Cape Water and Dams Report
(Kwaggaskloof Dam. Photo : Brown)
Dams – Latest levels: Winelands and Cape Town
Report nr. 92 (updated 5th March 2018) on the main dams serving
Cape Town City and nearby Boland/Overberg towns
Dams once again benefited from transfers from Kogelberg dam but less from rainfall runoff. Combined levels of the main dams dropped by 4.2 M.cuM, or 0.5% of capacity (vs the preceding week’s outstanding 3.1 M.cuM) and from 23.7% to 23.2% of capacity.
Releases from Groenland Water Users have terminated at 10 M.cuM. As at last week 4.0 M.cuM had reached Steenbras Upper Dam with the balance due to get there across the coming 14-20 days.
In 2017 the main dams dropped by 13.1 M.cuM, falling 1.4% to 31.0% of full capacity. The stark contrast with last year is that by end-February this year, most allocations of water to the agricultural sector had effectively stopped.
Current status?
Combined water stored in the 6 main dams fell to 207 M.cuM (122 M.cuM of easily accessible water) (last year, levels dropped to 275 and 190 M.cuM respectively over the same period).
How long will the remaining fresh water last?
We have entered March with over 207 M.cuM of water stored in the dams. This unexpectedly good result has been enhanced by the transfers.
However, even if we add back the transfers, our actual water consumption across the short month of February 2018 was less than 40% of what we used in the same period of 2017; an excellent outcome demonstrating the result of so many steps and efforts made to reduce water usage as well as possibly lower evaporation. So if we do reduce water consumed down to 50L/p/d then we should reach/exceed our Success Day target of 100 M.cuM of water in storage on 29 June.
But be aware that the Metro’s own consumption is staying stubbornly high which may yet reverse the present good trend and pull the disruption of “Day Zero” down on our own heads.
Are we winning?
Yes and no! At the moment the Metro is consuming some 537 ML/d and needs to get down to 450 ML/d if it is to meet the overall targets set by DWS. My estimate is that the average household consumption currently is about 78L/p/d. This is still way too high. It must be reduced to 50L/p/d if the Metro is to run consistently at 450ML/d in total. So, progress; but more is needed.
Here is the altered CoCT tracker chart showing how we are progressing towards our “Success Day” target. We are today at point red ‘X’ (23.2% of capacity on 5th March). The graph demonstrates that we remain above the dotted black line and therefore are more likely to reach our “Success Day” goal. Note, however, that the transfers continue to artificially improve the result – this effect will fall away by end-March and progress may slow.
Given that this result is being achieved despite the fact that the Metro consumption remains too high, furthermore means that both agriculture and the other municipalities have probably used less than that allocated to them by DWS. In fact Dep. Mayor Ian Nielsen confirmed last week that DWS has already sent a warning letter to the City regarding its failure to fully meet the lowered target.
(see here for a detailed explanation of how the chart is to be read).
What are the authorities doing now?
Here is a brand new graph to demonstrate progress being made by the City to produce extra water through the various augmentation initiatives. I measure this by comparison of the water that the City uses from all sources versus that which it draws from the dams; the difference clearly being water that it is producing though other means than surface run-off in the dam catchments.
On the graph, for clarity, I also show the present DWS allocation for Cape Town (yellow line) as well as the lower targets set by the City through level-6B restrictions (red dotted line). Why is this lower? Having lagged initially behind the DWS target the City needed to become more aggressive in February in an effort to compensate for its initial excess usage. The aim of the City is to push the blue dotted line down to the dotted red target line. That way it should reach end of June 2018 with sufficient water in the dams, while the augmentation supplies can be going to help rebuild water reserves in the dams for the following summer.
At the moment the augmentation contribution appears to be 36 ML/d. Having grown steady to this level from some 12 ML/d late last year. From this month its is expected to climb even more quickly, aiming at a total of 120+ ML/d by end-June and over 150ML/d by 2018 year-end. [ultimately the aim is to increase augmented water supplies to around 500 ML/d by 2020.]
See summary of Deputy Mayor Ian Nielsen’s full media briefing on Day Zero and augmentation.
See updated details of Cape Town’s planned interventions to produce fresh water here.
Learn about water savings efforts by other Cape municipalities – read more here.
Do visit the City of Cape Town website to see additional graphically presented information regarding the water situation – very helpful.
1) See the full water status presentation here and
2) Check out water usage for your property and of neighbours, friends, using this interactive map.
What ought you to be doing?
1) We need to get down to an average water consumption of 50L/person/day to be sure to avoid “Day Zero”. Please keep working on this and encouraging others to do better.
2) Doctors and pharmacists report that stomach-related ailments appear to be increasing. As the municipal water supply quality reportedly remains excellent, the main advice from practitioners is to ensure that everyone in the household applies good hygiene. Wash hands regularly during the day, always after handling “grey water” and especially before preparing food. A good tip is to add a few drops of bleach or Miltons to water used to wash hands and food (rinse again after).
Will the weather help?
La Niña is holding on and, while the trend is expected to shift back towards neutral, there is an increasingly high possibility that the ENSO area sea temperatures will remain somewhat below the mean; and so may contribute to a wetter Western Cape autumn and winter.
Occasional passing showers are possible but otherwise the weather is predicted to remain clear and warm over the coming few weeks. There are no big systems in the medium term outlook.
Our chart of rainfall for the dam catchments shows no meaningful rain at the dams last week.
In Summary: outflows exceeded inflows by 4.2 M.cuM and combined dam levels fell to 23.2%.
Here are the levels of the six main dams serving the Cape Town/Overberg/Boland area.
Plan ahead for possible water outages; here are points that could help.
Read our Indoors Water Savings Ideas here.
Read our Outdoors Water Savings Ideas here
Read about a D-i-Y household rainwater harvesting and tank system here
Read about South Africa’s desalination policies and initiatives.
Click here to see Winelands Weather forecast of possible near-term rain.
Report instances of piping failures and incorrect use to municipalities.
In Cape Town the contact details of the 24-hour Technical Operation Centre are: Email: waterTOC@capetown.gov.za Telephone: 0860103089 (choose option2: water-related faults) or SMS: 31373 (max 160 characters).
Tom Brown.
Retired international businessman with a background in Finance and IT; and now a fruit farmer, with a passion for the weather and climate.
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