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August 14, 2020 update

Based on samples collected this week along with visual inspections of the open water and shoreline areas by staff and volunteers, the vast majority of the lake remains well below the DEC threshold of a Harmful Algae Bloom (HAB). However, we are continuing to have a few reports from around the 36 miles of shoreline of isolated blooms. This week’s results from the shoreline volunteers are showing that 26 out of the 31 reports are indicating non-bloom conditions along the shoreline. We have also had numerous calls and emails from residents indicating potential bloom conditions along their shoreline area. Therefore, the basic message, “use your visual indicators before entering the water” needs to be followed closely. Our water clarity has on average dropped by another 0.5 meters this week, with our typical measurement around 4.0 meters using a secchi disk. During the height of the blooms last year we were around 2.75 meters of clarity- so we are not that far away from reaching that level.

As you may have heard, Kershaw Beach was closed yesterday by the State Department of Health. This was done out of a very strict abundance of caution. Samples were collected at the beach yesterday morning by watershed staff and run through the Finger Lakes Institute Fluoroprobe to determine the levels and types of algae. There were a mixture of algae types with very low concentrations of blue green algae (1.1 and 1.6 ug/L when the DEC bloom threshold is 25ug/L). The DOH requires 24 hours before they test for the potential toxin that is associated with Blue Green Algae. The beach continues to look clear this morning and a microcystin toxin test will be collected today by DOH and analyzed over the weekend. Stay tuned to the City’s website for an update as to when the beach will reopen. The kayak launch areas at Kershaw Park have been reopened this morning.

As we head into the weekend, the forecast is calling for sunny, warm weather. This means that conditions for HAB development can occur quickly. Please continue to 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:


Kevin Olvany

Watershed Program 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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