Storm Water

Stormwater Management

The Clean Water Act is the federal legislation that governs stormwater management. Stormwater point discharges to waters of the U.S. (pipes and drain pipes) are regulated using National Pollutant Discharge Elimination System (NPDES) permits. In 1999, federal regulations extended coverage of the NPDES program to local separate storm sewer systems (MS4’s) serving populations less than 100,000. In 2003, Denver Borough became an MS4 community and is required to comply with the NPDES program as an MS4. Under the NPDES stormwater program, the Borough is required to 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 a framework of six (6) minimum control measures:

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


Denver Borough’s Municipal Separate Storm Sewer System (MS4)


Denver Borough is a participant in and is complying with all the requirements of the Pennsylvania Department of Environmental Protection's (DEP) Municipal Separate Storm Sewer System (MS4) program. The goals of the MS4 program and Denver Borough are to reduce the discharge of pollutants from the Borough, to protect water quality, and to satisfy requirements of the Clean Water Act. Please remember that the water, and any items that go into a storm sewer, goes directly into local streams. This water is not cleaned in any way and does not go to the waste water treatment plant. Residents can assist in keeping our stormwater and stormwater system clean by doing the following: dispose of water properly, clean up after your pets, use fertilizers properly and efficiently to prevent excess runoff, and store potential pollutants indoors.


Please monitor stormwater inlets and drains near your property. No one should dump anything into the storm sewer system. Stormwater runoff occurs when precipitation such as rain or snow melt flows over the ground.  Impervious surfaces such as driveways, sidewalks, and streets prevent stormwater from naturally infiltrating into the ground.  As stormwater flows along streets, it picks up trash, leaves, pet waste, car fuels, and other pollutants like excess lawn fertilizers and pesticides.  This adds up to a lot of pollution to the Cocalico Creek and the Little Cocalico Creek.  For example, a single quart of motor oil can contaminate up to two (2) million gallons of drinking water.

If you see someone dumping please call the Denver Borough Municipal Building at 717-336-2831.


Denver Borough’s Stormwater Management Ordinance

On February 9, 2004, the Borough first adopted a Stormwater Management Ordinance whose purpose was to promote health, safety, and welfare within the Cocalico Creek Watershed.   On April 28, 2014, a new Stormwater Management Ordinance was adopted which complied with both Act 167 and MS4 requirements.  The purpose of the new ordinance is as follows:

  • Meet legal water quality requirements under state law, including regulations at 25 Pa. Code Chapter 93, to protect, maintain, reclaim, and restore the existing and designated uses of the waters of this commonwealth.
  • Preserve the natural drainage systems as much as practicable.
  • Manage stormwater runoff close to the source.
  • Provide procedures and performance standards for stormwater planning and management.
  • Maintain groundwater recharge to prevent degradation of surface and groundwater quality and to otherwise protect water resources.
  • Prevent scour and erosion of stream banks and streambeds.
  • Provide proper operation and maintenance of all stormwater management best management practices (SWM BMPs) that are implemented within the Borough of Denver.
  • Provide standards to meet NPDES permit requirements.
  • Promote stormwater runoff prevention through the use of nonstructural best management practices (BMPs).
  • Provide a regulatory environment that supports the proportion, density and intensity of development called for in the comprehensive plan; allow for creative methods of improving water quality and managing stormwater runoff; and promote a regional approach to water resource management.
  • Help preserve and protect exceptional natural resources, and conserve and restore natural resource systems.
  • Promote stormwater management practices that emphasize infiltration, evaporation, and transpiration.


Please click on the link below to access the Borough’s adopted Stormwater Management Ordinance.

Stormwater Management Ordinance – Adopted April 28, 2014

Please click on the links below to access the Borough’s MS4 Annual Reports.

2014 MS4 Annual Report (PDF)
2015 MS4 Annual Report (PDF)
2016 MS4 Annual Report (PDF)

2017 MS4 Annual Report (PDF)

2018 MS4 Annual Report (PDF)

2019 MS4 Annual Report (PDF)

2020 MS4 Annual Report (PDF)


For more information about stormwater management, please see the information displayed on bulletin boards in the Municipal Building and other various businesses throughout the Borough. You also can access one of the following links for information and resources: