Pathogens in Urban Streams and Runoff
Urban streams are intimately connected to their landscapes through highly engineered drainage networks, and this results in increased loads for many urban pollutants, including pathogens. This is part of the “urban stream syndrome”, and is particularly salient because contamination of recreational and potable waters presents potentially serious health hazards. The ubiquitous and frequent contamination of Baltimore streams with fecal coliforms presents a poignant challenge for managers seeking to minimize degradation by pathogens from runoff, leaking sanitary sewers, and urban animal populations because these streams are so often located in back yards and urban stream valley parks.
These studies of urban streams are focused on E. coli and E. coli 0157, and address the fluxes, survival, sources, and transport of pathogens in the context of urban drainage networks, urban runoff dynamics, and sanitary sewerage networks. The role of forest and impervious cover in pathogen stream transport is being investigated through sampling of streams of the BES LTER, WS263, and Baltimore City DPW stream monitoring networks. Plans are under way to examine the ecology of pathogens in riparian forested patches and the role of animals in transporting pathogens within the urban landscape. Plans are also under way to study the role of urban leaf litter as refugia for pathogens.
This data will enhance our ability to discern the effects of hydrologic drivers on baseflow pathogen levels in urban catchments. The large spatial-temporal framework and collaboration with local government monitoring will facilitate the study of long-term pathogen dynamics, so that effects on public health can be properly assessed. This work will facilitate improved watershed management efforts, including stream restoration work and will aid in the evaluation of sanitary sewer rehabilitation and the assessment of bacterial TMDLs in the Gwynns Falls. It is also being used to propose work that will investigate animal movement through urban catchments as it relates to pathogen loads to streams. Simple, easy to use E. coli enumeration techniques will be used to help watershed associations and students conduct bacteriological assessments of their local streams as well as providing a vehicle for public education and awareness of water pollution in urban areas.
These results suggest that most urban catchments, with their mosaic of vegetated and impervious areas and aging sewer infrastructure, can export very large numbers of pathogens. Leaking sewers (such as in the Gwynns Run) can certainly contribute great quantities of bacteria to downstream reaches, but the prevalence of the pathogen E. coli and E. coli 0157 in almost all Baltimore catchments indicate that other factors are also important. Hydrologic and seasonal influences are large, with elevated concentrations of E. coli in warmer weather and during and after runoff events. In particular, old, ultra urban catchments, with their high impervious cover and pollutant loads, may be hotspots for pathogen delivery to streams that were heretofore unappreciated.
A number of E. coli publications are in production.
Belt, Kenneth T., Christina Hohn, Aiah Gbakima and James A. Higgins. 2007. Identification of culturable stream water bacteria from urban, agricultural, and forested watersheds using 16S rRNA gene sequencing. Journal of Water and Health 5(3): 395-406.
Shelton, D.R., Karns, J.S., Higgins, J.A., Van Kessel, J.S., Perdue, M.L., Belt, K.T., Russel-Anelli, J., Debroy, C. 2006. Impact of microbial diversity on rapid detection of Enterohemorrhagic Escherichia coli in surface waters. Federation of European Microbiological Societies Microbiology Letters. 261:95-101.
Higgins, J.A., Belt, K.T., Karns, J.S., Anelli, J Shelton, D.R. 2005. Tir- and stx- positive E. coli in stream waters in a metropolitan area. Applied and Environmental Microbiology. 71:2511-2519.
Shelton, D.R., Higgins, J.A., Van Kessel, J.S., Pachepsky, Y.A., Belt, K., Karns, J.S. 2004. Estimation of viable Escherichia coli 0157 in surface waters using enrichment in conjunction with immunological detection. Journal of Microbiological Methods. 58:223-231.
Shelton, D.R., Van Kessel, J.S., Wachtel, M.R., Belt, K.T., Karns, J.S. 2003. Evaluation of Parameters Affecting Detection of Escherichia coli O157 in Enriched Water Samples Using Immunomagnetic Electrochemiluminescence. Journal of Microbiological Methods. 2003. v. 55: p. 717-725.
- Kenneth Belt, US Forest Service, Northern Research Station Hydrologist
- Dr. J. Higgins, formerly USDA ARS EMSL microbiologist
- D. Shelton, USDA ARS EMSL research leader
- K. Readel, UMBC GES lecturer
- Dr. Q. Holifield, USFS NRS Soil Scientist
- W. Stack, Baltimore City DPW
- Dr. R. Pouyat, USFS Washington Office Bioclimatologist
- Dr. P. Groffman CIES Senior Scientist
- C. Nilon, University of Missouri-Columbia Professor
- Laura Hungerford, University of MD Professor
- E. Doheney, USGS MD-DE-DC Water Science Center Network Chief & Surface-Water Specialist,
- G. Fisher USGS MD-DE-DC Water Science Center Hydrologist, Surface-Water Specialist,
- Dr. S. Kaushal, UMCES CBL Assistant Professor, Baltimore County Department of Environmental Protection and Resource Management
- Baltimore City DPW
- BES LTER
- Cary Institute of Ecosystem Studies
- UMBC Geography and Environmental Systems
- UMBC Center for Urban Environmental Research and Education
- UMCES Chesapeake Biological Lab
- University of Missouri Fisheries and Wildlife Biology
- University of MD School of Medicine
- USDA ARS Environmental Microbial Safety Lab
- USGS MD-DE-DC Water Science Center
Last Modified: 04/13/2009