The City of Austin will undergo its third year of a pilot program to mitigate harmful algae on parts of Lady Bird Lake. The program consists of applying lanthanum-modified clay near Red Bud Isle and along the north shore of the lake between I-35 and the lagoon near the Festival Boat Ramp.  

The clay material may help prevent or slow down the growth of harmful algae in the areas where it is applied. The clay binds to phosphorus, a key source of nutrients for algae. Once bound into a mineral form, the phosphorus becomes unavailable to the algae and essentially robs the algae of one of its primary food sources. 

The first applications will take place at Red Bud Isle on Monday, June 5, and east of I-35 on Tuesday, June 6, weather permitting. If additional time is needed, the work will extend into Wednesday, June 7. Additional applications are planned for July and August. 

The material is applied from a barge. It will look like the team is spraying a gray slurry into the lake that will temporarily cloud the water. The substance is safe for humans, the environment and wildlife, and will settle to the bottom in a few hours. During treatment, boaters should keep plenty of distance from the barge. 

Last year, the City of Austin applied a total of 60,000 pounds in each area across three applications. In 2021, the City applied 120,000 pounds at Red Bud Isle. Along the north shore of the lake between I-35 and the lagoon, there did not appear to be any alterations of the sediment phosphorus pool last year. This may have been due to weather patterns and the material getting washed downstream. This year the City is adjusting the program to apply more product along the north shore east of I-35 and less at Red Bud Isle. 

Blue-green algae are present on both Lady Bird Lake and Lake Austin and may contain toxins. Algae samples have been sent to a lab for testing, but the results have not been received yet. Other dangers, such as bacteria and parasites, may also be present. The City recommends that people and pets avoid contact with algae, not drink water directly from the lake, and rinse off after contact with the water. Do not allow dogs to lick their fur prior to rinsing. Please note that swimming is prohibited in Lady Bird Lake.  

If a person has sudden, unexplained symptoms after swimming, they should contact their medical provider or the Texas Poison Control Center at 1-800-222-1222. For a pet, they should contact their veterinarian. Please also let the City know by completing the reporting form, found at  AustinTexas.gov/Algae.