This data release includes raw and processed (inverted) data for three different geophysical methods, continuous resistivity profiles (CRP), direct current electrical resistivity tomography (ERT), and frequency domain electromagnetic induction (FDEM) data. These surface geophysical methods were used as a proxy for groundwater salinity in the Paradox Valley in western Colorado to investigate temporal and spatial variations in the position of brine-rich groundwater under the Dolores River. Continuous resistivity profile surveys along a 8-10 km reach of the Dolores River were conducted on March 7, May 16, and September 13 of 2017. The ERT surveys were conducted along 3 lines crossing the river and 1 line parallel to it during March 6-10, 2017. The FDEM surveys were conducted along the same paths as the CRP and ERT surveys. Some additional land-based FDEM surveys were conducted using an all-terrain vehicle (ATV). Below is a brief description of each attached file in the data release: 1. The file 'CRP_data.csv' includes raw data for all 4 of the CRP surveys of the river including one in March, two in May, and one in September. The columns titled 'date' and 'time' in the file differentiate data from the 4 surveys. 2. The file 'ERT_data.csv' includes data for all the ERT surveys, 3 crossing the river and 1 parallel to it. The columns titled 'Survey Description', 'survey geometry', and 'electrode spacing' can be used to differentiate data for the individual surveys. 3. The file ‘ERT_electrode_positions.csv’ includes the coordinates for the 56 electrodes in each ERT survey. 4. The file ‘FDEM_data.csv' includes GEM-2 data from the river and ATV land-based surveys. The columns titled 'Description', 'Land or Water', 'Mode', 'Date', and 'Run' can be used to differentiate data for the individual surveys. 5. The file 'QW_data.csv' includes GPS coordinates and water depth, temperature, and specific conductance for the CRP river surveys. The column titled 'DateTime' differentiates data for the March, May, and September surveys. 6. The image 'River_surveys.jpeg' shows the approximate path of each river-based CRP and FDEM survey and apparent conductivity based on 1530 Hz FDEM data. 7. The image 'ERT_survey_location_map.jpg' shows the approximate path of each ERT survey. 8. The image 'FDEM_ATV_surveys.jpg' shows the path of the ATV surveys and apparent conductivity based on 1530 Hz FDEM data collected in May 2017. 9. The file 'PVU_RiverCRP_inverted_conductivity.csv' contains the CRP inversion results from the four different river surveys (March, May first run, May 2nd run, and September). 10. The file 'PVU_ERT_inverted_conductivity.csv' contains the inversion results from the March 2017 ERT surveys. 11. The file 'PVU_RiverFDEM_inverted_conductivity.csv' contains the FDEM inversion results from the four different river surveys (March, May first run, May 2nd run, and September). 12. The file 'PVU_FDEM_inverted_conductivity.csv' contains inversion results from all of the March 2017 FDEM surveys (including walking, river, and ATV).