When a Water Sample is Not a Water Sample
When a Water Sample is Not a Water Sample: For the past two weeks, here in South Africa, a heated debate has been brewing over water quality sampling protocols in large water bodies. While the technical jargon—centred around “statistical representativity”—might put you to sleep, the public spectacle of elected officials navigating this minefield has been quite the show.
To grasp this issue, we need to tackle “statistical representativity” without inducing a nap. Let’s use Rand Water as our example.
Once upon a time, the South African economy was booming, thanks to the Witwatersrand goldfields. But extracting gold required water, and the Transvaal Highveld, a dry grassland, had little to offer. Enter Rand Water, created to supply water to the goldfields. As people flocked to the mines, towns sprouted, and trees were planted to combat dust, creating the largest man-made forest on the planet. Rand Water became the backbone of civilization in Gauteng.
But what does this have to do with statistical representativity in water quality sampling? Gauteng’s water supply relies on the Vaal River System, which has suffered from pollution over time. Rand Water needed to monitor these large water bodies effectively. Enter satellite surveillance.
The question arose: Can satellites monitor a large water body better than traditional grab sampling (taking a litre of water from anywhere in the lake)? Rand Water launched a research program to find out, using satellites to monitor light reflection off the Vaal Dam while taking grab samples to calibrate the data. Cyanobacteria, which absorb light, were measured to quantify their presence in the water.
The results were impressive. The Vaal Dam, plagued by eutrophication (nutrient enrichment from sewage), often experiences cyanobacteria blooms, affecting drinking water treatment. Rand Water’s monitoring program found that grab samples taken every two weeks were not representative of the entire water body. Satellite imaging, however, provided a more accurate picture.
Now, let’s compare this to Cape Town’s Blue Flag beach status debate, where one grab sample per week is taken to claim water safety. If grab sampling isn’t representative for the Vaal Dam, how can it be for the ocean?
Rand Water’s two-year research program, in collaboration with Cyanolakes, developed an accurate reporting protocol for cyanobacteria and algae. The data is now featured in all Rand Water reports on Vaal system water quality. The study found that cyanobacteria levels correlate with rainfall events, and satellite imaging is useful for detecting trends.
In conclusion, statistically representative sampling is crucial for public trust. Rand Water’s pioneering efforts in this field should be applauded. As for Blue Flag beaches, reliable safety reporting requires scientifically robust protocols. Just because something worked in the past doesn’t mean it’s still effective today.
So, let’s not demonize scientists when politicians misunderstand their message. Instead, let’s celebrate the advancements in science, engineering, and technology that help protect our water systems. And they all lived happily ever after—thanks to evolving science and technology.
Sardines and Sighting Maps
We have started the 2025 Sardine Run Map! And it already has some sardine action logged!
2024 was a thrilling year for sardines. All the action has been logged right here on The Sardine News. The 2024 map has been viewed 200 000 times and just keeps growing.
Which led us to decide to keep the map live. And keep adding unique marine animal sightings and events. That occurs non-stop all year round. This year we started to log more whale and dolphin sightings. And we even had a shipwreck! And a freaking tornado! And recently a capsized KZNSB boat! We have been updating the map with recent catches too…
These events will from now on be included in the Sardine News Sightings Map for 2024. And on the 1 January 2025, we shall start all over again.
Here are the links to existing and past Sardine Sighting Maps. Great for a windy day like today to research. With instructions to install The Sardine News right on your phone or desktop.
2025 Sardine Map
2024 Sardine Map
2023 Sardine Map
2022 Sardine Map
2021 Sardine Map
Channels
Brucifire Surf Retorts – highly entertaining surf reporting
Master Watermen – news from way down deep
The Sardine News – neva miss a single sardine
FishBazaruto – 1000 pounds plus
MYDO Tackle Talk – highly technical sport fishing
Surf Launching Southern Africa – getting out there safely
Water Woes – complain about your municipality here
Websites
umzimkulu.co.za – self-catering right on the Umzimkulu River
umzimkuluadrenalin.co.za – will get you right out and onto the edge
thesardine.co.za – never miss a single sardine
masterwatermen.co.za – news from under water
fishbazaruto.com – dreams
brucifire.co.za – surf retorts
