Define a watershed- A watershed is an area of land that drains water into a particular creek, river, lake, or aquifer. Water drains downhill, so hills, ridges and other high points define the boundaries of a watershed. The water that flows over the surface of the land and drains into a body of water is called runoff. The cleaner the land (i.e. watershed) the cleaner the runoff and the receiving body of water. If the land (i.e. watershed) is polluted, then runoff is polluted and the receiving body of water becomes polluted.
Do Watershed Model demonstration- Allow students to rain on the watershed using the watering can. Focus on the downhill pathways the water follows to drain to the creek, and the cleanliness of the water as it flows over the land. Tell students the red food coloring represents pollution. Allow students to drop one drop of food coloring on different areas of the watershed. Rain again and discuss the flow of pollutants from the land (i.e. watershed) to the creek.
Define Land Use- Land Use is how land has been changed for human use, e.g. for a school, road, park, preserve, etc. Studying land use is a quick, practical method of locating the source of pollutants found within a watershed. Watershed scientists are particularly interested in studying land use to determine the impact it will have on water quality. The first step in assessing land usage in a watershed is to observe how the land surrounding the waterway is being used. Different types of land use generate different types of pollutants, which can runoff into the local body of water. Land use practices in the Austin area can affect the quality of our creeks and ground water in various ways that you will research and identify.
Identify Land Use Impacts to Water Quality- Discuss student handout #1 Land Use and Pollutants:Causes and Effects. Students will use this handout to answer questions on the student sheet.
Student Land Use Map Activity- Arrange students in groups and give each group 1990 and 2000 Land Use maps of their watershed. Show transparency of 2000 map. Locate and define the headwaters, mouth, and the different kinds of land use. Give groups time to complete Lesson #1: Land Use and Water Quality In Your Watershed.