Urbanization has contributed to the degradation of Philadelphia's waterways, ecosystems and water quality.
If rain is not properly managed and flows over impervious surfaces—such as streets and rooftops—into the nearest storm drain, it can have a detrimental effect on river and stream corridors. In an urban environment, stormwater is also closely related to safety, flooding, waterway health, drinking water, and community investment.
Urbanization is responsible for many of the sources that contribute to waterway degradation in Philadelphia's streams. Increases in impervious surface area and runoff have negative effects on stream flow.
Once the natural physical condition of a waterway is compromised by pollution or excessive runoff, it sets off a chain of degradation from erosion to water temperature changes to habitat loss.