The streams that rise in Ekurhuleni and together become the Modderfontein River show large surges of water over a 24 hours cycle. These are the Kelvin Stream and the Sebenza Stream. The most striking pattern of flow is a lowest point about midnight followed by a surge in the early hours of the morning. This change can take place within a few minutes. Further changes occur but are less consistent and less marked.
The abruptness of the surges points to an active discharge of water. Whether this is waste water or reticulated water, the discharges must surely be dysfunctional.
The map shows the location of the sites. A time-lapse camera monitored the streams for periods from 24 to 96 hours, and the date and time stamp is on each photo. This report describes the changes in the Kelvin Stream, the Sebenza Stream, and the upper Modderfontein River.
A visual impression can be seen as a speeded-up time-lapse video.
Kelvin Stream at Dunbar Rd
In the 48 hour monitoring period starting mid-afternoon flow surged at 18:00, then receded to a minimum at 20:30. There was a sudden surge at 03:30 reaching maximum in 20 minutes, illustrated in Figures 1 and 2. The following day flow remained relatively high with a surge at 18:00 and decline similar to the first day. A surge at 06:00 reached the highest level in the 48 hour period, and at 07:15 it declined to the lowest level at 12:15 when there was a new surge (Figures 3 and 4).
Sebenza Stream at Driefontein Rd, Isandovale
The site is about 100 m downstream from Driefontein Road. The photos (Figures 5-7) show a dry channel at 01:05 which filled with water at 1:31 and reaching its highest point at 04:03. The grass in the foreground floated upwards to partly obscure the view before. The last photo shows the scene in daylight with a dry channel.
Modderfontein Stream at Crawford Rd, Illiondale
This site is about 100 m upstream from Crawford Rd. Over a period of 96 hours a daily cycle emerged. Starting mid-day the flow is low and late afternoon it increases. From early evening it declines to a lowest level about midnight. At a point somewhere between 01:00 and 04:00 it rises suddenly and very rapidly to its highest level of the cycle. From about 08:00 it declines, sometimes to another minimum around mid-day.
The following photos show a typical mid-day low (Figure 8), end of day increase (Figure 9), mid-night low (Figure 10), early morning peak (Figure 11), and still high at sunrise (Figure 12).
Monitoring the Jukskei River for 24 hours near the Clarkson Rd Weir in Morninghill, Bedfordview, showed the smell was fairly constant through the day but was slightly stronger at sunrise. The overall impression was that the river was more polluted in the early morning than at other times of the day, but this is probably due to local weather or micro-climate rather than changes in the water. The smell arises from the continuous flow of polluted water passing through, rather than accumulated sludge giving anaerobic conditions. The problems of pollution and smell will only be resolved when the source pollution in the Johannesburg CBD is addressed.
The project tracked conditions of the water that could possibly impact the smell or the appearance of pollution:
(i) Temperature: warmer water holds less dissolved gas so possibly smell is released from the river as the water temperature rises in the afternoon.
(ii) Dissolved oxygen: anaerobic conditions support the growth of bacteria that metabolize sulpher, releasing a distinctive smell.
(iii) Surface water level of the river and the quality of the water: this would show if the water flowing from the higher reaches of the Jukskei River over the course of the day changed and could impact smell or appearance.
The Jukskei River over 24 hours
The photo of the site project, about 100 m upstream from the Clarkson Rd Weir, shows how clear the water was (click to image to enlarge). The metered pole showing the water level is in the center of the photo.
Temperature and dissolved oxygen (DO) followed the expected daily rhythm. Temperature was lowest in the early morning, rising through to late afternoon. Dissolved oxygen rose during the day as the plants photosynthesize, and declined overnight. The smell at the river was present throughout the day and peaked at sunrise, but was not particularly strong.
The water level started rising from 6 pm and peaked at about midnight, returning to the daytime low about 8 am. The range was small, about 1.6 cm. Other measures of pollution showed no change over the 24 hour period. The water was too clear for turbidity to be measured and remained so throughout. Total Dissolved Solids were unchanged. Foam below the wall of the weir was constant through the day but was more marked at sunrise. Foam is however more stable at lower temperatures, and no difference could be seen elsewhere along this stretch of the river.
The impact of the Clarkson Rd Weir
Conditions are not the same in the typical part of the river, (the site in the photo above), in the dam where the rate of flow is slow, and downstream after the turbulence of the waterfall. The water was monitored at two additional sites, immediately above and below the wall. The next graph shows DO at the three sites, four times over the 24 hour period. The range is greatest in the dam, with a minimum of 2.9 and a maximum of 9,6 mg/L, but this does not amount to anaerobic conditions. DO was always highest below the wall, particularly at the sunrise minimum, showing how effective the aeration is as it tumbles down. The DO was also higher at sunrise at the upstream site, where the river was fast flowing but not turbulent, compared to the weir.
The Morninghill Smell does not come from anaerobic digestion of accumulated sludge, but from the continuous flow of sewage pollution from upstream. The dam behind the weir is shallow, the smell was not typical of anaerobic digestion, and the river along this stretch is reasonably aerated. The smell appeared to be trapped near the river by temperature inversion. These conditions dispersed with the breeze that started at sunrise.
The pollution and smell problems in Morninghill are linked directly to the source of sewage pollution upstream in the Johannesburg CBD. These problems will only be resolved when the source is addressed.
For more background on the Jukskei River and its pollution problems go to Jukskei River.
About this project
The site of this project was about 100 m upstream from the wall of the weir at Clarkson Rd, and at the wall of the weir.
Water level: A time lapse camera recorded water levels at night and manual photographs were taken during daylight. Smell was assessed subjectively by two people. The levels of smell shown are relative to each other over the monitoring period. Total dissolved solids: a TDS tester which also measured temperature. Dissolved oxygen was measured with dissolved oxygen meter which also measured water temperature.
My sincere thanks to local resident Gwen Doran for participating in this project and recording results during part of the monitoring period. Without her presence the project would not have been possible.
Jukskei River recovery from a major sewage spill is described.
In April 2017 a large sewage spill in Bruma caused a pollution increase in the upper Jukskei River. The flow was fixed on 3 May.
On 12 May there was heavy rain in the catchment (40 mm measured in Kensington), and on 15 May a contractor began cleaning up this section of the river.
I assessed the condition of the river during the spill (26 April), after the event (10 May) and after the clean-up (5 June). These results were compared to the most recent previous assessment (17 Dec 2016). A river health test using macro invertebrate MiniSASS assessment requires about six weeks to recover and will be done in July.
Direct measures of water quality (Turbidity and TDS) showed a rapid return to pre event levels once the spill stopped flowing.
The general consequences of the spill (appearance, colour, turbidity, foaming and smell) had not returned to levels before the spill by the post clean up assessment on 5 June.
Residents of Morninghill have expressed satisfaction with the clean-up which eliminated the smell.
It is not possible to draw conclusions as the efficacy of treating the contaminated river with special solutions of bacteria and enzymes since there are many uncontrolled variables. Only the elimination of smell in Morninghill is an improvement on the pre-condition of the river.
The real problem is the constant flow of pollution from the Johannesburg CBD, and the state of the river will be dire until the bad buildings there are fixed.
This report describes the Jukskei River recovery to 5 June 2017. Background to the situation of the Jukskei River is given here
Monitoring sites in this report
The map shows the five monitoring sites used to monitor the impact and recovery from the spill. The first site is upstream of the spill and the others downstream. Turnstone and Bruma sites are in Johannesburg and River Rd, Clarkson Rd and Willow Crescent are in Ekurhuleni.
Pollution in the upper Jukskei River
The problems brought about by the sewage spill in Bruma started in the second week of April with residents in Morninghill questioning the increased smell in WhatsApp groups, later on Facebook. There was confusion how to report it (Morninghill is in Ekurhuleni and Bruma is in Johannesburg). The local Councillor made the first formal complaint on 23 April. Response teams fixed two other sewage leaks without finding the main spill in the Queens Wetland, which was only stopped on 3 May. By this time the accumulated impact was so great that Joburg Water appointed a contractor to clean up, starting 12 May. Since I had already assessed pollution before, during and after the spill, I carried out a further assessment on 5 June to give a more complete view of the recovery. This river is extremely polluted permanently, so the April spill was in addition to the pollution from the Johannesburg CBD.
Morninghill residents say the bad smell problem in their area started after the removal of Bruma Lake. Odours are not easily measured and they tend to be stronger later in the day, possibly because the water warms up and expels dissolved gases.
Pollution trend Morninghill April 2015 to June 2017
Pollution in the upper Jukskei River at Clarkson Rd, Morninghill, is tracked using the three measures of pollution: RiverWatch Pollution Score, Total Dissolved Solids (TDS as ppm) and Turbidity (NTU) shown in Figure 2. Pollution increased drastically during the sewage spill on 26 April 2017. The main spill was stopped on 3 May, and on 10 May both turbidity and total dissolved solids were back at base level. The condition of the river, measured as RiverWatch pollution score, took longer to decline mainly due to ongoing smell, appearance and foaming and was still not restored on 5 June.
Pollution profile of Upper Jukskei River
Figure 3 shows Turbidity (NTU) at five sites between Turnstone Street Weir and Willow Crescent in St Andrews, Bedfordview, before, during and after the sewage spill and after the clean-up. Turbidity returned to pre event levels directly after the spill stopped flowing.
Figure 4 shows total dissolved solids (TDS in ppm or mg/L) at five sites between Turnstone Rd and Willow Crescent in St Andrews, Bedfordview, before, during and after the sewage spill and after the clean-up. TDS returned to pre event levels directly after the spill stopped flowing.
Figure 5 shows RiverWatch Pollution Score at five sites between Tenth Street Bruma and Willow Crescent in St Andrews, Bedfordview, before, during and after the sewage spill and after the clean-up. This score combines a visual assessment appearance, colour, turbidity, foaming and smell. Some of these take longer to clear, such as foaming, smell and appearance. At the post clean-up monitoring on 5 June all the sites to Clarkson Rd in Morninghill had not fully returned to pre-event scores.
Impact on the river by photo record
Turnstone Road Weir
The photos that follow show the condition of the water and stream bed at the Turnstone Rd Weir (upstream from the major spill in the Queens Wetland) and a second site downstream from the Clarkson Rd Weir in Morninghill. Click on the photo to see detail.
At Turnstone Rd Weir the situation appears much the same at all five occasions photographed between 17 December 2016 and 5 June 2017.
Clarkson Road Weir in Morninghill
Conditions downstream from Clarkson Rd Weir improved by 10 May with some algae clear of sewage deposit, and on 5 June 2017 it was almost as clear as on 17 December 2016.
At Turnstone Rd Weir, the first site monitored and upstream from the April sewage spill, the condition of the river is unchanged on all the monitoring dates except during the spill (April 26) when it was worse. This must have been due to another spill higher up that was fixed about that time.
Local residents have told me the clean-up late May eliminated the smell and they are satisfied with the outcome. The RiverWatch Pollution Score includes an assessment of the river smells, but these assessments were all done in the morning. At the two previous assessments in May and December 2016 there was no smell at the Clarkson Rd site. On 5 June 2017 a strong sewage smell was noted at the Turnstone and Bruma sites and faintly at the River Road site, but not at Clarkson Rd and further downstream.
The only improvement to something better than the pre-condition was the elimination of the smell at Clarkson Rd, reported by residents. Apart from that all sites as far downstream as Clarkson Rd had improved but not fully returned to the pre-condition. Other factors contributed to the improvement such as the physical cleaning, fixing another sewage leak in Morninghill and the rain two days before the clean-up started. As an experiment to see if treatment of the contaminated river with enzymes and bacteria is effective, it is not possible to draw any conclusion.
The sites will be tested again late July including the bio-assessment for River Health, which needs six weeks for recovery after a disruptive event.
Jukskei River pollution in the upper section of the catchment increased drastically in April 2017. Pollution and river health monitoring in Morninghill in Bedfordview shows this to be the worst situation in two years.
Pollution profiling at five sites between Bruma and St Andrews pointed to a problem upstream of the former Bruma Lake site
The source of the current problem is a sewage spill entering the river from the Queens Wetland, 50 m upstream from Queens Street Bridge.
This report describes the Jukskei River pollution from the Bruma sewage spill in April 2017. Read here for more background to the situation in the Jukskei River catchment.
Pollution trend in Morninghill April 2015 to April 2017
Jukskei River Pollution increased drastically in the upper section, as shown at Clarkson Rd, Morninghill. The first graph shows the trend in two measures of pollution (RiverWatch Pollution Score and Turbidity in NTU) and river health (MiniSASS) since May 2015. The situation in April 2017 is the worst recorded in two years, and reverses an improvement over the previous year.
Pollution profile of Upper Jukskei River April 2017
The second graph shows total dissolved solids (TDS in mg/L) and pollution score at five sites between Tenth Street Bruma and Willow Crescent in St Andrews, Bedfordview. These two measures of pollution show a sharp increase at the site of the former Bruma Lake.
Impact of Jukskei River Pollution
Upstream from Queen Street the water was grey-brown, foaming moderately with a smell of sewage. It is consistently like this. Downstream from Queen Street the water was grey-white, more turbid and smelling strongly of sewage. Usually the river at this point is clearer as much of the solid matter is precipitated out and retained by the weir under the bridge. The third photo shows the state of the river bed at the end of Clarkson Road in Morninghill. The rocks are covered in a layer of “sewage fungus”, making it impossible to assess river health.
The amount of foam increases steadily from Bruma to a peak at Gillooly’s Farm. This is usual since breakdown of sewage by bacteria produces the substances causing stable foam.
Source of the current pollution
The source of the current problem was easy to find. The photo shows the scene about about 50 m upstream from Queen Street Bridge. Pollution in the Jukskei River (foreground) is typical up to this point. In the background high volumes of heavily contaminated water are flowing from the Queens Wetland, which normally adds small volumes of clear water.
Quarterly Water Quality reports on the Jukskei River from City of Johannesburg (8 quarters) and Ekurhuleni Metro (14 quarters) were analysed for trends of sewage pollution
Jukskei River pollution is from sewage unchanged over this period of two to three years
The sites immediately downstream from the two sewage problem spots (Johannesburg CBD and Alexandra) show almost constant levels of pollution with no seasonal effect
Sites further downstream from the problem spots show lower pollution and a clear seasonal low in winter
Whether high or low, all sites have unacceptable levels of sewage pollution
Read here for more background to the Jukskei River catchment and its problems.
Upper Jukskei River
The site highest upstream is Bez Valley (corner 4th St and 5th Ave), where sewage pollution appears fairly level at an average of 2.1 million E coli counts per 100 ml. Downstream at Bruma E coli have declined to an average of 750 000 and at Lombardy East to 23 000. Ekurhuleni tests coliforms (also an indicator of sewage pollution) at Clarkson Rd in Morninghill, Bedfordview. Over three and a half years there is no trend, but there is a seasonal low in winter.
Alexandra and downstream
The first monitoring site after Alexandra is Marlboro Bridge, where the E coli counts per 100 ml are fairly constant and above 1 million. Two sites downstream show lower pollution with a more marked winter low, but there is no overall trend.
Lower Jukskei River
The E coli counts downstream from Northern Wastewater Treatment Works (NWTW) are fairly constant around 100 000 per 100 ml, which is about 5 to 10-fold higher than at the site upstream. This shows increased sewage pollution from the NWTW. The last two quarters are very similar, due to an increase at the upstream site. There is no trend over time.
Flood waters caused by run-off the Meadowdale Industrial Development tore through the suburbs of Buurendal, Highway Gardens and Hurlyvale on 9 November 2016 leaving more than physical destruction. They fed into a cycle of action and reaction between residents and the local authority of Ekurhuleni that started in the 1990’s:
Local authority underestimates the impact of run-off from the development
Addresses the issue only after a destructive flood
Prepares a plan to manage the run-off
Implements only part of the plan
A new flood and the cycle starts again
Visualize the problem. The perspective map of the Meadowdale Industrial Development below (click to enlarge) shows the catchment basin and the extent it is roofed over. Run-off from roofing is 100%. Storm run-off funnels to the low point at the R24 Freeway where it enters a culvert and emerges in the suburb of Buurendal. This view shows only the lower section of Meadowdale, the upper section Tunney adds to the run-off.
Then visualize the magnitude of the destruction on 9 November 2016. Water poured across the R24 Freeway 60 cm deep, flattening 40 – 50 m of fencing. It overwhelmed the retention dam and flowed diagonally across the suburbs. The flood followed the natural slope of the ground and original path of the stream. About 80 homes inside this path suffered damage.
The Buurendal flood of November 1998 – Cycle 1
As the Meadowdale development grew in the 1990’s there appears to have been no concern that the downstream suburbs in Edenvale were at risk. Then homes in Buurendal were flooded on 12 November 1997, something that had not happened before. On 19 November 1998 a devastating flood followed, affecting not only in Buurendal but homes and industries downstream in Eastleigh and Edenvale.
Residents of Buurendal asked the local authority, Greater Germiston Council at the time, to address the problem. They appointed consulting engineers who developed several options. The option recommended had three phases: First build a retention dam of capacity 2 800 cu m on a park land between Minuach and Donald Roads to manage a 1:10 year flood event. This was completed in 2000 and it is the Buurendal Retention Dam we know today. Phase 2 expropriate six properties and increase the capacity of the dam to 11 500 cu m to manage a 1:25 year flood. Phase 3 expropriate a further three properties downstream, building an open channel to a second retention dam in an existing open area. This dam would have a capacity of 20 000 cub m to manage a 1:50 year flood.
Phases 2 and 3 were not done.
On 12 January 2002 the suburbs downstream of the Buurendal Dam were flooded once more. Reacting to this the Director: Technical Services Ekurhuleni told residents that Phases 2 and 3 would proceed. The funds to acquire the additional properties were provided in the 2002/2003 budget, and funds for the second retention dam would be in the 2003/2004 budget. In 2004 two properties east of the dam were purchased and the dam enlarged to 6 500 cub m.
But Phase 3 and the greater part of Phase 2 were not done.
A drier period followed 2002 and flood matters became less urgent. It was also thought that storm water plans for the development of new Meadowdale extensions might make any further work at Buurendal unnecessary.
Development continued and about half the roof surface in this lower central section of Meadowdale in 2016 was built after 2002.
The Flood of February 2009 – Cycle 2
On 3 February 2009 a major flood caused damage in Buurendal and suburbs and industries downstream in Eastleigh and Edenvale.
Again residents of Buurendal banded together and this time submitted a petition to the Gauteng Provincial Legislature. Ekurhuleni responded and appointed consulting engineers Aurecon to investigate and produce the Stormwater Plan of 2011.
In the meantime development in Meadow continued and some measures were already being considered or being implemented. Buurendal Dam was cleaned and upgraded. This took more than two years and was completed in August 2011.
At a public meeting on 25 February 2010 Ekurhuleni presented solutions and told residents the dam at the top of Albert Amon Road was already in the budget. This retention dam was mentioned in meetings and newspaper reports through 2010 and 2011. In the 2011 Stormwater Plan it is called it “Upcoming Dam”, as if already in process.
Storm water run-off from the eastern development in Tunney was directed to the Harmelia Stream, through a berm built in Klopper Park. This option was not fully developed since Phase 2, the upgrade of an existing retention pond above Bell St, was not done. In 2016 there is a car park over the site of the dam shown in the original consulting engineer report. In addition the flood of 9 November crossed the diversion to Harmelia Stream and followed the natural flow to Buurendal.
The Storm Water Plan of 2011 consolidated options to control run-off in Buurendal and problem areas of Meadowdale. In the central Meadowdale catchment the consultants proposed four retention dams to reduce the flow under the R24 into Buurendal Dam from 56 cub m/sec to 23 cub m/sec in a 1:20 year event. The proposed retention dams are listed below and shown on the map of Meadowdale in 2011.
In the Stormwater Plan of 2011 run-off from the Greenhills and Tunney west developments was to be directed to the existing lake for attenuation in the 2011 storm water plan.
Meadowdale proposed attenuation dams 2011
Dam size cu m
Above Koornhof Rd
Above Albert Amon Rd
Herman Rd near R24
The Flood of November 2016 – a New Cycle?
On 26 October 2016 homes immediately below the Buurendal Dam were flooded when the dam overflowed. Two weeks later we have the devastating flood of 9 November that caused damage in Buurendal, Hurlyvale, Eastleigh and Edenvale.
At this stage, little of the 2011 Storm Water Plan seems to have been implemented. As at November 2016 (following map) no retention dams have been built. Two of the proposed dam sites have been built over, including the “Upcoming” dam site. The diversion of run-off from Tunney to Harmelia Stream is ineffective.
Will history repeat itself, or can Cycle 3 be avoided?
Rainfall and the Future
Officials from both Johannesburg and Ekurhuleni described the floods in Edenvale and Bedfordview on 9 November 2016 as a 1:100 year event. It may the most severe flood in 100 years, but the rainfall that brought it on is not that unusual. What has changed are conditions on the ground that make flooding possible, and the next event cannot be far in the future.
To give it context, rainfall modelling for this region, presented in the Storm Water Plan of 2011, is 138 mm for a 50 year event and 168 mm for a 100 year event. The highest 24 hour rainfall recorded at O R Tambo International Airport over 70 years is 187 mm.
On 9 November 2016 two sites in Edenglen measured 110 and 112 mm rainfall respectively, a site in Isandovale measured 95 mm and O R Tambo International Airport recorded 90 mm. Edenvale has twice received this amount of rain in the last 35 years (the other being 107 mm on 8 February 2000). The table below lists floods at Buurendal where the cause was run-off from Meadowdale, and the rainfall that brought this about.
1997 Nov 12
1998 Nov 19
2000 Feb 3
2002 Jan 12
2009 Feb 8
2009 Oct 30
2016 Oct 26
2016 Nov 9
On two occasions in the past Ekurhuleni has rejected claims of damages by residents saying the floods are a force majeure or “act of God”. This means the floods were something that could not be evaded through the exercise of due care. But here we have eight floods in the suburb of Buurendal over 18 years, three of which were major floods causing damage through the entire length of the river in Edenvale. The floods come from a very clear source, and lack of due care from the local authority is evident throughout this period and earlier.
The local stormwater control measures planned for Meadowdale should be implemented but are not adequate. I see only one answer that will permanently fix the situation, both for Buurendal and those further downstream. Demolish a strip of houses through the suburbs that lie on the original course of the stream from the R24 to Horwood’s Farm, open up the buried stream and bring it to the surface, and landscape a series of dams and wetlands to slow the flow.
Documents on the proposed development of JP Bezuidenhout Park and Horwood’s Farm show 50-year and 100-year flood lines. The flood on 9 November 2016 reached and slightly exceeded the 50-year flood line opposite the sports fields.
South of where the Harmelia Stream crosses Main Road (just off the map provided so one needs to extrapolate) the flood levels were probably well over the 50-year flood line. This is because the run off from Meadowdale industrial area crossed the R24 Freeway, overflowed the Buurendal retention dam, and flowed directly through Buurendal, Highway Gardens and Hurlyvale suburbs to arrive at this point. The photo below shows the maximum level of the water in Main Road between North Road and South Road. This was mainly due to the flood through the suburbs. See also Rainfall and Jukskei Rive Catchment Information and Edenvale Stream.
What can we learn from this?
First, the flood lines used in the documents for the proposed development show residential buildings inside the 50-year flood line, while the 100-year flood line includes up to three rows of houses. At the time they were built they would have been outside any flood risk area. As run off increases the flood lines have to be expanded, and those that were safe are no longer so.
Second, the response of the local authority to the increased flooding from the Meadowdale development has in the past been too little too late. The Buurendal retention dam is completely inadequate. The Eastleigh Stream is too constricted to cope with the current run off and further development in the catchment will make things worse.
Jukskei River Pollution and Health Profile May 2016
Many are concerned about Jukskei River pollution. Here is a view of the pollution and health of the river in May 2016 with trends over the years.
The Jukskei River has two major sources of pollution: sewage from Johannesburg CBD and from Alexandra. In Quarter 2 2016 pollution and E coli counts decrease downstream and river health improves, but in all cases the E coli count is unacceptably high and the river health is always in the lowest ecological category which is “Very Poor”.
Johannesburg CBD and its effects on the downstream suburbs Bruma and Morninghill: Over the ten year period from 2004 to 2014, downstream from the former Bruma Lake, E coli counts have increased 100-fold, most of which happened between 2007 and 2009. Over the last year, upstream from the former lake, E coli has been at around I million per 100 ml. Ekurhuleni monitors further downstream at Morninghill in Bedfordview, with similar results. The Bruma Lake was emptied and removed late in 2014, but there is no marked impact on sewage contamination downstream as shown by coliform tests. River Health has improved at the Morninghill site from April 2015 to April 2016, which could be a recovery from the effects of the lake removal.
Alexandra and downstream suburbs: E coli counts have increased steadily for the ten years up to 2014 and have been around 1.5 million per 100 ml for the last year. The impact of sewage from Alexandra on the Jukskei River must be at least as severe as that from Johannesburg CBD. The volume of the river at Marlboro is about double that at Bruma and the E coli counts are higher. From Marlboro the river flows through a stretch of open veld before it meets suburbs at Buccleuch and has already improved by then, yet the smell and litter problems are far greater than at Bruma and Morninghill. But the greatest impact is on Alexandra itself.
There are many sources of pollution throughout the catchment, but addressing these two will have the greatest impact in improving the river.
2. Profiles of the Jukskei River
The map (Figure 1) shows the course of the Jukskei River from its source in the Johannesburg City center to the Crocodile River and Hartebeespoort Dam, and the RiverWatch testing sites on the upper and mid sections. The monitoring points Morninghill and St Andrews are in Ekurhuleni while all others are in Johannesburg. The Marlboro site is immediately downstream of Alexandra.
Pollution was measured in three ways. Turbidity shows the amount of suspended particles in the water. The RiverWatch Pollution score is which is based on the colour, smell, clarity, foam and appearance of the river. The bacteriological profile shows E coli concentrations. E coli is a marker of sewage contamination.
Turbidity and Pollution scores in Figure 2 show two peaks of pollution: at the first source immediately downstream from the Johannesburg CBD and the second at Alexandra.
E coli test results were extracted from the Johannesburg Water Quality Report January 2016 which shows results for the previous four quarters, and used to create a profile of the river (Figure 3). The concentration of E coli peaks in two places: where the river exits Johannesburg CBD and Alexandra. In each case the counts drop further downstream, but at every site the counts are unacceptably high.
Figure 4 shows two measures of the health of the river. Dissolved oxygen is necessary for all forms of life except certain bacteria, and the test result shows how well the water will support life. Pollution feeds bacteria that use up the oxygen, eliminating organisms that need more oxygen. Dissolved oxygen in the Jukskei River is low following the inflow of pollution from Johannesburg CBD and again after Alexandra.
The River Health score (MiniSASS) assesses the types of invertebrates living at each site. Some invertebrates tolerate pollution more than others do not so this allows one to measure how pollution has affected life in the river over a period of time. The results show River Health scored zero at Bruma and Marlboro. It was impossible to do the test at these sites because of thick growth “sewage fungus”. River Health improves further downstream from the two sources of pollution, but at all sites the ecological status of the river was “Very Poor”, which is the lowest possible status.
3. Johannesburg CBD pollution
City of Johannesburg has supplied E coli test data for a site 150 m downstream from the former Bruma Lake to the National Microbial Monitoring Program (NMMP) from 2004 to 2014. The NMMP is managed by the Department of Water and Sanitation (DWS). Figure 5 shows the NMMP chart of results for this period. It is drawn with a logarithmic vertical axis so at first glance the trend looks flat, however it shows the E coli count increased about 100-fold over the 10 years, most of which happened between 2007 and 2009. The trend may be decreasing toward the end of the period but the points become sparse and CoJ has not supplied data to the NMMP since January 2015.
On leaving Bruma the Jukskei River flows through Bedfordview in Ekurhuleni. At Morninghill (Clarkson Rd site) Ekurhuleni tests for coliforms. This which is similar to the E coli test and it also serves as a marker of sewage pollution. Figure 6 shows results for the last seven quarters, together with E coli results from Johannesburg for the last four quarters for Bruma inlet, about 1 Km upstream. Bruma Lake was removed late in 2014, but there is no remarkable change in sewage markers downstream.
River Health at Morninghill (Clarkson Rd site) from April 2015 to April 2016 is tracked in Figure 7, showing an improvement with time. At first there was heavy sewage fungus blanketing the bed of the river so that in April and again July 2015 it was impossible to sample for river health. The river at that time was also carrying a large amount of black aggregated material all the way to Morninghill. By September the suspended aggregate material and the sewage fungus disappeared and River Health tests could be done. It is possible that the condition seen in April and July 2015 was the result of the removal of Bruma Lake and this settled down to a new equilibrium.
4. Alexandra pollution
City of Johannesburg also supplied E coli test data from the Marlboro site to the NMMP from 2004 to 2014, and the NMMP chart is shown in Figure 8. E coli counts increase steadily about 10-fold. The Johannesburg Water Quality Report January 2016 shows counts from 980 000 to 1 900 000 per 100ml over the previous year.
Inspection of this section of the Jukskei on four occasions between October 2015 and May 2016 found inflows of sewage into the river at many points, but two were of overwhelming importance (see map Figure 9). The first of these was about 200m downstream from Alfred Nzo Road Bridge. In the photo (Figure 10) the grey sewage can be seen entering water that was still clear before that point. This relates to Figures 2 and 4 that show the river health high and pollution low at Alfred Nzo Bridge. The second inflow was downstream of John Brand Road Bridge. At the time of this photo (Figure 11) there were EPWP workers removing litter, but the polluted water flowed freely into the Jukskei. Both are stormwater outfalls and both appear to be small streams that have been built over. The specific source of the sewage must therefore lie in the poor infrastructure of the west bank area and catchment of these streams.
The impact of sewage from Alexandra on the Jukskei River must be at least as severe as that from Johannesburg CBD. The volume of the river at Marlboro is about double that at Bruma and the E coli counts are higher. From Marlboro the river flows through a stretch of open veld before it meets suburbs at Buccleuch. It has already improved by then, yet the smell and litter problems are probably greater than at Bruma and Morninghill. However the impact of the pollution on Alexandra itself is probably most severe and appears to receive little attention.
Pollution Tracker is a visual assessment of pollution of a river made by volunteers and uploaded via a smartphone app.