The Texas Parks and Wildlife Department on Wednesday confirmed that invasive and destructive zebra mussels have now been detected in Lake Ray Roberts, north of Denton.
The discovery comes three years after the mussels invaded Lake Texoma.
""From an environmental and economic standpoint, this is very bad news," said Texas Parks and Wildlife executive director Carter Smith in an written statement. "We intend to continue working with our parners to do everything reasonably possible to try and prevent the further spread of this harmful invasive species."
The department has had an ongoing information campaign urging boaters to clean, drain and dry boats and trailers when moving from lake to lake to inhibit the spread of the zebra mussels, which are now present in more than 600 lakes and reservoirs in the U.S.
Lake Ray Roberts is only the second lake in Texas to be affected by the unwanted mollusk, which is believed to have spread to North America in the 1980s from the ballast water of an oceangoing ship.
TPWD regional inland fisheries director Brian VanZee said this is the first reservoir in the Trinity River Basin with a confirmed case of zebra mussels.
"The ones that have been found are only 1/8 to 1/4 of an inch in size, so that means they were likely spawned earlier this year," he said in a written statement.