Summer sunshine beckons us towards the water. Lazy afternoons by the lake, refreshing dips in the pond, or casting a line from the riverbank are quintessential warm-weather joys. But lurking beneath the surface, or sometimes quite visibly floating on top, can be an unwelcome guest: blue-green algae. While not all algae are harmful, certain types, specifically cyanobacteria often referred to as blue-green algae, can produce toxins that pose risks to people and pets, turning a perfect summer day sour.
Understanding the Unwanted Guest: What is Blue-Green Algae?
First things first, let’s clear up a common misconception. Blue-green algae aren’t technically algae at all! They are a type of bacteria called cyanobacteria. These microscopic organisms are naturally present in freshwater ecosystems like lakes, ponds, rivers, and reservoirs. Under specific conditions, however, their populations can explode, creating what we call a bloom. Think of it like a bacterial boomtown appearing almost overnight.
What fuels these blooms? Cyanobacteria love warm, slow-moving or stagnant water that’s rich in nutrients, particularly phosphorus and nitrogen. These nutrients often find their way into water bodies through runoff from agricultural land, fertilized lawns, leaking septic systems, and urban stormwater. When the temperature climbs and the water stays still, these bacteria can multiply rapidly, forming visible and sometimes vast accumulations.
Why Give Blooms a Wide Berth?
The main reason to be cautious around blue-green algae blooms is their potential to produce cyanotoxins. Not all blooms produce toxins, and even within a bloom, toxin levels can vary greatly. However, it’s impossible to tell just by looking whether a bloom is toxic or not. Therefore, the safest approach is always to assume it could be harmful.
Contact with or ingestion of water containing these toxins can lead to unpleasant consequences. Skin contact might cause rashes, hives, or blisters. Accidentally swallowing contaminated water could lead to stomach cramps, nausea, diarrhea, or vomiting. While serious health effects are less common, they are possible, making avoidance the best strategy. Pets, especially dogs who are more likely to drink lake water or lick scum off their fur, are particularly vulnerable and can become severely ill very quickly after exposure.
Becoming a Bloom Spotter: Identifying Blue-Green Algae
Knowing what to look for is your first line of defense. Blue-green algae blooms can vary significantly in appearance, but here are some common signs:
- Appearance like Scum or Paint: Often, blooms look like thick scum floating on the surface. It might resemble pea soup, spilled paint (typically green, blue-green, or sometimes reddish-brown), or thick mats.
- Color Variations: While often greenish or blue-green, blooms can also appear brownish, yellowish, reddish, or even whiteish.
- Surface Streaks or Dots: You might see streaks on the water surface or tiny green dots suspended in the water column.
- Cloudy or Murky Water: The water might lose its clarity and take on a distinct color associated with the bloom.
- Unpleasant Odor: Some, but not all, blooms produce a noticeable smell, often described as grassy, musty, septic, or like rotting plants.
It’s important to distinguish cyanobacteria blooms from harmless green algae or aquatic plants. True algae often look stringy or hairy and can be scooped up, feeling somewhat coarse. Duckweed consists of tiny individual floating leaves. Pollen can accumulate on the surface but usually looks yellowish and powdery. Cyanobacteria blooms often look more like paint or scum that disperses into fine particles when disturbed, rather than stringy filaments.
Where Do Blooms Typically Hang Out?
You’re more likely to encounter blue-green algae blooms in certain environments and conditions:
- Still Waters: Ponds, lakes, and reservoirs are prime locations, especially in shallow, sheltered bays where water doesn’t circulate much.
- Slow Rivers: Slow-moving sections of rivers can also support blooms.
- Warm Temperatures: Blooms thrive in warmer water, making late summer and early fall the peak season in many regions.
- Nutrient-Rich Areas: Water bodies receiving runoff from farms, fertilized lawns, or wastewater sources are more susceptible.
- After Heavy Rains: Stormwater runoff can wash excess nutrients into waterways, potentially triggering a bloom.
Strategies for Safe Summer Swims and Recreation
Being aware and taking precautions can significantly reduce your risk of encountering harmful blooms.
Look Before You Leap (or Wade, or Paddle)
This is the golden rule. Always take a few moments to visually inspect the water before you, your children, or your pets go in. Scan the surface and the shoreline. Does it look clear, or can you see signs of scum, discoloration, or paint-like streaks? If the water looks suspicious in any way, err on the side of caution and stay out.
Heed the Warnings
Many local health departments, park districts, or environmental agencies monitor popular recreational waters for harmful algal blooms. Check their websites or look for posted signs at beaches and boat launches. These advisories provide valuable information about current water conditions. If an advisory is issued, follow the recommendations strictly.
Important Water Safety Notice: Always visually inspect water bodies before entering. Look for surface scum, discoloration, or paint-like appearances which may indicate a harmful blue-green algae bloom. Pay attention to local health advisories and posted warnings at recreational sites. When in doubt about water quality, it is always safest to stay out and keep pets away from the water’s edge.
Protect Your Pets
Dogs are naturally drawn to water, but they are at higher risk from cyanotoxins. They are more likely to drink contaminated water while swimming or playing fetch. They may also ingest toxins by licking their fur after being in the water. Always provide fresh drinking water for your dog so they aren’t tempted to drink from the lake or pond. Keep them on a leash near suspect water bodies and prevent them from swimming in or drinking water that shows signs of a bloom. If your dog does come into contact with potentially affected water, rinse them off thoroughly with clean water immediately, paying attention to areas around the mouth and paws, and watch them closely for any signs of illness.
Rinse After Your Dip
Even if you don’t see an obvious bloom, it’s a good practice to rinse yourself, your children, and your pets off with fresh, clean water after swimming in any natural body of water. This helps remove any lingering bacteria or potential irritants from the skin and fur.
Don’t Treat Natural Waters Like Tap Water
Never drink untreated water directly from lakes, rivers, or ponds. Boiling water may kill bacteria, but it does not remove cyanotoxins if they are present. Always bring plenty of safe drinking water with you for your outings.
Report Suspicious Blooms
If you encounter water that you suspect has a blue-green algae bloom, consider reporting it to your local health department or environmental agency. This helps authorities track blooms and issue timely warnings to protect public health.
What About Fishing?
Fishing in waters experiencing a bloom requires caution. While simply catching fish is generally considered safe, there’s debate about consuming fish caught from affected waters. Toxins can potentially accumulate in fish tissues, particularly in organs. Check for any local fish consumption advisories issued by health or wildlife agencies for the specific water body. When cleaning fish caught in potentially affected waters, remove the guts and liver, and rinse the fillets thoroughly with clean water before cooking.
Enjoying summer activities on or near the water is a fantastic way to beat the heat and have fun. By learning to recognize the signs of blue-green algae blooms and taking simple precautions, you can significantly minimize potential risks. A little awareness goes a long way in ensuring your adventures remain safe and enjoyable for everyone, including your furry companions. Stay vigilant, check conditions, and when faced with murky, scummy water, remember the simple rule: when in doubt, stay out!
