Milnerton Lagoon / Woodbridge Island Pollution Status Report March 2025
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| Milnerton Lagoon / Woodbridge Island Pollution Status Report 2025 |
Index:
- Executive Summary
- Introduction
- Current Pollution Status in 2025
- Sources and Causes of Pollution
- Environmental and Community Impact
- Ongoing Remediation Efforts and Infrastructure Upgrades
- Public and Political Response
- Conclusion and Outlook
- Recommendations
- Works cited / References
- Report Compiler
- Disclaimer
1. Executive Summary:
"The water quality of Milnerton Lagoon and the surrounding Woodbridge Island area remains critically compromised in 2025. The primary driver of this persistent pollution is the ongoing challenge of managing sewage effluent, largely attributed to the operational limitations of the Potsdam Wastewater Treatment Works (WWTW) 1. Despite the City of Cape Town's undertaking of a substantial R5.2 billion upgrade to the Potsdam WWTW, with full completion anticipated by the end of 2027, interim improvements in treated effluent quality are expected around mid-2025 due to the fast-tracking of certain infrastructure components 1. Public concern remains high, fueled by persistent foul odours emanating from the lagoon and anxieties regarding associated health risks 1. Alarmingly, continued high levels of E. coli and Enterococci contamination within the lagoon and adjacent coastal areas pose a significant threat to both human and environmental health 1. The ecological integrity of this important estuarine system is under severe pressure, necessitating continued and intensified efforts to address the root causes of this pollution.
2. Introduction:
Milnerton Lagoon, an estuary formed by the Diep River, is a vital ecological feature within the City of Cape Town, situated near Woodbridge Island. This lagoon serves as a crucial nursery area for various fish species on the west coast, including the Cape stumpnose and white steenbras, highlighting its ecological significance 2. This report aims to provide a comprehensive analysis of the pollution status of Milnerton Lagoon and Woodbridge Island as of 2025, drawing upon available research to outline the current situation, its underlying causes, the resulting environmental and community impacts, and ongoing remediation initiatives. The lagoon has faced persistent pollution challenges for an extended period, with the Western Cape environmental inspectorate issuing a directive to the City of Cape Town over four years prior to this report to address the issue 2. This protracted history underscores the complexity and intractability of the pollution problems affecting this area.
3. Current Pollution Status in 2025:
3.1. Persistent Sewage Contamination:
The primary characteristic of the pollution affecting Milnerton Lagoon in 2025 is the continuous presence of sewage contamination 1. Reports from early 2025 indicate ongoing issues with sewage treatment as the principal source of this contamination 1. Disturbingly, residents have reported and even documented instances of what appears to be raw, untreated sewage flowing directly into the lagoon 10. This suggests that despite efforts to manage wastewater, significant breaches in the system continue to occur, leading to the direct discharge of sewage into this sensitive aquatic environment.
3.2. High Levels of Bacterial Contamination:
A major consequence of the sewage pollution is the sustained presence of elevated levels of bacterial contamination. Concerns regarding E. coli and Enterococci contamination within the lagoon and the adjacent coastal areas persist throughout 2025 1. Water quality data from November 2024, which likely reflects the situation in early 2025, revealed alarmingly high E. coli counts downstream of the Potsdam WWTW, reaching 7.3 million cfu/100ml. This figure is drastically higher than the 29,100 cfu/100ml recorded upstream of the treatment works and far exceeds the acceptable limit for intermediate contact, which is around 2,420 cfu/100ml 2. This stark difference in bacterial levels strongly indicates the Potsdam WWTW as a significant source of faecal contamination in the lagoon.
3.3. Foul Odours and Aesthetic Degradation:
Residents in the vicinity of Milnerton Lagoon and Woodbridge Island consistently report the presence of persistent and often nauseating odours of sewage emanating from the lagoon 1. This stench has been described as particularly severe in recent weeks leading up to and into 2025 2. Beyond the unpleasant smell, there have also been visual indicators of the pollution's impact, such as reports of dead fish found in the lagoon 1. These sensory experiences underscore the significant degradation of the environment and the negative impact on the quality of life for those living nearby.
3.4. Impact on Recreational Activities:
The severely compromised water quality has directly affected recreational activities associated with Milnerton Lagoon. The Milnerton Canoe Club, for instance, has halted all paddling activities on the lagoon due to its deteriorated state 2. Furthermore, signage has been erected at the mouth of the lagoon warning against swimming or any contact with the water due to the high levels of pollution 6. This curtailment of recreational use signifies a tangible loss of amenity for the community and highlights the extent to which the pollution has rendered the lagoon unsafe and unusable for leisure purposes.
4. Sources and Causes of Pollution:
4.1. Potsdam Wastewater Treatment Works (WWTW):
A primary source of the ongoing pollution in Milnerton Lagoon is the Potsdam Wastewater Treatment Works (WWTW), situated approximately 5 kilometers upstream on the Diep River 1. This facility releases over 40 million litres of treated effluent into the Diep River daily, which subsequently flows into the lagoon 6. Despite being a critical piece of infrastructure, the Potsdam WWTW has faced persistent challenges in meeting the required effluent quality guidelines 1. Data from the Department of Water and Sanitation's regulatory information system indicates that the Potsdam WWTW met the minimum effluent quality guideline for only 3% of its monthly tests over the past year leading into 2025 6. Additionally, the plant achieved chemical compliance (measuring elements like nitrogen, phosphates, and ammonia) in only 48% of effluent quality tests and physical compliance (measuring aspects such as suspended solids, pH, and electrical conductivity) in just 31% 6. The Department of Water and Sanitation currently lists Potsdam's effluent quality as 'bad', providing clear evidence of the plant's significant contribution to the pollution problem 6.
4.2. Infrastructure Failures:
Beyond the operational challenges at the Potsdam WWTW, failures within the broader sewage infrastructure network also contribute significantly to the pollution of Milnerton Lagoon. There have been multiple reported instances of sewer line collapses that have resulted in raw sewage flowing into the lagoon via stormwater channels 1. Specifically, in 2024, sewer line collapses occurred in July, August, and September, all leading to sewage contamination of the lagoon 2. Furthermore, rehabilitation work undertaken in October 2024 inadvertently caused sewage overflows into stormwater channels that drain into the lagoon 2. These repeated infrastructure failures highlight potential systemic weaknesses in the sewage collection and conveyance system, necessitating not only upgrades to the treatment plant but also a focus on the integrity and maintenance of the entire network.
4.3. Urbanization and Informal Settlements:
Rapid urbanization and the proliferation of informal settlements in the Cape Town area, particularly in areas like Dunoon situated along the Diep River, exert considerable pressure on the city's wastewater management infrastructure and contribute to the pollution of Milnerton Lagoon 5. The City of Cape Town itself acknowledged in a 2023 report that informal structures are projected to constitute 55% of all new dwellings within the next two decades 7. The expansion of informal settlements, with over 60,000 new structures between 2016 and 2020 alone, often outpaces the provision of adequate sanitation and waste disposal services 7. Consequently, inadequate sanitation practices in these areas lead to the direct contamination of the Diep River, which ultimately flows into Milnerton Lagoon 12. Research indicates that the water quality in the Diep River is poor, with the Dunoon informal settlement identified as a contributing factor due to insufficient sanitation and waste management 12. The Vryheidsfront Plus has criticized the City of Cape Town for its perceived failure to effectively manage rapid urbanization and its subsequent impact on essential infrastructure and environmental health 7.
4.4. Other Potential Sources:
While sewage remains the primary concern, other sources may also contribute to the overall pollution load in Milnerton Lagoon. Environmental activist Zoe Prinsloo mentioned that beach litter, litter originating upstream, and pollutants washed up by the sea add to the existing problems in the lagoon 13. Although these sources may be less significant than the continuous discharge of poorly treated sewage, they nonetheless contribute to the degradation of the lagoon's ecosystem and aesthetic quality.
5. Environmental and Community Impact:
5.1. Ecological Consequences:
The persistent pollution in Milnerton Lagoon has significant detrimental effects on its ecological health. As an estuary, the lagoon serves as a vital nursery area for various fish species 2. The documented instances of dead fish in the lagoon are a direct and visible consequence of the poor water quality 1. Furthermore, the excessive organic matter from sewage pollution leads to a drop in dissolved oxygen levels in the Diep River, creating anoxic conditions in some locations 14. This lack of oxygen severely impacts aquatic life, potentially leading to fish kills and disrupting the natural balance of the ecosystem. The high rainfall in September 2024 temporarily improved tidal interchange and increased oxygen levels in the lower reaches of the system, but concerns remain that the lagoon mouth will revert to a less functional state during the summer months, reducing this natural flushing and oxygenation 14.
5.2. Health Risks for Residents:
The polluted state of Milnerton Lagoon poses considerable health risks to the residents living in the surrounding areas. Concerns have been raised about the foul odours, which are suspected to contain highly toxic hydrogen sulphide 10. Exposure to such gases can lead to various health issues. Moreover, the high levels of E. coli and Enterococci bacteria in the water increase the risk of infections for anyone coming into contact with the lagoon 1. Recent cases of severe hospitalization following infections by swimmers in other polluted areas of Cape Town highlight the potential severity of these health risks 7. The presence of these pathogens indicates fecal contamination, which can carry a range of waterborne diseases.
5.3. Impact on Property Values and Tourism:
While not explicitly detailed in the provided snippets, the persistent and severe pollution of Milnerton Lagoon and the associated foul odours are likely to negatively impact property values in the adjacent Woodbridge Island and Milnerton areas. The desirability of residential properties in close proximity to a heavily polluted and malodorous water body would undoubtedly be diminished. Similarly, the degraded state of the lagoon and the warnings against contact with the water would likely deter tourists and negatively affect local businesses that rely on the area's natural amenities. The ecological disaster unfolding in the lagoon detracts from the area's appeal as a place to live, work, and visit.
6. Ongoing Remediation Efforts and Infrastructure Upgrades:
6.1. Potsdam WWTW Upgrade Project:
The City of Cape Town has initiated a substantial R5.2 billion upgrade project for the Potsdam Wastewater Treatment Works (WWTW) in an effort to address the root causes of the pollution 1. This ambitious undertaking, which commenced in April 2023 and is projected to be completed by the end of 2027, aims to more than double the plant's treatment capacity from 47 million litres to 100 million litres per day 1. The upgrades will incorporate cutting-edge membrane technology to ensure higher standards of wastewater treatment and treated effluent 3. Recognizing the urgency of the situation, the City is fast-tracking the installation of certain infrastructure components, particularly the dewatering and ultrafiltration installations, which are expected to be operational by approximately mid-2025 1. These early improvements are anticipated to lead to a noticeable enhancement in the quality of treated effluent discharged from the WWTW 1. The Deputy Minister of Water and Sanitation has expressed approval for this upgrade project, acknowledging its potential to improve the situation 5.
6.2. Other Remedial Actions:
In addition to the major upgrade of the Potsdam WWTW, the City of Cape Town has implemented other measures to mitigate the pollution in Milnerton Lagoon and the Diep River. A six-month aeration trial commenced to increase dissolved oxygen levels in the river, which are depleted due to the high organic matter content from pollution 14. This trial aims to combat the anoxic conditions that harm aquatic life. Regular maintenance activities, such as manual screen cleaning and pump checks, are being conducted at the Koeberg Pump Station to ensure efficient operation and prevent debris from entering the lagoon 1. Furthermore, the City is considering the installation of temporary package plants as a potential short-term intervention to alleviate pressure on existing sewerage infrastructure, including the Potsdam plant 11. These various efforts demonstrate a multi-faceted approach to addressing the complex pollution challenges facing the lagoon.
7. Public and Political Response:
7.1. Community Concerns and Advocacy:
The persistent pollution of Milnerton Lagoon has elicited strong reactions and significant concern from the local community. Residents have consistently voiced their anxieties regarding the foul odours, the potential health risks associated with the contaminated water, and the overall degradation of their environment 1. Environmental advocacy groups, such as ReThinkTheStink, have played an active role in monitoring the water quality through independent testing and raising public awareness about the severity of the situation 1. These groups advocate for more transparency and decisive action from the authorities to address the pollution effectively. The community's engagement underscores their deep concern for the health of the lagoon and their desire for a clean and safe environment.
7.2. Political Involvement:
The pollution of Milnerton Lagoon has also attracted attention from political parties and government officials. The Vryheidsfront Plus (VF+) has conducted oversight visits to the area and issued statements criticizing the City of Cape Town's management of the pollution, linking it to broader issues of overpopulation and inadequate spatial planning 7. The party argues that the state of the lagoon exemplifies systemic failures in urban planning and infrastructure management. Conversely, the Deputy Minister of Water and Sanitation has expressed support for the City's R5.2 billion upgrade of the Potsdam WWTW, recognizing it as a necessary step towards addressing the pollution 5. However, the Deputy Minister also highlighted the significant impact of the rapid growth of informal settlements, such as Dunoon, on the water body, indicating a broader understanding of the multifaceted nature of the problem 5. The involvement of various political actors demonstrates the significance of this issue at a governance level and the differing perspectives on its causes and potential solutions.
8. Conclusion and Outlook:
In conclusion, the pollution status of Milnerton Lagoon and Woodbridge Island in 2025 remains a critical concern. Persistent sewage contamination, primarily stemming from the operational challenges of the Potsdam WWTW and recurring infrastructure failures, continues to plague the lagoon. This results in alarmingly high levels of bacterial contamination, foul odours, and a significant degradation of the aesthetic and recreational value of the area. The ecological consequences are evident in reports of dead fish and reduced biodiversity, while residents face potential health risks from exposure to polluted water and toxic gases.
The City of Cape Town's ongoing R5.2 billion upgrade of the Potsdam WWTW represents a significant long-term effort to address the root causes of the pollution, with anticipated partial improvements expected by mid-2025. However, the full benefits of this project will not be realized until its completion in 2027. In the interim, the community and environmental advocacy groups continue to express their concerns and push for more immediate and effective interventions. The situation necessitates sustained commitment and potentially accelerated action to mitigate the ongoing environmental and health risks associated with the pollution in Milnerton Lagoon.
9. Recommendations:
Based on the analysis of the current pollution status and ongoing efforts, the following recommendations are put forth:
9.1. Enhanced Monitoring and Transparency:
The City of Cape Town should implement more frequent and comprehensive water quality monitoring programs for Milnerton Lagoon and the Diep River. This data, including detailed reports on the effluent quality discharged from the Potsdam WWTW, should be made readily accessible to the public to foster transparency and build trust. Furthermore, the planned establishment of a real-time hydrogen sulphide monitoring site at Woodbridge Island should be expedited to provide crucial information on air quality and potential health risks 10.
9.2. Expediting Infrastructure Upgrades and Maintenance:
While the Potsdam WWTW upgrade is underway, the City should explore all possible avenues to ensure the project remains on schedule and consider whether the timelines for key components can be accelerated further. Simultaneously, a comprehensive assessment of the existing sewage infrastructure network is crucial to identify and address vulnerabilities that lead to sewer line collapses and overflows. A proactive maintenance and upgrade program should be implemented to prevent future incidents of raw sewage discharge into the lagoon.
9.3. Addressing Urbanization and Informal Settlements:
Recognizing the significant impact of rapid urbanization and informal settlements on wastewater management, the City of Cape Town needs to prioritize the development and implementation of sustainable urban planning strategies. These strategies must account for population growth and ensure the provision of adequate sanitation infrastructure and waste management services in both formal and informal settlements. Innovative solutions for improving sanitation and waste disposal practices in informal settlements along the Diep River should be explored and implemented to reduce the direct contamination of the waterway.
9.4. Community Engagement and Collaboration:
The City should foster stronger and more consistent communication with residents, environmental advocacy groups, and political stakeholders regarding the pollution status and the progress of remediation efforts. Collaborative initiatives between the City and community-based organizations, such as those involved in water quality monitoring, should be supported and encouraged to harness local knowledge and expertise in addressing the pollution issues.
9.5. Further Investigation of Pollution Sources:
While the Potsdam WWTW and infrastructure failures are primary concerns, a comprehensive investigation into other potential sources of pollution, such as industrial discharges or agricultural runoff in the Diep River catchment area, should be conducted. Understanding the full spectrum of pollution sources is essential for developing truly effective and holistic remediation strategies for Milnerton Lagoon.
Table 1: Summary of Water Quality Parameters at Milnerton Lagoon (November 2024)
| Parameter | Location | Value | Acceptable Limit (Intermediate Contact) | Source |
|---|---|---|---|---|
| E. coli | Upstream of Potsdam WWTW | 29,100 cfu/100ml | 2,420 cfu/100ml | 2 |
| E. coli | Downstream of Potsdam WWTW | 7,300,000 cfu/100ml | 2,420 cfu/100ml | 2 |
Note: This table reflects the latest available data prior to 2025 as per the provided snippets and serves as an indicator of the likely conditions in early 2025.
Table 2: Potsdam Wastewater Treatment Works Effluent Quality Compliance (Most Recent Year Prior to 2025)
| Parameter | Compliance Rate | Source |
|---|---|---|
| Minimum Effluent Quality Guideline | 3% (Monthly Tests) | 6 |
| Chemical Compliance | 48% (Effluent Quality Tests) | 6 |
| Physical Compliance | 31% (Effluent Quality Tests) | 6 |
| Overall Effluent Quality Status | 'Bad' | 6 |
Note: This table summarizes the effluent quality compliance of the Potsdam WWTW in the year leading up to 2025, based on the provided data.
10. Works Cited / References
1. Water Quality Updates Milnerton Lagoon, Woodbridge Island, accessed March 18, 2025, https://www.vernonchalmers.photography/2024/04/sewage-problems-at-milnerton-lagoon.html
2. Sewage stench lingers at Milnerton Lagoon - Cape {town} Etc, accessed March 18, 2025, https://www.capetownetc.com/news/sewage-stench-lingers-at-milnerton-lagoon/
3. R5,2-billion upgrade to the Potsdam wastewater plant to benefit 75 000 households and support property development - Cape Business News, accessed March 18, 2025, https://www.cbn.co.za/featured/r52-billion-upgrade-to-the-potsdam-wastewater-plant-to-benefit-75-000-households-and-support-property-development/
4. Look: R5.2bn Potsdam Wastewater Treatment Works upgrade on track - Cape Town ETC, accessed March 18, 2025, https://www.capetownetc.com/news/potsdam-upgrade/
5. Deputy minister wades into Milnerton Lagoon stink - Table Talk, accessed March 18, 2025, https://tabletalk.co.za/news/2025-02-03-deputy-minister-wades-into-milnerton-lagoon-stink/
6. Sewage stench lingers at Milnerton Lagoon - The Mail & Guardian, accessed March 18, 2025, https://mg.co.za/the-green-guardian/2024-12-16-sewage-stench-lingers-at-milnerton-lagoon/
7. Milnerton Lagoon suffering from unmanageable migration levels: VF+, accessed March 18, 2025, https://www.capeindependent.com/article/milnerton-lagoon-suffering-from-unmanageable-migration-levels-vf
8. Milnerton Lagoon: Overpopulation and poor spatial planning threaten Cape Town's future | Freedom Front Plus, accessed March 18, 2025, https://www.vfplus.org.za/media-releases/milnerton-lagoon-overpopulation-and-poor-spatial-planning-threaten-cape-towns-future/
9. 2025 - Vernon Chalmers Photography, accessed March 18, 2025, https://www.vernonchalmers.photography/2025/
10. Residents raise alarm on health risks of Milnerton environment - IOL, accessed March 18, 2025, https://www.iol.co.za/capeargus/news/residents-raise-alarm-on-health-risks-of-milnerton-environment-4fc1f9a2-089d-4e91-ba9f-a9632c0525a0
11. Draft estuary plan, a step in the right direction for Milnerton Lagoon pollution - Western Cape, accessed March 18, 2025, https://wc.da.org.za/2022/09/draft-estuary-plan-a-step-in-the-right-direction-for-milnerton-lagoon-pollution?fbclid=IwAR2mMtveXTR-uUcWv1K1MC1-pNFAnBk9a5tyXyW9AmwSozN8QU_FFHtJFrI
12. (PDF) The impact of informal settlement on water quality of Diep River in Dunoon, accessed March 18, 2025, https://www.researchgate.net/publication/358044579_The_impact_of_informal_settlement_on_water_quality_of_Diep_River_in_Dunoon
13. Call to improve signs for lagoon 'health hazard' - Isolezwe lesiXhosa, accessed March 18, 2025, https://isolezwelesixhosa.co.za/news/2025-01-23-call-to-improve-signs-for-lagoon-health-hazard/
14. Six-month aeration trial commences at Diep River and Milnerton Lagoon to combat pollution, accessed March 18, 2025, https://www.iol.co.za/capeargus/news/six-month-aeration-trial-commences-at-diep-river-and-milnerton-lagoon-to-combat-pollution-cb1d2192-b1b6-407b-b548-dd1eb7e83e8f
11. Report Compiled by Google Gemini Deep Research March 2025
12. Disclaimer
The 'Milnerton Lagoon / Woodbridge Island Pollution Status Report March 2025' was compiled by Google Gemini (Deep Research) on the request of Vernon Chalmers Photography. Vernon Chalmers Photography was not instructed by any person, public / private organisation or 3rd party to request compilation and / or publication of the report on the Vernon Chalmers Photography website.
This independent status report is based on information available at the time of its preparation and is provided for informational purposes only. While every effort has been made to ensure accuracy and completeness, errors and omissions may occur. The compiler of this Pollution Report (Google Gemini Deep Research) and / or Vernon Chalmers Photography (in the capacity as report requester) disclaim any liability for any inaccuracies, errors, or omissions and will not be held responsible for any decisions made based on this information.
More Information (Water Quality Updates Milnerton Lagoon, Woodbridge Island)
Attached Image © Copyright Vernon Chalmers Photography