This data release contains data used to develop linear regression models to calculate continuous chloride concentrations in groundwater and runoff at an urban rain garden in Gary, Indiana. A python script was developed to perform the regression analysis and estimate sodium chloride (NaCl) loading to 5 rain-garden flumes as the product of: (1) the estimated continuous (one-minute) chloride concentration, (2) the mass ratio of sodium chloride to chloride, and (3) continuous flume discharge. The python source code used to execute the regression model and loading calculations is included in this data release in the zipped folder named Model_Archive.zip. The regression input (discrete specific conductance and chloride concentration data), chloride concentration model input (continuous specific conductance data) and NaCl loading model input (continuous flume discharge and specific conductance data) that were used to estimate chloride concentrations at 3 USGS monitoring wells (413610087201001, 413612087201301, 413611087201004) and NaCl loading at 5 USGS rain garden flume monitoring stations (413611087201101, 413611087201001, 413612087200901, 413611087200901, 413611087201002) are also included as part of the model archive (Model_Archive.zip). The model output consists of 3 .csv files for the USGS monitoring wells with estimated continuous (hourly) chloride concentrations (mg/L) and 5 .csv files for the USGS flume monitoring sites with estimated continuous (1-minute) chloride concentrations (mg/L) and NaCl loading (grams) that are presented in the zipped folder Model_Output_Data.zip.