Nemaha County, Nebraska: Private Well Water Quality
USGS models estimate the private-well arsenic exposure across Nemaha County, and USGS laboratory samples from at least 16 wells in the county show measured nitrate, manganese, iron and pH. The arsenic figure is an area estimate; the measurements are of other wells — neither is a test of your own well.
This is a modeled probability for the area, not a measurement of your well. USGS statistical models estimate how many private wells in this area are likely to exceed the federal limit — they cannot tell you what is in your water. Two neighbors can have very different results. The only way to know your well is to test it.
~3
people estimated to rely on private wells with modeled arsenic above the 10 µg/L EPA limit
2–3
90% confidence range for that estimate
17% of wells
sampled by USGS in the county measured > 10 µg/L for arsenic (6 wells)
Find out what's actually in your well
Private wells are not regulated by the EPA — nobody tests wells in Nemaha County for you. Arsenic, nitrate and coliform bacteria are the three most common private-well problems, and none of them has a taste or smell. A certified lab test checks all of them at once; the CDC and EPA recommend testing every well at least once a year.
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Measured well tests in Nemaha County
Unlike the arsenic estimate above, these are real laboratory results: the USGS has published chemistry from at least 16 wells in Nemaha County, sampled 1988–2016. They describe other wells in the county — domestic, public-supply and monitoring wells — not your well.
| Parameter | Median | Wells over threshold | What the threshold means |
|---|---|---|---|
| Nitrate (as N) | Not enough USGS well samples in Nemaha County (fewer than 5) — see the state page. | ||
| Manganese6 wells | 113 µg/L90th pct: 390 µg/L | 17%Some | > 300 µg/L (EPA health advisory). Lifetime health advisory; above 50 µg/L it already stains fixtures and tastes metallic. Neurological concern for infants. |
| Iron | Not enough USGS well samples in Nemaha County (fewer than 5) — see the state page. | ||
| pH16 wells | 7.1 90th pct: 7.5 | 0%Low | outside 6.5–8.5 (EPA secondary range). Low pH is corrosive and leaches lead and copper from plumbing; high pH causes scale and bitter taste. |
What the samples show
- Nitrate (as N): Not enough USGS well samples in Nemaha County — see the state page.
- Manganese: Manganese is common at nuisance levels: 50% of sampled wells were over the 50 µg/L staining standard; 17% over the health advisory.
- Iron: Not enough USGS well samples in Nemaha County — see the state page.
- pH: pH is in the normal range for most sampled wells (median 7.1).
- Arsenic (measured, 6 wells): Arsenic was measured above the limit in 17% of sampled wells (median 2 µg/L).
What to do about the biggest finding (arsenic): Test for arsenic; reverse osmosis or an arsenic-specific adsorption filter removes it — carbon pitchers do not. Read more: Arsenic in well water.
Source: USGS well samples aggregated to Nemaha County, Nebraska — manganese, pH and arsenic from USGS ScienceBase 5f36baa782cee144fb3873e8 (site medians, 1988–2019); nitrate and iron from McMahon et al. (2019), Environ. Sci. Technol. 53:29–38 (NWIS wells). County assignment by Census 2020 boundaries. Statistics shown only where ≥ 5 wells were sampled. USGS well samples; not a test of your well.
What the arsenic estimate means
Arsenic occurs naturally in bedrock and can dissolve into groundwater, so it shows up in private wells with no color, taste or smell. The USGS estimate above combines a statistical model of arsenic probability with the number of people on domestic wells in Nemaha County. A higher number means more of your neighbors are likely drinking water over the federal limit — but your own well could be higher or lower. Long-term arsenic exposure is linked to skin, bladder and lung cancers, so the EPA sets the limit at 10 µg/L.
Statewide, Nebraska also has a modeled nitrate exceedance of 2.2% of private-well residents — worth testing for at the same time.
What to do
- Test your well for arsenic, nitrate, manganese and iron — it's the only way to know your actual level.
- If arsenic or nitrate is present, install a reverse-osmosis system — carbon pitchers do not remove either.
- For manganese or iron staining, a whole-house oxidizing filter or softener is the fix; RO for the drinking tap.
- Re-test annually; well chemistry changes over time.
Match the filter to your test result
Carbon pitchers and faucet filters do not remove arsenic or nitrate. Reverse osmosis is the point-of-use fix; a whole-house system handles the rest of the home.
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Check price on Amazon →Affiliate links — we may earn a commission at no extra cost to you. Re-test after installing to confirm the system is working.