1987 Wetland Delineation Manual - The Wetlands Regulation Center
1987 Wetland Delineation Manual - The Wetlands Regulation Center
1987 Wetland Delineation Manual - The Wetlands Regulation Center
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<strong>Wetland</strong> Delination <strong>Manual</strong>, <strong>1987</strong> 35<br />
• STEP 7 - Determine Whether Soils of the Project Area Have Been Adequately Characterized.<br />
Examine the summarized soils data and determine whether the soils have been adequately<br />
characterized. For routine determinations, the soil series must be known. For comprehensive<br />
determinations, both the soil series and the boundary of each soil series must be known.<br />
Record information on DATA FORM 1. In either case, if there is evidence of recent significant<br />
soils alteration due to human activities or natural events, PROCEED TO Section F. Otherwise,<br />
PROCEED TO STEP 8.<br />
• STEP 8 - Summarize Available Hydrology Data. Examine available information and<br />
describe the area hydrology. Consider the following:<br />
a. USGS quadrangle maps. Is there a significant, well-defined drainage through the area? Is<br />
the area within a maior floodplain or tidal area? What range of elevations occur in the area,<br />
especially in relation to the elevation of the nearest perennial watercourse?<br />
b. NWI overlays or maps. Is the area shown as a wetland or deepwater aquatic habitat? What<br />
is the water regime modifier?<br />
c. EIAs, EISs, or GDMs that describe the project area. Extract any pertinent hydrologic data.<br />
d. Floodplain management maps. <strong>The</strong>se maps may be used to extrapolate elevations that can<br />
be expected to be inundated on a 1-, 2-, 3-year, etc., basis. Compare the elevations of these<br />
features with the elevation range of the project area to determine the frequency of inundation.<br />
e. Federal, State, and local government documents (e.g. CE floodplain management maps and<br />
profiles) that contain hydrologic data. Summarize these data.<br />
f. Recent (within past 5 years) aerial photography that shows the area to be inundated. Record<br />
the date of the photographic mission.<br />
1. Newspaper accounts of flooding events that indicate periodic inundation of the area.<br />
h. SCS County Soil Surveys that indicate the frequency and duration of inundation and soil<br />
saturation for area soils. CAUTION: Data provided only represent average conditions for a<br />
particular soil series in its natural undrained state, and cannot be used as a positive<br />
hydrologic indicator in areas that have significantly altered hydrology.<br />
i. Tidal or stream gage data for a nearby water body that apparently influences the area.<br />
Obtain the gage data and complete (1) below if the routine approach is used, or (2) below if<br />
the comprehensive approach is used (OMIT IF GAGING STATION DATA ARE<br />
UNAVAILABLE):<br />
25 February 1997 Environmental Techncal Services Co. 834 Castle Ridge Rd Austin, Texas 78746