Background – a river once free to meander ….
Before the arrival of the railways in Fish Hoek in 1890 the lower reaches of the Silvermine River and its mouth moved periodically back and forth between its present position and the Fish Hoek railway station. The river was `free’ and moved according to the vagaries of weather, tides and the position of coastal dunes. A map of about 1785 (see Malcolm Cobern’s “Story of the Fish Hoek Valley”) shows it joining the Fish Hoek stream and flowing into the sea near the present `lighthouse’ at the end of the promenade.
There was no road bridge across the river until 1874 and the wagon road from Cape Town to Simon’s Town stopped just south of Clovelly, which was then known as Die Trappies. The wagons then made their way along the beach at low tide and rejoined the road at the southern side of the valley near the Homestead. Quicksand at the mouth of the river in which a horse was reported to have been lost in 1774 was a concern. Warning signs reading “Danger: Quicksand” stood at the mouth of the river until about 1990, being periodically replaced in new positions. One wonders if the previous signs had succumbed to their own warnings!
With the building of the railway line and construction of the rail bridge in 1890, it was necessary to curb the river’s wanderings. The first major attempt was made in 1900. It consisted of a dyke which stretched from the beach to near the wooden pedestrian “pipe bridge”. When the Kakapo ran aground on Kommetjie beach in 1900 some of its plates were used in an attempt to restrain the southward movement of the Silvermine Estuary. These can still be seen on the beach during certain conditions. Other relics of this era are the stumps of a wooden bridge constructed in 1903 to give access for a private railway line from Fish Hoek station to the quarry behind the present electricity sub-station on Clovelly Road, between the road and rail bridges.
The 1900 dyke was not entirely successful and in 1925 another was built between it and the river, reinforced with corrugated iron sheets. Pieces of these can still be found and the remains of portions of both dykes exist beneath the sand near the walkway on the south side of the wetlands. Perhaps, one day, sections may be excavated for visitors to see. In about 1928 redundant square metal rainwater tanks from Fish Hoek were used to reinforce the dyke on the beach and these together with the concrete-filled petrol drums of about the same period, are still to be seen. It is interesting that the next major effort to control the river commenced in 2000, exactly a century after construction of the first dyke.
As Fish Hoek developed, houses were built and roads constructed over the former flood plain, giving rise to a serious risk of flooding in the lower lying parts of Fish Hoek. Coupled with proposals for a large road interchange planned for the lower part of the river, control measures became increasingly necessary. The river was confined to a sand canal which was dredged periodically to reduce the risk of flooding in the lower lying areas of Fish Hoek.
Formation of the Silvermine River Society
The growing threat of canalization of the Silvermine River and development on the Skildergatskop Sand Dunes gave rise to a well attended public meeting in Fish Hoek in April 1985, under the auspices of the Cape Peninsula Conservation Trust. The meeting was chaired by Mr. Graeme Binckes, chairman of Captrust, and the speakers were Professor John and Mrs Grindley of U.C.T., and Mr. Tom Keane, the well-known Fish Hoek environmentalist. This meeting resulted in the formation of the Silvermine River Society.
The first committee consisted of Tom Keane, Ed Coombe, Eric Barnes, Sidney Seftel, Councillor H. Langley, Hannetjie Allen, Angus Burns with Lewis Walter as Chairman. Mr. John Wiley, Minister of Environment Affairs and Tourism, became President of the Society. He was a great supporter of the aims of the Society, and in a letter to a local resident, dated January 21st 1987, stated “under no circumstances should the stream be canalized…… the Silvermine Stream, being the last source to sea stream in the Peninsula, must at all costs be left undisturbed and you can rely on my support in this matter”. Sidney Seftel produced the logo of the Society – a representation of the Cape Platanna, Xenopus gilli, a rare and endangered species from the Silvermine River.
Activities of the Society initially concentrated on the control of alien vegetation which was prolific along the banks of the river. This was so successfully carried out that there was virtually no re-growth in the lower reaches. The Society also cleared aliens and planted indigenous trees in and around an area called `The Glade’ along the banks of the Silvermine River in the foothills of the Skildergatskop sand dunes. Many of these trees still remain. The Glade, shaded by gum trees is an ideal picnic spot and outdoor classroom.
The development of the Silvermine Trail was another Society project. It ran along the southern bank of the river from the mouth to the Sunbird Centre, to connect with the (then) Silvermine Nature Reserve. It was a very popular walk for a number of years, but the increasing presence of squatters eventually discouraged many people from using it.
A great deal of time and effort was spent in trying to persuade officials that there were better options for the lower river than canalization. In 1987, Kim Kruyshaar and Mike Silberbauer, on behalf of the Society, produced a document entitled “A case for the retention of the Silvermine River as a natural river system”. This was widely circulated, and possibly brought about the first change in official thinking as to the future of the river. Kim followed this up in 1990 with another document entitled “Silvermine River Wetland Project”. An enormous amount of study went into it, and it set out the basic outlines of what eventually became Phase 1 of the overall wetland project. The efforts of the Silvermine River Society and its members over a long period laid the foundations for the preservation of the river and the development of one of the most valuable assets of the Fish Hoek Valley.
Proposals for development of the wetlands had two main objectives: the need to control floods which would otherwise threaten developed areas of Fish Hoek, and the need to preserve the river as a natural and recreational amenity. Fortunately by this stage there were some far-thinking people on the staff of the City Council, and they realised that Kim’s proposals could indeed be worked on as a basis for the overall development of the Lower Silvermine River to serve both objectives.
By 1992, the Friends of Silvermine Nature Area (FOSNA) had been formed, and was becoming increasingly influential. It gave a great deal of support and advice to the Silvermine River Society, and it was decided to pool resources to best serve the interests of the river and its catchment. The S.R.S. had served its purpose by keeping alive public awareness of the threats to the river and the sand dunes, monitoring all official procedures, and ensuring that no steps were taken which would adversely affect either. It was absorbed into FOSNA in 1995 and a sub-section called the River Rovers under the guidance of Evanne & Terry Rothwell co-ordinates ongoing efforts to manage the Lower Silvermine River Wetlands. .
The Silvermine River Flood Management & Wetlands Scheme.
On 17th June 1992, fire destroyed about 675 hectares of vegetation in the Silvermine Nature Reserve in the main catchment of the Silvermine River. The risk of serious flooding in lower Fish Hoek and Clovelly in the coming rainy season was greatly increased. It was estimated that because of the fire, the flow volumes in the river could be as much as 25% to 40% higher than previously. The threat was exacerbated by the extensive housing and road development in areas which had previously acted as sponges and aquifers.
The C.S.I.R. was commissioned to look into the problem, and produced a report which recommended widening and deepening the river as a short-term solution, to be followed up by a detailed fully integrated catchment study. The Wild Life Society and the Silvermine River Society energetically opposed the suggested widening and deepening which would turn a fairly natural river into an earth canal. The need for action was underlined in June 1992 when heavy rains resulted in dramatic flooding in Fish Hoek.
These floods were possibly the start of the partnership between the Cape Town City Council and residents of Fish Hoek and Clovelly which culminated in the flood management scheme and wetland development which we see today. Officials at last realised that local residents had indeed a valuable and detailed knowledge of local conditions and problems, which could be worked on to the benefit of all. A case in point was Kim Kruyshaar’s “Silvermine River Wetland Project” of 1990.
Numerous studies and reports into all aspects of the Silvermine problem were produced during the next few years and local residents actively expressed their views and give guidance. Diverse aspects including the Fish Hoek Northern Bypass Road, retention of a tributary through Hilton Road properties, otter friendly access between the wetlands and the sea and wheelchair access was taken into consideration. It is not necessary to detail all the reports and investigations here, but one of the most interesting is the Silvermine River Action Plan, which contains a wealth of interesting information, unfortunately sometimes clouded in technical terminology.
The flood management / wetland scheme was undertaken in three consecutive phases. Phase 1 from the Main Road to what became the first gabion weir, Phase 2a from that point to the second gabion weir, and Phase 2b the final section to the electricity pipe bridge. Preliminary work started in November 1998, and major construction on Phase 1 commenced in 2000 – just a century after the building of the 1900 flood control dyke, portions of which have been preserved. The cost of Phase 1 was approximately R3 million. Phase 2. followed in 2001 at a cost of R3,4 million, and Phase 2b in 2002 at about R2,6 million. Apart from a few holdups due to heavy rain, work generally proceeded smoothly and according to plan. Total costs were eventually something over R10 million.
The final result is a most attractive asset, used by increasing numbers of walkers and home to about sixty varieties of birds. Thousands of indigenous plants were successfully established around the wetland, which provide an ideal habitat for birds, insects, animals and reptiles. The wetlands are also a breeding ground of the Endangered Western Leopard Toad, whose matrimonial choruses enliven the area in August each year.
The municipal authorities are unable to provide the day to day attention necessary to keep the area clean and attractive. A group of local residents, the Riverine Rovers have voluntarily taken on this task. The Lower Silvermine Wetlands is a prime example of what can be achieved when Council and residents work together.
Proposed Bio-Diversity Agreement Area
Current management of the Silvermine wetlands as an ecological asset is compromised by lack of resources. The bulrush or Typha grows too vigorously and is turning the wetlands into a mono-culture. Already there are concerns that the breeding ponds for the Leopard Toad are overgrown and that the number of bird species is declining. One solution is the proclamation of the area as a Bio-Diversity Agreement Area – which is currently being drafted. This will raise the conservation profile of the area and make provision for funds to be spent on ecological management e.g. clearing typha.
Another highlight is support from the Table Mountain National Park for the Source to Sea trail along the Silvermine River. The original route cleared and marked by the members of the Silvermine River Society such as Tom Keane, Jim Langridge and Lewis Walter will one day be formalized and will provide a hikers gateway from the Fish Hoek Valley into the Silvermine Nature Reserve.