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Solving Tobago’s water supply problem
Tobago is presently experiencing a period of a significant decline in the supply of potable water to households and business enterprises by the Water and Sewerage Authority (WASA). This situation is being said to be caused by the decline in rainfall resulting from the El Nino phenomenon thus impacting on the amount of water available to WASA for treatment and transmission.
While it is true that Tobago is experiencing a severe dry season in 2016, the real cause has been the failure of WASA and other state agencies to implement the policies and programmes necessary for ensuring the sustainability of water supply on the island.
Historically, Tobago has been recognised as an island prone to annual short falls in rainfall. Also, the geomorphology limits the amount of water absorbed into the soil to become ground water (rock type and slope steepness.) Runoff is rapid especially in the absence of vegetative cover.
This has been recognised as far back as 1776 when the Main Ridge Forest Reserve was proclaimed. The observation was made then that the more land that was cleared for planting sugar cane the less water emanated from the springs and the lower the water levels in the rivers.
Given the natural challenges that Tobago faces with its freshwater supply, the main strategies for ensuring sustainable water availability should include;
1. maintaining as much vegetative cover as possible to retard runoff and increase percolation;
2. establishing and maintaining artificial water retention and storage (dams and lakes);
3. minimising loss of water during transmission and distribution; and
4. implementing water use conservation measures to curtail demand.
A review of the performance of WASA and other State actors in pursuing the strategies identified above shows that efforts have been limited and ineffective. In fact, WASA’s efforts at meeting water demand have been reactionary and the main option chosen is not sustainable.
For the past 15-20 years WASA has been seeking to increase water availability by exploiting ground water and has pursued an extensive and costly well-drilling programme. This programme was originally premised on the idea of the existence of “mega watersheds” in Tobago. A myth debunked by this writer more than 15 years ago. All ground water in Tobago originates as surface water and is recharged through rainfall. There are no very large aquifers.
WASA’s well-drilling programme is basically exploiting areas with large faults or fissures or river valleys. It should not be surprising that water levels have fallen significantly in rivers and streams adjacent to which wells have been established. At Mason Hall for example, the Garden (Adelphi) River levels have dropped significantly since several wells were established about ten years ago. Also, the adjacent swamps have been drying out (with implications for the famous Mason Hall blue food).
In the south-western part of the island the limestone (coral) overlying the igneous bedrock does hold water but the risk of salt water intrusion is significant if extraction is greater than recharge, especially with ocean level rise.
This begs the questions: Has WASA or the Water Resources Agency done the necessary recharge calculations to determine the sustainable extraction rates for the wells currently in use or the ones to come on stream soon? Have inspection wells been established to monitor salt water intrusion?
Where artificial water retention and storage is concerned, we all should know of the failure to maintain the Hillsborough Lake by allowing periodic scouring (as per design), resulting in the sediment build up that will cost millions to rectify. It is also ironic and possibly foolish for WASA to be asking the THA for funds to assist with the de-silting venture when the two agencies are funded from the same source and the THA cannot borrow. Also, contrary to what some may believe, the activities of WASA in Tobago are the responsibility of the Central Government and not the THA (Act 40 of 1996).
The need for increased artificial retention/storage has long been identified hence, for example, the proposal for, and design of, a Richmond Dam in 1998. The Richmond Water Project if implemented would have also allowed for the de-silting of the Hillsborough Lake and major refurbishment of the Hillsborough waterworks with minimal disruption of water supply. Why was this initiative not pursued further? What was the rationale for abandoning this approach and opting for ground water exploitation that is a less sustainable?
In terms of reducing water losses in transmission and distribution, the evidence is clear, even from casual observation, that WASA’s process of leak mitigation and repair is unsatisfactory. Investigations have revealed that in too many instances burst mains have resulted from technician errors in operating valves, causing too much pressure to build.
Partly responsible for this is that some valves are clockwise and others anti-clock wise and many are not marked. Sheer carelessness, particularly in communication, is another factor (as I have witnessed). Why also should a leak have to be repaired seven times within two years? Is it the use of poor materials or bad workmanship or a combination of both? (Please do not respond with the answer of old mains).
It is in the area of demand management ie the conservation of water use that WASA and the other state agencies could have and still can achieve probably the greatest impact on the sustainability of water supply. Given the predictions for increased droughts in the southern Caribbean (climate change), and the rising demand from households and industry, the management of demand is critical.
It is true that WASA has been promoting conservation through its public appeals concerning the use of water hoses, repairs to leaking faucets, washing, bathing etc, but much more can be done.
Metering and the application of suitable tariffs have proven to be very effective tools in water demand management. Consumers pay attention to the consumption of any commodity when their pockets are affected. The present system of surcharging households based on the Annual Rateable Value of the Property does not promote conservation and is also grossly unfair to some.
We know that WASA has attempted a pilot programme of metering at Bacolet Gardens. What have been the results? Has average consumption per house declined or increased? Hopefully, consumption was measured before metering. The present Minister with responsibility for public utilities is hinting at increases at water rates. He needs to speak to the issue of metering first. Hopefully, the newly appointed commissioners of the Regulated Industries Commission will address this issue.
The application of appropriate consumer technology is another area where significant conservation can be achieved. Low volume/high velocity faucets, low volume flush toilets, drip irrigation etc, are very effective and can be applied, especially if the right incentives are in place. Rain water can be harvested and utilised for processes that do not use potable water.
New buildings and those being renovated should have water reticulation systems to accommodate rain water use. Schools and other public buildings using large amounts of water daily should be retrofitted to utilise stored rain water. This is all part of “Green, clean, safe and serene.” One would hope that the “green building” approach is being applied in the new buildings and housing developments of the THA.
Finally, desalination is being promoted as an option for increasing the supply of freshwater and indeed it is an option, but its viability is questionable. Desalination brings with it high capital and maintenance costs. Additionally, periodic shut down for maintenance is necessary, leading obviously to disruptions in supply unless some measure of redundancy is built in and for which consumers will ultimately have to pay.
The present situation demands that we rethink our approach to our water supply situation. It is predicted that the demand for water will fuel wars later in this century. We have seen recently how the disruption of water supply was used with deadly effect in India. Let us ensure that our grandchildren are well prepared to face that scenario.
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