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Molybdenum in groundwater
Molybdenum (Mo) is a metallic element that is naturally present, usually at low levels, in the earth’s crust. Trace amounts of molybdenum are necessary for human health, and are obtained from common foods in the diet such as leafy vegetables, legumes, grains and organ meats. Higher concentrations have been found in soil or groundwater, typically in conjunction with spills or some historic waste disposal practices. Residents are advised to avoid the extremely low risk associated with future molybdenum exposures by not consuming water that contains molybdenum above the Wisconsin groundwater standard of 40 micrograms per liter (μg/L). Naturally-occurring levels of molybdenum in groundwater are low; U.S. Geologic Survey found a median value of 1 μg/L nationwide. Most well owners do not need to include molybdenum during annual well testing.
Molybdenum in southeast Wisconsin
Molybdenum concentrations above the state groundwater standard were found in monitoring wells and private water supply wells in the Caledonia-Oak Creek area in southeast Wisconsin. A two-year DNR study was unable to determine the origin of the elevated levels of molybdenum.
- Molybdenum in Southeast Wisconsin Fact Sheet
- Caledonia Groundwater Molybdenum Investigation (PUB-WA-1625)
- Summary of the DNR’s Molybdenum and Boron Investigation (PUB-WA-1640)
Who should test
The department, along with the state Department of Health Services (DHS) and local health officials, recommend that residents using private wells in the towns of Caledonia, Raymond, and Norway in Racine County, in Muskego in Waukesha County, and residents using private wells instead of municipal water in Franklin and Oak Creek in Milwaukee County should sample and test their well water for molybdenum, along with their recommended annual testing for bacteria and nitrates. Testing cost ranges from $13 to $45.
Testing your well water
- Get started
Contact a certified laboratory that can test your water for a specific contaminant.
- Collect a water sample properly
The laboratory you work through will provide you with a water sampling kit. You can watch a demonstration showing basic methods for properly collecting a water sample to yield accurate results.
Staff at the DHS recently completed a public health assessment in area wells. While the full assessment won’t be available for a few months, DHS staff have concluded from findings thus far that it is very unlikely that drinking water at these levels would result in current or future health effects for residents.
The Department of Safety and Professional Services (DSPS) has approved water treatment devices for molybdenum and boron. The total device cost ranges from $400 to $1000 depending on model and labor.
A licensed pump installer, well driller or similar water industry professional should be hired to correctly install an appropriate treatment device.
|Molybdenum in southeast Wisconsin||Eric Nitschke
|Drinking water, wells and well testing||Zoe McManama
|Caledonia Groundwater Molybdenum Investigation||Frank Schultz
|Molybdenum health issues||Elizabeth Truslow-Evans
Dept. of Health Services (DHS)
|Molybdenum treatment||Glen Schlueter
Dept. of Safety & Professional Services (DSPS)