Distribution of E. Coli in Urban Streams of Baltimore
Belt, K., Readel, K. and K. Zoller
Escherichia Coli were enumerated from weekly samples in streams of the Baltimore Ecosystem Study from 2000 to 2003. All suburban and urban sites had high levels of E. Coli. The urbanized downstream site in the Gwynns Falls (at GFCP) had the highest mean concentration (ca. 9000 org.100ml), and the largely forested sites of Baismans Run (BARN & POBR) had the lowest (mean <. 100 org/ml). Almost the entire E. Coli load at the most downstream (GFCP) Gwynns Falls site was due to a nearby small tributary (GFGR) receiving large amounts of sewage. In general, the suburban sites had the highest levels (above 1000 org/ml), and experienced the highest temporal variability. The two most upstream suburban Gwynns Falls sites (GFGL and GFGB) had higher mean concentrations than the downstream “older” suburban site (GFVN) and the older downstream reaches (once the effect of the contaminated tributary was removed). A Rapid PCR technique was used to analyze water samples from 20 streams in the Baltimore area in 2002-2003 to detect the E. Coli 0157 H7 pathogen and half of these sites had “hit” rates of over 20 %, with the greatest detection rates in the (ca. 40-75 %) in the sewage impacted sites (GFGR & GFCP) and the suburban GFGL site.
Keywords: E. Coli, Pathogens, Water Quality

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