WATER SUPPLY IN MAURITIUS WATER CRISIS! WHAT WATER CRISIS? Raj.H.Prayag et al.

WATER SUPPLY IN MAURITIUS WATER CRISIS! WHAT WATER CRISIS? Raj.H.Prayag et al. INTRODUCTION During the recent years at the end of the winter period, authorities responsible for the supply of water resort to water rationing in order to cater for potential water shortage and drastic water cuts. The question is: how come water shortage is experienced in a country where there is an average annual rainfall of over 2000 mm. In principle the water that falls over Mauritius should be more than adequate for the demand. It is a fact that the authority responsible for water management is competent, the engineers have the required experience. Furthermore, the authorities had commissioned various master plans, some done in the eighties, under the French cooperation program and other master plans were prepared in 2007 and in 2012 and consequently, have all the required engineering solutions for the sustainable management of the water resources in Mauritius. The paper also touches upon the authorities of the Ministry responsible for water supply that is, the Water Resources Unit and the CWA. It seems that there is a lack in clarity with regard to the various responsibilities. Which authority is responsible for the catchment areas, which is a key component for the harnessing of rainfall for replenishing of reservoirs and aquifers? The CWA Act of 1971 at part II section 4 defines clearly the responsibility of CWA i.e. The Authority shall be responsible for the control, development and conservation of water resources. It could not be any clearer that CWA is responsible for protection, harnessing, storage, treatment and distribution of water in the Republic of Mauritius. At Part IV of the CWA Act, the duties of CWA are further explicitly defined which covers a wide range of activities from investigating water resources; to preparing plans for conservation, utilisation and control and development of water resources, to preparing plans for the development of water basins and trans river basins, coordinate and investigate on the economic use of water. At section 21 of Part IV, of the Act, CWA should construct dams, reservoirs, drainage canals. It even has the responsibility to stock reservoirs and water courses with fish! What is the role and responsibility of the Water Resources Unit? When was it created? What are its legal responsibilities? Is there a clear legal demarcation of responsibilities between CWA and the WRU? If so, under which ACT? 1

The Rivers and Canal gives responsibilities to the Ministry responsible for local authorities, the Ministry of Health, the Ministry responsible for Forestry and the Ministry of Environment. The responsibilities are dispersed and the absence of a lead authority is clearly felt. This paper looks at the water demand trend over the years against the water captured and distributed and analyses the disparity between the two. The paper takes the form of questions and answers and it tries to provide as much information as possible. What are the Mauritius National Policies for harnessing of water, its management and distribution? The National Water Policy has been elaborated and approved in July 2014. (To be confirmed at level MEPU) In the most recent revision dated 2010, the guiding principles are: Water shall be considered as an economic good, which supports national economic integration and development and shall be conserved, developed and managed to provide economic benefits. As such, water should be used efficiently, with pricing policy and other mechanisms to encourage water allocation to higher value uses in order to maximise its net economic and social benefits. Water shall be considered as a social good that is essential to human dignity and social well-being. There should be explicit recognition that the poor should have access to water at an affordable price. Water allocation between sectors and users shall consider, among other things, the economic benefits balanced with social obligation and environment requirements. Due regard should be given to social development and food security. Government will promote measures to increase water use efficiency in agriculture. To ensure that provision of sanitation services is integrated into the provision of water supply for basic human needs Measures should be put in place to ensure that water is used in a sustainable manner, which also includes allocations set aside for environment maintenance purposes to safeguard the future existence of aquatic ecosystems. All new water mobilization infrastructure needs to be designed/phased with a view to be able to adapt to the impact of climate change on the availability of the island s water resources. The Objectives include 100% potable water coverage by 2020 and 75 % urban sewerage coverage by 2040. The water policy emphasizes that to solve the emerging problems in relation to the water resources, the supply side as well as the demand side will have to be managed more carefully than at present. 2

(b) In view of the huge change in the agricultural sector in terms of reduction in areas in cane plantation, etc, is there more water available for distribution for other uses? It is estimated that not much water will be available, as the development of agricultural land are mostly where there is no irrigation. (This goes against all logic!!!) Also water for existing irrigation system is already not sufficient. Use of treated wastewater for non-potable purposes As part of the solution for adequate water supply in Mauritius, the use of wastewater should be considered. In countries such as Namibia, treated wastewater is supplied directly from the plant to the consumer taps, while in Singapore it is mixed with potable water before reaching consumers as Nu-Water. At this stage, we propose the use of wastewater as a substitute for non-potable use, such as for irrigation and industrial purposes, so that the problem of social acceptability does not arise. The state of the art WWTP at St. Martin, funded by the EU and operational since 2005, treats wastewater received under gravity from the Plaines Wilhems area through the trunk main sewer network, and supplies the tertiary treated water for irrigation purposes. It has a design capacity of 69,000 m 3 per day and an average of 40,000 m 3 is being treated daily. The treated water, which undergoes sand filtering as well as UV disinfection, meets all the specifications of the EU Directive for irrigation purposes. Unfortunately, most of the treated water has been diverted to the sea for a long time. The treated wastewater has been initially used only in limited amounts - such as mixing, in equal proportions, with the water from La Ferme and Magenta Canals over limited periods to overcome the hesitancy of farmers on the western coast. The Montagne Jacquot WWTP, funded by the Japanese and located a few kilometres away from St Martin, has a capacity of 30,000 m 3 d- 1 and provides primary treatment with chlorine disinfection for the effluent. There is a definite potential, for feasible investment and sustainability, to upgrade this plant for tertiary treatment. Hence, a potential of 70,000m 3 per day is available, representing probably 20% of treated water daily output of the CWA plants actually reaching the consumers, for non-potable use. The water that can thus be saved from La Ferme reservoir can be made available for potable use, after installation of a treatment plant. In addition, hotels especially the coastal ones - should be encouraged to make use more effectively of their wastewater, for their own secondary use. The case for natural wastewater treatment plants e.g. constructed wetlands, with good quality treated effluents is proven today, and should be considered for sustainability reasons. Small, natural wastewater treatment plants can be set up on a decentralised basis they are less capital intensive, with low land footprints, low energy and no chemicals consumption. And the treated water is available for re-use immediately. 3

(WRU should be able to clarify for us on this point) (c ) Should Mauritius not be revisiting the issue of Water Rights? In the context of rationalization of water rights, an exercise was launched in 2013 to consolidate data on water rights holders. Very few holders of water rights have come forward. (WRU is in a better position to clarify) (d) How much more water can be made available from the Land Owners holding Water Rights? 1 Million cubic metre / day (guess) (apparently not much?) However, this is twice the volume of water being produced by CWA daily. (WRU is in a better position to clarify) (e) What has been the long term rainfall trend in Mauritius for the last 50 years and what has been the demand trend over the same period? An 8% reduction in rainfall has been noted from 1905 to 2007. The following table depicts the variations in long term rainfall pattern over Mauritius Period Mean(mm) Variance from Period Mean(mm) Variance from long- term long term mean mean 1904-1930 2,090-1.4% 1904-1960 2,180 +2.8% 1931-1960 2,260 +6.6% 1961-1990 2,100-0.9% 1961-2010 2,060-2.8% 1991-2010 2,000-5.7% Long Term mean 2,120 2,120 On the other hand, the demand (potable water) has been rising by an average of 2 % annually. (f) What is the projected rainfall for next 50 years and what is the related water demand? Projected rainfall next 50 years: At the southern Indian Ocean level, the following preliminary projection has been made based on IPCC model simulations: decreasing trend of 8% in annual rainfall. 4

The starting point for the demand forecast is a deficiency of around 66 Mm 3 in the capacity to mobilize enough raw water. Water demand projections indicate an incremental increase in the water requirements for the whole island of about 124 Mm 3 during the period up to 2050. Hence, the total water mobilization requirement by the end of the planning horizon is 190 M m 3 (refer to Master Plan for Development of the Water Resources in Mauritius by NIRAS/Mega Design) (g) What are the major constraints in harnessing rainfall for replenishing surface reservoirs and recharging aquifers? Further decrease in annual rainfall leading to reduction in freshwater availability Decrease in groundwater recharge and decline in groundwater level resulting in reduction of borehole yields, also accentuated by sea water intrusion in coastal aquifers due to sea level rise (impact of climate change). Increase in the rate of evaporation and evapo-transpiration specifically during the dry season Decreasing base flow in streams and rivers Urbanisation within the catchment of aquifer recharge Therefore the question is WHY? h) Are our watersheds protected and managed? If not? Why not? What are the constraints? There is no legal framework in place for preservation of our watersheds. No clear demarcation of responsibilities between the different stakeholders. However, reading the CWA Act 1971 part II section 4, it is the CWA. What are the proposals for developing a policy / watershed management plan? (i) What is the national strategy for water harnessing and management? (WRU Strategic Plan) what is the strategic plan? (j) Master Plans prepared since 1990s? Master Plan Study on Water Resources of Mauritius-French Cooperation (1991) Master Plan for Development of a Sustainable Potable Water Supply in Mauritius-GIBBs (2007) Master Plan for Development of the Water Resources in Mauritius NIRAS/Mega Design) 2012 5

(k) Why have not these Master Plans been implemented? No directive from Government towards implementation of the Action Plan The Master Plans have all been implemented to certain extents, on a piece meal basis. Given funding constraints and lack of in-house capacity, the projects have been prioritised and most important ones implemented first. It is, however, to be acknowledged that like most government agencies, the CWA is engaged in fire fighting most of the time and considerable funds and energy are diverted to these activities. (l) Look at the constraints in their implementation. Is it due to financial constraints? Or due to lack of appreciation in the urgency to plan and implement in view of impending huge variability in weather to come. Funding has been a major constraint. Another explanation is lack of government commitment towards implementation of the plan. (m) What are the priorities in the Water Sector? The upcoming Water Sector Reforms involving integration of CWA, WMA and Irrigation Authority into a single Water Authority, in line with the concept of Integrated Water Resources Management has been in the pipeline for a long time. This merger will allow a more holistic approach to be adopted in addressing water sector issues and will bring more synergy to the sector. The legislation is being worked upon. In conjunction, the Water Resources Bill will also be passed. Tackling the problem of NON REVENUE WATER (NRW), which is a major source of concern as it results in losses of a precious resource, which is translated into monetary losses for CWA? A reduction of NRW project is underway in MAV (Upper) Zone, with technical input from a team of Singaporean experts. It is proposed to extend this project to the remaining water supply systems, using a phased approach. (much delay has already occurred) Water balance between water produced and entering the system against water sold? Has this ever being undertaken by the CWA? If so, what is the finding? This is available. 50% NRW Aiming for water security up to 2040. Population growth coupled with a booming tourism industry, irrigation requirements as well as industrial and commercial growth will put additional pressure on existing water supply network and hence, projects aimed at harnessing and treating additional water resources are high on the agenda to be able to respond to future anticipated growth in water demand. 6

Building resilience to the effects of climatic change viz coping with prolonged drought conditions. This is being done by implementing projects such as interbasin transfers, drilling of new boreholes, construction of new dams and service reservoirs, new treatment plants, replacement of strategic old and inefficient pipelines, etc. Tapping of river sources and installation of mobile filtration plants are also being resorted to. A host of demand management measures comprising save water campaigns, promotion of water reuse, rainwater harvesting concepts, etc are also being taken. A change in mindset of people by instilling water saving culture is targeted. A reform of the Water Rights system is urgently called for. At present, it is estimated that there are some 500 holders of water rights based on a system of ownership that dates far back to colonial times. There is need for rationalizing this system as it is recognized that water is public property and cannot be privately owned. A modern system of large scale water allocation not based on human rights and land title but rather as a mechanism to permit the use of a public property and manage water in the environmental, public and economic interests of the nation as a whole, while fully encouraging, enabling and protecting private commercial investment and productivity. (n) What are the national plans, if any for this sector, with regards to Climate Change? At national level, a National Climate Change Adaptation Policy Framework has been prepared by the M/Environment. The policy framework explicitly recognizes that water supply by 2030 may not be sufficient to satisfy projected demand. The main objective of the document is to integrate and mainstream climate change adaptation into core development policies/strategies and plans of the Republic of Mauritius. Sectoral Strategy and Action Plan Strategies Fully develop the potential of integrated water management Aggressively increase water use efficiency Action List 1. Develop hydrological models 2. Identify strategies that can improve the co-ordination of local groundwater storage with local surface storage and other options 3. Promote the use of wastewater for agricultural needs 1. implement strategies to achieve a nation-wide 20% reduction in per capita water use by 2020 2. Apply all feasible efficient water 7

Expand water storage and conjunctive management of surface and groundwater resources Preserve, upgrade and increase monitoring, data analysis and management management practices to reduce water and improve the quality of drainage and return flows 3. Recycle water as drought proof water management strategy that may also be an energy efficient option in some regions 4. Authorise and fund new incentive based program to promote the mainstream adoption of water conservation 5. Reduce NRW to 25% 1. Increase surface water storage capacity thru the construction of 2 new dams and increase in storage capacity of existing ones 2. Expand the rainwater harvesting 3. Desalination to be considered as a means of increasing freshwater availability (This should be as a last resort because of negative environmental impacts and high energy cost. Furthermore, it goes against MID principle) 4. Encourage the adoption of local ordinances that protect the natural functioning of groundwater recharge areas 1. Improve the measurement of water use to facilitate better water planning and management (o) Is there any study/research undertaken to predict impact of climate change of the water resources of Mauritius? Should not there be one? The Climate Change Unit under aegis of Ministry of Environment and SD is active in researching and publishing results as part of international collaboration under the Inter-governmental Panel on Climate Change (IPCC). (You may browse the website or contact the Ministry for up-to date precise reports and results) Furthermore, the Mauritius Meteorological Services has over the past few years increased its ability to systematically monitor climate change parameters and has brought to light various trends of importance in assessing future impacts on water resource availability. (Meteorological services in better position to provide info) 8

(p) Should we not urgently plan for adaptation with regard to Climate Change? See (n) above Regular meetings are chaired by the Minister during dry season to monitor the water supply situation and urgent actions are taken to palliate the water deficiencies. A list of longer term measures are also agreed upon and projects that aim at building resilience to climate change are implemented. Government in the past provided funding for these projects (part loan/part grant to whom and what projects? What were the feedbacks and benefits?) (q) Policies on water harvesting at household level Government s decision on above is required. Necessary incentive scheme needs to be devised along the lines of the Water Tank Grant scheme. On its part, the MID Commission, which is coming up with the Green Economy Action Plan, is proposing to facilitate the implementation of rainwater harvesting systems for 10,000 families on a yearly basis and it is ready to provide the funds. What are the strategies put in place for its implementation and for the monitoring the benefits and impacts on the water sector? (r) How about sinking rainwater run-offs into sub-surface reservoirs /aquifers? Construction of structures and infrastructures in water catchment areas are depriving the aquifers much needed water for the recharging purposes. At the same time, the increased surface run-offs are causing over flowing of drains and flooding to properties and homes. Provision of sink holes to divert this excess surface water in certain areas could help recharge the ever depleting and over pumped aquifers. It is a fact that when aquifers are over pumped, the water tables are lowered and consequently, there is a negative cascading effects such as deprivation of water in the root zones for the cultivation of sugar cane with the inevitable consequences of lower productivity. (s) How about quality of water supplied at tap? The water supplied by CWA is 100% compliant to WHO norms for safe drinking water and standards set by M/Environment. Independent tests are also conducted by M/Health and Quality of Life. It is a known fact that water that test positive for bacteriological contaminations pertain to household water tanks which are not maintained properly. (t) Should we challenge ourselves on the way we use treated and piped water? Should treated water be used for industrial and irrigation purposes? Probably. It is however to be noted that raw water for some dedicated water system such as the Mare longue reservoir, Tamarin reservoir are channeled for irrigation through 9

the Magenta canal. Likewise in the north irrigation water coming from the Midlands catchment area is release through the La Nicoliere reservoir for irrigation in the northern plains. However, vegetable growers and livestock farmers do use piped water. Industries involved in food processing may need to have access to treated water. It is reckoned that manufacturing industries put undue pressure on supply of treated water. A mechanism needs to be developed for them to be able to have access to raw water supplies. (u) Is desalination of sea water an option? What is the cost per metre cube? What is the resulting impact of the concentrates from desalination plant returning to sea? Has any study been done to assess this? Desalination of water would not be a viable option for CWA. In spite of recent advances in membrane technology, the desalination process is still very expensive and impractical on a large scale. The cost per cubic metre of desalinated water is Rs 30/ approx. Apart from high cost of desalination, keeping in mind the topography of Mauritius, it would be too costly to pump the desalinated water from the coastal regions to the users on the higher plains. New hotels that are being set up are being encouraged by the authorities to equip themselves with desalination plants. Around ten of them do operate such plants. Where desalination is practiced on a large scale elsewhere in the world, it is usually because there is a cheap source of energy available. This option will become more attractive to Mauritius once our country becomes more self sufficient in renewable energy. With regard to return of concentrates from desalination plant, some research have shown that the resulting higher salinity in the water body has negative impacts on the marine resources such as the sea grass, corals and sea species. This is an area where Mauritius through MRC and the UoM should undertake research before the Authorities deciding on a policy to go for desalination plant. (v) What is the water pricing present policy? Pricing policy in Mauritius is based on cost recovery principle. It is however predominantly guided by social considerations, ensuring that tariffs are kept at reasonable levels so as not to hamper social and economic growth. (vi) Should we not cost and sell water at real production and distribution price? Mauritius being a welfare state and the authorities stand is that it would not be socially just to have a single tariff applied across the board. The pricing mechanism includes an element of cross subsidization in the sense that households and farmers pay a price which is below the real production and distribution price, whilst the commercial consumers, industries and hotels pay water rates which are above this average production and distribution cost. 10

Conclusions It is seen that Mauritius receives enough rainfall (over 2000 mm/year) to cater for the national demand. On the other hand, demand for potable and industrial use has gone up by an average of 2% a year while the trend in rainfall is down by approximately the same percentage. Therefore the need to plan for capturing more rainfall through strategically placed surface reservoirs, as advocated by the numerous master plans MUST be implemented in the short to medium terms. Innovative technologies for recharging the aquifers must be developed, as a matter of urgency. In view of the predicted exacerbated Climate Change driven uncertainties, the authorities should give the highest of priorities to securing water availability for its sustained development in the key sectors such as the social, economic, for ensuring agricultural productivities and food security. There should be no Water Crisis in Mauritius if the Authorities implement the recommendations of the various master plans. The technical / engineering solutions are available and there are enough Mauritian Engineers with experience in this sector to make water shortage a thing of the past. P.S This paper was written with inputs from engineers / experts (some who wish to remain anonymous and others who will recognise their inputs). IEM is grateful to all. rhpdrenv@intnet.mu 11