What is Stormwater Runoff?

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Stormwater runoff is rainwater or snowmelt that does not soak into the ground, but runs off land surfaces such as lawns, roofs, parking lots and roads and flows into the stormwater conveyance system to be delivered directly to rivers, lakes and streams.

Why Can Stormwater Runoff Be a Problem?

Stormwater runoff can cause two types of problems: it can be a source of water pollution and it can also cause flooding. 

How Does Stormwater Become Polluted?

Rainwater, or stormwater, starts out as clean water.  When rainwater or snow melt flows over the land surface, it can pick up anything on the ground surface, such as cigarette butts, litter, pet waste, oil, fertilizers and other chemicals, soil and other pollutants, that are then carried thru the stormwater conveyance system and discharged into the local water ways untreated.  This of course then causes harm to the environment. People going about their daily activities are the number one source of stormwater pollution.  Many of us are not aware of how we impact water quality.  Some common examples include over fertilizing our lawns, not picking up pet waste, not fixing oil leaks in our vehicles, and littering.

How Can Stormwater Runoff Contribute to Flooding?

Stormwater runoff can also contribute to flooding. Impervious surfaces like driveways, sidewalks, and streets prevent stormwater runoff from naturally soaking into the ground. As more and more areas become developed, more land surface becomes impervious as it is compacted or covered with streets, driveways, rooftops, parking lots etc. Increased impervious cover decreases the amount of rainfall that can naturally infiltrate into the soil and increases the volume and rate of storm water runoff. These changes lead to more frequent and severe flooding of waterways.

Where Does Stormwater Go?

Stormwater runs off the land and either flows directly into nearby rivers, lakes or streams, or travels there through a stormwater conveyance systems, which includes things such as curbs and gutters, inlets, storm sewers, ditches, detention ponds and channels. Anything that enters the stormwater system is discharged untreated into the lakes, streams, rivers or wetlands that we use for swimming, fishing and providing drinking water.