From WaterWiki

The decision making processes which determine where and how water is used and managed are both political and economic. A vital resource, water is more and more intensely managed, by both political entities and water users.

Fundamental questions need to be answered as to how water should be allocated. Many waterways throughout the world are shared between several countries, and often countries may be downstream and rely on two or more countries to ensure enough water travels down to meet everyone's needs.