263 



sewage field dilutions of ls300 are more easily determined 

 from salinity data than from temperature because the tem- 

 perature of the effluent is nearly that of the surface 

 layers in the bay. The nutrient salts, in concentrations 

 much greater than that normally found in shelf water, were 

 confined to an area within a few thousand feet of the 

 Hyperion outfall. The small pockets of high concentration 

 were distributed erratically throughout the effluent field. 

 Variations in nutrient concentrations between the Orange 

 County, Whites Point, and Hyperion outfalls are believed 

 to result from differences in the character of the effluent 

 discharged. Oxygen concentrations in the vicinity of the 

 outfall indicate no serious areas of oxygen depletion during 

 the time of the survey. 



Transparency 



The transparency of the water in Santa Monica Bay is 

 controlled partly by pljinkton, but primarily by the amount 

 of detrital debris contributed from the mountains, hills, and 

 low coastal plains bordering the bay. Rocks in the mountains 

 and hills are mainly fine-grained loosely consolidated shales 

 and sandstones so that material eroded from them and carried 

 to the bay during infrequent rains is usually in the clay 

 to fine sand particle range. The resultant turbidity in 

 the waters within a mile of shore is normally high and the 

 transparency subsequently is lower than desirable from an 

 aesthetic point of view. During the summer and fall a 

 relatively high turbidity is maintained by wave action. The 



