Blue Jay | Emma Dickinson
The Definition of Wetlands
By Jay Schofield
Introduction
Over the past two centuries, the United States’ definition of “wetlands” has changed dramatically, reflecting the country’s evolution in scientific understanding, legal priorities, and societal values. Originally seen as unimportant land to be drained or covered, wetlands are now recognized as vital ecosystems. As research and public education increase, society begins to understand the purpose of wetlands in supporting biodiversity, managing floodwaters, storing carbon, and so much more. This changing view has led to an evolution of definitions—scientific, legal, and regulatory—that differ across institutions and time periods. Understanding how these definitions have developed is essential for interpreting how wetlands are managed, protected, and contested in American policy and law.
My research follows the historical progression of wetland definitions in the United States, beginning with simple, early legislative mentions in the 19th century, and moving through technical and ecological frameworks in the 20th century. It explores not only the shifting scientific criteria that define a wetland, but also the competing interests (environmental, economic, and legal) that shape said definitions. Ultimately, this analysis shows there is no single, universally accepted definition of a wetland, reflecting the complex role wetlands play in American society and governance.
Definitions
Shaped by developments in science, shifts in land use priorities, and growing environmental awareness, the definition of a “wetland” in the U.S. has evolved significantly over the past century. As wetlands have become more central to ecological research, policy, and regulation, a more precise and functional understanding of what constitutes a wetland has emerged.
The Swamps and Lowlands Act of 1849 is one of the oldest acts mentioning the idea of wetlands and their categorization. This act gave the state of Louisiana the authority to drain wetlands for human use, such as farming and construction. The act goes as follows: “Be it enacted by the Senate and House of Representatives of the United States of America in Congress assembled, that to aid the state of Louisiana in constructing the necessary levees and drains to reclaim the swamp and overflowed lands therein…” (Swamps and Lowlands Act, 1849). While this act does not give a clear definition of wetlands, it represents the start of wetlands being recognized by the government and being mentioned in legal documents. Similarly, the Rivers and Harbours Act of 1899—while not specific to American wetlands—can be viewed as a steppingstone for future documents protecting and defining wetlands. The act states; “It shall not be lawful to construct or commence the construction of any bridge, causeway, dam, or dike over or in any port, roadstead, haven, harbor, canal, navigable river, or other navigable water of the United States until the consent of Congress to the building of such structures shall have been obtained…” (River and Harbors Act, 1899). The purpose of this act was to keep waterways open for transportation without private citizens or companies blocking the waterways without approval from the government. However, the River and Harbors Act created a baseline for official waterway protection within the government, which supported future legal documents in their protection and definition of American wetlands.
The first clear definition specific to wetlands was written in 1953 by the U.S. Fish and Wildlife Service, referring to wetlands as “lowlands covered with shallow and sometimes temporary or intermittent waters” (Martin et al., 1953). The Fish and Wildlife Service created this definition in 1953 to improve the conservation and management of migratory waterfowl by creating a foundation to improve their wetlands inventory. By creating a framework for the definition of a wetland, the Fish and Wildlife Service was able to begin categorizing and protecting American wetlands. This, in turn, preserved the populations of waterfowl that migrate through the United States. Their definition excluded any permanent waters such as streams, lakes, rivers, and so forth, which would be seen under separate definitions and regulations. Additionally, the organization’s definition of wetlands excluded any wet areas viewed as too temporary or insignificant to have a significant impact on wildlife. With their focus being on waterfowl and sport (such as hunting and fishing), these areas were not considered to be of any value or worth protecting and categorizing (Martin et al., 1953).
By 1979, the U.S. Fish and Wildlife Service saw the need to update their current definition of wetlands. The 1953 definition of wetlands was vague and made it difficult to decide whether an area qualified under their definition as a wetland. Therefore, the U.S. Fish and Wildlife Service wrote a new definition for wetlands: “Wetlands are lands transitional between terrestrial and aquatic systems where the water table is usually at or near the surface or the land is covered by shallow water. For the purposes of this classification, wetlands must have one or more of the following three attributes: (1) at least periodically, the land supports predominantly hydrophytes; (2) the substrate is predominantly undrained hydric soil; and (3) the substrate is nonsoil and is saturated with water or covered by shallow water at some time during the growing season of each year.” (Cowardin et al., 1979).
The new definition created clearer guidelines for what a wetland is and better standardized the identification procedures for said wetlands. The addition of technical and ecological terminology rooted the definition in scientific knowledge, which made it much easier to use in field studies and data collection. The 1979 U.S. Fish and Wildlife Service definition was essential in making the National Wetlands Inventory Project (NWI) more accurate and consistent with a stronger base in ecology. This new definition acknowledges the variation in hydrology within wetland environments, and expands the focus of wetland categorization and conservation beyond just large wildlife and waterfowl (Tiner, 1999). The 1979 definition also introduces the three big requirements for wetland identification: the presence of hydrophytes, hydric soils, and the saturation of nonsoil substrate during the growing season. These three requirements become a baseline for all future wetland definitions and become a central point in wetland identification.
In 1987, the U.S. Army Corps of Engineers came up with their own definition of wetlands in conjunction with the Environmental Protection Agency (EPA). Within their Corps of Engineers Wetlands Delineation Manual, the U.S. Army Corps of Engineers reads; “The CE (Federal Register 1982) and the EPA (Federal Register 1980) jointly define wetlands 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 generally include swamps, marshes, bogs, and similar areas” (U.S. Army Engineer Waterways Experiment Station et al., 1987). This 143-page manual goes into depth on not just the definition of a wetland, but the science and chemistry of wetlands as well, working to simultaneously provide a concise guide on how to identify a wetland and its various components. While there is no direct listing of the three main qualifications of a wetland (the presence of hydrophytes, hydric soils, and the saturation of nonsoil substrate during the growing season), the manual itself goes into extensive detail on each of the qualities listed in various sections within the manual (U.S. Army Engineer Waterways Experiment Station et al., 1987).
From here on, there isn’t much in the way of significant change to the general agreed-upon definition of wetlands as most definitions stick to the general three requirements of wetlands and previously outlined regulations as to what constitutes a wetland. For example, in 1995, the National Research Council (NRC) published Wetlands: Characteristics and Boundaries, which keeps a similar outline to the definition given by the U.S. Fish and Wildlife Service in 1979, and includes scientific components outlined within the Corps of Engineers Wetlands Delineation Manual. While some changes are made to emphasize and clarify certain parts of the definition, the overall core definition of wetlands remains relatively constant (National Research Council, 1995).
Implications
The definition of a wetland has gone through substantial changes and growth throughout history, and while the definition has become more specific and universal in recent years, there is still variation within different organizations and legal documents as to what the true definition of a wetland is. The Economic Research Service has stated “There is not a single definition of wetland that all agencies, scientists, policymakers, or landowners use for all purposes” (Ralph E. Heimlic et al., 1998). Part of the change in the definition of a wetland is due to an increase in scientific knowledge over time. With increased study of wetlands, scientists can more easily identify what constitutes a wetland and what does not, leading to more specific and scientific knowledge being added to newer definitions over time. Beyond scientific knowledge, the variation in wetland definitions can be attributed to a change in the reasoning behind the definitions. As the government and other organizations see the importance of wetlands both environmentally and for human convenience, the definition of a wetland becomes more specific, preventing people from finding loopholes in their documents and increasing the protection and regulations on American wetlands. Similarly, the increased appreciation for wetlands increases the amount of research and categorization needed for wetlands in America. This requires clearer guidelines as to what does and doesn’t constitute a wetland while making it easier for scientists to categorize and collect data on American wetlands.
Another cause of variation in wetland definitions stems from the individual needs of each organization and acts passed by congress. A written definition will reflect the purpose of the document it can be found in. A document focusing on the environmental protection of wetlands will have a different definition than a document focusing on the drainage of wetlands for agricultural use. No matter how much research is put into wetlands and their conservation and regulations, there will never be just one universal definition for what a wetland is. Newer documents may pull from previous documents when it comes to the base of their definition, but each new definition will have some variability in how they describe and categorize wetlands.
As there is increased understanding of wetlands and new documents that need to be released, the definition will continue to grow and will often see positive changes with more specific outlines and easier use for scientists and contractors alike. The ever-evolving definitions of wetlands is a positive attribute to the U.S. and to our society. The variation in definitions emphasizes the complexity of wetlands and how our society handles them. Hopefully we will continue to work to further understand and define wetlands in America.
References
U.S. Congress. (1849). Swamp and Overflowed Lands Act of 1849 (ch. 84, 9 Stat. 519). Government Printing Office.
River and Harbors Act of 1899: U.S. Statutes at Large, 30 Stat. 1121, Sections 9–20.
Martin, A.C., Hotchkiss, Neil, Uhler, F.M., and Bourn, W.S., 1953,
Classification of wetlands of the United States: Washington D.C., U.S. Fish and Wildlife Service Special Scientific Report, Wildlife, no. 20, 14 p.
Cowardin, L.M., Carter, Virginia, Golet, F.C., and LaRoe, E.T., 1979,
Classification of wetlands and deepwater habitats of the United States: U.S. Fish and Wildlife Service Report FWS/OBS-79/31, 131 p.
U.S. Army Engineer Waterways Experiment Station, et al. Corps of Engineers Wetlands Delineation Manual. Appendix C. Vicksburg, Miss., U.S. Army Engineer Waterways Experiment Station, 1987.
National Research Council (1995) Wetlands: Characteristics and Boundaries National Academies Press
Ralph E. Heimlich, Keith D. Wiebe, Roger Claassen, Dwight Gadsby, and Robert M. House (1998) Wetlands and Agriculture: Private Interests and Public Benefits United States Department of Agriculture and Economic Research Service
Jay Schofield is a senior at Susquehanna University studying Environmental Science and Ecology. They currently work at the CEER as an Environmental Education and Outreach Intern and have worked under the Middle Susquehanna Riverkeeper as well as the Chesapeake Conservancy. They are currently working on a thesis on campus tree health and urban tree planning. Jay’s favorite part of studying the natural sciences is getting to spend lab time outside and going on field trips to local forests and wetlands. They hope to one day work as a restoration specialist or environmental educator for a non-profit organization.