Its hidrogrfica basin represents 8% of domestic territory and 57% of the area of the half-barren one. They are 32 sub-basins, 168 tributaries and involves 505 cities. Its flow is interrupted by two barrages for energy generation, of Sobradinho and of Itaparica, in the verge between the Bahia and Pernambuco. The waters that feed the San Francisco are proceeding from water of rains and underground reservoirs (aquferos). The pluvial regimen of the region is known that, possesss a regimen of short period, which had to the climate and the rain scarcity in all basin, with low pluviomtricos indices in certain periods of year. The basin of the San Francisco is extensive, 2.800km of extension, meets in this region a varied ecosystem, therefore it cuts five states and its hidrogrfica basin is inserted in seven states, with diverse conditions. The pluviomtrico index in the basin of the San Francisco varies of 1.900mm in its spring in Minas Gerais 400mm in the half-barren hinterland northeastern. The river meets in advanced period of training of degradation, with the deforestation of the ciliares bushes and the areas of springs, with ousting of sewer and garbage – domestic servant and industrial of the mineradoras, pans of it and the farming activity, consequence of the action human being.
This problem is preoccupying, therefore only 5% of the sewer in the cities in the basin possess treatment. Impacts that the Project can cause: It was identified 40 impacts, being 23 of bigger relevance more than, considering that 11 is positive and 12 negatives. Between the positives we can cite: # the increase of offers and the hdrica guarantee, generation of jobs and income, dinamizao of the economy regional, increase of offers of water for the urban supplying, water supply for the agricultural populations, reduction of the exposition of the population the emergenciais situations of drought, dinamizao of the agricultural activity and incorporation of new areas to the productive process, improvement of the quality of the water in the receiving basins, reduction of the agricultural exodus and the emigration of the region, reduction of the exposition of the population the illnesses and deaths, reduction of the pressure on the health infrastructure.