Smaller text size Reset text size Larger text size
skip navigation
Air Rail Highway Bike/Ped Public Transit
The Water Quality Program ensures Department projects and programs are in compliance with various State and Federal water quality regulations and permitting programs, including: Alteration of Terrain, Section 401 of the Clean Water Act: Water Quality Certification, and various activities pursuant to the National Pollutant Discharge Elimination System administered by the EPA, including the 2017 Small Municipal Separate Storm Sewer System (MS4) permit.

What's New

Questions? Please Contact Mark Hemmerlein, Water Quality Program Manager,

National Pollutant Discharge Elimination System (NPDES)

Construction SiteSince the passage of the Clean Water Act (CWA) in 1972 the quality of our waters has improved significantly, however degraded water bodies still exist. Approximately 40% of these water bodies are still impaired and do not meet current water quality standards. Pollution from the following sources are the leading source of this impairment:

  • Construction site runoff
  • Urban/Suburban storm water runoff (MS4s)
  • Industrial facilities

The National Pollution Discharge Elimination System (NPDES) Phase I was initiated in 1990 under the CWA. This regulation covered the "medium" and "large" municipal separate sewer systems (MS4s) and included populations greater than 100,000 people. It also included construction activities that involved five (5) acres or more of soil disturbance. The third area of regulation included heavy industrial activity that included ten (10) industrial sectors. During Phase I, municipal activities, such as those conducted by NH DOT were considered exempt from regulation.

The NPDES Phase II "final rule" was signed in 1999 and became effective on March 10, 2003. This rule expanded on the NPDES Phase I rules and was intended to further protect and improve our nation's water bodies. Phase II included the addition of regulations covering "Small MS4" communities in 45 municipalities throughout New Hampshire and "small" construction activities. The Phase II rules have had a major impact on the New Hampshire Department of Transportation's operations as it included regulations of municipally owned industrial activities, which were exempt during Phase I.

Under both phases of NPDES states were given the authorization to choose whether they would like to be the permitting authority for NPDES regulated activities. The State of New Hampshire chose not to relinquish this right, making the US Environmental Protection Agency (EPA) the permitting authority for NPDES activities throughout the state of New Hampshire.

Each of the NPDES regulated activities are addressed in the following sections:

Construction Site Runoff

Construction SiteNPDES Phase I required that land disturbance greater than or equal to five (5) acres required coverage under the Construction General Permit (CGP). As of March 3, 2003 NPDES Phase II increased these requirements to include projects requiring land disturbance of greater than or equal to one (1) acre. Currently all projects disturbing greater than one acre of land require coverage under the Construction General Permit.

EPA considers the following activities "construction/land disturbance activities:" clearing, grading, excavation, stockpiling of fill material and other activities that expose soil related to projects that build, expand or replace or demolish something (such as a home, a store, a golf course, a road, etc.). EPA does not include routine earth-disturbing activities that are part of the day-to-day operation of a completed facility, such as landscape maintenance or the grading of existing gravel roads.

In order to obtain coverage under the CGP, NH DOT and/or its contractors are required to submit the following:

  • Notice of Intent (NOI) - The NH Department of Transportation AND its contractors are required to submit a Notice of Intent (NOI) at least 14 days prior to the beginning of any of the construction activities listed above. This NOI is intended to help identify all receiving water bodies of any construction runoff as well as indicate the presence of any threatened, endangered species or critical habitats are present within the project area. This NOI can be submitted electronically and viewed at the EPA's Electronic Stormwater Notice of Intent (eNOI) homepage.
  • Stormwater Pollution Prevention Plan (SWPPP) - The SWPPP is a plan developed by the contractor identifying the proposed erosion and sediment control techniques to be used on the project. This plan notes the appropriate Best Management Practices (BMP's) used to minimize the discharge of pollutants from the construction site. It is the responsibility of the Contractor to prepare the SWPPP to meet the requirements of the most recently issued CGP. The SWPPP must be submitted to NH DOT and approved by NH DOT prior to any work requiring land disturbance.
  • Notice of Termination (NOT) - The NH Department of Transportation AND its contractors are required to submit a Notice of Termination (NOT) upon completion of all land disturbing activities associated with the project.

Urban/Suburban Storm Water Runoff - Municipal Separate Storm Sewer Systems (MS4s)

No Dumping - Drains to BayMunicipal Separate Storm Sewer Systems (MS4s) are defined by the US Environmental Protection Agency (EPA) as a conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade channels or storm drains) which are designed or used for collecting or conveying stormwater and are not a combined sewer system nor part of a publicly owned treatment system. NPDES Phase I required that municipalities operating MS4s within large or medium urbanized areas, obtain an MS4 General Permit. NPDES Phase II increased this requirement to include small urbanized areas as well. 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.

East Kingston
Hampton Falls
New Castle
North Hampton

*Entire town/city is regulated. No *= Only part of the town is regulated

If an MS4 falls within an urbanized area, NPDES Phase II requires coverage under the MS4 General Permit. In order to obtain coverege under the General Permit submission or implementation of two (2) major components are required. The first component is the submission of a Notice-of-Intent (NOI) which requires general information about the owner and operator of the MS4, location of the MS4, and to what surface waters the MS4 discharges. The second component is the design and implementation of a Storm Water Management Plan (SWMP). The operator's SWMP is required to include measurable goals addressing Best Management Practices (BMPs) and the following six (6) minimum control measures:

  1. Public Education and Outreach
  2. Public Participation/Involvement
  3. Illicit Discharge Detection and Elimination
  4. Construction Site Runoff Control
  5. Post-Construction Runoff Control
  6. Pollution Prevention/Good Housekeeping

NH DOT operates MS4 systems to various extents in nearly every one of the 45 urbanized areas identified above. As a result NH DOT has implemented an extensive SWMP to meet the requirements of the MS4 General Permit.

Additional Information:


New Hampshire Department of Transportation
PO Box 483 | 7 Hazen Drive | Concord, NH | 03302-0483
Tel: 603.271-3734 | Fax: 603.271.3914

copyright 2015. State of New Hampshire