A Walking Tour of Millinocket Stream

When iron in the water comes in contact with dissolved or atmospheric oxygen, it oxidizes and precipitates, or drops out, becoming a yellowish-orange-red stain on the bottom of the stream. This happens with other metals, as well. These metals can clog the gills of fish. When this sediment lies on the bottom of a stream, it fills in spaces between rocks where insects live and fish eggs are laid, smothering the eggs.