AUSTIN, Texas — The City of Austin's Watershed Protection Department said Thursday that blue-green algae has been found in Lady Bird Lake.
The department learned of the algae's presence after it received lab results from a sample taken from Red Bud Isle on May 30. The department said it did not find mats of algae in other locations on Lady Bird Lake or Lake Austin when that sample was taken.
The toxin has previously been detected in algae samples taken from Lady Bird Lake and is a potent neurotoxin, the department said. Toxins produced by the blue-green algae can be harmful to people and pets.
To slow and potentially help prevent the growth of harmful algae in the lake, the department will expand its treatment of the body of water with a clay material that makes it hard for algae to feed and survive. Although the treatment should reduce the amount of harmful algae, the department said it still may be present.
Last year, the department applied the clay material, called Phoslock, to more than 22 acres of Lady Bird Lake near Red Bud Isle. Sediment tested from the area last month showed the Phoslock's effects had lasted over nine months.
With the expansion, the treatment will include the north shore of Lady Bird Lake from Interstate 35 to the lagoon by the Festival Beach boat ramp. The department said this area was chosen due to the results of algae samples collected last year showing toxins were present.
Treatment will happen on Monday, June 13, and Tuesday, June 14. The department said it would also reapply Phoslock at Red Bud Isle on Wednesday.
Thirty thousand pounds of Phoslock will be applied at each location and another treatment will be applied later in the summer, the department said. The cost for all the treatments, testing and lab work is $300,000.
Boaters are asked to avoid the treatment area during treatments and keep plenty of distance from the barge applying the treatment. The barge will be 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.
The department also warned lake goers that the algae may still be present even with treatment along with other bacteria and parasites. The department said people should look for water that is cool and running and avoid contact with algae.
Rinsing after swimming in natural bodies of water and not allowing dogs to lick their fur before rinsing is also encouraged.
The department said it has resumed biweekly monitoring of Lady Bird Lake and Lake Austin for harmful algae. Results are posted online but the department said the public should be aware that there is a one-to-two week turn-around time for results.
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