Examination of the watershed-wide distribution of Escherichia coli along southern Lake Michigan: An integrated approach

Applied and Environmental Microbiology
By: , and 



Recent research has highlighted the occurrence of Escherichia coli in natural habitats not directly influenced by sewage inputs. Most studies on E. coli in recreational water typically focus on discernible sources (e.g., effluent discharge and runoff) and fall short of integrating riparian, nearshore, onshore, and outfall sources. An integrated “beachshed” approach that links E. coli inputs and interactions would be helpful to understand the difference between background loading and sewage pollution; to develop more accurate predictive models; and to understand the differences between potential, net, and apparent culturable E. coli. The objective of this study was to examine the interrelatedness of E. colioccurrence from various coastal watershed components along southern Lake Michigan. The study shows that once established in forest soil, E. coli can persist throughout the year, potentially acting as a continuous non-point source of E. colito nearby streams. Year-round background stream loading of E. coli can influence beach water quality. E. coli is present in highly variable counts in beach sand to depths just below the water table and to distances at least 5 m inland from the shore, providing a large potential area of input to beach water. In summary, E. coliin the fluvial-lacustrine system may be stored in forest soils, sediments surrounding springs, bank seeps, stream margins and pools, foreshore sand, and surface groundwater. While rainfall events may increase E. coli counts in the foreshore sand and lake water, concentrations quickly decline to prerain concentrations. Onshore winds cause an increase in E. coli in shallow nearshore water, likely resulting from resuspension of E. coli-laden beach sand. When examining indicator bacteria source, flux, and context, the entire “beachshed” as a dynamic interacting system should be considered.

Publication type Article
Publication Subtype Journal Article
Title Examination of the watershed-wide distribution of Escherichia coli along southern Lake Michigan: An integrated approach
Series title Applied and Environmental Microbiology
DOI 10.1128/AEM.00454-06
Volume 72
Issue 11
Year Published 2006
Language English
Publisher American Society for Microbiology
Contributing office(s) Great Lakes Science Center
Description 10 p.
First page 7301
Last page 7310
Online Only (Y/N) N
Additional Online Files (Y/N) N
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