The Effect of Suspending the Bottom Material
at Bathing Beaches on the Fecal and Total
Coliform Densities of Bath Waters
WENDELL H. HOVEY, Instructor
N. BRUCE HANES, Professor
Civil Engineering Department
Tufts University
Medford, Massachusetts
INTRODUCTION
AND
LITERATURE REVIEW
The first assumed indicator of fecal pollution to gain wide acceptance was the
coliform group of bacteria. This group was defined as "all of the aerobic, and
facultative anaerobic, Gram-negative, nonspore-forming, rodshaped bacteria which
ferment lactose with gas formation within 48 hours at 35 C" (1). This group included
Escherichia coli, which was found by Escherich in 1885 to be a common inhabitant
of the intestinal tract of warm-blooded animals. Unfortunately the coliform group
has been found to include not only those bacteria associated with the intestines of
warm-blooded animals, but bacteria occurring naturally, and in great numbers, in
soils, plants, and insects (2, 3).
The ubiquitous nature of the coliform bacteria led to the definition of other
groups of indicator organisms. The most recent, the fecal coliform group, is that
portion of the coliform group which is detected and measured by a test based on
lactose fermentation at 44.5 C (4). Research investigations indicate that this group
has a good positive correlation with warm-blooded animal fecal contamination (4).
Fish, vegetation, and soils in remote areas away from fecal contamination have been
shown to rarely contain any fecal coliforms (2, 4).
Criteria for Bathing Water Quality
Stevenson (5) stated that there were significant increases in the incidence of
swimmer illness when the total coliform density exceeded 2,300 per 100 ml in the
water at Lake Michigan beaches and 2,700 per 100 ml along a reach of the Ohio
River. Later work on the same stretch of the Ohio River showed that fecal coliforms
represented 18 percent of the total coliforms and was taken to indicate that
detectable health effects might occur at fecal coliform levels of about 400 per 100 ml
(6, 7). Other studies showed that a bathing water with 400 fecal coliforms per 100
ml could be expected to have 0.02 vims particles per 100 ml (7).
On the basis of these epidemiological studies on bathing water quality and
health, the Committee on Water Quality Criteria recommended the following (7):
401