57 
The same is probably true around the Hyperion outfall since the 
data now available on the chlorinated effluent routinely discharged 
indicate large coliform populations may survive the chlorination. 
It is reassuring, however, that none of the 70 samples tested were 
at all suspicious of enteric pathogens. 
Fate of Coliforms 
Considering only the data presented so far, the interpretation 
of the results appears straightforward. It has been shown at all 
three outfalls that the effect of dilution on reducing the coliform 
count is very slow after the initial mixing of the effluent with 
sea water in the immediate vicinity of the outfalls. Initial 
dilutions of the sewage as low as one part in 35 at the surface 
have been calculated from chlorinity data at Whites Point where 
diffusers are used, and indications are that most of the sewage 
reaches the surface without appreciably greater mixing. It appears 
safe to conclude that a similar situation would exist at the 
proposed outfall, that the entire volume of water in the bay would 
not be available for mixing, and that dilution by itself would 
not reduce the coliform population to a point where State standards 
are met. 
It has been demonstrated that at all three outfalls, factors 
other than dilution cause a significant disappearance of coliforms 
from the surface waters. One of these factors has been clearly 
shown to be the process of sedimentation. It is our qualitative 
impression that no other factors beside dilution and sedimentation 
are of significance in the disappearance of coliforms over the 
initial six hour period after discharge of the effluent. Unfor- 
