Clean Water

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Everyone needs clean drinking water. All living creatures depend on clean water in streams and lakes for health and happiness…not to mention survival. That’s why the Pennsylvania Turnpike thinks a lot about how we handle stormwater runoff that comes from our roadways, service plazas, interchanges and other facilities.

When precipitation falls, it doesn't sit there, it starts moving according to the laws of gravity. Some precipitation seeps into the ground to replenish groundwater. Some of it also flows downhill as runoff. Runoff occurs during storms, and more surface water flows in streams (and as runoff) during storms.

As it flows over land, stormwater can pick up pollutants like sediment (dirt), nutrients (from lawn and farm fertilizers), bacteria (from animal and human waste), pesticides (from lawn and garden chemicals), metals (mining and industrial sources) and petroleum byproducts (from leaking vehicles).

Runoff from agricultural land (and even our yards) can carry excess nutrients like nitrogen and phosphorus into streams, lakes and groundwater supplies. These excess nutrients can also degrade water quality.


The way that the Pennsylvania Turnpike and other public entities manage stormwater is critical to reduce the risk of increased runoff. In developed or urbanized areas, more water arrives into a stream more quickly, due to more impervious surfaces.

In wooded areas, rainfall is absorbed by native soils (a process called infiltration), stored as groundwater and slowly discharged through springs into streams and other water bodies. Increased runoff is less significant in wooded areas because precipitation is absorbed into the ground, reducing the amount of runoff into a stream.

As watersheds become more urbanized, much of the vegetation is replaced by impervious surfaces, reducing the area where infiltration can occur. Thus, more stormwater runoff occurs — runoff that must be collected by extensive drainage systems that combine curbs, piping and ditches to carry stormwater runoff to streams.

A stormwater inlet is a common site on the Pennsylvania Turnpike and most other highways and roads. Stormflows are collected by these inlets, and the water is delivered through pipes to nearby creeks and streams to prevent roadway flooding.

Drainage ditches to carry runoff to storage basins are built along the Turnpike to retain runoff and collect sediment to keep it out of streams. Basins are also constructed to infiltrate stormwater back into the groundwater.

The next time you’re traveling on the Pennsylvania Turnpike, remember the important job these facilities — storm inlets, ditches and basins — perform to reduce runoff and keep waterways clean for all plants and animals who rely on fresh water.

Municipal Separate Storm Sewer Systems

MS4 is an acronym for “Municipal Separate Storm Sewer System.” An MS4 is usually owned and operated by a municipality or other entities like the Pennsylvania Turnpike Commission. It is made up of storm inlets, pipes, ditches, swales and basins used to collect and transport stormwater runoff which could be discharged into streams and rivers or infiltrated into the groundwater.

An MS4 is “separate” from a combined sewer system which collects rainwater, sewage and wastewater in the same pipe and carries it to a treatment plant before it’s discharged. MS4s use stormwater control measures, such as basins, to manage the flow of water and reduce pollutants such as sediment.

To prevent pollutants from being discharged into streams and rivers, the Environmental Protection Agency (EPA) and Pennsylvania Department of Environmental Protection (PADEP) required that municipalities and other entities such as the Pennsylvania Turnpike Commission develop a stormwater management program to reduce pollutants from being discharged to Waters of the Commonwealth.

To learn more about Municipal Separate Storm Sewer Systems, please visit this DEP FAQ.

What Does the Pennsylvania Turnpike Do?

For decades, we at the Pennsylvania Turnpike have taken numerous steps to better control stormwater runoff as well as to limit impurities in runoff across our system. In the coming months, we will launch an even larger Clean Water initiative aimed at improved protection of the streams and rivers that pass beneath or near our 552-mile highway system.

What Can I Do?

The Pennsylvania Department of Environmental Protection (DEP) has a mission to protect Pennsylvania’s land, air and water from pollution and provide a cleaner environment for the health and safety of its citizens. The DEP’s Bureau of Clean Water works with the Pennsylvania Turnpike and other entities to help ensure we follow regulations to reduce stormwater runoff as well as the pollutants in that runoff. Urban runoff pollution is a problem that has no boundaries, and neither does the solution! Residents can also do their part to reduce stormwater runoff. Click here to learn how.

Contact Us with questions or concerns.