“Our study is a precautionary tale of how entire populations could be put at risk even with small-scale fluid spills,” said USGS scientist Diana Papoulias, the study’s lead author. “This is especially the case if the species is threatened or is only found in limited areas, like the Blackside dace is in the Cumberland.”

Following the spill scientists noted “a significant die-off of aquatic life” in the area, including the minnows but also Creek chub and Green sunfish.

Sample analysis of wildlife showed gill lesions and damaged spleens and livers. The lesions, the panel notes, are indications of exposure to acidic water and toxic concentrations of heavy metals.

One ecologist who participated in the study called the fish deaths “a canary in a coal mine.”

“These species use the same water as we do, so it is just as important to keep our waters clean for people and for wildlife,” he said in a statement on Wednesday.