Fraser River Studies Lab
Biology 285
Fecal
Coliform Testing
Introduction
The Fraser will receive a certain amount of fecal material naturally
due to animal waste being deposited directly or by rainfall washing
waste material into the river. However, in a natural setting, vegetation,
which will stabilize top soil, holds water and acts as a filter
as it slowly releases it back into the river. The vegetation will
use the soluble organic waste moving with the water as it filters
past root systems. Sand and soil particles will also gather solid
waste particles as water flows through the soil. On our trip down
the Fraser River we passed through many natural areas, but we also
passed through many disturbed areas. Areas with large human populations
being the most disturbed (with regards to top soil and ground vegetation).
It is in these areas that one would expect to find evidence, in
the form of e-coli, in the river water. Not necessarily due to
the pumping of treated sewage into the river (as the sewage is
chlorinated in the contact tank followed by the addition of sulfur
dioxide to remove the chlorine) but due to the presence of storm
drains and pavement, which does not allow for any natural filtration
of waste, combined with a larger population of certain animals
that due well in urban settings and the presence of house hold
pets. This run-off will most likely contain an amount of waste
over and above that of an undisturbed site. Population growth may
also surpass the planned capacity of sewage treatment plants and
they may not be able to keep up with the amount of sewage entering
the plant.
It should be noted that common e-coli is not a harmful bacterium
(there are some harmful strains, however, such as ‘hamburger
disease’), and is present in human digestive tracts. Its
presence in an area is a strong indicator that sewage, which will
almost certainly contain pathogens, is being released with it.
It is also a cheap and relatively easy substance to test for.
The federal government sets standards that must be met or beaten
by the provincial government for e-coli counts. BC has set it’s
own standard; according to the BC Safe Drinking Water Act, total
allowable e-coli is zero. We collected Fraser River water samples
above and below two populated areas’ sewage outflows. The
first Quesnel, and second Hope. In doing so we wanted to discover
if any raw sewage was entering the river. I suspected we would
not detect any e-coli from the upstream test sites, but would get
small amounts from downstream, depending on recent rainfall in
the area.
Procedure
After rinsing out our sample jars three times with water
from the test location, approximately five kilometers upstream
from
Quesnel we obtained five first station samples at 1:45 p.m. on
July 4,
1997. This area had vegetative cover along and well back
from the riparian zone but was a disturbed area and had a human
population. Our five second station samples were taken approximately
two
kilometers down stream from the Quesnel sewage outflow at
4:30
p.m. the same day. This area also had riparian vegetative
cover but was a disturbed area and was also downstream from an
urban
setting.
We also added to our experiment at approximately 8:00 p.m. the
same evening by taking a sample of water from one of our drinking
water storage containers. We did this because people were not following
proper procedure and transferring water from this container into
a second one with a pouring spout. They were dipping their water
bottles directly into the container and touching the water with
their hands.
Using a Millipore filtration apparatus, we poured 100 ml of sample
water into the funnel. A .45 micron filter paper was used between
the funnel and the and the suction portion of the apparatus (see
diagram). This filter was then placed in a petris dish and a medium
specific to the growth of e-coli colonies was added. The petris
dish was then placed in an incubator (we used a styrofoam container
for this, hoping to maintain a temperature conducive to e-coli
growth, 45 degrees celcius).
We followed the same procedure in collecting samples from above
and below Hope’s sewage outflow on July 13, 1997. Areas both
above and below the outflow were in human disturbed areas, but
there was vegetation located on the riparian zones.
It should be noted that in both our study sites the areas were
without rainfall for at least a couple of days prior to our tests.
This is important as rainfall drainage collects waste and washes
it down storm sewers which can then go directly into the river
or be diverted through treatment plants, which may push them past
capacity, depending on the time of day.
Results
On July 6, 1997, our results for the first station tests (plus
the drinking water) samples were observed. All river water
samples turned up zero e-coli colonies per 100 ml sample. The drinking
water sample resulted in nine e-coli colonies per 100 ml sample.
On July 18, 1997, our results for the second station tests again
turned up zero e-coli colonies per 100 ml of sample water.
Discussion
Our results have shown that during test times, both Quesnel’s
and Hope’s sewage outflows met both federal and provincial
standards. I could not come to this conclusion, however, if we
had not taken the samples of our drinking water. The reasoning
behind this statement is that a possible flaw in our procedure
was the use of a styrofoam box for an incubator to maintain a 45
degree celcius temperature. We did not measure the temperature
in the Styrofoam box and could not be sure it was conducive to
e-coli growth. The fact that our drinking water sample did grow
nine e-coli colonies demonstrates that the temperature in the styrofoam
box was in fact conducive to e-coli growth.
Unfortunately, we did not take a control sample of drinking water
from a water barrel that had not been dipped into. Therefore, no
conclusions can be drawn as to whether the e-coli contamination
came from the dippers hands, or whether the source was contaminated.
However, since the contamination was discovered, and the water
bleached and then boiled before use and having no one fall ill
after consumption, evidence strongly suggests the hands of the
dippers (whom had at this point been five days into the raft trip)
being the point of contamination.
Another factor involving Quesnel’s and Hope’s zero
e-coli count is the lack of rain fall prior to our testing. The
Fraser river’s mean flow is 3,972 cubic meters per second
(Obee, 1993). This rate is well capable of moving any contamination
far away from our test site. In order to properly evaluate these
towns sewage outflows and storm drain runoff for sewage, the water
sample would have to be taken during peak sewage treatment flows
and during or immediately following rain fall.
Acknowledgments
To all those Fraser River Studies folks who dipped their hands
and water bottles into the drinking water, they did in fact, unwittingly,
create a control sample allowing us to conclude positively if our
samples were capable of growing e-coli colonies. Thank-you.
Also to Dean for explaining the procedures to us.
Literature Cited
Obee, Bruce. “Hell-Bent on the Fraser. Exploring the middle
reaches of BC’s
mightiest river.” Beautiful BC, May 1993, pp. 34.
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