Water Utility

Madison Water Utility will resample water from Well 27 on North Randall Ave. after recent testing showed radium levels once again exceeded the federal maximum contaminant level (MCL). Results from samples taken in May showed radium levels of 6.2 picocuries per liter. The MCL for radium is 5 picocuries per liter.
 
Madison Water Utility stepped up monitoring of the well in February when routine sampling found radium levels slightly exceeded the MCL. Those levels dropped below the MCL when the water was re-tested in April.
 
Radium has always occurred naturally in rock that makes up Madison’s aquifer, and variations in test results are not uncommon. The maximum contaminant level (MCL) for radium is meant to ensure the safety of water over a lifetime of consumption, so a brief spike or anomalous result should not cause alarm. Results would have to be consistently above the MCL for at least a year in order for the water to be considered in violation of federal health standards. However, Madison Water Utility takes these results very seriously and will continue to closely monitor the well.
 
Although Well 27 was in operation this past winter, it is generally used only during the high-demand summer and early fall months. In October, we will follow our standard procedure and take the well out of service. We may decide at that time to further study the geology of the well’s bore hole to determine which rock layers are contributing radium to the water supply and seal those layers if necessary.