CRS-54 



One Federal regulatory tool that requires an ability to estimate the value 

 of wetland functions is mitigation. Under the mitigation concept, recently 

 implemented by the U.S. Fish and Wildlife Service, the Service may not oppose 

 a proposed action if the permit applicant agrees to enhance or restore other 

 wetland areas to a level that approximates wetland values lost as a result 

 of the proposed project. 38/ This approach, which requires detailed knowledge 

 about the functions common to different wetland types, has been tried in a 

 number of cases in the recent past, following guidelines developed by the 

 Service. 



WETLAND ALTERATION 



Wetlands are altered by human activities in a variety of ways. Wetlands 

 may be altered directly by filling, dredging, draining or creating impound- 

 ments. Indirectly, alteration of waterflow patterns at other locations, and 

 changes in adjacent land use can change the functions and values of wetland 

 areas. Appendix A, which contains a detailed listing of the physical and 

 biological impacts associated with transportation fills, illustrates the 

 growing understanding of wetlands functions and impacts. The table below 

 lists some common activities which impact wetlands. 



TABLE 1. Common Activities Which Impact Wetlands 



o Direct removal of vegetation 

 o Direct removal of topsoil 



38 / U.S. Department of the Interior. Fish and Wildlife Service. U.S. 

 Fish and Wildlife Service Mitigation Policy, Notice of Final Policy. Federal 

 Register, v. 46, no. 15, January 23, 1981. p. 7644-7663. 



