Water quality and quantity are focal — or was that faecal — sujets du jour (burning issue) for East Londoners.
Many who live in Ducats, Nompumelelo and other parts of town were recently without water for well over a month. A month! Drinking the water that was tankered in was reportedly less pleasant than drinking bathwater.
While our municipal services may be lacking what it takes, our rivers are doing their utmost to supply us with a suite of eco-services.
If we would just stop getting in their way, with our endless weirs and dams, developments and pollution, the rivers would look after themselves. Healthy aquatic ecosystems have their own bioengineering teams and the best tech available to do this job solo. That is the design standard.
The non-living team-members include flow, habitat (rocks, stones, mud, sand), and river form. These provide the workspace for the biota. The living “workers” in the natural purification system include bacteria, fungi, sponges, mosses, plants and aquatic invertebrates, or bugs as we affectionately know them.
There are so many different types of bugs for this job that they have been organised into groups, for goodness sake:
- Grazers, which hoover up algae and such;
- Shredders, which shred coarse organics like leaves;
- Collector-gatherers, which collect wee particles of organics from the stream bed;
- Filterers, which strain out fine particles from the water column; and
- Predators.
In a healthy river, these little guys are unstoppable, and they keep the water clean enough to drink. But sadly, almost all cities, including ours, need to erect wildly expensive water treatment plants to provide drinking-quality water. In New York, they chose to rather save those billions, and look after their rivers. New Yorkers’ water comes from the Catskill, Delaware and Croton watersheds, and the river water is so clean that NY is one of few municipalities not required by law to filter its water — it is only disinfected by UV exposure. That is a city of 19.8-million. It is possible.
But, back to nature and those bugs. As river scientists we are able to gauge how polluted a flowing river is by looking at which bugs live in it. We use a method known as the South African scoring system version 5 (Sass5).
Sass5 was adapted for SA rivers in the late 1980s by river scientist Dr Mark Chutter, an old-school gentleman complete with white hair and specs. In the early 1990s, as a new postgrad student at Rhodes University, I was invited to assist Mark field-testing his new method in the rivers of the Eastern and Southern Cape. Ten days of netting bugs in beautiful rivers followed. I was hooked. One can really learn to love those soggy little critters.
The idea behind Sass5 is that every one of the 78 invertebrate family that live in South African rivers has a different known tolerance to polluted water, and is scored for this. The scores range from 1 to 15. The higher the number, the more sensitive the family is to pollution and degradation. A tuff mozzie larva would score 1, a horsefly larva 5, a common snail 3, different types of mayfly larvae 6 to 12, dragonfly larvae 6 to 10, a stonefly larva 12. Only two mayfly and one cranefly family score 15. Bugs with a score of 12 to 15 are increasingly rare in South African rivers.
When we “Sass” a river, we use a specially-made net to sample stones, edge vegetation, gravel, sand and mud habitats. We empty the sample into large, deep, white trays filled with clear water. We then get comfy and spend 15 minutes peering at the bugs in the tray, identifying them, and scoring them on a field sheet. We get a total score (all families found), number of families, and the average score per taxon or family. Just this information gets us a long way towards knowing how polluted the water is and how degraded the habitat has become.
We enter this info into a model called Mirai (macro invertebrate response assessment index) to get the present ecological state, or PES, of the site, which tells us how far from natural the site is. Say the PES is 80%, this means the water and habitat quality of the site is estimated to be about 20% off its natural pre-messy-human condition.
In SA, we summarise the PES of river sites into six categories, A to F, each representing a range of these percentages. An A category site is a pristine, beautiful, functioning thing, scoring between 88% and 100%, while an F category site has a PES of less than 30%, and is truly finished, for want of a better word.
When we head off to assess a river, we are usually a mob of scientists, and we assess the fish, the vegetation, the geomorphology, the flow and the water quality. It’s pretty cool. We combine each of our PES results into a single ecostatus category (also A to F) for that river site, and that’s a simple explanation of how river health is monitored.
And now you want to know what category most SA rivers are in, don’t ya. The department of water & sanitation monitors around 400 sites nationally each year in their river ecosystem monitoring programme. The 2021 invertebrate results for these sites, were: no A category rivers, 15% largely natural to good sites (B to B-C); 70% moderately to largely modified (C to C-D), and 15% seriously to critically modified (D, D-E and E). While this is not representative of the whole country’s rivers, it is a carefully selected set of sites, and 85% of them were in a moderately to critically degraded state. And what is being done about this? Monitoring clearly does not inform management.
In East London our inner city rivers (Buffalo, Nahoon, Quenera, and Ihlanza (“Turdy”) are, as we often hear, unhealthy to the point of making us sick. In terms of PES, these rivers hover between C and D to even D-E categories, depending on recent inflows and other variables.
In 2020, I sampled the Nahoon River near the Abbotsford causeway. The river was covered by a very retro-looking green carpet. Yep, water hyacinth. Below the causeway, in a trickle of flow, I collected a reasonable sample with plenty of bugs, many of which were scooped from the hyacinth’s vast floating root mass, and most of which were tough, low-scoring families. The total score was 84, and the PES for the river was 59.5% (a C-D).
More recently, since the hyacinth was momentarily cleared by high flows (flooding), I popped back the other evening to sample at the same spot. The river smelt like a wet dog, not a good sign. It got worse. In the stones habitat, I collected three bugs: one mozzie larva, one riffle bug, and one chironomid midge larva. Total Score: 8 — my worst sample in 20 years. I wanted to sob.
In its natural state, this river’s bugs would have scored up to 200. In the submerged grasses I scrummaged a few damselfly larvae, a crab, a few water boatmen and pygmy backswimmer bugs, a marsh treader, and probably the same riffle bug. Final total score for the site: 40. Now one cannot say much with one sample, but for that day, I estimate the Nahoon River bugs were 20-30% of their natural state and would be an E or F category. Critically modified: abandon hope all ye who enter.
Without a system shake-up, a lot more engineers in the mix, committed co-operative management action, massive and speedy funding for infrastructure upgrades — or even better, privatisation of wastewater treatment works — and creative solutions to pump station and sewer surcharges, I see only see a dark tunnel ... andiboni ukukhanya. My bucks are on the bugs.
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