(7) General land uses, such as cleared (agriculture or 

 pasture), forested, or urban. 



CAUTION: Obtain the most recent USGS maps. Older maps may 

 show features that no longer exist and will not show new fea- 

 tures that have developed since the map was constructed. Also, 

 USGS is currently changing the mapping scale from 1:24,000 to 

 1:25,000. 



b. National Wetlands Inventory products . 



(1) Wetland maps. The standard NWI maps are at a scale of 

 1:24,000 or, where USGS base maps at this scale are not 

 available, they are at 1:62,500 (1:63,350 in Alaska). 

 Smaller scale maps ranging from 1:100,000 to 1:500,000 are 

 also available for certain areas. Wetlands on NWI maps 

 are classified in accordance with Cowardin et al. (1979). 

 CAUTION: Since not all delineated areas on NWI maps are 

 wetlands under Department of Army jurisdiction, NWI maps 

 should not be used as the sole basis for determining 

 whether wetland vegetation is present. NWI "User Notes" 

 are available that correlate the classification system 

 with local wetland community types. An important feature 

 of this classification system is the water regime modi- 

 fier, which describes the flooding or soil saturation 

 characteristics. Wetlands classified as having a tempo- 

 rarily flooded or intermittently flooded water regime 

 should be viewed with particular caution since this 

 designation is indicative of plant communities that are 

 transitional between wetland and nonwetland. These are 

 among the most difficult plant communities to map accur- 

 ately from aerial photography. For wetlands "wetter" than 

 temporarily flooded and intermittently flooded, the prob- 

 ability of a designated map unit on recent NWI maps being 

 a wetland (according to Cowardin et al. 1979) at the time 

 of the photography is in excess of 90 percent. CAUTION: 

 Due to the scale of o.erial photography used and other 

 factors, all NWI map boundaries are approximate. The 

 optimum use of NWI maps is to plan field review (i.e. how 

 wet, big, or diverse is the area?) and to assist during 

 field review, particularly by showing the approximate 

 areal extent of the wetland and its association with other 

 communities. NWI maps are available either as a composite 

 with, or an overlay for, USGS base maps and may be 

 obtained from the NWI Central Office in St. Petersburg, 

 Fla., the Wetland Coordinator at each FWS regional 

 office, or the USGS. 



(2) Plant database. This database of approximately 



5,200 plant species that occur in wetlands provides infor- 

 mation (e.g., ranges, habitat, etc.) about each plant 

 species from the technical literature. The database 

 served as a focal point for development of a national list 

 of plants that occur in wetlands (Appendix C, Section 1). 



44 



