The hard task of maintaining acceptable E.coli levels
KNYSNA - The battle against high levels of E.coli in the culverts that feed into the Knysna Estuary seems to be never-ending. In the latest estuary water quality update published by Knysna Municipality, six of the seven culvert points where water samples are taken well exceeded the national limit for recreational use.
According to the national Department of Water Affairs' guidelines for recreational water usage in coastal marine waters, water quality for recreational use may not exceed 500 E.coli coliforming units (cfu)/100ml.
The culvert culprits
The biggest culprit was the Queen Street culvert where 18 100 units of E.coli per 100ml was recorded - more than 36 times the target. Next was the Long Street culvert with 10 400/100ml, followed by the train station culvert (8 300/100ml), Bongani (5 900/100ml), Knysna Angling and Diving Association (2 300/100ml), and finally Bigai (920/100ml). Only the Ashmead culvert was compliant and indicated no growth.
The seven culverts are tested monthly by the Garden Route District Municipality (GRDM), along with seven recreation points around the Knysna Estuary. According to GRDM chief communications officer Herman Pieters, monthly sampling of the 14 sites started in 2009, and in 2018 Knysna Municipality began publishing the results on its website.
"These sites were collaboratively selected by all the vested role players involved in the monitoring and managing of the estuary and land-based water/sanitation infrastructure," Pieters explained. The role players are GRDM, Knysna Municipality, and the custodians of the estuary, Garden Route National Park's Knysna Lakes Section (SANParks). They remain concerned about the pollution in the estuary.
SANParks, Knysna Municipality, and the estuary
"SANParks is designated as the management authority for the Knysna Estuary and our core mandate is biodiversity conservation," said Knysna Lakes section manager Megan Taplin. "We need to monitor and permit all activities on or affecting the estuary. SANParks does not manage the infrastructure and catchments which have an effect on the estuary and therefore needs to work with the municipalities to find ways of mitigating or stopping any pollution sources."
This is where Knysna Municipality comes into play, as it is responsible for all the municipal outlets into the estuary. According to municipal spokesperson Christopher Bezuidenhoudt, they have put measures in place to reduce the amount of pollution that reaches the estuary. "The municipality assists where requested with the erection of netting in major storm water culverts to capture litter that is washed down the storm water culverts. SANParks assist with the clearing of these culverts," he explained. "The municipality has a river health programme which clears the litter at the source of each major stream that flows into the estuary."
Sewage infrastructure
The culverts flowing into the estuary are not sewage infrastructure that empty directly into the estuary. "No sewage infrastructure drains directly into the estuary except for the outlet from the Waste Water Treatment Works (WWTW) after the sewage has been treated," Taplin said.
"However, untreated sewage can enter the estuary when there are illegal connections to storm water channels, when sewage manholes or pipes are blocked (then sewage runs into storm water drains or natural drainage channels) and from people using areas next to or draining into the estuary when going to the toilet."
Combative measures
Bezuidenhoudt said the municipality actively attends to sewerage blockages when they occur, and that it is implementing preventative measures and monitoring sewerage hotspots daily. It is also increasing capacity of the WWTW, with a rehabilitation plan for the Bongani Stream, a major contributor of litter and pollution into the estuary, in the pipeline. "This rehabilitation plan has been approved by the Department of Water and Sanitation. We await approval from the Department of Environmental, Forestry and Fisheries before we can commence with rehabilitation," Bezuidenhoudt said.
All three parties seem to be working together to combat the problem, and all are active members of the Authorities Pollution Committee that meets to address pollution issues. Actions carried out by the committee "include investigating sources of contamination systematically, sampling and monitoring and engaging in joint public education campaigns", according to Taplin.