46 



trations. Although there are variations that may be daily, 

 weekly, or annual, these variations are minor in comparison 

 with the great quantities of nutrients in the waters immedi- 

 ately surrounding the discharge point. In all cases, when 

 numbers of plankton were high in the vicinity of a sewer boil, 

 the numbers were also reasonably high in the waters which were 

 not affected by the sewage discharge. On days when there 

 were no plankton, or at least relatively few plankton, in the 

 surroimding waters, there were also few plankton in the 

 immediate vicinity of the discharge point. At times when dis- 

 colored water was noted in Santa Monica Bay or surrounding 

 Orange County outfall area, discolored water did not appear 

 to originate in the waters enriched by the sewage discharge. 

 On the other hand, discolored water frequently appeared many 

 miles away and gradually spread to the enriched waters. Once 

 these waters nearshore gained high numbers of plankton, the 

 discoloration increased markedly, and could be more or less 

 related to, visually at least, the flow of the sewage field. 



It is reasonable to assume, therefore, that the increase 

 of nutrients in nearshore waters from the discharge of sewage 

 does not in itself initiate a plankton bloom. The initiation 

 of a bloom must be due to some other condition, a condition 

 which is undoubtedly a natural characteristic of the near- 

 shore waters. Once rapid plankton reproduction is initiated 

 in continental shelf waters, the nutrients contributed by the 

 effluent markedly increase the r.eproductive rate, and thus 

 the numbers of plankton. Depending on the discharge volume, 

 ocean currents, and other oceanographic conditions, the effect 



