Dams – Latest levels: Winelands and Cape Town

(Stock photo)

Latest report (updated 7th November) on the main dams serving

Cape Town City and nearby Boland/Overberg towns

The combined water stored in the six main Cape dams dropped to 58.7% of overall capacity. We can expect this to be the regular pattern throughout summer – the water levels stored in the dams should fall fairly steadily now until arrival, hopefully, of relieving rains in during 2017.

So the most important indicator we will watch now is how fast stored water levels fall each week as a % of full capacity; this will indicate how much longer the water may last. We will also compare the change to the same period in 2015 because that will indicate how well the water saving measures are working this year compared to unrestricted use. So what happened this week?

Total water stored dropped faster this week (-1.1%) than it did last week (-0.9%); perhaps because some rain run-off was still flowing to the dams during the previous week; so this indicator probably still has to settle down. However, when compared to the same week in 2015, the drop was markedly less this year (-1.1% vs -1.4%); this is a good sign as it means less water is being consumed (an indication perhaps that restrictions are working?) than was the case in 2015.

Do we have enough water stored to see us through? Calculated using this past week’s drop in the total water stored, in the worst case of no significant rains falling across summer, then the water still stored by end of May 2017 would be around 24% of capacity. Assuming also that the last 10% or so of water in the dams cannot be easily used, then that would leave available only 14% of capacity. At the present reduced consumption rates that would equal just 3 months supply.

Now; some rains will surely fall across summer and some will end up in the dams so the situation may not get so dire. And our hope that a La Niña weather system may set in could see some strong earlier rains in 2017 which could relieve the situation quite quickly. However, even with normal winter rains in 2017 and 2018, it could take the dams two full years to recover.

The task is clearly to save water while we still can! Last week Hilary James reminded us that in 1983 Natal suffered a terrible drought.  “Every household was restricted to 12 Kiloliters of water a month. That’s 400 litres a day! If you exceeded your quota you received a heavy fine. If you did it a second time a restriction was fitted so that you would need to run water all day in order to receive your quota. Every body became very inventive with their limited water. The washing water was used to flush the toilets and the rinse water was put on the garden to save some of it. The children shared baths. As did the parents. We all strived to use less than our quota in case the drought continued. All leaking taps and pipes where repaired.”  So we are still relatively better off than areas where water supplies are already being cut for 8 hours per night.

Encouragingly, a mild, wetter La Niña weather pattern seems to still be prevailing, with what looks like a fairly normal summer rainfall pattern emerging inland as expected by the SA Weather Services. We may therefore still hope for unseasonal rains also falling in the Cape area.

The long-range weather forecast still predicts some unstable weather around the 22nd/23rd of this month with the possibility of thunderstorms. More light rain is forecast for early December. But there are no major systems foreseen at this time.

In Summary: outflows exceeded inflows at all main dams so total stored water volume fell to 58.7% of capacity. Rate of water usage rose slightly from last week. Rain may occur mid-November. Level-3 water restrictions are in effect in Cape Town. Costs of water will rise on 1st December 2016.

Here are the levels of the six main dams that serve the Cape Town/Overberg/Boland area. Also shown is the total water storage level of all the dams in the whole greater Western Cape.

One bright spot: if you’re looking for a new or used bakkie (maybe in which to go and check the dams) McCarthy Toyota, Paarl are offering very good discounts. Call 021 8635900. Ask for Willie or Charles. To get the deal, say “I saw it on ShowMe’s Dams report”.

Read about a D-i-Y household rainwater harvesting and storage system here

Read our water-wise landscaping and water-wise gardening suggestions.

Click here to see Winelands Weather forecast of possible near-term rain.