Pure water, H₂O, is hard to find outside of the laboratory. As precipitation moves over and through the earth chemicals are dissolved in the water. Wastes are placed on and in the land and discharged to lakes and streams can contaminate the water. Pollutants are materials added to water which can cause bad effects if present in high enough concentrations. Communities work together to reduce contaminant levels and make sure that we have good water quality.

Mercury... dioxin... phosphorus... coliform bacteria... we often hear of these pollutants and their impacts on our lives. Typically present in the environment only at trace levels, these substances can have serious effects on human and ecosystem health. Some pollutants come from near our homes and others from far away, but they are present across the State of Michigan, from Detroit to Isle Royale.

In this exercise, you will be introduced to three types of pollutants: toxic substances, nutrients, and pathogens. Their sources and impacts will be identified and strategies to control their impact on water quality will be described.