Flood fears mount — authorities open fifth sluice gate at Vaal Dam and evacuate homes

6 Apr 2025

Authorities have opened a fifth sluice gate at the Vaal Dam as inflows surge at an alarming rate. The rising water levels have prompted urgent warnings for low-lying communities, with the risk of riverbanks overflowing and posing a threat to homes and livelihoods.

In response to a dramatic surge inflow, authorities have activated a fifth sluice gate at the Vaal Dam. The rapidly rising water levels have triggered urgent warnings for low-lying areas, with concerns of bodies of water breaching and endangering homes and livelihoods.

The Department of Water and Sanitation requested the evacuation of residents near the Vaal Triangle, Parys and tributaries around the Vaal River, as well as farmers with pumps and equipment at the riverside.

The fifth sluice gate was opened at 10am on Sunday after Johannesburg received significant rainfall over the past week.

It was opened by the department less than 24 hours after a fourth sluice gate had been opened.

Spokesperson Wisane Mavasa told Daily Maverick on Sunday afternoon that the department could not rule out opening more sluice gates.

“As of midday today (Sunday) we are still receiving increased water inflows. It has increased from what we were getting on Sunday morning by about 200 cubic metres per second.”

The department said the Bloemhof Dam’s storage levels had also surged, climbing from 103.23% on Saturday to 106.91% on Sunday morning. The department said to manage the rapidly rising levels, water releases would gradually increase: starting at 1,100 m³/s at 10am, followed by 1,200 m³/s at 12pm, 1,300 m³/s at 2pm, and peaking at 1,400 m³/s by 4pm.

It it was prioritising dam safety and protecting critical infrastructure. The measures were also expected to ensure full storage capacity would be available once the rainfall season concluded.

The department said the outflows from the Vaal Dam were expected to hit the Vaal River Barrage Reservoir in about six hours and Bloemhof Dam within three to four days, causing rising water levels and overtopping riverbanks.

It warned that the increased releases from the five sluice gates might lead to downstream flooding, threatening infrastructure in lower-lying areas within the 100-year floodline or a 100-meter radius.

Evacuations

Downstream of Bloemhof Dam, the swelling water levels pose a significant challenge, set to impact everyone along the riverbanks in the Lower Vaal Catchment.

The department has informed those who might be affected to remove valuable equipment, movable structures and livestock to minimise potential damage or loss.

In Mpumalanga, where the Grootdraai Dam is located, the department said one sluice gate remained open at 2.5 meters to facilitate water releases. The department said the Grootdraai dam level currently stood at 102.41%.

The department said the Vaal Dam levels had swelled from 107.82% on Saturday to an imposing 109.39% on Sunday morning. Outflows are set to rise from 550 m³/s to just under 700 m³/s, while inflows continue pouring in at 1,000 m³/s — an ongoing testament to nature’s unrelenting force.

The department said key stakeholders in the unfolding situation include disaster management teams across national, provincial and local municipalities, specialised police water units, as well as farmers and communities both upstream and downstream along the Vaal River system.

Regular updates and alerts

The department was actively disseminating hydrology reports and updates through multiple platforms, ensuring stakeholders were regularly informed of dam water levels. During rainfall or potential flood scenarios caused by rising upstream levels, these updates shift to daily and hourly alerts.

Accompanied by actionable recommendations, they form the backbone of early warning systems and enable timely activation of evacuation plans.

Mavasa said every dam had its own control protocol, so what applied to the Vaal Dam might not necessarily be identically applicable to other dams.

“If Grootdraai Dam continues to receive more inflows from upstream, it necessitates that we also increase the outflows to manage the infrastructure,” Mavasa said.

“When the outflows are released, they flow down to the Vaal Dam together with the tributaries that are flowing in. Those also increase the inflow and necessitate the releases for us on the … Vaal Dam.” DM

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