SAN ANTONIO – Invasive zebra mussels that are known to harm wildlife have been detected at Medina Lake and could spread to nearby waterways, according to the Texas Parks and Wildlife Department.
TPWD on Tuesday announced that the detection marks the first time zebra mussels have been found in the San Antonio River Basin.
They were detected on Feb. 11 when someone showed TPWD officials an image of a zebra mussel at a boat ramp near Haby’s Cove. Biologists soon after discovered two zebra mussels attached to rocks in the area near Red Cove Marina.
Another zebra mussel was found three miles upstream during a search by the Bandera County River Authority and Groundwater District on Feb. 24.
While no other zebra mussels were found, Medina Lake has been labeled as “positive” for zebra mussels. There has been no evidence of “a reproducing population,” TPWD officials said.
“This is the first detection of zebra mussels in the San Antonio River Basin and could result not only in impacts on infrastructure, boats, and other property but also in downstream spread within the basin and introductions by boats moving from Medina Lake to other nearby lakes,” Monica McGarrity, TPWD’s senior scientist for Aquatic Invasive Species, said in a news release. “Finding zebra mussels in a new river basin, unfortunately, means that they’ve most likely been transported there by boats, barges, or other equipment that didn’t take appropriate precautions to prevent their spread.”
TPWD officials also said that Lake Placid, near Seguin, has been designated as “fully infested.” It was previously labeled as “positive.”
Zebra mussel larvae and a single adult were first detected there in May 2019.
Lake Buchanan, near Austin; Richland Chambers Reservoir, near Dallas; Grapevine Lake, near Grapevine; and O.H. Ivie Lake, east of San Angelo, are also designated as fully “infested.
Canyon Lake has been designated as “infested” after zebra mussels were first found there in 2017.
Zebra mussels have a presence in 31 Texas lakes and five rivers.
In the San Antonio area, Lake McQueeney near Seguin and Lake Dunlap in New Braunfels also have tested positive for the species.
The zebra mussels are sharp, causing a hazard on the shorelines. They can also damage boats, hurt aquatic life and clog pipes, TPWD says.
Boaters can help stop the spread by removing debris from their boats, draining water and allowing gear to dry out.
According to TexasInvasives.org, boaters could face a $500 fine for the transportation or possession of zebra mussels if they do not clean, drain and dry their boats.