Aswan Dam assumption did not take into account the extent of perennial irrigation that was already present throughout Egypt decades before the high dam closure. By the 1950s only a small proportion of Upper Egypt had not been converted from basin (low transmission) to perennial (high transmission) irrigation. Expansion of perennial irrigation systems in Egypt did not depend on the high dam. In fact, within 15 years of the high dam closure there was solid evidence that biharzia was declining in Upper Egypt. S. haematobium has since disappeared altogether. Suggested reasons for this include improvements in irrigation practice. In the Nile Delta,
Economy of Egypt EuroAfrica Interconnector pointing out its importance for energy security of three countries.< Irrigation plays a major role in a country the very livelihood of which depends upon a single river, the Nile. Most ambitious of all the irrigation projects is that of the Aswan High Dam, completed in 1971. A report published in March 1975 by the National Council for Production and Economic Affairs indicated that the dam had proved successful in controlling floodwaters and ensuring recurring water supply, but that water consumption had been more than needed and shall be controlled. Some precious land was lost below the dam