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Austin reopens Red Bud Isle after dog-killing toxins from algae subside

Monday, November 25, 2019 by Andrew Weber, KUT

Red Bud Isle has reopened after being closed for months because of toxins that attached to blue-green algae, city officials say.

The Austin Parks and Recreation Department said at noon Friday it reopened the area on Lady Bird Lake, which had been the nexus of an algae bloom that was reportedly responsible for the deaths of at least five dogs. The city closed the area in August and had been periodically monitoring levels of toxins in algae at various sites on the lake.

The city said dog owners can now let their pets swim in the lake at their own risk. But another harmful algae bloom could happen at any time in the lake, the city warned.

Levels of the toxin reached their peak in August. Scientists testing algae at three sites for the city’s Watershed Protection Department found the toxin was still lingering last month. As of Nov. 12, the toxin wasn’t present in algae samples taken from Lady Bird Lake, prompting the city to reopen Red Bud Isle today.

Exposure to the toxins that attach to blue-green algae can be fatal for pets, but is not considered deadly to humans.

Nutrients from upstream runoff in the Highland Lakes fed the algae blooms, collecting around Mansfield and Tom Miller dams, according to environmental scientists with Watershed Protection. That runoff was spurred by flooding events along the Llano and Pedernales rivers last year.

While the toxic blooms largely stayed put this summer and fall, officials worry they could become more prevalent going forward as the earth warms. The algae blooms thrive in clear, warm waters with little flow.

Environmental scientists say the presence of invasive zebra mussels in Lady Bird Lake will likely lead to more blooms in the future. The mussels filter the water, and the clearer waters ultimately allow more sunlight through to feed algae that initially blooms on the bottom of a body of water before floating to the top.

This story was produced as part of the Austin Monitor’s reporting partnership with KUT. Photo by Jorge Sanhueza-Lyon/KUT.

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