Feb 23, 2026
3 min read
Not all lakes are safe for swimming, and it's worth learning the warning signs of unsafe conditions before entering water that could make you sick.
5 red flags that should make you turn around before swimming in the lake
Ready for a quick water safety quiz?Take a longer-than-usual afternoon hike on a late spring day in the Sunshine State, the ground muddy from a recent downpour.The sun sets.Sweat drips.Then you come across a lake, most likely, as Florida is one of the states with the most lakes.it looks like a piece of armor sticking out of the surface and a pungent smell tickles your nose.Will you come in anyway?As it turns out, that would mean ignoring five of the biggest warning signs that should make you avoid swimming in a lake.
Swimming safety varies depending on where you're swimming. For example, swimming in the ocean presents many potential dangers—often requiring a lifeguard to stay close and identify dangerous rip currents. Additionally, sharks can be a cause for concern. At the same time, most swimming pools, if properly maintained and managed, are only open when they're deemed safe for swimming, but that doesn't mean they're not.Not gross. However, ponds occupy a strange middle ground. Many are just there, ready for use without supervision. While this bold freedom is part of the appeal, it is also a source of difficulty.
Fortunately, there are easy warning signs.Water quality alerts and advisories, posted in person and online, let you know what's simmering beneath the surface.Sometimes you run into literal red flags, the universal sign of danger.That said, the classic rule always applies: lifeguards know best and you are safe in their area.But what happens when you find an inviting lake and put aside those handy warnings and find yourself alone?Let's see.
Read more: Beach towns in Florida that could pass for the Caribbean
Avoid ugly and green flowers
If you ever stumble upon a lake with a water-green surface below, be careful.Lakes, which are freshwater sources, are prone to some diseases.The classic manifestation of this takes place in the form of algae-smooth green bark floating on the surface.Harmful algae caused by cyanobacteria (also known as blue-green algae), dinoflagellates, and diatoms can appear as green bitumen bubbles or something that looks like tracks.According to the Centers for Disease Control and Prevention (CDC).They also influence watercolors, turning them into unattractive shades of green, brown, red and blue.
According to the CDC and the UK Health Safety Agency, exposure to toxic algal blooms can lead to discomfort such as skin rash, coughing and watery eyes, or more serious symptoms such as vomiting, diarrhoea, muscle and joint pain or fever.The most difficult thing, however, is to distinguish between dangerous and benign algae.
To do this, the CDC recommends a three-pronged approach to potential blooms.First and foremost, avoid them.Any discolored and smelly water with strange growth on the surface is suspicious.Second, follow all posted advice.This applies not only to swimming, but also to fishing - after all, if the water is bad for the fish, it's probably bad for you.Finally, municipalities often post water quality advisories or maps online that show local bodies of water that are hazardous to public health.
Avoid water that is too cloudy
Few lakes share the clear waters of Caribbean beaches, and swimming in the mysterious abyss remains a big business.Or, depending on the perspective, it could be an advantage.However, there's a fine line between unknown and unsafe—and murky or cloudy water presents a long list of questions to consider before taking the plunge. In addition to bacterial blooms, cloudy water can be the result of hazardous sources, including everything from runoff to contaminants.
Although fresh water is not dangerous in itself, it can still hide dangers.Sharp objects, debris, and other hazardous materials can be waiting beneath the surface.Fortunately, scientific tools such as Secchi plates - black and white plates dropped into water - can help estimate the density of water.However, unless you are a scientist, the resulting data is useless, and the unknown is greater than the known.So, when in doubt, if you're going to take a dip, at least don't swallow, wearing a mask and earplugs can help.Finally, staying clean is also a solid way to avoid "swimmer's itch" on your lake trip.
Rainwater is a hidden danger.
Although the lakes themselves may not be dangerous, the surrounding area is.All it takes is a good rain to send a long list of pathogens washing into harmless waters.For example, rainwater can bring waste from nearby farms (including feces), as well as pesticides, fuel, and other pollutants from industrial activities.Likewise, drainage pipes can carry pollutants into lakes, and runoff can turn any lake into a secret reservoir of unknown chemicals and life forms.
As a result, rainfall accounted for more than half of all waterborne illnesses in the second half of the 20th century, according to a study by the Johns Hopkins Bloomberg School of Public Health.These diseases primarily manifest as gastrointestinal problems, and the presence of fecal matter, in particular, increases the risk of E. coli contamination. Although the Environmental Protection Agency has acceptable limits for E. coli for recreational water — as well as other standards — you may not be in a position to test for such levels.
To be safe, make sure that you always soak the lake well, and give it to 72 hours before injecting, if you don't have to take water or not.You don't want to run the risk of late water runoff.
Debris or floating objects means being outside.
Discovering a seemingly underutilized and underappreciated lake can feel like striking gold.It might even be one of the last frontiers of discovery.Still, although some may seem untouched, it's always worth a closer look.A lake, unlike a book, can be judged by its cover - and it should be.More than the obvious dangers of algae blooms and hazardous waste disposal, the debris floating on the lake's surface can reveal a lot about its life and condition.
If you see debris floating on the surface, such as cigarette butts, grease stains or random plastic objects or lily pads, this indicates pollution, a ship in need of a mechanic nearby, or a lack of management and maintenance by local authorities.Additionally, visible physical debris is a clear indicator of the presence of hidden chemical or bacterial contaminants in the water.The only thing a dirty face doesn't promise?Safe sailing.
Unpleasant odors indicate unsafe water
The last red flag you'll encounter as you approach the pool will be from the middle of your face.In particular, your nose can be your last line of defense and your best measuring tool, as almost all of the red flags above produce foul odors.Bacteria, algae and chemicals can hit your senses like a sledgehammer, and any rotten egg smell will indicate algae.flowers, which often give off a sweet smell when they die.Dead animals, such as fish in the stomach, will also do double duty, giving both visual and nasal warning to show what's going on.
Sometimes, though, the sheer excitement of seeing a welcoming body of water overwhelms you and you dive headlong into the pool, only to find that it's a real cesspool—and it smells like one, too.In addition to getting out immediately, you must wash your eyes, nose, and ears, and pay special attention to any cuts or open wounds that bacteria could enter. If you feel unwell, see a doctor.And next time use your senses.
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Read the original article about islands.
