Pollutants

sediment in waterThere are a number of different pollutants that can be picked up in stormwater and impact our land and water resources, including the following:

Sediment

Sediment is often viewed as the largest pollutant load associated with stormwater runoff in an urban setting. Unprotected earth disturbances caused by human activities, including highway construction, land development, and poor installation and maintenance of vegetation, can create sediment pollution.

Nutrients, Organic Matter, and Trash/Litter

Various forms of nutrients, organic matter, and trash may be carried by stormwater in urban areas. Consumption and decomposition of the nutrients and organic material by aquatic organisms can result in decreased oxygen levels, which, if they drop low enough, can severely impact water quality and plants and animals living in the water.

Nutrients enter the urban system in a variety of ways, including from commercial and home landscaping practices, leaks from sanitary sewers and septic systems, and animal waste. The nutrients most often identified in stormwater runoff are phosphorus and nitrogen.

Excess nutrients can cause algae blooms (excessive growth of algae) and can occur in lakes, reservoirs, rivers, ponds, bays, and coastal waters. They can become harmful by producing toxins that harm human health and aquatic life. When the algae die after using up the nutrients, they sink to the bottom and decompose in a process which removes oxygen from the water. Fish and other aquatic organisms will die when the oxygen level falls too low.

 


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