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The flow of groundwater into a stream is difficult to quantify. Several techniques exist, however they all have limitations with both practicality and accuracy being difficult to achieve. This study develops a method that is accurate, within the limits of input data, and practical for use in areas where groundwater inputs into rivers have a detectable level of some tracer (in this case salt). The study is undertaken on the Darling River in northwestern New South Wales, Australia. This study used a one-dimensional hydrodynamic model (MIKE 11) of the river with the coupled advection-dispersion module to model the transport of salinity concentrations. Using a simple mixing model, a time series of saline groundwater discharge was generated and input into the hydrodynamic model. The resulting saline-groundwater discharge hydrograph agrees with conceptual understanding of groundwater-surface water processes and reasonably approximates the actual measured EC values in the river.