Date of Award

5-14-2021

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Public Health

First Advisor

Dr. Lisa Casanova

Second Advisor

Dr. Karen Nielsen

Third Advisor

Dr. Dajun Dai

Abstract

The Chattahoochee River Watershed is the most utilized surface water resource in the state of Georgia, providing drinking water to most of metropolitan Atlanta, power to millions, and opportunities for recreation. Increasing population, urbanization, uncontrolled stormwater runoff, and wastewater mismanagement have impacted the water quality in the watershed, the extent of which has not been thoroughly assessed in over 20 years. The purpose of this dissertation is to examine trends in water quality across the watershed, identify current gaps in water quality analysis, and guide the direction of future research.

The three studies in this dissertation examine 10 years of data from the Neighborhood Water Watch (NWW) program across 159 collection sites in the Chattahoochee River Watershed to describe the geographic and temporal variations of E. Coli, total coliforms, optical brighteners, and turbidity in surface waters. The impacts of rainfall, seasonality, and urbanicity on water quality are assessed using ANOVA and multilevel models. Extreme values identified through an ARIMA time series model are used in a spill detection algorithm and seasonal spike counts are determined for the water quality indicators.

The findings of this dissertation identified relatively stable levels of E. Coli, coliform, and floridity across the watershed, though the overall mean concentration for hydrologic unit codes exceeded the selected water quality thresholds for all contaminants. Temporally, the fewest proportion of outliers were recorded during spring for all water quality indicators and the multilevel model confirmed decreased E. Coli concentrations associated during spring compared to the other seasons. E. Coli and floridity concentrations were higher in urban areas, while coliform and turbidity maintained stable levels across urban and rural tracts. The ARIMA time series analysis suggests that the NWW sampling strategy is not systematic enough to detect spills to waterways. These results provide insight into the current state of the watershed and present perspectives on the effectiveness of utilizing citizen science programs for large scale surface water monitoring.

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