Dam levels trail last year’s figures as super El Niño threatens South Africa’s water supply

South Africa faces a high probability of a strong El Niño developing this summer, raising the risk of water restrictions, rising costs and strained supply as key dams already sit below where they stood a year ago.

The event carries the risk of agricultural strain and higher food inflation heading into 2027, though full dam levels from previous wet seasons offer the country a buffer going into the new season.

Independent water expert Carin Bosman said the effects would depend on how the season unfolds, but warned that a drier summer would inevitably squeeze supply.

“With a forecasted drought, there will be less water availability, which will inevitably lead to more restrictions, increased costs (not just municipal, but everything down the value chain), and lower reliability of supply,” she said.

The Department of Water and Sanitation (DWS) said it is watching conditions closely and stands ready to act if needed.

“Should our monitoring systems show early signs of dry conditions, water users may be required to proactively implement water conservation measures, and in some systems water use restrictions may be introduced where necessary to ensure water security,” DWS spokesperson Wisane Mavasa said.

How current dam levels compare with a year ago

Weekly figures show that the major dams supplying Cape Town and the surrounding Western Cape Water Supply System stand at 77.7% of capacity for the week of 7 August 2026.

By comparison, the same week the previous year had storage at 84.8%.

Individual dams tell a mixed story.

Theewaterskloof, the largest dam in the Western Cape system, sits at 77.8% on 7 August, while Voëlvlei is lower still at 61.5%.

Steenbras Lower is the weakest of the group at 53.6%, whereas Steenbras Upper, Berg River and Wemmershoek all remain above 90%.

The Gariep Dam, South Africa’s largest dam by capacity, stands at 99.3% this week, unchanged from last week, according to DWS.

At the same time last year, the dam was recorded at 99.1%, meaning it currently sits marginally ahead of where it was a year ago, despite the broader national trend of dams running below 2025 levels.

In Gauteng and the Free State, the Vaal Dam, which along with the Vaal Barrage supplies much of the country’s economic heartland, remains close to full.

Storage over the week of 10 to 16 August 2026 ranges between 100.63% and 101.89%, averaging 101.41% for the week.

That marks a decline from the same period the previous year, when the Vaal Dam stood at 107.2%, according to the weekly provincial state of dams report.

Bosman said healthy-looking numbers should not be mistaken for security. “If consumption patterns are not reduced early enough, people can be caught with their pants down, because there is nothing you can do to fill a dam once it’s empty except wait for rain,” she said.

DWS echoed the caution, noting that “healthy dam storage levels provide an important level of assurance for current water availability but should not be interpreted as a guarantee against future water shortages.”

Four decades of recurring drought

South Africa’s current concerns sit within a much longer pattern.

Research published in 2021 in the journal Science of the Total Environment found that the country has been hit by drought repeatedly over the past 40 years, with major episodes recorded in 1982-1984, 1991-1992, 1994-1995, 2004-2005, 2008-2009, 2015-2016, and again in 2018-2020.

The researchers noted that these events have consistently rippled beyond the environment itself, disrupting social and economic systems as well.

The human and economic toll of past droughts has been substantial.

The 1992 drought is estimated to have affected around 250 000 people, costing roughly 50 000 agricultural jobs and a further 20,000 in related industries, according to the study’s review of historical impacts.

More than a decade later, during the 2007-2008 drought, government spending on agricultural drought relief – mostly subsidised livestock feed distributed according to farm size – topped R285 million, equivalent to about 19 million US dollars at the time.

The study also pointed to the 2015-2016 drought as a turning point that exposed how a single dry spell can cascade across multiple sectors of the economy at once.

Drought cycles and the difference a ‘super’ event makes

Bosman explained that South Africa moves through drought and flood cycles roughly every eleven years, and that the country is now about eleven years on from the 2016 drought that triggered Cape Town’s “Day Zero” crisis and water shortages in Gqeberha.

Asked whether the country was likely to see an actual drought this season, she pointed to that same cyclical pattern as the basis for her expectation.

She also distinguished between an ordinary El Niño and a “super” version of the phenomenon. “Climatologically, we go through ‘wetter’ (La Niña) and drier (El Niño) cycles every 11 years or so, but one of the effects of climate change is that it ‘speeds up’ the hydrological cycle,” she said, adding that higher temperatures lead to more evaporation, “and that creates longer lasting and more intensive droughts in some areas, and larger floods in other areas.”

DWS took a more cautious line on classification, saying its planning is not driven by descriptive terms.

“DWS bases its planning and operational decisions on official seasonal climate information and observed hydrological conditions rather than descriptive terminology,” Mavasa said.

She added that regardless of how a climate driver is labelled, the department follows “a risk-based approach involving continuous monitoring, preparedness planning, stakeholder coordination and adaptive water resource management to respond proportionately to prevailing conditions.”

Why some provinces face more risk than others

The picture varies sharply by region, with the Eastern Cape and KwaZulu-Natal already trending below the previous year while the Free State and Western Cape hold up more strongly.

Bosman said the pattern comes down largely to how carefully residents and industries manage consumption.

“Those who plan early and use water sparingly will be the least at risk,” she said.

DWS said provincial averages could be misleading given how fragmented the country’s water systems are.

“South Africa’s water resources are managed through a number of different catchments and water supply systems, each with unique hydrological characteristics,” Mavasa said.

“Consequently, risks differ between systems and cannot be determined solely by provincial dam storage percentages.”

Bosman advised residents to track the situation at a catchment level rather than relying on national headlines, watching the figures published for their own catchment areas by DWS and local water boards, since some dams will draw down faster than others depending on local consumption and inflows.

No part of the system is immune

Asked which parts of the country’s water infrastructure were most vulnerable to a fast-onset drought, Bosman said the risk is spread evenly across the network. “It’s not possible to determine which of bulk and municipal supply vs irrigation supply will run out first,” she said.

DWS gave a similarly broad assessment, saying the greatest danger lies in the combined strain of multiple pressures hitting the system at once.

“The most significant risk during an extended drought is the combined effect of reduced inflows, increased water demand and evaporation losses, particularly in water supply systems that are already under pressure,” Mavasa said.

She added that if a severe drought develops, the department would be “most concerned about water storage and supply infrastructure, especially dams, reservoirs, and the bulk water supply systems,” along with a declining groundwater regime.

Soil moisture and groundwater offer only a temporary buffer

Bosman set out three scientific categories of drought and explained how they build on one another.

A meteorological drought occurs when rainfall drops below normal, an agricultural drought follows once soil moisture declines, and a hydrological drought sets in once surface and groundwater levels fall after a prolonged dry spell. She said soil moisture and groundwater can cushion the country for a period but not indefinitely, “as groundwater needs rainfall in order to be recharged”.

DWS confirmed that it tracks both indicators as part of its broader monitoring effort.

“Healthy soil moisture supports agricultural production during short dry periods, while groundwater provides an important supplementary water source during times of reduced surface water availability,” Mavasa said, adding that the department monitors groundwater levels “alongside surface water resources to improve understanding of overall water availability”.

Uncertainty over timing and forecasting reliability

On how quickly conditions could deteriorate once the critical November-onward rainfall period arrives, Bosman expressed confidence in the underlying science, noting that forecasts are built on more than 80 years of historical data alongside internationally sourced information. “The climatologists usually publish the uncertainty factors with their data,” she said.

DWS took a more guarded view of what seasonal forecasting can actually deliver at a local level. “Seasonal climate forecasts are an important planning tool and provide valuable guidance on the likelihood of wetter or drier than normal conditions over broad regions,” Mavasa said.

“However, they are probabilistic in nature and cannot accurately predict rainfall at local scales or the precise timing and magnitude of rainfall events.”

Both Bosman and DWS declined to predict how the current event might compare with the droughts of 1982-83, 1997-98 or 2015-16. Bosman said the uncertainty over duration is itself the reason for caution, noting that “we don’t know how long it will last, and therefore we need to always use water sparingly, even in times of abundance.”

DWS gave a near-identical assessment, saying that “each El Niño event differs in terms of timing, intensity and regional impacts”, and that it is “not appropriate to assume that future conditions will mirror previous events.”

What residents can do now

With many dams still looking relatively healthy on paper, DWS said ordinary households share some responsibility for protecting the buffer.

“The Department encourages all South Africans to use water wisely at all times, regardless of prevailing climatic conditions,” Mavasa said, pointing to responsible use, fixing leaks and avoiding unnecessary losses as steps that would strengthen national water security.

Bosman’s advice points in the same direction, framed around vigilance rather than alarm.

She urged residents to track the figures for their own catchments through DWS and local water board publications rather than relying on national averages, since early, sustained conservation offers the surest protection against a fast-moving drought.