Concentrations of radium, Cambrian-Ordovician aquifer groundwater
![Map showing concentrations of combined radium in groundwater of the Cambrian-Ordovician aquifer at three concentration levels](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/full_width/public/thumbnails/image/Figure%20communication%20plan%20v2_0.png?itok=3prf_Btx)
Detailed Description
Concentrations of radium in samples of untreated groundwater from the Cambrian-Ordovician groundwater system frequently exceeded the USEPA Maximum Contaminant Level (MCL) of 5 picocuries per liter in Illinois, Iowa, and eastern Wisconsin, where wells tap deeper, older groundwater. From Stackelberg and others, 2018, "Radium mobility and the age of groundwater in public-drinking-water supplies from the Cambrian-Ordovician aquifer system, north-central USA."