Monday August 18, 2025 Honeoye Lake Water Quality
- Terry Gronwall
- 3 days ago
- 3 min read
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Monday August 18, 2025 Honeoye Lake Water Quality
Surface Water Temperature: ~78.4 F
Water Clarity: ~5.0 Feet
Lake Level: 802.9 Feet above sea level
Observations: Monday (8/18/25), Water clarity was ~5.0 feet the about 0.6 feet less
than last week. The surface water temperature was ~78.4 F about 0.7 F more than last week. It was sunny with a light wind today. A beautiful day to be out on Honeoye Lake!
We were able to check several open water and near shore locations today for blue-green algae blooms. We found a lot of blue-green algae in the water column, but did not see any blue-green algae surface scum at any of these sites. However, last Saturday we had several isolated near shore blue-green algae blooms reported to us. See picture on the left. Therefore, we expect that there could be surface blue-green algae blooms at isolated near shore locations around the lake given the amount of blue-green algae in the water column. There were five blue-green algae blooms on Honeoye Lake reported to the DEC HABs alert map between 8/11-8/17. Since Honeoye Lake has ~10 miles of shoreline your most accurate source of blue-green algae blooms is the crowd source bloom data found on the DEC HABs alert map (NYHABS).
Anabaena (Dolchospermum) (looks like a spring or chain of beads), Aphanizomenon (looks like a leaf), Limnoraphis (looks like a rod), and Microsystis (looks like a group of small round cells) are the current dominant blue-green algae species. See picture on the left. You should be watchful for Microcystis, Anabaena, Aphanizomenon, and Limnoraphis blooms lake wide. These are all blue-green (cyanobacteria) algae species. We expect to see blue-green algae blooms continue over the next few weeks particularly when we have 80-90 F days with calm winds. More information on blue-green algae can be found at: https://www.honeoyelakewatershed.org/habs
Several research studies have found that most of the phosphorus that fuels Honeoye Lake’s blue-green algae blooms is released from the lake bottom sediments when the lake’s dissolved oxygen level goes below 0.5 mg/L in the deeper parts of the lake breaking the phosphors/iron bond in the bottom sediments releasing phosphorus into the water column. The dissolved oxygen (DO) level near the lake bottom at ~7.0 m (~23.1 feet) was 0.42 mg/L and at ~9 m (~30 feet) was 0.16 mg/L today. This means that phosphorus is currently being released from the deep bottom sediments into the deepest part of the lake water. When we have a complete lake mixing event the deep lake water, with excessive amounts of phosphorus, will be mixed into the whole water column potentially fueling a blue-green algae bloom. Lake was stratified (i.e. had a thermocline) at ~7 m (~23.1 feet) deep. See temperature and DO graphs to the left.
We have been having regular seiche (internal wave) activity over the month. You can see that most dramatically on the above 6 m dissolved oxygen graph but is also occurring at deeper depths to a lesser degree. The seiche activity is rapidly warming the deeper water temperature.
The water temperature differential between the surface and 9 m (30 feet) is starting to decrease. As this water temperature differential decreases the lake’s resistance to mixing decreases. This trend should continue as we get cooler weather in a few weeks. Therefore, we expect that the lake should have a complete mixing event later in August or early September.
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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2025 Honeoye Lake Fishery Update
Pete Austerman
Aquatic Biologist
NYSDEC Region 8 Fisheries
Click on the link below:
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Click on the link below to see the Honeoye Lake Watershed Task Force 2025 Winter Newsletter:
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All operators of motorized vessels, regardless of age, will need a boating safety certificate by January 1, 2025.
Click on the link below for more information on how to get a NYS Safe Boating certificate:
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Click on the link below to see the Honeoye Lake Watershed Stormwater Toolkit:
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