Ammonia washed away from the nearby Kiolbassa Smoked Meats plant ended up in San Pedro Creek and the San Antonio River killing fish and other wildlife. Credit: Bonnie Arbittier / San Antonio Report

A release of ammonia gas at a meatpacking plant on the West Side led to the deaths of hundreds of fish in San Pedro Creek and the San Antonio River’s Mission Reach.

Late Monday night at Kiolbassa Smoked Meats’ plant at 1325 S. Brazos St., ammonia gas began escaping from an industrial refrigeration system, according to Kiolbassa and San Antonio Fire Department spokespersons. Firefighters received the call at 11:40 p.m.

Ammonia is a commonly used industrial refrigerant. Industrial plant operators often prefer it to alternatives because of its low cost and its benign effect on the Earth’s atmosphere if released. However, the gas is highly corrosive and can injure or kill people who inhale it.

“It’s a very hazardous gas,” Kiolbassa spokeswoman Laura Waldrum said. “In our haste to save lives of people inside the plant, it does appear that we had some impact on the environment.”

Using water from their hoses, firefighters successfully neutralized the gas, Waldrum said. No one suffered injuries, according to SAFD. Waldrum said the leak happened after production had finished for the day.

Over the next day, the ammonia-water solution that flowed from the site had deadly consequences for fish downstream. Runoff flowed into a storm drain on South San Marcos Street and from there to San Pedro Creek, according to the San Antonio River Authority.

Chris Vaughn, a River Authority aquatic biologist, said he arrived at San Pedro Creek near the Furnish Avenue crossing and Interstate 35 overpass shortly before 7 a.m. Wednesday. He and his colleagues found around 800 dead fish in the creek, 576 of them species native to the area, he said.

“We thought that it was fairly contained to that area,” Vaughn said, but they realized the pollution had spread downstream to the confluence with the San Antonio River and down the river’s main channel as far south as Mission Road.

By Wednesday evening, they had found around 1,000 more dead fish in the river’s main channel. He expects they’ll find another 1,000 to 2,000 on Thursday.

“Our main concern right now is the Mission Reach of the San Antonio,” he said.

Waldrum, Kiolbassa’s marketing and communications director, called the ammonia release a “one-time event.” The 71-year-old company is in its third generation of family ownership and is a longtime presence on the West Side and on the meat aisles of local grocery stores.

“We deeply regret the effects of this event on the environment and will continue to work with local and state officials to rectify this situation,” Waldrum said. She said she was still gathering details on what caused the leak.

It’s not clear what the official response will be. A spokesman for the Texas Commission on Environmental Quality, the State’s environmental regulator, said in an email that the San Antonio regional office is investigating but was not able to provide further information late Wednesday.

Fish kills like this are rare but not unheard-of on the San Antonio River. The worst in recent memory was in 2016, when more 12,000 fish suffocated in a remnant of the former river channel at Espada Park.

Biologists at the time said the die-off was the result not of a spill but stormwater runoff from a heavy rain that caused oxygen levels in the water to drop. Vaughn said it was a “cocktail of different things happening all at once.”

Vaughn described the river’s ecosystem as “extremely resilient” and likely to recover from the ammonia incident.

“We unfortunately lost a fairly significant number of fish, but it will be relatively short-lived, and it will certainly bounce back,” he said.

Brendan Gibbons is a former senior reporter at the San Antonio Report. He is an environmental journalist for Oil & Gas Watch.