variability ofvariability of escherichia coliescherichia

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


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


Location of Whiteoak Watershed


Sample Collection


Laboratory Processingy g


Laboratory AnalysisLaboratory Analysis


Daily Fecal Coliform Concentrations


Daily E. coli Concentrations


Potential causes of variabilityy

Very localized conditionsVery localized conditions

T tTemperature

Rain


Weekly E. coli Concentrations


Geometric mean of E. coli concentrations at each site


Comparing E. coli concentrations at different sites


Temperature


Rain


Number of Days After Rain Event


Amount of Rainfall

R2 = 136R2 =.136


What Causes Such Variation?


Location Effects


Temperature EffectsTemperature Effects

25°C <Water Temperature < 35°C


Rain Effects

Wash-Off Effect


Take a lot of samples


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.


Acknowledgments

National Science FoundationUH Civil/Environmental Engineering REUUH Civil/Environmental Engineering REUDr. Hanadi RifaiAnuradha DesaiAnuradha DesaiThe lab group I worked with


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.


variability ofvariability of escherichia coliescherichia

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