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New Hampshire Department of Environmental Services

Frequently Asked Questions
  • What is a Small MS4?
    Small MS4 stands for Small Municipal Separate Storm Sewer System. It is defined as a publicly owned conveyance or system of conveyances from ditches, curbs or underground pipes that divert stormwater into the surface waters of the state.
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  • What is a Municipality?
    Under the Phase II program, the following are considered municipalities:
    • United States, a state, city, town, borough, county, parish, district association or other public body.
    • US military installations, state or federal hospitals, county prison complexes, state colleges or universities, highways and other thoroughfares.
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  • Who will be required to apply for a MS4 General Permit in Phase II?
    A small MS4 is subject to storm water regulation if it is located within an "Urbanized Area"*

* Urbanized Areas - The Bureau of the Census has defined an "Urbanized Area" as a central place (or places) adjacent to a densely settled surrounding territory that together have a residential population of at least 50,000 and an average density of at least 1,000 people per square mile.

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  • What is required for an MS4 under Phase II?
    If your MS4 falls within an urbanized area, you must obtain the MS4 General Permit Adobe Acrobat Reader Symbol. The general permit requires the submission of a Notice-of-Intent (NOI) which requires general information about who owns and operates the MS4, where the MS4 is located, and to what surface waters the MS4 discharges. In conjunction with the NOI, a detailed storm water management program must be designed and implemented. Over the five year permit term, the operator is responsible for implementing a Storm Water Management Program including Best Management Practices and Measurable Goals to address the Six Minimum Control Measures that will control pollutants from all of the MS4 discharge points to the "Maximum Extent Practicable."

    For MS4s in the coastal watershed, there are two grants administered by NHDES that can help pay for required elements of one of the six minimum control measures, illicit discharge detection and elimination. Funding for these grants is provided by the New Hampshire Estuaries Project.

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  • When do MS4 facilities need to apply for a MS4 General Permit?
    The final MS4 General Permit was issued in the Federal Register and became effective on May 1, 2003. The permit requires that all owners and operators of small MS4 file their Notice of Intent applications by July 30, 2003.
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NH Department of Environmental Services | 29 Hazen Drive | PO Box 95 | Concord, NH 03302-0095
(603) 271-3503 | TDD Access: Relay NH 1-800-735-2964 | Hours: M-F, 8am-4pm

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