In the first of a four part series on the extensive impacts affecting the Mpofana River, Penny Rees writes: Having spent two days tramping down the Willow Fountain River that runs through Mbali outside Maritzburg, my head is spinning with the diverse tons of abuse and impacts that we heap on our rivers each day. Literally!
However, for now its back to the Mpofana and a summary of the river health status gleaned from tests and observations that we recorded during the Mpofana walk last month.
The Mpofana is no ordinary river, and like many things in life, is the exception to many rules. This small river (a stream really) was flooded into dubious posterity when it became the permanent recipient of water from the Mooi River as part of phase 1 of the Mooi uMngeni Transfer Scheme back in the 1980’s, when the transfer of water from the Mooi River to the uMngeni River via a pipeline was begun in order to increase the volume of the uMngeni River as demand from over 5 million people outstripped the uMngeni’s ability to supply the requirement of a thousand million litres of water for daily purification.
There was some research attempted at the time in order to glean an idea of how the increased amounts of water would impact the receiving stream. Of particular concern was that the increased flows, almost simulating constant flood conditions on the small river, would erode the banks away thus changing the ecology, health and route of the river and that the resultant silt would end up in Midmar Dam.
In addition, there was concern about the impacts to landowners along the river such as the flooding of their causeways across the river and loss of land to erosion.
These concerns seem to have become a reality. We have already seen the result of the erosion during previous river walks. In 2012, striding along the uMngeni River floodplain, despite a singular lack of recent rain, we were stunned at seeing a chocolate brown Lions River pouring silt into the uMngeni just 3 kilometres upstream of Midmar dam.
It was then that we began discussing the possibility of walking the tributaries in order to see where impacts originate.
Eighteen months after the uMngeni Walk, Preven and I set off down the Lions River – and saw once again the chocolate brown waters – this time being carried by the Mpofana into the Lions at the confluence of the two rivers.
Downstream of the confluence on a large floodplain, we saw how the Lions River had eroded to such an extent that stone gabions are being used in places to shore up the banks.
This is meeting with limited success, and it is clear that the meandering river is eroding at such a rate that it will change course and many of the meanders will disappear as the water finds the easiest, most direct path, re-routing the river to a straighter course. Apart from the ill effects that this is will have on the rivers health, such a straightening route will exacerbate downstream flooding and its dangers as the water, instead of spilling over the banks and dissipating onto the flood plain, will flood down the channel towards Midmar Dam at ever increasing speeds and force.
The inlet / head water of Midmar has been identified as an important Fish Breeding site and we wonder if and how all this silt is impacting the breeding site.
So, of course, the next logical step was to walk the Mpofana to see where the silt was originating – was the soil erosion behind the siltation due to poor land care or agricultural practices or the Mooi uMngeni Transfer Scheme. Or something else? That’s a long winded, but I guess, reasonable reason to walk a river!
Phase 2 of the Mooi uMngeni Transfer Scheme is now underway: the new Springrove Dam on the Mooi River is complete and full and as we speak a new, bigger pipeline is being installed beside the original aforementioned pipe in order to transfer increased loads of water from Spring Grove / Mooi River to the uMngeni River.
Was it fate, co-incidence or just the cogs of the universe turning that found us strolling, wading and hacking our way down the Mpofana when, due to the laying of the new pipes and construction of the new outfall, there has been no transfer of water for many months, and the Mpofana is thus at normal levels for the time of year.
Look out for Part two of the saga tomorrow.