 The study analyzes 41,081 data points from 17 basins in the southwestern United States to estimate the distribution of fresh and usable deep groundwater for potential human consumption and irrigation. The Great Basin has the largest percentages of fresh and usable deep groundwater with low toxic and trace element concentrations, making it a promising resource for irrigation use without treatment. This article was authored by Mary Kang, James E. Ayers and Robert B. Jackson.