Electricity generated from dams is by far the largest renewable energy source in the world. More than 90 per cent of the world’s renewable electricity comes from dams. Dams have also been used to store water for agriculture and household uses for thousands of years. Here are some of the well-known dams and reservoirs in Kenya, according to Kenya Electricity Generating Company (KenGen) and Global Energy Observatory
1. Masinga Dam
Straddling the border of Embu and Machakos Counties in the former Eastern Province, the scenic dam is the main reservoir in the cascade with a capacity of 1.56 cubic metres of water and is therefore used for water regulation throughout the year.
Two vertical Kaplan turbines drive two generators capable of generating 40 megawatts (MW) of power. The power generated at Masinga is transmitted to Kamburu and Mt Kenya Region. From Kamburu, power is transmitted to Nairobi through two 220kv lines.
The reservoir occupies a surface area of 120 square kilometres. The power station was conceived in 1960s after the commissioning of Kindaruma power station in 1968.
2. Kamburu Dam
It is the second major station in Kenya that supplies huge electrical energy. It took seven years for the construction to come to a considerable end.
It is found along river Tana and is one of the Seven Forks dams. The dam is also used as a source of water for the neighbouring people. Primary purpose of the dam is hydroelectric power generation and it supports a 93MW power station. It was built in 1971 to 1975, making it one of the oldest dams.
The 52 metres and 171 feet tall dam creates a reservoir with a capacity storage of 123,000,000 cubic metres.
3. Kiambere Dam
The primary purpose of the dam is hydroelectric power generation and it supports a 165MW power station. Construction on the dam commenced in 1983 and it was completed in 1987. The power station operated by KenGen is part of the Seven Forks Scheme.
The 110 metres (360ft) tall dam withholds a 585,000,000 m3 (474,000 acre ft) reservoir with the assistance of another earth-fill saddle dam to the northwest. Water from an intake on the saddle dam travels through a 4,060 metre (13,320 ft) head race tunnel to the power station which is located underground.
4. Gitaru Dam
The Gitaru Hydroelectric Power Station, also known as the Gitaru Dam, is the biggest station in terms of installed and effective capacity.
The highest recorded combined output was on May 22, 2002 when the output was 222MW and in November 2006 the unit recorded 220MW during one evening peak.
The number of units installed are three, producing a total capacity of 225MW which is the biggest hydro in East Africa. Number one was commissioned in 1999 with a rated capacity of 81.5.MW. The second and third units were installed the same year rating a capacity of 72.5MW.
The 30 metres (98 ft) tall dam withholds a 16,000,000 cubic metres reservoir. The relatively small reservoir relies on steady releases from the Masinga and Kamburu Dams upstream.
5. Ndakaini Dam
The dam is owned by Athi and operated by the Nairobi City Water & Sewerage Company and was known as Thika Dam. Construction started in 1988 when the government compulsorily acquired about 1,200 acres of land to create space for its construction to supply portable water to the residents of Nairobi and its environs.
The dam has a storage capacity of 70,000,000 cubic metres at full storage level of 2,041 metres above sea level and a depth average of 65 metres.
It produces 430,000 cubic metres per day of water, that is about 84 per cent of total supply of water to Nairobi residents.The dam’s catchment area measures 75 square kilometres and consists of Kimakia and Gatare Natural Forest which form Aberdare Ranges.
The main rivers that drain into the dam from this catchment are Thika, Githika and Kayuyu. Thika drains 50 per cent, Githika 30 per cent and Kayuyu 20 per cent of the catchment into the dam respectively. The area receives ample rainfall of between 2,000 and 2,500 milimetres annually.
6. Turkwel Dam
Turkwel Hydroelectric Power Station, also known as Turkwel Dam, is an arch dam on the Turkwel River about 76 km north of Kapenguria in West Pokot County. The dam serves several purposes including hydroelectric power production, irrigation tourism and fisheries.
The dam, Kenya’s tallest, has a height of 153 metres (502 ft), crest length of 150metres, dam volume of 170,000 cubic metres (6,000,000 cu ft) and retains a water volume of 1,641 million cubic metres. The project was completed by the French in 1991.
7. Kindaruma Power Station
Also known as Kindaruma Dam, the station situated 170 km north east of Nairobi straddles the border of Embu and Machakos counties .
Commissioned in 1968, Kindaruma was the first major power station in independent Kenya. It was originally designed with a provision of three turbine generator units. However, two vertical Kaplan turbines were installed.
The third unit has been installed with a capacity of 24MW thereby increasing the station’s output to 72MW and an upgrade of the first two units is currently underway. Power from Kindaruma is transmitted directly to Nairobi or to Kamburu via a 132KV substation.
Kindaruma is a surface power station and visitors have the luxury of observing the flow of water out of the tailrace.The spillway has three vertical gates and the dam is equipped with an emergency spillway in case of excessively high floods.
8. Sondu/Miriu hydropower station
The Sondu/Miriu Hydropower Station was developed by KenGen and has an installed capacity 60MW. Unlike other stations in Kenya, Sondu Miriu situated near Kisumu in western Kenya does not have a major dam and associated large reservoir but relies on the flow in the river with only a small storage capacity at the intake. It was funded by the Japan Bank for International Cooperation, with KenGen meeting part of the cost.
Water is diverted from the Sondu River at the Intake through a 6.2km long tunnel. A surface mounted penstock takes the water down the Nyakach escarpment to the Power Station below.
In the Powerhouse, harnessing the water and the head, the turbines are turned to generate the electricity.The water is then returned to the Sondu river approximately 13km downstream of the intake via a 4.7km long outlet channel.
9. Maruba Dam
Originates from the famous river Maruba that is the main source of water for the town of Machakos. The town has a population of about 210,000 people with a water demand of about 8000m3/day.
The storage capacity of the dam has gone down over the years as a result of continued siltation in rivers. However, the dam is still being expanded and several other projects coming from it.
10. Nairobi Dam
It is an embankment dam on the Nairobi River. The Dam constructed in 1953 holds back a reservoir with storage capacity of 98,000 m3 and surface area of 350,000 m2).
It is a shallow lake with an average depth on only 2.76 m (9.1 ft). Inflow is from the Motoine River, from rainfall, and waste water from the unsewered Kibera settlement.
Outflow is through evaporation and over the spillway into the Ngong River.The dam is heavily silted and areas have been reclaimed for agriculture by dumping solid waste.