Breed, Hosmer, and Bone, 1958) three times each year on a regular sche- 

 dule in addition to surveys after major storms (Fig. 1). Historical 

 profile data, if available for the region being monitored, may exhibit 

 some depth below which no significant changes in bathymetry occur; 

 profiles should then be surveyed to this depth. If historical data are 

 not available, profiles should extend to the -12-foot contour. Past 

 experience in the Great Lakes suggests that only minor changes in bathy- 

 metry occur lakeward of this contour. 



Elevations or depth measurements should be referenced to the 

 International Great Lakes Datum (IGLD) . Table 1 gives IGLD elevations 

 of low water datum (LWD) for each of the Great Lakes, including maximum 

 and minimum stage of record. 



A minimum program for recording shoreline changes is to measure the 

 distance from a building to the water's edge and the length of the 

 property lines in early spring, mid-summer, and late fall (Fig. 2). 

 These lengths should be measured in a horizontal plane and extend out to 

 the shoreline or to a convenient wading depth. The location of the top 

 of a bluff or dune should be noted in all cases (Fig. 3). 



An optimum surveillance program could be downgraded to a minimum 

 program after 2 years if analysis of the survey data indicates that 

 extensive survey coverage is not warranted. Programs can be developed 

 on an individual basis anywhere between the minimum and the optimum, 

 e.g., the program could be weekly surveys using the Jacob's Staff Method 

 (Emery, 1961; and Urban and Galvin, 1969) or thrice-yearly surveys using 

 standard survey methods (Allen, 1931; Ruby, Lommel, and Todd, 1950; and 

 Breed, Hosmer, and Bone, 1958). Typical survey schemes for minimum and 

 optimum survey programs for three structure types are shown in Figures 

 4 through 9. 



III. MONITORING SHORE PROTECTION STRUCTURES 



A program to monitor shore protection structures should continue for 

 at least 3 years, providing the structure does not fail in the meantime. 

 If one of the purposes of the program is to determine the economic or 

 effective life of the structure, it generally will be necessary to 

 continue the monitoring longer than 3 years. A surveillance program 

 should, as a minimum, cover three cycles of the normal expected storm 

 segments of the year. For the Great Lakes this would include three 

 periods of late fall or early spring. In some cases longer periods of 

 monitoring will be required to ensure adequate measurements covering 

 periods of exposure to changing conditions. 



The following items of data collection should be included in the 

 surveillance program of the constructed works: 



a. Condition Surveys. Hydrographic and topographic surveys, 

 including dimensions and elevations of the shore protection structure 

 referenced to survey monuments, should be made immediately before and 



