The impacts of hydropower developments on local environment, ecology, and socio-economics, has influenced, and will continue to influence, the efficacy in decisionmaking and planning/design processes. Big dams have several disadvantages: (a) high costs, (b) possible collapse, (c) evaporation loss, (d) flooding of prime agricultural land, (e) siltation of reservoir, (f) salt-water intrusion in coastal areas, (g) deforestation and ‘greenhouse’ effect, and (h) destruction of habitat for rare species. We must refine our environmental understanding of how hydropower development affects species, both individually and in their interactions with each other. The utter dependence of organisms on appropriate environments is what frustrates most attempts to proceed with development and still protect ecosystems and wider ecocomplexes. Conservation objectives must be integrated with other objectives in formulating national and other policies, before they crystallize into projects and programmes. When ecological factors are considered only at the end of the process, they are liable to be viewed as obstructing development, which can be disastrously wrong. But if integrated at the basic level of decision-making, they can positively guide development most propitiously and beneficially. Translated to the global context, this is best served by holistic thinking.