Free testing, with limits
Montana's free well testing is only for childcare facilities. Check which tests it includes before you count on it for uranium.
Montana's private well pageUranium in Montana well water, by county
Uranium is widespread, over the limit in 15% or more of tested wells, in 1 of the 12 Montana counties with 10 or more tested wells. 1 more look high, but those results likely overstate it. A county's share tells you how likely a problem is nearby. Only a test of your own well tells you what's in it.
How Montana compares with the rest of the country
Across Montana, about 1 in 12 tested wells had uranium over the EPA limit of 30 µg/L (28 of 324). Across all tested wells in the US it's about 1 in 22. So uranium turns up in Montana wells about twice as often as in the country as a whole, and a test is worth adding even if your county isn't on the list below.
Why it matters: Drinking it for years can harm your kidneys and raises the risk of cancer.
Uranium comes out of the rock and sediment the wells draw from.
Uranium in tested wells, county by county
Share of each county's tested wells with at least one result over the EPA limit of 30 µg/L. Counties need 10 or more tested wells to be listed. Widespread means 15% or more, worth checking 5 to 15%, rare under 5%.
| County | Wells tested | Wells over the limit | Level |
|---|---|---|---|
| Sheridan County | 13 | Widespread | |
| Big Horn County | 10 | Widespread | |
| Lewis and Clark County | 24 | Worth checking | |
| Jefferson County | 70 | Worth checking | |
| Yellowstone County | 12 | Worth checking | |
| Silver Bow County | 13 | Worth checking | |
| Roosevelt County | 49 | Rare | |
| Glacier County | 31 | Rare | |
| Ravalli County | 18 | Rare | |
| Richland County | 16 | Rare | |
| Carbon County | 14 | Rare | |
| Valley County | 13 | Rare |
* Likely overstated. These shares come from a narrow set of wells, so they probably run high for the county as a whole:
- Sheridan County: All of these tests come from the US Geological Survey in one small part of the county, so this likely overstates it.
11 more Montana counties have 1 to 9 tested wells for uranium, too few to rate.
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Where to get your well tested for uranium in Montana
A lab Montana certifies
Ask for uranium by name. Results from a certified lab count for a home sale or a loan.
Labs certified by MontanaA mail-in kit
Fill the bottles at your kitchen tap and mail them back. We mark the kits that include uranium.
Compare kitsKeep reading about wells in Montana
- Well water testing in Montana: how to get tested and what turns up statewide
- Uranium in well water: where it comes from, what it does and how to remove it
- Nitrate in Montana wells, by county
- Arsenic in Montana wells, by county
- Manganese in Montana wells, by county
- Lead in Montana wells, by county
- Radon in Montana wells, by county
Questions people ask about uranium in Montana
Is there uranium in Montana well water?
Uranium is widespread, over the limit in 15% or more of tested wells, in 1 of the 12 Montana counties with 10 or more tested wells. 1 more look high, but those results likely overstate it. Across Montana, about 1 in 12 tested wells had uranium over the EPA limit of 30 µg/L (28 of 324). Across all tested wells in the US it's about 1 in 22. So uranium turns up in Montana wells about twice as often as in the country as a whole, and a test is worth adding even if your county isn't on the list below.
Where can I get my well tested for uranium in Montana?
Montana's free well testing is only for childcare facilities. If that doesn't cover you, use a lab certified by Montana for drinking water, or a mail-in kit that includes uranium from a certified lab.
See Montana's list of certified labs, or compare mail-in kits.
Where these numbers come from
- Lab tests: Water Quality Portal (USGS and EPA), well samples since 2000. A well counts as over if any of its tests was over the EPA limit of 30 µg/L. Wells tested for studies and monitoring, not a random sample of homes.
- Likely overstated: our own check of who tested the wells, when and where. How we check.
- State programs and links: Department of Environmental Quality.