Zebra mussels and how they spread
In 2017, zebra mussels were first found in Canyon Lake by the Texas Parks and Wildlife. Fisheries biologists say once zebra mussels are in a body of water, they spread rapidly, and boats are to blame.
The mussels attach themselves to boats and hang on to those not adequately cleaned, drained, and dried. Once that boater enters a new body of water, the zebra mussels enter the water and begin reproducing.
According to the Texas Parks and Wildlife, 28 texas lakes are considered infested with zebra mussels.
“When they grow, they clog up pipes. They get all over boats. They just basically destroy infrastructure,” said John Tibbs with the Texas Parks and Wildlife.
That is a huge problem for places like Canyon Lake, where the lake is the community’s water source.
The mussels clogged a water intake pipe belonging to Canyon Lake Water Service Company in 2019. The infestation choked water pipes, dropping production by over 50%.
“The fact is that they can smother things and anything that’s in the water.” – Mukhtar Farooqi, TPWD
Smothering Technique
Ironically, smothering is exactly the strategy that got rid of zebra mussels in Lake Waco. Biologists say they didn’t have much of a chance to succeed when they first started the project, but they went ahead with it anyway. The mussels were found in Lake Waco in 2014. They fell off a barge that Tibbs said was put in the water despite showing obvious signs of having zebra mussels attached.
Biologists in Waco knew the threat of zebra mussels, which is why weeks before they were discovered in Lake Waco, Parks and Wildlife actually trained city staff on how to spot them. They were found by a lone pair of eyes who saw the mussels in the water, and that is how this whole experiment started.
“We defined an area, and the decision was made to put tarps all over the bottom of the lake here to smother out the sea mussels. They require oxygen to live. They require food to be taken from the water. And so if they were smashed to the bottom of the lake, they’re not going to be able to do any of that,” Tibbs said.
The mussels were found right at the shoreline. An area of the lake about the size of a football field was covered in tarps held down by sandbags. The technique was the idea of a Waco city employee.
“We gave it kind of out of a 10% chance of success, but it was the city’s money. So we help. And he was right. It worked,” says Tibbs.
Six months after laying the tarps, scientists pulled them up and found one zebra mussel. Years later, they have yet to find any more. How do they describe the success?
“Lucky would be one word I would use” - Michael Baird, fisheries biologist, TPWD
Here’s why. The mussels at Lake Waco were caught early. There were only about 75 of them at the time, all adults, and they hadn’t reproduced yet.
“It was caught just in the nick of time for that technique to work,” says Mukhtar.
Most often, by the time the mussels are discovered, there are far too many to control. That’s the case at both Canyon and Medina lakes. Chemical removal of the mussels would negatively affect the environment, potentially killing off other wildlife. Not to mention, “it’s going to be hugely expensive, a lake of this size, to put chemicals in there. And so not only is it environmentally damaging, it’ll be very expensive,” Mukhtar said.
At Canyon and Medina lakes, it is about learning to live with them. Mother Nature helps out somewhat on Medina Lake, where the water is low.
Current levels are down by 57 feet. In areas where the water dries up, the mussels will die.
“The lake level going up and down like that certainly could aid in slowing the population, and maybe they won’t reach a variable level. They may not reach the just massively high infestation levels that we see on lakes like Travis and Canyon,” said Monica McGarrity, senior scientist for aquatic invasive species for the Texas Parks and Wildlife.
Changes had to be made at Canyon Lake to deal with the infestation. Canyon Lake Water Service Company enlarged its infrastructure, making it big enough for divers to inspect and remove any mussels they find.
Clean, Drain, Dry
Larry Jackson with the Canyon Lake Water Service Company said, “Now, we actually have a brush that goes down into the casing and will clean out all of the debris or any kind of zebra mussels and push them out back into the lake.” The water company also switched to copper for some of its equipment, but the biggest solution is to “clean, drain and dry” your boats.
“Check your boat over, particularly if it’s in a slip and it’s been in there a long time. You really need to clean it,” says Tibbs.
Monica McGarrity echos that proper cleaning is crucial.
“Drain all the water from every compartment a lower the motor. Get all the water out of that. And then when you get home, open everything up and let everything dry out, preferably for a week.”
“That’s for lakes in general. When you know that it’s a zebra mussel-infested lake like this one, that makes it even much more important to make sure that there’s no water on board,” Mukhtar said.
That way, these critters can’t stay on board either.
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