3h 
Similar computations were made on the basis of chlorinity 
determinations on dye patch samples taken subsequent to zero time. 
The data are presented in Figure }}. The upper line represents the 
average calculated counts and the lower line the average observed 
counts for all the Orange County data. It can be seen that the 
average observed counts at all times after zero time are con-=- 
siderably less than the calculated counts; differing by one 
magnitude at about two hours, and 24 magnitudes at six hours. 
These data show that other important factors besides dilution 
are contributing to coliform disappearance. 
Unfortunately, comparable information is not available for 
the initial coliform population and chlorinity of the Hyperion 
and Whites Point effluents. Data provided by the Hyperion and 
Whites Point personnel indicate an average chlorinity for these 
two effluents of about 0.26 and 1.0 o/oo respectively and our 
own data show an average normal chlorinity for the surface waters 
of these areas of about 18.55 o/oo. Using these values, a dilution 
of 1/17 was calculated for the boil sample in the successful 
Hyperion dye patch experiment. Initial dilutions of up to 1/0 
have been found for other samples taken from the Hyperion boil. 
As with the Orange County experiments, the observed counts at 
Hyperion were less than the calculated counts at all times after 
the zero point value and the difference at the end of six hours 
was of the order of two magnitudes (Fig. ). 
The initial dilution of the sewage in the zero time sample 
at Whites Point was higher than at the other two outfalls, being 
1/8. This might have been expected since the Whites Point out- 
fall is the only one of the three with a large diffuser. On 
