Section B. Preliminary Data Gathering and Synthesis 



53. This section discusses potential sources of information that may be 

 helpful in making a wetland determination. When the routine approach is used, 

 it may often be possible to make a wetland determination based on available 

 vegetation, soils, and hydrology data for the area. However, this section 

 deals only with identifying potential information sources, extracting perti- 

 nent data, and synthesizing the data for use in making a determination. Based 

 on the quantity and quality of available information and the approach selected 

 for use (Section C) , the user is referred to either Section D or Section E for 

 the actual determination. Completion of Section B is not required, but is 

 recommended because the available information may reduce or eliminate the need 

 for field effort and decrease the time and cost of making a determination. 

 However, there are instances in small project areas in which the time required 

 to obtain the information may be prohibitive. In such cases PROCEED to 

 paragraph 55, complete STEPS 1 through 3, and PROCEED to Section D or E. 



Data sources 



54. Obtain the following information, when available and applicable: 



a. uses quadrangle maps. USGS quadrangle maps are available at 

 different scales. When possible, obtain maps at a scale of 

 1:24,000; otherwise, use maps at a scale of 1:62,500. Such 

 maps are available from USGS in Reston, Va. , and Menlo Park, 

 Calif., but they may already be available in the CE District 

 Office. These maps provide several types of information: 



(1) Assistance in locating field sites. Towns, minor roads, 

 bridges, streams, and other landmark features (e.g. 

 buildings, cemeteries, water bodies, etc.) not commonly 

 found on road maps are shown on these maps. 



(2) Topographic details, including contour lines (usually at 

 5- or 10-f t contour intervals) . 



(3) General delineation of wet areas (swamps and marshes) . 



Note: The actual wet area may be greater than that shown 

 on the map because USGS generally maps these areas based 

 on the driest season of the year. 



(4) Latitude, longitude, townships, ranges, and sections. 

 These provide legal descriptions of the area. 



(5) Directions, including both true and magnetic north. 



(6) Drainage patterns. 



43 



