From Texas to New York, freshwater sources are being invaded by a tiny but disastrous creature that no one seems able to stop.

“Zebra mussels are a plague,” says Lacey Steigerwald, who has watched as they have infested the Lakeway Marina on Lake Travis, where she works.

Smaller than a quarter, these mollusks can grow to densities that can reach more than 100,000 individuals per square meter. They are currently infesting more than 600 lakes and reservoirs across the United States including 17 in Texas. Besides Lake Travis, Lake Austin, Lake LBJ and Lake Pflugerville are also infested.

After being introduced, the mussels take over the waterways. They harm boats, clog pipes, damage water treatment plants and destroy ecosystems.

“They clog pipes like cholesterol. There is no limit to what they’ll attach to. Everything that sits in the water will be completely caked within a year,” says Steigerwald.

Morgan Klein, a sophomore at The University of Texas at Austin, was looking for a research topic and became fascinated by the zebra mussel problem. This summer she led a team of UT undergraduate researchers studying the severity of the infestation in the Austin area.

As the mussels grow, they eat at alarming rates. They filter out phytoplankton, small zooplankton, large bacteria and other debris, in the process upsetting the ecosystem’s balance. They have also been directly linked to the recent bloom in toxic blue-green algae apparently responsible for several dog deaths this year in Austin.