A multi-county regulation enforced by the Texas Parks and Wildlife Department requires boaters to drain water from watercraft when approaching or leaving public waterways. The reason? Zebra mussels.

Zebra mussels originated in Russia, spread to the United States in the 1980s and within 10 years colonized the Great Lakes and the Mississippi, Tennessee, Hudson and Ohio River basins. They became established in Texas in Lake Texoma in 2009 and have since been found in the Brazos River Basin, Lake Belton in Bell County, Bridgeport, Lavon, Lewisville and Ray Roberts. In other words, they reproduce rapidly.

“The biggest effect, and the thing we're trying to avoid, is any type of infestation in the basin,” said Judy Pierce, public information officer of the Brazos River Authority. ”They kind of attach to just about anything that they can to grow on, and that means they'll attach to the underside of boats, within wheel wells and just about anything.”

When introduced into a nonnative ecosystem, they consume nutrients that affect the food chain for fish and other aquatic life native to Texas. Additionally, the mussels will clog pipes that supply customers with drinking water. 

Adult zebra mussels colonize all types of living and non-living surfaces, including boats, buoys, docks, piers, plants and slow-moving animals such as native clams, crayfish and turtles. And, although they haven't been found in Young County, preventing the spread of the mussels solely depends on the boaters, who must drain their vessels after leaving a lake and inspect them before entering another.

In January, TPWD expanded the number of counties under the TPWD regulation from 30 to 47, including several in the Brazos River basin. Because the mussels are in a larvae stage after they are reproduced, they aren't visible to the naked eye, which makes them harder to detect on boats. This is why draining vessels is necessary to  prevent further infestation in other Texas lakes.