Monday August 24, 2026 Honeoye Lake Water Quality

Terry Gronwall
4 hours ago
3 min read

Updated: 3 minutes ago

The lake had a partial mixing event about 2 weeks ago causing several isolated blue-green algae blooms between August 16-21 as reported to DEC NYHABS map. However, recently the lake had a complete mixing event (turnover).

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Surface Water Temperature: ~74.1 F

Water Clarity: ~6.3 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 (8/24/26), Water clarity was ~6.3 feet a decrease of about 0.3 feet over the last week due to an increase of visible algae in the upper water column and an overcast sky. Today’s water clarity was ~2.3 feet higher than it was on August 25 2025. The surface water temperature was ~74.1 F about a 3.3 F decrease over the last week. The lake had a partial mixing event about 2 weeks ago causing several isolated blue-green algae blooms between August 16-21 as reported to the DEC NYHABS map. However, recently the lake has experienced a complete mixing event (turnover). This morning had an overcast sky with a 5-7 MPH south wind.

There have been 18 Honeoye Lake near shore blue-green blooms reported to the DEC NYHABS site since June 29. There were 8 new blue-green algae bloom reported to the DEC NYHABS site between August 16-21 they are the dark blue circles. See the Honeoye Lake DEC NYHABS Honeoye Lake map below:

We are now in the peak blue-green algae bloom time period across all of the Finger Lakes. The dark blue circles are booms reported in the last two weeks. See Finger Lakes DEC NYHABS 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 an increased 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 m (30 feet) was 7.37 mg/L today. This means that additional phosphorus is not currently being 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 about 2 weeks ago causing several blue-green algae blooms with surface scum. You can see the partial mixing event in the above temperature and dissolved oxygen profile graphs around 8/10. However, sometime in the last few days the lake has experienced a complete mixing event (turnover). You can see that both the water temperature and dissolved oxygen graphs have converged in value from the top to the bottom of the water column. The lake probably will stratify again in a few days to a week or two.

I created the table below in response to a question I recently got asking when does Honeoye Lake usually have its first complete mixing event and what was the water temperature. The answer is sometime between late July and late August when the surface and deep-water temperature converge reducing the lake’s resistance to mixing. See the last 10 years of lake mixing data below: