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  • Terry Gronwall

Sunday October 8, 2023 Honeoye Lake Water Quality

Updated: Oct 9, 2023

Surface Water Temperature: ~65.7 F

Water Clarity: ~5.3 Feet

Lake Level: ~802.8 Feet above sea level

Observations: Sunday (10/8/23), Over the last week the water clarity increased by ~0.3 feet to ~5.3 feet and the surface water temperature decreased by ~2.8 F to ~65.7 F. Colder fall weather has returned the lake to its fall cooling pattern. We were only able to check open water and very limited near shore areas for a blue-green algae bloom today due to the stormy weather. We did still find blue-green algae present in the water column in open water. Blooms, some of which may be severe including surface scum, could still be occurring at any location around the whole 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 especially on hot, sunny, calm wind days. 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 (DO) level near the lake bottom today between 7-9 m (~23-30 feet) was 7.02-6.94 mg/L. The DO was high enough to keep the phosphorus in the bottom sediments bond to iron. Today’s temperature and dissolved oxygen graphs are posted on the left.

The lake has completely mixed again sometime in the last few days. It is now isothermal which means a uniform water temperature from the surface to the bottom. You can see that in the temperature graph above where the temperature lines from all depths have converged together. The dissolved oxygen lines have converged at all depths too. The lake should now resume its fall pattern of steadily dropping water temperature until ice on in late December. This should cause the blue-green algae to slowly dissipate over the next several weeks. 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:


October FLCC Muller Field Station Events

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

Click on the link below to register for the Muller Field Station open house on October 21st:


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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