SrEPA
Protecting Drinking
Water Sources
EPA810-F-99-015
December 1999
SAFE DRINKING WATER ACT • CELEBRATING 25 YEARS • PROTECT OUR HEALTH FROM SOURCE TO TAP
The 1996 Amendments to the Safe Drinking
Water Act (SOWA) took a major new step in
drinking water protection by mandating that
states perform a source water assessment for each
public water system. States are responsible for
completing assessments for public water systems
in major metropolitan areas, small towns,
schools, restaurants, and other public facilities
that have a well or surface water supply. (Private
wells are not included in this effort.)
After a state's Source Water Assessment Program
(SWAP) is approved by the U.S. Environmental
Protection Agency (USEPA), the state has two
years, with a possible 18 months extension, to
conduct an assessment for each public water
system and make these assessments available to
the public. All assessments must be completed
by 2003.
The source water assessment programs estab-
lished by each state differ, depending on the
nature and threats to the water resources and the
drinking water program priorities in a particular
state. However, each assessment program must
include four major elements:
• delineating the source water protection areas
• conducting an inventory of significant potential
sources of contamination in those areas
• determining the susceptibility of public water
systems to those contamination sources
• releasing the results of the determinations to
the public
Following successful completion of these ele-
ments for each assessment, communities can use
the resulting information to identify priority
actions for protecting their drinking water
sources.
SOURCE WATER ASSESSMENTS
The four assessment steps are described in more
detail below.
Step 1: Delineate the source water
assessment area
For each ground water well or surface water system
that supplies public drinking water, states must
delineate and map the boundaries of each protec-
tion area.
For ground water systems, states commonly use
available information about ground water flow and
recharge to determine the source water protection
area around a well or well field.
For surface water systems drawing water from a
stream, river, lake, or reservoir, the land area in the
watershed upstream of the intake is identified on a
map. A topographic map is used to identify the
perimeter of the area that provides water to the
water system's intake. Some states plan to divide
the watershed area into segments — areas that are
closest to the intake where most types of contami-
nation sources may be found to be significant, and
other more distant areas. The entire watershed area
up to the state's boundaries is required to be
delineated and mapped, but the level of detail in
the inventory of potential pollution sources and the
susceptibility determination can vary in the different
segments. Coordination across state boundaries is
encouraged where appropriate.
Step 2: Conduct an inventory of potential
sources of contamination
In the second step of an assessment, the state identi-
fies the significant potential sources of pollutants that
could contaminate the water supply. This inventory
usually results in a list and a map of facilities and
activities within the delineated area that may release
contaminants into the underground water supply (for
wells) or the watershed of the river or lake (for
surface water sources).
Some examples of the many different types of
potential pollutant sources include landfills, under-
ground or above-ground fuel storage tanks, residential
or commercial septic systems, urban runoff from
streets and lawns, farms and other entities that apply
pesticides and fertilizers, and sludge disposal sites.
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Step 3: Determine the susceptibility of the
water supply to contamination
In the third step — the susceptibility determination - the
state combines the inventory results with other relevant
information to decide the likelihood of contamination of
the water supply by the identified significant potential
sources of contamination. This critical step makes the
assessments useful for communities. It helps local
decision-makers consider priority approaches for protect-
ing the drinking water supply from contamination. Some
states prioritize the potential for contamination from the
specific potential contamination sources or to individual
chemicals that could pollute the water. Other states
assign a susceptibility ranking of high, medium, or low to
the water source.
Step 4: Provide the assessment results to the
public
After the state completes the assessment for a particular
water system, it will summarize the information for the
public. Such summaries will help communities better
understand the potential threats to their water supplies
and identify priority needs for protecting the water from
contamination. This summary information must be
included in water systems' Consumer Confidence Reports
(annual water quality reports). Local communities,
working in cooperation with local, regional, and state
agencies, can use the information gathered through the
assessment process to create a broader source water
protection program to address current and future threats
to the quality of their drinking water supplies.
SOURCE WATER PROTECTION
While source water protection was not specifically
mandated by SDWA, USEPA and its partners encourage
states, tribes, and communities to use the information
from source water assessments to protect the delineated
source water protection areas from identified pollution
sources of major concern. Using a partnership approach,
community groups and local officials can plan how to best
manage those identified potential sources and prevent
new contaminant threats in the source water area.
Many source water protection areas will include multiple
jurisdictions, i.e., the city or county where the source
water intake or wellhead is located, and other towns,
counties, or states upstream or upgradient from the
public water system. Local political authorities may be
able to adopt protection measures within their jurisdic-
tion, but to achieve effective protection beyond their
boundaries, they will usually have to work with neighbor-
ing jurisdictions or federal or state authorities.
Communities use a wide array of different source water
protection methods to prevent contamination of their
drinking water supplies. One management option
involves regulations, such as prohibiting or restricting
land uses that may release contaminants in critical source
water protection areas. Along with regulations, many
communities hold local events and distribute .information..
to educate and encourage citizens and businesses to
recycle used oil, limit their use of pesticides, participate
in watershed cleanup activities, and a multitude of other
prevention activities. Another aspect of a source water
protection program can be the purchase of land or the
creation of conservation easements to serve as a protec-
tion zone near the drinking water source. For an effective
protection program, communities should consider using a
variety of prevention measures.
To assist their efforts to protect areas which surround
surface water sources of drinking water, local authorities
can look to Section 303 of the Clean Water Act. This
section requires each state to review its water quality
standards every three years. The review must consider
the "use and value" of the water as a drinking water
supply. States that adopt water quality standards to
protect all public water supplies and prospective supplies
can enforce these standards under state and federal law
to control pollution.
To augment local ground water protection efforts, some
states use ground water quality standards that work much
like the Section 303 program for surface water. Some
states also use a permit program to regulate pollution that
can contaminate ground water. The federal Under-
ground Injection Control (UIC) program regulates the use
of wells as a means to dispose of waste, and the Resource
Conservation & Recovery Act (RCRA) regulates the
management of hazardous and non-hazardous waste that
can contaminate ground water.
For More Information:
For further information on your state's source water
assessment program and how to participate, contact the
agency in your state that is managing the program. Call
the USEPA Safe Drinking Water Hotline at 1-800-426-
4791 or look at the web page at www.epa.gov/safewater/
protect.html for more information, state contacts, and
links to other organizations that may be active with
source water protection in your area. Your local water
supplier may also have more information about opportu-
nities to become involved in the source water assessment
process. You can call the phone number on your water
bill or contact your local health department for informa-
tion on your water supplier.
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