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  • Terry Gronwall

Monday July 3rd, 2023 Honeoye Lake Water Quality

Surface Water Temperature: ~74.8 F

Water Clarity: ~11.5 Feet

Lake Level: ~803.8 Feet above sea level

Lake level relative to long term average lake level: +0.3 Feet

Observations: Monday (7/3/23), Over the last week the water clarity increased by ~0.3 feet to ~11.5 feet and the surface water temperature increased by ~0.1 F to ~74.8 F. Lake level has risen about 3-4 inches over the last 48 hours due to all the rain we have had.

We found a Gloeotrichia bloom of varying intensities today both in near shore areas and open water. We did not see any surface algae scum. However, because of the rain we were not able to check our normal Monday near shore locations for blue-green algae blooms. You should be watchful for Gloeotrichia blooms lake wide. Gloeotrichia is a blue-green algae. Expect to continue to see Gloeotrichia blooms over the next few weeks. See pictures below: More information on Gloeotrichia 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.

Curly Leaf Pond Weed, an early season aquatic plant, growing to the lake surface has almost completely died off naturally. It typically completely dies off by late June.

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 at ~9 m (~30 feet) was only 0.44 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 serve a blue-green algae bloom we get when the lake mixes in a few weeks due to a strong wind. Lake was stratified at ~6 m (~20 feet) deep. See temperature and DO graphs to the left.

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:


June FLCC Muller Field Station Events

Click on the link below to see the June 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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