Toxic blue-green algae found in Lake Austin, Lady Bird Lake

A sign along the Ann and Roy Butler Hike and Bike trail reminds residents not to swim in Lady Bird Lake. (Jack Flagler/Community Impact Newspaper)
A sign along the Ann and Roy Butler Hike and Bike trail reminds residents not to swim in Lady Bird Lake. (Jack Flagler/Community Impact Newspaper)

A sign along the Ann and Roy Butler Hike and Bike trail reminds residents not to swim in Lady Bird Lake. (Jack Flagler/Community Impact Newspaper)

The presence of toxic blue-green algae or cyanobacteria has been confirmed in Lake Austin and Lady Bird Lake, according to an April 6 news release from the Austin Watershed Protection Department.

Aglae samples taken in mid-March from the Mansfield Dam area of Lake Austin tested positive for dihydroanatoxin—a toxin produced by cyanobacteria. Trace concentrations of the toxin were also detected in two algae samples collected from Lady Bird Lake.

Dihydroanatoxin is the same toxin recently discovered by the Lower Colorado River Authority within Lake Travis and other water bodies in the Highland Lakes chain. It was also found in 2019 and 2020 in Lady Bird Lake, which resulted in the death of at least five dogs.

The toxins produced by cyanobacteria can be dangerous when ingested by dogs, even in small amounts. Symptoms of exposure can include vomiting, excessive drooling and respiratory paralysis, among other illnesses.

As a result, the city is urging caution and recommended that dog owners not allow their dogs to ingest or touch algae within any local water bodies. The department also recommended rinsing dogs with clean water after swimming since some dogs will ingest the toxins by licking their fur.



If symptoms do occur, dog owners should seek veterinary care immediately and report the illness to the city’s service line at 311.

The events stemming from 2019 and 2020 were often linked to arid weather conditions and high temperatures, according to previous reports from the city. However, the most recent incidents in Austin and around Lake Travis occurred during a colder season.

As a result, the watershed protection department said it will re-evaluate its current monitoring program, which corresponds to an online information dashboard traditionally updated during the summer months.

The April 6 release confirmed the risk to humans is low, and people can continue to boat and fish within the lakes while avoiding handling any algae.

Notably, swimming has been banned in Lady Bird Lake since 1964, according to the release.

By Amy Rae Dadamo
Amy Rae Dadamo is the reporter for Lake Travis-Westlake, where her work focuses on city government and education. Originally from New Jersey, Amy Rae relocated to Austin after graduating from Ramapo College of New Jersey in May 2019.