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What To Know About Austin’s Blue-Green Algae This Summer

Posted on June 10, 2025   |   Updated on September 30, 2025
Kelsey Bradshaw

Kelsey Bradshaw

An infographic about blue-green algae.

Don’t forget these tips! (Centers for Disease Control and Prevention)

It’s summer, temperatures are rising and that means it’s blue-green algae season here in Austin.

Blue-green algae, or cyanobacteria, has been detected in Austin waterways since 2019, when several dogs died after swimming in Lady Bird Lake. Algae thrives in warm water and it’s best to take precautions.

Here’s what you need to know:

🫡 Assume Harmful Algae Is Present

It’s best to believe harmful algae and other dangers like bacteria and parasites are always present in Austin waterways. The city suggests treating all algae as though it’s toxic.

“Although we keep an eye on the condition of our lakes and creeks, there is no amount of testing that could be done to assure them safe from all risk,” the city says.

🦠 There Are Signs To Look For

Stagnant water with scum, film, or algae mats on the surface are all signs that harmful algae may be present. Blue-green algae can show up as slimy blobs, typically dark green or dark blue with green, and can be mixed with other algae.

Algae has already been spotted at Red Bud Isle on Lady Bird Lake this year.

How To Keep Your Dog Safe in the Austin Heat

🚨 The City Is in the Final Stages of Its Prevention Program

City watershed officials are applying a clay to areas of Lady Bird Lake this week meant to starve blue-green algae and prevent it from growing. Areas include: Red Bud Isle, the boat ramp on the north shore of the lake west of Interstate 35, and the north shore of the lake between Interstate 35 and the lagoon behind the Festival Beach Boat ramp.

The program started five years ago and involves workers spraying the clay from a barge into the water. Clay will be sprayed twice more this summer, in July and August.

☝️ What Not To Do

  • Don’t drink from natural waterways.
  • Avoid contact with algae.
  • Keep your animal out of algae-infested waters.
  • If your animal does end up in the water, make sure you rinse their fur afterward and keep them from licking their fur.

😷 Symptoms To Look for in Your Dog

Symptoms your dog has ingested harmful algae can occur anywhere from 15 minutes to days after they’ve been exposed, the American Kennel club says. Watch for:

  • Diarrhea or vomiting
  • Drooling
  • Neurologic signs such as:
    • Weakness
    • Disorientation/confusion
    • Collapse/unconsciousness
    • Seizures
  • Breathing difficulties

If you see any of these symptoms, contact your dog’s vet as soon as possible to avoid injury or death.

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