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Algal Bloom Monitoring

The Harmful Alagal Bloom (HAB) Monitoring program was created for Owasco Lake in 2015 to better monitor harmful algal blooms in Owasco Lake. The program is a joint effort between New York State Department of Environmental Conservation (NYS DEC)Owasco Watershed Lake Association (OWLA), Cayuga County Department of Health, and Inspection and Protection Division.

2016 Results                                        2017 Results

2015 Results

A bloom has potential to be harmful when high concentrations of cyanobacteria species (formerly known as Blue-Green Algae) are present. HABs can be harmful to humans, pets, and wildlife. Symptoms of HAB exposure can include: skin irritation, nausea, vomiting, allergic reactions, and in rare cases, death.

Currently, predicting a bloom is very difficult, but common factors associated with a bloom are warm, calm waters, sunlight, and high nutrient concentrations. Over the last few years, Owasco Lake has experienced an increase in the frequency of algal blooms, possibly as a result of heavy rains and nutrient loading. 

According to NYS DEC, HABs occur when cyanobacteria concentrations exceed 25-30 micrograms per liter (ug/L) and water is considered toxic (based on elevated risks for swimmers) when toxin levels are above 20 ug/L

Visit NYS DEC for more HAB information.

From the NYS Department of Health:

Program Information

Sampling Process:

Algal Bloom (HAB) samples are collected from Owasco Lake to determine the species of cyanobacteria present in addition to nutrient and toxicity levels. The HAB program is administered in coordination with the NYS DEC water sampling protocol of the Citizens Statewide Lake Assessment Program (CSLAP), organized by Scott Kishbaugh and the SUNY College of Environmental Science and Forestry (ESF).

According to protocol, two samples are drawn from the lake when a bloom resembles visual cues outlined by NYS DEC, including: a pea soup color, streaks of green, appearance of spilled paint, or green dots (see photos left). One sample is sent to ESF for species determination and toxicity, while the other bottle is taken to Upstate Freshwater Institute (UFI) for nutrient analyses.

Scott Kishbaugh shares results with the Inspection Program, Cayuga County Deptartment of Health, Owasco Watershed Lake Association (OWLA), and other organizations involved in Owasco Lake Watershed management, as well as adding the information to the NYS DEC HAB Notice webpage.

In 2016, surveillance efforts expanded thanks to increased funding from NYSDEC, which allowed for 80 bloom samples to be analyzed, up from 25 samples in 2015. Expanded monitoring efforts continue today and will help: (1) the community better understand the occurrence of blooms on the lake and whether they contain high toxins; and (2) identify trends that may develop between bloom location, time of year, water temperature, toxicity, and bloom density.


In order to improve since the 2016 HAB surveillance, 24 zones are routinely surveyed, monitored, and sampled by shoreline resident volunteers, every Monday, from early July through early October (see map at right for zone locations). In May 2016, NYSDEC HAB coordinators held two training sessions for volunteers. Training sessions provided program information including: how to recognize the visual cues of a bloom, the proper technique for sampling, and how to best document blooms they observe. Volunteer citizen scientists allow for consistent HAB surveillance around the lake which one or 2 folks could not carry out alone.  

NYS DEC Harmful Algal Bloom Visual Cues

HAB: Green Dots
HAB: Green Streaks
HAB: Spilled Paint
HAB: Pea Soup

click images for more information

Visual Cues

2016 HAB Monitoring Zones

For now, it is difficult to predict the where and when of harmful algae blooms, so watershed residents and visitors should be aware of how to identify and when to avoid potentially harmful, concentrated blooms. The New York State and Cayuga County Department of Health (DOH) have adopted the slogan of “Know It-Avoid It-Report It.”


  • Know It: Harmful Algal Blooms come in many forms and look very different; the common cues are spilled paint, streaks on the water surface, pea soup color, or small green dots suspended in the water column.

  • Avoid It: HABs may contain toxins that can cause skin irritation, nausea, vomiting, diarrhea, and many other illnesses. Never drink water that may have been drawn from an area that is experiencing a bloom and avoid all recreational activities near a bloom.

  • Report It: Blooms can be reported to the Owasco Lake Watershed Inspection Program at (315) 427-5188, or to the NYSDOH at If you or your pets experience any symptoms that may be related to a HAB, please contact your family doctor and/or report the illness to the Cayuga County DOH.

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