Invasive zebra mussels were discovered in Grapevine Lake by a team from the Texas Water Science Center.
On June 22, Christopher Churchill, Ph.d, from the United States Geological Society and his team found a juvenile zebra mussel attached to a sampler on the southern end of the reservoir. Plankton samples collected in May also revealed the presence of a microscopic larva.
Follow up surveys conducted by the Texas Parks and Wildlife Department at marinas and along the shoreline failed to find additional zebra mussels, so the department says "it appears this is a new introduction and both agencies will continue monitoring the lake closely."
A biologist with the Texas Parks & Wildlife Department said he expects to see more by the end of summer or the fall.
"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.
The Parks and Wildlife Department even offers a how-to video:
Only one lake - Lake Ray Hubbard - throughout the Trinity River Basin is currently classified as suspect, meaning zebra mussels or their larvae have been positively identified once before.
Five lakes, including Grapevine Lake, are currently classified as positive, meaning the mussels or their larvae have been documented more than once.
Five other lakes are classified as infested, meaning they have an established, reproducing population.
Grapevine Lake is managed by the U.S. Army Corps of Engineers, Fort Worth District. While it was primarily built for the purposes of flood control and conservation, the lake also serves 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 firstname.lastname@example.org so we can provide guidance and support to reduce the risk of spreading zebra mussels."
The department also offers an advice video for zebra mussels:
Zebra mussels can have serious economic, environmental and recreational impacts on reservoirs and rivers, due to their rapid rate of reproduction. They can harm native freshwater mussels and other species, affect water clarity, and cause harmful algal blooms, cover shoreline rocks and litter beaches with sharp shells, among other things.
As of of June 2018, 14 total bodies of water in five river basins across the state are listed as infested with zebra mussels.
The Parks and Wildlife Department and other agencies will continue to monitor high risk lakes in Texas, installing signage and reminding boaters to follow the law.
It is illegal to possess or transport zebra mussels, dead or alive, in the state. Boaters are required to drain all water from their boat and on-board receptacles before leaving or approaching a body of fresh water to prevent transferring any invasive species.
These mussels can survive for days. The requirement applies to all types and sizes of boats.
More information about zebra mussels can be found online.