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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

December 2000

DNR Water Supply Specialist Kelley O'Connor (r) discusses collecting water samples with a homeowner who is having her water supply tested for arsenic. © Robert Queen
DNR Water Supply Specialist Kelley O'Connor (r) discusses collecting water samples with a homeowner who is having her water supply tested for arsenic.
© Robert Queen

Well above, trouble below

Arsenic, a trace element once locked in bedrock, is turning up in some Wisconsin wells.

Megan Matthews

In spring 1998, before the King family bought their home near Oshkosh, they tested their well water for arsenic. Although the house was only six years old, a second deeper-cased well had been drilled to get past an aquifer where higher arsenic levels had plagued the previous owner. No arsenic was detected; the Kings bought the home that summer and moved in.

Three to four months later there were signs of trouble from the tap. Laundry was stained orange-brown. The Kings consulted several companies to treat what appeared to be high iron in the well water. Finally, a consultant asked the family if the well had been tested for arsenic. The Kings assured him the well had been tested less than a year ago. The company rep said that might not be good enough: Arsenic levels can change over time, and often water that's high in iron can also be high in arsenic.

Test results came back in April 1999, the same week their twins were born – arsenic was present in the water at 131 parts per billion (ppb) – well above the current national standard of 50 ppb.

"Our whole life changed after getting those test results back," said Mrs. King. "We don't use our water to prepare formula, rinse the bottles, prepare food, brush our teeth, or wash fruits and vegetables. We use it to do our laundry and other chores, but I can't take my kids outside and fill up a wading pool because I'm afraid they'll swallow some water."

By September 1999, the Kings were part of a DNR program that is testing how different treatment devices can reduce arsenic exposure. The experimental systems are installed in private homes where arsenic levels can be checked monthly. In the King house, an ion exchange system now removes arsenic at one spigot. The Kings wanted a system to treat all the water in the house. Such a system was installed, but broke once and pipes leaked in two places. The family was left with a water supply that corrodes the copper pipes and causes appliances to rust. The family is planning to drill a third well, using funds recently approved from the state's Well Compensation Program.

After learning of the problem, Mrs. King urged her neighbors to have their water tested for arsenic, too. "No one else seems to have a problem," she said. "Arsenic contamination is very sporadic and levels fluctuate so widely. I wish I'd done more research."

The Stilson family, who built in the area in 1995, knew there were regional concerns about arsenic, but their builder assured them the well was drilled and cased deep enough to bypass the problem. Then, earlier this year, Kevin Stilson noticed that ice from the ice maker was turning orange. A test confirmed his suspicions: high levels of iron and arsenic at 330 ppb in their water, almost seven times the level deemed acceptable. The Stilsons contacted the DNR and were offered an experimental whole-house water treatment system. Because inorganic arsenic tends to attach itself to iron, removing the iron has successfully reduced arsenic as well.

The Stilsons use bottled water for cooking and drinking, and have gotten regular medical checkups. Still, experts can't guarantee that using arsenic-contaminated water for bathing won't cause health problems. "They think it's OK," said Stilson, "but they can't give me one hundred percent assurance. That bothers me."

A natural element set free by the pressures of development?

Arsenic (As) is a tasteless, odorless element that occurs naturally in soil, bedrock, groundwater and the oceans. It is found in both organic and inorganic forms. Organic forms found in ocean fish and seafood are relatively nontoxic. However inorganic arsenic, the form found in many Wisconsin wells is a potent poison; ingesting small doses over many years has been associated with a variety of cancers, nervous system damage, diabetes and blood pressure changes.

Because arsenic is a natural part of our environment, everyone is exposed to trace amounts in foods, wood and coal smoke, tobacco products and dust from some industrial processes. Normally, arsenic is excreted from the body within a few days. Medical problems are usually associated with long-term exposure to moderately high amounts of arsenic, though short-term exposure can also cause health problems if levels are high enough.

There are pockets of arsenic contamination statewide, but wells drilled into bedrock layers called St. Peter Sandstone and Galena-Platteville Dolomite in northeastern, southeastern, and southwestern Wisconsin appear to contain higher levels of arsenic. These layers are the primary sources of drinking water in Outagamie, Winnebago and portions of Brown counties. More than 20,000 private drinking water wells and 434 public water systems draw water from these rock formations.

In the Town of Algoma west of Oshkosh, residents receive results from testing for arsenic in area well water. © Robert Queen
In the Town of Algoma west of Oshkosh, residents receive results from arsenic tests on area well water.

© Robert Queen

Arsenic-contaminated groundwater is a relatively recent discovery in Wisconsin. In fact, DNR scientists first became aware of the problem in 1987 when arsenic was detected in water samples drawn from groundwater near a proposed landfill site.

Researchers believe that this arsenic, trapped in bedrock for millions of years, may be released into groundwater as a consequence of increasing water use in the growing region. Water withdrawals are lowering the water table from one to three feet per year, and the demand is increasing rapidly with roughly 1,000 new wells drilled per year in Winnebago and Outagamie counties alone. An untested theory is that more openings in the bedrock layers may let more atmospheric oxygen seep into the aquifer, slowly oxidizing sulfide minerals in the rock and releasing iron, arsenic and other trace elements. The process is similar to what happens when a wet piece of iron begins to rust.

The methods used to construct and disinfect wells may also add oxygen into the aquifer. Air-rotary drill rigs pump huge amounts of air into the bedrock. Chlorine products, used to disinfect wells, may trigger chemical reactions that release arsenic from bedrock. Current research has neither proven nor disproven these theories.

Arsenic concentrations in area wells are highly variable, ranging from no detection to one well with 15,000 ppb – a level that can quickly lead to stomach upsets, diarrhea and nerve damage. Unfortunately, because of the way arsenic exists within this bedrock, there is no way to accurately predict whether water from a new well will pose a risk of arsenic exposure. Two out of three wells drilled in the area don't show signs of arsenic contamination and 95 percent of wells tested in the last 13 years have concentrations of less than 50 ppb, the current standard for public water supplies. Even wells drilled across the street from each other can show wildly different levels of arsenic in the drinking water.

Although there are still more questions than answers, water supply experts, the health community and homeowners are taking this problem quite seriously. The Department of Natural Resources designated an "Arsenic Advisory Area" in these counties in 1993. Research showed that within the advisory area, it made sense to case new wells deeper.

"As a first step, research showed it made sense to drill and case new wells deeper through more rock in order to tap a different aquifer. The strategy is to avoid bedrock layers with arsenic by extending the steel casing deeper so water can be withdrawn from bedrock layers below the arsenic contaminated zones," explained DNR Water Supply Hydrogeologist Tom Riewe.

These recommendations seemed to solve the problem for a while, but time is showing these steps may not be sufficient, as even deeper wells like the Kings' and Stilsons' are producing water with higher levels of arsenic.

Evaluating personal exposure and community health

Experts calculate that drinking water that contains 50 ppb arsenic that is consumed over a 70-year period would increase a person's chance of getting cancer by as much as 3 cases in a population of 1,000.

In 1993 the Wisconsin Department of Health and Family Services started working with local health officials to gather information about people who may have been exposed to higher levels of arsenic in their water for several years. Health surveys were collected from 1,838 people who drew their water from private wells in the region. Analysis showed that people who drank water containing more than 50 ppb arsenic for 10 years or more were seven times more likely to report skin cancer, and five times more likely to report other types of cancer than people with lower arsenic intakes.

These findings prompted the Department of Health and local health officials to reevaluate arsenic exposure and health status in the region. Between June 2000 and 2002, they will gather more information about arsenic exposure and health among families using private well water in the region. Area clinics and doctors are also learning how to recognize signs and symptoms of arsenic exposure. In addition, county health departments and townships are working with private laboratories to offer convenient low-cost arsenic tests (about $30) for residents.

New standards and research expected

The U.S. Environmental Protection Agency has proposed lowering the arsenic standard in public water supplies from 50 ppb to 5 ppb based on health concerns from prolonged exposure. These tighter standards would also be used to advise private well owners. The serious health risks warrant annual water testing for all wells in the advisory area.

Families whose water contains high levels are advised to discuss possible effects of exposure with their family physicians.

Experts from the DNR's drinking water and groundwater program have been meeting with Department of Health officials, experts at several Wisconsin universities, local county health departments, and the Wisconsin Water Well Association for a year to work on the problem. Some partners are investigating the chemical reaction that triggers arsenic release into groundwater, others are mapping where arsenic occurs within Wisconsin bedrock. Team members are examining well drilling techniques that can lessen arsenic release, testing methods to handle arsenic wastes trapped in treatment equipment, and developing community education programs across the state to share information about arsenic.

Another piece of the solution is working with the public to become more water-wise and less wasteful. While Wisconsin has an abundant supply of water, it needs to be managed properly in order to ensure enough safe drinking water for the future. Drawdown of the groundwater table may be part of the arsenic problem – better water conservation may become an important priority.

Several pilot programs are testing various treatment systems and determining how to keep the costs of arsenic monitoring and treatment affordable. Eventual solutions may include special well construction methods, setting wells with deeper casings, and whole house treatment systems. Private well owners may choose to form community water systems, group wells or neighborhood cluster wells. The leader of the work group, DNR Groundwater Chief Mike Lemcke, likens the investigation to having only 400 pieces of a 1,000-piece jigsaw puzzle on the table and not knowing how or if they fit together.

"We discovered the arsenic problem earlier in Wisconsin," Lemcke said, "and we're not waiting for others to find solutions that protect the health of private well owners. We decided to actively pursue our own, new research to come up with workable solutions in a reasonable timeframe."

Megan Matthews writes about environmental issues for DNR's Drinking Water and Groundwater programs.