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New Hampshire Department of Environmental Services

Frequently Asked Questions
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  • What is a wetland?

    An area that, either through surface water or ground water, is wet enough and wet for a long enough period of time, to support a predominance of vegetation that grows in saturated soil conditions. In order for an area to be deemed at wetland, all three (3) of the following must be present:

    • Hydric soils – soils that are saturated or flooded during the growing season sufficient to produce anaerobic conditions in the upper soil layers.
    • Hydrophytic vegetation – greater than 50% of the vegetation present is adapted for life in saturated soil conditions.
    • Hydrology – Evidence exists that demonstrates the soils in the area are inundated with water either permanently or periodically at some time during the growing season.

    Examples of wetlands include, but are not limited to: swamps, bogs, marshes, forested wetlands, wet meadows and vernal pools. Forested wetlands are the most difficult to identify. Use these clues to identifying forested wetlands.

    Helpful Documents:

* NHDES does not provide wetland delineation services. To confirm the presence of a wetland on your property, we recommend contacting a NH Certified Wetland Scientist (CWS).

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  • What areas are regulated under NH Wetlands Law?

    A Wetlands Permit from the NHDES Wetlands Bureau is required for excavating, removing, filling, dredging or constructing structures within the following jurisdictional areas:

    • Wetlands, such as forested, scrub-shrub, emergent wetlands, marshes, wet meadows and bogs.
    • Surface waters, including the beds and banks of streams, rivers, lakes, ponds and tidal areas.

    An illustration of a lake, the lake's bank and the bed of the lake.
    An illustration of a lake, the lake's bank and the bed of the lake.

      • The tidal buffer zone, which is the area extending landward 100 feet from the highest observable tide line. This area can contain wetlands, transitional areas, and natural and developed upland.
      • The prime wetland buffer, which is the 100 foot upland buffer for wetlands that have been municipally designated as prime wetlands and at the time of their designation a 100-foot upland buffer was required.
      • Sand dunes, which is a hill or ridge of sand piled up by the wind and commonly found on the Seacoast
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  • What are the wetlands setbacks?

    Under NH Wetlands Law, there are no setbacks. Many municipalities have more stringent standards and include wetlands buffers and setbacks. Several specific resource types in NH have buffers (added levels of protection) and, under RSA 485-A, there are setbacks when installing new septic systems.

    Prime Wetlands: Under RSA 482-A:15, several municipalities in NH have "Designated Prime Wetlands."  Some municipally designated prime wetlands have a 100 foot prime wetland buffer zone. Please use the Prime Wetlands Web tool to determine if a municipality has Designated Prime Wetlands.

    Tidal Buffer Zone: The area extending landward 100 feet from the highest observable tide line. This area can contain wetlands, transitional areas, and natural and developed uplands.

    Waterbodies Protected under the Shoreland Water Quality Protection Act (SWQPA): Under RSA 483-B, all lakes and ponds greater than 10 acres, all 4th order and greater streams and rivers and all waterbodies subject to the ebb and flow of the tide are protected. Under the SWQPA, there is a 50 foot primary structure setback and a 20 foot accessory structure setback. There are also limitations on removing vegetation adjacent to these waterbodies and this is explained within the Vegetation Management for Water Quality fact sheet.

    Septic Systems: Under RSA 485-A, the NHDES Subsurface Systems Bureau requires that new septic systems are installed at least 75 feet from wetlands having very poorly drained soils and 50 feet from wetlands having poorly drained soils. When installing septic systems within the protected shoreland, if the receiving soil of the septic system is a porous sand and gravel material with a percolation rate equal to or faster than 2 minutes per inch, the setback is at least 125 feet from the reference line of the waterbody.

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  • What activities require a wetlands permit?

    A permit from the NHDES Wetlands Bureau is required for excavating1, filling2, dredging3 and removing or constructing structures within areas jurisdictional under wetlands law.

    Examples of common activities that require a NHDES Wetlands Permit include, but are not limited to:

    • Construction of roadways or driveways
    •  Installing new culverts
    • Driving through wetlands and/or removing vegetation when soils are rutted or the roots of vegetation are disturbed
    • Maintenance, repair or replacement of culverts, bridges, dams and other structures
    • Logging activities
    • Trail construction
    • Utility inspection, maintenance and repair (electric, gas, water)
    • Pond construction and maintenance dredging
    • Beach construction or replenishment of beach sand
    • Constructing and repairing boat houses
    • Constructing and repairing breakwaters
    • Construction, modification and repair of docking structures
    • Installing watercraft lifts
    • Construction repair or modification of any retaining wall
    • Removing sand dune vegetation

    1 Excavating: to dig, remove, or form a cavity or a hole in an area within department's jurisdiction

    2 Filling: to place or deposit materials in or on a wetland, surface water body, bank or otherwise in or on an area within the jurisdiction of the department

    3 Dredge: to dig, excavate, or otherwise disturb the contour or integrity of sediments in the bank or bed of a wetland, a surface water body, or other area within the department's jurisdiction

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  • How do I determine temporary and permanent wetland impacts?

    Temporary wetland impacts are jurisdictional areas impacted by excavation, filling, or placing timber matting that only temporarily impact wetlands and the wetlands are allowed to fully restore upon completing the project. Temporary Impacts often include, but are not limited to: Areas excavated for burying utility lines, installing temporary equipment access ways and for installing temporary erosion controls.

    Permanent wetland impacts are areas that are altered, excavated, dredged or filled to a state that is irreversible and the lasting effects will be permanent. Permanent wetlands impacts include, but are not limited to: The fill associated with a wetland crossing, bridge abutments, culverts and excavation associated with ponds, ditches and channels.

  • How long is a wetlands permit valid?

    With the exception of Wetlands Minimum Impact Forestry Notifications, Recreational Mineral Dredging Permits and 10 year wetlands permits issued to repair or replace shoreline structures, wetlands permits are valid for 5 years.

    • Wetlands Minimum Impact Forestry Notifications are valid for two years
    • Recreational Mineral Dredging permits expire at the end of the calendar year in which they are issued
    • Wetlands permits issued to repair or replace shoreline structures to maintain their safety and integrity such as, but not limited to: docks, sea walls, breakwaters, riprap, access ramps and stairs that are damaged by storms or ice are valid for 10 years provided any work performed after the initial permitted work is completed meets the following conditions:
      • The original permit has not been revoked or suspended without reinstatement;
      • All structures are repaired or replaced to the original permitted location and configuration; and
      • All significant work is reported to the department in accordance with the reporting requirements for the original permit.
  • Can a wetlands permit be extended?

    With the exception of Wetlands Minimum Impact Forestry Notifications, Recreational Mineral Dredging Permits and 10 year wetlands permits issued to repair or replace shoreline structures, a single wetland "permit extension," not exceeding 5 years may be granted, provided the applicant demonstrates all of the following:

    (1) The permit for which the extension is sought has not been revoked or suspended without reinstatement;
    (2) The extension does not violate a condition of law or rule;
    (3) The project is proceeding towards completion in accordance with plans and other documentation referenced by the permit; and
    (4) The applicant proposes reasonable mitigation measures to protect the public waters of the state from deterioration during the period of extension.
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  • What is mitigation and when is it required?

    Mitigation is a way to ensure a project does not create a net loss of wetland functions and values. NHDES requires mitigation for the following projects:

    • Major impact projects, including those that:
      • will alter the course of or disturb 200 linear feet or more of an intermittent or perennial nontidal stream or river channel or its banks.
      • involve construction of a pond with more than 20,000 square feet of impact in a wetland or surface water.
      • involves only the installation of accessory docking structures or the construction of new shoreline structures and breakwaters, or includes such work in combination with other qualifying criteria, provided the resulting dock surface area of all new shoreline structures on the frontage is 2,000 or more square feet.
    • Minor impact projects with permanent jurisdictional impacts of 10,000 square feet or greater.

    To learn more about wetlands mitigation, visit the Wetlands Mitigation Program Page.

  • What is the highest observable tide line?

    Highest observable tide line is a line defining the farthest landward limit of tidal flow, not including storm events, that can be recognized by indicators such as the presence of a strand line of debris, the landward margin of salt tolerant vegetation, or a physical barrier that blocks farther flow of the tide.

  • What is the developed upland?

    Developed upland is the upland area within the tidal buffer zone where:
    (a) the natural soil and vegetation characteristics over a majority of the lot have been legally altered and have not returned to a natural state; and (b) the area contains at least two of the following criteria:

    (1) filled or excavated land
    (2) paved or graded land in use as a parking lot or a roadway
    (3) a lot occupied by residential or commercial buildings; or
    (4) a lot which is surrounded by residentially or commercially developed lots on at least two sides.

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  • Can I cut or remove trees and vegetation within a wetland?

    The mowing and cutting of vegetation, including trees, within wet meadows or forested wetlands, such as red maple swamps, hemlock swamps, spruce/ fir swamps and white pine swamps, is permissible without a wetlands permit provided the following conditions are met:

    (1) The roots of the vegetation are not disturbed;
    (2) The ground is frozen or sufficiently dry to avoid making ruts;
    (3) The area is stabilized once thawed; and
    (4) The project is not located within a prime wetland, prime wetland buffer zone, or 100 foot tidal buffer zone.

    There are limitations on removing vegetation adjacent to many surface waters of the state and this is explained within the Vegetation Management for Water Quality fact sheet.

    Always check with local town ordinances because they are often more stringent than state standards.

  • What are Best Management Practices (BMPs)?

    BMPs are publications created to promote a better understanding of valuable resources and they provide methods for minimizing impacts to them. A list of wetland BMP resources can be found on the NHDES Wetlands bureau website.

  • When do I need to do a pre-application meeting?

    Pre-applications are necessary when a project requires mitigation.  
    Contact us to set up a meeting.

  • What is the Natural Heritage Bureau (NHB)?

    The Natural Heritage Bureau (NHB) maintains data on known locations of rare species and exemplary natural communities. The NHB DataCheck Tool allows anyone planning a project in New Hampshire that requires a permit to find out if there are NHB records in the vicinity of the project.

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  • What does "grandfathered status" mean?

    Grandfathered status means that a structure was constructed in place prior to the NHDES Wetlands Bureau's permitting jurisdiction under RSA 482-A:3, I or it predecessor statute, RSA 483-A:1, I took effect.

    In order for a structure to be considered grandfathered, it must meet all of the following criteria:

    Construction/ Impact date:

    For areas adjacent to tidal waters, constructed prior to 1967

    For seasonal docking structures on lakes or ponds, installed prior to 1978

    For all other permanent structures, wetlands constructed, or wetlands impacted prior to 1969

    Structure Specifics:

    Since the initial construction/ installation, the structure has remained unaltered in location, size and configuration and has not been abandoned.

  • What is considered a "structure"?

    Structure means something installed, erected or constructed in a fixed location. Examples of structures include, but are not limited to: fence, dock, breakwater, post, pile, building, bridge, culvert and wall.

    Structures do not include, provided their construction does not require any regrading or recontouring of a waterbodie's shoreline and they're not constructed over a waterbody: bench, a landing with dimensions no larger than 10 feet wide by 10 feet long, or stairs with a width not exceeding 6 feet.

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  • What is bankfull depth?

    Bankfull depth is the vertical depth of a river/stream channel measured from the bed to the estimated water surface elevation required to completely fill the channel (bankfull width). If water were to exceed the bankfull depth, it would enter the floodplain or exit the river/stream channel. Max bankfull depth is measured from the deepest part of the channel (thalweg). Mean bankfull depth is the average depth measured along several cross-sectional areas. The bankfull depth corresponds with the start of a floodplain, which can be characterized by the following:

    • Topography – usually noted as a berm or break in the slope from the channel bank to a flatter surface
    • Vegetation – a change from bare surfaces or water tolerant species to semi-water tolerant or upland species
    • Sediment Texture – change in the size distribution of sediments

In cases where multiple channels exist, bankfull depth is the average depth of all the river/stream channels along a cross section.

An illustration showing the calculation of bankfull depth, which factors in the flood-prone width and bankfull width.
Bankfull depth is used to determine Rosgen Stream Classification.

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  • What is bankfull width?

    Bankfull width is the distance between the banks at bankfull stage (channel forming flow which is typically the 1.5 to 2 year storm event).

  • What is an entrenchment ratio?

    Entrenchment ratio is the flood prone width divided by the bankfull width. Entrenchment ratio is the vertical containment of a river as seen by the relationship between the channel (within the bankfull width) and the surrounding floodplain (within the flood prone width). The lower the ratio, the more entrenched a channel is. Entrenchment ratio helps determine the vertical containment of the river, which should be considered when designing a crossing structure.

    An illustration showing the calculation of bankfull depth, which factors in the flood-prone width and bankfull width.
    A series of diagrams showing the entrenchment ratio of various stream types.

  • What is sinuosity?

    A measure of a river's tendency to meander, move throughout a flood plain, or deviate from the shortest possible path, expressed as the ratio of actual channel length (AB) to straight-line valley length (CD).

    An diagram showing examples of what to measure to determine a stream's sinuosity.
    A diagram showing the calculation that provides a stream sinuosity.

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  • What is bankfull cross-sectional area?

    Bankfull cross-sectional area is the bankfull width multiplied by the mean bankfull depth.

  • What is width to depth ratio?

    Width to depth ratio is the ratio of the bankfull width divided by the mean bankfull depth.

  • What is flood prone width?

    The flood prone width is measured at the elevation that corresponds to twice the max bankfull depth.

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NH Department of Environmental Services | 29 Hazen Drive | PO Box 95 | Concord, NH 03302-0095
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