47 



of the increased reproductive rate by the effluent is noticeable 

 as much as 12,000 feet or more from the outfall. 



Increased numbers of phytoplankton in the water obviously 

 increases turbidity, and consequently decreases transparency. 

 This is due not only to the discoloration of the water as a 

 result of increased numbers, but also to the mere addition of 

 great quantities of particulate matter; in this case, the organ- 

 isms. Although turbidity may be increased by the addition of 

 dissolved compounds in the water, the major cause in nearshore 

 areas is from the particles of silt, clay, and sand, or any 

 other solid debris which can be kept in suspension by turbu- 

 lence. In the case of plankton, only exceptionally minor 

 turbulence is necessary, for even in calm waters floating 

 mechanisms inherent to the organisms will keep them in sus- 

 pension for indefinite periods of time. 



The question then arises as to whether the occurrence of 

 plankton in waters enriched by the effluent can be directly 

 attributed to the sewer outfall, or is it a natural phenomenon 

 which can therefore be disregarded when measuring transparency 

 in any monitoring program? Perhaps in order to apply the con- 

 dition to the water quality standards established on May 2, 

 1956, by the State Water Pollution Control Board, a legal 

 definition of what constitutes sewage origin is necessary. 

 However, there is no doubt that under certain conditions, the 

 waters within 2 to 3 miles of these three sewer outfalls con- 

 tain higher numbers of plankton than the surrounding waters, 

 and that the greater numbers are due to the enrichment of the 

 local ocean by the effluent. 



