Gambella National Regional State is rich in water resources. The major rivers are the Baro, Akobo, Allewero and Gillo. All of these rivers have major tributaries large enouugh for the local population to depend on as far as irrigation and pasturalism purpsoses are concerned. The Baro-Akobo catchments are the Baro and its tributaries (Birbir, Geba, Sor), the Alwero, the Gilo with its tributaries (Gecheb, Bitun, Beg) and the Akobo with its tributary Kashu. The general direction of the rivers is from the east to the west. The rivers originate in the Ethiopian highlands (2000-3500m) situated in the east of the area and fall to the Gambela plain (450m) in the west. All the major rivers are gauged except the Akobo flowing at the border with South Sudan and all its tributaries. The Catchment area and mean annual flows in the Gilo river of the basin is 12, 815 km2 and 12, 784 Mcm/year respectively (TAMS-ULG, 1997). Gilo sub basin originates from Godere, Mengeshi, and partly from Dima woredas (districts). These woredas are the upper part of the basin covered with high forests that contribute for Gilo sub basin; the main tributaries are Gecheb, Bitun and Beg rivers. with so many rivers which provide local population not only with water but also with fishes s but also There are sa lot of rivers in Gambella which provides Ethiopia with fresh water and hydro electricity.
Gilo sub-basin has potential water resources which are mainly originated from the forest. The water resources are permanent and temporary rivers, springs, water falls (Jay in Godere woreda and Fejeji in Mengeshi woreda) Tata and Bure (Bishan Waka) Lakes. These water resources are used for drinking water supply, home of aquatic flora and fauna as fish, fishing, Crocodile and hippopotamus, tourist attraction, visual view attraction. Bure Lake is found in Mengeshi woreda and surrounded by the highly dense forest. It serves as recreational, fishing and boat purpose. The different rivers existed in the forest area are tributaries of the Gilo river sub basin. The Gilo river tributaries are found on the upper catchment area of the sub-basin. Some of the rivers are drying through time. Some of the existing rivers are Fejeji, Jay, etc….. (See the annex). According to the information available from interview and discussion of the communities and key informants, groundwater is available at near depth of the ground.
Gilo river is a potential resource with diverse natural resource for the communities of the sub basin mainly (Mejengir, Agnua and Nuer) and others for drinking of both livestock and people, a natural habitat for a large number of fishery resources, and the place where a large population take as a recreational place(swimming, or taking bath) especially during the dry season of the year. It also serve as boat transportation during the wet season through which peoples meet with their beloved ones living on the other side of the river as well as goods and consumable items also transported by the boat from one place to the other. For instance (the Agnua community living in the Gog district can meet with the Jore community taking the boat from Puchala to Shantawa only using the boat in the wet season as walking on foot is unthinkable due to over flooding of the Gilo river).
The upstream districts (Godere and Mengeshi) are also the source of many perennial and annual rivers including Godere, Jery, and other rivers join after a certain distance and make the Gilo