For most people, the words swamp, marsh, bog or wetland mean a peaceful pond with cattails, water lilies, waterfowl and frogs. But contrary to popular belief, wetlands are not always wet.
Some wetlands are farmed, mowed for hay or maintained as a lawn. The Clean Water Act, all wetlands, according to the U.S. Army Corps of Engineers (COE) share these characteristics:
Wetlands are essential and provide several ecological, economic and social benefits, which is why policies are in place when developing in or around wetland areas. Wetlands provide habitat for fish, wildlife and plants; recharge groundwater and reduce flooding; provide clean drinking water; offer food and fiber; and support cultural and recreational activities. And because of this, wetlands are protected by federal, state and/or local regulations.
If you are planning a development project, building a new road or have an agricultural field that needs draining where a wetland may be disrupted or impacted, a delineation is your first step. A delineation tells you precisely the wetland location within your project plan. To obtain a permit for impacting a wetland, the delineated wetland boundary must be approved by the COE and often other local agencies that may have regulatory authority.
The best time to conduct a wetland delineation is during the “growing season,” the part of the year when soil temperature (measured 20 inches below the surface) is above biological zero (5°C or 41°F). A bud break on woody vegetation and visible “green-up” denoting active vegetation growth is also a proxy for the start of the growing season. Plants dying or entering dormancy mark the end of the growing season. The growing season varies considerably both year to year and geographically.
A wetland delineation should result in three findings:
Whether it is a small or large wetland delineation project, a delineator should prepare by researching the project area. This involves using mapping products such as aerial photographs and soil maps to identify potential aquatic resources. Some essential resources available:
If you are working on a smaller project, merely having a map is all you need. But if you are working on a larger project, you may be on a team, so it’s best to determine in advance who will cover what areas.
I always try to import project limits in the Global Positioning System (GPS) unit so I always know where I am on the site in respect to the proposed project. I don’t want to delineate too much or too little.
So, you’re ready to head out on a wetland delineation. But before you go, do you have the essential field gear? Here’s a check-list of the essential wetland delineation field gear recommended to help do your job, or make it easier:
Additional field gear to pack and prepare for your wetland delineation include:
Now that you’re prepared with the recommended essential wetland delineation gear and a plan, you’re ready to venture to the project site and begin the wetland delineation.
When you arrive at the project site, where do you begin? Is there an exact “start line” and “finish line”?
“Generally, you can start anywhere,” says Beduhn. “I look at the vegetation around me, review the locations from my resource mapping and begin the delineation with a sample point.”
These are the field procedures to follow in both upland and wetland areas:
1. Look at the vegetation around you. What types of vegetation do you see? It’s not uncommon to find vegetation in both upland and wetland areas. Rebecca will sometimes touch the vegetation to determine what the plant is. For example, Bedhun could feel edges on one plant picked during a delineation, and as a result, could identify the plant. “It helps to remember ‘sedges have edges’,” said Beduhn. “Many sedges are found in wetlands, but not all of them. It’s important to identify the type of sedge to determine the hydric indicator status of that species.” Other interesting vegetation found in this particular delineation is “sticky Willy.” Botanists won’t call it sticky Willy — they use the scientific names. Rebecca says some of the descriptive, common names can be helpful to remember a particular plant species. Other vegetation includes milkweed and reed canary grass – both of which can be found in uplands and wetlands. When you locate an area where the dominant vegetation is hydrophytic (grows in wetlands the majority of the time), you are on the right track to finding your wetland boundary.
2. Locate the topographic (topo) break. While not an accurate indicator, wetland boundaries are often associated with changes in topography, where the wetland is predominantly lower in the landscape.
3. Complete a soil sample.
Additional conditions to note during a wetland delineation is the temperature (higher or lower than normal) and precipitation (wetter or drier than normal).
Watch Beduhn in this video as she goes through the step-by-step of a soil sample.
Content of a wetland delineation report consists of:
After the draft report is prepared, the project owner then engages a wetland regulatory agency to review and confirm the results.
“We are all humans and vary in our approaches and analysis,” says Rebecca. “If the conditions change or something wasn’t identified accurately in the initial delineation, we fix it.”
In Minnesota, an approved wetland delineation is valid for five years, so long as conditions have not changed the boundary of that wetland during the five years since the initial approval.
Scientists classify dozens of wetland types, characterized by vegetation, soil type condition and degree of saturation or water cover. Agencies may require one or more of these types for all wetland delineations. In Minnesota, wetlands are classified three ways:
Wetlands are essential landscapes that provide ecological, economic and social benefits to the human and natural environment. This lends to strict policies for working in or near wetlands. Before you start your next project, following the steps and procedures for a proper wetland delineation is a basic and primary tenet to keep your project moving forward.
Rebecca Beduhn is a nationally-certified professional wetland scientist, Minnesota professional soil scientist-in training, and a Minnesota certified wetland delineator specializing in hydric soils. She is committed to preserving our environment and spends her days conducting wetland assessments and delineations, preparing regulatory permitting documents and mitigation site monitoring. Contact Rebecca