The LHWP has a multitude of interlinking effects on the people of the area, and on their physical, biological and cultural environment. Starting in 1990, the LHWP is being developed through a series of phases. The project area is in the Great Karroo Basin, a large shallow depression. The Malibamstso River valley is roughly 90 kilometres long and 20 kilometres wide. The soil layer on the valley sides is shallow, with sparse short grass cover.
Bare rock is exposed on the mountain tops.
Response to rainfall is rapid and attenuation poor, resulting in highly peaked floods. Mean annual rainfall, which varies from 600 mm in the lower Sengu valley to over 1000 mm on the Maluti Mountains, occurs mainly between October and April and averages 900 mm in the catchment area of the Katse dam. Temperatures in the project area range from well below 0 o C in the winter to 25-30 o C in the summer. At the Katse dam site, the temperatures fall below zero at night for prolonged periods in winter. LHWP exploits this natural resource by arresting the southern flow, storing the water and redirecting it northwards to the Vaal river, to supply the northern, industrial areas of South Africa.