&EPA
United States
Environmental Protection
Agency
Office of Water (4606)
Washington, DC 20460
EPA816-F-98-013
August 1998
Report Findings
Ground Water Quality in the United States
Ground water is a vital national resource. In many parts of
the Nation, ground water serves as the only reliable source of
drinking water. Unfortunately, this vital resource is vulnerable
to contamination resulting from human activities, and
increasing numbers of ground water contamination problems
are being discovered throughout the country.
This report summarizes major sources of ground water con-
tamination and the activities that are being implemented to .
protect this valuable resource for future generations. Most of
this information was obtained from reports submitted in
1996 to the U.S. Environmental Protection Agency (ERA) by
States, American Indian Tribes, and Territories in fulfillment of
requirements set forth in Section 305(b) of the Clean Water
Act. These reports, referred to as the "Section 305(b)
reports," identified contaminant sources and the associated
contaminants that threaten the integrity of State, Tribe, and
Territory ground water resources. Information from the
Section 305(b) reports are combined into a National Water
Quality Inventory: 1996 Report to Congress.
What is Ground Water?
First and foremost, ground water is water that is out of
sight, below the land surface. Because ground water is
unseen, it is commonly misunderstood. Many people
envision ground water as flowing in underground rivers.
Only in rare cases, such as places where caverns exist,
does ground water move in that fashion. Normally,
ground water moves slowly through open spaces between
sand grains below the earth's surface. Subsurface geologic
materials that provide storage for ground water are called
aquifers.
Water enters aquifers as precipitation falling to the earth
that does not evaporate or get taken up by plants and
trees, but rather seeps into the soil of our yards, parks,
and other unpaved areas, filling the open spaces below
the ground surface. This water moves at slow rates, often
at only fractions of a foot per day, and is discharged to
surface water bodies as part of the hydrologic cycle.
Hydrologic Cycle
Is Ground Water Important?
Although 75% of the earth's surface is covered by water,
less than 1 % is fresh water that is available for our use. It
has been estimated that more than 95% of the world's
fresh water reserves are stored in the earth as ground
water.
Ground Water Flow Through the Subsurface
Distribution of Water on Earth's Surface
Sand
Grains
Open
Spaces
Freshwater
Available for Use
0.52%
Ice Caps and Glaciers 1.97%
Other 0.01%
Surface Water 4% I
-------
In the United States, ground water is used for agricultural,
residential, industrial, and commercial purposes. Ground
water provides water for drinking and bathing, irrigation
of croplands, livestock watering, industrial and commer-
cial uses, and thermoelectric cooling applications. In
1990, ground water supplied 51% of the Nation's overall
population with drinking water. In rural areas of the
Nation, ground water supplied 95% of the population
with drinking water.
Ground water is also often directly connected to rivers,
streams, lakes, and other surface water bodies, with water
flowing back and forth from one resource to the other.
In some areas of the country, ground water contributes
significantly to the water in streams and lakes. The quality
of the ground water can have an important effect on the
overall condition of the surface water and its use.
It is evident that ground water is a very important
resource. Preserving the quality of our ground water
resources ensures that our needs as a Nation Will be met
now and into the future.
Is Our Ground Water Contaminated?
Prior to the mid-1970s, it was thought that soil provided
a protective "filter" or "barrier" that stopped the down-
ward movement of contaminants spilled on the land sur-
face and thus prevented ground water resources from
being contaminated. However, the discovery of pesticides
and other contaminants in ground water showed that
ground water resources were indeed vulnerable to con-
tamination resulting from human activities. The potential
for a contaminant to affect ground water quality is
dependent upon its ability to move through the overlying
soils and reach the underlying ground water aquifer.
Ground water contamination is most common in highly
developed areas, agricultural areas, and industrial com-
plexes. Ground water contamination is usually found in
relatively well-defined, localized "plumes" originating
from specific sources such as leaking underground
storage tanks, on-site disposal systems, spills, landfills, or
industrial facilities. Contamination also occurs as a general
deterioration of ground water quality over a wide area
due to diffuse nonpoint sources, such as agricultural fertil-
izer and pesticide applications, and urban runoff. When
large areas are degraded, it makes it difficult to specify
the exact sources of contamination.
Sources of Ground Water Contamination
Ground Water Movement
»• Intentional Input
>• Unintentional Input
-------
Frequently, ground water contamination is discovered
long after it has occurred. One reason for this is the slow
movement of ground water through aquifers, sometimes
moving as little as fractions of a foot per day. Contami-
nants in the ground water may persist for many years. In
some cases, contaminants introduced into the subsurface
decades ago are only now being discovered. This also
means that the environmental management practices of
today will have effects on ground water quality well into
the future.
What Are The Most Common Sources
of Ground Water Contamination?
The three most common sources of ground water
contamination are leaking underground storage tanks,
landfills, and septic systems. These findings are based on
data reported by States in their 7996 Water Quality
Reports. States also indicated that fertilizer applications,
pesticide applications, agricultural chemical facilities, and
agricultural activities were sources of potential ground
water contamination. When these latter categories are
aggregated, it becomes clear that agriculture also consti-
tutes a major source of ground water contamination.
Leaking Underground Storage Tanks (USTs). Although
underground storage tanks are found in all populated
areas, they are generally most concentrated in heavily
developed urban and suburban areas. USTs are primarily
used to hold petroleum products such as gasoline, diesel
fuel, and fuel oil. Because they are buried underground,
leakage can be a significant source of ground water con-
tamination that may go undetected for long periods of
time.
Ground Water Contamination as a Result
of Leaking Underground Storage Tanks
Organic chemicals associated with petroleum products are
one of the most common ground water contaminants.
The most significant effects generally occur in the upper-
most aquifer, which is frequently used by homeowners of
private wells. Organic chemicals threaten the use of
ground water for human consumption because some of
them are known to cause cancer even at very low concen-
trations.
The primary causes of leakage in USTs are faulty installa-
tion and the corrosion of tanks and pipelines. As of March
1996, more than 300,000 releases from USTs had been
confirmed. EPA estimates that nationally 60% of these
leaks have affected ground water quality, and, in some
States, the number is as high as 90%.
The number of new releases continues to outpace the
number of sites where cleanup has been completed. EPA
anticipates that the total number of confirmed releases
could reach 400,000 in the next several years. After this
peak, EPA expects fewer releases as LIST owners comply
with EPA's release prevention and detection requirements.
EPA seeks to prevent another generation of leaking USTs
by working to ensure that the regulatory requirements for
upgrading, replacing, or closing tanks are met. Where
leaks have already occurred, EPA is promoting cleanup
activities at the sites posing the greatest risk to human
health and the environment.
Landfills. Landfills, generally used to dispose of municipal
and industrial wastes, are one of the most significant
sources of ground water contamination. This can be,
attributed to the fact that landfills historically have been
sited on lands considered to have no other useful purpose.
The potential for ground water contamination at these
sites was rarely considered in the site selection.
Unlined abandoned sand and gravel pits, old strip mines,
marshlands, and sinkholes were often used for landfills. In
many cases, ground water was very near the land surface,
and the potential for ground water contamination was
high. Although regulations involving landfills have
changed dramatically, past practices continue to threaten
ground water quality.
The two most common types of landfills are those which
dispose of municipal and industrial wastes. Although a
municipal landfill may contain some industrial wastes, the
most frequently disposed wastes are household products,
such as paper products, diapers, plastics, and cleaning
products. Materials disposed in industrial landfills are
generally site specific. Common materials include plastics,
metals, fly ash, sludges, coke tailings, foam containers,
and construction materials. The possible ground water
contaminants include metals, sulfates, nitrates, and
organic chemicals.
Recognizing the problems associated with old, inactive
landfill sites, States and the Federal government are taking
action to ensure that current and future landfills are less
-------
of a threat to ground water. Federal requirements under
the solid waste laws address siting and operating con-
cerns. The potential for ground water contamination can
be reduced if the landfill is sited in an area with clay soil,
or with a clay or plastic liner, or in locations where the
ground water aquifer is not immediately below the land-
fill. Furthermore, active landfills can be required to be
licensed to accept only certain types of wastes. In some
States, landfills licensed to accept municipal wastes and/or
special wastes are secure landfills with leachate collection
systems and treatment, thereby greatly reducing the risk
of ground water contamination.
Ground Water Contamination as a Result
of Unlined Landfill Disposal
Unlined Landfill
Septic Systems. Septic systems include buried septic tanks
with fluid distribution systems, or leachfields. Designed to
release fluids or wastewaters into constructed permeable
leach beds, septic systems rely on biological organisms
and gravity flow to treat the wastewater. These systems
are commonly used for domestic management of sewage
and liquid household wastes.
A variety of waste fluids are disposed of in septic systems
and, as a consequence, the potential for ground water
contamination is high. Ground water may be contami-
nated when the septic systems are poorly designed or
constructed and/or improperly used, located, maintained,
or abandoned. Private wells located near septic systems
and leachfields are at a higher risk of becoming contami-
nated.
Typical contaminants from household septic systems
include bacteria, nitrates, and viruses from human wastes;
phosphates from detergents; and other chemicals that
might originate from household cleaners. Contaminants
from commercial and industrial facilities may include
metals and organic chemicals.
Most municipal, commercial, and industrial facilities that
provide a service or manufacture a product generate
process wastes. Sometimes the wastes end up in shallow
disposal systems, particularly in unsewered areas.
Examples of other shallow disposal systems include:
industrial waste disposal wells, motor vehicle waste
disposal wells, cesspools, dry wells, improved sink holes,
and agriculture and storm water drainage wells. EFft is
proposing to add requirements to its existing Under- *
ground Injection Control program to ensure that high risk
shallow injection wells do not endanger underground
sources of drinking water. This step-wise approach consists
of (1) a proposed rule creating additional requirements for
three types of high-risk shallow injection wells in ground
water-based source water protection areas: industrial
waste disposal wells, motor vehicle waste disposal wells,
and large-capacity cesspools; and (2) further study of
other types of shallow injection wells not covered in the
proposed rule to provide the factual basis for further regu-
latory action, as necessary. However, the problem is too
vast to be effectively managed solely by the traditional
State and Federal regulatory approach. Thus, most solu-
tions will continue to be implemented at the local govern-
ment level.
What is the Cost of Ground Water
Contamination?
As more and more areas of ground water contamination
are discovered, Americans are becoming increasingly
aware that contaminated ground water is both difficult
and expensive to clean up. There are both direct and indi-
rect costs associated with contaminated ground water.
Direct costs usually result from cleanups and associated
activities and are usually more quantifiable. Indirect costs,
related to the effects of contaminated ground water on
the public, are less tangible and may be more difficult to
determine and quantify.
Direct costs (e.g., legal fees for cleanup, investigative,
engineering, and operational activities) can be estimated
and have proven to be very high. Treatment to remove
contaminants from ground water has cost individual
businesses thousands, and sometimes millions, of dollars
every year. Despite the staggering monetary direct costs,
indirect costs may be of even greater concern. Indirect
costs include the potential for increased health risks,
increased public concern, and decreased availability of
fresh water and may prove to be more costly than the
direct costs.
When both direct and indirect costs are considered, it
becomes evident how expensive it is to clean up ground
water resources that have been contaminated by human
activities. Efforts to compare the costs of post-contamina-
tion cleanup to the costs of preventive ground water
protection have found that there are real cost advantages
to promoting protection of this resource.
What Is Being Done to Prevent Ground
Water Contamination?
Because it is expensive and technologically complex to
clean up contaminated ground water resources, ground
water protection has become the focus of numerous State
-------
and Federal programs. Some of these programs are regu-
latory in nature and restrict or control specific activities
from introducing contaminants onto the land surface,
be/owthe land surface, or into ground water resources.
Two of the most important Federal programs addressing
ground water protection are authorized by the Clean
Water Act and the Safe Drinking Water Act.
Under the Clean Water Act. EPA has provided funding to
the States for over 13 years to develop and implement
ground water strategies and programs. Every State in the
Nation has developed ground water strategies and has
implemented them in many creative ways. Based on an
EPA-wide initiative in the early 1990s, nine States to date
have achieved EPA endorsement of a basic comprehensive
ground water program, and seven other States are in the
process of developing one. These programs have
increased the coordination among State agencies and
increased the consistency in the way State programs focus
on priority ground waters. EPA programs, in turn, have
been seeking to align program priorities with these State
ground water priorities.
Under the Safe Drinking Water Act, EPA is authorized to
ensure that water is safe for human consumption. One of
the most fundamental ways to ensure consistently safe
drinking water is to protect the source of that water. This
law, re-authorized in 1996, requires all States to assess all
source waters for the benefit and protection of all public
water systems. By 2003, States will complete assessments
for the 170,000 public water systems, which for many
such systems, will lead to protection programs. States will
delineate drinking water source protection areas around
public water systems (whether based on ground water,
surface water, or both); inventory all significant potential
sources of contamination; and determine the susceptibility
of public water systems to the contamination sources.
States have many options to develop and implement
Statewide and local protection programs. The options will
address the inventoried contamination sources identified
as threatening public water systems through non-regula-
tory or regulatory measures.
What Actions Are Needed to Complete
a Local Drinking Water Source Assessment?
0
Delineation
Delineate a source water
protection area
Establish Delineation
Areas with Best
Available Data
Inventory
Identify significant
potential sources of
contamination
- Identify contaminants
- Inventory sources of
those contaminants
• Map significant
potential sources
Establish Inventory
Susceptibility
Determinations
Study the hydrology
and geology of the
source water
protection area
- Consider well or intake
integrity
- Look at contaminant
source characteristics '
Determine Susceptibility
of PWS to Inventoried
States, in cooperation with EPA, also implement Wellhead
Protection Programs, Sole Source Aquifer Programs, and
Underground Injection Control Programs. Wellhead *
Protection Programs will likely be operating in all States by
the year 2000, with the goal of protecting all public water
systems based on ground water. Over the last five years,
EPA has been assisting the States, in part, by sponsoring
local ground water protection pilot projects in all 50 States
through various stakeholders. EPA has designated 63 sole
source aquifers nationwide and the Regions reviewed
close to 200 federally-funded projects in 1997 for these
aquifers. The Underground Injection Control Program
protects ground water from all injection wells and has
been focusing in the late 1990s on addressing injections
wells in shallow aquifers.
EPA's programs offer assistance and guidance to States for
the implementation of ground water protection efforts,
but, ultimately, the key to protecting this resource is for
individuals to become knowledgeable about the ways this
resource becomes contaminated and learn how each of us
can protect it.
Where Do You Go For More Information?
For more information about ground water protection,
contact your local water supplier, environmental protec-
tion or health department, or the state office responsible
for protecting your water supply. For more information
about the National Water Quality Inventory: 1996 Report to
Congress, contact
Mr. A. Roger Anzzolin
305(b) Coordinator/Ground Water
U.S. Environmental Protection Agency
Office of Ground Water and Drinking Water
401 M Street, S.W. (4606)
Washington, DC 20460
ANZZOLIN.ROGER@EPA.GOV
202-260-7282
202-401-3041 (fax)
For more information, you may also contact
Safe Drinking Water Hotline
800-426-4791
or visit the Internet sites
http://www.epa.gov/safewater ,
http://www.epa.gov/305b
------- |