***Article Update: Kent Werlin is the Senior Wetland Scientist with Biota Research and Consulting in Jackson, Wyoming. Kent was kind enough to edit my article and provide updated, more accurate information. My disclaimer stands (do your own research), and see the updated article below:
Wetlands are often confused with floodplains and flood zones. Flood zones are not always wetlands, and wetlands are not necessarily located in floodplains, though there are circumstances where either could be true. Flood zones can occur in areas next to large bodies of water or runoff areas and are often considered higher risk when it comes to flooding. However, any property can flood, not necessarily only properties in a floodplain.
Wetlands are regulated by the U.S. Army Corps of Engineers and Environmental Protection Agency under the Clean Water Act. To be considered a “wetland”, an area must meet all of the following criteria:
1) Wetland Hydrology: To have wetland hydrology, an area must be at least saturated in the upper 12 inches of the soil profile for a period of 14 days during the growing season in 5 out of every 10 years. Active monitoring of hydrology via the use of shallow groundwater monitoring wells and/or wetland hydrology indicators are utilized by wetland professionals to determine the presence of wetland hydrology. These indicators include the presence of surface water, saturation, geomorphic position, oxidized rhizospheres (root channels), a dominance of wetland vegetation, and others.
2) Wetland (Hydrophytic) Vegetation: roughly a quarter of the plant species in the United States grow in wetland areas. To be a wetland, an area must be dominated by facultative or wetter plant species based on the National Wetland Plant List, which designates plant species as upland, facultative upland, facultative, facultative wetland, or obligate wetland. These are described below:
- Upland – plant species that occur in non-wetland areas 99% of the time and do not indicate wetland conditions (e.g. sheep fescue, sagebrush, western wheatgrass)
- Facultative Upland – plant species that occur in upland environments 75% of the time and in wetlands 25% of the time (e.g., orchardgrass)
- Facultative – plant species that occur in wetland environments 50% of the time and in upland environments 50% of the time (e.g. Kentucky bluegrass, common timothy, and meadow foxtail)
- Facultative Wetland – plant species that occur wetland environments 75% of the time and in upland environments 25% of the time (e.g. Baltic Rush, reed canarygrass)
- Obligate Wetland – plant species that occur in wetlands 99% of the time. These species are generally indicative of wet areas. (e.g. beaked sedge, Booth’s willow, hardstem bullrush)
3) Wetland Soils: Wetland soils are often referred to as hydric soils. These soils can generally be analyzed by digging a 20-inch deep hole and looking for hydric soil indicators that indicate a high water table and/or periodic saturation within the upper horizons of the soil profile. These indicators include an abundance of organic soil matter, oxidized iron (rust colored) or manganese (purple) concentrations, and others.
Can you build in Wetland?
Wetland areas do require special permits and approvals. But first, they must be identified as wetland, usually by way of what is referred to as a wetland or aquatic resource delineation performed by a properly trained wetland consultant (such as the co-author of this article, Kent Werlin, the Senior Wetland Scientist with Biota Research and Consulting) and following the wetland delineation protocol approved by the Army Corps. Wetlands in Teton County are subject to both federal and local (county) regulations which differ in their requirements.
If a property in Teton County, Idaho shows indications of wetland presence based on the nationwide National Wetland Inventory (NWI) mapping (can be viewed via the Teton County GIS Mapserver), the county will generally require a delineation before approving subdivision or issuing grading or development permits for the subject property. Under current county regulations (Teton County Land Development Code 2022), the county requires either a 50′ or 100′ development setback on wetlands, depending on the level of analysis conducted. If a site-specific wetland delineation is conducted, the county will place a 50’ development setback on all wetlands delineated by a wetland professional and approved by the Army Corps. If there is no site-specific wetland delineation conducted, then the county falls back on the NWI mapping and requires a 100’ setback on NWI mapped wetlands.
At the federal level, the Army Corps requires a permit application for the placement of fill material (e.g., rock, gravel, concrete, soil, etc.) in jurisdictional wetlands. The Army Corps has a suite of streamlined Nationwide Permits for activities that impact up to 0.5 acres of wetland. If wetland impacts exceed 0.1 acres, then the Army Corps requires a Compensatory Wetland Mitigation Plan that involves the creation of new wetlands or enhancement of existing wetlands to compensate for development-related wetland losses.
A recent supreme court case (EPA v Sackett) decision has put the jurisdictional status of some wetlands at the federal level in question. The Army Corps is in the process of modifying their technical guidance for determining jurisdictional status based on the outcome of this court case and should be issuing guidance in the coming months. While it may be possible to impact wetland areas with the proper permits, it is important to remember the reason that these regulations exist….to protect wildlife, habitat, and waterways, often considered a key cornerstone of Teton Valley’s natural beauty.
END UPDATED ARTICLE – Special thanks to Kent Werlin, biotaresearch.com
Disclaimer: As always, I need to start out this article with a disclaimer. I know enough about many of these topics to be dangerous – which is dangerous. Always seek the advice of appropriate professionals as this information is subject to change as well as my own interpretation. I don’t often go back and update old articles, so I’ll leave this here.
Wetland should not be confused with floodplain. Flood zones are not always wetland, and wetlands are not necessarily in floodplains. Flood zones normally occur in areas next to bodies of water or runoff areas and are often considered higher risk when it comes to flooding. However, any property can flood, not necessarily only properties in a floodplain or a wetland.
How to Identify Wetland
Wetland can occur even in areas not directly adjacent to a body of water and is usually determined by three primary factors:
1) Hydrology: Hydrology indicators can include the presence of surface water or wet soils as determined by evidence or review by a wetland professional utilizing different tools or testing to understand the presence of water.
2) Vegetation: Roughly a quarter of the plant vegetation species in the United States grow in wetland areas. Plant species can be classified in a number of different ways as identified below in order of wet to dry:
- Obligate Wetland (usually very indicative of wetland areas) ie Sedges (which have triangular, sharp stems) and Willow
- Facultative Wetland (usually occur in wetlands, but occasionally found in non-wetlands) ie Horsetail, Baltic Rush
- Facultative (equally likely to occur in wetlands or non-wetlands) Meadow Foxtail, Timothy, Brome, Bluegrass
- Facultative Upland (usually occur in non-wetlands, but occasionally found in wetlands) ie Potentilla
- Obligate Upland (almost always occur only in non-wetlands) ie Sheep Fescue
3) Soils: Wetland soils are often referred to as hydric soils. These soils can be analyzed by digging a hole (usually 12-18 in deep) and looking at indications of saturated soils that usually show indications of oxygen depletion. This can be evidenced (essentially) by rust in the soils and the coming and going of water, creating oxidation. Oxidation can be due to iron and is usually identified by orange flecks in the soil or manganese which will reveal itself with a purple color.
Can you build in Wetland?
Wetland areas do require special permits and approvals. But first, they must be identified as wetland, usually by way of what is referred to as a Wetland Delineation performed by a properly trained wetland Consultant.
If a particular property shows indications of wetland, Teton County, Idaho will generally require a Wetland Delineation. They have requirements of 50′ or 100′ setbacks, depending on the delineation findings. If the project looks like it will encroach within 50′ of wetlands as indicated by the Delineation, the county may require a Jurisdictional Determination (JD) from the Army Corps of Engineers. If there are any questions on a project, despite setbacks, the Teton County Planning Staff may still send the information to the Corps for review. A JD is the process of Determining whether areas indicated as wetland are regulated by the U.S. Army Corps of Engineers under section 404 of the Clean Water Act and/or Section 10 of the Rivers and Harbors Act.
If a property is determined to be wetland, with the proper permits it may be possible to impact up to 0.1 acre of wetland for driveway, septic, and a home site. If wetland is mitigated to another area, these improvement areas can be increased to 0.5 acres.
Wetland areas can make tremendous home sites, but it is important to remember the reason that these regulations exist in order to protect wildlife, habitat and waterways, often considered a key cornerstone of Teton Valley’s natural beauty.
- 1998 Edition of the US Army Corps of Engineers “Recognizing Wetlands” document
- Teton County, Idaho Planning & Zoning
- Teton County, Idaho Land Development Code (current)