Lesotho and South Africa celebrated a significant milestone this week as construction officially commenced on the main water transfer works for Phase II of the Lesotho Highlands Water Project (LHWP). The works include Polihali Dam, Polihali Transfer Tunnel and the Senqu Bridge.
The sod-turning ceremony took place on 23 May in Malingoaneng Mokhotlong, attended by His Majesty King Letsie III and President Cyril Ramaphosa of South Africa.
According to Tente Tente, the Chief Executive of the Lesotho Highlands Development Authority, the advanced infrastructure, including roads, bridges, power facilities, and housing, is almost complete, paving the way for the main construction phase. The construction of the dam and tunnel is expected to take about five years, with water transfer operations scheduled to start in 2028. The Oxbow Hydropower Scheme, an integral part of Phase II, will begin generating power in 2029.
The Polihali Dam, similar to the Mohale Dam built during Phase I of the LHWP, will be a concrete-faced rockfill dam. It will create a reservoir across the valleys and tributaries of the Senqu, Khubelu, Mokhotlong, Moremoholo, and Sehong-hong rivers, covering an area of 5053 hectares. The dam will include a spillway, a compensation outlet structure, and a mini-hydropower station.
The Polihali Transfer Tunnel will transport water from the Polihali reservoir to the Katse reservoir using gravity. From Katse, the water will be delivered through a tunnel to the 'Muela Hydropower Station, constructed during Phase I, and then channeled to the Ash River outfall outside Clarence in the Free State, ultimately supplying water to Gauteng.
One of the notable features of Phase II is the Senqu Bridge, which is almost one kilometer long and stands 90m tall. This bridge, the first of its kind in Lesotho, surpasses the Mphorosane Bridge constructed during Phase I. It is the largest among the three bridges to be built under Phase II, spanning the Polihali reservoir.
The Polihali reservoir will add 2,325 million cubic meters of storage capacity to the LHWP, increasing the annual water supply rate from 780 million cubic meters to 1,270 million cubic meters. This expansion will help meet South Africa's growing water needs. Additionally, the increased water flow will enhance power generation within Lesotho, reducing the country's reliance on electricity imports. Phase II builds upon the success of Phase I, which was completed in 2003.