Harmful Algal Blooms

Blue Green Algea on the water shoreOccurrence

Harmful algal blooms have been common in recent years during the latter half of the summer on lakes within Cayuga County.

Health Risks

Harmful algal blooms, also known as cyanobacteria, are of concern as they can produce toxins that could pose a health risk to people and animals when they are exposed to them in large enough quantities. Health effects could occur when the blooms are swallowed while swimming or through contact with the skin.

Consuming water containing high levels of harmful algal blooms has been associated with effects on the liver and on the nervous system in laboratory animals, pets, livestock, and people. Direct contact or breathing airborne droplets containing high levels of harmful algal bloom toxins during swimming or showering can cause irritation of the skin, eyes, nose and throat and inflammation in the respiratory tract.


Pet owners should keep their pets away from water experiencing algae blooms. If animals ingest the toxins either through drinking or cleaning their fur after exposure, they can become sick quickly.

As a reminder, the Cayuga County Health Department encourages the community and visitors to: Know It, Avoid It and Report It. 

  1. Know It
  2. Avoid It
  3. Report It

Surface waters that are discolored with a paint-like or filmy appearance or floating scum should always be avoided as they are potentially harmful. Images of these types of blooms as well as non-harmful blooms can be viewed by visiting this Department of Environmental Conservation link.


Weather influences where harmful algae blooms will occur. During extended periods of calm and sunny days, blooms can accumulate at the surface in any location. Wind and waves may cause them to form along shorelines or in protected areas. Shifts in wind direction can move a bloom from one location to another. Periods of cool rainy weather can often lead to the disappearance of a bloom.