24, 
COLIFORM BACTERIA DISTRIBUTION 
Field Procedures 
Dye Patch Experiments 
Dye patch experiments were used to obtain a direct measure 
of the rate of disappearance of coliform organisms in the sewage 
fields. Approximately one pound of fluorescein dissolved in about 
a gallon of sea water was introduced into the sewage field at the 
edge of the "boil" above the outfall being investigated. After 
allowing a few minutes for the dye to become distributed, the zero 
time sample was taken from within the dyed area. The dyed patch 
was then followed for three to six hours and samples were removed 
at intervals, These samples were analyzed for their chlorinity and 
coliform content. 
The dye patches behaved differently during various experiments. 
In some instances the dyed area remained compact and of limited 
extent; in others, the dye spread out over a large area, usually 
in ribbon-like form. The dye was renewed as required to enable 
continuous observation of that part of the sewage field originally 
marked, In some instances this required about one pound of dye per 
hour, in others only the initial pound was required for the four 
to six hour pericd. When samples were removed or dye added an 
effort was made to pick the most concentrated area of the dye 
patch. On two occasions colorimetric determinations on samples 
removed from the dye patches were compared against a standard 
curve set up with measured amounts of fluorescein, and the 
results indicated that the concentration of dye in the patch did 
not exceed one part in 10,000. 
