Causes of fish die-off and stench at Jeffreys Bay’s Seekoei Estuary still a mystery
Residents claim the dead fish and continued stench at the Seekoei Estuary is a result of a wastewater treatment works pumping raw sewage into the Swart River – one of the two rivers that meet at the estuary.
Jeffreys Bay residents are calling for urgent action from the Kouga municipality following the death of fish and birds in the area and a terrible stench emanating from the Seekoei Estuary – allegedly because of wastewater treatment works pumping raw sewage into the Swart River.
According to Jeffreys Bay residents, the sewage pollution into the Swart River started in 2011. In 2014 the town lost its blue flag status.
Resident Freddie van Rooyen said the DA leadership in the municipality was the opposition when it complained about pollution of the estuary in 2011.
“The spillages have been happening for years, I read and personally saw … but it got worse in 2018 … I started to investigate the spillages and in 2022 I started investigating the treatment plants.”
“The municipality should be transparent in terms of all their water sample results for at least the last six months … Private samples taken in the six months show high levels of E Coli,” he said.
He said in December 2021 the problem started affecting Aston Bay, another area of Jeffreys Bay. “The algae started rising rapidly and a terrible smell hung over Aston Bay.”
He said the municipality always blamed eutrophication, “which occurs when the environment becomes enriched with nutrients”, and heat and drought, which causes the algae to appear – but never mentioned the nutrients from their processing plant fed the algae to reproduce quickly.
Residents said they conducted their own water tests in the estuary and Swart River and registered very high counts of e.Coli, faecal coliforms and total coliforms over 12 months. The tests, they said, indicated that the E.coli count was above 115–2,419 CFU per 100ml, the total coliform count was 2,419 CFU per 100ml, while the faecal coliform count was above 2–205 CFU per 100ml.
The residents also carried out two tests at the outflow of the treated water to the Swart River, which showed E. coli above 1,500–15,000 CFU per 100ml and the Faecal Coliforms above 1,500–15,000 CFU per 100ml.
Van Rooyen said the municipality offered explanations of drought, high evaporation, rotten plants, fish dying from the salt quality. It then changed its story to low oxygen without offering proof of chemical oxygen demand (COD) tests or toxicity tests of the water, the type of algae, the type of toxic gases released by the algae or the chemicals used at the treatment plant and quantities.
Nahoon Estuary Management chairperson Christo Theart said he had visited the wastewater treatment works at Jeffreys Bay and could confirm that raw sewage was flowing into the Swart River, which joins the Seekoei River flowing into the Seekoei Estuary.
“Fish are dying,” he said. “The functioning of the estuary is also hampered by a causeway, which prevents the flow of water within the estuary as the culverts in the causeway are too small or too few.”
He said these issues had left the estuary in a very poor state. Residents had said that the situation had been dire for months but complaints to the Kouga municipality had fallen on deaf ears.
“In the SA 2021 municipal Green Drop Report’s score for wastewater treatment plants, Kouga municipality scored 19% . We could not enter the works, but from the outside it is clear that there are serious functional deficiencies. The plant is not fenced, it does not have a standby power plant,” Theart said.
Kouga municipality denied deliberately dumping raw sewage in the Seekoei Estuary.
“The Seekoei Estuary is no longer functioning naturally, due to anthropogenic (human) activities … altering the natural ecological function of the estuary. This has been exacerbated by extraction and irrigation dams situated higher up in the catchment area, the long drought experienced in the area and the effects of climate change, such as changes in temperature and frequency of precipitation events,” the municipality said.
It said it had erected the causeway in response to a request from the community.
“Studies show that since the late 1980s the estuary experienced mass mortality of fish that was attributed to drought and excess water extraction in the catchment areas.
“The ongoing drought and insufficient freshwater inflow into the estuary resulted in the low water depth and increased sediment accumulation within the estuary basin. Further to this, the municipality had to artificially breach the Seekoei Estuary mouth, under the approval of Department of Economic Development, Environmental Affairs and Tourism, to reduce over-wash of the causeway, damage to vehicles and infrastructure. These artificial opening events lead to ineffective scouring of sediments from the estuary and are below the natural mouth breaching level of +2.0 to +2.5 m MSL (Mean Sea Level) for the Seekoei,” the municipality said.
According to the municipality, hyper-salinity in the estuary was because of high temperatures and evaporation rates, which increased during warmer seasons.
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“Concomitantly, in February and March we also have very high water temperatures. Plant growth in the shallow water is also high and because plants produce oxygen during the day, levels of oxygen deplete after dark. All of this leads to declining water quality, exacerbated by rotting aquatic vegetation. The situation gets worse as hydrogen sulphide builds up in the sediments and causes invertebrate die-off,” the municipality added.
The municipality said the stench from rotting organic matter then manifested itself as poor air quality around the estuary.
“From inspection and looking at the photos taken of dead fish, most of the fish are juveniles … During the [estuary] mouth open phase that lasted a few months beginning last spring, recruitment of small fish was good. The lesson here is that these small fish spawn in the nearshore environment and enter estuaries deliberately … this estuarine phase of their life cycle is obligatory.”
“Many small fish washed over the sand berm at high tide recently … These small fish are then probably shocked by the water quality issues in the estuary – no acclimation period that might give them a better chance … As we move into winter, current problems will probably abate,” the municipality said.
It said its own investigations showed that the current issues at the estuary resulted from the conditions listed above.
“We are in consultation with professionals from Nelson Mandela University who are investigating and implementing short-term solutions … A review of the estuary management plan will be done for medium and long term solutions.” DM/OBP
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