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Zebra mussels invade Lake Ray Roberts
Published: Friday, July 20, 2012 4:02 PM CDT
The invasive mussel species that closed off Lake Texoma's water supply three years ago has been found in Lake Ray Roberts, the Texas Parks and Wildlife Department announced Wednesday.
Zebra mussels reproduce rapidly and attach to hard surfaces, latching onto one another to form massive clusters. While not toxic to drinking water, they are known to clog water intake pipes and boat motors, creating expensive maintenance issues for water utilities and boaters.
Lake Ray Roberts lies north of Denton. While the only drinking water pumps at the lake are owned by the city of Denton, water flows downstream through the Trinity River Basin to Lake Lewisville, which provides water to Lewisville, Flower Mound and other Upper Trinity Regional Water District member cities.
This flow has put Lake Lewisville directly in the crosshairs of downstream-flowing zebra mussel larvae, said Brian Van Zee, regional inland fisheries director for Texas Parks and Wildlife.
"What that means is, Lake Lewisville and other sections of the Trinity River downstream are at pretty high risk of seeing an introduction of zebra mussels, as well," he said, "and obviously they have a lot of environmental, economic and recreational impact."
Tom Taylor, UTRWD executive director, said the district expects mussels at Lewisville at least within the next few years. The lake's intake, co-owned by the city of Lewisville and the water district, is fitted with screens and an air-blasting system intended to push away mussels, debris and other species. But residents can expect their water bills to go up as the mussels multiply and increase maintenance costs.
"We'll be monitoring it. We'll be alert," he said. "We'll be examining what other people do who face this problem. ... This is giving us a heads-up, and so we have time to prepare."
The discovery, the second of its kind in Texas and the first in the Trinity River Basin, makes it more important for boaters to follow the proper procedures of cleaning, draining and drying their boats before entering any Texas lake, especially after visiting mussel-infested waters such as Ray Roberts and Texoma, Van Zee said.
"That's the most effective thing that we can do in terms of trying to educate the boaters and anglers," he said. "The clean, dry, drain message is something every boater should be doing anyway."
Water sources used by cities such as Plano, Allen, Frisco and McKinney will not be immediately impacted by the find, Van Zee said. While those reservoirs, including Lake Lavon and Jim Chapman Lake, are also in the Trinity River Basin, they are on the east fork of the river and will not be in the direct path of migrating zebra mussels.
However, it is of the utmost importance that boaters follow proper cleaning procedures if they want to keep it that way, said North Texas Municipal Water District spokeswoman Denise Hickey.
"What you would want is to minimize the spread of the zebra mussel or any invasive species," she said. "To do that, our boaters and our anglers need to properly clean, drain and dry."
James Kennedy, an environmental scientist at the University of North Texas, said it is not yet known how established the species is at Ray Roberts, and environmental differences at each lake will factor into how prevalent the mussels become in the basin as a whole.
While the relative newness of the species to the North Texas environment makes it hard to predict how well it will thrive, the mussels are likely to start showing up in other waters given the amount of boat traffic in the area and connectivity of Ray Roberts to other waters, Kennedy said.
"Based on what we've seen in the rest of the country, we're not going to eradicate these guys," he said. "I don't think there's much we can do to control them other than trying to prevent their spread to other lakes. In one sense, I think its almost inevitable that's going to happen."
Carole Bassinger, director of public works for the city of Lewisville, said while no specific plan is in place in the event of the mussels' appearance, the city would have to find a way to protect its intake structures if the species does appear.
"There's nothing we can do at this point except ask people to follow the recommendations on keeping your boats clean," Bassinger said.
It is unknown how the species ended up at Ray Roberts. It was most likely introduced by a boat that had recently been to Texoma and not been properly cleaned, according to the release. The samples discovered were an eighth- to a quarter-inch in size, suggesting they were spawned earlier this year.
Three small mussels have already been found immediately downstream of the Ray Roberts dam, suggesting some mussels may have already entered the river and are headed for Lake Lewisville, Van Zee said.
For information on how to properly clean, dry and drain your boat to prevent the spread of invasive species such as zebra mussels, visit www.texasinvasives.org.