Have your say on City’s estuary plan

The Rietvlei and its wetlands will be affected by the draft management plan.

The public has until the end of June to comment on the City’s draft plan to manage the pollution-plagued Diep river estuary in Milnerton.

The river flows from the Riebeek Kasteel mountains, north-east of Malmesbury in the Swartland local municipality and through the Rietvlei wetlands, comprising Flamingo Vlei and Milnerton Lagoon, which form part of the estuary that covers an area roughly the size of 900 rugby fields.

The review of the plan is seen as critical because it will look for ways to ease urban pressures on the estuary, according to mayoral committee member for spatial planning and environment Eddie Andrews.

The Stellenbosch, Swartland and Drakenstein municipalities also hold authority over parts of the river feeding the estuary.

Water quality had declined over time, “with total dissolved salts, nutrients and suspended solids increasing consistently” and growing residential and industrial developments had affected the ecosystem in the catchment, said Mr Andrews.

“These have had either a direct or indirect impact on the functional integrity of the estuarine system.”

David Ayres, who heads the planning and bio-diversity portfolio for the Greater Table View Action Forum, said that upgrading the Potsdam sewage plant and freezing new developments connected to it would ease pressure on the ecosystem.

The City should also examine the type of effluent that was being pumped into rivers across the metro, he added.

He accused the City of forging ahead with densification at the cost of the environment despite knowing the Potsdam plant couldn’t cope.

The City had conceded that it would take 18 years to reverse the damage to the Diep River, he said.

“To put that into perspective, a child born today would have to endure an environment harmful to their health until they reach adulthood. They’d never be able to swim in the river or the sea.”

According to Mr Andrews, other sources of pollution entering the Diep River, apart from the Potsdam plant’s treated effluent, include run-off from agricultural and industrial areas, substances that residents illegally dispose of in the stormwater system, foreign items dumped in sewer systems, and sewer spills.

About a third of the estuary was surrounded by developed land, where roads and embankments reduced its natural ability to meander, he said.

“The revised plan includes new information and recommendations and was workshopped with external experts and independent scientists in the field of coastal and estuarine science,” Mr Andrews said.

The estuarine management plan, developed by the City’s environmental management department, divided the river into six zones, with priorities and objectives tailored for each. It also outlined capital projects such as improvements to bulk sewage infrastructure and an upgrade for Potsdam that would see it expand and use new treatment technology, he said.

Other projects included building stormwater-to-sewer diversions in Dunoon and Doornbach and treatment wetlands at Erica Road and Bayside Canal outfalls and seeing to it that all pump stations in the Diep River’s catchment worked properly and were linked to a generator.