The study objectives were to review and update the findings of previous flooding investigations that have been carried out for Forbes. This included the update of flood frequency analyses that have been undertaken for several long-term stream flow gauges that are located in the Lachlan River and one of its major tributaries upstream of Forbes, and to develop of hydrologic and hydraulic models that would enable patterns of main stream flooding to be more accurately defined for floods with Annual Exceedance Probabilities ranging between 50 and 0.2 per cent, as well as for the Extreme Flood.