58 
tunately, because of the highly variable composition of the sewage 
effluents and the impossibility of analyzing a sufficient number 
of subsurface samples to give an exact quantitative picture, one 
cannot calculate whether the extra disappearance of coliforms 
above dilution is due entirely to the sedimentation process or 
whether death and other factors also play a significant role. 
In this connection, beach count data around the Hyperion outfall 
clearly indicate survival of coliforms for greater than 2); hours. 
For purposes of prediction, however, the causes of disappearance 
are secondary as long as the rate of disappearance can be estimated. 
The rate of disappearance for all causes in the vicinity of 
the Orange County Outfall is such that counts of more than 10 coli- 
forms per ml should not occur at distances of greater than six 
hours travel from the outfall. The surface distribution of coli- 
forms at Orange County and the observed rate of travel of the dye 
patches, as well as other data, indicate that currents of 0.2 knot 
or less are typical for the area, giving a pollution boundary of 
10 coliforms per ml at roughly 6,000 feet from the outfall. Since 
the dominant direction of sewage flow observed in this area has in 
general been parallel to the beach rather than towards the beach, 
little pollution would be predicted for the beaches in the vicinity 
of the Orange County outfall and what does occur would be expected 
within roughly a mile on either side. Actually, the beach count 
data available do not bear out these predictions. The possible 
reasons for this discrepancy will be discussed in the following 
section. 
If the rate of disappearance of coliforms in the Orange County 
area also held for the proposed outfall in Santa Monica Bay, then 
