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What is Stormwater Runoff?

During a Storm Event, rainfall is either absorbed into the ground or it flows across the surface of the ground towards a downstream point once the ground becomes saturated with water. The rainfall that does not perculate into the ground and flows across surfaces to a downsteram point is commonly refered to as Stormwater Runoff.

As Stormwater Runoff flows across various surfaces it has the potential to accumulate and transport pollutants like sediment, debris, and chemicals. If left untreated, Stormwater Runoff can impact water quality, harming or killing fish and other wildlife, and may even flood downstream areas.

Construction and Industrial Activities significantly increase the chances that Stormwater Runoff will accumulate pollutants as existing land coverage is either changed or subjected to industrial exposures. For this reason, these activities most comply with both federal and state stormwater regulations to ensure that polluted Stormwater Runoff does not have an adverse affect on receiving water bodies.

Construction Activities

Construction Activities

Information on land disturbing activities that require NPDES Stormwater Coverage.

Design Guidance

Industrial Activities

Information for facilities that discharge stormwater and the associated NPDES Coverage.

Regulated MS4s

Common Pollutants

Information on various pollutants that can be found in stormwater runoff.

The majority of Stormwater Regulations can be met by implementing a set of site specific Best Management Practices (BMPs) that is outlined in a stormwater management plan referred to as a Stormwater Pollution Prevention Plan (SWPPP).

Another source of concern with Stormwater Runoff is within urbanized areas as determined by the latest census. In addition to construction and industrial activities, Urbanized Areas are more and more often being pointed out as the contributing factor to many water quality impacts in our water ways. Many Pollution Prevention Programs have been created to reduce the impact of Stormwater Runoff from Urbanized Areas.


Bureau of Water . Phone: (803) 898-4300 . Fax: (803) 898-3795 .