Lee County, Iowa: Private Well Arsenic Risk
USGS models estimate the private-well arsenic exposure across Lee County. This is an area estimate, not a measurement of any individual 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.
~573
people estimated to rely on private wells with modeled arsenic above the 10 µg/L EPA limit
422–771
90% confidence range for that estimate
10 µg/L
EPA maximum contaminant level for arsenic
What this 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 Lee 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, Iowa also has a modeled nitrate exceedance of 0.4% of private-well residents — worth testing for at the same time.
What to do
- Test your well for arsenic (and nitrate) — it's the only way to know your actual level.
- If arsenic is present, install a reverse-osmosis system — carbon pitchers do not remove arsenic.
- Re-test annually; well chemistry changes over time.
Treating arsenic in Lee County
Arsenic is not removed by carbon pitchers or faucet filters. Reverse osmosis is the treatment that brings it below the federal limit at your tap.
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