Well water in Fall River County, South Dakota
1in10
Testing recommended
tested well samples in Fall River County exceeded the EPA limit for uranium (30 ug/L), based on public data from USGS Water Quality Portal.
The strongest signal is radium (226 + 228): 27% of 11 local samples were above the limit, too few samples to carry the headline but first on the test list below.
2,024 test results across 11 contaminants from at least 265 wells, 1931 to 2010; chloride has the most at 301. Data refreshed September 15, 2026.
Compiled by Nick at Well Water Nerd from public records. How these pages are built
An estimated 2,474 people in Fall River County get their drinking water from a private well, per USGS 2015 county water use. That is about 36% of residents.
Separately, the USGS national arsenic model estimates that <1% of the 2,474 people on private wells in Fall River County draw water above 10 ug/L, from geology and well depth rather than local tests.
What individual samples found
Each row summarizes every public sample for that contaminant inside Fall River County. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.
| Contaminant | Above limit | Samples | Detected | Median | Highest | Limit |
|---|---|---|---|---|---|---|
| Radium (226 + 228) 1979 | 11 | 91% | 1.4 | 15 | 5 pCi/L EPA limit | |
| Uranium 1954 to 1997 | 226 | 83% | 3.7 | 115 | 30 ug/L EPA limit | |
| Arsenic 1978 to 2010 | 243 | 51% | 0 | 53 | 10 ug/L EPA limit | |
| Copper 1978 to 1997 | 232 | 29% | 0 | 0.21 | 1.3 mg/L EPA limit | |
| Nitrate 1931 to 2007 | 88 | 90% | 0.28 | 8 | 10 mg/L EPA limit | |
| Fluoride 1937 to 2008 | 74 | 100% | 0.79 | 4 | 4 mg/L EPA limit | |
| Lead 1978 to 1997 | 15 | 40% | 0 | 0 | 15 ug/L EPA limit | |
| Chloride 1931 to 2010 | no limit | 301 | 76% | 19 | 2,110 | 250 mg/L nuisance level |
| Sodium 1931 to 2010 | no limit | 290 | 100% | 204 | 1,920 | 20 mg/L health guideline |
| Iron 1931 to 1997 | no limit | 273 | 86% | 20 | 56,000 | 300 ug/L nuisance level |
| Manganese 1954 to 2008 | no limit | 271 | 81% | 10 | 9,570 | 300 ug/L health guideline |
Over time
Share of samples above the limit by period. A cell needs ten samples to show; a comparison needs twenty in each period. Later periods sample fewer wells, and often the ones already known to have a problem.
| Contaminant | before 2000 | 2000s | 2010s | 2020s |
|---|---|---|---|---|
| Arsenic | 3%232 samples | 10%10 samples | n/a | n/a |
Closer than the county
See the sampled wells near your address
The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.
Check my addressWhat this means
The contaminants most often above their limit here are radium (226 + 228) (27% of 11 samples), uranium (10% of 226 samples), and arsenic (4% of 243 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.
Chloride, Iron, and Manganese are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.
What to test for in Fall River County
- 1Radium (226 + 228)27% of 11 local samples were above the limit.
- 2Uranium10% of 226 local samples were above the limit.
- 3Arsenic4% of 243 local samples were above the limit.
- 4Coliform bacteriaRecommended for every private well, every year.
- 5NitrateRecommended for every private well, especially near farms or septic systems.
- 6FluorideDetected in 100% of local samples.
- 7IronDetected in 86% of local samples.
- 8Volatile organic compounds (VOCs)258 reported spills and releases on record locally.
Test your Fall River County well for radium (226 + 228), uranium and arsenic
Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.
Order the Tap Score well water test kit, from $209Already tested? Upload the report
Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.
Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.
Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.
Where to get a well tested in South Dakota: certified labs, state programs and prices.
Already have results back? Get your lab report read against the Fall River County numbers, $29. Every line explained, ranked by what matters, with the fix for each.
Wells in Fall River County
658 domestic wells in Fall River County are on record with the state since 1972. the typical well is 280 feet deep (one in ten goes past 702 feet).
Find your own well's report
The state keeps the driller's report for most wells drilled since 1984. It tells you how deep your well is, where bedrock starts, and how much water it makes, which decides what treatment can work.
- Open DANR well completion reports and choose Water Well.
- It lists depth, aquifer, static water level and the driller.
South Dakota has required reports since 1986.
The rock under Fall River County
Lower Cretaceous aquifers
Sandstone. Sandstone wells draw from pore space in the rock and tend to be dependable. Iron, manganese and hardness are common, and some sandstones carry arsenic or radium, so a first test should include both.
Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the county centroid. A single well can sit in a different unit, especially near a boundary.
Official help in South Dakota
Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.
- Test a Private Well, South Dakota Department of Health
- Drinking Water Program - Laboratory Certification, South Dakota DANR
Contamination sources on record in Fall River County
South Dakota DANR tank facilities and spills records 258 reported spills and releases in Fall River County, among 318 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.
- 258
- reported spills and releasesMost spills are fuel; a few are solvents or chemicals that reach the water table.
- 33
- registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
- 27
- other solid waste facilities
Treatment that fits the local profile
Radium (226 + 228)
Water softener (cation exchange); Point-of-use reverse osmosis
Uranium
Point-of-use reverse osmosis; Anion exchange; Whole-house anion exchange
Arsenic
Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
Manganese
Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis
Systems we would look at first
Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.
For radium (226 + 228)
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For uranium
Whole-house arsenic and uranium filter
whole-house, at the point of entry, about $2,500
Adsorptive iron-based media; sized to your well yield.
For arsenic
Aquasana SmartFlow reverse osmosis
under-sink or countertop, about $225
Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.
For manganese
Iron and manganese oxidizing filter
whole-house, at the point of entry, about $1,800
Air-injection or greensand media; fixes staining at the source.
Free, no obligation
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Common questions
How deep are wells in Fall River County?
The typical domestic well in Fall River County is 280 feet deep, based on 658 wells reported to the state since 1972. One in ten is deeper than 702 feet.
Is there arsenic in well water in Fall River County?
Arsenic was detected in 51% of 243 public well samples in Fall River County, and 4% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.
How often should I test a private well in Fall River County?
Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.
Counties near Fall River County
Closest first. Groundwater does not stop at a line on a map, so the next county over is a fair second opinion.
Want the numbers themselves? Download the South Dakota dataset as CSV, every county and town, with the sources named.
Sources
- USGS Water Quality Portal: 2,024 samples in Fall River County. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
- USGS national arsenic model (Ayotte 2017): estimated share of 2,474 people on private wells in Fall River County above 10 ug/L of arsenic, from geology, well depth and land use. County estimates of domestic well users with arsenic above 10 ug/L from the USGS national logistic regression model (Ayotte, Medalie and Qi, 2017), with private well population from the USGS 2015 county water-use compilation (Dieter and others, 2018). Retrieved September 15, 2026.
- South Dakota DANR well completion reports: 1,401 well records in Fall River County, 658 domestic. Well completion reports filed with the South Dakota Department of Agriculture and Natural Resources. Only aggregates are shown; owner names and addresses are never stored. Retrieved September 18, 2026.
- South Dakota DANR tank facilities and spills: 318 regulated sites located in Fall River County. Regulated tank facilities and spill reports from the South Dakota Department of Agriculture and Natural Resources. Retrieved September 18, 2026.
Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.