10 Wetland Assessment Criteria 



Groups 1-3. To protect the integrity of the wetland system, it is often 

 essential to acquire adjacent or intermixed upland areas. 



The Senate Committee Report on the Act provided guidance indicating that 

 acquisition of an interest in wetlands includes adjacent and associated 

 uplands essential to maintaining the values of the wetlands. However, 

 the Act refers specifically to the acquisition of wetlands and it was not 

 intended that former wetlands converted to non-wetlands were to be 

 targeted for acquisition purposes. These areas may have been diked or 

 drained by man for conversion to other uses, such as agriculture. As such, 

 there may be several factors making these sites less viable for 

 acquisition, including landowner opposition to selling the land, high cost 

 per acre for "highly productive" land, and high cost for wetland 

 restoration. 



Although the trends study provides the only data useful for a statistical 

 comparison of ecoregions in the U.S. during the 1954-74 period, it is 

 recognized that the data may not accurately portray wetland trends for 

 certain local, State or regional areas. Other historical, recent or detailed 

 information may demonstrate a different trend of wetland loss, stability 

 or increase for a local. State or regional area. When information is 

 available to substantiate trends for various wetland types other than that 

 shown by the NWI trends study, it may be used to support departures from 

 the trends groupings presented in Table 1. For example, the trends data 

 showed that palustrine open water wetlands increased between 1954 and 

 1974. However, a State may have documentable information showing that 

 generally unmappable wetland types, such as aquatic bed, rock bottom or 

 reef, found within the open water type, decreased significantly and 

 warrant priority consideration for acquisition. Also, wetland types may 

 have been historically rare, such as in the arid regions of the western 

 U.S., so would warrant priority consideration. 



(b) Losses by Region 



The NWI trends study generated national estimates of wetlands and 

 deepwater habitat acreage for the lower 48 States during the 1950's, the 

 1970's, and the change for this period. The study also generated State 

 estimates. The study samples were selected within boundaries formed by 

 35 physical subdivisions described by Hammond (1970), States, and a 

 special coastal strata (see Cowardin et al., 1979, pg. 27) including the 

 marine intertidal category and the estuarine system. The study results 

 are valid at the national level, but the data are not reliable enough to 

 provide statistical significance at the State level. 



The national data show that certain ecoregions of the U.S. have lost more 

 of their wetland base acreage (i.e., between 1954 and 1974) than other 

 areas. In this NWPCP, ecoregions are used for an objective comparison 

 of wetland losses among various locations. 



