Investigating Bacterial Contamination in Snapfinger Creek

Samantha Andrews, Georgia State University-Perimeter College

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Initial Publication Date: September 16, 2022


Water quality is a global concern for natural and potable water sources. Lack of access to clean water due to poor sanitation can lead to microbial disease outbreaks, such as cholera, that can cause serious illnesses and death. In the US, one threat to water quality is raw sewage spills into homes and bodies of water from breaches in aging sewer systems [1]. While local government organizations and the US Environmental Protection Agency (EPA) are actively working to resolve the issue, the problems persist today, especially during times of heavy rainfall. Raw sewage contains chemicals, human waste, microbes, and other contaminates that are a threat to human, animal, and environmental health [2-4].

Snapfinger Creek, located in Metro Atlanta, has been contaminated by many raw sewage leaks in the past few years. In March 2020, an estimated 7 billions of untreated sewage was released into Snapfinger Creek during periods of heavy rainfall [5]. The United States Geological Survey (USGS) monitors conditions in Snapfinger Creek and has reported high values of fecal coliform and E. coli bacteria concentrations. Water pollution is not an isolated occurrence. Snapfinger Creek is not a contained body, so all connected bodies of water downstream are also in danger of contamination.

For this activity, students will analyze ten years of collected water quality data from Snapfinger Creek and investigate the change in the microbial concentration levels. The essential question that students will answer for this activity is: how does the aging infrastructure of the nation's sewer systems impact water quality in local bodies of water?

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Learning Goals

  • Explain the impact of sewage spills on water quality and environmental health and safety.
  • Utilize USGS resources to monitor and analyze historical and real-time Snapfinger Creek environmental parameters (ex: pH, dissolved oxygen levels).
  • Create time series graphs to model and analyze the fecal coliform, E. coli, and total coliform concentration data in Snapfinger Creek over a 10-year period.
  • Use bacteria data to predict conditions that could promote algae blooms in Snapfinger Creek.
  • Evaluate and compare the bacteria time series graphs to evaluate their implications on human health and water quality management.

Context for Use

This activity can be implemented in an introductory biology, microbiology, and environmental science lecture or lab course. This activity requires 1 to 3 days of instruction, depending on the amount of class time available and the students' knowledge of Excel. While students do not have to be experts in microbiology, it is helpful to have a basic understanding of the terms and techniques so that data will have meaning beyond just a plotting exercise. If necessary, due to time constraints, you may choose to assign one of the days as an out of class assignment or combine Days 1 and 2. A proposed class schedule is provided in the teacher resource materials.

How Instructors Have Used This Module

Using Project EDDIE modules in Microbiology (BIO 2300)
Samantha Andrews, Georgia State University
This module will help students explore the environmental impact of sewage spills on bodies of water. Sewage spills are not only a human health hazard due to the release of waste and microbes, but can also increase algae growth and lead to disruption of the ecosystem.

Description and Teaching Materials

Quick overview of the activities in this module

  • Pre-class assignments: (1.) Students will review the EPA article to learn about the environmental impacts of sewage leaks in the US. (2) Students will also complete an Excel tutorial to learn how to generate quality time series graphs.
  • Activity A: Students create a time series graph to model the fecal coliform levels in Snapfinger Creek over a ten-year period.
  • Activity B: Students will model the Snapfinger Creek E. coli levels and evaluate implications for human health.
  • Activity C: Students will compare water quality time series on the the total coliform concentration and their implications for water quality management.

Workflow of this module:

  1. Instructor will present the module using a PowerPoint presentation on water quality background information and activity instructions (provided below).
  2. Students will receive the EPA handout, Excel pre-class assignment, and activity handout (all provided below).
  3. Students will complete the pre-class assignments, read EPA document and complete the Excel plotting exercise. For Excel plotting assignment students will learn how to how to to create time series plot. 
  4. Students will complete the activities. 

Teaching Materials

Instructor Files

  • Instructional PowerPoint (PowerPoint 2007 (.pptx) 2MB Sep6 22)
  • Instructor Guide (Microsoft Word 2007 (.docx) 22kB Sep15 22)

Student Files

Data Sets (for reference)

  • Complete data set (Excel 2007 (.xlsx) 808kB Aug16 22) - Use for reference, not the activity

Teaching Notes and Tips

Students likely have various levels of experience with technology and graphing. The pre-class assignment can be assigned as a tutorial and provide practice with Excel and graphing. An instructors' guide, answer key, and presentation are provided above.


Students will answer questions throughout the activity that reinforce the learning goals.

References and Resources

  1. EPA Enforcement Report-EPA Strategically Addressing Raw Sewage Discharges Across Nation to Protect Public, Environment (
  2. Loosli, F., et al., Sewage spills are a major source of titanium dioxide engineered (nano)-particles into the environment. Environ Sci Nano, 2019. 6(3): p. 763-777.
  3. Mearns, A.J., et al., Effects of pollution on marine organisms. Water Environ Res, 2019. 91(10): p. 1229-1252.
  4. Fent, K., A.A. Weston, and D. Caminada, Ecotoxicology of human pharmaceuticals. Aquat Toxicol, 2006. 76(2): p. 122-59.
  5. 11 Alive News March 11, 2020 Report: