Hartbeespoort and surrounding communities remain at risk after an aerial survey revealed extensive pollution in the Kaalspruit, Jukskei, Hennops and Crocodile river systems that feed the dam, Deputy Water and Sanitation Minister Jack Bloom reported to the Mail & Guardian.
Key problems identified from the air
The survey, carried out by the deputy minister, documented visible signs of contamination and human impact along interconnected waterways. Observations included unnatural foaming, long stretches of murky water, widespread illegal dumping and large stands of invasive aquatic plants such as water hyacinth and salvinia that are suffocating sections of the waterways and the dam.
- Infrastructure failures: Bloom reported malfunctioning wastewater treatment works and overflowing pump stations as significant contributors to pollution.
- Point and non-point pollution: Sewage, industrial effluent and agricultural fertiliser runoff were all identified as nutrient sources encouraging invasive plant growth.
- Acute hotspots: The deputy minister pointed to locations such as the Zandspruit pump station in northern Johannesburg as specific problem areas requiring urgent attention.
How pollution reaches Hartbeespoort
Bloom described the problem as extending well beyond the dam itself: rivers carry contaminants downstream into Hartbeespoort, where excess nitrogen and phosphorus from sewage and fertilisers fuel the spread of aquatic weeds. These plants reduce oxygen levels in the water, posing a threat to fish and the broader aquatic ecosystem.
“My aerial oversight showed the importance of identifying hotspots where localised action can eat this giant elephant of a problem one bite at a time,” Bloom said, according to the Mail & Guardian.
The deputy minister cited an estimated 90-million-litre daily flow of untreated sewage into the dam from three malfunctioning Johannesburg wastewater treatment works. While the Limpopo-Olifants Catchment Management Agency said that treatment works discharge treated effluent, Bloom warned that untreated sewage can still enter rivers through manhole overflows and failing sewer networks.
Context: the state of wastewater systems
The survey findings echo concerns raised in the 2025 Green Drop report, which the deputy minister referenced. That report found that 23 of Gauteng’s 61 wastewater systems were in a critical state, signalling broader systemic problems that have implications for downstream users such as Hartbeespoort.
| River | Primary issues observed |
|---|---|
| Kaalspruit | Murky stretches, illegal dumping |
| Jukskei | Construction rubble near banks, potential collapse risk |
| Hennops | Sewage contamination, invasive plants |
| Crocodile | Nutrient runoff, widespread vegetation |
Local consequences and next steps
For Hartbeespoort residents the findings have several immediate and medium-term implications. Increased weed growth can hamper water recreation, affect property values, and complicate bulk-water management and treatment costs. Lower dissolved-oxygen levels threaten fish stocks that local people rely on for livelihoods and leisure.
Bloom urged a science-led response: measuring flows and nutrient concentrations to pinpoint interventions that will be most effective. He recommended targeted, localised action at identified hotspots rather than broad measures that may dilute resources.
The survey also highlighted acute infrastructure risks in urban areas upstream. A mass of construction rubble beside the Jukskei River in Alexandra was singled out as being at risk of collapsing into the waterway, a development Bloom warned could block flow and cause urban flooding.
Local and national agencies face a co-ordinated challenge: repairing and maintaining wastewater treatment works and pump stations, addressing sewer network overflows, enforcing regulations around illegal dumping, and reducing agricultural runoff. The Limpopo-Olifants Catchment Management Agency acknowledged that treated effluent is discharged by works but that untreated sewage can still enter rivers via manhole overflows.
Residents and municipal leaders in the Hartbeespoort catchment will be watching how quickly action is taken at the hotspots identified from the air. The deputy minister’s aerial oversight lays out specific sites for remediation, but turning those observations into funded, operational interventions will determine whether the ecological condition of the dam and its feeder rivers improves.
