Water resources management in modern Egypt about 3.5 BCM/year of municipal wastewater was being discharged into the Nile and the sea in 2002, out of which only 1.6 BCM/year (about 45%) were treated. Industrial effluents contribute to about 1.3 BCM/yr of wastewater being discharged to surface waters, only some of which is being treated. Hydropower. An important use of water in Egypt is for the production of hydropower. This use is non-consumptive and is thus available for other uses further downstream. Hydropower plants exist at the Aswan High Dam (2100 MW), the old Aswan Dam (270 MW)and power plants at the Esna (90 MW) and Naga
Aswan Low Dam in the lower Nile. The dam, originally limited in height by conservation concerns, worked as designed, but provided inadequate storage capacity for planned development and was raised twice, between 1907 and 1912 and again in 1929–1933. These heightenings still did not meet irrigation demands and in 1946 it was nearly over-topped in an effort to maximize pool elevation. This led to the investigation and construction of the Aswan High Dam upstream. The earliest recorded attempt to build a dam near Aswan was in the 11th century, when the Arab polymath and engineer Ibn al-Haytham (known as "Alhazen" in the West)