Ohlanga revival: how UPL’s rehabilitation effort is bringing life back to the river and estuary

MARCEL DREYER

The ongoing rehabilitation of the Ohlanga River and catchment area recently received a major boost with the next phase of work on the waterways has been given the green light by the KwaZulu-Natal Department of Economic Development, Tourism and Environmental Affairs (EDTEA), which is the responsible government regulatory agency.

Getting the green light for this project to proceed is a significant milestone in the collaboration between UPL South Africa and local, provincial and national governmental departments. With the assistance of the Department of Water and Sanitation, EDTEA and eThekwini, work can now commence in earnest to bring the rehabilitation project to completion.

It has now been over three years since the arson attack on the leased warehouse in Cornubia which led to agricultural chemicals escaping into the environment. UPL South Africa immediately engaged experts in various fields to monitor and advise on mitigating the risk posed by the spill and cooperated with all relevant authorities to design and implement an extensive remediation and rehabilitation programme.

There have already been some major successes. From a diatom perspective (simple plants growing within the stream, and typically very sensitive to pollution and water quality changes), the tributary of the Ohlanga River, situated next to the former warehouse, has already shown to be in a fair to good condition and is close to its natural state before the 2021 incident.

The extensive monitoring and testing regime of the independent experts has for some time already shown that there are very low concentrations of residual chemicals related to the spill in the Ohlanga waterways that were once affected by the spill event.

The few chemical compounds that still register in laboratory tests are generally at the lowest limit of detection. Importantly, these chemicals are also far below their agricultural application level, meaning that the active compounds are so low that they would be deemed ineffective when applied in safe agricultural environments.

Work on the tributary will include soil health assessments of the riverbed and banks. Where necessary, the team will introduce new organic material to restore plant life. Scientists will also monitor the soil’s health down to its microbiome. In areas where they find a comparative lack of native microbes, the soil will be inoculated to kickstart the development of a healthy soil microbiome.

In a few areas, the riverbed or banks will be lightly shaped to increase stability, for vegetation establishment, or to place rocks and boulders to aerate the water or dissipate energy in the flow of the river. Where natural re-vegetation has not yet occurred, the team will select and plant indigenous species of grasses, trees, and other plants – all regulated and approved as part of the EDTEA-mandated processes.

To ensure that these new indigenous plants thrive, the team will mechanically remove plants that are not desirable or that compete with the natural restoration, including alien vegetation.

The wetland will also see similar rehabilitation efforts. Owing to the nature of the water flow in the wetland, some areas of the wetland will need similar soil enhancement through the introduction of organic material and the reintroduction of beneficial fungi and bacteria. In some areas, the soil layers will be turned to encourage the growth of this microbiome and to facilitate the breakdown of any residual herbicides that may linger. The estuarine and marine specialist on the team currently recommends no physical rehabilitation interventions in the estuary.

Various zones within the wetland will be replanted with different groupings of indigenous plants, taking account of factors such as water flow and water depth. Any alien vegetation that hinders the growth of indigenous plants will be removed.

The goal of this phase of intervention is to return the tributary and estuary to a state that resembles the river before the July 2021 incident. The tributary, river and estuary are next to human settlements, commercial developments, roads, and agricultural land. Pollution from these sources constantly finds its way into the waterways.

There are no residual impacts on the bed or banks of the small portion of the Ohlanga River which was affected by the spill and no intervention is necessary.

The city’s declining sewerage infrastructure also poses a threat, and sewage spills into the river are a frequent enough occurrence that the team monitoring the Ohlanga also monitors the levels of E. coli in the water. At various points over the past three years, the E. coli levels were so high as to present a danger to human life, pointing to elevated sewage levels that also threaten plant and animal life.

Earlier in 2024, a large fish die-off in the estuary was traced back to poorly performing large wastewater treatment works within the catchment and sewage-related pressures causing severe oxygen depletion in the water and the fish deaths. During this sewage-induced fish kill in the Ohlanga Estuary, hundreds of healthy fish were noted in the previously contaminated Ohlanga tributary below the original spill site.

The rehabilitation project has already seen net positives for the affected watercourses. The pollution control dam (PCD) situated adjacent to the former warehouse is designed to catch any residual chemicals from the slab during rain. The PCD water is then treated by a Department of Water Affairs and Sanitation (DWS) approved and licensed state-of-the-art water treatment facility, removing to non-toxic levels any residual chemicals which remain, after which the clean water is released into the Ohlanga tributary.

The experts working on the site have observed that the treated water is of such a high standard that it is typically now acting as a dilutant for other sources of pollution along the river.

That UPL South Africa can start on this significant next phase of rehabilitation is a testament to the significant progress that has been made over the past three years. UPL South Africa has remained committed to the rehabilitation project and has reconfirmed this in recent engagements with local, provincial and national government stakeholders.

With the immense effort and man-hours that the team of experts are committing to this project, it is anticipated that the affected environment will soon be back to its pre-2021 state.

Marcel Dreyer is UPL Africa’s regional head.

***The views expressed here are not necessarily those of Independent Media or IOL.***

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