The Construction of the Polihali Dam, an integral part of Lesotho Highlands Water Project Phase 2 is set to commence soon and its impoundment should start at the second half of 2023.
The water project which include the Polihali-Katse transfer tunnel, is a combined effort of both the governments of South Africa and Lesotho. Phase 2 of the LHWP is as a result of the successful completion of Phase 1 in 2003.Its estimated cost is a total of US $1.3bn.
The Dam will be built downstream of River Seqhu and River Khubelu. It will have a 163.5-m-high concrete-faced rock-fill embankment dam wall with a concrete side channel spillway. Water supply will only begin once the reservoir has filled completely.
The Projected date of completion has been set to 2024 upon which expected water supplied to South Africa would be an estimate of 780 million cubic meters yearly over the subsequent 20 years.
The crest length will be 915 m, with a free standing compensation outlet tower. Polihali-Katse Transfer Tunnel. This tunnel will be 38.2km long with an average diameter of 5m. The first Phase of this project consisted of the Katse and Mohale dams, the Muela hydropower station which was completed in 2003 and inaugurated in 2004.
Katse dam is situated about 2,000m above sea level and is one of the world’s 10 largest concrete arch dams in terms of volume . It is also the highest dam wall in Africa. The Muela hydropower project is fed by Katse reservoir via a 45km long concrete lined transfer tunnel which has a diameter of about 4.35m. The major benefit of this project is that it generates close to 85% of Lesotho’s electricity.