The Snake-Filled Lakes Of South Dakota You'll Want To Think Twice About Swimming In

Snakes — even when they're not venomous or monstrously huge (looking at you, anacondas!), many people are still afraid of them. According to a 2016 study published in medical journal Psychiatry Research, roughly half of the worldwide population experiences anxiety over snakes, and 2-3% of people could be diagnosed as having a true phobia of them. To be fair, there are valid reasons to be scared, as certain snakes can cause injuries and, in extreme situations, death.

Those who are snake-phobic should know that South Dakota is home to certain lakes that, unfortunately, have their fair share of these slithery creatures. A few of the state's snake-filled lakes that you'll want to think twice about swimming in or hanging out near include Lewis and Clark Lake, Sylvan Lake, Lake Francis Case, Sheridan Lake, and Stockade Lake. While not all the snakes in these lakes are venomous, some are. Curious to learn which ones live where? We'll break down which species are known to frequent each spot, so you can plan accordingly.

Originally formed in 1881 when a dam was built at Sunday Gulch, Sylvan Lake is located in Custer State Park, home to South Dakota's oldest and largest resort. Within the park, visitors can take part in outdoor activities like hiking, paddle boating, fishing, and rock climbing.

Despite all the natural beauty at Sylvan Lake (including its incredible surrounding rock formations), something not-so-friendly lurks here, too: venomous prairie rattlesnakes. While these guys usually stick to rocky and grassy spaces nearby, it's possible to find them in the water. For instance, as South Dakota radio station KXRB reported in 2022, a prairie rattlesnake approached and bit a South Dakota fisherman in a boat along the Missouri River in 2016. Though this incident did not occur at Sylvan Lake, you may still want to take extra precautions to avoid a surprise rattlesnake encounter while visiting this Custer State Park waterway.

A few ways to stay safe include walking carefully through brushy areas and not sticking your hands under rocks. The last thing you want to do is provoke one, since this can increase your chance of being bitten. Considering what happened to that fisherman, it's probably a good idea to stay aware while in the water, too!

Lewis and Clark Lake was named after the famous early-1800s expedition that traveled through — among other regions — the land now known as South Dakota. Did Lewis and Clark see snakes while there? Possibly! At the very least, they were probably concerned about them, since a member of their team was bitten by a snake during a portion of their journey through Kansas. 

An excellent place to visit during this breathtaking South Dakota byway road trip, Lewis and Clark Lake welcomes anglers, boaters, and even campers (thanks to four nearby campgrounds). Northern water snakes are known to live along the lake's shore and in the surrounding wetlands, while ring-necked snakes typically reside in damp local woodlands. The good news is that both species are not venomous and generally steer clear of humans. However, you should avoid disturbing them as best you can, as doing so could cause them to bite. Even if they're not venomous, snake bites usually aren't a fun time.

Another South Dakota spot where you could find a prairie rattlesnake lurking is Lake Francis Case. Located not far from Gregory, a tranquil city with rustic charm, the lake lies along the Missouri River in South Dakota's southeastern region. The area is known for lots of outdoor activities ranging from camping and picnicking, to fishing, swimming, bird-watching, hiking, and biking. 

To the west of Lake Francis Case is the Snake Creek Recreation Area. This roughly 700-acre landscape was another spot where Lewis and Clark stopped during their expedition, and it's currently where outdoor enthusiasts can enjoy South Dakota's stunning wilderness. However, it's also home to prairie rattlesnakes, which you might find hanging out in the bushes or on rocks by the shore. Unfortunately, these snakes thrive during summer, aka the busy travel and outdoor fun season. So, while visiting Lake Francis Case, be cautious and mindful of your surroundings to avoid these critters. 

If you are bitten by a prairie rattlesnake at either Lake Francis Case or Sylvan Lake — the two places on this list known to have this venomous species — immediately call 911 or get to a hospital. Seeking prompt medical care is important to avoid serious symptoms.

East of this hidden South Dakota Black Hills city with iconic and unlimited outdoor thrills, Stockade Lake is another Custer State Park destination. Situated close to the historic Gordon Stockade (where people first found gold in the Black Hills), this spot welcomes swimming along its beach and boating on the water. Families will also appreciate the nearby playground for kids.

While you might not find gold around Stockade Lake today, you could find snakes, specifically the Plains hognosed snake. This species gets its name from the snakes' upturned, pig-like snouts. While they typically reside in local sandy areas or woodland clearings, the good news is that they aren't considered venomous, so there's no immediate danger. In fact, Plains hognosed snakes don't often bite at all. That said, when they do bite, it can hurt. So, as with most wildlife, it's best to leave these animals be.

Sheridan Lake is located about 15 miles from Rapid City, an artsy South Dakota city between the Black Hills and Badlands. The lake could easily be considered an outdoor lover's dream, since it provides access to all kinds of adventures like swimming, hiking, fishing, camping, boating, birding, canoeing, mountain biking, and wildlife spotting.

Of course, one slice of wildlife you might not want to see here are the snakes. Eastern yellow-bellied racers and hognose snakes are known to live in surrounding meadows and near the shore. While the racers are non-venomous, hognoses are mildly venomous. As such, despite being relatively non-threatening to humans and pets, these creatures often aren't among the animals people are chomping at the bit to get up close and personal with. If you do happen to spot one out in the wild, leave it alone or let it move along. Like many other snakes, these guys may bite if they feel threatened, and though their bite isn't deadly, it could still be painful.