Groundwater circulation is an important process in irrigation, mining activities and town water supplies. Tracers that undergo different degrees of re-equilibration with the atmosphere during this recirculation process can enable ambient groundwater and recirculated groundwater to be differentiated. In this paper, the recirculated groundwater has been pumped to dewater open pit mines, and discharged into ephemeral creeks. Some of this water subsequently recharged back into the aquifer. CFC-12 (which completely re-equilibrates on exposure to the atmosphere), 14C (partial re-equilibration) and 3H (no re-equilibration) are used in a four end-member mixing analysis to differentiate between (1) ambient groundwater, (2) recirculated groundwater, (3) river recharge from natural flows prior to commencement of mining operations (in 2007), and (4) natural river recharge post-2007. Sampling of the surface water when discharge of mine water was the only source of river flow enabled the extent of re-equilibration of both CFC-12 and 14C to be accurately determined. Since CFC-12 re-equilibrates more rapidly than 14C, recirculating groundwater had a CFC-12 concentration which was close to modern, but a 14C activity that was higher than the original groundwater, but less than modern recharge. Since 3H does not re-equilibrate with the atmosphere, it enabled differentiation between stream recharge due to infiltration of mine water discharge and that due to natural creek flows. Uncertainty of end-member compositions is due to changes in the end-member concentrations over time in the case of natural river flows, uncertainty in the extent of tracer re-equilibration for the groundwater recirculation end-member, and spatial variations in the composition of the ambient groundwater end-member. The mean uncertainty of end-member fractions was estimated to be less than 12%.