As a nature lover, I always say it’s better to be safe than sorry. It’s important to know about new outdoor threats to ensure you’re protected from them, like in the case of dangerous ticks in the Cleveland area. But there’s another annual threat that’s worth keeping on your radar… each summer, watch out for blue-green algae in Cleveland. This potentially harmful bloom can impact the health of your dogs, kids, and even you if you’re exposed. Here’s what you need to know:

Blue-green algae, or cyanobacteria, is oddly kind of beautiful.
Mapbox/Flickr
Though it's deadly, this toxic is almost like a watercolor painting when seen from space. This startling juxtaposition is so often seen in deadly things in nature, like flowers and even poison dart frogs. But like those two harbingers of death, you'll want to stay far away from cyanobacteria.
Blue-green algae blooms at a startling pace in the summer months, and it has been spotted in small inland lakes and the Great Lakes alike.
NOAA Great Lakes Environmental Research/Flickr
Known as harmful algal blooms, the presence of blue-green algae can impact the health of fish, indigenous animals, and even people during algal bloom season. This spans from July to October, and it seems like it's happening earlier and earlier nowadays... in 2023, algal blooms were identified in Lake Erie on July 4, which was a the second-earliest bloom date ever recorded.
As blue-green algae can move with the wind and currents, they can spread and change throughout the warmer months.
NASA Goddard Space Flight Center/Flickr
Since 2019, an algal bloom has been expected in Western Lake Erie, near the Sandusky area. With the right conditions, this toxin can sweep across Lake Erie and into Cleveland area waters.
While it's harmful to humans and ecosystems, this type of toxin is especially dangerous to water-loving pets.
Andrew Bone/Flickr
In humans, the effects of blue-green algae aren't great. Exposure can result in flu-like symptoms or rashes, but it's much worse if ingested by dogs. It can kill a pup within 20 to 30 minutes, so a visit to the vet should be a priority if you think your four-legged friend was exposed.
Before letting your dog dive into local bodies of water, look for signs of blue-green algae.
Derell Licht/Flickr
Oftentimes, it's hard to see blue-green algae in the water. A quick Google search can warn you about impacted areas, but blooms can pop up before water authorities realize and report on it. Residue like the blue patch pictured here can wash up on shore, and it's a tell-tale sign of an algal bloom. Even this residue should be avoided, as it's potentially toxic.
While blue-green algae is inevitable, to a degree, local authorities are taking steps to fight it.
Tim Evanson/Flickr
H2Ohio is a newer water quality initiative that's fighting harmful algal blooms in the state. This initiative educates and helps farmers to reduce phosphorus runoff from fertilizer, as this type of contamination is a primary cause of Lake Erie blooms. By incentivizing fertilizer runoff management, this program has already been making an impact since its implementation in 2019.
But even with management programs in place, we've got a ways to go before this threat is fully eliminated.
CSIRO/Wikimedia Commons
You'll want to keep an eye out for advisories from the Ohio EPA to keep a pulse on which waterways should be avoided. Lake Erie is an annual contender you'll want to keep an eye on, but inland waters like Chippewa Lake can be impacted, too.
So if you're planning to head out and make a splash with Fido, make sure to check local advisories before you head out.
Maja Dumat/Flickr
Watch for signs of contamination, too, and don't let your dog drink lake water. This is a good practice to adopt in general, as there are other types of pollution that can make your pet sick.
With management programs in place, blue-green algae will become less common in Ohio.
European Space Agency/Flickr
For now, however, it's something to keep on your radar. This type of algae is a health threat, and it is absolutely one you'll want to stay away from. Avoid infected waters, and don't touch any suspicious blue or green residue on the lake shore if you spot it.
While it's important to know about this type of danger, don't let it stop you from enjoying all that the local landscape has to offer.
Erik Drost/Flickr
Blue-green algae is beautiful, but it's potentially deadly. As long as you check local water alerts and keep an eye out for signs of contamination, you're all set to make a splash this summer and every summer.

Each summer, remember to keep your eyes peeled for signs of blue-green algae in Cleveland when you’re out swimming. From small inland lakes to the Great Lakes, this threat is everywhere… and it’s one you’ll want to keep on your radar!

Wondering where you and your pup can enjoy the great outdoors together? Check out our list of dog-friendly places in Cleveland to get out and get some sunshine with your four-legged friends.

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