Assessing Fecal Pollution in Urban Watersheds: Insights from Turkey Creek
The late, great comedian George Carlin once mused that swimming in the Hudson River in the 1940s as a child prepared his immune system for anything the world could throw at it. The high pollution levels in the Hudson, especially around that period of time, have been well documented with clean-up efforts lasting decades.
While the benefits of microbial exposure and the risks of an excessively sterile environment have been known to the microbiome research community for years, it was very much by luck that he was not injured through exposure to this river that was impaired not only by contamination from wastewater, but also industrial chemical waste that was routinely disposed of in the Hudson. Many other bodies of water around the USA and the rest of the world are still contaminated by chemical and/or biological pollutants from different sources. Two such bodies of water include the Seine River in France, where contamination is threatening to interfere with the 2024 Paris Olympics, and Turkey Creek in Gulfport, Mississippi, USA, which is often listed as one of the most polluted creeks in the United States.
Environmental health risks from fecal and other watershed pollution present a significant concern for public safety due to potential spread of human and animal pathogens and impacts on nearby marine and wildlife. A recent study published in the journal Science of the Total Environment explored fecal contamination in Turkey Creek with a focus on better understanding the sources and dynamics of this pollution.
Background
Fecal contamination in surface water poses severe risks, including the pollution of drinking and recreational waters, degradation of aquatic habitats, and disease transmission. Millions of people globally still face exposure to fecal-contaminated drinking water. In the United States, the EPA mandates the development of Total Maximum Daily Loads (TMDLs) for impaired watersheds to manage and reduce pollution. Identifying the sources of this pollution is crucial for the success of these strategies.
The Study
Researchers from the US Environmental Protection Agency (EPA), and University of Alabama conducted a comprehensive study of Turkey Creek, listed among America's most endangered creeks. After collecting samples from Turkey Creek, the team from University of Alabama and EPA enlisted the help of Zymo Research’s bioinformatics team to carry out additional analysis on the existing data to identify additional geographical or temporal patterns in the collected samples. The study aimed to identify the sources of fecal pollution and factors influencing fecal indicator loading.
Methodology
Over two years, water quality monitoring was carried out at four stations along Turkey Creek for three key parameters including:
- Enumeration of Fecal Indicators: E. coli and male-specific coliphages were measured to indicate fecal contamination.
- Sediment Analysis: Metagenomic analysis of sediment samples provided insights into microbial community dynamics.
- Water Quality Measurements: Parameters such as pH, salinity, and temperature were recorded.
Key Findings
- Surface Water Contamination Sources:
- Two stations, one near a lift station and one upstream of a wastewater treatment plant, showed the highest fecal contamination.
- The station adjacent to livestock land exhibited the least impairment.
- Municipal sewage was identified as a predominant source of contamination near the wastewater treatment plant.
- Rainfall Influence:
- Antecedent rainfall positively correlated with fecal indicator loadings at three of the four stations.
- However, rainfall was not the primary driver of fecal transport at one station.
- Sediment Microbial Communities:
- No presence of E. coli or enterococci in the sediment.
- Unique taxonomic signatures were observed at each station, with some overlap after major rain events.
- Sediment collection methods and sample locations significantly influenced microbial composition.
Implications
The study's multi-faceted approach provided critical insights into the complexity of fecal pollution sources in the Turkey Creek watershed. Identifying and characterizing point and non-point sources of contamination aids in developing targeted pollution abatement strategies. The findings highlight the importance of regular monitoring and comprehensive analysis to address urban watershed pollution effectively.
Conclusion
Urban watersheds like Turkey Creek face complex challenges related to fecal pollution. This study underscores the necessity of integrating various analytical methods to understand and mitigate these issues. Effective management and pollution reduction strategies are essential to protect public health and environmental quality in urban areas.
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