P2 
unchlorinated sewage. It was recognized that the disappearance 
would be due to several factors and that dilution, mortality, 
and sedimentation were probably the most important, Dilution 
could be measured to roughly one part in 400 by chlorinity deter- 
minations, but experiments were not designed to distinguish be- 
tween other causes of disappearance. 
Twelve cruises were conducted between September 1955 and 
February 1956. Of the cruises, ten were to determine the distri- 
bution of coliforms in time and space and two were to reinves- 
tigate the bottom coliform field in Santa Monica Bay. 
The sea around the Orange County outfall was chosen as the 
principal area of investigation because the discharge was primary 
unchlorinated effluent and the oceanography was similar to that 
in the shallow areas of Santa Monica Bay. The waters surrounding 
the Los Angeles County outfall at Whites Point were investigated 
to check results obtained at Orange County and to note the distri- 
bution of coliforms as affected by a deeper point of discharge 
and better mechanical diffusion. In both areas, the occurrence 
of bottom coliforms was determined, but the extent of the fields 
was not investigated. 
Although the volume of sewage discharging from each of the 
outfalls differs, it was believed that the processes relating 
to the disappearance of the bacteria from the waters would be 
the same. The results have shown this to be more or less true. 
However, the rates of disappearance were different around the 
three outfalls and from the data obtained during a cooperative 
cruise with the Los Angeles Sanitation District at the Hyperion 
outfall, it seems possible that the physical and chemical dif- 
