Several Durban rivers are polluted with health-threatening levels of E.coli (sewage) - sometimes at levels hundreds of times over the recommended safety limits for drinking, washing, swimming or canoeing.
The eThekwini Municipality has been singled out as one of the "most significant" polluters of some rivers because of the failure to repair burst sewer lines and poor management at some waste-water treatment plants.
These are some of the findings of the latest river monitoring project conducted by Pietermaritzburg-based river scientist Mark Graham, on behalf of the municipality.
His report describes some of the worst-affected rivers as little more than "open sewers". Apart from the real possibility of gastro-intestinal sicknesses such as "Dusi guts", his report also points to the potential for spreading more serious water-borne diseases, including hepatitis, typhoid and dysentery. In the lower reaches of the Mbokodweni River, south of Durban, there were reports of children developing welts and sores on their skin from playing in highly polluted water.
Where the Mlazi River flows into the concrete Umlaas Canal section, he found "geysers" of raw sewage bubbling up from the bottom and test samples showed readings of 280 000 counts of E.coli/100ml of water during his latest 2007 survey.
Graham reported similar high readings of E.coli to authorities during the 2006 survey, but it appeared that "little had been done" to fix the problem.
In the Isipingo River, E.Coli concentrations of 440 000 counts/100ml were recorded in the latest survey.
Graham said E.coli levels of 1 000/100ml were sufficient to induce Dusi guts, while the South African guideline for acceptable recreational contact was set at 130/100ml.
"The question has to be asked: How many of these discharges (of raw sewage) occur daily within the eThekwini Metro and outside of chance observance by a survey team?" Graham said, noting that "the eThekwini Municipality is largely responsible for the current poor condition of many rivers".
He also raises a red flag about such poor water flowing into the sea, particularly for international tourism, as E.coli could compromise the "blue flag" status of beaches.
Graham's report follows disclosures in yesterday's Mercury focusing on at least one significant leak from a broken sewer line, and reports that the organisers of the Dusi Canoe Marathon will consider calling off future events if E.coli levels are found to be too high. Many paddlers have come down with tummy bugs since the event.
Workers in Seaview said a broken sewer line above the Umhlatuzana River was still discharging sewage, nine months after the pipe became blocked solid with a hard, waxy substance.
Neil Macleod, head of water and sanitation in eThekwini, said his staff were still investigating the issue and he hoped to issue a statement soon.
However, initial inquiries showed that although the steel pipe had indeed been cut open by municipal contract staff last year, it was repaired and sealed with an epoxy/PVC patch.
An inspection in December showed that the repair on the damaged pipe was still intact, but it now appeared that the patch was either removed some time after December 28 or had burst open very recently because of a new blockage with the same substance which clogged the line last year.
Macleod said the hole would be shut with welded steel and a probe was under way to trace the source of the blockage, and other possible crimes.
Asked to comment on Graham's report, Macleod said he would need to study each incident in full, but noted that sewer blockages frequently happened in the same places because the sewer system was treated as a convenient rubbish disposal system by some.
"We are often called in to unblock the same sewer lines. Then we find anything from sheep heads, rocks, shoes and buckets, rags or newspapers dumped in these pipes."
"This is a process of education, to get people to realise that sewers are not rubbish dumps."
Even neighbourhoods such as Mount Edgecombe estate had incidents of toilet bowls overflowing because of high water pressure from illegal interconnections between stormwater and sewage systems.
Graham's report, which analyses 18 main rivers and smaller tributaries in eThekwini, concludes the worst polluted rivers include the Umbilo, Mgeni, Mbokodweni, Isipingo, Ohlanga, Piesang, Mlazi and Umhlatuzana rivers.
He singles out the Aller, a small river which flows through the New Germany area, as posing a "significant and unacceptable threat" to a nearby shack settlement and the lower reaches of the Mgeni/Blue Lagoon area.
It appeared that the Umbilo municipal waste water treatment works was having a "highly significant and negative impact" on the health of the Umbilo River.
It was "probably the biggest single point-source impact on the Umbilo. Little appears to have changed in this system for the last 10 years".
Parts of the Umkhumbane (near its confluence with the Umbilo) was home to rat-tailed maggots as well as "sewage/ blood worms".
These maggots have special "snorkels" to breathe and survive in the most highly polluted environments. Sewage worms are also specially adapted to surviving in very foul water.
The Umhlatuzana, Hammarsdale and Izimbokodweni waste-water works or pump stations were all especially problematic.