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  • Terry Gronwall

Monday September 6th 2021 Honeoye Lake Water Quality

Updated: Sep 7, 2021

Surface Water Temperature: 74.5 F

Water Clarity: 5.5 Feet

Lake Level: 803.5 Feet above sea level

Lake Level Relative to Weir: +0.0 Feet

Observations: Monday (9/6/21), The water clarity has decreased ~1 foot to 5.5 feet and the surface water temperature has decreased ~4 F to 74.5 F over the last week. There was Anabaena, Microcystis, and Melosire (a diatom) visible in the water column. The lake mixed again over the weekend bringing nutrients released from the bottom sediments to the surface potentially fueling a continuation of our blue-green algae bloom later this week. We only saw blue-green algae surface scum in a few isolated near shore areas. It was a very nice day to be out on Honeoye Lake (picture to left), but open water still had a lot of blue-green algae visible in it (picture below):

We took the images below of today’s Anabaena (looks like a coiled spring), Microcytes (looks like a blob of cells), Melosire (long straight yellow cellular structure) algae samples using a high-powered microscope. You can Google Anabaena, Microcystis, and Melosire to learn more about them. Today was the first time this summer that we found Melosire. 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.

The lake mixed again over the weekend (9/4 & 9/5). You can see the lake mixing event on our temperature and dissolved oxygen charts to the left. The temperature and dissolved oxygen at every depth becomes uniform and the lines on the graph converge. When the lake mixed it mixed some bottom water with phosphorus and ammonia released from the bottom sediments into the whole water column. This may potentially fuel a continuation of our blue-green algae bloom later this week. However, the cooler fall weather we are having could reduce its impact. Surface water temperature 74.5 F. Bottom water temperature 73.4 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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