Roding Valley waterworks

Since its official opening on the 30th October 1941, the Roding waterworks scheme has supplied water to both Nelson City and Richmond. The scheme consists of a low dam and a 2.68 kilometre pipeline through the hill to Marsden Valley. The dam continues to supply about one third of the city's annual water needs.   In 1884, two mining engineers who inspected the Aniseed Valley copper mines, W. H. Hoby and G. B. Stewart, ambitiously proposed a branch railway from Stoke with a tunnel under the Barnicoat Range as a means of transport to and from the mines. Stewart argued that the tunnel, estimated to cost 3000 pounds, could also be used to bring water from the Roding to the city. His idea was ahead of its time by some 50 years.

Roding River Camp, Aniseed Valley Copper Smelter, Nelson Provincial Museum,  F G Gibbs Collection, half 330
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Building the Roding Scheme

The Aniseed Valley Road was upgraded to get materials and labour to the site, and work began on the tunnel. A workers' camp was set up, consisting of a cookhouse, huts and hot showers. Men who lived outside the valley were picked up by Jim Troup each morning in his Lincoln car, while another worker, Tracey Stratford, supplied a billy of milk each day. Tunnel excavation commenced at both ends and was carried out with explosives and pick and shovel by the light of acetylene lamps. Men worked round-the-clock in two 12-hour shifts. Ponies were hired from farmer Roy Johnston, to cart spoil which was tipped into the river. Resource consent would not be granted today for such casual silting of excellent fishing holes!

One memorable incident in 1939 was heard as far away as Wakefield. A tunneller's cigarette butt started a fire which spread to the powder house. According to Ruth Whittaker in her book 'Pioneers of Aniseed Valley', the force from the resulting explosion blew the stable off the horse and the animal continued to munch its chaff.

At the Marsden Valley end of the tunnel, one of the patients from Ngawhatu Psychiatric Hospital  befriended the workers when they emerged every lunchtime into daylight. A story is told that a new worker on the job saw the lunchtime guest and said, "I know where you come from, you're one of those mad beggars from over the hill." "Ah yes", replied the wise patient, "But I don't work."

Dam in 1980, Nelson City Council
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For the dam part of the scheme, land was purchased by the Public Works from Roy Johnston. A diversion tunnel was constructed to take the river away from the site, and the base for the dam wall excavated into 4ft of solid rock (bedded sandstone and mudstone). No explosives were allowed to be used due the risk of cracking and hence weakening the rock.

In 1972 the dam was raised 1.5 metres which had the dual effect of increasing storage capacity and increasing the maximum flow to 24,000 cubic metres per day. Two smaller intakes helped raise levels during periods of low flow, but have not been used since completion of the Maitai Dam in 1987.  

The caretakers

A caretaker's home was built in 1941, by the Nelson City Council on land leased from the Crown. Various caretakers have lived there over the years, inspecting the dam daily and cleaning the screens and inspecting the tunnel weekly for cracks and leaks. In the early days, children were home-schooled. Today's road improvements have lessened isolation.

Note on the Nelson city water supply

The city's first supply came from a weir and pipeline on the Brook Stream, in 1867, and later expanded to the Brook dam in 1904. Leaking problems and an increasing demand for water plagued the scheme throughout its life (1904 - 2000). The Roding scheme was completed in 1941, but the city continued to grow. An intake on the Maitai River supplied the city by 1963 and an earth dam was completed in 1987. The Nelson Water Treatment Plant, sited near the Tantragee Saddle, opened in 2004 and treats water from both the Maitai and Roding Rivers.

More information about the Roding Dam

Scheme Designer: J G Littlejohn, City Engineer
Consulting Engineer: F S Williams
Contractor: Humes Pipe Company
Supervisor of Construction: C I Kidson
Tunnel Sub-Contract: Downer Brothers Ltd
Tunnel Supervisor: W Taylor
Tunnel Specifications: length - 2.68 kms; height - 1.95 metres; width - 1.2 metres

This material was produced for the Nelson City Council heritage Panel at Aniseed Valley, 2008 (updated 2022)

Sources used in this story

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