Atypical Situations
Atypical Situations
Areas in which indicators of one or more
wetland parameters have been obscured by
some recent change or disturbance
Some of these situations are now covered
in “Difficult Wetland Situations in the 87”
Manual Supplements
Atypical Situations
Were wetlands present
before disturbance?
(e.g., enforcement cases)
Are wetlands now present
on a disturbed site? (e.g.,
agricultural lands and
man-induced wetlands)
Atypical Situations
Procedures given in the Corps Manual
depend on which parameter was disturbed:
• Vegetation
• Soils
• Hydrology
HOWEVER………
Atypical Situations
Regardless of the parameter disturbed (soils, veg. or
hydrology), the same basic methodology is followed:
Step 1. Describe the alteration.
Step 2. Describe effects on the parameter.
Step 3. Characterize the original condition of
the parameter.
Step 4. Determine whether the parameter was
hydric (soil), hydrophytic (veg), or
wetland hydrology (hydrology).
PROBLEM
AREAS
PROBLEM
AREAS
Refers to wetlands where indicators
of one or more of the 3 parameters
may be absent or misleading due to
natural and/or seasonal variations
All three parameters are met, but
may not be apparent on a given day
or during a given growing season
PROBLEM AREAS
1. Seasonal Wetlands (more details in 87
Manual supplements)
2. FACU-Dominated Wetlands
3. Created Wetlands
4. Problem Soils (more details in 87 Manual
Supplements)
1. SEASONAL WETLANDS
The Problem: lack of hydrology indicators
during drier part of the growing season
Potential Solutions: make site visits during
early (wet) part of the growing season, and/or
use secondary indicators, scrutinize
the other two parameters, factor in
landscape position, use BPJ
Seasonal
Wetlands
Wetland/Upland Boundary:
• Is where water levels fluctuate the greatest
• Is where shortest duration wetland hydrology
occurs
• Often, only short-term hydrology data is
available; fortunate to have one growing
season of monitoring well data
Source: Dr. Richard Skaggs, April 1996
Upland
Boundary
Wetland
LOCATION
LOCATION
YEARS
YEARS MONITORED
MONITORED
ACCURACY
ACCURACY
UPLAND
UPLAND
3
WETLAND
WETLAND
5
95%
92%
BOUNDARY
BOUNDARY
1
60%
BOUNDARY
BOUNDARY
9
85%
BOUNDARY
BOUNDARY
15
94%
Can take up to 15 years of monitoring in the wetland
boundary zone to achieve the same accuracy as wetland and
upland monitoring
Soil Survey Data – a useful source of
information for seasonal wetlands
High
High Water
Water Table
Table
Soil
Series
Depth
Depth
Faxon
Faxon
0.0
0.0 –1.0
–1.0
Ettrick
Ettrick
Du
Du Page
Page
Flooding
Flooding
Frequency
Frequency
Duration
Duration
Months
Months
Nov-May
Nov-May
None
None to
to
Common
Common
V.
V. Brief
Brief
Apr-May
Apr-May
+1.0-1.0
+1.0-1.0
Nov-Jun
Nov-Jun
Frequent
Frequent
Brief
Brief to
to
Long
Long
Nov-May
Nov-May
>6.0
>6.0
----
Frequent
Frequent
Long
Long
Jan-Jun
Jan-Jun
Months
Months
1 July
Hydric
Hydric Soils
Soils
Hydrophytic
Hydrophytic Vegetation
Vegetation
Wetlands ???
Seasonal Wetlands…
1 July
1 June
Hydric
Hydric Soils
Soils
Hydrophytic
Hydrophytic Vegetation
Vegetation
Wetland
Wetland Boundary?
Boundary?
Seasonal Wetlands…
1 July
1 June
1 May
Hydric
Hydric Soils
Soils
Hydrophytic
Hydrophytic Vegetation
Vegetation
Wetland
Wetland Boundary
Boundary
Seasonal Wetlands…