Arsenic is showing up in Scott County drinking water

An infamous chemical best known for poisoning kings and emperors is appearing in an unlikely place: private wells in Scott County.

Arsenic — a naturally occurring element found in air, soil, food and water — has made its way into drinking water for some residents in Minnesota’s ninth most populous county, concerning officials who point to the chemical’s connection to certain cancers and diabetes.

The county runs a testing program that helps neighbors determine if their private wells contain levels of arsenic exceeding limits that the Environmental Protection Agency deems safe. But Scott County leaders haven’t managed to secure grant money that could pay for filters for residents to rid their tap water of arsenic.

That’s left residents on the hook for flushing their water of yet another chemical that joins a growing list of contaminants dirtying this essential resource across the southern Twin Cities suburbs — from per- and polyfluoroalkyl substances and nitrates to cyanizine and arsenic. While some cities hiked water rates to pay for projects to purify city-provided water, the presence of contaminants in private wells adds another layer to this ongoing public health issue.

“We have high arsenic in Scott County,” said Kate Sedlacek, the county’s environmental services manager, at a December meeting. “We thought it was just going to be a certain area, and we are finding it throughout the whole county.”

Arsenic contamination is widespread in Scott County.

Testing has shown that almost 47% of new private wells in the county contain arsenic above two parts per billion, the detection limit for most water testing labs. Roughly 13% of wells had amounts of the element at rates above ten parts per billion, the maximum contaminant level for public water supplies, according to the EPA.

The element ended up in private wells thanks to glacial deposits, sediment that released arsenic after being left behind by glaciers that melted thousands of years ago. Hennepin, Wright and Carver counties also have a relatively high number of wells contaminated with arsenic.

Yet nailing down exact numbers can be a challenge. The state maintains a database that tracks the presence of arsenic in private wells across Minnesota. And contractors are required to test for a suite of contaminants, including nitrate, coliform bacteria and arsenic, when installing a new well. But private wells are largely unregulated after that, Berquist said.

Berquist added that there’s no statewide program for arsenic testing, though officials recommend people with private wells test — and treat — their water for the chemical. Options include reverse osmosis filter systems, which typically cost several hundred dollars.

Berquist noted that few programs exist to help people defray the costs of expensive filtration systems. And although the health department scored grants that provided Minnesotans with free kits to test their water for chemicals including arsenic, that money will soon run dry.

“We will not be able to continue that assistance going forward,” she said.

“If you send out a targeted mailing saying, ‘Hey, we’re worried about there being arsenic in your water, please test,’ turns out, folks will test,” said Scott County Water Resources Supervisor Vanessa Strong.

Numbers have dipped since then. But county officials still recommend that residents who source their water from arsenic-tinged wells use an alternate drinking water source or install a treatment system. (Strong noted that leaders are primarily concerned about chemical contamination in private wells; water from city sources is safe.)

For now, officials are working to amass groundwater data from various sources — cities, townships, the state — to create a “comprehensive picture” of water quality in the area.

“So no matter where you live in Scott County, you should be able to see the same cohesive data,” Strong said.

They’re also on the hunt for money that could fund treatment systems.