Kainji Dam: A Masterpiece, that took 20,000 men from nine different nationalities to construct.

Dam being a structure across a stream, river, or estuary is built to retain water. Dams are being built to meet demands for water for human consumption, irrigation, or industry; to actually reduce the peak discharge of flood water; to increase the depth of water in a river so as to improve navigation; to increase available water storage for generating hydroelectric power. Incidentally, it can be provided for recreation. A dam is also described as the central structure in a multipurpose scheme aiming at the conservation of water resources. The earliest recorded dam in history is believed to have been on the Nile River at Kosheish, where a 49-foot (15metre) high masonry structure was built about 2900 BC to supply water to King Menes' capital at Memphis. The oldest dam in use is a rock-fill structure about 20 feet high on the Orontes in Syria, built about 1300 BC. 

Dams are actually categorized into several distinct classes, by profile and by building material. Decision as to which type of dam to build depends largely on the foundation conditions in the valley and the construction materials available. Broadly, the choice of materials now lies between concrete, soils, and rock fill. Secondary works at a dam may include spillways, gates, or valves to control the discharge of surplus water downstream from the dam; an intake structure conducting water to a power station or to canals, tunnels, or pipelines for more distant use; provision for evacuating silt carried into the reservoir; and means for permitting ships or fish to pass the dam. The multipurpose dam holds special importance in less developed countries, where a small nation may reap enormous benefits in agriculture and industry from a single dam.

Kainji Dam was built in 1968, it was actually constructed across the Niger River, in Niger State, in North Central Nigeria (There are three major dams in Niger State, Nigeria. The Kainji Dam built in 1968, Jebba Dam built in 1985 and Shiroro Dam built in 1990. A fourth dam is being built at Zungeru, also in Niger State). Kainji Dam is the largest of the dams on the Niger, is 215 feet (66 m) high and 1,800 feet (550 m) across and provides electrical power, improved river navigation upstream to Yelwa in Kebbi state, water control of the Niger down to the Kaduna River confluence, and a road across the Niger. Its reservoir, Kainji Lake, supports irrigation and fishing projects in the states in which it lies. On its western shore, Lake Kainji National Park serves as a recreation centre. The Niger is also a source of hydroelectricity.

The Kainji Dam has a concrete main dam with rockfill embankments and a saddle dam. The saddle dam protects the main dam during flooding. There are four spillways with hydraulic operated gates of 15.2 x 15.2 m (50 x 50 ft), which could be opened to control flood and also to release water for use at the Jebba Dam downstream. It is 85.5 m (215 ft) in height and about 8 km (5 miles) in length. The lake is supplied with water from the upper Niger River and it flows from Futa Djarlon Island through Guinea, Mali, Sierra Leone, Senegal and Niger. The reservoir lake stretches some 136 km upstream and has a breadth of 24 km at its widest point. The maximum head elevation is 141.7 m (465 ft) and maximum tail elevation is 104m (330 ft). The lake has a total capacity of 15 billion cubic meters covering an area of 1270 square kilometres. The lake is one of the longest dams in the world.

Most of the structure is made from earth, but the centre section, housing the hydroelectric turbines, was built from concrete. A retrieved information from daily trust online states that the dam was designed to have a generating capacity of 960 Megawatts; however, only 8 of its 12 turbines have been installed, reducing the capacity to 760 Megawatts. The dam generates electricity for all the large cities in Nigeria. Some of the electricity is sold to the neighbouring country of Niger. In addition, occasional droughts have made the Niger's water flow unpredictable, diminishing the dam's electrical output. The dam has a single-lock chamber capable of lifting barges 49 metres (161 ft).

Kainji Lake measures about 135 kilometres (84 mi) long and about 30 kilometres (19 mi) at its widest point, and supports irrigation and a local fishing industry. Africasia.com also reported that in 1999, uncoordinated opening of floodgates led to local flooding of about 60 villages.

The dam which took almost five years to construct was built by Impregilo, a consortium of three Italian firms. It took 20,000 men of nine different nationalities to construct it. US$209 million was the total estimated cost, with one-quarter of this amount to resettle people displaced by the construction of the dam and its reservoir, Kainji Lake.