Skip to main content

Escherichia coli Sampling Reliability at a Frequently Closed ChicagoBeach: Monitoring and Management Implications

Monitoring beaches for recreational water quality is becoming more  common, but few sampling designs or policy approaches have evaluated  the efficacy of monitoring programs. The authors intensively sampled  water for E. coli (N=177 ) at 63rd Street Beach, Chicago for 6 months  in 2    in order to:  1) characterize spatial-temporal trends,   2) determine between and within transect variation, and   3) estimate sample size requirements and determine sampling reliability.     E. coli counts were highly variable within and between sampling sites  but spatially and diurnally autocorrelated. Variation in counts  decreased with water depth and time of day. Required number of samples  was high for 7 % precision around the critical closure level (i.e., 6  within or 24 between transect replicates). Since spatial replication  may be cost prohibitive, composite sampling is an alternative once  sources of error have been well defined. The results suggest that  beach monitoring programs may be requiring too few samples to fulfill  management objectives desired.    (beach closings); (beach closing); (beach closure); (beach closures);  (E. coli); (Escherichia coli); (monitoring); (beach monitoring);  (microbial); (microbe); (microbes); (Lake Michigan)

In progress
Start Date
End Date
Scope of Study
Field and Modeling
Laboratory Investigation
Scale of Phenomena
Land Use and Habitat
Lake Basin Connecting Channels
Lake Michigan
State Province
Region Being Monitored
Nearshore Terrestrial
Resource Being Monitored
Human Health
Plankton / Microorganisms
Beneficial Use Impairment Assessments
Beach Closings
Annex Numbers
Remedial Action Plans and Lakewide Management Plans
Surveillance and Monitoring
  • Annex Numbers
    Annex Numbers
    Remedial Action Plans and Lakewide Management Plans
    Surveillance and Monitoring
  • Annex 17

The Great Lakes - St. Lawrence Research Inventory is an
interactive, Internet-based, searchable database created as a tool to collect and disseminate
up-to-date information about research projects in the
Great Lakes - St. Lawrence Region.