MS4 Toolbox

According to the federal law commonly known as Stormwater Phase II, permits are required for stormwater discharges from Municipal Separate Storm Sewer Systems (MS4s) in urbanized areas and those additionally designated by the New York State Department of Environmental Conservation (NYSDEC). Owners or operators of such MS4s must be authorized in accordance with the State Pollutant Discharge Elimination System (SPDES) General Permit for Stormwater Discharges from Municipal Separate Storm Sewer Systems (MS4 GP).

This page contains information and reference material that will aid in the implementation of a Stormwater Management Program (SWMP) and provide assistance in meeting the MS4 GP and program requirements.

SPDES MS4 GP-0-24-001 Resources:

The SWMP Plan Components Tool and Compliance Items Summary Tool

  • Refer to the permit for all requirements that need to be implemented by the MS4 Operator. GP-0-24-001 is the ruling document.
    • These are tools, meant to be updated by the MS4 Operator, as needed.
    • There are tabs in each tool indicating the respective parts of GP-0-24-001. It is up to the MS4 Operator to determine which parts are necessary for permit implementation.
  • SWMP Plan Components Tool (xls)
    • Each row indicates a component to include in the SWMP Plan with its respective permit reference. 
    • Note: If there is a permit requirement that is not applicable to the MS4 Operator, it must be noted in that MS4 Operator's SWMP Plan. 
  • Compliance Items Summary Tool (xls)
    • Each row indicates a compliance item with its respective permit reference and compliance timeframe. 
    • Note: Compliance timeframes for contingency items (e.g., Within thirty (30) days of an illicit discharge, the MS4 Operator must document each report of an illicit discharge in the SWMP Plan) are not included in the tool.
    • MS4 Six Month Compliance Check-in: Recording, Presentation (PDF), and Transcript (PDF) Updated: June 4, 2024

Overview of the Minimum Control Measures (MCM)

The MS4 GP requires development of a SWMP that includes the six required program components, or the six minimum control measures (MCMs).

1. Public Education and Outreach

The MS4 Operator must develop and implement an education and outreach program to increase public awareness of pollutant generating activities and behaviors. This MCM is designed to inform the public about the impacts of stormwater on water quality, the general sources of stormwater pollutants, and the steps the general public can take to reduce pollutants in stormwater runoff.

2. Public Participation/Involvement

The MS4 Operator must provide opportunities to involve the public in the development, review, and implementation of the SWMP. This MCM is designed to give the public the opportunity to include their opinions in the implementation of this SPDES general permit.

3. Illicit Discharge Detection and Elimination

The MS4 Operator must develop, implement, and enforce a program which systematically detects, tracks down, and eliminates illicit discharges to the MS4. This MCM is designed to manage the MS4 so it is not conveying pollutants associated with flows other than those directly attributable to stormwater runoff.

4. Construction Site Runoff Control

The MS4 Operator must develop, implement, and enforce a program to ensure construction sites are effectively controlled. This MCM is designed to prevent pollutants from construction related activities, within the automatically and additionally designated areas, as well as promote the proper planning and installation of post-construction stormwater management practices.

5. Post-construction Runoff Control

The MS4 Operator must develop, implement, and enforce a program to ensure proper operation and maintenance of post construction SMPs for new or redeveloped sites. This MCM is designed to promote the long-term performance of post-construction SMPs in removing pollutants from stormwater runoff.

6. Pollution Prevention/Good Housekeeping

The MS4 Operator must develop and implement a pollution prevention and good housekeeping program for municipal facilities and municipal operations to minimize pollutant discharges. This MCM is designed to ensure the MS4 Operator's own activities do not contribute pollutants to surface waters of the State.

MS4 Maps

Automatically and Additionally Designated Areas

The regulatory requirements apply to MS4 Operators within the automatically designated areas as identified by the US Census and areas that have been additionally designated by NYSDEC (with the exception of minimum control measures 4 and 5, which apply to the municipal boundaries, unless a waiver is granted). For a map of the automatically designated areas in NYS identified by the US Census Bureau, please visit the Stormwater Interactive Map.

The map books (below) highlight the 2000 and 2010 automatically designated area boundary, as well as the additionally designated boundaries. The map books are organized by county and are intended to assist MS4 Operators in the development and implementation of their SWMP.

How to use the map books

To use these maps books select the county of the municipality (please note that some of the map books contain more than one county). The first page is an index of the maps and shows the map key. Use the map index to locate the area of interest and scroll to that map page. Again, please note that the area of interest may lie on more than one map page. Note: these maps are large files and may take a few minutes to load. All of these files access DEC's FTP site, which is not available using many web browsers. We suggest you use Internet Explorer 11 or a file transfer software like Filezilla to access these files.

Local School District Decision Tree for MS4 Determination

Each school property within a school district needs to be evaluated separately. Contiguous properties are considered as one.

Any "no" answers will likely result in eligibility for a waiver1 from the program

  1. Does the school property in question have more than a single building? In 40 CFR 122.26(b)(16)iii, EPA clarifies that the definition of small MS4 does not include individual buildings. The NYSDEC defines a building as schools, administration and office buildings, maintenance and bus garages, athletic buildings, equipment and grounds keeping buildings, but not sheds (If yes go to 2)
  2. Is the school property in question located wholly or partially within the Automatically Designated Urbanized Areas or the New York State Additionally Designated Areas ? Check the Stormwater Interactive Map on DEC's website to help determine whether your district has school property located within the Automatically Designated Urbanized Areas or the Additionally Designated Areas boundaries. (If yes go to 3)
  3. Does the property in question have a daytime population of more than 1000 students/staff ? (If yes go to 4 ) if no, then see waiver criteria below taken from EPA factsheet 2.1. Property may be eligible for a waiver. (If not eligible for waiver go to 4)
  4. This property is subject to the MS42 phase II program requirements

1Waiver Criteria

  1. the jurisdiction served by the system is less than 1,000 people;
  2. the system is not contributing substantially to the pollutant loadings of a physically interconnected regulated MS4; and
  3. if the small MS4 discharges any pollutants identified as a cause of impairment of any water body to which it discharges, storm water controls are not needed based on wasteload allocations that are part of an EPA approved or established "total maximum daily load" (TMDL) that addresses the pollutant(s) of concern.

2Definition of an MS4

40 CFR 122.26(b)(8) "municipal separate storm sewer means a conveyance or system of conveyances (including roads
with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, or storm drains):

  1. Owned or operated by a State, city, town, borough, county, parish, district, association, or other public body (created by or pursuant to State law)...including special districts under State law such as a sewer district, flood control district or drainage district, or similar entity, or an Indian tribe or an authorized Indian tribal organization, or a designated and approved management agency under section 208 of the Clean Water Act that discharges into the waters of the United States." (Note: "Waters of the United States" refers to surface water only.)
  2. Designed or used for collecting or conveying storm water
  3. Which is not a combined sewer; and
  4. Which is not part of a Publicly Owned Treatment Works (POTW) as defined at 40 CFR 122.2" According to 40 CFR 122.26(b)(16)iii, small MS4s (population less than 100,000) "includes systems similar to separate storm sewer systems in municipalities, such as systems at military bases, large hospitals or prison complexes, and highways and other thoroughfares. The term does not include separate storm sewers in very discrete areas such as individual buildings."

Guidance Documents

Stormwater Management Guidance Manual for Local Officials (PDF) - This is guidance for local officials on complying with state and federal stormwater management requirements, minimum control measures 4 and 5, as well as developing and implementing local SWMPs.

The New York State Department of Environmental Conservation Model Local Law to Prohibit Illicit Discharges, Activities and Connections to Separate Storm Sewer Systems, April 2006 (PDF) - This model local law is intended to be a tool for communities that are subject to the MS4 General Permit.

The New York State Department of Environmental Conservation Sample Local Law for Stormwater Management and Erosion & Sediment Control, March 2006 (PDF) - This model local law is intended to be a guidance tool for communities that are subject to the MS4 General Permit.

Decision Tree for MS4 Waiver I (PDF) - The document will help MS4s evaluate eligibility for Waiver I.

Census Blocks with Population List (Excel) - This spreadsheet provides the population, based on the 2010 Census, of every census block within the Automatically Designated Boundaries of New York State. This list will help determine the total population within a municipality's Automatically Designated Boundary when evaluating eligibility for a waiver.

USGS StreamStats – This web-based tool is a free and easy way to delineate watersheds.

Wet Weather Visual Monitoring – This guide can be used when conducting wet weather visual monitoring at high priority municipal facilities per GP-0-24-001. 

The Center for Watershed Protection Illicit Discharge Detection and Elimination Guidance Manual, 2004 – This guidance is referenced throughout GP-0-24-001 to assist with monitoring location inspection and sampling. 

Catch Basin clean out Fact Sheet (pending)

Resources for Newly Designated MS4 Operators

The USEPA identified new MS4 Operators based on the 2010 Census urbanized areas maps. The designation requires coverage the under the General Permit for Stormwater Discharges from Municipal Separate Storm Sewer Systems.

Newly designated MS4 Operators are encouraged to review the General Permit for Municipal Separate Storm Sewer Systems, GP-0-15-003, forms, and supplemental documents. These documents are available on the Stormwater MS4 Permit and Forms web page.

MS4 Introduction and Overview Presentation (PDF) - This presentation is an overview and introduction to the MS4 program.

USEPA's National Menu of Best Management Practices (BMPs) for Stormwater - A link leaving the NYSDEC's website to the USEPA compiled list of BMPs for each Minimum Control Measure.

USEPA's Stormwater Phase II Final Rule Fact Sheet Series- A link leaving the NYSDEC's website to the USEPA fact sheets about small MS4 programs, minimum control measures, and permitting.

Recommendations for Stormwater Managers

Developing, implementing, and enforcing a SWMP involves additions and modifications to many areas of responsibility. Stormwater program coordinators must make sure that municipal personnel (elected officials, professional staff, and laborers) are informed about the value and necessity of the SWMP, assigned appropriate responsibilities, provide technical and procedural training, and have appropriate performance standards.

SWMPs should be designed to work in concert with other water resource improvement projects. When possible, stormwater program coordinators should use inter-municipal partnerships to improve efficiency, promote consistency, and reduce costs.

Partners Available to Assist MS4 Operators

Assistance may be available for MS4 Operators from the following organizations:

Funding Opportunities

MS4 Draft Funding Document (PDF) - This was developed to summarize the provisions in existing state law that may allow for the funding of the local share of the MS4 program.

Contact for this Page

Division of Water
625 Broadway
Albany, NY 12233

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