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Water Quality Update for July 24, 2020

We hate to be writing our first water quality update in late July, but we are learning that conditions are becoming favorable for potential cyanobacteria (blue green algae) blooms on the lake. On Thursday, July 23rd, there was a reported bloom in the Crystal Beach area. A sample was collected and analyzed, and it was confirmed to be above the DEC threshold (25 ug/L – micrograms per liter) to be considered a Harmful Algae Bloom (HAB).

The stretch of warm, sunny and relatively calm conditions in July has been increasing surface water temperatures rapidly, setting the stage for a potentially early bloom season (see this article for further details on the factors contributing to HABs). We have started to see some surface streaking and “dots” in the water in isolated locations. However, overall, most sections of the lake do not have visual indications of algae that are concerning at this time. But it is important to keep in mind that conditions can change quickly.

Based on the secchi disk measurements taken by both volunteers and staff, our overall water clarity is about 6 meters - which is slightly above average for this time of year. However, we have seen a reduction in water clarity from a couple weeks ago.

Please use your visual indicators to look for signs of a HAB- lots of dots in the water, surface streaking, pea soup like conditions- before you, a family member or pets enter the water. If you have questions or suspect a HAB- please email:

We are thrilled to have 41 volunteers assisting with the Shoreline Harmful Algae Bloom Monitoring Program this season. The information collected through this program, in conjunction with the data submitted from our 21 volunteers performing weekly secchi disk readings around the lake, is incredibly helpful in assessing overall lake-wide conditions. The reports coming in (often daily!) are reviewed by watershed staff and HABs program team leaders and help inform our members and the general public with water quality updates. We will be aiming to send you routine weekly updates each Friday. Stay tuned!

Please check out the below resources for more information on harmful algae blooms.


Kevin Olvany

Watershed Manager, Canandaigua Lake Watershed Council

Lindsay McMillan

Association Director, Canandaigua Lake Watershed Association

More Information on Blue Green Algae

Click below for our Harmful Algae Bloom brochure.

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