Zebra mussels eradicated from local drinking supply but survive winter weather
GEORGETOWN, Texas (KXAN) — While it isn't exactly lake weather, one creature is using the winter months to enjoy the waves: zebra mussels.
The invasive species first reached the United States by infesting the freezing waters of the Great Lakes and going dormant when temperatures dropped below 55 degrees.
There is some good news when it comes to zebra mussels, humans have found a few solutions.
"What we do is we charge them with a very light, very light electrical charge, just a low current charge. And basically there's copper rods inside these cells. And what that electrical charge does is it slowly dissolves the copper at a known rate," Bill Carr said, utility systems manager for the Brushy Creek MUD.
The utility installed the Fortress Mussel Control System after discovering zebra mussels in Lake Georgetown in 2017. The system uses copper rods to poison the mussels.
"Copper is toxic to zebra mussels at all stages," Carr said.
According to Carr, the team used this system plus copper-coated filters at the base of their intake pipes in Lake Georgetown. Copper released in the system also coats the inside of the pipes. Zebra mussels can not attach to copper.
The lake, Carr said, "absolutely has zebra mussels in it."
"Once they're established in a lake, you know, getting rid of them is just, it's just not very realistic," Carr said.
Texas lakes and the zebra problem
According to Texas Parks and Wildlife, 33 lakes in Texas are infested with zebra mussels, alongside seven river basins.
A spokesperson with TPWD said:
"Unfortunately, there are no good means by which we can eradicate zebra mussels from infested lakes, particularly the large river impoundments found in Texas. Chemical treatments are cost-prohibitive in most situations and have only proven effective in small (typically quarry) lakes with no/temporarily stopped outflow (and even those will require longer monitoring to truly verify eradication) and have failed in other situations for localized infestations or entire lakes."
One lake that was able to remove the mussels, Lake Waco. In 2021, TPWD reported that the mussels had been eliminated.
In that case, the mussels were only found in a small part of the lake. Officials were able to cover the mussels with a tarp, smothering them and preventing them from spreading.
According to TPWD, Lake Waco is still zebra mussel-free.
"The Lake Waco situation was extremely unique in that the infestation was caught extremely early, was highly localized (< 1 acre area), conditions were conducive to bottom barrier approach, and timing allowed barrier installation prior to spawning and production of free-floating, dispersing larvae," the spokesperson said.
Copper in the water
According to Carr, the copper system the Brushy Creek MUD is utilizing poses no threat to humans.
"No risk to humans whatsoever. In fact, there is a recommended daily allowance of copper that people need for health purposes."
The recommended daily allowance of copper for humans is 900 micrograms per day. The copper system used by the utility uses 10 micrograms per day.