Cyanobacteria are one of the oldest known life forms on earth. Better known as blue-green algae, the photosynthetic microorganism occurs naturally in almost all waterways around the world. The algae itself is relatively benign. But when it mixes with runoff from cities and farms, carrying fertilizers and other pollutants, the algae can start to bloom and release a powerful toxin that can cause rashes and stomach, liver, or respiratory problems in humans.
This summer, one such bloom led to the death of multiple pets that had been swimming in, and likely ingested, contaminated water in Austin’s Lady Bird Lake. (No human cases of poisoning have been reported.) In Austin’s waterways, which are part of the Lower Colorado River watershed, algal blooms themselves aren’t uncommon. But in years past, the blooms haven’t been of the toxic variety—most reported sightings have been about the type of gold or green algae that forms a layer of harmless, if aesthetically unpleasant, scum in the water.
“In general, algae are a natural part of the ecosystem. They’re essential at the base of the food web—they’re just plants,” says Brent Bellinger, a senior environmental science specialist with Austin’s Watershed Protection Department. The city is still investigating the specific set of factors that caused the toxic, blue-green cyanobacteria in particular to bloom in high concentrations this summer. Austin is the only city where the Texas Parks and Wildlife Department (TPWD) has confirmed cases of cyanobacteria this summer. For now, the department recommends that people and pets avoid swimming or drinking from pools of stagnant water where algae is visible—whether or not it’s the poisonous kind.
