Groundwater in the Great Lakes Basin

BACKGROUND
The first underground septic systems were used by the
French in the 1870s (CDC, 2006). By the mid-1880s,
two-chamber, automatic siphoning tank systems,
the ones commonly used today, were installed in the
United States (CDC, 2006). More than a century later,
these on-site wastewater treatment systems (OWTS)
are proliferating in the Great Lakes Basin due to
expanding and widely distributed populations that
lack access to centralized sewer systems (CDC, 2006).
(See Table 1.) The term on-site wastewater treatment
system refers to systems utilizing sub-surface disposal.
They range in size from individual single-family
systems to systems serving businesses, commercial
developments, institutions or groups of homes with
flows up to 10,000 gallons per day.
Today’s residential septic tanks are typically made of
concrete, steel, fiberglass, polyethylene or other approved
material, which hold 1,000 gallons or more of wastewater
(CDC, 2006). In areas with on-site disposal systems, most
of the liquid waste will enter the groundwater (Howard,
2002). In Bermuda, for example, septic discharge provides
35% of the total aquifer recharge (Howard, 2002).
NUMBER OF SEPTIC SYSTEMS
One-quarter to one-third of homes in the U.S. use septic
systems (CDC, 2006), and approximately one-third of
new residential homes in the U.S. are constructed with
septic or other forms of on-site wastewater treatment
systems (Rafter, 2005). In Canada many rural homes also
rely on septic systems (Canada Mortgage and Housing
Corp., 2007). In Michigan approximately 50% of new
homes are constructed with septic tanks (Fishbeck,
Thompson, and Carr and Huber Inc., 2004). In Minnesota
it is estimated that approximately 86% or 535,000 homes
rely on on-site systems; of these, an estimated 144,000
were failing and 64,000 posed an imminent threat to
public health and safety (McDilda, 2007). Septic tank
deterioration is a major concern. In Door County,
Wisconsin, 80% to 90% of tanks in the area come out of
the ground looking like Swiss cheese (Dayton, 2008). It
is estimated that $1.2 billion is needed in order to address
the state’s septic problems and an additional $3.4 billion
to address sewer and wastewater treatment plant issues
(Wallace, Nivala and Brandt, 2006).
Maryland is estimated to have 420,000 septic tanks
with an additional 1,000 installed each year (Murray,
2004). In 2004 a bill was passed implementing a
$30 annual fee for homeowners with septic tanks.
Table 1.
Number of On-Site Systems by State and Province
Source: Adapted from presentation by Ric Falardeau
at the Science Advisory Board’s Groundwater Consultation, Lansing, Michigan, March 2006.
State /
Province
Total
Number of
Systems
Permits per
Year
Illinois ND ND 50,000
Indiana 800,000 14,500 50,000
Michigan 1,400,000 35,000 455,000
Minnesota 535,000 17,500 35,000
New York ND ND 200,000
Ohio 1,000,000 20,000 110,000
Ontario 1,200,000 2 25,000 3 ND
Pennsylvania ND ND 25,000
Wisconsin 680,000 21,000 110,000
Number of Systems in
Counties that Border the
Great Lakes 1
56
1
In the U.S. 100% of the 67 county or regional agencies that border a Great Lake and that regulate OWTS were surveyed.
In Ontario, the only province bordering the Great Lakes, one office was surveyed at each level within a bordering region:
a regional (unincorporated area), township or county level and/or municipal level (building department) office. The total
U.S. and Canada survey attempted 80 offices of which 74 (93%) responded. Adapted from Gorman and Halvorsen, 2006.
2
Estimate; actual number unknown (Doug Joy, personal communication at the Syracuse Groundwater Consultation).
3
Number of new or replacement systems per year; 5% are advanced technology (Doug Joy, personal communication).
ND – No data