DATA 



During four extensive observation periods, turbidity 

 and temperature data were taken at 30-minute intervals. 

 The first period was about 10 hours long, and the other three 

 were from 26 to 29 hours long. 



TURBIDITY STRUCTURE --TIME SERIES 



From each turbidity run, the per cent transparency was 

 scaled from the continuous trace every 2^ feet from surface 

 to bottom. These readings were plotted on charts and 

 isolines were constructed. Thus the plot represents changes 

 in the vertical distribution of turbidity with time. Figures 

 6, 7, 8, and 9 show these plots, with the numbers on the 

 isolines referring to per cent transparency per half-meter 

 (e.g., 20-per cent light transmission signifies very turbid 

 water, 80-per cent very clear, etc.). The contours are in 

 10-per cent intervals. From the examples of data separately 

 discussed below, it will be evident that the turbidity varies 

 greatly with depth and time, and that sweeping changes take 

 place rapidly, completely altering the existing pattern. 



14 July 196 (fig. 6) 



This short series of turbidity measurements depicted 

 a condition in which the near-surface layer had a high tur- 

 bidity. The most turbid water occurred at high tide or 

 shortly after high tide, with less than 20-per cent light 

 transmission. At 1800, a mid-depth layer was clearly 

 discernible with maximum turbidity between 8 and 18 feet. 

 The clearest water, which occurred at the greatest depth 

 (about 50 feet), had a transparency between 6 and 70 per 

 cent as great as that of distilled water. It should be pointed 

 out that on this day the turbidity was greater than usual 

 throughout the water column. 



19-20 July 1960 (fig. 7) 



This depth-time series of turbidity measurements lasted 

 for 26 hours. During this period the water column was clearer 

 than on 14 July 1960. At the beginning of the series the water 

 had a nearly uniform turbidity from surface to bottom. Around 

 1700, however, clearer water (78-per cent transparency) was 

 introduced near the surface and, to a lesser extent, at greater 

 depths. This change occurred just before a high tide, in 



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