Development alters the landscape by increasing impermeable surfaces, compacting soil, and introducing pollutants into the storm sewer system. These characteristics mean an increase in the quantity of runoff and a reduction in the quality of the discharge. As development occurs, vegetation must be removed; the same vegetation that filters pollutants, slows erosion and runoff velocity, and provides shade that supports varying ecosystems. Studies have shown that planning for the minimization of pollutants BEFORE construction is the most cost-effective method of stormwater quality management. 

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There are generally two forms of substantial impacts of post-construction runoff. The first is caused by an increase in the type and quantity of pollutants, and the second occurs by increasing the quantity of water delivered to the waterbody during a storm. Increases in impervious surfaces, such as parking lots, rooftops and sidewalks, prevent runoff from percolating into the soil.

 

Activities under Minimum Control Measure V address these issues by implementing best management practices that either preserve or restore vegetation or stream buffers, increase permeable surfaces and promote onsite treatment of stormwater discharge.

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