TX_7.8C Watershed Reading Science PDF

Watershed (B) Earth and Space Watersheds 1 A warm, spring sun beams down on a snow-covered mountain. The frozen world begins to slowly thaw. The snow turns into an icy, cold liquid as it trickles down the mountain. As this water flows down, it will join larger bodies of water. It may join a roaring...

Watershed (B) Earth and Space Watersheds 1 A warm, spring sun beams down on a snow-covered mountain. The frozen world begins to slowly thaw. The snow turns into an icy, cold liquid as it trickles down the mountain. As this water flows down, it will join larger bodies of water. It may join a roaring river or a peaceful lake. The entire area of land, including the mountain, hillsides, and valleysthat drain into the river, is called a watershed. 2 Only 3% of Earth's water is fresh water. Fresh water is the water that we can drink and use. Unfortunately, the actual amount of liquid water is less than 1% of the amount of fresh water. Liquid fresh water can be found on the surface of Earth. It can also be found in aquifers as groundwater stored in the pores of rocks and soil. Watersheds are very important! They collect rainfall and melting snow. Watersheds drain into the larger bodies of water, such as rivers, streams, lakes, oceans, and aquifers. 3 A healthy watershed allows us to have clean water to drink and pollution-free lakes, rivers, oceans, and aquifers. Unfortunately, human activities can contaminate water. There are two types of human water pollution: point source and non-point source. 4 Point source pollution happens when chemicals or other pollutants from one identifiable source enter bodies of water. Point source pollutants are often caused by businesses that use hazardous materials in manufacturing a product. Farms with animal waste storage facilities, pesticides, and fertilizers can also be a source of the pollution. All of these types of point source pollution can contaminate surface and groundwater. Point source pollution of aquifers can be almost impossible to treat. Point source pollution of groundwater is often caused by solvents, paint, and oil products. In addition to oil and fuel pollutants, bacteria, fertilizers, and detergents can contaminate surface water. These can come from sites that are not careful with their storage or disposal activities. These types of pollution can kill aquatic life, or make a river or lake unusable for recreational activities such as fishing or skiing. 1 Watershed (B) Earth and Space 5 The second type of water pollution is called non-point source pollution. Non-point source pollution happens as water flows over the watershed. The water can pick up natural and human-made pollutants on its way to surface streams or groundwater. You or someone you know may be contributing to non-point source water pollution and not even be aware of it. Have you ever washed a car, fertilized the yard, or owned a dog or cat? If you answered yes to one of these questions, you could have caused pollution. Soap suds from a car can flow down the street and enter a storm drain. The storm drain eventually leads to a lake or river. Soap suds can kill fish and other aquatic life. Do you have a nice, green yard? Lawn fertilizers can be washed into a storm drain just like the soap suds. Perhaps you have a pet. Walking Fido down the street to take care of his business can cause pollution. You must use one of those dog waste bags for proper disposal of your pet's waste. Animal waste has harmful bacteria in it. 6 Once people become aware that there is a pollution problem in an area, scientists can determine what kind of pollution is to blame. Point source pollution comes from just one location. Thus, the source of this type of pollution can often be found quickly. A point source polluter will usually add just one or two contaminants to the water. They also have a steady, predictable flow. Concerned citizens can often find a point source polluter by observation. You can often see visible signs around the place where the pollutant is entering the watershed. Water in different locations can be tested. As the samples get closer to the point source, the amount of pollutant found will increase. 7 Non-point source pollution comes from all over the watershed. There is no individual source. Contaminants come from multiple locations, with only small amounts from each. A scientist can tell that a body of water has been contaminated by non-point source pollution because there will be a large number of different pollutants found in the water. Usually, there is just a small concentration of each pollutant. The amount can rise right after a large rainfall. 8 The next time you wash a car or walk the dog, think about the risk of adding pollutants to the water supply. It is important to limit the amount of non-point and point source pollutants that enter streams, rivers, lakes, oceans, and aquifers. This allows us to drink and use clean water. Pollution-free surface water also allows fish and other aquatic life to have a clean and healthy place to live. 2