 WAC-041
A cache by Cache and Dash SC Hidden: 4/29/2009
Size:  (Small) Difficulty:  Terrain:  (1 is easiest, 5 is hardest)
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This series of caches will detail portions of the State's Ocean
Water Quality Monitoring and Notification program. This beach site
is sample location 'WAC-041' in the program and this cache details
the Tier classifaction system and actual process for sampling:
RISK-BASED BEACH EVALUATION AND CLASSIFICATION
Beaches in South Carolina are ranked based on available information
concerning intensity of beach use, potential risk to public health,
and other applicable factors. A three-tier system was used for this
process, with Tier I being the highest priority:
Tier I site – storm water outfall or swash and high
beach-goer activity. (all sites in Horry County)
Tier II site - heavy beach-goer activity but no direct storm water
outfall (all sites south of Horry County)
Tier III site - low to no beach-goer activity but someone 'might'
swim here as it has patron access (mostly marinas and boat
launches, or places only accessable by boat)
Intensity of beach use was based on accessibility of the beach,
available governmental data, and observations of actual use.
Accessibility encompassed factors such as public or private beach,
number of access points, amount of available parking, and if
accessible by foot or by boat only.
Potential Risk to Public Health
For those beaches previously monitored, risk was assessed based on
the presence of known pollution sources and the number of
advisories and total beach-mile-days of advisories in the 2002 swim
season. For those beaches and points of access not previously
monitored, risk was inferred based on several factors. These
factors included water body classification, potential for point and
non-point source pollution, historic water quality of similar
areas, type of use (likelihood of ingesting water), and
susceptibility of user population.
Other Factors:
Other factors considered in establishing beach priorities were the
importance to the local economy and tourism industry, public
opinion, and public input. South Carolina’s Atlantic Ocean
coastline is a well-known feature of the State drawing millions of
visitors annually and boosting local economy. Due to these factors,
oceanfront beaches were given priority in the ranking scheme.
MONITORING PLAN
The objective of South Carolina’s beach monitoring program is
to protect public health through the issuance of advisories based
on accurate, representative sampling. This sampling design and
monitoring implementation plan has been developed to describe the
frequency and location of monitoring and assessment of South
Carolina’s coastal recreation waters.
A study to determine levels of bacteria in the surf of South
Carolina beaches under varying site and environmental conditions
was conducted with ten local governments in 1997. One sampling site
was selected for each two to three miles of beach, and one each at
the furthest reaches of accessible beach within each
participant’s jurisdiction. In areas with swashes or storm
water discharges to the beach, sites at their confluence with the
ocean, and 100 feet on either side, were selected. At a minimum,
the two sites with the highest estimated storm flows in each
municipality or jurisdiction were included. Samples were collected
in dry weather at high and low tide and in wet weather at high and
low tide. “Dry” weather meant that three or more days
had passed since the last rain. “Wet” weather samples
were collected within three hours of the first rain of 0.1 inches
or more, following a dry period. Over 1,400 surf and storm water
samples were collected during this study. Major finding of the
study were:
In areas with no storm water outlets or swashes, the average
concentration did not exceed EPA guidelines and all individual
sample results were less than State safe swimming limits,
regardless of weather conditions.
Beaches with discharges from swashes and/or storm water outlets
showed variability based on weather. Dry weather samples from these
areas did not exceed the EPA recommended average. Wet weather
effects on surf bacteria varied from site to site and with rainfall
amount; results from many samples exceeded the single-sample limit.
In general, highest single-sample concentrations were associated
with rainfall amounts greater than one inch.
Routine monitoring of beaches from 1998 through present has
validated the previous points and has added to our understanding of
beachfront water quality dynamics. This monitoring has shown that
beaches with associated storm water runoff (Tier I beaches) have
the highest counts in the period three hours before to three hours
following low tides.
SAMPLING PROCEDURE
Samples are taken weekly at Tier I sites and every other week at
Tier II sites. A 100ml sample is taken at knee depth (to simulate a
child playing in the surf) and put on ice. This is done so that any
bacteria concentrations are 'fixed' and will help prevent further
growth as well as allow for a6 hour holding time on samples before
they must be processed.
Once back at the lab, the a 10 ml sample is pulled from the main
sample for each site and diluted with 90ml of regular water to
create a 10:1 concentration. This is put in a sealable pouch with a
special food that encourages bacteria growth. The special food also
has an effect of causing the individual colonies to flouresce, or
glow, under a black light. After 24 hours in an incubator at 103F,
the samples are removed and passed under the blacklight to assess
actual concentrations. Where there is a glow, you have a colony.
Count the colonies and multiple by 10 and you have a concentration
for the sample you took yesterday.
A more rapid method of detection (2 hours) is currently being
developed by scientists with monies from EPA grants and works great
in fresh water beaches (like those on the Great Lakes) but has been
found to be exceedingly inaccurate when used in salt water
environments. So for now, 24 hours is the best method
available.
Info about the cache series: Each cache in the "WAC" series
will have items pertaining to the State's "Stay Well in the Water"
program or in the case of WAC-034, items from the Town of Surfside.
Feel free to take one from each cache and I'll try to keep them all
stocked with different items. Also, each cacher that logs finds at
all four caches in the series will get a special "Stay Well in the
Water" totebag! (One per family of cachers, please). Check out all
four, learn the background and facts and become educated so you can
help educate others!
For further information check out the rest of the caches in the
series:
WAC-004: Program Overview
WAC-019: Permanent Signs and Advisories
WAC-034: Math Modeling and Future Projects
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