Effects of Sediment‐Control Operations on Fish and Macroinvertebrate Communities in Dam Reservoirs

ABSTRACT Sediments are avoided in many river and dam managements because of their adverse effects on water usage and flood control. Recently, sedimentation control measures, including sluicing, have been employed to manage sediments in river channels and restore communities in dammed rivers. Sediment sluicing is a technique used to control sedimentation in reservoirs by allowing sediment‐laden water to pass through dams during high‐flow events by establishing lotic conditions. Although sluicing operations can provide sediment and increase community diversity in river channels below dams, their effects on reservoir fauna remain unclear. Therefore, this study aimed to investigate the effects of sluicing operations on fish and benthic invertebrate communities in two reservoirs using 14‐year monitoring data. Our results showed significant increases in total nitrate in water and oxidation–reduction potential at the bottom, decreases in suspended solids in winter, and reductions in taxon richness and total density of summer macroinvertebrate communities after sluicing operations. However, the results suggested that the population of macroinvertebrates and fish recovered over time after each dam operation. In conclusion, although sluicing operations reduced reservoir biota, macroinvertebrate and fish richness were restored within a few months after the operation, suggesting that the impact of dam operations on biota may be minimal.