Sunday August 31, 2025 Honeoye Lake Water Quality
- Terry Gronwall
- Aug 31
- 3 min read
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Sunday August 31, 2025 Honeoye Lake Water Quality
Surface Water Temperature: ~72.0 F
Water Clarity: ~5.0 Feet
Lake Level: 802.9 Feet above sea level
Observations: Sunday (8/31/25), Water clarity was ~5.0 feet about 2.9 feet less
than last week. The decrease was due to an increase in algae in the water column. The surface water temperature was ~72.0 F about 2.5 F less than last week due to the cooler fall like weather we have been having. The lake experienced a complete mixing event mid-last week causing widespread blue-green algae blooms. It was partly cloudy with a light wind today. A beautiful day to be out on Honeoye Lake!
Today we checked several near shore and open water locations for blue-green algae. We found heavy concentrations of blue-green algae at most locations and blue-green algae surface blooms at about 50% of the locations we checked lake wide. See pictures on the left: Therefore, we expect that there will be surface blue-green algae blooms at isolated near shore
and open water locations around the lake given the amount of blue-green algae in the water column for the next few weeks. There were 9 blue-green algae blooms on Honeoye Lake reported to the NYS DEC HABs alert map, dark blue circle, over the last two weeks. We expect that there will be an increase of blue-green algae blooms reported to the NYS DEC HABs Alert map this coming week. The light blue circles are blue-green algae blooms reported to the DEC more than two weeks ago. See NYS DEC HABs alert map below: 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 ~9 m (~30 feet) was 5.55 mg/L today. This means that phosphorus is not currently being released from the deep bottom sediments into the deepest part of the lake water. We had a complete lake mixing event mid-last week that mixed the deep lake water, with excessive amounts of phosphorus, with the whole water column fueling the blue-green algae bloom the lake has been experiencing over the last few days. Lake was not stratified today but has started the process to stratify again soon. See temperature and DO graphs to the left.
You can see the complete lake mixing event on the above Temperature and Dissolved Oxygen graphs where the 0-9 m lines have converged to the same level mid-last week. This is why we had an increase in blue-green algae blooms over the last few days. We are likely to keep experiencing blue-green algae blooms for the next serval weeks.
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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