Monday September 28, 2026, Honeoye Lake Water Quality

Terry Gronwall

25 minutes ago

3 min read

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This will be our last Honeoye Lake water quality blog update for the 2026 summer season. Hopefully, you found our water quality blog updates useful and informative. Please check for HLWTF blog updates periodically over the fall and winter for timely updates on fall color, ice in/out, Muller Field Station Newsletters, etc. Our water quality blog updates will start again in mid-May 2026.

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Monday September 28, 2026, Honeoye Lake Water Quality

Surface Water Temperature: ~66.4 F

Water Clarity: ~7.3 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 (9/28/26), Water clarity was ~7.3 feet the same as last week. Today’s water clarity was ~2.7 feet higher than it was on September 28 2025. The surface water temperature was ~66.4 F about a 4.3 F decrease over the last week. The lake is in a very typical September water quality pattern this year with surface water temperature rapidly dropping every week. This morning had an overcast sky with a light north wind.

At the end of November 2025, the DEC NYHABS site had 70 reports of Honeoye Lake HABS compared to 25 HABS reports as of September 28, 2026. There were no new lake wide blue-green algae bloom reported to the DEC NYHABS site over the last week. The last blue-green bloom we reported on 9/17 to the DEC NYHABS site is still dark blue in color. 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/

Today we visually found about the same 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) as last week. We also found a small amount of Ceratium (looks like a small space ship) which is not a blue-green species 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 sunny 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 phosphorus/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 7.89 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 is still isothermal meaning the water temperature is uniform from the surface to the bottom. The dissolved oxygen is well mixed too. Ranging from 8.34 mg/L at the surface to 7.89 mg/L near the bottom. The blue-green algae in the lake should gradually dissipate now that the water temperature is getting rapidly colder every week.

Be sure and watch for our 2027 Honeoye Lake Watershed Task Force Newsletter next winter which will have a State of the Lake article explaining why Honeoye Lake had such a low amount of HABS in 2026.

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