The Nairobi Dam is an embankment dam

Embankment dam

An embankment dam is a massive artificial water barrier. It is typically created by the emplacement and compaction of a complex semi-plastic mound of various compositions of soil, sand, clay and/or rock. It has a semi-permanent waterproof natural covering for its surface, and a dense, waterproof...

 on the Nairobi River

Nairobi River

Nairobi River is a river flowing through the Kenyan capital Nairobi. It is the main river of the Nairobi river basin, a complex of several parallel streams flowing eastwards. All of the Nairobi basin rivers join east of Nairobi and meet the Athi River, eventually flowing to the Indian ocean. These...

 in Nairobi

Nairobi

Nairobi is the capital and largest city of Kenya. The city and its surrounding area also forms the Nairobi County. The name "Nairobi" comes from the Maasai phrase Enkare Nyirobi, which translates to "the place of cool waters". However, it is popularly known as the "Green City in the Sun" and is...

, Kenya.

Background

The Dam constructed in 1953 holds back a reservoir with storage capacity of 98000 cubic metre and surface area of 350000 m² (86.5 acre). It is a shallow lake with an average depth on only 2.76 m (9.1 ft)

Inflow is from the Nairobi River, from rainfall, and waste water from the unsewer

Sewer

Sewer may refer to:* Part of sewerage, the infrastructure that conveys sewage*Effluent sewer, a collection system that transports only the liquid portion of wastewater through small-diameter pipes laid at contour...

ed Kibera

Kibera

Kibera is a division of Nairobi Area, Kenya, and neighbourhood of the city of Nairobi, located from the city centre. Kibera is the largest slum in Nairobi, and the second largest urban slum in Africa...

 settlement.
Outflow through evaporation and over the spillway into the Ngongo River.

The Dam is heavily silted and areas have been reclaimed for agrigulture by dumping solid waste, the water hyacinth

Water hyacinth

The seven species of water hyacinth comprise the genus Eichhornia. Water hyacinth are a free-floating perennial aquatic plant native to tropical and sub-tropical South America. With broad, thick, glossy, ovate leaves, water hyacinth may rise above the surface of the water as much as 1 meter in...

 plant is very common and has clogged the water preventing sailing and fishing.

Regeneration projects

Prime Minister Raila Odinga

Raila Odinga

Raila Amollo Odinga , also popularly known to Kenyans as Agwambo, is a Kenyan politician, currently serving as the Prime Minister of Kenya in a coalition government. He has served as a Member of Parliament for Langata since 1992, was Minister of Energy from 2001 to 2002, and was Minister of Roads,...

 announced plans to regenerate the Dam and when he met with the Nairobi Dam Trust Initiative on 14 September 2011.

He asked that it be made part of the Nairobi River Basin Project funded by the United Nations Environment Program with the tasks of removing the water hyacinth and solid waste to restore the aquatic ecosystem.
Also associated encroachment would need the settlements to be pulled down (Kibera is the second biggest slum in Africa, with 700,000 inhabitants) with an estimated cost of 700 million Kenyan Shilling

Kenyan shilling

The shilling is the currency of Kenya. It is divisible into 100 cents.-Coins:The first coins were issued in 1966 in denominations of 5, 10, 25 and 50 cents, and 1 and 2 shillings. Twenty-five cents coins were not minted after 1969; 2 shillings coins were last minted in 1971...

(7.3 million USD)