Managing natural resources involving two or more states can easily threaten regional or even world peace and stability. With the growing demand over water resources and the quest for control by riparian states, conflict is increasingly becoming inevitable. This book examines the impact of the Gilgel Gibe III hydroelectric power project of Ethiopia on the Omo Basin (Ethiopia) and Lake Turkana (Kenya) as a source of potential conflict. The ambiguity surrounding an adequate agreement on the Omo-Turkana watercourse may worsen the already fragile peace in the Horn of Africa. This study, therefore, suggests Preventive Diplomacy as a method of conflict resolution through early warning and preventive measures, in accordance with international laws, to avert potential conflicts. This work can be of great help to governments, NGOs, environmental activists and anyone concerned with peacebuilding, diplomacy, conflict management and prevention especially in Africa and around the world.