An overview of
Wetland Delineation
In preparation for next week’s field trip
Go to the web site below and SCAN…
1987 Army Corps of Engineers Manual
www.wes.army.mil/el/wetlands/pdfs/wlman87.pdf
(note: cut and paste the web address)
Purpose and Objectives of the Manual
The purpose of the manual is to provide users with guidelines and
methods to determine whether an area is a wetland for purposes
of Section 404 of the Clean Water Act.
“Jusrisdictional Wetland”
Specific objectives of the manual are to:
a. Present technical guidelines for identifying wetlands and
distinguishing them from aquatic habitats and other nonwetlands.
b. Provide methods for applying the technical guidelines.
c. Provide supporting information useful in applying the technical
guidelines.
Steps in a Delineation
1. Gather and review documents, if
possible before going to the site
2. Visit site, document vegetation and
field indicators of hydrology and soils
3. Write report
Review these Documents:
(copies of these will be provided to you next week)
1.
2.
3.
4.
5.
Property boundary map (usually from client)
Topo map (online: www.topozone.com)
Soil Survey maps & info (seen in previous lab)
NWI maps (discussed subsequently)
Other maps as necessary (aerial photos and
satellite imagery)
Soil Maps
1. Locate the site (make field copy and
draw in property boundaries)
2. Read about the soils types at the site
3. Check National and Local Hydric Soil
Lists
4. Note Munsell Colors for soils listed
Hydric Soil List Home Page:
http://www.statlab.iastate.edu/soils/hydric/homepage.html
Can you find Trinity Soil Series on the State Page?
What is the other hydric soil in Denton County?
Hydric Soil Indicators are also discussed
on the web site and
associated links
National Wetland Inventory
1. Nationwide effort by USFWS to map all
wetlands and bodies of water in the U.S.
2. Maps are based on aerial photos and color
infrared photography
3. Limited field verification
4. Information is overlaid on topo maps
5. Approx. 40% have been digitized (only
Dallas and Houston in Texas)
NWI maps, cont.
5. Hard copies of NWI maps at Willis Library
Document section
6. Alphanumerical description of wetlands
based on classification system of Cowardin
1979
7. NWI maps do not confirm presence or
absence of jurisdictional wetlands
8. See example & read more in Chpt. 21 of text
Interactive Mapping Tool
http://ecos.fws.gov/nwi_mapplet/area_selection.html
The above web site allows you to create a NWI map
for areas in the US where the info has been digitized.
Try making a map for Dallas County.
NWI map
for NEPA
Document
Lewisville
Lake
Management
Plan
Zoom in and find the
water budget site. Is
it mapped as a
wetland? What type
are the nearest
wetlands to the site?
http://www.swf.usace.army.mil/links/OPs/Lewisville/toc/exh5no1.jpg
Cowardin Wetland Classification
most frequently used in U.S.
1. System (e.g. P=Palustrine=associated with
Ponds)
2. Subsystem
3. Class
4. Water regime
5. Explained fully in Chpt. 21 or on web site
To the Field
Sept. 19, 1 pm
We’ll be going to do a field
delineation (don’t know where
yet). Wear long pants, boots or
other sturdy shoes, bring
sunscreen, bug repellant, and
water.
Establish Transects
1. Transects should cross all possible
bodies of water or potentially wet areas
2. The number of transects depend on size
of property
3. Plots are placed along the transects at
areas where the vegetation /hydrology
/soils appears to change
4. Zoom in on the following map for
examples of transects and plots
Document Conditions at Plot
Take a minute to look at the sample delineation
data form which is a Word file
“Delinsample.doc” . This form was part of a
local delineation and it has three sections:
1. Vegetation
2. Hydrology
3. Soils
Vegetation
1. Each plot: ID
dominant species in
each strata (trees,
vines, shrubs, herbs)
2. Look up status of
species on National
List of Wetland Plants
e.g. OBL, FAC, etc.
(available online,
search for it)
Vegetation cont’
1. Is the percentage of dominant plant species
that are hydrophytes (FAC, FACW and OBL)
greater than 50%?
2. See chapter 21 or the Manual for
explanations of these terms.
3. If yes, then wetland vegetation is present.
Wetland Hydrology
1. Check for saturation within 12 inches
2. Look for wetland hydrology field
indicators (drift lines, water marks,
sediment deposits, etc.)
3. Include recorded or historical data
such as stream gages, flood maps,
etc.
Hydric Soils
1. Use auger to take a soil sample
2. Describe the horizons (texture and
color), compare to soil survey info
3. Document any hydric soil indicators
Soil auger and page from a Munsell Color Chart.
Make a Determination
If wetland
vegetation,
hydrology,
and soils
are present,
then the
site is a
wetland.
Dominant vegetation is Eragrostis repens, soil is saturated and
has hydric indicators, is this plot located in a wetland?
• If any of the three are missing, the site is not a
jurisdictional wetland.
• If not wetland, the site may be either aquatic or
upland. Aquatic sites may be protected by
the Clean Water Act.
Continue along transects…..
1. Until site is adequately characterized.
2. Include photo documentation of each plot;
3. Estimate size of total wetlands on site;
4. Characterize community types based on
hydrology and vegetation;
Write Report
GOOD NEWS!!!
1. In lieu of the full report, each student will
turn in the data sheets (one sheet per plot)
2. If you can’t identify a plant in the field,
bring a complete sample in a zip lock bag
back to the lab, if you’re nice, Robin
Buckallew might help you id the plant.
3. Data sheets due Sept. 26.