AUSTIN — Stillhouse Hollow Reservoir is the latest Texas lake to become infested with zebra mussels, according to the Texas Parks and Wildlife Department (TPWD). Fisheries biologists recently confirmed the presence of the invasive aquatic species after an attentive boater and his family found what they believed to be zebra mussels attached to a submerged rock and reported the sighting.

“The family was aware of zebra mussels through our extensive public outreach campaign, had seen them previously on Lake Belton and knew they were an invasive species,” said Brian Van Zee, Inland Fisheries Regional Director for TPWD. “Because the family promptly took action and reported the sighting, we were able to locate and document the infestation.”

The rapidly reproducing zebra mussels, originally from Eurasia, can have serious economic, environmental and recreational impacts on Texas reservoirs. Zebra mussels can clog public-water intake pipes, harm boats and motors left in infested waters, cover anything left under water and litter beaches with their sharp shells.

Stillhouse Hollow is a U.S. Army Corps of Engineers reservoir on the Lampasas River in the Brazos River basin, 5 miles southwest of Belton, Texas. On July 25, TPWD inland fisheries staff surveyed six locations throughout Stillhouse Hollow Reservoir and documented zebra mussels at all six sites, confirming that the lake is infested.

“Currently, the density of zebra mussels on Stillhouse Hollow isn’t as high as it is on Lake Belton, but it appears to be a fairly new and developing population,” said Van Zee. “Several sizes of zebra mussels were documented which indicates that it is a viably reproducing population”.

“While this is discouraging news for Stillhouse Hollow Reservoir, the good news is that boaters are becoming more aware of the importance of practicing ‘Clean, Drain and Dry’ and are helping us detect zebra mussels more quickly when they are spread to a new lake,” he noted.

Since zebra mussels were first found in Texas in 2009, seven lakes in three river basins are now fully infested, meaning that they have an established, reproducing population. Zebra mussels have been found on occasion in six other Texas lakes but at this time it is uncertain if those lakes have a viable reproducing population. See the TPWD web site for details on affected water bodies.

In Texas, it is unlawful to possess or transport zebra mussels, dead or alive. Boaters are required to drain all water from their boat and on-board receptacles before leaving or approaching a body of fresh water in order to prevent the transfer of zebra mussels that might be inside. Zebra mussel larvae are microscopic and can survive for days in water transported from a lake. The requirement to drain applies to all types and sizes of boats whether powered or not: personal watercraft, sailboats, kayaks/canoes or any other vessel used on public waters. Movement from one access point to another on the same lake during the same day does not require draining.

TPWD and a coalition of partners have been working to slow the spread of zebra mussels by reminding boaters to clean, drain and dry their boats, trailers and gear before traveling from one waterbody to another. The partners in this effort include: North Texas Municipal Water District, Tarrant Regional Water District, City of Dallas Water Utilities Department, Trinity River Authority, San Jacinto River Authority, Sabine River Authority, Brazos River Authority, Guadalupe-Blanco River Authority, Lower Colorado River Authority, Upper Trinity Regional Water District, Water Oriented Recreation District of Comal County and the Lady Bird Johnson Wildflower Center.

More information about zebra mussels can be found online at www.texasinvasives.org/zebramussels.