Durbanville residents’ hope was restored when Ward 21 councillor Hendri Terblanche called a meeting last Thursday (13 February) to announce that plans are in motion to restore and rehabilitate the Rosendal Dam.
“So today we’ve got the experts, you asked for a solution, and I’m not an expert, but I trust the capable employees of the City of Cape Town, because they always proved themselves in the past. And I also believe that they will provide us with the necessary expertise to proceed and rehabilitate Rosendal Dam. We look forward that everybody can still enjoy it,” Terblanche announced to residents present, overlooking the dam’s banks.
This follows some years of locals raising concern of the dam’s state resulting in either dead fish washed ashore en masse, or birdlife migrating to other areas (“Dead fish shock Durbanville residents, walkers”, TygerBurger, 3 April 2024).
Experts engaged
Terblanche introduced the following experts from the City to relay the dam’s rehabilitation game plan:
- Vincent Harris, the District Head: Roads and Stormwater serving District 2 (Kraaifontein, Brackenfell, Durbanville & Bellville above the N1), from the roads infrastructure and management department under the Urban Mobility Directorate.
- Sihle Jonas, an Ecological Coordinator at the City serving the Ecological Management Unit under the recreation and parks department as well as community services and health.
- Willem Myburgh, the area head for horticulture for the recreation and parks department under community services and health.
Elma Hatfield was also introduced as an assistant available to deal with residents’ queries.
Dam issues discussed
Myburgh, Jonas and Harris respectively touched on challenges and solutions best suited in terms of financially sustainable options for Rosendal Dam’s rehabilitation.
Challenges discussed related to water levels and seasonality in that the dam fills up during winter rains but dries up in summer, leading to water shortages. This affects water quality with reduced water levels leading to poor water quality, contributing to algal blooms.
This explains the mass fish deaths due to low oxygen levels caused by algal blooms.
But another issue was the prevalence of only invasive fish species to the local environment, worsening ecological imbalances.
The impact driven by trees and birds was discussed in that trees on the island attract birds, whose droppings increase nutrient levels in the water, worsening water quality.
Illegal fishing and fish transfer explains the prevalence of invasive species, no thanks to fishermen introducing such species by moving fish between water bodies, further disrupting the ecosystem.
The dam is the only stormwater inlet, accumulating excess nutrients and contaminants while natural evaporation still leads to significant water loss, despite efforts to block the outlet.
Another option to rehabilitate the dam initially considered was disruptive dredging. However, Myburgh explained that dredging as a solution is costly, ineffective long-term and would damage the surrounding park area.
Plans set in motion
- Tree removal: All trees on the island will be removed to deter bird roosting and reduce nutrient buildup.
- Island rehabilitation: The island will naturally be covered by reeds and grasses; no active planting will be done.
- Invasive fish removal: All invasive fish will be eliminated using an approved fish-killing treatment.
- No-fishing policy: Strict enforcement of the no-fishing rule, with new dedicated no-fishing signs.
- Fishing permit enforcement: Public awareness that Cape Nature permits alone are not enough; municipal permission is also required.
- Prohibition of fish release: Signage will be installed to prohibit the release of fish into the dam, as it is illegal without a permit.
- Natural water filtration: Reeds will be encouraged to grow around the island to help with water filtration.
- Stormwater management: Efforts will continue to manage water levels effectively and minimise nutrient buildup from run-off.
Jonas confirmed that chemical called piscicides will be used to remove the fish in the dam.
“Biodiversity management got a tender for the piscicides and applications have been made to use this tender. As soon as we get permission, we will use it which kills anything with gills,” Myburgh added.
As the dam’s systematic rehabilitation is set in motion, pending more meetings with experts and officials, quotes, certain tenders and official permissions, Terblanche continued to highlight uses for the dam in Rosendal Park and ways residents may look forward to the future.
“If you look, for example, there at the back (of the park), it would be a perfect setting for a philharmonic orchestra, or like, for example, a residence picnic . . . there are so many opportunities.”
