Our Connection to Water

It can be easy to forget about where our drinking water comes from. Many Americans get their drinking water from local surface bodies like rivers and lakes. For example, the city of Philadelphia sources its drinking water from the Delaware and Schuylkill rivers. Still, many people don’t understand the connection between what we do in our communities and the quality of the water we drink. Besides human use, local waterways support numerous forms of life, and pollution threatens their capacity to do so. Surprisingly, a lot of this pollution doesn’t fit the image we might have in our heads: a big factory dumping into the local river. It looks a little different, perhaps a lot more familiar – like a pristine and manicured lawn, a car driving down the road, or a gutter draining into the street during a rainstorm.

What is a watershed?

Watersheds are the key to understanding how each one of us is connected to the water in our region. A watershed is an area of land that drains rain or snowmelt into a river, lake, stream or other body of water.  Each one of us lives in a watershed.  In Pennsylvania, there are six major watersheds; the Ohio, Genesee, Susquehanna, Delaware, Erie, and Potomac. Larger watersheds such as these contain many smaller watersheds, which are separated from each other by high points in the land that form the boundary of watershed. 

Factors like elevation are important to understanding how a watershed functions.  When precipitation falls to the Earth, gravity helps guide it to the lowest possible point, which is often a stream.  The journey that this precipitation makes is not always on the surface – more often it occurs below our feet through the migration of groundwater.   But with urban development encompassing more and more land every year, the ability of water to permeate the soil is thwarted by hard surfaces like asphalt and concrete.  When precipitation hits these surfaces, it is bound to become stormwater runoff.  


In natural environments like a forest, the ground is permeable, meaning that precipitation can easily soak into it. After soaking into the ground, this water filters down through the soil, becoming groundwater and making a slow journey to the local waterway. In urban and suburban landscapes, surfaces consist of man-made structures like houses, buildings, and roads which are impervious, meaning water cannot soak into them. This means that when precipitation hits most urban surfaces, it cannot infiltrate into the ground and thus it becomes stormwater runoff.

As stormwater runoff flows across impervious surfaces to storm drains, it picks up pollutants like oil, road salt, sediment, fertilizer, and pesticides. Most storm drains and sewers lead directly to local surface bodies of water like streams, rivers, and lakes. Thus, the pollutants from our urban and suburban landscapes are transported directly to local waterways very quickly and with no filtration. This not only harms the quality of our water and the health of the organisms that live in it, but can also contribute to damaging flash floods, especially during a large storm event.

Green Stormwater Infrastructure

Green Stormwater Infrastructure, commonly referred to as GSI, is a way to manage stormwater runoff by imitating nature. It uses plants, stone, and soil to slow down the flow of water and filter out pollutants. This helps to decrease the amount of water that goes into our sewer systems and protects our waterways.

The infrastructure in GSI refers to the various tools and methods we use to accomplish these objectives. Some examples of GSI include rain gardens, downspout planters, rain barrels, conservation landscaping, and riparian buffers. These tools allow us to capture, store, filter, infiltrate, absorb, and evaporate stormwater using various methods, thus reducing runoff from our properties.