Invasive zebra mussels found in Lewisville Lake

Posted Friday, Jun. 21, 2013  comments  Print Reprints

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Texas is begging boaters to “clean, drain and dry” their crafts to help fight the spread of zebra mussels after the destructively invasive mollusks showed up in Lewisville Lake.

The U.S. Geological Survey on Thursday confirmed the infestation in the third Texas lake — the second in the Trinity River basin — to fall victim to the thumbnail-sized marauders, less than a year after they were found in Lake Ray Roberts.

A live juvenile zebra mussel was found on a “settlement sampler” near the dam at Lewisville Lake, said Christopher Churchill, a USGS biologist who has been watching for them.

“My first thought was it was a little bit of a surprise to find it on the south side of the lake by the dam,” he said. “We would expect to see signs of the organism on the north side of the lake, coming in from the downstream flow from Lake Ray Roberts. We’ve found settlement of the larvae there before.”

More than a few zebra mussels have to get together before a colony can start, and Churchill said that it is significant that only one mussel was found. But it wasn’t unexpected.

“Future research, continued surveys are necessary to determine if zebra mussels are able to establish a reproducing population in Lewisville Lake,” he said. “We’ve known for a while that Lewisville Lake was susceptible to infestation. It has a very high amount of transient boat traffic, compared with other lakes.”

Dangerous for their ability to clog public-water intake pipes and harm boats and motors with their razor-sharp-edged shells, zebra mussels have significant economic and recreational impacts, a Texas Parks and Wildlife Department news release said.

The mussels also deprive fish — including bass and catfish — of their food, officials said.

Owners are urged to clean all mud, algae and other debris from boats and trailers after operating them, as well as draining and drying everything, before launching into other bodies of water. The parks department requires anglers and boaters to drain all water from their boats — including live wells — before leaving lakes Texoma, Lavon, Ray Roberts and Lewisville.

The first zebra mussels in the U.S. hit the Great Lakes in the 1980s and were believed to come from ships that originated in the Black Sea. They’ve since invaded 23 states, including the Mississippi River basin and 10 lakes in Oklahoma.

They arrived in Lake Texoma in 2009 and before long their signature striped shells virtually filled every bay. Low levels of zebra DNA larvae have been found in Eagle Mountain Lake and Lake Bridgeport, but those lakes have yet to show evidence of the mussels themselves.

For brochures, wallet cards or posters about zebra mussels, email

This report includes material from the Star-Telegram archives.

Slowing down zebra mussels

• Clean all vegetation, mud, algae and other debris from the boat and trailer before leaving the lake.

• Drain all water from the motor as well as the live well, bilge, bait buckets and any other compartments or systems that hold water before leaving the lake.

• Dry the vessel and associated equipment for a minimum of seven to 10 days during the months of May through October or for 15 to 20 days from November through April. Drying times are approximate, and conditions such as lower air temperatures, higher humidity and whether the vessel is kept in dry storage should be considered.

• For more information, go to

Source: Texas Parks and Wildlife Department

Terry Evans, 817-390-7620 Twitter: @fwstevans

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