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  • Terry Gronwall

Sunday July 30th, 2023 Honeoye Lake Water Quality

Surface Water Temperature: ~77.4 F

Water Clarity: ~7.9 Feet

Lake Level: ~803.7 Feet above sea level

Lake level relative to long term average lake level: +0.2 Feet

Observations: Sunday (7/30/23), Over the last week the water clarity decreased by ~3.6 feet to ~7.9 feet and the surface water temperature decreased by ~0.5 F to ~77.9 F. Lake level has dropped ~0.2 feet (~2.4 inches) over the last week due to the Town of Richmond’s emergency project to remove shale from the outlet creek. The drop in water clarity was due to a partial mixing event caused by 18-19 MPH winds last Thursday. This mixing event mixed some amount of phosphorus released from the bottom sediments over the last few weeks with the whole vertical water column providing fuel to increase the amount of algae in the water column. We received a report of an isolated blue-green algae bloom with surface scum along the North shore yesterday. Blooms could be occurring at other isolated locations around the lake.

We did not find any Gloeotrichia today. This was expected as Gloeotrichia usually disappears in late July. We also found increasing amounts of Anabaena (Dolchospermum) (Looks like a spring). Anabaena usually shows up in mid-July. So, it is right on time. We also found Aphanizomenom (Looks like a leaf) 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 Gloeotrichia and Anabaena can be found at:

We also found Asterinella (Star shaped pattern which is hard to see in our above image) and Ceratiumnin (Looks like a small space ship) in the image with the Aphanizomenom leaf like algae above. These are not blue-green algae species. You can Google these names for more information.

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 7.5-9 m (~25-30 feet) was only 0.43-0.33 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 at ~7 m (~23 feet) deep today. Today’s temperature and dissolved oxygen graphs are posted on the left. You can see last Thursday’s partial lake mixing event on the above temperature and dissolved oxygen chart above with the 7-7.5 m blue lines converging with the more shallower depths last Thursday. This would have mixed whatever amount of phosphorus was released from the bottom sediments from 6-7.5 m with the whole vertical water column. This was enough phosphorus to increase the amount of algae in the water column reducing water clarity, but we have not had a major blue-green algae bloom yet. 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:


Town of Richmond has received an Emergency Permit from the New York State Department of Environmental Conservation (DEC).

This permit will allow the Town of Richmond to remove 2 Gravel bars in Honeoye Creek.

The Town of Richmond started removing the shale bars last week (week of July 24th). The lake level had been dropping less than 0.25 inch per day. From last Friday morning to last Saturday morning the lake level dropped ~1 inch. We will continue to monitor the lake level going forward.


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


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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