An overview of Wetland Delineation

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An overview ofWetland Delineation

• In preparation for next weeks field trip

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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)
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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.
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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

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Review these Documents(copies of these will be
provided to you next week)

1. Property boundary map (usually from client)
2. Topo map (online www.topozone.com)
3. Soil Survey maps info (seen in previous lab)
4. NWI maps (discussed subsequently)
5. Other maps as necessary (aerial photos and
   satellite imagery)

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Soil Maps

• Locate the site (make field copy and draw in
  property boundaries)
• Read about the soils types at the site
• Check National and Local Hydric Soil Lists
• Note Munsell Colors for soils listed

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Hydric Soil List Home Page
http//www.statlab.iastate.edu/soils/hydric/homepa
ge.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
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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)

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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
• NWI maps do not confirm presence or absence of
  jurisdictional wetlands
• See example read more in Chpt. 21 of text

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Interactive Mapping Tool

• http//ecos.fws.gov/nwi_mapplet/area_selection.htm
  l

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.
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NWI map for NEPA Document Lewisville Lake Manageme
nt 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
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Cowardin Wetland Classificationmost frequently
used in U.S.

1. System (e.g. PPalustrineassociated with Ponds)
2. Subsystem
3. Class
4. Water regime
5. Explained fully in Chpt. 21 or on web site

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To the Field

• Sept. 19, 1 pm
• Well be going to do a field delineation (dont
  know where yet). Wear long pants, boots or other
  sturdy shoes, bring sunscreen, bug repellant, and
  water.

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Establish Transects

• Transects should cross all possible bodies of
  water or potentially wet areas
• The number of transects depend on size of
  property
• Plots are placed along the transects at areas
  where the vegetation /hydrology /soils appears to
  change
• Zoom in on the following map for examples of
  transects and plots

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Document Conditions at PlotTake 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

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Vegetation

• 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)

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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.

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Wetland Hydrology

• Check for saturation within 12 inches
• 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.

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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

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Soil auger and page from a Munsell Color Chart.
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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?
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• 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.

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Continue along transects..

• 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

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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 cant identify a plant in the field, bring
   a complete sample in a zip lock bag back to the
   lab, if youre nice, Robin Buckallew might help
   you id the plant.
3. Data sheets due Sept. 26.