SAN ANTONIO – Think of it as a liver transplant.
The San Antonio River Authority is reintroducing 5,000 freshwater mussels into the river over the next month or two, generally between Interstate 10 and a little below Loop 410 on the South Side.
SARA and the U.S. Fish and Wildlife Service said it’s a first-of-its-kind conservation effort in Texas.
Unlike the invasive zebra mussel, the yellow sandshell is a native mussel that hasn’t existed in the city’s waterway for several decades, but could help with biodiversity and filter harmful bacteria out of the water.
Though they’ll go into the water at about three-quarters of an inch in size, the yellow sandshell can grow to about five-and-a-half inches. Mussels — sometimes called the “livers of the river” — can filter about 10 gallons of water a day on average.
“We have a number of different spots throughout the river that we know are healthy for these mussels to come into — or to live in,” said SARA Environmental Sciences Manager Shaun Donovan. “And, you know, the water quality in the river is so good that mussels can live here. And so, while mussels will improve water quality, we wouldn’t be here today if the water quality wasn’t already good.”
The river authority plans to add pimplebacks, pistolgrips, and threeridge mussels in the future, as well
SARA finds pregnant mussels downstream in Karnes and Goliad counties. Those mussels are then brought to the Inks Dam National Fish Hatchery in Burnet — approximately 55 miles northwest of Austin — where U.S. Fish and Wildlife Service looks after them, and the larvae can grow on fish.
SARA then grows the mussels a bit more in floating baskets in the San Antonio River until they’re big enough to be put out into the wild on their own.
“Freshwater mussels play a vital role in maintaining the ecological balance of our rivers and streams,” Amy Lueders, Southwest regional director of U.S. Fish and Wildlife Service, said in news release. “These filter-feeding mussels help improve water quality by removing pollutants and tiny particles from the water, enhancing overall water clarity and supporting a healthier aquatic ecosystem.”
About 10% of the mussels are fitted with PIT tags, which can be found using a metal detector-style instrument, so SARA can sweep the river later to find the cluster of mussels and measure their growth and survivability.
“So we know that there’s going to be some loss over time,” Donovan said. “So we know that’s why we want to put those 2,000 maybe over the next five or 10 years. If that becomes 250 surviving, thriving, reproducing adults, that’s a really good mussel bed.”
The project has been underway since 2017 and has included testing whether the mussels would survive, perfecting their techniques and producing the mussels.
SARA has spent $520,000 since teaming up with U.S. Fish and Wildlife Service in 2019. It has another $214,000 committed through its 2026 fiscal year.
“While we’re (in) Year 3 or 4 in this project, I mean, this is our first year having a successful cohort,” Donovan said. “But as we get better and better at those techniques, the cost to produce each muscle is just going to significantly decrease. So, again, it’s been a huge battle and that expertise at Inks Dam is invaluable.”