Holidaymakers flocked to the ever popular Onrus beach and lagoon (estuary) over the festive season, the question of pollution again reared its head and led to some confusion about the possible health risks posed by swimming in the estuary.

Onrus Estuary in summerWater samples are routinely taken by the Environmental Services Department of the
Overstrand Municipality (OM) from all the estuaries in the Overstrand, including Onrus,
and tested by an accredited laboratory for E.Coli and enterococci, two accepted indicators of possible faecal pollution. Signage was erected at the Onrus Estuary by the Municipality prior to the season that indicates the current levels of enterococci.

The Onrus River Estuary Forum (OREF)

‘Swimming at own risk’ was, and remains, the general message, but most beach revellers were uncertain about what this all means and how safe the water is for swimming.
Concerns about the water quality of the Onrus estuary have been an ongoing issue over the years and is now being tackled head-on by the Onrus River Estuary Forum (OREF).

Formed in October last year to allow civil society organisations to participate in the
implementation of the Onrus River Estuary Management Plan, OREF has engaged with
government agencies to manage the pollution problem as a top priority.

Onrus Estuary warningShaped under the auspices of the OM, in accordance with the National Integrated Coastal Management Act, the OREF is chaired by retired water engineer Peter van Niekerk with Paul de Villiers as vice chair.

Also on the committee is Rob Fryer, General Manager of Whale Coast Conservation (WCC), who erected an information notice at the estuary just before the start of the holiday season. The sign had a QR code link to a website page that could be accessed by the public. The website page gives a simple explanation of the meaning of the bacteriological data and the current status of the water quality and associated health risks.

“Unfortunately municipal officials had the notice removed because prior permission
hadn’t been given for it to be displayed,” says Rob. “An official application has been made to display the notice and it is hoped that the required authorisation will be given quickly.”

Estuary findings

According to Rob, WCC analysed the bacteriological data from water samples taken by the OM and analysed by a Merieux NutriSciences (Swift) laboratory. “The guidelines advocate using statistical methods to determine the overall recreational health of water,” says Rob. “For the water quality to be considered ‘good’, with an associated risk of gastrointestinal infection less than 5%, the enterococci level should be less than 200 cfu/100 ml.

“Using these guidelines, the Onrus Estuary is consistently rated as ‘poor’ (unsatisfactory)
and the risk of contracting gastrointestinal infections by using it recreationally is
greater than 8.5%. Over the season, the 90th percentile of enterococci from data taken
over 20 weeks has been 460 cfu/100ml, with individual sample test results being
much higher.”

Should the estuary be closed?

Several opinions recently expressed on social media platforms criticised the OM for
not closing the estuary for recreational use over the season. There were also unconfirmed
reports of children getting sick with gastrointestinal tract infections after swimming in the lagoon.

While Rob agrees that the water is polluted and that the public should be aware of the
high health risk of swimming in the estuary due to bacterial contamination, he also points
out that the responsibility for closing the estuary to the public does not lie with the
local OM.

“Where the pollution levels exceed safe limits, such as in the Onrus estuary, the Overberg
District Municipality (ODM) is responsible for making the public aware of the health risks by erecting warning signs,” says Rob. “Only the ODM can take the decision to put up a ‘No Swimming’ sign.”

This illustrates one of the core issues that OREF wants to address in the coming months:
while the Onrus estuary, and all other estuaries within the Overstrand, falls wholly within
the boundaries of the local OM, there is currently no government management
authority actively coordinating estuary management activities.

“That is why the OREF was established by representatives from civil society organisations
as a formally constituted NGO and will play a pivotal role in aiding the coordination
of government agencies responsible for the various estuarine management activities
and to monitor the implementation of EMP,” says Rob.

Pollution origin

So where is the pollution coming from and whose responsibility is it to rectify the
matter? “There are many potential sources of pollution, some of which are under the
control of the OM,” says Rob. “The OM has addressed a major part of the likely
sources of contamination, including the so-called Kidbrooke sewage pipeline and
private septic tanks of properties close to the estuary. As far as we know, there have been
no sewage system failures this season that has led to spillages, but OREF has requested
that a formal HAZOP (Hazard & Operability) study be carried out to determine the vulnerability to sewage spills when all pumps are incapacitated during failures. The results will determine what action is required to address this issue.”

The chairperson of OREF, Peter van Niekerk, emphasises that more research needs to be
done in order to pinpoint possible sources of pollution. “The OM has been very supportive
and inspection of the septic tanks in the residential area around the estuary has already been carried out, with several being upgraded. The OM has also undertaken to expand
the area of inspections. “This is, however, a complex issue and there are many factors
that have to be taken into account, including long-term temperature and rainfall data. A
proper, scientific study needs to be commissioned to identify the causes of the high
enterococci test results.”

Property owner input

Rob adds that property owners should have their septic tanks pumped out regularly, as overfull tanks are a prime suspect source of bacterial contamination, which is why OREF will be suggesting to the OM that mandatory pumping of septic tanks is implemented on a
regular basis. The other concerns of the OREF relate to sorting out the protocol for
dealing with information about the recreational water quality and deciding on whether or
not to close the estuary to swimming.

The OREF leadership and senior representatives of the local Overstrand and Overberg District Municipalities, the Breede- Gouritz Catchment Management Agency, Department of
Environmental Affairs and Development Planning and the Department of Agriculture are meeting on 19 January to work out a plan to address these issues. The OREF leadership has presented a proposal to the officials on what it believes needs to be considered as
priorities for the government agencies to tackle.

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