Lower Kihansi dam, Tanzania

Small but damaging. Despite its relatively modest dimensions, the Lower Kihansi dam has been a source of high biodiversity loss, destroyed a unique ecosystem and almost caused the extinction of the Kihansi Spray Toad in Tanzania, among other flora species


What on the paper appears to be a relatively harmless dam, it revealed to be highly impacting in terms of biodiversity loss. In fact, the Kihansi Gorge is a unique ecosystem home to an enormous variety of plants and animals. Some of them, like the Kihansi spray toad and a species of wild coffee, used to live only in the downstream waterfall spray zone which course has been drastically altered after the dam construction [3] [4]. Initially funded by a USD$275 million loan to which the International Development Agency of the WB, the European Investment Bank and the development agencies of Norway (NORAD), Sweden (SIDA) and Germany (KfW) contributed [1], the dam was built by the government of Tanzania in order to meet the growing electricity demands of its mining and tourism industries [2]. The construction works of the Kihansi dam began in 1995 without a proper Environmental Impact Assessment (EIA), which did not include an analysis of the downstream impacts neither an environmental flow assessment. No potential ecological impacts were declared. Later on, several ex-post studies have been carried out by academics and development agencies after the discovery of the biodiversity richness of the downstream ecosystems and their endangered species [3] [4] [5] [6]. They all conclude that the dam is causing significant environmental damage and that is of clearly inadequate significance, as reduced the amount of silt and water coming down from the waterfall into the gorge by 90%. Just a short-term emergency project tried to recreate the spray zone conditions through an artificial sprinkler in order to stabilise the toad population, without being able to restore the original state of the gorge. Nowadays, civil society group locally and internationally (Friends of the Earth and International Rivers, among others) are now working to hold project donors responsible for it. The project did not impact just flora and fauna along the Kihansi river: about 16,000-20,000 people were estimated to live in the project area in 1990. 380 families had to be relocated [5] [7]. According to KfW agency, “the participation of the population in the project benefits was not achieved to the desired extent due to the accelerated spread of malaria” caused by the construction measures. [5] Apparently, while initially the remoteness of the highlands villages was protecting the local population from HIV and malaria, the relocation measures and the slowness of health protection measures implementation caused the illnesses to spread. Overall, it is to be considered an unsuccessful project which does not meet several guidelines of the World Commission on Dams [2], as (i) it did not maintain rivers with high ecosystem values in their natural states, avoiding negative impacts on endangered species; (ii) just a poor and incomplete EIS was carried out ex-ante; (iii) no environmental flow assessment was considered; and (iv) the Government of Tanzania is not forcing TANESCO to comply with existing water rights because of demands for power.

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Basic Data
NameLower Kihansi dam, Tanzania
ProvinceIringa Region
Accuracy of LocationHIGH local level
Source of Conflict
Type of Conflict (1st level)Water Management
Type of Conflict (2nd level)Dams and water distribution conflicts
Specific CommoditiesElectricity
Project Details and Actors
Project Details"The Lower Kihansi hydroelectric power plant is located about 450 km southwest of the capital Dar Es Salaam and 80 km south of the city of Iringa. [...] It was built between July 1995 - February 2000. The concrete gravity dam, which created a reservoir of one million cubic meters of water, has a maximum height of 25 m and a crest length of 200 m. The middle portion of the dam consists of an open spillway that is 70 m long, designed for a discharge capacity of 470 m³/s. A consolidation grout curtain was made along the entire length of the dam. Downstream of the spillway, work was done to protect against erosion with concrete retaining walls and rip-rap lining on the slopes. The intake structure,

located on the left bank of the river, is an integral part of the dam structure and incorporates a 10 x 6 m trash rack rake and a 4 x 5 m control gate. The project includes the following underground structures: a vertical shaft 5.64 m in diameter and 508 m long; a headrace tunnel with a cross-section of 30 and 37.6 m², 2,276 m long, with a slope of 1:7, which then branches off into three reinforced penstocks having a total length of 329 m; a main plant-access tunnel with a cross-section of 40.5 m², 1,807 m long, which has also additional sections, for an overall length of 2,280 m, allowing access to the transformer vaults; five outlet pipes with a cross-section of 22 m² and a discharge tunnel with a cross-section of 34 m², for a total length of 2,368 m; cable tunnel 1,765 m long;

other service tunnels of variable cross-section, for a total length of 526 m. The plant has an initial capacity of 180 MW, with three vertical Pelton turbines which utilise a gross drop of 853.5 m. It will have a final installed power of 300 MW with five generator units. The underground power plant is 70.3 m long, 12.6 m wide, and has a maximum height of 33.6 m. Turbines and generators located in the plant are connected to their corresponding transformer vaults by three busbar tunnels." [8]
Project Area (in hectares)59,000
Level of Investment (in USD)275,000,000
Type of PopulationRural
Potential Affected Population16,000 - 20,000
Company Names or State EnterprisesTanzania Electric Supply Company Ltd (TANESCO) from Tanzania - Main project promoter
Salini Impregilo from Italy - Construction works
International and Financial InstitutionsThe World Bank
Norwegian Agency for Development Cooperation (NORAD) (NORAD) from Norway
Swedish International Development Cooperation Agency (SIDA) (SIDA) from Sweden
German Development Bank KfW (KfW) from Germany
Environmental justice organisations and other supportersInternational Rivers, https://www.internationalrivers.org/

Friends of the Earth, http://www.foei.org/

Fivas, http://fivas.org/
The Conflict and the Mobilization
Intensity of Conflict (at highest level)LOW (some local organising)
When did the mobilization beginIn REACTION to the implementation (during construction or operation)
Groups MobilizingIndigenous groups or traditional communities
International ejos
Social movements
Local scientists/professionals
Forms of MobilizationCreation of alternative reports/knowledge
Development of alternative proposals
Lawsuits, court cases, judicial activism
Media based activism/alternative media
Objections to the EIA
Public campaigns
Arguments for the rights of mother nature
Appeals/recourse to economic valuation of the environment
Environmental ImpactsVisible: Biodiversity loss (wildlife, agro-diversity), Loss of landscape/aesthetic degradation, Deforestation and loss of vegetation cover, Surface water pollution / Decreasing water (physico-chemical, biological) quality, Large-scale disturbance of hydro and geological systems, Reduced ecological / hydrological connectivity
Potential: Desertification/Drought, Global warming, Groundwater pollution or depletion
Health ImpactsVisible: Infectious diseases
Potential: Mental problems including stress, depression and suicide, Violence related health impacts (homicides, rape, etc..) , Health problems related to alcoholism, prostitution, Occupational disease and accidents
Socio-economic ImpactsVisible: Displacement, Loss of livelihood, Loss of traditional knowledge/practices/cultures, Land dispossession, Loss of landscape/sense of place
Potential: Social problems (alcoholism, prostitution, etc..)
Project StatusIn operation
Pathways for conflict outcome / responseEnvironmental improvements, rehabilitation/restoration of area
Strengthening of participation
New Environmental Impact Assessment/Study
Development of AlternativesPrior to the implementation of the project, The World Bank investigated two dam alternatives and a natural gas project. Moreover, "alternatives exist that would sustain the Gorge Habitat and ensure that the LKHP remains economically viable. These alternative proposals would increase instream bypass flows to seven cubic meters per second in order to create sufficient spray from the waterfall. Nevertheless, the World Bank and other funders have opted not to oblige the Government of Tanzania to implement this option." [2]
Do you consider this as a success?No
Why? Explain briefly.If sustainable development is the one "that meets the needs of the present without compromising the ability of future generations to meet their own needs" (United Nations) this is not a successful case, due to the high biodiversity irreversible loss.
Sources and Materials

[3] Lovett, J. C. et al., 1997. Assessment of the impact of the lower Kihansni Hydropower Project on the forests of Kihansi Gorge, Tanzania. Biodiversity and conseration 6, 915-933

[4] Quinn, C.H. et al, 2005. Effect of the Lower Kihansi Hydropower Project and post-project mitigation measures on wetland vegetation in Kihansi Gorge, Tanzania. Biodivers Conserv 14: 297. doi:10.1007/s10531-004-5048-3


[8] Salini Impregilo website 2013. Lower Kihansi hydroelectric project. Accessed: 26/04/2017
[click to view]

[5] KfW, 2006. Tanzania: Lower Kihansi Hydropower Station. Ex-Post evaluation. Accessed: 26/04/2017
[click to view]

[6] BBC News, 2009. Species' extinction threat grows. Accessed: 26/04/2017
[click to view]

[1] Olse, E.F., 2001. World Bank Reports Discloses Serious Environmental Damage from Tanzanian Dam. International Rivers. Accessed: 26/04/2017
[click to view]

[2] International Rivers, 2001. Lower Kihansi Hydropower Project: An Evaluation of the Project Against World Commission on Dams Guidelines. Accessed: 26/04/2017
[click to view]

[7] Lower Kihansi Hydropower Project, Tanzania. Accessed: 26/04/2017
[click to view]

Other Documents

Lower Kihansi dam, Tanzania Credits: Salini Impregilo website, 2013
[click to view]

Kihansi Spray Toads Credits: http://frogsaregreen.org, 2013
[click to view]

Meta Information
ContributorAB - ICTA
Last update27/04/2017