The harmful algal bloom identified last week in Upper Saranac Lake. Cyanobacteria is green in color and can often have the appearance of spilled paint. (Provided photo — New York state Department of Environmental Conservation)

SARANAC LAKE — A harmful algal bloom discovered in Upper Saranac Lake last week has now dissipated. The bloom was one of several identified throughout the Adirondacks following a bout of unseasonably warm weather.

The cyanobacteria, or blue-green algae, was first reported on Sept. 4 and reported again on Sept. 5. It mostly dissipated by Sept. 7 but was officially declared dissipated as of Tuesday, according to Guy Middleton, lake manager at the Upper Saranac Foundation.

“It was small and localized,” Middleton said.

The New York state Department of Environmental Conservation’s HAB geographic information system currently pinpoints three cyanobacteria blooms in the upper end of Upper Saranac Lake, as well as an archived bloom declared dissipated in July. Middleton expects that the recent blooms will soon be marked dissipated in the GIS archive.

Cyanobacteria blooms are, as their nickname suggests, incredibly harmful to people and pets. According to the DEC, a person’s sensitivity to HABs exposure can vary. Regardless, cyanobacteria is toxic and can affect people through skin exposure or ingestion. Anybody who wants to enjoy some lakeside recreation should check the HABs GIS and ensure there is no active bloom in their chosen body of water before embarking. Contact with a bloom can cause symptoms such as nausea, vomiting, diarrhea, skin or throat irritation, allergic reactions or breathing difficulties. Pets — specifically, dogs — who swim in affected water and later ingest the cyanobacteria while grooming can also experience negative effects such as seizures, convulsions, paralysis, disorientation, inactivity, elevated heart rate and difficulty breathing. The DEC recommends seeking professional care for people and pets alike if contact is made with a HAB.

HABs are a fairly common natural occurrence, though they are often spurred on by a lapse in watershed management or particular weather conditions. In the case of Upper Saranac Lake, Middleton believes the HABs were due to the latter cause.

“The conditions (last week) were just right for that to occur,” he said.

Brendan Wiltse, senior research scientist at the Paul Smiths’ College Adirondack Watershed Institute, attributes the recent crop of HABs across the region to weather conditions as well.

“Under the right weather conditions, these blooms form. We often see them in multiple lakes at a time,” he said. “There were several lakes at the beginning of last week that bloomed. Off the top of my head, Blue Mountain Lake, Raquette Lake, Upper Saranac, Barnum Pond, Bubb Lake all had blooms early last week, and that was likely triggered by the unseasonably warm, sunny and calm conditions that we had. Lower St. Regis Lake bloomed, as well.”

Wiltse said that HABs clear up on their own, and usually fairly fast. Given the right shift in weather conditions and wind, the bloom will disperse and dissipate within days. In the case of Upper Saranac Lake, Wiltse’s prediction proved right on track.

The Adirondack Watershed Institute took samples of the Upper Saranac HAB to study and identified the specific species that formed the bloom — Dolichospermum. According to Wiltse, it’s a common genus in the Adirondacks around this time of year.

Extreme weather events, and unseasonably warm weather, are expected to happen with increasing frequency as the planet warms as a result of climate change. This past summer, the effects were seen across the Adirondacks. Severe flooding hit the central Adirondacks in July, destroying roads and infrastructure in the Long Lake area. Smoke from wildfires in Canada impacted air quality in the Adirondacks at various times throughout the summer, prompting the DEC to issue air quality alerts warning residents to take precautions. There were also bouts of sweltering heat, with scientists and meteorologists proclaiming record-breaking temperatures throughout the summer.

“There is a question whether climate change is contributing to the bloom formation in the Adirondacks. Certainly, we know that weather plays an important role. We also know that the climate is changing in a way that is creating the conditions that (causes HABs) to be more likely here in the park,” Wiltse said. “We’re seeing the climate warming, especially in the fall, which is when we tend to see these blooms happen. So there’s nothing that can be done … in the moment when a bloom forms. It’s really just waiting for it to dissipate. But good stewardship practices in our watersheds can reduce the likelihood they will form.”

The DEC asks citizens to “know it, avoid it, report it” when it comes to HABs. HABs have several typical presentations, described by the DEC as “streaks, spilled paint, pea soup, floating clumps or dots.” They are green in color. There is a suspicious algal bloom report form on the DEC’s HABs page, and those who suspect a HAB are encouraged to either fill out the form or contact HABsInfo@dec.ny.gov for more information.