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  • Terry Gronwall

Monday July 10th, 2023 Honeoye Lake Water Quality

Updated: Jul 11, 2023

Surface Water Temperature: ~78.3 F

Water Clarity: ~11.2 Feet

Lake Level: ~804.0 Feet above sea level

Lake level relative to long term average lake level: +0.5 Feet

Observations: Monday (7/10/23), Over the last week the water clarity decreased by ~0.3 feet to ~11.2 feet and the surface water temperature increased by ~3.5 F to ~78.3 F. Lake level has risen to about 804.0 due to all the rain we have had recently. It was a very nice day to be out on the lake.

We got almost 1 inch of rain at our house late yesterday (Sunday) afternoon. However, Bristol and South Bristol must have gotten more rain because there was floating debris along the East shore. A lot of floating debris near Burns Point today. Be very careful if you venture out on the lake. See pictures below:

We found a Gloeotrichia bloom of varying intensities today both in near shore areas and open water. We also found sparce amounts of Anabaena (Dolchospermum) for the first time this summer too. Anabaena usually shows up in mid-July. So, it is right on time. You should be watchful for Gloeotrichia and Anabaena blooms lake wide. These are both blue-green algae species. Expect to continue to see Gloeotrichia and Anabaena blooms over the next few weeks. See pictures of Gloeotrichia on the left and Anabaena on the right below: More information on Gloeotrichia and Anabaena can be found at:

We did not expect the DEC Alum Treatment to reduce our traditional Gloeotrichia blooms starting in mid-June given that the Alum Treatment was in water depths 18 feet and deeper. When Gloeotrichia dies its seed goes to the lake bottom in shallow water. Then in the spring it acquires nutrients directly from the shallow water bottom sediments. Then blooms.

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 between 8-9 m (26.5-30 feet) was only 0.34-0.40 mg/L today. The DEC’s Alum Treatment last November should prevent the phosphorus from being released when the DO is less than 0.50 mg/L. We will all know how effective the Alum Treatment is by observing how severe a blue-green algae bloom we get when the lake mixes in a few weeks due to a strong wind. Lake was stratified today at ~5 m (~16.5 feet) deep today. See today's temperature and dissolved oxygen graphs above.

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:


July 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:


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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