Sewickley Township’s Stormwater Program

Sewickley Township recognizes that storm water is a very important natural resource that provides a source for our drinking water supplies, water for our crops, lawns and gardens, and a replenishment of our streams, ponds and lakes which in turn provide recreation opportunities and enhanced aesthetic value to our community. In order to protect our natural waterways, Sewickley Township has implemented a program to regulate the storm water that is intercepted by its municipal separate storm sewer system, or MS4.  This program was initiated by a state-wide mandate for small- to medium-sized communities with MS4s, such as Sewickley Township, to be permitted under the Pennsylvania Department of Environmental Protection’s (PADEP’s) National Pollution Discharge Elimination System (NPDES) Phase II permit program. This webpage provides general information on storm water and on the Township’s MS4 stormwater program.


What is an MS4?

MS4 is an acronym for a Municipal Separate Storm Sewer System. An MS4 is defined as a collection and conveyance system or a group of collection and conveyance systems owned, operated and maintained by a state, city, township, borough or other public entity.  An MS4 collects and conveys only storm water runoff and conveys it into streams, rivers, lakes, wetlands or other natural or man-made receiving waters within the Commonwealth of Pennsylvania. The MS4 system may include such structures as storm pipes, catch basins, trench drains, roadside swales and cross drains, conveyance channels, detention ponds, infiltration basins, rain gardens or other structures designated for the collection, storage and conveyance of stormwater runoff.

What is Stormwater Runoff?

Storm Water | Copley Township, OH

Stormwater runoff comes from rainwater/snowmelt that runs into larger bodies of water. Precipitation cannot infiltrate impervious surfaces like pavement, roofs, and sidewalks. Precipitation can infiltrate into soil and grass. We cannot make everything an impervious surface, so there is stormwater runoff that causes several problems.


What is Non-Stormwater Discharge?

Non-stormwater discharge is discharge into the Township’s MS4 system or natural waterways that is not due directly to a rainfall or snowmelt runoff event.  Non-stormwater discharge includes groundwater exfiltration, mine pool discharge, discharges from potable water sources such as fire hydrants or waterline blow-off valves, sanitary sewer discharges septic systems, or combined sanitary and storm overflows.  The Township’s stormwater management ordinance prohibits illicit discharges and connections into its MS4 but does list certain exemptions for non-stormwater discharges.

Why can stormwater runoff be a problem in the Township?

This is important because it is polluting our waters. When precipitation falls, the water falls on the impervious surface and runs to the nearest MS4. On its way, it picks up sediment, car oil, fertilizers, pesticides, and all other kinds of pollution. The water from MS4s, goes into bodies of water untreated, which has a negative impact on aquatic life.

Stormwater runoff can also lead to urban flooding. Storm drains can only take so much water at a time, which causes flooding.  Increases the number of impervious surfaces increases the amount of stormwater and storm drains can only take so much water going down them at a time. The excess water then turns into flooding. This can cause erosion, deterioration of waterways, and can result in roadway, infrastructure, and bridges being damaged.

What is Sewickley Township doing about stormwater runoff?

As part of its MS4 permit program, the Township has implemented several actions required under the NPDES storm water program, permittees must develop a stormwater management plan that provides the details of how the community will comply with the requirements of the permit. Permits are based on six minimum control measures, or MCMs, to ensure the proper handling and discharge of stormwater through its MS4 system.  Such measures include:

  • MCM-1 Public Education & Outreach – An informed community is a very important part of a stormwater management program to insure support and compliance. For this measure the township is providing and distributing educational materials concerning stormwater runoff through various outlets to residents, businesses, contractors and developers within the Township. The township has also set up a stormwater task force that consists of various representatives across the township to specifically obtain and investigate storm water issues to inform the supervisors to inform the public. Storm drain markers are also important to remind those passing by that the storm drains connect to local waterbodies and dumping will pollute those water, so you may start seeing these plaques on the inlets. More information on this control measure is located by clicking the following button:
MCM1-Public Education Outreach
  • MCM-2 Public Participation/Involvement – The public is a valuable asset to a municipal stormwater management plan. The MS4 program can only be successful if the community around is willing to comply and be involved. The township is always looking for volunteers, including scouting groups, educators, outdoors clubs, watershed and environmental groups, or any individuals interested in keeping our streams and lakes clean.  For more information or ideas on how you can help out, call the Township at (724) 834-7232 or click the following button:
MCM2-Public Participation
  • MCM-3 Illicit Discharge Detection and Elimination – Through its Illicit Discharge Detection and Elimination program, the Township has developed a Township-wide MS4 outfall map showing all natural waterways and roadways within the Township as well as all outfall locations of its MS4 system into the natural receiving waters. This map will serve as a tool for the Township to identify outfalls that are discharging pollutants as determined by visually screening each outfall during dry-weather periods. Any indications of non-stormwater discharge will prompt the Township to find and identify the source of these pollutants and take actions to eliminate the source(s).
  • The Township has adopted an ordinance to prohibit illicit discharges and connections of non-stormwater into its MS4 system and enable the Township the authority to fine individuals caught illegally dumping pollutants into its MS4 system. For more information on illicit discharges, click the following button:
  • MCM-4 Construction Site Runoff Control – Polluted stormwater runoff from construction sites flows into the MS4 system and into the rivers and streams. The main pollutant concern is sedimentation. The Township has adopted an ordinance for the regulation of stormwater management of land disturbance activities and contractors need to be aware of the requirements and how to satisfy them. For more information, click the following button:
MCM4-Construction Site Runoff Control
  • MCM-5 Post Construction Runoff Control – The Township has adopted an ordinance for the regulation of stormwater management for the handling of stormwater runoff from a site after it has been developed. The Township also provides educational material to developers and contractors who come to the Township office for building permit applications. The Township also utilizes the technical support services of the Westmoreland Conservation District to review land disturbance plans to ensure that these plans are sufficient in addressing construction site stormwater and post-construction stormwater and to conduct site inspections to ensure that the sites are being constructed in accordance with the approved plans.  For more information, click the following button:
MCM5-Post Construction Runoff Control
  • MCM-6 Pollution Prevention/Good House Keeping – This is a crucial part of any MS4 program and by the township keeping their system clean it should encourage you to do the same. The Township is continuously maintaining and tracking its MS4 system through cleaning, repairing and improving the system to ensure that it is functioning correctly. The Township is also monitoring all other municipal operations such as fleet vehicle maintenance, municipal property maintenance, as well as salt and anti-skid material stockpiling to minimize any detrimental impacts that these operations may have on the MS4 system.  For more information, click the following button:
MCM6-Pollution Prevention Good House-Keeping

What can you do to improve stormwater quality in the Township?

What Is Runoff? | H2OC Stormwater Program

It takes everyone to provide continual improvement to the waterways within Sewickley Township.  We would hope that every person realizes that what is dumped into the Township’s MS4 system, ultimately ends up in the streams, rivers and lakes that we all care about.  Here are several things each of us can do to help keep our waterways clean.

  • Sweep yard debris off the street.
    • Compost yard debris or put it in the trash rather than hosing it into the streets.
  • Keep grass height to at least three inches.
    • Longer grass retains more rainwater and requires less fertilizer.
  • Do not wash your car in the driveway.
    • Wash your car at a carwash that recycles the water or wash your car in the grass where it will soak up the water to keep it from becoming stormwater runoff.
  • Use pesticides according to the instructions.
    • Do not use more than directed and do not use right before a rainstorm to prevent extra chemicals running into our waterways.
  • Pick up after pets.
    • Pet waste contains bacteria and can be a source of stormwater pollution.
  • Grow a garden or more plants.
    • Increasing the number of surfaces that can be infiltrated reduces the amount of stormwater runoff.
  • Notify the Township’s Code Enforcement Office at 724-446-7202 if you see any pollutants or non-stormwater discharge in the Township’s MS4 system or natural waterways.

Related Links and more information for the Township’s Stormwater Program:

Learn more:

Department of Environmental Protection (DEP)

Environmental Protection Agency (EPA)

Stormwater PA


Gibson-Thomas MS4 Info 1 of 2

Gibson-Thomas MS4 Info 2 of 2

How to help:

10 Ways to Prevent Stormwater Runoff

Center for Watershed Protection

Stormwater Smart PA

Permits and Reports:

Sewickley Township General Permit

2019-2020 MS4 Report

2018-2019 MS4 Report

2017-2018 MS4 Report

As required under its MS4 permit, the Township submits an MS4 Annual/Progress Report that reports actions that the Township has taken over the past year to reduce pollution in its MS4 and receiving waters. Click here to view the latest report.