wetland delineation special...

2017 Critical Methods Tom Nedland, WDNR

Wetland Delineation Special Considerations

Important Delineation Considerations

VEGETATION • Use the most up to date list


VEGETATION • Populus tremuloides

and Rubus idaeus are FAC in NC/NE Regions of Wisconsin


Be sure to consider nomenclature changes • Be sure to look up synonyms

• glossy buckthorn = Frangula alnus (R. frangula) • weeping willow= Salix x pendulina (S. babylonica) • crack willow = Salix x fragilis (S. fragilis)

• http://rsgisias.crrel.usace.army.mil/nwpl_static/index.html

VEGETATION

http://rsgisias.crrel.usace.army.mil/nwpl_static/index.html

Important Delineation Considerations SOILS Field Indicators of Hydric Soil in the United States -version 8.0 • Includes all changes from latest errata. • Adds clarifying statements “within” replaced with < clarifies starting depth requirements

Important Delineation Considerations SOILS Use appropriate hydric soil indicators – per texture

Mineral Soils • A indicators (All mineral textures) • Sandy Textures = S Indicators

LFS or coarser (LS, FS, S)

• Loamy/Clayey Textures = F Indicators LVFS or finer (SL, L, SIL, SCL, CL, SICL,

SC, SIC, C)

Organic Soils • A indicators

Important Delineation Considerations SOILS Fun Test!!! • Which indicator(s) can be used for a diagnostic

layer that is 1. Loamy fine sand 2. Fine sandy loam


layer that is 1. Loamy fine sand (A and S) 2. Fine sandy loam


layer that is 1. Loamy fine sand (A and S) 2. Fine sandy loam (A and F)

Important Delineation Considerations SOILS Dig soils to adequate depth Regional Supplements

Recommend 20 inches. Hydric Soil Indicators Version 8.0 Recommends 20 inches Exceptions: May need to dig

deeper during dry season or in mollisols.

Dry Season = 24 inches to document dry season water table

Example soil profile. NRCS.

Important Delineation Considerations SOILS Understand Term Depleted Matrix • Value 4, Chroma 1 or 2, with >2% redox

concentrations • Value 5, Chroma 2, with >2% redox

concentrations • Value 5, Chroma 1, redox not required • Value >6, Chroma 1 or 2, redox not required

Depleted Matrix Value >5 chroma 1,

Value >6, chroma 2

with or without redox concentrations

4/1, 4/2, 5/2 with >2%

redox concentrations

Important Delineation Considerations HYDROLOGY Read and understand the user notes! • Geomorphic Position (D2) • Sparsely vegetated

concave surface (B8)

Important Delineation Considerations HYDROLOGY Geomorphic Position (D2) • Probably present if in a concave landscape position

and the other two parameters are present

Review user notes: not applicable in areas with functioning drainage systems or rapidly permeable soils

Important Delineation Considerations HYDROLOGY Geomorphic Position (D2) • Recommendation:

1. Rapidly Permeable Soils – do not indicate as present unless soil and vegetation parameters are present

2. Drainage Systems – do a hydrologic analysis if in a concave landscape position and hydric soils present

“Rapidly permeable” includes gravel, sand, and fine sand

Photo from Winnebago County Soil Survey

Knoll: Geomorphic Position Indicator generally not applicable

Photo from Winnebago County Soil Survey

Depression/Drainageway: Geomorphic Position Indicator generally is applicable

Important Delineation Considerations HYDROLOGY Sparsely vegetated concave surface (B8) • Concave surfaces with less than 5% ground cover

caused by long duration ponding during the growing season Review user notes: should contrast with adjacent

convex areas. • Recommendation:

1. Make sure sparse vegetation is due to ponding, not shading (compare concave to convex landforms)

2. Make sure vegetation is sparse – less than 5% ground cover

Sparsely vegetated concave area caused from long term ponding

Sparsely vegetated convex area caused from dense shading

Important Delineation Considerations HYDROLOGY Utilize Gage Data Where Available

Median Value = Determines the growing season flood elevation for 50/100 years. Any land found below the median elevation meets wetland hydrology and hydric soil indicators. Useful for large, dynamic systems

Important Delineation Considerations HYDROLOGY Stunted or stressed plants (D1 Indicator) • Use caution in harvested crop fields • Crop stubble can be very misleading. Suggest

not utilizing this indicator unless crops are still alive, or evidence of stunting/stress is justified with supplemental information. Eg. Explain in remarks how the

“stunted/stressed” stubble fits into the larger picture (landscape position, soil indicators, off-site review, etc.)

Important Delineation Considerations GENERAL

Antecedent Hydrologic Conditions • Recommend NRCS Method

• http://el.erdc.usace.army.mil/elpubs/pdf/wrap00-1/contents.pdf

• Statewide consistency • Not representative of site conditions? – Other sources

• USGS Waterwatch • Palmer Drought Severity Index

• Transfer information to data forms accordingly • In report, let reviewers know this information was taken into consideration

http://el.erdc.usace.army.mil/elpubs/pdf/wrap00-1/contents.pdf

http://el.erdc.usace.army.mil/elpubs/pdf/wrap00-1/contents.pdf

NRCS Antecedent Rainfall Documentation Method Important Delineation Considerations


Antecedent Hydrologic Condition Example, Madison • Example: NRCS method not accurate (June 9, 2008)

March (1) April (2) May (3) Result Normal (2) Wet (3) Normal (2) Normal

Product Score (2) (6) (6) (14)

• 7.8 inches of rain fell between June 1 and June 8. • NRCS method not accurate under these conditions!!


Antecedent Hydrologic Condition Example, Madison • Other tools can help tell the tale (June 9, 2008)

USGS Waterwatch Data


Antecedent Hydrologic Condition Example, Madison • Other tools can help tell the tale (June 9, 2008)

Palmer Drought Index


Antecedent Hydrologic Condition Example, Madison • Let reviewers know how this information was taken

into consideration “Results of the antecedent precipitation analysis indicate the site had received normal rainfall during the three months prior to the wetland delineation. However, 7.08 inches of rainfall was documented near the site two days prior to the field investigation. Based upon the extreme amount of rain that occurred shortly prior to the field visit, it was assumed that primary wetland hydrology indicators would be present within the wetlands, as well as adjacent upland areas.”

Important Delineation Considerations GENERAL Document Growing Season • Most important for early or late season work • Document on data form or in report

• Green up (early) • Green growth on non-evergreen plants (late) • >41F at 12 inches below soil surface (late or early)

Growing Season Examples

Important Delineation Considerations GENERAL Document Growing Season • If field work completed outside of growing season…

• Perform a field visit the following spring • Verify accuracy of delineation (vegetation and hydrology)

Non-Growing Season Example UNLESS… Soil temp is >41F at 12 inches below soil surface.

Important Delineation Considerations GENERAL Adequately characterize a site • Take data points in Wet spot on soil mapping Wetness signatures on air photos Hydric or inclusion soils Distinct plant communities observed on air photos Mapped wetland area

Important Delineation Considerations GENERAL Adequately characterize a site


Wetness Signature


Wetness Signature

Mapped WWI


Wetness Signature

Mapped WWI

Potential Wetland Soils


Areas that need documenting


100 feet


100 feet

Why isn’t this area wetland?

How was this boundary established? Need paired points.

Why isn’t this area wetland?

Important Delineation Considerations GENERAL In difficult wetland situations, consider all data before reaching a decision Agricultural Sites Consideration 1: Has hydrology been altered?

• If not, soils may tell the story of the site Consideration 2: What does the preponderance of

information tell you? • Does offsite review indicate healthy crops and

drains have been documented? Often that is enough information to justify a field decision.

• Does offsite review indicate poor crop health, even though drains have been documented? That suggests the area is not effectively drained.

Important Delineation Considerations GENERAL In difficult wetland situations, make sure to consider all data before reaching a decision Agricultural sites Other Considerations:

• Are reference areas available? • What were the antecedent precipitation levels? • Does the volunteer vegetation in the questionable

area differ from the volunteer vegetation in obvious upland areas?

Questions

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