Cape Town dams: Day Zero is now just 14 weeks away

steenbras dam digging city of cape town water

The City of Cape Town released its first dam report for 2018 on 1 January, but you’d be hard pressed to find any new year cheer in it.

To recap, levels across the City’s monitored dams were at a combined 31%, down by a percentage point over the previous week. Daily water consumption remained relatively low in comparison to previous months, with 578-million litres per day being consumed by Cape Town’s residents and industries.

Roll on to the latest report, released on 8 January, and the overall picture gets a little bleaker.

cape town dam levels 8 jan 2018Dam levels are now at 29.7%, dropping by 1.3% over the previous reported week.

Just one of the six dams in the Western Cape Water Supply System (WCWSS) — the collective name for the six largest dams that supply Cape Town and surrounds — saw an increase in storage levels. This was the Wemmershoek Dam near Franschhoek which gained a minute 0.2%, remaining just 52.3% full.

Its neighbour, the Berg River Dam, dropped by 1.2% over the previous week to hold 58% of its designed capacity. The Steenbras Lower and Upper dams dropped 1.6% and 0.6% respectively.

Cape Town should now brace for Day Zero, now forecast to strike on 22 April 2018

But the biggest losers were the two largest dams in the system — the Theewaterskloof and the Voëlvlei. The former lost 1.6% of its total capacity now standing at just 16.8% full.

The Voëlvlei Dam continued the downward trend, also dropping 1.6% to its current level of 20.6%.

Overall, the WCWSS’s major dams lost a total of 11.9-billion litres over the previous week, enough water to supply Cape Town for around three weeks.

dam level history wcwss 8 jan 2018

The City of Cape Town has also included new graphs in its dam report, highlighting the deviation of the current dam levels from that of previous years, stretching back to 2009 (above).

This alongside its new “Weekly Dam Drawdown Tracker” (below), which factors in noncompliance with Level 6 water restrictions, maximum calculated evaporation and similarly dismal rainfall we saw in 2017.

Currently, it suggests that Day Zero — the day collective dam levels will hit 13.5% — now stands at 22 April 2018.

wcwss weekly dam drawdown tracker 8 jan 2018

And in case you’re wondering, the rainfall over the weekend (below) did not affect the City’s larger dams.

Theewaterskloof’s catchment area received just 0.7mm of rainfall, while the Voëlvlei area didn’t see precipitation at all. The Steenbras catchment area also received a dismal 0.9mm between 6 and 7 January.

rainfall cape town 8 jan 2018

The Wemmershoek catchment area saw 6.3mm of rainfall on Sunday, helping the dam’s storage level remain relatively stable.

Incidentally, Newlands received close to its entire monthly rainfall average for January in just two days. We could use some of this rainfall over an actual dam though.

Read all previous articles on the Cape Town water crisis here.

All images, figures and graphs: City of Cape Town

Andy Walker, former editor


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