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Municipal Stormwater

Program Updates

Notices of Intent (NOIs):

NOIs (3800-PM-BCW0100B) to remain covered under the PAG-13 General Permit are not due in September 2022. In September 2017, NOIs were due to remain covered under the PAG-13 General Permit that became effective on March 16, 2018. When the statewide PAG-13 General Permit is reissued by DEP, as was done in March 2018, MS4s covered by the previous PAG-13 General Permit are automatically covered by the reissued PAG-13 General Permit if a timely NOI is submitted by the MS4.

DEP will notify MS4s of the new due date for NOI submission when that date is determined.

Annual Status Reports:

MS4 Annual Status reports (3800-FM-BCW0491) are due by September 30, 2022.

Municipal permittees must submit copy of an ordinance that is consistent with DEP’s 2022 Model Stormwater Management Ordinance (3800-PM-BCW0100j) as an attachment to an Annual MS4 Status Report by September 30, 2022 (existing permittees) or the fourth Annual MS4 Status Report following approval of permit coverage (new permittees).

Permittees that lack the authority to enact ordinances (non-municipal permittees and counties) are required to develop and adopt a Standard Operating Procedure (SOP) that prohibits non-stormwater discharges consistent with the General Permit, and must submit a copy of the SOP as an attachment to an Annual MS4 Status Report by September 30, 2022 (existing permittees) or the fourth Annual MS4 Status Report following approval permit coverage (new permittees).

MS4 Frequently Asked Questions (FAQ) Document:

The MS4 FAQ provides general information on the MS4 program as well as concepts relevant to Pollutant Reduction Plans (PRPs) and TMDL Plans. Periodic updates to the MS4 FAQ are published as needed.


Municipalities and other entities such as universities and prisons that meet certain standards must obtain NPDES permit coverage for discharges of stormwater from their municipal separate storm sewer systems (MS4s). In Pennsylvania, there are two Large MS4s, no Medium MS4s, and 1059 Small MS4s.

MS4s must apply for NPDES permit coverage or a waiver if they are located in an urbanized area as determined by the latest Decennial Census by the U.S. Census Bureau, or if they are designated as needing a permit by DEP. EPA has posted Urbanized Area Maps from the 2010 census data.

For NPDES permits issued after 2017, MS4s that discharge to surface waters impaired for certain pollutants or that discharge to waters in the Chesapeake Bay watershed were required to develop Pollutant Reduction Plans (PRPs) or TMDL Plans. See the PRP/TMDL Plans webpage for further information.

NPDES Permits

Small MS4s that are required by federal regulations to obtain NPDES permit coverage may, if eligible, apply for coverage under the NPDES General Permit for Stormwater Discharges from Small MS4s (PAG-13) (3800-PM-BCW0100) that is currently in effect. Small MS4s that are ineligible for PAG-13 General Permit coverage may apply for an individual permit (3800-PM-BPNPSM0200).

Permit coverage is generally for a 5-year term. To renew coverage for a new term, MS4 permittees must submit an individual permit application or a NOI to discharge under the statewide General Permit prior to the expiration date of coverage, as specified in the permit. The MS4 can, if it chooses, elect to apply for an individual NPDES permit in lieu of continued coverage under the reissued General Permit.

DEP has developed a reporting tool that can be used to search NPDES-permitted and waived MS4s in Pennsylvania.


DEP's regional offices inspect MS4s to determine if the MS4 is meeting its permit obligations. The inspections are documented on a MS4 inspection report (3800-FM-BPNPSM0489). DEP also reviews the Annual Status Reports (3800-FM-BCW0491) submitted by MS4s to DEP.

Contact Us

For questions on MS4 NPDES permits and compliance in Pennsylvania, contact DEP’s Bureau of Clean Water (BCW) at or 717-787-5017.