Cape Town dams at 38.5%, desalination timeline remains unclear

city of cape town water consumption calculator

Last week, Cape Town welcomed a weak cold front that brought some 30mm of rain in some areas of the city. But this hasn’t done much to bolster dam storage according to the City’s latest report.

Total storage in the six major dams supplying Cape Town is down by 0.1% to 38.5% (pdf). That’s a loss of around 519-million litres — slightly less than the average day’s consumption in the city.

Cape Town’s dam levels

Leading the decrease was everyone’s favourite underperforming dam — the Theewaterskloof.

The largest reservoir in the Western Cape again struggled to hold its level, dropping from 27.8% last week to 27.3% this. At the same point last year, it was 51% full.

The Steenbras Upper Dam dipped to 100.4% — shedding 1% — while its Lower neighbour gained 1.1% overall.

cape town dam levels 31 october

Image: from City of Cape Town dam report, 30 October 2017

The three other large dams located in the mountains of the Western Cape Water Supply System saw gains, with the Berg River Dam now up to 68.7%. It’s now just 4.3% shy of its level last year.

The Voëlvlei Dam was the other big gainer, adding 0.5% to last week’s level of 27.9%, with the Wemmershoek Dam’s level growing to 48.2% from 47.6% last week.

As for the City’s eight minor dams, only three atop Table Mountain saw increased levels.

October’s rainfall figures

Cape Town’s final rainfall figures for October also paints a welcome picture.

The City noted that six of the ten areas it monitors received more rainfall than their long-term averages. This included both Voëlvlei Dam and Wemmershoek Dam catchment areas.

cape town rainfall levels 31 october

Image: from City of Cape Town dam report, 30 October 2017

Theewaterskloof’s catchment area fell well short, receiving just 33% of its long-term average rainfall for October, partially explaining its waning levels this month.

The Steenbras catchment area also received around 20mm less rainfall this month than usual.

Western Cape’s dam levels

According to the Western Cape government’s latest records published on 23 October, nine dams in the Karoo are below the 10% mark.

This includes the Gamkapoort Dam (north of Calitzdorp), the Oukloof Dam (near Prince Albert) and the Gamka Dam (outside Beaufort West).

The latter, in fact, is completely empty.

Other dam levels are more promising. Worcester’s Brandvlei Dam saw gains of 0.6% last week, while the Garden Route Dam gained 2.2% over the previous week.

Find all Western Cape dam levels listed here.

Cape Town water consumption

For the second week in a row, Cape Town’s residents consumed less than 600-million litres per day.

It again hit the 585-million litres per day mark, suggesting that the City’s water rationing programme may be a factor in the reduction.

Nonetheless, residents are still using 85-million litres per day more than the City’s target. This is down from 1.1-billion litres per day prior to water restrictions came into effect.

The latest augmentation plans

Thank you Cape Town for your all your efforts and for being partners as we adapt to the New Normal. We will not allow a well-run city run out of water (sic),” noted mayor Patricia de Lille in a statement.

We are bringing more alternative water sources into our network while all Capetonians must continue to save. The only way through this is together.

Among these alternative water sources already online, the Atlantis and Silwerstroom Aquifers are reportedly adding an additional five million litres per day to the City of Cape Town’s water production.

This will increase incrementally to 25 million litres per day,” de Lille added.

The mayor will this week will also visit the Zandvliet Wastewater Treatment Works in Khayelitsha, which will be upgraded to “deliver 10 million litres per day” to the system.

The eight planned desalination plants however have yet to be given a confirmed date of operation.

Feature image: City of Cape Town

Andy Walker, former editor


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