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Water

Have a drink!

No man ever steps in the same river twice, for it’s not the same river and he’s not the same man.
Heraclitus of Ephesus

St Helena’s supply of fresh water was always an important resource

Water

Below: Important Resource • Too Much, Too Little • Engineering Solutions • Geography and Geology • Supplies Today • Connect Saint Helena Ltd. • Read More

An Important Resource

The presence of an abundant supply of fresh water is what attracted the Portuguese to St Helena in the first place. The sea route around the tip of Africa and up to Southern Europe was long and arduous, taking many months and with few opportunities to collect fresh water. It was evident to João da Nova that St Helena had an ample supply - from his anchorage in what is now James Bay he could see it flowing down the thickly-wooded valley into the sea. We do not have detailed records of his visit (probably lost in the Lisbon Earthquake in the 1750s), but it seems unlikely he failed to re-provision his ships’ supplies. So supplying João da Nova and his crews with fresh water was probably St Helena’s first contribution to humankind.

The Portuguese immediately decided to make St Helena a waystation in the South Atlantic, the modern equivalent of a Motorway Services. As is explained on our page The Early Years they released livestock (pigs, goats) and planted fruit trees and vegetables for collection by passing ships. All very useful but not eclipsing the value of drinkable water.

Formal occupation of St Helena had to wait until 1659 when Governor Dutton and his colonists arrived, and the presence of an ample supply of water made their landing place the ideal spot to found their settlement{5}. And thus what is now Jamestown was born.

Too Much, Too Little

The early history of the development of St Helena is underpinned by water - sometimes in insufficient quantities and at other times in excess. From the Records:

23rd January 1699: Reported that the island is suffering from a long drought. (Further severe water shortages reported in 1720-4 & 1738.)

5th March 1781: The fortifications at Sandy Bay are extensively damaged by a large torrent of water following heavy rain. (In 1787 Ruperts suffers a similar fate.)

Water shortage news, S.A.M.S. Radio 1 18th December 2016

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Major floods, most resulting in loss of life and/or destruction of livestock and property, were reported in 1691, 1701, 1706, 1781, 1863, 1871, 1873, 1874, 1878, 1887, 1904, 1932, 1987 and most recently in 1993. Severe droughts occurred in 1699, 1714, 1724, 1738, 1932-3, 1943, 1964, 1970 and most recently in 1973, all resulting in losses of livestock though with no reported human casualties. Note that 1932 began with flooding (in May) and ended with a drought running from October to June 1933 - quite a year!

This ‘boom-and-bust’ has continued throughout our history, even up to the present day, with severe consumption restrictions imposed over the summer of 2016/17 (The Run dried up) and again in June 2019{6}.

Too Much
Too Much

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Too Little
Too Little

… {1}
{1}{a}

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… {2}
{2}

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{b}

 

A wet decade…

The 1850s seem to have been a very wet decade, with many incidents of trouble with rain or the sea{7}:

22nd February 1753: Some very heavy showers of Rain which fell Tuesday last (18th) upon the Hills near Banks’ brought such great and impetuous Torrents of water down that valley as did much damage to the lower Platform there.

3rd September 1753: By a very heavy Sea such as never was known in the memory of any man upon the Island some damage was lately done to the old Battery at Sandy Bay.

22nd October 1753: The Guard House at Lemon Valley washed away by an unusual torrent of Water occasioned by some heavy Rains - likewise a Breast-work at Break Neck Valley.

20th January 1755: High surf damages fortifications in several places. (High surf or rollers during January also recorded as damaging property and sea defences in 1771 & 1787.)

8th September 1755: Some very High Surfs have lately washed away the Earth and undermined parts of the Works at Ruperts and done damage to those at the Main Fort.

29th June 1756: Council fails to meet due to a large Torrent of water coming down this valley which ran with such rapidity out of its common course that it was not possible to turn it until the Runs abated and therefore it has done great damage to the Fortifications and Plantations as well as to many of the possessions of the Inhabitants.

This may have included an El Niño period, but the phenomenon has only been recorded since the beginning of the 20th Century.

Engineering Solutions

Water supply to Ladder Hill Fort, Read’s map, 1817
Water supply to Ladder Hill Fort, Read’s map, 1817

In 1711 Governor John Roberts proposed to divert the water running from Plantation Valley to New Ground, a wide but waterless plain in St Pauls. Sugar cane and yams were to be grown there to double the revenue from harvests. This was not acted upon and today New Ground is filled with houses.

The need to fortify St Helena created a water problem. Forts tended to be on cliff-tops at high elevation, whereas water tends to run in the bottom of our many deep valleys. Carrying water to the fort in peacetime is not a major problem, but under siege any fort that does not have its own water supply cannot hold out for long. Even the fort in Chapel Valley (now known as The Castle) was built away from the river (nowadays The Run) because of the risk of flooding. The bedrock of St Helena is largely impervious, so simply drilling wells would not have been a viable approach, even assuming 18th Century fort-builders could have got access to the technology needed to penetrate solid granite. So some of the early water engineers devised some interesting strategies to resolve these problems.

Perhaps the most interesting is that devised for Ladder Hill Fort. The fort had its own water supply carried from what is now the Redhill Treatment Works, below High Knoll Fort, in a channel, probably of stone (see excerpt from Read’s map, 1817, right). It is not clear, however, if this was a covered or an open channel. If the latter it would clearly have become quickly apparent to a besieging enemy what the water was and where it was going, and it would have been very simple to interrupt, or more deviously, pollute the supply.

Curiously, High Knoll Fort was intended as a redoubt fort, where the population of the island could shelter in case of an invasion (hence the size of the large central area). And yet the fort has no water supply! It may be that there were wells, long since filled in, but no record of these exists. Without its own supply the fort would have had to be extensively provisioned with water before any siege to have had the faintest hope of holding out for as much as a week.

Natural watercourses, 1690s {3}
Natural watercourses, 1690s{3}

Then there was the water supply for ships. Originally, as shown on early maps (and explained on our page The Run) the water flow through Jamestown forked roughly where The Market is today, with one channel following the current route down the western side of the valley and the other travelling down the eastern side, behind the fort. Ships collecting water used this latter channel because it was more accessible from the landing place (the current Wharf). But as Jamestown was developed there was a need to build over this eastern channel so instead, in the late 1700s, a flow was created in an artificial channel, flowing from the top of town (at Chubb’s Spring), in pipes and/or an open channel all the way down to the Wharf, where it was stored in two cisterns - now the two round-topped buildings, one of which is the main image on our Historic Buildings page. This facility fell out of use in the 19th Century, though it is apparently still possible to see the old water channel in the footpath known as Sisters Walk.

In 1862, a scheme by Governor Drummond Hay to start a new housing development in Ruperts was made possible by the establishment of a reliable water supply piped into the valley from The Briars, although the scheme didn’t really take off and only a few houses were built.

A rather spectacular example of water engineering was implemented in 1900, when the Boer Prisoners (1900-1902) were encamped on Deadwood Plain. It rains a lot in Longwood but not so much in the summer and with thousands camped up there, plus guards and others essential to the camp, a water supply was needed. So a Desalination Plant (turning seawater into fresh water) was built in Ruperts and the fresh water pumped by steam engines up the valley to the Plain, some 500m above. Sadly the plant proved too expensive to run and was abandoned soon after it opened (only the chimney remains, and can be seen in Ruperts today).

Desalination plant in Ruperts (also showing the Ruperts Valley Railway)
Desalination plant in Ruperts (also showing the Ruperts Valley Railway)

Domestic water supply

Initially water was supplied not to individual homes but to communal taps, fed by a collection tank. Matty John was, for a time, employed as the Half Tree Hollow ‘waterman’. His job was to ensure the communal tanks were full and any drowned animals were removed. If you go up the main road through Half Tree Hollow you can see one of the blocks of taps on the turning by the Community Care Centre, though the taps are now dry - the feeder tank has long been dismantled. From the Records:

24th October 1906: Half Tree Hollow’s water supply dangerous to health with no finance for improvement.

Communal taps in Half Tree Hollow {4}
Communal taps in Half Tree Hollow{4}

Jamestown’s water was, however, the priority because in those days it was where most of the people (and many of the more influential people) lived. In May 1902, Governor Sterndale issued Ordinance #8 to improve the supply of fresh water to the town, in turn replaced by a similar Ordinance with the same number by Governor Gallwey in 1904. This stated that the water supply would be connected directly to homes, initially paid for by Government but with the costs recovered from owners in instalments. This did not work out quite as planned, Gallwey later reporting that the value of the drainage and water fittings in many buildings far exceeds the value of the buildings and contents. The result is that the poorer classes in Jamestown are burdened with a crushing load of debt{8}. But at least the residents of Jamestown had piped fresh water into their homes{9}.

Treatment works
Treatment Works{c}

Water supplies were improved elsewhere, too. From the Records:

1st July 1908: A 3in water pipe has been laid from Wells Gut to Longwood.

The water storage system for Half Tree Hollow was improved in 1916 by the addition of large storage tanks, the ‘three tanks’ beside the road near the Kingdom Hall. Further improvements (unspecified) are recorded as having been completed in 1959.

Governor Guy opening the Red Hill Water Treatment Plant

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Treated water was introduced in 1979. On 12th December the water treatment plants at Red Hill, Hutts Gate and Chubb’s Spring opened after construction by The Royal Engineers as part of ‘Project Bonaparte’. Some residents immediately complained that they did not like the taste. Just under a year later in October 1980 Chlorine was added to the Jamestown water supply for the first time. Other areas’ supplies were upgraded in the following months, but not the supply to Blue Hill, which remains unchlorinated at the time of writing. Many Saints continue to dislike the taste of treated water, even to the extent of driving to Blue Hill to collect untreated water for drinking and cooking, despite an official warning from Connect Saint Helena Ltd. that all untreated water should be boiled before use or treated with treatment tablets.

Water storage tanks, seen from High Peak
Water storage tanks, seen from High Peak

Geography and Geology

As discussed on our Geology of St Helena page, St Helena was formed by the eruption of two sea-floor volcanoes, some 7-15 million years ago. Originally the island would have been much bigger and dome-shaped (see the diagram on our Geology of St Helena page). Its current size and shape owes much to the action of water, eroding the land and forming the many deep valleys. The current water courses are shown in the image at the top of this page. Yet, today, most of these valleys are dry for most of the year, the only significant water flows being The Run in Jamestown, Lemon Valley, Sharks Valley, Fishers Valley and Sandy Bay. Either the island used to be a lot wetter, or water is a much more efficient erosion-agent than we might have expected. We favour the former explanation but, sadly, for most of the 7-17 million years of our island’s existence there was nobody here to document the weather.

The map (below) shows our primary watercourses and the rainfall isohyets (like contours):

Rainfall and primary water courses
Rainfall and primary water courses{d}

Supplies Today

Water found
Successful drilling

So how is sufficient water collected today the supply just under 5,000 inhabitants? The answer is springs and boreholes. Some rainfall is collected by simply falling from the sky into the reservoirs, but the majority is collected at springs around the island and some is pumped from boreholes. Sadly although the population is not increasing significantly, water consumption is. Figures released by Connect Saint Helena Ltd. showed that water consumption in 2018/19 had risen by 19,331,000 litres, an increase of 8% on the previous year. In modern life people wash themselves, their clothes and other things like floors and cars far more frequently than they would have dreamed of doing 100 years ago. Most people shower daily; as little as 50 years ago a bath was a weekly event. Clothes are washed after a single day’s use (or even a single evening), where previously the washing was done once a week. Horses did not need washing as often as cars (apparently) do. So the island is continually seeking new sources of water. Desalination has been proposed, using solar energy or biological processing to reduce the energy required (the 1900 Desalination Plant simply boiled the seawater and collected and condensed the steam - a very energy consuming process). It seems likely that Connect Saint Helena Ltd. will be continuously chasing further water resources for the foreseeable future.

Brown Water 2019

Another issue which constantly resurfaces is Brown Water. When one of the storage reservoirs nears empty, silt that has collected in the reservoir bottom gets drawn into the pipes, and somehow manages to evade the filtration processes, the result being brown water. This has been a complaint for many years and, at the time of writing remains so. Water also sometimes goes brown after maintenance work on the pipe network. Connect Saint Helena Ltd. advises customers to run the taps until the water clears but it has been pointed out that water is expensive and who pays for this wasted water? (The consumer, of course.) The picture (right) accompanied an article in the St Helena Sentinel on 4th April 2019.

Connect Saint Helena Ltd.

Connect Saint Helena Ltd. logo

In 2013 the Government of St Helena ‘divested’ responsibility for the island’s electricity supply & distribution, water supply & distribution and waste water collection & disposal to a limited company 100% owned by the Government of St Helena - Connect Saint Helena Ltd.

To ‘connect with’ Connect Saint Helena go to www.connectsainthelena.com.

Read More

Below: Article: ‘Serious Water Shortage’ Declared • Article: Desalination: the Ideal Solution? • Article: Meeting St Helena’s Water Demands

Article: ‘Serious Water Shortage’ Declared

By Andrew Turner, SAMS, published in the St Helena Sentinel, 20th June 2019{10}

Reservoir empty

An island-wide ban on nonessential water use will come into effect Monday. According to Connect Saint Helena Ltd., reservoir levels are at 30% or less, which signifies a Serious Water Shortage/Stage 3 Drought.

The St Helena Resilience Forum and Connect Saint Helena have activated Major Incident Plans. Further information on water restrictions, and information about how agricultural consumers can apply for exemptions, can be found on pages 28-29.

This is the first time since 2016 that the island has had such a severe shortage.

While partially caused by a lack of June rains (as in 2016), the current shortage was likely worsened by an increase in water consumption over the past year.

Currently St Helena is consuming around 280,000 litres more than we are collecting from our raw water stocks each day.

Pumps to move water between storage points were introduced in 2016 so that lower consumption areas or high-output sources could supplement other areas when necessary, and this process continues to be utilised to combat shortages. Consumers were first urged to reduce water consumption in May, when Connect Saint Helena Ltd. announced an island-wide water shortage. On June 1st Connect CEO Barry Hubbard said reservoirs were at 35% and remaining stable.

As long as we receive the winter rain at the usual time, the reservoirs will be replenished ready for next year, Barry said.

But since the beginning of this month, the water shortage has worsened. Consumption has not reduced, and the rains haven’t arrived as early as expected.

Since 1980 St Helena has started getting annual rains in June pretty much every year. However, in 2013 and three years later, in 2016, the rains did not arrive in June. Now, three years on from 2016… could we be seeing the start of a pattern? Regular updates on reservoir levels will be issued to the public. If you see anyone using water irresponsibly or notice a burst pipe or leak, Connect urges you to contact them immediately.

Article: Desalination: the Ideal Solution?

Desalination Machine

By Andrew Turner & Emma Weaver, SAMS, published in the St Helena Sentinel 27th June 2019{10}

Island surrounded by water, and still no water…

Why are they not converting sea water?

Build a desalination plant.

News of an island-wide water shortage last week spurred people, like the Facebook™ commenters quoted above, to ask why St Helena doesn’t use desalination. More than 300 million people now get their water from more than 20,000 desalination facilities across the globe, according to the International Desalination Association. But St Helena, although surrounded by ocean, does not house one of those facilities. If we could turn the ocean water into fresh water, then water shortages - like the current Stage 3 Drought and the similar droughts in 2013 and 2016 - might become a thing of the past.

But how feasible is desalination really, for St Helena?

What is desalination?

Desalination is the process of turning saltwater or seawater into drinking water by removing the salt.

Desalination is still a developing technology and many experts say that it is not ready to be used on a global scale. But that has not stopped countries such as China, India, South Africa and the United States investing in these plants. And according to the BBC, a number of small countries like the Maldives, Malta and the Bahamas meet all their water needs through desalination. Success stories like Israel where desalination saved the country from the worst drought the area had seen in 900 years.

There are two main kinds of desalination - Distillation and Reverse Osmosis.

Reverse Osmosis Distillation (ROD) is now seen as the more efficient method and has largely replaced Distillation. In ROD, seawater is pumped to one side of a tank and pure water on the other side, separated by a semi-permeable membrane. Extreme pressure is applied to the seawater side of the tank to push the seawater through the filter. The remaining salt and chemicals are then disposed of, usually back into the ocean.

On St Helena, many believe desalination could be effective in preventing water shortages. A stable supply of water is vital for St Helena currently. Most of the Government’s Sustainable Economic Development Plan (SEDP) relies on a good supply of water - to facilitate increased tourism, development and investment; to increase exports (like coffee and honey, all which need water to be produced); to enhance the supply of local produce; and to substitute imports (like the £65,000 worth of mineral waters we imported in 2016/17).

But would desalination prevent drought-related water restrictions like we’re currently experiencing? Experts say desalination comes with its own issues, and may be less than the ideal solution.

It’s expensive

For islanders already struggling with Connect’s current water tariffs - desalination would be even more costly.

According to the BBC, desalination may be getting cheaper but it is still prohibitively expensive for poorer countries, many of whom also suffer from water scarcity. This is mainly due to the costs of the desalination process - and for places like St Helena where only a small population would split the cost of desalinated water, these costs are especially prohibitive.

Of course, though, ROD is used on neighbouring Ascension Island, which has an even smaller population. As rains are rare on the island, Ascension uses ROD as its main source of water. Ascension’s system uses two ROD plants that fit into 20ft containers and are capable of producing 120 cubic metres of water per day.

For Ascension, desalination has proven very effective. But importantly, Ascension is a working island and so residents benefit from a water allowance from their employers (and the US Air Force base has its own separate ROD facility funded for its employees). Only when residents go over their allowances do they foot their own water bills.

I was working for AIG back in 2015, and as a resident of Ascension your contract comes with some water allowance, said Emergency Planning & Sea Rescue Officer Simon Wade. [But] after you use your allowance, you have to pay the true cost of water. That cost back in 2015 was £24 for 1,000 litres of water - and you quickly start realising that’s unaffordable. The cost on Ascension is now £29.30 per 1,000 litres.

The reason ROD is so costly, is that large amounts of electricity are needed to generate the high pressure that forces the water through the ROD filter. According to research from MIT, current methods require about 14 kilowatt-hours of energy to produce 1,000 gallons (3.8 cubic meters) of desalinated seawater. Therefore it would currently cost approximately £91 to produce 1,000 gallons (3.8 cubic meters) of desalinated water on St Helena. (Although cheaper, renewable energy is being promised by SHG as part o Connect’s deal with company PASH Global - the deal was publicised back in April 2018 but has yet to be finalised.) But for now, desalination on St Helena would mean households with a quarterly water bill of around £40, would instead see a bill of around £900, according to the island’s monopoly utilities provider Connect Saint Helena Ltd..

The cost of desalination is prohibitively expensive at about £24 per cubic meter plus that water would need to be pumped up to Hutts Gate or Red Hill which would cost another £20, so say £44 per cubic meter, Connect CEO Barry Hubbard said. We currently charge less than £2 per cubic meter so whilst [desalination] is technically feasible, people could not afford the increase. A household consuming 20 cubic meters of water per quarter would see their bill of approximately £40 increase to £900, which is unaffordable.

It would need environmental mitigation

St Helena uses diesel generators - and the amount of electricity needed to run an ROD plant would have clear associated environmental impact. And diesel pollution wouldn’t be the only worry. According to a report by Washington DC’s Food & Water Watch, the by-products of desalination include salt, bisulphates and chlorines. This waste typically finds its way back to the ocean and the concentration of chemicals is harmful to marine life. Some desalination plants try and reduce this affect by pumping the leftovers into areas with a heavy swell, so that the concentration mixes back in with the seawater quicker - but still, scientists are worried about the affects of the concentrated chemicals.

High salinity and reduced dissolved oxygen levels can have profound impacts on benthic organisms, which can translate into ecological effects observable throughout the food chain, said Wageningen University’s Edward Jones in a BBC article from January entitled Concerns over increase in toxic brine from desalination plants. Further environmental damage could arise because plankton, fish eggs and other organisms can be sucked up by the intake at the plant and killed during the purification process. As with most things, the better a system is designed from the beginning, the less impact there will be during operation, said Head of Marine Conservation at the National Trust Beth Taylor. No system is perfect and mitigation is not cheap. Any desalination project would need an in-depth EIA - as with anything - but it could definitely work here - and its urgency could be supported by the current issues with water.

It’s got associated health concerns

ROD would remove the salt from seawater - the fresh water would then be treated in the usual way. However, seawater contains a greater amount of chemicals such as Boron that cannot be entirely removed by ROD or by the standard water treatment methods, according to the World Health Organisation (WHO).

A small amount of Boron is needed by the body as it helps the body produce oestrogen and assists in bone growth. Boron is found in very small doses in nuts and other plant foods, and some people take Boron supplements if they are Boron deficient. However Boron can have negative effects on male fertility as well as being fatal in high enough doses. The WHO guideline value for Boron in drinking-water is 2.4 mg/l and many water companies have had to develop separate processes for removing Boron from ROD water.

And when salt is removed by ROD, some essential minerals like Calcium and Magnesium are also removed. According to a WHO study, this can negatively affect health because Calcium is a substantial component of bones and teeth and Magnesium plays an important role in digestion - and both minerals also help counteract the effects of metals (like Boron) in water.

Wait… Didn’t St Helena have a desalination plant?

Interestingly, St Helena used to have a desalination plant. In 1901 St Helena was faced with housing thousands of Boer prisoners, but the island lacked enough fresh drinking water. A distillation desalination plant was built in Rupert’s Bay. The plant was tested, though it was never really used (now only the large brick chimney remains).

Is there a solution?

Desalination technology is constantly advancing.

For instance, American company Memsys in 2011 showcased an entirely solar-powered desalination plant that fit inside a shipping container. The plant uses a process called vacuum multi-effect membrane distillation, which combines ROD with thermal desalination. Water is boiled in a vacuum, at low temperatures, and the steam is passed through several membranes at lower and lower temperatures and pressures. The system recovers its own energy at each step - and that energy is then used to power the next step. The shipping container unit can produce 265 gallons of fresh water daily. This system is cheap to run because of its energy efficiency and more environmentally friendly that standard ROD methods, as it runs on solar power.

Its health concerns are also significantly lessened, according to Memsys: This high quality of separation can be achieved for all mineral parts and organic elements including dangerous elements like Boron and Arsenic which can pass mechanical filtration processes like reverse osmosis. The Memsys system costs twice as much, though, to purchase as a standard ROD plant.

The Ruperts desalination plant in use in the 1900s
The Rupert’s desalination plant in use in the 1900s

Article: Meeting St Helena’s Water Demands

FoSH Wirebird cover #5 April 1992

By Ian Mathieson, published in the ‘Wirebird’, the magazine of Friends of St Helena{11} Number 5, April 1992{10}

Unlike many small tropical and sub-tropical islands St Helena is relatively well endowed with water. The quantity and quality of the water contributed significantly to the island’s importance as a staging post for the returning East India fleet in the eighteenth and nineteenth centuries.

St Helena has five perennial streams - James Valley, Lemon Valley, Sharks, Fishers and Sandy Bay. Powells also runs continuously in most years. As the diagram shows, the island’s average annual rainfall is over 900 mm in the vicinity of the Peaks and here lie the sources of the perennial streams. James and Lemon Valleys discharge into safe anchorages and so their exploitation has been possible although the Lemon Valley supply was of much greater significance in the past. The other main streams all discharge into unsheltered waters and the only effective way of harnessing their flows has been to intercept them before they drop too far down the valley. In the case of Sharks this has proved impossible because the main flow issues from a spring known as Hancock Hole situated well down the valley. Not only is the island fortunate in having James Valley, it’s principal stream, discharging into a sheltered anchorage but also with Lemon Valley this is the only stream that is not saline at low levels.

Despite having a relative abundance of water, droughts have also been a regular part of St Helena’s history. The effect of drought has been mainly felt by cattle - no rain to grow fodder crops and no water to supply the large pastures on the western side of the island. Until the last ten years little attempt was made to conserve water for dealing with drought periods which, during this century, have occurred about once every 15 years and have tended to last for two or three years with varying degrees of severity. The last drought lasted from 1983 to 1987. Although major attempts to improve the island’s supplies had already started by the construction of Scotts Mill reservoir in 1982 the severity and duration of this drought made it clear that increased attention would need to be given to improving the island’s water supplies.

Between 1984 and 1990 St Helena’s total demand for water nearly doubled to around 0.5 million cubic metres per annum. This increase was in part due to the ending of the restrictions imposed by the drought but also reflected the increased affluence of islanders, many of whose homes began to contain automatic washing machines, dishwashers and the other water demanding accoutrements of a more affluent society. In 1990 a plan, combining estimates of the island’s future water needs and with its water resources, was prepared by a joint team from PWD, A&F and the Castle. The study showed that by 2010 demand can be expected to rise by a further 50 percent to 0.75 million cubic metres per annum. About 25 percent of this demand would be created by agriculture and businesses and the remainder by domestic consumers.

The Water Plan also estimated the island’s total water resources. Of some 47 million cubic metres of rain falling on the island in an average year only about 4.5 million cubic metres emerges as spring or stream flow; the rest is lost to evapotranspiration. So to meet future demands in an average year nearly twenty percent of the island’s total water resource will have to be recovered; in a drought this could be more than 30 percent-a considerable challenge.

In the last ten years construction of storage reservoirs has been continuing apace. The programme has focused on trying to tap the supplies from the perennial streams. Following the completion of Scotts Mill, a second reservoir was constructed just upstream at Harpers. A third reservoir is under construction and a fourth planned so that the complex around Harpers will eventually have a total capacity of 50,000 cubic metres. This is being used to supply the treatment works at Redhill and from there to feed Half Tree Hollow, the island’s main growth area. Supplies from Chubbs Springs continue as strongly as they ever had, with the population of Jamestown static or even declining, no major improvements are envisaged on this system. Water has always been a problem at Longwood which receives it supplies from the springs issuing at the head of Fishers Valley above Hutts Gate. During 1989 Willowbank was investigated as a possible reservoir site with which to augment the supply. The valley’s gravelly bottom proved unsuitable for reservoir construction but was shown to provide a very substantial groundwater reservoir. Tube-wells were sunk and the resulting abstraction pumped to Hutts Gate to give Longwood a much more reliable supply. Another small reservoir was constructed at the head of Deep Valley to supply the Levelwood area. With the commissioning of the island’s fourth water treatment works near this site during 1990, more that 90 percent of the island’s dwellings now have access to a treated water supply. The success of these developments has greatly raised islanders’ expectations both about the quality and reliability of supply. A series of wet years since 1988 has meant that it has been relatively easy to meet demands. However, statistics point to the likelihood of a drought occurring before the end of the century. Will the island cope? One encouraging factor is the enlightened management of the system. Ahead of Britain, all St Helena’s homes have their supplies metered and charging is being introduced this year aimed at reducing wastage. But as we have seen, in a drought, about one third of the total water resource will need to be collected if major restrictions are to be avoided. There are few places in the world where such high levels of recovery are attained and certainly not anywhere with such difficult terrain. There is a possible solution and the key to this is provided by the island’s endemic vegetation.

Anyone who has lived at Longwood will know that mists are a common occurrence. During the summer when the grass on the golf course is brown they may have noticed areas of green under some of the trees and hedges. This greenness is due to the trees’ leaves intercepting the mist and causing it to condense and drip onto the grass beneath. Mists are most common on the Peaks and this area is the principal source of the island’s streams. In fact it is estimated that about one third of the stream flow is generated from an area of about 650 hectares around the Peaks (five percent of the island’s area). However, the most effective mist interceptors, the endemics, have been largely cleared from this small area and replaced by flax and grass. Neither of these plants are good mist interceptors because they do not allow air to move through their leaves. The replacement of the grass and flax in the Peaks area by efficient mist interceptors, be they endemics or other trees like the Norfolk Island pine, would increase precipitation. At present rainfall in this area Just exceeds evapotranspiration by about 10-20 percent. The excess all goes towards spring and stream flow. A ten percent increase in precipitation could cause stream flows to increase by as much as 50 percent.

So it seems likely that the destruction of St Helena’s endemic flora has significantly contributed to the severity of the effects of drought Future prosperity could well be linked to the future management of the island’s vegetation.

Laugh at funny Water humour - LOL

Credits:
{a} Marian Yon{b} Government of St Helena{c} Connect Saint Helena Ltd.{d} Diagram from the Article: Meeting St Helena’s Water Demands

Footnotes:
{1} The Run, 2016.{2} Amusingly, by the time the competition was judged, the rains had begun and the water situation was no longer critical.{3} We have seen this map attributed to Bellin, 1764, but we cannot accept this attribution because the Lines were established in 1706 and the Castle was rebuilt in 1708 but neither of these is shown. If this map were drawn in 1764 it was around 60 years out-of-date. It has also been attributed to Bellin with a different date - 1704 - which seems more likely.{4} Unfortunately if you look today (at the time of writing) someone has covered the blocks with graffiti. Graffiti is very unusual in St Helena and it seems nobody has a way of cleaning it off! This image was taken before the graffiti.{5} Though when Thomas Best had arrived in The Dragon in March 1614 he had expressed the view that Limon Valley’ has better water than Chapel Valley.{6} On 8th January 2005 the water taps in Longwood actually ran dry because the local distribution system did not have enough water to cover the demand from its customers.{7} There was also an Earthquake on 7th June 1756.{8} By 1911 83 owners of 135 Jamestown properties still owed the Government of St Helena a total of £3,379, which the Government of St Helena decided to write off.{9} Read more in ‘The First Dozen Years’ (of the 20th Century), by Ian Bruce.{10} Reproduced for educational non-commercial use only; all copyrights are acknowledged.{11} The four ‘Wirebird’ publications should not be confused.

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