What is Stormwater?

While you may be familiar with the term, have you ever wondered what stormwater is?
What is Stormwater? - Articles

Updated: April 19, 2018

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What is Stormwater?

In Pennsylvania, we get an average of 41 inches of precipitation each year. When it rains or the snow melts, where does this water go?

In more natural areas, water is quickly able to infiltrate into the ground. A forested area allows for about 18 inches per hour of infiltration, where an average lawn allows for about 2 inches per hour. Impervious surfaces like pavement and rooftops, offer no infiltration at all. All of the water that doesn’t infiltrate flows over the ground, over roofs and through gutters on buildings, into storm drains, and into the nearest waterway –our lakes, rivers, and streams. This is stormwater.

Stormwater can be the water running out of the gutters on your home or garage, and down your driveway. If a home has 2,000 square feet of impervious surfaces, that is equal to 1,246 gallons of stormwater runoff that need to be managed during a typical rainstorm. That’s a lot of water that needs somewhere to go! Stormwater can also be the water rushing across a farm field, over a highway, through a parking lot, or through a construction site. It’s important to be aware of stormwater, where it comes from, and where it goes because it impacts water quality in your local watershed. Flooding, pollutants, erosion, and property damage can all result from uncontrolled stormwater runoff.

There are local ordinances and regulations for the control of stormwater runoff in your municipality. These ordinances determine the best ways to manage stormwater for the benefit of local residents and businesses, as well as for the overall health of the watershed. Homeowners, businesses and industries can all work together with municipalities to help manage stormwater and its potential impacts. Understanding stormwater is the first step to making good choices and being a good neighbor in your watershed

If you have additional questions about stormwater, or you are just interested in learning more, you can find a full series of videos and articles in the Penn State Extension Stormwater Basics series .

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Private Water Supplies (wells, springs) Water Testing and Treatment Pond Management and Aquatic Plants Youth Environmental Education

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