Fresh Water Resources

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Freshwater Resources • Only 3% of Earth water is fresh water. • Fresh water is usually considered a renewable resource. But, in some cases, like the Ogallala Aquifer that spans from South Dakota to Texas is not a renewable resource. The aquifer took more than a million years to collect and it is not replenished by rain. The Ogallala is expected to run dry in 20 to 40 years. Water Pollution • Pollutants can enter the water supply by run-off. • A pollutant is a harmful material that can enter the biosphere. • Point source Pollution- pollutants from a single source entering water. Factories are an example of point source pollution. • Nonpoint sources- pollutants from many, smaller sources entering water. Grease and oil washed off the streets by rain are examples. The primary sources of water pollution are Nonpoint sources, residential sewage, and industrial/ agricultural chemicals. Industrial and Agricultural Chemicals • PCB’s- industrial pollutant in a class of organic chemicals. • In the 1970’s PCB’s were banned because they often entered mud and sand making it almost impossible to eliminate. • DDT- a pesticide, effectively controls agricultural pests and disease- carrying mosquitoes. • Harmful industrial pollutants include heavy metals like Cadium, Lead, Mercury, and Zinc. • Instead of using harmful pesticides, farmers should use IPM (Integrated Pest Management) • IPM techniques include biological control- using predators and parasites to regulate for pest insects, crop rotation, and the use of less poisonous sprays. Water Quality and Sustainability • Some plants filter out certain pollutants. Forests and other vegetation help purify water that seeps into the ground. • Watershed- all land whose groundwater, streams, and rivers drain into the same place, like a large lake. • One way of water conservation is drip irrigation. • Drip

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