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Arsenic – Occurrence in Wisconsin

Private well sampling Map 2014 - 2019
Beginning in 2014 the department has required arsenic sampling when pump work is done on existing wells. The map is from the 35,000+ samples collected over the first four and a half years. The map depicts the percent of wells over 10 ppb arsenic in each county - see tabular data. This analysis shows that arsenic is more widespread than previously thought.
Private well sampling Map 1988 - 2000
This map displays private well samples in the state with a concentration of arsenic greater than 10 ppb. The data is from the Groundwater Retrieval Network Database covering from 1988 - 2000.
Public well sampling Map 1973 - 2000
This map displays public well samples in the state with a concentration of arsenic greater than 10 parts per billion (ppb). The data is from the DNR Public Water Supply Database covering from 1973 - 2000.

Tables summarizing sampling from public wells and private well town-based sampling for arsenic

Public well sampling Data 2000
In 2000 the DNR sponsored a special sampling program to investigate arsenic occurrence in public wells. The sampling was designed to gather comparable data from all public wells and to maximize arsenic occurrence. For municipal wells (MC) a time was calculated for each well that was equal to 0.8 well volumes divided by the pumping rate. For other than municipal (OC) and non-transient non-community (NN) wells average times of six and seven minutes were used. The results are presented for both the wells and systems.
Town based sampling Data 2000 - 2003
The department, along with Department of Health Services, Department of Safety and Professional Services and Local Health Departments sponsored sampling of private wells by civil towns in Outagamie and Winnebago Counties. The results are presented by town for the number of samples and percentage of samples above a given arsenic concentration level.

DNR well and water sample databases