Water Resources Research Act Program

Details for Project ID 2016GA366B

Fecal bacteria source tracking, nutrient analysis, and modeling of an urban TMDL watershed

Institute: Georgia
Year Established: 2016 Start Date: 2016-04-01 End Date: 2017-03-31
Total Federal Funds: $18,000 Total Non-Federal Funds: $36,000

Principal Investigators: David Radcliffe, Mussie Habteselassie

Project Summary: Pathogens are the most common reason why U.S. water bodies are listed as impaired. Many of these streams in the Southeast are in the highly developed I-85 urban corridor that runs from Montgomery, AL to Richmond, VA in the Southern Piedmont geophysical region. The primary limitation to addressing pathogen TMDL streams has been identifying the sources of fecal pollution. Nutrients are another common reason for listing water bodies as impaired. Our proposal will focus on identification of the sources of pathogens and nutrients in a typical urban stream in Athens, GA. The project will involve the use of advanced microbial source tracking and modeling approaches to isolate the sources. The proposal has been developed in cooperation with Athens-Clarke County Stormwater Management Program. The specific objectives of this proposed study are:  to use bacterial and chemical methods of source tracking to determine the source of bacteria, nitrogen (N), and phosphorus (P) in the Trail Creek watershed, and  to develop a watershed-scale model using the Storm Water Management Model (SWMM) to explore the effect of implementing low impact development (LID) within the Trail Creek watershed. The Trail Creek watershed is 33 km2 in area and consists of the East Fork, West Fork, and Trail Creek branches, all of which are listed as impaired due to fecal coliform (FC). The upper reaches of the East and West Forks are in forest and pasture landuse and the lower reaches are predominately urban landuse. The watershed includes parts of four census tracts which have high percentages of population living below the poverty line. We will install an automated sampler (purchased on a previous grant) for sampling during storms at the outlet of the Trail Creek watershed. We will collect monthly base flow samples and composite samples during storm events for 9 months at the outlet. In addition, we will conduct two synoptic targeted sampling events along all three reaches, one during base flow and one shortly after a storm. We will use these water samples to carry out the source tracking work, nutrient analysis, and modeling. The samples will be analyzed for bacteria sources and concentrations of E. coli and Enterococci, forms of N and P, and for nitrogen and oxygen isotopes. The isotope analysis will help identify the sources of nutrients. Potential sources of bacteria and nutrients include leaking sewer lines, overflowing sewer manholes, septic systems, cattle and horses, deer, wildlife, pets,and leaky storm water lines that intercept groundwater contaminated by other sources. Bacterial markers for human, ruminant and dog sources will be used. We will develop a watershed scale model of Trail Creek using the SWMM model which has the ability to simulate various LID practices including filter strips, rain gardens, swales, and pervious pavement. We will use the model to test scenarios using various LID practices, their locations, and costs to determine the most effective way to reduced bacteria and nutrient loading to Trail Creek. The proposed project will train a Masters student, an undergraduate student worker, and an undergraduate student intern. Our study could be a model for addressing impaired urban watersheds in the Southern Piedmont region.