31 OCTOBER 



TAWAS POINT 



10 OCTOBER 



BAY CITY 



10 OCTOBER 



31 OCTOBER 



HARBOR BEACH 



10 OCTOBER 



Figure 7. — Prevailing wind vectors for October 1956, 

 at Coast Guard Stations bordering Lake Huron. 



determining the procedure to be 

 followed in the interpretation 

 of effects of wind on water move- 

 ment. The direction of the wind 

 and direction of the movement of 

 a bottle were correlated over 

 periods of several weeks, regard- 

 less of the station for which 

 the track was used. On the other 

 hand, for study of short-term 

 movements, it is desirable to 

 use wind data from the station 

 closest to the path of drift. 

 It may be of some significance 

 that movements of bottles that 

 agree least with wind movements 

 were those dropped farthest from 

 any source of wind information. 



WATER MOVEMENTS OF 

 SAGINAW BAY 



General features of the Bay 



According to the Great Lakes 

 Pilot, 1956, "Saginaw Bay, the 

 largest indentation along the 

 west shore of Lake Huron, has a 

 width at its entrance between 

 Pointe aux Barques and Au Sable 

 Point of 26 miles, and from this 

 line southwesterly to its head 

 at the mouth of Saginaw River the 

 distance is 51 miles. Its mini- 

 mum width is 13 miles, between 

 Sand Point on the east and Point 

 Lookout on the west in the outer 

 portion of the bay; but, owing 

 to the very shallow bank extend- 

 ing from the easterly shore to 

 beyond the Charity Islands, and 

 to the shoal projecting from 

 Point Lookout, the deep channel 

 at this point of least width is 

 contracted to a width of about 

 1 3/4 miles. The water level in 

 Saginaw Bay is subject to sudden 

 changes due to the wind, a north- 

 east gale driving the water into 

 the bay so as to raise the level 

 at the mouth of Saginaw River 3 

 to 4 feet sometimes in less than 

 as many hours , while a southwest 

 wind lowers the level at times 

 sufficiently to cause large ves- 

 sels to ground in the channel." 



Of the several tributaries 



11 



