2022 County-wide Act 167 Stormwater Management Model Ordinance

On February 10, 2022, the Chester County Board of Commissioners adopted Resolution 06-22 to amend the County-wide Act 167 Stormwater Management Plan for Chester County, PA to replace the 2013 model ordinance with the 2022 County-wide Act 167 Stormwater Management Model Ordinance. 

Following the Commissioners’ adoption, Chester County submitted the adopted Model Ordinance and appendices to the Pennsylvania Department of Environmental Protection (PA DEP) for their review in accordance with the Pennsylvania Stormwater Management Act (PA Act 167). PA DEP reviewed the Model Ordinance and requested minor changes to improve consistency with their state-wide 2022 Stormwater Management Model Ordinance. Three changes were incorporated into the County-wide Model Ordinance to address PA DEP’s comments. PA DEP has reviewed these changes and noted that they have no further comments on the County-wide Model Ordinance. PA DEP will issue a final review letter upon the re-adoption of the updated ordinance. Subsections modified to address PA DEP's comments are listed below with a description of the changes made.

  • Subsection 305.A: The following text was removed from the adopted Model Ordinance: “or a minimum of one and one half (1.5)-inches of runoff from all Regulated Impervious Surfaces shall be managed. Whichever volume is greater shall be managed.” Thus, this section will remain unchanged from the 2013 Model Ordinance. 
  • Section 309.B: The reference to NOAA Atlas 14 was updated to state the following: “the latest version of the Precipitation-Frequency Atlas of the United States, National Oceanic and Atmospheric Administration (NOAA), National Weather Service, Hydrometeorological Design Studies Center, Silver Spring, Maryland (NOAA Atlas 14)”.
  • Section 706: The inspection requirements for both the municipal inspection (Option 1) and landowners inspection (Option 2) options were modified. Option 1 was modified to state that MS4 municipalities are required to inspect BMPs after each 25-year storm event. Language was also added to provide municipalities with the choice to request the owner of a BMP to complete an inspection after a 10-year event. Option 2 was modified to require inspections after each 10-year event, but inspection reports are only required to be submitted if requested by the municipality. 

Links to updated versions of the adopted Model Ordinance and supporting documents can be found below. The following documents were also updated for consistency with the changes to the Model Ordinance: Appendix B, Appendix E, the Matrix of Minimum Standards, Summary of Changes, and Summary of Options. Municipalities should reference these latest documents when updating their ordinance to be consistent with PA DEP’s 2022 Model Ordinance and the County-wide Act 167 Model Stormwater Ordinance. 

County-wide Act 167 Stormwater Management Ordinance

Note: It is recommended that municipalities adopt the Model Ordinance as a stand-alone ordinance. Municipalities do not need to submit their updated ordinance to the Chester County Planning Commission or the Chester County Water Resources Authority (CCWRA) prior to adoption. After the ordinance has been adopted, we ask that an electronic copy along with the completed “Certification of Ordinance Adoption” (linked below) be submitted to CCWRA at [email protected]

Implementation Resources 

The Chester County Water Resources Authority encourages all municipalities to begin reviewing the adopted Model Ordinance and assessing which optional provisions will be included in your updated ordinance. Municipalities with MS4 permits should plan to update their ordinances to be consistent with the updated County-wide Model Ordinance by September 30, 2022, or by the submission of the fourth Annual MS4 Status Report following permit coverage (for new permittees).. Below are additional resources to assist Municipalities with updating their ordinances to be consistent with the County-wide Model Ordinance. 

The updated Model Ordinance is the culmination of nearly three years of collaboration between Chester County, its municipalities, residents, and other stakeholders. Over this period, the Chester County Water Resources Authority hosted or presented at 36 in-person and virtual public and stakeholder input meetings designed to identify ways to improve the implementation and effectiveness of the County’s 2013 model ordinance. The County solicited additional input through the creation of a stormwater management survey that was distributed to municipalities and residents. The updated Model Ordinance was significantly shaped by the input received through these efforts. 

The updated Model Ordinance was designed to meet the needs of Chester County municipalities, fulfill the standards set forth in the Pennsylvania Storm Water Management Act (“Act 167”), and comply with the regulatory requirements of Pennsylvania Department of Environmental Protections’ (PA DEP) National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) program.  The updates incorporated into the Model Ordinance were also designed to comply with the provisions included in PA DEP's 2022 Model Stormwater Management Ordinance.  

Additional Resources

 Model Ordinance Implementation Workshops


The Chester County Water Resources Authority hosted two implementation workshops to assist municipalities with updating their stormwater ordinance. Links to the recordings and PDFs of presentations delivered at both workshops can be found at this page

Please email us at [email protected] with questions relating to the material presented at these workshops or if you have other questions about the updated Model Ordinance.