Technical ReportPDF Available

Water quality in the Selati River, Phalaborwa

Authors:
  • South African Environmental Observation Network - Ndlovu Node

Abstract and Figures

In June 2009, the SAEON Ndlovu Node initiated a long-term research project on the water quality of the lower Olifants River, including the majority tributaries, within the Lowveld region of the Limpopo Province. This report describes significant results found for the Selati River, and was prepared at the request of the Makhushane Tribal Authority. Two sites on the Selati River have been sampled every 1 to 2 months for 3 years for macro-invertebrates, using the SASS 5 method. Various physical and chemical variables have also been sampled, although at less frequent intervals, during this period. One of the sites is located between the FOSKOR and PMC mines, south of the town of Phalaborwa. The other is located upstream of the mines, at the R40 bridge. Data from these sites indicate a progressive decline in the quality of the water in the Selati River, and the river is currently in highly degraded condition. To investigate the reason for the declining water quality, E. coli testing was performed in the Selati River upstream of the R40 sites, and in tributaries of the river that flow through the lands of the Makhushane Tribal Authority, in October 2012. These results indicated the inflow of partially or untreated sewerage, and a number of sites of sewerage input were identified. The high levels of bacteria in the water pose a health risk for both people and livestock. Related sources of potentially serious pollution were also identified, including the dumping of disposal diapers into water bodies, and pit latrine toilets.
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Report on the water quality of the Selati River,
Ba-Phalaborwa area, Limpopo Province
28th March 2013
SAEON Report: NDL/OLIF/01
Dr Anthony Swemmer
&
Mr Thabo Mohlala
SAEON Ndlovu Node
Kruger National Park
Private Bag x1021
South Africa
Tel: 013 735 3534
Fax: 013 735 3544
Int. Code: +27
www.saeon.ac.za
SUMMARY
In June 2009, the SAEON Ndlovu Node initiated a long-term research project on the water
quality of the lower Olifants River, including the majority tributaries, within the Lowveld
region of the Limpopo Province. This report describes significant results found for the Selati
River, and was prepared at the request of the Makhushane Tribal Authority.
Two sites on the Selati River have been sampled every 1 to 2 months for 3 years for macro-
invertebrates, using the SASS 5 method. Various physical and chemical variables have also
been sampled, although at less frequent intervals, during this period. One of the sites is
located between the FOSKOR and PMC mines, south of the town of Phalaborwa. The other is
located upstream of the mines, at the R40 bridge. Data from these sites indicate a
progressive decline in the quality of the water in the Selati River, and the river is currently is
highly degraded condition.
To investigate the reason for the declining water quality, E. coli testing was performed in the
Selati River upstream of the R40 sites, and in tributaries of the river that flow through the
lands of the Makhushane Tribal Authority, in October 2012. These results indicated the
inflow of partially or untreated sewerage, and a number of sites of sewerage input were
identified. The high levels of bacteria in the water pose a health risk for both people and
livestock.
Related sources of potentially serious pollution were also identified, including the dumping
of disposal diapers into water bodies, and pit latrine toilets.
INTRODUCTION
The Ndlovu Node of the South African Environmental Observation Network (SAEON)
initiated a long-term research project on river water quality of the lower Olifants River in
June 2009. Ten sites were selected, which included 6 sites on the major tributaries of the
Olifants River within the Lowveld. Two of these sites were selected on the Selati River.
The objectives of the research project are:
1. To detect trends of changes in water quality on seasonal and annual time scales.
2. To detect the occurrence and approximate location of pollution inputs (such as
sewerage overflows, industrial pollution spills, or nutrients leaching from farm lands).
3. To provide long-term data on both aquatic communities (invertebrate and fish) and key
water quality variables, at the same sites. Concurrent collection of both types of data
will allow for better understanding of the impact of reduced water quality on the
diversity of aquatic ecosystems.
The sites used for this research project are the same as those used for water quality
monitoring by the Department of Water Affairs (DWA). This project was initiated because it
was felt that the sampling conducted by DWA was not frequent enough to address the
above objectives.
METHODOLOGY
Sampling sites
The two sites on the Selati River are shown in Figure 1:
X1SELA-R40 is at the R40 bridge (DWAF sampling site WMS 72_1000009796),
X2SELA-MINE is between the mining areas of FOSKOR and Palabora Mining Company mines,
on the bridge of the road to the Phalaborwa barrage (DAWF sampling site WMS
B72_1000009797).
Water quality variables
Macro-invertebrates were sampled using the SASS5 methodology, as an index of water
quality. This was done every one to two months, by Thabo Mohlala.
Physico-chemical variables were sampled at the same time as SASS sampling, usually on the
same days the macro-invertebrate sampling. pH, conductivity, total dissolved solids and
dissolved oxygen were measured on-site, while the concentrations of metals were tested in
a laboratory using a spectrophotometer (Merck RQ-flex).
In October 2012, samples were collected for E.coli analysis, in order to detect sewerage
inputs, at the Sela-Bridge site as well as in tributaries of the Selati River upstream of these
sites. These sites are mostly located in the Makhushane Tribal Authority area. These samples
were analyzed by the laboratory at the Ebenezer plant of Lepelle Northern Water. These
were delivered to the laboratory and analyzed within 24 hours of collection.
Figure 1. Satellite image of the Ba-Phalaborwa area, showing the location of the two SAEON monitoring sites
located on the Selati River.
X1SELA-R40
X2SELA-MINE
Selati River
RESULTS
The SASS data indicate a constant decline in water quality at both Selati River sites, from the
time that the project started (June 2009) until the end of 2012, with more stable values
during 2012 (Figure 2). Values at the start of the period indicated that the river was
“moderately modified” (band C of the guidelines published by Dallas, 2007 ). By 2012, the
river had deteriorated to “seriously modified” (band E) at both sites. As declines occurred at
both sites, it is likely that the cause of the declining water quality is located upstream of the
Sela-R40 site.
Figure 2. SASS data from the macro-invertebrate sampling. Points show the "average score per taxon" (ASPT)
for the site at the R40 bridge (X2SELA-R40) and at the bridge on the road to Lepelle Northern Water (X1SELA-
MINE)
Physical and chemicals variables measured exceeded the guidelines set for Aquatic
Ecosystems by the Department of Water Affairs on most sampling occasions. Nitrogen and
phosphorus levels exceeded guidelines values on more than 75% of the sampling dates,
indicating the eutrophication (the addition of excess nutrients in the river water) has been
occurring for many years. Figure 3 shows that nitrogen values have often risen well above
the levels expected for a natural, unpolluted river.
High concentrations of nutrients such as nitrogen and phosphorus can only be the result of
pollution from untreated or partially treated sewerage, or from the leaching of fertilizers
from agricultural areas upstream. As there is no commercial agricultural directly upstream of
the Ba-Phalaborwa area, it is highly likely that sewerage inflows are responsible.
The E.coli results confirmed the input of raw or partially treated sewerage into the
tributaries of the Selati River, within the Ba-Phalaborwa area. E.coli bacteria were detected
at all sites tested, including two sites at the outflow of the Namakgale sewerage works
(Figure 4). E. coli counts should be zero for water released from sewerage works, according
to Department of Water Affairs guidelines. This was not the case for the Namakgale
Sewerage Works at the time of sampling. In addition, high E.coli values in other tributaries
indicated an overflow of untreated sewerage from a pump station located on the eastern
side of Namakgale, and from areas further upstream, most likely the Phalaborwa and
Lulekani sewerage works.
These data, including GPS locations of all sampling sites, can be obtained free of charge from
SAEON (email: thabo@saeon.ac.za or tony@saeon.ac.za)
Figure 3. Concentration of nitrogen in the Selati River, as indicated by nitrate (NO3) sampled at the two sites
between 2009 and 2013. The dashed red lines shows that limit for aquatic ecosystems set by the Dept Water
Affairs. Nitrogen concentrations should not exceed this limit for natural rivers.
Other observations
Extensive algal mats were observed on the Selati River, both in the Makhushane areas and
downstream as far as the confluence with the Olifants River. This provides further evidence
of severe eutrophication (i.e. an input of nutrients from sewerage sources). However,
additional sources of eutrophication were observed in the Makhushane area. These include
the dumping of disposable diapers (nappies) and other litter directly into tributaries (Figure
5), and hundreds of pit latrines that are built very close to tributaries and are likely to
infiltrate directly into the ground water.
Figure 4 Locations where samples were collected for E.coli analysis. E.coli was detected at all sites, indicating a risk of
disease if the water is used for drinking. Yellow dots indicate E.coli values between 0 and 235 colonies /100ml, which poses
a risk for swimming or washing in the water. Orange dots indicate E.coli values between 235 and 1000, which poses a risk
for young livestock which drink the water. Red dots indicate E.coli values greater than 1000, which poses a risk to both
young and mature livestock.
Figure 5. Nappies and litter dumped into tributaries of the Selati River, in the Makhushane Tribal Authority area
CONCLUSIONS
There has been a strong decline in the water quality within the section of the Selati
River that flows through the Makushane Tribal Authority land, between 2009 and
2013. The river is now severely degraded, as are many of the tributaries on this land,
and consumption of the river water poses a health risk to both humans and
livestock. The health risk resulting from eating fish caught in this part of the river has
yet to be established.
Inadequate treatment of sewerage is the most important factor causing this
degradataion.
DISSEMINATION OF RESULTS
The above results were presented at the following meetings:
52nd Inter-company Water and Waste Management Meeting at Sefapane Lodge in
Phalaborwa, on the 2nd November 2012, attended by representatives of the
Department of Water Affairs (Marcia Malapane, Henry Malulele, Tinyiko Mpele,
Gladys Makhado) and the Mopane District Municipality (James Nkuna).
A meeting of the Ba-Phalaborwa Local Water Forum, held on the 1st February 2013,
and attended by the Assistant Director for Water Services, in the Department of
Technical Services, Ba-Phalaborwa Local Municipality (Mr Khathu Mpharalala)
References
Dallas, H.F., 2007. River Health Programme: South African Scoring System (SASS) Data
Interpretation Guidelines. The Freshwater Consulting Group / Freshwater Research
Unit, University of Cape Town.
Department of Water Affairs and Forestry, 1996. South African Water Quality Guidelines
(second edition). Volume 5: Agricultural Use: Livestock Watering.
Department of Water Affairs and Forestry, 1996. South African Water Quality Guidelines
(second edition). Volume 2: Recreational Use.
Department of Water Affairs and Forestry, 1996. South African Water Quality Guidelines
(second edition). Volume 7: Aquatic Ecosystems.
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