during the commencement of the flood tides will be the 

 proper time for taking the low water line, and your 

 operations must be so timed, as to be on the shore on 

 those periods. 



18. You will establish points along the shores, and 

 mark them securely by means of stakes, at suitable 

 distances, for the use of the hydrographical parties 

 in taking their sounding--and also furnish them with 

 the high and low water line, from your map, they may 

 require. 



58. The first specific instruction regarding the nature of the line to 



be surveyed is contained in the Plane Table Manual (Wainwright 1889), which 



states: "In tracing the shoreline on an exposed sandy coast, care should be 



taken to discriminate [sic] between the average high-water line and the storm 



water line." Still later, Shalowitz (1964, p 174) elaborated by stating: 



The mean high-water line along a coast is the inter- 

 section of the plane of mean high water with the shore. 

 This line, particularly along gently sloping beaches, 

 can only be determined with precision by running spirit 

 levels along the coast. Obviously, for charting pur- 

 poses, such precise methods would not be justified, 

 hence, the line is determined more from the physical 

 appearance of the beach. What the topographer actu- 

 ally delineates are the markings left on the beach by 

 the last preceeding high water, barring the drift cast 

 up by storm tides. On the Atlantic coast, only one 

 line of drift would be in evidence. ... If only one line 

 of drift exists, as when a higher tide follows a lower 

 one, the markings left by the lower tide would be 

 obliterated by the higher tide and the tendency would 

 be to delineate the line left by the latter, or pos- 

 sibly a line slightly seaward of such drift line. 



In addition to the above, the topographer, who is an 

 expert in his field, familiarizes himself with the tide 

 in the area, and notes the characteristics of the beach 

 as to the relative compactness of the sand (the sand 

 back of the high-water line is usually less compact 

 and coarser) , the difference in character and color 

 of the sun cracks on mud flats, the discoloration of 

 the grass on marshy areas, and the tufts of grass or 

 other vegetation likely along the high-water line. 



59. Historical references are included to emphasize that it was the 

 intention of all the agency's topographic surveys to determine the line of 

 mean high water (MHWL) for delineation on maps. With the exception of tidal 

 marsh areas, where in most cases the outer limit of vegetation is mapped, 

 the MHWL delineated on the surveys by the experienced topographer or 



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