One of the most significant effects of the Clark Fork River flooding is the danger of toxic materials stored for the last half-century in the old Smurfit settling ponds that are separated from the swollen river by only a series of earthen berms, being released into the river.

Missoula County Environmental Health Specialist Travis Ross told reporters at a briefing on Wednesday afternoon that the EPA has been testing the waters and found troubling results.

“There’s some complicated hydrogeology going on there and we believe those interactions are still occurring showing materiel leaving the site and entering surface water,” said Ross. “There are several contaminants of concern that have been evaluated including heavy metals and dioxin. So, the county commissioners yesterday wrote a letter to the EPA requesting testing on those areas where the ground water and the surface water are interacting.”

Ross said the commissioners have also asked for a contingency plan, should the berms be breached and the contaminants reach the river and head downstream.

“What are the EPA and the potentially responsible parties going to do if there is some sort of catastrophic release?,” he asked. “What is that plan? We haven’t seen one of those yet. They also want a failure analysis. They want to look at the stability of those berms, what are they made of, is it contaminated? The commissioners want to go a step further to include a hydraulic analysis, what kind of erosive forces such as ice jams, log jams do to the berms. Then, should the berms not hold, what does the transport scenario look like, how would that sludge be transported downstream, and where would it land?”

The ‘potentially responsible parties’ include WestRock, M2Green and International Paper.

Though the Clark Fork River has receded somewhat, it is expected to return to moderate flooding by the weekend, and remain there for some time.