Stormwater Management



What is Stormwater?

Stormwater runoff is precipitation that does not soak into ground, but flows over land into storm drains. As this water flows across surfaces it picks up pollutants from the ground. Water that flows into stormwater drains is released back into natural water sources and does not go to a treatment plant.


Where does it go?

Sewer pipes and stormwater pipes are not connected! Stormwater flows back out into natural bodies of water, not into treatment plants.


What problems does it cause?

Examples of stormwater pollutants include sediments, plant nutrients, metals, organic materials, oil and grease, pet waste, and pesticides. Since stormwater runoff does not go though a treatment plant, increased amounts of pollutants entering stormwater drains causes an increase in surface water pollution and lower water quality.

Problems caused in water bodies may include erosion/sedimentation, turbidity, eutrophication, increased salinity and habitat disruption. Eutrophication results from excess plant nutrients (nitrogen & phosphorous—found in many fertilizers) causing an overgrowth of algae, leading to decreased oxygen levels in surface waters. This creates problems for aquatic life.


What can I do to help?

·         Do not dump waste in storm drains!

·         Clean up pet waste.

·         Landscape with fewer hard-paved (impervious) surfaces.

·         Prevent erosion by vegetating bare soil.

·         Reduce pesticide use.

·         Clean up auto/household chemical spills with absorbents instead of rinsing with water.

·         Do not litter.

·         Do not dump grass clippings and other yard waste into street curbs and drains.



Stormwater Regulations

The National Pollutant Discharge Elimination System (NPDES) program was established by the federal government to control discharges of water pollution. The NPDES Permitting and Compliance Programs of Pennsylvania’s Department of Environmental Protection (PA DEP) is responsible for administering the program for the state. Goals are set to improve the water quality using the 6 key elements of NPDES Phase II – Municipal Separate Storm Sewer System (MS4) Program.

What is an MS4?

An MS4 is a conveyance or system of conveyances that is:

·         Owned by a state, city, town, village, or other public entity that discharges to waters of the U.S.;

·         Designed or used to collect or convey stormwater (including storm drains, pipes, ditches, etc.);

·         Not a combined sewer; and

·         Not part of a Publicly Owned Treatment Works (sewage treatment plant).


What are Best Management Practices (BMPs)

Best Management Practice (BMP): Activities, facilities, designs, measures, or procedures used to manage stormwater impacts from regulated activities, to meet state water quality requirements, to promote groundwater recharge, and to otherwise meet the purposes of this Ordinance. Stormwater BMPs are commonly grouped into one of two broad categories or measures: “structural” or “nonstructural.” In this Ordinance, nonstructural BMPs or measures refer to operational and/or behavior-related practices that attempt to minimize the contact of pollutants with stormwater runoff whereas structural BMPs or measures are those that consist of a physical device or practice that is installed to capture and treat stormwater runoff. Structural BMPs include, but are not limited to, a wide variety of practices and devices, from large-scale retention ponds and constructed wetlands, to small-scale underground treatment systems, infiltration facilities, filter strips, low impact design, bioretention, wet ponds, permeable paving, grassed swales, riparian or forested buffers, sand filters, detention basins, and manufactured devices. Structural stormwater BMPs are permanent appurtenances to the project site.

6  Minimum Control Measures (MCMs)

1.     Public Education and Outreach – Educate the public about stormwater and the importance of protecting water quality.

2.     Public involvement – Involve the public in developing, implementing, and reviewing MS4 management programs and describes ways to reduce stormwater pollution.

3.     Illicit Discharge regulations -  Identifying and eliminating illicit discharges and spills to storm drain systems.

4.     Construction site runoff regulations (Erosion and Sedimentation Control) -  Address stormwater runoff from active construction sites.

5.     Post-construction site runoff regulations (BMP’s) – Sddress stormwater runoff after construction activities have ended.

6.     Pollution prevention and good housekeeping (for municipal operations)- Aims to reduce water pollution through prevention and good housekeeping practices related to municipal operations.


For Additional Information Please Check Out the Following Links:

·         What is a Watershed Brochure

·         Green Guide for Property Management

·         Chester County Water Resource Authority

·         StormwaterPA

·         EPA Municipal Separate Storm Sewer System (MS4) Information

·         PA DEP MS4 Information Resources

·         MS4 FAQ – PA Department of Environmental Protection (PA DEP)

·         PA DEP – Stormwater Management

·         Map of Pennsylvania’s NPDES MS4 Permitting Program