or grading creates poorly drained pockets that become an increasing 

 problem as slope decreases. 



Slopes from 10 percent to less than 1 percent have been success- 

 fully planted. Slopes of 1 to 3 percent are preferable as long as 

 surface drainage is not impeded. 



3. Exposure . 



Exposure to wave action is a major factor in determining the fea- 

 sibility of marsh establishment along any exposed shoreline. Marsh 

 plants can withstand low to moderate levels of wave energy character- 

 istic of many sites in sounds, bays, and estuaries, but cannot grow 

 and persist under high-energy conditions. For example, marshes are 

 not found on the open coasts of the Atlantic and Pacific Oceans and 

 the Great Lakes. 



Preliminary marsh-building design criteria have recently been 

 advanced and are based on limited data (Woodhouse, Seneca, and Broome, 

 1972, 1974, 1976; Garbisch, 1977; Knutson, 1977). Research is con- 

 tinuing on this subject. In the meantime, some rough rule of thumb 

 is necessary. Wave climate, as determined by wind speed and direc- 

 tion, bottom and shoreline configuration, water level, and fetch, is 

 a dominating factor in determining site suitability. However, the 

 absence of information on the tolerance of marsh plantings to speci- 

 fic wave climates and the difficulty of forecasting wave climate for 

 specific sites, make it necessary to rely on more general indexes. 

 Fetch is probably the most readily determined and the most meaning- 

 ful available. It must be used with caution, always keeping in mind 

 the modifying effect of other factors . 



Although marsh plantings were reported as early as 1948 (Sharp 

 and Vaden, 1970), most plantings were done from 1969 to 1976: 19 on 

 the northeast Atlantic coast, 20 in the Chesapeake Bay, 19 on the 

 southeast Atlantic coast, 20 on the gulf coast, and 10 on the Pacific 

 coast. Successful establishments of sprigs or plugs were recorded at 

 fetches of less than 4 kilometers in North Carolina and the Chesapeake 

 Bay, and at a maximiom fetch of 2 kilometers in Texas and California 

 (San Francisco Bay) . Seeding has been successful in North Carolina 

 and Chesapeake Bay when the fetch is less than 1 kilometer. Much de- 

 pends on the timing of individual storms. The critical period is 

 during establishment. Storms that will eliminate fresh transplants 

 or young seedlings may have no effect on established stands. Also, 

 wave action during high water may be above much of the plantings with 

 damage confined to the upper part where it can be more readily toler- 

 ated. Consequently, experience with the same site can vary greatly 

 from year to year. 



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