2. LEO Data . 



Wave and beach data from sites at Ludington, Muskegon, and Warren 

 Dunes (Fig. 1) are given in Tables 1, 2, and 3. The data are systemati- 

 cally collected as part of the CERC Littoral Environment Observation 

 (LEO) program (Berg, 1968). The Lake Michigan observations, made by 

 State park rangers, are a joint effort by CERC, the U.S. Army Engineer 

 District, Detroit and the State of Michigan Department of National 

 Resources. Data from the ice-free months of 1972 have been tabulated by 

 Bruno and Hiipakka (1973) . Daily observations consist of visual 

 estimates of height, period, direction, and type of breaking waves, width 

 of the surf zone, direction and windspeed as measured by a Dwyer wind 

 meter, direction and rate of longshore current as indicated by a dye 

 patch, and a measure of foreshore slope with a level or an inclinometer. 

 Surface sediment samples are collected in the swash zone at monthly 

 intervals. 



Breaker height is lowest in summer and highest in fall which agrees 

 with the wind data in Figure 2. Longshore current direction, dominant ly 

 to the south at Warren Dunes and mixed at the other two sites, is 

 consistent with the open water fetches of these sites (Fig. 1). 



3. Lake Level. 



Precipitation and runoff changes cause both long-term and annual 

 fluctuations in the level of Lakes Michigan and Huron which are hydrolo- 

 gically a single unit. Other factors affecting the lake level are the 

 rate of flow from Lake Superior and the outflow to Lake Erie. However, 

 the dominant factor is precipitation. A plot of lake level and precipi- 

 tation from 1900 to 1972 (Seibel , 1972), shows a high degree of correla- 

 tion between the two curves. 



Long-term changes may have a range of several feet. Average lake 

 levels for 1960-72, as measured by the Huron-Michigan "master" gage at 

 Harbor Beach, Michigan, are shown in Figure 3. Lowest recorded lake 

 levels in the past 112 years occurred in March 1964, and were preceded 

 by a period of high levels in the early 1950's. 



Annual fluctuations are usually about 1 foot and predictable. Minimum 

 annual level is generally in February and March and the maximum in summer 

 (Fig. 4), reflecting both precipitation and runoff. Winter runoff is 

 negligible due to low temperatures which keep the moisture in the form 

 of snow and ice. 



4. Ice Formation . 



Although Lake Michigan does not freeze over completely, ice usually 

 forms along the shores of the study area during a normal winter. Freezeup 

 begins in late December in the northern part of the lake and ice accumulates 

 in a southerly direction along the shorelines. Maximum ice cover occurs 



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