Non-point source pollution or runoff - is treatment needed?

Whenever we build neighborhoods, parking lots, roads, and even farms, human activities result in pollution that enters surface water during rain events. For the past 20 years, we have required many parking lots and concrete pads to have retention ponds mostly for the prevention of flash floods. However, when we look at these ponds we see how much pollution is actually in runoff. Let's look at the pollution in runoff:



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• Neighborhood retention ponds disguised as water features often require additions of copper sulfate or dye as the fertilizer runoff from lawns and yards creates algae blooms. Most of the pollution is in the form of nitrogen and phosphorus but also various herbicides/pesticides
  
  
• Parking lot, gas station. road, and warehouse lot runoff contains a blend of hydrocarbons including motor oil, fuels, and various chemicals including surfactants, pesticides, and herbicides.
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While the hydrocarbons and chemicals are bad pollutants, most of our current problem is from fertilizer runoff. The Great Lakes area of the USA has had problems with blue-green algae blooms causing off-flavors and toxicity in drinking water supplies. In bays and inlets, the lakes experience eutrophication where low DO during warm months damages wild life and causes odors for neighboring areas.

Current efforts focus on creating awareness of the pollution in runoff, but are not enforcing any treatment requirements. As our population and development increases and non--point source pollution starts to contribute more "loadings" to the environment that municipal water treatment plant or industrial wastewater treatment discharges, the pollution issues may require more neighborhoods, farms, and commercial areas to have stormwater discharge permits. 

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