Mbombela Water
Reconciliation Study
Water Quality
2rd Steering Committee Meeting
16 October 2012
Bundu Lodge
Objectives
Ensure that the water
reconciliation strategy for
Mbombela satisfies the quality
requirements of all relevant water
users.
More Specific Objectives for
WQality
• Identify triggers which may have an effect on water
quality
• Identify water users
• Evaluate current water quality and observe trends
• Compare ambient water quality with user requirements
(RWQO)
• Reconcile quality quantity and user requirements
General land Use in the Crocodile
River
• Forestry - the western half of the catchment, has the
largest number of plantations.
• Dry land agriculture - these activities are located
primarily in the central parts of the catchment and take
the form of maize, subtropical fruits, nuts, citrus, coffee
and vegetable cultivation.
• Irrigated agriculture - the primary crops grown include
maize, citrus, tobacco, sugar- cane and subtropical fruits
sugar-cane and citrus being the most important. The
largest areas of irrigation are located in the central and
eastern regions of the catchment.
General land Use in the Crocodile
River (2)
• Nature conservation - the major area of nature conservation
activity in the catchment occurs within the southern portion of the
Kruger National Park.
• Mining and quarrying - the majority of mining activity has occurred
along the Kaap River and to some degree in the lower Crocodile
River.
• Domestic and industrial land use - the towns of Nelspruit and
White River are the focus of domestic and industrial land use in the
catchment, with smaller centres at strategic points across the
catchment. The Sappi paper mill is situated at Ngodwana next to the
Elands River. Sawmill in Graskop and Smelter in Machadodorp
Water Quality Impacts
• Elands River
– Upper Elands River have generally good quality water
all year round. However, trout farming and sewage
treatment plants has been identified as a source of
eutrophication.
– Ferro-chrome smelter at Machadodorp
– Downstream in the Elands River, high electrical
conductivity concentrations occur due to the presence
of Sappi at the confluence with the Ngodwana River
Water Quality Impacts (2)
• Montrose to Nelspruit,
– Afforestation in the catchment of the Nels River causes an
increase in manganese background values, an increase in
sediment loads and a decrease in pH values during logging
operations.
– Agricultural runoff here is related to increases in electrical
conductivity, trace elements and nutrients.
– Diffuse source releases from Papas Quarry at the confluence
with the Gladdespruit , is a source of increased manganese
concentrations in the Crocodile River.
Water Quality Impacts (3)
• Nelspruit to the confluence with the Kaap River
– is associated with domestic runoff, littering and an
increase in nutrients. Industrial effluents from
Nelspruit cause an increase in manganese
concentrations, while major
– sewage treatment works at the towns of Nelspruit,
Matsulu and Nkayamazane are sources of high
nutrient loads in the river.
Water Quality Impacts (4)
• The Kaap River
– has a potential impact on the lower Crocodile River
due to agricultural runoff (increases in pesticides,
trace elements and nutrients).
– Mining activities have a high impact on water quality
in this river during low flows (increases in sulphate,
electrical conductivity, iron, zinc, arsenic and cyanide,
and a decrease in pH)
Water Quality Impacts (5)
• The Sabie Sand River
– Forestry activities close to or within the riparian zone
are the primary threat to health of the riparian habitats
and vegetation.
– Trout is a threat to in-stream ecological health,
through diversion of water for dams and weirs, which
impact on the water flows in the area. Rivers may
become enriched with nutrients from fish feed and
waste.
Water Quality Impacts (6)
North Sand River
• Typical impacts on water quality from rural and informal settlements
relate to poorly managed or absent sanitation systems, littering and
solid wastes being washed into the rivers and streams. Elevated
nutrients and bacteriological
• Small scale agriculture which takes place may result in an increase
of pesticides and nutrients from fertilisers in the rivers.
• Water is impacted by both waste water treatment plant discharges
and diffuse pollution from rural and informal settlements due to
poorly managed or absence of sanitation systems.
Water Quality
In general, a progressive decrease in water
quality occurs in the river with increasing
distance downstream.
Waste Water Treatment Works
• 7 WWTW ( Kingstonvale, Kabokweni,
White River, Hazyview, Matsulu, Rockys
Drift, Waterval Boven)
• Compliance to Water Quality Discharge
Standards are very poor.
• Microbiological > Chemical
• Only Hazyview is operated above capacity
Green Drops
Green Drops 2
RWQO
• RWQO is the water quality component of the Resource
Quality Objectives (RQOs).
– numeric or descriptive in-stream (or in-aquifer) water quality
objectives
– finer resolution (spatial or temporal) than RQOs
• Levels
– Target, Acceptable, Tolerable, Unacceptable
Reserve Crocodile X22B, X 22C X22J
Parameterr
Ecological Reserve
Basic Human Needs
Reserve
Water Quality Reserve
TDS
Na
Mg
K
Ca
Cl
SO4
Soluble Phosphate
Total Inorganic Nitrate:
Soluble Phospate
≤ 254
≤ 30
≤ 19
≤ 1.1
≤ 20
≤ 18
≤14
≤ 0.055
>33.1
≤ 1000
≤ 200
≤ 100
≤ 50
≤ 150
≤ 200
≤400
N/A
N/A
≤ 254
≤ 30
≤ 19
≤ 1.1
≤ 20
≤ 18
≤14
≤0.055
>33.1
pH
DO %
Ammonia (mg N/l as NH3)
5.6 - 8.1
>100
95% < 0.015
5 -9.5
N/A
N/A
Fe
Al
Mn
42
95% < 20 and 99% < 150
95% < 370 and 99% < 1300
TWQR
Cr (VI)
Cr (III)
Zn
Cu
Cd
As
CN
Cl
95% < 14 and 99% < 200
95% < 24 and 99% < 340
95% < 3.6 and 99% < 36
95% < 1.5 and 99% < 4.6
95% < 0.5 and 99% < 6
95% < 20 and 99% < 130
95% < 4 and 99% < 110
95% < 0.35 and 99% < 5
6.
-8.1
>100
95% < 0.015
95% < 20 and 99% < 150
95% < 370 and 99% < 1300
95% < 14 and 99% < 200
95% < 24 and 99% < 340
95% < 3.6 and 99% < 36
95% < 1.5 and 99% < 4.6
95% < 0.5 and 99% < 6
95% < 20 and 99% < 130
95% < 4 and 99% < 110
95% < 0.35 and 99% < 5
Way Forward
• What water uses are impacting on the water quality? 
• Who is using the water? 
• What water quality will be acceptable? 
• What is the current water quality and what trends do we
observe? 
• Reconcile current qualities with user requirements =
RWQO ?
• How can this results influence the Mbombela Water
Reconciliation Strategy?
Way Forward (2) Gaps
• Water Quality Monitoring Data limited
(spatial information and parameters)
• RWQO be set at desk top level with the
purpose of guiding this project only – no
public participation
• Classification of rivers not yet finalised