What Is Wetland Delineation?

Wetland delineation is a critical environmental assessment process that identifies and maps wetland boundaries based on soil, vegetation, and hydrology. This precise science informs land use decisions, ensuring ecosystems are protected while balancing development needs. Intrigued by how this impacts your community and the environment? Discover the intricate balance wetland delineation maintains in our next section.
B. Turner
B. Turner

The term wetlands refers to bogs, marshes, and peat lands, as well as many other areas with water-bearing soil. These wetlands represent unique ecosystems that are capable of supporting plants and animals that can't survive anywhere else on earth. Unfortunately, modern development and progress poses a significant threat to wetlands worldwide, which has led many countries to take steps to protect these lands. Conservation and protection often begins with wetland delineation, which is the process of establishing formal or legal boundaries around these delicate ecosystems.

The wetland delineation process can vary dramatically based on the requirements in each country or region. Typically, delineation involves taking soil samples of the wetland itself as well as in the soil on the outskirts of the area. Crews also map the wetland, and note the presence of plant, animal, and aquatic species. Most regions define a wetland as an area with hydric soil capable of supporting wetland species and plant life. Typically, the boundary of a wetland can be defined as the point at which these features are no longer present.

A wetland.
A wetland.

After wetland delineation is complete, crews place physical markers in the field to show developers and contractors where the protected area begins. They may also create topographic or aerial maps to illustrate these boundaries. Most regions require local inspectors or agents to approve these maps and boundaries before any type of work can begin.

Wetland delineation is a very difficult process, largely because very few people can agree on exactly what a wetland is. It can be further complicated by differing definitions and requirements at the local, state, and federal level within a region. For example, the United States (US) Army Corps of Engineers provides federal standards for wetland delineation, and these standards are constantly changing. Individual US states and cities have their own definitions and standards, many of which differ significantly from the federal definitions.

Wetlands typically refer to areas with water bearing soil.
Wetlands typically refer to areas with water bearing soil.

Due to the complexity of this process, wetland delineation is often carried out by highly trained professionals. Some undergo training from federal or state environmental agencies, while others hold degrees in environmental science or related fields. Even in areas where specific training is not required, individuals may find that training and experience are critical to navigating the wetland delineation process. Developers should be prepared to spend a great deal of time and money preparing to establish boundaries and obtain permission before starting a project near a potential wetland.

While wetland delineation requires a tremendous investment in time, money, and effort, it also provides immeasurable benefits to society. If wetlands were disturbed, plant and animal species may not survive. Wetlands also help to reduce flooding within an area, and act as a filter for stormwater runoff to help reduce air and water pollution levels. Finally, many wetlands act as carbon sinks, helping to trap carbon gases so they can't escape into the atmosphere. Each time a wetland is disturbed, large volumes of carbon can be released in the form of greenhouse gas emissions, which contribute to global warming.

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Discussion Comments


Wetland Delineations are a necessary part of almost any surface impact project, thanks to the Clean Water Act. Trained biologists are needed to conduct the delineation, and there are conventional rules set forth by the US Army of Engineers to follow.

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    • A wetland.
      By: Elenathewise
      A wetland.
    • Wetlands typically refer to areas with water bearing soil.
      By: cantelow
      Wetlands typically refer to areas with water bearing soil.