the water reservoirs, he will, for the benefit of the House, obtain from the Central Water Authority, inform…
(No. A/32) Dr. Ms B. Thannoo (Second Member for Quartier Militaire & Moka) asked the Minister of Energy and Public Utilities whether, in regard to the water reservoirs, he will, for the benefit of the House, obtain from the Central Water Authority, information as to – (a) the frequency at which dredging and maintenance works to improve the storage capacity thereof are undertaken and table information as to the number of times same have been undertaken since 2015 to date, and (b) why La Ferme Water Reservoir is reserved for irrigation purposes only.
Reply: With regard to part (a) of the question, I am informed by the Water Resources Commission that dredging to existing impounding reservoirs already in operation is not carried out for technical reasons and taking due consideration of the uncertainties related to the non- homogeneous geological condition in Mauritius. I am further advised that dredging will disturb the reservoir bed, which has consolidated over the years with the flow of silt during floods. It can also induce seepage of water under the dam foundation which in turn can endanger the stability and safety of the embankment structure. The safest method to increase the storage capacity of a reservoir is through raising of the dam embankment. In the event desilting of reservoir bed has to be undertaken, it should be carried out in the context of a complete rehabilitation/raising of dam project. In this case, the reservoir is completely emptied and additional engineering measures, for example, construction of cut-off wall, are implemented to secure the dam embankment. However, as for maintenance works around the major reservoirs, these are carried out regularly. Regarding part (b) of the question, I am informed that La Ferme Reservoir, located near the village of Bambous, has been constructed around the year 1914, across River Belle Isle and is primarily used for irrigation to support agriculture in the western coast. The reservoir has a storage capacity of 11.52 million m3. Historically, it serves the Black River District, supplying water for sugar cane and other crops, while also functioning as a key storage facility for agricultural, rather than domestic consumption. The Ministry has appointed consultants to review the La Ferme Dam structure and to propose measures to rehabilitate and enhance its structural integrity while at the same time, increase its storage capacity. Bidding documents have been prepared for the rehabilitation works which includes raising of the dam to increase the storage capacity to 14.0 million m3. It is envisaged to use the water for potable purposes once the infrastructure works are completed. Studies are ongoing on this aspect, given that a new water treatment plant would need to be constructed in due course. ALMA, L’ESPÉRANCE, L’AVENIR, RIPAILLES & NOUVELLE DÉCOUVERTE – WATER SUPPLY ISSUES – SURVEY OF UNUSED BOREHOLES & WELLS – DECENTRALISATION PLAN