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About the Data

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Long-term exposure to arsenic, even at low levels, is associated with adverse health effects, including cancer of the bladder, lungs, skin, kidney, nasal passages, liver, and prostate. Other possible health effects include cardiovascular disease, developmental and reproductive effects, diabetes, and skin changes. The risks from exposure to arsenic depend on many factors, including the type of arsenic, the duration and level of exposure, and individual susceptibility, which can depend on things like age and genetics.

For more information, visit MN Public Health Data Access: Arsenic in Private Wells.

Data Notes
  • Of the 64,793 new private wells sampled, 48.4 percent had arsenic at concentrations above the typical detection limit of 2 µg/L and 11.3 percent had arsenic above the health-based value of 10 µg/L.
  • These data are limited to new private wells constructed and tested August 2008 to December 2021. Therefore, these data are not representative of all private wells in Minnesota.
  • The county arsenic values provide important information regarding arsenic concentrations and distribution in private well water in Minnesota. The extent of the Des Moines Lobe Till can also be used to identify areas where higher arsenic concentrations may be found. However, the county data and till information cannot be used to predict arsenic concentrations in individual wells. The only way to know the arsenic concentration in a well is to have the well tested.
  • Data are not currently available in the map for other contaminants of concern in private wells, such as bacteria and nitrate.
  • Counties with less than 20 total wells tested should be interpreted with caution; the data may be unstable because it can change dramatically with the addition or subtraction of one well. Unstable data are displayed with hash-marks on the map and an asterisk (*) next to the county name on the pop-up display and table.
  • For additional information pertaining to the data, please visit the "About the Drinking Water Quality Data" page.
Data Source
  • Minnesota Department of Health Well Management Database
For questions or more information regarding the mapping application, please contact the Minnesota Public Health Data Access
or via e-mail at: health.dataportal@state.mn.us

Table: Private Wells - Arsenic

Region Number of Wells Tested Number of Wells > 2µg/L Percent of Wells > 2µg/L Number of Wells > 10µg/L Percent of Wells > 10µg/L 95th Percentile Arsenic Value (^) Median Arsenic Value
County Number of Wells Tested Number of Wells > 2µg/L Percent of Wells > 2µg/L Number of Wells > 10µg/L Percent of Wells > 10µg/L 95th Percentile Arsenic Value (^) Median Arsenic Value

Unstable data (*)
95th Percentile Arsenic Value (^)

Feature

Unstable data (*)
95th Percentile Arsenic Value (^)