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  • Terry Gronwall

Monday June 28th 2021 Honeoye Lake Water Quality

Surface Water Temperature: 75.9 F

Water Clarity: 18.7 Feet

Lake Level: 803.1 Feet above sea level

Lake Level Relative to Weir: -0.4 Feet

Observations: Monday (6/21/21), The water clarity has increased by ~2 feet over the last week to 18.7 feet and the surface water temperature has decreased 1.8 degrees Fahrenheit to 74.1 Fahrenheit. There was very light Gloeotrichia, an early season blue-green algae species, visible in the water column in most areas of the lake this morning. For more information on Gloeotrichia see the articles at HARMFUL ALGAL BLOOMS | Honeoye Lake (

With the warm weather we are currently having surface water temperature could increase over the rest of the week creating conditions that may facilitate a blue-green algae bloom. Everyone should be very careful to watch for blue-green algae blooms.

Due to winds of 20-25 MPH with white caps last Thursday June 24th the lake mixed down to 8.5 m (~28 feet). This mixing event is confirmed by all the temperature and dissolved oxygen lines on the graph to the left converging to almost the same value last Friday 6/25.

Since the dissolved oxygen level below 26 feet had been close to zero (anoxic), which is low enough to weaken the phosphorus iron bond, phosphorus was released into the deep water. When a lake stratifies and forms a thermocline the decaying organic matter, dead algae and weed fragments, on the lake bottom consumes dissolved oxygen in the water below the thermocline. When the dissolved oxygen has been completely consumed the phosphorus iron bond in the bottom sediments becomes weak releasing legacy phosphorus into the water near the bottom sediments. Last week's lake mixing event would have mixed this bottom water containing excessive amounts of phosphorus with the whole water column providing fuel for a potential blue-green algae bloom. In this case only a small amount of bottom water had been anoxic limiting this impact. Today, June 28th, the lake has already started to restratify starting this cycle all over again.

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:

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.


- Click on this link for "2021 Honeoye Lake Aeration Engineering Planning Project"

- The NYSDEC has recently released a new report “Feasibility Assessment of Harmful Algal Bloom Management Options for Honeoye Lake and Conesus Lake” as a follow-up to their 2018 Honeoye and Conesus Lake HABs Action Plans. Click on the link SCIENTIFIC RESEARCH | Honeoye Lake ( to see report:

This report evaluates various techniques for mitigating Harmful Algae Blooms in Honeoye Lake by preventing the release of legacy phosphorus from the lake bottom sediments.

- Click on this link for HLWTF Winter newsletter: e6fc30_ef8d01223f42408ba11b3a7a5f83bebe.pdf

- Click on this link for "2020 Water Quality: What, Why, What's Next"

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