We All Live In a Watershed

By -Lynette Black

Many people are familiar with toolsheds and woodsheds, those shelters where we store equipment, tools, and firewood. A watershed, however, causes a bit more confusion. Despite what the word may imply, a watershed is not a house for water. A better way to understand the term is to remember an alternative definition for shed—“to give off” or “to cause to be dispersed without penetrating.”

Simply put, a watershed is all the land that drains into a body of water. When it rains, a farmer irrigates a field, or someone washes his/her car at home, all the water that falls on the ground has to go somewhere. Some will evaporate, some will soak into the ground, and some can travel over the land surface. Eventually the runoff, and even some of the groundwater, will make its way into a ditch, stream, or lake. The body of water and the land the water traveled across make up the watershed.

If you made a model of a watershed, you might construct some hills and valleys with a few streams running through them. If you made it “rain” on your model and closely observed where that water fell, you could see how the topography, or lay of the land, determines the flow of the water. Some of the water falling on top of your hill will go to one side and into one of the rivers. The rest of the rain will flow down the other side of the hill to the other stream. The hill acts a divide, determining the direction in which the water moves. This model shows two small watersheds—one for each stream. It also is an example of a larger watershed—one that has two streams that will eventually flow into a larger river.

Watersheds can be large or small depending on the size of the waterbody associated with it. There can also be a watershed within a watershed. To help identify watersheds, the United States Geological Survey has delineated them by assigning them hydrologic unit codes. These codes breakdown watersheds into successively smaller pieces. For example, the code for the watershed in which the Elkhart County SWCD office is located is 04050001210020 (Rock Run Creek subwatershed). This means water drains from the area around the office into Rock Run Creek. From there it goes to the Elkhart River-Main Branch, to the St. Joseph River, to Lake Michigan and the Great Lakes Basin.

The example above shows us that watersheds are connected. What happens in the smallest subwatershed can effect the largest. If a ditch becomes polluted, that pollution can travel to the adjoining stream and so on. Furthermore, if the ditch is protected and cleaned-up, the land and water downstream will experience less of a pollution load.

It is important to know what a watershed is because everybody and everything lives in a watershed. Our everyday activities are done within a watershed—from work to recreation. Awareness of how those activities affect the land, air, and water and the appropriate actions to take will help make a healthy watershed. Simple things that most people can do include picking up after pets, carpooling, testing the soil before fertilizing, disposing of waste and trash appropriately (never dump anything into a storm drain or directly into a body of water), and using conservation practices in farming, industry, and construction. A healthy watershed benefits us all, and we can all do our part to conserve the place in which we live.

http://water.usgs.gov/GIS/huc.html

Diagram: http://www.gtbay.org/aboutgtbws.asp

Watershed 101