rate for points in Berrien County between 1830 and 1956 was 0.60 meter per 

 year, which was higher than the overall lake average. None of his points 

 within the five study reaches. 



were 



A report on a proposed beach nourishment project for St. Joseph, Michigan, 

 included an analysis of the bluff recession within the five reaches and a study 

 of the bluff, beach, and nearshore sediment characteristics (Beach Erosion 

 Board, 1956) . The report concluded that only 20 to 40 percent of the bluff 

 material was suitable beach-fill material. A peak bluff recession rate of 

 3.21 meters per year was found in reach D for the period 1830 to 1872. The 

 average rate between 1830 and 1954 for all five reaches was only 0.50 meter 

 per year, a value similar to but lower than that derived by Powers (1958) for 

 about the same period. 



Seibel (1972) examined the bluff recession since 1938 at four Lake Michigan 

 and two Lake Huron locations, and the relationship between lake level and pre- 

 cipitation, and between lake level, storm frequency, and bluff recession. He 

 determined linear relationships between average lake level and bluff recession 

 for each of the six sites. 



One of the six sites was at Bridgeman in Berrien County where measurements 

 were made at 2 7 profile lines, including six within the five study reaches. 

 Data were obtained from aerial photos dated 1938, 1950, 1955, 1960, 1967, 1970, 

 and 1972. Average bluff recession rate was 1.2 meters per year between 1938 

 and 1970, although individual profiles retreated as much as 9 meters per year. 



In addition to the long-term rates, Seibel also computed the rate of bluff 

 recession between 1970 and 1972 at 14 points near the powerplant from the same 

 photos used in this study. An average rate of 2.8 meters per year was deter- 

 mined, an increase over the preceding period (1967 to 1970). Most of the in- 

 crease occurred south of the powerplant. Seibel indicates that much of the 

 increase can be explained by the increase in average lake level. An important 

 conclusion reached by Fox and Davis (1970), Seibel (1972), and Johnson and 

 Hiipakka (1976) was the significance of infrequent, severe storms in control- 

 ling the rate and amount of bluff recession. 



Because the problem of lakeshore property insurance is directly linked to 

 the recession rate in an area, there is considerable interest in predicting 

 future bluff lines for at least the mortgage life of a structure (generally 

 30 years). Jannereth (1974) described the State of Michigan's effort to pre- 

 dict bluff lines from 1938 and 1974 photos. The results (Michigan Department 

 of Natural Resources, 1975) indicate that except for a small part of reach E, 

 all five reaches are in high risk erosion areas. A bluff recession rate of 

 1.1 meters per year was determined for reaches A, B, and C, and a rate of 0.5 

 meter per year for reaches D and E. These values were used to compute a mini- 

 mxom setback line equal to 30 times the recession rate. A recommended setback 

 line was also determined by adding another 9 meters to the minimum setback 

 value. 



The Michigan Department of Natural Resources (1974) participated with the 

 U.S. Army, Corps of Engineers in monitoring the effect of the temporary harbor 

 at the powerplant. They found similar rates of recession north and south of 

 the plant at areas with similar bluff topography for the period July 1970 to 



51 



