How to Identify a Wetland (and why it matters)

Wetland environment

Wetlands provide habitats and ecological services for countless species in a variety of ways. Macroinvertebrates (dragonflies, stoneflies, and other water-dwelling insects) spend much of their early lives under water. Dozens of rare plant species in Tennessee require wetland habitats for survival. Migratory birds also depend on wetlands to feed, nest, and mate. And while wetlands make great homes for wildlife, they also clean our water. Known as the "kidneys of the landscape," wetlands trap and filter chemicals, clean polluted waters, and ameliorate both floods and drought (Mitsch and Gosselink, 2007).

But if you are at all versed in scientific literature, you are well aware that we are losing our wetlands. Prior to the mid-1970's, wetland drainage was accepted and often encouraged by government programs. In Tennessee alone, approximately 59 percent of our wetlands have been lost since the early 1990's to filling, draining, and habitat conversion (ASWM, 2017; Mitsch and Gosselink, 2007). Other states such as California and Ohio report as much as a 90 percent loss of wetlands.


To protect these resources, we must first be able to identify them. So what is a wetland? We delineate, or draw boundaries around wetlands using a few pieces of equipment and reference materials that help us understand the landscape. Wetlands are delineated by observing the presence or absence of three variables: hydrology, dominant plant species, and hydric soils (USACE, 1987). All three indicators must be present during the growing season for a waterbody to be considered a wetland. If all three characteristics are observed, it means that the area is likely inundated or saturated by water at a frequency that supports wetland conditions (USACE, 1987). These indicators are noted on a data sheet

Some indicators are more difficult to identify than others. While hydrology indicators are relatively easy to spot, wetland plant species can be difficult to identify, but the difference between two species can mean very different things. For example, Carex cephalophora, oval-leaf sedge, is common in Tennessee. It is known from most counties in the state in open mesic woods. Because oval-leaf sedge does not need an aquatic habitat to survive, it is known as a facultative upland species.

 Plant distributions referenced from Kartesz, 2017.

Plant distributions referenced from Kartesz, 2017.

It's sister, Carex gravida, or heavy sedge, is of special concern (relatively rare) in Tennessee. It is known from just over ten of the 95 counties in the state, but looks similar in appearance to oval-leaf sedge. While the two appear similar, heavy sedge depends on wetlands to survive. It is known as a facultative wetland species. We must be able to make this distinction in the field to delineate wetlands accurately and take proper care during alteration or impact.

 Plant distributions referenced from Kartesz, 2017.

Plant distributions referenced from Kartesz, 2017.

Similarly, wetland soils take a bit of classification practice. A soil probe is used to extract soil from both a wetland and non-wetland point. This allows us to see where the wetland begins (where the soils are hydric) and ends (where they are no longer hydric). Once a soil core is extracted, we mark the soil layers by color and texture. A reference book known as the Munsell soil color book is used to identify the color of each layer. A hue and chroma is noted and later compared to known soil layers

 Depleted matrix hydric soil indicator (USDA-NRCS, 2016).

Depleted matrix hydric soil indicator (USDA-NRCS, 2016).

Another important note about wetlands is that they vary regionally. Each major region of the US has adopted what is known as a "Regional Supplement." Eastern Tennessee falls within the Eastern Mountain and Piedmont region from west central Tennessee east, and the Atlantic and Gulf Coastal Plain region from west central Tennessee to the west (depicted here). Different data sheets (and therefore different wetland indicators) are used according to these regions.


As with any natural resource, our communities must decide what to protect as we grow. Wetlands are protected under the Clean Water Act (CWA), originally known as the Federal Water Pollution Control Act (USEPA, 1972). Until February 2017, federal regulation was also extended to the USACE under the Waters of the United States (WoUS) Rule, enacted by the Obama administration in 2015. The Trump administration recently rescinded this rule, seeking to redefine WoUS, and to return federal regulation of these waters to each state.

While federal regulation is no longer certain, impacts to wetlands are regulated by our state's Tennessee Department of Environment and Conservation (TDEC) to curb any reductions in water quality. That means that prior to any impact, fill, or other alteration, permittees are required to disclose disturbance and mitigation plans. In other words, they must explain why they could not avoid the wetland resource and further detail how impact will be minimized. Alteration permits vary depending on the size of the wetland and the ecological functions it supports.


Compensatory mitigation (wetland enhancement and restoration) is mandatory for projects resulting in larger wetland impacts as part of a larger rule known as "No Net Loss." Depending on the type and size of the wetland impact, mitigation requirements will vary.

 An impacted wetland due to cattle pugging (left; Hughes et al., 2014) will be held to different mitigation standards than a forested wetland (right; the leaves of skunk cabbage sprout soon after the inflorescence blooms), but both would be considered a wetland.

An impacted wetland due to cattle pugging (left; Hughes et al., 2014) will be held to different mitigation standards than a forested wetland (right; the leaves of skunk cabbage sprout soon after the inflorescence blooms), but both would be considered a wetland.

Three methods of wetland mitigation in order of preference by the USACE include banking, in-lieu fee, and permittee-responsible. A wetland bank describes a site where wetland resources are built, enhanced, or conserved to provide compensatory wetland mitigation credits to a permittee (developer). The responsibility of building a wetland habitat is therefore passed to another entity, making the mitigation process relatively quick and almost always successful. An in-lieu fee program is similar to wetland banking, but the wetland credits are bought and sold through another governing entity, like a city or county.

Permittee-responsible wetland mitigation requires the impacting party and/or consultant to oversee the creation or enhancement of a wetland. This process is typically less expensive than banking. Complex planning, knowledge about local soils and plant species, and a long-term monitoring plan (often in excess of ten years) can create a lengthy mitigation process. Research suggests that on-site mitigation in the form of creation, restoration, enhancement, and preservation is largely unsuccessful, resulting in poorly functioning wetlands, unmet permit conditions, and uncompleted projects (ASWM, 2017; Morgan and Roberts, 2002; Turner et al., 2001). Poor design, improper hydrology, and poor plant survival rates reduce the effectiveness of wetland mitigation.

Each wetland is different, existing under a unique set of environmental conditions, therefore all methods should be considered before mitigation is conducted.


Clean Water

Wetlands filter wastes, harmful chemicals, and sediment from our waters and atmosphere. They are crucial for countless ecosystem services including flood storage and groundwater recharge. Wetlands cover just three percent of the worlds land but store approximately 30 percent of our carbon (Mitsch and Gosselink, 2007). As we continue to lose wetland habitats, our waters require additional chemical treatment as surrounding streams, lakes, and rivers suffer from wildlife loss, flood damage, and pollution.


To better serve our environment as we develop our communities, Circadian created a unique approach to the wetland permitting process. Our team has over ten years of experience planning, delineating, and permitting wetland impacts responsibly. We believe that the development of our community and environmental health are possible in every project. Whether you are a homeowner,  business, or  interested citizen with a wetland on your property, we are here to help you through the environmental process. Contact us anytime. 

Wetland habitat

Literature Reviewed

Hughes, A., L. McKergow, C. Tanner, and J. Sukias. 2014. Influence of livestock grazing on wetland attenuation of diffuse pollutants in agricultural catchments. National Institude of Water and Atmospheric Research. Accessed June 2017. Available online at: file:///E:/Downloads/Hughes_et_al_2013_FLRC_paper.pdf.

Kartesz, J.T., The Biota of North America Program (BONAP). 2015. Taxonomic Data Center. ( Chapel Hill, N.C. [maps generated from Kartesz, J.T. 2015. Floristic Synthesis of North America, Version 1.0. Biota of North America Program (BONAP). (in press)].

Mitsch, W. J., and J. G. Gosselink. Wetlands. Hoboken: John Wiley & Sons, 2007. 582 pp. In print.

Morgan, K. L. and T. H. Roberts. 2002. Characterization of wetland mitigation projects in Tennessee, USA. The Society of Wetland Scientists. Wetlands 23(1): 65-69. Accessed June 2017.

Turner, R. E., A. M. Redmond, and J. B. Zedler. 2001. Count it by acre or function - Mitigation adds up to net loss of wetlands. National Wetlands Newsletter 23:6. Accessed June 2017. 

USACE. 1987. Corps of Engineers Wetlands Delineation Manual. US Army Engineer Waterways Experiment Station. Vicksburg, MS. Technical Report Y-87-1.207. Accessed June 2017. 

USDA-NRCS. 2016. Field Indicators of Hydric Soils in the United States, Version 8.0. L.M. Vasilas, G.W. Hurt, and J.F. Berkowitz (eds.). USDA, N.

USEPA. 1972. Federal Water Pollution Control Act. Available online at: Accessed July 2017.

*Photo credits to Gary P. Fleming and Peter M. Dziuk.