The Dargle River was not quite the doddle that the DUCT River Walk team imagined. They had planned to do it in two days as it was less than 20 kms, but in the end they spent four walking.
Climbing up the river through the forest, in and out of steep river banks, high stepping through overgrown kikuyu, ducking under and through thickets, though thick mud, wading in deep water, clambering over fences and rock hopping.
Dargle farmer, Will Griffin dropped them off high in the hills near the road to Fort Nottingham where the river rises from a seep in the grassland. “This farm has been in our family for four generations.” He told them. “You are in for a great adventure.”
After trickling through the grassland for a few hundred metres, the river dropped straight down a cliff into the forest! This was certainly going to be an adventure.
The team, consisting of Penny Rees, Preven Chetty and Pandora Long spent most of the first day exploring the stream in the forest, finding waterfalls, little pools and admiring the magnificent mist-belt trees.
“This part is absolutely pristine” said Penny, “how wonderful to be able to drink straight from the stream.”
Unfortunately, it wasn’t long before the river hit human activity and the water quality dropped dramatically.
Although the river is still very picturesque in places, the banks are invaded by alien vegetation (bramble, bugweed, wattle), with kikuyu pastures right up to the edges and dams showing signs of nutrification.
As Dargle is a tributary of the Mngeni river, which supplies water to millions of people, this is cause for concern. “The land, river, sky are all one eco-system” commented Pandora. “When one part suffers, it affects the whole.”
Preven added “Where invasive vegetation dominates almost all indigenous plant and invertebrate life is excluded leading to a very degraded system.”
The main negative impacts were:
- Invasive alien plants causing poor condition of the river banks in the 32 metre buffers edge
- invasive plants eliminating indigenous vegetation
- Heavy siltation in many areas where cattle access the river to drink
- Too many nutrients (livestock, possible effluent)
- Rubbish: Dumping rubbish in the river and farm rubbish pits possibly too close to the river
Along the way there were promising signs of efforts to clear the riparian zone (32m is the regulation).
The Dargle Conservancy has begun clearing where the road crosses the river and, while it is a long term project, at least the water is visible now that the brambles are dead.
The highlight of the walk was a stretch of completely untransformed grassland and river.
Here the team found stoneflies (which indicate exceptional water quality) and marvelled at the ability of a river to heal itself when ecosystems are intact. “This made my heart sing” said Penny delightedly “It gives me hope for all our unloved Midlands rivers.”
The team conducted miniSASS tests all along the way to determine the health of the river.
Penny explains: A river habitat is a mirror image of the more familiar landscape of, for example, Mfolozi Game Reserve – teeming with predators and prey, herbivores and scavengers, each with his preferred home, be it under a rock, burrowed in the sand, swimming on or below the surface. These tiny critters are the base of an intricate web which links rivers and the land and the sky – each one dependant on and impacted on by the other. Damage to the river habitat has the same impacts on the river inhabitants as does damage to the bush which will cause problems for the Lions, Impala and Hyaenas.
The different river inhabiting insects have different levels of tolerance to pollution, and so, if you can catch and identify them, you can get a good idea of the health of the river.
The results on the Dargle River were:
- Site 1: 5.9 = Largely modified / Poor Condition (In an area that cattle access the stream to drink)
- Site 2: 4.75 = Seriously / critically modified (Very poor condition) (Downstream of cattle pastures, slightly silted and very shaded by invasives)
- Site 3: 4.9 = Seriously / critically modified (Very poor condition) (Downstream of crops and heavily infested with invasive plants)
- Site 4: 4.71 = Seriously / critically modified (Very poor condition) (Downstream of intense cattle pastures, eroded river banks and heavy invasive plant infestation at the site)
- Site 5: 7.5 = Largely natural / few modifications (Good condition)
- Site 6: 5.1 = Largely modified (Poor condition) Intense dairy, erosion from cattle trampling, bramble & kikuyu)
- Site 7: 6.6 = Moderately modified (Fair condition) less than 1km downstream of the previous site, with an extensive wetland and a waterfall between the two sites
The other test that the River Walks do is Methalyne (Meth) Blue – which indicates the oxygen levels in the water. A sample of water is stained with Meth Blue (the oxygen component is stained). If there are bacteria present, the bacteria will eat the oxygen and the blue colour will fade. Most of the sites along the Dargle had high bacteria levels.
Remember these River facts:
- Rivers can heal themselves (although this is no excuse to contaminate or impact them). In order to heal they need a long enough stretch without any negative impacts.
- Wetlands clean rivers – the roots of the plants actually absorb pollutants and help to polish the water.
- Keeping the river buffer area (32 metres wide from the edge of the water) in a natural state and clear of non-indigenous plants means rivers are healthier.
Sadly Dargle is not a healthy river.
Midlands Conservancies Forum secured funding from N3Toll Concession for this initiative as part of their Protecting Ecological Infrastructure Programme – to monitor tributaries of the uMngeni – Lions, Dargle, Indezi and Karkloof.
All data collected is shared widely, used by scientists, NGOs and government agencies, and is an important record of the state of our rivers. See the pictures and read all about Walking the Dargle at: http://umngeniriverwalk.wordpress.com/ Secret Forest; Rocky Horror; Heaven and Hell; It’s Doable.
We plan a miniSASS workshop and walk on Howard Long’s beautiful part of the river on 8 March. Penny will do a slide show of the river as well. Don’t miss out on the fun!