Possible Uranium Contamination in Keweenaw Wells
Scattered drinking water sources on the Keweenaw Peninsula east of the Keweenaw Fault have been found to contain uranium and/or gross alpha (a measure of radioactivity) in amounts that exceed the proposed federal Maximum Contaminant Levels (MCLs). The source of the uranium may be shale deposits that run inconsistently through the sandstone formation. Because of the inconsistent deposits, it cannot be reliably predicted which water supplies might be affected.
The supplies with known radioactivity are north of Jacobsville in Houghton and Keweenaw Counties. They include wells in the Gay, Big Traverse, Mason, and Chassell areas. There is no direct data on other water supplies located elsewhere in the same bedrock formation, but it is possible that they could also be affected.
It is hoped that in the future a pattern of uranium contamination will be mapped and we have more specific guidance to people seeking well permits. As new and existing supplies are tested, we will be able to collect relevant data regarding both the wells themselves and the human exposure. Over time we will gain a clearer picture of the extent of the problem and the health consequences, if any.
In the meantime, we caution people with private wells in the suspect area that the possibility of uranium contamination exists and recommend that their water be tested for gross alpha activity by a certified lab. The State of Michigan laboratory is not certified; samples must be sent to the Wisconsin State Laboratory*. The cost of the test is approximately $55.
The health effects of uranium exposure in the amounts that we have seen are remarkably few, mainly limited to kidney damage with long-time use. There is also a very small possibility of an increased risk of cancer over a lifetime of exposure.
If your well is located in the area of concern and you want to have the water tested, you can pick up a collection bottle at the health department office in Hancock. You will be asked to provide information about the location and specifics of your well and to fill out a very brief health questionnaire.