A report out this week details the contamination that’s left after the U.S. Army Corps of Engineers’ clean-up of a dump site at Bradford Island, next to Bonneville Dam.
The good news: Crayfish at the site are no longer hazardous-waste-grade toxic. Their contamination levels have dropped dramatically.
The bad news: The contamination is still above the healthy limits set by the Oregon Department of Environmental Quality.
Of particular concern are the toxins detected in small-mouth bass tissue. As of October 2007, they’re high enough to justify a health advisory for anyone fishing around Bradford Island. Scott Clemens, a spokesman for the Corps, said the toxic fish pose a risk to recreational or tribal subsistence bass fishers around the island, but his agency hasn’t been able to find many people who fit that description. Salmon and sturgeon that swim through that area don’t spend enough time there to accumulate toxins, he said.
The worst of the toxins – polychlorinated biphenyls or PCBs – were leaking out of electrical equipment that had been dumped into the Columbia River. The equipment was removed in 2002, and the Corps dredged up the most contaminated sediment in 2007. The underwater video above shows the method the Corps used to vacuum up the sediment. It went through that tube and several layers of filters on a barge. Most of the sediment was removed from the river entirely, Clemens said, while the water was returned to the river.
Bob Schwartz, Bradford clean-up project manager for DEQ, said he’s hoping the next samples of bass tissue will show lower levels of PCB contamination. The lower contaminant levels in the river sediment were encouraging, he said, but the bass tests are still a concern.
The Corps still needs to study the area to determine the health risks of contaminated sites both in the river and on land. Depending on what they find in the next phase of the project, the agency may do some more clean-up work, or it might just continue monitoring for contamination.