如果賴索扥根據南非原本的協議要求的量來排出廢水；則受到5-dam Lesotho Highlands Water Project (LHWP) 所影響的河流，可能會惡化成 "廢水下水道"。這些推論來自賴索扥高原水資源發展當局 (LHDA) 要求Meiti顧問帶領的內流條件 (IFR) 研究的最後草稿。這份報告打算告知提議Mashai水壩的計劃者，此為目前南非與賴索扥之間的協議交涉議題。
在IFR-報告中，專家們宣佈內流條件是相當廣泛的，它企圖預估建立Katse、Mohale、Matsoku，與Mashai水壩所造成的河流量減少的長期衝擊。它也提出補償與緩和這些衝擊的方法。
補償與緩和真的是一項龐大的工作。由於對於條約的堅持，造成在賴索扥流出的Kaste下游減少96%的水量，Senqu河則減少57%。這些則轉換成 "非常嚴重" 的生物物理學與社會衝擊，每年價值美金2.8~4.2百萬。直接居住在Kaste水壩下游的居民，已經報告水生害蟲的數目增加，以及在 Malibamatso河成為低流量之後，所產生的皮膚疹。
水壩造成河流在低水量與水災之間，以及需要小心處理的化學合成物的惡化。這些改變會引發生態系統的連鎖反應，進而影響依賴這些自然系統的群落。舉例來說，水壩也許可以預防水災，然而水災會產生可以餵養魚的昆蟲，魚可以提供必需蛋白質給居住在河岸的孩童。平均每20年，Katse、 Mohale,、與Mashai水壩才會允許一次水災 (比一年一次的平均高)。Kaste影響Senqunyane，Mashai則影響Senqu，而Malibamatso與 Senqunyane會流入Senqu。
根據這份報告，水壩的衝擊 "將會表現物理與化學狀況的嚴重惡化"，以及嚴重的生物變化。他們預估這個系統會有大密度的海藻生長，對魚類造成毒害；有毒植物的入侵 (特有植物的損失 - 以及依賴它們的物種)，造成黑蒼蠅與其它以家畜維生的害蟲嚴重增加；大部分魚類族群的減少，有些魚種，如Maloti鰷魚與蹲魚會瀕臨滅絕；瀑布下降；囓齒類族群暴增，進而影響河岸的作物。
這些生態系統的改變，造成許多社會衝擊。許多魚類與野生植物減少超過 50%。社會研究指出，當物種減少到某個數量時，居住在河邊的群落將再也無法收穫它們了 (這通常是長期的快速增加進與出河流流域)。因此，降低50%，會造成河岸村民100%的資源損失 - 這對於原本就處於低營養狀態的群落而言，是非常嚴重的狀況。低流量也會增加河流裡的污染物，造成像賈弟蟲等痢疾性疾病嚴重增加。作者指出，皮膚病與眼疾也預期會快速增加。這些損失的資源的現金補償價值，以及減輕水供應系統所供養的民眾與動物的健康問題、疫苗接種，以及VIP公廁，每年將高達4.28百萬元。
在報告的結尾，作者們形容賴索托的河川是：「活的博物館，蘊藏著有助於解開非洲古老歷史的生物種類」以及是當地居民的「世外桃園和淨化心靈的聖境」，他們要求水利資源決策人士在進一步推行計畫時，應審慎考量這些實際因素。
但IFR聲嚴厲色的草案，令賴索托與南非在持續協商「賴索托高地水源計畫(LHWP)」上陷入窘境。假如賴索托決定遵從該計畫所訂的條約，興建 Mashai水壩，以每秒50.8立方公尺的水量供應南非，南非恐怕將無力負擔興建此大型水壩所需的補償金；假如賴索托決定讓更多的水流入水庫，將減少市售水的供應，其結果亦將降低該計畫所應有的成本效益。無論賴索托的決定為何，南非無疑都將尋求成本最低的水源供應，但成本最低的選擇絕不會是在賴索托興建更多水壩。
顧問團又提出另一種對生態環境及人類生活傷害較小的假設，其一是以每秒38立方公尺的水量供給南非，如此每年可省下57萬1千美元用在賠償資源的損失。但是大費周張的抽水和居民外遷後，卻只能為戈坦市換來較少的水量，那麼興建Mashai水壩是否仍舊符合南非的成本效益還是個問題。
LHDA的環境及社會服務團體總經理夸姆‧歐杜魯說：「我們的任務就是從IFR的假設中，找出一個在經濟與技術上實際可行，又能兼顧環境承載度的平衡點。」
任務的下一個步驟將交由LHDA指派的獨立專案小組──
世界銀行，以及歐洲投資銀行，先對此草案做書面審查。專案小組的委員包括珍‧杜蘭博士、湯姆‧麥克瑪翁教授（兩位均為澳洲學者），以及麥克‧曼提斯博士（非洲籍）。歐杜魯表示，LHDA應在五月即公開發表審查結果報告，但這份報告至今仍尚未公佈。
- 詳情請洽：
- Lori PottingerInternational Rivers Network（國際河流組織）
- Tel: +1-510-848-1155
- E-mail: lori@irn.org
- 莫蘇西或穆西亞改造資源中心
- Tel: +266-314-463
- E-mail: centre@lesoff.co.ls
Rivers affected by the 5-dam Lesotho Highlands Water Project (LHWP) could deteriorate to "something akin to waste-water drains" if Lesotho delivers as much water to South Africa as the original treaty requires. This is according to the final draft of the In stream Flow Requirements (IFR) study conducted by Metsi Consultants at the request of the Lesotho Highlands Development Authority (LHDA). The report is intended to inform planners' decisions about the proposed Mashai Dam, which is currently the subject of treaty negotiations between South Africa and Lesotho.
The IFR, heralded experts as being one of the most comprehensive ever undertaken, attempts to predict the long-term impacts of reduced river flows caused by the construction of Katse, Mohale, Matsoku, and Mashai dams. It also recommends measures to compensate for and mitigate against these impacts.
Compensation and mitigation will be a truly formidable task. Adherence to the treaty requirements results in 96 percent reductions in river flow below Katse Dam and 57 percent reductions where the Senqu River flows out of Lesotho. This translates into "critically severe" biophysical and social impacts that will cost between US$2.8-$4.2 million annually to address. Residents living immediately below the completed Katse Dam already report increased numbers of aquatic insect pests, and skin rashes after crossing the low-flowing Malibamatso River.
Dams tamper with a river's complicated changes between low flow and flood as well as its delicate chemical composition. These changes can trigger a chain reaction of consequences for the ecosystem, which in turn impact communities that depend on these natural systems. For example, a dam may prevent a flood that would have triggered the emergence of insects that would in turn have fed fish that would have provided essential protein to children living along a riverbank. Katse, Mohale, and Mashai dams will only allow floods on the average of once in a 20-year period (rather than the norm of once a year). Katse affects the Malibamatso River, Mohale affects the Senqunyane, and Mashai affects the Senqu. The Malibamatso and the Senqunyane flow into the Senqu.
According to the report, the dams' impact "will manifest as strongly deteriorating physical and chemical conditions" and major biological changes. They predict dense algal growths throughout the system, which can be toxic to fish; encroachment of exotic plants (at the expense of native plants--and the species that depend on them); moderate to critically severe increases of blackfly and other pest populations which prey on livestock; reductions in most fish populations, with some species like the Maloti minnow and trout reaching the point of extinction; declines in waterfowl, and an explosion in rodent populations, which could affect crops along the riverbanks.
These changes to the ecosystem will have major social impacts. Many fish and wild vegetable species will be reduced by over 50 percent. Social studies have shown that when species decrease to this extent, communities living near the river no longer make the effort to harvest them (it is often a long, steep hike into and out of the river valley). Therefore, a reduction of 50 percent is effectively a loss of 100 percent of these resources to riparian villages--a serious situation given the already low nutrition levels in these communities. The low flows will also increase levels of pollutants in the river, causing critically severe increases of diarrhoeal diseases like giardia. Skin and eye diseases are also expected to increase sharply, the authors state. The cost of cash compensation for lost resources and mitigation against public and animal health problems via provision of water supply systems, vaccinations, and VIP latrines will reach nearly $4.28 million annually.
In closing, the report's authors plead for recognition of Lesotho's rivers as "living museums, containing species that could help unlock the ancient history of Africa" and as "places of great beauty and spiritual renewal" for the people who live near them. They ask that water resource decision-makers seriously consider these facts before making further developments in the system.
The draft IFR's dire warnings put Lesotho in a difficult position as it continues to renegotiate the LHWP Treaty with South Africa. If Lesotho decides to stick to the Treaty requirements by building Mashai Dam and delivering 50.8 cubic meters/second to South Africa, the resulting compensation costs may render the venture infeasible to South Africa. If Lesotho decides to allow more water to flow downstream through its dams, less water will be available to sell, again reducing the odds that the project will be cost effective. Either way, South Africa will no doubt choose the least-cost water supply, which may not be more dams in Lesotho.
The consultants present other scenarios that would cause less damage to the ecosystem and the humans living in it. One of these scenarios would allow 38 cubic metres per second of water to flow to South Africa while costing less than $571,000 annually to compensate for resource losses. The question is whether the construction of Mashai Dam will remain cost effective to the South Africans if it means less water for Gauteng along with high pumping and resettlement costs.
Kwame Oduru, General Manager for LHDA's Environmental and Social Services Group, said, "We are committed to finding an IFR scenario that will balance economic and technical feasibility with environmental acceptability."
The next step in this process is for an LHDA-appointed independent expert panel,
the World Bank, and the European Investment Bank will review the draft document first. The expert panel includes Dr. Jane Doolan, Prof. Tom McMahon (both from Australia), and Dr. Mike Mentis (from South Africa). Oduru said LHDA will release the report to the public in May. At press time, it still had not been released.
For more information:
Contact Lori Pottinger
International Rivers Network
Tel: +1-510-848-1155 lori@irn.org
Mothusi Seqhee orMotseoa Senyane-Makatjane
Transformation Resource CentrePhone: +266 314463
E-mail: centre@lesoff.co.ls
