As more and more picnic tables and iron grills began to emerge from the flooded waters of Ray Roberts Lake, rangers at the Isle du Bois unit of the state park noticed some new additions to the infrastructure.
Cathy Milliger, a seasonal employee with the park, scraped her hand under one of the aluminum picnic tables on Tuesday morning. She lifted up her hand, and piled high in her palm were dozens of tiny zebra mussels, all about the size of a black-eyed pea.
“What surprised us was how difficult they are to get off. They are on everything,” she said, examining the pile of mussels.
“The picnic tables that were under water for any length of time have them all over them. The limbs and stuff that were in the water, it looks like it’s a zebra mussel plant. It’s incredible how damaging they are.”
Zebra mussels, an invasive species, have been spreading across the United States for decades and are beginning to show up in more and more lakes across Texas, according to Bryan Daniels, a Texas Parks and Wildlife resource specialist at Ray Roberts Lake State Park.
Zebra mussels were first found in Ray Roberts Lake in 2012. Experts believe the pests hitched a ride to Ray Roberts on a boat that had been on Lake Texoma.
The mussels out-compete native freshwater mussels and build up in massive numbers around a lake. Scientists haven’t found a good way to remove them, either, according to Jason Schooley, assistant superintendent at the Isle du Bois unit.
“Once they’re here, they’re here. They haven’t figured a way to get them out. There’s no remedy for this at this point, at least no cost-effective ones,” he said while driving his truck around the campgrounds. “Over time they’ll go away, just like any other shell. They’ll disintegrate over time as people walk on them.
“But, they won’t go away as far as the lake is concerned. They don’t have a method for getting them out of the lake.”
Daniels said chemicals were used in 2012 to try and reduce the mussels, but that wasn’t cost effective — or effective at all, for that matter. The mussels are filtering organisms, and the lake’s water is clearer as a result. That may make for better bass fishing, but the mussels’ presence will have a negative effect over time.
“In the long run, it’ll actually be worse because different plant species will be able to grow and colonize different areas,” Daniels said. “It’ll change the whole structure of the water column because light can penetrate deeper into the lake.”
Park employees have been working for “weeks and weeks,” Milliger said, to clean off the mussels from everything that was under water. They have cleaned mussels from tables, grills, electrical outlets, trees, shrubs and bathrooms.
When the mussels are wet and alive, they are extremely difficult to remove. Rangers must use a power washer and scraper to get them off a surface. After they die and dry off, they can be removed by hand — although they can be dangerous to walk on.
“There’s one right there,” Milliger said. “Feel how sharp that is, if you were to step on that. Think about a bunch of those. They can definitely cut your feet.”
Park employees are doing their best to remove the mussels from the areas of the park that have dried out, Schooley said. “They won’t be able to remove them all at once, though.
“As they are out of the water they’ll die and they’ll dry up,” Schooley said. “As you saw, [Milliger] was able to pull them off with her bare hands. If they were alive, that wouldn’t even be an option. You’d have to use a tool and gloves and all that stuff.
“Down in our day-use area we are cleaning up as best we can, as much as we can. But it’s like confetti; you can’t get all of it. It’s not going to be completely gone.”
It’s yet to be seen if zebra mussels will fade away over time. But both Schooley and Milliger agreed that as long as people keep spreading the pests by not cleaning their boats and water vessels, they aren’t going anywhere anytime soon.
“Other lakes, like Texoma, are also infested with zebra mussels pretty bad. I don’t know if we are the worst one, but apparently it doesn’t take long. Just one person bringing their boat to an unaffected lake could start it,” Milliger said.
“We need people to be diligent about when they pull their boats out to clean, drain and dry and do it every time you take your boat out.”