Long-term water use of a plantation of river red gum ( Eucalyptus camaldulensis) was estimated using a groundwater hydrographic separation technique and compared with transpiration rate estimated by sap flow measurements using the heat pulse method. The recession components of hydrographs of wells inside and outside the plantation were compared for a period of 24 months. During summer the difference in gradient between the two well locations was assumed to equal the water use by the plantation. With this assumption, the hydrograph separation technique allowed differences between rates of transpiration to be estimated. Water use was found to range from 0.9 to 1.3 mm day −1 in summer, based on analysis of the recession curve, and 0.95 mm day −1 in winter, based on the accession curve. Stand transpiration, estimated by the heat pulse method, was found to be 0.96 mm day −1. In native woodland where water levels are deeper (up to 16 m) the ascending components of the hydrographs of wells inside and outside the woodland were used to estimate the water use of the woodland. This was found also to be 0.9 mm day −1.