Stormwater is rainwater or melted snow that runs off streets, lawns, and other land surfaces. When stormwater is absorbed into soil, pollutants are filtered out and the water flows into streams and rivers or eventually replenishes aquifers.

As stormwater runs off impervious surfaces, like pavement and roofs, the volume and velocity of the flow increases. This is called stormwater runoff. 

Because stormwater runoff can flow rapidly into storm drains, sewer systems, and drainage ditches, it causes the following problems, especially during heavy rain events:

Flash Flooding – fast moving stormwater runoff that overloads storm drains and drainage areas causing temporary flooding of roads and low-lying areas.  
 
Erosion – fast moving stormwater erodes stream banks causing large amounts of soil to fill stream beds, destroying fish and amphibian’s habitat and killing insect larvae that fish rely on for food.   

Sedimentation – sediment from construction projects or other exposed topsoil is carried off into streets and waterways by stormwater runoff.

Pollution – stormwater runoff picks up pollutants such as fertilizer, heavy metals, oil from vehicles, fecal coliform from animal waste, and sediment when it erodes the land.  The polluted stormwater runoff is called non-point source pollution when it enters our streams, rivers, lakes, reservoirs, aquifers and bays. 

Non-point sources pollution comes from many diffuse sources, not a single "point" source. Non-point source pollution is the leading cause of water quality deterioration in Charles County’s streams, rivers, and the Chesapeake Bay.  Some common sources of non-point source pollution are:

• Pesticides/Fertilizers - carried away from residential yards, gardens, golf courses, and agricultural areas.

• Automotive - Improperly disposed of or stored oil and car wash residues are carried into waterways via storm drains.

• Litter –Trash left on roads and sidewalks is carried into waterways and clogs storm drains.

• Pet Waste – Un-scooped pet waste enters waterways which increases bacterial coliform levels.

• Salt – Used to treat roads during winter, salt washes into freshwater streams and aquifers increasing their salinity.

You can learn how you can Help Stop Pollution or learn more about waterway Pollution by visiting their web pages.

A watershed is the land area that drains to a stream, lake, river, bay or ocean.  In each watershed all of the water that falls in it, and drains off of it, goes to a common outlet, such as a reservoir outflow, mouth of a bay, or any point along a stream channel.  Watersheds include surface water, like lakes, streams, reservoirs, and wetlands and underlying groundwater.

Water that flows over or through a watershed eventually ends up in the waterway to which it drains, including what is picked up along the way. Development projects, stormwater runoff patterns, the location of pollution sources, and groundwater and stream flow all affect the health of our watersheds.

Watersheds can be large or small and smaller watersheds can make up a much larger one.  Charles County is located in the Chesapeake Bay watershed, which spans 64,000 square miles across the District of Columbia and parts of six states - Maryland, Virginia, Pennsylvania, Delaware, West Virginia, and New York.  This means all the water that comes through or originates from Charles County drains to the Chesapeake Bay. 

Maryland has 138 smaller watersheds, called 8-digit scale watersheds, representing drainage divides between 3rd order rivers or streams.  The ten 8-digit scale watersheds within Charles County are the:

• Mattawoman Creek
• Patuxent River Lower
• Nanjemoy Creek
• Gilbert Swamp
• Zekiah Swamp
• Wicomico River
• Port Tobacco River
• Potomac River Lower Tidal
• Potomac River Middle Tidal
• Potomac River Upper Tidal

Stormwater runoff discharged into waterways often creates unlivable conditions for fish and other aquatic life, loss of aesthetics, and human health issues. Visit our Help Stop Water Pollution page to find out how you can help be the solution to water pollution.