In the spring and the fall of each year, the water in Lake Murray can experience rapid warming or cooling trends. This rapid change in temperature can cause water that is typically found at the bottom of the Lake to move to the surface. This water contains decaying matter such as leaves and a mineral called manganese, both of which have distinctive unpleasant odors. Rivers can also turn over, but it is not as common. Extended warm weather also encourages algae and bacteria to grow in surface waters.
Water systems use disinfectants, such as chlorine, to kill harmful bacteria.
Certain bacteria and algae that are not harmful can form a substance called Geosmin. Geosmin has a strong, musty or earthy odor. A very small amount of Geosmin, five nanograms, can affect the taste and smell of water. Five nanograms is the equivalent of one second in 6,400 years. Columbia conducts periodic tests for Geosmin in both Lake Murray and the Columbia Canal.