Variability of Escherichia coliVariability of Escherichia coli(E. coli) concentrations in ( )
Whiteoak Watershed, Houston TexasHouston, Texas
Prepared by
Karina Navarro
University of Houston, TXAugust 6, 2008
Variability in Whiteoak Bayou WatershedVariability in Whiteoak Bayou WatershedBackgroundWatershed LocationWatershed LocationSampling and Analysis MethodsResults
Variability between sitesyTemperature effectsRain effects
Possible Explanations of Variability
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BackgroundBackground
E. coli is used as an indicator bacteriaTh TCEQ t t d d f th i ll blThe TCEQ sets standards for the maximum allowable levels of E. coliAll surface waters in Texas are supposed to meet theAll surface waters in Texas are supposed to meet the standards for contact recreationThe streams in Whiteoak Bayou Watershed fail to
t th t d dmeet these standards
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Location of Whiteoak Watershed
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Sample Collection
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Sample Collection
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Laboratory Processingy g
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Laboratory AnalysisLaboratory Analysis
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Laboratory AnalysisLaboratory Analysis
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Daily Fecal Coliform Concentrations
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Daily E. coli Concentrations
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Potential causes of variabilityy
Very localized conditionsVery localized conditions
T tTemperature
Rain
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Weekly E. coli Concentrations
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Geometric mean of E. coli concentrations at each site
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Comparing E. coli concentrations at different sites
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Temperature
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Rain
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Number of Days After Rain Event
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Amount of Rainfall
R2 = 136R2 =.136
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What Causes Such Variation?
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Location Effects
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Temperature EffectsTemperature Effects
25°C <Water Temperature < 35°C
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Rain Effects
Wash-Off Effect
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Take a lot of samples
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ReferencesReferencesOffice of Homeland Security & Emergency Management. Historical Data. 1
August 2008. 2 August 2008 <http://www.hcoem.org/HistoricalData.aspx>.Tchobanoglous, George, and Edward D. Schroeder. Water Quality. Reading,
MA Addi W l 1987MA:Addison-Wesley, 1987.Texas Commission on Environmental Quality. TCEQ. 30 July 2008. 31 July
2008 <http://www.tceq.state.tx.us>.Traister, Elena and Shimon C. Anisfeld. “Variability of Indicator Bacteria at , y
Different Time Scales in the Upper Hoosic River Watershed.” Environ. Sci. Technol. 40.16 (2006): 4990-4995.
United States Environmental Protection Agency. “Ambient Water Quality Criteria for Bacteria- 1986 ” January 1986Criteria for Bacteria 1986. January 1986.
University of Houston and CDM. "Technical Support Document for Buffalo and Whiteoak Bayou TMDL." Technical Support Document. 2008.
University of Houston. “Bacteria Total Maximum Daily Loads for the Sims B W t h d H t T ” A t 2007Bayou Watershed, Houston, Texas.” August 2007.
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Acknowledgments
National Science FoundationUH Civil/Environmental Engineering REUUH Civil/Environmental Engineering REUDr. Hanadi RifaiAnuradha DesaiAnuradha DesaiThe lab group I worked with
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The research study described herein was sponsored by the National Science Foundation under the Award No. EEC-0649163. The opinions expressed in this study are those of the authors and do not necessarily reflect the views of the sponsornecessarily reflect the views of the sponsor.
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