In early February, AfriForum, together with several other organisations, businesses and community members, removed more than 1 623 tonnes of water lettuce from the Vaal River. Photo: AfriForum
The government has halted the “spraying of a sub-lethal chemical”, glyphosate, to combat the invasive alien water lettuce clogging parts of the sewage-polluted Vaal River.
In a joint statement Forestry, Fisheries and the Environment Minister Barbara Creecy and Water and Sanitation Minister Senzo Mchunu noted “public concerns” over Rand Water’s use of the herbicide.
“Following the complaints in the public domain, the two ministers and other relevant parties met and agreed to determine whether the clearing methods followed were in line with the regulatory environment and to devise a plan that ensures that the clearing of the alien invasive plants is done in a manner that poses no harm to the environment,” read the statement.
The ministers said their departments would then issue a further statement on what steps would be taken to clear the plants.
But water governance expert Carin Bosman said that the “botched” and “criminal” handling of water lettuce in the Vaal River using herbicides containing glyphosate was a case of “entitlement and hubris” meeting “incompetence”, causing “unintended consequences such as harm to human health and damage to ecosystems”.
Concerned citizens of the Vaal River had obtained permission from Rand Water to spray glyphosate in a sub-lethal dose, using crop dusters and drones, on 14 February.
“Rand Water claims that they received approval from the department of forestry, fisheries and the environment (DFFE), who in turn says that the spraying of glyphosate on the Vaal River is ‘approved under a General Authorisation’, from the department of water and sanitation (DWS).”
But the general authorisation issued by the DWS explicitly prohibits the use of hazardous substances in water without a water use licence issued under the National Water Act, she said.
“The DFFE has no mandate to issue any ‘approvals’ in this regard, and furthermore, under the Fertilisers, Farm Feeds, Agricultural Remedies and Stock Remedies Act 36 of 1947, glyphosate is not approved for use on water lettuce or in water resources.”
It is a criminal offence to dispose of a substance such as glyphosate in water without a water use licence under the National Water Act, she said. The off-label use of a herbicide such as glyphosate is also a criminal offence under the Act.
Sewage contamination
The Vaal River has high nutrients: phosphates and nitrates. “The reason is that not everybody in the Vaal Triangle has formalised sanitation so we have informal sanitation and [their] waste goes into stormwater and into the river because that’s where the stormwater goes.”
The municipal sewage infrastructure of Emfuleni, Vereeniging, Vanderbijlpark and Sebokeng is under stress. “There is a problem with properly treating the sewage with the result that the Vaal River is high in nutrients, in addition to the sludges and everything else. If you have high nutrients in water then you will get eutrophication, which means there’s so much high levels of nutrients that algae and plants grow spectacularly in and on the water.”
Water lettuce is a perennial, mat-forming, free-floating aquatic plant, native to South America, which grows in humid climates because of eutrophication and has a lifespan of about two to four weeks. As the floating mats cover the water surface, it creates a problem for boats, makes fishing more difficult, affecting recreational activities and tourism and can also clog pipes. But, “it does not have a significant detrimental effect on other aquatic life, or other uses of the water resource in the short term.”
Glyphosate hazards
Rand Water said the herbicide spray would be done in accordance with the approved general authorisation from the DWS and with technical information from the DFFE. It had embarked on an integrated approach to manage the water lettuce infestation, including physical removal, biocontrol and chemical application.
Experts, it said, had agreed “that this type of approach is most suitable at present”. The application of all herbicides was approved by both departments and they are “set at a sub-lethal dose because we are implementing an integrated approach”.
Bosman said that glyphosate is a broad-spectrum systemic herbicide and crop desiccant. It is an organophosphate, used on land to kill weeds and grasses that compete with crops but is prohibited for use in water as it is toxic to aquatic organisms.
“Glyphosate is extremely soluble in water, and it can persist for up to 170 days in low-light conditions and over 300 days in dark conditions, such as would be found under mats of water lettuce. When glyphosate enters water resources, it remains there for significant amounts of time. Furthermore, the application of a herbicide in sub-lethal concentrations will simply increase the resistance of the plant to the herbicide.”
It poses a significant risk to humans. The International Agency for Research on Cancer categorises glyphosate as a probable carcinogen. “It may cause a higher risk of liver and kidney damage and studies indicate that glyphosate causes developmental effects, including reduced infant body weight and skeletal changes.”
“Now, 20km downstream from where this is happening [the chemical spray], the Parys municipality abstracts water to treat for drinking purposes if they are not supplied by Rand Water. Then the next town down is Klerksdorp and the Midvaal Water Company abstracts water from the Vaal River to treat for human consumption for Klerksdorp, Orkney, Stilfontein and Hartbeesfontein,” said Bosman.
None of those water purification works are designed to remove organophosphates, she added.
‘Big stink’
The “big stink” over the infestation of water lettuce in the Vaal River, she said, was driven by wealthy people living on Millionaires Bend, who “couldn’t take tourists on their boats on the river to go and watch the sunset” because the weed interfered with their propellers.
“And that’s where they then started making petitions and putting pressure on the government to do something because it’s a ‘crisis’. They were not thinking for one second about the poor people who use this river for sustained subsistence fishing and the drinking water that’s abstracted downstream to give people to drink who cannot afford to buy bottled water.”
Water lettuce is much closer to the water; it’s not a big plant so the chances of the glyphosate getting washed off and just running off into the water is so much greater; it will,” said Bill Harding, a limnologist with a special and long-term interest in eutrophication and cyanobacteria.
Using glyphosate on any aquatic plant doesn’t work that well, he explained. “You end up with a whole lot of sick-looking plants; in some cases, if you get a really good dose on it, you’ll kill it. But it’s not really effective and it’s dangerous. It’s presumably carcinogenic and that the DFFE would even consider spraying it in a water supply is shocking in itself.”
But it’s not the first instance where glyphosate has been sprayed in waterways. “They allow it all the time and they are using other things too. There’s another one [herbicide] called acrolein, which they [DWS] use, which is also presumed carcinogenic …
“They’re allowing that on some dams [for the control of algae, fungi and submerged aquatic weeds in their canals] sort of out of the public eye … It’s not just the herbicides, they’ve been adding chemicals to try and control algal blooms without any testing … The water is a drinking water supply eventually,” he said.
This is “all putting lipstick on a pig”, Harding said, describing how the herbicide spray on the Vaal River appears to “make the problem go away and to give us a couple of months of breathing space … Yes, you’re killing the weed but you’re killing a whole lot of other stuff in the water bodies that you can’t see. You’re upsetting that whole ecosystem [Vaal River] and the system is already stressed so every time you hit them with this, it gets weaker.”
All these interventions avoid the real problem. “The problem is wastewater that needs to be treated to appropriate levels.”
The two departments referred the Mail & Guardian to the ministers’ statement and said further communication “would be issued as soon as the process indicated is done”.
*This story has been updated