The objective of this study is to assess the impacts of dam construction on downstream flow regimes and local livelihoods in the upper Srepok basin. This can by achieved by (i) field survey including interviews and group discussions and (ii) assessment of changes in flow regimes. The field survey was carried out to investigate the impacts of dam operation on flow regimes and local livelihoods. The flow regime changes in the study area were assessed by using the Indicator of Hydrologic Alteration (IHA) and Range of Variability Approach (RVA) methods to the historical data of streamflow before and after dam operation. The results from household interviews and group discussions indicate that local people have felt differing livelihoods impacts from hydropower projects. Although water resources have been managed by many agencies at different levels, the coordination is rather weak. The cooperation among sectors, between central and local government, and among provinces in the exploitation for multiple purposes has been found to be loose and inefficient. There is a "gap" in knowledge about the overlaps, gaps and conflicts between provincial and district levels. The results from flow alteration assessment shows that flow regimes have been altered after dam operation, particularly during the low and high pulses. It also suggests that in allocating water for better water resources management, the compromise between instream and offstream users/sectors should be carefully considered.