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Escherichia coli and enterococci at beaches in Grand Traverse Bay, MI:Sources, Characteristics, and Environmental Pathways

This project quantified Escherichia coli (EC) and enterococci (ENT) in  beach waters and dominant source materials, correlated these with  ambient conditions, and determined selected EC genotypes and ENT  phenotypes. Bathing-water ENT criteria were exceeded more frequently  than EC criteria, providing conflicting interpretations of water  quality. Dominant sources of EC and ENT were bird feces (1 8/d/bird),  storm drains (1 7/d), and river water (1 11/d); beach sands, shallow  groundwater and detritus were additional sources. Beach-water EC  genotypes and ENT phenotypes formed clusters with those from all  source types, reflecting diffuse inputs. Some ENT isolates had  phenotypes similar to those of human pathogens and/or exhibited  high-level resistance to human-use antibiotics. EC and ENT  concentrations were influenced by collection time and wind direction.  There was a 48-72-h lag between rainfall and elevated EC  concentrations at three southern shoreline beaches, but no such lag at  western and eastern shoreline beaches, reflecting the influence of  beach orientation with respect to cyclic (3-5 d) summer weather  patterns. In addition to local contamination sources and processes,  conceptual or predictive models of Great Lakes beach water quality  should consider regional weather patterns, lake hydrodynamics, and the  influence of monitoring method variables (time of day, frequency).    (Escherichia coli); (enterococci); (MST); (microbial source tracking);  (BST); (bacterial source tracking); (Lake Michigan); (Michigan)

Status
In progress
Type
Project
Start Date
End Date
Scope of Study
Field Investigation
Laboratory Investigation
Scale of Phenomena
Landscape
Land Use and Habitat
Shoreline
Lake Basin Connecting Channels
Lake Michigan
State Province
Michigan
Region Being Monitored
Nearshore Terrestrial
Resource Being Monitored
Human Health
Program Drivers
Great Lakes Protection Fund
Beneficial Use Impairment Assessments
Beach Closings
Annex Numbers
Pollution from Contaminated Groundwater
Pollution from Non-Point Sources
Remedial Action Plans and Lakewide Management Plans
Surveillance and Monitoring
General
Monitoring
Annex
  • Annex Numbers
    Annex Numbers
    Pollution from Contaminated Groundwater
    Pollution from Non-Point Sources
    Remedial Action Plans and Lakewide Management Plans
    Surveillance and Monitoring
  • Annex 17

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