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  • Terry Gronwall

Monday June 21st, 2021 Honeoye Lake Water Quality

Updated: Jun 22, 2021

Tuesday 6/22 - We took at Temperature & Dissolved Oxygen Profile today. The lake mixed down to ~20 feet, but did not disturb the thermocline at 23 feet. This means that the legacy phosphorus released from the bottom sediments over the last couple weeks is still being held below the thermocline.

We down loaded the weather station data today too. We had maximum wind speeds of 26-27 MPH yesterday (Monday 6/21) morning. Wind speeds above 20-25 MPH usually completely mix the lake.


Surface Water Temperature: 75.9 F

Water Clarity: 15.5 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 decreased by ~3.2 feet over the last week to 15.5 feet and the surface water temperature has decreased 0.2 degrees Fahrenheit to 75.9 Fahrenheit. There was no visible blue-green algae in the water column this morning. However, with the rapidly increasing surface water temperature everyone should be very careful to watch for blue-green algae blooms.

Our early morning thunder storm today (Monday 6/21/21) combined with 15 MPH winds gutsing to 20 MPH contributed to the drop in water clarity. We were not able to take a Temperature and Dissolved Oxygen profile this morning due to the high winds. We will take one tomorrow (Tuesday) or Wednesday to see if the storm combined with the high winds caused a complete lake mixing event or not. Please check back Tuesday or Wednesday for a mid-week update.

The lake was stratified at ~16 feet last week. The dissolved oxygen level below 26 feet is now close to zero which is low enough to weaken the phosphorus iron bond releasing Phosphorus 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 phosphorous iron bond in the bottom sediments becomes weak releasing legacy phosphorus into the water near the bottom sediments. Then when there is a lake mixing event this bottom water containing excessive amounts of phosphorus is mixed with the whole water column fueling a blue-green algae bloom.

Finally, the NYSDEC stocked ~40,000 walleye fingerlings in Honeoye Lake last Wednesday 3/16/21 and has stocked ~130,000 over the last 4 years to encourage a larger adult walleye population. Based on fisherman reports the number of adult walleyes has significantly increased. We are currently investigating if this increase in adult walleye population is causing a top-down

food web effect. The hypothesis we plan to investigate next summer is that an increase in the adult walleye population might reduce the prey fish population which in turn might increase the zooplankton population. Since zooplankton feed on algae this could be a factor in our lower levels of algae in 2019-2020.

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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