I am not a fan of the "water wars" motif that reporters and NGOs throw around; see this and this post.
Fleck mentioned a new research paper that points out water is more often associated with peace than war, and it got me to thinking...
Why would there be wars over oil or diamonds but not water? Or, are there wars over water for the same reason as there are wars over oil, etc.
No, I don't think that there are wars over water.
Ok, well there may be, but they are not "natural" or common. That's because of the nature of water -- as compared to resources like oil or diamonds.
If we fight a war over oil, and I win, then I get to keep it. You get nothing, and there's nothing you can do to keep me from "enjoying" the wealth from it. If you lose a war over water, you can "destroy" the water (through contamination) and then I can't use it.
The same principle kept us alive during the Cold War. MAD (mutual assured destruction) meant that the "winner" would also lose because the loser would have launched enough ICBMs to destroy the winner. Such an outcome made peace the preferred outcome (there were still proxy wars, but they did not go nuclear.)
So it's the risk of MAD that has instilled a "neutrality" around water in human cultures. The same holds for animals -- in times of drought, watering holes tend to be non-aggression zones among species that would normally kill or hunt each other. This changes if there is so little water in the hole that the animals start to go mad with thirst and fight. [At least that's what I read in Heart of Dryness :)]
Bottom Line: We cooperate in managing water resources because the alternative -- death for all -- is not worth fighting over.