Abstract
Water is one of our key and indispensable natural resources. It plays a fundamental part in life
(and the quality thereof), the environment, food production, hygiene, industry and power
generation. Water is one of the major limiting factors in South Africa when it comes to
economical growth and social development. In our country water is a scarce resource which is unevenly distributed both geographically and through time. As the demand for water increases,
with increasing human populations and economic development, so to does the pollution of our
river ecosystems.The Elands River is one of these natural resources that is under constant threat.
It falls within the Incomati Water Management Area and is further sub divided into the Crocodile River sub area. This sub area is highly stressed, as it provides water for several
human activities. The Elands River is a major tributary of the Crocodile River. The Crocodile
River is a source of fresh water for several towns and is used by industry, rural and the
agricultural communities (including tobacco farms). The Elands River in turn, is used for
irrigation of vegetables. Both these rivers support a rich diversity of aquatic life. Along with its
social and economical importance, the Elands River has immense ecological importance, as it holds great biodiversity including critically endangered biota.
The main anthropogenic impacts on the Elands and Crocodile rivers include:
· The Sappi Ngodwana Mill and the associated pulp and paper activities
· The influence of the Ngodwana dam wall on the flow and water quality within the lower
Ngodwana River
· Nutrient loading taking place due to the treated sewage that is released into the river in
the upper reaches and in the vicinity of the Mill
· Sedimentation and flow regulation that is taking place in the Crocodile River, upstream
of the confluence with the Elands River
· And the agricultural activities within the Elands River system.
The activities related to the Mill are the major concern in the study. The Sappi Ngodwana Mill
is situated at the confluence of the Elands and Ngodwana rivers. The mill does not discharge
effluent directly into the river. The effluent is however, irrigated onto the 514 hectares of
farmlands adjacent to the Mill. The irrigated effluent has contaminated the groundwater in this
area and the primary influence of this groundwater contamination is the deterioration of the
surface water quality as well as, negatively impacts the quantity of water in the Elands River.
The groundwater enters the Elands River through three springs near Ngodwana namely Fraser’s
eye, Northern eye and Eye X. The groundwater from both Fraser’s eye and Eye X has been
contaminated with calcium, potassium, magnesium, sulphates and most importantly chlorides.
All these substances contribute to the increase in conductivity in the Elands River, which in turn
may have a possible impact on the ecological integrity of the system. The pulp and paper
industry is a large consumer of water and few regrettable incidents over the years have given the
industry a reputation as a major water polluter. The industry’s management of water is,however, of world class and every attempted is made to manage the environment in a
sustainable manner. This study aims to assess the impact of these anthropogenic activities on
the associated aquatic ecosystems.
Assessing the impact of anthropogenic activities on the aquatic environments, like the Elands
River, has in the past been based mainly on the assessment of water quality. Earlier
management of water resources has thus been based on the potability of water. Over the last
decade management initiatives have expanded to include domestic, agricultural, recreational
and most importantly instream (fish, invertebrates etc.) users. It has become common practise to
use aquatic biota to assess the impacts of human activities of freshwater resources. The reason
for this is that animals and plants can provide a long–term integrated reflection of water quality,
quantity, habitat quality and other environmental conditions. Water and sediment quality was
assessed by applying standard techniques and protocols. Additionally historical water quality
data was obtained from the Sappi Ngodwana Mill and the Department of Water Affairs and
Forestry. Habitat quality was assessed by implementation of habitat quality indices. This
included that Integrated Habitat Assessment Index and the Habitat Quality Index. The
vegetation at each site was identified in the field with the assistance provided by the members of
the Elands River Valley Conservancy and using various field guides and the riparian zone was
then demarked. The integrity of the fish community was assessed by implementing the Fish
Assemblage Integrity Index and the Fish Response Assessment Index. The integrity of the
aquatic macro invertebrate communities was also assessed. This was achieved through use of
the South African Scoring System and the Macro Invertebrate Response Assessment Index.
Finally, spatial and/or temporal trends were assessed by implementation of various multi variate
statistical procedures.
Prof. J.H.J. Van Vuren
Prof. V. Wepene