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040213_algaeWhat are Harmful Algal Blooms (HABs)?

Most algae are harmless and are an important part of the food web. Algae are naturally present in slow moving streams, lakes, marine waters and ponds in low numbers. Certain types can become abundant and form blooms under the right conditions. Some algae can produce toxins that can be harmful to people and animals. These are collectively called harmful algal blooms (HABs).

Algae blooms most frequently occur in nutrient-rich waters, particularly during hot, calm weather.

Because it is hard to tell a harmful algae bloom from other algae blooms, we recommend avoiding contact with any floating rafts, scums, and discolored water. Find out what water bodies have a blue-green algal bloom notice.

Freshwater Blue-green Algal Blooms

Blue-green algae, technically known as cyanobacteria, are naturally present in lakes and streams in low numbers. Blue-green algae can form HABs that discolor the water or produce floating rafts or scums on the surface of the water. These can cause health risks to people and animals when they are exposed to them.

Blue-green algae blooms can occur in freshwater lakes and ponds and can reduce the recreational value of a water body, due to unpleasant appearances and odors, and can cause a variety of ecological problems, such as reduced oxygen levels. They also have the potential to form harmful (toxic) blue-green algal blooms, although the factors that cause blue-green algae to produce toxins are not well understood.

Harmful blue-green algae blooms can cause health effects when people and animals come in contact with them. Symptoms can include nausea, vomiting, diarrhea, skin or throat irritation, allergic reactions or breathing difficulties. Blue-green algae can also produce toxins that affect the liver and nervous systems when water is consumed in sufficient quantities.

What should you do if you see a Harmful Algal Bloom?

  • If you see it – avoid it
  • People, pets and livestock should avoid contact with water that is discolored or has algae scums on the surface. Colors can include shades of green, blue-green, yellow, brown or red. If contact does occur, rinse thoroughly with clean water to remove algae.
  • Never drink untreated surface water, whether or not algae blooms are present. Untreated surface water may contain other bacteria, parasites or viruses, as well as cyanotoxins that could cause illness if consumed.
  • People not on public water supplies should not drink surface water during an algal bloom, even if it is treated, because in-home treatments such as boiling, disinfecting water with chlorine or ultraviolet (UV), and water filtration units do not protect people from HABs toxins.
  • Stop using water and seek medical attention immediately if symptoms such as vomiting, nausea, diarrhea, skin, eye or throat irritation, allergic reactions or breathing difficulties occur after drinking or having contact with blooms or untreated surface water.
  • Please report any health symptoms to NYS Health Department at harmfulalgae@health.ny.gov and your local health department (link leaves DEC website.)
  • For answers to other frequently asked questions go to the DEC HABs FAQ page.
  • If you suspect that you have seen a HAB or you, your family, or pet has been in contact with a bloom, please report the bloom to the DEC. Fill out and submit a Suspicious Algal Bloom Report Form (PDF, 763 KB). Email the completed form and, if possible, attach digital photos (close-up and landscape to show extent and location) of the suspected bloom to HABsInfo@dec.ny.gov.

More about Harmful Algal Blooms (HABs):

The Chautauqua Lake Association is the only entity that NYS collaborates with locally on identifying and confirming the presence of HABs.  Persons suspecting the presence of a HAB should contact the office so that we can investigate the situation.  If you experience any adverse effects from a possible HAB that would require a doctor’s visit for either a human or a pet, ask the doctor or vet to report his/her findings to the Chautauqua County Health Department. Below are some helpful resources for staying informed and safe around HABs: