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A wetland is a unique ecosystem that is permanently or seasonally saturated by water, including swamps, marshes, bogs, vernal pools, and similar areas. They provide water quality improvement, flood protection, shoreline erosion control, food for humans and animals, and critical habitat for thousands of species of aquatic and terrestrial plants, aquatic organisms, and wildlife.
Princeton Hydro is regionally recognized for its capabilities in the restoration of freshwater and saltwater wetland ecosystems. Our ecologists also regularly conduct wetland delineations. A wetland delineation, a requirement of most permitting efforts, is the field work conducted to determine the boundary between the upper limit of a wetland and the lower limit of an upland thus identifying the approximate extent and location of wetlands on a requested site.
For this edition of our “A Day in the Life” blog series, we join Environmental Scientist Ivy Babson and Regulatory Compliance & Wildlife Surveys Project Manager Emily Bjorhus, PWS out in the field for a wetland delineation.
Most commonly, wetlands are delineated based on the Routine Onsite Determination Method set forth in the Federal Manual Identifying and Delineating Jurisdictional Wetlands (FICWD 1989) with supplemental information provided by the applicable United States Army Corps of Engineers’ (USACE) regional supplement manual.
USACE’s “three-parameter” approach defines an area as a wetland if it exhibits, under normal circumstances, all the following characteristics:
Ivy and Emily begin by coordinating with the client to ensure they’ve been granted site access approval.
They then perform a comprehensive desktop analysis of the project site, identifying existing features like wetlands, open waters (streams, lakes), and potential hydric soils. This involves utilizing resources like USFWS’s National Wetland Inventory Mapper, the U.S. Geological Survey’s SSURGO Soils Survey, and, for New Jersey-based delineations, NJDEP’s GeoWeb. The desktop review also allows Ivy and Emily to assemble the proper safety gear and create a Model Health & Safety Plan (HASP). A HASP must always be prepared before the field work begins.
Then, the field-day packing begins; the following items are a requirement for any wetland delineation:
It’s always important to make a plan for the project. If we are delineating a large property, it might take several days to traverse, and each day, the weather might be different. So planning ahead, but also being prepared for unexpected changes, will make the day go that much smoother. And, as part of the HASP, we must identify important points of contact and know where the closest hospital is in case of a serious emergency. So, reviewing this information and planning ahead prior to heading into the field is a very important step in the process.
While wetland delineations can be conducted any time of the year, they are best conducted during the “growing season” when soil temperatures are above the biologic zero and vegetation is easily identifiable by leaves, inflorescence, or other unique identifying characteristics that would otherwise be difficult to identify during the winter months.
Ivy and Emily begin by locating known (mapped) wetland or waterbody features and writing a list of all plants observed on-site. They maintain the plant list throughout the day.
If, during the desktop review, they find a mapped wetland or stream, they walk there first to determine if wetlands are actually present. Even if a wetland is mapped on a database, it may not actually exist for various reasons. On the flip side, even if a site is not mapped as containing wetlands, the site could very well contain them. As such, the wetland delineation determines exactly what is on-site and supplements the desktop review.
As mentioned above, a wetland delineation considers three determining factors: 1) vegetation, 2) soils, and 3) hydrology. While on site, Ivy and Emily must identify hydrophytic vegetation, take soil borings, and look for wetland hydrology to identify whether a wetland is present or not.
Wetlands are dominated by hydrophytes which are plants that can grow in water or on a substrate that is at least periodically deficient in oxygen because of excessive water content and depleted soil oxygen levels.
The USACE and NJDEP definition of hydrophytes is based on the USFWS classification system. In general, any plant species that is found growing in wetlands more than 50% of the time is considered a hydrophyte. These plants include those classified by the USFWS as “facultative,” “facultative wetland,” or “obligate.”
As a wetland delineator, it is important to possess strong plant identification skills and an eye for recognizing various ecological plant communities, which are groups of plants that share a common environment and environmental requirements. They are often defined by dominant plant species.
Once Ivy and Emily identify the hydrophytic plant community, they determine what type of ecological community they are in (e.g., freshwater forested wetland, estuarine scrub-shrub wetland, or freshwater tidal emergent marsh). Today, they are in a freshwater forested wetland, which means Ivy and Emily must now assess each stratum of the forested wetland by writing down the species and associated percent species cover.
To accurately describe the vegetation at each sampling point, we collect data on each horizontal strata or layer. Vegetative strata for which dominants are determined include (1) tree (> 5.0 inches diameter at breast height (DBH) and 20 feet or taller); (2) sapling (0.4 to <5.0 inches DBH and <20 feet tall); (3) shrub (usually 3 to 20 feet tall including multi-stemmed, bushy shrubs); (4) woody vine; and (5) herb (herbaceous plants including graminoids, forbs, ferns, fern allies, herbaceous vines, and tree seedlings). They repeat this process for each representative wetland.
Next, Ivy and Emily look for the upland plant community that is directly upslope of the wetland and make note of the proximity to the wetland, repeating the same vegetation documentation process.
Ivy and Emily must determine whether the soils within the hydrophytic plant community are hydric. Hydric soils are defined as soils that are saturated, flooded, or ponded long enough during the growing season to develop anaerobic conditions in the upper part. Hydric soil indicators are features in the soil that predominantly form by biogeochemical processes in a saturated and anaerobic environment and result in the accumulation of loss of iron, manganese, sulfur, or carbon compounds.
Emily uses a soil auger to collect a sample of the first 6 – 12 inches of soil where the most significant parts of a hydric soil would be occurring.
Once Ivy and Emily identify that the soil is indeed hydric, Ivy uses her Munsell soil color book to determine the value of the soil and each hydric soil indicator.
They also document additional characteristics of each soil layer: Is it loam, silty loam, sand, sandy loam, silt, muck, clay, clayey loam, etc.? What is the percentage of rocks, plant roots, or other organic matter in each layer? What is the percentage of redoximorphic features of each layer and are they faint or prominent?
Each layer of the soil profile, which is typically documented to a depth of at least 18 inches, is sectioned out and thoroughly described.
The identification of positive indicators of wetland hydrology includes direct observation of indicator groups, such as the observation of surface water or saturated soils, evidence of recent inundation, evidence of current or recent soil saturation, and evidence from other site conditions or data. Each group contains several indicators, which are classified into categories known as “primary” or “secondary” indicators.
To positively identify the area as being a wetland, at least one primary wetland indicator (from any group) or at least two secondary wetland indicators (from any group) must be present.
Additionally, for an area to be designated as a wetland, the area must have the presence of water for a week or more during the growing season. Areas with wetland hydrology characteristics are those where the presence of water has an overriding influence on characteristics of vegetation and soils due to anaerobic and reducing conditions, respectively.
Today, Emily and Ivy observe a depression (secondary) along with a few inches of standing water (primary), water-stained leaves (primary), frogs hopping around (primary), and moss trim lines on the tree trunks (secondary). All signs point to a forested wetland; however, there is more to consider.
Ivy and Emily’s soil boring assessment showed that the soils within the top 12 inches of the soil surface were saturated (primary) and bright orange streaks were visible along the plant roots, which they documented as oxidized rhizospheres along living roots (primary). Because they identified more than one primary and two secondary wetland indicators, they can confidently delineate the wetland.
Now that Ivy and Emily established that a wetland is present, they must find the boundary of the upland. They are now looking for the absence of hydrophytic vegetation, hydric soils, and positive indicators of wetland hydrology as well as the dominance of upland ecological plant communities. The same analysis and documentation process they completed for the wetland area is also required for the upland area.
Once they locate the boundary, they flag the wetland line, labeling the flagging with the wetland nomenclature and either hanging it or pinning it into the ground.
While the description sounds relatively simple, finding the boundary between a wetland and upland can be tricky and time consuming. For example, there may be some hydrophytic vegetation growing within an upland and there may be one secondary positive indicator of wetland hydrology, but hydric soils are missing. To positively classify an area as a wetland, a slam dunk on all three parameters is required.
Ivy and Emily must also delineate waterbodies concurrent with wetlands. Waterbodies may include, but are not limited to, streams, rivers, lakes, and ponds. To delineate a waterbody, they hang labeled flagging along the waterbody’s top of bank or its ordinary high water mark. Throughout this process, they take pictures to document the existing waterbody conditions.
Once the wetland delineation is complete, Ivy and Emily draw out a field sketch that depicts the approximate extent and location of the wetland and waterbody boundaries with their respective nomenclature.
Depending on the project scope, the field sketch is either submitted to a Professional Licensed Surveyor who will then visit the site to survey each wetland and waterbody flag, or Ivy and Emily will return to the site to survey each flag with a survey-grade GPS. Once the survey is complete, Ivy and Emily will conduct a final review of the plans to ensure accuracy.
If requested, they will also prepare a wetland delineation report, which outlines the delineation method, findings, results, and thorough description of each wetland and its soils, hydrology, and vegetation.
“Wetland delineations aren’t for the faint of heart,” said Ivy. “At the end of the day, you might emerge from a dense stand of Phragmites garnering strange looks from passersby with muck smeared on your face, sticks and leaves poking out of your hair, a belly full of mosquitos that you might have accidentally swallowed, and fingernails stuffed with dirt. However, there isn’t any other type of field that I would rather be in. As a wetland delineator, I can access environments that most people would steer clear of and, as a result, I get to see things that I wouldn’t get to see anywhere else. I get to improve my plant identification skills and expand my knowledge of how wetlands function as an ecosystem.”
A big thanks to Ivy and Emily for taking us out in the field for a wetland delineation!
Emily Bjorhus is a Project Manager that specializes in environmental regulatory compliance, ecological services and wildlife surveys. She leads federal, state and local environmental permitting processes, NEPA compliance and documentation, Endangered Species Act Section 7 consultations, and Clean Water Act Section 404(b)1 analyses. Mrs. Bjorhus is a certified Professional Wetland Scientist.
As an Environmental Scientist, Ivy Babson regularly conducts wetland delineations and monitoring, flora/fauna surveys, water quality sampling, fishery surveys, permitting, and regulatory compliance for a series of projects. She earned her Wetland Delineation Certification from Rutgers University. Ivy graduated from the University of Vermont in 2019 with a B.S. in Environmental Science with a concentration in Ecological Design, and minor in Geospatial Technologies.
To read more about our wetland restoration work, go here: http://bit.ly/PHwetland. If you enjoyed this blog, check out another one from our “A Day in the Life” series, and stay tuned for more.
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