When Lago Vista resident David Reed traveled to Point Venture to go fishing on the banks of Lake Travis in mid-May, he noticed clusters of small mussels scattered around the shores with a distinctive striped design on the shells.
Reed said he had heard about zebra mussels in the news, but he had never before seen the mussels in person.
“I started to remove the ones I could see, and then I realized that there were hundreds of them just scattered throughout the rocks,” he said. “They’re definitely here; it’s not just a rare occurrence."
Zebra mussels were discovered in Texas within the past decade, and the Texas Parks and Wildlife Department announced the mussels were found in Lake Travis in 2017. According to the TPWD and Texas Invasives, an online project maintained by the Lady Bird Johnson Wildflower Center, the species of mussels pose an ecological threat, damage boats, leave sharp shells along shorelines and threaten a city’s water supply by clogging pipes.
The cities of Cedar Park and Leander pull water from Lake Travis for their water supplies. In the spring, the cities plus Round Rock entered into an agreement with the Brushy Creek Regional Utility Authority to build a joint chemical treatment station to prevent zebra mussels from clogging their pipes.
According to TPWD, zebra mussels are a destructive invasive species that spread from one fresh water lake to another, frequently by traveling on boats and boat trailers. Native to Europe and Asia, the mussels were first observed in North America in Michigan and Ontario in 1988 and landed in North Texas lakes in 2009, according to Nonindigenous Aquatic Species, an online information resource for the U.S. Geological Survey. In 2017, TPWD announced that the species had spread to Lake Travis and other Central Texas lakes.
The species has a distinctive zebra-striped shell, and each can grow to about 1.5 inches wide. According to Texas Invasives, one zebra mussel can produce up to 1 million microscopic larvae, which can survive for days in water trapped in a boat.
It is currently required by Texas law to drain water out of a boat before leaving the water, said Marcos De Jesus, a district biologist for Inland Fisheries for the TPWD. He said the department has been working to teach the public to also clean a boat with high-pressure water and soap and let it dry for at least a week before moving to another lake that is not infested by the mussels.
“It’s really hard because you’re dealing with something you can’t see,” he said. “It’s microscopic in the form that it transfers.”
The mussels can cluster together by threads extending from underneath their shells, allowing them to attach to objects, surfaces or other mussels, according to the NAS. The species filters lake water, which can lead to increased water clarity, but has an environmental impact by hurting native aquatic life.
“If that food chain gets depleted because of the zebra mussels, other critters that rely on that food chain, like algae and small fish, will start getting impacted,” De Jesus said.
He said zebra mussels can be detrimental to a city’s water supply by colonizing the insides of water pipes and restricting the flow of water.
“I think that’s what the cities are worried about—having to maintain these intakes and preventing them from getting clogged from zebra mussels,” De Jesus said.
Part of Cedar Park’s and Leander’s water system is supplied by the Brushy Creek Regional Utility Authority, which was founded in 2007 by representatives from the two cities and Round Rock. The three entities were looking to plan a three-phase regional water system that would pull water from Lake Travis for the next 50 years.
The BCRUA began providing water from Lake Travis to Cedar Park and Leander in mid-2012. The utility authority has been finishing the design of Phase 1C of the project, which expands a water treatment plant and a floating raw water pump station in Lake Travis. Construction on Phase 1C of the project is scheduled for 2019-20.
The second phase of the BCRUA’s deep-water intake project will include the construction of the deep-water intake, a pump station and intake and transmission tunnels, according to utility authority documents. Final design of Phase 2 could be completed in early 2021.
BCRUA General Manager Tom Gallier said Cedar Park and Leander each have a floating intake station and water treatment plant that pull water from Lake Travis, and BCRUA's regional water treatment plant also provides drinking water into the city's systems.
In May, Leander City Engineer Wayne Watts told City Council that the mussels present a significant threat to the BCRUA’s floating raw water intake and other downstream treatment facilities.
“They are a tremendous detriment to anything that’s in the water, particularly our pipelines and our raw water barges,” he said.
Gallier said the Lake Travis water is conducive for the zebra mussels.
“They’re growing everywhere out there, even right now, even on the shoreline around the lake, people are noticing them,” he said.
JOINT TREATMENT STATION
Gallier said Cedar Park completed visual studies of the city’s underwater intake in April using remote cameras and divers. During an April BCRUA meeting, he showed a photo with clusters of zebra mussels attached to the intake.
“Now that doesn’t mean that we have a problem right now with them, but it’s like the canary in a coal mine—it shows that we have a problem already starting, and that’s why we’re trying to get this joint facility built and online as quickly as we can,” he said.
The cities of Cedar Park, Leander and Round Rock entered into an agreement with the BCRUA in April and May to start the process of chemically treating the entities’ water structures of zebra mussels. The entities will fund a $1.35 million joint chemical treatment station located in Cedar Park’s water treatment plant along Lake Travis.
The station will utilize sodium permanganate—a common chemical used for water treatment—that will prevent the attachment and growth of zebra mussels in the raw water intake structures.
De Jesus said the TWPD has noticed that lakes in Texas typically experience the worst of a zebra mussel infestation in the second and third summer after the mussels are discovered. He said this summer could be the height of the infestation in Lake Travis.
“So right now, we’re experiencing the year-after boom,” he said. “Everything that got infested last year, Canyon Lake, Lake Austin, Travis, those lakes are actually showing a boom this year. They’re starting to spread all over the place.”
Though with no way to rid the lakes of the species, he said treating pipes for the mussels will become a regular cost of pulling water from the lake.
“Eventually, those costs get passed down to the users, the consumers,” De Jesus said. “That’s where it really could get bad, when water bills start going up because there’s more money put into treating these intakes at the lakes.”
Gallier said the chemical treatment, maintenance and upkeep of the facility will become a regular part of costs for water customers moving forward.
“It will [add to residents’ water bills in the future] because it will be part of the ongoing cost of water treatment,” he said. “However, the reality is that these measures that we’re taking in the grand scheme of things are not horribly expensive, so it’s not something where people are going to see any kind of noticeable increase to water bills.”
Gallier said he hopes the treatment station will be in place by next spring.
In the meantime, De Jesus said residents should be conscious and spread the word on how to prevent the spread of zebra mussels, and not to let the mussels prevent them from utilizing the area’s natural resources.
“We hate to see people not enjoying the lakes and not using the resources because of [the mussels], it’s just a matter of doing the right thing after you use [the lakes],” he said.