Toxic bacteria continue to pose a threat in Lady Bird Lake, according to recent city water testing. Austin's Watershed Protection Department says it's still finding toxic blooms of algae at Red Bud Isle, Barton Creek and downstream from Barton Springs Pool – and that it likely won't go away until mid-October.
The blue-green algal blooms, known as cyanobacteria, were first detected in early August around Red Bud Isle. The algae produce a neurotoxin that the city says is responsible for the deaths of at least five dogs that previously swam near Red Bud Isle, which has been closed since earlier this month.
Further testing revealed other algae blooms at Auditorium Shores and Barton Creek downstream from Barton Springs Pool, but according the city, the most recent round of tests shows that the algae blooms haven't spread much.
“We’re seeing the positive samples come back from the same areas of the Lake,” says Sara Hartley, Assistant Director of Austin’s Watershed Protection Department. “Although we do know that the algae mats can break up and move around, so we’re still cautioning anyone that’s out on the lake to stay away from any algae that they see.”
This is not the first time blue-green algae have appeared in local waterways, but Hartley says, it is the most severe and deadly outbreak recorded by the city.
Experts say several things triggered the algae blooms. Increased silt, agricultural and waste runoff brought into the lake from last year’s severe fall flooding created a welcoming environment for the algae.
The blooms are something Austinites could see more of as climate change warms local waterways, researchers say.
Austin just wrapped up one of its longest stretches of triple digit days ever recorded, and according to the Environmental Protection Agency, that relationship between warmer temperatures and algae growth means toxic blooms will become more common as the earth’s atmosphere heats up.
“We are absolutely taking climate change very seriously when it comes to this particular situation,” Hartley said, “because temperatures rising means the water temperature is rising, and that could be one factor that allows for additional algae blooms.”
Climate change encourages algae blooms in several ways. For one, algae floats to the surface more easily in warmer water, but those warmer temperatures also prevent water from mixing, which allows algae to grow thicker and faster, according to the EPA.
The City of Austin expects the algae to die off by mid-October when temperatures cool. In the meantime, officials are urging people to keep their dogs away from lake water.
Hartley says people kayaking or paddle boarding on the Lake should avoid algae and shower immediately after.