Ohio EPA collects and reports information on groundwater quality, and provides data from groundwater monitoring.
The Indiana Department of Environmental Management's Ground Water Section maintains the Indiana Wellhead Protection Program. Indiana's Wellhead Protection page includes information on project implementation and featured communities.
The Minnesota Wellhead and Source Water Protection Programs prevents contamination by requiring public drinking water supplies to identify critical supply recharge areas and adopt management strategies to protect water supplies. This webpage by the Minnesota Pollution Control Agency provides additional resources and guidance for water systems, including maps of petroleum remediation.
The U.S. EPA Drinking Water Action Plan outlines challenges facing drinking water infrastructure, and presents priorities for improving drinking water.
The Minnesota Department of Health provides GIS shapefiles on drinking water protection area, as well sampling results of manganese, radionuclides, nitrates.
The EPA's DWMAPS is an online mapping tool designed to help concerned citizens and resource managers find information about drinking water in their communities and take action to protect their source water.