New York District Header Image


Home > Missions > Regulatory  > Wetlands Identification

Wetlands Identification

What Are Wetlands?

Wetlands are defined as those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions.  Wetlands are transitional areas between open water and dry land and are often found along bays, lakes, rivers and streams.  Examples include bottomland forests, swamps, bogs, marshes, wet meadows and seasonal wet woods.

Wetlands may not be obvious for particular wetland types or at all times of the year.  Many forested wetlands and wet meadows are wet only during part of the year.

Why are wetlands important?

Besides performing important water quality functions such as filtration, wetlands provide food and habitat for an abundance and diversity of life unrivaled by most other types of environments.  Along with open water, they are breeding, spawning, feeding, cover and nursery areas for fish and are important nesting, migrating, and wintering areas for waterfowl and other wildlife.

Wetlands also serve as buffer areas to protect shorelines and stream banks from erosion and storm surges, and act as natural water storage areas during floods and groundwater recharge areas.  In addition, wetlands assimilate, recycle, filter and remove pollutants from water.

Why do wetlands need to be identified?

Section 404 of the Clean Water Act requires Corps authorization for the discharge of dredged or fill material into waters of the United States.  Waters of the United States include wetlands, intermittent and perennial streams, ponds, rivers, lakes and the territorial seas.  Activities in waters of the United States for which permits may be required include, but are not limited to, placement of fill material, land clearing involving relocation of soil, road construction, shoreline erosion control, mining, utility line or pipeline construction and other activities which result in a discharge of fill material.  Discharges of fill material are regulated under Section 404 for all waters of the United States regardless of size.

Wetlands in New York may also be regulated by the New York State Department of Environmental Conservation.  Their Freshwater Wetlands Act protects those freshwater wetlands in the state that are greater than 12.4 acres in size, and any smaller wetland of unusual local importance.  The Freshwater Wetlands Act grants the administration of wetlands protection within the Adirondack Park to the Adirondack Park Agency.  Wetlands over 1 acre in size, or any size wetland adjacent to open water are regulated within the Adirondack Park.

Recognizing Wetlands

The Corps uses three characteristics to determine if an area is a wetland: vegetation, soil and hydrology.  Unless an area has been altered or is a rare natural situation, indicators of all three characteristics must be present for an area to be a wetland.

  • Vegetation
    Wetland vegetation consists of plants that require saturated soils to survive as well as plants that gain a competitive advantage over others because they can tolerate prolonged wet soil conditions.  Over 5,000 plant types in the United States may occur in wetlands.  For example cattails, rushes, ferns, sedges, red maples, elms, and willows usually occur in wetlands.  Wetland vegetation may also exhibit physical adaptations that indicate the presence of water.  These adaptations include shallow root systems, swollen trunks or roots growing from the plant stem or trunk above the soil surface.

  • Soils
    Soils that occur in wetlands are called hydric soils.  Hydric soils have characteristics that indicate they were developed in conditions where soil oxygen is/or was limited by the presence of water for long periods of the growing season.  By examining the soil, one can determine if hydric indicators are present.

    Hydric soils:

    • usually contain predominantly decomposed plant material (peat or muck)
    • may have a bluish gray or gray color at 10 to 12 inches below the surface layer
    • usually have dark and dull (brownish black or black) soil as the major color
    • may have the odor of rotten eggs
    • may be sandy and have dark stains or streaks of organic material in the upper layer (3 to 12 inches below the surface)

  • Hydrology
    Wetland hydrology refers to the presence of water, either above the soil surface or within the soil, but near the surface (12 to 18 inches below the soil surface, depending on the soil type) for a sufficient period of the year to deprive the soils of oxygen and significantly influence the plant types that occur in the area.  Gauging station or ground water well data provides the most reliable evidence.  However, there are field indicators that provide evidence of the periodic presence of inundation or soil saturation.  These include:
    • standing or flowing water
    • waterlogged soil
    • water marks on trees
    • drift lines, which are piles of debris oriented in the direction of water movement
    • debris lodged in trees
    • thin layers of sediment deposited on leaves or other objects. These layers of sediment often become consolidated with small plant parts to form crusts on the soil surface
    • stained leaves
    • oxidized root channels

When should I check with the Corps to see if my project might impact a wetland?

You should ask the Corps office to determine whether an area is a wetland if it has any of the following conditions:

  • The area is flooded or ponded, and occurs in a floodplain or has low spots or is poorly drained such that water is present just below or collects above the soil surface for part of the growing season;
  • The area has plant communities that commonly occur in areas having standing water for part of the growing season;
  • The area has peat or mucky soils or is soft enough that it compresses under foot;
  • The area is periodically flooded by tides.
  • The area shows up as a wetland on either a State wetland map, a National Wetland Inventory Map, or as a hydric soil on a Soil Survey Map.

If you plan to perform work or deposit fill material in areas where you observe possible indicators of any of the characteristics of a wetland, you should seek assistance from either the local Corps District Office or an expert at making wetland determinations. The final determination of whether an area is a wetland and whether the activity requires a permit must be made by the appropriate Corps District Office.

Increasingly, potential applicants for Department of the Army permits are hiring environmental consultants to do wetlands determinations and delineations for them. In addition, because of Federal budgetary and work force constraints, we are requesting that many potential applicants have wetlands delineations done by consultants. Under existing constraints, the Corps of Engineers will field verify as many wetlands delineations as possible. We recommend that wetlands delineations performed by consultants be submitted for review and confirmation at least one month in advance of a submittal of a Department of the Army permit application.

All wetland delineations will be reviewed to insure compliance with the methodology contained in the Corps of Engineers Wetlands Delineation Manual dated January 1987 and that sufficient information is provided to justify the wetland/upland boundaries as shown on the delineation map(s). To obtain a jurisdictional determination letter, all consultant-prepared wetlands delineations should include the following:

  1. A delineation map depicting a point to point survey of the wetlands, and any other waters of the United States, boundaries as flagged by the consultant in the field.  The consultant should review the survey for accuracy before submittal to this office." We prefer topographic maps with contour intervals of one or two feet and at a scale of 1 inch equals 100 feet.  However, these specifications may vary depending upon the scope of the delineation and the nature of the project.  In certain situations, a point to point survey of the wetlands boundary may not be required.  However, the boundary must be reproducible in some manner.  The consultant should contact this office for approval before submitting a delineation without a point to point survey.  In all cases, the wetlands boundary must be marked with survey flagging or stakes in the field before this office will conduct a site inspection to verify the delineation.  The flags or stakes must be sequentially numbered and those numbers shall appear on the survey for each point.
  2. The respective sizes of wetlands in acres, and streams in width and length, should be included on the map.
  3. The location of all sample sites should be shown on the delineation map(s).
  4. Wetlands delineation data forms, or similar data sheets, for each sample site, cross- referenced to the sites should be shown on the delineation map(s). The data for each sample site shall clearly list the indicators or lack of indicators for soils, vegetation and hydrology, and shall include the basis for determining whether the sample site is wetland or upland. The number of sample sites will vary depending upon the size and shape of the wetlands, the degree of difficulty in differentiating wetland and upland, width of transition zones, etc. A wetlands delineation field data sheet is available from a Corps office or through the New York District Corps website at Wetland Determination Data Form for field use. 
  5. A site location map, preferably a 7.5-minute USGS quadrangle, any other pertinent maps of the site, and the latitude/longitude or UTM coordinates of the site should also be included.
  6. A brief written report should be included with the submittal.  This report should list the property owner(s) and/or the developer(s) requesting the delineation.  The report should also describe the nature of the proposed development, and when a permit application will be submitted for the project.  The report should list any intermittent or perennial streams located on the site, the type(s) of wetlands present, such as palustrine forested, riverine emergent, etc., the dates of the actual field work, and include representative color photographs of the site.

Wetlands delineations that are complete and accurate can be confirmed in writing by the Corps of Engineers.