AUSTIN (KXAN) — Austin’s Watershed Protection Department sent crews Sunday to Lady Bird Lake to treat toxic blue-green algae blooms after an area tested positive June 9.

They’ll be out there Monday and Tuesday as well, using a chemical called Phoslock that is designed to bind phosphorus — a key nutrient for algae blooms — so the plants can’t use it to grow. The positive test was for an area around Red Bud Isle, but the blooms that secrete the cyanotoxin that can kill animals have been found throughout Lady Bird Lake and Lake Austin in the past.

  • The City of Austin said it will be treating the water with Phoslock, which cuts off nutrients to the algae and keeps it from spreading. Crews were out on boats over the weekend treating spots where the toxic algae has been detected. (KXAN photo/Frank Martinez)
  • The City of Austin said it will be treating the water with Phoslock, which cuts off nutrients to the algae and keeps it from spreading. Crews were out on boats over the weekend treating spots where the toxic algae has been detected. (KXAN photo/Frank Martinez)
  • The City of Austin said it will be treating the water with Phoslock, which cuts off nutrients to the algae and keeps it from spreading. Crews were out on boats over the weekend treating spots where the toxic algae has been detected. (KXAN photo/Frank Martinez)
  • The City of Austin said it will be treating the water with Phoslock, which cuts off nutrients to the algae and keeps it from spreading. Crews were out on boats over the weekend treating spots where the toxic algae has been detected. (KXAN photo/Frank Martinez)
  • The City of Austin said it will be treating the water with Phoslock, which cuts off nutrients to the algae and keeps it from spreading. Crews were out on boats over the weekend treating spots where the toxic algae has been detected. (KXAN photo/Frank Martinez)

The city has a dashboard available to the public to check where crews have tested for the toxins and if the tests came back positive. Blue-green algae blooms thrive in warm, stagnant water, and the city has tested for the toxins at Auditorium Shores and the Festival Ramp, along with Red Bud Isle. As of Monday afternoon, the only positive test has been at Red Bud Isle. For pet owners, that means you should keep your furry friends out of the water near there.

The dashboard also shows water temperatures and flow data for each of the testing sites.

There’s also a dashboard for Lake Austin and testing sites at Jessica Hollis Park, the Walsh Boat Landing and Emma Long Metropolitan Park. The latest tests for those spots haven’t come back yet.

The treatment costs around $300,000, the city said, but it appears to be well worth the expense. Officials said they used the chemical — which is safe for both people and pets — on 22 acres around Red Bud Isle last year and it reduced phosphorus levels by 40% and it lasted for months.

The city said it’ll use around 30,000 pounds of the material, and it will be applied again later this summer.