Lesotho: Is Construction At the Lesotho Highlands Water Project Polluting Rivers?

The concern comes from visible signs near Kopano Ke Matla’s construction site. During an August visit, wastewater appeared to flow continuously from an outlet near the Sekoai River. On 7 September, residents reported foamy water, and villager Thomello Ramotloenya said he saw white bubbles while grazing animals. The river is about ten metres from the perimeter fence.

The outlet is part of the contractor’s wastewater-treatment system, according to LHDA spokesperson Mpho Brown. He said it is approved and intended to release only treated effluent. However, the article records suspected pollution, not a confirmed breach. The observed foam, colour, or chemical quality had not yet been tested.

LHDA said it would refer the collected evidence to the project engineer for inspection and testing. Brown said no inspection or tests had yet occurred. If testing finds non-compliant effluent, the discharge should stop immediately while the cause is corrected.

The article presents the Lesotho Highlands Water Project as a large water-development project between Lesotho and South Africa. It involves construction sites, tunnels, reservoirs, contractors, engineers, and environmental controls. The project matters because the Katse reservoir, one of its water facilities, supplies drinking water to South Africa.

Kopano Ke Matla Joint Venture is building the Polihali transfer tunnel. The article refers to wastewater from a tunnel boring machine access adit at Polihali, showing that the tunnel work includes underground construction and supporting access infrastructure. Wastewater from those activities must be treated before release.

The tunnel’s precise engineering function is not explained in the supplied article, so its role can be stated only as a transfer-tunnel component of the wider project. The current dispute concerns whether wastewater from its construction is properly treated. The project engineer is expected to inspect and test suspected discharges.

This is a very large cross-border infrastructure project. The article gives its cost as M42-billion and describes it as being between Lesotho and South Africa. That scale explains why construction decisions can affect many workers, communities, waterways, and water users beyond the immediate site.

The contractor’s suspension in May 2025 sent 1,400 workers home. The suspension followed concerns that oily and acidic wastewater had been discharged into nearby rivers and the Katse reservoir. Work resumed after the project engineer inspected upgrades and independent laboratory results found treated effluent met required standards.

The project’s importance also comes from its water connection. The Katse reservoir supplies drinking water to South Africa. That makes wastewater control a cross-border issue, not only a local construction matter. New suspected pollution near the Sekoai River therefore faces scrutiny from communities, LHDA, engineers, and water authorities.

Kopano Ke Matla Joint Venture is the contractor building the Polihali transfer tunnel. Its construction activities produce wastewater that must pass through an approved treatment system before discharge. The contractor is therefore responsible for operating and upgrading that system and correcting any non-compliance.

The project engineer has a central technical role. LHDA said it would refer evidence of suspected pollution to the engineer for inspection and testing. Earlier, the engineer inspected upgrades before work resumed, while independent laboratory results confirmed that treated effluent met required standards. Supervising engineers had also identified earlier treatment failures.

The Lesotho Highlands Development Authority, or LHDA, oversees the project and communicates the environmental requirements. Brown said LHDA would take whatever further action the contract allows. If testing finds non-compliant effluent, discharge should stop immediately, and Kopano Ke Matla must correct the cause before releasing water again.

Kopano Ke Matla was suspended for 18 days after concerns about acidic and oily wastewater entering nearby rivers and the Katse reservoir. A suspension letter dated 5 May 2025 said the contractor had addressed only three of 26 identified non-compliant issues. Engineers cited missing effluent test results, a broken sulphuric acid dosing pump, high pH in treated water, and oil contamination.

They also reported possible untreated construction wastewater entering the Ntšupe River, untreated tunnel effluent reaching the Katse reservoir, and failures to maintain sewage and wastewater-treatment plants. These failures mattered because treatment systems were not reliably controlling the quality of discharged water.

Before work resumed on 25 May, the contractor added settling capacity, a pH-correction stage, revised its operating procedures, and appointed a qualified process specialist. The engineer approved the revised method statement. Independent laboratory results then confirmed the treated effluent met required standards.

Discharging acidic or oily wastewater without adequate treatment could reduce water quality in rivers and reservoirs. The concern is especially serious because the Katse reservoir supplies drinking water to South Africa. Nearby communities also depend on local waterways and reported seeing foam in the Sekoai River. The article does not confirm that the latest suspected discharge caused illness, ecological damage, or unsafe drinking water.

The earlier suspension shows the potential pathway. Engineers found evidence of oil contamination, high pH in treated water, and concerns about untreated wastewater reaching the Ntšupe River and Katse reservoir. Such findings indicate that treatment failures could allow harmful substances to leave the construction site and enter shared waterways.

The immediate response should be inspection and testing. LHDA said discharge would stop if effluent quality is non-compliant, and the contractor would have to correct the cause. Further action could follow under the contract. Until testing is completed, the latest pollution report remains unconfirmed.

Wastewater treatment uses several safeguards because construction water can contain suspended material and chemically altered water. Settling allows solids to separate before final discharge. The article says the upgraded plant received additional clarifier capacity for primary settlement. This helps reduce the material carried into a river or reservoir.

pH correction addresses water that is too acidic or too alkaline. The revised method statement added a pH-correction stage before final discharge, after engineers had raised concerns about high pH and a malfunctioning sulphuric acid dosing pump. Testing then checks whether the treated effluent meets required standards rather than relying only on appearance.

These steps reduce the chance that polluted water reaches aquatic ecosystems, communities, or drinking-water supplies. They do not prove every discharge is safe by themselves. The current case still requires inspection and laboratory testing. If results show non-compliance, LHDA says discharge should stop until the treatment problem is fixed.