Zebra mussels 'no longer a concern' for Brushy Creek water thanks to copper system

GEORGETOWN, Texas (KXAN) -- The Brushy Creek Municipal Utility District said it's no longer worried about an aquatic invader that has taken over dozens of lakes across Texas.

Worry over zebra mussels is a thing of the past for the area, as the species has been eradicated from Lake Georgetown, according to Brushy Creek MUD Facilities Manager Bill Carr.

In a press release issued Thursday, Carr credited the disappearance of the invasive mollusks to the copper ion generation system installed at BCMUD's water intake facility at Lake Georgetown in 2022.

Since the completion of the system's installation, Carr said there is now enough proof of its effectiveness to warrant peace of mind.

“BCMUD now has two years of data showing that we do not have zebra mussels in our system,” he said. “Before that, when we were implementing the sodium permanganate system, when we’d drain our pond to clean it, it was completely infested with zebra mussels.”  

Carr said before the copper ion system, the infestation was so ubiquitous that no metal was visible on the screens between BCMUD’s raw water pond and its water treatment plant, and the walls of the raw water station that pumps water into the District’s Water Treatment Facility were completely covered with zebra mussels.  

“Now, we have none,” he said. 

According to BCMUD, a recent report from the Brazos River Authority said copper ion generator systems work by allowing low doses of copper solution where districts and entities like BCMUD draw water from sources such as Lake Georgetown. 

Through the copper ion system, Carr said they’re able to render the zebra mussels harmless at a dose of under 10 µg/L, or parts per billion (ppb), of copper, and explained the Environmental Protection Agency (EPA) has set the maximum contaminant level (MCL) in drinking water for copper at 1,300 ppb.  

Carr also said BCMUD regularly tests the water at its treatment plant for added safety.

History of zebra mussel invasion, treatment efforts

According to the Texas Parks and Wildlife Department, zebra mussels were first found in Lake Texoma in 2009 and have since fully infested 33 Texas lakes as of summer 2024, including Lake Georgetown and Stillhouse Hollow Lake, BCMUD’s two largest water sources.

The invasive species can clog water intake systems, disrupt ecosystems, and contaminate water, resulting in foul-smelling water for thousands of homes at a time, per TexasInvasives.org. They can also impose significant costs on utilities -- and subsequently, taxpayers -- that can amount to millions of dollars. 

Zebra mussels were first noticed at Lake Georgetown in 2017. The BCMUD started feeding sodium permanganate at the Water Treatment Facility in 2018 in an attempt to combat the invasion and keep the mussels out of the raw water pond and all of the piping infrastructure at the facility, according to Carr.

That method proved less effective than Carr would have liked, the press release stated. For the next two years, he and his team tried several other chemical-based methods, but he said none were as effective as the copper ion system. 

Carr also said the high price tag of $783,000 for the system is worth it, and it saves money for the MUD in the long-term.

“The first set of copper rods used in the copper ion system lasted us almost 18 months at a cost of about $4,500 a piece,” Carr said. “Previously, we were spending $4,500 every two months on chemicals. In the long term, the cost savings are enormous.”

According to BCMUD, Austin Water has also been working to install copper ion systems in three of its major intakes since an infestation in 2019 took hold at the Ullrich treatment plant that draws water from Lake Austin.

The release from BCMUD stated Julie Hollandsworth, Austin Water operations and maintenance division manager, said that's still the plan, but there have been hurdles because of the size of the city's water operation and equipment delays from the manufacturer.