EN
Several cases of the developing water crisis in semi-arid regions of Tanzania are described. Some cases have transboundary causes. These include Lake Victoria and the riparian population as a result of hydroelectricity developments in Uganda, the Serengeti ecosystem threatened by deforestation of the Mau forest and irrigation in Kenya, and several national parks threatened by irrigation projects within Tanzania. Some of these developments are given national priorities like in case of the Great Ruaha River. Other irrigation projects are driven by the local population to combat poverty. Most of these developments are in breach of state laws because there is no consideration of minimal environmental flows and all have profound negative impacts on people and wildlife downstream. The paper describes the previously unreported case of irrigation in the upper Katuma River that flows into Lake Rukwa, which lead to poverty increase, environmental degradation and a decrease in ecosystem services provision downstream. Governance at the watershed scale in a framework compatible with ecohydrology principles is needed. Such solutions are proposed.