See Also
Planning
Grants for Public Water Systems
Forms,
Checklists, and Worksheets for Public Water Systems
Contact DEQ
Regional
Office
Water
Quality Managers
State
Office
Water
Quality Division
Jerri Henry
(208) 373-0471
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Drinking Water:
The Arsenic Standard
and Public Water Systems
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| Concern over the potential effects of long-term,
chronic exposure to arsenic in drinking water has prompted the U.S.
Environmental Protection Agency (EPA) to reduce the drinking water
standard for arsenic from 50 parts per billion (ppb) to 10 ppb, effective
January 26, 2006. The standard applies to most public drinking
water systems in Idaho. |
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| What is Arsenic? |
| Arsenic
is a naturally occurring element found in the earth's crust that
is found most everywhere. It occurs naturally in rocks and soil,
water, air, and plants and animals. There are trace amounts of it
in all living matter.
Approximately
90% of industrial arsenic in the U.S. is used as a wood preservative.
Arsenic is a well-known poison used in the manufacture of agricultural
chemicals such as pesticides, weed killers, and rodenticides. It
is also used in the production of paints, dyes, metals, drugs, soaps,
and semi-conductors.
Arsenic
can be released into the environment through natural activities
such as volcanic action, erosion of rocks, and forest fires, or
through human activities such as pesticide application, improper
disposal of arsenic-containing waste chemicals, agricultural applications,
mining, and smelting. |
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| How Does Arsenic Get into Drinking Water? |
| Most arsenic in drinking water comes from natural
rock formations. Water that encounters rock formations can dissolve
arsenic and carry it into underground aquifers, streams, and rivers
that may be used as drinking water supplies. Arsenic deposited on
the ground from industrial or agricultural uses tends to remain in
the top few feet of soil for a long time and is not likely to have
a significant impact on most aquifers. When dissolved in water, arsenic
has no smell, taste, or color, even at high concentrations. |
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What
Are the Health Risks of Water Above the New Arsenic Level? |
Arsenic
in drinking water, soil, air, and food does pose health risks. Although
a very high dose (60,000 micrograms) of arsenic can be lethal, the
amount of arsenic in drinking water is very small by comparison
and any health effects are the result of prolonged exposure over
a period of years.
The more
your customers are exposed to arsenic over time, the higher the
risk becomes for experiencing health effects. Different people may
have different responses to the same exposure to arsenic, depending
on dose, duration, general health, age and other factors, so there
is no way to know exactly what may happen in any given case. Reducing
the amount of arsenic allowed in drinking water will lessen your
customers' exposure and reduce risk of adverse health effects.
For more
information on the health impacts of arsenic in drinking water,
visit EPA's Web site on Drinking
Water and Health: What you need to know. |
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| How Does the Standard Affect Public Water
Systems in Idaho? |
The standard applies to all 750 Community
Water Systems (CWS) and to 245 Non-transient Non-community Water Systems
(NTNCWS) in Idaho that exceed 10 ppb of arsenic. The deadline for
complying with the new arsenic rule was January 23, 2006.
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| How Has DEQ Helped Public
Water Systems Comply? |
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In fall 2002, DEQ sponsored a
free arsenic sampling event for NTNCWS to help determine the
level of arsenic in their systems and potential treatment needed.
A total of 101 systems took advantage of this opportunity. |
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Also in 2002, DEQ served as an information
resource for public water systems that applied to participate
in Round 1 of EPA's Arsenic Treatment Demonstration Project.
Round 1 was aimed at demonstrating commercially-ready treatment
technologies or engineering solutions for removing or reducing
arsenic for small systems. Twelve Idaho systems applied. The
city of Fruitland, Idaho, was one of only 18 project sites selected
nationally to participate in the project. |
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Under DEQ's drinking
water planning grant and drinking
water construction loan programs, several municipal water
systems have received funding to evaluate options for addressing
arsenic contamination of drinking water. |
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In 2003, DEQ once again served as a resource
for public water systems interested in participating in Round
2 of EPA's Arsenic Treatment Demonstration Project. |
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DEQ also worked with water systems
to facilitate exemptions that will provide qualified systems
more time to determine how they will comply with the arsenic
rule and fund the necessary treatment of their drinking water
supplies. |
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Lastly, DEQ offered an option for system owners to enter into a Compliance Agreement Schedule with DEQ. The Compliance Agreement schedule enabled water systems that entered into the Compliance Agreement Schedule by January 23, 2006, to avoid accruing violations and penalties. |
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| For More Information |
An Evaluation of Potential Associations between Arsenic Concentrations in Ground Water and 2000 - 2004 Cancer Incidence Rates in Idaho by Zip Code
(pdf on Cancer Data Registry of Idaho Web Site) |
Arsenic and Your Distribution System
(U.S. EPA Fact Sheet, April 2007: pdf 575 kb, 4 pages)
Information to help water system owners and operators understand and respond to issues that may arise with arsenic in the distribution system, or with distribution system concerns resulting from the installation of arsenic treatment. |
Arsenic
in Drinking Water (EPA Web Site) |
Arsenic
in Drinking Water Rule (on EPA Web Site) |
Arsenic
Trade Show (on EPA Web Site)
An interactive tool from EPA to assist small drinking water utilities
with decision trees and tips for evaluating and selecting treatment. |
| Fact
Sheet and Quick
Reference Guide to the Arsenic Drinking Water Rule (on
EPA Web Site) |
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Information
for Idaho Water Systems Concerning Arsenic in Drinking Water (Environmental
Finance Center, Boise State University, Web Site) |
Geochemical
and Descriptive Data for Sedimentary Aquifer Materials in Southwestern
Idaho
Study by the U.S. Geological Survey in cooperation with DEQ seeks
to provide a first step toward understanding where arsenic is stored
in the hydrologic environment and how it is being mobilized in ground
water. This information, along with other interpretive work planned
for future studies, is intended to be used to develop strategies to
prevent or mitigate arsenic contamination of drinking water supplies.
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