24 
of the trips taken, most of the solids in the bay at these 
times were from chlorinated effluents and would be expected to 
contribute little or nothing to the subsurface coliform counts. 
Bureau of Sanitation Results 
Previous to the May 1 report, there had been an extensive 
discussion of the apparent discrepancies between the disappearance 
rates we observed using the dye patch technique, and the rates 
found by the Bureau of Sanitation using a different type of 
field procedure. This problem was discussed in the May 1 
report (p. 64-71) and it was concluded that the differences 
in results were independent of field or laboratory technique 
and related only to differences in the nature of the effluents 
being studied. Most of our work was done on primary effluent 
from Orange County and most of theirs on secondary treatment 
effluent from Hyperion. This conclusion has been substantiated 
by the more recent data collected by them and us during periods: 
of discharge of primary effluent from Hyperion. Without 
detailing the Bureau of Sanitation data, which are summarized 
in their “Summary Report, Oceanographic Investigation of 
Santa Monica Bay, July 1956", it is sufficient to point out 
that they show an average 90% reduction of coliform rate of 
3.4 hours for the first nine hours after discharge as compared 
to our average figure of 3 hours for the first 6 to 10 hours 
after discharge. Further, on a single trip to the Orange 
County area they found a disappearance rate identical to that 
given in the May 1 report. 
