Managing the Groot River Estuary

Mark Brown
24 June 2016
Managing the Groot River Estuary

As most of you know, the Groot River Estuary in Nature's Valley is what is called a natural open/closed system. Essentially this means the mouth of the estuary opens and closes naturally as part of it's annual cycle, and that the biodiversity within the system is used to these cycles. In an ideal world, the system would remain natural and man would not have to intervene. 

In some coastal areas though, including Nature's Valley, development of housing has meant that natural systems occasionally need to be managed. In our case, there are a few conservancy tanks along Lagoon Drive that could under certain conditions potentially get flooded before the mouth naturally opens, leading to unwanted and dangerous pollution of the estuary. There are a few instances where this has happened in the valley, resulting in high E. coli levels and unwanted illness in swimmers. The ecological consequences can also be devastating. This means that the water levels in the estuary need to be carefully monitored and the mouth breached artificially if it gets too high.

Estuaries in South Africa fall under the legal management of the Department of Environmental Affairs, who have strict regulations about when and how a mouth is breached, and who can breach it. This means that even though SANParks manage the Garden Route National Park, they need to get national permission to do the breach. The public are NOT allowed to conduct breaches, and can face heavy fines for attempting to do so. 

Public breach

Unaware of the repercussions of their actions, these members of the public were found trying to "help" nature.

This family visiting the Valley this past weekend were spotted trying to "help" nature, and were asked to please refrain from doing so. They did not know it was illegal to do this, or that there were hefty fines they could face if caught by the authorities - thanks to quick thinking NVT staff who spotted this and educated the group.

There is a couple of water level meters around the Estuary that SANParks uses to monitor when and how the mouth should be breached. A management committee for the Estuary is in place, which includes NVT staff, and we work together with SANParks to ensure the estuary is given the best opportunity to breach naturally, or to be breached manually if it gets too high and threatens the conservancy tanks. Not everyone agrees with this approach, and some feel the mouth should be breached earlier than when it sometimes is - but in essence the duty of SANParks is to manage the system in as natural a way as possible, and intervene only when it is necessary. NVT agrees with this approach. Our research over the last few years has highlighted this estuary as critically important for several line fish species, most notably Cape Stumpnose and White Steenbras, which are two of the top five species caught by shore-based anglers in the area. It is the pristine nature of the Groot River Estuary that enables these species to safely use it as an important nursery ground. This provides the young fish have a safe environment to grow up in, and ensures fish stocks are available for anglers in future.

In practice, the mouth is artificially breached a few times a year on average, and is either done with the help of a TLB, or manually by dedicated ranger crews with spades. After careful monitoring, and realising the natural conditions were not going to allow a natural breach before dangerous levels were reached, SANParks took the decision on Monday afternoon to breach the mouth. Marco Barnardo led his ranger team in the action, and managed to successfully complete the breach on the same day.

breach1

The SANParks ranger team preparing a manual breach.

The exact timing and location of the breach is important, and we commend SANParks for their action on Monday which ensured no conservancy tanks got flooded. We commit to continue to work closely with them to ensure the best management of the Estuary is in place, and that the amazing biodiversity of the estuary and it's important ecological function can be maintained as naturally as possible. Exciting news is that the management committee are working on the development of a full blown Estuary Management Plan for the estuary, and NVT will be fully involved in the process. Together, we can ensure generations to come enjoy this magnificent estuary!

Flowing strong

Well done SANParks!

 

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