With the sad news that several dogs have died after probable exposure to toxic algae in Lady Bird Lake, questions have been raised about a health threat many did not even know existed.
What is toxic blue-green algae?
These are actually not algae, but a group of bacteria, called cyanobacteria, that contain special pigments enabling them to make their own food from the sun like plants. They occur naturally in all types of water, including the creeks, rivers, and lakes of Central Texas. In warm, slow-moving water, typically in the late summer or early fall, cyanobacteria can multiply into large concentrations called “algae blooms” that can be seen as they spread across the water’s surface. Fertilizer runoff into streams and ponds increases the risk of these blooms by adding additional nutrients to the water for growth. Invasive zebra mussels are also linked to algae blooms. I saw my first zebra mussels in Lake Austin last summer on a piece of driftwood floating by. This summer they are everywhere, covering anything they can attach to underwater.
Why are they dangerous?
Many species of cyanobacteria produce toxins which can be extremely dangerous to all animals. The most dangerous is a neurotoxin which can cause rapid paralysis and death before there is time to get help. Other toxins can damage the liver, kidneys, gastrointestinal tract, and skin. Dogs are especially at risk because they not only swim in questionable water but also drink it.
What are the symptoms of blue-green algae poisoning?
Symptoms vary widely but include vomiting, diarrhea, drooling, weakness, muscle tremors, disorientation, seizures, and difficulty breathing. Symptoms can show within 30-60 minutes of exposure, and while immediate veterinary care is imperative, there are no antidotes to the toxins. Rapid decline and death can occur in spite of emergency treatment.
How do I know if the water is safe for my dog?
Never allow your dog to drink or swim in water that looks suspicious in any way. Not all algae blooms produce toxins, but you cannot tell by looking. Any water that has an unnatural blue-green color is covered in a brown or green scum, or has a foul smell should be avoided. Remember that not all toxic algae is floating on the surface where it is obvious. I always advise, when in doubt, keep your dog out. Some algae blooms float on the surface allowing the wind to blow heavy concentrations to the shoreline where dogs drink. These were the first zebra mussels in our lakes I had seen.
What about Lady Bird Lake?
While other lakes in the area are fine, Lady Bird Lake is for now not safe for dogs. The area of most concern is around Red Bud Isle Park just below Tom Miller Dam. The water there is shallow, warm, and slow-moving with large areas covered in algae. Tests are ongoing to confirm the presence of toxins, but for now, the park is closed and the entire lake is off-limits to dogs. People swimming in Lady Bird Lake has long been prohibited. Surface activities on the lake such as paddle boarding and canoeing are presumed to be safe for people although caution is advised. While no human deaths have ever been reported, people have become sick from toxic algae exposure. Austin drinking water does not come from Lady Bird Lake.