Wetland Identification and Delineation
Wetland determination (sometimes called identification) is simply the determination of whether an area is a wetland or not. Wetland delineation is the actual determination and establishment of wetland boundaries.
Delineations are based on the definition of wetland in the Clean Water Act.
Delineations are based on the definition of wetland in the Clean Water Act.
From the definition, there are three criteria to delineate wetlands: wetland hydrology, hydric soils, and hydrophytic vegetation.
Hydrology
Wetland hydrology refers to the specific hydrologic conditions that are required to form and maintain wetlands. Saturation at or near the surface, or inundation, for approximately 14 consecutive days or more during Michigan’s growing season typically creates the necessary conditions in the soil to form and maintain wetlands. Wetland hydrology, hydric soils, and hydrophytic vegetation are all linked. Hydrophytic vegetation and hydric soils result from wetland hydrology; and conversely, the presence of hydrophytic vegetation and hydric soils indicate wetland hydrology.
Of the indicators used for wetland identification, wetland hydrology is the most variable and often the most difficult to observe directly. Numerous factors influence hydrology, including precipitation, topography, soil permeability, and plant cover. The technical wetland hydrology criteria looks at the distance to the water table based on soil drainage and permeability characteristics.
Common Field Indicators of Wetland Hydrology
Hydric soils have physical and chemical indicators of repeated and prolonged saturation at or near the soil surface. These indicators are a direct result of the lack of oxygen in the upper part of the soil caused by the presence of water in the spaces between soil particles (which forces air out of the soil). In Michigan and most of the temperate regions of the United States, hydric soils are flooded, ponded, or saturated for about 14 consecutive days during the growing season.
Common Field Indicators of Hydric Soils
Hydrology
Wetland hydrology refers to the specific hydrologic conditions that are required to form and maintain wetlands. Saturation at or near the surface, or inundation, for approximately 14 consecutive days or more during Michigan’s growing season typically creates the necessary conditions in the soil to form and maintain wetlands. Wetland hydrology, hydric soils, and hydrophytic vegetation are all linked. Hydrophytic vegetation and hydric soils result from wetland hydrology; and conversely, the presence of hydrophytic vegetation and hydric soils indicate wetland hydrology.
Of the indicators used for wetland identification, wetland hydrology is the most variable and often the most difficult to observe directly. Numerous factors influence hydrology, including precipitation, topography, soil permeability, and plant cover. The technical wetland hydrology criteria looks at the distance to the water table based on soil drainage and permeability characteristics.
Common Field Indicators of Wetland Hydrology
- Drift lines – drift lines consist of debris (remnants of vegetation, sediment, litter, etc.) that was deposited as a result of water movement
- Water marks – stains on bark or other fixed objects such as bridges or pilings; thin layers, coatings, or depositions of mineral or organic matter on plants
- Oxidized root channels – iron oxide concentrations, orange or red-brown color, along the length of a root channel
- Water-stained leaves – generally grayish or blackish leaves on the forest floor
- Surface scoured areas – surface is scoured along floodplains where overbank flooding erodes sediments
Hydric soils have physical and chemical indicators of repeated and prolonged saturation at or near the soil surface. These indicators are a direct result of the lack of oxygen in the upper part of the soil caused by the presence of water in the spaces between soil particles (which forces air out of the soil). In Michigan and most of the temperate regions of the United States, hydric soils are flooded, ponded, or saturated for about 14 consecutive days during the growing season.
Common Field Indicators of Hydric Soils
- Organic soils – also known as histols, these are thick peats and mucks
- Organic surface layer – organic layer that forms above the mineral substrate
- Sulfidic material – soils that emit an odor of rotten eggs
- Iron or Manganese concentrations – accumulations of black or dark brown masses
- Soil color - gleyed (bluish, greenish, or greyish) or low chroma (dull)/mottled soils (bright splotches of color in a dull matrix)
- Dark vertical streaking – cross-sectional view of the soil in a soil pit will appear to be vertically streaked
Hydrophytic Vegetation
Hydrophytic (water-loving) vegetation is plant life that is adapted to grow in areas where the frequency and duration of inundation or saturation is sufficient to exert a controlling influence over the plant species present. Among other things, all plants need oxygen and water. There is a point at which the frequency and duration of water in the soil causes at least periodic deficiencies in oxygen in the root zone. This is because water replaces air in the spaces between the soil particles in saturated conditions. In order to survive the stress of low oxygen levels in the root zone, hydrophytic plants have structural and functional adaptations to allow them to thrive in these areas.
The U.S. Fish and Wildlife Service, in cooperation with other agencies and professional botanists, developed the following categories to help determine if a vegetation community would be considered to be adapted to wetland conditions:
Obligate Wetland Plants (OBL) — Species in this category are estimated to occur in wetlands more than 99 percent of the time.
Facultative Wetland Plants (FACW) — Species in this category are estimated to occur in wetlands approximately 99-67 percent of the time.
Facultative Plants (FAC) — Species in this category are estimated to occur in wetlands approximately 66-34 percent of the time.
Facultative Upland Plants (FACU) — Species in this category are estimated to occur in wetlands approximately 33-1 percent of the time.
Obligate Upland Plants (UPL) — Species in this category are estimated to occur in wetlands less than 1 percent of the time.
Obligate Upland Plants (UPL) — Species in this category are estimated to occur in wetlands less than 1 percent of the time.
Wetland Identification Program
The Michigan Department of Environment, Great Lakes, and Energy (EGLE) has a Wetland Identification Program (WIP) to assist the public in identifying wetland and non-wetland (i.e., upland) areas on their property. The WIP offers levels of service to assist the public.
Level 1: Wetland Inventory Maps
EGLE wetland inventory maps are now available for each county are available in electronic form, or can be requested in paper form at cost, on the ELGE website under Wetland Inventory Maps. Since these maps are not based upon an on-site review, the EGLE does not provide a jurisdictional guarantee or a map specific to the parcel.
The Michigan Department of Environment, Great Lakes, and Energy (EGLE) has a Wetland Identification Program (WIP) to assist the public in identifying wetland and non-wetland (i.e., upland) areas on their property. The WIP offers levels of service to assist the public.
Level 1: Wetland Inventory Maps
EGLE wetland inventory maps are now available for each county are available in electronic form, or can be requested in paper form at cost, on the ELGE website under Wetland Inventory Maps. Since these maps are not based upon an on-site review, the EGLE does not provide a jurisdictional guarantee or a map specific to the parcel.
Level 2: On-Site Determination
This service offers an on-site review of an identified area, up to five acres in size, by EGLE staff. The ELGE staff will identify, with flagging, areas that contain wetland and determine whether the wetland is regulated under Part 303. The purpose of this type of review is to identify areas where permits are not required.
Level 3: On-Site Wetland Boundary Confirmation
This service offers an on-site review of an identified area by EGLE staff to verify a wetland delineation (i.e, identification of a specific wetland boundary) completed by a wetland professional and/or consultant. The EGLE staff will verify flagged wetland boundaries placed by the applicant's wetland consultant and whether the wetland is regulated under Part 303.
Click here for more information on the Wetland Identification Program.
This service offers an on-site review of an identified area, up to five acres in size, by EGLE staff. The ELGE staff will identify, with flagging, areas that contain wetland and determine whether the wetland is regulated under Part 303. The purpose of this type of review is to identify areas where permits are not required.
Level 3: On-Site Wetland Boundary Confirmation
This service offers an on-site review of an identified area by EGLE staff to verify a wetland delineation (i.e, identification of a specific wetland boundary) completed by a wetland professional and/or consultant. The EGLE staff will verify flagged wetland boundaries placed by the applicant's wetland consultant and whether the wetland is regulated under Part 303.
Click here for more information on the Wetland Identification Program.
