GSA Annual Meeting in Denver, Colorado, USA - 2016

Paper No. 71-18
Presentation Time: 9:00 AM-5:30 PM


DINGUS, Jack1, BARRON Jr., Herbert Pat1 and DUNKLE, Kallina2, (1)Department of Geosciences, Austin Peay State University, PO Box 4418, Clarksville, TN 37044, (2)Department of Geosciences, Austin Peay State University, Clarksville, TN 37044,

In 2006, three of the Cumberland River’s tributaries were placed on the Environmental Protection Agency’s 303(d) list, restricting them from being used for municipal water supply due to Escherichia coli (E. coli) measurements above maximum allowable contaminant levels and high siltation. E. coli contaminates surface water and groundwater from sources that include municipal sewage and agricultural runoff. Furthermore, urban land use attributes to many sources of water pollution such as runoff, improper disposal of trash, leaky septic systems, and animals. Impermeable areas such as driveways, pavement, and rooftops force storm water runoff to be directed to the streams through storm drains rather than allowing the water to be filtered by the natural processes of the riparian buffer zone. Urban land use within the watershed's impaired stream areas ranges from 1.7% to 68.7% of land adjacent to the streams.

In order to locate the source or sources of E. coli stream contamination, water samples have been collected and tested for E. coli since November 2014, with weekly testing in 2015. The water samples were analyzed with a DNA-detection technique, called Polymerase Chain Reaction (PCR), which is a widely practiced molecular technique to detect trace amounts of very specific DNA sequences in water samples; this is more popularly thought of as “DNA fingerprinting”. Additionally, one to four locations on each stream have been periodically analyzed for pH, total dissolved solids, electrical conductivity, nitrates, and dissolved oxygen to look for chemical trends. Aerial views of the streams were obtained from Google Maps to determine the extent of their riparian buffers. As a check to this data, portions of each of the three streams were walked to document the riparian buffer zones along the streams. Also, a map with multiple layers was created in ArcMap that includes land use and sampling results. Definite correlation can be seen between precipitation and E. coli presence, therefore, samples were collected before, during, and immediately after precipitation events. Rainfall is a likely cause of spikes in E. coli results, due to run-off from these rainfall occurrences bypassing the natural filtration of the riparian buffer.