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PREDICTED IMPACTS Vegetation (See also Resource Impacts) ❏ Narrower vegetation zones along rivers ❏ Many riparian species will be less abundant ❏ Algal blooms will be more frequent ❏ Some species will increase Aquatic animals ❏ Increases in algal feeding invertebrate community ❏ Increases in tolerant filter feeding invertebrate communities; decreases in sensitive species ❏ Increases in some Simulium, (significant as stock disease vectors) ❏ Increases in midges ❏ Possible introduction of disease carrying snails, Planorbidae and Physidea ❏ Decline of some fish species: trout, yellowfish ❏ Likely extinction of the Maloti minnow in some river reaches Resource impacts ❏ Decreases in shrubs and trees used for fuel and construction ❏ Decrease in some medicinal plant species ❏ Decrease in availability and size of fish ❏ Decrease in availability of river sand ❏ Decreases in availability of wild edible vegetation ❏ Increase in the availability of reeds and thatching grass Socio-economic impacts ❏ Immediately downstream of Katse and Mohale dams, social impacts may be critically severe under the Treaty scenario, due to resource depletion ❏ Social impacts are low, however, for all sites located two or more reaches away from the structures ❏ The baseline health status of the population at risk is relatively poor ; the Treaty and Fourth scenarios increase the risks of infection from moderate to severe for diarrhoeal and skin and eye diseases. Summary of findings (continued) The main significance of hydrological changes will be as follows: Low flows will be lower, both wet and dry season low flows. Low flows are important for creating different conditions in different seasons, dictating the occurrence or emergence and population densities of various species at different times of the year. Small floods will be smaller and less frequent in occurrence. They stimulate spawning in fish, flush out poor quality water, cleanse the riverbed and sort river stones by size, thereby creating different habitats. They trigger and synchronize activities as varied as upstream migrations of fish and germination of seedlings on river banks. Large floods will be almost eliminated, except for very wet periods when the dams may overtop. Large floods provide scouring flows that shape the river channel; they also trigger some of the same responses as small floods. They move and cleanse cobbles and boulders on the riverbed and deposit silt, nutrients, eggs and seeds on floodplains; they inundate backwaters, secondary channels and floodplains, recharge soil moisture levels in the banks and trigger bursts of growth in many species. Flow variability will be reduced, in daily, seasonal and annual cycles. Variability acts as a form of natural disturbance, which effectively creates temporal and spatial habitat mosaics, of areas inundated and exposed for different periods of time. The greater the habitat diversity, the greater the species diversity and the greater is ecosystem stability and resilience against unnatural perturbations. Overall Impact Rating The overall significance of the potential biophysical changes flowing from these hydrological changes was rated by Metsi for each IFR site, under each scenario, as shown in Table 2. Table 2: Reach-specific summary of the predicted combined biophysical consequences for each scenario with Phase 1 dams in place. The levels of impacts are coded as follows: white – negligible; green – low; yellow – moderate; blue – severe; red – critically severe. 1 2 7 3 4 5 6 8 Reach Proximal to dam or weir Distant from dam or weir Minimum Degrradation M M L L L N N N Design Limitation ** Site 1 is below Matsoku Weir, and attracts Severe and Critically Severe ratings, despite the relatively high proportion of MAR (40%) still flowing down the river, due to the extinction in the Matsoku River of the Maloti minnow. LHDA is establishing a program to protect the minnow in other Lesotho rivers. Summary Findings ❏ Sites proximal to dam structures have the potential to be severely impacted under all realistic scenarios (the exception is the Minimum Degradation scenario), largely on the basis of physical in-stream habitat changes and losses of aquatic biota. ❏ Consequential changes in riparian biota and resources are much less certain (see Predicted Impacts), as are changes in human and animal health vectors and agents. S** S S M L L N L Fourth S** S S M L L L L Treaty S** CS S S M L L M 8
RECORDED IMPACTS Metsi Consultants did their baseline study field work during 1999, when Katse Dam was being operated at close to Treaty minimum releases, so the results gave a good indication of the kinds of conditions which might prevail under the Treaty scenario: ❏ The state of both the instream and riparian habitat (“habitat integrity”) at site 2 (below Katse) was rated to be less than 50% (of the ‘pristine’ condition). Other sites – not affected by a dam – got scores of between 80% and 95%. ❏ Water quality at site 2 was poor, there were abundant algae in the water (mountain rivers usually flow clean) and very few fish. Monitoring downstream of Katse Dam (IFR sites 2 and 3) in summer 2000/01 and summer 2001/02 has shown ❏ A reduction in instream river health indicators at site 2, much less so at site 3, largely due to the absence at site 2 of sensitive groups of macro- invertebrates (only tolerant groups were recorded) ❏ A lack of clear geomorphologic trends (an important prediction of the IFR studies was major changes in river geomorphology), although sedimentation in some pools was observed; ❏ Woody plant species have increased in number and distribution, having colonised boulder beds and sandbars, which would previously have been often covered with water. This appears to contradict the study findings, but it does not mean that the pattern will not change in the long term. ❏ During summer 2002, however, river flow was very high and fish were reported to be abundant below Katse Dam. Metsi’s pilot community surveys, conducted in April and May 2002, show some communities already suffering fuel wood shortages that are not due to the project, that is, fuel wood resources are already depleted in some areas. They also report on the experience of communities regarding both reduced flows and flood conditions. Reduced flows allow their stock to cross the river, where previously they couldn’t, and encroach into other villages’ grazing lands. High flows, on the other hand, wash away trees planted by individuals. The Economics of IFRS Losses To Downstream Communities ❏ The IFR study finds sizeable economic losses (in terms of use values and necessary compensation costs) to downstream communities ranging from a total of M2,9 million to M8 million annually depending on the IFR scenario chosen. It should be kept in mind, however, that the figures are estimates only, based on certain biophysical predictions, and are primarily for the purposes of scenario comparison. ❏ The IFR study also finds that small increases in releases will only have a modest impact on these losses, although there are differences between the various resources and sites. Only considerable increases in IFR releases will succeed in sharply reducing the losses to downstream communities. Even in the Minimum Degradation Scenario, downstream communities do face losses for which, according to Treaty rules, they should be entitled to compensation of some form. ❏ A recent pilot consultation process amongst downstream communities revealed very realistic and clear preferences for mitigation and compensation amongst potentially affected communities, from programs of assistance to replace lost resources, to flow releases, to assistance with broader development needs as mitigation for losses which would be difficult to replace directly. Revenue and Other Losses ❏ While increasing IFR releases for Lesotho would reduce downstream losses, Lesotho would also lose variable water royalties and hydropower revenues, which would have a negative impact on Lesotho’s economy as a whole. For example, if the Fourth Scenario were to be adopted, the loss to the Lesotho economy would be some M17,5 million per annum at 1999 prices, or about 6% of the total revenues from the LHWP. In addition the original objective that Muela HEP would make Lesotho self sufficient in electricity, would be compromised. ❏ The Klasen study of the economic impacts of the different IFR release scenarios shows that, from an economic point of view, the economic costs to Lesotho and South Africa of increasing downstream releases beyond the Treaty minimum level always outweigh the benefits for downstream communities (and, thus, the costs of compensation for losses). This is the case from the point of view of the project, of RSA and of Lesotho. ❏ In other words, the lost royalty and hydropower revenues would always be greater than the economic losses to downstream communities. ❏ Notwithstanding this, the overall project benefits, over the life of this project, are so large that the viability of the project is not affected by including these downstream losses, that previously had not been considered in the economic assessment of the project. ❏ While the water transfer benefits of the project would be sharply reduced under the three scenarios with releases in excess of the Treaty Minimum, as would the already low rate of return of the hydropower component, they remain sizeable enough that LHWP as a whole remains viable even if IFR releases were increased. ❏ Therefore in setting the IFR policy some difficult decisions and trade-offs have to be considered, and public consultation is an essential element in this process. 9
Page 1 and 2: This document is intended as a mean
Page 3 and 4: PUBLIC DISCLOSURE AND INVOLVEMENT P
Page 5 and 6: Instream Flow Requirements: Theory
Page 7: WHERE TO GET MORE INFORMATION The 3

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