Groundwater in the Great Lakes Basin

Table 2.
Indiana Counties – Septic Systems
County %
Households
with Onsite
Wastewater
Disposal
(Septic)
Number of
Households
with Onsite
Wastewater
Disposal
(Septic)
County Area
(Acres)
Density
of Septic
Systems
(Acres
per septic
system)
% Area with
Soils Having
“Severe
Limitations”
for Septic
Systems
Lake 10.0% 18,274 396,962 21.7 96.0%
Porter 31.0% 14,444 334,267 23.1 83.0%
LaPorte 43.0% 18,002 389,865 21.7 74.0%
Source: Adapted from presentation by Mike Molnar at the IJC Nearshore Workshop, March 2008. Based on
Natural Resources Conservation Service (NRCS) Soil Survey information, calculated by Bill Hostetter,
Soil Scientist in the Indiana NRCS State Office. “Severe Limitations” are based on NRCS criteria, which are
more restrictive than those required by the Indiana State Department of Health.
Percent and number of households with on-site wastewater disposal (septic systems) are from the 1990 Census.
tank and a soil absorption bed. In the tank, solids settle
to the bottom and are partially broken down by bacteria.
The top layer of liquid effluent discharges via gravity
to the soil absorption bed (Wisconsin Department of
Commerce, 1999). The soil absorption bed removes some
pathogens, organic material and suspended solids from
the effluent by physical filtration, aerobic microorganisms
and soil cation exchange capacity. The effectiveness
of the conventional system depends on the permeability
of native soils and the slope and drainage pattern of
the site (Wisconsin Department of Commerce, 1999).
Conventional systems require maintenance and pumping
to ensure that the tank remains watertight and to
remove accumulated solids.
In the Great Lakes region the most attractive sites for
new homes, such as along environmentally sensitive
inlets and inland lakes, have low-permeability soils
and high water tables, making them unsuitable for
conventional, gravity-fed septic systems (Gorman and
Halvorsen, 2006). Homeowners in these areas often
use alternative OWTS technologies and techniques
Case Study: State of Saginaw Bay On-Site Wastewater Treatment Systems
Source: Kart, 2006.
“When a wastewater treatment plant discharges to the Saginaw River, it makes headlines.
When a septic system discharges, there is silence.”
Some homes in Gladwin County, Michigan, have septic systems, but many do not work. Other homes
have no system at all; waste is often dumped directly into ditches. The untreated sewage contaminates
surface and groundwater since it contains pathogens such as E. coli and viruses which are a human health
threat.
This situation is repeated throughout many small towns of the Saginaw Bay region which were built
without sewers and before modern OWTS regulations. In nearby Denmark Township, Tuscola County,
E. coli levels have tested as much as 300 times higher than state water quality standards allow (Kart,
2006). Unfortunately, many occurrences happen in low-income areas, where the resources of residents
(retired and unemployed) are already stretched.
Since the publication of Kart’s article in 2006 the situation has not improved and may even be getting worse
(Ferretti, 2007). A report by Rose, a microbiologist, indicates that the problem may be increasing with
increasing discharge from sewage and septic tanks (Ferretti, 2007). Despite excessive amounts of algae the
Department of Environmental Quality (DEQ) has yet to list Saginaw Bay as impaired (Kart, 2008).
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