The organic clean-up of the largest freshwater lake in the Nelson Mandela Bay region is yielding positive results, with the water body set to be “swimmer-ready” during the course of this year.
In the past pollution levels North End Lake have made it unsuitable for swimming events where participants come into direct contact with contaminants. However water quality test results from the lake following bioremediation reveal a marked improvement in various critical parameters.
According to Rhino Water director Sarel Bam, whose company was appointed to conduct the organic clean-up of the lake, the toxic blue-green algae, faecal coliforms and E. coli levels dropped substantially between January and March.
The downward trend was significant, said Bam, and a clear indication that the North End Lake’s bioremediation was taking effect in spite of a continued influx of toxins and other pollutants into the lake. He added that anecdotal evidence such as a marked increase in the number of young fish, or fingerlings, also suggested an improvement.
The most recent test results from the North End Lake – taken since the bioremediation of the water body began last November – reveal that inorganic materials such as dissolved metals and minerals now meet the national SANS 241 specifications for drinking water. Algae and bacterial levels have also dropped significantly, although still remain above the acceptable standards for recreational use.
Pollutant sludge levels on the floor of the North End Lake have also decreased by up to 20cm, from depths of around 80cm, since the first phase of the project commenced. The second phase of the project which started on 6 January this year will continue until the end of June.
“Based on the data we have, we are on the right track,” said Bam. “Algae levels have improved substantially, while bacterial forms such as E. coli, faecal coliforms and Enterococci have also improved, but are not yet where we would like them to be.”
DWAF guidelines state that E. coli and faecal coliform colonies should be fewer than 130 per 100ml, while toxic blue-green algae levels should be less than six blue-green units per millilitre.
“Some members of the public have also commented on improved water clarity, but this will change as the sludge continues to lift. We’re looking at ways to expedite the process and have the North End Lake remediated in the coming months.”
The bioremediation process has involved dosing the lake with an imported proprietary product containing natural bacteria and co-enzymes to effectively lift and digest sludge from the bottom of the lake and remediate the water.
“Our dosing regime currently involves spraying 3 400 litres of product into the lake on a weekly basis,” said Bam.
Gabions built by consulting engineers Africoast at various water entry points have also helped to contain the inflow of solid waste such as plastic bags. This two-part process was envisaged to work together to enable the holistic remediation of the water body.
Creating a world-class water sports location
The clean-up has been rolling out under the watchful eye of stadium operator Access Leisure and Facilities Management. According to its chief executive Chantal du Pisani, the progress was the result of the good work carried out between the partners.
“The vision has always been to establish a world-class water sports location, adjacent to the world class sport fields that we have in the Nelson Mandela Bay Stadium. This will provide a unique setting for all kinds of sporting and leisure activities. But the key to this is a safe, clean and well-maintained North End Lake.
“The rejuvenation of the North End Lake precinct is critical for this process, with the hope that the lake will be ready for full open water contact toward the end of the year,” said Du Pisani. “We’ve had phenomenal support for this process from all our partners, and we are extremely pleased with these interim results.”