 Dams not only interrupt linear water flow and cause major geological channel shifts, but also limit the amount of water available to fishes in lakes, streams and rivers  and have the potential to change the trophic structure because of these alterations of the habitat and the limitations to movement and connectivity.Unnatural water flow below dams causes immense habitat degradation, reducing viable options for aquatic organisms.Upstream migration is hindered by the dam structure and can cause population declines as fishes don’t have access to normal feeding and/or spawning grounds.