How Does Excessive Water Use Affect Water Quality?

The demand for water in the United States creates the need to build dams, dig wells, and make withdrawals from our natural water bodies. Using too much water also significantly contributes to "nonpoint source pollution." This is when water moves across the ground, collecting pollutants from various sources, and eventually depositing them into our drinking water. Failing to use water efficiently can hurt our water supply by:

• Altering stream flows due to excessive withdrawals.
  
  
• Causing saltwater to intrude into freshwater aquifers due to excessive withdrawals.
  
  
• Increasing the amount of dirty runoff water that flows into natural water supplies. This runoff water carries sediments, nutrients, salts and other pollutants and can be caused, among other things, by overirrigating urban landscapes or farm fields. Nutrients such as nitrogen, phosphorus, and potassium are naturally occurring, but habitats can be destroyed when excess amounts of any one nutrient, especially phosphorus, are concentrated in the soil or water.
  
  
• Creating the need to build additional dams. Dams generate nonpoint source pollution by trapping sediment and other pollutants, affecting water quality both upstream and downstream. This concentrates pollutants, causes sediment in the river to pile up, decreases dissolved oxygen, and alters water temperatures.

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