Published: March 7, 2024 By

The George R. Aiken Graduate Fellowship supports CU Boulder graduate students conducting water-related research. Allison Cook, a master’s degree student in the Environmental Engineering program, is passionate about tracing and control of pathogens in the urban environment for stronger public health. With her fellowship, she is investigating E. coli concentrations in storm sewers near Boulder Creek. Her research will help identify the source of the E. coli, which will help mitigation efforts.

The study conducted as part of the George Aiken Fellowship investigated water quality management strategies in Boulder, Colorado, using Microbial Source Tracking (MST). It focused on E. coli contamination on CU campus storm sewers. Collaborating with the University of Colorado Boulder Department of Environmental Health and Safety (CUEHS), the study aimed to evaluate the effectiveness of annual pipe cleaning initiatives in reducing E. coli pollution. By conducting nine sampling campaigns between June and October 2023, the study assessed the impact of pipe cleaning on the storm sewer microbiome and identified key factors influencing microbial contamination levels.

The MST study employed quantitative polymerase chain reaction (qPCR) methods recommended by the EPA to measure fecal indicator bacteria concentrations, targeting specific markers for human, avian, ruminant, and canine fecal contamination. Surprisingly, the analysis consistently detected human fecal contamination throughout the study period, with concentrations highest at the Upper 28th Street Outfall location that leads into Boulder Creek. However, markers for avian, canine, and ruminant fecal contamination were generally not detected, except for a single instance of avian marker detection coinciding with elevated E. coli levels that were measured by CUEHS.

Furthermore, the study assessed the impact of precipitation events on microbial contamination levels and conducted statistical analyses to evaluate the effectiveness of pipe cleaning. Results indicated no significant difference in contamination levels before and after cleaning at the sampling sites, suggesting the need for further attention to address microbial contamination comprehensively. This study also suggests that pipe cleaning may not be the most effective E. coli mitigation strategy; or at least, that pipe cleaning did not significantly alter the residual microbiome of the stormwater pipes.

Overall, the study underscores the complexity of microbial dynamics in urban environments and highlights the importance of continued monitoring efforts to inform effective water quality management strategies.

See also

A research partner and Alli Cook sample a CU Boulder storm sewer in fall 2023.

A research partner and Alli Cook sample a CU Boulder storm sewer in fall 2023.

Alli Cook, with campus partners, samples water from a campus storm sewer.

Cook, with campus partners, samples water from a campus storm sewer.