Invasive zebra mussels have been discovered in Grapevine Lake, a popular outdoor recreation destination located in the Dallas-Fort Worth metroplex.
On June 22, a team led by Christopher Churchill, PhD, from the United States Geological Survey (USGS) Texas Water Science Center found a juvenile zebra mussel attached to a sampler on the southern end of the reservoir. In addition, plankton samples collected by the USGS in May revealed the presence of a microscopic larva. Follow up surveys conducted by TPWD at marinas and along the shoreline failed to document any additional juvenile or adult zebra mussels. Thus, it appears this is a new introduction and both agencies will continue monitoring the lake closely.
“With the boating season in full swing and the busy Fourth of July holiday right around the corner, it’s very important for all boaters to understand that if they are going to be enjoying the lake they need to clean, drain and dry their boat and equipment every time they leave the water – it’s not just the right thing to do, it’s the law,” said Brian Van Zee, TPWD inland fisheries regional director.
Currently throughout the Trinity River Basin, one lake is classified as suspect, meaning zebra mussels or their larvae have been positively identified one time in the lake (Lake Ray Hubbard), five lakes are now classified as positive, meaning zebra mussels or their larvae have been documented more than once (Lakes Grapevine, Lavon, Richland Chambers, Worth and Fishing Hole Lake) and five more lakes are classified as infested, meaning they have an established, reproducing population (Lakes Bridgeport, Eagle Mountain, Lewisville, Livingston and Ray Roberts).
Grapevine Lake is managed by the U.S. Army Corps of Engineers, Fort Worth District. Primarily built for the purposes of flood control and conservation, the lake is also popular as a boating, hunting, and fishing destination.
“Zebra mussels shouldn’t deter anyone from visiting and enjoying the water this summer,” Van Zee said. “But preventing the spread of zebra mussels needs to be a priority for everyone –regardless of which lake you’re visiting. Please remember your wet equipment should be properly cleaned, drained and dried after use and if you are moving your boat from a slip on a lake known to have zebra mussels, then please contact TPWD at (512) 389-4848 or email [email protected] so we can provide guidance and support to reduce the risk of spreading zebra mussels.”
The rapidly-reproducing zebra mussels can have serious economic, recreational and environmental impacts on Texas reservoirs and rivers. Zebra mussels can harm native freshwater mussels and other aquatic species, affect water clarity and cause harmful algal blooms, cover shoreline rocks and litter beaches with sharp shells, clog water intakes, damage or increase maintenance on hydroelectric and other facilities using raw surface water, and damage boats and motors left in infested waters.
As of June 2018, in Texas, 14 water bodies in five river basins are listed as infested with zebra mussels, six water bodies are listed as positive – including Grapevine Lake- and three water bodies are listed as suspect for having zebra mussels.
TPWD and partners will continue monitoring high risk lakes in Texas, installing signage and reminding boaters to clean, drain and dry their equipment when leaving public boat ramps.
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 onboard receptacles before leaving or approaching a body of fresh water to prevent the transfer of zebra mussels and other invasive species. Zebra mussel larvae are microscopic and both adults and larvae can survive for days in or on boats 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.
More information about zebra mussels can be found online at tpwd.texas.gov/ZebraMussels. Photos of the juvenile zebra mussel found at Grapevine Lake can be found on Flickr here.