Municipal Stormwater System

NPDES PAG-13 General Permit, MS4 Progress Report

The Borough of Lansdowne is one of approximately 1,000 jurisdictions in Pennsylvania that are considered small municipal separate stormwater systems (MS4's), requiring a permit
from the Pennsylvania Department of Environmental Protection (PADEP).

Stormwater Requirements

The stormwater requirements of the Federal Clean Water Act are administered under the Pennsylvania Department of Environmental Protection's Municipal Separate Storm Sewer
(MS4) Program. Under the MS4 Program, permittees are required to incorporate the following six elements (known as minimum control measures, or MCMS) into their Stormwater Management Programs:

  • Construction site runoff control
  • Illicit discharge detection and elimination
  • Pollution prevention and good housekeeping for municipal operations and maintenance
  • Post-construction stormwater management in new development and redevelopment
  • Public education and outreach
  • Public Involvement and participation

Best Management Practices

Each MCM has a series of suggested Best Management Practices (BMPs) associated with it to guide permit holders in the program development, tracking, and reporting.

Pool Water Rules in Pennsylvania

Check out the Department of Environmental Protection's website if you have any questions about draining your above ground pool and emptying your in-ground pool.

Pollution Control Over Stormwater

"Illicit Discharge" 

Federal regulations define an illicit discharge as "…any discharge to an MS4 that is not composed entirely of stormwater…" with some exceptions.

Included Exceptions

These exceptions include discharges from NPDES-permitted industrial sources and discharges from fire-fighting activities. Illicit discharges are considered "illicit" because MS4s are not designed to accept, process, or discharge such non-stormwater wastes.

Table 1 (Illicit Discharges)
Sources of Illicit Discharges include the following:

  • Car wash wastewaters
  • Effluent from septic tanks
  • Improper disposal of auto and household toxins
  • Improper oil disposal
  • Laundry wastewaters
  • Radiator flushing disposal
  • Sanitary wastewater
  • Spills from roadway accidents

Why Illicit Discharge Detection & Elimination Efforts Are Necessary

Discharges from MS4s often include wastes and wastewater from non-stormwater sources. A study conducted in 1987 in Sacramento, California, found that almost one-half of the water discharged from a local MS4 was not directly attributable to precipitation runoff. A significant portion of these dry weather flows was from illicit and/or inappropriate discharges and connections to the MS4.

Direct Connections

Illicit discharges enter the system through either direct connections (e.g, wastewater piping either mistakenly or deliberately connected to the storm drains) or indirect connections (e.g, infiltration into the MS4 from cracked sanitary systems, spills collected by drain outlets, or paint or used oil dumped directly into a drain). The result is untreated discharges that contribute high levels of pollutants, including:

  • Bacteria to Receiving Water Bodies
  • Heavy Metals
  • Nutrients
  • Oil and Grease
  • Solvents
  • Toxins
  • Viruses

Pollutant Levels

Pollutant levels from these illicit discharges have been shown in EPA studies to be high enough to significantly degrade receiving water quality and threaten aquatic, wildlife, and human health.

Report a Stormwater Pollution Incident

To report a stormwater pollution incident, please use the "how may we help you" form or report a municipal services concern.