Cool Weather Brings An End To 2020 Harmful Algae Season

Watershed Protection staff are no longer detecting harmful algae in Lady Bird Lake. With cool temperatures, harmful algae are unlikely to return until next summer.

Although there is always some level of risk in a natural water body, currently the risk at Lady Bird Lake is low.

This year, the city first detected toxins in algae samples taken from Lady Bird Lake on July 14th and continued to find toxins until mid-November. The last positive algae sample was taken on November 10th.

“Thankfully, we did not receive any reports of dogs becoming ill or dying due to algae exposure after swimming in the lake this year,” Watershed Protection Department said. “We credit this success to the care dog owners took in following recommendations and keeping their pets out of the water during the long, hot summer and fall.”

The city first received reports of dogs dying after swimming in Lady Bird Lake in August 2019.

“This year, we instituted a weekly monitoring program for harmful algae beginning in late June to help avoid a similar, sad situation,” the city said. “Signs were posted at the lake to educate dog owners, and data from the monitoring program has been available on a dashboard at AustinTexas.gov/algae.”

During the low-risk season, we will not be updating the dashboard except to present average temperature and flow data from the summer and fall.

The type of harmful algae on Lady Bird Lake is different from the more common algae outbreaks in the Great Lakes and along the Gulf Coast.

Rather than being dispersed throughout the water body, the algae grows in clumps at the bottom of the lakebed and rises to surface of the water.

There is less information or research available about this type of harmful algae bloom. Data from the monitoring program this year will help the city understand more about when the algae is likely to emerge next year.
 
There is more information available at AustinTexas.gov/Algae.