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Report No 678-F-001
METSI CONSULTANTS: SUMMARY OF MAIN FINDINGS FOR PHASE 1 DEVELOPMENT
The costs of mitigation for public and animal health are relatively low in comparison to compensation costs for
resource losses and the differences between scenarios are not as marked (Table 10.6). This stems from the
nature of the mitigation, i.e., immunisation and sanitation measures are directed at communities and not directly
at the specific consequences of flow changes.
Fish
Forage
Medicinal plants
Wild vegetables
Trees & shrubs
0 2 4 6 8 10 12 14 16
Minimum Degradation Design Limitation Fourth Treaty
Figure 10.2 Percentage of total resource value lost for each scenario.
The relationship between extracted water yields from the system and the extent of resource losses is not linear
over the ranges measured in the study. While the Treaty Scenario extracts only 20% more water from the system
than the Design Limitation one (which utilizes outflow capacities to the maximum extent to avoid downstream
impacts), overall resource losses are 30% higher and fish and forage losses about 50% higher. Losses under the
Treaty Scenario are also substantially higher than under a scenario in which relatively small additional
downstream flows are allocated, e.g., overall estimated resource losses for the Treaty Scenario are 17% higher
than under the Fourth Scenario, whereas the additional water yield is only ~8% more. The implication is that, in
seeking to mitigate environmental impacts and reduce resource losses, the differences between the Treaty and
other scenarios will indicate opportunities for achieving this without necessarily sacrificing large amounts of water
yield.
10.10. OPTIMISATION OF TREATY MINIMUM RELEASES
Article 7(9) of the Treaty refers to water released to rivers downstream of the LHWP structures, and states “The
LHDA shall at all times maintain rates of flow in the natural river channels immediately downstream of the Katse
and Mohale dams of not less than 500 and 300 litres per second respectively and shall, if so required, release the
quantities of water from either Katse or Mohale reservoirs as the case may be, necessary to maintain such rates
of flow: provided that subsequent to the implementation of Phase 2 of the Project, such rates of flow may be
adjusted by agreement between the Parties and provided further that in the event of either reservoir being at its
minimum operating level, the quantities of water released shall be equal to the flow rate into such reservoir not in
excess of the specified rate of release.”
If the Treaty provisions are interpreted strictly as stated above, then minimum releases of 0.5 and 0.3 m 3 s -1 would
be required at all times from Katse and Mohale, respectively, and there would be no opportunity to optimise the
releases (which implies changing them to suit downstream conditions). If, however, the Treaty-specified releases
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