Internationally, when more than one country controls portions of a river basin, respective rights to water supplies need to regulated by negotiations and treaties; hydrology points to collaborative efforts as the key to optimum utilization of scarce water resources. Frequently, however, the politics of water resource allocation become enmeshed with other quarrelsome issues, aggravating international tension between neighbouring countries. Hydropolitics can be the first step in promoting collaborative relations across borders, but can also lead to sharpened international tension. Indeed, water resources represent a great potential for conflict because of competing demands on limited supplies or because of deterioration in quality through use. Conflicts exist both within national boundaries and between adjacent countries.