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  • Terry Gronwall

Monday August 28th, 2023 Honeoye Lake Water Quality

Updated: Aug 28, 2023

Surface Water Temperature: ~73.8 F

Water Clarity: ~4.0 Feet

Lake Level: ~802.9 Feet above sea level

Observations: Monday (8/28/23), Over the last week the water clarity increased slightly by ~0.7 feet to ~4.0 feet and the surface water temperature decreased only by ~0.2 F to ~73.8 F. The lake appears to be in its fall cooling pattern all ready. We found a blue-green algae bloom of varying intensity from light to heavy lake wide today. In some locations we found a blue-green algae surface scum. The blue-green algae bloom was heaviest usually with surface scum in the Southern Lake Basin. Blooms, some of which may be severe, could be occurring at other isolated near shore locations around the lake. DEC advice is “HABs: Know it, Avoid it, Report it”

We found Anabaena (Dolchospermum) (Looks like a spring), Aphanizomenom (Looks like a leaf), Microcystis (Looks like a big blob with small cells), and Planktothrix (looks like a small rod). These are all blue-green algae species. You should be watchful for blue-green algae blooms lake wide. Expect to continue to see blue-green blooms over the next few weeks. See pictures below: More information on Microcystis and Anabaena can be found at:

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 0.50 mg/L in the deeper parts of the lake. The dissolved oxygen level in deep water was below 0.5 mg/L for all of July and the first half of August. The dissolved oxygen (DO) level near the lake bottom today between 8-9 m (~26.5-30 feet) was 6.79-4.13 mg/L due to our first complete lake mixing event last week. This level of dissolved oxygen will keep the phosphorus bond to iron until the dissolved oxygen goes below 0.5 mg/L again when the lake restratifies. Lake was not stratified today but is starting to restratify again. You can see that on the above dissolved oxygen chart. Today's temperature and dissolved oxygen graphs are posted on the left. You can see that the lake has had a complete lake mixing event over the last week on the above temperature and dissolved oxygen charts with both the temperature and dissolved oxygen lines converging together to become almost uniform temperature and dissolved oxygen wise at all water depths. This would have mixed whatever amount of phosphorus was released from the bottom sediments with the whole vertical water column. This must have been enough phosphorus, even with the benefit of the DEC’s Alum Treatment last November, to fuel our current blue-green algae blooms at least partially. We are not sure yet if this is the only source of phosphorus fueling are current blue-green algae blooms or not. Other sources of phosphorus are rain storm run-off, Zebra mussel waste products, etc. Please report any Honeoye Lake HABs you observe to us and DEC by submitting a HABs report at:

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:


August FLCC Muller Field Station Events

Click on the link below to see the July Muller Field Station Newsletter:


New York Safe Boating Class Certificate will be required of all boaters on this schedule:

If born on or after: You will need boating safety certificate to operate motorized vessel in:

January 1, 1988 2022

January 1, 1983 2023

January 1, 1978 2024

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 and the schedule of local NYS Safe Boating classes:


Honeoye lake is included in the DEC's Big Panfish Study. Please click on the link below to read their Interim report:


Please visit the Honeoye DEC Project website for more information on the Honeoye Lake Nutrient Inactivation (Alum Treatment) Project: Honeoye Lake Nutrient Inactivant Pilot Study (


Glacial History of Honeoye Lake

Please check out the new “Glacial History of Honeoye Lake” sign at Sandy Bottom Park.

Thank you to Dr. Bruce Gilman for the content, the Ontario County Water Resources Council for the funding, and the Finger Lakes Land Trust for the imagery.

More information on Honeoye Lake’s Geology History can be found on HLWTF web site:


Ontario County Soil & Water Conservation District featured two Honeoye Lake watershed erosion control projects in their Summer 2023 Newsletter:


Please click on this link for the Winter 2023 HLWTF Newsletter:


- 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 the blue outlined box that says "Log in / Sign up" in the upper right-hand corner of this page to sign-up to be notified when we update our weekly Honeoye Lake water quality blog.


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