With the discovery this summer of zebra mussels in Lake Ray Roberts in Denton County, officials fear it is only a matter of time before the invasive species is found downstream in Lewisville Lake and then transported by boaters to other lakes across North Texas.The mussels, which settle on just about any hard surface and litter shorelines with their razor-sharp shells, have proved to be a headache as they've slowly moved across the U.S since first being found in the Great Lakes in the 1980s.Now that zebra mussels are in Lake Ray Roberts -- the assumption is they got there by hitching a ride on a boat from Lake Texoma or some other infested lake -- there's nothing stopping them from drifting down the Elm Fork of the Trinity River. They would first reach Lewisville Lake and eventually go all the way to Lake Livingston north of Houston. They were also found in Lake Ray Hubbard, just east of Dallas."The concern now is that it puts Lake Lewisville at the threat of infestation," said Robert McMahon, professor emeritus of biology at the University of Texas at Arlington who has been sampling at area lakes. "With boater movement, it could then easily move to other North Texas lakes."Zebra mussels, which are named for their distinctive striped pattern, can wipe out native mussels and mess up a lake's ecosystem. They first showed up in Texas at Lake Texoma in April 2009, where they quickly filled bays with shells. Last year's drought killed off a number of the mussels when the lake's water level dropped, but they're still found in large number in the lake.Divers also checked Lake Grapevine last week but haven't reported finding any zebra mussels. The Army Corps of Engineers and Texas Parks and Wildlife Department are trying to stop the spread with boater-education pamphlets and signs posted at area lakes.Not in Tarrant CountySo far, zebra mussels haven't been turned up in any Tarrant County lakes, though testing last fall showed low levels of DNA larvae in Eagle Mountain Lake as well as Lake Bridgeport in Wise County, which are both Tarrant Regional Water District reservoirs.Testing this summer, however, found no mussels or larvae in those lakes."I think almost all of the lakes we use to supply water are vulnerable, including Arlington, Benbrook, Eagle Mountain Lake, Bridgeport and Richland-Chambers in East Texas," said David Marshall, the water district's engineering services director. "Only Cedar Creek in East Texas may not have the proper water chemistry for them to thrive but that remains to be seen."Tarrant Regional, which provides raw water to 98 percent of Tarrant County, has already allocated $683,100 to plan for zebra mussels in its $2.3 billion integrated pipeline project with the city of Dallas. That pipeline will bring more water from Richland-Chambers and Cedar Creek Lake to the Metroplex, but its first phase isn't expected to be completed until 2020.Fort Worth officials are waiting for a report from Tarrant Regional about possible zebra mussel effects. They expect the creatures will eventually reach city-owned intake valves at Eagle Mountain Lake and Lake Worth."We're very concerned," said Fort Worth Water Department spokeswoman Mary Gugliuzza.Effects already seenThe impact of zebra mussels can be already seen for customers of the North Texas Municipal Water District, which serves Dallas suburbs, including Frisco, Plano and Richardson. A $270 million pipeline is being rushed to completion to take water from Lake Texoma to the North Texas Municipal district's treatment plant so it can bypass Lake LavonThe pipeline was fast-tracked after water transfers from Texoma to Lavon were stopped once zebra mussels were found in Sister Grove Creek, which had been used to transfer water from Texoma downstream to LavonLast week, Texas Parks and Wildlife held a meeting with stakeholder groups to plan for the eventual spread of zebra mussels. Most Metroplex water providers and some cities attended. Even Houston sent a representative with the concerns about Lake Livingston."I don't think there's an expectation we can stop them," said Brian Van Zee, inland fisheries regional director at Texas Parks and Wildlife. "Trying to stop that leap from the Trinity to another basin is probably our biggest effort right now because they could easily jump to other basins to the east or the west like the Brazos at Possum Kingdom or Lake Granbury."The mussels are believed to have been brought to North America from the release of ballast water from ships that came from the Black Sea, according to the U.S. Geological Service.Zebra mussels have been found in 23 states, including the Mississippi River basin. In Oklahoma, they have been found in 10 lakes, and they are in three Texas lakes.Bill Hanna, 817-390-7698Twitter: @fwhanna
Slowing the advance of 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 www.texasinvasives.org.
Source: Texas Parks and Wildlife