6 days ago
Harmful algae blooms in Canandaigua Lake: What to expect in late summer
CANANDAIGUA, NY — A year ago June 20, Canandaigua Lake saw the earliest blue-green algae bloom ever recorded. The year before that, a bloom was recorded on June 22, but then not again until late July.
In 2022, a bloom wasn't recorded until Aug. 16, even though the year before a bloom was recorded on June 29.
This year, small and localized blooms were recorded on July 28, but no new blooms were recorded as of Aug. 8.
So unlike Halloween or Christmas, the arrival of harmful algae blooms, also known as HABs, is not something that can be pinpointed on the calendar (and it's becoming a yearly tradition, although unlike the holidays, it's not one lake users look forward to).
If one thing is certain, HABs will come, in Canandaigua Lake and the other Finger Lakes.
New Canandaigua Lake Watershed Association Executive Director Emily DeBolt explains what to expect in these last days of summer. Answers have been lightly edited.
Q: What are you expecting for Canandaigua Lake this year?
DeBolt: They are doing some really interesting work up on Lake Erie with harmful algae bloom forecasting models. It will be great if we will all be able to benefit from what they are learning up there.
In the meantime, it's really anyone's guess, unfortunately. The cold winter with more ice cover than usual could play into things. The water sure was colder than usual for a while early on, but by now the lake has caught up and is warm like usual. (The surface temperature as of Aug. 8 was recorded at 78 degrees Fahrenheit, down two degrees from the week prior, according to the Watershed Association's weekly water quality report.)
The large storm in June that brought lots of sediment and nutrient into the lake could have a hand in things.
But day to day it's largely dependent on the weather. Cayuga Lake had a large number of blooms early and then calmed down a bit. Now Seneca Lake has been having blooms.
We already had our first bloom reports of the season, but they were small and localized.
Q: What are the right conditions for blue-green algae in Canandaigua Lake?
DeBolt: A combination of factors allows the cyanobacteria to grow into blooms that can be harmful to human and animal health and degrade our water quality.
With climate change, we are seeing an increase in large storm events that overwhelm the land's capacity to slow and filter the water before it reaches the lake. These storm events bring pulses of sediments and nutrients into the lake, helping fuel excessive aquatic plant growth and algae blooms.
Also, the invasive dreissenid mussels (both quagga and zebra) have been altering our lake ecosystem and while they filter other algae out of the water, they leave the cyanobacteria that causes HABs behind. Those are all the underlying factors.
In short, hot, calm days create ideal conditions for harmful algal blooms. Light winds can also move the blooms around so — depending on the direction of the wind — one side of the lake or the other might see the worst blooms at any given time.
Q: Do you have more volunteers reporting Canandaigua Lake conditions this year?
DeBolt: We have an amazing 'army' of volunteers all over the lake reporting for us. I think we have 74 this year. We keep a map of what sections people are monitoring, so if someone is interested in monitoring a section of shoreline for us, they should reach out and we can let them know if we need someone in that area still.
Q: What should Canandaigua Lake users be on the lookout for?
DeBolt: Use visual cues to identify harmful algae blooms. They can appear like pea soup, spilled paint, globs or surface streaks. The color is typically green, blue-green or yellow, but can also potentially be brown, red or purple.
When in doubt, stay out!
Q: What should residents and Canandaigua Lake users be aware of and what can they do to help?
DeBolt: Lake users need to educate themselves about HABs so that they can safely and confidently enjoy the lake. Blooms can appear quickly in the lake when the conditions are just right.
Please use your visual indicators before recreating in the water and be sure to keep pets away from the water as well.
They can always reach out to us at HABS@ with a photo or HABs-related question.
We keep a detailed map of bloom locations on our website and info about HABs. The state Department of Environmental Conservation has resources as well about HABs identification and they keep the NYHABs map showing reported bloom locations for all of New York state.
The one thing we can all do is work to protect the lake is by reducing the amount of nutrients that get into it. Everyone has a part they can play.
So that means limiting the use of lawn fertilizers, planting native plants to help soak up stormwater before it becomes runoff, making sure their septic system is working properly (if they have one) and many more things.
We have resources on our website with all sorts of 'Lake Friendly Living' tips.
Q: What other ways are there to be informed about Canandaigua Lake conditions?
DeBolt: We also send out weekly water quality updates during the summer.
This is a great way to know what is going on in the lake currently and to get the latest up-to-date info about HABs.
If people don't receive these weekly emails, we encourage them to go on our website and sign up at
What is the Canandaigua Lake Watershed Association?
The community-based nonprofit organization is committed to preserving the water quality and ecological health of Canandaigua Lake and its surrounding watershed.
Through education, scientific research and advocacy for sound public policy, the Watershed Association engages the community to promote stewardship and protect Canandaigua Lake.
This organization is not to be confused with the Canandaigua Lake Watershed Council, which is made up of the 14 watershed and water-purveying municipalities that work together toward protecting the lake.
For more information or to get involved, visit or @CanandaiguaLakeWatershed on Instagram.
Mike Murphy covers Canandaigua and other communities in Ontario County and writes the Eat, Drink and Be Murphy food and drink column. Follow him on X at @MPN_MikeMurphy.
This article originally appeared on Rochester Democrat and Chronicle: Harmful algae blooms in Canandaigua Lake: What to expect in late summer
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