Wells may tap into trouble

Study finds human viruses in deep Madison aquifer

By DARRYL ENRIQUEZ
denriquez@journalsentinel.com

Posted: June 16, 2006

An armor plate of clay and shale that for thousands of years has prevented surface pollution from contaminating vast underground vaults of fresh water is being breached, alarming water scientists in Wisconsin and possibly affecting national water policy.

Human-borne viruses have been found in wells that tap the deep aquifer 800 feet below the city of Madison for drinking water, a public health expert from the Marshfield Clinic Research Foundation said.

The presence of viruses in groundwater is not new. Bacterial and viral contaminates are regularly found in shallow wells. What's startling in this study is that viruses may have penetrated what was thought to be an impermeable layer of earth that encases a deep aquifer, said Ken Bradbury, a state hydrogeologist.

For the near future, the question of how viruses managed to migrate deep below Madison will remain unanswered. Water experts will instead launch a $1.8 million research project in west and central Wisconsin to determine the impact of viruses on the health of children.

"I never thought we'd find viruses in the Madison water, given the depth of the aquifer," said Mark Borchardt, director of the Public Health Microbiology Laboratory for the Marshfield Clinic Research Foundation. "That's the message from Madison. We can't assume the deep water is microbiologically pure. This has ramifications for the state and national policy."

The U.S. Environmental Protection Agency is working on enacting new regulations to protect water purity of deep aquifers that are thousands of feet below ground and near-surface shallow aquifers. The new regulations likely will contain health standards based, in part, on the findings of the Wisconsin health study funded by the EPA, Borchardt said.

"More than half of the U.S. population relies on groundwater for its drinking water, and research shows that groundwater can become contaminated with waterborne infectious agents like viruses," he said. "Groundwater is perceived as being pure, but between 1991 and 2000, more than two-thirds of the 163 waterborne infectious disease outbreaks in the U.S. were attributed to groundwater contaminated by viral, bacterial and disease-producing agents."

Experts think that the number of outbreaks is underestimated by tenfold because many states do not require that waterborne outbreaks be reported to the U.S. Centers for Disease Control and Prevention, he said.

Groundwater users have seen contamination problems arise over the past several years, including cancer-causing radium and toxic arsenic.

Over the past several decades, environmental protection measures have focused largely on surface water, such as lakes, streams and wetlands.

It's only been in the past decade, as officials became more aware of contaminants, that they turned their attention to the unseen yet much-needed underground water source.

Melissa Scanlan, executive director of Midwest Environmental Advocates, said the Madison study reinforces the idea that all water is connected.

"We now have a water management system that does not reflect science," she said. "We don't connect the two. The research shows that water is constantly in motion and shows the need for an integrated management system that looks at ground and surface water as interconnected, as pieces of the whole. Any other approach is missing the boat."

Scanlan's agency is involved with the state's Groundwater Advisory Committee, a group charged by the Legislature with examining ways to improve groundwater management in southeast Wisconsin and the Brown County area. Both areas of the state are experiencing groundwater shortages and contamination problems.

In Borchardt's new health study, children's health will be studied because their immune systems lack a tolerance to waterborne contaminates that can cause diarrhea, vomiting and fever, he said. The study will check municipal wells in 14 west and central Wisconsin communities for viral contamination. Nearly 1,100 children and 700 adults have agreed to participate in the study, he said.

"We're going to the heart of the matter to see if there's a health impact by viral contamination," Borchardt said.

The study will look at users of sandstone aquifers that are near the surface and often become polluted with a variety of contaminants, many of them borne in the gastrointestinal tracts of humans, he said.

Viruses can be managed

State hydrogeologist Bradbury, who teamed up with Borchardt in the study of Madison's deep aquifer, stressed that if properly managed, viruses in municipal groundwater do not pose a health threat, provided a water system is properly chlorinated. The Madison findings will be circulated to water utilities through the American Water Works Association, which is funding the Borchardt-Bradbury research.

The Madison study explored an underground formation called an aquitard, which confines aquifers in a protective casing and was thought to protect the water from invading contaminants. Bradbury said aquitards also prevent surface and shallow aquifer water from entering deep aquifers that hold water up to 10,000 years old.

Bradbury, who is with the Wisconsin Geological and Natural History Survey of the University of Wisconsin Extension in Madison, has three untested theories about how viruses got into the deep aquifer.

The first is that the aquitard may have cracks, some as small as a hairline, and viruses were able to squeeze through. Another theory is that well casings can be a pathway if they contain similar cracks. A third possibility is that Madison is sitting on an unknown number of abandoned and unsealed wells.

"The important thing in either case is that there is a pathway and the aquitard is not a foolproof protector of the aquifer," Bradbury said. "Many of the things we do on the surface are contaminating groundwater, and viruses are one of them. People get lax about their water, but it pays to be vigilant."