<Tr> <Th_colspan="2"> Basin features </Th> </Tr> <Tr> <Th> Basin size </Th> <Td> 325,000 km (125,000 sq mi) </Td> </Tr> <P> The Blue Nile (Ge'ez ጥቁር ዓባይ Ṭiqūr ʿĀbbāy (Black Abay) to Ethiopians; Arabic: النيل الأزرق ‎; transliterated: an - Nīl al - Azraq) is a river originating at Lake Tana in Ethiopia . With the White Nile, it is one of the two major tributaries of the Nile . The Blue Nile supplies about 80% of the water in the Nile during the rainy season . </P> <P> The Blue Nile is so - called because floods during the summer monsoon erode a vast amount of fertile soil from the Ethiopian Highlands and carry it downstream as silt, turning the water dark brown or almost black . </P>

What is the source if the nile river