580.0 



579.0 - 



■^ 578.0- 



577.0 



576.0 - 



575.0 



60 61 



Figure 3. 



64 65 66 

 Years 



Mean annual elevations at Harbor Beach, Michigan, 

 1960 to 1972 (feet above mean water level at 

 Father Point, Quebec). 



17 



