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  • Terry Gronwall

Monday August 30th 2021 Honeoye Lake Water Quality

Surface Water Temperature: 78.6 F

Water Clarity: 6.5 Feet

Lake Level: 803.6 Feet above sea level

Lake Level Relative to Weir: +0.1 Feet

Observations: Monday (8/30/21), The water clarity has increased ~0.3 feet over the last week to 6.5 feet and the surface water temperature has increased ~0.3 F since last Monday (8/23/21) at 78.6 Fahrenheit. There was Anabaena, Microcystis, Lyngbya visible in the water column. The lake is still experiencing a blue-green algae bloom. We only saw blue-green algae surface scum in a few isolated near shore areas. We didn’t see surface scum in open water. See today’s bloom picture near our dock on the left.

We took the images below of today’s Anabaena (looks like a coiled spring), Microcytes (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 and Microcystis. Everyone should be very careful to watch for blue-green algae blooms for the next few weeks.

We had a report of an isolated young-of-year perch and sunfish kill last weekend. However, we did not see any signs of new fish kills this morning at the over 12 near shore locations we checked for a blue-green algae bloom. A fish kill in shallow water can occur at night the when the dissolved oxygen is consumed by the decomposing dead algae in the water.

The lake mixed 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 about 10 days ago. The lake has now restratified at 7 m (~23 feet) again which will cause legacy phosphorus to be released from a significant area of the bottom sediments all over again which is being held below the thermocline at this time. Surface water temperature 78.6 F. Bottom water temperature 72.1 F.

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.

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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