Evidence from previous archaeological surveys, and field sampling undertaken for the present study, shows that the mid-Pleistocene to recent Holocene and historical sequence is well represented in the lower Orange River valley. Dam construction will inundate important archaeological sites and possibly damage others in the course of construction. Of the two potential dam construction sites, the Vioolsdrif option would have the greater impact on the archaeological remains. It is recommended that a detailed archaeological survey and mitigation programme should form part of the feasibility study for dam construction. An integrated archaeological programme could be carried out in the space of approximately two field months. The results of such a programme would effectively mitigate damage to the archaeological record and provide a significant contribution to archaeological knowledge.