The Nile River is the longest river in the world and unquestionably the life blood of Egypt. Throughout Egypt’s history the Nile River has provided water for drinking, irrigation, and replenishment of fertile soils. About 95 percent of Egypt’s population lives within 12 miles (20 kilometers) of the river’s banks or on its delta. This segment of the Nile River has been modified by the construction of the Aswan High Dam. The dam is barely visible toward the northern edge of the photograph. This project was begun in 1958, and the dam was dedicated in 1971. The 365-foot-high (110-meter-high) dam created Lake Nasser, one of the world’s largest artificial lakes. A series of photographs of Lake Nasser, taken in different seasons and years, is useful in mapping the seasonally influenced fluctuating water levels in the lake. Water levels are normally lowest during April and May; then during the summer months the water level rises. The dam has dramatically (1) changed how Egyptians irrigate their fields, (2) increased oil-poor Egypt’s hydroelectric power generation, and (3) curtailed flood control problems. The inundated area created behind the Aswan High Dam extends into a small area of north-central Sudan.