As part of its mission to provide scientific information to help manage natural resources, the USGS is conducting 42 projects in 34 states and Puerto Rico in support of source-water assessments. In aggregate, these studies help assess and protect drinking water for 83 million people, which makes the USGS the largest provider of source-water information in the nation. Several projects are applying innovative research tools developed by the USGS, such as ground-water age dating using freon compounds. Some of the USGS projects focus on a particular aspect of source-water assessments, such as delineation of source areas or mapping the occurrence of specific contaminants such as pesticides, nitrates, solvents, fuel components, microbes, or arsenic in source areas. Other studies cover the complete delineation and assessment process.
Some studies are specific to a county or city, while others cover an entire state.