| VISUALS |
OUTLINE |
| Display
Title and Byline |
"Sterilization of a Stream:
Rainbow Creek"
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| Map
of watershed with stream highlighted |
INTRODUCE
THE STREAM
- Location
- watershed - city- where does it flow?
- Influential
land use(s)
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| Photos
taken at each site |
- Monitoring
site locations
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| Graph
with fecal coliform data on both sites for current year |
PROBLEM
- Our
data + QC lab data detected zero fecal coliform bacteria at our
downstream site during spring sampling
- When
high, fecal coliform serve as an indicator of human
contamination in the stream
- We
contacted several local agency scientists who were concerned
about their absence
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| Graph
of historical fecal coliform data |
RESULTS
- The
average fecal coliform counts for both of our sites during spring sampling over the past several years is around 400
CFU/100 mL.
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| Graph
of chloride data |
- Our
chloride levels were much higher than in past sampling periods.
-
Spring sampling chloride averages for both sites during the past several years have been on the order of 8 mg
Cl-/L.
-
This spring's chloride for our downstream site was 24 mg
Cl-/L; substantially higher than the average of 8 mg/L from past sampling periods and the 6 mg/L we detected at the upstream site this spring.
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| Graph
of stream flow data |
- Because
large fluctuations in stream flow between sampling periods might
have had an impact on chloride measurements, we also looked at stream flow.
But flow has remained fairly consistent for each spring sampling
event over the last several years.
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| |
CONCLUSIONS
- Some
source of chloride has been introduced in the mile-long stretch
of Rainbow Creek between our upstream and downstream sites.
- The
elevated chloride levels in the stream could be responsible for
the absence of fecal coliform bacteria.
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| Typical
chloride levels for possible sources, including drinking water,
swimming pools, hot tubs |
- Suburban
development is the dominant land use within the watershed,
therefore an input of municipal drinking water is one possible
source of contamination.
- Swimming
pools are a more likely source because their chloride
concentrations are much higher than drinking water.
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| Display
recommendations in TEXT |
RECOMMENDATIONS
- Agency
scientists should further investigate the absence of bacteria
and the source of chloride in Rainbow creek to confirm that they
are related.
- There
needs to be more education on watershed systems to create
greater public awareness of the impacts we have on streams.
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