Nairobi bets on new dam projects to end water supply crises

Nairobi residents have been subjected to water rationing and irregular water supply since 2017.

But this is set to change within the next five years under an elaborate plan being laid down by different agencies in the city.

Athi Water Works Development Agency managing director Michael Thuita says the plan involves bringing online three new dams — Kariminu II, Maragua IV and Ndarugo —which will allow the water agencies to pump in an additional 320,000 cubic metres of water daily to the city in the short-term.

The projects will supplement water that will be pumped to the city via the completed Northern Water Collector Tunnel, which will supply 140,000 cubic metres daily.

This will see a water supply deficit to the city, which currently stands at 350,000 cubic metres, plugged and a surplus left. With demand estimated to be increasing by 20,000 cubic metres every year, the deficit will be close to 450,000 cubic metres in the next five years.

Mr Thuita said the tunnel system and Kariminu Dam would partly solve recurrent water problems in Nairobi.

Pending Bill

He said the water tunnel would be operational in six months after the government clears a Sh3.5 billion debt that is holding final works on the project. The project, which commenced in 2015 and was expected to be ready by last April, had hit a snag over the outstanding bill.

“The matter (debt) has been escalated to the Cabinet, which has already met and we are just waiting for a response from the Treasury. The moment we clear the bill we will finish the remaining work within two weeks,” said Mr Thuita.

“Once we clear the Sh3.5 billion, we will start utilising the tunnel within a month and then be able to deliver water to Nairobi within six months.”

The water supply system entails the construction of an 11.8km underground tunnel that draws floodwater from the Maragua, Gikigie and Irati rivers.

The project has three main components — a tunnel that cost about Sh8.5 billion, a Sh4.5 billion water treatment plant and the pipelines costing about Sh7.5 billion. Land compensation cost Sh8 billion, raising the total to about Sh30 billion.

The outstanding bills are Sh1.7 billion for the tunnel itself, Sh724 million for the water treatment plant and Sh1 billion for the pipeline component.

The piping will be from Thika Dam to Gigiri reservoirs in Nairobi before the water is distributed across the capital city and its environs.

In 2016, the construction of the Sh4.7 billion Kigoro Water Treatment plant in Gatanga, Murang’a County began to complement the Ng’ethu treatment plant in handling the extra water flowing to Ndakaini Dam from the Northern Water Collector tunnel. It was to be completed in May 2018, but it also experienced some delays.

“The piping has been done. The water treatment plant was completed about two years ago, but the contractor declined to hand it over until the Sh724 million debt is paid. We also have to clear the balance for the tunnel for the contractor to pay the suppliers for the remaining bit of work,” said Mr Thuita.

Surplus Supply

The Sh24 billion Kariminu II Dam in Gatundu North is penciled for completion next year and will produce 70,000 cubic metres of clean water per day, with Nairobi residents getting 20 percent of the water while the remaining 80 per cent supplied to Kiambu constituencies of Thika, Ruiru and Juja.

Built on a 600-acre piece of land, the dam upon completion will have a height of 59 metres with 26.5 million cubic metres storage capacity.

Mr Thuita exuded confidence that it will be done without the sort of hiccups that have delayed the tunnel project.

Nairobi residents currently depend on water from Ndakaini Dam through the Ng’ethu Water treatment plant that supplies 480 million litres of water daily and Sasumua Dam’s 59 million litres. Ruiru 1 Dam and Kikuyu Springs together contribute 26.8 million litres of water to the city every day. The failure by the water agencies to meet demand is also due to limitations in the water treatment system, which can only process 526,000 cubic metres daily against a demand of close to 900,000 cubic metres.

The dire situation has seen the proliferation of vendors who make a kill from city residents by charging as high as Sh50 for a 20-litre water jerrican. They have also been accused of sabotaging the supply system to create artificial shortages to boost their sales.

Mr Thuita says the two new treatment systems will process an additional 160,000 cubic metres of water cutting the deficit to 200,000 cubic metres. This is where Maragua IV and Ndarugo Dams projects will come in handy to bridge the gap. The two projects are in the planning stage and awaiting Cabinet approval for the procurement process to commence.

He said the two dams, upon completion, would each supply 150,000 cubic metres daily to the capital city, bringing in a total of 300,000 cubic metres of water.

Plugging Deficit

“If we are cleared this year, in the next five years we shall be able to bridge the entire water deficit in the city. We shall be able to use the existing pipeline to immediately inject additional water to the city,” he said.

If successful, the capacity addition plan will solve a problem that has been decades in the making.

Nairobi has benefited from piped water for the past 115 years, starting with the development of the Kikuyu Springs source and Kabete treatment works in 1906 with a capacity to supply 4,800 cubic metres daily.

This was followed by the development of the Ruiru Dam in 1936 and the Sasumua Dam on the Chania River in 1945, which was expanded in 1956.

In the 1970s, these sources were no longer sufficient to supply the growing city during the dry season and financing for a new and larger dam, Ndakaini, was proposed to alleviate growing water shortages.

The first Nairobi Water Supply Project was between 1972 and 1976 and the second Nairobi Water Supply Project (1978-1984) developed the Chania-Kimakia-Thika river system to meet the water supply needs of the city until 1988.

When the construction of Thika Dam, now Ndakaini, was mooted by the government in 1988, the end game was to have a reservoir to supply continuous reliable water to the residents of Nairobi City and its environs with minimum interruptions.

However, Nairobi’s population had been steadily rising throughout all these planning periods — from 4,000 in 1900 to 859,000 in 1979, 1.1 million in 1984 and two million by 1995. The number of city residents hit 3.9 million in 2010 and is today close to five million.

The Ndakaini project — sitting on approximately 1,200 acres of land — was designed to serve Nairobi well into 2010 thereafter additional investment would be needed to augment supplies, treatment and pumping capacity.

As designed, the construction of the Dam should have increased the water supply capacity to 646,200 cubic metres daily, which would have met the water demand up to 2008. The water capacity would then need to be augmented to meet the demand from 2010 and beyond, by transferring water from the northern rivers to Thika Dam via a system of collector tunnels.

This was the birth of the Northern Water Collector Tunnel.