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Poor sanitation infrastructure in rural areas can often lead to high levels of fecal contamination in local waterbodies and subsequent exposure to waterborne disease can occur. Although standard water quality measures such as quantification of E. coli can reveal relative concentrations of fecal contamination, they do not pinpoint the sources of such contamination. Source assessment in rural areas affected by untreated household waste might be improved with the human-specific, microbial source tracking marker HF183. This study attempted to quantify HF183 in two particular Appalachia streams with known discharges of untreated household waste. Water samples were taken above and at multiple points below these discharges on 29 occasions between August 2012 and April 2016, and tested for both HF183 and E. coli. HF183 was detected consistently in one of the study streams, though the concentrations were generally much lower than those previously reported in raw sewage; in the other watershed, HF183 was never detected. Further analysis via a multiple linear regression model showed a positive correlation between the level of E. coli and the proximity and number of known waste discharge points upstream from each sampling site. Primary conclusions of this study include: 1) HF183 is not always detected, even in watersheds with known sources of human fecal contamination, 2) it may be a useful water quality assessment tool where such contamination is suspected, particularly in cases where contaminant source allocation is necessary for setting mitigation priorities.

High levels of fecal bacteria in surface waters are a public health concern due to the enteric illnesses caused by primary contact with these waters. Shortcomings in the current fecal indicator bacteria (FIB) monitoring approach and the ubiquity of pathogen-impaired water bodies has led to the development of microbial source tracking (MST), a molecular tool that can identify potential fecal contamination sources. In this study we use a bacterial community based approach examining the V4 region of the 16S rRNA gene to elucidate sources of fecal bacteria in Antelope Creek, an urban creek in Lincoln Nebraska. We hypothesized that sediment from the bed of Antelope Creek and animal wastes near the stream were major sources of the fecal bacteria in dry and wet weather water samples. To test the hypothesis, water from three dry weather events and three storm events was collected in addition to streambed sediment, sanitary sewage, and fecal waste from birds, dogs, small mammals, and horses. A UniFrac multi-variative principal coordinate analysis (PCoA) revealed differences in bacterial communities from sediment and water samples, indicating that sediment is not likely a major contributor of bacteria to dry and wet weather flows. PCoA analysis on the Bacteroidetes phylum revealed strong differences in community composition between water samples and fecal waste from horses, sanitary sewage, geese and dogs. The closest fecal community compositions were found for wastes from small mammals, pigeons, and ducks. Statistical differences were seen in the overall bacterial community and the Bacteroidetes population by sampling date for both dry and wet weather water, while no statistical differences were seen by sampling location. This distinction suggests that environmental or source changes throughout the recreational season (e.g. temperature, sunlight, seasonal animal migration) were the major drivers of the shifts in the bacterial community in Antelope Creek. The absence of a location with consistently high E. coli counts suggests no major point source contribution. Advisers: Bruce I. Dvorak and Xu Li

During the 1980’s millions of households in Bangladesh switched from drinking surface water to private groundwater wells to reduce their exposure to fecal microorganisms. Sadly, this switch to shallow groundwater resulted in the largest example of drinking water poisoning in history, with approximately 100 million people exposed to high concentrations of naturally occurring Arsenic in the groundwater. Spatial distribution of Arsenic in the shallow aquifers tends to be patchy, so the most economical mitigation option has been lateral switching from high Arsenic wells to nearby low Arsenic wells. The recently developed Arsenic flushing conceptual model, which explains the spatial distribution of Arsenic throughout the shallow aquifers in Bangladesh, suggests however, that low Arsenic zones are recharged via coarse-grained, rapid flow pathways and therefore represent a higher risk for waterborne pathogens. The objectives of this dissertation are to evaluate new methods for sampling and detection of waterborne pathogens, while also identifying sources of fecal contamination and transport pathway(s) to private wells emplaced within the shallow aquifers. It was demonstrated that private wells are broadly contaminated with E. coli, with prevalence ranging from 30 to 70%. The fact that E. coli was detected more frequently in private wells than sealed monitoring wells (p

Bacteriological examination of natural waters, using indicator organisms to establish their sanitary quality, is a standard procedure in water quality surveys. The coliforn and fecal streptococci bacteria, being natural inhabitants of the intestine, occur in very large numbers in human and animal excreta,hence their use as indicator organisms to indicate the extent of fecal pollution. There has been increasing interest in the possible use of bacteriological examination of water as a means of determining the nature and remoteness of a pollution source. To be able to distinguish animal waste contamination from human has obvious significance for public health purposes. For practical purposes, the determination of the age and source of fecal contamination should be reasonably apparent from the results of the investigatory methods used.