Efforts to restore the Milnerton Lagoon are ramping up, with dredging in the works and infrastructure upgrades well under way. These targeted operational improvements are aimed at improving water quality and system performance across the lagoon and the wider Diep River catchment.
At a public meeting on 25 March, the City of Cape Town updated residents on progress made so far and outlined the way forward with the integrated solutions being implemented to reduce pollution and improve environmental conditions.
Backed by extensive sewer and pump station upgrades, as well as improvements at the Potsdam Wastewater Treatment Works (WWTW), the programme is beginning to show measurable results. System performance is being strengthened by proactive maintenance while continuous environmental testing and monitoring is ongoing.
‘We are beginning to see the results of our investments. Fewer blockages and reduced odours are just some of the benefits. These interventions are building a more resilient system for the long term,’ said Councillor Zahid Badroodien, Mayoral Committee Member for Water and Sanitation.
Key interventions under way
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Lagoon dredging and flow improvements: A tender is being evaluated, with works expected to start in June 2026. This includes creating a defined channel, reshaping sandbanks, constructing a berm, and managing the lagoon mouth to improve flushing and reduce stagnation.
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Sewer network upgrades and maintenance: Preventative cleaning and rehabilitation projects are reducing blockages and extending the life of ageing pipes across Montague Gardens, Milnerton, and Century City.
- Pump station telemetry: Telemetry now monitors all 56 lower Diep River pump stations in real time.
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Pump station (PS) upgrades:
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Saline water trial: From September 2026 a pilot project will introduce 80 – 100 litres per second of saline water from Milnerton Beach well points to improve flows, dilute pollutants and reduce odours.
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Potsdam Wastewater Treatment Works upgrade:
o Key sections like ultrafiltration and dewatering are operational or in trial phases.
o Membrane Bioreactor (MBR) commissioning expected to start in November 2026.
o It will improve nutrient removal, effluent quality, and environmental performance.
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Air quality improvements: Monitoring of hydrogen sulphide (H₂S) levels shows a significant decrease in the WHO 30-minute guideline value for nuisance for H2S of 5 ppb (7µg/m³). From 26 February 2025 until 31 December 2025 a total of 1397 nuisance exceedances were recorded. During 1 January 2026 until 26 March 2026 only 10 exceedances were recorded. The WHO daily guideline value for Health Guidance of 150 µg/m³ was not exceeded in the monitoring period. A permanent monitoring station is planned, along with active research on the deployment of low-cost sensors to supplement the fix ambient air quality monitoring network.
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Scientific interventions: Pilot studies using nanobubble technology and liquid microbial products show promise in reducing odours, harmful bacteria, and sludge accumulation. Further work is under way to determine optimal implementation methods, particularly in uncontrolled flowing environments such as the lagoon and river systems.
‘These measures are already making a difference. As major interventions move into implementation, we are entering a critical phase that will further improve the health of the Milnerton Lagoon and the surrounding catchment,’ said Councillor Badroodien.
