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The Lower Colorado River Authority is urging people and pets to avoid algae in Inks Lake and Lake LBJ after tests detected toxic levels of cyanobacteria that could pose a danger. The concerning levels of toxicity were only detected in the algae, not in the lake water, the LCRA said. 

Test results were taken from three sites on each of the two lakes. Cyanobacteria, or blue-green algae, typically thrive in hot, dry weather, said LCRA Executive Director of Water John Hofmann. 

“The algae can begin producing toxins at any time, so our advice is to treat all algae as if it could be toxic,” Hofmann said. 

LCRA biologists said cyanotoxins likely are present in other areas of the Highland Lakes, but lakes Buchanan, Marble Falls, and Travis have not been tested. 

“There is every reason to believe algae there are producing toxins as well,” Hofmann said of the three untested lakes. “I can’t stress this strongly enough — don’t take an unnecessary risk with your family, friends, and pets. If you see algae in the water, move somewhere else to recreate, especially if you’ve got your dog with you.’’

Cyanotoxins from algae can pose a danger to humans and pets when ingested. Toxicity can only be confirmed by scientific testing as fragments of algae look and smell the same regardless of whether they are producing toxins.

“Pet owners need to take this seriously,” Hofmann said. “Dogs will eat algae or lick it off their coats, which can have devastating consequences if the algae are producing toxins.”

The LCRA has not received any reports of pets becoming ill in relation to algae in the Highland Lakes since 2021. The river authority has regularly monitored for cyanotoxins in lakes Buchanan, Inks, LBJ, Marble Falls, Travis, Bastrop, and Fayette since several dogs became sick or died after contact with algae in Lake Travis. The routine testing of lake water has either detected no cyanotoxins or, at times, cyanotoxins at levels well below what the World Health Organization considers potentially harmful to humans or pets.

This summer, LCRA began testing algal material in Lake LBJ and Inks Lake as part of a joint study with the city of Austin. Biologists with the the city monitor for toxic algae in Lake Austin, Lady Bird Lake, and Lake Walter E. Long. Information on city of Austin monitoring is available at

Swimming in a lake or river always carries some level of risk, warns the LCRA. Unlike swimming pools, natural water bodies are not chlorinated or disinfected. In addition to algae, other organisms such as bacteria or parasites could be present.

According to the Centers for Disease Control and Prevention, people who come into contact with cyanotoxins could experience the following:

irritation of the skin, eyes, nose, throat, or lungs;

and, if swallowed, stomach pain, headache, muscle weakness, dizziness, vomiting, diarrhea, or liver damage.

Symptoms in dogs could show up as:

  • excessive salivation
  • vomiting
  • fatigue
  • staggered walking
  • difficulty breathing
  • convulsions
  • liver failure

In some instances, death of animals can occur within hours or days.

For more information on LCRA algae testing, visit