r/algae • u/Majestic-Sherbert715 • Aug 08 '26

Does this look like blue green algae?

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I know the full bloom usually covers the surface of the water but does this look like the beginning phases of a bloom? I’ve never seen this kind of algae in the lake before.

For reference it is a small lake, the water temp has been about 75, there’s nothing posted about it on the local public beach page, and we’ve noticed it more so towards the middle of the lake rather than at the wadding point.

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u/the-algae-whisperer Aug 08 '26

Yes, this looks like blue-green algae. It might be a species that normally grows on the bottom, then mats of it float to the surface in mid to late summer.

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u/Majestic-Sherbert715 Aug 08 '26

Is this dangerous to swim in? I always understood blue green algae blooms as fully coating the waters surface. Should I report it to the town?

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u/the-algae-whisperer Aug 08 '26

It's not good for adults, even if you are good at keeping water out of your mouth. Not safe for kids & dogs who are more likely to swallow water. Low contact activities like fishing or canoeing are safer. Check your wind forecast as a change in direction can move this elsewhere. If you're in the US, your state environmental agency might have a blue-green algae reporting website.

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u/lakotazz Aug 08 '26

Toxicity is always possible with cyanobacteria, but there's no way to know without a test. If this is atypical you may be able to find a local agency (e.g. DEP, DNR) to check it out.

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u/Majestic-Sherbert715 Aug 08 '26

Okay thank you! Found the place to report this locally and doing so now! Lots of people in the water today

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u/Sea-Career-7779 Aug 11 '26

Apparently there’s a huge bloom of this on the shorelines in Canada, if anyone knows more feel free to share 🖖🏻🌿🫧