Is there arsenic in your private well? Study analyzes residents’ risk in Great Basin, western Utah

CEDAR CITY — What’s in your water? Scientists at the Desert Research Institute took water samples from wells in Nevada, testing for arsenic exceeding safe levels. Using this data, they estimated the risk to private well users throughout the Great Basin, including those living in Iron and Beaver counties.

Stock image | Photo by ArtTim/iStock/Getty Images Plus, St. George News

Due to the Great Basin’s aridness, surface water is “sparse,” according to the institute’s website. This means many residents rely on private wells, which are unregulated. Additionally, over 49,000 of these wells may be at risk of “unhealthy levels of arsenic” across the region.

While the Environmental Protection Agency’s guidelines allow for up to 10 micrograms of arsenic per liter in public drinking water, research has indicated that long-term exposures of over 5 micrograms per liter may impact a person’s health, according to the institute.

Some symptoms of long-term exposure to high levels of arsenic in drinking water include pigmentation changes to a person’s skin, hyperkeratosis, or hard patches on the soles of the feet or palms, and skin lesions, according to the World Health Organization. Typically these symptoms occur after approximately five years of minimum exposure and can be a precursor to skin cancer.

Additionally, long-term exposure can cause bladder and lung cancers, and according to WHO, may be associated with diabetes, pulmonary disease and cardiovascular disease.

Researchers collecting samples from a private domestic well to test its water quality, date and location not specified | Photo courtesy of Dan Saftner, Cedar City News

Dan Saftner, a hydrogeologist at the Desert Research Institute, told Cedar City News that his work entails researching ground and surface water issues and how they relate to water quantity and quality.

One reason individuals in the Great Basin are at a higher risk for arsenic in their drinking water is due to the region’s unique landscapes, characterized by mountain ranges that surround “deep, narrow, elongated valleys,” Saftner said.

These mountains are “undoubtedly” primary sources of the metalloid in many areas, he added.

For instance, volcanic and meta-sedimentary rocks often contain arsenic. As they erode and weather, the resulting sediment fills the valleys. Water percolating through the valley floor transports arsenic to aquifers, which Saftner said are the study’s targets.

Other sources that “have not been considered much in previous work” are geothermic and tectonic activity — faults and fractures in the subsurface.

“In our region, we have very high geothermal activity,” he said. “We have a narrow lithosphere and very high geothermal gradient, so you don’t have to go deep into the earth to find really high temperatures, right?”

These deep, geothermal reservoirs can also host high levels of arsenic, Saftner said, adding that when this water migrates up through fault zones, it can mix with shallow aquifers, increasing arsenic concentrations.

Because this research illustrated that arsenic in groundwater is an issue in the Great Basin, scientists questioned how much of the metalloid is present in private wells, Saftner said. Researchers sampled hundreds of wells in and around Nevada cities and towns, including Reno, Fallon and Carson City, and analyzed them for dissolved metals, including arsenic.

This map indicates probability of arsenic levels exceeding 5 micrograms per liter in northern Nevada | Image courtesy of Dan Saftner, Cedar City News

While some findings were anticipated, others exceeded their expectations, including the percentage of wells that were found to have high arsenic levels, Saftner said.

The samples represented a small subset of private wells in the Great Basin region, prompting them to develop a model that “accurately predicts” the arsenic concentrations in locations where they couldn’t collect samples, he said.

The model was created using publicly available data from the U.S. Geological Survey and information obtained from earlier samples. And data was organized by water basin and county. But because their analysis focused on basins, some counties were partially studied as they are host to multiple basins — some of which weren’t included.

Approximately 5% of Iron County was analyzed and about five people in that range used domestic wells. Of those, the study found that 3.1 individuals had the type of well most at risk of high levels of arsenic. Researchers analyzed approximately 29% of Beaver County, finding that no one within that area used private wells, and thus zero were at risk.

Saftner said he hopes that Great Basin residents use the data as a resource “to at least be informed about the arsenic potential in your area.”

Researchers collecting samples from a private domestic well to test its water quality, date and location not specified | Photo courtesy of Dan Saftner, Cedar City News

Additionally, the hydrogeologist encourages private well users to have their water tested regularly and to contact their state Division of Water Resources. Utahns should contact their local health departments for information concerning water quality testing.

“The more you can do it (test), the better,” he said. “Water changes over time — it’s not static. There are seasonal changes. There are land use changes over time. As there’s more groundwater pumping, the natural conditions of groundwater quality can change. So it’s important to stay on top of it.”

The results of these tests can help residents make an informed decision about necessary treatments. It is also essential to evaluate a well’s water quality after it is tested, Saftner said. For instance, “even if you removed 75% of the arsenic, you still might have levels that exceed the EPA’s drinking water guidelines” due to the high concentrations of the metalloid found in some locations.

For more information, visit the Desert Research Institute’s website. To access the full study, click here.

Copyright St. George News, LLC, 2023, all rights reserved.

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