Yeah, it's not obvious what trouble a big dam can cause--aside from the collapse concern. I myself come down in favor of small hydropower facilities, thought my river runner friends think I'm a traitor. It just makes sense to me to provide local power for cities with whatever resource they have in abundance. But powering a nationwide grid with one source, and selling that power outside a nation, is a bid for additional profits by the corporations that own the government. And frankly I think it's wrong for moneyed interests to destroy the lives of millions of self-sustaining rural people and to furthermore drown vast areas of rich floodplain land. We need those farmers and gatherers and plant species on this planet.