When zebra mussels first arrived at Lake Texoma in 2009, the hope was the invasive species would be stopped at the Texas-Oklahoma border.
But five years later, officials realize that the tiny zebra-striped mussels, which can clog intake valves and leave shorelines littered with their razor-sharp shells, are likely to keep spreading across Texas.
The latest attempt to slow their march went into effect Sunday, when Texas Parks and Wildlife imposed new rules on 30 more Texas counties about cleaning, draining and drying boats before moving them to another lake.
The rules, which were already in effect in Tarrant County and across much of North Texas, now include Johnson and Ellis counties, stretching as far south as Travis County in Central Texas.
Boater traffic is believed to be the main way zebra mussels reached Texas after first showing up in Great Lakes nearly 30 years ago.
Earlier this year, one zebra mussel veliger, or larva, was found in Lake Lavon in Collin County.
Other lakes that have tested positive for zebra mussels are Ray Roberts, Lewisville, Texoma, Bridgeport and Belton.
Three other lakes — Grapevine, Fork and Tawakoni —have tested positive for zebra mussel DNA.
Lake Grapevine has had three positive DNA tests for zebra mussels, and there is concern that it is only a matter of time before mussels are found since the lake is close to both Lake Lewisville and Lake Ray Roberts, said Brandon Mobley, a natural resources specialist with the Army Corp of Engineers in Fort Worth.
“It is a very popular lake right in the middle of the Metroplex,” Mobley said. “We’re concerned both for its proximity and usage. It’s going to get exposed at some level. We’ve seen a couple of DNA hits, but we haven’t found any adults, we haven’t found any larvae.”
Besides concerns about North Texas lakes, there is also greater focus on preventing the mussels’ spread further south.
When Lake Belton in Central Texas tested positive, it got the attention of the corps, which maintains reservoirs all over Texas and is trying to increase awareness in areas that have yet to see zebra mussels.
“It was really an eye-opener for us,” Mobley said. “We’re moving past Central Texas, down to South Texas to try and get ahead of them.”
One of the concerns are popular lakes in the Texas Hill Country around Austin and San Antonio that attract boaters from all over the United States. The corps and Parks and Wildlife are working with commercial boat haulers and marinas to look for boats bought from out-of-state infested areas.
Signage has also been added at many lakes across Texas, including Eagle Mountain Lake and Lake Bridgeport.
Ken Kurzawski, program director with Parks and Wildife Inland Fisheries division, said the stage agency will be posting more signs at lakes and conducting more public awareness campaigns as the weather warms up this spring.
“We found that awareness of clean, drain and dry is pretty high among boaters in the DFW area, but we’ve got more work to do in Central Texas,” Kurzawski said.
New counties added
The rules that went into Sunday require all boats operating on public water in those counties to be drained after use. It includes all types and sizes of boats, including personal watercraft, sailboats or anything else used to travel on public waters.
The new counties that have been added include Archer, Bastrop, Bell, Bosque, Burnet, Clay, Comal, Comanche, Coryell, Eastland, Ellis, Erath, Falls, Fayette, Freestone, Hamilton, Hays, Henderson (west of SH 19), Hill, Johnson, Leon, Limestone, Llano, McLennan, Navarro, Robertson, Somervell, Travis, Wichita, and Williamson.
Besides Tarrant, other North Texas counties already under the rules include Collin, Cooke, Dallas, Denton, Fannin, Grayson, Hood, Jack, Kaufman, Montague, Palo Pinto, Parker, Rockwall, Stephens, Wise, and Young.
Zebra mussels are native to the Caspian Sea area of Asia. They are believed to have made their way to North America in the 1980s via the ballast water of a ship. They were first found in the Great Lakes region, and are known to have infested 29 states, including more than 600 lakes or reservoirs in the U.S.