Results and Discussion

1
A Spatial Analysis of the influence of a rain
event on Fecal Coliform Concentrations and
Turbidity in a small N.E. Ohio Freshwater
Stream Ian Santino, Glennon Beresin, Andrew
Fenster Oberlin College, Systems Ecology 2008

• Background
• Plum Creek is a tributary of the Black
  River watershed which flows directly into Lake
  Erie. The creek passes through agricultural,
  forested, and urban landscapes and thus makes it
  similar to many other streams In the NE Ohio
  bioregion. Therefore, Plum Creek is an ideal
  place for studying the effect of land use on
  measures of water quality including nutrients,
  turbidity, and bacteria concentrations. Fecal
  coliforms (FC) are naturally occurring bacteria
  that help break down food in the guts of most
  mammals. Thus, they serve as an indicator for
  fecal contamination and are associated with
  the presence of pathogens in water, such as
  Hepatitis A.
• The health of Plum Creek has been a
  particular environmental concern over the past
  several decades (USGS 1977). Two years ago,
  Oberlin began a regular water quality
  monitoring program in Plum Creek. However, the
  focus of data collection and analysis in the past
  has been on how nutrient concentrations change
  over time, at different locations along the
  stream and following storm events (e.g Feeser
  and Soong, 2006, Cummings et al.,2006). No
  studies have yet focused on FC dynamics in
  relation to spatial variability and weather
  conditions. The goal of our study was to analyze
  FC at high spatial resolution during autumn
  along the four miles of Plum Creek that run
  through Oberlin city limits on a low flow day and
  a high flow day.

• Methods
• We chose our sample sites to be consistent with
  sampling in a previous study of water quality
  of Plum Creek (Feeser and Soong, 2006). Based on
  extenuating circumstances, only eleven sample
  sites are included in our study (See diagram of
  stream pictured below).
• The locations of the sample sites are within
  agricultural, forested, and urban/residential
  landscapes and all have easy road access, except
  the location within the arboretum.
• We sampled during a low flow period on 11/5/08
  and a high flow period, after 12 hours of rain,
  on 11/15/08. We used standard methods and
  procedures to collect stream water (Basic
  Laboratory Procedures for Wastewater Examination,
  2002), conduct FC analysis (Basic Laboratory
  Procedures for Wastewater Examination, 2002), and
  measure turbidity (R. Johnson et al. 2002).

Turbidity vs. Fecal Coliform
14
10
High-flow
Average
R20.22
FC (1000s of colonies)
R20.61
6
2
Low-flow
R20.08
0
0
20
40
60
80
100
120
140
160
Turbidity (FTU)

• When data from low and high flow periods are
  analyzed as a unit, a moderately strong
  positive trend is evident between turbidity and
  FC (in orange), indicating that turbidity induced
  by storm events generally delivers FC to the
  stream.
• However, if data are analyzed for either of
  the individual days in isolation, no clear
  trends are evident between FC and turbidity
  (blue low flow, purple high flow). We
  interpret this to mean that turbidity is
  indirectly related to increased FC in the water.
  It seems more likely that the storm event both
  increased turbidity due to an increase in flow
  and increased runoff carrying FC into the
  creek, producing a positive correlation.

• Results and Discussion

Mechanistic hypotheses 1. We expected an
increase in FC during a rain event due to
increased runoff carrying FC delivered from the
land. 2. In addition, we expected a positive
correlation between turbidity and FC due to
increased sediment disturbance in the water. 3.
Finally, we expected stretches of the Plum Creek
through urban areas to have the highest FC levels
because of increased impermeable ground surfaces,
and prevalence of FC sources associated with use
by humans and animals.

• Conclusions and Future Research
• The temporal and spatial variability of FC
  concentrations in Plum Creek displayed in our
  data signifies that further testing needs to be
  done at this high resolution. We only captured
  the patterning during the course of two autumn
  days, instead of having a full year picture of
  the fluctuations.
• We also only captured the change between low flow
  and high flow, where a more complete
  understanding of how weather affects FC would
  call for sampling several times before, during
  and after the same weather event.
• Although we can see that the portions of the
  stream running through the more highly populated,
  urban landscapes had higher FC both during a high
  and low flow period, the mechanism for those high
  levels is unclear. We can only speculate that the
  FC is entering the stream in those locations and
  that the increase during a rain event brings in
  runoff from the surrounding areas. However, it is
  also possible that it is flowing downstream from
  a different location.

Literature Cited Cummings, J., Reed, T., and
Weinberger, K. December, 2004. The city of
Oberlins effect on the Plum Creek watershed
during a storm event variation in upstream and
downstream water quality during and after storm
water run-off as a function of urban land cover.
Oberlin College, Systems Ecology (ENVS
316). Feeser, J., Lauterbur, E., and Soong, J.
December, 2006. Nutrient concentrations along an
agricultural/urban stream during low flow and
post-storm periods as a function of varying
land-use and biological processing. Oberlin
College, Systems Ecology (ENVS 316). Johnson,
R., S. Holman and D. Holmquist. 2002. Water
quality with calculators. Vernier Software and
Technology. Basic Laboratory Procedures for
Wastewater Examination, Fourth Edition, Water
Environment Federation, 2002. U.S. Geological
Survey flow and water quality data for Plum Creek
for a 3 month period in 1977