom that depleted the lake of oxygen and caused a fish kill.

Credit: Patty Wight | Maine Public

The lake recovered, but another algal bloom last year caused taste and odor issues in the water supply, prompting the city to apply a special treatment.

Williams said there are ways to prevent algal blooms, such as limiting runoff and allowing native plants to grow on shorelines to act as filters. But he said change is already happening in Maine’s lakes, and the state must adapt.

“From our perspective, the most important thing is to get as many trained people out there and gather as much information as possible so we can better understand which lakes are most risk and see what can be done to reduce that risk,” he said.

Maine has about 3,000 lakes in the public domain, which makes it a challenge to monitor them all. Lake Stewards of Maine trains volunteers who monitor just under 500. They share that data with the Maine Department of Environmental Protection, which regularly monitors about two dozen lakes for blooms.

Back on Sabattus Pond, Deeds said the water quality in most of Maine’s lakes is very good. But he said the need to better predict toxic algal blooms is urgent.

“The numbers are small right now, but we are seeing a trend toward lakes getting worse. And when they do get worse, they get worse in a hurry,” he said

This article appears through a media partnership with Maine Public.