Arsenic and manganese have turned up often in Harding County wells, mostly in older study samples.
2 likely overstated, 1 worth checking, 1 rare out of 4 health checks.
From 23 wells tested in Harding County since 2005; your own well needs its own test. How to read this
*Arsenic, manganese and nitrate: All of these tests come from a single agency between 2005 and 2010 in one small part of the county, so this likely overstates them.
Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+
Lab results: Water Quality Portal (USGS and EPA)
Who drinks from a well here
8 in 10 people 1,018 people
Nobody else tests these wells. Only you do.
People on wells: EPA researchers' 2020 estimate
How deep wells go here
Deep wells: fewer surface germs, more minerals from the rock.
Well depths: US Groundwater Well Database
Radon risk (a gas from rock)
Possible here. A home air test is inexpensive.
Radon zones: EPA map
Here's how Harding County compares with South Dakota and the counties around it.
Each result puts Harding County next to the 6 counties that border it, on the chart's 0 to 50% scale.
These 2 have turned up often here, mostly in older study samples.
Arsenic8 of 23 wells over
All of these tests come from a single agency between 2005 and 2010 in one small part of the county, so this likely overstates it.
Manganese7 of 23 wells over
All of these tests come from a single agency between 2005 and 2010 in one small part of the county, so this likely overstates it.
This one is worth checking in Harding County.
Nitrate2 of 23 wells over
All of these tests come from a single agency between 2005 and 2010 in one small part of the county, so this likely overstates it.
This one is rare in Harding County.
Lead1 of 23 wells over
Every well needs a bacteria test every year.
E. coli0 of 2 wells had it
E. coli means human or animal waste is getting in, so if a test of your Harding County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 13 of 23 tested wells, and it isn't a health risk.
Iron stains13 of 23 wells had it
Most of the 23 wells tested in Harding County were last tested before 2010.
An old result shows the water as it was then, so treat these 23 wells as a starting point and test your own.
Most Harding County wells in these records were tested for research or because someone suspected a problem, which can push the shares above what a typical home well would show (how we read the numbers).
One mail-in lab test covers the 4 things to check in Harding County.
- Bacteria
- Nitrate
- Arsenic
- Manganese
What South Dakota offers well owners
- Free testingDANR points well owners to a free private well assessment, including water testing, offered by Midwest Assistance Program. See the program
- Certified labsSouth Dakota's list of certified labs
- Well recordsSouth Dakota's well record search
Half the household wells here are shallower than 200 feet.
That comes from 528 household wells in South Dakota's drilling records. Most wells of every kind here are 131 to 320 feet deep. Wells as deep as Harding County's are usually better protected from fertilizer and bacteria at the surface, but they can pick up more of what's in the rock, like arsenic and uranium. Typical household wells here go deeper than in 32 of the 65 other South Dakota counties with enough drilling records.
Look up your own well's depth in South Dakota's well record search, or see how to find it.
Well depths: US Groundwater Well Database
Here's what we know about radon and PFAS in Harding County.
Harding County is in the EPA's middle radon zone. An indoor air test is cheap and tells you whether to look at your water. Radon guide
Radon zones: EPA Map of Radon Zones
Questions people ask about well water in Harding County
Is well water in Harding County safe to drink?
8 of 23 wells tested in Harding County had arsenic over the limit, about 1 in 3. Across South Dakota it's about 1 in 4. We don't rank this against other South Dakota counties, because most of these tests are old study samples. All of these tests come from a single agency between 2005 and 2010 in one small part of the county, so this likely overstates it. So test your own well for arsenic before you count on it.
Can I get my well tested for free in Harding County?
DANR points well owners to a free private well assessment, including water testing, offered by Midwest Assistance Program. If not, use a lab South Dakota has certified for drinking water. Ask for bacteria, nitrate, arsenic and manganese, the tests that matter most in Harding County.
How deep are wells in Harding County?
Half the household wells here are shallower than 200 feet. Typical household wells here go deeper than in 32 of the 65 other South Dakota counties with enough drilling records.
How often should I test my well in Harding County?
Harding County has no public bacteria results for wells, so follow the CDC's advice: test for bacteria and nitrate every year, and right away after a flood, a repair, or any change in taste or smell.
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Where the Harding County numbers come from
- People on wells: 1,018 in Harding County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 382 well water samples from 23 wells in the Water Quality Portal, run by the USGS and EPA, 2005 to 2010.
- Well depths: 528 South Dakota drilling records for Harding County, gathered in the US Groundwater Well Database (Lin and others, 2024).
- Neighboring counties: the 6 counties that share a border with Harding County, from the Census Bureau's county adjacency file.
- Results marked likely overstated: our own check of who tested the wells, when and where.
- Radon: Harding County is zone 2 on the EPA Map of Radon Zones.
- State programs and links: Department of Agriculture and Natural Resources (DANR), checked November 1, 2026.