Zebra mussels on water intakes
Plans underway to treat waters, avoid damage of an infestation.
Clusters of invasive zebra mussels have been found clinging to filtering screens in Austin’s water utility intake pipes on Lake Travis.
Divers made the discovery Sept. 7 while inspecting the screens at the Handcox Water Treatment Plant on Lake Travis. The plant uses three intakes set one above the other at different depths to bring in water.
At the beginning of the month, divers went down to make a routine intake switch. The intakes are opened or closed depending on lake water levels.
In the first intake, the divers saw that almost half of one screen was covered with mussels. Then, more than 20 percent of a second screen was covered, said Mehrdad Morabbi, Austin Water’s treatment operations manager.
The screens are octagonal and measure roughly 24 feet by 30 feet, he said.
Divers used a pressure washer to clear out the lower intake screen and began work on the top intake, which Morabbi said usually does the brunt of the work at the facility. However, time constraints only allowed them to remove roughly 50 percent of the mussels on that intake.
Divers will have to come back in the winter to finish the job.
Morabbi said Austin Water completely shuts down its intakes while divers are working, so they have to wait until water demand is lower.
The discovery comes more than a year after the critters appeared in Lake Travis, and about seven months after Texas Parks and Wildlife Department officials first spotted the larvae of the razorsharp mussels in Lady Bird Lake.
Earlier this year, 14 bodies of water and five river basins in Texas — including Lake Austin and Lake Georgetown — were found to be infested with zebra mussels.
Seven more either tested positive or were suspected of containing zebra mussels.
In other parts of the country, infestations have led to millions — in some cases, billions — of dollars in damage to infrastructure.
A 2009 report from the Aquatic
Nuisance Species Task Force found that zebra mussels cost the power industry $3.1 billion through much of the 1990s by clogging pipes in the Great Lakes.
“It’s concerning, but it’s not unexpected. We knew that typically the first season is the worst season,” Morabbi said. “This is historically (the case) based on what we’ve studied and (who) we’ve talked to.”
Austin Water has hired a consulting firm that is about to wrap up a preliminary engineering study to address the problem in the future.
Authorities are considering chemical options to treat the water for mussels, but any change in treatment has to be approved by the state.
The Handcox facility is one of three Austin Water treatment facilities. The mussels likely have started to swarm intake pipes at the two other facilities on Lake Austin as well.
“We inspected the Lake Austin ones around the beginning of summer,” Morabbi said, adding that those facilities also will be inspected again in the winter. “We expect to find mussels in those facilities too.”
Zebra mussels have con- tinued their steady spread across Texas since first arriving in the state on Lake Texoma in 2009.
Authorities said the Legislature provided more than $6 million to Texas Parks and Wildlife from statewide management of invasive species in the 2016-17 and 201819 biennial budgets.
“These investments expand TPWD’s ability to combat the spread of zebra mussels, and helps to fund a public awareness campaign, outreach and prevention efforts, and research into new solutions,” officials said.
Zebra mussels are small, only centimeters in size when fully grown.