National Water Harvesting and Storage Authority

ISIOLO PROJECT BRIEF

THE LOCATION AND OBJECTIVE OF THE DAM

The proposed dam is located at Crocodile Jaws site approximately 18km from Oldonyiro shopping centre and on the border of Isiolo and Laikipia counties. The proposed dam is intended to regulate the flows of the Ewaso Nyiro River, supply water to Isiolo town, the proposed Isiolo resort city and rural areas of Isiolo, Laikipia and Samburu counties. The project will also generate 16MW of hydropower.

The project will serve a population of about 220,726 people in the initial year 2020, 343,560 people in the future year 2030 and 564,819 in the ultimate year 2040. The projected water demand is 7,894m³/day for the initial year 2020, 18,957m³/day in the future year 2030 and 60,000m³/day in the ultimate year 2040.

PROJECT PARTICULARS

The table below shows the project particulars of the proposed dam:

PROGRESS OF THE PROJECT

-Design of the project is complete

-Pre-qualification for finance and build contractors has been done

-Consultation of stakeholders on going

-The process to seek NEMAs approval and licence has begun

NYAHURURU DAM

Pesi (Nyahururu) Dam is located in Nyandarua County on Pesi River and about 1.5km upstream of the confluence of Pesi and Gathanji Rivers. It is located 37km to the south-west of Nyahururu Town. The name of the dam as originally proposed in the National Water Master Plan of 1992 and as indicated in Kenya Government vision 2030 development plan is Nyahururu Dam. The dam was proposed to supply water to Nyahururu Town and its environs.

The original Nyahururu Dam site was proposed about 4km to the west of Nyahururu Town and in Laikipa County. On assessment of the suitability of the site for development of a large dam to supply Nyahururu Town with water in year 2015.

The site was found not to be suitable due to environmental changes that have taken place since 1992. These changes include high level of water pollution due to human settlement in the dam catchment area that include establishment of housing estates like Kia Maina settlement and Coresite estates, cultivated catchment that require rehabilitation and permanent structures that would be affected that include a section of Nyahururu -Nakuru Road.

Besides environmental changes, the proposed original dam site would require water to be pumped to the water supply area: The top water level in the proposed dam is at contour 2400masl while the existing storage tank for supply of water to Nyahururu and its environs is at contour 2400masl which means that the dam could not supply water by gravity.

Pumping of water could raise maintenance and operations cost of the water system to unsustainable level like the existing water system that is currently serving Nyahururu Town. Therefore, an alternative dam site was explored and found on Pesi River hence the name Pesi (Nyahururu) Dam.

The primary objective of Pesi (Nyahururu) Dam Water Supply Project is to provide reliable and sustainable domestic water supply to Nyahururu Town and environs, Ol Kalou Town and environs and other needy areas that can be supplied with water by gravity from the dam.

 The secondary objective of Pesi (Nyahururu) Dam Water Supply Project is to provide water for irrigation, hydropower generation and scenery for tourism and sporting activities.

Proposed dam capacity

The proposed Pesi (Nyahururu) Dam will be 60m high and will impound a total of 16,000,000m³ of water.  Dam capacity required to meet the projected water demand is 11,300,000m³. The dam crest will be 380m long. The bottom water outlet after water treatment will be at contour 2460masl which will be high enough to command gravity flow to most of the supply target areas.

(ii)            Type of Dam and Construction Materials

The proposed dam will be an earth-fill dam. The soils at the dam site and in the vicinity of the dam are red soils that have high cohesion values with low permeability. The soils are non-dispersive. The soils are good for dam construction.

Other construction materials like ballast can be obtained by crushing hard-stone which is readily available within reasonable haulage distance from the dam site.

(iii)          Benefits to persons in the vicinity of the proposed dam

Besides getting employment during construction of the project, the water supply that is currently serving the people and which does not cover 25% of the target area will be expanded to serve all the people around the dam area.

Areas to be served with water

The proposed Pesi (Nyahururu) Dam will supply water to areas of Nyandarua and Laikipia Counties. The areas to be served in Laikipia County include Nyahururu, Marmanet and Wiyumiririe Towns and their environs. The areas of Nyandarua County that will be served with water include Ndaragwa, Gwa Kung'u, Mairo-Inya, Ol Joro Orok, Kasuku, Part of Rurii and Ol Kalou Towns and environs that include several sub-locations/locations.

Populations and water demands

The populations and total water demands are estimated as follows:

From the year 2005/2006, when NWCPC was given its new mandate of being the construction arm of the Ministry of Water and Irrigation, the Corporation has been constructing small dams/pans in mainly in the ASAL areas across the country.  This has helped in increasing the country’s water storage and also has provided water for both domestic and livestock use.

Since the year 2005/2006 to date, NWCPC has constructed/rehabilitated over 1,019 small dams/ pans across the country mainly in the Arid and Semi Arid Areas.  This has increased the countries water storage by approximately 18.5 Million cubic metres of water serving about 1 million people and over 2 million domestic animals.  These projects have had a major positive impact to livelihoods of communities in areas affected by perennial droughts

Among the small and medium dams constructed are:
Ilengeni Dam, Kalundu Dam, Matinga Dam, Ndumbuni Dam, Chamawa Pan, Muserech Pan.

The Authoritys target for construction/rehabilitation of medium sized dams/pans in Arid and Semi-Arid Lands in Kenya was 11No. Dams. The Corporation has already achieved a target of 8No. Dams. Construction/rehabilitation of 7No.