Iron and Manganese in Drinking Water
Periodically, iron and manganese levels rise in Lake Lanier, the source of our drinking water. When this occurs, Cumming Utilities modifies the water treatment process by adding strong oxidants to oxidize these metals and remove them from our drinking water supply.
Generally, iron and manganese levels rise in the fall when the lake “turns over”. Lake turn-over occurs when the upper levels of the lake are cooled by cooler fall air. As the top layers of the lake cool, they become more dense and settle to the bottom of the lake and push the water on the bottom of the lake up to the surface. Water on the bottom of the lake may contain higher levels of iron and manganese and this “turn-over” process churns the lake and brings higher concentrations of these metals to the surface.