Ground Water PSAs
2009 Public Service Announcement
2006 Public Service Announcement
See Also
Drinking
Water Protection
Source
Water Assessment Data and Reports
Contact DEQ
Regional
Office
Water Quality Managers
State
Office
Water Quality Division
Amy Williams
(208) 373-0115
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Water Quality: Source Water Assessments
of Public Drinking Water Systems
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| In 1996, Congress amended the Safe Drinking Water
Act to emphasize the protection of surface and ground water sources
used for public drinking water. The amendments require that each state
that has primacy for its drinking water program develop a plan for
assessing public drinking water sources, conduct assessments on all
public water systems, and make the assessments available to the public.
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| What is a Source Water Assessment? |
| A
source water assessment provides information on the potential contaminant
threats to public drinking water sources. In Idaho, most of those
sources (>95%) are ground
water. Each source water assessment:
- Defines the zone of contribution, which is that
portion of the watershed or subsurface area contributing water
to the well or surface water intake (source
area delineation)
- Identifies the significant potential sources
of drinking water contamination in those areas (contaminant
source inventory)
- Determines the likelihood that the water supply
will become contaminated (susceptibility
analysis)
Each assessment is
summarized in a report
that describes the above information and provides maps of the location
of the public water system, the source area delineation, and the
locations of potential contaminant sources. Idaho began developing
source water assessments in 1999, and in May 2003 met its obligation
under the amendments of the Safe Drinking Water Act by completing
delineations for all 2100+ public water systems that were active
in Idaho as of August 1999. Source water assessments for new public
drinking water systems are being developed as those systems come
online. Each public water system is provided with two copies of
its final assessment report. |
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Source Area Delineation |
| The
delineation process establishes the physical area around a well
or surface water intake that becomes the focal point of the source
water assessment. The process includes mapping the boundaries of
the zone of contribution (the area contributing water to the well
or to the surface water intake) into time of travel zones (zones
indicating the number of years necessary for a particle of water
to reach a well or surface water intake). The size and shape of
the source water assessment area depend on the delineation method
used, local hydrogeology, and volume of water pumped from the well
or surface water intake. |
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Contaminant Source
Inventory |
| This
process involves collecting, recording, and mapping existing data
and geographical information system (GIS) coverages to determine
potential contaminant sources (e.g., gas stations) within the delineated
source water assessment area. The potential contaminant source inventory
is one of three factors used in the susceptibility analysis to evaluate
the overall potential risk to the drinking water supply. The inventory
process goal is to locate and describe those facilities, land uses,
and environmental conditions that are potential sources of ground
water or surface water contamination.
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Susceptibility
Analysis |
| This
process determines the susceptibility of each public water system
well or surface water intake to potential contamination within the
delineated source water assessment area. It considers hydrogeologic
characteristics, land use characteristics, potentially significant
contaminant sources, and the physical integrity of the well or surface
water intake. The outcome of the process is a relative ranking into
one of three susceptibility categories: high, moderate, and low.
The rankings can be used to set priorities for drinking
water protection efforts. |
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| What is a Public Water System? |
| Source
water assessments are conducted by DEQ for public water systems.
To be classified as a public water system, the system must supply
water to at least 25 people or must have at least 15 service connections.
If the system does not meet these requirements, it is considered
a private system.
Public
water systems are divided into three main groups:
- Community:
A public water system that regularly serves year-round residents
(i.e., a system that serves people at their homes; examples include
systems that serve towns or subdivisions).
- Non-community, non-transient:
A public water system that serves at least 25 of the same people,
four or more hours per day, for four or more days per week, for
26 or more weeks (i.e., a system that serves always serves the
same people, but not at their homes; examples include systems
that serve schools or businesses).
- Non-community, transient:
A public water system that does not serve at least 25 of the same
people, four or more hours per day, for four or more days per
week, for 26 or more weeks (i.e., a system that serves different
people all the time; examples include systems that serve campgrounds
or rest areas).
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| What is the Source Water Assessment Plan? |
| With
input from a diverse group of stakeholders and Idaho's Source Water
Assessment Advisory Committee, DEQ completed the Idaho
Source Water Assessment Plan in October 1999, and it was
approved by the U.S. Environmental Protection Agency (EPA) in November
1999.
The Idaho
Source Water Assessment Plan was developed in response to
requirements set forth by the Safe Drinking Water Act Amendments
passed by Congress in 1996. DEQ's source water assessment plan describes
the major components of, and the procedures for, conducting source
water assessments. |
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| The Source Water Assessment Process |
| Source Water Assessments are created based on the
steps outlined in the Idaho Source Water Assessment Plan.
While DEQ conducts most of the assessments, public water systems are
encouraged to take an active role in the assessment of their systems
and may perform all or part of their own assessments if they choose.
DEQ provides assistance to those public water systems that choose
to perform their own assessments to ensure that they meet minimum
requirements set forth by the EPA. |
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How Source Water
Assessments Are Created |
| Creating
a source water assessment is a 10-step process. While some of these
steps are sequential, others (e.g., public participation, managing
data, and working with the system) occur continually throughout
the process. |
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Step
1. Solicit public participation.
Participating in
the planning and implementation phases of the assessment process
provides citizens and local officials with valuable information
to use in local planning and decision making. Participating
in the assessment process may also provide communities with
the incentive to develop locally sponsored source water protection
efforts. |
Steps
2, 3, 4. Collect, analyze, and manage data.
The efficient collection,
analysis, and management of data are essential to the completion
of the source water assessment process. Source water assessments
rely on currently existing information and GIS technology. |
Step
5. Notify the system.
Public drinking
water system personnel are informed when the source water
assessment process is initiated for their system and asked
to participate in the process by providing information, acting
as the lead for the assessment, and reviewing the draft assessment.
The process works best when system personnel participate directly.
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6. Perform the source area delineation.
The delineation process establishes the physical area around
a well or surface water intake that will become the focal
point of a source water assessment. The process includes mapping
the boundaries of the zone of contribution into time of travel
zones.
Contaminant
time of travel calculations, soil characteristics, land use,
and similar information are often estimates based on the results
of previous analyses, information acquired from existing databases,
or both. While the reports are based on the best information
available, report users need to keep in mind that hydrogeologic
information and potential contaminant inventories may not
have been confirmed by on site investigations. |
Step
7. Conduct the potential contaminant source inventory.
This process involves
collecting, recording, and mapping existing data and GIS coverages
to determine potential contaminant sources within the delineated
source water assessment area. |
Step
8. Perform the susceptibility analysis.
This process determines
the susceptibility of each public water system well or surface
water intake to potential contamination within the delineated
source water assessment area. The outcome of the process is
a relative ranking into one of three susceptibility categories:
high, moderate, and low. The rankings can then be used to
set priorities for source water protection efforts. |
Step
9. Make the reports available to the public.
Two copies of the
final source water assessment report are provided to public
water system personnel. Copies of the reports are also available
at the DEQ state office, at the appropriate DEQ regional office,
and on DEQ's
Web site. |
Step
10. Voluntary protection.
Local communities, working in cooperation with state agencies,
can use the information gathered through the assessment process
to create a broader drinking water protection program to address
current problems and prevent future threats to the quality
of their drinking water. more
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How Source Water
Assessments Are Being Updated |
| Existing public water systems are constantly changing:
a new well is added, another is removed, a surface water intake is
added. Assessments are updated as soon as new information is added
to the databases used to generate the assessments. The assessments
shown on the Web site are then updated to reflect these changes. |
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How Source Water
Assessments Are Being Used |
| Source water assessments are the cornerstone for
drinking water protection. Local communities
can use the information gathered through the assessment
process to create a broader source water protection
program to address current problems and prevent future
threats to the quality of their drinking water supplies. The information
acquired from assessments also assists DEQ in overseeing public water
systems. |
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| Drinking Water (Source) Protection |
| Communities
can use source water assessments to implement drinking water protection
plans, programs, and activities. Preventing contaminants from entering
a public water system supply minimizes the problems that can occur
from contaminants in the water supply, such as increased health
risks, expanded drinking water monitoring requirements, additional
water treatment requirements, or expensive environmental cleanup
activities.
In general,
drinking water protection is composed of five steps:
- Delineate the land area to be protected
- Identify potential contaminant sources
- Develop and implement a management plan for the drinking water
protection area
- Plan for the future: develop a contingency plan and plan for
future drinking water sources
The information
for steps 2 and 3 can usually be taken directly from the source
water assessment.
A community can gain
official recognition for its drinking water protection plan by pursuing
state certification through the DEQ. For a community to have its
plan certified, the plan must address eight protection elements
and be technically appropriate. more |
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| For More Information |
| Drinking
Water Protection
Learn
how drinking water protection activities build on source water assessments.
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| EPA
Source Water Assessment Web site |
| EPA
Region 10 Source Water Assessment Web site |
Idaho
Source Water Assessment Plan
(DEQ
Publication, October 1999: pdf 2.4 mb, 200 pages)
Describes how source water assessments are conducted in Idaho.
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Protecting
Drinking Water Sources in Idaho
(DEQ Publication,
August 2000, Revised April 2007: pdf 483 kb, 66 pages)
Provides guidance to parties interested in
protecting drinking water sources in Idaho. |
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