Zebra mussels at Lake Brownwood will be 'an extremely big issue' says official

Steve Nash
Brownwood Bulletin
Zebra mussels have been detected at Lake Brownwood. This photo is from the website https://lakes.grace.edu/

John Allen, general manager of the Brown County Water Improvement District, recalled the “kick in the gut” he felt when the Texas Parks and Wildlife detected zebra mussel larvae in Lake Brownwood.

The agency reported the discovery in an April press release.

“We were hoping, against all odds, maybe there’s something in our water that won’t let them grow to adults,” Allen said.

“But now that we’ve actually found some, it looks like our water will sustain them.”

Allen was referring to a Lake Brownwood boat owner’s discovery of two juvenile mussels on one of the vessel’s pontoons while it was being cleaned at a car wash.

“He actually brought them to us,” Allen said. “We retrieved them, confirmed with Inland Fisheries out of Abilene that that’s what they were. This boat has never been in any other water but Lake Brownwood. So that’s a pretty good indication that where they came from. They had to be out of Lake Brownwood.”

Though small — about 1.5 inch — zebra mussels are “a highly invasive, non-native species that cause damage to boats as well as to infrastructure for water supply and control and other facilities using raw surface water,” Monica McGarrity, senior scientist for aquatic invasive species at the Texas Parks and Wildlife, said in the April press release. 

“Zebra mussels also negatively impact the ecosystem, competing with native filter feeders and altering the food web and attaching to and harming native mussels. Their razor-sharp shells can litter shorelines and cover underwater hard surfaces, posing a hazard for humans.”

Allen said the district will need to prevent the mussels from clogging up Lake Brownwood’s pipelines and pump stations — and that will be expensive.

A single adult female can produce a million offspring in a year, Allen said.

“It  will be an extremely big issue before it’s over,” Allen said. “Once you have them, there is really nothing you can do as far as getting rid of them in lakes like this. What we have to focus on now is protecting our infrastructure — our pipelines and our pump stations — which will end up being some kind of chemical treatment  to the water coming to town, just to keep the zebra mussels from sticking to the pipes, clogging everything up.”

Those steps will need to be taken “in the very near future,” Allen said. “I have the engineers looking at it right now.”

Allen said it may cost the water improvement district “a couple of million dollars” to protect the infrastructure. It will become an ongoing expense “just for the chemicals every year to keep treating the water, to keep them from affecting our infrastructure,” Allen said.

Zebra mussels are are native to the the seas of Eastern Europe and were first discovered in the Great Lakes in the 1988. It is believed the mussels arrived in the ballast water of ocean-going ships, according to www.usgs.gov.

The Texas Parks and Wildlife said its Inland Fisheries Division collected mussel plankton samples at two sites, approximately 3 miles apart, at Lake Brownwood in November, according to a news release issued in April.

Those samples led to the detection of zebra mussel larvae, with no adult zebra mussels found at that time, according to a spokesperson with Parks and Wildlife.

The agency has asked the public to be on the alert for zebra mussels at Lake Brownwood on boats, rocks, docks and other hard surfaces. Anyone spotting them was asked to notify the agency at AquaticInvasives@tpwd.texas.gov with photos.

Zebra mussels attach firmly to hard surfaces and have triangular shells, often with tan/brown stripes and grow to approximately 1.5 inches long, the agency said.

Lake Brownwood was the second lake in the Upper Colorado River Basin where zebra mussels have now been detected, which indicates this species is continuing to spread westward, the Parks and Wildlife said.

Allen said, “Austin’s dealt with this for years. I’ve talked to a lot of people down there. I’m going to visit with them more next week.”

One adult zebra mussel can filter 1 liter of water a day.

“Once you get them they start growing pretty quick," Allen said. "In most lakes that get them, the lakes actually really clear up. You may be able to see 10 or 12 feet deep in  most parts of the lake.

“But what that starts affecting is your small fish that use some of that same material to eat. That material’s no longer there, which eventually will affect your bigger fish population also.”

Once the species is in a lake, “there’s nothing you can do to get rid of them,” Allen said.

While substances including chlorine bleach and copper sulfate will kill the mussels, they will also killed the fish. “So you can’t really treat the whole lake like that,” Allen said. “It’s just impossible."