Increased risk of harmful algae on Lady Bird Lake during summer

The Summer months bring the waters around Austin into an increased risk for harmful algae, says the Watershed Protection Department.

A harmful algae bloom, or Cyanobacteria, becomes more likely at Lady Bird Lake because warm water with high levels of nutrients flows lower through the lake. The department has begun weekly monitoring of algae from four separate locations on Lady Bird Lake.

RELATED: Hot days ahead: How to keep yourself safe

Lady Bird Lake testing locations: 

  • Red Bud Isle
  • The mouth of Barton Creek
  • Vic Mathias Shores
  • Festival Beach

Algae samples collected by staff are sent to UT Austin where researchers identify algae species, perform DNA fingerprinting, and test for toxins.

“ I did observe algae growth starting kind of the accumulate around the edges near the shoreline of Red Bud Isle, very little algae along Auditorium Shores, Butler Park area, the lower reservoir had a lot of algae,” said  Austin Watershed senior environmental scientist  Brent Bellinger.

Bellinger started collecting samples last week. The most recent samples were taken on Thursday. 

“If you went to each site and grabbed a clump of it, it looks different in all those locations, so the trick is, those samples are dropped off at the University of Texas, they’re going to have a look at them, see what species are present and hopefully ascertain if there's potentially any toxic species,  as well as if any toxins in the batch of the water itself,” said Bellinger.

Late Friday FOX 7 was told that preliminary findings indicate that the type of algae that produced toxins last year have been found at Red Bud Isle. The toxicity report on the water has not yet come in.  The area remains open but warnings are going up. 

Testing results from the initial samples should be available next week and can be found here.

2019's algae bloom was particularly harmful to dogs, whereas at least five dogs died after swimming in Lady Bird Lake, the city says. Therefore the city is recommending dog owners to exercise caution when allowing their dogs into Lady Bird Lake over the summer and fall months. 

RELATED: Pet owners mourn loss of dogs who died after swimming at Lady Bird Lake

Symptoms of algae exposure may include:

  • Excessive drooling, vomiting, and diarrhea
  • Foaming at the mouth
  • Jaundice and hepatomegaly
  • Blood in urine or dark urine
  • Stumbling
  • Loss of appetite
  • Photosensitization in recovering animals
  • Abdominal tenderness
  • Progression of muscle twitches
  • Respiratory paralysis

The city says education signs have been placed around Lady Bird Lake in six separate locations and more signs may be added if toxins are detected. 

Despite the safety advisory a lot of dogs were in the water Friday afternoon.

“We were going to the lake every day previously but that seem like it was getting cloudy that water was getting a little bit nasty and this water was nice and clear so I’m hoping this is safe for a while longer,” said Jeffery Parks who was near Butler Park with his dog.

Hot spots tend to be along shorelines, in Stagnant water, sometimes in aquatic vegetation and under trees. For dogs that do get in the water,  Bellinger recommends a nose to tail scrubbing.

“Make sure that you’re rinsing your dog off if they have been in the water rinse them off try to limit their exposure to the water try not to get them to drink the water which is of course tough rinsing them off though if they have any algae in there for so they’re not consuming that later is imperative also,” said Bellinger.

The city has set up a website that tracks conditions on the local waterways.  It will be upgraded to include an informational  dashboard e similar to what is used to track COVID-19 trends. Like the virus - controlling this watery outbreak will be difficult.


At this time the risk of harmful algae appears to be low and the city says people can continue to boat and fish while following COVID-19 restrictions.