Groundwater in the Great Lakes Basin

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season. The sampling sites included 24 land-spreading
sites and 26 septic-system sites. Among the 50 wells,
four (8%) were positive for six different types of viruses
(Borchardt et al., 2003). The implication of this study is
that if an 8% contamination rate is generalizable, then
as many as 1.2 million households in the United States
are exposed to viruses via their well water.
These two studies are crucial to the discovery that:
• Human viruses are common in groundwater, even
in deep wells in a confined aquifer.
• Bacteria indicators of water sanitary quality are not
correlated with virus presence.
• Viruses are responsible for groundwater-related
disease outbreaks, but the level of sporadic
endemic illness attributable to virus-contaminated
groundwater is unknown.
PROTECTION OF GROUNDWATER SOURCES
TO PROTECT PUBLIC HEALTH
As stated on the U.S. EPA Web site:
The Environmental Protection Agency is promulgating
a National Primary Drinking Water Regulation, the
Ground Water Rule, to provide for increased protection
against microbial pathogens in public water
systems that use ground water sources. This final rule
is in accordance with the Safe Drinking Water Act as
amended, which requires the Environmental Protection
Agency to promulgate National Primary Drinking
Water Regulations requiring disinfection as a treatment
technique for all public water systems, including
surface water systems and, as necessary, groundwater
systems. The Ground Water Rule establishes a risktargeted
approach to target groundwater systems
that are susceptible to fecal contamination, instead
of requiring disinfection for all groundwater systems.
The occurrence of fecal indicators in a drinking water
supply is an indication of the potential presence of
microbial pathogens that may pose a threat to public
health. This rule requires groundwater systems that are
at risk of fecal contamination to take corrective action
to reduce cases of illnesses and deaths due to exposure
to microbial pathogens.
The Ground Water Rule will require monitoring that
will identify groundwater-based water supply systems
that are susceptible to fecal contamination. These
higher risk systems are required by the rule to monitor
and, when necessary, take corrective action to remove
microbiological contamination. Corrective action can
include:
correcting all significant deficiencies, providing an
alternate source of water, eliminating the source of
contamination or providing treatment that reliably
achieves at least 99.99% (4-log) treatment of viruses
(using inactivation, removal or a state-approved combination
of 4-log virus inactivation and removal) for each
contaminated groundwater source.
Full compliance with the rule is required by December
1, 2009.
Given the reported lack of correlation of viral contamination
with bacterial indicators, it is not clear that the
new U.S. EPA Ground Water Rule will prove a fully
adequate mechanism to protect public health.
CONCLUSIONS
Seven conclusions are drawn regarding pathogens in
groundwater in the Great Lakes Basin.
1. Very few studies on groundwater quality
in the Great Lakes are available. More data
are needed. In the 1993 Summary Report,
Groundwater Contamination in the Great Lakes Basin,
the Commission recognized the need to reduce
the degree of uncertainty concerning the nature,
extent and significance of groundwater contamination
in the Great Lakes ecosystem (IJC, 1993).
Specifically, the Commission recommended that
special attention be given to “the need for fundamental
research concerning persistence, transport
and fate of pathogens and contaminants in and
through groundwater aquifers.” Studies since then
have improved understanding in this area, but
there is still plenty to be learned. Recent research
on viruses underlines how little is currently known
about the relationship between groundwater and
human disease transmission.
2. Groundwater monitoring should include
coliphage in addition to E. coli. Application of new
methods for microbial monitoring will allow for
prioritization on a science risk-based approach and
result in improvements and protection of the Great
Lakes Basin groundwater.
3. Seasonal assessment of groundwater contamination
during high-rain events and spring melt
should be undertaken. For instance, information
on health risks and occurrence in water (potential
exposure) should be acquired, and with that
information the development of rules for control of
these contaminants may ensue.