Updated November 18, 2011
Radium at Well 19 Tests Below MCL
Earlier this year, a sample taken from Well 19 exceeded the maximum contaminant level (MCL) of 5 picocuries per liter [pCi/L] for combined radium. Additional samples were collected in September and October with both results showing the radium level below the MCL. The Water Utility plans to sample the well again in December in addition to eight times in calendar year 2012. Complete test results are available on our website.
Radium in groundwater comes from the decay of uranium and thorium. These naturally-occurring elements are found in the rock that makes up the aquifer supplying Madison’s drinking water. Additional information on radium is available on the Wisconsin DNR and US EPA websites.
Long-term exposure to elevated levels of radium in drinking water could increase the risk of bone cancer. The immediate health risk associated with drinking water containing low radioactivity levels is minimal. The water is safe to drink, and the seeking of alternative water sources is not recommended. The MCL for radium has been set well below levels for which health effects have been observed and is therefore assumed to be protective of public health.
Because exposure to high levels of radium over many years may increase the health risk, an MCL violation occurs after the running annual average of quarterly samples is above 5 pCi/L. The Water Utility is currently required to collect quarterly samples.
Well 19 operates year-round and primarily serves the University of Wisconsin campus area and the Regent neighborhood.
