Descriptive and Statistical Assessment of Escherichia coli in a Suburban Lake for Management Purposes Open Access

Cunningham, Lauren C. (2016)

Permanent URL: https://etd.library.emory.edu/concern/etds/3t945q94q?locale=en
Published

Abstract

INTRODUCTION Current research efforts focus on contamination in water bodies with obvious risk of exposure and economic impact, such as larger lakes with beaches. Improved surveillance methods increasingly link small scale outbreaks to recreational freshwater. This linkage has implications for lake management. A small neighborhood lake in suburban Georgia is the focus of this investigation into environmental predictors of Escherichia coli (E. coli). The study will address four aims: 1) determine if E. coli concentrations exceed recommended standards for recreational water, 2) assess correlations between variables to determine likely predictors of E. coli levels 3) develop a predictive model that may be used to 4) inform future lake management decisions.
METHODS Data was compiled from publicly available sources including Georgia Adopt-A-Stream, National Oceanographic and Atmospheric Administration Climate Data Online, National Aeronautics and Space Administration Earth Observatory, and community-hired contractor lake service reports. E. coli counts were collected from three sites: the inflowing creek, the outflow edge of the lake, and the outflow creek. Associations between environmental factors were assessed by Pearson and Spearman correlations to determine parameters for a predictive model for E. coli in Lake Avondale. Environmental variables considered include air temperature, conductivity, dissolved oxygen (DO), fecal coliform, insolation, month, pH, season, sampling site, and water temperature. Multivariate linear regression and logistic regression models were developed to investigate the relationships of environmental factors with the dependent variable, E. coli concentration and presence, respectively.
FINDINGS Multivariate linear regression found conductivity, log-transformed precipitation, and sampling site predict log-transformed E. coli. Investigation of interaction terms resulted in an over-specified model of E. coli concentration by conductivity, sampling site, insolation, pH, log-precipitation, water temperature, dissolved oxygen, season, interaction between dissolved oxygen and season. Logistic regression found conductivity and dissolved oxygen predict E. coli presence. Limitations include small sample size and convenience sampling at irregular intervals across space and time. Results suggest key environmental factors such as precipitation, conductivity, and dissolved oxygen be considered or controlled during lake management decisions. For a community actively engaged in the management of a local lake concerns regarding water quality are valid. Extending that concern to questions of health risks while perhaps not a dire concern is a reasonable discussion to promote evidence-based lake management.

Table of Contents

Chapter I: Introduction.......................................................................................................................1

.....Background....................................................................................................................................1

.....Problem Statement..........................................................................................................................5

.....Purpose Statement..........................................................................................................................6

.....Specific Aims..................................................................................................................................6

.....Significance Statement.....................................................................................................................6

.....Research Question............................................................................................................................7

.....Hypothesis......................................................................................................................................7

.....Ethics.............................................................................................................................................7

Chapter II: Literature Review................................................................................................................8

.....Recreational Water-Associated Outbreaks..............................................................................................8

.....Pathogens of Interest........................................................................................................................9

..........Enteric Bacteria...........................................................................................................................9

..........Protozoan Parasites.....................................................................................................................10

..........Enteric Viruses............................................................................................................................11

..........Other Pathogens..........................................................................................................................11

..........Indicator Organisms......................................................................................................................12

.....Sources of Contamination...................................................................................................................12

.....Measures of Microbial Water Quality......................................................................................................13

..........Coliform Bacteria...........................................................................................................................13

...........E. coli........................................................................................................................................13

..........Conductivity................................................................................................................................14

..........Dissolved Oxygen..........................................................................................................................15

..........Insolation....................................................................................................................................15

..........pH..............................................................................................................................................16

..........Temperature.................................................................................................................................16

..........Transparency and Turbidity..............................................................................................................17

..........Exposure.......................................................................................................................................17

..... Water Quality and Dogs ........................................................................................................................ 18

......Lake Management...............................................................................................................................18

..........Factors of Importance.....................................................................................................................18

..........Nutrients.......................................................................................................................................19

..........Pesticides......................................................................................................................................20

..........Metals...........................................................................................................................................20

..........Buffer Region..................................................................................................................................20

..........Color.............................................................................................................................................21

..........Algae and Fish.................................................................................................................................21

..........Canada Geese and Other Waterfowl.....................................................................................................22

..........Precipitation....................................................................................................................................24

.....Upper Ocmulgee River Watershed.............................................................................................................24

.....Bess Walker Park, Avondale Estates..........................................................................................................25

.........Lake Management in Bess Walker Park...................................................................................................25

.........Fauna of Bess Walker Park..................................................................................................................26

.........Geese of Bess Walker Park..................................................................................................................26

.........Pesticides and Bess Walker Park...........................................................................................................27

.....Results of Studies Investigating the Problem - Interrelationships

.....Between Variables.................................................................................................................................28

.....Risk Assessment....................................................................................................................................29

.....Current problem and relevance to target population.....................................................................................30

Chapter III: Manuscript............................................................................................................................31

.....Abstract..............................................................................................................................................31

.....Introduction.........................................................................................................................................32

.....Methods..............................................................................................................................................34

..........Data Sources...................................................................................................................................34

...........Data Analysis..................................................................................................................................36

.....Results................................................................................................................................................39

..........Descriptive Results............................................................................................................................39

..........Correlation Results.............................................................................................................................40

..........Linear Regression Results....................................................................................................................41

..........Logistic Regression Results..................................................................................................................43

.....Discussion.............................................................................................................................................43

.....Conclusion.............................................................................................................................................48

Chapter IV: Conclusion and Recommendations.............................................................................................50

.....Conclusions............................................................................................................................................50

......Recommendations for Lake Avondale..........................................................................................................50

.....Recommendations for Future Studies...........................................................................................................51

.....Extended Discussion of Canada Geese.........................................................................................................52

.....Volunteer Data Collection..........................................................................................................................53

.....Public Health Implications..........................................................................................................................53

Chapter V. Report to the Community............................................................................................................54

Tables and Figures......................................................................................................................................56

.....Table 1: Descriptive statistics of continuous environmental factors....................................................................56

.....Figure 1: Comparison of E. coli concentration by sampling site...........................................................................57

.....Table 2: Yearly compliance with EPA monthly E. coli regulation..........................................................................57

.....Table 3: Monthly compliance with EPA monthly E. coli regulation

...................for recreational..........................................................................................................................58

.....Figure 2: Comparison of environmental variables across the three

....................sampling sites...........................................................................................................................59

.....Table 4: Results of simple linear regression analysis of environmental

....................variables with log-transformed E. coli to assess bivariate association...................................................60

.....Table 5: Comparison of multivariate linear models for predicting E. coli

...............concentrations in Lake Avondale based on environmental factors.............................................................60

.....Table 6: Correlation matrix comparing environmental parameters using

.....................correlation coefficients and the associated p-values.......................................................................61

.....Table 7: Parameter estimates for the full eight--variable predictive linear

...................regression model of log-transformed E. coli in Lake Avondale...............................................................62

.....Table 8: The parameter estimates for the reduced model based on backwards

....................selection from the eight-variable predictive model of log-transformed E. coli.........................................62

.....Table 9: The parameter estimates for the reduced model with potential outliers identified
...................by jackknife residuals, removed
.....................................................................................................62

.....Table 10: Parameter estimates for the reduced nine-variable predictive linear regression
.....................model including investigation of interaction terms............................................................................
63

.....Figure 4: Numbers of geese relocated annually from Lake Avondale, Avondale Estates, Georgia................................63

References..................................................................................................................................................64

Appendix.....................................................................................................................................................75

.....Appendix A: Acronyms................................................................................................................................75

.....Appendix B: Definitions of Terms...................................................................................................................76

.....Appendix C: Regulations on Fecal Coliforms and E. coli......................................................................................77

.....Appendix D: Estimated Water Ingestion During Water Recreation Activities...........................................................78

.....Appendix E: Proportions of Microbial Etiologic Agents Associated with Recreational Water
........................Outbreaks
.............................................................................................................................79

.....Appendix F: Key Water Quality Concerns for Selected Lake Uses........................................................................80

.....Appendix G: Data Sources...........................................................................................................................81

.....Appendix H: Map of Plan for Bess Walker Park.................................................................................................82

.....Appendix I: Locations of Sampling Sites.........................................................................................................83

......Appendix J: Extended Site Description..........................................................................................................85

......Appendix K: Monthly Precipitation Data.........................................................................................................86

......Appendix L: Photos from Lake Avondale........................................................................................................87

......Appendix M: Relative Location of Lake Avondale.............................................................................................88

About this Master's Thesis

Rights statement
  • Permission granted by the author to include this thesis or dissertation in this repository. All rights reserved by the author. Please contact the author for information regarding the reproduction and use of this thesis or dissertation.
School
Department
Subfield / Discipline
Degree
Submission
Language
  • English
Research field
Keyword
Committee Chair / Thesis Advisor
Committee Members
Partnering Agencies
Last modified

Primary PDF

Supplemental Files