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ERDC TR-04-1
overlap at a site and not be easily distinguished. Occasionally very large dis-
charges fill the entire floodplain beyond the area where the majority of channel-
forming processes occur. Evidence of previous hydrologic events, such as drift
material, may be removed and redeposited at higher elevations within the flood-
plain, altering one's perception of what is ordinary.
The indicators we identify in Table 1 contain a degree of variability as to the
level of event they may represent. This makes relying on any one indicator for
one point in time challenging. In addition, to avoid misinterpretation and increase
consistency in applications, many of the indicators need to be refined and will
require unambiguous definitions and descriptions. These will need to be devel-
oped after initial testing and evaluation in a number of watersheds. Additional
study may suggest the necessity to combine certain indicators or to use them only
in particular positions in the watershed or landscape.
We make the following observations and suggestions about the potential
OHWM indicators identified in this literature review:
The indicators in Table 1 should not yet be used for jurisdictional
purposes pending further testing and verification;
The use of those indicators found consistently above and below OHW
may be helpful in determining the area within which the OHW boundary
is located;
If possible, gauge data and local hydrology models should be used as
supporting evidence until OHWM indicators are further refined and
tested; and
Other indicators not reported here may also be useful in delineating the
OHW boundary.