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Floods in the Salado River basin, Argentina, seriously affect both human activities and the environment. Inadequate and improper water management aggravates the effects of natural extreme events. The damage caused by the extreme flood in 1993 cost US$507 million, affected 14,500 farmers and flooded 6,500,000 ha within the basin. This paper analyses natural trends within the rainfall and riverflow records, and considers the possible effects of human interference. The river basin is mainly underlain by impermeable soils with a high water table. The soil factor and the low topographic gradients often produce surface run-off with slow lateral drainage. Very often, heavy rainfall associated with high soil moisture content leads to flooding of the basin. Three major flood events that have occurred since 1960 have been analysed. Flood occurrences have been placed in the context of precipitation variability and soil water storage. The precipitation records of two long-term stations in the basin (Junin and Dolores) show an increasing trend and this is due to rainfall increases in the warm season. However, none of the rain events reached the probable maximum precipitation of 100 year return period. The discharge records of the Salado River are compared with the pattern of the El Niño/Southern Oscillation and it is found that only the May discharge anomalies are weakly related to the El Niño driven climate variability. Results from this study are useful for the formulation of flood mitigation measures. The paper concludes with a consideration of the flood mitigation policy developed in Plan Maestro.