Scientist says toxic blue-green algae likely caused by cold weather

The Lower Colorado River Authority is continuing to test the water in the Highland Lakes after ten locations of Lake Travis tested positive for toxins from blue-green algae. 

The toxins are suspected to have caused illness and the death of several dogs playing in the lake near Hudson Bend

Most of the algae present at Lake Travis is harmless, but the LCRA said this year tests showed toxic blue-green algae mixed in. 

"Until you've got the all-clear, I would kind of avoid it," said John Higley, CEO and principal scientist for Environmental Quality Operations, an Austin-based laboratory that aims to detect, monitor, and eradicate invasive species. 

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The toxic blue-green algae found near the shoreline likely led to sick and dying dogs this winter, according to the LCRA. 

It's a similar story to what is believed to have happened to several dogs who swam in the water at Red Bud Isle and Lady Bird Lake in 2019. The City of Austin later confirmed the presence of toxins from blue-green algae in those locations in the summer of 2019 and 2020

"It really can happen in any of our Highland Lakes, as long as you have an area where it's somewhat less turbulent, so it's not moving so fast. So things can kind of grow and churn wherever there's storm runoff, warm weather, or when there's a big nutrient mixing event, we're likely to see these kinds of things happen," Higley said. 


During previous years' toxic algae blooms, dog owners were warned to keep an eye out as water temperatures warmed up. This year comes with a warning to also be vigilant following a cold snap. 

"This is kind of one of those things where the freeze actually likely brought it up and released it, rather than bringing it down... So this is a different type of blue-green algae. Something else to worry about, something new to worry about," said Higley. 

The LCRA warns people and pets can be exposed to harmful toxins by swimming in or ingesting water where the blue-green algae is present. That can lead to severe reactions for both humans and animals. 

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"I think, if you see algae, don't swim it, period... And certainly don't let your animals, or livestock, or pets drink from the shoreline," Higley said. 

Higley said there's a better way to proactively check for algae toxins so that no other pets or people are unknowingly exposed. "We need to be using biosensors and do a whole bio-monitoring process to avoid these kinds of events in the future, and it can't be done," said Higley. 


Until then, the risk will always remain at natural bodies of water. "I think people are just going to have to be hyper-aware. Anytime there's an abrupt weather change, storm event or anything like that," Higley said. 

The LCRA warns dog owners to call a vet immediately if their pet has excessive drooling, seizures, weakness, vomiting or diarrhea after contact with a natural body of water. People should call a poison control center if they experience similar symptoms that could be related to exposure to harmful algae.