increases in down stream flooding occurs with the loss of 25-50 percent of the 

 wetlands in the watershed. The Eastern Water Law Center of the University of 

 Florida College of Law' has developed a model surface water runoff control 

 ordinance that recognizes the role of wetlands in regulating water runoff. In 1975 the 

 Natural Resources Defense Council reviewed the flood control value of wetlands for 

 the Federal Insurance Administration and urged that agency to adopt regulations 

 that recognize this wetland function.** 



Do'lar values of the water retention and detention functions of wetlands have been 

 developed for a very few sites. Such values are valid for these particular sites and 

 cannot be generalized to other areas. However, it is interesting to note the Charles 

 River study estimated that the greater Boston area would be spared flood losses of 

 $647,000 annually by the year 2000. If this is viewed as a kind of return or interest 

 received from protecting or investing in wetlands, one can say that each wetland acre 

 has a value equal to $1,488 put in the bank at an interest rate of about 5 percent.'* 

 Since 1970 (and as recently as 1979) both the U.S. Army Corps of Engineers'" and the 

 Massachusetts' office of the U.S. Soil Conservation Service (SCS)' ' have developed 

 trial or "rule of thumb" techniques for evaluating the flood control values of 

 wetlands. These approaches numerically rate wetlands according to actual storage, 

 the effectiveness of the storage, the need for control downstream, damage potential, 

 or calculated factors based on percent of a watershed in wetlands. The flaw in the 

 dollar values generated by these procedures is the dependence upon downstream- 

 made structures to generate economic values or calculate avoided losses. Wetlands 

 that effectively detail flood waters on streams that have little man-made development 

 are rated low in flood control value. This ignores the value of current land uses that 

 do not involve structures as well as the loss of future opportunities for alternative 

 land uses if the flood detention function is impaired. The efforts to understand the 

 flood control function of wetlands have been very exciting, but it would seem that 

 hydrologists have much more to do in applying their technology more effectively to 

 wetland flood control than has been done to date. For example, studies of the 

 relations of wetlands to flood control in unglaciated areas of the United States are 

 lacking. 



Storm Damage 



Coastal wetlands have become regarded as landscape units that protect fastlands 

 from erosion, and act as buffers against coastal flooding and sea level rises. In 1974 

 research workers at the Virginia Institute of Marine Science reported that saline 

 marsh vegetation can absorb or dissipate wave energy and establish a dense root 

 system that stabilizes the soil.'' They also reported that freshwater species were less 

 effective in this regard and that the peat substrate of some marshes acts as a giant 

 sponge in receiving and releasing water. 



In the early 1970s they developed a ranking system for use in the Virginia wetland 

 regulation program that rates 12 coastal wetland plant communities for effectiveness 

 as buffers against erosion and flood. But actual experimental testing of this role of 

 coastal wetlands has not been conducted. University of Michigan wetland 

 researchers in 1978 stated that where physical processes combine to produce shore 

 erosion, the energies involved are likely to prevent the establishment of wetland 

 communities." This assumed function of coastal wetlands requires further study 

 before it is widely used as a basis for regulation. 



Water Quality 



In the anaerobic soils of wetlands the process called denitrification removes 

 nitrogen from the water and during the growing season plants remove nitrogen and 

 phosphorous from wetland soils and water. Researchers at Louisiana State 

 University's Center for Wetlands'^ have suggested that this function is a form of 

 natural tertiary treatment that has an income capitalized value in southeastern tidal 



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