The Paul Smith’s College Adirondack Watershed Institute (AWI) has confirmed the presence of a harmful algal bloom (HAB) in Mirror Lake in the Village of Lake Placid, NY. On Monday, November 9^th, a concerned citizen contacted the Mirror Lake Watershed Association to report a suspicious algal bloom at the south end of the lake. A sample delivered to the AWI lab later that day was analyzed and confirmed the dominant algae to be a species cyanobacteria capable of producing cyanotoxins, harmful to people, pets, and wildlife.

AWI’s Water Quality Director, Dr. Brendan Wiltse, analyzed the sample; he says, “Cyanobacteria are a natural part of the lakes biotic community, the concern arises when dense blooms form. These blooms are capable of producing toxins that can be harmful to humans and animals. It is important to note that the presence of a bloom does not necessarily mean that toxins are present.”

Online information from the New York State Department of Environmental Conservation’s HAB Program states that exposure to any cyanobacteria HABs can cause health effects in people and animals when water with HABs is touched, swallowed, or when airborne droplets are inhaled. People and pets should avoid contact with any floating mats, scums, or discolored water, and should rinse off with clean water if contact occurs.

The bloom was reported at the south end of Mirror Lake, near the beach and public park. Bill Billerman, President of the Mirror Lake Watershed Association, states, “Our volunteers took quick action upon receiving the report. At this time of year, our primary concern is the safety of dogs and other pets that may enter the lake. We encourage the public to avoid letting their dogs enter the water if they are suspicious of whether a bloom is present.”

While it is too early to determine the cause of the bloom, experts say that continued monitoring will help understand contributing factors to the bloom. Wiltse says, “AWI field scientists sampled the lake on Friday and noted that it had turned over, a natural process that occurs in the fall that can bring nutrient-rich water from the bottom of the lake to the surface, possibly contributing to the HAB event. The unseasonably warm, sunny weather over the last few days may also be a contributing factor. Thankfully, we have a robust monitoring program that not only helped detect this early but will provide data critical to further our understanding of the circumstances around this bloom.”

This event is one that scientists have been warning about for several years. “The reduction in mixing from road salt puts the lake at greater risk of HABs. We will continue to work with our partners at AWI to understand what led to this incident. Our work on salt reduction, stormwater improvement, and other measures to protect Mirror Lake is more important now than ever,” says Ausable River Association Executive Director Kelley Tucker.

For more information go to www.health.ny.gov/harmfulalgae.

The mission of the Paul Smith’s College Adirondack Watershed institute is to protect clean water, conserve habitat and support the health and well-being of people in the Adirondacks through scientific inquiry, stewardship and real world experiences for students. https://www.adkwatershed.org/

The Ausable River Association was formed in 1998 to help communities in the Ausable River Watershed protect its streams and lakes. https://www.ausableriver.org/