A preliminary investigation was made into two aspects of the inter-relationships between groundwater discharge and streamflow in the Wilson Creek Watershed. The first aspect was to evaluate the relationships between the major dissolved ions in the stream (varying both with time and distance from the source) and the groundwater. The second was to attempt a baseflow separation of a peak-flow hydrograph using characterising groundwater ions. Sulphate was used as the characterising ion because of the evidence of its being representative of the groundwater. The stream water was found to be from local and not deep groundwater reservoirs, because of the downward hydraulic gradient in the piezometers, and their chemical characteristics. Consistent results utilising the relationships between the sulphate content and streamflow in calculating the groundwater discharge in a flood peak indicate that this method of baseflow separation is likely to be representative. This assumes a limited dilution of the groundwater component.