21 
report, p. 66) that showed no dye toxicity. These experiments 
were run in the absence of direct sunlight and the possibility 
existed that a toxicity due to a photodynamic effect could 
occur. Consequently, toxicity of fluorescein was retested 
taking this factor into consideration, but no photodynamic 
effect could be shown. The results of one experiment are 
presented in Table III. 
Subsurface Distribution of Coliforms 
Thirty-four stations were occupied at which a series of 
one surface and three subsurface samples were collected and 
analyzed for coliforms and chlorinities. The profile con- 
structed from one series of stations is shown in Figure 7. 
As with the previous data of this nature discussed in the 
May 1 report, the highest subsurface counts occurred along the 
general lines of movement of the surface effluent field. The 
tongues of high coliform content extending down from the sur- 
face that were so prominent in the Orange County data did not 
show up as strongly in the data taken in Santa Monica Bay. 
There were individual high subsurface counts in areas of normal 
chlorinity that did suggest sedimentation as was discussed 
above in connection with the subsurface radioactivity measure- 
ments. In general, the evidence for sedimentation as an 
important factor for coliform disappearance was not as strong 
in the Santa Monica Bay area as in the other areas studied. 
This could relate to the lack of steady state discharge of 
unchlorinated effluent into Santa Monica Bay. Since unchlor- 
inated sewage was only released for a few hours on the days 
