15 



tration with depth; ammonia essentially concentrated in the 

 surface water and decreasing to zero at depth. Silicate, 

 phosphate, and nitrate all show patchy areas of low concen- 

 tration in the intermediate layer. 



Whites Point Outfall 



The vertical and horizontal distribution of nutrients in 

 the water surrounding the Los Angeles County outfall at Whites 

 Point differ significantly from the other two areas. The 

 difference appears to be due to (1) a different type of treat- 

 ment, (2) the depth of discharge, and (3) the mechanical 

 method of discharge. The nutrient concentrations are lower in 

 any given mass of water, spread through a greater thickness 

 of water, and extend for greater distances (Figure 6). For 

 example, low and high oxygen concentrations are generally 

 less extreme than at the other two outfalls, the values 

 remaining in a median range throughout the entire water column 

 and for distances as much as six miles from the outfall. 



Ammonia values decrease with depth, as at Orange County 

 and Hyperion, but no areas of normal concentration occur 

 within 11,000 feet of the outfall, and reasonably high ammonia 

 has been measured near Point Vicente, The same is true with 

 silicate and phosphate, although the silicate concentrations 

 are greater on the bottom than at the surface and there is an 

 intermediate layer of lower values. 



From the nutrient averages (Figure 7) a variable decrease 

 in ammonia with depth is noted, as well as pockets of concen- 

 tration in the bottom layer which is otherwise low. The 



