Monday August 10, 2026 Honeoye Lake Water Quality

Terry Gronwall
8 hours ago
3 min read

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The lake had a partial mixing event late last week causing an increase in blue-green algae in the upper water column.

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Surface Water Temperature: ~78.1 F

Water Clarity: ~8.3 Feet

Lake Level: 803.0 Feet above sea level

Lake level is a little below weir level. Evaporation will lower the lake level 0.1 to 0.4 inches per day from this level unless we get more rain soon.

Observations: Monday (8/10/26), Water clarity was ~8.3 feet an increase of about 1.7 feet over the last week. Today’s water clarity was ~2.6 feet higher than it was on August 11 2025. The surface water temperature was ~78.1 F about a 2.0 F increase over the last week. The lake had a partial mixing event late last week causing an increase in blue-green algae in the upper water column. This morning had an overcast sky with a light south wind.

There have only been 10 Honeoye Lake near shore blue-green blooms reported to the DEC NYHABS site since June 29. There has not been a new blue-green algae bloom reported to the DEC NYHABS site since June 20^th. See the Honeoye Lake DEC NYHABS Honeoye Lake map below:

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:

https://experience.arcgis.com/experience/e5dec19912454731a308bbb7af605fb3/

We found “increasing” amounts of Anabaena (Dolchospermum) (looks like a spring or chain of beads), Microcystis (looks like a group of small round cells), Limnoraphis (looks like a rod), and Aphanizomenon (looks like a leaf) again today. See algae images on the left and below: You should be watchful for Anabaena, Microcystis, Limnoraphis, and Aphanizomenon blooms, all cyanobacteria species, lake wide over the next few weeks particularly when we have 80-90 F days with calm winds. More information on Gloeotrichia and Anabaena which are cyanobacteria can be found at: https://www.honeoyelakewatershed.org/habs

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 0.5 mg/L in the deeper parts of the lake breaking the phosphors/iron bond in the bottom sediments releasing phosphorus into the water column. The dissolved oxygen (DO) level near the lake bottom at ~9.0 m (~30 feet) was 1.88 mg/L today. This means that no additional phosphorus should be released from the lake’s bottom sediments at this time. Today’s temperature and dissolved oxygen graphs are posted on the left.

The lake had a partial mixing event late last week increasing the amount of blue-green algae in the upper water column. You can see the partial mixing event in the above temperature and dissolved oxygen profile graphs. However, the temperature and dissolved oxygen did not become completely uniform from top to bottom of the water column like it does when the lake has a complete mixing (turnover) event.

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