United States
Environmental Protection
Agency
Office of Water
(4606)
EPA 816-F-00-025
May 2000
Community Involvement in
Drinking Water
Source Assessments
Do you know where your
community s drinking water comes
from?
What are the major threats to your
drinking water quality?
Community members and civic or youth
groups can help answer these questions and
use the information to protect their drinking
water sources. By working with their state's
program to assess drinking water sources,
community groups can help to identify
potential threats to the quality of their
drinking water. They can also help local
officials develop and implement a plan of
action to prevent water quality problems.
Your state is now
required to assess all the
ground water and surface
water sources that supply
water to public water
systems, and you can be
involved in the process.
These assessments will
identify the major
potential sources of
contamination to drinking
water supplies, and will
determine how susceptible
are to contamination. The
This fact sheet explains the four
steps of source water
assessments ; how communities
can participate in the assessment
process; and how communities
can utilize assessment
information for source water
protection . Downloadable
provided to the public to help communities
plan for protection activities.
Each state is moving forward to implement
assessments of its public water systems, as
required under the federal Safe Drinking Water
Act. Assessments must be completed by 2003
for every public water system—for major
metropolitan areas and the smallest towns,
including schools, restaurants and other public
facilities that have wells or surface water
supplies. Assessments will not be conducted
for drinking water systems that have less than
fifteen service connections or that regularly
serve less than twenty-five individuals, since
these are not considered public water systems.
SOURCE WATER ASSESSMENTS
The source water assessment
programs created by states
differ since they are tailored to
each state's water resources and
drinking water priorities.
However, each assessment must
include four major elements:
the water systems
results will be
• delineating (or
mapping) the
source water
assessment area
conducting an inventory of
potential sources of
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contamination in the
delineated area
• determining the susceptibility
of the water supply to those
contamination sources
releasing the results of the
determinations to the public
These steps are described in more detail
below, with information on how citizens and
organizations can join in the assessment
process.
STEP 1: DELINEATE THE SOURCE WATER
ASSESSMENT AREA
For each ground water well or surface water
intake that supplies public drinking water,
the land area that could contribute water and
pollutants to the water supply must be
delineated or mapped. Significant potential
sources of contamination will then be
identified in this delineated area during
Step 2 of the assessment process.
For ground water supplies, states commonly
use information about the flow of
underground water to delineate source water
assessment boundaries. This results in a map
of land areas where, if pollutants are spilled
or discharged on the surface, they could filter
through the soil to the ground water and be
drawn into a particular well. Some states
may use a simpler mapping approach, by
drawing a circle of a certain radius around
the well.
For a community that uses surface water
from a stream, river, lake or reservoir, the
land area in the watershed upstream of the
intake is identified on the map. A watershed
boundary is drawn using a topographic map,
and includes the land areas where rain or
melted snow flows over or through the
ground and eventually enters the water
source upstream of the water system's
intake.
Watershed
to Stream C
Source Water Intake
Some states plan to divide the watershed area
into segments—areas closest to the intake
where most types of contamination sources
can impact the water supply, and other more
distant areas. The entire watershed up to the
state's boundaries is required to be delineated,
but the inventory of potential pollution sources
may be more detailed in segments that are
closer to the intake.
After the state has completed its assessment
for a water system, the community may decide
to undertake protection efforts for targeted
sources of contamination. An initial step could
be to expand upon the state's delineation
process. Particularly for smaller ground water
systems, where states may not have the
resources to conduct a detailed delineation,
additional scientific methods can be used to
more accurately delineate the area that
contributes ground water to the well.
Community members can seek assistance from
the environmental sciences, geology or
engineering departments of local colleges, or
from environmental consulting firms to assist
in creating more detailed delineations.
Sometimes these services are provided by
professors, graduate students or local firms for
a reduced fee or none at all. In addition, local
water resource information is often available
from other sources such as the federal Natural
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Resource Conservation Service, the United
States Geological Survey, and the state's
Cooperative Extension Service.
STEP 2: CONDUCT AN INVENTORY OF
POTENTIAL SOURCES OF CONTAMINATION
Community groups can become especially
involved in the second step of an assessment-
-identifying 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 ground 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, underground or above-ground fuel
storage tanks, residential or commercial
septic systems, storm water runoff from
streets and lawns, farms that apply pesticides
and fertilizers, and sludge disposal sites.
Some states are asking communities to
conduct the inventory themselves, in order to
obtain detailed information about potential
contaminant sources. Others will use
computer databases and focus the inventory
on land uses and activities that are currently
mapped or regulated. Although this
approach may not address sources of
contaminants that are not currently
regulated, such as smaller livestock areas or
auto salvage yards, the database inventories
could include industries and sewage
treatment plants that discharge wastewater,
hazardous waste sites, mining operations,
particular land use categories (such as
industrial, agricultural and urban areas), and
various facilities that have environmental
permits.
Community groups such as watershed
organizations, local environmental committees
or scout troops can enhance the
Non-point Sources
Surface Water ^Industry
Protection Area Sewage «-
Treatment
., ^ Plants Qrv-aite
Septic
-^ Public Drinking Systems
Water Reservoir
_
"
state's assessment by conducting site-specific
inventories of potential pollutant sources that
may not be on state databases or maps. Local
inventories may provide information on
abandoned dump sites, businesses with septic
tanks or floor drains such as dry cleaners or
car repair shops, pesticide mixing and storage
areas, golf courses, and other land uses that
may release pollutants to ground water or
surface water. Community groups can
coordinate their local inventory with the state's
assessment process or can enhance a
completed assessment with a more detailed
inventory.
A helpful document to aid community groups
is EPA's "Drinking Water Contaminant Source
Index," which is a list of potential contaminant
sources and the pollutants they can release.
You can find this publication at
www.epa.gov/safewater/swp/sourcesl .html on
the EPA web site.
STEP 3 - DETERMINE THE SUSCEPTIBILITY OF
THE WATER SUPPLY TO CONTAMINATION
For the susceptibility analysis, the state
combines the inventory results with other
relevant information to decide how likely will a
water supply become contaminated by
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identified potential sources of contamination.
This critical step makes the assessments
useful for communities, since it provides
information that local decision-makers may
use to prioritize approaches for protecting
the drinking water supply. Local information
provided to the state by local community
groups about contaminant sources, water
resource characteristics or environmental
management practices may be used in the
susceptibility determination process. Some
states prioritize the potential for
contamination from identified potential
contamination sources or specific chemicals
that could pollute the water. Other states
assign susceptibility rankings of high,
medium or low to the water sources.
STEP 4: RELEASE THE ASSESSMENT
RESULTS TO THE PUBLIC
After a state completes the assessment of a
particular water system, it will summarize the
information for the public. Such summaries
help communities understand the potential
threats to their water supplies and identify
priority needs for protecting the water from
contamination. States will make the
assessment summaries available to the public
in a variety of ways. Some states plan to
convene public workshops, while others will
have copies available in public libraries and
from local government offices or water
suppliers. Many also plan to post the
assessment summaries on the Internet. The
results of the assessments will also be
included in the annual water quality reports
that community water systems are required
to prepare for their customers. Community
groups can convene local meetings to discuss
the results and begin the process of
protecting the drinking water source.
SOURCE WATER PROTECTION
Whether using the state's assessment or
expanding it into a more detailed local
assessment, communities can use information
gathered through the assessment process to
create a broader source water protection
program. Community groups and local
officials, working in cooperation with local,
regional and state government agencies can
plan how to manage identified potential
contamination sources and prevent new
contaminant threats in the source water
assessment area.
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 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 creation of conservation
easements to serve as a protection zone near
the drinking water source. For an effective
protection program, communities should
consider using a variety of prevention
measures.
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. Look at the
EPA web page at
www.epa.gov/safewater/protect.html or call
the EPA Safe Drinking Water Hotline at
1-800-426-4791 to find more information and
state contacts. The web page also lists other
organizations that may be active with source
water assessments and protection in your area.
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Your local water supplier may also have
more information about opportunities 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 information on
your water supplier.
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