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Apr-17-2007 11:29printcomments

Arsenic Contamination in Oregon, Washington Wells Raises Concerns

The health concern about arsenic is primarily related to its role as a carcinogen, even at extremely low levels, causing skin and possibly other cancers.

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(CORVALLIS, Ore.) - Public concerns about high levels of arsenic in well water have prompted a recent and continuing testing program in the area around Sweet Home, Ore., and may raise a warning flag for other areas of the state that could also face problems with this toxin due to geology or land use practices.

In a recent round of testing done near Sweet Home, almost one-fourth of the well water samples showed levels of arsenic now considered unsafe by EPA standards.

Some areas in the Tualatin Basin near Portland; the Ontario region in Eastern Oregon; areas around Creswell and Cottage Grove south of Eugene; and much of the Puget Sound area are also known to have some concerns about high groundwater levels of arsenic.

Officials at Oregon State University who operate the Extension Well Water Program say people should avoid a panic or emotional reaction to the issue of arsenic in water.

Levels considered safe have been tightened recently and health risks are still unclear, said Gail Andrews, an assistant professor of bioengineering and OSU water quality educator – but consumers still should be aware and informed on the safety of their water and take action if necessary.

“Arsenic, in particular, is a poison that tends to have an emotional stigma attached to it,” Andrews said. “Probably a third of the calls I get are about this one issue. But there are ways water can be treated, people can drink bottled water, it’s not a problem using this water for bathing and many other uses, and the science is still somewhat uncertain about just how much of a danger arsenic is at very low levels.”

The health concern about arsenic is primarily related to its role as a carcinogen, even at extremely low levels, causing skin and possibly other cancers.

Safety levels for public water supplies are measured in parts per billion – a level that’s about 1,000 times more stringent than some other common water contaminants such as nitrates.

Recently, the allowed level for public water supplies was lowered from 50 to 10 parts per billion.

“Worth noting is that these are standards for accumulated lifetime exposure, meaning you drink primarily just that water from a single source for your entire life,” Andrews said. “Needless to say, if you moved a lot or had slightly higher levels at something like a vacation home you just visited occasionally, that would be much less of a concern.”

Arsenic is found naturally in some geologic formations, especially in wells that tap into deeper formations, and can vary over time.

Sometimes levels are also related to past agricultural practices and use of pesticides.

Maps are available outlining areas in the state where arsenic tends to be more of a concern, and it’s been known for some time that the Sweet Home area was one of the hot spots.

At the recent testing around Sweet Home, which was done with the collaboration and support of the local Rotary Club, 84 well water samples were submitted.

Arsenic was not detected in 53 samples; found at levels between 4-10 parts per billion in 11 samples; was more than 10 ppb in 15 samples and more than 50 ppb in five samples. The highest level detected was 175 parts per billion.

As a follow up, another program is planned for community education and bringing in well water samples in Sweet Home on Thursday, May 10th, from 6:00-8:00 PM in the meeting room of the Sweet Home School Board. Tests will be done for arsenic, nitrate levels and bacteria.

Many people do not realize, Andrews said, that there are no laws regulating standards for private wells – and often homeowners are not even aware they may have water problems with arsenic or other common contaminants such as nitrates or E coli.

The burden is on the individual home owner, landlord or renter to be aware of potential well water risks and take steps to monitor or prevent them.

Testing for arsenic is inexpensive, done by many private companies for about $25.

Treatments for arsenic contamination are available but often expensive – they can range from $3,000 to $8,000 for treatments with existing technology.

Some new systems for treatment that are far less expensive may soon be available when testing is complete, Andrews said.

More information on this and many other well water issues can be obtained on the web at or by calling 541-737-6294.

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Cliff Treyens April 18, 2007 5:41 am (Pacific time)

The National Ground Water Association also provides an excellent Web site with much information about water well maintenance, water testing and water quality issues. It can be viewed at It is worth well owners spending a few hours reviewing this Web site to see the very practical information listed there. -- Cliff Treyens, Public Awareness Director, National Ground Water Association

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