Blue Green Algae

What is Blue Green Algae?

Blue-green algae, or cyanobacteria, are a group of photosynthetic bacteria that can release harmful toxins and skin irritants. Naturally present in very low concentrations in lakes and streams, a combination of key environmental factors and weather conditions can favor blue-green algae growth and form blooms and surface scums where toxins may become concentrated enough to become a health threat. Blue green algae is also referred to as “Harmful Algal Blooms” or “HABs.”


Exposure to blue-green has the potential to cause illness in humans and animals. A person can become exposed to blue-green algae through swimming, inhaling water spray (e.g., when boating or water skiing), or by swallowing contaminated water. Blooms can also have a negative impact on the Lake by discoloring water and producing foul odors that result from the decomposition of blue-green algae cells.


  • Do not swim in or swallow water containing algae scums/blooms; Do not swallow lake water even if algae is not present.
  • Do not boat, water ski, jet ski, etc. over affected water.
  • Do not let children play with scum layers, even from the shore.
  • Wash and dry any clothing and equipment that has come in contact with algae scums.
  • Do not let pets drink or swim in waters experiencing blooms.
  • Immediately rinse off pets with clean water after contact with surface water before they get a chance to groom and ingest toxins that may have collected in their fur.
  • Never treat surface waters with chemicals, including herbicides or algaecides, without a permit from the Department of Environmental Conservation:
  • Always take a shower after coming into contact with any surface water (whether or not a blue-green algae bloom is present).
  • Consider medical attention of you experience sumptoms of neausea, vomiting, or diarrhea; skin, eye or throat irriation; allergic reactions or breathing difficulties. Report Symptoms to the Livingston County Department of Health


Blue-green algae cells can form into blooms and surface scums. Cyanobacteria are most often blue-green in color, but can also be green, blue, reddish-purple, or even brown. Blooms can take on the appearance of “pea soup,” green or blue paint, or form puffy clumps that float on the surface. Blue-green algae is often confused with filamentous algae which can also collect on the surface. If the bloom in question has a hair-like or stringy appearance, it is likely filamentous algae, which is not a health concern.

To Report a Suspect Algae Bloom of for Current Lake Status Please Contact:

Livingston County Department of Health - Center for Environmental Health
Phone: (585) 243-7280
Current Health Alerts

What is Livingston County Doing to Address this Threat?

In response to widespread blue green algae blooms on nearby lakes in 2011, the Conesus Lake Watershed Council developed a Blue Green Algae Detection and Response Plan overseen by the Livingston County Department of Health. Updated in 2015, the plan outlines testing, response and public notification procedures in the event of a blue green algae bloom. The implementation of the Conesus Lake Watershed Management Plan helps to reduce nutrients flowing off the landscape and into the Lake, which feeds algae blooms of all varieties.