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Water Quality Update for July 31, 2020

As we head into the weekend, we wanted to share an update on the conditions we have been seeing over the past week.

The vast majority of the lake continues to be free of any Harmful Algae Blooms (HABs). Our lake researcher from Finger Lakes Community College, Patty Thompson completed her monthly sampling of the lake yesterday and saw no surface concentrations of algae in the lake and had low chlorophyll-a levels (indirect measurement of algae) at each of the six locations sampled. The Watershed Manager was also on the lake Thursday afternoon/evening and saw no concentrations of algae at the surface. Water clarity as measured by the use of secchi disk was in the 6.0-6.5-meter range. In addition, numerous shoreline visits by the Watershed Manager showed clear conditions in most locations.

However, our Watershed Manager and volunteers did see a few isolated small shoreline blooms yesterday (see picture) in the northeast section of the lake along with some light streaking of algae just off of the shoreline. Typically, we see a HAB form in coves where a gentle wind can concentrate the HAB at the shoreline edge. The picture from yesterday shows only a few feet of bloom conditions and then the water is clear just past it. The issue is if humans, especially kids are playing in this shoreline zone- the HAB can be a real health issue for the person. Dogs can be especially impacted by these areas as well. They will typically drink water at the shoreline and play within this zone. The HAB collects on their fur which concentrates it and then when the dog licks its fur it can get a heavy dose of the HAB.

Overall, our secchi disk readings have been in line with what we would expect this time of year – in fact, the weekly average is up about a half meter from this week in 2019 - with no significant sudden decreases in clarity. However, we know based on our monitoring program that there is blue green algae in the water and if conditions are right it can concentrate into blooms.

The takeaway: this is the time of year where you need to look before you leap. Its impossible to predict where blooms may pop up, so it’s best to pay close attention to the appearance of water before recreating in the lake. For more information on keeping pets safe during bloom season, we have linked a webinar put on by Penn State Extension in the below list of resources.

Our Shoreline HAB Monitors will begin with their routine weekly surveys on Monday, August 3rd, so next week’s Water Quality update will feature and interactive map of all the weekly reports that came in.

As always, please continue 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 Manager, Canandaigua Lake Watershed Council

Lindsay McMillan

CLWA Association Director

More Information on Blue Green Algae

Click below for our Harmful Algae Bloom brochure.

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