Disaster heading towards the Orange river?

Vaal River Rats SA today reported that hyacinth and water lettuce have been spotted down river.

In a Facebook post the organisation said there are confirmed reports that the water lettuce has made its way down to Parys.

Over 400 weevils were released in the Vaal River on Thursday, 15 February, to halt the growth of water lettuce (Pistia Stratiotes), which has become a crisis.  Water lettuce is a poisonous and highly invasive free-floating freshwater weed found in water bodies and slow-moving waterways in warm regions. It was first seen in SA in the Suikerbosrivier in 2021.

According to Prof. Julie Coetzee from the Rhodes Centre for Biological Control, these insects can effectively control this floating invasive species. Positive feedback is that weevils which were originally released in the Leeuspruit a few years ago, are breeding well there and have caused damage to much of the water lettuce there.

Although water lettuce and water hyacinths are different species, both produce thousands of seeds that remain viable in the sediment for years, she said.

When releasing the weevils and hoppers last week, Dr Leslie Hoy, Manager of Environmental Services at Rand Water, discussed the integrated approach to managing water lettuce and hyacinth on the Vaal, including physical removal, biocontrol, and chemical application.

Professional crop sprayers and drone operators sprayed the herbicide glyphosate on the Vaal for the first time last week after Rand Water earlier said the Department of Forestry, Fisheries and the Environment, and the Department of Water and Sanitation South Africa had approved the application of all herbicides used on the project, “set at a sub-lethal dose.”

According to Rand Water, the sub-lethal dose increases the sugar and carbohydrate contents of the Pontederia Crassipes plant, making it more palatable for the biocontrol agent.

Spraying glyphosate has however since sparked widespread reaction. Complaints in the public domain led to a joint statement on Saturday by the Ministers of Forestry, Fisheries and the Environment, Ms Barbara Creecy, and Water and Sanitation, Mr Senzo Mchunu, saying all relevant parties have agreed to determine whether the clearing methods followed, were in line with the regulatory environment.

It was said that the departments will now devise a future plan that ensures that the clearing of the alien invasive plants is done in a manner that poses no harm to the environment.

Once that process is concluded, the Departments will issue a further statement on the way forward.

Yet, no one says much about how government and municipalities address the root of the water lettuce crisis – the constant sewage spillage into the Vaal.

Prof. Anthony Turton’s earlier warning that no eutrophic system in SA has ever been effectively rehalitated should not go unnoticed. He explained that a eutrophic system has high levels of nutrients, typically phosphate and nitrate, usually associated with sewage return flows.

“We are polluting our drinking water systems with untreated sewage, with major economic and social consequences over time,” Turton said.

He added that the consumer would bear the brunt of making this water safe for human consumption. The logical solution was to stop polluting our rivers with untreated sewage. As long as we fail to do this, we fight a losing battle against the stranglehold of invasive plants on the Vaal.

The Emfuleni Local Municipality (Evaton, Sebokeng, Vaal Oewer, Vanderbijlpark and Vereeniging) is one of the municipalities previously warned to stop dumping sewage into the river. Over the weekend, a concerned citizen was quoted on Vaal River Rats SA’s Facebook page, saying the sewage works south of Soweto had pumped raw sewerage into the Klip River for years. This river flows into the Vaal at Vereening.

The Department of Water and Sanitation, as custodian of the national water resources, is responsible for ensuring that we protect our water resources. With the alarming condition of numerous municipal sewage plants, people have begged for stricter action against those responsible for pollution for a long time.

The excessive growth of invasive plants like water lettuce and hyacinth in the Vaal River could lead to a series of ecological problems, including suffocating other aquatic plants and negatively affecting the viability of other aquatic animals. It could also clog water pumps on the river bank and cause damage to farming equipment.

For the past weeks, community members and organisations have been using their resources and time to manually remove the water lettuce,

Over the weekend Vaal River Rats SA reported a big water lettuce carpet building up at the Barrage wall, with patches of hyacinth emerging in between. The organisation asked Rand Water for urgent assistance in cleaning in front of the Barrage.

“This is the whole country’s crisis; we do not understand the calamity coming our waym” Andrew Surtees of the Vaal River Rats SA said. The organisation on Tuesday warned that the 40km aquatic weed problem in part of the Vaal River Barrage Reservoir could become a 1 000km plus problem if the aquatic weed proliferation is not addressed urgently and it moves down river past the Barrage. “The environmental, social, economic and water extraction damage will significantly dwarf the current 40km problem.”

As part of the general authorisation, physical removal is still permitted. “Rand Water asked our river community to notify them when we plan to remove so they can have a representative on site,” Vaal River Rats SA said.