City Of Salem Chooses Ozone To Treat Cyanotoxins In Raw Water

Geren Island, a small island southeast of Salem, is home to the City of Salem’s Geren Island Water Treatment Plant (WTP). This facility obtains their water supply from the North Santiam River. Historically during the algae season, April through October, the Geren Island WTP’s slow-sand filtration system and thorough water quality monitoring of the North Santiam River, had successfully removed the cyanotoxins in their source water.

But in 2018—due to several factors including an outbreak of an algal bloom in the Detroit Reservoir—the water from the North Santiam River had much higher concentrations of cylindrospermopsin and microcystin...and the appearance of these contaminants occurred much earlier than in previous years. The City of Salem took immediate action and fast-tracked a temporary treatment system which was installed within weeks. This temporary system was able to control the levels of toxins for the next few years, giving them enough time to find and build a permanent solution that would provide clean and safe drinking water long into the future.