Beware These 10 Dangerous Animals Found in Illinois’s Lakes and Rivers

Written by Crystal
Updated: July 6, 2023
© Eddie J. Rodriquez/
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Illinois has a total of 86,076 miles of rivers. But are they safe to swim in? The answer depends on where you’re taking a dip. The state offers a lot of fascinating swimming opportunities, but you have to know where to go and what animals to keep an eye out for. Follow along as we reveal the top dangerous animals in Illinois’s lakes and rivers.

dangerous animals in Illinois

Are Illinois’s Waterways Safe for Swimming?

Eldon Hazlet State Park Illinois
Some of Illinois’s waters are safe to swim in; others aren’t. Pictured is Lake Carlyle at Eldon Hazlet State Park, which doesn’t offer swimming, as the park has a public swimming pool.

©Jason Patrick Ross/

To swim or not to swim! It’s a question new visitors find themselves asking when learning about Illinois’s lakes and rivers. The answer isn’t a one-size-fits-all solution; you have to choose whether or not to swim based on locations, conditions, and other variables.

In other words, swimming in Illinois’s rivers can be dangerous. But people go swimming there all of the time! It’s all about knowing what to look out for and where it’s safe to take a dip.

Swimming Spots

Have you heard of Fox River? This spot has several parks and beaches along its path, making it a family-friendly location. Always check current conditions and regulations before taking a dip.

Here are a few more popular swimming spots that include Illinois’s lakes and rivers:

  1. Lake Michigan Beaches
  2. Lake Le-Aqua-Na State Park
  3. Centennial Beach
  4. Rend Lake
  5. Clinton Lake
  6. Carlyle Lake
  7. Chain O’Lakes State Park
  8. Kinkaid Lake
  9. Starved Rock State Park
  10. Illinois Beach State Park
  11. Silver Springs State Park
  12. Burden Falls in Shawnee National Forest
  13. Bell Smith Springs in Shawnee National Forest
  14. Kincaid Lake Spillway in Shawnee National Forest
  15. Independence Grove
  16. Fish Lake Beach Camping Resort
  17. Kayak Morris
  18. Three Oaks Recreation Area
  19. West Beach at Indiana Dunes National Park

You can even find spots to go scuba diving! The Swinging Bridge on the Illinois River is a popular scuba diving spot with deep water.

Swimming Safety Tips

After researching Illinois’s lakes and rivers to find a good spot to swim, go the extra mile by practicing these safety tips:

  • Talk to local authorities about safe swimming areas.
  • Enter water cautiously.
  • Dive only in designated areas.
  • Avoid swimming near storm drains, contaminated water, or strong currents.
  • Ensure children wear life vests.
  • Teach kids safe swimming techniques.
  • Keep a phone nearby for emergencies.
  • Be aware of your surroundings.

Now, let’s look at the creatures you might encounter swimming in and around Illinois’s lakes and rivers.

Dangerous Animals in and Around Illinois’s Lakes and Rivers

Here is a list of the most dangerous animals found in and around Illinois’s lakes and rivers:

  1. Kissing Bugs
  2. River Otters
  3. Coyotes
  4. Black Bears
  5. Scorpions
  6. Centipedes (that sting)
  7. Timber Rattlesnake
  8. Brown Recluse Spider
  9. Black Widow Spider
  10. Cougars

Kissing Bugs

Kissing Bug
The kissing bug can transmit Chagas disease through its feces.

©Henrik Larsson/

Kissing bugs are found crawling around Illinois’s lakes and rivers, and these bugs can transmit dangerous diseases. To prevent exposure, avoid sleeping in areas where these bugs are found, and use bug nets treated with insecticides.


Lithobius melanops
Centipedes deliver a painful bite similar to a bee sting.

©4,000 × 2,500 pixels, file size: 10.36 MB, MIME type: image/jpeg – License

How painful is a centipede bite? It depends on how hard they pinch you. Centipedes can pinch you with a pair of claws positioned behind their head. The good news is that their jaws are relatively weak and can rarely break human skin. If a bite does occur, individuals may experience swelling at the site and pain similar to a bee sting.

River Otters

Otter Teeth - Otter showing teeth
River otters can attack if threatened.

©Paul A Carpenter/

Why are river otters on this list? Because these creatures aren’t just cute, they’re powerful too. There’s proof that gangs of river otters can take on a crocodile and win. You definitely don’t want to get on their bad side.

River otters are defensive if threatened. They have super sharp teeth and incredibly strong jaws. Avoid disturbing the otters when swimming in Illinois’s lakes and rivers, no matter how cute they seem.


Coyote walks along the water
Look for coyotes searching Illinois’s lakes and rivers for food.

©Frank Fichtmueller/

Belonging to the canine family, coyotes pose a potential threat if they’re sick, injured, or used to being fed by people. They may also target pets and small livestock. Avoid feeding any wild animal and always maintain distance.

Black Bears

Black bear
If they feel threatened or they’re caring for cubs, black bears become defensive.

©Joshua Daniiel/

Black bears pose a risk if startled or caring for their young. There’s nothing quite like the rage of a Mama bear defending her cubs. Avoid a close encounter by being bear smart. Keep campsites clean and carry bear spray.


Parabuthus maximus commonly known as the Thick-tailed Scorpion.
Illinois doesn’t have a lot of scorpions, but some can be found hiding under rocks and in crevices.

©Lauren Suryanata/

Scorpions have a venomous sting that is used for hunting/defense. The world is full of all different sizes of scorpions ranging from itty bitty to humongous ones. Thankfully, Illinois is home to the smaller plains scorpion and the bark scorpion, both of which like to hide in rocks and crevices. Avoid direct contact, and check clothing in scorpion-infested areas.

Timber Rattlesnake

A Timber Rattlesnake striking prey
Timber rattlesnakes live throughout Illinois.

©Joe McDonald/

Watch out! Timber rattlesnakes are venomous and native to the eastern U.S. Wear protective clothing, like long pants and snake-proof boots while walking in their habitat. If you’re concerned about snakes living by your campsite, there are methods for repelling them. Bites are dangerous and need immediate medical attention.

Brown Recluse Spider

Mediterranean recluse spider, violin spider (Loxosceles rufescens), Brown recluse spider, in its wild habitat.
A brown recluse bite can cause severe tissue damage.


The brown recluse spider is highly venomous. You can identify them by violin-shaped markings. Bites can cause serious wounds, but sometimes they’re just uncomfortable. Here’s what a brown recluse spider bite looks like. Avoid disturbing them and always shake off your clothes after a hike.

Black Widow Spider

Animals with exosceleton black widow spider
The black widow will bite to defend itself, and their bite is highly venomous.


The infamous black widow spider has potent venom. This spider species is non-aggressive, but they will bite in self-defense. Be cautious in dark, secluded areas. Bites cause severe pain and require medical attention.


Cougars rarely attack people, but when they do, the results can be fatal.

© Viacheslav

Last on our list of dangerous animals around Illinois’s lakes and rivers, we have cougars. These wild cats usually leave people alone, but they pose a potential threat if sick or threatened. Attacks are rare but fatal. Hike in groups, and make noise.

Unsure whether you’re looking at a mountain lion or a cougar? Both big cats are basically the same species, with minor differences based on location.

Summary of 10 Dangerous Animals Found in Illinois’s Lakes and Rivers

NumberDangerous Animal
1Kissing Bugs
3River Otters
5Black Bears
7Timber Rattlesnake
8Brown Recluse Spider
9Black Widow Spider

The Featured Image

Looking down the Illinois River to the Lincoln Memorial Bridge. LaSalle, Illinois, U.S.A..
© Eddie J. Rodriquez/

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About the Author

Crystal is always looking to learn more, and share her finds with you along the way. It's amazing how you can spend your entire life living with plants and animals, but still know so little about them! Let's explore our world together as Crystal covers topics about creatures, places, and experiences.

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