Stormwater MS4 permit

Montgomery County is required to have a Municipal Separate Storm Sewer System (MS4) permit for urbanized areas to prevent the discharge of pollutants such as pet waste, trash, engine oil and fertilizers into waterways.

The Permit conditions strictly apply to the County's urbanized areas draining through County maintained stormwater conveyances and requires the County to develop a stormwater management program that demonstrates the County addresses the following minimum control measures (MCMs):

Public education and outreach on stormwater impacts, and public involvement and participation (MCM 1 and 2)

Students gather around a model to learn how stormwater impacts the terrain.

These measures address the need to increase knowledge of the hazards of improper disposal or discharges to our watersheds, of steps that can be taken to reduce stormwater pollution, and to encourage public participation in events that reduce stormwater pollutants. Find our library of printable materials and our annual reports detailing outreach and participation events on our resources page.

The County would like to hear from residents with comments or suggestions on the MS4 Program Plan or other aspects of the program. Contact Stormwater Specialist John Burke at

Illicit discharge detection and elimination (MCM 3)

The County has an Illicit Discharge Ordinance and tracks illegal stormwater pollutants. This information is provided in the MS4 Outfall Map, which also provides the latest inspection results. As part of Illicit Discharge Detection and Elimination (IDDE), the County encourages the public to report stormwater problems (form) (email).

Related documents

Construction site stormwater runoff control (MCM 4)

The County's Stormwater Ordinance and the Administrative Manual address compliance with the requirements associated with the regulation of land disturbing activities. Complete documents and publications are found at Land Development.

Post-construction stormwater management in new and re-development (MCM 5)

The County was notified of approval as a VSMP Authority on June 25, 2014. The County maintains information on Public Stormwater Facilities and Private Stormwater Facilities within the regulated urbanized area and is required to insure adequate long-term operation and maintenance of these facilities. Section 9 of the Administrative Manual and Postconstruction Inspection Guidance provide policies and procedures for these compliance activities.

Pollution prevention/good housekeeping for municipal operations (MCM 6)

The County's Good Housekeeping Procedures and IDDE Field Guide provide staff with policy and guidance to minimize or prevent pollution discharges from municipal operations. Training is scheduled in accordance with a Municipal Training Program to increase staff awareness of good housekeeping procedures.

Stormwater Pollution Prevention Plans (SWPPP) documents are developed for the Montgomery County Public Schools Facilities Site. This high priority county facility within the MS4 service area is identified as having a high potential for discharging pollutants.

State-approved 2021 Nutrient Management Program (Part 1) and  2021 NMP (Part 2). Documents provide guidance for the proper application of nutrients to specific sites requiring these plans. The Virginia Department of Conservation and Recreation (DCR) accepted these plans effective Aug. 4, 2021 (Part I, Part II). The  Urban Nutrient Management Handbook guides the public and staff on how to properly apply nutrients to ensure plant health, while minimizing the movement of phosphorous and nitrogen in the environment.