Austin is seeing thick, floating blobs of harmful blue-green algae (cyanobacteria) in its waterways, with colonies detected at Red Bud Isle on Lady Bird Lake and Walsh Boat Landing on Lake Austin, as well as in other creeks and ponds. The algae can produce the neurotoxin dihydroanatoxin-a, making it toxic to humans and especially dangerous to pets. Since 2019, six dogs have died from related toxins. City officials urge caution: avoid water with algae along the shore, surface scum, stagnant or murky areas, or any water after recent rain.

People and dogs should not drink lake water, swim near the blobs, or allow pets to lick their fur before rinsing off after contact. Symptoms of poisoning in dogs include excessive drooling, vomiting, diarrhea, stumbling, muscle twitches, and respiratory issues; humans may experience rashes, gastrointestinal problems, headaches, or neurological symptoms. More blooms are expected as temperatures rise. Officials recommend assuming all algae may be toxic and seeking medical or veterinary help if symptoms appear after exposure.