2022 Season: HABs REPORT CARD


If you are having a hard time recalling last year’s harmful algal bloom (HABs) season, there might be a good reason why! Compared to previous years, CLWA water monitoring volunteers observed fewer cyanobacteria blooms (cyanoHABs) during the 11-week monitoring period last summer. With increased participation, 67 shoreline volunteers monitored 61 zones along the lake. Out of 404 observations submitted, only 33 blooms were documented, with the highest number in the Northeast/Central East regions. No blooms were reported in the southern portion of the lake.

Table 1. 2022 Canandaigua Lake Shoreline CyanoHABs Monitoring by Region








The 2022 algal bloom season on Canandaigua Lake had several reported blooms. The first was a small, localized shoreline bloom on August 16th in the northwest region. On September 9th, another shoreline bloom was reported in the northeast/central east area, with visual observations from six volunteers. Additional bloom activity occurred on September 17th and 18th, primarily in the northern half of the lake, with eight reports. Two smaller blooms were reported on September 24th and 30th, with four and three visual observations respectively. Unlike previous years, there were no lake-wide blooms. The majority of the reported blooms were identified as “small, localized,” and were confirmed by NYSDEC based on photos.

CLWA’s shoreline volunteer observations on cyanoHABs were shared in the weekly Water Quality Updates by CLWA and the Canandaigua Lake Watershed Council. These organizations rely on the valuable observations made by CLWA volunteers to keep the watershed community informed.

A total of 14 bloom samples were collected for microcystin testing at the Finger Lakes Institute in Geneva. Out of these samples, 12 had microcystin concentrations exceeding the USEPA recreational threshold of 4 μg/L. The concentrationsranged from 3.3 to 366.0 μg/L. It is worth noting that microcystins can persist even after a visible cyanobacterial bloom disappears, with a typical half-life of four to 14 days, influenced by factors such as photodegradation, bacteria, and organic matter. Ongoing research in the Finger Lakes region continues to focus on the persistence of microcystin toxins. CLWA is grateful to its dedicated volunteers and partners, including Seneca Lake Pure Waters Association (SLPWA), Canandaigua Lake Watershed Council, NYSDEC, and Finger Lakes Institute, for their continued support of the Shoreline CyanoHABs Volunteer Monitoring Program.

So what accounts for fewer observed blooms during the 2022 season? “We know many factors play a role in the development of cyanoHAB blooms, like, nutrient run-off, invasive species, (specifically dreissenid mussels which can release and recycle legacy nutrients), and climate change,” states CLWA Citizen Science Committee Chair Sally Napolitano. “The spring and summer of 2022 experienced “abnormally dry” conditions for much of our area according to the U.S. Drought Monitor. This may have denied the cyanobacteria much of the nutrients needed to fuel their growth for bloom development. Through our project with Greg Boyer at SUNY-ESF, we know Microcystis was present as early as June 14th, 2022 when we began our weekly sampling and imaging, but fortunately, their growth didn’t rise to the “bloom” level as early or as frequently as in past years. More research needs to be done to understand the role of both dreissenid mussels and nutrient pulses delivered by rain events and their impact on the formation of cyanoHABS.”


Associate Director of Educational Programs at hobart & william smith colleges

U.S. EPA. 2019. Recommended Human Health Recreational Ambient Water Quality Criteria or Swimming Advisories for Microcystins and Cylindrospermopsin. EPA Document Number: 822-R-19-001. Available from: https://www.epa.gov/sites/default/files/2019-05/documents/hh-rec-criteria-habs-document-2019.pdf