THE PHYSICAL AND CHEMICAL LIMNOLOGY OF STERKFONTEIN DAM, EASTERN ORANGE-FREE-STATE, SOUTH-AFRICA

The great depth and high altitude of Sterkfontein Dam relative to other large reservoirs in Southern Africa make this an unusual water body. It is also characterised by an almost entirely artificial inflow. As Sterkfontein Dam is the main storage reservoir in the Tugela-Vaal interbasin transfer scheme, the water quality needs to be monitored. This is the first limnological study of this reservoir, where the physical and chemical quality of the water body was examined. The reservoir was stratified during summer, although not very strong. The stratification was easily destroyed by wind. Mixing was such that aerobic conditions prevailed in the profundal zone. Nutrient concentrations were low, suggesting that this system is oligotrophic. The relatively low mean temperatures, low turbidity and distribution of well-oxygenated water to large depths make this a good potential habitat for fish, especially trout.