During March 1988 a major flood inundated the Orange River mouth. Observations on the impact of the flood on the biota of this region are presented. A total of 315 ha of wetland vegetation was destroyed, either by erosion or by deposition of coarse sediments. Birds appear to have been the most severely affected component of the fauna. Piscivorous birds were unable to locate prey in the turbid water, whereas wading species were deprived of suitable foraging areas. Observations made during a follow-up visit in October 1988 suggest that there will be no long-term negative impact as a result of the floods.