General Stormwater Concepts

What is Stormwater?

Stormwater is rainwater that washes through our property and streets, taking with it any debris that may be in its path. This mixture of rain, debris, oil and waste is known as “runoff”.

What is a Watershed?

A watershed is the area of land that drains to a common waterway, such as a stream, lake, estuary, wetland, aquifer, or even the ocean. Further information can be found at the EPA website on opens in a new windowwatersheds.

What is a Floodplain?

A floodplain is any area that can be expected to flood occasionally. It is the lowland adjacent to a ditch, river, creek, stream or lake. With very few exceptions, almost all areas of the United States are subject to some kind of flooding when the right set of circumstances occurs. However, the risk of flooding varies from place to place. See the picture below to better visualize a floodplain.

What is a Floodway?

Floodway includes the channel of a river or stream and area adjacent to the channel that will carry moving water during times of flood. This is a high hazard portion of the floodplain. The floodway is that portion of the floodplain that we see on television where the houses have been swept off their foundation. In addition to being a hazard to residents, the floodway also presents a hazard to rescue personnel. See the picture below to better visualize a floodway.

Flood Plans

If you want to view maps of local floodways, please consult the opens in a new windowFEMA floodway maps.


Wetlands are lands where saturation with water is the dominant factor determining the nature of soil development and the types of plant and animal communities living in the soil and on its surface. Wetlands vary widely because of regional and local differences in soils, topography, climate, hydrology, water chemistry, vegetation, and other factors, including human disturbance. Indeed, wetlands are found from the tundra to the tropics and on every continent except Antarctica. Further information can be found at the EPA website on opens in a new windowwetlands. For a map of local wetlands please consult the opens in a new windowNational Wetland Inventory Maps.

Storm Drains & Sanitary Sewers, What’s the difference?

Sanitary sewers receive wastewater from indoor plumbing fixtures such as bathroom sinks, mop sinks, floor drains, washing machines and toilets. The treatment process removes solids and organic materials, the water is filtered and a disinfectant is added to destroy bacteria, viruses and other pathogens. After treatment, the water is released into the environment.

Storm drains receive rainfall runoff after storm. Water that goes down a storm drain is left untreated and eventually ends up in ditches, lakes, rivers and streams. Substances such as detergents, cleaners and grease are harmful to aquatic ecosystems, wildlife and human health. Storm drains are found outdoors, such as on streets, near sidewalks and in parking lots. Think of these drains as rivers beneath your feet! So protect your storm drains by preventing any harmful materials from entering into them and report suspected polluters. The drainage conveyance system is currently being mapped in ArcGIS and will be available online as sections are completed.