16 
favorably with that in Santa Monica Bay and along the Orange 
County coast, indicating that the shelf water mass is more or 
less the same for the entire coast of the Los Angeles Basin. 
Salinity changes in the surface layers are probably due 
mainly to natural causes, although some effect of dilution must 
occur from the effluent discharge. Because of better mechanical 
diffusors on the Whites Point outfall than at Orange County or 
Hyperion, dilution of the sea water is noticeable only in the 
immediate area of the boil, and not at distances noted in the 
other areas. 
The principal reasons for the variations in the water 
characteristics near Whites Point are (1) the presence of the 
adjacent Palos Verdes Hills, and (2) the narrow continental 
shelf. During the rainy season the hills are a source of run- 
off which dilutes the nearshore surface water layers. The marked 
relief and steep slopes promote rapid delivery of rainfall by 
surface drainage and groundwater percolation. In comparison, 
the broad flat plains bordering the other outfalls act as 
reservoirs, tending to absorb the rainfall, or restricting the 
runoff to local channels, 
The narrow shelf allows the offshore currents to come relati- 
vely close to shore and introduce different water masses to the 
outfall area. Such an action does not occur over the broad shelves 
in Santa Monica Bay and along the Orange County coast. This would 
indicate that salinity variations would more naturally occur near 
Whites Point, whereas conditions around the other outfalls should 
be more stable because of the minor movements of in situ water 
masses, 
