Pollution, bacteria testing taking place in Knysna Estuary

2019-05-21 13:21
SANParks rangers take samples in the deep channels of the Knysna estuary. (SANParks)

SANParks rangers take samples in the deep channels of the Knysna estuary. (SANParks)

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Regular pollution and bacteria testing has revealed a concentrated presence of E. coli bacteria in the Knysna Estuary, a SANParks spokesperson says.

According to SANParks, the bacteria has been found in high concentrations in specific areas.

"Areas that have shown constant high E. coli include the Bongani and Ashmead channels. The intervention is to understand the system, hence the Knysna Basin Project's effort to survey the tributaries flowing into the Knysna Estuary to try and probe sources of pollution as one aspect of the study," Nandi Mgwadlamba SANParks regional communications manager for the Garden Route National Park told News24 on Tuesday.

The Knysna Estuary is the largest tidal water exchange in South Africa and, while that gives it the ability to dilute effluent, the scale of the industrial development is beginning to have a negative effect.

Agencies including SANParks, the Garden Route District Municipality, the Knysna Municipality, and the Breede-Gouritz Catchment Management Agency have worked to address the problem.

E. coli levels have dropped in most of the areas except for the Ashmead and Thesen Island inlet, according to SANParks.

Mgwadlamba said authorities were planning a workshop to focus on the industrial area.

Oil and grease pollution

SANParks data also showed a decline in oil and grease pollution which affected the Waste Water Treatment Works (WWTW) as a result of the introduction of oil-eating bacteria.

"Letters requesting restaurants to provide proof of their oil and fat disposal mechanisms were completed. Recent oil and grease tests show a drastic decrease in levels at the municipality's WWTW. The municipality also removed residual oil and grease in sumps. This has brought on a subsequent recovery of the WWTW so that its functioning has improved," SANPArks said in a statement.

The Ashmead Channel is home to the Leisure Island Boat Club, but SANParks said that it was "not safe for use for swimming, bait collection, fishing or wading at present".

E. coli levels have dropped in most of the areas except for the Ashmead and Thesen Island inlet, according to SANParks.

"The latest samples of estuary water quality, taken by Garden Route District Municipality indicate that the Ashmead Channel, Bongani, Bigai, Long Street, Station culvert and the Knysna Angling Association (KADA) culverts are non-compliant, with E.coli readings above the Department of Water Affairs acceptable limits for recreational use."

The pollution in the estuary can have a detrimental impact on human consumption as well.

"Pollution is harmful to plant and animal life. If for example, if a fish swallows pollution and someone catches it later, that can affect the eater of that fish. Similarly, it can affect other fish eaters, seals and birds. Here we see how inter-connected humans are to animals, plants, the sea, the environment," said Mgwadlamba.

Knysna Waste Water Treatment Works is seen.

Knysna Waste Water Treatment Works is seen. (SANParks)

'Increased pollution levels'

Pollution levels in the estuary are not new.

A 2007, a CapeNature report compiled by Coastal and Environmental Services found that the Knysna Oyster Company had very low stocking densities for oysters it farmed in the Knysna estuary.

"The main reason for this is that the survival rate of oysters has dropped dramatically over the last four years from 55% to 20%," read the report.

"The company believes this is largely due to increased pollution levels in the lagoon. This is supported by the extremely high arsenic levels that were detected in tests after a heavy mortality event last year; both SANParks and the Knysna Municipality were furnished with the test results," the report added.

The Knysna Municipality in 2014 sponsored a clean-up of the Bongani river which flows into the estuary. As part of the River Health Programme, 30 women cleaned the river on a weekly basis.

According to the SANParks Garden Route National Park Knysna Coastal Area State Of Knowledge report, the potential for pollution in the estuary is high because of 111 drainage pipes discharging water from residential and industrial areas.

According to SANParks, the Knysna municipality will be given an opportunity to provide further action plans to rectify the situation in the estuary.

SANParks will also conduct regular water sampling in order to keep track of the extent of the pollution.

"If the pollution ends up killing plants and animals, we lose out on species. Current and future generations might never know them as they might go extinct if they die in large numbers. Pollution is a killer, whichever way you look at it," said Mgwadlamba.

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