Background & Introduction
The Mzimkhulu Regional Water Supply Scheme, which forms part of the KwaZulu
Natal’s Lower South Coast System, supplies water to the coastal region from
Hibberdene to Margate, including Port Shepstone. In addition, the scheme also
supplies many rural inland settlements such as Fairview, Kwa-Madlala, Louisiana,
Bhoboyi, Murchison, KwaNdwalane, Izontsha, KwaMavundla, Gamalakhe, etc, with a
total estimated present rural population size of about 140 000.
The water is presently sourced from non-regulated river flows in the Mzimkhulu
River. The water is abstracted at the St. Helen’s Rock abstraction works near
Port Shepstone and is pumped into the water treatment works. From there the
water is distributed to the various user nodes.
The Southern KwaZulu-Natal Water Resources Pre-feasibility Study Phase 1,
completed in 2002, concluded that during dry periods, the river flow is
insufficient to meet the water requirements, even without provision for the
release of the Ecological Reserve. The study recommended that, in order to
provide for the water requirements for all users, including the Reserve, the
construction of an off-channel storage (OCS) dam in one of the tributaries to
the Mzimkhulu River, should be considered. The reservoir would be filled from
its incremental catchment, supplemented by pumping from the Mzimkhulu River
during times of high river flows. During times of low flows water would be
released back into the Mzimkhulu River for abstraction downstream at the
existing St. Helen’s Rock Abstraction Works.
The Southern KwaZulu-Natal Water Resources Pre-feasibility Study Phase 2, which
was completed in February 2005, investigated numerous options with regard to the
position of the potential OCS dams. Four competitive sites located about 20km
north-west of Port Shepstone were selected as the most feasible potential OCS
dam sites. Two of the sites (D2 and D2A) are located on the Ncwabeni River while
the remaining two sites (D3 and D3A) are on the Gugamela River. Conceptual
designs for the dam at these sites were undertaken as part of the
Pre-feasibility study.
Following on the Pre-feasibility study a Reconnaissance Phase of the Mzimkhulu
River Off-Channel Storage Pre-feasibility Study, completed in October 2007,
re-assessed all four OCS dam options on the basis of more detailed hydrological
modelling and updated information regarding water requirements, topographical
surveys, geotechnical and flood hydrology data, which became available after
completion of the Phase 2 Pre-feasibility Study. It was established that the D3
site on the Gugamela River and the D2A site on the Ncwabeni River were
distinctly less favourable than the other two sites and were therefore not
investigated any further.
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