Water Quality Update

for Friday, Aug 1st 2025

Monday afternoon was HOT & the north end of the lake was very busy with people cooling off! Photo by Emily DeBolt

The Lake This Week


The week started off HOT! with a cold front bringing rain in on Thursday to cool things off. Unfortunately Monday afternoon brought our first HAB (cyanobacterial Harmful algal bloom or C-HAB) reports of the season. Both were located in the north end and were small and localized, with streaking on the surface and some dots throughout the water column. With the hot temperatures - conditions were ideal for more blooms - and we were on the lookout - but so far we have just had the two reports


All in all - It was a gorgeous week to be out enjoying the lake!

First HAB report came in Monday afternoon on the west side a bit south of Butler Beach. CLWA staff went over to Butler Beach and took a look and checked in with the life guards, but everything looked okay at the swimming area still.

Map shows location of two bloom reports from Monday afternoon. Both were small and localized. The interactive map is available on our website for more details.

Latest HABs research: Microsystis releases chemicals to suppress competitors

A new study published July 2 from Cornell researchers found that microsystis, a common cyanobacteria in HABs, boosts its success by releasing chemicals that block competitors from getting a vital vitamin, helping it dominate lakes and cause harmful blooms.


Here's How:

  • Microsystis releases chemicals called antivitamins that look like vitamin B1 (thiamin).
  • Other algae take in these fake vitamins, thinking they are real.
  • Once inside, the antivitamins block enzymes that need real B1 to help the algae grow.
  • This slows down or harms the growth of those algae.
  • M. aeruginosa has a special enzyme that lets it make its own real B1 and resist its own antivitamins.



Read more about this research here.

HAB on Canandaigua Lake Sept 2024. photo by Emily DeBolt

Boat Launch Steward Program Mid-Season Update

The Finger Lakes Partnership for Regional Invasive Species Management (FLPRISM) staffs three boat launches at Canandaigua Lake with watercraft inspection stewards. FL PRISM provides full-time coverage until Labor Day for Canandaigua State Marine Park and Woodville DEC Boat Launch and part-time coverage for Vine Valley; all launches then switch to part-time coverage until the end of October. CLWA and the Watershed Council (CLWC) also help fund this program to prevent the spread of aquatic invasive species (AIS) into and out of Canandaigua Lake.

Inspections to Date

  • Canandaigua State Marine Park: 2,326 inspections
  • Woodville DEC Boat Launch: 2,259 inspections
  • Vine Valley Beach: 37 inspections

Decontamination Efforts

  • 140 watercrafts decontaminated at Canandaigua State Marine Park

Peak Activity

  • Busiest day: July 4th, with 289 inspections completed across all three launches


If you are at the launch and see one of the stewards - be sure to say Hi and thank them for all their work this summer helping protect our Lake!

Inspecting a boat at Canandaigua Marine Park. photo by FL PRISM

Lake steward outreach table at Woodville DEC Boat launch. photo by FL PRISM

Stay informed so you can enjoy Canandaigua - or other New York Lakes - safely and confidently this summer.



We have a map on our website homepage for Canandaigua Lake reported blooms.


NYHABS Map

The link below leads to the NYHABS interactive map and displays the location of HABs in New York State. Each blue dot outlined in black represents a HAB reported in the past 2 weeks. There may be other waterbodies with HABs that have not been reported to DEC. All reports through our monitoring program are shown on our own map on our website. CLWA staff uploads all HABs report to the NYHABs database that we receive through our trained volunteers.


Visit NYHABS map here NYHABs map on Aug 1 shown below.

Remember - conditions can change rapidly. Please use caution when out on the lake and look for characteristics of HABs including water that looks like:


  • Pea soup, spilled paint, surface streaks or scum
  • Color's that are typically green, blue-green or yellow but can also be brown, red or purple
  • Typically found along shorelines or coves


For images and more information on HABs, refer to the section below.


Please, to keep yourselves and pets safe, avoid any water conditions that appear to be bloom-like. Don't hesitate to reach out to us at 585-394-5030 with any questions or email us at HABS@canandaigualakeassoc.org if you are concerned about water quality. Sending us photos of the water is strongly encouraged. Have a wonderful weekend and stay tuned.

About HAB's

Cyanobacteria, sometimes referred to as blue-green algae because of their color, are among the oldest organisms on Earth. They are naturally occurring in our lakes, generally in low numbers. 


When triggered by the perfect storm of conditions - such as heavy rains followed by a few days of warm weather with calm winds - cyanobacteria may begin to increase, forming “blooms”. HABs can appear quickly and persist for hours or days, or they can disappear almost as quickly as they formed.


Since previous research informs us that high levels of toxins (microcystin) may accompany the blooms, humans and our pets should avoid coming into contact with the water when an active bloom is observed.


How to identify blooms

Use visual cues to identify potential blooms. They can appear like pea soup, spilled paint, surface streaks or scum. The color is typically green, blue-green, or yellow, but can also be brown, red, or purple. When blooms are discovered, they are usually found along shorelines or in cove areas. They are most often seen along the stretch of shoreline that is impacted by the prevailing winds. However, during significant bloom events, sometimes they can be found in open water areas. 


Visit the NYS DEC website to learn more about identifying blooms.

What should you do if you suspect a bloom


When in doubt, stay out! 

  • Don't swim, wade, jetski, waterski or tube in a bloom.
  • Shower if exposed to bloom conditions. Wash pets off if they have gone into bloom-infested waters.   
  • Don't consume fish from the lake during blooms.
  • Do not use PRIVATE water drawn from the lake during a bloom. Public water supplies have safeguards in place and can be utilized unless you are otherwise notified.
  • Report the bloom to the NYSDEC NYHABs portal: on.ny.gov/habform 

HABs Links and Resources

Further reading on HABs and their impacts on human and pet health


NYS Department of Health HABs Website

NYS Department of Environmental Conservation HABs Website

Dogs and HABs

Drinking Water and HABs

Information for Surface Water Drawers during HAB Season

Article on the Contributing Factors to HABs in Canandaigua Lake


If you have any questions please don't hesitate to reach out to HABs@canandaigualakeassoc.org

New Finger Lakes Foam Reporting Tool Launched

Foam on Canandaigua Lake on October 3, 2024. photo courtesy Emily DeBolt

We are excited to announce the launch of a new Finger Lakes wide foam reporting survey. After working on Canandaigua Lake, Rick and Stella from GAR have expanded their research to include other lakes. We helped them adapt the Canandaigua Foam reporting tool into a larger region-wide survey. If you have participated in the foam survey in the past, you will now need to use this new foam survey. If you have the old one loaded into the Survey 123 app you will want to delete that one and download this one.


You can learn more all about the foam found on Canandaigua Lake and find the link to the survey on our Foam page on the website: https://www.canandaigualakeassoc.org/water-quality/lake-foam/


Read an update about GAR's work in our most recent Summer Newsletter here.

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