WQ1405:             Arsenic in Groundwater - The Unknown Threat

Speakers:            Douglas Schnoebelen, PhD; Sophia Walsh


Public wells in the United States are regularly tested for arsenic, but private wells typically are not. However, when arsenic was found in 47% of wells tested in Iowa in 2008, a case study was designed to determine the source. This pilot study in Cerro Gordo County tests 29 parameters of wells and maps them against their depth and source aquifers. See which factors are associated with arsenic contamination in groundwater, recommendations for avoiding contamination, and how researchers, public health officials, and private wells drillers built a successful team to serve the homeowners for this serious threat.



Arsenic in Groundwater is a known problem in Iowa and health risks associated with consuming arsenic laden drinking water are numerous.  A three year study ending in 2008 found that in 47% of the wells tested throughout Iowa, arsenic was present. The next step was to find out why the arsenic is present in the groundwater. This project was designed to reveal how arsenic can be avoided when new wells are drilled and how to assess if operating wells are at risk for arsenic levels above the Safe Drinking Water Act Maximum Contaminate Level of 10 parts per billion for public water supplies. 

This presentation examines the initial results of the ongoing Centers for Disease Control and Prevention funded study in Cerro Gordo County, IA that has focused on what indicators are found in arsenic contaminated private wells.   Testing is being done on approximately 50 wells for 29 parameters including pH, temperature and flow rate as well as total arsenic, arsenic speciation, alkalinity, hardness.  Wells and well depths have been mapped in order to allow comparison between wells in different aquifers.  State and local government officials, public health professionals and well contractors will be interested in the findings of this study.