The Tosca-Molopo case presents a unique example of an effective groundwater management intervention in South Africa, where groundwater governance has otherwise been described as weak to non-existent. Prior to 1998, groundwater was a private resource used and exploited by landowners. The National Water Act of 1998 defined groundwater as a national resource, which provided the basis for management intervention by the government. The circumstances precipitating the particular interventions in Tosca-Molopo over the period 1993 to 2011, their nature, and the consequences are described, and general lessons are sought. Rapid and uncontrolled expansion of irrigation use lead to over-abstraction of a dolomite and sedimentary aquifer system. Groundwater levels declined, shallow boreholes dried up, livestock and domestic water supply systems failed, leaving land without water. The existing water use entitlements were verified and validated, unauthorised use was stopped, a further reduction above a threshold of maximum irrigation area per farmer was implemented, and subsequently an even stricter compulsory licensing was initiated, though providing for fair and equitable entitlements. A local water user association was established for water use and groundwater level monitoring as well as general support of the process. Through these management measures, the water levels stabilised over a number of years to prevent further failure of the water supply systems. The case illustrates that a combination of conducive factors within a properly framed legal system, including political will, mutual perception of the problems among stakeholders, sufficient technical capacity for implementing, monitoring and enforcing tightened regulations, and a functioning collaboration between the national and local level, can lead to reversing trends in groundwater over-abstraction.