Hartbeespoort Dam has been renowned for its poor water quality since the mid twentieth century.


The Dam suffers severe eutrophication, in 2003 resulting from high concentrations of phosphates and nitrates in the Crocodile River, the major inflow.
The primary pollution sources are industrial and domestic effluent from Gauteng.
The catchment area includes Bruma lake in the Jukskei River and Centurion lake in the Hennops River.

The extreme level of eutrophication is evident in excessive growth of microscopic algae and cyanobacteria, and macrophytes such as water hyacinth (Eichhornia crassipes).
This is caused by the growing level of dysfunction in the many sewage works that drain the city of Johannesburg, which, unusually for a large city, straddles a continental watershed instead of being located on a lake, river or seafront.
Hartbeespoort Dam has become a robust example of the unintended consequence when an aquatic ecosystem flips from a stable but desirable state, into a stable but undesirable state, defying the best scientific interventions for decades.
This is driven to a certain extent by the decline of data capture and processing systems that underpin water resource management in South Africa.
  
The South African Department of Water Affairs and Forestry launched the Harties metsi a me (Harties, My Water) programme to find solutions to the water quality problems.
Budgeted government expenditure from 2004 to 2015 for the clean-up and rehabilitation of the dam and its catchment, and for related community projects, amounted to R900 million.

Some biomanipulation methods applied to dams such as Hartbeespoort have come under scientific scrutiny.
Hartbeespoort Dam has been renowned for its poor water quality since the mid twentieth century.

The Dam suffers severe eutrophication, in 2003 resulting from high concentrations of phosphates and nitrates in the Crocodile River, the major inflow. The primary pollution sources are industrial and domestic effluent from Gauteng. The catchment area includes Bruma lake in the Jukskei River and Centurion lake in the Hennops River. 
The extreme level of eutrophication is evident in excessive growth of microscopic algae and cyanobacteria, and macrophytes such as water hyacinth (Eichhornia crassipes). This is caused by the growing level of dysfunction in the many sewage works that drain the city of Johannesburg, which, unusually for a large city, straddles a continental watershed instead of being located on a lake, river or seafront. Hartbeespoort Dam has become a robust example of the unintended consequence when an aquatic ecosystem flips from a stable but desirable state, into a stable but undesirable state, defying the best scientific interventions for decades. This is driven to a certain extent by the decline of data capture and processing systems that underpin water resource management in South Africa.   
The South African Department of Water Affairs and Forestry launched the Harties metsi a me (Harties, My Water) programme to find solutions to the water quality problems. Budgeted government expenditure from 2004 to 2015 for the clean-up and rehabilitation of the dam and its catchment, and for related community projects, amounted to R900 million.
Some biomanipulation methods applied to dams such as Hartbeespoort have come under scientific scrutiny.
Hartbeespoort Dam