What is Stormwater? | www.charlescountymd.gov


Charles County, Maryland

What is Stormwater?

What is Stormwater?


Stormwater is rainwater or melted snow that runs off streets, lawns, and other land. 

When stormwater is absorbed into soil, pollutants are filtered out and the water eventually replenishes aquifers or flows into streams and rivers. 

As stormwater runs off impervious surfaces, like pavement and roofs, the water picks up pollutants such as landscaping fertilizer, heavy metals and oil from vehicles, fecal coliform from pet waste, and sediment from eroding land. 

Untreated stormwater containing pollutants, known as stormwater runoff, runs rapidly into storm drains, sewer systems and drainage areas. 



(Photo Credit: Courtesy NCDENR)

The following concerns can arise as a result:

Flash Flooding – fast moving stormwater runoff that overloads storm drains and drainage areas causing temporary flooding. 




Erosion – fast moving stormwater erodes stream banks.  Insect larvae, fish, and amphibians are negatively affected due to stream habitat degradation from the fast moving water. 

Sedimentation – sediment from construction projects or other exposed soil are carried into waterways with runoff.

Pesticides/Fertilizers - carried with stormwater runoff from residential yards, gardens, golf courses and agricultural areas polluting waterways. 

Automotive - Oil and car wash residues are carried into waterways via storm drains.


Litter –trash left on roads and sidewalks is carried into waterways via storm drains.

Pet Waste – unscooped pet waste enters waterways, increases bacterial coliform.

Salt – winter weather road treatment salt get carried into the streams.





Stormwater runoff discharged into waterways often creates unlivable conditions for fish and other aquatic life, loss of aesthetics, and human health issues.