A drinking water advisory for the city of Salem doesn’t look like it’s going away just yet.
After extending the advisory over potentially harmful cyanotoxins for two weeks on June 11, city officials now say it's unlikely the warning will be lifted June 25.
“I’m not going to rule anything out, but it does seem unlikely,” said Heather Dimke, a management analyst for Salem’s public works department.
Related: As Salem Frets About Toxic Algae, Should The Rest Of Oregon?
Since late May, Salem has been beset by concern about toxins from an algae bloom in Detroit Reservoir, which feeds the city’s water supply. The toxins can be dangerous in high enough concentrations, but aren’t currently subject to federal regulation.
They’ve periodically showed up in Salem’s drinking water at levels where the contaminants are a potential concern to young children, pregnant or nursing mothers, and other people with vulnerable immune systems.
The city's initial advisory was issued May 29 then lifted June 2. Just four days later, the city issued a second advisory, saying concerning levels of toxins had once again been detected.
On June 11, Salem City Manager Steve Powers announced in a news conference that the problem seemed to have subsided again, but that the advisory would remain in place for another two weeks while the city tested out new treatment strategies.
“The on-again, off-again nature of the advisory was causing confusion,” Powers said at the time. “Extending the advisory until we can ensure our water customers, our residents, that the water is safe to drink is the best course of action.”
Related: Salem Tests A New Way To Remove Toxins From Drinking Water
But the city's plan for using powdered carbon to help alleviate toxins is still in the works, Dimke said, and recent results show the issue hasn't subsided. A water sample from June 18 once again showed potentially problematic levels of toxins in the city's water system.
“That speaks just to the variability,” Dimke said Friday. “This is a natural substance. We’re learning much about how variable it can be and change on a daily basis.”
Harmful algae blooms have become a matter of increasing concern in Oregon in recent years, though there are no federal requirements to test for the cyanotoxins they produce. In light of Salem's woes, the Oregon Health Authority is expected to issue temporary rules mandating testing in coming weeks.