The U.S. Geological Survey collected groundwater samples from 17 wells in the Indio subbasin (CA basin designation 7-21.01) of the Coachella Valley and surface water samples from two sites representing sources of recharge to the Indio subbasin in 2021. These samples are intended to provide inorganic water quality data, particularly total dissolved solids (TDS), within areas of the Indio subbasin not sampled for the Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project’s assessment of the quality of groundwater used for domestic and small system drinking water supplies in Coachella Valley (CODA). Other areas of special interest for the Indio salinity study were nearby managed aquifer replenishment facilities. Various well types were sampled including domestic, public supply, irrigation, and monitoring wells. The two surface water samples were collected in order to better understand primary sources of recharge to the Indio subbasin: the Whitewater River and the Colorado River via the Coachella Canal. Groundwater samples from all 17 wells were analyzed for field water-quality parameters, major ions and trace elements, chromium (VI), perchlorate, nutrients, carbon-14 in dissolved inorganic carbon, stable isotopic ratios of water, tritium, isotopes of sulfur in sulfate, sulfur hexafluoride, and noble gases. Groundwater levels were measured in 9 of the 17 wells. Surface water samples from both sites were analyzed for field water-quality parameters, major ions and trace elements, chromium (VI), perchlorate, nutrients, and stable isotopic ratios of water. All results are presented in this data release except for the isotopic ratios of strontium and boron in water. Data collected from 23 wells sampled in the Indio subbasin for the CODA assessment are not included in this data release but can be found here: https://doi.org/10.5066/P9UYXI95