Know Your Environment. Protect Your Health.

Uranium

City of Mountain Home

Uranium is a known human carcinogen. The federal legal limit for uranium is set at 30 micrograms per liter (corresponding to parts per billion), but utilities can also report uranium in picocuries per liter (pCi/L), which is a measure of radioactivity in water. EWG translated all uranium results to pCi/L using a conversion factor developed by the EPA. With this conversion approach, the limit of 30 ppb corresponds to 20 pCi/L. Drinking water with this much uranium would cause more than 4.6 cancer cases in a population of 100,000. California set a public health goal for uranium of 0.43 pCi/L. Read More.

Multiple forms of uranium can be detected in water, including uranium-234, uranium-235 and uranium-238. Uranium-234 is the most toxic form of uranium for human health.

 

11

Samples

0

Samples exceeding legal limit (MCL)

5

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2018ND30ND
2019ND30ND
2020N/A00N/A
20210.67 pCi/L110.67 pCi/L
20221.17 pCi/L440.67 pCi/L - 1.34 pCi/L
2023N/A00N/A

pCi/L = picocuries per liter

State, National, and Health Guidelines for Drinking Water

EWG Health Guideline: 0.43 pCi/L

The EWG Health Guideline of 0.43 pCi/L for uranium was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. Three most common uranium isotopes are U-234, U-235 and U-238. All isotopes of uranium are radioactive, and the total radioactivity depends on the ratio of isotopes. This health guideline protects against cancer.

EPA Maximum Contaminant
Level (MCL): 20 pCi/L

pCi/L = picocuries per liter

All test results

Date Lab ID Result
2018-03-20R1811826ND
2018-08-01R1836907ND
2018-08-01R1836908ND
2019-06-11R1927644ND
2019-06-11R1927639ND
2019-06-11R1927642ND
2021-09-22R21502310.67 pCi/L
2022-02-24R22091691.34 pCi/L
2022-05-11R22226181.34 pCi/L
2022-07-20R22349520.67 pCi/L
2022-10-19R22522911.34 pCi/L