Last month, water samples taken in the estuary showed improvement after signage was erected warning recreational users not to fish, collect bait or swim there due to contamination and high levels of E coli.
The Knysna municipality confirmed there was chemical contamination at its wastewater treatment works (WWTW) dating as far back as February 4, and acknowledged it was a cause for concern.
Yesterday, SANParks said at the Ashmead channel E coli counts were still high, although down from the last sample taken on April 3, a current 1 200cfu/100ml from 2 160cfu/100ml.
“Cfu” stands for “colony-forming unit”, an estimate of viable bacteria or fungal cells in a single sample. Results are reported as cfu/milliliter for liquids.
The Bongani stream is still over the limit at 3 200cfu/100ml and higher than the previous sample of 2 100.
The Queens Street outlet has shown a drop to 13cfu/100ml after a number of consecutive readings of over 30 000cfu/100ml.
Salt River is also non-compliant at 970cfu/100ml.
The Department of Water and Sanitation guidelines for recreation stipulate the acceptable level of Ecoli bacteria must be lower than the 500cfu/100ml mark. The entire Ashmead channel up until the north-eastern side of Costa Sarda is still not safe to wade, fish or swim in.
“All other recreational sites in the estuary are compliant and satisfactory. These include deep water channels sampled by SANParks,” Knysna Park manager Megan Taplin said.
Municipal health services of the Garden Route District Municipality will take water samples at non-compliant sites of concern weekly, in addition to their regular monthly 14-point sampling protocol.
The authorities pollution committee comprising SANParks, the Knysna municipality, the municipality’s health division and the Breede-Gouritz Catchment Management Agency continue to monitor the Knysna estuary’s pollution levels.
The municipality has attributed the incident to a presence of oil and grease at the WWTW which kills good bacteria. An oil-eating enzyme was then introduced to target the pollution as well as useful bacteria from other WWTW plants before the effluent is released. The municipality reported the continuation of oil pollution in the WWTW.
“The Garden Route District Municipality has issued letters to all businesses alongside the estuary requesting an explanation of how businesses are disposing of fats and oil stores as an attempt to identify polluters.
"The Knysna municipality, along with the district, is still investigating the sumps and channels leading to various areas to narrow down the source of oil pollution,” SANParks said.