30-1 



25- 



o ao- 



a. 



y 10- 



5- 



fUMlM. aO-83 



0.01 0.10 



1.00 



99.00 99.90 99.99 



10.00 25.00 50.00 75.00 90.00 



PERCENT GREATER THRN 



Figure 35. Distribution of surface water temperatures 

 for 1980 through 1983 



salts, soluble organic material, detritus, living' organisms, and inorganic 

 particles in the water. These dissolved and suspended materials change the 

 absorption and attentuation characteristics of the water, which vary daily and 

 throughout the year. 



94. The surface water visibility at the seaward end of the pier varies 

 in a manner similar to that of the temperature, with lows in January through 

 March and highs in June and July (Figure 36). Since the pattern of offshore 

 and onshore winds that produces major temperature differences also controls 

 the visibility, the warm surface water is usually clearer, while the cooler 

 bottom water contains large concentrations of suspended matter. 



95. Present data year. Daily water visibility values, measured at the 

 seaward end of the pier using a secci disc, reflect the wind-dominated pro- 

 cesses discussed above. Between May and August the visibility was occasion- 

 ally above 6 m, however, visibility was less than 2 m almost as often during 

 those months. Table 11 shows the monthly means for the year. 



96. 1983 versus prior years. Visibility during 1983 was similar to 

 prior years (Figure 37), although visibility was lower during January through 

 March and higher during May through July. 



62 



