Warm, sunny fall weather produces HABs on Adirondack lakes 

First-ever cyanobacteria blooms documented on Lake Colby, Lower Saranac Lake, Moose Pond

By Zachary Matson

Warm, sunny and calm weather in recent weeks drove the formation of cyanobacteria blooms on lakes and ponds throughout the Adirondacks, including the first blooms recorded on Lake Colby, Lower Saranac Lake and Moose Pond.

A bloom emerging on Mirror Lake at the end of October was observed across the whole lake and persisted for multiple days – the second recorded bloom on Mirror Lake and the first since 2020.

Scientists suspect the blooms flourish in warm and calm fall weather when sunlight and a churn of nutrients combine to spur rapid cyanobacteria growth, forming what are known as harmful algal blooms (HABs). In some forms, cyanobacteria  can produce toxins harmful to humans and animals. The state Department of Environmental Conservation cautions people to avoid all algae-like formations and report any sighting. 

“Know it, avoid it, report it,” the DEC advises. 

Some blooms cover a small area while others, like the recent Mirror Lake bloom, can spread lakewide. Interest in the blooms has ramped up in recent years and reports are increasing —though researchers remain unsure of the extent blooms are actually increasing. Cyanobacteria, also known as blue-green algae, were one of the first organisms to form.   

Adirondack Watershed Institute researchers paddled around Mirror Lake on Oct. 31 to document the extent of the bloom. The Mirror Lake Watershed Association worked with town employees to place signs around the lake warning people to avoid the algae-like formations. 

“Once is an anomaly, twice means it’s going to happen again,” said Bill Billerman, vice chair of the association.

Scientists are working to understand how, where and why HABs occur and what leads to toxins formation. DEC outlined dozens of research topics in a 2021 report. The increased attention has led to a surge in HAB reports across the state, and HABs are being documented for the first time on new lakes each year. 

“There are quite a bit of reports coming in,” said Brendan Wiltse, senior research scientist at the Adirondack Watershed Institute. “There needs to be more work to understand these.”

Scientists have raised a litany of possible factors influencing formations, including warming water temperature, internal lake dynamics, agricultural and stormwater runoff, septic tank and road salt pollution, invasive species and more.  

State officials confirmed HABs on over a dozen Adirondack lakes this summer and fall, including at Lake Champlain on numerous dates.

Sightings on the DEC HABs tracking map list: 

• Lake George (Warren County), Oct. 26;
• Willis Lake (Hamilton County), Sept. 8;
• Otter Lake (Oneida County), Sept. 10;
• Raquette Lake (Hamilton County), Oct. 15;
• Lower Saranac Lake (Franklin County), Oct. 5;
• Upper Saranac Lake (Franklin County), Sept. 7;
• Copperas Pond (Franklin County), Aug. 11;
• Whey Pond (Franklin County), Aug. 15, Sept. 5, Oct. 23;
• Rat Pond (Franklin County), Sept. 2;
• Barnum Pond (Franklin County), Sept. 3, Sept. 9;
• Meacham Lake (Franklin County), Sept. 30;
• Moose Pond (Essex County), Oct. 23;
• Mirror Lake (Essex County), Oct. 31, Nov. 2, Nov. 4;
• Fern Lake (Clinton County), Aug. 1;

Cyanobacteria can release toxins that cause nausea, vomiting, diarrhea, skin or throat irritation, allergic reactions or asthma-like breathing difficulties. DEC warns of risks from HABs regardless of the presence of toxins. Public beaches and drinking supplies are given special attention. 

“Exposure can cause health effects in people and animals when water with HABs is touched, swallowed, or when airborne droplets are inhaled,” according to DEC. “This is true regardless of toxin levels.”

Many HABs, including the recent one on Mirror Lake, are not tested for the presence of toxins. In a statement, DEC said it “does not routinely test reported HABs for toxins” but that algal toxins are tested on 24 Adirondack lakes as part of a monitoring program not focused on HABs. The statement said “several HABs in the state are found to contain toxins” each year and that while 2022 data is still under review, state officials expected that trend to continue. 

DEC does test some HABs for toxins and the Department of Health works with public water suppliers to monitor and respond to HABs near water sources. In the past decade, the state has documented around 270 confirmed HABs producing toxins statewide, including on The Lake in Central Park, according to DEC data. 

Occurrences of toxins have been less frequent inside the Blue Line. Lake Placid registered toxins in a 2015 HAB and a 2019 HAB on Mountain Lake in the southern Adirondacks tested positive for toxins, according to the state data.     

A pair of “small, localized” HABs were detected on Lake George on Oct. 26 in Basin Bay and Bolton Bay along the lake’s western shore. Neither of the small formations were producing toxins, the Lake George Association said in a Thursday update.

After the 2018 announcement of a statewide HABs initiative, DEC developed HABs action plans for over a dozen lakes across the state, including Lake George and Lake Champlain.  The plans focus on watershed management strategies to reduce nutrients from sources like wastewater treatment plants, storm runoff and septic systems. 

The Lake George plan was updated this summer and highlights the need to expand sewer infrastructure, improve stormwater collection and replace failing septic systems in the coming years. 

 “We want to continue to prioritize these projects for state funding,” Lauren Townley, a DEC watershed management planner, said during a presentation at the Lake George Park Commission’s September meeting. 

The Lake George plan notes that water temperatures in the lake increased 3.2 degrees from 1980 to 2009 and highlighted nearshore areas as especially important to monitor for HABs.