Contaminants are common in SD drinking water, but most within legal limits

FSA water glass

State testing data show that several contaminants — all of which can be harmful to human health — are commonly found in the drinking water provided to residents of South Dakota, but whether the contaminants are present at unhealthful levels is a matter of ongoing debate.

In most cases, the tap water generated by the 650 drinking-water systems across the state fall well within guidelines set by the U.S. Environmental Protection Agency for safe consumption of lead, copper, nitrates, arsenic, radium, uranium, and a chlorine sanitation byproduct called trihalomethanes.

All of those chemicals, most of them known carcinogens, are consistently found in much of the drinking water tested regularly by South Dakota water system operators and reported to the state and federal governments. Except in rare cases, such as when a system failure occurs or a contaminant builds up over time, the contaminant levels fall below the legal guidelines set by the EPA.

But a national environmental group is trying to change the definition of “safe” and strengthen federal and state guidelines for what is considered “healthful” when it comes to the presence of dangerous contaminants in drinking water. In its annual report on America’s drinking water supply, released on Oct. 26, the nonprofit Environmental Working Group noted that many federal water-quality standards have not been updated in 20 or even 50 years, and that there are no legal limits whatsoever for 160 contaminants that can make their way into the American drinking-water system.

“The disturbing truth shown by the data is that when most Americans drink a glass of tap water, they’re also getting a dose of industrial or agricultural contaminants linked to cancer, harm to the brain and nervous system, changes in the growth and development of the fetus, fertility problems and/or hormone disruption,” the EWG said in a news release.


The study’s two main goals, according to Alexis Temkin, a staff toxicologist at EWG, is to provide Americans with an easy way to find recent data on the quality of their local drinking-water system and to highlight the group’s belief that contamination standards need to be updated and strengthened.

“Primarily, what we know is that ‘legal’ doesn’t necessarily mean ‘safe,’” Temkin said. “The vast majority of the utilities across the country get a passing grade by the EPA even though contaminants are almost always present.”

The EWG water-quality study examined test results from nearly 50,000 water systems across the U.S., including those in South Dakota. The EWG creates its own set of safety guidelines that are based on the most stringent health guidelines and scientific data currently available, Temkin said.

Based on its own safety guidelines, the group found that nearly all South Dakotans are consuming drinking water with contaminants at unhealthy levels.

The EWG study, which uses a two-year average of data from 2015-17, reported that 291 South Dakota utilities serving about 703,500 people had unhealthful levels of trihalomethanes, or THMs, the chlorine byproduct that can cause bladder and skin cancers and inhibit fetal growth. The study found that 234 systems serving 458,500 people had unhealthful levels of nitrate; 83 systems serving 421,250 people had unhealthful levels of chromium; 37 systems serving 201,000 people had unhealthful levels of arsenic; and 210 systems serving 220,000 people had unhealthful levels of radium or uranium.

Inspection data from the South Dakota Department of Environment and Natural Resources reveals that from 2012 through 2016, 712 water systems across South Dakota were cited 2,673 times for water-quality or system violations that potentially affected a total of 334,300 people.

A spokesman for the DENR, which is responsible for water testing, system monitoring and enforcement of contaminant limits, said the EWG study represents an unfair “apples-to-oranges comparison” of water-quality standards.

The strict contaminant standards used by EWG may create a misleading picture for the public that drinking water across the country and in South Dakota is unsafe, said Jeremiah Corbin, source-water protection specialist for the South Dakota Association of Rural Water Systems.


“I’m concerned that they may give people the misconception that their water is not safe when, based on drinking-water standards, it is safe,” Corbin said. “By cherry-picking what health levels they’re going to choose for safe water, it unfairly muddies the conversation.”

Corbin said maintaining safe, high-quality drinking water is an ongoing challenge that is taken extremely seriously by operators of the roughly 300 water systems in the association.

“I’m not saying there aren’t systems that aren’t perfect, but generally speaking I think the water systems and the state do a marvelous job of providing clean drinking water,” Corbin said.

Inspections reveal contamination problems

The EWG report makes clear the differences between its health standards and the legal limits, and the gap is often very wide.

For example, the EWG health limit for TMHs is .15 parts per billion, compared with the legal level of 80 ppb. For nitrates, the EWG health limit is .14 ppb, compared with the long-held federal safety standard of 10 ppb; for arsenic, the EWG health limit is .004 ppb, compared with the federal standard of 10 ppb.

Only five South Dakota systems were found to be in violation of EPA contaminant standards during the EWG study period:

  • Bonesteel (275 customers) was above the legal limit for nitrates.

  • Buffalo Gap (126 people) and the Cottonwood Grove Mobile Home Park (30 people) were above legal limits for uranium.

  • Cedar Gulch #2 (33 people) and the Shirt Tail Gulch Development (60 people) tested above legal limits for radium.

State-level violations are far more common. In 2016, the state recorded 365 total violations by 123 water systems that served about 72,000 people. That was down from a recent high of 705 violations by 143 systems affecting 82,500 people in 2014.
The DENR requires that system operators regularly take water samples for testing; the frequency is dictated by the contaminant sought and the size of the system. Some tests are required annually and others every three years.

The Hill City water system in Pennington County, serving 950 people, was cited for exceeding limits of arsenic in July and October 2018, according to state documents. The city of Springfield, in Bon Homme County, which serves about 2,000 people, was cited for exceeding limits of THM on five occasions from 2015 to 2019.


The town of Wessington in Beadle and Hand counties, serving 175 people, was cited for failing to monitor for chlorine and bacteria in 2015 and for not having a certified system operator that year. The Town of White, in Brookings County, was cited in 2016 for failing to notify the 485 people it serves of high lead and copper readings in 2016. The Yankton water system, which serves 14,700 people, was cited for high THM levels in 2016 and 2019.

The water system in the capital city of Pierre sent an advisory to the roughly 14,000 people it serves in March 2019 after the EPA found high levels of manganese in the local water supply.

The chemical can cause brain illnesses if ingested by infants; long-term consumption by adults can cause nervous-system and brain illnesses.

The city’s water comes from wells dug as early as 1927 and manganese levels likely built up since then. Pierre is building a new water-treatment system that will use surface water from the Missouri River and should come online in late 2021. The state has provided Pierre with a $36.9 million loan for construction of the new water plant.

Smaller systems at greater risk

According to the EWG report and to a News Watch review of state water-system inspections, higher and more frequent levels of contamination tend to occur in smaller water systems.

One of the most problematic systems in South Dakota serves only about 35 people in the Cedar Gulch #2 subdivision just east of Rapid City. Between July 1, 2014, and July 1, 2019, water tests revealed 64 violations of state regulations, including 32 listed as “exceedance of allowable contaminant levels” for presence of radium and alpha emitters, both radioactive compounds that can cause cancer.

Contamination of drinking water can occur due to a number of factors, including inefficient treatment systems; from leaching of contaminants from lead pipes and aging system components; from agricultural, industrial or septic-system runoff; or owing to infusion of materials within geologic formations surrounding a well.

The privately owned water system in Owanka serves about 23 residences and 52 people in a remote area of Pennington County about 10 miles southwest of Wasta. Marvin Williams, president of the water board, said the system taps the Inyan Kara Aquifer, a highly saline source mainly used for livestock. The system has been cited by the state 14 times for having high levels of radium from 2016 to 2019.

The state DENR has stepped in and last year provided a $50,000 grant to the Owanka system to fix the ongoing problem, likely through installation of treatment systems that will be installed on taps in the homes of system users, according to the DENR.

The Bon Homme-Yankton Rural Water System had problems in April 2019 when the Spencer Dam on the Niobrara River in Nebraska failed, sending debris and sediment into Lewis and Clark Lake, the water source for the system.

The source water entering the system that serves about 37,000 people in all or parts of Avon, Freeman, Irene, Menno, Mitchell, Parkston, Scotland, Tabor, Tyndall and Volin was very high in turbidity, a murkiness that can inhibit disinfection processes and foster growth of bacteria.

“Essentially, the source water from Lewis and Clark was like a chocolate milkshake,” said Terry Wootton, general manager of the water system.

System operators acted quickly to shut down the flow of water, and then heightened chlorine levels and added another chemical to hasten settling of sediments, Wootton said. Within 30 hours of the inflow of contaminated water, the turbidity levels had fallen to safe levels. Customers never received any contaminated water, he said.

Efforts ongoing to protect, improve drinking water

This year, the state Board of Water and Natural Resources within the DENR will spend $64.5 million to aid municipal and regional water systems, said Walsh, the DENR spokesman. Out of 21 total projects, two were to correct compliance issues (the Pierre rebuild and the Owanka improvements).

Much of the state’s focus has been on improving systems in rural areas that do not have ready access to reliable water sources, Walsh said.

The state has an operator-certification program that offers free classes several times a year at locations across the state, Walsh said. The state also contracts with groups that provide operators technical assistance and training, including the rural water association.

Corbin said the rural water association has a strong relationship with the state in training and educating water-system managers across the state to operate efficiently and to stay up on new technologies or techniques that can improve drinking-water quality.

“Our bread and butter is training and technical assistance for community water systems,” Corbin said. “Everybody’s goal is to provide the highest-quality water they can, and people take that very seriously.”

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