Austin Launches Final Year of Algae Reduction Pilot on Lady Bird Lake
AUSTIN, TX — In an ongoing effort to combat harmful algae blooms, the City of Austin will begin the final phase of a five-year pilot program on Lady Bird Lake next week. The program, which began in 2020, aims to reduce the proliferation of toxic cyanobacteria—also known as blue-green algae—by targeting its food source: phosphorus.
The city will apply lanthanum-modified clay to three high-risk areas of the lake starting Monday, June 9. The clay binds with phosphorus in the water, rendering it unavailable for algae growth. If needed, the application will continue on June 10. Additional treatments are scheduled for July and August, when hot weather typically drives algae proliferation.
The treatment sites include:
- Red Bud Isle
- The boat ramp on the north shore of the lake, west of I-35
- The north shore between I-35 and the lagoon behind the Festival Beach Boat Ramp
The application is performed from a barge and may resemble a gray slurry being sprayed into the water. While the substance is safe, officials ask boaters to steer clear of the barge during application.
Each year of the program has cost approximately $300,000, funded through the city’s drainage charge on utility bills. Over the past four years, results have varied: Red Bud Isle has seen significant phosphorus reductions, while downriver sites have shown smaller improvements. City scientists attribute the mixed outcomes to varying sediment chemistry and runoff from urban tributaries.
Following the final treatment this year, the city will evaluate its findings and determine the most effective long-term strategy to manage nutrient levels in the lake. One key focus is preventing nutrient pollution at its source.
Residents Encouraged to Help
While the pilot program has played a key role, city officials emphasize that community involvement is essential. Residents are urged to:
- Limit or avoid fertilizer use
- Pick up pet waste
- Replace lawns with native plants and vegetation
- Plant trees and shrubs along creeks to filter runoff
Nutrient pollution comes not only from within Austin but also from upstream sources beyond the city’s control—including fertilizers, aging septic systems, and wastewater discharge. Climate change and invasive species like zebra mussels may also influence nutrient dynamics and algae growth.
Public Health and Safety
Since the first documented harmful algae bloom on Lady Bird Lake in 2019, new blooms have been detected each year. Similar incidents have occurred in Lake Austin, Barton Creek, and other nearby water bodies. Though widespread contamination has been avoided, algae mats—where toxins are concentrated—pose health risks to humans and pets.
The city continues to advise:
- Avoiding contact with algae
- Not allowing pets to swim or lick their fur after contact
- Refraining from drinking untreated lake water
- Rinsing off thoroughly after water contact
Swimming in Lady Bird Lake remains prohibited.
Anyone experiencing unexplained symptoms after water exposure should contact their healthcare provider or the Texas Poison Control Center at 1-800-222-1222. Pet owners should consult their veterinarian if symptoms appear. Suspected algae-related incidents can be reported at AustinTexas.gov/Algae.
Despite the concerns, officials note that Austin’s algae blooms remain relatively limited compared to other parts of the country and world, where entire water bodies have been closed. With continued intervention and public cooperation, the city aims to preserve the health and safety of its treasured urban lake.
