Canterbury’s first century of water

Press, 24 December 1977, Page 15

Canterbury’s first century of water

Water races, the man-made canals that take the waters of the Southern Alps to

Canterbury’s flat farmland, will complete their first 100 years in a few days time;

and despite their wastefulness and the appeal of piped-water systems, they look

like staying for another century. DERRICK ROONEY looks at the origins of

a unique system, grounded in India, that has boosted Canterbury’s annual in

come by many millions of dollars.

Water — it is something city people take for granted, something that just comes out when the tap is turned on. But there are many people in Canterbury who may never have piped water laid on to their homes, to whom water is a luxury. On Tuesday, some of them will pass, perhaps without knowing it, the first century of the most precious Christmas present the farmers of inland Canterbury have ever had.

Just 100 years ago, two days after Christmas, 1877. the first of Canterbury’s unique public water-race systems was opened, in the Kowai Pass, inland from Sheffield. Today, the same system, enlarged and given new headworks, covers hundreds of miles and supplies water to perhaps hundreds of thousands of sheep and cattle in one of New Zealand’s biggest counties. Canterbury’s system of water races is a brilliantly simple and logical system of taking water to a large, dry, flat area backed by a mountain range drained by only three major rivers.

Water races are not, as many city dwellers believe. for irrigation. Nor are they ditches. They are a source, in many places the only source, of water for stock and sometimes — despite the teeming millions of organisms they must harbour — for human consumption. Water races have turned hundreds of thousands of worthless acres into some of the finest sheep and cattle country in New Zealand. Their return to the community is impossible of calculation, but must run into many millions of dollars every year in wool and meat. The Malvern water race, earliest and perhaps the most important public water-race system in New Zealand, owes its origins to the foresight and in* itiative of James de Renzie Brett, one of the most remarkable and colourful of Canterbury’s settlers. At various stages of his career he was a general in the Middle Bast, a colonel in the Indian Army, one of the principal figures in the suppression of the Indian Mutiny, a

Canterbury landowner, and a legislator.

When he arrived in New Zealand, in the late 1860 s, agriculture in the province was undergoing a crisis.

The good land alongside the permanent watercourses had been taken up; plenty of land was still there for the taking elsewhere, but for one thing: water. A farm without a stream was a poor farm.

All water for farms that did not adjoin the riverbeds had to be carted in drays, and on Monday mornings long lines of drays carrying 400-gallon tanks waited at every watercourse to which there was road access. Some of the larger farmers kept special threehorse teams that went to the rivers every day for water.

When the Courtenay Road Board was formed in 1865, its first task was to make dray tracks into the Waimakariri River. There was really no alternative. Wells were possible in many areas, but not everywhere (despite the abundance of water below many parts of the Canterbury plains, there are places where it is possible to go down 400 feet without finding water). Some of the larger fanners had wells, including Colonel Brett (his well at Kirwee went down 200 feet), but the cost put them well beyond the reach of the average squatter. So a large area stretching between the Waimakariri and the Hawkins rivers, frozen in winter and blasted and baked by nor’westers in summer, was useless as grazing land. Until Colonel Brett’s scheme, that is.

Colonel James de Renzie Brett was a soldier, though not necessarily a simple one, with memories of the primitive irrigation systems of India, and he presumably saw the watering of the arid Canterbury plains as a simple exercise in logistics. If this wild and arid country were subjected to proper military discipline, it would be made to blossom. So he looked at the Waimakariri River as a .fountainhead, and singlemindedly set about making his vision a reality.

He went about it realistically, too; he didn’t just

talk about it, but spent some of his own money to get facts and figures, and to establish whether the scheme was feasible, before he took it to the Provincial Council;

At the 1871 meeting of the council he moved that a sum of money be added to the estimates to pay for a survey of the practicability of diverting water from the Waimakariri over the plains and as far as Rolleston.

He got support, unexpectedly, from Sir John Hall, of Christchurch, one of the owners of Terrace Station — one of the earliest Canterbury runs, stretching around the foothills between the Hororata and Rakaia rivers. These two, both strong characters, were often at loggerheads, and were later the principals in a great row, which Sir John won, over the administration of the provincial police. But both were big enough men to realise that water was more important than politics.

Sir John told the council that “the benefits accruing from such a scheme will be inestimable, and will lead to the profitable occupation of large tracts of land that are almost worthless in consequence of the entire absence of water.” So the Provincial Council hired C. E. Fooks, who had earlier built a small, private water-race system on Westerfield station in Mid-Canterbury, between Ashburton and Hinds, to report on the possibility of irrigating Malvern.

His first conclusion must have been a bitter pill for the colonel: the Waimakariri, Fooks reported, would have to be eliminated from the likely sources because of the difficulty of raising the water to the top of the terraces. Later, in the 1890 s, this conclusion was justified when the Selwyn County Council spent thousands of pounds on a complicated scheme to take water from an intake at the gorge bridge through a tunnel and system of flumes to an open race which ran alongside the Coal Track Road (later renamed West Coast Road, and now known as Old West Coast Road) to join the main race at Kimberley. This race was never

satisfactory, and when the fluming collapsed at Deans Gully in 1908 it was abandoned. Only in the last 20 years have this race and headworks been redesigned, re-opened, and assumed major importance: ultimate justification of the colonel’s vision.

Fooks, having rejected the Waimakariri, turned his attention to the Hawkins River and the Kowai River. Two sites on the Hawkins were considered first, and rejected because in summer the flow was too low; a mere six cusecs. Fooks settled finally on a site in the Kowai River, 60 chains above the ford on the West Coast Road. The distance to Rolleston was 321 miles, the fall an average of 40ft in the mile, and there was a plentiful flow of water. But it took five years, two more reports by different engineers, a lot of political wrangling, and an act of Parliament before the Provincial Council could go ahead with the scheme.

The proposals finally adopted were made by G. Thornton, the assistant provincial engineer. The river was to be raised by a dam four miles above Kowai Pass, and the water taken by tunnel through the south bank to an open channel, heading off to the plains.

The council allocated £22,000 for the scheme, but in the event it did not need this much; the successful tenderers, Fraser Brothers (fresh from South Canterbury, where they had just built a canal to take a water supply to Timaru from the Pareora River), submitted a price of £13,000. For that sum, the council got a dam 300 ft long, 12ft thick at the base and

3ft at the top, and rising 7ft above the normal level of the river. At its back the dam was strengthened by two counterforts 4ft wide, 17ft high, and 15ft through at the bottom. The whole structure was based on solid rock. At the south end of the dam the riverbank was 40ft high, and because of this a suggestion of an open cutting instead of a tunnel was rejected: it would have made the whole system insecure.

The tunnel in its final form was 3ft 6in wide and sft 6in high, with internal walls made of two courses o f bricks, vertical sidewalls and a circular head. Sluice gates controlled the flow of water into the tunnel. The bricks — half a million of them — were made on the site with clay from the excavations, and fired in primitive kilns fuelled with Kowai Pass coal — an early example of Kiwi initiative.

With the first flood came the first snag, the problem that has caused headaches for all engineers who have designed waterworks for Canterbury rivers: shingle. The reservoir created by the Kowai dam disappeared with the first spring flood, when the whole basin in front of the dam filled with shingle. In this case it mattered little, for the flow down the river was ample, and the only effect was to raise the normal water level to the tunnel mouth.

The shingle problem also bedevilled the men working on the dam during construction. In one flood, in December, 1876, four months after work started, so much shingle was brought down that 100 men had to be

brought in from Christchurch, or wherever they could be found, to protect the work in progress.

But in due course the headworks and first two miles of race were completed; and officially opened on December 27, 1877, at a grand ceremony for which a large number of people travelled by dray, waggon, or horseback from all parts of the Selwyn county (in those days Selwyn county stretched from Riccarton to Arthur’s Pass and down to Rakaia) to hear flowery speeches from Canterbury’s notables. These included Mr Rolleston, of avenue fame, and Colonel Brett himself, who really pulled out the stops. The opening of the waterworks was one of the greatest and most important undertakings New Zealand could boast of, he said. “The water which .they are now bringing through the plains will be as pleasant and far more useful than the milk and honey flowing through the land of Syria.” Curiously, although the rival paper, the “Lyttleton Times,” reported the opening effusively and in great derail, the whole project got scant attention from “The Press,” which in those days was by no means rurally oriented, and did not consider the opening worth mentioning in its columns. “The Press” contented itself with a couple of sentences three days beforehand, announcing that it understood that the first trials of the Malvern water race would be held “on Thursday next.” And even when it reported Colonel Brett’s death 12 years later, “The Press” ignored his most important achievement in this country.

If the early history of the Plains water supply proves anything, it is that even in those days red tape had no less glue on it than it has today.

It took nine months of negotiations, after the opening, before the Selwyn County Council “reluctantly” agreed to take charge of the completion of the race, and the Provincial Government formally relinquished control in September, 1878.

The county council appointed one John Webster as engineer, at a salary set at 5 per cent of the money spent, and engaged Frasers, once again, and one David Jebson as contractors.

A t Sheffield the smoothly-flowing project has its first brush with bureaucracy: the railway station had been built on the land reserved for the water race, and there was nowhere for the water to go. Various schemes were suggested, including a diversion around Little Racecourse Hill, before the Railways Department eventually agreed, without, a great deal of grace, to a face-saving compromise: it would build a concrete culvert to take the water past the railway station. So the race still describes a dogleg at Sheffield today.

By 1880, the race had reached Waddington, where it branched, one part going to Kirwee and the other to Darfield — today a bustling county seat, then just a one-dog town, barely a dot on the map, but interesting as the site of one early example of multiple use of race water: a flour mill, long disappeared, once straddled the main race through the township.

Brett and other residents with holdings at Aylesbury financed a private branch scheme to take water to Aylesbury, using a natural gully from Kirwee. Later this was taken over by the council. After that, progress was rapid, and by 1883 Colonel Brett .had seen his dream come true: water from the foothills of the Southern Alps, converted by man for his own use, was coursing across the Canterbury Plains not only to Rolleston but to Burnham and Norwood as well.

That the Malvern waterrace system, wjen completed, was so successful that its network of channels and mini-canals has survived practically unaltered to the present says a lot for the ingenuity of the pioneers, for there is more to designing a practical water-race system than just scratching a channel across the landscape.

Flow rates, weed growth, oxidation, water depth, percolation, eutrophication, and erosion are some of the problems that must be solved. Some of them, like erosion and flow rates, are interdependent. If the velocity of the water is too high, there will be scouring. This was a headache in the early days in the few miles below the headworks, where the fall is about 100 ft in the mile. The original designers made a series of “weirs” to control the flow. As far as Waddington, these were made of concrete. Below that, they were of kauri boards, and many of them survive today, with the kauri timber still sound after a century of immersion.

From Kirwee, Colonel