A new study released this week by the U.S. Geological Survey found “potentially harmful” levels of contaminants in fish in the lower Columbia River.
The study, published in the journal Science of the Total Environment, analyzed a series of locations on the river below Bonneville Dam, including the Portland-Vancouver area. Researchers discovered that some resident fish, mainly large-scale suckers, contained chemicals at levels that officials have determined can cause health concerns for the people who eat them, according to the USGS. That’s particularly true for people who eat large quantities of fish, such as tribal populations.
The study measured for contaminants including pesticides, flame-retardant compounds and ingredients from common household products, according to the USGS.
The presence of those chemicals went beyond fish; they also showed up in insect, sediment and water samples taken from the Columbia River, according to the study.
And they were “biomagnified” higher up the food chain, said Elena Nilsen, a research chemist with the USGS in Portland. In other words, fish tissue showed higher levels of pollutants than insects; insects showed higher levels than sediments; and so on.
“That really shows us that these contaminants are in fact having an impact on the food web,” Nilsen said.
The study also showed that fish become more stressed and contaminated farther downstream as more urban water runoff enters the river, according to the USGS.
This week’s study, a multiyear effort, is far from the first to find the presence of pollutants in the Columbia River system.
In 2012, data collected by advocacy group Columbia Riverkeeper found “alarming” levels of toxins in fish — including one fish with a level of polychlorinated biphenyls, or PCBs, at 270 times the amount considered safe for unrestricted consumption. Past research has shown similar problems.
But the contaminants measured in the lower Columbia River by the USGS study are actually lower than the contaminants found in other parts of the country, and even in parts of the mid-Columbia basin, Nilsen said.
Some of the pollutants confirmed by researchers are “legacy” chemicals from practices of decades past.
But the results should still give people pause, Nilsen said.
“I hope that everyone thinks about how we impact the system,” Nilsen said. “We all live here. We all share the river.”