48 
in Figures ll, 12, and 13. Considering the vast volume of water 
being sampled in these series and the very small numbers of samples 
that could be taken, it is certain that the profiles presented can- 
not be considered as an exact representation of the subsurface 
distribution of coliforms. Nevertheless, certain features of the 
profiles appear repeatedly in the various series and suggest two 
general conclusions. 
The first of these is that the highest subsurface counts occur 
along the general lines of surface movement of the sewage field. 
For example, Figure 11 shows two profiles obtained on the morning 
and afternoon of the same day. In the morning, the surface sewage 
field was moving upcoast, while the direction was reversed in the 
afternoon. It can be seen that the subsurface MPN reflect this 
altered movement. The Whites Point profile of November 3 and the 
Hyperion profile of January 12 show the same effect; high subsurface 
counts in the direction of surface movement, and essentially zero 
counts in the opposite direction. Such a pattern could result in 
at least two ways; either by assuming a uniform direction of move- 
ment of the water at all levels with subsurface as well as surface 
sewage flow, or else by assuming all sewage rises and flows at the 
surface only and subsurface coliforms represent sedimentation from 
the surface field. 
The repeated occurrence of tongues of high coliform cout 
extending downward from the surface provide evidence for sedi- 
mentation as the major factor determining subsurface coliform 
distribution. Such a tongue is clearly seen in the profiles in 
Figure 11, 12, and less prominently in Figure 13. It is quite 
clear in Figure 1h, which presents an average of all the profile 
