The Illinois EPA Source Water Assessment Program (SWAP) protects drinking water for more than 11 million people. This resource outlines the purpose of Illinois SWAP, the types of water supplies to be assessed, and the expected results from SWAP.
The Indiana Department of Environmental Management conducts source water assessments for public water systems. This webpage provides links to access all available source water assessments for Indiana, which details drinking water sources and their susceptibility to contamination.
The PA DEP open data portal provides GIS data for drinking water, water quality, and other resources.
The Minnesota Department of Health provides GIS shapefiles on drinking water protection area, as well sampling results of manganese, radionuclides, nitrates.