mean more competition for water resources and will
applications of different microbial source tracking tech-
change the overall pollution level (less dilution), increase
niques in the Great Lakes region. This is an area of research
short-term impacts (more storms) and decrease the
that will undoubtedly be growing in the future and
carrying capacity to handle the microbial contamination.
providing new tools to more quickly and accurately
determine the sources of fecal pollution responsible for
For microbial contamination even these short-term trends
contaminating drinking and recreational waters in the
are of concern as illness can take place with even short-
term/transient contamination events. In addition, much of
the stress will be more obvious in the summer when more
Sewage Treatment and Urbanization
people will be in, around and near the waterways and use
of the lakes for recreation is high.
The SAB suggests that loading of microbial pathogens into
rivers and into the lakes from sewage discharges, including
viruses and parasites should be estimated in order to
examine the carrying capacity of the waterways and risks.
The SAB suggests that recent hydrodynamic models that are
being investigated for ecosystem predictions should be
Most conventional wastewater treatment facilities, while
examined and ground-truthed for microbial indicator
addressing suspended solids, biological oxygen demand
and in some cases fecal coliform bacteria, provide minimal
reductions of enteric pathogenic viruses and protozoa.
Great Lakes scientists are using multiple regression
Levels between 10 to 100 parasites and viruses per 100
techniques to develop more sophisticated models for
liters can be detected in most secondary effluents (Rose et
predicting beach water quality in Chicago and Milwaukee
al. 2001a) and it can be estimated that as much as one
based on indicator concepts for identification of risk.
million pathogenic organisms per day can be loaded to a
These models include rainfall during the previous 24
water body from a single facility. Greater risk and greater
hours, wind, solar radiation, water temperature, lake stage,
concentrations are seen due to combined sewer overflows
water turbidity and pH. Rainfall, wind and turbidity are
and storm sewer overflows flows, however the data
indicative of the strong influence that storms have on E.
supporting the risk is often not collected.
coli concentrations. At the Milwaukee beach, storm effects
result primarily from sewage overflows into tributary rivers
Little is known in regard to the fate (survival and transport)
that get pushed shoreward by easterly winds. The Chicago
of these types of enteric pathogens in the Great Lakes.
beach is not directly influenced by stream inflows, but
Information is needed so that these data can be used in
storms stir up E. coli laden sand in the breaker zone. Solar
models to address the potential for public exposure on
radiation is a negative term in the model that reflects UV-
beaches and through drinking water systems.
mediated bacterial die-off during bright sunshine. Water
temperature and lake stage represent conditions that lead
to high bacterial concentrations during non-storm periods.
Bacterial populations grow faster in warm water and
The SAB suggests that water quality trends in key waterways
bacteria become more concentrated when lake level falls at
should be explored under various flow scenarios. Storm
the beach in Chicago. These models were evaluated by
events and water quality changes need to be investigated in
comparing predictions of E. coli concentration exceeding
areas where public exposure and health risk may occur.
U.S. EPAs recommended threshold of 235 colony forming
units (cfu)/100mL with measured concentrations. The
The recent report on Confronting Climate Change in the
model correctly predicted 66 of 90 events at the Milwaukee
Great Lakes Region: Impacts on our Communities and
beach and 50 of 57 events at the Chicago beach. Model
Ecosystems (Kling and Wuebbles, 2003) has been released
errors were evenly split between false negatives and false
and has some startling findings in regard to impact on
positives for the Milwaukee beach, but five of the six
water quantity. The suggested changes in water quantity
incorrect predictions for Chicago are ones that would have
will influence the quality of the water as well, but these
led to overprotective actions.
have not been quantified, yet it is clear that these changes
could influence the risk of waterborne disease (Patz et al.
This type of research investigation should be expanded to
2000; Rose et al. 2001b). Some of the predictions include:
other watersheds and improved so that it can address risks
increases in temperatures by the end of the century could
associated with pathogenic microorganisms. This will aid
further the trend of lowering lake levels, and could lead to
in developing a predictive approach for the detection of
more/longer flood and drought cycles; inland lakes and
headwaters in rivers will have lower levels particularly in
the summer; and soil moisture will decrease. This will