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  • Terry Gronwall

Monday August 23rd, 2021 Honeoye Lake Water Quality Update

Surface Water Temperature: 78.3 F

Water Clarity: 6.2 Feet

Lake Level: 804.1 Feet above sea level

Lake Level Relative to Weir: +0.7 Feet

Observations: Monday (8/23/21), The water clarity has decreased ~1.7 feet over the last week to 6.2 feet and the surface water temperature has increased 1.3 F since last Monday (8/16/21) at 78.3 Fahrenheit. There was Anabaena, Microcystis, Lyngbya visible in the water column in most areas of the lake this morning. There was surface streaking in some locations. The Southern Lake Basin seemed to have a heavier bloom than the Northern Lake Basin. The lake is currently experiencing a significant blue-green algae bloom. We received several reports of isolated intense near shore blue-green algae blooms with surface scum yesterday (Sunday 8/22). See today’s open water picture and yesterday's bloom picture near our dock below:

We took the image to the left of today’s Anabaena (looks like a coiled wire), Microcystis (looks like a blob of cells), Lyngbya (long straight filaments) algae samples to the left using a high-powered microscope. You can Google Anabaena, Microcystis, Lyngbya to learn more about these cyanobacteria. Today was the first time this summer that we found Lyngbya. For more information on Anabaena and Microcystis see the articles at HARMFUL ALGAL BLOOMS | Honeoye Lake (

The DEC recommends that you, your family, and pets avoid contact with water that contains blue-green algae bloom like Anabaena, Microcystis, Lyngbya. Everyone should be very careful to watch for blue-green algae blooms for the next few weeks.

The lake mixed down to 8 m on Thursday August 19th due to the wind (~20 MPH) and rain storm (~2 inches) that occurred then. This brought both external run-off from the lake’s watershed carrying nutrients into the lake and when the lake mixed it mixed some bottom water with phosphorus and ammonia released from the bottom sediments into the whole water column. This is what fueled our Anabaena, Microcystis, and Lyngbya bloom starting late last week and last weekend. The lake has now restratified again which will cause legacy phosphorus to be released from a significant area of the bottom sediments all over again.

When a lake stratifies and forms a thermocline the decaying organic matter, dead algae and weed fragments, on the lake bottom consumes dissolved oxygen (DO) in the water below the thermocline. When the DO has been completely consumed the phosphorus iron bond in the bottom sediments becomes weak releasing legacy phosphorus into the water near the bottom sediments. Surface water temperature 78.3 F. Bottom water temperature 72.8 F.

Always use your own visual assessment before making contact with the lake water at this time of year as the blue-green algae situation can change daily if not hourly. Please regularly check the DEC HABs alert map for more detailed updates on Honeoye Lake HABs alerts:

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- Click on this link to see the new HLWTF Honeoye Lake Watershed Storm Water Took Kit if you are planning any storm water projects on your property:

- Click on this link for "2021 Honeoye Lake Aeration Engineering Planning Project"

- Click on this link for HLWTF Winter newsletter: e6fc30_ef8d01223f42408ba11b3a7a5f83bebe.pdf

- Click on this link for "2020 Water Quality: What, Why, What's Next"

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1 Comment

Aug 25, 2021

Hi Terry,

I am part of a lake association with similar issues as yours. Would you kindly call (978-621-1752) or email me ( - Dr. Karen Haswell

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