Article: E. coli Sampling Reliability at a Frequently Closed Beach

[Wirick.Holiday@epamail.epa.gov]

Congratulations to Richard Whitman and Meredith Nevers whose article
made the cover of ES&T!

(See attached file: EST0081504_cov.pdf)

Escherichia coli Sampling
Reliability at a Frequently Closed
Chicago Beach: Monitoring and
Management Implications
R I C H A R D L . W H I T M A N * A N D
M E R E D I T H B . N E V E R S
U.S. Geological Survey, Great Lakes Science Center,
Lake Michigan Ecological Research Station,
1100 North Mineral Springs Road, Porter, Indiana 46304
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=1770) at 63rd Street Beach, Chicago for 6 months
in 2000 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 70% 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. As the recreational water
quality national database is developed, it is important
that sampling strategies are empirically derived from a
thorough understanding of the sources of variation and the
reliability of collected data. Greater monitoring efficacy
will yield better policy decisions, risk assessments,
programmatic goals, and future usefulness of the information.


(See attached file: EST0081504_cov.pdf)

EST0081504_cov.pdf