Austin Watershed Protection Department to expand approach to tackling harmful blue-green algae
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The City of Austin Watershed Protection Department will continue testing algae on Lady Bird Lake (Jack Flagler / Community Impact Newspaper)
The City of Austin’s Watershed Protection Department has been grappling with harmful algae in its lakes since the summer of 2019, and a number of new incidents have resulted in the department ramping up its algae plan.
in the early April, amid what the city called “off-season,” low levels of Dihydroanatoxin – a form of cyanobacteria – has been detected in Lake Austin and Lady Bird Lake. Earlier this year, the same toxin, which can be fatal if consumed by dogs, was discovered in Lake Travis by the Lower Colorado River Authority.
In response, Austin’s department announced on June 1 that it would expand its plan to include year-round, bi-weekly surveillance at three locations on Lake Austin and Lady Bird Lake. In addition, the city will monitor an area on Walter E. Long Lake at least three times in summer and autumn.
Results from a June 1 visit to Lake Austin and Lady Bird Lake showed no signs of algae in either location, according to an update posted on the city’s algae side.
To address the algae problem, the watershed department is also planning to use a material called Phoslock, which is patented to help mitigate harmful algal blooms.
The clay-like material hinders the growth of algae by binding to phosphorus, which serves as fuel for cyanobacteria. Phoslock binds to water and sediment to trap phosphorus in a mineral form, making the nutrients unavailable to cyanobacteria, according to Brent Bellinger, senior environmental scientist with the Austin Watershed Protection Department.
“We will target the nutrients that are in the water column and in the sediments,” said Bellinger.
If approved by Austin City Council on June 10, the pilot would include three applications of Phoslock over 20 acres of water around Red Bud Isle.
The 2021 program includes a price of $ 300,000, which the department says will cover the cost of materials, applications, and extensive laboratory testing. During the June 10 meeting, the council will discuss a five-year $ 1.48 million deal with SePRO Corp., the company that makes Phoslock.
Phoslock was first developed by an Australian national science agency and has since been featured in more than 80 peer-reviewed publications as an effective algae prevention method, according to city information. Bellinger said that Phoslock is particularly attractive to the water catchment area because of its environmental friendliness.
Methods to kill harmful algae can include copper sulfate treatments known as algicides, according to Bellinger, who said these have their drawbacks. Phoslock doesn’t kill cyanobacteria directly, but it can prevent it, he said.
“Unfortunately, [algaecides] can kill many other desirable invertebrates so we’re looking for something that is environmentally friendly, ”said Bellinger. “The other side effect of treating the algae, [with algaecides] Here, too, one does not really address the problem that drives algae growth. ”
Phoslock would be used three times by boat over a nine week period starting June 21. During this time, residents would still have access to Redbud Isle, although the town may provide information to visitors to the lake through signage.
While the department believes Phoslock should result in less toxicity, recreational users and dog owners should continue to exercise caution with algae. Bellinger said the treatment is not a “miracle cure” and that the environment does not automatically become safe when used.
“This is a pilot project. We know how Phoslock can work and we suspect and hope that it will reduce algae growth and possibly toxicity, ”said Bellinger. “But we still urge caution.”
Recreational users should never allow their dogs to consume or touch seaweed while swimming in lakes in central Texas. Learn more about the city’s seaweed Desktopwhich will be updated in the coming weeks.
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