Aswan Dam in Egypt had to be dredged regularly to remove sediments. After construction of the dam, aquatic weeds grew much faster in the clearer water, helped by fertilizer residues. The total length of the infested waterways was about 27,000 km in the mid-1990s. Weeds have been gradually brought under control by manual, mechanical and biological methods. Mediterranean fishing and brackish water lake fishery declined after the dam was finished because nutrients that flowed down the Nile to the Mediterranean were trapped behind the dam. For example, the sardine catch off the Egyptian coast declined from 18,000 tons in 1962 to a
Economy of Egypt border, behind the Aswan High Dam. Just north of Cairo, the Nile spreads out over what was once a broad estuary that has been filled by riverine deposits to form a fertile delta about wide at the seaward base and about from south to north. Before the construction of dams on the Nile, particularly the Aswan High Dam (started in 1960, completed in 1970), the fertility of the Nile Valley was sustained by the water flow and the silt deposited by the annual flood. Sediment is now obstructed by the Aswan High Dam and retained in Lake Nasser. The interruption