All of us living within a particular watershed have the ability to make changes in the environment which can intentionally or inadvertently affect aquatic ecosystems, even when activities are far from any waterbody. These changes include many common activities such as the construction of homes, roads and shopping centers, and growing crops, lawns, and livestock. Inputs of nutrients, sediments, and toxic substances from these sources can seriously impair streams, ponds, and groundwater resources. Human activities can also change the pattern of water flow in a drainage network, increase the amount of water that reaches a waterbody, and allow water to get there faster without the opportunity for removal of pollutants by slow infiltration into the soil.
Ask students to brainstorm a list of all the different land use activities in their community or town. This may be done as a homework project -- for example, students could record all the different land uses they observe on their way home from school. Table 1 gives one possible scheme of land uses. After students generate their list, ask them to think about the kinds of contamination that may result from these different land use activities. Record their suggestions on the board. A list of possible ideas appears below